JP2006330150A - Color filter for liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color filter for a liquid crystal display apparatus, the filter having color pixels in a plurality of colors on a transparent substrate and having excellent flatness of the surface with a minute level difference, and thereby, to save a polishing process, to stabilize a chromaticity of the color pixels, to reduce processes and to exclude an overcoat layer in an IPS (in-plane switching) system. <P>SOLUTION: A light shielding portion 15 is formed by overlapping a peripheral edge of a color pixel 12 having the peripheral edge 12S having a tapered cross-section form with a peripheral edge of a color pixel 14 in another color which is adjacent to the first pixel and has the peripheral edge 14S with a tapered cross-sectional form. The height H1 (level difference) from the upper face of the color pixel to the upper face of the light shielding part is ≤0.5 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a color filter, and more particularly to a color filter for a liquid crystal display device having a small surface level difference and excellent flatness.

FIG. 3 is a plan view schematically showing an example of a color filter used in the liquid crystal display device. 4 is a cross-sectional view of the color filter shown in FIG. 3 taken along line XX ′.
As shown in FIGS. 3 and 4, the color filter used in the liquid crystal display device has a black matrix (51) and colored pixels (52) sequentially formed on a glass substrate (50).
3 and 4 schematically show a color filter, and 12 colored pixels (52) are shown. In an actual color filter, for example, several hundreds of pixels are displayed on a 17-inch diagonal screen. A large number of colored pixels of about μm are arranged.

The black matrix (51) is a matrix having light shielding properties, and the colored pixels (52) have, for example, red, green, and blue filter functions.
The black matrix determines the position of the colored pixels of the color filter, makes the size uniform, and shields unwanted light when used in a display device, making the image of the display device uniform and uniform. In addition, it has a function of making an image with improved contrast.

This black matrix (51) is an example in which a resin is used as a black matrix material on a glass substrate (50).
The black matrix (51) is formed on the glass substrate (50) by, for example, a photolithography method using a black photosensitive resin for forming a black matrix, and the black matrix formed using the resin. Is referred to as a resin black matrix (51).

  The colored pixel (52) is a photolithography method using a negative colored photoresist in which a pigment such as a pigment is dispersed on the glass substrate (50) on which the resin black matrix (51) is formed. That is, it is formed as a colored pixel by exposure to a coating film of a colored photoresist through a photomask and development processing. Red, green, and blue colored pixels are sequentially formed.

  The resin black matrix, for example, causes internal reflection in a liquid crystal display device that occurs when a metal such as chromium is used as a black matrix (not shown) when using a high-brightness backlight such as a television. In order to suppress a low-reflection resin black matrix, or in order to suppress an electric field disturbance in a liquid crystal display device when used in, for example, an IPS (In Plane Switching) system, a high insulation is required. It has been adopted when a functional resin black matrix is required. However, the black matrix is gradually shifting from a black matrix using a metal such as chromium to a resin black matrix.

When a large number of color filters are manufactured, a color filter corresponding to a single liquid crystal display device is manufactured in a state where it is applied to a large glass substrate. For example, a 17-inch diagonal color filter is manufactured by attaching four faces to a large glass substrate of about 650 mm × 850 mm.
Resin black matrix formed by photolithography using a black photosensitive resin rather than a black matrix that uses a metal such as chromium as a black matrix material to form a thin film with a vacuum device as the glass substrate becomes larger Is becoming more advantageous in terms of price, and is gradually shifting to a resin black matrix. Moreover, it tends to avoid using metals such as chromium in consideration of the environment.

The resin black matrix cannot obtain a high concentration in a thin film with a film thickness of about 100 nm to 200 nm, like a black matrix using a metal such as chromium, for example, a thickness of about 1.0 μm to 1.5 μm. To obtain the necessary high concentration.
When the film thickness of the resin black matrix is increased to, for example, about 1.0 μm, as shown in FIG. 4, the colored pixel (52) formed by overlapping the peripheral portion on the resin black matrix (51) The peripheral edge becomes a protrusion (53) on the end of the resin black matrix (51).

The height of the protrusion (53) is such that, for example, a colored pixel (52) having a thickness of about 1.5 μm is formed on the end portion of the resin black matrix (51) having a thickness of about 1.3 μm by overlapping the peripheral portion thereof. When formed, the thickness is about 1.0 μm.
This protrusion (53) makes the surface of the color filter uneven, and deteriorates flatness. When a color filter having such protrusions (53) with a deteriorated surface flatness is used in a liquid crystal display device, the alignment of liquid crystal molecules is disturbed due to the influence of the protrusions, or display unevenness occurs. When the transparent conductive film is formed, the display quality and reliability are lowered, such as contact with the electrode of the opposing panel, causing a short circuit, disconnection of the transparent conductive film, or undesired components flowing out from the crack. Become.

The height of the projection that does not adversely affect the display quality of the liquid crystal display device, that is, the projection that does not disturb the alignment of the liquid crystal molecules, is approximately 0.5 μm or less from the top surface of the colored pixel to the top surface of the projection. Is.
As a technique for avoiding the formation of such protrusions or a technique for flattening the surface of the color filter, the following techniques have been proposed.

1) For example, in Japanese Patent Laid-Open No. 10-96809, protrusions are generated at the end of a black matrix by giving exposure to the colored photosensitive resin through a photomask from the back side of the glass substrate on which the black matrix is formed. This technique avoids the problem.
At the time of exposure, a reflection plate for reflecting ultraviolet light from the back surface side of the glass substrate is provided on the upper surface of the coating film in order to compensate for insufficient curing due to light attenuation on the upper coating film of the colored photosensitive resin.
However, this technique suffers from insufficient attenuation and insufficient curing.

2) Japanese Patent Laid-Open No. 9-43412 discloses a resin black matrix having a reduced thickness by increasing the content of a black pigment contained in the black photosensitive resin used for forming the resin black matrix.
This technique has a drawback in that the effect of reducing the height of the protrusion is insufficient.

3) Japanese Patent Laid-Open No. 2002-228826 discloses that an overcoat layer having an excessive thickness is provided on a glass substrate on which a resin black matrix and colored pixels are formed using a positive photosensitive resin, and exposure is given. This is a technique of making the film soluble in a developer and flattening it by developing it to a desired thickness.
This technique has a drawback in that a step of providing an overcoat layer is added.

Therefore, in many cases, the height of the protrusion formed by polishing on the surface of the color filter is reduced.
However, when the color filter surface is polished, for example, when a protrusion having a height of about 1.0 μm is performed to the height (step) of the protrusion that does not disturb the alignment of liquid crystal molecules, the color filter surface is colored. A certain amount of polishing is applied to the pixel, and the chromaticity is changed, and the productivity is reduced by increasing the polishing amount.

  In addition, in a color filter used in the IPS system, when a photosensitive pigment dispersion resin composition is used as a material for forming a colored pixel or the like, a trace amount of alkali metal ions or nitrate ions from the formed colored pixel or the like is used. Chlorine ions or the like, or, for example, trace amounts of alkali metal ions from the residue of the material used in the patterning process for forming colored pixels as pixels, are eluted in the liquid crystal material, which hinders the operation of the liquid crystal. Display quality may be adversely affected.

Therefore, in color filters used in the IPS system, a protective layer (overcoat layer) on the colored pixels is often provided as an eluent barrier after the colored pixels are formed.
Since this overcoat layer can have a function of flattening the surface of the color filter on which the protrusions are formed, the color filter used in the IPS system is not polished to reduce the height of the protrusions. In addition, an overcoat layer is provided so as to provide flatness and also serve as a barrier for the eluate.
Japanese Patent Laid-Open No. 10-96809 Japanese Patent Laid-Open No. 9-43412 JP 2002-228826 A

It is an object of the present invention to provide a color filter for a liquid crystal display device in which a plurality of colored pixels are provided on a transparent substrate, and having a fine step on the surface and excellent in flatness. is there.
This eliminates the need for polishing, stabilizes the chromaticity of the colored pixels, and reduces the number of steps. Further, in the color filter used in the IPS system, it is possible to omit the overcoat layer. That is, an inexpensive color filter for a liquid crystal display device can be provided.

  The present invention relates to a color filter in which a plurality of colored pixels are provided on a transparent substrate, and adjacent to a peripheral portion of a colored pixel having a peripheral portion having a tapered cross section, and having a peripheral portion having a tapered cross section. A color filter for a liquid crystal display device, characterized in that a light shielding portion is formed by overlapping the peripheral portions of colored pixels of other colors.

  In the color filter for a liquid crystal display device according to the present invention, the height (step) from the upper surface of the colored pixel to the upper surface of the light shielding portion is 0.5 μm or less. This is a device color filter.

According to the present invention, a light-shielding portion is formed by superimposing the peripheral portions of adjacent colored pixels having a tapered cross-sectional shape on the peripheral portion of a colored pixel having a peripheral portion having a tapered cross-sectional shape. As a result, the surface step is minute and the color filter has excellent flatness.
In the present invention, since the height (step) from the upper surface of the colored pixel to the upper surface of the light shielding portion is 0.5 μm or less, the alignment of the liquid crystal molecules is not disturbed, and the display quality of the liquid crystal display device is adversely affected. Never give.
This eliminates the need for polishing, stabilizes the chromaticity of the colored pixels, and reduces the number of steps. Further, in the color filter used in the IPS system, it is possible to omit the overcoat layer. That is, an inexpensive color filter for a liquid crystal display device can be provided.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 is a cross-sectional view schematically showing an embodiment of a color filter for a liquid crystal display device according to the present invention. FIG. 1 is an enlarged view of a portion between a first color pixel and a second color pixel.
As shown in FIG. 1, the color filter portion for a liquid crystal display device shown as an example has a first color pixel (12) formed on a glass substrate (10), and then a second color. Colored pixels (14) are formed.

The colored pixel (12) of the first color has a peripheral portion (12S) having a tapered cross section, and the colored pixel (14) of the second color has a peripheral portion (14S) having a tapered cross section. have. The second color pixel (14) adjacent to the first color pixel (12) is on the peripheral edge (12S) of the first color pixel (12) formed on the glass substrate (10). The peripheral edge portion (14S) is overlapped, and the overlapping portion is a light shielding portion (15).
That is, the light-shielding portion (15) includes a peripheral portion (12S) of the first color pixel (12) and a peripheral portion (14S) of the second color pixel (14).

  In FIG. 1, reference numeral (A) indicates the region of the first color pixel (12), and reference numeral (B) indicates the first color pixel (12) when used in the liquid crystal display device. Display area. Similarly, the symbol (A ′) indicates the region of the colored pixel (14) of the second color, and the symbol (B ′) indicates the colored pixel (14 of the second color when used in the liquid crystal display device. ) Display area.

When the area (A, A ′) of the colored pixels (12, 14) is about 200 μm, the width (W1) of the light shielding portion (15) is, for example, about 20 μm, and the first color pixel ( The thickness (T1) of 12) and the thickness (T2) of the colored pixel (14) of the second color are about 1.5 μm. The first color pixel (12) has a taper angle (θ) of about 2 ° to 45 °.
The height (step) (H1) from the upper surface of the colored pixel (12) of the first color or the colored pixel (14) of the second color to the upper surface of the light shielding portion (15) is very small. This height (step) (H1) is preferably 0.5 μm or less.

  On the other hand, FIG. 5 is an enlarged cross-sectional view of the vicinity of the protrusion (53) shown in FIG. 4, but as shown in FIG. 5, a resin black matrix having a thickness of about 1.3 μm and a width (W2) of about 20 μm ( 51), and in the color filter in which the thickness (T11) of the colored pixel (52) and the thickness (T12) of the colored pixel (52 ′) are about 1.5 μm, the height of the protrusion (53) ( The step (H2) is about 1.0 μm.

That is, the color filter for a liquid crystal display device according to the present invention is not provided with a resin black matrix, and the cross-sectional shape is tapered at the peripheral portion of the colored pixel having a peripheral portion having a tapered cross-sectional shape at that portion. Since the light-shielding portion is formed by overlapping the peripheral portions of adjacent colored pixels having other peripheral portions, the step (H1) corresponding to the protrusion is very small. As shown in FIG. 1, the thickness of the peripheral portion having a tapered cross-sectional shape is such that the thickness decreases toward the tip.
Accordingly, it is not necessary to perform polishing, the chromaticity of the colored pixels is stabilized, and the number of processes can be reduced. Further, in the color filter used in the IPS system, it is possible to omit the overcoat layer. That is, an inexpensive color filter for a liquid crystal display device can be provided.

2A to 2D are cross-sectional views illustrating an example of a method for manufacturing a color filter for a liquid crystal display device according to the present invention. FIG. 2A shows a state in which exposure is performed through a photomask (PM1) for forming the colored pixels (12) of the first color. On the glass substrate (10), a negative colored photoresist (20) for the colored pixel (12) of the first color is applied.
The density of the light-shielding portion of the photomask (PM1) used for forming the first color pixel (12) is represented by the height indicated by the symbol (D).

Since the uniform irradiation light (L) from above the photomask (PM1) is diffracted at the end of the light-shielding portion of the photomask (PM1), the colored pixels (first color) obtained in the development processing after exposure ( The peripheral portion (12S) of 12) has a tapered cross section as shown in FIG.
In FIG. 2A, in order to obtain diffracted light, an interval is provided between the negative colored photoresist (20) and the photomask (PM1). By adjusting this gap (G), the width (W1) of the peripheral portion (12S) of the colored pixel (12) of the first color is set.

In FIG. 2C, the photomask (PM2) for forming the second color pixel (14) is formed on the glass substrate (10) on which the first color pixel (12) is formed. It shows a state where exposure is performed.
On the glass substrate (10), a negative colored photoresist (30) for the colored pixel (14) of the second color is applied.
The photomask (PM2) used for forming the second color pixel (14) has a density similar to that of the photomask (PM1) as shown by the hatched lines in FIG. 2 (c). .

The uniform irradiation light (L) from above the photomask (PM2) is diffracted at the end of the light-shielding portion of the photomask (PM2), so that the colored pixels (second color) obtained by the development processing after exposure ( As for the peripheral part (14S) of 14), as shown in FIG.2 (d), a cross-sectional shape becomes a taper shape.
In FIG. 2C, a space is provided between the negative colored photoresist (30) and the photomask (PM2) in order to obtain diffracted light. By adjusting this interval (G), the width (W1) of the peripheral portion (14S) of the colored pixel (14) of the second color is set.

  There is no resin black matrix below the light shielding portion (15) formed by the peripheral portion (12S) of the first color pixel (12) and the peripheral portion (14S) of the second color pixel (14). Therefore, the level difference (H1) corresponding to the protrusion is very small, and a thickness of 0.5 μm or less can be easily obtained.

It is sectional drawing which showed typically one Example of the color filter for liquid crystal display devices by this invention. (A)-(d) is sectional drawing explaining an example of the manufacturing method of the color filter for liquid crystal display devices by this invention. It is the top view which showed typically an example of the color filter used for a liquid crystal display device. It is sectional drawing in the X-X 'line | wire of the color filter shown in FIG. It is sectional drawing to which the vicinity of the protrusion shown in FIG. 4 was expanded.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 50 ... Glass substrate 12 ... Colored pixel 12S of the 1st color in this invention ... Peripheral part 14 of the colored pixel of the 1st color ... Colored pixel 14S of the 2nd color in this invention ... The peripheral edge 15 of the colored pixel of the second color ... the light shielding part 20, 30 ... the negative colored photoresist 51 ... the black matrix 52 ... the colored pixel 53 ... the protrusion (step)
A ... Colored pixel area A '... Colored pixel area B of second color ... Colored pixel display area B' of first color ... Colored pixel of second color Display area D: Height G representing the density of the light-shielding portion of the photomask ... Distance L between the photomask and the colored photoresist ... Irradiation light H1 ... Small step H2 in the present invention ... Height of protrusion (step)
PM1 ... Photomask PM2 for the first color pixel ... Photomask T1 for the second color pixel ... T1 thickness of the first color pixel T2 ... Second color Pixel thickness T11, T12 ... Colored pixel thickness W1 ... Shading width W2 ... Resin black matrix width

Claims (2)

  In a color filter in which a plurality of colored pixels are provided on a transparent substrate, the peripheral portion of the colored pixel having a peripheral portion having a tapered cross-sectional shape is adjacent to another color having a peripheral portion having a tapered cross-sectional shape. A color filter for a liquid crystal display device, characterized in that a light shielding portion is formed by overlapping the peripheral edge portions of the colored pixels.   2. The color filter for a liquid crystal display device according to claim 1, wherein a height (step) from the upper surface of the colored pixel to the upper surface of the light shielding portion is 0.5 [mu] m or less.

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