JPH10123312A - Color filter, color liquid crystal display device, and production of those - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve both of brightness and color purity of a color filter by forming a transparent colorless part in a size which can not be visually recognized in each transparent color pixel patterned into plural colors on a transparent substrate. SOLUTION: A positive photosensitive resin layer 3 is formed on a conductive layer 2 (B). Then a mask 4 having a specified pattern is mounted thereon (C) to obtain a patterned substrate (D). The conductive layer 2 is energized to form black pixels 8 by electrodeposition in an electrodeposition bath (E). A positive mask having a light transmitting part corresponding to a color image while a light-shielding part 10 corresponding to a transparent colorless part remains is mounted on the black pixels and the positive photosensitive resin layer on the substrate 1 to obtain a patterned substrate (G). Further, first color pixels red(R) are formed by electrodeposition (H). These processes (F) to (H) are repeated (I) to (K) to form second color pixels green(G) 6. At least, a transparent colorless part 9 is formed (P), (Q).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter, and more particularly, to a color filter mounted on a color liquid crystal display, a color facsimile, a three-tube and single-tube color video camera, a solid color video camera, and the like. The present invention relates to mounting of a liquid crystal display using a color filter and a method of manufacturing the same.

[0002]

2. Description of the Related Art In general, a color liquid crystal display device displays a color image by forming a color filter on a substrate such as glass and forming electrodes thereon. As described above, a color filter used in a color liquid crystal display device or the like is formed by providing extremely fine regions colored with three or more hues having different hues on a substrate.

As a pattern composed of fine regions of each hue, a so-called striped stripe pattern or a mosaic pattern in which regions of different hues are adjacent to each other are known. It is known that a pattern provides a visually superior effect. In these patterns, when colored pixels are directly adjacent to each other, it is difficult to obtain color contrast.
It is preferable that a black pixel is formed between the color pixels.

[0004] Such a color filter is formed by a method such as a pigment dispersion method, an electrodeposition method, and a printing method. However, the color filters obtained by any of the methods have not yet satisfied both the brightness and the color purity of the image. That is, if the color purity is to be increased, the brightness becomes insufficient, and if the brightness is prioritized, the color purity has to be sacrificed to some extent.

On the other hand, liquid crystal display devices include a transmission type in which a light source is provided as a backlight on the back of a liquid crystal cell and a reflection type in which an external light source is used to observe reflected light from the liquid crystal cell. In the transmission type, the image is bright to some extent,
In addition, high color purity can be obtained. However, in the case of the transmission type, it is necessary to incorporate a power source and a light source lamp for a light source, and it is difficult to reduce the size, thickness, and weight, and thus it is not suitable for portable use. For this reason, the reflection type has recently attracted attention as a method suitable for portable use and as a method capable of reducing the thickness.

However, since the reflection type liquid crystal display device does not have a built-in light source, it has a drawback that the screen is dark and difficult to see in a dark place such as a room. This problem is even more pronounced when the width of the black pixel is wide. The screen can be made brighter by reducing the color purity of the image, but this naturally lowers the color purity.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color filter capable of displaying a color image having sufficient brightness and color purity.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a transparent non-colored portion having a size substantially invisible to the naked eye, in each of the transparent colored pixels formed on a transparent substrate and patterned in a plurality of colors. To improve the brightness and color purity of a color filter at the same time. More specifically, the present invention
Colored pixels provided on the transparent substrate in a pattern of a plurality of colors are composed of a transparent colored pixel and a black pixel, and the transparent colored pixel has a light transmission region having a light transmittance of 50% or more in a visible region. A transparent colored portion having a spectral characteristic curve having a light transmittance of 20% or less in a light absorbing region and a transparent uncolored portion having a light transmittance of 40% or more over the entire visible region. A color filter having a light transmittance of 5% or less over the entire region.

The present invention also provides a photosensitive film formed on a surface of a transparent conductive layer provided on a transparent substrate, wherein the photosensitive film has a light transmitting region having a light transmittance of 50% or more in a visible region. And a transparent colored portion having a spectral characteristic curve having a light transmittance of 20% or less in a light absorbing region and a transparent uncolored portion having a light transmittance of 40% or more over the entire visible region. After placing the mask, it is exposed and developed to expose a part of the transparent conductive layer, and then a transparent colored portion is formed by an electrodeposition coating method, and a required number of photolithography and electrodeposition coating methods are performed. The present invention relates to a method for producing the above color filter, which comprises repeatedly exposing and finally exposing the remaining portion of the photosensitive film and performing electrodeposition coating to form a transparent and non-colored portion.

Further, the present invention is a color liquid crystal display device in which liquid crystal is sealed between at least a pair of electrode substrates, wherein at least one of the electrode substrates has a plurality of transparent colored portions having different hues on a transparent substrate. A color filter formed of a transparent colored pixel comprising an uncolored portion and a black pixel having a light transmittance of 5% or less over the entire visible region;
At least one of the transparent colored pixels includes a transparent colored portion having a light transmission region having a light transmittance of 50% or more in a visible region and a spectral characteristic curve having a light transmittance of 20% or less in a light absorption region; 40% light transmittance over the entire visible region
The present invention relates to a color liquid crystal display device comprising the transparent and non-colored portions described above.

Further, the present invention is a color liquid crystal display device in which liquid crystal is sealed between at least a pair of electrode substrates, wherein at least one of the electrode substrates has a plurality of transparent colored layers having different hues on a transparent substrate. In the manufacture of a color liquid crystal display device having a color filter formed of a transparent colored pixel comprising a portion and a transparent uncolored portion and a black pixel, a black pixel having a light transmittance of 5% or less over the entire visible region is formed. Next, a transparent colored portion having a light transmission region having a light transmittance of 50% or more in a visible region and a spectral characteristic curve having a light transmittance of 20% or less in a light absorption region, and a light transmittance over the entire visible region. Is formed in accordance with the first pattern, and the second color is different from the first hue.
And the third hue are similarly repeated to obtain the second and third hues.
Forming a transparent colored pixel in a pattern, and then forming a transparent conductive film on the black pixel and the first to third patterned pixels.

That is, the color filter of the present invention disperses or divides a fine transparent uncolored portion, that is, a transparent region having a light transmittance of 40% or more over the entire visible region, in a transparent colored pixel having a plurality of color patterns. This transparent non-colored portion makes it possible to increase the brightness of the transparent colored pixel. Moreover, the color purity can be increased by increasing the color density of the transparent colored portion. Thus, a color filter having both sufficient brightness and color purity was obtained.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The color filter of the present invention is composed of transparent colored pixels and black pixels provided in a pattern of a plurality of colors, and each transparent colored pixel has a substantially invisible size. A transparent non-colored portion is provided.

In the present invention, the transparent non-colored portion refers to a highly transparent region having a light transmittance of 40% or more over the entire visible region. That is, the transparent colored pixel of the color filter of the present invention has a light transmission region with a light transmittance of 50% or more in the visible region and a spectral characteristic curve with a light transmittance of 20% or less in the light absorption region. It comprises a transparent colored portion and a transparent uncolored portion having a light transmittance of 40% or more over the entire visible region.

The transparent non-colored portion is provided in a finely dispersed or divided state in the transparent colored pixels patterned into a plurality of colors, and functions to increase the light transmittance of the entire transparent colored pixel. The area ratio of the transparent uncolored portion in one transparent colored pixel is 30% or less, preferably 25% or less, more preferably 20% or less. The size of each transparent uncolored portion dispersed and present is 20 μm or less at the maximum.

The transparent non-colored portion is preferably formed by forming a transparent film by electrodeposition on the exposed electrode substrate. Other means such as dispersing transparent particles in the transparent colored film forming the transparent colored pixels is preferable. May be introduced.

The transparent colored pixels patterned into a plurality of colors are:
A photosensitive resin layer is formed on a transparent conductive layer formed on a substrate such as glass, and a mask patterned for each color is placed on this layer. The conductive layer is exposed, and a colored pixel can be formed on the exposed transparent conductive layer by electrodeposition coating. Although the number of colors of the transparent colored pixels is not particularly limited, it is preferable to use three primary colors of blue, green, and red.

Although a black pixel is not always necessary, by providing it at a boundary between pixels of other colors, color contrast can be improved. For the present invention, it is preferable to provide a black pixel. The black pixel has a light transmittance of 5% or less over the entire visible region.

The size of one colored pixel other than black is 50
To 300 μm, preferably 60 to 150 μm, more preferably 70 to 90 μm, and the width of the black pixel is 5 to 70 μm.
μm, preferably 10 to 50 μm, more preferably 15 μm
３０30 μm.

In each transparent colored pixel, the transparent colored image portion has a light transmittance of 50% or more in a light transmitting region corresponding to the color in a spectral characteristic curve of a visible region, and a light transmittance of a light absorbing region. Is formed to be 20% or less. For example, FIG. 2 shows a spectral characteristic curve of a green pixel. The light transmission region has a peak at 540 μm, and a light absorption region having a light transmittance of 20% or less exists on the long wavelength side and the short wavelength side. I do. The thickness may be determined depending on the balance between the required color purity and brightness, and is usually 0.2 to 5.0 μm,
Preferably from 0.5 to 3.0 μm, more preferably from 1.7 to 3.0 μm.
2.0 μm.

The color filter of the present invention in which a transparent uncolored portion is provided in a transparent colored pixel is manufactured by any of the conventional manufacturing methods such as a pigment dispersion method, an electrodeposition method, and a printing method. Is also good. However, it is preferable to manufacture the positive photosensitive resin layer by forming the positive photosensitive resin layer on the transparent conductive layer formed on the substrate by a resist electrodeposition method. When the resist electrodeposition method is used, the thickness of the color filter can be controlled with high accuracy by controlling only the applied voltage and the applied time during the electrodeposition. Therefore, the surface flatness of the color filter is also good even when it is composed of pixels of a plurality of colors. Further, since the dimensional accuracy of the pixels is high, the color contrast is also good.

Hereinafter, a method for manufacturing a color filter and a color liquid crystal display device of the present invention will be described in detail with reference to FIG. First, FIG.
A transparent conductive layer is formed on a substrate 1 as shown in FIG. Substrate 1
May be any substrate usually used in a multicolor display device, such as a glass substrate or a plastic substrate. For the transparent conductive layer, for example, a material containing tin oxide, indium oxide, antimony oxide, or the like as a main component is preferably used. This transparent conductive layer is formed by a method such as evaporation or sputtering.

Next, as shown in FIG. 1B, a positive photosensitive resin layer 3 is formed on the conductive layer 2. This positive photosensitive resin can be exposed and developed a plurality of times with the photosensitive resin layer applied once, and is not resistant to an acid composed of tert-butyl ester of carboxylic acid or tert-butyl carbonate of phenol. Positive photosensitive resin compositions containing a polymer having a stable branched group and a photopolymerization initiator which generates an acid upon exposure (for example, see JP-B-2-27660 and JP-A-2-309358). Disclosed)
Is preferred.

A mask 4 having a predetermined pattern is placed on the positive photosensitive resin composition 3 (FIG. 1C), and the photosensitive resin composition layer at the exposed portion can be eluted by exposure. Then, a patterned substrate is obtained by elution with a predetermined eluent (FIG. 1 (D)). Mask and elution techniques are known. As shown in FIG. 1 (D), the substrate has a shape in which the conductive layer 2 is exposed at a portion requiring coloring. As shown in FIG. 1E, the conductive layer 2 is energized, and a black pixel 8 is formed by electrodeposition in an electrodeposition bath.

The synthetic polymer resin used as a film-forming component of the electrodeposition bath used in this method may be cationic, anionic or amphoteric, and various conventionally known ones such as acrylic resin and epoxy resin Resin, urethane resin, polybutadiene resin, polyamide resin, carboxyl group-introduced polybutadiene, carboxyl group-introduced alkyd resin, and the like. It should be noted that, depending on the ionicity of the synthetic polymer resin, some may affect the conductive layer 2, and it is necessary to select a film-forming component in consideration of this point. The details of the electrodeposition bath and others are described in JP-A-59-114592 and Japanese Patent Application No. 62-46321 by the present inventors (JP-A-63-210).
No. 901). This electrodeposition paint may be either photocurable or thermosetting.

Next, as shown in FIG. 1F, a colored image in which a light shielding portion (10) corresponding to a transparent non-colored portion is left in the black pixel and the positive photosensitive resin layer formed on the substrate 1. A positive mask 4 'having a light transmitting portion corresponding to the above is placed (see FIG. 1).
(F)) Exposure exposes the photosensitive resin composition layer at the exposed portion in the same manner as described above to obtain a patterned substrate (FIG. 1 (G)).

Further, as shown in FIG. 1H, a first colored image (for example, red (R)) 5 is formed by applying electricity to the conductive layer 2 and performing electrodeposition in an electrodeposition bath. Next, a second colored pixel (for example, green (G)) 6 is formed by repeating FIGS. 1 (F) to 1 (H) (FIGS. 1 (I) to 1 (K)).

Similarly, a third colored pixel (for example, blue
(B)) 7 is formed (FIGS. 1 (L) to 1 (N)).

Finally, the entire surface of the substrate on which the positive photosensitive resin layer is left is exposed, and the substrate is further eluted to expose the conductive layer 2 (FIG. 1 (P)), as shown in FIG. 1 (Q). Electric current is applied to the conductive layer 2 to form a transparent uncolored portion 9 by electrodeposition in an electrodeposition bath composed of a transparent film-forming component.

[0030]

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to the following examples. Example 1 A transparent conductive film IT was formed on a glass substrate in the same manner as in the prior art.
An O (indium tin oxide) compound was formed. On this transparent conductive film, a positive-type photosensitive resin composition “EXERID PR-
146 "(manufactured by Nippon Paint Co., Ltd.) with a spinner at 3.0μ
m, and dried to form a positive photosensitive resin composition layer on the transparent conductive film. Next, exposure was performed with a high-pressure mercury lamp through a 25 μm lattice-like photomask for a black matrix, and further heating was performed at 100 ° C. for 3 minutes, and when this was developed with an alkaline aqueous solution, the exposed portions formed salts and eluted, The surface of the transparent conductive layer was exposed. Next, the substrate with the transparent conductive layer exposed was immersed in an electrodeposition bath of a black anionic electrodeposition resin composition, and a DC voltage of 30 volts was applied for 10 seconds using the transparent conductive film as a positive electrode. Thereafter, the substrate was pulled up and sufficiently washed with water. At this time, the electrodeposited resin composition does not adhere to the positive photosensitive resin composition on the transparent conductive film and is washed away with water, but the polymer adhered to the electrode to which the voltage is applied is water. It is insoluble in water, so it is not washed off with water. After washing with water and drying, a black polymer film having good light-shielding properties was formed on the transparent electrode.

Next, a width of 70 μm and a length of 210 μm
Among the colored pixels, the ratio of the total area of the transmission image to the area of the colored pixels is 30/70 and the diameter is 5 μm so that holes are formed.
A photomask designed with a large number of transparent uncolored parts is placed, exposed with a high-pressure mercury lamp in the same manner as described above, further heated at 100 ° C. for 3 minutes, and further developed with an alkaline aqueous solution. The surface of the conductive film was exposed. Next, the substrate on which the black layer with the transparent conductive film exposed was formed was immersed in an electrodeposition bath of a green anion-type electrodeposition resin composition, and a DC voltage of 35 V was applied for 15 seconds using the transparent conductive film as a positive electrode. After the application, the substrate was pulled up and washed sufficiently with water. After washing with water
When dried, a green polymer film with high color purity and good transparency was formed.

By repeating the same steps for red and blue in the same manner, red and blue polymer films were similarly formed. Finally, the entire surface of the substrate on which the remaining positive-type photosensitive resin composition and the black, green, red, and blue coloring layers are formed is exposed to a high-pressure mercury lamp and developed with an alkaline aqueous solution to leave the positive-type coloring layer. The surface of the transparent conductive film was exposed by eluting the photosensitive resin composition. Next, the transparent film was electrodeposited in the same manner. The thickness of each of the colored film and the transparent uncolored film was 3 μm.

The pixel of the green part of this color filter is
As shown by the curve a in FIG. 2, the light transmittance at 500 to 600 nm was 80% or more. The Y value at this time is 58
It became. These measured values were greatly improved in both color purity and brightness than characteristic values of the conventional color filter. Here, the Y value is a value that determines the brightness (or luminance ratio) of a color defined in "Measure Color" (by Toshio Hirai, edited by the Japan Standards Association).

Example 2 On a color filter obtained in the same manner as in Example 1, a transparent conductive film was provided in a thickness of 90 nm by a low-temperature sputtering method, and then polyimide was applied thereon to form a film in a thickness of 100 nm. Thereafter, a rubbing treatment was performed, and the resultant was combined with a thin film transistor serving as a counter electrode. Next, liquid crystal was injected between the electrodes to assemble the liquid crystal cell, and a color liquid crystal display device including a color filter having the above-described image inside the liquid crystal cell was obtained.

Comparative Example 1 A color filter was formed in the same manner as in Example 1 except that the structure of a conventional color filter without a transparent clear film of the color filter was used, and the light transmittance was measured.
This is shown by curve b in the figure. The Y value at this time was 40. It can be seen from the curve b and the Y value in the figure that unless a transparent clear film is provided in the colored pixel, it is difficult to achieve both color purity and brightness, and a colored pixel having sufficient performance cannot be obtained.

[0036]

The color filter of the present invention has improved characteristics in both color purity and brightness as compared with the conventional one. Further, the thickness of the color filter was uniform and excellent in surface flatness, and together with the above characteristics, the color filter was suitable as a color filter for a reflective color liquid crystal display device.

[Brief description of the drawings]

FIG. 1 is a process drawing showing a manufacturing method of the present invention, and shows a cross-sectional view.

FIG. 2 is a spectral characteristic curve of a transparent colored pixel.

[Explanation of symbols]

1: glass substrate, 2: transparent conductive film, 3: positive photosensitive resin layer, 4: photomask, 5: colored portion of transparent colored pixel (red), 6: colored portion of transparent colored pixel (green), 7 : Colored portion (blue) of transparent colored pixel, 8: black pixel, 9: transparent uncolored portion,
10: Shielding part of photomask corresponding to transparent uncolored part a: Spectral characteristic curve of pixel having transparent colored image and transparent uncolored part, b: Spectral characteristic curve of colored pixel not having transparent uncolored part.

Claims (7)

[Claims] 1. The brightness and color of a color filter is provided by providing a transparent non-colored portion having a size substantially invisible to each other in each of the transparent colored pixels which are patterned into a plurality of colors provided on a transparent substrate. A method that simultaneously improves purity. 2. A colored pixel provided on a transparent substrate in a pattern of a plurality of colors includes a transparent colored pixel and a black pixel, and the transparent colored pixel has a light transmittance of 50% in a visible region.
A transparent colored portion having a light transmission region as described above and having a spectral characteristic curve in which the light transmittance of the light absorbing region is 20% or less, and a transparent uncolored portion having a light transmittance of 40% or more over the entire visible region. Wherein the black pixel has a light transmittance of 5% or less over the entire visible region. 3. The area ratio of the transparent non-colored portion to the total image area of the transparent non-colored portion and the transparent colored portion in one transparent colored pixel is 30% or less, and the size of each transparent non-colored portion is less than 30%. 3. The color filter according to claim 2, wherein the maximum size is 20 μm or less. 4. A photosensitive film is formed on the surface of a transparent conductive layer provided on a transparent substrate, and the photosensitive film has a light transmitting region having a light transmittance of 50% or more in a visible region and absorbs light. A transparent colored portion having a spectral characteristic curve in which the light transmittance of the region is 20% or less, and a light transmittance of 40% over the entire visible region.
After placing a mask patterned so as to form a transparent uncolored portion as described above, this is exposed and developed to expose a part of the transparent conductive layer, and then the transparent colored portion is formed by an electrodeposition coating method. Forming, repeating the required number of photolithography method and electrodeposition coating method, finally exposing and exposing the remaining of the photosensitive film and electrodeposition coating to form a transparent non-colored portion, Claims: The method for producing a color filter according to any one of claims 1 to 3. 5. A mask in which a photosensitive film is formed on a surface of a transparent conductive layer provided on a transparent substrate, and a black pixel having a light transmittance of 5% or less over the entire visible region is patterned on the photosensitive film. After mounting, this is exposed and developed to expose a part of the transparent conductive layer, and then a black pixel is formed by an electrodeposition coating method. Subsequently, the light transmittance of the photosensitive film in the visible region is 50% or more. A transparent colored portion having a light transmission region having a light transmittance of 20% or less and a light transmission region having a spectral characteristic curve of 20% or less, and a transparent uncolored portion having a light transmittance of 40% or more over the entire visible region. After placing a patterned mask to be formed, it is exposed and developed to expose a part of the transparent conductive layer, and then a transparent colored portion is formed by an electrodeposition coating method, and a required number of photolithography processes are performed. And electrodeposition coating method 4. The method for producing a color filter according to any one of claims 1 to 3, wherein the remaining portion of the photosensitive film is exposed and exposed and electrodeposited to form a transparent uncolored portion. 6. A color liquid crystal display device in which liquid crystal is sealed between at least a pair of electrode substrates, wherein at least one of the electrode substrates has a plurality of transparent colored portions having different hues and a transparent uncolored portion on a transparent substrate. And a color filter formed of black pixels having a light transmittance of 5% or less over the entire visible region, wherein at least one of the transparent colored pixels has a light transmittance of 50% in the visible region. A transparent colored portion having a light transmission region as described above and having a spectral characteristic curve in which the light transmittance of the light absorbing region is 20% or less, and a transparent uncolored portion having a light transmittance of 40% or more over the entire visible region. A color liquid crystal display device comprising: 7. A color liquid crystal display device in which liquid crystal is sealed between at least a pair of electrode substrates, wherein at least one of the electrode substrates has a plurality of transparent colored portions having different hues on a transparent substrate and a transparent non-colored portion. In the manufacture of a color liquid crystal display device having a color filter formed of transparent colored pixels and black pixels, a black pixel having a light transmittance of 5% or less over the entire visible region is formed, and then the light is transmitted to the visible region. A transparent colored portion having a light transmission region having a transmittance of 50% or more and a spectral characteristic curve having a light transmittance of a light absorption region of 20% or less, and having a light transmittance of 40% or more over the entire visible region. A transparent colored pixel of a first hue composed of a certain transparent uncolored portion is formed according to a first pattern, and a second hue and a third hue different from the first hue are similarly repeated. After forming the second and third transparent colored pixels in a pattern, the black pixel and the first to third pixels are formed.
Forming a transparent conductive film on the pattern-shaped pixels.