Patent Application
20060033419
The present invention relates to an image display device which makes use of the emission of electrons in a vacuum which is formed between a face substrate and a back substrate, and more particularly to an image display device having a prolonged lifetime which can maintain a parallelism of both substrates at a high level and, at the same time, can ensure a mechanical strength of a panel and the realization of large-sizing of a display size and a high quality display and a manufacturing method thereof.
As a display device which exhibits the high brightness and the high definition, color cathode ray tubes have been popularly used conventionally. However, along with the recent request for the higher quality of images of an information processing equipment or television broadcasting, the demand for planar displays (panel displays) which are light-weighted and require a small space while exhibiting the high brightness and the high definition has been increasing.
As typical examples, liquid crystal display devices, plasma display devices and the like have been put into practice. Further, particularly, as display devices which can realize the higher brightness, various types of planar display devices have been put into practice. Here, these planar display devices include an electron emission type display device or a field emission type display device as a display device which utilizes an emission of electrons from electron sources into a vacuum or an organic EL display which exhibits the low power consumption or the like.
Among such planar display devices, as the above-mentioned field emission type display device, there have been known a display device having the electron emission structure which was invented by C. A. Spindt et al, a display device having an electron emission structure of metal-insulator-metal (MIM) type, a display device having an electron emission structure which utilizes an electron emission phenomenon based on a quantum theory tunneling effect (also referred to as “a surface conduction type electron source”), and a display device which utilizes an electron emission phenomenon which a diamond film, a graphite film, carbon nanotubes or the like possesses.
Among these panel type display devices, the field emission type display is formed by laminating a face substrate which is provided with anode electrodes and phosphor layers on an inner surface thereof and a back substrate on which field-emission-type cathodes and control electrodes to each other with a gap of, for example, 0.5 mm or more, and these substrates are hermetically sealed to form a panel, and a sealed space which is defined between two substrates of the panel is held at a pressure lower than an atmospheric pressure of an ambient field or is evacuated into a vacuum.
Recently, as the field-emission type electron sources which constitute the cathodes of the planar display of this type, the use of carbon nanotubes (CNT) has been studied. The carbon nanotubes are formed by fixing a carbon nanotube aggregate which is formed by gathering a large number of extremely fine needle-like carbon compounds to the cathode electrode.
By applying an electric field to the cathode electrode having the carbon nanotubes, it is possible to allow the carbon nanotubes to emit electrons of high density with high efficiency and the phosphor is energized with these electrons thus providing various types of display devices or the flat panel display capable of displaying images or the like which exhibit the high brightness. This type of display device is disclosed in Japanese Patent Laid-open Hei11 (1999)-317164 (patent literature 1) and Japanese Patent Laid-open Hei8 (1996)-83579 (patent literature 2), for example.
In the drawing, numeral 5 indicates a group of electron emission elements and numeral 6 indicates image forming members.
In this manner, the patent literature 1 discloses the constitution in which the spacers 4 which constitute the support columns are arranged between the face substrate 1 and the back plate 2 so as to uniformly maintain a distance between the face substrate 1 and the back plate 2 over the whole surfaces of the substrates.
For example, as the image forming member 6, the constitution which provides an anode electrode and a phosphor layer on the face substrate has been known. Further, as a group of the electron emission elements 5, there has been generally known the structure which provides a cathode line, a field-emission-type electron source which is electrically connected with the cathode line and is formed for every pixel, and a grid electrode which is arranged close to the field-emission-type electron source in an electrically insulated manner and is formed for every pixel to the back substrate or the like.
With respect to the above-mentioned panel display which is constituted of two substrates, the plasma display (PDP) and the panel display having the metal-insulator-metal type electron sources (MIM-Display) also have the substantially equal constitution. Hereinafter, although the invention will be explained by taking the field-emission-type display device as an example, the invention is also applicable to the PDP and the MIM-Display in the substantially same manner. Further, the invention is also applicable to the display which uses the surface conduction elements (SED) in the substantially same manner.
Further, as a related art relevant to this type of panel display, besides the constitution described in the above-mentioned patent literature 1, patent literature 2, for example, discloses the constitution in which, stacked adhesion portions which are formed of a frit glass layer—a metal back layer—a frit glass layer on a black matrix BM on a phosphor screen of a face substrate, and a frit glass on the stacked adhesion portions is melted to fix spacers thus achieving the prevention of the peeling of the metal back layer and the prevention of positional displacement of the spacers.
In the above-mentioned planar display device, the electrons emitted from the electron sources impinge on the phosphor body which constitutes the anode after passing through apertures formed in the control electrode and excite the phosphor body to emit light thus performing the display. Such an image display device provides the planar display which possesses excellent properties such as the high brightness and the high definition, is light-weighted and requires a small space.
However, in spite of such excellent structure, the planer image display device has the following drawbacks to be overcome. In the flat panel displays which use a cold cathode as an electron source including the display devices disclosed in the above-mentioned patent literatures 1 and 2, it is difficult to hold and fix the distance holding members (hereinafter referred to as spacers) arranged in the inside of a display region between both substrates in a state that the spacers are set free from the positional displacement and the inclination and hence, it is difficult to maintain the parallelism of both substrates and, at the same time, it is also difficult to ensure a sufficient panel strength.
Further, the conventional flat panel display has a drawback that the spacers are damaged and the electrodes or the like are damaged due to the damaged spacers. Further, in the conventional flat panel display, by adding a step to fix the spacers, there arises a possibility that cracks or leaks occur at hermetically sealed portions. There has been a demand for a technique which can overcome such drawbacks.
To fix the spacers and both substrates, in general, frit glass which is equal to the frit glass used as a material of the hermetic sealing material is used. In the crystallized frit glass, the crystallization progresses due to heating for a long time, and physical property values such as the thermal expansion coefficient and the like are changed whereby there arises a possibility that cracks occur due to an impact or the like and, at the same time, the hermetic sealing is damaged and hence, leaking is generated.
Further, the amorphous frit glass is softened due to the reheating temperature. Accordingly, the spacers which are once fixed by softening suffer from the positional displacement or the inclination whereby it is difficult to allow the amorphous frit glass to hold and fix the spacers at desired positions with high accuracy. Further, when the amorphous frit glass is used, also due to the generation of the deflection of the substrate or the like, it is difficult to maintain the parallelism of both substrates and to ensure the panel strength. Further, there also arises a drawback that spacers are damaged.
On the other hand, in the constitution which selectively uses plural kinds of frit glasses having different softening temperatures for fixing the spacers as disclosed in the patent literature 1, in general, the frit glasses have properties which exhibit softening gradually depending on kinds thereof. For example, the softening starts from a temperature approximately 50° C. lower than a nominal value and hence, the fluctuation of temperature is taken for granted.
Accordingly, even when the plural kinds of frit glasses whose softening temperature difference is approximately 50° C. or less are selectively used, it is almost impossible to hold the spacers in a state where the spacers are practically set free from the positional displacement and the inclination. Further, it is practically impossible to selectively use the plural kinds of frit glasses whose softening temperature difference exceeds 50° C. Accordingly, there has been a demand to cope with such drawbacks.
Further, with respect to the constitution disclosed in patent literature 2 which provides the stacked adhesion portions formed of the frit glass layer—the metal back layer—the frit glass layer on the black matrix BM of the phosphor screen, since the metal back layer is interposed between the frit glass layers, the upper and lower frit glass layers are difficult to melt, whereby there has been a demand for further enhancement with respect to the reliability of holding spacers.
Further, in the related art which includes patent literature 2, jigs or the like are indispensable for holding spacers at the time of adhering and fixing the spacers and holding the spacers during the manufacturing steps after such adhering and fixing, this has brought about drawbacks that spacers, electrodes and the like are damaged or the operational efficiency is lowered during mounting or dismounting of the jigs or the like.
The invention provides an image display device and a manufacturing method thereof which can overcome the above-mentioned drawbacks, and can ensure a panel strength while holding the parallelism between both substrates by ensuring the fixing of spacers, can realize a large-sized display and a high quality display, and can also prolong a lifetime thereof.
To overcome the above-mentioned object, the invention is characterized by the constitution which fixes spacers to a substrate using the composite fixing structure by way of fixing materials and the arrangement of spacers.
Due to such a constitution, it is possible to obtain the reliable fixing of the spacers thus ensuring the parallelism of both substrates and the strength of the panel.
The invention has the following advantages.
(1) In the invention, it is possible to surely adhere and fix the spacers and both substrates and hence, a distance between both substrates can be held at a desired value by the cooperation of the spacers and a frame. Further, the invention can also enhance a mechanical strength of a panel. Still further, the invention can realize the large-sized display and the high-quality display, leading a display device with prolonged lifetime.
(2) With the use of the combination of fixing by fusion and fixing by dissolution, the invention can surely adhere and fix the spacers and the substrates and, at the same time, can prevent the occurrence of damages on electrodes and the like thus realizing the electrodes or the like which exhibit high quality and high performance.
(3) The invention uses the combination of fixing by fusion and fixing by dissolution and hence, the spacers and the substrates can be surely adhered and fixed to each other whereby the operability is enhanced.
(4) The invention uses the combination of fixing by fusion and fixing by dissolution in adhering and fixing the spacers and both substrates and hence, the spacers and both substrates can be surely adhered and fixed to each other.
(5) In the invention, the bonding of conductive components and vitrifying components contained in the fixing material is strengthened and hence, the charging can be surely prevented and, at the same time, the spacers and both substrates can be surely adhered and fixed to each other.
(6) In the invention, the fixing structure can be divided in two, that is, the fixing by fusion and the fixing by dissolution and hence, the operability can be enhanced. Further, the conductive components can be obtained stably at a low cost.
(7) In the invention, by forming the spacers using ceramics members, it is possible to provide spacers which have a mechanical strength necessary for a cold cathode display panel and, at the same time, it is possible to ensure the reliability of the adhesion and fixing of the spacers and both substrates.
In the invention, the spacers per se can be easily manufactured on a mass production basis and hence, it is possible to obtain the spacers at a low cost.
(9) In the invention, the spacers can hold the distance between both substrates at a desired value over a whole surface of the substrate in cooperation with the frame and, at the same time, the mechanical strength of the panel can be enhanced, whereby it is possible to realize the image display device which enables the large-sizing of the display and the high-quality display and also possesses the prolonged lifetime.
(10) In the invention, by setting the distance between the spacers to 50 mm or less, it is possible to reduce a distortion of a display image attributed to the deflection of the substrate.
(11) The invention can provide the constitution which exhibits the high reliability with respect to both of the adhering and fixing of the spacers and the substrate and the hermetic sealing of the frame and the substrate, and can realize, not to mention the enhancement of operability, the image display device which enables the large-sizing of the display and the high-quality display and also possesses the prolonged lifetime.
(12) It is possible to enhance the operability by making use of the fixing by fusion and the fixing by dissolution.
(13) The use of jigs and the like is not indispensable and hence, it is possible to obviate the various drawbacks attributed to the jigs and hence, it is possible to realize the image display device which enables the large-sizing of the display and the high-quality display and also possesses the prolonged lifetime.
(14) Further, there is no generation of the positional displacement or the inclination of the spacers. Further, there is neither breaking of the spacers nor damages on the electrodes or the like attributed to the broken spacers.
Hereinafter, embodiments of the invention are explained in detail in conjunction with attached drawings of the embodiments.
In
In
The plate-like spacers 4 and the short spacers 14 shorter than the plate-like spacers 4 are constituted of a thin ceramics plate made of alumina or the like. The plate-like spacers 4 and the short spacers 14 are arranged in a space defined between the face substrate 1 and the back substrate 2. Further, the spacers 4 and the short spacers 14 are erected on a surface of the above-mentioned substrate substantially vertically. A plurality of spacers 4 and short spacers 14 are arranged at a given pitch interval in a state that the spacers 4 and the short spacers 14 have a long-side direction thereof aligned with the above-mentioned one direction (X direction) (hereinafter referred to as “column”). A plurality of spacer columns are arranged at given pitch distances in another direction (Y direction) which intersects the above-mentioned one direction orthogonally. The spacers 4 and the short spacers 14 are fixed to the face substrate 1 by way of the fixing material 11 which contains a conductive component. Further, the spacers 4 and the short spacers 14 and the face substrate 1 are fixed to each other using two kinds of fixing methods consisting of fixing by fusion and fixing by dissolution. That is, the spacers and the substrates are fixed to each other using the composite fixing structure where the spacers and the substrates are fixed using a plurality of fixing means. The spacers 4 and the short spacers 14 and the back substrate are connected with each other only by fixing by dissolution.
The composite fixing structure of the face substrate 1 and the spacers 4, 14 is explained in detail in conjunction with
The black matrix 63 is formed on the face substrate 1 and a metal back layer 62 which is constituted of an aluminum thin film is formed on the black matrix 63.
First of all, the spacers 4 and the short spacers 14 have portions thereof embedded in the fixing material 11 arranged on the metal back layer 62 of the face substrate 1. Next, portions of the above-mentioned embedded portions of the spacer are heated at a temperature of approximately 1000° C. or more, for example, using a heat focusing means such as laser irradiation thus locally melting the fixing material 11. The melted portions are solidified along with the lowering of temperature and forms fixing points 13. The fixing points 13 fix the spacers 4 and the short spacers 14 to the face substrate 1 by fusion by way of the fixing material 11.
Next, the temperature is elevated to a temperature at which the above-mentioned fixing material 11 is dissolved, for example, approximately 450° C. and remaining portions except for the melted fixing points 13 are dissolved thus further fixing the face substrate 1 and the spacers 4 and the short spacers 14 by dissolution.
Accordingly, the face substrate 1 and the spacers 4 and the short spacers 14 are fixed by the combination of the composite fixing structure of the fixing by fusion and the fixing by dissolution.
Although there may be a case in which traces of the above-mentioned irradiation may remain at portions of the spacers 4 and the short spacers 14 in the vicinity of the melting fixing point 13, the spacers per se and the fixing strength of the spacers receive no adverse influence.
Further, the above-mentioned fusion fixing point 13 may be decided based on the sizes, materials of the spacer and the working efficiency and the like.
On the other hand, the back substrate 2 and the spacers 4 and the short spacers 14 are fixed using the fixing by dissolution which dissolves the above-mentioned fixing material 11.
The arrangement pattern of the spacers held by such a fixing structure adopts the dispersion arrangement exhibiting a staggered pattern in which center positions of spacers 4 along long sides of the spacers 4 are displaced in one direction (X direction). That is, this embodiment uses both spacers which are constituted of the spacers 4 having a thickness D, a length L1 and a height H and the short spacers 14 which have the same thickness and the same height as the spacers 4 and only differ in length from the spacers 4. As the sizes or the like are described in detail in
Further, the mixed columns 451, 452 are formed by aligning three spacers 4 at a pitch interval Px1 and two short spacers 14 at both ends. The four-piece columns and the mixed columns are configured to be arranged in parallel alternately at a pitch interval Py1 in another direction (Y direction) which intersects the above-mentioned one direction.
Further, in the four-piece columns 441 to 443, an interval in the aligning direction between the outermost spacer 4a in each column and the frame 3 is set as Wx1, while in the mixed columns 451 and 452, an interval in the aligning direction between the outermost spacer 14a in each column and the frame 3 is set as Wx1. Further, an interval in the arrangement direction between the outermost side columns 441 to 443 and the frame 3 is set to Wy1 (Wy1≈Wx1).
Further, the four-piece columns 441 to 443 and the neighboring mixed columns 451, 452 have the arrangement in which the centers of the long sides of the spacers 4 differ thus adopting the dispersion arrangement in which the arrangement pattern of the spacers 4 adopts the staggered pattern.
The spacers 4 and the short spacers 14 are arranged in a dispersed manner such that a stress attributed to an atmospheric pressure is substantially uniformly applied to the respective spacers 4 and the short spacers 14 so as to prevent the deflection and damages of the substrate and the generation of buckling of the spacers. Further, the respective spacers 4 and the respective short spacers 14 have upper and lower end surfaces thereof fixed to both substrates 1, 2 by way of the fixing material 11. Further, the spacers 4 and the short spacers 14 hold a distance between both substrates 1, 2 to a given size in cooperation with the frame 3.
Here,
A plurality of cathode lines 51 extend in one direction (X direction) and are arranged in parallel in another direction (Y direction) on the inner surface of the back substrate 2.
The cathode lines 51 have end portions thereof bifurcated as cathode-line lead lines 51a along two sides of the back substrate 2 and are pulled out to the outside of the hermetic sealing portion. The cathode lines 51 can be formed by vapor deposition or by baking. In forming the cathode lines 51 by baking, a silver paste which is formed by mixing low-fusion glass which exhibits the insulation property into conductive silver particles having a particle size of several μm (for example, approximately 1 to 5 μm) is printed to form a film of a large thickness and the film is baked at a temperature of approximately 600° C., for example.
Further, the control electrodes 53 are arranged above the cathode lines 51 in an insulated manner from the cathode lines 51. The control electrodes 53 constitute the control electrode lead lines 53a and are pulled out to the outside of the hermetic sealing portion at another one side of the back substrate 2.
Further, the electron sources 52 which are arranged on the cathode line 51 at a given pitch are formed of an electron emission element of metal-insulator-metal (MIM) type, an electron emission structure element which utilizes an electron emission phenomenon based on a quantum theory tunneling effect (also referred to as “a surface conduction type electron source”), or a diamond film, a graphite film and carbon nanotubes or the like. As a method for forming the electron sources 52, for example, a carbon nanotube paste is printed on a surface of the cathode line 51 which is formed by pressure membrance-printing and then baking and is baked in a vacuum at a temperature of 590° C., for example.
In this embodiment, as the carbon nanotube paste, a paste which is formed by dispersing single-wall carbon nanotubes in ethyl cellulose and terpineol is used.
Here, although the explanation has been made with respect to the single-wall carbon nanotubes above, the multi-wall carbon nanotubes or the carbon nanofibers maybe used. Further, besides these materials, for example, diamond, diamond-like carbon, graphite, amorphous carbon and the like can be used. Further, it is also possible to use the mixture of these materials.
Further, the image forming member 6 arranged on the face substrate 1 includes the phosphor layer 61, the metal back layer 62 which is formed on the phosphor layer 61 and the black matrix (BM) film 63. This constitution is substantially equal to the constitution of a conventional color-cathode-ray-tube phosphor screen.
In such a constitution, electrons emitted from the electron sources 52 which are arranged on the cathode lines 51 receive a control by electron passing holes formed in the control electrodes 53 to which a grid voltage of approximately 100V is applied and pass through the electron passing holes. Then, the electrons advance to the image forming members 6 to which an anode voltage of several KV to 10 and some KV is applied, pass through the metal back layers 62 (anodes) and impinge on the phosphor layers 61 thus allowing the phosphor layers 61 to emit light to perform a desired display on a video image screen.
Then, unit pixels are arranged on intersecting portions of the cathode lines 51 and the control electrodes 53 in a matrix array and the above-mentioned display region is formed of the matrix-arrayed pixels. In general, a group consisting of the above-mentioned three unit pixels constitutes a color pixel having colors of red (R), green (G) and blue (B).
Next, the sealing material 10 is made of amorphous frit glass which is, for example, composed of 75 to 80 wt % of PbO, approximately 10 wt % of B2O3 and 10 to 15 wt % of balance. The sealing material 10 is arranged on upper and lower end surfaces of the frame 3 and hermetically seals peripheral portions of the face substrate 1 and the back substrate 2 which are stacked in the Z direction. Due to such hermetic sealing, a portion surrounded by the frame 3 and both substrates 1, 2 constitute the display region 12.
Here, the hermetic sealing performed by way of the sealing material 10 is performed in a nitrogen atmosphere at a temperature of approximately 430° C. and, thereafter, the heating at a temperature of approximately 350° C., the evacuation and the sealing follow. Here, the Z direction means the direction which is orthogonal to substrate surfaces of the back substrate 2 and the face substrate 1 which are overlapped to each other.
Next, the fixing material 11 which fixes the spacers 4, the short spacers 14 and both substrates 1, 2 is constituted of a mixture of 50 wt % of a conductive component which is formed of conductive silver particles having a particle size of several μm to several tens μm (for example, approximately 3 to 10 μm) and 50 wt % of low-fusion-point frit glass which constitutes a vitrifying component which exhibits the insulation property. The fixing material 11 fixes the upper and lower end surfaces of the spacers 4 and both substrates 1, 2. The low-fusion-point frit glass is constituted of the composition which contains, for example, SiO2, B2O3 and PbO as main components.
The fixing material 11 can be used in a state that the vitrifying component falls in a range of 10 to 90 wt %. When the vitrifying component of the fixing material 11 is less than 10 wt %, the adhesion strength becomes insufficient and hence, the spacers are removed or inclined whereby it becomes difficult to hold the parallelism between both substrates 1, 2 and, at the same time, it is difficult to ensure the desired panel strength. Further, there exists the possibility of the occurrence of defects such as the rupture of the spacers and damages on electrodes attributed to the rupture of the spacers when the adhesion strength decreases.
Further, the adhesion temperature at the time of adhering the spacers and the substrate is set based on the fusion characteristics of the conductive component. Accordingly, when the vitrifying component of the fixing material 11 is less than 10 wt %, the adhesion temperature becomes high. Accoridngly, there arises a problem with respect to the heat resistance of the electrodes, particularly the heat resistance of the electron sources 52. That is, there arise problems that the electrodes are damaged in the high-temperature adhesion and the adhesion strength becomes insufficient in the low-temperature adhesion thus giving rise to a drawback with respect to use as an image display device.
On the other hand, when the vitrifying component exceeds 90 wt %, an electric resistance value of bonding portions becomes high and a potential in the vicinity of the spacer 4 becomes unstable and hence, there arises the difference in a beam quantity among the electron beams which pass in the vicinity of the spacer 4 whereby the fluctuation of brightness and color tone is generated on a phosphor screen thus giving rise to a defect with respect to the display quality which does not allow the practical use of the display device.
Accordingly, the vitrifying component ratio can be used in a range of 10 to 90 wt %, while it is difficult to use the vitrifying component ratio which falls outside the range. Further, although the detailed explanation will be made later, it is desirable that the vitrifying component ratio practically falls within a range of 20 to 80 wt %, and it is more preferable that the vitrifying component ratio is approximately 50 wt % in view of the electric and mechanical properties as well as the operability.
Further, as the conductive components, beside the above-mentioned silver, for example, one selected from a group consisting of nickel, gold, platinum and the like or an alloy which contains such metals as a main component can be used. It is desirable to use a granular material which constitutes a sintered body of these metals. Particularly, it is preferable to use silver and nickel in view of the stable supply, inexpensive cost and, further, operability.
The upper and lower end surfaces of the spacer 4 and both substrates 1, 2 are fixed to each other with the above-mentioned fixing structure using the fixing material 11 having the above-mentioned composition.
In this embodiment, the fixing of the face substrate and the spacers is performed by the combination of a plurality of fixing structures consisting of the fixing by fusion and the fixing by dissolution and hence, it is possible to ensure the reliability of fixing of the substrate and the spacers.
Further, since the spacers 4 are accurately fixed to the substrate by fixing by fusion, even in the fixing by dissolution, it is possible to obviate the occurrence of the inclination and peeling-off of the spacers and hence, the breaking of the spacers or the damages on the electrodes can be obviated.
Further, since the spacers 4 are accurately fixed to the substrate by fixing by fusion, the use of the jigs which has been conventionally inevitable including a panel assembling step with the back substrate can be avoided and hence, not to mention the overcoming of the drawbacks attributed to the use of jigs, it is also possible to enhance the operability.
Further, by arranging plural types of combinations of the spacers 4 and the short spacers 14 having the size different from the spacers 4, the whole area of the substrate can be held uniformly. Accordingly, a stress attributed to an atmospheric pressure is substantially uniformly applied to the respective long and short spacers 4, 14 thus preventing the deflection and damages of the substrate and the generation of buckling of the spacers whereby it is possible to provide the highly reliable display device which can ensure the parallelism of both substrates and the panel strength.
Further, by setting the distances Wx1, Wy1 between the outermost spacers 4, 14 and the frame 3 substantially equal to the distances Px1, Px2 between the spacers, the outermost spacers 4, 14 hardly receive the influence of the fixing of the frame 3 and the sealing material 10 and hence, it is possible to hold the whole area of the display region 12 substantially uniformly.
Further, by allowing the aligning direction of the spacers and the extending direction of the cathode lines to be aligned with each other, it is possible to enhance the dielectric characteristics between the cathode lines. Further, by interposing, for example, a low-resistance metal layer as a third layer between the fixing material 11 and the spacers 4, 14, a potential of the spacers becomes more stable and hence, mislanding attributed to the diffusion of electron beams hardly occurs thus giving rise to an advantage that the image quality is enhanced.
This embodiment describes the constitution which fixes the spacers 4 to the back substrate 2 using the composite fixing structure. That is, in
Further, the control electrodes 53 are arranged above the cathode lines 51 in a state that the control electrodes 53 cross the cathode lines 51 orthogonally and are insulated from the cathode lines 51. The end portions of the control electrodes 53 are pulled out to the outside of the support body 3 of the back substrate 2 as the control electrode lead lines.
On the other hand, each spacer 4 is arranged between the control electrodes 53 and in substantially parallel with the control electrodes 53 and has one end thereof fixed to the back substrate 2 by the composite fixing structure by way of the fixing material 11. In this composite fixing, to ensure the insulation between the cathode lines 51, when necessary, an insulation layer may be interposed between the fixing material 11 and the cathode lines 51.
According to this embodiment, by arranging the respective spacers 4 between all grid electrodes 51, it is possible to strengthen the holding strength of both substrates. Further, the trajectories of the electron beams can be controlled by the spacers and hence, the scattering of the electron beams can be reduced thus enhancing the brightness of a screen.
According to this embodiment, the operability of the spacer fixing operation can be enhanced and, at the same time, the embodiment is advantageous in view of a cost.
That is, in this embodiment, the four-piece columns 441, 442, 443 each of which arranges four pieces of spacers 4 having a thickness D, a length L1, and a height H at a pitch interval Px1 while allowing the long sides of the spacers 4 to be aligned with the above-mentioned one direction (X direction) and the three-piece columns 431, 432 each of which arranges three pieces of spacers 4 at the same pitch Px1 are configured to be arranged in parallel in another direction (Y direction) which intersects one direction alternately at a pitch Py1.
Further, in the four-piece columns 441 to 443, the distance in the aligning direction between the outermost spacer 4a of each column and the frame 3 is set as Wx1, while in the three-piece columns 431, 432, the distance in the aligning direction between the outermost spacer 4b of each column and the frame 3 is set as Wx2 (Wx2>Wx1) and an envelope E which connects the outermost sides of these columns exhibits a serrated shape. Further, the distance in the arrangement direction between the outermost columns 441, 443 and the frame 3 is set to Wy1 (Wy1≈Wx1).
Further, the three-piece columns 431, 432 which are arranged close to the four-piece columns 441 to 443 have the center in the longitudinal-direction of the spacers 4 made different from each other thus providing the dispersed arrangement in which the spacers 4 are arranged in a staggered pattern.
The arrangement number and the arrangement position of the spacers are set such that a stress attributed to an atmospheric pressure is substantially uniformly applied to the respective arranged spacers 4. Further, the spacers 4 are arranged in a dispersed manner so as to prevent the deflection and damages of the substrate and the generation of buckling of the spacers. Each spacer 4 also have upper and lower end surfaces thereof fixed to both substrates 1, 2 by way of the fixing material 11. Further, the spacers 4 hold a distance between both substrates 1, 2 to a given size in cooperation with the frame 3.
According to the constitution of this embodiment, due to the proper arrangement of the spacers, it is possible to prevent the occurrence of damages on the spacers per se and, at the same time, a desired holding strength can be obtained with small number of spacers 4 due to the arrangement pattern indicated by an envelope E whereby the operability can be enhanced eventually. Further, with the use of single kind of spacers, the management of the operation is facilitated.
A thickness and a height of the short spacers 24 are set equal to the thickness and the height of the spacers 4, while the distance Wx3 between the short spacer 24 and the frame 3 has the relationship of Wx3>Wx1.
According to this embodiment, with the use of the short spacers 24 and the long spacers 4, an approximately uniform load is applied to the respective spacers 4, 24 corresponding to respective sizes of the spacers 4, 24 and hence, it is possible to hold the distance between both substrates at a given size and, at the same time, it is possible to prevent the deflection and damages on the substrate and also the damages on the spacers.
Further, it is also possible to give rise to a reinforcing effect also in another direction which is orthogonal to the above-mentioned one direction and the whole area of the display region can be uniformly held provided that the relationship Wx3>Wx1 is satisfied.
Next,
Although the required adhesion strength of the spacers in this type of image display device is set by taking a safety coefficient at the time of assembling into consideration, it is empirically known that it is possible to obtain a sufficient adhesion strength by setting the safety coefficient to about 100 times or more of the weight of the spacer.
In
In
Further, when this value exceeds 20%, as can be clearly understood from
However, when the vitrifying component ratio is 100%, since the fixing material is constituted of only the vitrifying component, a resistance value becomes excessively high as described later thus giving rise to a drawback that the spacers are charged. In this manner, there arises the possibility that a locus of the electron beam is disturbed by charging. Due to the charging of the fixing material, there arises the possibility that it is less efficient to fix by fusion than expected and that the substrates and the spacers are excessively strongly fixed to each other thus hampering the recycling operation. Accordingly, it is desirable that the above-mentioned vitrifying component ratio in the fixing material is 90% or less.
Next,
As can be clearly understood from
Further, it is preferable that the resistance value is practically 1010Ω·cm or less and hence, it is desirable to set the vitrifying component ratio to 80 wt % or less. On the other hand, when the vitrifying component ratio is lowered, the resistance value is also lowered as shown in the drawing.
However, it is necessary to prevent both substrates from becoming conductive with each other and hence, it is preferable to set the vitrifying component ratio to 10 wt % or more, and it is more preferable to set the vitrifying component ratio to 20 wt % or more.
Here, the material, the individual size, the number of arrangement, the arrangement pattern and the like of the spacers are determined by taking the sizes of the substrates, the number of pixels, the deflection quantity of both substrates, the operability and the like into consideration. Accordingly, with respect to the respective sizes of the spacers which are used in the above-mentioned
Next,
Here, in
First of all, in
In general, when the deflection quantity of the substrate is increased, the reflection on the screen is generated at the time of performing a display and hence, there arises a drawback that the display quality is deteriorated. To ensure the display quality by overcoming this drawback, it is necessary to limit the deflection quantity such that the maximum allowable deflection quantity of the substrate is approximately 40 μm. Accordingly, it is preferable to set the above-mentioned pitch distance Px1 to 50 mm or less.
On the other hand, with respect to the deflection quantity of an end surface of the substrate indicated by the solid line L2, irrespective of the value of the above-mentioned pitch distance Px1, when the distance Wx1 in the above-mentioned aligning direction exceeds 60 mm, the deflection quantity exceeds 60 μm and the reflection on the screen is generated. Accordingly, it is necessary to set the distance Wx1 in the aligning direction at the end surface to 50 mm or less in the same manner as the pitch distance Px1 at the center portion.
Next, in
In
Next, the manufacturing method of the display device of the invention is explained.
In
Here,
Next, the spacers 4 are aligned with and mounted on the above-mentioned fixing material layers 11a, wherein one end side 41 of the spacer 4 is partially embedded in the fixing material layer 11a. This step is performed before drying the above-mentioned fixing material layer 11a.
Next, laser beams 15 or the like are irradiated to the vicinity of the one-end-side portion of the spacer 4 which is embedded in the fixing material layer 11a in a state that the spacer 4 is held. The beam-irradiated portion is heated at a temperature of 1000° C. or more, for example, to fuse the fixing material 11 and the spacer 4 is fixed to the face substrate 1 at the fusing fixing point 13.
In performing this fixing by fusion, besides the above-mentioned laser beams, it is possible to use a heating device which can heat the material to be heated 18 by the combination of an infrared light source 16 and an elliptical reflector 17 which is shown in
This fixing by fusion is performed at plural fusion fixing points 13 along the long-side direction of the spacer 4 thus fixing the spacer 4 to the face substrate 1 by fusion. A given number of spacers 4 are fixed by fusion to the face substrate 1 by repeating this step and, thereafter, the sealing material 10 in which a given binder is mixed is applied to the face substrate 1 thus constituting the face substrate provisional assembled body FTA shown in
Here, it is possible that the sealing material 10 is not formed on the substrate and the whole sealing material 10 is applied to the frame 3 side. Further, it is possible that the face plate 1 including the spacers 4 which are fixed by fusion is heated in the atmosphere at a temperature of 450° C., for example, for 10 minutes before applying the sealing material 10 and, thereafter, the heating for dissolution of the fixing material 11 is performed.
Next, the above-mentioned face plate provisional assembled body FTA is provisionally baked at an approximately 150° C. which is a temperature which can dissipate the binder thus forming the face substrate assembled body FPA.
On the other hand, on the back substrate 2 side, first of all, the plurality of cathode lines 51 which extend in the X direction and are arranged in parallel in the Y direction which intersects the X direction, the control electrodes 53 which extend in the Y direction and the like are formed. Thereafter, the fixing material 11 and the sealing material 10 to which the given binders are mixed respectively are applied and formed in given patterns thus forming the back substrate provisional assembled body BTA.
The back substrate provisional assembled body BTA is provisionally baked at a temperature of approximately 150° C. which can dissipate the binders and, thereafter, the electron sources 52 are formed on the cathode lines 51 to form the back substrate assembled body BPA.
Further, the sealing material 10 to which the given binder is mixed is applied to the upper and lower end surfaces of the frame 3 and, thereafter, the frame 3 is provisionally baked to form the frame assembled body SPA. Here, the temperature at the time of performing the provisional baking is set to approximately 150° C. or more which can dissipate the binder. When frit glass is used, it is possible to perform the baking operation at a temperature of approximately 350° C. to 450° C.
Next, a panel provisional assembled body PSA is formed by overlapping three assembled bodies, that is, the face substrate assembled body FPA which fixes one-end sides 41 of the spacers 4 to the face substrate 1 by fusion, the back substrate assembled body BPA and the frame assembled body SPA in the Z direction. While pressing the panel provisional assembled body PSA in the Z direction, the panel provisional assembled body PSA is heated at a temperature of 430° C. for 10 minutes, for example, thus hermetically sealing both substrates and the frame 3 using the sealing material 10 and, at the same time, one-end sides 41 of the spacers 4 are fixed to the face substrate 1 by fusion by way of the fixing material 11 while another-end sides 42 of the spacers 4 are fixed to the back substrate 2 by fusion by way of the fixing material 11.
Next, a space which constitutes an display region 12 surrounded by both substrates 1, 2 and the frame 3 is evacuated by way of an exhaust pipe not shown in the drawing. It is possible to perform the evacuating operation simultaneously with heating in the step for fusing the sealing material 10 and the fixing material 11 after arranging the panel provisional assembled body PSA in a vacuum furnace.
Here, it is needless to say that the invention is not limited to the above-mentioned embodiments and various modifications can be made without departing from the technical concept of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-236286 | Aug 2004 | JP | national |
