JPH10260401A - Liquid crystal color filter and method of manufacturing liquid crystal color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color filter having high electrical insulation and liquid crystal display performance, and a photoresist used for selectively forming each of R, G, B layers by an electrolytic method. To provide a method for preventing peeling of flakes. SOLUTION: Between electrode lines 22 on a glass substrate 23, the width is 10 μm, the thickness difference is 1.2 μm, and the resistivity is 10 ⁸ Ωm.
As described above, the light shielding layer 21 is formed with a light transmittance of 0.1% to 10%. Positive photoresist 2 on entire surface of glass substrate 23
After application of No.4, only the electrode for forming the R layer is exposed by a pre-baking and a photomask on which a predetermined pattern is formed. R layer 2 composed of organic pigment and transparent conductive particles by electrolysis
5 is formed. Each layer of G (green) 26 and B (blue) 27 is also formed by repeating the above steps. A polyimide alignment film is applied to this color filter, cured by heating, and bonded to a counter electrode substrate to form a liquid crystal panel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter used for a liquid crystal display device such as a liquid crystal display device for a personal computer and a liquid crystal display device for a portable information terminal, and a method of manufacturing the color filter.

[0002]

2. Description of the Related Art A dyeing method, a pigment dispersion method, an electrodeposition method and the like have been put to practical use as a method for producing a color filter for a liquid crystal display device. On the other hand, we have conventionally proposed the following color filters. That is, it is a color filter in which an organic pigment and transparent conductive particles having a hydrophobic surface are co-dispersed in a surfactant solution having redox reactivity, and the organic pigment and the transparent conductive particles are codeposited by electrolysis (International Publication number WO 94/27173). In this color filter, a transparent electrode layer having a predetermined pattern is formed on a substrate in advance, and an organic pigment and the transparent conductive particles are codeposited on the transparent electrode layer by electrolysis. This eutectoid layer has at least 1.3 R (red), G (green) and B (blue) layers by a conventional pigment dispersion method / dyeing method or electrodeposition method.
Although a thickness of about μm was necessary for spectral characteristics, a sufficient spectral characteristic can be obtained with a thickness of 1.2 μm because it does not include a resin component. When this is actually used as a liquid crystal display device, a liquid crystal panel is formed by a predetermined process.
The transparent electrode layer is also used as an electrode for driving a liquid crystal. Usually, a light shielding layer is provided between the patterns of the transparent electrode layer. As the light-shielding layer, a metal thin film of Cr or the like, a resin film in which carbon fine particles are dispersed, and the like are known as general materials. The purpose of using the light-shielding layer is to suppress unnecessary light transmission in the liquid crystal panel and improve the contrast. Cr is of course electrically conductive, but a resin in which carbon fine particles are dispersed is also added with a large amount of carbon particles in order to emphasize light-shielding properties, and usually has a resistivity much lower than 10 ⁸ Ωcm.

[0003] The above-mentioned color filters are formed as follows in forming the three primary colors of R, G and B on the transparent electrode layer.
This will be described with reference to the cross-sectional view of FIG. A positive photoresist layer 32 is formed on the entire surface of a glass substrate 33 (FIG. 3).
(A)) Only the portion of the electrode layer where the organic pigment and the transparent conductive particles are desired to be eutectoid is developed to expose the transparent electrode layer 31 (FIG. 3 (b)). Depending on the selection of the organic pigment exhibiting the RGB color tone, the RGB color filter layer 34 can be selectively formed by repeating this process three times and electrolyzing each (FIG. 3C).

[0004]

The above prior art has the following problems.

[0005] 1. Since the conventional light-shielding layer material is a metal film or a resin film containing a large amount of carbon, the light-shielding property is sufficiently high and a light transmittance of 0.01% or less at a wavelength of 550 nm. However, the resistivity was basically considerably lower than 10 ⁸ Ωcm, and the film was conductive. Therefore, when formed between the transparent electrode layers, there is a problem that the electrode patterns are electrically connected to each other, and the liquid crystal cannot be driven when a liquid crystal panel is formed.

[0006] 2. Usually, the substrate on which a color filter is formed is a glass substrate on which a transparent electrode layer (generally indium tin oxide or tin oxide) is formed. The glass surface is exposed by etching, and the glass surface is exposed. When a photoresist layer is formed on the entire surface of the substrate to selectively form the R, G, and B layers,
Most of them directly cover the glass surface. In general, photoresist has poor adhesion to a smooth glass surface, and peels off very easily, especially when immersed in an electrolytic solution during electrolysis, and floats in the electrolytic solution to hinder the formation of the R, G, and B layers. Gave.

[0007] The present invention solves the above-mentioned problems, and an object of the present invention is to provide high electrical insulation,
Provide a color filter for a liquid crystal having a light-shielding layer that does not hinder the driving of the liquid crystal, and manufacture a color filter for a liquid crystal that can prevent peeling of a photoresist used for selectively forming each of R, G, and B layers by an electrolytic method. It is to provide a method.

[0008]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems, and comprises the following means.

In the liquid crystal color filter of the present invention, a transparent electrode layer having a predetermined pattern is formed on a glass substrate, and a predetermined portion of the transparent electrode layer and a predetermined portion between the patterns have a resistivity of at least a resin and an organic pigment. 10 ⁸ Ωc
m, a light-shielding layer pattern having a thickness of 0.2 to 1.2 μm and a light transmittance of 0.1 to 10% at a wavelength of 550 nm is formed, and a portion surrounded by the light-shielding layer pattern; A color filter layer of RGB three primary colors or YMC three primary colors having a predetermined arrangement of at least an organic pigment and transparent conductive particles is formed in a portion where the transparent electrode layer is exposed, and a transparent layer is formed on the light shielding layer and the color filter layer. A characteristic overcoat layer is formed.

Further, R (red), G (green), B
(Blue) Each color filter layer or Y (yellow)
· M (magenta) · C (cyan) color filter layers are deposited by electrolysis.

The resistivity of the light-shielding layer can be defined on the following grounds. That is, a common electrode, which is a liquid crystal driving electrode in the horizontal direction, is usually formed on the color filter substrate. V
It is formed as 480 linear electrodes for GA display and 600 linear electrodes for SVGA display. The length of this line is about 32 cm including the IC mounting part in the SVGA display panel having a diagonal length of 15 inches. The gap between the electrode lines is limited to 10 μm in processing. Therefore, if the thickness is 1.2 μm, the width is 10 μm, and the length is 32 cm, the gap is 10 μm.
^When a light-shielding layer having a resistivity of ⁸ Ωcm is formed, the resistance of the light-shielding layer between two electrode lines is calculated to be 2.6 * 10.
⁷ Ω. We assume that the resistance between these electrode lines is 10
It was experimentally confirmed that when the resistance was ⁷ Ω or more, no electrical leakage occurred between the electrodes when the liquid crystal was driven. If the distance between the electrode lines is 10 μm or more, the thickness of the light-shielding layer is 1.2 μm, and the size of the liquid crystal panel is 15 inches or less on the diagonal, the resistance value between the electrode lines can be increased, so that the problem of the leak between the electrodes is eliminated. .

On the other hand, it has been experimentally confirmed that the light-shielding property is practically sufficient if a light transmittance (550 nm) in the range of 0.1 to 10% can be ensured, particularly when used in an STN type liquid crystal panel. .

The reason why the thickness of the light shielding layer is set to 0.2 to 1.2 μm is as follows. For example, each of the RGB color filter layers can provide sufficient spectral characteristics with a maximum thickness of 1.2 μm when used in a normal transmission type liquid crystal panel, and has a practical thickness of 0.2 μm when used in a reflection type liquid crystal panel. it can. For this reason, it is better to be within the range equivalent to these film thicknesses.
Preferably, the difference between the thickness of each of the RGB layers and the thickness within 0.2 μm is desirable. The main reason is to prevent poor alignment of the liquid crystal due to a step.

According to the method of manufacturing a color filter for liquid crystal of the present invention, a transparent electrode layer is formed on a glass substrate, the transparent electrode layer is etched into a predetermined pattern, and the transparent electrode layer is selectively formed on the transparent electrode layer by an electrolytic method. In the method for manufacturing a color filter for a liquid crystal for forming a color filter layer, at least a region cut out for use as a liquid crystal panel is left as it is without etching the transparent electrode layer or is not covered with the transparent electrode layer outside the region. When a portion is provided, the portion not covered with the transparent electrode layer is characterized in that at least the short side has a length of 10 mm or less or a diameter of 10 mm or less.

Since it is necessary to make marks required for ultraviolet exposure and panel assembly on the transparent electrode layer, an exposed glass surface is generally inevitably formed, but there is no problem with the above shape.

The above area definition was confirmed experimentally and used as a basis. The exposed glass portion in the area finally used as the liquid crystal panel is not a problem because it is 10 mm or less in width or covered with a light-shielding layer.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1) 300 mm x 400 mm with a thickness difference of 0.7 mm
Indium tin oxide (hereinafter I)
A transparent electrode layer (abbreviated as TO) was formed with a thickness of 0.2 μm. In order to etch this transparent electrode layer into a predetermined pattern, a positive type photoresist (OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied in a thickness of 1.5 μm on the entire surface of the transparent electrode layer and baked at 90 ° C. for 10 minutes. . The film was exposed to ultraviolet light using a predetermined photomask, developed with an alkaline developer, and the photoresist was removed only from the portion where the transparent electrode layer was to be etched. Soak the substrate in a mixed solution of hydrochloric acid and nitric acid,
The portion of the ITO from which the photoresist was removed was etched away to form a pattern as shown in FIG. A rectangular area 11 surrounded by a straight line is a color filter substrate which is finally cut out for use as a liquid crystal panel.
In this embodiment, a diagonal size of 15 inches (32 cm × 2
3.5 cm). At this time, in the region 11, 600 electrodes 12 (finally electrodes used as a common electrode as a liquid crystal panel) for forming R, G, and B layers by electrolysis were formed in a line. ITO is etched so that a 10 μm gap is formed between the lines. The region 11 has a glass exposed surface of 320 mm in the length direction, but no glass exposed surface longer than 10 mm in width. Area 1
The outside of No. 1 was basically processed so that ITO was left as it was without being etched. However, a region 13 (10 mm × 10 mm area,
2), a region 14 (an area of 10 mm in diameter, 4) for forming a mark to be used when applying an alignment film in a panel forming process.
Area) and an area 15 (10 mm × 50 mm, 4 places) for forming a mark required for assembling the panel basically have minute size marks made of ITO. The surface is exposed.

Subsequently, a light shielding layer was formed. The light-shielding layer material is obtained by blending carbon fine particles (13% by weight) and an organic pigment (30% by weight) in a photosensitive acrylic resin as a solid content and coating the resultant with a cellosolve-based solvent. ^One having a resistivity of ⁸ Ωcm was used. FIG. 2 is a diagram schematically showing a cross section taken along line AA ′ of FIG. Between the electrode lines 22 on the glass substrate 23, a width of 10
The light shielding layer 21 was formed with a thickness of 1.2 μm and a thickness difference of 1.2 μm (FIG. 2).
(A)). The light transmittance was 0.1% (550 nm wavelength). The formation was performed by applying a light-shielding layer material over the entire surface by spin coating, followed by pre-baking, ultraviolet exposure using a photomask having a predetermined pattern formed thereon, development, and heating curing. Note that the light-shielding layer may be formed in a lattice shape not only between the electrodes but also over the electrodes.
Can be provided as needed in the portion inside the.

Subsequently, R, G and B layers were formed. As shown in FIG. 2B, as a first step of forming a color filter layer, a positive photoresist 24 was applied to the entire surface of the glass substrate 23 to a thickness of 1.5 μm, and then pre-baked to form a predetermined pattern. UV exposure with a photomask, development, and post-baking were performed to expose only the electrode for forming the R layer. As the positive photoresist, OFPR-800C manufactured by Tokyo Ohka Kogyo Co., Ltd., which was determined to have the best adhesion to the glass surface among the evaluations, was used.

As a second step of forming a color filter,
An R layer 25 comprising an organic pigment and transparent conductive particles (ITO particles subjected to hydrophobic surface treatment) was formed by electrolysis as shown in FIG. The film thickness was 1.0 μm. As a specific forming method procedure, first, an electrolytic solution was prepared. The following components were blended and dissolved or dispersed in pure water.

[0021]

[Table 1]

Dispersion was carried out for 90 minutes with ultrasonic waves of 20 kHz. The substrate prepared in FIG. 2B was immersed in the prepared electrolytic solution to perform electrolysis. The positive photoresist on the top edge of the board was partially peeled off, clipped, and connected to the positive side of the DC power supply. Similarly, a platinum-plated titanium counter electrode was immersed in the electrolyte and connected to the negative side of the DC power supply. An electrolysis voltage of 0.6 V was applied and electrolysis was performed for 10 minutes.

The applied positive photoresist is applied to the area 11
The R layer was formed in an extremely favorable state without any peeling off inside and outside of.

After the electrolysis, the substrate was washed with water and dried, and thereafter, all the positive type photoresists were peeled off with a 3% aqueous KOH solution, washed sufficiently with water, and heated at 180 ° C. for 30 minutes. At this stage, the state is as shown in FIG.

Each layer of G (green) 26 and B (blue) 27 was also formed by repeating the above steps (b) to (c) of FIG. 2 (FIG. 2 (e)). The composition of the used electrolyte was as follows.

[0026]

[Table 2]

The thickness of the formed layer is 1.0 μm for both G and B.
And As in the case of R, the positive photoresist did not peel off at all.

Finally, the state as shown in FIG. 2E was completed, and a transparent thermosetting acrylic resin was overcoated over the entire surface with a thickness of 0.2 μm. Through the above steps, the color filter of this example was completed.

A polyimide alignment film having a thickness of 0.05 μm was applied to the color filter and cured by heating. 6.
A liquid crystal panel was formed by bonding to a counter electrode substrate with a cell gap of 3 μm. Predetermined shape (color filter side is area A
The liquid crystal was injected, and the overcoat and the polyimide film at the end of the electrode line were removed by ashing with oxygen plasma. Further, a liquid crystal driving IC was mounted on the end of the electrode line including the opposing substrate.

The completed liquid crystal panel is an SVGA specification ST.
It can be used as an N-type color liquid crystal.
By driving at a duty ratio of 00, a contrast ratio of 20: 1 was obtained. No electric leakage between the common electrodes due to the light-shielding layer was observed at all. In addition, a liquid crystal panel having a good appearance was produced without occurrence of defective orientation of the liquid crystal.

Example 2 A color filter was produced by changing the material of the light shielding layer material from Example 1. An organic pigment (the same material and the same mixing ratio as those in which the RGB layers were formed in Example 1) was mixed with a photosensitive acrylic resin at a weight ratio of 30% in the solid content, and diluted with ethyl cellosolve acetate to form a paint. What was done was used. When finally cured by heating, it showed a resistivity of 10 ¹⁰ Ωcm at a film thickness of 1.2 μm. The light transmittance was 10% (550 nm).

In the same manner, an STN type liquid crystal panel was prepared and evaluated. The contrast was slightly lower than that of Example 1 but 15: 1, but it was a level that was not problematic in practical use.

(Example 3) The materials and manufacturing steps used in Example 1 were basically the same except for the following.
Finally, a color filter for liquid crystal used for a reflective STN type liquid crystal color panel was manufactured.

On a glass substrate, a 0.3 μm thin film of chromium metal serving as a reflector was formed under a transparent electrode layer via a transparent silicon oxide insulating layer.

The light-shielding layer was formed with a thickness of 0.2 μm. The light transmittance is 10% (5%) when simply formed on glass.
50 nm).

Instead of the RGB layers, colored layers of three primary colors of yellow (Y), magenta (M) and cyan (C) were formed. The composition of the electrolyte used was as follows.

[0037]

[Table 3]

[0038]

[Table 4]

The thickness of each of the formed Y, M and C layers is 0.4 μm.
m. As described above, a reflection type color filter was produced.

Finally, a reflective liquid crystal panel was manufactured and evaluated. The liquid crystal panel is a STN type color liquid crystal of SVGA specification. A contrast ratio of 4: 1 is obtained by driving at a 1/300 duty ratio, and can be practically used depending on the application. . No electrical leakage between the common electrodes due to the light-shielding layer was observed at all. In addition, a liquid crystal panel having a good appearance was produced without occurrence of defective orientation of the liquid crystal.

(Comparative Example 1) A material in which the amount of added carbon fine particles was increased was used as the light shielding layer material in Example 1. When the film thickness was 1.2 μm, the light transmittance was 0.05% and the light-shielding property was improved, but the resistivity was 1 × 10 ⁷ Ωcm. As a result of producing and evaluating a liquid crystal panel, an electric leak between electrode lines occurred during driving of the liquid crystal.

(Comparative Example 2) The size of the area 13 for forming an alignment mark at the time of exposure is
15 mm, the size of the area 14 for forming the mark used when applying the alignment film in the panel making process is 15 mm in diameter,
The size of the area 15 for forming a mark necessary for assembling the panel was set to 50 × 20 mm. That is, the area of the exposed surface of the glass covered with the positive photoresist was increased.

As a result, when the substrate was put in an electrolytic solution for forming the first R layer, and the substrate was taken out after a predetermined time after the electrolysis, cracks were formed in the positive photoresist layer covering the exposed glass surface. Happen, 1 / of each area
Two-thirds were peeled from two. Further, as a result of the peeled-off positive photoresist floating in the electrolytic solution, about 10 small scratches were made on the formed R layer, resulting in a defective product at this stage.

[0044]

As described above, according to the present invention, required physical properties required for forming a light-shielding layer for a liquid crystal color filter which must be formed in direct contact with a liquid crystal driving electrode can be clarified. Has become easier. As a result, it has become extremely easy to provide a liquid crystal color filter particularly suitable for the STN type.

In addition, it has become possible to provide an effective method for preventing the removal of the photoresist used in the conventional selective formation of the R, G, and B layers by the electrolytic method.

[Brief description of the drawings]

FIG. 1 is a view for explaining a method for manufacturing a color filter of the present invention in an example.

FIG. 2 is a diagram for explaining a color filter and a method of manufacturing the color filter according to the present invention in an embodiment.

FIG. 3 is a diagram for explaining a conventional technique.

[Explanation of symbols]

11 A region finally used as a liquid crystal panel 12 A line electrode used for electrolysis and a common electrode 13 A region for forming an alignment mark at the time of exposure 14 A region for forming a mark used when applying an alignment film in a panel forming step 15 Area for Forming Marks Required for Assembling Panel 21 Light-Shielding Layer 22 Line Electrode Used for Electrolysis and Common Electrode 23 Glass Substrate 24 Positive Photoresist Layer 25 R Layer 26 G Layer 27 B Layer 31 Line Used for Electrolysis and Common Electrode Electrode 32 Positive photoresist layer 33 Glass substrate 34 Color filter layer

Claims (3)

[Claims] 1. A transparent electrode layer having a predetermined pattern is formed on a glass substrate, and a predetermined portion of the transparent electrode layer and a predetermined portion between the patterns have a resistivity of at least 10 ⁸ Ωcm comprising a resin and an organic pigment, and a thickness of at least 10 ⁸ Ωcm. Is from 0.2 to 1.2
μm, a light transmittance of 550 nm at a wavelength of 0.1 to 10 μm.
% Of the light-shielding layer pattern, the portion surrounded by the light-shielding layer pattern and the portion where the transparent electrode layer is exposed,
It is required that a color filter layer of RGB three primary colors or YMC three primary colors having a predetermined arrangement composed of at least an organic pigment and transparent conductive particles is formed, and that a transparent overcoat layer is formed on the light shielding layer and the color filter layer. Characteristic color filter for liquid crystal. 2. The color filter for a liquid crystal according to claim 1, wherein each of the R, G, and B layers is deposited by electrolysis. 3. A color filter for a liquid crystal, comprising: forming a transparent electrode layer on a glass substrate; etching the transparent electrode layer into a predetermined pattern; and selectively forming a color filter layer on the transparent electrode layer by an electrolytic method. In the manufacturing method, the transparent electrode layer is left as it is without etching at least except a region cut out for use as a liquid crystal panel, or when a portion not covered by the transparent electrode layer is provided outside the region, the transparent electrode The portion not covered by the layer has at least a short side of 10 mm or less or a diameter of 1
A method for producing a liquid crystal color filter, wherein the color filter has a shape of 0 mm or less.