JPH06281806A - Forming method for color filter - Google Patents

Abstract

PURPOSE:To constitute the color filter of a mosaic-like pattern, for instance, the color filter of a delta array by using an electrodeposition coating method. CONSTITUTION:A photosensitive coating film 2 is formed on the surface of an electrode 1 formed almost extensively on at least one surface of a substrate 5, the photosensitive coating film 2 is peeled off to a prescribed pattern by a photolithography method and an electrode exposed part 4 is formed, a coating film 3' of a prescribed hue is formed on the electrode exposed part 4 by an electrodeposition coating method, the photosensitive coating film 2 in an area being adjacent to an area in which the coating film 3' is formed, is peeled off to a prescribed pattern by a photolithography method and the electrode exposed part 4 is formed and on the electrode exposed part 4, a coating film whose hue is different from the above-mentioned hue is formed by a electrodeposition coating method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter forming method, and more particularly to a color filter forming method suitable for forming a mosaic color filter.

[0002]

2. Description of the Related Art Conventionally, in a liquid crystal display device or the like, a color filter is formed on an electrode surface to display a color image. For example, as shown in an exploded perspective view in FIG. 5, indium tin oxide (ITO) or the like is fixed in parallel on the lower glass substrate 5 by a method such as vapor deposition to form the Y electrode 6. Similarly, the X electrode 9 is formed on the upper glass substrate 8. Next, the Y electrode 6 of the lower glass substrate 5
Apply a color filter to the surface of the X electrode 9 and the Y electrode 6
The electrode surfaces of the glass substrates 8 and 5 are made to face each other with a predetermined interval so that and are orthogonal to each other, and the peripheral portion is sealed with a sealing material (not shown) to form a liquid crystal display cell. A liquid crystal material (not shown) is injected into this cell, and when the liquid crystal material is a twisted nematic (TN) type, the polarizing plate 11 has a polarization direction substantially parallel to the outside of the two glass substrates 5 and 8. They are provided so as to be substantially orthogonal to each other to form a display device.

In this case, if a color filter is formed on the surface of the Y electrode 6, a phenomenon (hereinafter, referred to as "parallax") in which the display color is shifted from that of the working electrode due to the difference in the angle at which the viewer looks at the display device is prevented. Therefore, in a color display device such as the liquid crystal display device or the electrochromic display device described above, a color filter is formed on the electrode surface.

A printing method, a photolithography method, an electrodeposition coating method and the like have been studied as a method for forming a color filter on the electrode surface. For example, the above-mentioned liquid crystal display device for displaying a color image by matrix electrodes. In order to obtain a high-density image, the color filter is required to have a fine pattern with a width of, for example, about 100 μm, and a pattern accuracy such that the relative position with the Y electrode 6 is displaced within about 10 μm. It In such a case, of the above-described color filter forming methods, the electrodeposition coating method is superior to the other methods because a color filter that almost completely matches the Y electrode 6 can be obtained.

On the other hand, as the pattern of the color filter, a so-called striped pattern having a stripe shape or a mosaic pattern in which regions of different hues are adjacent to each other is known, but under certain conditions (for example, from a relatively close distance). It is known that the mosaic pattern has a better visual effect when the display screen is observed).

Furthermore, in order to improve the resolution in the diagonal direction, it is necessary to arrange the mosaic color filters by shifting the row pitch or the column by a half pitch and the matrix pitch (hereinafter, such an array is referred to as a delta array). It is also known to be effective.

[0007]

As described above, in the case of a display device or the like which is desired to obtain a high density image quality, it is required to form a color filter having a mosaic pattern on a fine electrode. It However, in the conventional electrodeposition coating method, even if an attempt is made to form a multicolored color filter, for example, only a color filter having the same hue can be formed on a rod-shaped electrode as shown in FIG. It was impossible to form. Therefore, it has been considered impossible to provide color filters of different hues on the electrodes entirely formed on the surface of the substrate.

The present invention solves the above-mentioned drawbacks of the conventional color filter forming method, and uses an electrode coating method to form a mosaic pattern color filter, and further, an array pattern such as a color filter having a delta array. The objective is to form a color filter having a high degree of freedom in a relatively simple process.

[0009]

In order to achieve the above-mentioned object, the present invention is to form a color filter by combining a photolithography process and an electrodeposition coating process. That is, the method for forming a color filter of the present invention is the method for forming a color filter on an electrode surface, in which a photosensitive coating is formed on at least one surface of the substrate, and the electrode surface is formed almost entirely. First step of forming and peeling the photosensitive film into a predetermined pattern by photolithography to expose the electrode surface, and forming a coating film of a predetermined hue on the exposed electrode surface by an electrodeposition coating method A second step of
The third step of exposing the electrode surface by peeling off the photosensitive film in the area adjacent to the area where the coating film is formed on the electrode surface by a photolithography method, and exposing the electrode surface And a fourth step of forming a coating film of a hue different from the hue on the surface of the electrode by an electrodeposition coating method. It is characterized in that the coating is applied substantially only once in forming the coating films of the plurality of hues.

Hereinafter, each step of the method for forming a color filter of the present invention will be described by using a typical example.

1 to 3 are plan views showing steps of forming a mosaic color filter on an electrode formed on substantially the entire surface of a substrate by the method for forming a color filter of the present invention.

First, I is deposited on the glass substrate 5 by a vapor deposition method or the like.
The electrode 1 made of TO or the like is formed on almost the entire surface of the glass substrate 5 on one surface. The electrode 1 is not limited to the electrode as in this example, and may be an opaque metal electrode or the like.

Next, as shown in FIG. 2, a photoresist is applied to a desired portion of the electrode 1 to form a photosensitive film 2. Visible rays, ultraviolet rays, far-infrared rays, or the like is irradiated onto a predetermined portion of the photosensitive coating 2 through a predetermined photomask, and the irradiated or non-irradiated portion of the photosensitive coating 2 is peeled from the electrode 1 with a developing solution. To expose the electrode surface of the portion (so-called photolithography method).

The photoresist used in this step may be a commonly used photoresist, but it is necessary that it is a photoresist that is peeled off in the subsequent electrodeposition step. Although it may be a negative type or a positive type, in this example, since the electrode exposed portions 3 are scattered, the positive type which can be used by exposing the photoresist once applied several times without changing the developing conditions is preferable. Easy to use.

The developing solution for the photosensitive film 2 may be an organic alkaline developing solution or the like which is usually used for the photoresist.

As described above, the color filter of the first color is formed by the electrodeposition coating method on the surface of the electrode 1 which is exposed by peeling the photosensitive film 2 in a predetermined pattern.

In the electrodeposition coating method, an electrode (the solution tank itself may be used as an electrode) is provided in a coating solution, and a voltage is applied between both electrodes by using the electrodeposited object as an electrode of opposite polarity, and the electrodeposited object is applied. In addition, the resin, pigment, etc. in the paint are discharged and deposited.
After that, when the deposit on the electrodeposit is fired, the deposit spreads on the deposit to form a uniform coating surface.

The paint is a kind of colloidal dispersion in which a pigment and resin particles are dispersed in a solvent such as water, and an anion type paint using a salt in which an anion such as a carboxyl group is neutralized with an amine or ammonia as the resin particle. And a cation-type paint that uses a salt obtained by neutralizing a cation such as an amino group with an organic acid such as acetic acid.

However, as in this example, an oxide (for example, IT
When a coating material is formed on the electrode 1) of (O), the electrode 1 is used as a cathode when a cationic coating material is used, so that the electrode 1 is reduced when energized, and the electrode 1 is May dissolve in the coating solution. Further, when it is used as an electrode of an electrode display device or the like, the electrode is required to have high transparency, but the reduction reaction described above may reduce the transparency of the electrode, making it unusable. Therefore, when forming a coating film on an oxide electrode, the above-mentioned anionic coating material is desirable. Since the coating film thus formed on the electrode 1 becomes an electrically poor conductor, even if the electrode 1 is immersed in a coating solution of another hue and electrodeposition coating of another hue is performed. A new coating film is not formed on the coating film formed in the previous step.

Next, as shown in FIG. 3, the photosensitive coating film 2 in the area adjacent to the coating film forming portion 3'formed in the previous step is peeled into a predetermined pattern by the above-mentioned photolithography method to expose the electrode exposed portion 4. To form.

The glass substrate 5 having the exposed electrode portion is immersed in an electrodeposition tank filled with a paint having a hue different from the hue of the coating film formed on the coating film forming portion 3 ', and the electrode 1 is energized to A coating film of the hue is formed on the exposed electrode portion 4 by a coating method. The coating film is baked and spread to give a uniform coating film. Finally, the remaining photoresist is removed to obtain a mosaic color filter.

In this example, since the hues of the three primary colors are planned as the hues of the coating films, the patterns shown in FIGS. 2 and 3 are formed on the surface of the electrode 1 only by the steps described above. However, the method of forming the color filter of the present invention is not limited to the pattern of the three primary colors as in this example, and coating films of two different hues are formed on the same electrode. Alternatively, a mosaic-shaped color filter may be used. In this case, the pattern of the photomask may be formed by alternately forming coating films of two hues so that the remaining coating film is not formed. Needless to say, a so-called checkered mosaic color filter may be used. Further, the shape of the coating film forming each pixel may not be a quadrangle but may be a circle or a triangle, and needless to say, may be a stripe pattern instead of a mosaic pattern.

Since this example is intended to be used as a full-color liquid crystal display device, a coating film of the third hue is formed following the above-mentioned steps, and a photosensitive film 2 is formed in the last step described above. The surface of the electrode 1 exposed by peeling is formed by an electrodeposition coating method. In this case, full-color display can be performed if the first to third hues are the three primary colors.

FIG. 4 shows an example in which a liquid crystal display device is constructed using the electrode substrate with a color filter for a full color dot matrix liquid crystal display device formed as described above. FIG. 4 is a sectional view.

In the figure, I is formed on the surface of the lower glass substrate 5.
An electrode 6'is formed by vapor deposition of TO or the like. On the surface of the electrode 6 ′, for example, red, blue,
A mosaic color filter 7 of three primary colors of green is formed. In addition, not shown polyimide, polyamide,
An alignment film made of SiO, TiO ₂ or the like is formed on the surface of the color filter 7 if necessary.

On the other hand, an electrode 9'is formed on the surface of the upper glass substrate 8, and the upper glass substrate 8 and the lower glass substrate 5 are connected to each other as shown in FIG.
Are arranged so as to face each other, and the peripheral portion is sealed with a sealant 10 such as an epoxy resin to form a liquid crystal display cell.

A liquid crystal material (not shown) is injected into this liquid crystal display cell, and a polarizing plate is installed if necessary to complete a full color dot matrix type liquid crystal display device. Needless to say, an alignment film is also formed on the surface of the electrode 9'if necessary. Furthermore, the mosaic color filter formed as described above can also be used in an active matrix type liquid crystal display panel using thin film transistors.

[0028]

In the method for forming a color filter of the present invention, the entire surface of the electrode is once covered with a photosensitive film, only the necessary portion is peeled off by the photolithography method, and only the surface from which the photosensitive film is peeled off by the step is peeled off. Since the coating film is formed by the electrodeposition coating method, it is possible to form the coating films of a plurality of hues on the same electrode surface by the electrodeposition coating method. Also, the process is simplified because the photosensitive film is formed substantially only once at the beginning, instead of re-coating the photosensitive film for each coating film having a different hue. To this end, the first
It is preferable to bake at a low temperature at which the photosensitive coating does not deteriorate when the coating film having the above hue is baked.

Further, since the electrodeposition electrode is formed on almost the entire surface of the substrate, it is possible to form an array such as a delta array of color filter patterns. Therefore, the degree of freedom regarding the arrangement of the pixels (matrix) of the formed color filter is extremely high.

[0030]

EXAMPLE ITO was vapor-deposited on the surface of a glass substrate, and electrodes were formed on almost the entire surface of the substrate as shown in FIG.

Next, a photoresist was applied to the electrode almost entirely over the surface by a spinner method to form a photosensitive film. Positive type OFPR-2 (trade name) as photoresist
It was used.

A photomask was placed on the photosensitive film, and the photosensitive film was irradiated with ultraviolet rays through the photomask by a projection method to expose the photosensitive film in the pattern of the photomask. Next, the photosensitive film is developed with a developer (HMO-81 (trade name)),
The photosensitive film in the exposed area was melted and peeled off in the pattern as shown in FIG. 2 to expose the electrode surface.

Next, the common part of the electrodes on the above-mentioned glass substrate was connected to the negative electrode of the DC stabilized power source and immersed in an electrodeposition tank filled with red paint (azo dye). A stable platinum electrode was used as the counter electrode, and a direct current voltage of 20 V was applied between both electrodes for 2 minutes to obtain a red coating film having a thickness of 1.3 μm. This red coating film was baked and spread at 120 ° C. to make the film thickness uniform.

Next, the photosensitive coating on the glass substrate is formed by the photolithography method in the same manner as the above-mentioned method.
It is peeled off in the pattern as shown in, and it is immersed in an electrodeposition tank filled with a green dye (phthalocyanine dye), and the electrodeposition coating and firing are performed under the same conditions as those for forming the above-mentioned red coating film. A green coating film having the same thickness was formed at a position adjacent to the film.

Next, the photoresist remaining on the surfaces of the glass substrate and the electrode was completely removed by a stripping agent (sulfuric acid-hydrogen peroxide) to expose the remaining surface of the electrode. A blue coating film was formed on the exposed electrode surface by the same electrodeposition coating method as above to form a mosaic color filter of three primary colors.

The spectral characteristics of this color filter are shown in FIG.

Next, ITO is formed on the upper glass substrate by vapor deposition.
The electrode and the thin film transistor were formed.

Polyimide amide was applied to the surface of this electrode and the electrode on which the above-mentioned color filter was formed by a spinner method, cured at 180 ° C. for 30 minutes, and then subjected to an alignment treatment by rubbing.

Thereafter, epoxy resin is applied to the peripheral portion of the lower glass substrate as shown in FIG.
The epoxy resin was used as a spacer / sealant at an interval of 5 μm. After forming the cell in this manner, a guest-host type liquid crystal having a positive dielectric anisotropy and adjusted to black was injected into the cell to form a full color dot matrix type liquid crystal display device.

[0040]

In the color filter forming method of the present invention, the color filter is formed by combining the photolithography method and the electrodeposition coating method. Therefore, the color of the mosaic pattern is formed by using the electrodeposition coating method. filter,
For example, a delta array color filter can be formed, and it is possible to form a color filter suitable for a fine pattern without misalignment between the electrode and the color filter.

Further, the application of the photoresist is substantially 1
Since it is only once, the production process can be simplified and the cost can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing steps of a representative example of the present invention.

FIG. 2 is a plan view showing steps of a representative example of the present invention.

FIG. 3 is a plan view showing steps of a representative example of the present invention.

FIG. 4 is a cross-sectional view showing an example in which a liquid crystal display device is configured by using a color filter formed by the method of the present invention.

FIG. 5 is an exploded perspective view showing an example of a conventional liquid crystal display device.

FIG. 6 is a spectral characteristic diagram of one example of a color filter formed by the method of the present invention.

[Explanation of Codes] 1 ... Electrode 2 ... Photosensitive coating 3, 4 ... Electrode exposed portion 3 '... Coating film forming portion 5, 8 ... Glass substrate 6 ... Y electrode 7 ... Color filter 9 ... X electrode

Claims (1)

[Claims] 1. A method for forming a color filter for forming a color filter on an electrode surface, wherein a photosensitive film is formed on at least one surface of an electrode which is substantially entirely formed on at least one surface of a substrate, and the photosensitive film is formed. A first step of exposing the electrode surface to a predetermined pattern by photolithography, and a second step of forming a coating film of a predetermined hue on the exposed electrode surface by an electrodeposition coating method, A third step of exposing the electrode surface by peeling off the photosensitive film in the area adjacent to the area where the coating film is formed on the electrode surface by a photolithography method, and exposing the electrode surface by the third step. And a fourth step of forming a coating film of a hue different from the hue on the surface of the electrode by an electrodeposition coating method. The method for forming a color filter, wherein the application of the functional coating is performed substantially only once in forming the coating films having the plurality of hues.