Patent Grant
7042156
This application is based on Japanese Patent Application No. 2002-310190 filed Oct. 24, 2002, the contents of which are incorporated hereinto by reference.
1. Field of the Invention
The present invention relates in general to a flat-panel display device, and more particularly to improvements in a structural arrangement for and a process of sealing the device.
2. Discussion of Related Art
There are known flat-panel display devices such as a plasma display panel (PDP) and a field emission display (FED) arranged to display a desired image. Such a flat-panel display device includes a pair of flat panels at least one of which is transparent and which cooperate to define therein an air-tight space in which a gas discharge is induced to generate a ultraviolet radiation, or a cathode and a fluorescent layer are provided so that the cathode generates an electron beam that excites the fluorescent layer to generate light. The image is formed with the ultraviolet radiation or the light. An example of this type of flat-panel display device is disclosed in “Advanced Technologies of Displays”, p.82–84, 101–106, Chizuka Tani, first print, first edition, Kyouritsu Publishing Company, Japan, Dec. 28, 1998.
The flat-panel display device of the type described above is used alone to display a single image, or used as each of unitary components of a so-called “tiled display” device, which uses, as the unitary components, a plurality of the flat-panel display devices that are arranged adjacent to each other and cooperate to form a large-sized screen parallel to a direction of arrangement of the flat-panel display devices. The tiled display device is required to have a spacing pitch or spacing distance between effective display areas of the adjacent flat-panel display devices, which is as small as possible, in order to improve a high degree of continuity of an image and thereby enhance a quality of the image displayed.
In the tiled flat-panel display device known in the art, however, a sealing portion is provided along the periphery or perimeter of each flat-panel display device, so that a center-to-center spacing distance between the picture elements in the adjacent flat-panel display devices tends to be considerably larger than a center-to-center spacing distance between the adjacent picture elements within each flat-panel display device. Accordingly, the known tiled flat-panel display device is not capable of displaying an image with a high degree of continuity of the image. Where the flat-panel display device is not used as each unitary component of the tiled display device, but is used alone, too, the provision of the sealing peripheral portion causes a similar problem, since it is generally desired to maximize a ratio of the size of the effective display surface area of the display device with respect to its overall external size, while minimizing the dimension of the peripheral sealing portion.
The present invention was made in view of the background art discussed above. It is a first object of the present invention to provide a flat-panel display device which has an increased ratio of the size of the effective display surface area to its overall external size. A second object of the invention is to provide a process of sealing the flat-panel display device along its periphery, so as to minimize the dimension of the peripheral sealing portion.
The first object indicated above may be achieved according to a first aspect of the present invention, which provides a flat-panel display device comprising:
a transparent first plate and a second plate which are disposed in parallel with each other and cooperate to define therebetween an air-tight space in which light is generated for emission through the first plate;
a sealing material for air-tightly sealing the air-tight space along a periphery of the first and second plates; and
metallic thin sheets bonded with the sealing material to end faces of the first and second plates such that the metallic thin sheets cover the end faces.
In the flat-panel display device constructed according to the first aspect of this invention, the metallic thin sheets are bonded with the sealing material to the end faces of the first and second plates, so as to cover the end faces, so that the air tightness of the air-tight space defined between the first and second plates is increased owing to a comparatively long sealing length along which the sealing material is provided on the end faces as well as in the peripheral portion of the air-tight space. This arrangement makes it possible to reduce a required dimension of a mass of the sealing material in the peripheral portion of the air-tight space, which dimension is measured in the direction parallel to the first and second plates. Accordingly, the required degree of air tightness of the air-tight space is obtained with a relatively small thickness of a mass of the sealing material existing on the end faces of the plates. The present arrangement is effective to minimize an amount of reduction of the size of an effective display surface area of the display device due to the presence of the sealing material, and an amount of increase of the overall external size of the display device due to the presence of the sealing material outside the first and second plates. Accordingly, the present flat-panel display device has a relatively high ratio of the effective display surface area to the overall external size. The metallic thin sheets may cover substantially entire areas of the end faces of the first and second plates, as well as the mass of the sealing material in the peripheral portion of the air-tight space. However, the metallic thin sheets need not cover substantially entire areas of the end faces, and an end portion of the end face of each of the two plates which is remote from the air-tight space may be exposed. The term “metallic thin sheets” is interpreted to include sheets or tapes having a thickness of not larger than 1 mm.
In a first preferred form of the first aspect of the invention, the flat-panel display device further comprises: a plurality of internal conductors disposed between the first and second plates, each of the plurality of internal conductors having one end located near the end faces of the first and second plates; and a plurality of lead conductors provided on surfaces of the metallic thin sheets which face the end faces of the first and second plates, the plurality of lead conductors being electrically connected to the internal conductors, respectively. In the present flat-panel display device, the internal conductors provided in the display device can be electrically connected to an control circuit through the lead conductors provided on the metallic thin sheets. Thus, the lead conductors facilitate electrical connection of the internal conductors to the control circuit. In the conventional flat-panel display device, the internal conductors are connected, at the peripheries of the first and second plates, to the conductors connected to the external control circuit. To this end, electrode terminals are required at the peripheries of the plates. The provision of these electrode terminals reduces the size of the effective display surface area of the display device. In the present flat-panel display device, the internal conductors are connected to the lead conductors when the metallic thin plates are bonded to the end faces of the first and second plates, so as to seal the air-tight space along the periphery of the display device. Accordingly, the present display device does not require the terminals to be provided outside the sealing portion, for electrical connection to the external control circuit. Thus, the metallic thin sheets make it possible to further increase the ratio of the effective display surface area of the display device to the overall external size, while minimizing the required dimension of the sealing portion in the direction parallel to the first and second plates.
In one advantageous arrangement of the flat-panel display device according to the first preferred form of the invention, each of the plurality of lead conductors has one end portion which extends in a direction substantially parallel to inner surfaces of the first and second plates, toward inner portions of the first and second plates, and each lead conductor is electrically connected at the above-indicated one end portion thereof to the corresponding one of the plurality of internal conductors. This arrangement does not require the internal conductors to be formed such that one end portion of each internal conductor is located on the end face of one of the first and second plates. Accordingly, the present arrangement facilitates electrical connection of the internal conductors with the lead conductors, even where one end of each internal conductor is located in the peripheral portion of the air-tight space.
In another advantageous arrangement of the flat-panel display device according to the first preferred form of the invention, each of the metallic thin sheets has a surface covered by a layer of a dielectric material, and the plurality of lead conductors are strips of an electrically conductive material formed on the layer of the dielectric material. In this flat-panel display device, short circuiting between the lead conductors is prevented by the dielectric layer formed on each metallic thin sheet.
In a further advantageous arrangement of the first preferred form of the invention, the flat-panel display device further comprises a plurality of external conductors which are provided on a back surface of the second plate and which are electrically connected to the plurality of lead conductors, respectively. In the present flat-panel display device, the internal conductors and the external conductors are electrically connected to each other through the lead conductors, by simply bonding together the first and second plates with the sealing material and bonding the metallic thin sheets to the end faces of the first plates with the sealing material.
In a still further advantageous arrangement of the flat-panel display device of the invention, each of the metallic thin sheets is an L-shaped sheet that is L-shaped in transverse cross section and consists of two portions one of which faces the end faces of the first and second plates and the other of which faces a back surface of the second plate, each of the plurality of lead conductors being provided on one surface of the L-shaped sheet and L-shaped following the above-indicated one surface of the L-shaped sheet. In this flat-panel display device, one end portion of each lead conductor is located on the back surface of the second plate, so that the lead conductor can be easily electrically connected to an external conductor, through the above-indicated end portion of the lead conductor on the back surface of the second plate. Further, the lead conductors are backed up and covered by the L-shaped metallic thin sheets, so that the portion of each lead conductor near the edge between the end face and the back surface of the second plate is protected by the metallic thin sheet against breakage or disconnection which would result in electrical discontinuity between the internal and external conductors.
In a second preferred form of the flat-panel display device according to the first aspect of the present invention, each of the metallic thin sheets includes an end-face portion covering the end faces of said first and second plates, and a back-surface portion which extends from the end-face portion and covers a back surface of the second plate, the back-surface portion being provided for pressing contact with a heat dissipating member fixed to a frame member when the flat-panel display device is attached to the frame member. In this form of the flat-panel display device, the heat dissipating member is installed on the display device such that the heat dissipating member is held in pressing contact with the back-surface portion of the metallic thin sheets, when the display device is fixed to the frame member. Where the present flat-panel display device is used as each of unitary components of a tiled display device, the heat dissipating member can be used even after the present display device whose service life has been reached is replaced by a new one. The conventional flat-panel display device has a heat dissipating member directly bonded to the back surface of the second plate, so that the display device must be replaced with a new one, together with the heat dissipating member bonded to the second plate. Where the present flat-panel display device is used alone, the display device is fixed to the frame member, for improving the ease of handling of the display device. Where the flat-panel display device is used as each of unitary components of a tiled display device, too, the individual display devices are fixed to respective local portions of the frame member such that the display surface areas of the display devices cooperate to provide a single flat large display surface area. In either of these two cases, the display device is fixed to the frame member to which the heat dissipating member is fixed, so that the heat dissipating member can be used with a newly installed display device by which the present display device has been replaced after its service life. Preferably, the heat dissipating member is elastically biased against the back-surface portion of the metallic thin sheets of the display device fixed to the frame member, under a biasing force of a suitable biasing means such as a spring provided on the frame member.
In a third preferred form of the first aspect of this invention, the flat-panel display device further comprises an electromagnetic-wave absorbing film which is formed on a front surface of the first plate and which is connected at a peripheral portion thereof to the metallic thin sheets. In the present flat-panel display device, the electromagnetic-wave absorbing film can be easily rounded through the metallic thin sheets. Preferably, the electromagnetic-wave absorbing film is a mesh of a metallic material bonded to the front surface of the first plate, or a transparent film of an electrically conductive material formed on the front surface of the first plate. In the former case, the mesh has a comparatively high value of electric conductivity, so that the mesh may be electrically connected at one portion or a few portions thereof to the metallic thin sheets. In the latter case, the transparent film of the electrically conductive material has a comparatively low value of electrical conductivity, so that the transparent film is required to be electrically connected at a relatively large number of portions thereof to the metallic thin sheets. The electromagnetic-wave absorbing film desirably has a surface area slightly smaller than that of the front surface of the first plate. In this case, each metallic thin sheet is preferably L-shaped in transverse cross section, and consists of two portions one of which faces the end faces of the first and second plates and the other of which faces the front surface of the first plate and at least partially overlaps with the electromagnetic-wave absorbing film. This arrangement does not require the electromagnetic-wave absorbing film to be bent at the periphery of the first plate, for electrically connection with the metallic thin sheets, and eliminates a problem of warpage of the electromagnetic-wave absorbing film at its peripheral portion, and a problem of distortion of an image displayed at the peripheral portion of the display device.
The flat-panel display device according to the first aspect of this invention is suitable used as each of unitary components of a large-sized tiled display device wherein a plurality of flat-panel display devices are arranged to provide a single flat display surface. Since the flat-panel display device of the present invention has a relatively large effective display surface area with respect to the overall external size, the tiled display device consisting of a plurality of the flat-panel display devices of the invention as the unitary components does not suffer from a large difference between the center-to-center pitch of picture elements within each flat-panel display device and the center-to-center pitch of picture elements within the adjacent flat-panel display devices. Accordingly, the tiled display device does not have visually disturbing or perceptible seams at the boundaries of the adjacent flat-panel display devices, and is capable of displaying a large-sized image with high quality.
The second object indicated above may be achieved according to a second aspect of the present invention, which provides a process of manufacturing a flat-panel display device comprising a transparent first plate and a second plate which are disposed in parallel with each other and cooperate to define therebetween an air-tight space which is air-tightly sealed along a periphery of the first and second plates and in which light is generated for emission through the first plate, the process comprising the steps of:
applying a sealing material to end faces of the first and second plates such that a peripheral portion of the air-tight space is filled with a mass of the sealing material;
forcing metallic thin sheets onto the end faces of the first and second plates such that the metallic thin sheets cover the end faces; and
heating the metallic thin sheets and the sealing material to fire the sealing material for air-tightly bonding together the first and second plates, and bonding the metallic thin sheets to the end faces through the sealing material, to thereby air-tightly seal said air-tight space along its periphery.
In the process of manufacturing the flat-panel display device according to the second aspect of this invention, the sealing material applied to the end faces of the first and second plates is squeezed between the end faces and the metallic thin sheets when the metallic thin sheets are forced onto the end faces. When the metallic thin sheets and the sealing material are subsequently heated, the sealing material is fluidized, and the fluidized sealing material flows and further spreads in a gas between the metallic thin sheets and the end faces, owing to a capillary phenomenon, so that the end faces of the first and second plates are covered by the metallic thin plates bonded thereto with the sealing material, and the air-tight space is air-tightly sealed along its periphery, over a relatively large sealing length along which the sealing material is provided on the end faces as well as in the peripheral portion of the air-tight space. Accordingly, the present process makes it possible to reduce the required dimension of a mass of the sealing material present in the peripheral portion of the air-tight space as measured in the direction parallel to the inner surfaces of the first and second plates, and the required thickness of a mass of the sealing material on the end faces of the plates, while assuring a required degree of air tightness of the air-space. Thus, the mass of the sealing material in the peripheral portion of the air-tight space does not cause a considerable decrease of the size of the effective display surface area of the display device, and the mass of the sealing material on the end faces does not cause a considerable increase of the overall external size of the display device. Accordingly, the flat-panel display device manufactured by the process of the invention has a comparatively high ratio of the size of the effective display surface area to the overall external size.
In one preferred form of the process according to the second aspect of this invention, each of the metallic thin sheets is provided with a plurality of perforations through which an excess portion of a mass of the sealing material initially existing between the metallic thin sheet and the end faces of the first and second plates is moved outwardly of the each metallic thin sheet. If the sealing material is applied to the end faces of the first and second plates in an excessively large amount, the excess portion of the mass of the sealing material existing between each metallic thin sheet and the end faces of the plates can be moved through the perforations outwardly of the metallic thin sheet, when the metallic thin sheet is forced on the end faces during heating of the sheet and the sealing material for sealing the air-tight space. Accordingly, the perforations function to optimize the amount of the sealing material staying between the end faces and the metallic thin sheet, thereby minimizing an amount of increase of the overall external size of the display device due to an excessively large thickness of the sealing material existing between the end faces of the first and second plates and the metallic thin sheets.
In one advantageous arrangement of the above-indicated preferred form of the second aspect of the invention, the process further comprises a step of removing the excess portion of the mass of the sealing material which has been moved through the perforations outwardly of each metallic thin sheet, after the step of heating the metallic thin sheets and the sealing material to fire the sealing material. An increase of the overall external size of the display device due to an excessively large amount of the sealing material moved through the perforations onto the metallic thin sheets can be prevented by removing the mass of the sealing material staying on the metallic thin sheets after the heating step.
In another preferred form of the second aspect of the invention, the step of applying the sealing material to the end faces of the first and second plates and the step of forcing the metallic thin sheets on the end faces are performed substantially concurrently by forcing the metallic thin sheets each coated on one surface thereof with the sealing material onto the end faces of the first and second plates. In this form of the process, the end faces of the first and second plates are coated with the sealing material when the metallic thin sheets are forced onto the end faces. Further, the dimension of the mass of the sealing material existing in the peripheral portion of the air-tight space in the direction parallel to the plates can be made smaller than where the sealing material is directly injected into the peripheral portion of the air-tight space.
In a further preferred form of the second aspect of the invention, the process further comprises a step of forming a layer of a dielectric material on one surface of each of the metallic thin sheets, and a plurality of strips of an electrically conductive material on the layer of the dielectric material, before the step of applying the sealing material, the strips being fired into a plurality of lead conductors in the step of heating the metallic thin sheets and the sealing material. In this form of the process, the lead conductors for electrically connecting internal conductors to an external device can be formed when the strips of the electrically conductive material are fired in the step of heating the metallic thin sheets forced onto the end faces of the first and second plates. Further, the thus formed lead conductors can be electrically connected to the internal conductors when the metallic thin sheets are forced onto the end faces. The layer of the dielectric may be fired before the strips of the electrically conductive material are formed on the fired dielectric layer. However, it is possible to first coat each metallic thin sheet with a paste of the dielectric material, then apply a paste of the electrically conductive material in a predetermined pattern of strips to a dried layer of the paste of the dielectric material, and finally fire the pastes of the dielectric material and the electrically conductive material to concurrently form the dielectric layer and the lead conductors.
The above and other objects, features, advantages and technical and industrial significance of the present invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings, in which:
There will be described in detail some embodiments of this invention, referring to the accompanying drawings.
Referring first to the perspective view of
Each of the front and back plates 12, 14 used for the PDP 10 is formed of a suitable transparent glass material such as a soda-lime glass, which has a softening point of about 700° C. These front and back plates 12, 14 are square plates having four sides each having a length of about 192 mm, and a uniform thickness within a range of 1.1–2.8 mm, for instance, about 1.8 mm. Each of the metallic tapes 16 is formed of an alloy 42-6 (ASTM F31-68) which has coefficient of thermal expansion close to that of a glass, a thickness within a range of 50–200 μm, for example, a thickness of about 100 μm, and a width and a length determined depending upon the dimensions of each end face of the PDP 10, for example, a thickness equal to a sum of the thickness values of the two plates 12, 14 (namely, within a range of 2.2–5.6 mm, for example, about 3.6 mm), and a length of about 192 mm which is equal the length of each side of the plates 12, 14. In the present embodiment, the four metallic tapes 26 each having the length equal to that of each side of the plates 12, 14 are separately bonded to the respective four end faces of the PDP 10. The front plate 12 functions as a first flat plate, while the back plate 14 functions as a second flat plate.
Referring next to the partly cut-away perspective view of
Between the upper end faces of the partition walls 22 on the back plate 14 and the inner surface of the font plate 12, there is formed a grid member 20 in the form of a grid or lattice consisting of first elongate walls and second elongate walls that are perpendicular to each other, such that the first elongate walls extend in the direction of extension of the partition walls 22. Thus, the partition walls 22 and the grid member 20 are formed within the air-tight space between the front and back plates 12, 14. The front and back plates 12, 14 are bonded together by the partition walls 22 and the grid member 20 formed on the partition walls 22.
The inner surface of the back plate 14 is covered over a substantially entire area thereof by an undercoat 26 formed of a low-alkali glass or a non-alkali glass. On this undercoat 26, a plurality of individual writing electrodes 28 are formed of silver by a thick-film forming technique, so as to extend in the longitudinal direction of the partition walls 22, such that the individual electrodes 28 are aligned with the respective discharge channels 24, and each electrode 28 is interposed between the adjacent partition walls 22. These individual electrodes 28 are covered by an overcoat 30 formed of a low-softening-point glass and an inorganic filler such as white titanium oxide (titania). The partition walls 22 are formed on the overcoat 30.
The inner surface of the overcoat 30 and the side surfaces of the partition walls 22 are covered by fluorescent layers 32 which correspond to the respective discharge channels 24. The adjacent three fluorescent layers 32 are formed of respective fluorescent materials that are excited by a ultraviolet radiation, to generate respective red (R), green (G) and blue (B) lights, respectively. The fluorescent layers 32 have suitable thickness values that are selected within a range of about 10–20 μm, depending upon the colors of the lights generated. Thus, the adjacent discharge channels 24 are provided with the fluorescent layers 32 of the respective three different colors (R, G, B). The undercoat 26 and the overcoat 30 are provided to prevent a reaction between the individual electrodes 28 formed of silver and the back plate 14, and contamination of the fluorescent layers 32.
On the inner surface of the front plate 12, there are formed a plurality of parallel partition strips 34 aligned with the respective partition walls 22. The partition strips 34 are formed of a material similar to that of the partition walls 22, and have a thickness of about 20–50 μm, for example. The partition strips 34 formed on the inner surface of the front plate 12 are spaced from each other by parallel fluorescent strips 36 each interposed between the adjacent strips 34. Each of the fluorescent strips 36 has a thickness within a range of about 5–15 μm. The adjacent three fluorescent strips 36 generate respective lights of the same colors as those generated by the corresponding fluorescent layers 36 formed in the respective discharge channels 24. The thickness of the partition strips 34 is determined to be larger than that of the fluorescent strips 36, in order to prevent the grid member 20 from contacting the fluorescent strips 36.
Referring further to the partly cut-away perspective view of
The dielectric core structure 38 has a thickness within a range of about 30–50 μm, for example, about 40 μm, and has first and second partition walls corresponding to the above-described first and second elongate walls of the grid member 20. These partition walls have a width almost equal to that of the partition walls 22, or slightly larger than that of the partition walls 22 by a suitable amount of alignment margin. For instance, the width of the partition walls of the core structure 38 is selected within a range of about 100–150 μm. The core structure 38 is formed by a thick-film forming technique of a dielectric composition including a low-softening-point glass such as PbO—B2O3—SiO2—Al2O3—ZnO—TiO2, and a ceramic filler such as alumina.
The conductive pattern 42 is formed by a thick-film forming technique, of an electrically conductive composition including silver (Ag), chromium (Cr) or cupper (Cu) as an electrically conductive material, and has a thickness of about 5–10 μm, for example. The conductive pattern 42 includes a plurality of conductor portions 50 formed on the second partition walls of the core structure 38, extending in a direction perpendicular to the longitudinal direction of the partition walls 22, that is, extending in a direction perpendicular to the longitudinal direction of the individual electrodes 28. The conductor portions 50 have a width of about 50–80 μm, for example.
Each of the conductor portions 50 has a plurality of lugs 52 which are spaced apart from each other in its longitudinal direction (its direction of extension) and which protrude in one of opposite directions parallel to its direction of width, such that the directions of protrusion of the lugs 52 of the adjacent two conductor portions 50 are opposite to each other. Each of the lugs 52 has an end portion 48 covering a part of the corresponding side surface of the partition wall of the dielectric core structure 38. The end portions 48 of the two lugs 52 of the adjacent two conductor portions 50 are opposed to each other, and provide a pair of mutually opposed portion 48 which serve as holding electrodes or scanning electrodes, as described below. Each lug 52 or holding electrode 48 has a width dimension of about 100 μm, for example, in the longitudinal direction of the conductor portion 50, and a height dimension almost equal to the thickness of the grid member 20, that is, a height dimension within a range of about 30–50 μm, for example, 50 μm. Thus, the holding electrodes 48 of the lugs 52 of each conductor portion 50 cover a part of the side surface of the corresponding partition wall of the dielectric core structure 38. In the present embodiment, the conductor portions 50 of the conductor pattern 42 function as internal conductors, and include terminal portions located at the periphery of the front and back plates 12, 14. As shown in
The covering dielectric layer 44 described above has a thickness within a range of about 10–30 μm, for example, 20 μm, and is formed by a thick-film forming technique of a low-softening-point glass such as PbO—B2O3—SiO2—Al2O3—ZnO—TiO2. The covering dielectric layer 44 is provided to store a charge on it surface, for permitting an AC discharge between the holding electrodes 48, and to prevent exposure of the holding electrodes 48, for thereby reducing a change of the atmosphere within the discharge channels 24 due to a gas emitted from the holding electrodes 48.
The protective film 46 also described above has a thickness of about 0.5 μm, for example, and is formed by a thin-film or thick-film forming technique of a composition whose major component is MgO, for example. The protective film 46 is provided to prevent sputtering of the covering dielectric layer 44 due to discharge gas ions. Since the protective film 46 is formed of a dielectric material having a high secondary-emission coefficient, the protective film 46 substantially functions as a discharging electrode.
In the PDP 10 having an electrode arrangement described above, all pairs of the two mutually opposed holding electrodes 48, which pairs are spaced from each other in the longitudinal direction of the conductor portions 50, are sequentially scanned by applying an alternating current pulse to one of the two holding electrodes 48 of each pair, while the selected individual writing electrodes 28 corresponding to the picture elements to be activated according to display data indicative of an image to be displayed are energized with alternating current pulses in synchronization with the scanning operation of the holding electrodes 48. As. a result, a discharge takes places between the energized individual writing electrode 28 and one of the two holding electrodes 48, as indicated by arrow A in
When the discharge takes place between the mutually opposed holding electrodes 48, 48, the ultraviolet radiation generated by the discharge propagates beyond the holding electrodes 48 in the longitudinal direction of the discharge channel 24 parallel to the partition walls 22. Accordingly, the parts of the fluorescent layer 32 and fluorescent strip 36 which are located outside the spacing between the holding electrodes 48 are also excited by the ultraviolet radiation, to generate lights. In the present PDP 10, each picture element or cell is defined by the adjacent partition walls 22, in the direction perpendicular to the longitudinal direction of the partition walls 22 (namely, perpendicular to the plane of
Referring back to
Generally, a degree of air tightness of an air-tight space increases with a sealing depth as represented by a dimension of a mass of a sealing material which fills the peripheral portion of the air-tight space. In the present PDP 10 wherein the sealing material 56 is interposed between the metallic tape 16 and the end faces 54 of the front and back plates 12, 14, the air tightness is determined by not only the above-indicated sealing depth but also a total length of the widthwise opposite end portions of the metallic tape 16, which total length is almost equal to a sum of the thickness values of the front and back plates 12, 14. Namely, the air tightness of the air-tight space between the front and back plates 12, 14 of the present PDP 10 is increased by the presence of the above-indicated front and back end portions of the sealing material 56 interposed between the metallic tape 16 and the end faces 54, in addition to the intermediate portion of the sealing material 56. In this arrangement, therefore, the required sealing depth can be reduced, and the size “m” of the non-display surface area can be reduced, while maintaining the desired degree of air tightness of the air-tight space. Accordingly, the present PDP 10 has an increased ratio of the size of the effective display surface area to the overall external size. Therefore, the use of the present PDP 10 as each of the unitary components of a large-sized tiled flat-panel display device permits this tiled display device to have an accordingly increased ratio of the effective display surface area to the overall external size, so that the tiled flat-panel display device is capable of displaying a large-sized image with high quality, with substantially no visually perceptible seams between the adjacent PDPs 10. Further, the large-sized tiled flat-panel display device can be manufactured at a relatively low cost.
The PDP 10 is manufactured by forming the front plate 12, the back plate 14 and the grid member 20, assembling these members 12, 14, 20 into a pre-cursor of the PDP 10, and sealing the pre-cursor along its perimeter. A process of sealing the assembled pre-cursor of the PDP 10 according to the principle of this embodiment of the invention will be described by reference to the flow chart of
Initially, step 60 is implemented to prepare four metallic tapes 16 (one of which is shown in
In the following step S70, the metallic tapes 16 are attached under pressure to the respective four end faces of a prepared assembly of the front and back plates 12, 14 and the grid member 20.
Then, step 72 is implemented to heat the metallic tapes 16 at a suitable temperature selected depending upon the specific composition of the glass frit 66, within a range of about 400–500° C., for example, at 450° C., for softening and fluidizing the glass frit 66 so that the a fluidized mass of the glass frit 66 located near the end faces 54 flows into the peripheral portion of the air-tight space between the front and back plates 12, 14. Subsequently, the metallic tapes 16 and the glass frit 66 are cooled in air, so that the glass frit 66 is cured. Thus, the air-tight space between the front and back plates 12, 14 is sealed by the sealing material 56 in the form of the glass frit 66 which exists not only in the peripheral portion of the air-tight space, but also between the metallic tapes 16 and the end faces 54 of the plates 12, 14, as shown in
There will next be described other embodiments of this invention. In the following embodiments, the same reference signs as used in the first embodiment described above will be used to identify the functionally corresponding elements or process steps, which will not be described in detail.
Referring to the perspective view of
The assembly of the front and back plates 12, 14 and the grid member 20 is sealed along its periphery with the metallic tapes 74, as indicated in the fragmentary cross sectional view of
In the present second embodiment, therefore, an excess portion of the glass frit 66, if the glass frit 66 is applied to the metallic tape 74 in an excessively large amount, is moved through the perforations 76, so as to stay on the outer surface of the metallic tape 74, so that only a required amount of the sealing material 56 (glass frit 66) exists in the peripheral portion of the air-tight space between the front and back plates 12, 14 and between the metallic tape 74 and the end faces 54. Thus, the use of the metallic tapes 74 having the perforations 76 is effective to prevent an increase in the external size of the PDP 10 due to an excessively large amount of the sealing material 56 between the metallic tapes 74 and the end faces 54. It is noted that the mass of the sealing material 56 (glass frit 66) left on the outer surfaces of the metallic tapes 74 is removed by grinding or any other suitable method, after the metallic tapes 74 and the glass frit 66 are subjected to the heating or firing operation.
The second embodiment uses a metallic thin sheet in the form of a metallic tape 84 which is L-shaped in transverse cross section, as shown in
As shown in the perspective view of
The sealing operation using the metallic tapes 84 described above is performed as illustrated in the flow chart of
In the following step 96, the dielectric layer 86 is formed on the inner surface of the L-shaped metallic tape 84, as shown in
In the next step 98, the lead conductors 88 are formed on the dielectric layer 86, as shown in
Then, step 100 is implemented to apply masses of a paste 102 of an electrically conductive material to the respective two portions of each lead conductor 88, which two portions correspond to the positions at which the electrically conductive bodies 90, 92 described above are eventually formed, as shown in
Referring next to the fragmentary perspective view of
Referring to
Reference is now made to the perspective view of
In the present embodiment wherein the heat dissipating member 116 is fixed to the frame member 121, without direct connection of the heat dissipating member 116 with the back plate 14, the heat dissipating member 116 may be used with the new PDP 10 by which the present PDP 10 has been replaced after its served life. Although the heat dissipating member 116 is not directly connected to the back plate 14, the generated heat can be efficiently dissipated through the heat dissipating member 116 fixed to the frame member 121. In the present embodiment, the frame member 121 is provided with a suitable mechanism to elastically bias the heat dissipating member 116 against the back plate 14, for holding the heat dissipating member 116 in abutting contact with the back plate 14 with a large area of surface contact therebetween.
The perspective view of
Referring next to the perspective view of
In the present eighth embodiment, the end portions of the end faces 54 at the four corner portions of the front and back plates 12, 14 are covered by the corner protective lugs 128, so that the air tightness at the corner portions is improved than in the first embodiment using the metallic tapes 16, for example. Where a small gap is left between the corner protective lugs 128 and the end portions of the tape sections 127b, the gap accommodates some distance of displacement of the metallic sheet assembly 126 due to thermal expansion during heating thereof, relative to the front and back plates 12, 14 which are formed of a glass composition and held substantially stationary. In the present embodiment, the corner protective lugs 128 and the end portions of the tape sections 127b have flat end faces, as shown in
The metallic sheet assembly 126 may be used in place of the metallic tapes 16 and the metallic plate 120, in the embodiment of
The air-tight space between the front and back plates 12, 14 is air-tightly sealed with the metallic tape 130, as shown in the fragmentary cross sectional view of
Referring to
In the ninth embodiment of
Referring to
While the preferred embodiments of the present invention have been described above in detail by reference to the drawings, it is to be understood that the invention may be otherwise embodied.
While the illustrated embodiments of the invention which have been described are applied to the color plasma display panel (PDP 10 of AC type and the process of sealing the PDP 10, the principle of the present invention is equally applicable to any type of flat-panel display device which is sealed along its periphery, irrespective of the specific electrode arrangement. For instance, the present invention is applicable to a monochromatic PDP of AC type, an FED, a SED, a PDP of conventional 3-electrode surface discharge type, and any other type of flat-panel display device which may or may not be provided with a grid member like the grid member 20, 104, 108 used in the illustrated embodiments.
The PDP 10 according to the illustrated embodiments is a full-color display device provided with the fluorescent layers 32 and fluorescent strips 36 corresponding to the primary three colors. However, the principle of this invention is equally applicable to a flat-panel display device provided with fluorescent layers corresponding to one color or two colors, and a flat-panel display device wherein the fluorescent layers are provided on only one of the front and back plates 12, 14.
Although the metallic tapes 16, etc. used in the illustrated embodiments have a thickness within a range of about 50–200 μm, thin metallic sheets having a larger thickness (e.g., about 1 mm) than the metallic tapes may be attached to the end faces 54 of the front and back plates 12, 14 of the PDP 10. The thickness of the thin metallic sheets is determined depending upon the required degree of air tightness of the air-tight space of the display device, the required ease of handling of the sheets, and the tolerable maximum dimension of the non-display surface area of the display device.
In the illustrated embodiments, the metallic tapes 16, etc. are coated with the glass frit 66, and the glass frit 66 is calcined before the metallic tapes are attached to the end faces 54. However, the end faces 54 may be coated with the glass frit 66 before the metallic tapes are attached to the end faces 54.
While the metallic tapes 16, etc. used in the illustrated embodiments are formed of an alloy 42-6 (ASTM F31-68), the metallic tapes may be formed of any other metallic material which has a coefficient of thermal expansion close to that of the material of the front and back plates 12, 14, namely, a glass having a low softening point.
It is to be understood that the present invention may be embodied with various other changes, modifications and improvements, which may occur to those skilled in the art, without departing from the spirit and scope of the invention defined in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-310190 | Oct 2002 | JP | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20040119397 A1 | Jun 2004 | US |
