Sealing of flat-panel device

Information

  • Patent Grant
  • 6722937
  • Patent Number
    6,722,937
  • Date Filed
    Monday, July 31, 2000
    23 years ago
  • Date Issued
    Tuesday, April 20, 2004
    20 years ago
Abstract
A flat-panel display is hermetically sealed by a process in which a first plate structure (30) is positioned generally opposite a second plate structure (32) such that sealing material (34) provided over the second plate structure lies between the plate structures. In a gravitational sealing technique, the first plate structure is positioned vertically below the second plate structure. The sealing material is heated so that it moves vertically downward under gravitational influence to meet the first plate structure and seal the plate structures together. In a global-heating gap-jumping technique, the plate structures and sealing material are globally heated to cause the sealing material to jump a gap between the sealing material and the first plate structure. When the first plate structure is positioned vertically above the second plate structure, the sealing material moves vertically upward to meet the first plate structure and close the gap.
Description




FIELD OF USE




This invention relates to techniques for sealing flat-panel devices such as flat-panel displays.




BACKGROUND ART




A flat-panel device typically contains two generally flat plates positioned opposite each other. A flat-panel display is a type of flat-panel device utilized for displaying information. The two plates in a flat-panel display are commonly termed the faceplate and backplate. The faceplate, which provides the display's viewing surface, is part of a faceplate structure containing one or more layers or regions formed over the faceplate. The backplate is similarly part of a backplate structure containing one or more layers or regions formed over the backplate. The two plate structures are sealed together, typically through an outer wall, to form a sealed enclosure.




A flat-panel display utilizes mechanisms such as cathode rays (electrons), plasmas, and liquid crystals to display information on the faceplate. Flat-panel displays which employ these three mechanisms are generally referred to as cathode-ray tube (“CRT”) displays, plasma displays, and liquid-crystal displays. The constituency and arrangement of the display's two plate structures depend on the type of mechanism utilized to display information on the faceplate.




In a flat-panel CRT display, electron-emissive elements are typically provided over the backplate. Light-emissive elements are situated over the faceplate. When the electron-emissive elements are appropriately excited, they emit electrons that strike the light-emissive elements causing them to emit light visible on the faceplate. By appropriately controlling the electron flow from the backplate structure to the faceplate structure, a suitable image is displayed on the faceplate. The electron flow needs to occur in a highly evacuated environment for the CRT display to operate properly and to avoid rapid degradation in performance. It is thus critical to hermetically seal a flat-panel CRT display.





FIGS. 1



a


-


1




c


(collectively “FIG.


1


”) illustrate a conventional technique for sealing a flat-panel CRT display of the field-emission type, often referred to simply as a field-emission display (“FED”). The components of the FED being sealed in

FIG. 1

include backplate structure


10


, faceplate structure


12


, outer wall


14


, and multiple spacer walls


16


situated between plates structures


10


and


12


for preventing outside forces, such as air pressure, from collapsing or otherwise damaging the FED.




At the point shown in

FIG. 1



a


, spacer walls


16


are mounted on faceplate structure


12


, and outer wall


14


is connected to faceplate structure


12


through frit (sealing glass)


18


provided along the faceplate edge of outer wall


14


. Frit


20


is situated along the backplate edge of outer wall


14


. A pump-out tube (not shown) is typically affixed to backplate structure


10


for later evacuating the sealed FED. Prior to the sealing operation, backplate structure


10


is physically separate from the composite structure formed with faceplate structure


12


, outer wall


14


, and spacer walls


16


.




Structures


10


and


12


/


14


/


16


are placed in an alignment system


22


, aligned to each other, and brought into physical contact along frit


20


as shown in

FIG. 1



b


. Alignment system


22


is located in, or is placed in, an oven


24


. After being aligned and brought into contact along frit


20


, structures


10


and


12


/


14


/


16


are slowly heated in air to a sealing temperature ranging from 450° C. to greater than 600° C. Frit


20


melts. The FED is subsequently cooled down to room temperature. As frit


20


cools down, it seals composite structure


12


/


14


/


16


to backplate structure


10


.




At or near the end of the cooldown, the FED is removed from alignment system


22


and oven


24


. The pressure in the interior of the FED is brought down to the desired vacuum level by removing air through the pump-out tube. The pump-out tube is then closed. Aside from the pump-out tube,

FIG. 1



c


depicts the final hermetically sealed FED.




During the sealing operation, the upper edge of outer wall


14


, including frit


18


and frit


20


, is initially slightly higher than the upper edges of spacer walls


16


. As frit


20


melts, it compresses somewhat in the direction, commonly referred to as the z direction, perpendicular to plate structures


10


and


12


until spacer walls


16


meet backplate structure


10


. Frit


18


may also compress in the z direction during the sealing operation. Hence, plates structures


10


and


12


move relative to each other in the z direction as the FED is being sealed. A similar type of z motion would occur if a rectangular ring of frit were substituted for composite outer wall


14


/


18


/


20


.




A side effect of motion in the z direction is that faceplate structure


12


sometimes moves relative to backplate structure


10


in a direction perpendicular to the z direction. Hence, the alignment of plate structures


10


and


12


is sometimes degraded as a result of the z motion of structures


10


and


12


. Due primarily to differences in the coefficients of thermal expansion of plate structures


10


and


12


and alignment system


22


, the degradation in alignment can occur despite the use of system


22


. It would be desirable to hermetically seal a flat-panel display, especially a flat-panel CRT display such as an FED, according to a technique that largely avoids z motion between the displays two plate structures and thus avoids alignment degradation due to such z motion.




As frit


20


melts and compresses in the z direction, frit


20


normally spreads laterally over faceplate structure


12


. The lateral area of structure


12


can be increased in the peripheral area outside the viewing area to allow for frit


20


to spread laterally. However, it is typically desirable that the peripheral display area be as small a fraction as possible of the total lateral area of structure


12


. Accordingly, increasing the lateral area of structure


12


to allow room for frit


20


to spread is disadvantageous.




In addition, frit


20


may occasionally spread laterally beyond the normal area allocated for the spreading of frit


20


and damage components of the FED. A similar disadvantage would occur if composite outer wall


14


/


18


/


20


were replaced with a ring, again rectangular, of frit. In sealing two plate structures of a flat-panel display, especially a flat-panel CRT display such as an FED, together through a sealing structure, it would be desirable to have a technique for suitably restricting lateral spreading of the sealing material in the sealing structure.




PCT Patent Publication WO 98/26440 discloses a local-energy gap-jumping technique for sealing the backplate structure and faceplate structure of a flat-panel display. A rectangular frame of sealing material, typically frit, is sealed to the faceplate structure. The sealing frame laterally surrounds a group of spacer walls that extend further away from the faceplate structure than does the sealing frame. The backplate structure is placed vertically above the faceplate structure so that the sealing frame and spacer walls are situated between the two plate structures. The backplate structure lies directly on the spacer walls. Because the spacer walls are taller than the sealing frame at this point, a gap is present between the backplate structure and the sealing frame.




The two plate structures in PCT Patent Publication WO 98/26440 are held in a desired alignment using a suitable tacking mechanism. Energy is then transferred locally to portions of the sealing frame close to the backplate structure. The local energy, typically light energy provided from a laser or focused lamp, causes the sealing material to jump the backplate-structure-to-sealing-frame gap and hermetically seal the plate structures together.




By using spacer walls that are initially taller than the sealing frame, the sealing technique of PCT Patent Publication WO 98/26440 largely avoids undesired z motion during the sealing operation. However, utilization of a laser, focused lamp, or other local-energy producing mechanism to direct energy locally onto the sealing frame can sometimes be relatively time-consuming and thus unduly expensive. It would be desirable to have a technique that can be implemented rapidly, and relatively inexpensively, to seal a flat-panel display such as an FED.




GENERAL DISCLOSURE OF THE INVENTION




The present invention furnishes techniques for sealing a flat-panel device so as to achieve a hermetic seal while avoiding the above-mentioned disadvantages of the prior art. The sealing techniques of the invention are especially suitable for sealing a flat-panel CRT display, such as an FED, in which the interior of the display needs to be at a high vacuum during display operation. Nonetheless, each of the present sealing techniques can be applied to a display which requires a strong seal even though the display's interior may not be at a high vacuum during display operation.




In one aspect of the invention, sealing of first and second plate structures of a flat-panel device to each other is performed under the influence of gravity. More particularly, sealing material is provided in a specified pattern over the second plate structure. The first plate structure is positioned vertically below the second plate structure so that the sealing material lies between the two plate structures. As used here in describing gravitational sealing of two plate structures, the term “vertically” means vertically relative to the body, such as the earth, which provides the gravitation. The sealing material is then heated so that it moves downward under gravitational influence to contact the first plate structure and seal the plate structures together.




The plate structures are preferably maintained in a largely fixed positional relationship to each other during the heating step. For instance, the positioning of the first plate structure below the second plate structure is preferably conducted in such a way that the plate structures are spaced vertically apart from each other in largely a fixed manner. That is, the spacing between the plate structures along any vertical line through the plate structures is approximately constant. This positional relationship is then maintained during the heating step using, for example, an intermediate mechanism situated between the plate structures.




Importantly, by maintaining the plate structures in largely a fixed positional relationship to each other during the heating step, there is a essentially no z motion of one of the plate structures relative to the other during the heating step. Inasmuch as such z motion during the sealing of a pair of plate structures to each other often causes degradation in the alignment of the plate structures to each other, sealing the first and second plate structures together under the influence of gravity with the plate structures held in largely a fixed positional relationship to each other so as to avoid such z motion also avoids associated alignment degradation.




The heating step during the gravitational sealing operation preferably entails globally heating the sealing material and the two plate structures. The term “global” or “globally” as used here in describing a heating operation performed on parts of a device means that the heat is applied in a generally non-selective manner to the parts of the device. A global heating operation is thus basically the converse of a local heating operation in which energy is directed selectively to certain material largely intended to receive the energy without being significantly directed to nearby material not intended to receive the energy. Global heating is typically less time-consuming, and thus less expensive, than local heating. As a result, using global heating to perform the heating step of the present gravitational sealing operation helps keep the sealing cost down.




In another aspect of the invention, one or more restricting structures are utilized to limit the area where first and second plate structures of a flat-panel device are sealed to each other. The seal-restricting structure or structures thereby prevent the sealing material from spreading to sensitive device areas and degrading the device.




Specifically, one or two seal-restricting structures are provided over the first plate structure. Sealing material is provided in a specified pattern over the second plate structure. The plate structures are then positioned generally opposite each other so that the sealing material and the restricting structure or structures lie between the plate structures. If only one restricting structure is provided over the first plate structure, the sealing material is situated opposite a location close to the restricting structure. When two restricting structures are provided over the first plate structure, the sealing material is situated opposite a location between the restricting structures.




The sealing material is heated to seal the plate structures together. If one restricting structure is provided over the first plate structure, the sealing material contacts the first plate structure close to that restricting structure. The restricting structure largely prevents the sealing material from spreading laterally over the restricting structures and contacting the first plate structure laterally beyond the restricting structure. When two restricting structures are placed over the second plate structure, the sealing material contacts the first plate structure between the restricting structures. The two restricting structures then largely prevent the sealing material from spreading laterally over the restricting structure and contacting the first plate structure laterally beyond one or both of the restricting structures. In either case, use of the restricting structure or structures typically prevents the sealing material from spreading laterally in such a manner as to degrade the flat-panel device. Also, the lateral area of the flat-panel device need not be significantly increased to allow for lateral spreading of the sealing material.




In a further aspect of the invention, first and second plate structures of a flat-panel device are sealed together according to a global-heating gap-jumping technique. In particular, sealing material is again provided in a specified pattern over the second plate structure. The two plate structures are then positioned opposite each other so that the sealing material lies between the plate structures. The positioning step is done in such a way that a gap separates the first plate structure from the sealing material provided over the second plate structure.




The first plate structure is preferably positioned vertically above the second plate structure. Similar to what was said above about the meaning of the term “vertically” in connection with the gravitational sealing technique of the invention, the term “vertically” as used in connection with the present global-heating gap-jumping technique means vertically relative to the underlying major gravitational body above which the global-heating gap-jumping technique is performed. With this in mind, the preferred orientation of the first plate structure above the second plate structure in the global-heating gap-jumping technique is opposite to the orientation in which the plate structures are arranged during the heating step of the gravitational sealing technique.




The sealing material and plate structures in the present global-heating gap-jumping technique are then globally heated to cause the sealing material to bridge the gap between the plate structures and seal them together. In the preferred case where the first plate structure is positioned vertically above the second plate structure, the sealing material provided over the second plate structure moves vertically upward to jump the gap. By using global heating to produce gap jumping, the cost of the sealing operation can be kept relatively low.




The present gravitational sealing technique can be performed with one or two seal-restricting structures. The same applies to the global-heating gap-jumping sealing technique of the invention. By maintaining the plate structures in largely a fixed positional relationship to each other during the heating step, the resultant sealing technique achieves both the advantages of using one or two seal-restricting structures and the advantages of the gravitational or global-heating gap-jumping technique. That is, device alignment degradation caused by z motion during the sealing operation is largely avoided, the sealing material is largely prevented from spreading over undesirable device areas and damaging sensitive device elements, and the device's lateral area need not be significantly increased to accommodate spreading of the sealing material.




In short, use of the present sealing techniques enables a flat-panel device to be hermetically sealed in a manner that avoids critical degradation problems. The sealing operation can be performed in a highly cost-efficient manner. The invention thereby provides a substantial advance over the prior art.











BRIEF DESCRIPTION OF THE DRAWINGS





FIGS. 1



a


-


1




c


are cross-sectional side views representing steps in a conventional process for sealing a flat-panel CRT display.





FIGS. 2



a


-


2




i


are cross-sectional side views representing steps in a process the utilizes gravity in accordance with the invention for sealing a flat-panel display.





FIG. 3

is a layout view of the faceplate structure in

FIG. 2



a


. The cross section of

FIG. 2



a


is taken along plane


2




a





2




a


in FIG.


3


. The layout of

FIG. 3

appears as viewed from plane


3





3


in

FIG. 2



a.







FIG. 4

is a cross-sectional layout view of the faceplate structure, outer wall, and spacer walls in

FIG. 2



d


. The cross section of

FIG. 2



d


is taken along plane


2




d





2




d


in FIG.


4


. The cross section of

FIG. 4

is taken along plane


4





4


in

FIG. 2



d.







FIG. 5

is a layout view of the backplate structure as it appears before being brought into contact with the spacer walls and tacking structures in

FIG. 2



f.







FIG. 6

is a cross-sectional side view of a variation of the faceplate structure, outer wall, and spacer walls in

FIG. 2



d.







FIGS. 7



a


-


7




d


are cross-sectional side views representing steps in part of a process for sealing a flat-panel display utilizing seal-restricting structures according to the invention. The process of

FIGS. 7



a


-


7




d


begins with the steps of

FIGS. 2



a


-


2




e.







FIG. 8

is a layout view of the backplate structure as it appears before being brought into contact with the spacer walls and tacking structures in

FIG. 7



a.







FIG. 9

is a cross-sectional side view of a variation of the faceplate structure, outer wall, and spacer walls in

FIG. 7



b.







FIGS. 10



a


-


10




i


are cross-sectional side views representing steps in another process for sealing a flat-panel display utilizing seal-restricting structures according to the invention.





FIG. 11

is a layout view of the faceplate structure in

FIG. 10



a


. The cross section of

FIG. 10



a


is taken along plane


10




a





10




a


in FIG.


11


. The layout of

FIG. 11

appears as viewed from plane


11





11


in

FIG. 10



a.







FIG. 12

is a cross-sectional layout view of the faceplate structure, outer wall, and spacer walls in

FIG. 10



d


. The cross section of

FIG. 10



d


is taken along plane


10




d





10




d


in FIG.


12


. The cross section of

FIG. 12

is taken along plane


12





12


in

FIG. 10



d.







FIGS. 13



a


-


13




c


are cross-sectional side views representing steps in part of a process for sealing a flat-panel device using a global-heating gap-jumping technique according to the invention. The process of

FIGS. 13



a


-


13




c


begins with the steps of

FIGS. 2



a


-


2




f.







FIGS. 14



a


-


14




c


are cross-sectional side views representing steps in part of a process for sealing a flat-panel display using a global-heating gap-jumping technique and seal-restricting structures according to the invention. The process of

FIGS. 14



a


-


14




c


begins with the steps of

FIGS. 2



a


-


2




e


and


7




a.







FIGS. 15



a


-


15




c


are cross-sectional side views representing steps in part of another process for sealing a flat-panel display using a global-heating gap-jumping technique and seal-restricting structures according to the invention. The process of

FIGS. 15



a


-


15




c


begins with the steps of

FIGS. 10



a


-


10




f.













Like reference symbols are employed in the drawings and in the description of the preferred embodiments to represent the same, or very similar, item or items.




DESCRIPTION OF THE PREFERRED EMBODIMENTS




General Considerations




A flat-panel display sealed according to the present invention has two plate structures referred to as the backplate structure and the faceplate structure. As used here, the “exterior” surface of the faceplate structure is the surface on which the display's image is visible to a viewer. The opposite side of the faceplate structure is referred to as its “interior” surface even though part of the interior surface of the faceplate structure is normally outside the enclosure formed by sealing the faceplate structure to the backplate structure through an outer wall. Likewise, the surface of the backplate structure situated opposite the interior surface of the faceplate structure is referred to as the “interior” surface of the backplate structure even though part of the interior surface of the backplate structure is normally outside the display's sealed enclosure. The side of the backplate structure opposite to its interior surface is referred to as the “exterior” surface of the backplate structure.




Gravitational Sealing





FIGS. 2



a


-


2




i


(collectively “FIG.


2


”) illustrate a general gravity-based technique for hermetically sealing a flat-panel display according to the invention. The components of the flat-panel display sealed according to the process of

FIG. 2

are a backplate structure


30


, a faceplate structure


32


, an outer wall


34


, and an internal spacer system consisting of a group of spacer walls


36


. Backplate structure


30


, faceplate structure


32


, outer wall


34


, and spacer walls


36


are fabricated separately.

FIG. 2



a


only depicts faceplate structure


32


.

FIG. 2



i


depicts all of components


30


,


32


,


34


, and


36


after plate structures


30


and


32


have been sealed together through outer wall


34


.




Backplate structure


30


and faceplate structure


32


are generally rectangular in shape. The internal constituency of plate structures


30


and


32


is not shown in the drawings. However, backplate structure


30


consists of a backplate and one or more layers or regions formed over the interior surface of the backplate. Faceplate structure


32


consists of a transparent faceplate and one or more layers or regions formed over the interior surface of the faceplate.




Outer wall


34


is arranged in a specified pattern, normally a rectangle as viewed perpendicular to plate structure


30


or


32


. More particularly, wall


34


normally consists of four sub-walls arranged in the desired rectangular pattern. Spacer walls


36


maintain a constant spacing between plate structures


30


and


32


in the sealed display, and enable the display to withstand external forces such as air pressure. The display sealing operation normally involves raising the components of the flat-panel display to elevated temperature. To reduce the likelihood of cracking the display, especially during cooldown to room temperature, outer wall


34


is typically chosen to consist of material having a coefficient of thermal expansion (“CTE”) that approximately matches the CTEs of the backplate and the faceplate.




A flat-panel display sealed according to the process of

FIG. 2

can be any of a number of different types of flat-panel displays such as CRT displays, plasma displays, vacuum fluorescent displays, liquid-crystal displays, and light-emitting diode displays. In flat-panel CRT displays of the field-emission type and in some flat-panel CRT displays of the thermionic-emission type, backplate structure


30


contains a two-dimensional array of rows and columns of electron-emissive regions situated over the backplate. Structure


30


is then an electron-emitting device.




Specifically, backplate structure


30


in a flat-panel field emission CRT display typically has a group of emitter electrodes that extend across the backplate in a row direction. A dielectric layer lies over the emitter electrodes. A row of the electron-emissive regions also overlie each emitter electrode. At each location for an electron-emissive region, a large number of openings, each occupied by an electron-emissive element, extend through the dielectric layer down to a corresponding one of the emitter electrodes.




A patterned gate layer is situated on the dielectric layer. Each electron-emissive element is exposed through a corresponding opening in the gate layer. A group of control electrodes, either created from the patterned gate layer or from a separate control-electrode layer that contacts the gate layer, extend over the dielectric layer in a column direction perpendicular to the row direction. Each control electrode extends along one column of the electron-emissive regions. The emission of electrons from the electron-emissive region at the intersection of each emitter electrode and each control electrode is controlled by applying appropriate voltages to the emitter and column electrodes.




Alternatively, the emitter electrodes can extend in the column direction while the control electrodes extend in the row direction. Although the row direction is typically the direction in which a line of the display's image is presented, the terms “row” and “column” are arbitrary and can be reversed in meaning.




Faceplate structure


32


in the field-emission display (again, “FED”) contains a two-dimensional array of light-emissive elements provided over the interior surface of the transparent faceplate. An anode is situated adjacent to the light-emissive elements in structure


32


. The anode may be positioned over the light-emissive elements. In that case, the anode typically consists of a thin layer of electrically conductive light-reflective material, such as aluminum, through which the emitted electrons can readily pass to strike the light-emissive elements. U.S. Pat. Nos. 5,424,605 and 5,477,105 describe examples of FEDs having faceplate structure


32


arranged in the preceding manner.




Alternatively, the anode in the FED can be formed with a thin layer of electrically conductive transparent material, such as indium tin oxide, located between the faceplate and the light-emissive elements. In either case, the anode is provided with a suitably high voltage that draws emitted electrons toward target light-emissive elements in faceplate structure


32


. As the electrons strike the light-emissive elements, they emit light visible on the exterior surface of the faceplate to form a desired image.




The thickness of outer wall


34


is normally 1-6 mm, typically 2.5-3.5 mm. Although the dimensions have been adjusted in

FIG. 2

to facilitate illustration of the components of the flat-panel display, the height of outer wall


34


is usually of the same order of magnitude as the outer wall thickness. For example, the outer wall height is normally 1-1.5 mm, typically 1.2 mm.




The four sub-walls of outer wall


34


can be formed individually and later joined to one another directly or through four comer pieces. The four sub-walls can also be a single piece of appropriately shaped material. Outer wall


34


normally consists of frit, such as Ferro


2004


frit combined with filler and a stain, arranged in a rectangular annulus. The frit in outer wall


34


normally melts at temperature of 300-600° C. The frit melting temperature is much less, typically 100° C. less, than the melting temperature of any of the materials of plate structures


30


and


32


and spacer walls


36


.




Spacer walls


36


typically extend in the row direction. Each pair of spacer walls


36


is normally separated by multiple rows of pixels. Spacer walls


36


typically consist primarily of material which is electrically insulating or highly electrically resistive (but still slightly electrically conductive). For simplicity, spacer walls


36


are illustrated in

FIG. 2

using shading for electrically insulating material. When the flat-panel display is an FED, one or more electrodes (not shown) are typically provided along one or both faces of each spacer wall


36


for controlling the electron flow from backplate structure


30


to faceplate structure


32


. Electrodes (likewise not shown) are typically also present along the edges of spacer walls


36


where they contact plate structures


30


and


32


.




The sealing process of

FIG. 2

is performed in the following manner starting with faceplate structure


32


in

FIG. 2



a


. Part of the interior surface of structure


32


forms a rectangular annular sealing area


32


S along which outer wall


34


is to be joined to structure


32


. Faceplate sealing area


32


S is indicated by dark line in FIG.


2


. This, however, is only for illustrative purposes. Except as described in the following two paragraphs, structure


32


typically does not have a feature that expressly identifies the location of sealing area


32


S. The rectangular shape of sealing area


32


S can be seen in

FIG. 3

which illustrates a layout view of structure


32


at the stage of

FIG. 2



a.






Faceplate sealing area


32


S may be of different surface energy than the two portions, identified by reference symbols


32


NI and


32


NO in

FIG. 3

, of the interior surface of faceplate structure


32


adjoining and extending respectively along the inside and outside of sealing area


32


S. If so, the surface energy of area


32


S is of such a nature as to promote bonding of area


32


S to the sealing material of outer wall


34


. This generally means that area


32


S is wettable by the wall sealing material. The surface energy of each of adjoining portions


32


NI and


32


NO is then of such a nature as to inhibit bonding of portions


32


NI and


32


NO to the sealing material of outer wall


34


. This generally means that non-sealing portions


32


NI and


32


NO are largely non-wettable by the wall sealing material compared to area


325


.




The surface energy difference between faceplate sealing area


32


S and each of non-sealing portions


32


NI and


32


NO can be achieved in various ways. For example, area


32


S or/and portions


32


NI and


32


NO can be treated with one or more appropriate chemical compounds that change the surface energy in the desired way. Material that yields the desired surface energy can be deposited to form area


32


S or/and non-sealing portions


32


NI and


32


NO. In that case, area


32


S may be visibly discernible. Examples of materials that can be deposited to provide area


32


S with a different surface energy than non-sealing portions


32


NI and


32


NO are (a) carbon, (b) organic compounds such as polyimide, photoresist, hydrocarbons, and fluorinated plastics, and (c) electrical insulators such as aluminum oxide, silicon oxide, and silicon nitride.




Outer wall


34


is placed in an oven


38


. See

FIG. 2



b


. Wall


34


lies on a suitable support (not shown) in a horizontal position in oven


38


. Faceplate structure


32


is placed in oven


38


and positioned on top of wall


34


with the interior surface of structure


32


facing downward so that sealing area


32


S is vertically aligned to wall


34


. The alignment is done with a suitable alignment system (not shown). Area


32


S normally contacts wall


34


when the positioning step is completed.




After the alignment is completed, faceplate structure


32


is sealed to outer wall


34


. The faceplate-structure-to-outer-wall seal can be done in any of a number of ways. Normally, the sealing of wall


34


to structure


32


is performed under non-vacuum conditions at a pressure close to room pressure (typically 1 atmosphere or 760 torr), usually in an environment of dry nitrogen or an inert gas such as argon. In a typical implementation, oven


38


is filled with dry nitrogen at a pressure of approximately 710 torr.




The faceplate-structure-to-outer-wall sealing operation typically entails appropriately heating outer wall


34


so as to cause wall


34


to soften. A thin portion of wall


34


along sealing area


32


S may melt. When area


32


S is of surface energy that promotes bonding of the sealing material of wall


34


to area


32


S while adjoining portions


32


NI and


32


NO are of surface energy that inhibits bonding of the wall sealing material to portions


32


NI and


32


NO, portions


32


NI and


32


NO inhibit the sealing material of wall


34


from spreading laterally beyond area


32


S.




Outer wall


34


is preferably sealed to faceplate structure


32


with a laser


40


after globally raising wall


34


and structure


32


to a bias temperature of 200-400° C., typically 340° C. The elevated temperature during the laser seal is employed to alleviate stress along the sealing interface and reduce the likelihood of cracking. Laser


40


produces a laser beam


42


which passes through a quartz window


38


W located along the top of oven


38


. Laser beam


42


passes through transparent material of faceplate structure


32


and impinges on outer wall


34


along sealing area


32


S. Beam


42


normally makes one pass along the length of sealing area


32


S. The light energy of beam


42


causes a thin portion of outer wall


34


along sealing area


32


S to be raised up to, or above, the melting temperature of outer wall


34


. The so-melted portion of wall


34


subsequently cools down to room temperature (typically 20-25° C.). During the cooldown, wall


34


becomes sealed to structure


32


along area


32


S.




During the faceplate-structure-to-outer-wall sealing operation, faceplate structure


32


and outer wall


34


can have different orientations than that described above and shown in

FIG. 2



b


where faceplate structure


32


is vertically on top of outer wall


34


. For instance, wall


34


can be vertically on top of structure


32


. In that case, laser


40


is typically situated vertically below oven


38


.




The faceplate-structure-to-outer-wall seal can alternatively be effected in a sealing oven by globally raising faceplate structure


32


and outer wall


34


to a suitable sealing temperature to produce the seal and then cooling composite structure


32


/


34


down to room temperature. Structure


32


is typically oriented horizontally in the sealing oven with one of components


32


and


34


positioned vertically on top of the other of components


32


and


34


. The faceplate-structure-to-outer-wall sealing temperature, typically in the vicinity of 300-600° C., equals or slightly exceeds the melting temperature of the frit in outer wall


34


, and therefore causes the frit to be in a molten state for a brief period of time. The faceplate-structure-to-outer-wall sealing temperature is sufficiently low to avoid melting, or otherwise damaging, any part of faceplate structure


32


.




After completing the faceplate-structure-to-outer-wall seal, resultant structure


32


/


34


is removed from oven


38


or other oven. Structure


32


/


34


is typically oriented so that outer wall


34


is vertically on top of faceplate structure


32


, e.g., by flipping structure


32


/


34


over if faceplate structure


32


was vertically on top of outer wall


34


during the faceplate-structure-to-outer-wall sealing operation. See

FIG. 2



c.






Spacer walls


36


are mounted on the interior surface of faceplate structure


32


inside outer wall


34


. See

FIG. 2



d


. Also see

FIG. 4

which presents a plan view of resultant structure


32


/


34


/


36


at the stage of

FIG. 2



d


. Spacer walls


36


are normally taller than outer wall


34


. In particular, spacer walls


36


extend further away, typically an average of at least 50 μm further away, from faceplate structure


32


than does outer wall


34


.




Although spacers walls


36


are normally mounted on faceplate structure


32


after the sealing of outer wall


34


to structure


32


is performed, spacer walls


36


can be mounted on structure


32


before the faceplate-structure-to-outer-wall seal. In that case, the faceplate-structure-to-outer-wall sealing temperature is sufficiently low to avoid melting, or otherwise damaging, walls


36


.




Backplate structure


30


is to be hermetically sealed to outer wall


34


of structure


32


/


34


/


36


along a rectangular annular sealing area


30


S of the interior surface of backplate structure


30


. The rectangular shape of backplate sealing area


30


S can be seen in

FIG. 5

which presents a layout view of structure


30


prior to being joined to outer wall


34


.




Similar to what said above about faceplate sealing area


32


S, backplate sealing area


30


S may be of different surface energy than the two portions, indicated by reference symbols


30


NI and


30


NO in

FIG. 5

, of the interior surface of backplate structure


32


adjoining and extending respectively along the inside and outside of sealing area


30


S. If so, the surface energy of area


30


S is of such a nature as to promote bonding of area


30


S to the corresponding sealing material of outer wall


34


. This generally means that area


30


S is wettable by the wall sealing material. The surface energy of each of adjoining backplate area portions


30


NI and


30


NO is then of such a nature as to inhibit bonding of portions


30


NI and


30


NO to the sealing material of outer wall


34


. Non-sealing area portions


30


NI and


30


NO are thus largely non-wettable by the wall sealing material compared to area


30


S.




The surface energy difference between backplate sealing area


30


S and each of non-sealing portions


30


NI and


30


NO can be attained in various ways. For instance, area


30


S or/and portions


30


NI and


30


NO can be chemically treated so as to change the surface energy in the desired way. Material that yields the desired surface energy can be deposited to form area


30


S or/and portions


30


NI and


30


NO. The above-mentioned carbon-containing materials and electrical insulators suitable for deposition to provide faceplate sealing area


32


S with a different surface energy than faceplate non-sealing portions


32


NI and


32


NO can also be deposited to provide backplate sealing area


30


S with a different surface energy than backplate non-sealing portions


30


NI and


30


NO.




A getter (not shown) may be situated either on the interior surface of backplate structure


30


within sealing area


30


S or on the interior surface of faceplate structure


32


within sealing area


32


S and thus within outer wall


34


at this point in the sealing process. As a result, the getter is located within the enclosure formed when backplate structure


30


is sealed to composite structure


32


/


34


/


36


. A pump-out tube (not shown) for evacuating the display is normally connected to the display, typically to backplate structure


30


. Alternatively, the getter may be partially or wholly situated in the pump-out tube.




As another alternative, the getter may be situated in a thin auxiliary compartment (not shown) later mounted over the exterior surface of the backplate and accessible to the enclosed region between plate structures


30


and


32


by way of one or more openings in the backplate and/or, depending on the configuration of the auxiliary compartment, one or more openings in outer wall


34


. In this case, the auxiliary compartment does not extend significantly above circuitry mounted over the exterior surface of the backplate for controlling display operation, and thus does not create any significant difficulties in handing the flat-panel display. When the getter is situated in such an auxiliary compartment, the pump-out tube is typically connected to the auxiliary compartment. Part of the getter may be situated in the pump-out tube.




The getter sorbs (collects) contaminant gases produced during, and subsequent to, the sealing of backplate structure


30


to composite structure


32


/


34


/


36


, including contaminant gases produced during operation of the hermetically sealed flat-panel display. The getter may consist of non-evaporable or/and evaporable gettering material. Techniques for activating non-evaporable getter material are described in U.S. Pat. No. 5,977,706, the contents of which are incorporated by reference herein.




Backplate structure


30


is now brought into contact with composite structure


32


/


34


/


36


in such a way that the interior surface of backplate structure


30


meets spacer walls


36


with backplate sealing area


30


S aligned to outer wall


34


. Because spacer walls


36


extend further away from faceplate structure


32


than does outer wall


34


, a gap separates outer wall


34


from backplate structure


30


along all, or largely all, of area


30


S.




In the course of aligning backplate structure


30


to composite structure


32


/


34


/


36


, a tacking operation is normally performed to hold backplate structure


30


in a fixed positional relationship to faceplate structure


32


and thus in a fixed positional relationship to structure


32


/


34


/


36


. The tacking operation broadly entails rigidly coupling plate structures


30


and


32


together through a suitable intermediate mechanism at multiple locations spaced laterally apart along structures


30


and


32


. The alignment and tacking operations can be done in various ways.

FIGS. 2



e


and


2




f


illustrate one way for implementing the alignment and tacking operations.




In the example of

FIGS. 2



e


and


2




f


, faceplate structure


32


initially extends roughly horizontal with its interior surface pointing upward. See

FIG. 2



e


. A tacking system consisting of a group of laterally separated tack structures


44


is provided on the interior surface of faceplate structure


32


outside outer wall


34


. Each tack structure


44


consists of a main tack body


44


M and a pair of bonding pieces


44


F and


44


B provided respectively on the bottom and top surfaces of main tack body


44


M. Bonding pieces


44


F and


44


B typically consist of suitable glue or other adhesive. For instance, bonding pieces


44


F and


44


B may consist of glue that cures when appropriately subjected to ultraviolet (“UV”) light or heat provided, e.g., by visible or/and infrared (“IR”) light. Piece


44


F of each tack structure


44


is situated between the interior surface of faceplate structure


32


and tack body


44


M for that tack structure


44


. Tack structures


44


typically extend approximately the same distance away from, i.e., above in the example of

FIG. 2



e


, faceplate structure


32


as do spacer walls


36


.




Backplate structure


30


is placed on top of composite structure


32


/


34


/


36


with the interior surface of backplate structure


30


facing downward so that sealing area


30


S is vertically aligned to outer wall


34


. See

FIG. 2



f


. The alignment is done with a suitable alignment system (not shown). In addition to contacting spacer walls


36


, the interior surface of structure


30


contacts bonding pieces


44


B of tack structures


44


. The alignment is normally done optically in a non-vacuum environment, normally at room pressure, with alignment marks provided on plate structures


30


and


32


. Specifically, backplate structure


30


is optically aligned to faceplate structure


32


.




In aligning backplate structure


30


to composite structure


32


/


34


/


36


, various techniques may be employed to ensure that spacer walls


36


stay in fixed locations relative to backplate structure


30


. For example, walls


36


may go into shallow grooves (not shown) provided along the interior surface of structure


30


. The grooves may extend below the general plane of the interior surface of structure


30


or may be provided in structures extending above the general plane of the interior surface of structure


30


. Walls


36


may have feet attached to structure


30


.





FIG. 2



f


presents an example in which bonding pieces


44


F and


44


B consist of adhesive, such as UV-curable or thermally curable glue, that provides strong bonding upon being subjected to suitable radiation. For this purpose, composite structure


32


/


34


/


36


, including tack structures


44


, lies between a pair of lasers


46


and


48


in the alignment system. Laser


46


overlies structure


32


/


34


/


36


. Laser


48


underlies structure


32


/


34


/


36


. Lasers


46


and


48


respectively provide laser beams


50


and


52


which respectively impinge downward and upward on structure


32


/


34


/


36


at the locations for tack structures


44


. When bonding pieces


44


F and


44


B consist of UV-curable glue, laser beams


50


and


52


consist of light at one or more appropriate UV wavelengths. Similarly, laser beams


50


and


52


consist of visible or/and IR light when pieces


44


F and


44


B are formed with thermally curable glue.




Backplate structure


30


is transparent, or largely transparent, to light (including UV and/or IR light) at the locations above tack structures


44


. To the extent that structure


30


may have opaque regions, e.g., metallic electrodes, directly above tack structures


44


, these opaque regions are sufficiently narrow that they do not significantly affect the passage of light through structure


30


. Accordingly, laser beams


50


and


52


respectively pass through transparent material of plate structures


30


and


32


and impinge respectively on bonding pieces


44


B and


44


F, curing them so that they chemically and/or physically interact with structures


30


and


32


. As a result, pieces


44


B and


44


F securely join tack structures


44


to plate structures


30


and


32


. Tack structures


44


then cooperate with spacer walls


36


in causing plate structures


30


and


32


to be spaced apart from each other in a largely fixed manner. Lasers


46


and


48


can be replaced with focused lamps that provide appropriate light for curing pieces


44


B and


44


F.




Rather than using tack structures


44


to tack backplate structure


30


to faceplate structure


32


and thus to composite structure


32


/


34


/


36


, the tacking operation can be performed by joining backplate structure


30


to faceplate structure


32


along outer wall


34


at multiple laterally separated tacking seal portions of backplate sealing area


30


S. This is typically performed by directing light energy of a laser or focused lamp through the tacking seal portions of area


30


S and onto the corresponding adjacent portions of wall


34


. Thin portions of wall


34


melt when struck by the beam of light energy. Upon cooling, the thin portions of wall


34


then securely hold backplate structure


30


in a fixed position relative to faceplate structure


32


.




As another alternative, faceplate structure


32


can be tacked to backplate structure


30


through selected ones or all of spacer walls


36


. Each wall


36


intended to serve as a tack element for tacking structure


32


to structure


30


is referred to here as a tacking spacer wall. Each tacking spacer wall


36


is connected to faceplate structure


32


during the tacking operation or at an earlier point, e.g., during the placement of walls


36


on the interior surface of structure


32


at the stage of

FIG. 2



d


. During the tacking operation, each tacking spacer wall


36


is rigidly connected to the interior surface of backplate structure


30


.




The rigid connection of tacking spacer walls


36


to plate structures


30


and


32


can be performed in various ways. For example, plate structure


30


or/and plate structure


32


can be provided with one or more grippers into which each tacking spacer wall


36


is inserted. The grippers securely physically clamp tacking spacer walls


36


to structure


30


or/and structure


32


so as to hold faceplate structure


32


in a fixed positional relationship to backplate structure


30


.




Glue or other adhesive can be utilized to rigidly connect each tacking spacer wall


36


to backplate structure


30


or/and faceplate structure


32


. The adhesive can be placed on opposite top and bottom edges of each tacking spacer wall


36


or/and on suitable portions of structure


30


or/and structure


32


prior to rigidly connecting tacking spacer walls


36


to structure


30


or/and structure


32


. When the adhesive needs UV or thermal curing to create the rigid bonds, an appropriate curing step is performed, e.g., globally in a heating oven for thermal curing or locally with one or two lasers or focused lamps for thermal or UV curing. When used, the laser or lasers can be arranged generally in the manner depicted in

FIG. 2



f


for lasers


46


and


48


.




Tacking spacer walls


36


can be rigidly connected to backplate structure


30


or/and faceplate structure


32


by metal such as suitable eutectic, solder, or braze. Heat is applied in an appropriate manner to form each eutectic, solder, or braze bond. Tacking spacer walls


36


can also be ultrasonically bonded to structure


30


or/and structure


32


. One of the preceding tacking techniques can be employed to connect tacking spacer walls


36


to backplate structure


30


during the tacking operation while another of these techniques is used to connect tacking spacer walls


36


to faceplate structure


32


during or before the tacking operation.




Tacked, aligned structure


30


/


32


/


34


/


36


, typically including tack structures


44


, is oriented so that faceplate structure


32


is vertically on top as shown in

FIG. 2



g


, e.g., by flipping structure


30


/


32


/


34


/


36


over if backplate structure


30


was previously vertically on top, and placed in a sealing oven


54


for sealing backplate structure


30


to outer wall


34


. See

FIG. 2



h


. As situated in oven


54


, backplate structure


30


is thereby positioned vertically below faceplate structure


32


such that spacer walls


36


and the sealing material formed with outer wall


34


lie between plate structures


30


and


32


. Tacked structure


30


/


32


/


34


/


36


normally extends approximately horizontal, i.e., a normal to the exterior surface of plate structure


30


or


32


extends approximately in the vertical direction. Tacked structure


30


/


32


/


34


/


36


can, however, extend somewhat off-horizontal, typically up to at least 20° off-horizontal, without significantly affecting the backplate-structure-to-outer-wall seal.




Faceplate structure


32


and outer wall


34


are vertically separated from backplate structure


30


either along all of backplate sealing area


30


S or, in the case where backplate structure


30


is directly tacked to outer wall


34


, along largely all of area


30


S. Spacer walls


36


and, when present, tack structures


44


form an intermediate system which is situated between plate structures


30


.and


32


and which causes structures


30


and


32


to be spaced vertically apart from each other in a largely fixed manner. As composite structure


30


/


32


/


34


/


36


is oriented in oven


54


, the gap between backplate structure


30


and outer wall


34


runs along the then-existent bottom edge of wall


34


.




The sealing of outer wall


34


to backplate structure


30


in oven


54


can be performed in any of a number of ways after composite structure


30


/


32


/


34


/


36


, again typically including tack structures


44


, is arranged in the foregoing manner. The backplate-structure-to-outer-wall sealing operation is normally done under non-vacuum conditions at a pressure close to room pressure, typically in an environment of dry nitrogen or an inert gas such as argon. In a typical implementation, oven


54


is filled with dry nitrogen at a pressure of approximately


710


torr. Alternatively, the backplate-structure-to-outer-wall sealing operation can be performed at a suitably high vacuum, typically a pressure of 10


−6


torr or less, in a sufficiently large vacuum chamber. In that event, the flat-final display is normally not provided with a pump-out tube for evacuating the display.




A heating operation, referred to as the gravitational heating operation, is performed to cause the sealing material formed with outer wall


34


to soften and move vertically downward under gravitational influence so as to contact backplate structure


30


and seal plate structures


30


and


32


together through outer wall


34


. In particular, the temperature of wall


34


is raised sufficiently that the sealing material of wall


34


softens and moves slowly downward to meet structure


30


during the gravitational heating operation. Wall


34


is then cooled down. During the cooldown, wall


34


becomes hermetically sealed to structure


30


along all of backplate sealing area


30


S.




The intermediate system formed with spacer walls


36


and, when present, tack structures


44


causes plate structures


30


and


32


to remain vertically spaced apart from each other during the gravitational heating operation in largely the fixed manner established directly before the gravitational heating operation. Specifically, the distance between plate structures


30


and


32


along any vertical line through structures


30


and


32


remains largely constant during the gravitational heating operation. Consequently, largely no z motion occurs between structures


30


and


32


during the gravitational heating operation, thereby substantially avoiding alignment degradation that might otherwise arise as a consequence of such z motion.




Also, the tack system formed with tack structures


44


, with the regions where outer wall


34


is directly tacked to backplate structure


30


, or with spacer walls


36


to the extent that they are used as tacking elements largely prevents plate structures


30


and


32


from moving horizontally relative to each other during the gravitational heating operation. The net result is that structures


30


and


32


remain in a largely fixed positional relationship to each other during the gravitational heating operation. When backplate sealing area


30


S is of surface energy that promotes bonding of outer wall


34


to area


30


S while adjoining backplate area portions


30


NI and


30


NO are of surface energy that inhibits bonding of wall


34


to portions


30


NI and


30


NO, non-sealing portions


30


NI and


30


NO inhibit the sealing material of outer wall


34


from spreading laterally beyond area


30


S.




The gravitational heating operation preferably consists of globally heating structures


30


and


32


/


34


/


36


, typically including tack structures


44


, by raising structures


30


and


32


/


34


/


36


to a sealing temperature of 300-600° C., preferably 320-500°, typically 450° C., for 15-30 min., typically 20 min. For instance, the oven temperature can be ramped upward from room temperature to 450° C. at 5° C./min., maintained at 450° C. for 20 min., and then ramped downward from 450° C. to room temperature at −5° C./min. Although the sealing temperature is high enough to cause the sealing material of outer wall


34


to soften and, in some cases, melt or be on the verge of melting, the sealing temperature is sufficiently low to avoid significantly damaging any critical component of structure


30


or


32


or any of spacer walls


36


.




Alternatively, the gravitational heating operation can be performed by locally heating outer wall


34


to a temperature high enough to cause the sealing material of wall


34


to soften and move downward to contact backplate structure


30


. The local heating entails directing a beam of energy onto wall


34


. The energy beam can be highly focused as occurs with light energy provided from a laser or focused lamp. The energy beam can also be less focused than occurs with a laser or focused lamp provided that the heat energy does not go significantly beyond wall


34


. As an example, wave energy in the form of microwave or IR radiation can be utilized to locally heat wall


34


.




As a further alternative, global heating of structures


30


and


32


/


34


/


36


can be combined with local heating of outer wall


34


. In particular, the temperature of oven


54


can be raised to a point somewhat below that needed to cause the sealing material of wall


34


to soften and move significantly downward under gravitational influence. Local heating, e.g., by a laser or focused lamp, is then performed on wall


34


to raise its temperature to a point sufficiently high that the sealing material of wall


34


softens and moves downward under gravitational influence to meet backplate structure


30


and, upon cooldown, becomes hermetically sealed to structure


30


.




After the gravitational heating operation is completed, sealed structure


30


/


32


/


34


/


36


, typically including tack structures


44


, is removed from oven


54


.

FIG. 2



i


illustrates how the sealed flat-panel display appears at this stage. The sealing material formed with outer wall


34


does not extend significantly beyond sealing area


30


S of backplate structure


30


. Also, the wall sealing material extends continuously from faceplate structure


32


to backplate structure


30


.




Tack structures


44


, when present, typically remain in the final flat-panel display but can be removed from the display. In any event, subsequent operations depend (in part) on whether the gravitational heating operation was performed under vacuum or non-vacuum conditions. If the gravitational heating operation was conducted under non-vacuum conditions, subsequent operations entail evacuating the interior of the sealed display to a pressure of 10


−6


torr or less, closing the pump-out tube (again, not shown), and activating the getter (again, likewise not shown) to the extent that the getter consists of non-evaporable getter material.




Subject to being in an activated condition after the flat-panel display is evacuated, activation of the getter can be performed before, during, and/or after closure of the pump-out tube. Various techniques, including global heating of the display and local heating of the getter by, e.g., a laser or focused lamp, can be employed to activate the getter. When the getter is situated in an auxiliary compartment attached to backplate structure


30


, the auxiliary compartment is normally sealed to structure


30


subsequent to sealing outer wall


34


to structure


30


but before activating the getter and closing the pump-out tube. Nonetheless, the auxiliary compartment can be sealed to structure


30


at the same time that composite structure


32


/


34


/


36


is sealed to structure


30


and thus during the gravitational heating operation.




If the gravitational heating operation was done under vacuum conditions, the subsequent operations primarily entail activating the getter. If the getter is partially or wholly situated in an auxiliary compartment, the auxiliary compartment is sealed to backplate structure


30


either during the gravitational heating operation or after the gravitational heating operation and thus under vacuum conditions. Inasmuch as no pump-out tube is normally employed when the gravitational heating operation is done under vacuum conditions, the flat-panel display is fully sealed at the end of the gravitational heating operation or, as appropriate, after sealing the auxiliary compartment to backplate structure


30


under vacuum conditions. The interior of the sealed display is at a pressure suitably low for display operation.




Rather than consisting totally of sealing material that softens and moves downward during the gravitational heating operation, outer wall


34


may consist only partly of such sealing material.

FIG. 6

illustrates a structure containing such a variation of wall


34


at the stage of

FIG. 2



d


. In this variation, wall


34


consists of a main outer wall portion


34


M and a pair of sealing portions


34


B and


34


F. Sealing portion


34


B is situated on one edge of main wall portion


34


M. Sealing portion


34


F is situated on the opposite edge of main wall portion


34


M. At the point shown in

FIG. 6

, sealing portion


34


F joins main portion


34


M, and thus outer wall


34


, to faceplate structure


32


.




Sealing portions


34


B and


34


F, typically consisting of frit, soften and move vertically downward during the gravitational heating operation in which outer wall


34


is sealed to backplate structure


30


. Main wall portion


34


M consists of material, such as ceramic, which does not significantly change shape when subjected to the temperature that sealing portions


34


B and


34


F are subjected to during the gravitational heating operation. Although main portion


34


M typically moves downward during the gravitational heating operation due to the downward movement of sealing portion


34


F, main portion


34


M does not soften significantly during the gravitational heating operation and thus does not significantly change shape.




Seal-restricting Structures




The process of

FIG. 2

is particularly suitable for sealing a flat-panel display when there is only a relatively small change in viscosity of the sealing material during heating steps, especially the gravitational heating operation utilized to seal backplate structure


30


to outer wall


34


. However, it is sometimes desirable to utilize sealing material that undergoes a relatively large viscosity change during heating steps. In such cases, one or more seal-restricting structures can be utilized in place of, or in addition to, surface-energy modification to inhibit the sealing material of wall


34


from spreading laterally during elevated-temperature operations such as the gravitational heating operation.





FIGS. 7



a


-


7




d


(collectively “FIG.


7


”) illustrate part of a general process for hermetically sealing a flat-panel display utilizing seal-restricting structures in accordance with the invention. The process of

FIG. 7

begins with the steps of

FIGS. 2



a


-


2




e


for creating composite structure


32


/


34


/


36


, including tack structures


44


, as described above. The steps of

FIGS. 7



a


-


7




d


respectively parallel the steps of

FIGS. 2



f


-


2




i.






A pair of concentric rectangular annular seal-restricting structures


60


and


62


are provided on the interior surface of backplate structure


30


. The combination of backplate structure


30


and backplate restricting structures


60


and


62


forms a composite backplate structure


30


/


60


/


62


. The rectangular shape of restricting structures


60


and


62


can be seen in

FIG. 8

which presents a layout view of composite backplate structure


30


/


60


/


62


prior to being joined to outer wall


34


according to the process of FIG.


7


. As described further below, restricting structures


60


and


62


are positioned in such a way on backplate structure


30


that, in the sealed flat-panel display, inner restricting structure


60


runs along the inside of wall


34


while outer restricting structure


62


runs along the outside of wall


34


. Backplate sealing area


30


S extends between structures


60


and


62


.




Backplate restricting structures


60


and


62


normally (but not necessarily) consist of material largely non-wettable by the sealing material of outer wall


34


relative to sealing area


30


S of backplate structure


30


. When wall


34


consists of frit, at least along area


32


S, restricting structures


60


and


62


typically consist of carbon-containing material, especially hydrocarbon material. One example is polyimide. Another is silicon carbide. Structures


60


and


62


may consist of material, such as silicon nitride, which does not contain a significant amount of carbon. Structures


60


and


62


normally have a width (or thickness) measured laterally of 0.2-2 mm, typically 0.5 mm.




Backplate restricting structures


60


and


62


can be formed in various ways. For instance, at a suitable stage during the manufacture of composite backplate structure


30


/


60


/


62


, a blanket layer of the seal-restricting material can be formed on the then-existent interior surface of backplate structure


30


. The formation of the blanket layer can be done by a deposition technique such as evaporation, sputtering, liquid spraying, spin coating, meniscus coating, extrusion coating, or chemical vapor deposition. A deposited amount of the seal-restricting material can be spread with a doctor blade. Using a suitable photoresist mask, undesired portions of seal-restricting material are removed to produce restricting structures


60


and


62


.




Alternatively, backplate restricting structures


60


and


62


can be selectively deposited, typically by evaporation or sputtering, on the then-existent interior surface of backplate structure


30


using a shadow mask to prevent the seal-restricting material from accumulating on undesired portions of the then-existent interior surface of backplate structure


30


. Instead of a shadow mask, a photoresist mask can be formed on portions of the then-existent surface of backplate structure


30


not intended to receive the seal-restricting material. The seal-restricting material is then deposited, typically by any of the techniques mentioned above for depositing a blanket layer of the seal-restricting material, after which the photoresist mask is removed to remove any seal-restricting material accumulated on the mask. Restricting structure


60


and


62


can also be screen printed on the then-existent interior surface of backplate structure


30


using a liquid or slurry that contains the seal-restricting material.




Backplate restricting structures


60


and


62


can be created from actinic material by depositing a layer of actinic seal-restricting material on the then-existent interior surface of backplate structure


30


, exposing part of the material to suitable actinic radiation, and removing either the exposed or unexposed actinic material with a suitable developer. When the actinic material consists of photopolymerizable material such as photopolymerizable precursor polyimide material, the actinic radiation is typically UV light that causes the exposed photopolymerizable material to polymerize. The unexposed photopolymerizable material is then removed with the developer.




With composite backplate structure


30


/


60


/


62


having been formed in the preceding way, structure


30


/


60


/


62


is placed on top of composite structure


32


/


34


/


36


as shown in

FIG. 7



a


. In particular, structure


30


/


60


/


62


is positioned over structure


32


/


34


/


36


in the same way that backplate structure


30


is positioned over structure


32


/


34


/


36


at the corresponding stage shown in

FIG. 2



f


for the process of FIG.


2


. Consequently, the interior surface of backplate structure


30


in composite structure


30


/


60


/


62


faces downward with backplate sealing area


30


S vertically aligned to outer wall


34


. The interior surface of backplate structure


30


contacts spacer walls


36


and bonding pieces


44


B of tack structures


44


. Since spacer walls


36


are taller than outer wall


34


, a gap is again present between backplate structure


30


and outer wall


34


along all, or largely all, of area


30


S. The alignment is performed in the way described above in connection with

FIG. 2



f.






Outer wall


34


is situated opposite backplate sealing area


30


S and therefore opposite a location between backplate restricting structures


60


and


62


. Wall


34


may, or may not, extend into the space between structures


60


and


62


. Wall


34


typically does not contact structure


60


or


62


at the stage of

FIG. 7



a


. The lateral spacing between wall


34


and structure


60


or


62


is normally 5-500 μm, typically 250 μm. However, wall


34


can contact structure


60


or/and structure


62


at this point. In any event, structures


60


and


62


are shorter than spacer walls


36


and thus do not contact faceplate structure


32


.




Only one of restricting structures


60


and


62


may actually be provided on backplate structure


30


. In that case, outer wall


34


is situated at a location close to that one of structures


60


and


62


at the stage of

FIG. 7



a


. As in the case where both of structures


60


and


62


are present, the lateral spacing between wall


34


and structure


60


or


62


present on backplate structure


30


is normally 5-500 μm, typically 250 μm, but can drop to zero. If only one of restricting structures


60


and


62


is present, that one is typically inner structure


60


. Except as specifically indicated below, the remainder of the description of the process of

FIG. 7

is presented below as if backplate structure


30


were provided with both of restricting structures


60


and


62


. To the extent that one of structures


60


and


62


may be absent, a reference to, e.g., a reference symbol denoting, an absent one of structures


60


and


62


is to be ignored in the remainder of the process description of FIG.


7


. For instance, a reference to composite backplate structure


30


/


60


/


62


thereby means composite backplate structure


30


/


60


if outer restricting structure


62


is absent or composite backplate structure


30


/


62


if inner restricting structure


60


is absent.




Composite backplate structure


30


/


60


/


62


is typically tacked to composite structure


32


/


34


/


36


using lasers


46


and


48


in the same way that lasers


46


and


48


are employed to tack backplate structure


30


to composite structure


32


/


34


/


36


in the process of

FIG. 2

at the stage of

FIG. 2



f


. As indicated in

FIG. 7



a


, laser beams


50


and


52


respectively impinge downward and upward on structure


32


/


34


/


36


at the locations of tack structures


44


. Bonding pieces


44


B and


44


F are cured by laser beams


50


and


52


so as to chemically or/and physically interact with plate structures


30


and


32


. Focused lamps can be substituted for lasers


46


and


48


. In any event, bonding pieces


44


B and


44


F tack structures


44


to plate structures


30


and


32


. Once again, tack structures


44


cooperate with spacer walls


36


in causing plates structures


30


and


32


to be spaced vertically apart from each other in a largely fixed manner.




Similar to what was said above about the alternative ways of tacking backplate structure


30


to faceplate structure


32


in the process of

FIG. 2

, composite backplate structure


30


/


60


/


62


in the process of

FIG. 7

can alternatively be tacked to structure


32


at multiple laterally separated tacking seal portions of backplate sealing area


30


S rather than being tacked to structure


32


by way of tack structures


44


. This alternative tacking procedure is typically implemented by directing light energy of a laser or a focused lamp through the tacking seal portions of area


30


S and onto adjacent portions of outer wall


34


in the way described above for the process of FIG.


2


. Wall


34


is thereby joined to backplate structure


30


at multiple locations spaced laterally apart along area


30


S.




Composite backplate structure


30


/


60


/


62


can also be tacked to faceplate structure


32


along selected ones or all of spacer walls


36


. Except for backplate structure


30


/


60


/


62


in the process of

FIG. 7

replacing backplate structure


30


in the process of

FIG. 2

, this alternative is performed in the way described above for tacking backplate structure


30


to faceplate structure


32


through selected ones or all of spacer walls


36


in the process of FIG.


2


.




Tacked, aligned structure


30


/


32


/


34


/


36


/


60


/


62


, typically including tack structures


44


, is oriented so that faceplate structure


32


is on top, typically by flipping structure


30


/


32


/


34


/


36


/


60


/


62


over as indicated in

FIG. 7



b


, and placed in oven


54


. See

FIG. 7



c


. As occurs at the corresponding stage of

FIG. 2



h


in the process in

FIG. 2

, backplate structure


30


is positioned vertically below faceplate structure


32


in oven


54


at the stage of

FIG. 7



c


with outer wall


34


lying between plate structures


30


and


32


. Spacer walls


36


and, when present, tack structures


44


again form an intermediate mechanism situated between plate structures


30


and


32


for causing structures


30


and


32


to be spaced vertically apart from each other in a largely fixed manner.




Outer wall


34


is now sealed to backplate structure


30


in the manner described above in connection with the process of

FIG. 2

at the stage of

FIG. 2



h


. Oven


54


is normally filled with dry nitrogen or/and an inert gas at a pressure close to room pressure. Alternatively, oven


54


can be a vacuum chamber that is pumped down to a high vacuum condition, typically a pressure of 10


−6


torr or less, after tacked structure


30


/


32


/


34


/


36


/


60


/


62


is placed in over


54


.




A heating operation is performed to cause the sealing material formed with wall


34


to soften and move vertically downward under gravitational influence. During this heating operation, again referred to as the gravitational heating operation, the wall sealing material contacts backplate structure


30


along backplate sealing area


30


S. Plate structures


30


and


32


are thereby sealed together through wall


34


.




The intermediate structure formed with spacer walls


36


and, when present, tack structures


44


again causes plate structures


30


and


32


to remain spaced vertically apart from each other in largely the fixed manner established directly before the gravitational heating operation. The tack system prevents structures


30


and


32


from moving horizontally relative to each other. Hence, structures


30


and


32


remain in largely a fixed position relative to each other during the gravitational heating operation. Because there is largely no z motion between structures


30


and


32


during the gravitational heating operation, alignment degradation due to such z motion is again avoided.




During the gravitational heating operation, the sealing material of outer wall


34


contacts backplate structure


30


between restricting structures


60


and


62


. Depending on the viscosity of the sealing material and on the lateral separation between wall


34


and each of restricting structures


60


and


62


prior to the gravitational heating operation, wall


34


may contact the outer sidewall of inner restricting structure


60


and/or the inner sidewall of outer restricting structure


62


. However, structures


60


and


62


largely prevent the wall sealing material from spreading over structures


60


and


62


and contacting backplate structure


30


laterally beyond structures


60


and


62


. That is, inner restricting structure


60


largely prevents the wall sealing material from contacting backplate structure


30


inside inner structure


60


and damaging sensitive elements such as electron-emissive elements in the active portion of backplate structure


30


. Outer restricting structure


62


similarly largely prevents the wall sealing material from contacting backplate structure


30


outside structure outer


62


. The capability to achieve such restriction is typically enhanced by manufacturing restricting structures


60


and


62


so as to be largely non-wettable by the wall sealing material.




By appropriately choosing the lateral spacing between wall


34


and each of backplate restricting structures


60


and


62


prior to the gravitational heating operation, the sealing material of outer wall


34


normally does not spread laterally to contact inner structure


60


beyond its outer sidewall or to contact outer structure


62


beyond its inner sidewall. That is, the wall sealing material normally does not extend significantly over the top of structure


60


or


62


. Because structures


60


or


62


provide physical and/or chemical restraints to the lateral spreading of the wall sealing material during the gravitational heating step, the viscosity of outer wall


34


in the process of

FIG. 7

can change more during the gravitational heating operation than in the process of FIG.


2


.




When only one of restricting structures


60


and


62


is provided on backplate structure


30


, outer wall


34


contacts backplate structure


30


close to that one of structures


60


and


62


during the gravitational heating operation. For example, if inner structure


60


is present but outer structure


62


is absent, wall


34


contacts backplate structure


30


close to the outer sidewall of inner structure


60


. On the other hand, if outer structure


62


is present but inner structure


60


is absent, wall


34


contacts backplate structure


30


close to the inner sidewall of structure


62


.




Additionally, when only one of restricting structures


60


and


62


is present, backplate sealing area


30


S may be of different surface energy than the portion


30


NI or


30


NO of the interior surface of backplate structure


30


extending along and adjoining area


30


S and situated on the opposite side of area


30


S from that one of structures


60


and


62


. For instance, if only inner structure


60


is present, area


30


S may be of different surface energy than portion


30


NO extending along the outside of area


30


S. If only outer structure


62


is present, area


30


S may be of different surface energy than portion


30


NI extending along the inside of area


30


S. Although neither of backplate area portions


30


NI and


30


NO is indicated in

FIG. 7

or


8


, the locations of portions


30


NI and


30


NO are indicated in

FIG. 5

which presents a layout view corresponding to that of

FIG. 8

but prior to the formation of restricting structures


60


and


62


on backplate structure


30


. Accordingly,

FIG. 5

effectively presents a layout view of backplate structure


30


for the process of

FIG. 7

prior to forming restricting structures


60


and


62


.




The surface energy of backplate sealing area


30


S promotes bonding of the sealing material of outer wall


34


to area


30


S. During the gravitational heating operation, the wall sealing material wets area


30


S. When backplate area portion


30


NI or


30


NO is of different surface energy than area


30


S, the surface energy of portion


30


NI or


30


NO is chosen to inhibit bonding of the wall sealing material to portion


30


NI or


30


NO. During the gravitational heating operation, the wall sealing material does not significantly wet portion


30


NI or


30


NO compared to how the sealing material wets area


30


S. Portion


30


NI or


30


NO thereby (a) inhibits the sealing material of wall


34


from spreading inward when portion


30


NI is of the so-chosen surface energy or (b) inhibits the wall sealing material from spreading outward when portion


30


NO is of the so-chosen surface energy.




After completing the gravitational heating operation, sealed structure


30


/


32


/


34


/


36


, including backplate restricting structure


60


and/or backplate restricting structure


62


and also typically tack structures


44


, is removed from oven


54


.

FIG. 7



d


illustrates the sealed flat-panel display at this stage. The sealing material formed with outer wall


34


does not extend significantly laterally beyond restricting structures


60


and


62


when both are present on backplate structure


30


. If only one of structures


60


and


62


is present, the wall sealing material does not extend significantly laterally beyond that one of structures


60


and


62


and, if the surface energy of backplate sealing portion


30


NO or


30


NI opposite that structure


60


or


62


is chosen in the above-described manner, does not extend significantly beyond backplate sealing area


30


S. Further operations, which depend (in part) on whether the gravitational heating operation was performed under vacuum or non-vacuum conditions, are performed on the display of

FIG. 7



d


in the manner described above for the display of

FIG. 2



i.






As in the flat-panel display sealed according to the process of

FIG. 2

, outer wall


34


in the display sealed according to the process of

FIG. 7

may consist only partly of sealing material that softens and moves downward during the gravitational heating operation.

FIG. 9

illustrates a structure containing such a variation of wall


34


for a flat-panel display sealed according to the process of FIG.


7


. The structure of

FIG. 9

occurs at the stage of

FIG. 7



b


. As in the earlier-mentioned variation of

FIG. 6

, wall


34


in the variation of

FIG. 9

consists of main outer wall portion


34


M and sealing portions


34


B and


34


F. Main wall portion


34


M again consists of material, such as ceramic, which does not significantly change shape during the gravitational heating operation.





FIGS. 10



a


-


10




i


(collectively “FIG.


10


”) illustrate another process for hermetically sealing a flat-panel display utilizing seal-restricting structures in accordance with the invention. The process of

FIG. 10

differs from that of

FIG. 7

in that the seal-restricting structures are provided on both of plate structures


30


and


32


in the process of

FIG. 10

rather than just on backplate structure


30


as occurs in the process of FIG.


7


. Subject to this difference and noting that the process of

FIG. 7

begins with the steps of

FIGS. 2



a


-


2




e


, the steps of

FIGS. 10



a


-


10




i


respectively parallel the steps of

FIGS. 2



a


-


2




e


and


7




a


-


7




d.






A pair of concentric rectangular annular seal-restricting structures


64


and


66


are provided on the interior surface of faceplate structure


32


as shown in

FIG. 10



a


. The combination of faceplate structure


32


and faceplate restricting structures


64


and


66


forms a composite faceplate structure


32


/


64


/


66


. The rectangular shape of restricting structures


64


and


66


can be seen in

FIG. 11

which presents a layout view of composite faceplate structure


32


/


64


/


66


at the stage of

FIG. 10



a


. As described further below, restricting structures


64


and


66


are positioned in such a way on faceplate structure


32


that restricting structure


64


runs along the inside of outer wall


34


while restricting structure


66


runs along the outside of wall


34


. Faceplate sealing area


32


S extends between structures


64


and


66


.




Faceplate restricting structures


64


and


66


normally (but not necessarily) consist of material largely non-wettable by the sealing material of outer wall


34


relative to sealing area


32


S of faceplate structure


32


. When wall


34


consists of frit at least along area


32


S, restricting structures


64


and


66


are normally constituted in a similar manner to restricting structures


60


and


62


on backplate structure


30


. Accordingly, faceplate restricting structures


64


and


66


typically of carbon-containing material, especially hydrocarbon material, when wall


54


consists of frit at least along area


32


S. Examples of the carbon-containing material for structures


64


and


66


are polyimide and silicon carbide. Structures


64


and


66


may also consist of silicon nitride or another material which does not contain a significant amount of carbon. Structures


64


and


66


normally have a width (or thickness) measured laterally of 0.2-2 mm, typically 0.5 mm.




Faceplate restricting structures


64


and


66


can be formed in a similar manner to backplate restricting structures


60


and


62


. For example, at a suitable stage during the manufacture of composite faceplate structure


32


/


64


/


66


, a blanket layer of seal-restricting material can be formed on the then-existent interior surface of faceplate structure


32


. The formation of the blanket layer of seal-restricting material for faceplate restricting structures


64


and


66


can be done in any of the ways described above for creating the blanket layer of seal-restricting material for backplate restricting structures


60


and


62


. Using a suitable photoresist mask, undesired portions of the seal-restricting material are removed to produce faceplate restricting structures


64


and


66


.




Alternatively, faceplate restricting structures


64


and


66


can be selectively deposited on the then-existent interior surface of faceplate structure


32


using a shadow mask to prevent the seal-restricting material from accumulating on undesired areas of the then-existent interior surface of structure


32


. The shadow mask can be replaced with a photoresist mask formed directly on the then-existent surface of faceplate structure


32


at the locations where no seal-restricting material is desired. After depositing the seal-restricting material, the photoresist mask is removed to remove any seal-restricting material deposited on the mask. Restricting structures


64


and


66


can also be screen printed on the then-existent interior surface of faceplate structure


32


.




Faceplate restricting structures


64


and


66


can be created from actinic material by depositing a layer of actinic seal-restricting material on the then-existent interior surface of faceplate structure


32


, exposing part of the material to suitable actinic radiation, and removing either the exposed or unexposed actinic material with an appropriate developer. When the actinic material consists of photopolymerizable material, e.g., photopolymerizable precursor polyimide material, the actinic radiation is typically UV light that causes the exposed photopolymerizable precursor material to polymerize. The unexposed photopolymerizable material is then removed with the developer.




Outer wall


34


is placed in oven


38


. See

FIG. 10



b


. Wall


34


again lies on a suitable support (not shown) in a horizontal position in oven


38


. Composite faceplate structure


32


/


64


/


66


is placed in oven


38


and positioned on top of wall


34


with the interior surface of faceplate structure


32


facing downward so that wall


34


contacts structure


32


in the space between faceplate restricting structures


64


and


66


. Depending on thickness of wall


34


relative to the spacing between restricting structures


64


and


66


, wall


34


may contact one or both of structures


64


and


66


at this point. In any event, wall


34


is vertically aligned to faceplate sealing area


32


S. As necessary, a suitable alignment system (not shown) is utilized to achieve the requisite alignment.




Only one of faceplate restricting structures


64


and


66


may actually be provided on faceplate structure


32


. In that case, outer wall


34


is situated at location close to that one of restricting structures


64


and


66


at the stage of

FIG. 10



a


. If only one of restricting structures


64


and


66


is present, that one is typically inner structure


64


.




Except as specifically indicated below, the remainder of the description of the process of

FIG. 10

is presented below as if faceplate structure


32


were provided with both of restricting structures


64


and


66


. To the extent that one of structures


64


and


66


may be absent, a reference to, e.g., a reference symbol denoting, an absent one of structures


64


and


66


is to be ignored in the remainder of the process description of FIG.


10


. For instance, a reference to composite faceplate structure


32


/


64


/


66


thereby means composite faceplate structure


32


/


64


if outer restricting structure


66


is absent or composite faceplate structure


32


/


66


if inner restricting structure


64


is absent.




With composite faceplate structure


32


/


64


/


66


suitably aligned to outer wall


34


, structure


32


/


64


/


66


is sealed to wall


34


. The faceplate-structure-to-outer-wall sealing operation is performed in the manner described above in connection with the process of

FIG. 2

at the stage of

FIG. 2



b


. Hence, after filling oven


38


with dry nitrogen or an inert gas at a pressure close to room pressure, wall


34


is heated so that it softens. In the preferred heating process described above in connection with

FIG. 2



b


, wall


34


is raised to a suitable bias temperature after which laser beam


42


of laser


40


is directed along faceplate sealing area


32


S so as to cause a thin portion of wall


34


along area


32


S to melt. During the subsequent cooldown, wall


34


becomes sealed to composite faceplate structure


32


/


64


/


66


.




The faceplate-structure-to-outer-wall seal occurs along faceplate sealing area


32


S located between faceplate restricting structures


64


and


66


. Structures


64


and


66


prevent the sealing material of outer wall


34


from spreading over structures


64


and


66


and contacting faceplate structure


32


laterally beyond structures


64


and


66


. In other words, inner restricting structure


64


prevents the wall sealing material from contacting faceplate structure


32


inside inner structure


64


and damaging sensitive elements such as light-emitting elements in the active portion of faceplate structure


32


. Outer restricting structure


66


similarly prevents the wall sealing material from contacting faceplate structure


32


outside outer structure


66


. The capability to achieve such restriction is typically enhanced by fabricating restricting structures


64


and


66


so as to be largely non-wettable by the wall sealing material.




By appropriately controlling the faceplate-structure-to-outer-wall sealing operation, the wall sealing material normally does not spread laterally to contact inner faceplate restricting structure


64


significantly beyond its outer sidewall or to contact outer faceplate restricting structure


66


significantly beyond its inner sidewall. That is, the wall sealing material normally does not extend significantly over the top of structure


64


or


66


. Since structures


64


and


66


furnish physical and/or chemical restraints on the lateral spreading of the sealing material of wall


34


during the faceplate-structure-to-outer-wall sealing operation, the viscosity of wall


34


can change more during the faceplate-strncture-to-outer-wall seal here than in the process of FIG.


2


.




When only one of restricting structures


64


and


66


is provided on faceplate structure


32


, outer wall


34


contacts faceplate structure


32


close to that one of structures


64


and


66


during the faceplate-structure-to-outer-wall seal. For example, if inner structure


64


is present but outer structure


66


is absent, wall


34


contacts faceplate structure


32


close to the outer sidewall of inner structure


64


. On the other hand, if outer structure


66


is present but inner structure


64


is absent, wall


34


contacts faceplate structure


32


close to the inner sidewall of outer structure


66


.




Also, when only one of faceplate restricting structures


64


and


66


is present, faceplate sealing area


32


S may be of different surface energy than the portion


32


NI or


32


NO of the interior surface of faceplate structure


32


extending along and adjoining area


32


S and situated on the opposite side of area


32


S from that one of structures


64


and


66


. For example, if only inner structure


64


is present, area


32


S may be of different surface energy than portion


32


NO extending along the outside of area


32


S. If only outer structure


66


is present, area


32


S may be of different surface energy than portion


32


NI extending along the inside of area


32


S. Although neither of faceplate area portions


30


NI and


30


NO is indicated in

FIG. 10

or


11


, the locations of portions


30


NI and


30


NO are indicated in

FIG. 3

which presents a layout view corresponding to that of

FIG. 11

but prior to the formation of restricting structures


64


and


66


on faceplate structure


32


. Accordingly,

FIG. 3

effectively presents a layout view of faceplate structure


32


for the process of

FIG. 10

prior to forming restricting structures


64


and


66


.




The surface energy of faceplate sealing area


32


S promotes bonding of the sealing material of outer wall


34


to area


32


S. During the faceplate-structure-to-outer-wall sealing operation, the wall sealing material wets area


32


S. When faceplate area portion


32


NI or


32


NO is of different surface energy than area


32


S, the surface energy of portion


32


NI or


32


NO is chosen to inhibit bonding of the wall sealing material to portion


32


NI or


32


NO. During the faceplate-structure-to-outer-wall sealing operation, the wall sealing material does not significantly wet portion


32


NI or


32


NO compared to how the wall sealing material wets area


32


S. Portion


32


NI or


32


NO thereby (a) inhibits the sealing material of wall


34


from spreading inward when portion


32


NI is of the so-chosen surface energy or (b) inhibits the wall sealing material from spreading outward when portion


32


NO is of the so-chosen surface energy.




After the faceplate-structure-to-outer-wall seal is completed, composite sealed structure


32


/


34


/


64


/


66


is removed from oven


38


or other oven. Structure


32


/


34


/


64


/


66


is oriented so that outer wall


34


is on top of faceplate structure


32


, e.g., by flipping structure


32


/


34


/


64


/


66


over if composite faceplate structure


32


/


64


/


66


was vertically on top of outer wall


34


during the faceplate-structure-to-outer-wall seal. See

FIG. 10



c.






Further processing on composite structure


32


/


34


/


64


/


66


is typically conducted in the manner described above in connection with

FIGS. 2



d


and


2




e


for the process of FIG.


2


. In particular, spacer walls


36


are provided on the interior surface of faceplate structure


32


as shown in

FIG. 10



d


. Also see

FIG. 12

which presents a plan view of resultant structure


32


/


34


/


36


/


64


/


66


at the stage of

FIG. 10



d


. Tack structures


44


are typically provided on faceplate structure


32


outside outer wall


34


as indicated in

FIG. 10



e


. Alternatively, selected ones or all of spacer walls


36


can be tacked to composite faceplate structure


32


/


64


/


66


in the manner described above for connecting tacking spacer walls


36


to faceplate structure


32


in the process of FIG.


2


.




The remainder of the sealing operation in the process of

FIG. 10

is conducted in the manner described above in connection with the of process of FIG.


7


. Specifically, seal-restricting structures


60


and


62


are provided on the interior surface of backplate structure


30


. Composite backplate structure


30


/


60


/


62


is placed on top of composite structure


32


/


34


/


36


/


64


/


66


as depicted in

FIG. 10



f


. The interior surface of backplate structure


30


thereby faces downward with backplate sealing area


30


S vertically aligned to outer wall


34


. The interior surface of backplate structure


30


contacts spacer walls


36


and bonding pieces


44


B of tack structures


44


. A gap is again present between wall


34


along all, or largely all, of sealing area


30


S. Faceplate restricting structures


64


and


66


are respectively situated opposite backplate restricting structures


60


and


62


but do not contact structures


60


and


62


.




Composite backplate structure


30


/


60


/


62


is typically tacked to composite structure


32


/


34


/


36


/


64


/


66


using lasers


46


and


48


in the same manner that lasers


46


and


48


are employed to tack composite backplate structure


30


/


60


/


62


to composite structure


32


/


34


/


36


in the process of FIG.


7


and thus in the same manner that lasers


46


and


48


are utilized to tack backplate structure


30


to composite structure


32


/


34


/


36


in the process of FIG.


2


. Upon being struck by laser beams


50


and


52


, bonding pieces


44


B and


44


F of tack structures


44


join structures


44


securely to plate structures


30


and


32


. Alternatively, composite backplate structure


30


/


60


/


62


can be tacked to composite faceplate structure


32


/


64


/


66


(a) along outer wall


34


in the way prescribed above for tacking backplate structure


30


to faceplate structure


32


through outer wall


34


in the process of

FIG. 2

or (b) through selected ones or all of spacer walls


36


in the way prescribed above for connecting tacking spacer walls


36


to backplate structure


30


in the process of FIG.


2


. Upon being struck by laser beams


50


and


52


, bonding pieces


44


B and


44


F of tack structures


44


join structures


44


securely to plate structures


30


and


32


. Alternatively, composite backplate structure


30


/


60


/


62


can be tacked to composite face structure


32


/


64


/


66


(a) along outer wall


34


in the way prescribed above for tacking backplate structure


30


to faceplate structure


32


through outer wall


34


in the process of

FIG. 2

or (b) through selected ones or all of spacer walls


36


in the way prescribed above for connecting tacking spacer walls


36


to backplate structure


30


in the process of FIG.


2


.




Tacked, aligned structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


, typically including tack structures


44


, is oriented so that faceplate structure


32


is vertically on top as depicted in

FIG. 10



g


, e.g., by flipping tacked structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


over if backplate structure


30


was previously vertically on top, and placed in oven


54


. See

FIG. 10



h


. As occurs at the corresponding stage of

FIG. 2



h


in the process of

FIG. 2

, or at the corresponding stage of

FIG. 7



c


in the process of

FIG. 7

, backplate structure


30


is positioned vertically below faceplate structure


32


in oven


54


at the stage of

FIG. 10



h


with outer wall


34


lying between plate structures


30


and


32


. With spacer walls


36


and, when present, tack structures


44


forming an intermediate mechanism that causes plate structures


30


and


32


to be spaced vertically apart from each other in largely a fixed manner, a gravitational heating operation is performed to hermetically seal composite faceplate structure


32


/


64


/


66


to composite backplate structure


30


/


60


/


62


through outer wall


34


. The gravitational heating operation is conducted as described above in connection with

FIG. 2

subject to the modifications of

FIG. 7

to account for backplate restricting structures


60


and


62


.




If (as in the flat-panel display sealed according to process of

FIG. 2

) restricting structures


64


and


66


were not provided on faceplate structure


32


, the sealing material of outer wall


34


would normally not spread significantly laterally over faceplate structure


32


during the gravitational heating operation. Nonetheless, to the extent that such lateral spreading might otherwise occur, inner restricting structure


64


and/or outer restricting structure


66


, depending on whether one or both are present, inhibit lateral spreading of the wall sealing material beyond sealing area


32


S.




As in the flat-panel display sealed according to the process of

FIG. 7

, only one of restricting structures


60


and


62


may actually be provided on backplate structure


30


in the flat-panel display sealed according to process of FIG.


10


. In that event, all of the comments made above about only one of structures


60


and


62


being present in the process of

FIG. 7

apply to the process of FIG.


10


. This includes arranging for the surface energy of backplate sealing area


30


S to differ from the surface energy of adjoining backplate area portion


32


NI or


32


NO as described above.




Sealed structure


30


/


32


/


34


/


36


, including faceplate inner restricting structure


64


and/or faceplate outer restricting structure


66


, backplate inner restricting structure


60


and/or backplate outer restricting structure


62


, and also typically tack structures


44


, is removed from oven


54


after the gravitational heating operation is completed. The sealed flat-panel display is depicted in

FIG. 10



i


. The sealing material formed with outer wall


34


does not extend significantly laterally beyond restricting structure


64


and


66


when both are present on faceplate structure


32


. If only one of structures


64


and


66


is present, the wall sealing material does not extend significantly laterally beyond that one of structures


64


and


66


and, if the surface energy of faceplate area portion


32


NI or


32


NO opposite that structure


64


or


66


is chosen in the above-described manner, does not extend significantly beyond faceplate sealing area


32


S. Further operations on the display of

FIG. 10



i


are performed as described above for the display of

FIG. 2



i.






All the variations described above for the processes of

FIGS. 2 and 7

generally apply to the process of FIG.


10


. This includes tacking plate structures


30


and


32


directly together at multiple laterally separated locations along outer wall


34


, or through selected ones or all of spacer walls


36


, rather than using tack structures


44


. Also, outer wall


34


can be configured as described above in connection with

FIGS. 6 and 9

so as to consist of main outer wall portion


34


M and sealing portions


34


B and


34


F.




Global-heating Gap-jumping Sealing





FIGS. 13



a


-


13




c


(collectively “FIG.


13


”) illustrate part of a general global-heating gap-jumping technique for hermetically sealing a flat-panel display according to the invention. The process of

FIG. 13

begins with the steps of

FIGS. 2



a


-


2




f


for creating tacked, aligned structure


30


/


32


/


34


/


36


, typically including tack structures


44


, as described above. All of the variations to the steps of

FIGS. 2



a


-


2




f


apply to forming tacked structure


30


/


32


/


34


/


36


for being sealed according to the process of FIG.


13


.

FIG. 13



a


illustrates how structure


30


/


32


/


34


/


36


, here including tack structures


44


, appears after the steps of

FIGS. 2



a


-


2




f


are completed.




Tacked structure


30


/


32


/


34


/


36


, typically including tack structures


44


, is placed in sealing oven


54


. See

FIG. 13



b


. Structure


30


/


32


/


34


/


36


can be oriented in various ways in oven


54


. Preferably, backplate structure


30


is vertically on top in tacked structure


30


/


32


/


34


/


36


. As situated in oven


54


, backplate structure


30


is thereby positioned vertically above faceplate structure


32


so that spacer walls


36


and the sealing material formed with outer wall


34


lie between plate structures


30


and


32


. This is generally opposite to the orientation of structure


30


/


32


/


34


/


36


during the gravitational heating step in the process of FIG.


2


. Structure


30


/


32


/


34


/


36


in the process of

FIG. 13

normally extends approximately horizontal at the stage of

FIG. 13



b


. However, structure


30


/


32


/


34


/


36


can extend somewhat off-horizontal, typically up to at least 40° off-horizontal, without significantly affecting the backplate-structure-to-outer-wall seal in the process of FIG.


13


.




As in the process of

FIG. 2

, faceplate structure


32


and outer wall


34


in the process of

FIG. 13

are spaced apart from backplate structure


30


either along all of backplate sealing area


30


S or, when backplate structure


30


is directly tacked to outer wall


34


, along largely all of area


30


S. Accordingly, a gap again separates wall


34


from backplate structure


30


along all, or largely all, of area


30


S. The gap arises because spacer walls


36


extend further away from faceplate structure


32


than does outer wall


34


. Spacer walls


36


and, when present, tack structures


44


thereby again form an intermediate system which is situated between plate structure


30


and


32


and which causes structures


30


and


32


to be spaced vertically apart from each other in largely a fixed manner.




The gap between outer wall


34


and backplate structure


30


has an average height which is normally at least 25 μm. The average height of the gap is typically 75 μm and can be at least as much as 300 μm. In the orientation of

FIG. 13



b


, the gap runs along the then-existent top edge of wall


34


rather than along the then-existent bottom edge of wall


34


as occurs during the gravitational heating step in the process of FIG.


2


.




Tacked structure


30


/


32


/


34


/


36


, typically including tack structures


44


, in the process of

FIG. 13

is globally heated to cause the sealing material of wall


34


to jump the gap and hermetically seal plate structures


30


and


32


together through outer wall


34


as indicated in

FIG. 13



b


. During the global-heating gap-jumping operation, wall


34


softens and may even melt along its outside surface. Surface tension causes the softened material of wall


34


to become rounded. The softened material at the upper corners of wall


34


moves toward the longitudinal center of wall


34


. In turn, this causes the material along the longitudinal center of wall


34


near backplate structure


30


to move away from faceplate structure


32


so as to meet backplate structure


30


along sealing area


30


S. The wall sealing material moves vertically upward in the preferred implementation where backplate structure


30


is vertically above faceplate structure


32


.




Gas contained in the softened portions of outer wall


34


, or produced as a result of the softening (or melting) of the wall sealing material, may contribute to the upward expansion of wall


34


. Also, depending on the composition of wall


34


and on the conditions of the global-heating gap-jumping operation, material along the outer surface of wall


34


may undergo phase change in which the density of that material decreases. The attendant increase in the volume of wall


34


further contributes to the movement of the wall sealing material toward backplate structure


30


.




The global-heating gap-jumping operation normally consists of raising structures


30


and


32


/


34


/


36


, typically including tack structures


44


, to a sealing temperature of 300-600° C., preferably 320°-500° C., typically 450° C., for 15-30 min., typically 20 min. Outer wall


34


, along with the remainder of tacked structure


30


/


32


/


34


/


36


is subsequently cooled down. During the cooldown, wall


34


becomes hermetically sealed to backplate structure


30


along all of sealing area


30


S. In a typical implementation, the temperature in oven


54


is ramped upward from room temperature to 450° C. at 5° C./min., maintained at 450° C. for 20 min., and then ramped downward from 450° C. to room temperature at −5° C./min. The sealing temperature, although sufficiently high to cause the sealing material of wall


34


to soften and sometimes melt or be on the verge of melting along its outside surface, is sufficiently low to avoid significantly damaging any critical components of plate structure


30


or


32


or any of spacer walls


36


.




The global-heating gap-jumping operation may be performed at vacuum or non-vacuum conditions. In the non-vacuum case, the global-heating gap-jumping operation is normally done at a pressure close to room pressure in an environment of dry nitrogen or an inert gas such as argon. A typical implementation entails filling oven


54


with dry nitrogen at approximately 710 torr. In the vacuum case, the pressure in oven


54


is typically pumped down to 10


−6


torr or less.




Similar to what occurs during the gravitational heating operation of

FIG. 2

, the intermediate system formed with spacer walls


36


and, when present, tack structures


44


causes plate structures


30


and


32


in the process of

FIG. 13

to remain vertically spaced apart from each other during the global-heating gap-jumping operation in largely the fixed manner established before the global-heating gap-jumping operation. Accordingly, largely no z motion occurs between structures


30


and


32


during the global-heating gap-jumping operation. Alignment degradation that might otherwise occur due to such z motion is largely avoided.




Likewise, the tack system formed with tack structures


44


, with the regions where outer wall


34


is directly tacked to backplate structure


30


, or with spacer walls


36


when they are used as tacking elements largely prevents plate structures


30


and


32


from moving horizontally relative to each other during the global-heating gap-jumping operation. Hence, structures


30


and


32


remain in largely a fixed positional relationship to each other during the global-heating gap-jumping operation. Backplate sealing area


30


S may be of surface energy that promotes bonding of outer wall


34


to area


30


S while adjoining backplate area portions


30


NI and


30


NO are of surface energy that inhibits bonding of wall


34


to portions


30


NI and


30


NO. In that case, non-sealing portions


30


NI and


30


NO inhibit the sealing material of outer wall


34


from spreading laterally beyond area


30


S during the global-heating gap-jumping operation.




Sealed structure


30


/


32


/


34


/


36


, typically including tack structures


44


, is removed from oven


54


after the global-heating gap-jumping operation is completed.

FIG. 13



c


depicts how the sealed flat-panel display appears at that point. The sealing material formed with outer wall


34


does not extend significantly beyond sealing area


30


S of backplate structure


30


. Subsequent operations, dependent (in part) on whether the global-heating gap-jumping operation was done under vacuum or non-vacuum conditions, are performed in the way described above for the process of FIG.


2


.




Outer wall


34


has been illustrated in

FIG. 13

as having a vertical cross-sectional profile that is generally rectangular. However, the vertical cross-sectional profile of wall


34


can have a non-rectangular shape. As one example, the vertical cross-sectional profile of wall


34


at the stage of

FIG. 13



a


can be shaped roughly like an inverted trapezoid, preferably an inverted isosceles trapezoid, in which the shorter of the two parallel sides of the trapezoid meets faceplate sealing area


32


S. Gap jumping to seal the flat-panel display thereby occurs along the longer of the two parallel sides of the trapezoid. The trapezoidal vertical cross-sectional profile for wall


34


is advantageous because additional wall material for gap jumping is provided at a location close to backplate structure


30


.




In the example of

FIG. 13



c


, the sealing material of outer wall


34


extends continuously from faceplate structure


32


to backplate structure


30


. However, analogous to what was said above about the constituency of wall


34


in the flat-panel display sealed according to the process of

FIG. 2

, wall


34


in the flat-panel display sealed according of

FIG. 13

may consist only partly of sealing material that softens and jumps the gap between wall


34


and backplate structure


30


. Wall


34


in the display sealed according to the process of

FIG. 13

can be configured as shown in

FIG. 6

to consist of main wall portion


34


M and sealing portions


34


B and


34


F.




During the global-heating gap-jumping operation, sealing portion


34


B changes shape so as to jump the gap between wall


34


and backplate structure


30


. Main portion


34


M largely retains its shape during the global-heating gap-jumping operation. Outer wall


34


in this variation may also have a non-rectangular vertical cross-sectional profile, e.g., a roughly trapezoidal vertical cross-sectional profile in which sealing portion


34


B is wider laterally than sealing portion


34


F. This profile can facilitate gap jumping to seal the display.





FIGS. 14



a


-


14




c


(collectively “FIG.


14


”) illustrate part of a general process for sealing a flat-panel display using a global-heating gap-jumping technique and backplate seal-restricting structures


60


and


62


in accordance with the invention. The process of

FIG. 14

begins with the steps of


2




a


-


2




e


for creating composite structure


32


/


34


/


36


, typically including tack structures


44


, followed by the step of

FIG. 7



a


for tacking composite backplate structure


30


/


60


/


62


consisting of backplate structure


30


and restricting structures


60


and


62


to composite structure


32


/


34


/


36


to form tacked, aligned structure


30


/


32


/


34


/


36


/


60


/


62


. The steps of

FIGS. 14



a


-


14




c


respectively parallel the steps of

FIGS. 13



a


-


13




c


.

FIG. 14



a


depicts how tacked structure


30


/


32


/


34


/


36


/


60


/


62


, here including tack structures


44


, appears after the steps of

FIGS. 2



a


-


2




e


and


7




a


are completed.




Tacked structure


30


/


32


/


34


/


36


/


60


/


62


, typically including tack structures


44


, is placed in sealing oven


54


. See

FIG. 14



b


. All the comments made above about the configuration and orientation of tacked structure


30


/


32


/


34


/


36


, including the presence of a gap between backplate structure


30


and outer wall


34


, in the process of

FIG. 13

after the placement of structure


30


/


32


/


34


/


36


into oven


54


but prior to the global-heating gap-jumping operation apply to the configuration and orientation of structure


30


/


32


/


34


/


36


/


60


/


62


at this point in the process of FIG.


14


. Hence, backplate structure


30


is preferably vertically above outer wall


34


in the process of

FIG. 14

so that the gap between backplate structure


30


and wall


34


runs along the top edge of wall


34


in tacked structure


30


/


32


/


34


/


36


/


60


/


62


.




Tacked structure


30


/


32


/


34


/


36


/


60


/


62


is globally heated as described above for tacked structure


30


/


32


/


34


/


36


at the stage of

FIG. 13



b


. The global heating causes the sealing material of outer wall


34


to vertically jump the gap and hermetically seal plate structures


30


and


32


together through wall


34


as indicated in

FIG. 14



b


. All the comments made above about the global-heating gap-jumping operation in the process of

FIG. 13

apply to the global-heating gap-jumping operation in the process of FIG.


14


. This includes the alternative of configuring the vertical cross-sectional profile of wall


34


to be of non-rectangular shape such as an inverted trapezoid at the stage of

FIG. 14



a.






Similarly, the comments made above about backplate restricting structures


60


and


62


during the gravitational heating operation in the process of

FIG. 7

generally apply to structures


60


and


62


during the global-heating gap-jumping operation in the process of FIG.


14


. In addition, a result of utilizing structures


60


and


62


is that, when at least one of structures


60


and


62


actually laterally restricts the sealing material of outer wall


34


during the global-heating gap-jumping operation, more of the wall sealing material is forced upward toward overlying backplate structure


30


than what would occur if restricting structures


60


and


62


were absent. Consequently, structures


60


and


62


generally enhance the capability to jump the gap. This advantage also typically arises when only one of structures


60


and


62


is present.




Sealed structure


30


/


32


/


34


/


36


/


60


/


62


is removed from oven


54


after completing the global-heating gap-jumping operation. See

FIG. 14



c


in which, compared to the orientation of structure


30


/


32


/


34


/


36


/


60


/


62


in

FIG. 14



b


, structure


30


/


32


/


34


/


36


/


60


/


62


has been flipped over. Once again, the sealing material of wall


34


does not extend significantly beyond sealing area


30


S of backplate structure


30


. Subsequent operations are performed as described above for the process of FIG.


2


.





FIGS. 15



a


-


15




c


(collectively “FIG.


15


”) illustrate part of a general procedure for sealing a flat-panel display using a global-heating gap jumping technique, backplate seal-restricting structures


60


and


62


, and faceplate seal-restricting structures


64


and


66


in accordance with the invention. The process of

FIG. 15

begins with the steps of

FIGS. 10



a


-


10




f


for creating tacked, aligned structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


, typically including tack structures


44


, in which composite backplate structure


30


/


60


/


62


, again consisting of backplate structure


30


and restricting structures


60


and


62


, is tacked to composite faceplate structure


32


/


64


/


66


consisting of faceplate structure


32


and restricting structures


64


and


66


. The steps of

FIGS. 15



a


-


15




c


respectively parallel the steps of

FIGS. 13



a


-


13




c


.

FIG. 15



a


depicts how tacked structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


, here including tack structures


44


, appears after the steps of

FIGS. 10



a


-


10




f


are completed.




Tacked structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


, typically including tack structures


44


, is placed in sealing oven


54


. See

FIG. 15



b


. All the comments made above about the configuration and orientation of tacked structure


30


/


32


/


34


/


36


, including the presence of a gap between backplate structure


30


and outer wall


34


in the process of

FIG. 13

after placement of structure


30


/


32


/


34


/


36


into oven


54


but prior to the global-heating gap-jumping operation apply to the configuration and orientation of tacked structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


at this point in the process of FIG.


15


. Consequently, backplate structure


30


is preferably vertically above outer wall


34


at this point in the process of

FIG. 15

so that the gap between backplate structure


30


and wall


34


runs along the top edge of wall


34


in tacked structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


.




Tacked structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


is globally heated as described above for tacked structure


30


/


32


/


34


/


36


at the stage of

FIG. 13



b


. The global heating causes the sealing material of outer wall


34


to jump the gap and hermetically seal plate structures


30


and


32


together through outer wall


34


as indicated in

FIG. 15



b


. All the comments made above about the global-heating gap-jumping operation in the process of

FIG. 13

apply to the global-heating gap-jumping operation in the process of FIG.


15


.




Similarly, all the comments made above about backplate restricting structures


60


and


62


and faceplate restricting structures


64


and


66


during the gravitational heating operation in the process of

FIG. 10

generally apply to structures


60


,


62


,


64


, and


66


during the global-heating gap-jumping operation in the process of FIG.


15


. Furthermore, backplate restricting structures


60


and


62


enhance the capability to jump the gap between backplate structure


30


and outer wall


34


in the process of

FIG. 15

in the same way as in the process of FIG.


14


. This advantage arises if only one of faceplate restricting structures


64


and


66


is present and typically also if only one of backplate restricting structures


60


and


62


is present.




Sealed structure


30


/


32


/


34


/


36


/


60


/


62


/


64


/


66


, including faceplate inner restricting structure


64


and/or faceplate outer restricting structure


66


, backplate inner restricting structure


60


and/or backplate outer restricting structure


62


, and also typically tack structures


44


, is removed from oven


54


after the gravitational heating operation is completed. The sealed flat-panel display is depicted in

FIG. 10



i


. The sealing material formed with outer wall


34


does not extend significantly laterally beyond restricting structure


64


and


66


when both are present on faceplate structure


32


. If only one of structures


64


and


66


is present, the wall sealing material does not extend significantly laterally beyond that one of structures


64


and


66


and, if the surface energy of faceplate area portion


32


NI or


32


NO opposite that structure


64


or


66


is chosen in the above-described manner, does not extend significantly beyond faceplate sealing area


32


S. Further operations on the display of

FIG. 10



i


are performed as described above for the display of

FIG. 2



i.






Variations




While the invention has been described with reference to particular embodiments, this description is solely for purpose of illustration and is not to be construed as limiting the scope of the invention claimed below. For example, outer wall


34


can have a lateral shape other than a rectangular annulus. The sealing of faceplate structure


32


to wall


34


can be performed at orientations other than those shown in

FIGS. 2



b


and


10




b


. The tacking of faceplate structure


32


to backplate structure


30


through tack structures


44


can likewise be performed at orientations other than those depicted in

FIGS. 2



f


,


7




a


, and


10




f.






The roles of plate structures


30


and


32


can be reversed in the overall sealing operation. That is, outer wall


34


and spacer walls


36


can be initially joined to backplate structure


30


rather than to faceplate structure


32


. In that case, spacer walls


36


in resultant composite structure


30


/


34


/


36


extend further away from backplate structure


30


than does outer wall


34


. Faceplate structure


32


is then placed on composite structure


30


/


34


/


36


, appropriately aligned to structure


30


/


34


/


36


, and tacked to backplate structure


30


. The tacking operation can be performed with tack structures


44


, along multiple laterally separated portions of outer wall


34


, or through selected ones or all of spacer walls


36


. Because spacer walls


36


are taller than outer wall


34


, a gap separates faceplate structure


32


from outer wall


34


.




To complete the sealing operation, tacked structure


30


/


32


/


34


/


36


can be oriented in sealing oven


54


so that backplate structure


30


is vertically above outer wall


34


. The gap between outer wall


34


and faceplate structure


32


is then present along the then-existent bottom edge of wall


34


. Subject to the roles of plate structures


30


and


32


being reversed, a gravitational heating operation is performed on structure


30


/


32


/


34


/


36


as generally described above for the process of FIG.


2


. This causes the sealing material of wall


34


to move downward under gravitational influence to meet faceplate structure


32


and hermetically seal the flat-panel display.




Alternatively, tacked structure


30


/


32


/


34


/


36


can be oriented in oven


54


so that faceplate structure


32


is vertically above outer wall


34


. With structure


30


/


32


/


34


/


36


SO oriented, the gap between outer wall


34


and faceplate structure


32


is present along the then-existent top edge of wall


34


. Subject again to the roles of plate structures


30


and


32


being reversed, a global-heating gap-jumping operation is performed on structure


30


/


32


/


34


/


36


as generally described above for the process of FIG.


13


. The sealing material of wall


34


then moves vertically upward to jump the gap and hermetically seal the display.




One or both of backplate restricting structures


60


and


62


may be provided on backplate structure


30


in the situation where the roles of plate structures


30


and


32


are reversed. Similarly, one or both of faceplate restricting structures


64


and


66


may be provided on faceplate structure


32


in this situation. Because the roles of plates structures


30


and


32


are reversed, backplate restricting structures


64


and


66


restrict the lateral movement of the wall sealing material as it moves vertically, whether downward or upward, across the gap between outer wall


34


and faceplate structure


32


. Hence, the roles of backplate restricting structures


64


and


66


are basically reversed from the roles of faceplate restricting structures


60


and


62


, and vice versa.




Outer wall


34


can be initially joined to one of plate structures


30


and


32


with spacer walls


36


being initially joined to the other of structures


30


and


32


. Backplate structure


30


, now connected either to outer wall


34


or to spacer walls


36


, is aligned and tacked to faceplate structure


30


, now connected either to spacer walls


36


or to outer wall


34


. Depending on which of these two alternatives is utilized, a gap is present either between outer wall


34


and backplate structure


30


or between outer wall


34


and faceplate structure


32


.




Tacked, aligned structure


30


/


32


/


34


/


36


in the alternative described in the preceding paragraph can be oriented so that the gap runs along the then-existent bottom edge of outer wall


34


. A gravitational sealing operation is then performed as generally described above for the process of

FIG. 2

to close the gap and seal the flat-panel display. Alternatively, tacked structure


30


/


32


/


34


/


36


can be oriented so that the gap runs along the then-existent top edge of wall


34


. In that case, a global-heating gap-jumping operation as generally described above for the process of

FIG. 13

is utilized to close the gap and seal the display. One or more of seal-restricting structures


60


,


62


,


64


, and


66


can be utilized in either of these two variations.




As mentioned above, the gravitational heating operation of the invention can be performed by locally heating outer wall


34


rather than globally heating tacked structure


30


/


32


/


34


/


36


. Energy is then transferred locally to the sealing material of wall


34


so as to cause the wall sealing material to move vertically downward and seal plate structures


30


and


32


together through wall


34


. This variation can, of course, be employed when faceplate structure


32


is tacked to backplate structure


30


through selected ones or all of spacer walls


36


.




When global-heating gap-jumping is utilized to seal backplate structure


30


to faceplate structure


32


after tacking faceplate structure


32


to backplate structure


30


through selected ones or all of spacer walls


36


, it can sometimes be advantageous to substitute local heating of wall


34


for global heating of tacked structure


30


/


32


/


34


/


36


. That is, after faceplate structure


32


is tacked to backplate structure


30


through selected ones or all of spacer walls


36


so that a gap is present between backplate structure


30


and composite structure


32


/


34


/


36


, energy is transferred locally to the sealing material of outer wall


34


to cause the wall sealing material to jump the gap and hermetically seal backplate structure


30


to faceplate structure


32


through outer wall


34


. The wall sealing material moves vertically upward to meet backplate structure


30


in the preferred embodiment where backplate structure


30


is vertically on top in tacked structure


30


/


32


/


34


/


36


.




The local energy transferred to outer wall


34


to cause gap jumping when faceplate structure


32


is tacked to backplate structure


30


through selected ones or all of spacer walls


36


is typically light energy provided by a laser or focused lamp. As occurs when the present gravitational heating operation is performed by local energy transfer, the local energy can be microwave or IR energy provided from a source that suitably focuses the local energy. Further details on using local energy to hermetically seal a flat-panel display are presented in PCT Patent Publication WO 98/26440, cited above, the contents of which are incorporated by reference herein.




The above-mentioned variations dealing with role reversal and so on generally apply to situations in which local heating of outer wall


34


is utilized to seal backplate structure


30


to composite structure


32


/


34


/


36


after tacking backplate structure


30


to faceplate structure


32


through selected ones or all of spacer walls


36


. For example, the roles of plate structures


30


and


32


can be reversed so that outer wall


34


and spacer walls


36


are initially joined to backplate structure


30


rather than to faceplate structure


32


. Similarly, outer wall


34


can be initially joined to one of plate structures


30


and


32


while spacer walls


36


are initially joined to the other of structures


30


and


32


. Also, one or both of seal-restricting structures


60


and


62


can be provided on backplate structure


30


. One or both of seal-restricting structure


64


and


66


can be provided on faceplate structure


32


.




Spacer walls


36


in the internal spacer system can be replaced with spacers having shapes other than generally flat walls. Alternative shapes for such spacers include posts and combinations of spacer walls. As viewed perpendicular to plate structure


30


or


32


, a spacer post can, e.g., be of rectangular or circular shape. A spacer formed with multiple walls can, as viewed perpendicular to plate structure


30


or


32


, be shaped like a “T”, an “L”, an “H”, and so on.




Under certain circumstances, a flat-panel display manufactured according to the invention may not have an internal spacer system for maintaining a largely constant spacing between plate structures


30


and


32


and for preventing external forces, especially air pressure, from damaging the display. For instance, the display may be of sufficiently small lateral area that an internal spacer system is not necessary. Alternatively or additionally, plate structures


30


and


32


may be sufficiently strong on their own to withstand air pressure and other such external forces. See U.S. Pat. No. 5,964,630 for examples of flat-panel CRT displays not having internal spacer systems.




Should a spacer system not be present between plate structures


30


and


32


or, although present, not be utilized to produce a gap between outer wall


34


and either plate structure


30


or


32


prior to the gravitational heating or global-heating gap-jumping operation of the invention, the gap can be established by tack structures


44


when they are present. Alternatively, the gap can be established by another mechanism situated outside wall


34


. As an example, an alignment system can be utilized to clamp structures


30


and


32


so as to establish the gap and hold structures


30


and


32


in a substantially fixed position relative to each other during the gravitational heating or global-heating gap-jumping operation. An external spacer system consisting of one or more external spacers may be strategically placed between structures


30


and


32


outside wall


34


. The external spacer system may, as with tack structures


44


, remain in the sealed flat-panel display or may be removed from the display.




The invention can be employed to hermetically seal flat-panel devices other than displays. Examples include (a) microchannel plates in high-vacuum cells similar to photo multipliers, (b) micromechanical packages for devices such as accelerometers, gyroscopes, and pressure sensors, and (c) packages for biomedical implants. Various modifications and applications may thus be made by those skilled in the art without departing from the true scope and spirit of the invention as defined in the appended claims.



Claims
  • 1. A method comprising the steps of:positioning first and second plate structures generally opposite each other such that a restricting structure provided over the first plate structure lies between the plate structures and such that sealing material provided in a specified pattern over the second plate structure lies between the plate structures and is situated at a location close to the restricting structure; and heating the sealing material to seal the plate structures together such that the sealing material contacts the first plate structure close to the restricting structure and such that the restricting structure largely prevents the sealing material from spreading laterally over the restricting structure to contact the first plate structure laterally beyond the restricting structure, the restricting structure being sufficiently short as to be spaced apart from the second plate structure subsequent to the heating step.
  • 2. A method as in claim 1 wherein the sealing material does not spread significantly over the restricting structure during the heating step.
  • 3. A method as in claim 2 wherein the sealing material is situated sufficiently close to the restricting structure during the positioning step that the sealing material laterally contacts the restricting structure during the heating step.
  • 4. A method as in claim 1 wherein the restricting structure consists of material not significantly wettable by the sealing material.
  • 5. A method as in claim 1 wherein the restricting structure is largely of laterally annular shape, the sealing material contacting the first plate structure at a location largely outside the restricting structure during the heating step.
  • 6. A method as in claim 1 wherein:the positioning step entails positioning the first plate structure vertically below the second plate structure; and the sealing material moves vertically downward under gravitational influence during the heating step.
  • 7. A method as in claim 1 wherein the heating step comprises globally heating the sealing material, the plate structures, and the restricting structure.
  • 8. A method as in claim 7 wherein:the positioning step entails positioning the first plate structure vertically above the second plate structure such that a gap at least partially separates the sealing material from the first plate structure; and the sealing material jumps the gap during the heating step.
  • 9. A method as in claim 1 wherein the positioning step includes arranging for the plate structures to be spaced apart from each other in largely a fixed manner such that the plate structures are spaced apart from each other in largely that fixed manner during the heating step.
  • 10. A method as in claim 9 wherein the positioning step includes placing intermediate means, other than the sealing material or the restricting structure, between the plate structures such that the intermediate means contacts both plate structures.
  • 11. A method as in claim 1 wherein:the method further includes, prior to the positioning step, the step of providing a further restricting structure over the second plate structure such that the sealing material is situated over the second plate structure opposite a location close to the further restricting structure; and the further restricting structure largely prevents the sealing material from spreading laterally over the further restricting structure to contact the second plate structure laterally beyond the further restricting structure during the heating step.
  • 12. A method as in claim 1 wherein the second plate structure has (a) a sealing area which contacts the sealing material and is of a surface energy that promotes bonding of the sealing material to the sealing area and (b) a further area which laterally adjoins the sealing area and is of a surface energy that inhibits bonding of the sealing material to the further area.
  • 13. A method as in claim 1 wherein, after the heating step is completed, the sealing material extends continuously from each plate structure to the other plate structure.
  • 14. A method as in claim 1 wherein:an outer wall portion has opposite first and second edges respectively covered by first and second parts of the sealing material; and the outer wall portion is provided over the second plate structure prior to the positioning step such that the second part of the sealing material joins the second plate structure to the outer wall portion along its second edge.
  • 15. A method as in claim 1 wherein the plate structures are components of a flat-panel display.
  • 16. A method as in claim 15 wherein the flat-panel display is flat-panel cathode-ray tube display.
  • 17. A method as in claim 1 wherein the sealing material is largely of laterally annular shape.
  • 18. A method as in claim 1 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile shaped generally like a rectangle.
  • 19. A method as in claim 1 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile having (a) a first side that meets the first plate structure and (b) a second side that meets the second plate structure, extends generally parallel to the first side, and is shorter than the first side.
  • 20. A method as in claim 1 wherein, prior to the heating step, the sealing material has a vertical cross-sectional profile having a first side and a second side that meets the second plate structure, extends generally parallel to the first side, and is shorter than the first side.
  • 21. A method as in claim 20 wherein the vertical cross-sectional profile of the sealing material prior to the heating step is shaped generally like a trapezoid whose two parallel sides respectively constitute the aforementioned first and second sides.
  • 22. A method as in claim 21 wherein the trapezoid is an isosceles trapezoid.
  • 23. A method comprising the steps of:positioning first and second plate structures generally opposite each other such that a pair of restricting structures provided over the first plate structure lie between the plate structures and such that sealing material provided in a specified pattern over the second plate structure lies between the plate structures and is situated opposite a location between the restricting structures; and heating the sealing material to seal the plate structures together such that the sealing material contacts the first plate structure between the restricting structures and such that the restricting structures largely prevent the sealing material from spreading over the restricting structures to contact the first plate structure laterally beyond the restricting structures.
  • 24. A method as in claim 23 wherein the sealing material does not spread significantly over the restricting structures during the heating step.
  • 25. A method as in claim 24 wherein the sealing material is situated sufficiently close to the restricting structures during the positioning step that the sealing material laterally contacts at least one of the restricting structures during the heating step.
  • 26. A method as in claim 23 wherein the restricting structures consist of material not significantly wettable by the sealing material.
  • 27. A method as in claim 23 wherein the sealing material is largely of laterally annular shape.
  • 28. A method as in claim 27 wherein each restricting structure is largely of laterally annular shape.
  • 29. A method as in claim 23 wherein:the positioning step entails positioning the first plate structure vertically below the second plate structure; and the sealing material moves vertically downward under gravitational influence during the heating step.
  • 30. A method as in claim 23 wherein the heating step comprises globally heating the sealing material, the plate structures, and the restricting structures.
  • 31. A method as in claim 30 wherein:the positioning step entails positioning the first plate structure vertically above the second plate structure such that a gap at least partially separates the sealing material from the first plate structure; and the sealing material jumps the gap during the heating step.
  • 32. A method as in claim 23 wherein the plate structures are maintained in a largely fixed positional relationship to each other during the heating step.
  • 33. A method as in claim 23 wherein the positioning step includes arranging for the plate structures to be spaced apart from each other in largely a fixed manner such that the plate structures are spaced apart from each other in largely that fixed manner during the heating step.
  • 34. A method as in claim 33 wherein the arranging step includes placing intermediate means, other than the sealing material or the restricting structures, between the plate structures such that the intermediate means contacts both plate structures.
  • 35. A method as in claim 34 wherein the intermediate means comprises tack means through which the plate structures are coupled together at multiple locations spaced laterally apart along the plate structures.
  • 36. A method as in claim 34 wherein the sealing material is largely of laterally annular shape, the intermediate means comprising spacer means situated inside the sealing material.
  • 37. A method as in claim 23 wherein the positioning step includes arranging for spacer means to be situated between the plate structures so that the second plate structure and the sealing material are vertically spaced apart from the first plate structure along largely all of the sealing material prior to the heating step.
  • 38. A method as in claim 37 wherein the spacer means causes the plate structures to be spaced apart from each other in largely a fixed manner during the heating step.
  • 39. A method as in claim 23 further including, between the positioning and heating steps, the step of joining the sealing material to the first plate structure at multiple locations spaced laterally apart along the first plate structure.
  • 40. A method as in claim 39 wherein the joining step entails directing energy locally onto the sealing material at multiple laterally separated seal locations respectively corresponding to the multiple locations along the first plate structure.
  • 41. A method as in claim 23 wherein:the method further includes, prior to the positioning step, the step of providing a pair of further restricting structures over the second plate structure such that the sealing material is situated over the second plate structure opposite a location between the further restricting structures; and the further restricting structures largely prevent the sealing material from spreading laterally over the further restricting structures to contact the second plate structure laterally beyond the further restricting structures during the heating step.
  • 42. A method as in claim 23 wherein the second plate structure has (a) a sealing area which contacts the sealing material and is of a surface energy that promotes bonding of the sealing material to the sealing area and (b) a further area which laterally adjoins the sealing area and is of a surface energy that inhibits bonding of the sealing material to the further area.
  • 43. A method as in claim 23 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile shaped generally like a rectangle.
  • 44. A method as in claim 23 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile having (a) a first side that meets the first plate structure and (b) a second side that meets the second plate structure, extends generally parallel to the first side, and is shorter than the first side.
  • 45. A method comprising the steps of:positioning a first plate structure generally opposite a second plate structure such that sealing material provided in a specified pattern over the second plate structure lies between the plate structures, such that a gap at least partially separates the sealing material from the first plate structure, and such that spacer means (a) lies between the plate structures, (b) is largely laterally surrounded by the sealing material, and (c) is rigidly coupled to both plate structures at multiple locations spaced laterally apart along the plate structures; and transferring energy locally to the sealing material to cause the sealing material to close the gap and seal the plate structures together.
  • 46. A method as in claim 45 wherein the spacer means comprises multiple spacers spaced laterally apart from one another.
  • 47. A method as in claim 45 wherein the spacer means causes the plate structures to be spaced apart from each other in largely a fixed manner during the energy-transferring step.
  • 48. A method as in claim 45 wherein the energy comprises light energy.
  • 49. A method as in claim 45 wherein the first plate structure lies vertically below the second plate structure during the energy-transferring step such that the sealing material moves vertically downward under gravitational influence to contact the first plate structure during the energy-transferring step.
  • 50. A method as in claim 45 wherein the first plate structure lies vertically above the second plate structure during the energy-transferring step such that the sealing material moves vertically upward to bridge the gap during the energy-transferring step.
  • 51. A method as in claim, 50 wherein the gap has an average height of at least 25 μm.
  • 52. A method as in claim 45 wherein:the positioning step entails the positioning the plate structures such that a restricting structure provided over the first plate structure lies between the plate structures and such that the sealing material is situated at a location close to the restricting structure; and the sealing material contacts the first plate structure close to the restricting structure during the energy-transferring step and is largely prevented by the restricting structure from spreading laterally over the restricting structure to contact the first plate structure laterally beyond the restricting structure.
  • 53. A method as in claim 52 wherein:the method further includes, prior to the positioning step, the step of providing a further restricting structure over the second plate structure such that the sealing material is situated over the second plate structure opposite a location close to the further restricting structure; and the further restricting structure largely prevents the sealing material from spreading laterally over the further restricting structure to contact the second plate structure laterally beyond the further restricting structure during the energy-transferring step.
  • 54. A method as in claim 45 wherein:the positioning step entails positioning the plate structures such that a pair of restricting structures provided over the first plate structure lie between the plate structures and such that the sealing material is situated opposite a location between the restricting structures; and the sealing material contacts the first plate structure between the restricting structures during the energy-transferring step and is largely prevented by the restricting structures from spreading laterally over the restricting structures to contact the first plate structure laterally beyond the restricting structures.
  • 55. A method as in claim 45 wherein the sealing material is largely of laterally annular shape.
  • 56. A method comprising the steps of:positioning a first plate structure vertically below a second plate structure such that sealing material provided in a specified pattern over the second plate structure lies between the plate structures; and heating the sealing material so that it moves generally downward under gravitational influence to contact the first plate structure and seal the plate structures together, the first plate structure having (a) a sealing area which contacts the sealing material during the heating step and is of a surface energy that promotes bonding of the sealing material to the sealing area and (b) a further area which laterally adjoins the sealing area and is of a surface energy that inhibits bonding of the sealing material to the further area.
  • 57. A method as in claim 56 wherein the plate structures are maintained in largely a fixed positional relationship to each other during the heating step.
  • 58. A method as in claim 56 one wherein the heating step comprises globally heating the sealing material and the plate structures.
  • 59. A method as in claim 56 wherein the plate structures are components of a flat-panel display.
  • 60. A method as in claim 59 wherein the flat-panel display is a flat-panel cathode-ray tube display.
  • 61. A method comprising the steps of:positioning a first plate structure vertically below a second plate structure such that sealing material provided in a specified pattern over the second plate structure lies between the plate structures; and heating the sealing material so that it moves generally downward under gravitational influence to contact the first plate structure and seal the plate structures together, the second plate structure having (a) a sealing area which contacts the sealing material and is of a surface energy that promotes bonding of the sealing material to the sealing area and (b) a further area which laterally adjoins the sealing area and is of a surface energy that inhibits bonding of the sealing material to the further area.
  • 62. A method as in claim 61 wherein the first plate structure has (a) a sealing area which contacts the sealing material during the heating step and is of a surface energy that promotes bonding of the sealing material to the first plate structure's sealing area and (b) a further area which laterally adjoins the first plate structure's sealing area and is of a surface energy that inhibits bonding of the sealing material to the first plate structure's sealing area.
  • 63. A method as in claim 61 wherein the plate structures are maintained in largely a fixed positional relationship to each other during the heating step.
  • 64. A method as in claim 61 one wherein the heating step comprises globally heating the sealing material and the plate structures.
  • 65. A method as in claim 61 wherein the plate structures are components of a flat-panel display.
  • 66. A method as in claim 65 wherein the flat-panel display is a flat-panel cathode-ray tube display.
  • 67. A method comprising the steps of:positioning first and second plate structures generally opposite each other such that a restricting structure provided over the first plate structure lies between the plate structures, such that sealing material provided in a specified pattern over the second plate structure lies between the plate structures and is situated at a location close to the restricting structure, and such that intermediate means, other than the sealing material or the restricting structure, lies between the plate structures and contacts both plate structures; and heating the sealing material to seal the plate structures together such that the sealing material contacts the first plate structure close to the restricting structure and such that the restricting structure largely prevents the sealing material from spreading laterally over the restricting structure to contact the first plate structure laterally beyond the restricting structure.
  • 68. A method as in claim 67 wherein the intermediate means comprises tack means through which the plate structures are coupled together at multiple locations spaced laterally apart along the plate structures.
  • 69. A method as in claim 68 wherein the sealing material is largely of laterally annular shape, the tack means being situated outside the sealing material.
  • 70. A method as in claim 67 wherein the sealing material is largely of laterally annular shape, the intermediate means comprising spacer means situated inside the sealing material.
  • 71. A method as in claim 70 wherein the intermediate means further includes tack means through which the plate structures are coupled together at multiple locations spaced laterally apart along the plate structures.
  • 72. A method as in claim 67 wherein the sealing material is situated sufficiently close to the restricting structure during the positioning step that the sealing material laterally contacts the restricting structure during the heating step.
  • 73. A method as in claim 67 wherein:the positioning step entails positioning the first plate structure vertically below the second plate structure; and the sealing material moves vertically downward under gravitational influence during the heating step.
  • 74. A method as in claim 67 wherein the heating step comprises globally heating the sealing material, the plate structures, and the restricting structure.
  • 75. A method as in claim 74 wherein:the positioning step entails positioning the first plate structure vertically above the second plate structure such that a gap at least partially separates the sealing material from the first plate structure; and the sealing material jumps the gap during the heating step.
  • 76. A method as in claim 67 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile shaped generally like a rectangle.
  • 77. A method as in claim 67 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile having (a) a first side that meets the first plate structure and (b) a second side that meets the second side plate structure, extends generally parallel to the first side, and is shorter than the first side.
  • 78. A method comprising the steps of:positioning first and second plate structures generally opposite each other such that a first restricting structure provided over the first plate structure lies between the plate structures, such that a second restricting structure provided over the second plate structure lies between the plate structures, and such that sealing material provided in a specified pattern over the second plate structure lies between the plate structures, is situated at a location close to the first restricting structure, and is situated opposite a location close to the second restricting structure; and heating the sealing material to seal the plate structures together such that the sealing material contacts the first plate structure close to the first restricting structure, such that the first restricting structure largely prevents the sealing material from spreading laterally over the first restricting structure to contact the first plate structure laterally beyond the first restricting structure, and such that the second restricting structure largely prevents the sealing material from spreading laterally over the second restricting structure to contact the second plate structure laterally beyond the second restricting structure.
  • 79. A method as in claim 78 wherein the sealing material is situated sufficiently close to the restricting structures during the positioning step that the sealing material laterally contacts the restricting structures during the heating step.
  • 80. A method as in claim 78 wherein:the positioning step entails positioning the first plate structure vertically below the second plate structure; and the sealing material moves vertically downward under gravitational influence during the heating step.
  • 81. A method as in claim 78 wherein the heating step comprises globally heating the sealing material, the plate structures, and the restricting structures.
  • 82. A method as in claim 81 wherein:the positioning step entails positioning the first plate structure vertically above the second plate structure such that a gap at least partially separates the sealing material from the first plate structure; and the sealing material jumps the gap during the heating step.
  • 83. A method as in claim 78 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile shaped generally like a rectangle.
  • 84. A method as in claim 78 wherein, subsequent to the heating step, the sealing material has a vertical cross-sectional profile having (a) a first side that meets the first plate structure and (b) a second side that meets the second side plate structure, extends generally parallel to the first side, and is shorter than the first side.
US Referenced Citations (23)
Number Name Date Kind
1931311 Young Oct 1933 A
3777281 Hochuli Dec 1973 A
3874549 Hascoe Apr 1975 A
3879629 Durand Apr 1975 A
4021219 Stockdale et al. May 1977 A
4618801 Kakino Oct 1986 A
4683154 Benson et al. Jul 1987 A
5275328 Lodge et al. Jan 1994 A
5424605 Lovoi Jun 1995 A
5477105 Curtin et al. Dec 1995 A
5489321 Tracy et al. Feb 1996 A
5548181 Jones Aug 1996 A
5589731 Fahlen et al. Dec 1996 A
5693111 Kadowski et al. Dec 1997 A
5697825 Dynka et al. Dec 1997 A
5807154 Watkins Sep 1998 A
5820435 Cooper et al. Oct 1998 A
5827102 Watkins et al. Oct 1998 A
5964630 Slusarczuk et al. Oct 1999 A
5977706 Cho et al. Nov 1999 A
6036567 Watkins Mar 2000 A
6109994 Cho et al. Aug 2000 A
6139390 Pothoven et al. Oct 2000 A
Foreign Referenced Citations (1)
Number Date Country
WO 9826440 Jun 1998 WO
Non-Patent Literature Citations (5)
Entry
Branst et al. “The Challenge of Flat Panel Display Sealing,” Semiconductor Int'l .. Jan. 1996, pp. 109-112.
Jellison et al., “Laser Materials Processing at Sandia National Laboratories,” Applications of Lasers and Electro-optics, Conference, Oct. 17-20, 1994, sponsored by Dept. of Energy, 10 pages.
Tannas, Flat-Panel Displays and CRTs (Van Nostrand Reinhold), Section 79, 1985, pp. 217-221.
Zimmerman et al., “Glass Panel Alignment and Sealing for Flat-Panel Displays” Viewgraph Presentation, NCAICM Workshop, Contract No. F33615-94-C-1415, Nov. 30-Dec. 2, 1994, 29 viewgraphs.
Zimmerman et al., “Glass Panel Alignment and Sealing for Flat-Panel Displays,” Contract Summary, ARPA High Definition Systems Program, ARPA High Definition Information Exchange Conference, Apr. 30-May 3, 1995, 2 pages.