JPH10186364A - Rubbing processing device, rubbing processing method, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly rub the surface of a substrate to be processed having difference in level and to improve the display grade of a liq. crystal display device. SOLUTION: Belt-like electrodes 54a, 54b for display and films to be processed 55a, 55b for covering these electrodes 54a, 54b are formed on one surface of rectangular substrates 53a, 53b of the substrates to be processed 51a, 51b. Rubbing process is executed by relatively moving the substrate to be processed and a rubbing roller 52 is brought into contact with the surface of this film to be processed, and while being rotated round a revolving shaft 58. Selections are respectively made to keep the longitudinal directions 62a, 62b of the electrode to be in parallel with one side 53c of the substrate, one juxtaposed direction 63 of piles of a rubbing cloth 57 of the rubbing roller 52 to be in parallel with the revolving shaft 58 and the angle θ1 between the juxtaposed direction 63 and the longitudinal directions 62a, 62b of the electrodes to be within the range of ±5 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubbing apparatus which is used for forming an alignment film of a device using a liquid crystal such as a liquid crystal display, and performs a rubbing process on a predetermined film to be processed. It relates to a rubbing treatment method. Further, the present invention relates to a rubbing cloth and a rubbing roller provided in the rubbing treatment device. Further, the present invention relates to a liquid crystal display device having an alignment film formed by performing a rubbing process using the rubbing device.

[0002]

2. Description of the Related Art As a device using liquid crystal, there is, for example, a liquid crystal display device. The liquid crystal display device is, for example, an OA such as a word processor or a personal computer.
(Office Automation) It is suitably used as a display means of a device, and specifically, for example, an STN (super twisted nematic) type liquid crystal display device is exemplified.

A liquid crystal display device has a structure in which a liquid crystal is interposed between a pair of substrate members, at least one of which has translucency. The pair of substrate members is formed, for example, by forming a display electrode on a light-transmitting substrate and forming an alignment film on a substrate including the electrode. In the STN-type liquid crystal display device, liquid crystal molecules interposed between the substrate members are twist-oriented between the substrate members by 180 ° or more, for example, in the range of 210 ° to 260 °. The alignment film has a function of aligning the alignment direction of the liquid crystal molecules in one direction, and a rubbing process using a predetermined rubbing processing device is performed on the surface to add the function.

FIG. 7 is a plan view showing a substrate 1 and a rubbing roller 2 for explaining a rubbing process using a conventional rubbing apparatus. Substrate to be processed 1
Has a display electrode 4 formed on one surface of a substrate 3,
A processing target film 5 made of a resin such as polyimide is formed so as to cover the electrode 4. The rubbing roller 2 is configured by winding a rubbing cloth 7 on the surface of a roller 6 with a double-sided adhesive sheet or the like.

Specifically, the rubbing roller 2 is brought into contact with the surface of the film 5 to be processed at a predetermined pressure, and the rubbing roller 2 is rotated about a rotation shaft 8 in a predetermined direction 9 at a predetermined speed. While moving the substrate 1 to be processed and the rubbing roller 2 relatively,
Is moved in the direction 10 and the surface of the target film 5 is rubbed in a certain direction.

Here, in a liquid crystal display device that performs dot matrix display, the following conditions are selected. The substrate 3 of the substrate to be processed 1 is rectangular. The electrode 4 has a band shape, and its longitudinal direction and one side 3a of the substrate 3 are selected in parallel. The rubbing cloth 7 of the rubbing roller 2 is a cloth in which a pile as described later is planted, and the direction in which the piles are arranged and the rotation axis 8 are selected in parallel. Further, at the time of the rubbing process, the side 3a of the substrate 3, which is the side where the rubbing process is started, and the rotation axis 8 are selected at a predetermined angle α. The rubbing direction 11 is a direction orthogonal to the direction in which the piles of the rubbing roller 2 are arranged in parallel. Here, the direction is orthogonal to the rotation axis 8.

FIG. 8A shows a cloth 12 for the rubbing cloth 7.
FIG. 8B is a perspective view showing the cloth 12 in an enlarged manner. The cloth 12 for the rubbing cloth 7 is a cloth in which piles tens of dozens of filaments are knitted into ground yarns 13 knitted vertically and horizontally, and the planted lengths of the piles 14 are evenly arranged. The fabric 12 is made in consideration of the utilization efficiency,
Along one direction 15a of the pile 14 and a direction 15b orthogonal to the one direction 15a, the circumferential length of the roller 6 is defined as one side length, and the width direction length of the roller 6 is defined as the other side length. After being cut into a rectangular shape, the juxtaposed direction 15a and the rotating shaft 8
Are wound around the roller 6 so as to be parallel to each other.

FIG. 9 is a plan view for explaining an STN type liquid crystal display device 16 having an alignment film formed by using the above-described conventional rubbing device. The direction of the viewing angle with respect to the display screen of the liquid crystal display device 16 is as shown in FIG.
As shown in the figure, the vertical direction and the horizontal direction are 12:00, 6 o'clock, 9 o'clock, and 3 o'clock directions on the paper surface, and the direction in which the contrast ratio is the largest is, for example, 12:00 o'clock. Viewing angle setting. The rubbing direction is selected so that the distribution of the contrast ratio and the like depending on the viewing angle direction is symmetrical in the vertical and horizontal directions.

On the other hand, the substrate member 17 is, for example, shown in FIG.
As shown in FIG.
9 is formed, and an alignment film 20 is formed so as to cover the strip electrode 19. The strip electrode 19 is orthogonal to the side 18 a of the substrate 18 where the rubbing process is started, that is, the side 18 a in the 12:00 direction. Formed in the direction. The angle between the rubbing direction 11a and the side 18a is selected as β1, and the rubbing process is performed to form the alignment film 20.

Similarly, as shown in FIG. 9C, the other substrate member 21 has a strip electrode 23 formed on one surface of a substrate 22, and an alignment film 24 covers the strip electrode 23. The strip-shaped electrode 23 is formed on the side 22a of the substrate 22 at which the rubbing process is started, ie, 1 side.
It is formed parallel to the side 22a in the 2 o'clock direction. The angle between the rubbing direction 11b and the side 22a is selected as β2 and rubbing is performed to form the alignment film 24.

The alignment films 20 and 2 thus formed are
The substrate members 17 and 21 each having the substrate 4 shown in FIG.
As shown in FIG. 3, the alignment films 20 and 24 are opposed to each other, the rubbing directions 11a and 11b are set to form an angle γ, and the substrates are bonded to each other with a liquid crystal interposed between the substrate members 17 and 21. The liquid crystal display device 16 is used. The angles β1 and β2 are, for example, both set to 30 °,
Angle γ is chosen to be 240 °. The angle γ is a twist angle (twist angle) of the liquid crystal molecules interposed between the substrate members 17 and 21 between the substrate members.

[0012]

In recent years, the market for liquid crystal display devices that perform STN-type dot matrix display has been expanding not only as notebook personal computers but also as thin display means due to improvements in display characteristics. With respect to the increase in screen size and definition, it is important to improve the in-plane uniformity of display quality, particularly the in-plane uniformity of display quality and the contrast ratio in halftone display.

FIG. 10 is an enlarged sectional view showing a state during the rubbing process. The target film 5 is formed so as to cover the electrode 4.
And the thickness of the target film 5 is, for example, 500
電極, the electrode 4 is placed on the surface of the substrate 1 to be processed.
Step occurs. The rubbing roller 2 rubs the surface of the substrate to be processed 1 having such a step with a pile 14.

With the demand for larger screens and higher definition,
The load on the drive voltage due to the resistance of the electrode 4 increases. In order to reduce this load, the thickness of the electrode 4 of the substrate 1 to be processed is formed to be large, whereby the step tends to be large.

FIG. 11 is an enlarged view showing a state of a conventional rubbing process. FIG. 11A is a plan view, and FIG. 11B is a perspective view. The substrate 3 of the substrate 1 to be processed is rectangular, and the longitudinal direction of the band-shaped electrode 4 is
The side 3a is selected to be parallel, the direction in which the piles of the rubbing roller 2 are arranged in parallel and the rotation axis 8 are selected to be parallel, and the side 3a at which rubbing is started and the rotation axis 8 are selected to have a predetermined angle α. . Since the above-described step is formed on the surface of the substrate 1 to be processed, as shown in FIG. 11B, the piles 14a, 14b , 14c abut one by one sequentially. In addition, the pile 14 extends from the side 25b facing the side 25a.
a, 14b, and 14c are sequentially separated one by one. As a result, the bristle tips of the pile 14 are disturbed, and the rubbing direction of the electrode 4 is disturbed between the central portion, the peripheral portion where the rubbing process is started, and the peripheral portion where the rubbing process is completed. It will be. As described above, since the level difference tends to be large, the disturbance in the rubbing direction becomes remarkable.

In a liquid crystal display device having an alignment film subjected to such a rubbing process, the alignment direction of liquid crystal molecules is disturbed and the twist angle γ is disturbed in a pixel region where electrodes of one and the other substrate members overlap each other. It will be. In particular, the pretilt angle of the 12 o'clock side peripheral portion and the 6 o'clock side peripheral portion of the pixel becomes higher than the pretilt angle of the central portion of the pixel, and a phenomenon that transmittance increases, that is, a so-called light leakage phenomenon occurs. Note that the pretilt angle is an inclination angle formed by the major axis direction of the liquid crystal molecules with respect to the surface of the substrate member.

The pretilt angle when a display voltage is applied to the liquid crystal layer (when an ON voltage is applied) and the pretilt angle when no display voltage is applied (when an OFF voltage is applied) are defined as The greater the difference, the greater the light transmittance ratio, that is, the greater the contrast ratio. However, as described above, since the in-plane pretilt angle is disturbed, the difference in the pretilt angle between when the ON voltage is applied and when the OFF voltage is applied becomes small, and the contrast ratio is reduced.

Further, when the off-state voltage is reduced, the on-state voltage becomes relatively insufficient, and the transmittance is reduced. If the luminance of the backlight incorporated in the liquid crystal display device is increased in order to obtain a sufficient luminance with a high transmittance, there is a disadvantage that power consumption increases and continuous driving time is shortened.

A technique for reducing the disturbance in the rubbing direction is disclosed, for example, in Japanese Utility Model Laid-Open No. 2-033030. The publication relates to a technology for winding a rubbing cloth on a roller, by disposing a non-rubbing portion that is not in contact with a pile by disposing a joining end having no pile at an angle with respect to the rotation axis of the rubbing roller,
Eliminates continuous, non-uniform orientation.

Further, the present applicant has proposed another method for reducing the disturbance in the rubbing direction in Japanese Patent Application Nos. 7-229336 and 8-281151. Japanese Patent Application No. 7-
No. 229336 relates to a technique for winding a rubbing cloth around a roller in the same manner as in the above-mentioned publication. Specifically, the rubbing cloth is wound around a roller such that the direction of one pile is inclined with respect to the rotation axis of the rubbing roller. Thus, the density of the pile in contact with the substrate to be processed is increased, and the uniformity in the rubbing direction is improved. Furthermore, Japanese Patent Application No. 8-281
In No. 151, the uniformity of the rubbing direction is enhanced by keeping the amount of contact of the rubbing roller with the substrate to be processed substantially constant.

Japanese Patent Application Laid-Open No. 7-281188 discloses a technique for obtaining a stable liquid crystal alignment state having a high pretilt angle by specifying the surface roughness of a rubbing cloth of a rubbing roller. I have. JP 7
Japanese Patent Application Laid-Open No. 168186 discloses a technique for improving the uniformity of the liquid crystal alignment state by specifying the inclination angle of a pile of a rubbing cloth with respect to the cloth ground and making the direction of rubbing the substrate to be processed coincide with the inclination direction of the pile. It has been disclosed. Japanese Patent Application Laid-Open No. 22224/1990 discloses that when a substrate to be processed moves in a certain direction while being in contact with a rubbing roller, an angle between a direction perpendicular to the certain direction and a rotation axis direction of the rubbing roller, A technique for obtaining a liquid crystal alignment state with high in-plane uniformity by setting an angle in a range of ± 1 ° to ± 45 ° is disclosed.

However, none of the publications can eliminate the inconvenience caused by the positional relationship between the substrate 1 to be processed and the rubbing roller 2 as described with reference to FIG.

An object of the present invention is to provide a rubbing treatment apparatus and a rubbing treatment method capable of uniformly rubbing a stepped surface of a substrate to be treated. Another object of the present invention is to provide a rubbing cloth and a rubbing roller provided in such a rubbing treatment device. It is still another object of the present invention to provide a liquid crystal display device having an alignment film formed by a rubbing process using the rubbing device and having improved display quality.

[0024]

According to the present invention, there is provided a process comprising a plurality of strip electrodes formed on a substrate in parallel with each other, and a film to be rubbed is formed on the substrate so as to cover the strip electrodes. 2 orthogonal to each other on the surface of the film to be treated of the substrate
A rubbing cloth having piles planted at regular intervals in the direction is brought into contact with a rubbing roller wound around the roller surface, and the substrate to be processed and the rubbing roller are relatively moved to be processed. In a rubbing treatment apparatus for rubbing the film surface, an angle θ1 between one direction of the pile of the rubbing roller and the longitudinal direction of the strip electrode of the substrate to be processed is selected within a range of ± 5 °. Rubbing processing device. According to the present invention, a step is formed by the strip electrodes by selecting an angle θ1 between the direction in which the piles of the rubbing roller are arranged in parallel and the longitudinal direction of the strip electrodes of the substrate to be processed within a range of ± 5 °. On the surface of the substrate to be processed, the pile abuts almost simultaneously on one side of the convex portion forming the step, and the pile is almost simultaneously separated from the side opposite to the side, and the rubbing process is performed. Therefore, the disorder of the pile tips is reduced, and the in-plane uniformity in the rubbing direction is improved. Rubbing treatment can be performed on any of the pair of substrate members constituting the liquid crystal display device under the above conditions to improve the uniformity.

According to the present invention, there is also provided a rubbing roller provided on the substrate such that a longitudinal direction thereof is parallel to one side of the substrate, the rubbing direction being a direction orthogonal to the one parallel direction of the pile of the rubbing roller. An angle θ2 between the direction and the longitudinal direction of the strip electrode is selected in a range of 10 ° or more and 60 ° or less. According to the present invention, the angle θ2 between the rubbing direction, which is a direction orthogonal to the direction in which the piles of the rubbing rollers are arranged, and the longitudinal direction of the strip electrode is selected within a range of 10 ° or more and 60 ° or less. The pile is abutted / separated almost simultaneously with one side of the convex portion forming the step of the substrate, and the pile is rubbed. Therefore, the disorder of the pile tips is reduced, and the in-plane uniformity in the rubbing direction is improved. Such a condition is suitable for an STN liquid crystal display device.

Further, according to the present invention, the angle θ3 between the rotation axis direction of the rubbing roller and the one side-by-side direction of the pile is
It is characterized by being selected in the range of 10 ° or more and 60 ° or less. According to the present invention, the angle θ3 between the rotation axis direction of the rubbing roller and the direction in which the piles are arranged in parallel is 10 ° or more and 60 ° or more.
By selecting the following range, the pile abuts on one side of the convex portion forming the step of the substrate to be processed almost simultaneously /
The rubbing treatment is performed by separating. Therefore, the disorder of the pile tips is reduced, and the in-plane uniformity in the rubbing direction is improved. Such a condition is suitable for an STN liquid crystal display device.

According to the present invention, there is also provided a rubbing cloth having a rectangular shape, wherein the pile is planted at intervals having a periodicity in two directions perpendicular to each other. (1) A rubbing cloth characterized in that an angle θ4 formed between the juxtaposed direction and one side of the rubbing cloth is selected in a range of 10 ° or more and 60 ° or less. According to the present invention, such a rubbing cloth can be wound around a roller to form a rubbing roller. Using the rubbing roller, disturbance of a pile tip can be reduced, and in-plane uniformity can be improved. Rubbing treatment can be performed.

The present invention is also directed to a rubbing roller, wherein a rubbing cloth having piles planted at intervals having a periodicity in two directions perpendicular to each other is wound on a roller surface. Is a rectangle, and an angle θ4 between one side of the pile and one side of the rubbing cloth is selected in a range of 10 ° or more and 60 ° or less, and the one side of the rubbing cloth is wound in parallel with the rotation axis direction of the roller. It is a rubbing roller characterized by being worn. According to the present invention, using such a rubbing roller, turbulence of pile tips can be reduced, and rubbing treatment with improved in-plane uniformity can be performed.

The present invention is also directed to a rubbing cloth wound on a rubbing roller wound on a roller surface, the rubbing cloth having piles planted at intervals having periodicity in two directions orthogonal to each other. Is a rectangular band shape, one side of the pile and one side of the rubbing cloth are selected in parallel, and the one side of the rubbing cloth is spirally wound in a direction inclined with respect to the rotation axis direction of the roller. A rubbing roller. According to the present invention, using such a rubbing roller, turbulence of pile tips can be reduced, and rubbing treatment with improved in-plane uniformity can be performed.

The present invention also provides a step of forming a plurality of strip electrodes on a substrate in parallel with each other, a step of forming a film to be rubbed on the substrate so as to cover the strip electrodes, Rubbing the film surface using a rubbing apparatus as described above. According to the present invention, on the surface of the processing target substrate on which the step is formed by the band-shaped electrode, the pile abuts almost simultaneously on one side of the convex portion forming the step, and the pile is formed from the side opposite to the side. The rubbing process is performed almost simultaneously. Therefore, the disorder of the pile tips is reduced, and the in-plane uniformity in the rubbing direction is improved.

According to the present invention, in a liquid crystal display device in which a liquid crystal is interposed between a pair of substrate members, at least one of which has a light-transmitting property, at least one of the pair of substrate members has the above-mentioned structure. A liquid crystal display device having an alignment film rubbed using the rubbing device described above. According to the present invention,
On the surface of the substrate on which the step is formed by the strip-shaped electrodes, the pile abuts almost simultaneously on one side of the convex portion forming the step, and the pile is almost simultaneously separated from the side opposite to the side, and rubbing is performed. It is processed. Therefore, the disorder of the pile tips is reduced, and the in-plane uniformity in the rubbing direction is improved. In a liquid crystal display device having an alignment film subjected to such a rubbing process, the uniformity of alignment of liquid crystal molecules in the pixel region is improved, and the uniformity of twist angle is improved. Further, the occurrence of a light leakage phenomenon in which the pretilt angle in the pixel becomes substantially equal and the transmittance partially increases is suppressed. Therefore, the uniformity of the pretilt angle in the pixel is improved, and the difference in the pretilt angle between when the ON voltage is applied and when the OFF voltage is applied has a sufficiently large value, and a high contrast ratio can be obtained. Since a high contrast ratio can be obtained, it is not necessary to increase the brightness of a backlight incorporated in the liquid crystal display device, and a liquid crystal display device with low power consumption and long continuous drive time can be realized.

Further, according to the present invention, the liquid crystal interposed between the substrate members is such that the liquid crystal molecules are between 210 ° and 260 ° between the substrate members.
It is characterized in that it is an STN liquid crystal that is twist-oriented in the range of °. According to the present invention, an excellent display quality can be obtained in an STN-type liquid crystal display device that is easily affected by the liquid crystal alignment state with respect to the display quality.

[0033]

FIG. 1 is a plan view showing a rubbing apparatus according to a first embodiment of the present invention. here,
An example in which a pair of substrate members included in a liquid crystal display device are formed using the rubbing device will be described. FIG. 1 (a)
FIG. 1 shows a state of a rubbing process on a substrate 51a to be processed, which is one substrate member of a pair of substrate members.
(B) is a diagram showing a state of a rubbing process on a substrate to be processed 51b, which is the other substrate member.

The substrate to be processed 51a is formed by forming an electrode 54a for display on one surface of a substrate 53a, and forming a film to be processed 55a made of a resin such as polyimide over the electrode 54a. The rubbing roller 52 is configured by winding a rubbing cloth 57 around the surface of a roller 56 with a double-sided adhesive sheet or the like.

Specifically, the rubbing roller 52 is brought into contact with the surface of the film to be processed 55a at a constant pressure, and the rubbing roller 52 is moved in a predetermined direction 5 around the rotation shaft 58.
9, the substrate 51a and the rubbing roller 52 are relatively moved while rotating at a predetermined speed, for example, the rubbing roller 52 is moved in the direction 60 to rub the surface of the film 55a in a certain direction. Formed by

The substrate to be processed 51b has a display electrode 54b on one surface of the substrate 53b, similarly to the substrate to be processed 51a.
Is formed, and a film to be processed 55b is formed so as to cover the electrode 54b. The alignment film is formed by rubbing the surface of the film to be processed 55b in the same manner as described above.

Here, the following conditions are selected for a liquid crystal display device that performs dot matrix display. The substrates 53a and 53b of the substrates to be processed 51a and 51b are rectangular.
The electrodes 54a and 54b are strip-shaped, and the longitudinal direction 62a of the electrode 54a and one side 53c of the substrate 53a are selected in parallel,
The longitudinal direction 62b of the electrode 54b and one side 53d of the substrate 53b
And are selected in parallel. The rubbing process is performed on the sides 53c, 5
It starts from 3d. The rubbing cloth 57 of the rubbing roller 52 is a cloth in which piles are planted as shown in FIG.
And the rotation shaft 58 are selected in parallel.

In the rubbing process of the substrate 51a, the piles of the rubbing roller 52 are arranged in one parallel direction.
3 and the longitudinal direction 6 of the strip electrode 54a of the substrate 51a to be processed.
The angle with 2a is selected as a predetermined angle θ1. At the time of the rubbing treatment of the substrate 51b, an angle between the one parallel direction 63 and the longitudinal direction 62b of the strip electrode 54b of the substrate 51b is selected to be a predetermined angle θ1.
The angle θ1 is preferably selected within a range of 5 °. In the present embodiment, the angle θ1 is ± 5 °.

The rubbing directions 61a and 61a are perpendicular to the direction 63 in which the piles of the rubbing rollers 52 are arranged.
b. Here, the direction is orthogonal to the rotation axis 58.

In the present embodiment, the first juxtaposition direction 6
3. An angle between a rubbing direction 61a, which is a direction orthogonal to 3, and a longitudinal direction 62a of the strip-shaped electrode 54a;
The rubbing direction 61b which is a direction orthogonal to the juxtaposition direction 63
And the longitudinal direction 62b of the strip-shaped electrode 54b,
Both are selected at a predetermined angle θ2. The angle θ2 is preferably selected in a range from 10 ° to 60 °.

In the present embodiment, the rubbing cloth 57 is
A cloth made of rayon fiber having a trade name of YA-18R manufactured by Yoshikawa Kako was used. The direction with the highest contrast ratio is 1
A rubbing process was performed to create a liquid crystal display device with a viewing angle of 0:30. Also, the electrodes 54a, 54b
Was 3000 mm thick, and the size of the display screen was 13.8 inches with a diagonal length of 35 cm.

FIG. 2 shows a pair of substrate members 65a, 65a on each of which an alignment film has been formed using the rubbing apparatus as described above.
FIG. 5 is a plan view for explaining an STN-type liquid crystal display device 64 including the liquid crystal display device 5b. The respective alignment films are opposed to each other so that the rubbing directions 61a and 61b form an angle γ1, and the substrates are bonded to each other with a liquid crystal interposed between the substrate members 65a and 65b. Angle γ
1 is selected in the range of 180 ° or more, preferably 210 °
° to 260 °. In the present embodiment, 260
° selected. Note that the angle γ1 is different from the substrate members 65a, 65
b is the twist angle (twist angle) of the liquid crystal molecules interposed between the substrate members.

In this embodiment, the pair of substrate members 65
A color STN type liquid crystal display device having a cell thickness of 6 μm, which is an interval between a and 65b. After injecting the liquid crystal, it was combined with a polarizing plate and a retardation plate.

Next, the result of comparing the display quality between the liquid crystal display device of the first embodiment and the liquid crystal display device of the prior art will be described. The liquid crystal display device of the related art is a liquid crystal display device having an alignment film formed using a rubbing treatment device as shown in FIG. The twist angle was set, and the cell thickness was set to 6 μm. The display quality was evaluated by observing the liquid crystal display device in a lighting state with a microscope. The liquid crystal display device of the first embodiment has less light leakage at the 12 o'clock direction peripheral portion and the 6 o'clock direction peripheral portion of the pixel than the liquid crystal display device of the related art, and has high in-plane uniformity. It was confirmed that it was lit.

Further, a predetermined drive circuit was connected to evaluate the electro-optical characteristics. Specifically, the luminance is measured by supplying an on / off (lighting / non-lighting) signal to the liquid crystal display device using a luminance measuring device BM7 manufactured by Topcon Corporation, and measuring the luminance from the luminance ratio to a direction directly above the display surface. Was determined. With the liquid crystal display device of the first embodiment, a contrast ratio of 37: 1 was obtained, compared to 29.5: 1 of the liquid crystal display device of the prior art. This means that the contrast ratio has been improved by about 25%.

Further, when the transmittance of the backlight light to the liquid crystal display device was obtained, it was found that the transmittance of the liquid crystal display device of the first embodiment was 4.5%, compared with the conventional liquid crystal display device of 3.4%. Obtained. This means that the transmittance was improved by about 30%.

FIG. 3 is a plan view showing a rubbing apparatus according to a second embodiment of the present invention. FIG. 3A shows a state of a rubbing process on the substrate to be processed 51a.
FIG. 3B is a diagram illustrating a state of a rubbing process on the substrate to be processed 51b. The rubbing roller 71 used in the second embodiment is configured by winding a rubbing cloth 73 on the surface of a roller 72 with a double-sided adhesive sheet or the like. As in the first embodiment, the alignment films are films to be processed 55a and 55b.
The rubbing roller 71 is brought into contact with the surface of the
While rotating the rubbing roller 71 at a predetermined speed in a predetermined direction 59 about the rotation shaft 58,
a, 51b and the rubbing roller 71 are relatively moved, for example, the rubbing roller 71 is moved in the direction 60, and the surfaces of the processing target films 55a, 55b are rubbed in a certain direction.

Here, in the liquid crystal display device which performs dot matrix display, the following conditions are selected. The shapes of the substrates 53a and 53b of the substrates to be processed 51a and 51b, and the electrodes 54
The shapes of a and 54b and the positional relationship between them are the same as in the first embodiment. Rubbing cloth 73 of rubbing roller 71
Is a cloth in which a pile as shown in FIG. 8B is planted in the same manner as in the prior art, and an angle between the one juxtaposition direction 74 of the pile and the rotation shaft 58 is selected as a predetermined angle θ3. The angle θ3 is preferably selected in a range from 10 ° to 60 °.

In the rubbing process of the substrate 51a to be processed, the piles of the rubbing roller 71 are arranged in one direction.
4 and the longitudinal direction 6 of the strip electrode 54a of the substrate 51a to be processed.
The angle with 2a is selected as a predetermined angle θ1. At the time of the rubbing process of the substrate 51b, an angle between the one juxtaposition direction 74 and the longitudinal direction 62b of the strip electrode 54b of the substrate 51b is selected to be a predetermined angle θ1.
The angle θ1 is preferably selected within a range of ± 5 °.
In the present embodiment, the angle θ1 is set to 5 °.

The angle formed between the rotation shaft 58 of the rubbing roller 71 and the side 53c of the substrate 53a,
The angle between the substrate and the side 53d of the substrate 53b is selected to be a predetermined angle. In this embodiment, the angle is set to 40 °.

The direction perpendicular to the one arranging direction 74 of the piles of the rubbing rollers 71 is the rubbing direction 75a, 75.
b. For example, the direction is parallel to the movement direction 60.

In the present embodiment, the rubbing cloth 73 is
The trade name YA-19R manufactured by Yoshikawa Kako was used. In addition, rubbing processing was performed to create a liquid crystal display device in which the direction with the highest contrast ratio was set to the viewing angle direction at 12:00. The thickness of the electrodes 54a and 54b was 3000 °, and the size of the display screen was a 13.8 type with a diagonal length of 35 cm.

By using the rubbing device described in the second embodiment to form a pair of substrate members 65a and 65b, an STN-type liquid crystal display device 64 as shown in FIG. 2 can be realized. In this embodiment, a liquid crystal display device in which the angle γ1 was selected to 260 ° and the cell thickness was 6.7 μm was prepared.

The torque current when rotating the rubbing roller 71 of the rubbing processing apparatus of the second embodiment was smaller than that of the conventional rubbing processing apparatus and was stable. This is because the rubbing roller 71 has a single pile
And the strip electrodes 54a, 54 of the substrates 51a, 51b to be processed.
b is ± 5 ° with respect to the longitudinal direction 62a, 62b.
It is probable that the selection in the following range caused the hair tips of the pile to come into contact with the edges of the electrodes 54a and 54b almost at the same time and to come apart almost at the same time, thereby reducing the variation of the hair tips. Such effects can be obtained also in the rubbing processing device of the first embodiment.

Next, the result of comparing the display quality between the liquid crystal display device of the second embodiment and the liquid crystal display device of the prior art will be described. The conventional liquid crystal display device is the same as that described in the first embodiment. The display quality is the first
Evaluation was performed in the same manner as in the embodiment. The liquid crystal display device of the second embodiment, like the liquid crystal display device of the first embodiment, has light leakage at the 12 o'clock direction peripheral edge and the 6 o'clock direction peripheral edge of the pixel as compared with the conventional liquid crystal display device. It was confirmed that lighting was performed with high uniformity in the plane.

The electro-optical characteristics were evaluated in the same manner as in the first embodiment. The contrast ratio in the directly above direction was 33.7: 1 in the liquid crystal display device of the second embodiment, compared to 33.7: 1 in the liquid crystal display device of the related art. This means that the contrast ratio has been improved by about 14%.

Further, the transmittance of the backlight to the liquid crystal display device was 4.3% in the liquid crystal display device of the second embodiment, compared with 3.8% of the liquid crystal display device of the prior art. . This means that the transmittance was improved by about 13%.

FIG. 4 is a plan view showing a cloth 81 in which a predetermined area is cut and used as a rubbing cloth 73 for the rubbing roller 71. FIGS. 5A and 5B are perspective views showing a state in which the cut rubbing cloth is wound around the roller 72. FIG.

The cloth 81 for the rubbing cloth is the same as the cloth used in the conventional rubbing apparatus, and specifically, as shown in FIG. A pile 14 in which several tens of filaments are bundled is knitted, and the pile implantation length of each pile 14 is uniform. That is, it is a cloth on which the piles 14 are planted at intervals having periodicity in two directions orthogonal to each other.

Two types of setting are possible for the cutting area of the cloth 81, one of which is one side 84 of the cloth 81, one side 84 parallel to one pile arrangement direction, and a rectangular cutting area 8.
The two sides 85 are set so as to form a predetermined angle θ4. That is, the angle θ with respect to one pile
A region 82 having one side 85 forming 4 is cut. In this case, it is preferable to select the angle θ4 in a range from 10 ° to 60 °. The angle θ4 is specifically set to 45 ° in the second embodiment. As shown in FIG. 5A, the rubbing cloth 73a formed by cutting the area 82 is set so that one side 85 and the rotation shaft 58 are parallel to each other.
It is wound around 2. That is, the rubbing cloth 73a is wound so that the one side 85 coincides with the width direction of the roller 72.

On the other hand, the angle θ4 is set to 0 °, and one side 84 of the cloth 81 is set to be parallel to one side 86 of the band-shaped rectangular cutting area 83 in the longitudinal direction. That is, an area 83 having one side 86 parallel to one pile arrangement direction is cut. As shown in FIG. 5B, the rubbing cloth 73b formed by cutting the region 83 is spirally wound with one side 86 of the rubbing cloth 73b inclined with respect to the direction of the rotation shaft 58 of the roller 72. Be worn.

In the first embodiment, the cutting area is set such that the one side 84 of the cloth 81 and the one side of the rectangular cutting area are parallel with the angle θ4 being 0 °. That is, a region having one side parallel to the one arrangement direction of the pile is cut. The rubbing cloth cut in this manner is wound around the roller 56 in the same manner as in FIG. By cutting the fabric 81 in a direction parallel or orthogonal to the direction in which the piles are arranged, the use efficiency of the fabric 81 can be increased.

FIG. 6 is an enlarged view of the rubbing process of the first and second embodiments. FIG. 6A is a plan view, and FIG. 6B is a perspective view. Although a step is formed on the surface of the processing target substrate 51 by the electrode 54,
The substrate 53 is rectangular and has a longitudinal direction 62
And one side 53c of the substrate 53 are parallel to each other, and the angle θ1 between the one parallel direction 63, 74 of the piles of the rubbing rollers 52, 71 and the longitudinal direction 62 of the strip electrode 54 is an angle within ± 5 °. Therefore, at the time of rubbing, as shown in FIG. 6B, the piles 88a, 88b and 88c abut at one time on one side 87a of the convex portion forming a step.
Also, a pile 88 is formed from a side 87b facing the side 87a.
a, 88b and 88c are almost simultaneously separated.

Thus, regardless of the size of the step,
The disturbance of the hair tips of the pile 88 is reduced. Therefore, in the surface of the electrode 54, disturbance in the rubbing direction between the center portion, the peripheral portion on the side where the rubbing process is started, and the peripheral portion on the side where the rubbing process is completed is suppressed.

In the liquid crystal display device having the alignment film subjected to such a rubbing process, the uniformity of the alignment of the liquid crystal molecules in the pixel region is improved, and the uniformity of the twist angle γ1 is improved. In addition, the pretilt angles of the 12 o'clock side peripheral edge and the 6 o'clock side peripheral edge of the pixel are substantially the same as the pretilt angle of the central portion of the pixel, thereby suppressing the occurrence of a light leakage phenomenon that partially increases the transmittance. Is done. Further, since the uniformity of the pretilt angle in the plane is increased, the difference in the pretilt angle between when the ON voltage is applied and when the OFF voltage is applied is not reduced, and a high contrast ratio can be maintained. Further, when the off-state voltage is to be reduced, sufficient luminance can be obtained without increasing the luminance of the backlight, so that a liquid crystal display device with low power consumption and long continuous driving time can be realized. it can. Further, in a STN type liquid crystal display device in which the display quality is easily affected by the liquid crystal alignment state, excellent display quality can be obtained.

As described above, in the first and second embodiments, since the angle θ1 is selected within the range of ± 5 °, the disturbance of the pile tips is reduced, and the in-plane uniformity in the rubbing direction is improved. . Rubbing treatment can be performed on any of the pair of substrate members constituting the liquid crystal display device under the above conditions to improve the uniformity.

In the first embodiment, the angle θ2 is set to 10 °
Since the angle is selected within the range of 60 ° or less, a substrate member for an STN-type liquid crystal display device that can obtain the above-described effects can be manufactured. Also, by selecting θ3 in the range of 10 ° or more and 60 ° or less in the second embodiment, a substrate member for an STN liquid crystal display device that can obtain the above-described effects can be produced.

In the second embodiment, the rubbing cloth 73 cut with the angle θ4 selected from the range of 10 ° or more and 60 ° or less.
The rubbing roller 71 can be formed by winding a around the roller 72. At this time, by wrapping the rubbing cloth 73a so that the one side 85 of the rubbing cloth 73a coincides with the width direction of the roller 72, a rubbing roller having the above effect can be produced. In addition, one side of the pile 74 and one side 86 of the rubbing cloth 73b are selected in parallel, and the one side 86 of the rubbing cloth 73b is inclined with respect to the direction of the rotation shaft 58 of the roller 72 and spirally wound. A rubbing roller having the same effect can be produced.

A plurality of strip-shaped electrodes 5 are provided on the substrate 53.
4 are formed in parallel with each other, a target film 55 to be rubbed is formed on the substrate 53 so as to cover the strip electrodes 54, and the surface of the target film 55 is rubbed using the above-described rubbing apparatus. A rubbing method for rubbing is also included in the scope of the present invention.

[0070]

As described above, according to the present invention, the angle .theta.1 between the direction in which the piles of the rubbing roller are arranged and the longitudinal direction of the strip electrode of the substrate to be processed is selected within the range of. +-. 5.degree. The rubbing treatment can be performed by bringing the surface of the substrate to be processed into and out of contact with the pile almost simultaneously. Therefore, disturbance of the pile tips is reduced, and in-plane uniformity in the rubbing direction is improved.

Further, according to the present invention, the angle θ2 between the rubbing direction, which is a direction orthogonal to one direction in which the piles of the rubbing rollers are arranged, and the longitudinal direction of the strip electrode is 10 ° or more and 60 ° or more.
The same effect can be obtained even if it is selected in the range below °.

According to the present invention, the angle .theta.3 between the direction of the rotation axis of the rubbing roller and the direction in which the piles are arranged in parallel is 10 degrees.
The same effect can be obtained even if it is selected within the range of not less than 60 ° and not more than 60 °.

Further, according to the present invention, the angle θ4 formed between the one side of the pile and one side of the rubbing cloth is 10 ° or more and 60 ° or more.
The rubbing cloth selected in the range of not more than ° is wound around a roller to form a rubbing roller, and a rubbing treatment can be performed using the rubbing roller to obtain the above-described effects.

Further, according to the present invention, the rectangular rubbing cloth is formed so that the angle θ4 between the one side of the pile and one side of the rubbing cloth is in the range of 10 ° to 60 °, and the one side of the rubbing cloth is a roller. A rubbing process that achieves the above-described effects can be performed using a rubbing roller wound so as to match the width direction.

Further, according to the present invention, the belt-shaped rubbing cloth is set so that one side of the pile is parallel to one side of the rubbing cloth, and the one side of the rubbing cloth is inclined with respect to the direction of the rotation axis of the roller. Using a rubbing roller wound spirally, a rubbing treatment that can achieve the above-described effects can be performed.

Further, according to the present invention, it is possible to provide a rubbing method capable of obtaining the above-described effects.

According to the present invention, in a liquid crystal display device having an alignment film rubbed by using the rubbing device as described above, the uniformity of the alignment direction of liquid crystal molecules in a pixel region is improved. The uniformity of the twist angle is improved. Also, the pretilt angles in the pixels become almost equal,
The occurrence of the light leakage phenomenon that partially increases the transmittance is suppressed. Since the uniformity of the pretilt angle in the pixel is improved,
The difference in pretilt angle between when the on voltage is applied and when the off voltage is applied has a sufficiently large value, and a high contrast ratio can be obtained. Since a high contrast ratio can be obtained, it is not necessary to increase the luminance of a backlight incorporated in the liquid crystal display device, and a liquid crystal display device with low power consumption and long driving time can be realized.

Further, according to the present invention, an excellent display quality can be obtained in an STN type liquid crystal display device in which the display quality is easily affected by the liquid crystal alignment state.

[Brief description of the drawings]

FIG. 1 is a plan view showing a rubbing apparatus according to a first embodiment of the present invention.

FIG. 2 shows an S including a pair of substrate members 65a and 65b on which an alignment film is formed by using the rubbing apparatus of the first embodiment.
FIG. 3 is a plan view for explaining a TN-type liquid crystal display device 64.

FIG. 3 is a plan view showing a rubbing apparatus according to a second embodiment of the present invention.

FIG. 4 is a plan view showing a cloth 81 in which a predetermined area is cut and used as a rubbing cloth 73 for a rubbing roller 71.

FIG. 5: Roller 7 is applied to cut rubbing cloths 73a and 73b.
It is a perspective view which shows a mode that it winds around.

FIGS. 6A and 6B are enlarged views of a rubbing process according to the first and second embodiments. FIG. 6A is a plan view, and FIG. 6B is a perspective view.

FIG. 7 is a plan view showing a substrate to be processed 1 and a rubbing roller 2 for explaining a rubbing process using a rubbing apparatus as a conventional technique.

FIG. 8A is a plan view showing a cloth 12 for the rubbing cloth 7, and FIG. 8B is an enlarged perspective view showing the cloth 12. FIG.

FIG. 9 is a plan view for explaining an STN-type liquid crystal display device 16 having an alignment film formed by using a conventional rubbing device.

FIG. 10 is an enlarged sectional view showing a state during a rubbing process.

FIG. 11 is an enlarged view showing a state at the time of a rubbing process according to the related art, and FIG. 11 (a) is a plan view and FIG.
(B) is a perspective view.

[Explanation of symbols]

 51, 51a, 51b Substrate to be processed 52, 71 Rubbing roller 53, 53a, 53b Substrate 53c, 53d One side of substrate 54, 54a, 54b Electrode 55, 55a, 55b Film to be processed 56, 72 Roller 57, 73, 73a, 73b Rubbing cloth 58 Rotation axis 59 Rotation direction 60 Movement direction 61a, 61b, 75a, 75b Rubbing direction 62a, 62b Longitudinal direction of electrode 63, 74 Pile juxtaposition direction 64 Liquid crystal display device 65a, 65b Substrate member 81 Fabric 82, 83 Cutting Area 84 One side of the fabric 85, 86 One side of the rubbing cloth 87a, 87b One side of the convex portion forming a step 88, 88a, 88b, 88c Pile

Claims (9)

[Claims] 1. A plurality of strip-shaped electrodes are formed on a substrate in parallel with each other, and a film to be rubbed is formed on the substrate so as to cover the strip-shaped electrodes. A rubbing roller having a pile planted at intervals with periodicity in two directions perpendicular to each other is brought into contact with a rubbing roller wound around the roller surface,
In a rubbing processing apparatus for rubbing a surface of a film to be processed by relatively moving a substrate to be processed and a rubbing roller, a direction of one pile of rubbing rollers and a longitudinal direction of a strip electrode of the substrate to be processed are formed. A rubbing treatment device, wherein the angle θ1 is selected within a range of ± 5 °. 2. A rubbing direction which is provided on the substrate such that a longitudinal direction thereof is parallel to one side of the substrate, and a rubbing direction which is a direction orthogonal to the one parallel direction of piles of rubbing rollers. 2. The rubbing treatment apparatus according to claim 1, wherein an angle [theta] 2 between the strip electrode and the longitudinal direction is selected in a range of 10 [deg.] To 60 [deg.]. 3. An angle θ3 between the rotation axis direction of the rubbing roller and the one juxtaposed direction of the pile is 10 ° or more and 6 ° or more.
The rubbing treatment device according to claim 1, wherein the rubbing treatment device is selected within a range of 0 ° or less. 4. A rectangular rubbing cloth wound on a roller surface, wherein piles are planted at intervals having a periodicity in two directions orthogonal to each other, wherein the piles are arranged in parallel. A rubbing cloth, wherein an angle θ4 between the direction and one side of the rubbing cloth is selected in a range of 10 ° or more and 60 ° or less. 5. A rubbing cloth having piles planted at intervals having a periodicity in two directions orthogonal to each other,
In the rubbing roller wound around the roller surface, the rubbing cloth to be wound is rectangular, and the angle θ4 between the one side of the pile and one side of the rubbing cloth is selected from a range of 10 ° to 60 °. A rubbing roller, wherein the one side of the rubbing cloth is wound in parallel with a rotation axis direction of the roller. 6. A rubbing cloth having piles planted at intervals having periodicity in two directions orthogonal to each other,
In the rubbing roller wound on the roller surface, the rubbing cloth to be wound has a rectangular band shape, and one side of the pile and one side of the rubbing cloth are selected in parallel, and the one side of the rubbing cloth is a roller. A rubbing roller, which is wound spirally inclining with respect to the rotation axis direction of the rubbing roller. 7. A step of forming a plurality of strip-shaped electrodes on a substrate in parallel with each other, a step of forming a film to be rubbed on the substrate so as to cover the strip-shaped electrodes, and A rubbing process using the rubbing device according to any one of claims 1 to 3. 8. A liquid crystal display device in which a liquid crystal is interposed between a pair of substrate members, at least one of which has translucency, wherein at least one of the pair of substrate members is a substrate member. 3. A liquid crystal display device having an alignment film rubbed by using the rubbing device according to any one of 3. 9. The liquid crystal interposed between the substrate members is an STN liquid crystal in which liquid crystal molecules are twist-aligned in a range of 210 ° to 260 ° between the substrate members.
The liquid crystal display device as described in the above.