JPH03220587A - Display device - Google Patents

Abstract

PURPOSE:To obtain high brightness by forming a 1st filter and a 2nd filter so that their end parts overlap with each other. CONSTITUTION:A color filter is constituted by forming the 1st and 2nd adjacent color filters so that their end parts overlap with each other to specific size. Thus, the adjacent color filters are formed having the end parts one over the other and then the overlap part decreases in reflection factor and transmissivity to a light beam as compared with the parts where the color filters are formed independently to operate as a black matrix. Consequently, a plasma display which is improved in brightness and has superior display quality can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a display device having a color filter.

[Prior Art] As an example of a display device, a display device is known in which a color filter is disposed at the opening of a discharge cell in a plasma display using phosphors.

The above-mentioned plasma display obtains visible light of a predetermined color by exciting the phosphor with ultraviolet rays generated by plasma discharge within the discharge cell, but the phosphor is usually formed of a white material, and the discharge cell In order to improve the amount of ultraviolet rays reflected inside the discharge cell, the inside of the discharge cell is often made of white material. Therefore, since the inside of the discharge cell becomes white, external light is more likely to be reflected inside the discharge cell, and the contrast ratio tends to decrease. The color filter is provided to reduce the amount of external light reflected above, and usually only transmits light of a specific color corresponding to the emitted color of the phosphor and absorbs other light. It is believed that a material having this effect is used, and that the effect of improving the contrast ratio can be obtained.

In addition, the above color filters emit light from phosphors.
Since it also has the effect of transmitting only light rays of a predetermined color, it is thought that the effect of sharpening the chromaticity can also be obtained. For plasma displays equipped with the above color filters, please refer to Itaben et al.'s ``Ultra Low Reflectance Color Display Discharge Panel.''
(Journal of Television Society, yol, 42, No. 10 (
1988), p. 1084-1090).

FIG. 2 is a partial sectional view showing the internal structure of an example of a plasma color display having the above-mentioned color filter. In the figure, 1 is a front glass plate, and 2 is a rear glass plate disposed opposite to the front glass plate 1. On the front glass plate 1 are a red filter (hereinafter abbreviated as R filter) 31 and a green filter (hereinafter G filter).
Color filters 32 and a blue filter (hereinafter abbreviated as B filter) 33 are arranged with predetermined dimensions and arrangement.

Each of the above color filters includes, for example, a filter paste made of copper sulfate and an alkali metal salt for the R filter, copper sulfate, chromium oxide, and cobalt oxide for the G filter, and a cobalt-based pigment for the B filter.
They are each formed by thick film printing and then firing at a temperature of around 580'C.

A light emitting element is formed behind the front glass plate 1 on which each color filter is formed.

The light emitting element includes an anode 4 and phosphor layers 51, 52 and 53 formed on the surface of each of the color filters 31, 32 and 33 facing the back glass plate 2, and a front glass of the back glass plate 2. A cathode 6 is formed on the surface facing the plate 1.

The anode 4 is a transparent electrode, and is usually made of ITO or the like and formed by a thin film process.

In each of the phosphor layers, a phosphor that emits fluorescence of a color transmitted by each of the color filters is formed at a position corresponding to each color filter. That is, on the R filter there is a layer 51 of a phosphor that emits red (hereinafter abbreviated as R phosphor), and on the G filter there is a layer 52 of phosphor that emits green (hereinafter abbreviated as G phosphor).
A phosphor layer 53 that emits blue light (hereinafter abbreviated as B phosphor) is provided on each of the B filters.

All of the above-mentioned phosphors are generally made of a white material. Examples of the above-mentioned phosphors include (Y,Ga)BO,:Eu'' for the R phosphor, Zn2SiO4:Mn, etc. for the G phosphor, and B for the B phosphor.
Examples include aMgAl, 402s:Eu2'', etc. Each of the above phosphor layers is formed by a method such as thick film printing.
It is fired at a temperature of around 0°C. In addition, in the display illustrated in FIG. 2, a phosphor layer is formed by mixing indium oxide in a predetermined ratio with each of the phosphors to give conductivity, and the phosphor layer is formed so as to cover the entire anode 4. The layer itself acts as an anode, increasing the area of the light emitting part and improving brightness.

The cathode 6 is formed on the surface of the back glass plate 2 facing the front glass plate 1 so as to be perpendicular to the anode 4 formed on the front glass plate l. The cathode 6 is made of nickel, aluminum, etc., and is formed by a method such as thick film printing.

Further, on the rear glass plate 2, each color filter is formed parallel to the anode 4, that is, perpendicular to the cathode 6 on the rear glass plate 2, and on the front glass plate 1. A barrier rib 7 is provided at a position facing the boundary. The barrier ribs 7 are provided to separate adjacent discharge anodes from each other and prevent erroneous discharge. The barrier rib 7 is formed by repeating thick film printing many times and has a typical height of 160 Atm. In the case of a color plasma display, the barrier ribs 7 are generally formed using a white material such as titanium oxide in order to increase the reflectance of ultraviolet rays inside the cell and improve the overall brightness. be.

The portion facing the barrier rib 7 on the front glass plate 1 (
The boundary portion of each color filter becomes a non-light-emitting portion because light emission is blocked by the barrier rib 7. Therefore, a black matrix 8 is provided in the non-light-emitting portion. By providing the black matrix 8, the contrast ratio can be improved. The black matrix 8 is formed by printing a thick film of black paste made of a pigment as close to black as possible, and then firing it at a temperature of about 580°C.

In the color plasma display having the above configuration, a sealed discharge cell is formed by combining a front glass plate 1 and a rear glass plate 2 and sealing the end faces of each using low melting point lead glass or the like. ing. The discharge cell is generally filled with a gas such as xenon. Then, when a voltage is applied between the anode 4 and the cathode 6, a plasma discharge is generated, and each of the above-mentioned phosphors is excited by the ultraviolet rays obtained by this discharge, and visible light of a desired emission color is obtained.

[Problems to be Solved by the Invention] However, in a plasma display having a conventional color filter having the above configuration, since the black matrix is formed by thick film printing of black pigment, the width of the black matrix is 100μm
In a display with a narrow cell pitch, the ratio of the black matrix width to the cell pitch becomes higher, and the width of the discharge cell opening (light emitting area) becomes relatively narrower, resulting in lower brightness. Then there is a problem.

The above problem is especially noticeable in the case of high-definition color displays. For example, in high-definition color displays with a cell pitch of about 300 μm or less, the width of the light emitting area is less than 2/3 of the cell pitch, and the entire width of the cell pitch is The brightness is halved compared to when it is a light emitting area.

On the other hand, it is also conceivable to form a fine line of 100 μm or less, about 50 μm, using a metal thin film process to form a black matrix.

However, metal-based fine lines formed on glass surfaces using known thin film processes have low heat resistance;
It is impractical because it will peel off in the temperature range above and below.

SUMMARY OF THE INVENTION The present invention has been devised to solve the above-mentioned problems, and its purpose is to provide a display device with excellent display quality that can obtain high brightness.

[Means for Solving the Problems] A display device according to the present invention includes a front glass plate, a first color filter formed on the front glass plate and transmitting a first color, and a first color filter formed on the front glass plate and transmitting a first color. In the display device, the display device includes a second color filter that is formed in a color filter and transmits a second color, and a light emitting element that is formed behind the front glass plate.
The end portions of the filter are formed so as to overlap with each other.

[Function] In the display device of the present invention, the black matrix is formed by overlapping the end surfaces of adjacent color filters, so the black matrix can be easily formed by adjusting the dimensions of the overlapping portions. The width can be narrowed. Therefore, compared to displays in which the black matrix is formed by thick film printing, the ratio of the width of the black matrix to the cell pitch can be reduced, and the light emitting area can be relatively widened, resulting in lower brightness. An improved plasma display can be obtained.

[Example] The present invention will be described below based on the illustrated example. The display device in this embodiment is a color plasma display.

FIG. 1 is a partial sectional view showing the internal structure of an embodiment of a plasma display according to the present invention.

In FIG. 1, the same components as in the conventional example are given the same reference numerals, and the explanation will be omitted unless particularly necessary. 31.
32 and 33 are color filters formed on the front glass plate 1. Each color filter is formed by thick film printing using the same filter paste as in the conventional example. Each color filter has a portion (hereinafter sometimes referred to as an overlapping portion) 9 that is overlapped with an adjacent color filter at its end.

In the present invention, each of the color filters described above must be formed by overlapping the ends of adjacent first color filters and second color filters with a predetermined dimension. By overlapping the ends of adjacent color filters, the overlapping part 9 has lower reflectance and transmittance of light compared to the part where each color filter is formed individually, and a black matrix is formed. can act as.

The width of the overlapping portion 9 can be arbitrarily set in consideration of the brightness of the discharge cells, but for example, if the cell pitch is 300
In the case of a high-definition color display on the order of .mu.m, the thickness is usually about 50 .mu.m, and preferably about 30 .mu.m if possible.

Next, an example of a method for manufacturing the plasma display of this embodiment will be described below.

First, a filter paste (viscosity: approximately 20,000 poise) consisting of copper sulfate and an alkali metal salt is applied onto the front glass plate 1 using a 325 mesh screen at a printing pressure of 0.5 kg/rr? , the squeegee angle was 700, the squeegee speed was 25 cm/s, the gap between the screen and the glass plate was 1 mm, the cell pitch was 280 μm, the width of the overlapped portion 9 was 50 μm, the emulsion thickness was 5 μm,
A thick film is printed with a pattern width of 270 μm and baked at 580° C. to form the R filter 31. After washing the surface of the R filter 31 with water, a G filter 32 and a B filter 33 are sequentially formed on the surface of the front glass plate 1 on which the R filter 31 is formed. A paste consisting of copper sulfate, chromium oxide and cobalt oxide is used as the paste for forming the G filter, and a paste consisting of a cobalt pigment is used as the paste for forming the B filter. The conditions for thick film printing and firing are R
This is the same as when forming the filter.

By the method described above, color filters are formed on the surface of the front glass plate 1, in which adjacent color filters and their end portions overlap each other with a width of 50 μm. In addition, in the above-mentioned method of forming a color filter, first,
The reason for forming the R filter is that, as a phenomenon peculiar to the above-mentioned R filter, when the filter paste for forming the R filter is fired at a temperature range of around 580°C, white powder adheres to the surface of the glass plate after firing. This is because the white powder must be washed before forming the other two types of color filters. The white powder is considered to be a reaction residue when the copper contained in the filter paste for forming the R filter reacts with tin (Sn) contained in the front glass plate to achieve the red color, or a residue during firing.

After forming the R filter, either the G filter or the B filter may be formed.

In this example, the light reflectance and transmittance of the individual portions and the overlapping portion 9 of each of the color filters 31, 32 and 33 formed as described above are shown in Table 1 below.

Table 1 As is clear from Table 1 above, the overlapping portion 9 of the color filters formed as described above has lower reflectance and transmittance than the individual portions of each color filter. , can act as a black matrix.

Next, a light emitting element is formed behind the front glass plate 1 on which the color filter is formed as described above. The light emitting element has a transparent electrode 4 formed on each color filter 31, 32, and 33 formed so that the overlapping portion 9 acts as a black matrix by overlapping their ends, and a transparent electrode 4 formed on each color filter. It consists of phosphor layers 51, 52 and 53 of corresponding luminescent colors and a cathode 6 formed on the back glass plate 2. The light emitting element is formed in the same manner as in the conventional method.Next, barrier ribs 7 are formed on the back glass plate 2 in the same manner as in the conventional method. The barrier ribs 7 can prevent erroneous discharge between adjacent discharge anodes.

The barrier rib 7 has a bottom width of about 120 μm,
Thick film printing is repeated many times on the back glass plate 2 so that the width of the top portion reaching the front glass plate 1 side does not exceed the width of the overlapping part 9 of each of the color filters. If the width of the top portion of the barrier rib is larger than the width of the overlapping portion 9 of the color filter, the barrier rib 7 may block the light emission of the phosphor, resulting in a decrease in brightness.

Next, the front glass plate 1 and the back glass plate 2 are stacked on top of each other, and the discharge space created between them is filled with a predetermined gas and sealed. This completes the manufacturing.

Table 2 shows a comparison of the brightness and contrast ratio between the plasma display of the present invention and a conventional example in a dark room, and Table 3 shows a comparison under fluorescent lighting.

Table 2 Table 3 [Effects of the Invention] As explained in detail above, according to the present invention, the overlapping portion formed by overlapping the end surfaces of adjacent color filters acts as a black matrix. , the width of the black matrix can be reduced. Therefore, the width occupied by the black matrix in the cell pitch can be reduced, the brightness and contrast ratio can be improved, and a plasma display with excellent display quality can be obtained.

It should be noted that there are two types of plasma displays: monochrome type and color type, and the present invention can be applied to either type as long as it has a color filter. Further, the present invention can be applied to display devices other than plasma displays.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view showing the internal structure of a color plasma display in this embodiment, and FIG. 2 is a partial cross-sectional view showing the internal structure of a conventional color plasma display. 1... Front glass plate, 2... Back glass plate, 31.32.33... Color filter 4... Discharge anode, 51.52.53... Phosphor layer, 6... Discharge Cathode, 7... Barrier rib, 8... Black matrix, 9... Overlapping part.

Claims (1)

[Claims] A front glass plate; a first color filter formed on the front glass plate and transmitting a first color; and a first color filter formed on the front glass plate and transmitting a second color. In a display device including a second color filter and a light emitting element formed behind the front glass plate, an end of the first color filter and an end of the second color filter are mutually connected to each other. A display device characterized in that the display devices are formed so as to overlap each other.