1. Field of the Invention
The present invention relates to a substrate having a light emitter which emits light by electron beam irradiation for an image display device, such as a field emission display, which utilizes an electron beam. The present invention also relates to an image display device using the substrate and an information display reproducing apparatus using the image display device.
2. Related Background Art
Research and development of the image display device for which a field emission type electron-emitting device, a surface conduction electron-emitting device, and the like are used is in progress for a flat panel display of application.
In the display panel of
In the image display device having the above structure, an electric field is generated between the rear plate 31 and the faceplate 40 by applying the high voltage (sometimes referred to as “accelerating voltage” or “anode voltage”) to the metal back 45 which is of a part of the anode electrode. The electric field causes the electron-emitted from the electron-emitting device 33 to collide with the fluorescent material, which allows the fluorescent material to emit the light to display an image. At this point, because brightness of the image display device depends largely on the accelerating voltage, in order to increase the brightness, it is necessary to increase the accelerating voltage. Further, in order to realize a reduction in thickness of the image display device, it is necessary to decrease the distance between the rear plate 31 and the faceplate 40. This results in the generation of the considerably high electric field between the rear plate 31 and the faceplate 40.
The flat panel display in which the high electric field is applied between the rear plate and the faceplate in the above-described way is disclosed in Japanese Patent Application Laid-Open No. 10-326583.
However, there are the following problems in the flat panel display in which the high electric field is applied between the rear plate and the faceplate.
In the structure of
In order to solve the above problems, an object of the invention is to provide an image display device which suppresses influence by the discharge between the faceplate and the rear plate to improve reliability.
According to a first aspect of the invention, there is provided a substrate, having a light emitter, which is used for an image display device, the substrate comprising:
(A) a substrate which has a member having a plurality of openings on a surface of the substrate;
(B) light emitters which are arranged in the plurality of openings respectively;
(C) a plurality of conductive films arranged to cover the light emitter; and
(D) an electrode pad which is connected to a power supply for providing potential to the plurality of conductive film,
wherein the member having the plurality of openings has a conductive area,
the conductive area is electrically connected to the electrode pad,
each of the plurality of conductive films is in contact with the member having the plurality of openings,
the minimum value of resistances (Rx) between the two conductive films adjacent to each other in the plurality of conductive films is larger than the minimum value of resistances (Rz) between the conductive area and the plurality of conductive films, and
a resistance (Rp) in a range from the conductive area to the, electrode pad is smaller than the resistance (Rz) in a range from the conductive area to each of the plurality of conductive films.
According to a second aspect of the invention, there is provided a substrate, having a light emitter, which is used for an image display device, the substrate comprising:
(A) a substrate which has a resistance member including a plurality of openings on a surface of the substrate;
(B) light emitters which are arranged in the plurality of openings respectively;
(C) a plurality of conductive films which are arranged so as to be connected to the resistance member, the light emitter arranged inside each of the plurality of openings being covered with the conductive film, the conductive films being separated from each other at an interval; and
(D) an electrically conductive area being connected to the plurality of conductive films electrically through the resistance member,
wherein the minimum value of resistances (Rx) between the two conductive films adjacent to each other in the plurality of conductive films is higher than the minimum value of resistances (Rz) between the conductive area and the plurality of conductive films.
A third aspect of the invention is an image display device including the substrate having the light emitter described in the first aspect or the second aspect of the invention and the rear plate in which electron-emitting devices are arranged.
In the invention, when resistance Rx is simply measured between two adjacent conductive films in the plurality of conductive films, the resistance Rx cannot accurately be measured because wrap-around of resistance Rz through the conductive area is added to the resistance Rx. As used herein, the term of “resistance Rx” between the two adjacent conductive films in the plurality of conductive films shall mean the resistance Rx in which the wrap-around of the resistance Rz is removed.
The function of restricting the current during the discharge is imparted to the faceplate of the invention. Therefore, the image display device in which the damage is suppressed during the discharge to improve the reliability can be obtained by using the face plate of the invention.
When the discharge is generated between the faceplate 40 and the rear plate 31 as described above, in order to decrease discharge current so that the effect of the discharge is suppressed, it is effective that the charge accumulated in the electrostatic capacity is prevented from flowing into the rear plate 31.
A basic principle of the substrate having a light emitter (sometimes referred to as “faceplate”) of the invention will be described.
In the image display device according to the invention, the metal back performs functions of increasing efficiency of light emission outputted to the side of the substrate 11 by reflecting forward the light emitted to the side of the rear plate 21 or applying the accelerating voltage in order to accelerate the electron.
In the invention, the metal back is formed by the plurality of conductive films 15, and the respective conductive films 15 are preferably formed in a rectangle or a square. A potential of each conductive film 15 is defined by electrically connecting the conductive film 15 to the conductive area 12. The conductive area 12 may constitute the member 17 according to the invention, and the member 17 has a plurality of openings (hereinafter referred to as “opening member”). The opening member 17 may have the distance specifying member 13 and the conductive area 12. The distance specifying member 13 specifies (defines) the distance between the light emitters 14 (fluorescent material). Therefore, in the manufacturing process, it is possible to adopt the process of arranging the light emitter 14 in each opening after the opening member 17 is formed.
The shape of the conductive area 12 constituting a part of the opening member 17 is not limited only to the configuration shown in
The plurality of electron-emitting devices 23 and the wirings connected to the electron-emitting devices 23 are arranged on the rear plate 21 (only the row-direction wirings 22 are shown in
In the invention, as shown in
However, the currents (corresponding to I2 of
When the resistance Rx is smaller than the resistance Rz, the current flowing through the resistance Rz becomes larger than the current flowing through the resistance Rx, and the effect of the resistance Rz is decreased. Therefore, in the structure of
Preferably the light emitter 14 is formed by a member (insulating material) having a sufficiently high resistance value. Further, preferably the light emitter 14 is formed by a plurality of insulating fluorescent material particles.
In the resistance Rx between the adjacent blocks (between the conductive films 15), the wrap-around by the resistance Rz is removed. However, when the resistance is simply measured between the conductive films 15, the wrap-around by the resistance Rz cannot be removed. Therefore, an example of a method of measuring the resistances Rx and Rz according to the invention will be described referring to
It is assumed that the resistance between the arbitrary conductive film 15 and the conductive film 15 adjacent to the arbitrary conductive film 15 is Rx (the resistance in the plane direction of the distance specifying member 13 in
The following conditions are required for the resistance Rz.
With reference to (1), although the resistance Rz depends on the accelerating voltage applied to the image display device or the size of the display area, it is preferable that an effect of the current restriction is exhibited when the resistance Rz is more than 500Ω, and it is more preferable that the resistance is not lower than 5 KΩ. With reference to (2), although the resistance Rz depends on the amount of current injected from the electron-emitting device, the voltage drop caused by the current injected from the electron-emitting device becomes sufficiently small when the resistance Rz is lower than 1 MΩ, and more preferably the voltage drop can substantially be neglected when the resistance Rz is not more than 100 KΩ.
With reference to (1), when the resistance Rx is lower than 1 KΩ, the current flowing through the resistance Rx becomes large. Therefore, although the resistance Rx depends on the accelerating voltage applied to the image display device or the size of the display area, the resistance Rx is set to not lower than 1 KΩ to exhibit a current restriction. More preferably, the resistance Rx is set to 1 MΩ or more, for practical use.
For the method of connecting each conductive film 15 and the conductive area 12 or the high-voltage power supply 16 by the resistance described above, the method in which the connection is performed not through the opening member 17 according to the invention but through the conductive fluorescent material may be used. However, almost all of the fluorescent materials which emit the light by the electron beam irradiation are the insulating material, and light-emission color and light-emission efficiency are sacrificed when the conductivity is imparted to the fluorescent material. On the contrary, when the structure in which the resistance Rz is determined by the member (opening member 17) except for the fluorescent material is formed like the invention, the light-emission color and the light-emission efficiency which are of the important functions of the image display device are not sacrificed.
Any configuration can be adopted for the conductive area 12 according to the invention, because the conductive area 12 electrically connects the electrode pad (not shown) and each conductive film 15. Preferably the conductive film 15 is formed on the surface side of the substrate 10 of the opening member 17, and the desired effect can be obtained without obstructing the light emitted from the fluorescent material (light emitter) 14 by producing the conductive film transparent to visible light over the surface of the substrate 10, specifically by producing the transparent conductive film such as ITO over the surface of the substrate 10.
The structure in which the distance specifying member 13 is clearly distinguished from the conductive film 12 is shown in
For example, the conventional black matrix can be applied to the distance specifying member 13 according to the invention. Examples of the method of manufacturing the distance specifying member 13 includes a photolithography method and a screen printing method in which ruthenium oxide paste, resistance element paste containing carbon graphite, glass frit, and back pigments, or paste containing barium titanate powder is used. The materials except for the above-described materials can be used as long as the material has the high resistance value.
The electrode pad (not shown) also acts as the member which electrically connects the conductive area 12 and the high-voltage power supply 16 for providing the anode potential. When the resistance Rp in the range from the conductive area 12 located nearest each conductive film 15 to the electrode pad (position to which the anode potential is provided) is larger than the resistance Rz in the range from the each conductive film 15 to the conductive area 12, the potentials of the conductive films 15 are varied by the influence of the current of the electron beam. When the resistance Rp is smaller than the resistance Rz, the potentials may become substantially equal among arbitrary points of the conductive area 12. As a result, the potentials of the conductive films 15 may be also substantially equalized.
As the size of each conductive film 15 is decreased, the charge accumulated in each conductive film 15 is decreased. As a result, since the current (corresponding to I1 in the drawings) flowing into the block by the discharge becomes small, it is preferable in displaying the stable image.
In the faceplate 10, the fluorescent material (light emitter) 14 which emits the light of any one of R (Red), G (Green), and B (Blue) is arranged to form one sub-pixel. A set of three sub-pixels of R, G, and B may form one pixel. Accordingly, it is possible that one sub-pixel is covered with the conductive film 15, it is possible that one pixel is covered with the conductive film 15, and it is possible that at least two pixels are covered with the conductive film 15.
The image display device of the invention is formed by the substrate having a light emitter of the invention and an electron-emitting device. Accordingly, except that the substrate with a light emitter of the invention is used as the faceplate 40 of the display panel of
An information displaying/reproducing(playback) apparatus can be formed by using the display panel (image display device) of the invention, which is described referring to
Specifically, the information displaying/reproducing apparatus such as a television set includes a receiving apparatus which receives a broadcasting signal such as a television broadcasting signal, a tuner which selects the received signals, and displaying and/or reproducing apparatus which outputs at least one of video information, character information, and audio information which are included in the selected signal to the display panel to display it on the screen. When the broadcasting signal is encoded, the information displaying/reproducing apparatus of the invention can include a decoder. An audio signal is outputted to separately-provided sound reproducing means such as a speaker to reproduce the audio signal in synchronization with the video information or the character information which is displayed on the display panel. The face plate (11,15,17) may correspond to the screen.
The following method can be cited as an example of the method of outputting the video information or the character information on the display panel to display and/or reproduce the video information or the character information on the screen. An image signal is generated corresponding to each pixel of the display panel from the received video information or character information. The generated image signal is inputted to a drive circuit of a display panel 77. Then, the image is displayed by controlling the voltage applied to each electron-emitting device in the display panel on the basis of the image signal inputted to the drive circuit.
It is possible that the interface unit is connected to an image recording apparatus and image output apparatus such as a printer, a digital video camera, digital camera, a hard disk drive (HDD), and a digital video disk (DVD). In this case, it is possible to form the information display reproducing apparatus (or television set) in which the image recorded in the image recording apparatus can also be displayed on the display panel 77 and the image displayed on the display panel 77 is processed according to need to output the processed image to the image output apparatus.
The configuration of the information display reproducing apparatus described above is only for illustrative purpose, and various modifications and changes can be made on the basis of the technical thought of the invention. The information display reproducing apparatus of the invention can form the various information display reproducing apparatuses by connecting the information display reproducing apparatus to a system such as a television meeting system and a computer.
Referring to the accompanying drawings, examples of the invention will be described. However, the scope of the invention shall not be limited to the size, the material, and the shape of the constituent components and a relative arrangement of the components which are described in the following examples except for the particular description.
The image display device including the display panel shown in
In Example 1, the distance between the rear plate 21 and the faceplate 10 was set to 2 mm. The inside of the sealed vessel formed by the rear plate 21, the faceplate 10, and the sidewall 19 was maintained at a degree of pressure below 10−7 Pa. In Example 1, the number of row-direction electric line 22 was set to 240 (N=240), and the number of column-direction electric line 24 was set to 80 (M=80).
The process of manufacturing the faceplate of Example 1 will specifically be described below.
ITO which formed the conductive area 12 was deposited over the surface of the image area of the cleaned glass substrate by a sputtering method. A sheet resistance value of ITO was set to 100Ω/□.
Then, the paste containing silver particles and glass frits was printed around the conductive area 12 as shown in
The lattice-shaped black matrix having the openings of 200 μm by 200 μm was formed as the distance specifying member 13 by the screen printing method with the ruthenium oxide paste. In the black matrix, the thickness was 10 μm, and a pitch of the opening was 250 μm.
Each opening of the black matrix was filled with the fluorescent materials of R, G, and B by the screen printing method so that the thickness of the fluorescent materials became 10 μm. The fluorescent materials were printed in each color. In Example 1, the opening was filled with the fluorescent materials by the screen printing method. However, the filling method is not limited to the screen printing method. For example, it is possible to adopt the photolithography method. The fluorescent material of P22 which is used in the CRT field was used as the fluorescent material 14. The red color (P22-RE3; Y2O2S:Eu3+), the blue color (P22-B2; ZnS:Ag,Al), and the green color (P22-GN4; ZnS:Cu,Al) were used as the fluorescent materials.
A resin film was deposited on the black matrix and the fluorescent material by a filming process which is publicly known as the manufacturing technology of a cathode-ray tube. Then, Al was deposited on the resin film by the evaporation. The resin film was removed by thermal decomposition to produce the conductive film (Al film) whose thickness was 100 nm on the black matrix and the fluorescent material.
The conductive film was cut on the black matrix with a YAG laser machine to divide the conductive film into the conductive films 15 of each sub-pixel. Thus, the black matrix and the conductive film 15 were connected to each other by overlapping each other in the region whose width was 25 μm, and the adjacent conductive films 15 were separated from each other by the distance of 200 μm.
Then, the faceplates for measuring the resistances Rx and Rz were produced. In the faceplate for measuring the resistance Rz, the conductive film of the faceplate produced in the above-described way was removed except for the measurement area. In the faceplate for measuring the resistance Rx, ITO which is of the conductive area was not produced, and the conductive film was removed except for the set of adjacent conductive films 15 in the measurement area. As a result of the measurement with the measurement faceplates, the resistance Rz was 1.5 KΩ and the resistances Rx was 200 KΩ. The resistance Rp was measured in the faceplate which was completed to the stage of forming the electrode pad 19 in the above-described way. When the resistances Rp were measured at many points in the image display area, the maximum value of the resistances Rp was about 30Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method shown in
The faceplate of Example 1 was used to produce the image display device which included the display panel having the structure shown in
In Example 1, the image display device having the high brightness and good color reproducibility could be obtained by using the P22 fluorescent materials (insulating material) which have a reputation in the CRT field.
The image display device including the display panel shown in
In Example 2, the conductive area 12 was formed between the substrate 11 and the distance specifying member 13 while the pattern of the conductive area 12 was equal to that of the distance specifying member 13. Specifically, the conductive area 12 was formed so that the thickness of the paste containing the black pigments, silver particles, and the frit glass became 5 μm by the screen printing method using the glass substrate similar to Example 1. The subsequent processes were similar to Example 1 except that the thickness of the black matrix was set to 5 μm.
When the resistances Rx, Rz and Rp were measured in the same way as Example 1, Rx was 100 KΩ, Rz was 700Ω, and Rp was not more than 1Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method similar to Example 1 (
The faceplate of Example 2 was used to produce the image display device which included the display panel having the structure shown in
In Example 2, since the conductive area 12 does not exist in the portion where the fluorescent material 14 is provided, transmittance of the light is improved, and the brighter image was obtained.
The image display device including the display panel shown in
In Example 3, the conductive area 12 was formed in a line shape parallel to the Y-direction. Specifically, the conductive area 12 was formed so that the thickness of a photosensitive paste containing the black pigments, silver particles, and the frit glass became 2 μm by the screen printing method. Then, the dried photosensitive paste was exposed and developed to produce the plurality of line-shaped conductive areas 12 extending in the Y-direction. The subsequent processes were similar to Example 1 except that the thickness of the black matrix was set to 8 μm.
When the resistances Rx, Rz and Rp were measured in the same way as Example 1, Rx was 250 KΩ, Rz was 2 KΩ, and Rp was not more than 1Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method similar to Example 1 (
The faceplate of Example 3 was used to produce the image display device which included the display panel having the structure shown in
In Example 3, since the conductive area 12 was formed in the strip shape, both the resistances Rx and Rz were increased, which allows the current to be decreased during the discharge. Therefore, the image display device which less subjected to the damage caused by the discharge could be formed.
The image display device including the display panel shown in
In Example 4, as with Example 3, the conductive area 12 was formed in the stripe shape parallel to the Y-direction. The distance specifying member 13 was formed by arranging the black matrix 25 and the insulating member 26 on the stripe-shaped conductive area 12. Therefore, the black matrix 25 was in a ladder shape extending in the Y-direction, and the insulating member 26 was formed in a gap between the adjacent ladder-shaped black matrixes 25 while formed in the line shape extending in the Y-direction.
Specifically, the photosensitive paste containing the low-melting glass frit and the black pigments was formed as the insulating member 26 by the photolithography method. In the photosensitive paste, the width was 260 μm and the thickness was 8 μm. The black matrix 25 was also formed by the photolithography method. In the black matrix 25, the width was 20 μm and the thickness was 8 μm.
In Example 4, the insulating member 26 has the function of increasing the resistance Rx between the conductive films 15 divided by the black matrix 25 which is of the resistance element and the resistance Rz between the conductive film 15 and the conductive area 12.
In Example 4, the resistance Rx becomes the resistance through the insulating member 26 by using the insulating member 26, so that the resistance more than 1 MΩ can easily be obtained. Since the area of the black matrix 25 which is of the resistance element which is in contact with the conductive area 12 and the conductive film 15 is decreased, the resistance Rz can be increased.
When the resistances Rx, Rz and Rp were measured in the same way as Example 1, Rx was not lower than 10 MΩ, Rz was 20 KΩ, and Rp was not more than 1Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method similar to Example 1 (
The faceplate of Example 4 was used to produce the image display device which included the display panel having the structure shown in
In Example 4, since the insulating member 26 was arranged, both the resistances Rx and Rz were increased, which allows the current to be decreased during the discharge. Therefore, the image display device which less subjected to the damage caused by the discharge could be formed.
The image display device including the display panel shown in
In Example 5, as with Example 3, the conductive area 12 was formed in the stripe shape parallel to the Y-direction. The black matrix was used as the distance specifying member 13, and the black matrix was formed on the stripe-shaped conductive area 12. The black matrix was formed by the photolithography method. In the black matrix, the width was 50 μm and the thickness was 8 μm. The black matrix was separated between the adjacent conductive films 15. Namely, the black matrix in Example 5 was the plurality of ring-shaped distance specifying members 13 which were arranged so as to surround each fluorescent material 14. Thus, the resistance Rx between the adjacent conductive films 15 becomes substantially infinite.
When the resistances Rx, Rz and Rp were measured in the same way as Example 1, Rx was not lower than 10 MΩ, Rz was 8 KΩ, and Rp was not more than 1Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method similar to Example 1 (
The faceplate of Example 5 was used to produce the image display device which included the display panel having the structure shown in
In Example 5, since the distance specifying member 13 was separated between the adjacent conductive films 15, the resistance Rx between the adjacent conductive films 15 was increased, which allows the current to be decreased during the discharge. Therefore, the image display device which less subjected to the damage caused by the discharge could be formed.
The image display device including the display panel shown in
In Example 6, the metal plate having the plurality of openings was-used as the opening member 17. The metal plate 27 was coated with the high-resistance member 28, and the metal plate 27 was bonded to the glass substrate with the low-melting glass frit. It is preferable that the material whose thermal expansion coefficient is close to that of the glass substrate is used as the metal substrate 27 so that the metal plate 27 is not peeled off from the glass substrate during the burning. A 436 alloy was used in Example 6. The high-resistance member 28 is not particularly limited as long as the resistances Rx and Rz can be set to the desired values. In Example 6, in consideration of the ease of the production and adhesive properties in the low-melting glass frit, a glaze in which platinum fibers were dispersed was applied and burned to form antistatic glass lining having the thickness of 2 μm. Although the antistatic glass lining was used as the high-resistance member in Example 6, the high-resistance member is not limited to the antistatic glass lining. For example, it is possible to use an oxide film produced by applying the material a dipping technique in a sol-gel process.
A part of the high-resistance member 28 formed on the metal plate 27 was peeled off, and the exposed portion of the metal plated 27 was electrically connected to the electrode pad (not shown), which allowed the voltage to be provided from the high-voltage power supply.
When the resistances Rx, Rz and Rp were measured in the same way as Example 1, Rx was not lower than 10 MΩ, Rz was 200 KΩ, and Rp was not more than 1Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method similar to Example 1 (
The faceplate of Example 6 was used to produce the image display device which included the display panel having the structure shown in
In Example 6, the metal plate 27 and the high-resistance member 28 were used as the opening member 17, so that production cost could be reduced.
As shown in
In Example 7, the size of the opening in the black matrix was set to 100 μm by 300 μm, the width of the black matrix between the sub-pixels was set to 50 μm, the width between the pixels was set to 200 μm in the X-direction, and the width between the pixels was set to 300 μm in the Y-direction. The black matrix whose thickness was 5 μm was produced by the photolithography method. The area formed by the three color fluorescent materials of R, G, and B (three sub-pixels) was set to one pixel. The fluorescent material of each color was arranged in each sub-pixel, and the conductive film 15 was provided in each one pixel.
When the resistances Rx, Rz and Rp were measured in the same way as Example 1, Rx was 200 KΩ, Rz was 1.5 KΩ, and Rp was 30Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method similar to Example 1 (
When the image display device for which the faceplate of Example 7 was used was; used at the high voltage of 15 KV, sometimes the discharge was generated. However, the defect that the observer perceived was not generated, and the image display device having the high reliability could be obtained.
The problems, in which the width of the black matrix was too narrow to separate the conductive film 15 between the sub-pixels and the resistance Rx was not larger than the resistance Rz due to the short distance even if the conductive film 15 could be separated, could be avoided by arranging the conductive film 15 in each pixel in Example 7.
As shown in
In Example 8, the size of the opening in the black matrix was set to 50 μm by 100 μm, the width of the black matrix between the sub-pixels was set to 50 μm, the width between the pixels was set to 200 μm in the X-direction, and the width between the pixels was set to 300 μm in the Y-direction. The black matrix whose thickness was 5 μm was produced by the photolithography method. The area formed by the three color fluorescent materials of R, G, and B (three sub-pixels) was set to one pixel. The fluorescent material of each color was arranged in each sub-pixel, and the conductive film 15 was provided in each two pixel.
When the resistances Rx, Rz and Rp were measured in the same way as Example 1, Rx was 200 KΩ, Rz was 600Ω, and Rp was 30Ω. When the magnitudes of the resistances Rx and Rz were compared to each other by the method similar to Example 1 (
The faceplate of Example 7 was used to produce the image display device having the structure shown in
The problems, in which the width of the black matrix was too narrow to separate the conductive film 15 and the resistance Rx was not larger than the resistance Rz due to the short distance even if the conductive film 15 could be separated, could be avoided by arranging the conductive film 15 in each pixel in Example 8.
This application claims priority from Japanese Patent Application No. 2004-040757 filed Feb. 18, 2004, which is hereby incorporated by reference herein.
Number | Date | Country | Kind |
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2004-040757 | Feb 2004 | JP | national |
Number | Date | Country | |
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Parent | 11043076 | Jan 2005 | US |
Child | 11937574 | Nov 2007 | US |