JPH0224604A - Color filter - Google Patents

Abstract

PURPOSE:To lower the reflection factor of a light shielding layer and to obtain an excellent visual image which is reduced in total reflection by providing fine irregular parts on one surface of a transparent base body and providing light shielding layers thereupon. CONSTITUTION:The fine irregular parts are provided on one surface of the transparent base body 1 made of glass, etc., and the light shielding layers 3 are provided thereupon. Consequently, the reflected light i'2 of external light i2 is diffused. Further, a water-soluble photosensitive agent is applied on the light shielding layers 3, and then dried, patterned, and colored and a reverse printing treatment is carried out to form a color filter element 4. Similarly, color filters 4' and 4'' are formed. Consequently, the color filter is obtained.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a color filter suitable for use in a full-color liquid crystal device, and more particularly, it relates to a color filter that is suitable for use in a full-color liquid crystal device, and more specifically, a large number of fine color separation color filter elements and light shielding elements on a transparent substrate. This invention relates to a layered color filter.

<Prior Art> Several types of full-color liquid crystal display devices have been put into practical use. Figure 2 shows an example of an active matrix type using thin film transistor (TPT) elements. explain. Here, the panel (^) has a fine color filter element (4) for color separation on one side of a transparent substrate (1).

(4°), (4"), light shielding layer (3), transparent electrode (5)
, an alignment film (8) is formed, and an analyzer 0ω is provided on the back surface.

Panel (B) has a TPT element (6) on a transparent substrate (2).
, a transparent electrode (7) and an alignment film (8) are formed, a polarizer (9) is provided on the opposite side, and a liquid crystal 01) is sealed between the panel (A) and the panel (B).

Color filter element (4), transparent electrode (7) and TP
The T elements (6) form a pair to constitute a full-color liquid crystal pixel. By providing an opaque light-shielding layer (3) at the boundary between each color filter element, the boundaries of the image become clearer, and a visual effect can be expected. Further, in a liquid crystal display using TPT and having a structure as shown in FIG. 2, deterioration of TPT element characteristics due to external light can be prevented.

The light shielding layer (3) can be roughly classified into inorganic type and organic type.

Inorganic systems include metal chromium, chromium oxide, etc. alone or in combination of two or more on a glass substrate.

In organic systems, dichromate or the like is added to water-soluble colloids to make them photosensitized, patterned according to conventional methods, and then dyed with dyes, or silver halide is dispersed and reduced to produce silver. There is a method of precipitating and blackening. There are also methods in which carbon or the like is dispersed in a photosensitive resin, followed by exposure and development for patterning, and methods in which printing is performed with black ink.

<Problem to be solved by the invention> In the full-color liquid crystal display shown in Fig. 2, the light source (1
The light (i,) emitted from the transparent electric rod (7) and the liquid crystal (11
), passes through the color filter element (4) (++°)
and reaches the observer. During this time, the light (i,) emitted from the light source (+2+) changes according to the signal. The same thing can be said about the color filter elements (4'') and (4°'').

On the other hand, external light (12) reaches the observer through the light shielding layer (
3) may be reflected. In particular, when (i,') is weak (dark image), (i,') is relatively weak compared to (i,').
,') become brighter. As mentioned above, one of the roles of the light shielding layer is to clarify the boundaries between color filter elements, so it is desirable that the amount of reflected external light (i,') is small.

If a highly durable metal-based material is used as the material for the light-shielding layer (3), the Hz") value will become even higher, impairing the quality of the liquid crystal display. Therefore, at the same time, the reflectance of the light-shielding layer (3) will be lowered. By reducing total internal reflection, visible image quality can be improved.

Means for Solving the Problems As described above, the present invention provides a color filter that reduces the reflectance of a light-shielding layer and at the same time provides a good visual image with less total reflection. Explain.

First, fine irregularities are provided on one side of a transparent substrate (1) such as a glass plate, and a light shielding layer (3) is provided thereon. In such a structure, the reflected light (iz') of external light (one) is diffused, so the reflected external light that is visible to the observer is smaller than in the case shown in Figure 2, and the reflectance is reduced. Shading N (by the same material)
3) However, there is a large difference in visual effect between the case of Fig. 1 and the case of Fig. 2.

<Detailed Description of the Invention> The depth of the unevenness of the transparent substrate (1) of the color filter shown in FIG. 1 is 10 μm or less, preferably 3 μm or less. Techniques for processing the surface of a transparent substrate (1) such as a glass plate into irregularities include chemical etching methods and physical and mechanical processing methods. Alternatively, it can be formed by coating a granular transparent pigment on a flat glass plate.

In forming the light shielding layer N(3), a very common technique is to form a metal or metal oxide by a method such as sputtering and pattern it by chemical etching.

In addition, black patterns can also be produced by patterning a photosensitive resin and dyeing it with black dye, or by dispersing carbon black, organic black pigments, or opaque pigments in the photosensitive resin and exposing it to light using a mask. It is possible.

The fine color separation color filter element (4) is usually red,
They are blue and green, and can be formed using various methods. The unevenness of the transparent substrate is effective for scattering external light, but when viewed as a liquid crystal cell, the cell spacing is partially different, which deteriorates the purity of color.

Therefore, it is desirable that the surface of the color filter element (4) is sufficiently flat. To achieve this, the depth of the unevenness should be set to 3
μm or less, and after forming a light shielding layer (3) as shown in Figure 3,
After coating the undercoat layer side, a color filter element is formed, or a top coat layer θ is formed on the light shielding layer (3) and the color filter element (4) as shown in FIG.
It is desirable to provide a force.

<Example 1> As a transparent substrate (1), fine irregularities were formed on the surface of a thin plate glass by frosting. In the case of processing using a 1200 mesh abrasive material, the unevenness was 10 μm or less. Next, after thoroughly cleaning the uneven surface of the transparent substrate (), a chromium oxide film was formed by sputtering to a thickness of 1350 mm.

At this time, the transmission density was 2.8 and the reflectance was 31%. Next, the chromium oxide film was etched according to a conventional photolithography method to form a light shielding layer (3). Further, on the light-shielding layer (3), a water-soluble photosensitizer obtained by mixing and dissolving 10 parts by weight of gelatin with molecules of 1i10,000 and 72 parts by weight of ammonium dichromate in 500 parts by weight of pure water is coated and dried. The filter element (4) was patterned using a method, then colored red with an acid dye, and immersed in a tannic acid solution for resist dyeing treatment to form a color filter element (4). Thereafter, a green color filter element (4°) and a blue color filter element (4°) were formed in the same manner to produce the color filter shown in FIG. 1. Although the reflectance of the light-shielding layer (3) was 31%, since total reflection was low, it gave a visual appearance closer to black.

<Example 2> A chromium oxide film was similarly formed on the surface of the transparent substrate (1) used in Example 1 to form a light shielding layer (3). Next, go east■
0.5 parts by weight of N-methyl 2-pyrrolidinone (hereinafter referred to as NMP) was added to 1 part by weight of Semicofine 5P-910 manufactured by Manufacturer Co., Ltd., and a film thickness of 3 μm was formed by spinner coating.
The undercoat layer side shown in FIG. 3 was formed by holding the temperature from 100°C to 300'C in 50°C increments for 30 minutes each.

Next, 9.0 g and 0.9 g of pigment and dispersant were added to 1 g of Semicofine 5P-91090, respectively.
They were added and thoroughly mixed on a triple roll to make red, green, and blue varnishes. An example of the pigment is shown below.

For red filters: Liotogen Red GD (manufactured by Toyo Ink Manufacturing ■) For green filters: Lionol Green 2YS (manufactured by Toyo Ink Manufacturing ■) For blue filters: Lionol ES (manufactured by Toyo Ink Manufacturing ■) Next, for 10 g of red varnish 5g of NMP was added, thoroughly stirred, and applied by spinner at 1250rpm for 60 seconds onto the glass plate on which the undercoat layer 0ω was formed, and heated at 60°C for 15 minutes and then at 130°C3.
Heat for 0 minutes and place Japanese synthetic rubber on the red filter layer.
JSI? -CBl? -M901″ negative resist 20
After spin-coding at 00 rpm and pre-beta at 80°C for 30 minutes, pattern exposure was performed and development was performed using a special developer.

Next, after boiling at 125°C for 30 minutes, Microposit developer MP-312 (Sibley Far East ■)
The openings of the red coating were removed by etching with an alkaline solution diluted 1:1 with pure water. Then 250 ml in a nitrogen stream
A color filter element (4) was formed by heating at °C for 60 minutes.

Thereafter, a color filter element (4') and a color filter element (4'') were sequentially formed using the green varnish and blue varnish described above in the same steps to produce the color filter shown in FIG. 3.

<Example 3> C3G-L-0800 manufactured by Chinso Co., Ltd. was coated with a spinner onto a soda-lime glass plate that had been frosted using hydronic acid on a glass plate, and then baked at 450°C for 60 minutes. A thin chromium film with a thickness of 1000 mm was formed on this glass by sputtering metallic chromium.

Next, according to the usual method for photo applications, a light-shielding layer (
3) was formed. The transmittance of this film was 0.2% or less, and the reflectance was about 50%. Next, in the same manner as in Example 1, a fourth
Color filter elements (4) (4') (4") shown in the figure
) were formed respectively. Next, 75 g of Sumidur N-75 (manufactured by Sumitomo Bayer Urethane ■) was mixed with 1200.100 g of Dismohen (manufactured by Sumitomo Bayer Urethane ■), and 30 m and 10 m of cellosolve acetate and butyl acetate were added, respectively.
The coating was spin-coated with pn1 and cured by heating at 150° C. for 90 minutes to form an overcoat layer (+71) to produce a color filter as shown in FIG. 4.

<Example 4> The frosted glass used in Example 1 was coated with a black varnish having the following composition and patterned.

(1) Semico Fine 5P-710 Toshi ■ Film forming 6.1 parts (2) Carbon black 4.5 parts (3) Titanium white 1.3 parts (4) Lionol ES (manufactured by Toyo Ink Manufacturing ■) 3.5 Part (5) Lyotogen Red CD (manufactured by Toyo Ink Manufacturing ■) 3.2 parts (6) Dispersion aid 1.4 parts or more (1
The compositions of ) to (6) were thoroughly mixed and dispersed using three rolls to obtain a black varnish.

Next, 1 part of the black varnish was mixed with 1 part of NMPI and 1 part of dimethylformamide, and an appropriate amount of the mixture was dropped onto the glass substrate, and the mixture was heated to 100 Or p mi using a spinner.

Spin coating for seconds and drying at 150'C.

Next, Microposite 1400-25 (Spree
(manufactured by Far East ■) was spin-coded at 150 Orpm for 15 seconds. After soft baking at 90° C. for 30 minutes, pattern exposure was carried out, and development was performed using a developer prepared by diluting MF312 with pure water at a ratio of 1:1 to form a black pattern at the same time.

Next, use Microposit 140 with n-butyl acetate solution.
0-25 was peeled off and heated at 280°C for 60 minutes. A black pattern was formed through the above steps. Thereafter, a color filter consisting of R, G, and B was manufactured in the same manner as in Example 2.

<Effects of the Invention> The color filter according to the present invention has excellent durability, and even when using metals and metal oxide films with high transmission density, the reflection of external light is averaged and the light-shielding layer becomes closer to black. . Therefore, when used in a liquid crystal display device, the clarity of the image was improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view of one embodiment of the color filter of the present invention. FIG. 2 is an explanatory diagram of a liquid crystal display using a conventional color filter. 3 and 4 are cross-sectional explanatory views showing other embodiments of the color filter of the present invention. 1.2... Transparent substrate 3... Light shielding layer 4.4.
4”...Color filter element 6...TPT element 5.7...Transparent electrode 9...Polarizer 11...Liquid crystal 13...Undercoat layer 8...Alignment film 10... Analyzer 12...Light source 14...Overcoat layer

Claims (1)

[Scope of Claims] 1) A color filter characterized in that a large number of color separation color filter elements and a light shielding layer are provided on a transparent substrate having fine irregularities on one surface. 2) The color filter according to claim 1, wherein the light shielding layer is a thin film of metal or metal oxide. 3) The color filter according to claim 1, wherein the light shielding layer is a film in which a dye or a pigment is dispersed in a resin. 4) The color filter according to claim 1, characterized in that a transparent resin layer is provided between the transparent substrate and the color separation color filter element to make the uneven surface flat. 5) The color filter according to claim 1, wherein a transparent resin layer is provided on the surface of the color separation color filter element and the light shielding layer to flatten the surface.