JPH10106442A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the contrast of an image display device without decreasing brightness too much in the image display device provided with a color filter. SOLUTION: In an image display device equipped with a display picture element area A, and filter portions 11 of a color filter in the display picture element area A, such a filter as an occupying rate of the filter portions 11 in the display picture element area A is not 100%, but a part where coloring colors are not filtered exists. It is desirable that the occupying rate of the filter portion 11 in the display picture element area A is 30 to 95%. Thereby, the contrast of a display image can be enhanced without decreasing brightness too much.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image display device provided with a color filter such as a plasma display panel (PDP), a field emission display (FED), and a cathode ray tube (CRT).

[0002]

In the case of color display in the image display device as described above, it is common to provide a color filter on the side where the observer visually recognizes. However, there is a problem that the contrast deteriorates when a color filter is provided.
This will be described using P as an example.

[0003] In general, a PDP is provided with a pair of electrodes arranged regularly on two opposing glass substrates, and a gas mainly composed of an inert gas such as Ne, He or Xe is sealed between the two substrates. Has a structure. Then, by applying a voltage between these electrodes and generating a discharge in a minute cell around the electrodes, each cell is made to emit light and display is performed. The cells arranged regularly are selectively discharged and emitted. This P
The direct current type (DC) in which the electrode is exposed to the discharge space
Type) and an AC type (AC type) covered with an insulating layer. Both types are further classified into a refresh driving method and a memory driving method depending on the display function and the driving method.

FIG. 1 shows a configuration example of an AC type PDP. This figure shows the front plate and the back plate separated from each other. As shown in the figure, two glass substrates 1 and 2 are arranged in parallel and opposed to each other, and both become the back plate. The cell barriers 3 provided on the glass substrate 2 in parallel to each other are held at regular intervals. On the back side of the glass substrate 1 serving as a front plate, composite electrodes composed of a transparent electrode serving as a sustain electrode 4 and a metal electrode serving as a bus electrode 5 are formed in parallel with each other, and a dielectric layer 6 is covered thereover. The protective layer 7 (MgO layer) is further formed thereon. On the other hand, on the front side of the glass substrate 2 serving as a back plate, address electrodes 8 are formed between the cell barriers 3 so as to be orthogonal to the composite electrode and parallel to each other. A phosphor 9 is provided so as to cover the cell bottom. The AC type PDP is of a surface discharge type, and has a structure in which an AC voltage is applied between composite electrodes on a front panel to discharge by an electric field leaking into a space. In this case, since the alternating current is applied, the direction of the electric field changes according to the frequency. Then, the phosphor 9 is caused to emit light by the ultraviolet light generated by the discharge, and the light transmitted through the front plate is visually recognized by the observer.

[0005] By the way, various improvements have been made so far in the color PDP as described above, but at present the contrast is not sufficient because of the insufficient luminance of the PDP itself. In order to make the display easier to see, it is effective to reduce the reflectance of the image display surface and improve the contrast of the displayed image. One way to achieve this is to use a ND (Neutral Density) filter characteristic on the front panel. To have. Nd ₂ O ₃ is put in the front plate to give absorption characteristics outside the main spectrum of the luminous body. Fill the area other than the fluorescent layer with a low reflection material. That is,
A black matrix is formed. The pigment is mixed with the fluorescent layer. A pigment layer is formed before the fluorescent layer. A color filter that transmits only a single wavelength of the emission spectrum is provided for each of the red, green, and blue cells. However, unlike a CRT, a PDP does not have much room for luminance, and therefore, a color filter with a black matrix is effective in minimizing a decrease in luminance and increasing contrast. However, when a black matrix (BM) and a color filter composed of three colors of red (R), green (G), and blue (B) are provided, the color filter covers the entire display area surrounded by the black matrix. Is formed, the luminance is reduced by the filter portion. Such a problem is not limited to the PDP, but also applies to other image display devices.

An object of the present invention is to provide an image display device having a color filter capable of improving the contrast of a displayed image without significantly lowering the luminance.

[0007]

In order to achieve the above object, the present invention provides an image display apparatus having a display pixel region and a filter portion of a color filter in the display pixel region, wherein the filter portion occupies the display pixel region. The ratio is 10
It is characterized by having a color filter having a portion where the emission color is not filtered instead of 0%. It is desirable that the ratio of the filter portion in the display pixel area is 30 to 95%.

[0008]

FIG. 2 is an explanatory diagram showing the relationship between a black matrix and color filters when display pixels are in a matrix. In order to obtain this pattern, a grid-like black matrix 10 is formed so as to divide the rectangular display pixel area A, and furthermore, the center of each display pixel area A, that is, the space between the display pixel area A and the surrounding black matrix 10 is provided. Is opened to form the filter portion 11 of the color filter in a predetermined color arrangement. In this case, the ratio of the filter portion 11 of the color filter to the area of the display pixel region A surrounded by the black matrix 10 is 30 to 9
Set to be 5%. That is, the filter part 1
If the proportion of 1 is less than 30%, the phosphor becomes white as a whole when it is not emitting light, and if it exceeds 95%, the brightness decreases. This condition is as follows when the horizontal and vertical lengths of the display pixel area A are a ₁ and b ₁ , respectively, and the horizontal and vertical lengths of the filter portion 11 are a ₂ and b ₂ , respectively. It is represented by equation (1). 0.3 ≦ (a ₂ b ₂ / a ₁ b ₁ ) ≦ 0.95 (1)

FIG. 3 is an explanatory diagram showing the relationship between the black matrix and the color filters when the display pixels are striped. In order to obtain this pattern, a linear black matrix 10 is formed so as to divide the stripe-shaped display pixel area A, and furthermore, the center of each display pixel area A, that is, an interval between the black matrix 10 on both sides, is provided. Is opened to form the filter portion 11 of the color filter in a predetermined color arrangement. Also in this case, with respect to the area of the display pixel region A sandwiched between the black matrices 10,
The ratio occupied by the filter portion 11 of the color filter is 3
Set to be 0-95%. That is, if the ratio occupied by the filter portion 11 is less than 30%, the phosphor becomes white as a whole when the light is not emitted, and the luminance decreases if the ratio exceeds 95%. This condition is such that the width of the display pixel area A and the width of the filter portion 11 are a,
When a ′ is set, it is expressed by the following equation (2). 0.3 ≦ (a ′ / a) ≦ 0.95 (2)

When the above color filters are provided on the front panel of the AC type PDP shown in FIG. 1, they are provided on a glass substrate, between the composite electrode and the dielectric layer, in the dielectric layer (in this case, , The dielectric layer is composed of at least two layers), between the dielectric layer and the protective layer. When a black matrix and a color filter are formed on a glass substrate, an overcoat layer is provided for the purpose of flattening these irregularities. The overcoat layer is transparent and has a visible light transmittance of 80 or more over the entire display area.

[0011] The black matrix is composed of Cu-Cr, Cu-Cr-
It is formed by firing a black glass powder obtained by mixing 2 to 50 parts by weight of an inorganic black pigment powder made of Mn, Cu-Cr-Co, Cu-Cr-Mn-Fe, or the like.

As the colorant for the filter portion of the color filter, any heat-resistant pigment can be used. In this case, although it depends on the manufacturing process of the substrate, it is usually sufficient if the substrate has heat resistance of about 450 to 600 ° C. Also,
Colored glass that can ensure wavelength selectivity with a thin film thickness can also be used. It is also effective to mix a glass frit with a low melting point to improve color development and its stability, heat resistance, adhesion and surface smoothness.

Although there are many types of heat-resistant pigments, typical ones are iron (red), manganese aluminate (pink), gold (pink), antimony-titanium-chromium (orange), iron -Chromium-zinc (brown), iron-based (brown), titanium-chromium-based (yellow-brown), iron-chromium-zinc-based (yellow-brown), iron-antimony-based (yellow-brown), antimony-titanium-chrome-based (Yellow), zinc-vanadium (yellow), zirconium-vanadium (yellow), chromium (green), vanadium-chromium (green), cobalt (blue), cobalt aluminate (blue), vanadium- There are zirconium-based (blue), cobalt-chromium-iron-based (black), and the like. It is desirable that particles having a particle size of 1 μm or more account for 10% by weight or less of all particles. That is, if there are many particles having a large particle diameter, the transmittance is reduced and the luminance is reduced. Further, the particle size is 0.01 to
It is desirable that 0.7 μm particles account for at least 20 wt% of all particles.

There are many types of colored glass due to the coloring mechanism. Also, the color of the same raw material changes depending on the conditions. As an example, the frit is made of silicic acid (SiO ₂ ), lead oxide (Pb).
O), potassium oxide (K ₂ O), boric acid (B ₂ O ₃ ), aluminum fluoride (AlF ₃ ), potassium lead glass containing arsenic oxide (As ₂ O ₃ ), etc. as a main component. , Silica stone, lead red, yellow lead oxide, lead white, potassium nitrite, boric acid, borax,
Sodium bicarbonate, fluoride and the like are used. As coloring agents, arsenous acid (white), tin oxide (white), copper oxide (green), cobalt oxide (blue), potassium dichromate (yellow), antimony oxide (yellow), iron oxide (brown), manganese dioxide (Purple), nickel oxide (purple), gold chloride (red), sodium uranate (orange), selenium red (reddish red) and the like are combined and mixed. Then, a mixture obtained by mixing, heating and melting, vitrifying and cooling and pulverized is used.

The color filter can be formed by using a color glass paste or a glass paste in which an inorganic pigment is dispersed as a paste material, patterning the paste material by screen printing, and then firing. In addition, a photosensitive paste obtained by adding a photosensitive resin to a colored glass paste or a photosensitive paste obtained by adding a photosensitive resin to a glass paste in which an inorganic pigment is dispersed is used as a paste material, and the paste material is coated. After that, a photolithography method may be used in which patterning is performed by exposure through a mask and subsequent development, followed by baking to form the color filter.

[0016]

【Example】

(Embodiment 1) In this embodiment, a grid-like black matrix and color filters are formed on a glass substrate 1 as shown in FIG. Specifically, first, a black glass powder paste was applied by screen printing and fired to form a black matrix. Next, three types of color glass pastes of red, green and blue were used as paste materials for the filter portion, these were patterned on the glass substrate 1 by screen printing, and then fired to form color filters. Here, the filter portion 11 was formed with five pattern sizes shown in Table 1. The color glass paste used is a transparent glass component (50 to 90 watts) corresponding to each of the above colors by ionic coloring or colloidal coloring.
t%) and an organic vehicle (10 to 50 wt%) obtained by kneading ethyl cellulose and terpineol. A screen plate of 300 mesh is used, and the glass paste of each color is adjusted to a viscosity of 20 by appropriately adding an organic vehicle.
The print was adjusted to about 0 to 1000 poise. A belt-type firing furnace was used for firing, and a thermal gradient of 350 to 580 ° C was created, and firing was performed at 580 ° C for 20 minutes or more, for a total of 120 minutes. The belt speed was 80 mm / min. Moreover, you may make it bake at 600 degreeC for 15 minutes using a batch type baking furnace.

After the sustain electrode 4 and the bus electrode 5 are formed on the color filter, a 300 mesh screen printing is performed using a colorless transparent glass paste ("PLS3162S", manufactured by Nippon Electric Glass Co., Ltd.). Print all over with
By firing, the dielectric layer 6 was formed. A protective layer 7 was formed thereon to produce a front panel. Table 1 shows the evaluation results of the front panel thus obtained.

[0018]

[Table 1]

As can be seen from Table 1, when the CF (color filter) occupancy is 20%, the contrast is low.
The brightness of 100% is considerably reduced, but 30 to 95%.
% Was favorable in the overall evaluation from the viewpoint of luminance and contrast.

(Embodiment 2) In this embodiment, the glass substrate 1
After a sustain electrode 4 and a bus electrode 5 are formed on the substrate, a dielectric layer 6 covering them is formed in two layers, and a striped black matrix and a color filter as shown in FIG. 3 are formed therebetween. The first layer of the dielectric layer 6 is made of a colorless transparent glass paste ("PLS3162" manufactured by Nippon Electric Glass Co., Ltd.).
S ") using a 300 mesh screen printing (solid printing). Next, the black matrix was formed by applying a photosensitive black glass powder paste over the entire surface by screen printing, patterning through an exposure step and a development step, and then firing. The color filter was formed by using a paste material obtained by dispersing a pigment in a colorless and transparent glass paste, patterning the screen material by screen printing, and forming the color filter on the first dielectric layer by firing. Here, the filter portion 11 was formed with five pattern sizes shown in Table 2. The paste material for each color is
Pigment particle size 0.01-0.5μ with paint shaker
m, and the finely divided inorganic pigment (10
-20% by weight) and a colorless transparent glass paste (80-90%).
wt%) was kneaded and dispersed using a three-roll mill for 20 to 30 minutes. Further thereon, a second layer of the dielectric layer 6 was similarly formed using the same material as described above. The printing conditions and baking conditions are the same as in the first embodiment. The baking step may be performed after printing of each layer, or may be performed simultaneously after forming each layer in a dry state.

On the second layer of the dielectric layer 6, a protective layer 7 was formed to produce a front plate. Table 2 shows the evaluation results of the front panel thus obtained.

[0022]

[Table 2]

As can be seen from Table 2, when the CF (color filter) occupancy is 20%, the contrast is low.
The brightness of 100% is considerably reduced, but 30 to 95%.
% Was favorable in the overall evaluation from the viewpoint of luminance and contrast.

[0024]

As described above, the image display device of the present invention can improve the contrast of the displayed image without significantly lowering the luminance because there is a portion where the emission color is not filtered in the display pixel region. it can.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing an example of a configuration of an AC type plasma display panel in a state where a front plate and a back plate are separated from each other.

FIG. 2 is an explanatory diagram showing a relationship between a black matrix and a color filter in which a display pixel is a matrix type.

FIG. 3 is an explanatory diagram showing a relationship between a black matrix and a color filter in which a display pixel is a stripe type.

[Explanation of symbols]

 A display image area 10 black matrix 11 filter part

Claims (2)

[Claims] In an image display device having a display pixel region and a filter portion of a color filter in the display pixel region, the ratio of the filter portion in the display pixel region is 10%.
An image display device comprising: a color filter having a portion where emission color is not filtered, which is not 0%. 2. The image display device according to claim 1, wherein the ratio of the filter portion in the display pixel area is 30 to 95%.