JPH0922027A - Production of display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device in which so-called nonmodulated light from an area except a pixel electrode can be enough blocked and the contrast ratio which is one of the display performances can be improved. SOLUTION: This method includes the following process. A first substrate is produced by forming a pixel electrode 4 connected to each crossing point of matrix wires comprising plural line electrodes and plural column electrodes via a nonlinear element, applying an insulating light-shielding film material comprising an org. resin on the area except the pixel electrodes, hardening the film at <=400 deg.C to form an insulating light-shielding film 11. Then a second substrate having counter electrodes is formed. The first and the second substrates are disposed to face each other to hold the electrodes and a light- modulating material 8 between the substrates.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and in particular, it has an so-called active matrix type electrode structure in which a non-linear element typified by a thin film transistor is provided at an intersection of matrix wirings, and an electric / optical modulation material such as liquid crystal. The present invention relates to a display device that operates.

[0002]

2. Description of the Related Art Conventionally, a thin film transistor (hereinafter abbreviated as TFT) made of polysilicon, amorphous silicon, tellurium, or a metal / insulating film / metal diode having a sandwich structure of a metal thin film made of aluminum oxide has been used. An active matrix type liquid crystal display device using a non-linear element is disclosed and widely known, for example, in Japanese Patent Laid-Open Nos. 56-25714 and 56-25777.

[0003] With respect to this type of display device, for example, a case in which a TFT is used, a conventional technique will be described.

That is, FIG. 4 (a), which is often used in order to explain the wiring of an active matrix type liquid crystal display device using TFTs, comprises a signal line group and a scanning line group. A TFT is provided at each intersection of the matrix wiring, and one of its source electrode or drain electrode is connected to the pixel electrode.

FIG. 4 (b) is a sectional view taken along line BB of FIG.
The cross section taken along ′ is shown in consideration of the counter substrate, and a liquid crystal 8 is used between the substrate 1 and the counter substrate 2 as electro-optical modulation light, and light irradiation is performed from either of the substrates. In this case, the transmission type is used. At this time, a red (R), green (G), and blue (B) color filter 6 is provided on the counter substrate 2 side in order to display the display device in color. In the figure, reference numeral 3 denotes a polarizing plate, and reference numeral 5 denotes a signal line electrode. And when operating as a transmission type,
The pixel electrode 4 uses a transparent conductive film. Strictly speaking, the liquid crystal operation is limited to only the region of the counter electrode 7.

That is, the liquid crystal 8 on the substrate except for the pixel electrode region does not operate at all. On the substrate 1 provided with the matrix wiring, wiring electrodes for signal lines, wiring electrodes for scanning lines, and TFTs are provided in addition to the pixel electrode regions, and these are electrically connected to each other by the multilayer wiring or wiring arrangement. Insulated. Therefore, for example, even when an opaque material such as a metal thin film is used as the electrode material, a space between wirings is often present, and the liquid crystal 8 does not operate in this area, so-called unmodulated light is transmitted. The unmodulated light means that there is always leakage light for the display device, and increases the background, that is, significantly lowers the contrast.

As a method of reducing the non-modulated light, for example, the rubbing direction of the alignment control film is set to be a right angle, and
There is a method in which the polarizing plates are arranged in parallel so that light is not transmitted when no voltage is applied to the liquid crystal 8.

In this case, since only the pixel electrode region is light-modulated by the signal voltage, in principle, non-modulated light cannot exist. However, when the manufacturing process of the display device is taken into consideration, the polarization directions of the two polarizing plates 3 need to be adjusted to be exactly parallel, and the background due to the leaked light is determined only by this alignment accuracy. Even if the deviation angle is within 1 ° as a practical alignment accuracy, it is very difficult to manage this during mass production.

On the other hand, when the polarizing plate is arranged at a right angle, the angular deviation causes only a slight decrease in the transmittance at the end, has little influence on the contrast, and can be said to be highly producible in mass production. At this time, only the liquid crystal corresponding to the pixel electrode region to which the signal voltage has been applied gives a light modulation effect, and the aforementioned unmodulated light determines the contrast. A conventional method for solving this problem is to provide a light shielding screen with a thin metal film on the counter substrate side.

That is, as shown in FIG. 4 (c), only the R,
This is a method in which the G and B color filters 6 are arranged and all the remaining regions are covered with a light shielding screen 9 made of a metal thin film. This certainly achieves its initial purpose, but this method also has the following disadvantages.

First, both the matrix wiring substrate 1 and the counter substrate 2 provided with the light shielding screen 9 must be fixed in an accurate positional relationship. In such a liquid crystal display device, the pixel pitch is often designed to be several hundred microns. For example, when the pixel pitch is set to 200 microns, the alignment accuracy is about several microns in order to obtain a predetermined aperture ratio.

Also, the light from the light source is hardly a perfect parallel ray, and the aperture ratio is further reduced in consideration of the non-modulated light component of the light obliquely incident on the substrate. For example, the above 2
In the case of the 00 micron pitch, 10 μm in the signal scanning line electrode, and in consideration of the area of the TFT portion, the effective pixel electrode size is approximately 50 to 60% in terms of the aperture ratio. When the precision and the margin of the oblique incident light are taken into account, the aperture ratio is reduced to about 40 to 50%. This decrease in the aperture ratio directly leads to a decrease in the image quality of the display device.

[0013]

As seen in the above-mentioned prior art, the problem of non-modulated light, which is one of the causes of the deterioration of the image quality of the liquid crystal display device, is caused by the polarization direction of the polarizing plate 3, the liquid crystal operating state, the opposite substrate, and the like. Shading screen 9 and matrix substrate 1
Although the light-shielding screen 9 above has been variously devised,
Each has its own disadvantages, and the disadvantages directly lead to a decrease in yield during mass production.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display device which eliminates non-modulated light and which can be easily manufactured to provide a high yield.

[0015]

According to a first aspect of the present invention, a non-linear element is connected to each intersection of a matrix wiring composed of a plurality of row electrodes and a plurality of column electrodes on a first substrate. And a step of applying an insulating light-shielding film material made of an organic resin on a region excluding the pixel electrode and curing the material at a temperature of 400 ° C. or lower to form an insulating light-shielding film. And a step of forming a counter electrode on the second substrate, and a step of arranging the first substrate and the second substrate so as to face each other and sandwiching an electrode / light modulation substance therebetween. It is a manufacturing method.

The invention described in claim 2 is the method of manufacturing a display device according to claim 1, wherein the insulating light-shielding film is cured at a temperature of 200 ° C. or less.

As the material of the insulating light-shielding film in the present invention, one containing a dye as one of its components is suitable. Here, curing means that in the case of a polyimide-based resin, a polyamic acid as a precursor thereof is heat-treated to form a polyimide, and in the case of other organic resins, a heat-shielding film is formed from an organic resin solution and then heat-treated. To remove residual solvent.

The light-shielding effect depends on the spectrum of the light source used, but it is generally desirable that the average optical density in the visible region is 1.0 or more in the light transmittance spectrum, and from the viewpoint of inter-wiring leak current and the like. The electric resistivity is preferably 10 ohm cm or more. In particular, as the organic resin, polyimide, polyamide imide, polyester imide, polyamide, polyester amide,
And a polymer comprising at least one of polyether sulfone is preferable.

As described above, since the insulating light-shielding film is directly provided on the substrate having the matrix wiring, that is, on the pixel electrode portion, the problems of the angle alignment accuracy of the polarizing plate and the problem of the aperture ratio as pointed out in the conventional example can be excluded. Also, unlike metal materials, since they are high-resistance materials, problems such as electrical short circuits and interlayer short circuits can be solved.

Further, regarding the light-shielding effect, in the case of a metal material, an optical density of 4 or more can be easily obtained, but in the case of a polymer material, its transmission spectrum cannot be a constant value over all wavelength ranges. If the average optical density is 1.0 or more in at least the visible region, the purpose of blocking unmodulated light can be sufficiently achieved.

Further, from the viewpoint of the manufacturing process, the light shielding film can be easily formed on the already completed matrix wiring substrate by using the existing photolithography technique, and the alignment precision thereof is simply determined by the precision of the photolithography used. Then
Even during mass production, it is easy to set the accuracy within 3 μm.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will now be described in detail with reference to the drawings.

FIGS. 1 (a) and 1 (b) show an embodiment of a display device according to the present invention. The same parts as those of the conventional example are designated by the same reference numerals, and a TF is used as a non-linear element.
A first substrate on which matrix wiring using T is formed;
This is an example applied to a color liquid crystal display device used in a transmissive TN mode in which a liquid crystal which is an electro-optical modulator is sandwiched between a color filter and a second substrate on which a counter electrode is formed.

That is, 1 and 2 in FIG. 1 (b) are transparent substrates made of glass or the like for sandwiching the liquid crystal 8, and a deflection plate is provided on the outer surface of each of the substrates 1 and 2. Has been.

Further, the substrate 1 is also called a matrix substrate, and the scanning line connected to the gate electrode of the TFT and the pixel electrode 4 connected to the drain electrode or the source electrode are formed on the inner surface of the transparent substrate 1. Has been formed.

In the present invention, the insulating light-shielding film 11 is provided in order to block the transmitted light which passes through other portions except the pixel electrode 4 region on the substrate 1, that is, the regions such as the matrix wiring and the TFT. A liquid crystal orientation control film (not shown) made of, for example, polyimide, polyamide, polyvinyl alcohol, or the like is provided on the light shielding film 11 by rubbing treatment, and is in contact with the liquid crystal 8.

On the other hand, on the inner surface of the substrate 2, R, G, B color filters 6 are formed at positions corresponding to the respective pixel electrodes 4, and on the color filters 6, for example, an indium tin oxide film or the like is formed. A transparent conductive film and a counter electrode 7 made of a rubbing-processed liquid crystal alignment control film (not shown) are formed on the transparent conductive film, and are in contact with the liquid crystal 8.

Next, as a particularly specific example, a case where a polymer containing a black dye is used as a material of the insulating light-shielding film 11 will be described.

The polymer used as the base material is required to have excellent electrical insulation and heat resistance and good compatibility with the dye. Specific examples include polyimide, polyamideimide, polyesterimide and polyamide. , Polyesteramide, polysulfone, polyethersulfone, polyarylate, polyetheretherketone, polyacetal, polycarbonate, nylon, polybutylene terephthalate, (modified) polyphenylene oxide, polyphenylene sulfide, epoxy resin, unsaturated polyester resin, bismaleimide resin, etc. These polymers may be used in one kind or in a mixed system of two or more kinds.

The black dye may be any one as long as it absorbs light in the visible range, that is, in the wavelength range of at least 400 to 800 nm. Specific examples thereof include products manufactured by Sumitomo Chemical Co., Ltd. Name Amil Black F-8
BL, Sumilite Black Gconc, Direct Deep Black XA, Sumifix Black B, Amil Black F-GL, Sumicaron Black S-BF, Spirit Black No. 920, Japananol First Black Dconc, Sumicolor Black PR-3F-3
65, Sumicolor Black PR-8T-364, Sumicolor Black PR-8T-363, Oil Black No
1. Mitsui PS Black EX-58 and Mitsui PS Black EX-174 manufactured by Mitsui Toatsu Chemicals, Inc .; Oleosol First Black B manufactured by Taoka Chemical Co., Ltd.
LN and the like.

It also includes a method in which two or more coloring dyes such as a red dye, a blue dye, a green dye and a yellow dye are blended and blackened to be used.

The amount of the black dye used in the present invention is in the range of 1 to 200 parts by weight, preferably 5 to 150 parts by weight, based on 100 parts by weight of the polymer. When the amount of the black dye used is less than 1 part by weight, the light absorbing effect is poor.
If it exceeds 200 parts by weight, it becomes difficult to form a coating film.

In the present invention, it is also possible to use an infrared absorbing agent for the purpose of improving the effect of light absorption ability. The infrared absorber used at this time is 700 to 1
There is no particular limitation as long as it absorbs light in a wavelength region of 500 nm. Specific examples include PA1001, PA1005, and PA1 manufactured by Mitsui Toatsu Chemicals, Inc.
HR and HR series such as HR102 and HR105-R manufactured by Hodogaya Chemical Industry Co., Ltd. The amount of these infrared absorbers used is
0.1 to 50 parts by weight based on 100 parts by weight of the polymer,
Preferably it is in the range of 0.5 to 40 parts by weight.

Next, a specific example will be given to explain in more detail.

Specific Example 1 Preparation and Performance of Black Polymer Pyrromellitic dianhydride was added to a reaction flask (internal volume: 500 ml) equipped with a stir bar, thermometer and dropping funnel.
086 g, 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride 19.340 g and N, N-dimethylacetamide 150 g were added, and the mixture was sufficiently stirred and kept at 0 ° C. A solution obtained by dissolving 17.538 g of 1,4-bis (4-aminophenoxy) benzene in 130 g of N, N-dimethylacetamide was gradually added dropwise to the addition funnel. After completion of the dropwise addition, the mixture was stirred at 0 to 10 ° C for 4 hours to obtain a polyamic acid solution. 4.2 g of a black dye (trade name: Spirit Black 920, manufactured by Sumitomo Chemical Co., Ltd.) and an infrared absorber (trade name: PA100, manufactured by Mitsui Toatsu Chemical Co., Ltd.) were added to the polyamic acid solution thus obtained.
6) A solution prepared by dissolving 1.0 g of N, N-dimethylacetamide in 35 g was added and thoroughly mixed to obtain a black polyamic acid solution. This solution was applied to a quartz glass wafer by spinner at a rotation speed of 2000 rpn. Then 100
The film was dried and cured at 20 ° C. for 20 minutes, 150 ° C. for 20 minutes, and 250 ° C. for 1 hour to form a black polyimide film having a thickness of 1.8 μm. The light transmittance of the black polyimide film obtained by measuring the light transmittance of the black polyimide film thus obtained was satisfactory as shown in FIG.

Concrete Example 2 Manufacturing Method and Performance of Display Device By a conventional method, a scanning line electrode, a signal line electrode, a TFT using hydrogenated amorphous silicon as a semiconductor material, a pixel electrode and the like are formed on a glass transparent substrate. Black polyamic acid solution 2
Spinner coating at 000 rpm, then dried and cured at 100 ° C. for 30 minutes and 150 ° C. for 1 hour to give a film thickness of 2.0
A μm black polyimide film was formed. Next, using a known photolithography technique, a desired pattern including an opening in a pixel electrode portion was obtained. Here, a hydrazine / ethlenediamine (weight ratio: 5: 5) solution was used for etching the black polyimide. Subsequently, after performing drying with nitrogen gas, the polyamic acid was completely cured by performing a heat treatment at 200 ° C. for 1.5 hours. An alignment control film is provided on the surface of the substrate thus prepared in accordance with a conventional method, rubbed, and a liquid crystal display device is formed by pairing with a counter electrode substrate provided with a color filter, a transparent counter electrode, an alignment control film, and the like in advance. Produced. FIG. 3 shows the measurement results of the transmittance characteristics with respect to the signal voltage of the display device thus obtained.

As is apparent from FIG. 3, the contrast ratio was about 10 in the case of the conventional method, but due to the effect of the light-shielding film 11 in the present invention, the contrast ratio is 50, which is a great improvement. Was given.

[0038]

As described above in detail, the display device of the present invention has a function of sufficiently blocking so-called non-modulated light from other regions excluding the pixel electrode, which is one of the display performances. It greatly contributes to the improvement of the ratio.

Further, by using the insulating light-shielding film material, it is not necessary to structurally consider electrical short circuit, leak, etc., and it can be easily applied to all display devices using existing active matrix wiring. .

In particular, when a black polymer which absorbs light very much is adopted, it is possible to provide an inexpensive display device which can be manufactured by an easy process and which is lightweight and thin.

[Brief description of drawings]

1A is a plan view of a display device according to an embodiment of the present invention, and FIG. 1B is a sectional view taken along line AA ′ of FIG. It is a figure.

FIG. 2 is a characteristic curve diagram showing a transmittance spectrum of a black polymer in the display device of the present invention.

FIG. 3 is a characteristic curve diagram showing a transmittance-signal voltage characteristic in the display device of the present invention in comparison with a conventional example.

FIG. 4A is a plan view of a conventional display device,
4B is a sectional view taken along the line BB ′ of FIG. 4A and viewed in the direction of the arrow, and FIG. 4C is a cross-sectional view of BB ′ of FIG.
It is sectional drawing cut | disconnected along the line and seen in the arrow direction.

[Explanation of symbols]

 1, 2 ... Substrate 3 ... Deflection plate 4 ... Pixel electrode 5 ... Signal line 6 ... Color filter 7 ... Counter electrode 8 ... Liquid crystal 11 ... Light-shielding film

Claims (2)

[Claims] 1. A step of forming a pixel electrode connected to each intersection point of a matrix wiring composed of a plurality of row electrodes and a plurality of column electrodes on a first substrate through a non-linear element, and the pixel electrode A step of applying an insulating light-shielding film material made of an organic resin on the removed region and curing it at a temperature of 400 ° C. or lower to form an insulating light-shielding film; and a step of forming a counter electrode on the second substrate. And a step of arranging the first substrate and the second substrate so as to face each other and sandwiching an electrode / light modulating substance between them. 2. The method of manufacturing a display device according to claim 1, wherein the insulating light-shielding film is cured at a temperature of 200 ° C. or lower.