JPH1048413A - Color filter substrate, its production, and color liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease abnormal orientation of liquid crystal molecules and to obtain a high-quality color filter substrate and high-quality display by rubbing the substrate so that the direction of a component perpendicular to the stripes is to be from a pixel having largest film thickness to a pixel adjacent to the first pixel and having smallest film thickness. SOLUTION: When surface levels of pixels differ among colors, liquid crystal molecules are oriented along the wall faces of the color pixels. When the rubbing is carried out so that the direction of a component perpendicular to the stripe direction is from a red pixel 2 to a blue pixel adjacent to the red pixel, the orientation of liquid crystal molecules 14 on the border between the red pixel 2 and blue pixel 4 differs but produces little reverse tilt 16. When the pixels are rubbed in the direction from the red pixel 2 to the adjacent green pixel 3, orientation of liquid crystal molecules 14 differs on the border of the red pixel 2 and green pixel 3 and on the border of the green pixel 3 and blue pixel 4, which causes lots of reverse tilt 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color filter substrate suitably used for a color liquid crystal display device, a method of manufacturing the same, and a color liquid crystal display device using the same.

[0002]

2. Description of the Related Art With respect to color filters which are very important for colorizing a liquid crystal display device, there are various types of color filters of a triangle type, a mosaic type and a stripe type depending on the kind of color pixel arrangement (see FIG. 1). ). Among them, particularly, the triangle type and the mosaic type are mainly used for AV for clear image display, and the stripe type is widely used mainly for OA equipment for displaying graphics and characters.

Further, the liquid crystal display device has an alignment processing step in which a polymer alignment film such as polyimide is coated on each of the upper and lower substrates, and a rubbing treatment (so-called) is rubbed in one direction with a cloth made of fiber such as rayon. And a process of bonding the upper and lower substrates and a process of injecting a liquid crystal into the formed empty panel and sealing it. Here, in the case of a thin film transistor type liquid crystal display device, the substrate includes an upper substrate: a color filter substrate and a lower substrate: a TFT substrate. Note that a thin film transistor type liquid crystal display device is
Hereinafter, it is abbreviated as TFT-LCD.

When rubbing a color filter substrate or the like during the manufacturing process, the direction inclined 45 ° from the vertical and horizontal directions of the substrate is defined as the direction to be rubbed in the rubbing process, so that the viewing angle characteristic is reduced. We are aiming for uniformity.
In particular, in the case of a stripe type color filter, the direction of rubbing in the rubbing process is also at an angle of 45 ° with respect to the stripe direction (see FIG. 2).

However, the pixels of the color filter are:
In order to sequentially form each color pixel, there is often a so-called inter-color step having a different thickness for each color, and further, in the case of the stripe type color filter which is in great demand for OA, As described above, since the rubbing is performed in a direction inclined by 45 ° with respect to the stripe direction, the effect of the step between colors appears as an abnormal alignment of liquid crystal molecules at the interface between the alignment film and the liquid crystal layer. The display quality of a liquid crystal display device may be reduced.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is intended to manufacture a color liquid crystal display device using a color filter having a stripe type and a step between colors. (Or
It is an object of the present invention to provide a color filter substrate having high quality and a high quality color filter substrate by reducing abnormal alignment of liquid crystal molecules in order to reduce display defects.

[0007]

Means provided by the present invention in order to solve the above-mentioned problems are as follows. First, as described in claim 1, pixels of the same color are sequentially arranged in a predetermined direction in a stripe shape.
In addition, there is a color filter having a different film thickness for each type of pixel color, and with respect to the direction in which the alignment film provided on the color filter has been subjected to the rubbing process, the direction of the component which is perpendicular to the stripes. Is a color filter substrate characterized in that it faces from the color pixel having the thickest film thickness to the color pixel adjacent to the color pixel and having the thinnest film thickness.

According to a second aspect of the present invention, there is provided a color filter in which pixels of the same color are sequentially arranged in stripes in a predetermined direction, and the thickness of each color is different for each pixel type.
After forming an alignment film on the color filter, the direction of a component perpendicular to the stripe with respect to the direction of the rubbing treatment is changed from the color pixel having the largest film thickness to the color pixel. A method of manufacturing a color filter substrate, characterized by performing a rubbing process so as to face a color pixel which is adjacent and has the thinnest film thickness.

According to a third aspect of the present invention, there is provided a color filter in which pixels of the same color are sequentially arranged in stripes in a predetermined direction, and the color filters have different film thicknesses for each type of pixel color. With respect to the direction in which the alignment film provided above has been subjected to the rubbing treatment, the direction of the component perpendicular to the stripe is from the side of the color pixel having the largest film thickness, adjacent to the color pixel, and A color liquid crystal display device comprising a color filter substrate facing a color pixel having the smallest thickness.

According to another aspect of the present invention, there is provided a color liquid crystal display device including a color filter in which pixels of the same color are sequentially arranged in a stripe shape in a predetermined direction, and the film thickness of each pixel is different from each other. With respect to the orientation direction of the liquid crystal, the direction forming a direction component perpendicular to the stripe is the color adjacent to the color pixel having the largest thickness and the color having the smallest thickness from the side of the color pixel having the largest thickness. A color liquid crystal display device characterized by being oriented in the direction of a pixel.

The color filter according to the present invention belongs to the category of so-called stripe type color filters, and can be said to be a color filter having a step between colors. Note that a color filter having a step between colors refers to the height of a color pixel in the plane of one color filter,
Or a color filter in which the height of a color pixel among a plurality of color filters has a clear difference in height between a pixel of one color and a pixel of another color, even if there is manufacturing variation. Things. For example, in the case of a color filter in which color pixels are provided with different film thicknesses for each color on the same plane, it can be said that this is a representative example of a color filter having a step between colors. Here, the main reason for changing the film thickness of the color pixel is usually to obtain the spectral characteristics required for a color filter. Now, after forming the alignment film on the color filter, the rubbing direction which is also a normal rubbing direction, that is, the rubbing direction performed at an angle of 45 ° to the stripe direction of the color filter, is The rubbing process is performed so that the direction of the vertical direction component goes from the side of the color pixel having the thickest film thickness to the side of the color pixel adjacent to the color pixel and having the thinnest film thickness.

In the case where a color filter of stripe type and having a step between colors is used in the above process, the direction of the rubbing treatment which is performed at an angle of 45 ° with respect to the normal stripe direction is changed to the alignment direction. It is necessary to set more strictly in consideration of the direction of the step between colors so that the number of abnormal portions is reduced as much as possible.

For example, when the thickness of each color pixel is reduced in the order of red pixel (R)> green pixel (G)> blue pixel (B), the component perpendicular to the rubbing direction in the stripe direction is obtained. When the rubbing is performed such that the direction of the red pixel is directed from the red pixel to the adjacent blue pixel, the alignment film on the color filter substrate and the liquid crystal are compared with the case where the rubbing is performed so that the red pixel is directed to the adjacent green pixel. At the layer interface, the places where the directions of the liquid crystal molecules (the so-called director directions) are opposite to each other are reduced, and the rising direction of the liquid crystal molecules when an electric field is applied differs between the adjacent left and right regions (the so-called reverse tilt).
This is because it is possible to reduce the occurrence of alignment abnormality (such as a zigzag defect) due to the occurrence of the reverse tilt.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, the liquid crystal molecules are generally oriented in the rubbing direction. However, if there is a step between colors as described above, the liquid crystal molecules are oriented along the color pixel wall surface. Then, as shown in FIG. 5A, when the rubbing is performed such that the direction of the component perpendicular to the rubbing direction of the stripe direction is from the red pixel to the blue pixel adjacent thereto, the boundary between the red pixel and the blue pixel is obtained. When the rubbing is performed in such a manner that the direction of the liquid crystal molecules is different from each other, and the rubbing is performed in a direction from the red pixel to the adjacent green pixel as shown in FIG.
The direction of the liquid crystal molecules is different at the boundary between the green pixel and the blue pixel.

Therefore, at the boundary between the alignment film and the liquid crystal layer, the rising direction of the liquid crystal molecules when an electric field is applied is different between the left and right regions, so that reverse tilt is likely to occur and zigzag defects and the like are generated. Orientation abnormality is easily observed. In fact, when trying to observe the appearance of the rise of liquid crystal molecules, prepare a liquid crystal display device filled with liquid crystal,
Observing the state of applying a voltage to the liquid crystal layer using, for example, a polarizing microscope, it can be seen that the liquid crystal rises from the rubbing direction. Whether the color liquid crystal display device according to the present invention, for example, by such observation,
Alternatively, when the color liquid crystal display device is disassembled, a groove-like trace due to the rubbing treatment can be confirmed (for example, by a high-resolution observation means such as an electron microscope). The thickness of the color filter is determined by using a known means for measuring a minute thickness (for example, a method using the degree of depth of focus adjustment of a microscope, or the like) so that the color filter meets the requirements according to the present invention. It is possible to check whether or not the condition is satisfied.

By the way, comparing FIG. 5A and FIG. 5B, FIG. 5A shows a stripe type in which the region where the alignment abnormality occurs is smaller, and has a step between colors. When an rubbing process is performed by forming an alignment film on a color filter having the rubbing process, the direction of a component perpendicular to the stripe direction in the rubbing process performed at an angle of 45 ° with respect to the normal stripe direction is the best. If the rubbing direction is set so as to be from the thick color pixel to the adjacent thinnest color pixel, a better quality color filter substrate and a high quality A color liquid crystal display device can be realized.

Hereinafter, a TFT-LCD which is a mainstream as a so-called color liquid crystal display device will be described as an example, and its manufacturing process will be briefly described with reference to the drawings.

(See FIG. 3) First, an alignment film is formed on each of the TFT substrate and the color filter (CF). After cleaning each substrate, the alignment film is usually called a rubbing process, in which a polymer film such as polyimide is formed on the substrate by a flexographic printing process and a subsequent curing process, and the film is rubbed in one direction with a cloth such as rayon. Processing completes the formation.

Further, after each substrate is washed, spacers are sprayed on the TFT substrate, and a sealing material is applied on the color filter substrate. In the spacer dispersing step, a spherical spacer having a predetermined diameter is dispersed in a water / alcohol-based solution so that the spherical spacer is distributed on the substrate at about 10 / mm ² .
The method of spraying it is mainstream. In the sealing material application step, a rectangular seal pattern frame having a liquid crystal injection port and the same width is formed by a screen printing method. Usually, a spacer is mixed with a predetermined ratio in the sealing material.

Then, the TFT substrate and the color filter substrate are bonded together. The bonding step is a step of bonding the TFT substrate and the color filter substrate accurately using the alignment mark, and then baking under pressure to cure the sealing material while maintaining the gap between the substrates. .

The subsequent liquid crystal injecting step is a step of injecting the liquid crystal into the completed empty panel by a vacuum injecting method, and sealing the inlet with an adhesive. In vacuum injection, first, the injection tank is evacuated to about 10 ^-3 Torr, then an empty panel is immersed in a liquid crystal reservoir installed in the tank, and the liquid is injected into the empty panel by gradually leaking the inside of the tank. In principle, the principle is the use of capillary action due to pressure differences. In addition, for sealing the injection port, apply UV curable resin to the injection port, and apply UV
It is cured by irradiation.

(Refer to FIG. 4.) Finally, the color liquid crystal display device is completed by washing, attaching a polarizing plate, and the like.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a TFT substrate and a stripe type color filter having a step between colors (pigment dispersion type, red pixel thickness 1.5 μm, green pixel thickness 1.3 μm, and blue pixel thickness 1. 1 μm) were prepared, and they were subjected to ultrasonic cleaning while being immersed in acetone, ethanol, and pure water in this order for several minutes each. Next, a polyimide film (manufactured by Hitachi Chemical Co., Ltd., trade name: LQ-T1)
20) was formed with a thickness of 0.1 μm.

Next, regarding the color filters, first,
In the direction from the pixel red pixel to the blue pixel where the direction of the direction component perpendicular to the stripe direction is from the thickest color pixel to the adjacent thinnest color pixel 45 to the stripe direction
し Rubbing is performed diagonally.
Rubbing was performed in a predetermined direction in consideration of the rubbing direction of the color filter substrate.

Next, the same cleaning as that described above was performed, and a glass spacer (manufactured by Sumita Optical Glass, particle size 6.5 μm) was removed.
Scattered on the TFT substrate under the condition that the number of the spacers becomes about 0.1 / mm ² .
A seal material (trade name: Structbond XN-21-S, manufactured by Mitsui Toatsu Chemicals) to which 5% by weight was added was applied and formed by a screen printing method using a predetermined plate pattern.

Then, the color filter substrate and the TFT substrate are attached to each other, and are pressed while using a predetermined jig.
It was baked in an oven at 0 ° C. for 1 hour. After slow cooling, the empty panel is taken out and the liquid crystal (Merck, trade name: ZL)
After vacuum injection of I-4792), the injection port was sealed with a sealant (manufactured by Nippon Denki Co., trade name: DNM-2110) to complete a color liquid crystal display device.

For comparison, as a comparative example, the same TFT substrate and the same color filter as those in the above-described embodiment were separately prepared, and the rubbing direction of the alignment film on the color filter was in the opposite direction to that in the above-described embodiment. From the red pixel to the green pixel, the direction of the component perpendicular to the stripe direction is from the thickest color pixel to the second thickest color pixel adjacent to it. And the rubbing process is performed at an angle of 45 ° to the stripe direction.
A color liquid crystal display was completed.

Finally, in each of the color liquid crystal display devices of the embodiment and the comparative example, between the crossed Nicols of the polarizing microscope, the rise and the alignment state of the liquid crystal molecules when an electric field was applied were observed. As a result, the color liquid crystal display device completed as an example is a high quality color liquid crystal display device with less occurrence of alignment abnormalities such as reverse tilt at the boundary between color pixels than the color liquid crystal display device of the comparative example. Confirmed that there is.

[0029]

As described above, according to the present invention, it is possible to reduce alignment abnormalities such as reverse tilt which are likely to occur at the boundary between color pixels. According to the result, in order to reduce display defects that may occur when a color liquid crystal display device is manufactured using a color filter having a stripe type and a step between colors, alignment abnormalities of liquid crystal molecules can be reduced, As a result, a high-quality color filter substrate, a method of manufacturing the same, and a color liquid crystal display device capable of high-quality display can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing color filters by type. (A) Triangle type color filter (b) Mosaic type color filter (c) Stripe type color filter

FIG. 2 is an explanatory view schematically showing an example of a rubbing direction according to a conventional technique for a stripe type color filter substrate.

FIG. 3 is an explanatory view schematically showing a general manufacturing process of a color liquid crystal display device.

FIG. 4 is an explanatory diagram schematically showing a general cross-sectional structure of a TFT-LCD.

FIG. 5 is an explanatory view schematically showing a rubbing direction in a stripe type color filter. (A) In the case of the embodiment of the stripe type color filter according to the present invention (b) In the case of the stripe type color filter according to the comparative example

[Explanation of symbols]

1 color filter 2 red pixel 3 green pixel 4 blue pixel 5 rubbing direction 5 'rubbing direction (another example) 6 ··· Color filter substrate 7 ··· TFT substrate 8 ··· TFT 9 ··· Sealing material 10 ··· Alignment film 11 ··· Color filter layer 12 ··· Liquid crystal layer 13 ··· · Spacer 14 · · · Liquid crystal molecules 15 · · · Direction of the direction component perpendicular to the rubbing stripe direction 16 · · · Location of reverse tilt

Claims (4)

[Claims] 1. A color filter in which pixels of the same color are sequentially arranged in a stripe shape in a predetermined direction, and a color filter having a different film thickness for each type of pixel color is provided. An alignment film provided on the color filter is subjected to a rubbing process. With respect to the given direction, the direction of the component perpendicular to the stripe is from the side of the color pixel having the largest thickness to the color pixel adjacent to the color pixel and having the smallest thickness. A color filter substrate characterized by being oriented. 2. An alignment film is formed on a color filter in which pixels of the same color are sequentially arranged in a stripe pattern in a predetermined direction and have different film thicknesses for each type of pixel color. Later, with respect to the direction of the rubbing process, the direction of the component perpendicular to the stripe is shifted from the side of the color pixel having the largest thickness to the color pixel adjacent to the color pixel and having the smallest thickness. A method of manufacturing a color filter substrate, comprising performing a rubbing process so as to face the substrate. 3. A color filter in which pixels of the same color are sequentially arranged in a stripe pattern in a predetermined direction, and a color filter having a different film thickness for each type of pixel color is provided. With respect to the direction subjected to the rubbing process, the direction of the component perpendicular to the stripe is from the side of the color pixel having the largest thickness to the color pixel adjacent to the color pixel and having the smallest thickness. A color liquid crystal display device comprising a color filter substrate facing in a direction. 4. A color liquid crystal display device comprising a color filter in which pixels of the same color are sequentially arranged in a stripe pattern in a predetermined direction, and a color filter having a different film thickness for each type of color of the pixels. With respect to the above, the direction forming a direction component perpendicular to the stripe is oriented from the side of the color pixel having the largest thickness to the direction of the color pixel adjacent to the color pixel and having the smallest thickness. A color liquid crystal display device characterized by the above-mentioned.