JP2011053250A - Rubbing processing device, rubbing processing method, and method for manufacturing liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbing processing device and a rubbing processing method capable of suppressing the generation of rubbing stripes without changing viewing angle characteristics of a vertical alignment liquid crystal display element, and to provide a method for manufacturing the liquid crystal display element using the rubbing processing method. <P>SOLUTION: The rubbing processing device 1 includes: a stage 10 on which a substrate 30 having an alignment layer formed thereon is placed; and a rubbing roll 20 disposed so that it can come into contact with the alignment layer. The rubbing roll 20 rotationally moves in parallel to the surface of the substrate 30. In a plane parallel to the surface of the substrate 30, regarding a tilt angle &theta;<SB>1</SB>of the substrate 30 with respect to a direction vertical to the advancing direction of the rubbing roll 20 and an angle &theta;<SB>2</SB>formed by the advancing direction of the rubbing roll 20 and the direction vertical to the rotary shaft of the rubbing roll 20, &theta;<SB>1</SB>=&theta;<SB>2</SB>, and &theta;<SB>2</SB>&ne;0 are established. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a rubbing treatment apparatus that performs a rubbing treatment on an alignment film formed on a substrate of a liquid crystal display element, a rubbing treatment method, and a method for manufacturing a liquid crystal display element using the rubbing treatment method.

  Conventionally, in order to align liquid crystal molecules in a specific direction along an alignment film of a liquid crystal display element, an electrode and an alignment film are formed while rotating a rubbing roll in which a cloth such as rayon or cotton is wound around a cylindrical roll. A rubbing process is performed in which the substrate is rubbed in one direction while advancing on the formed substrate. In the rubbing process of the vertical alignment liquid crystal display element, the rubbing process is performed in such a direction that the liquid crystal molecules at the alignment film interface on one substrate side and the liquid crystal molecules at the alignment film interface on the other substrate side are parallel to each other. Therefore, the rubbing process is generally performed so that the horizontal direction of the substrate and the substrate traveling axis are parallel, and the traveling direction of the rubbing roll and the direction perpendicular to the rotating shaft of the rubbing roll (rubbing direction) are the same direction. Is.

  However, the rubbing process is characterized by rubbing with a woven fabric made of fibers having a diameter of several tens of μm in manufacturing a vertically aligned liquid crystal display element, and depending on the rubbing place (for example, glass, electrode, alignment film) on the substrate. The fiber has different wrinkles. And, in addition to the difference in the crease, the rubbing direction of the rubbing roll and the traveling direction are the same direction. As a result, streaks in the rubbing direction become more prominent (longer) depending on the location, and the display quality of the liquid crystal display element is significantly deteriorated. Cause defects. With respect to this problem, in the rubbing method described in Patent Document 1, the rubbing streak is intentionally divided into microscopic pieces by tilting the traveling direction of the rubbing roll from the direction perpendicular to the rotation axis of the rubbing roll. suppress.

JP 2002-6322 A

  However, in the rubbing method described in Patent Document 1, by shifting the traveling direction of the rubbing roll from the direction perpendicular to the rotation axis of the rubbing roll, the viewing angle direction is also shifted by the amount shifted, and the viewing angle characteristics of the liquid crystal display element are reduced. It will change.

  The present invention has been made in view of such problems, and a rubbing processing apparatus, a rubbing processing method, and the rubbing processing capable of suppressing the occurrence of rubbing lines without changing the viewing angle characteristics of a vertically aligned liquid crystal display element. An object of the present invention is to provide a method for producing a liquid crystal display element using the method.

In order to achieve the above object, a rubbing treatment apparatus according to the first aspect of the present invention provides:
Substrate transport means for moving a substrate having an alignment film on its surface in parallel with the surface;
A rubbing roll disposed so as to be in contact with the alignment film;
Rubbing roll moving means for moving the rubbing roll parallel to the surface of the substrate;
A rubbing roll rotating means for rotating the rubbing roll,
In a plane parallel to the surface of the substrate, an inclination angle θ _{1 of the} substrate with respect to a direction perpendicular to the traveling direction of the rubbing roll, and a traveling direction of the rubbing roll and a direction perpendicular to the rotation axis of the rubbing roll are formed. The angle θ ₂ is characterized in that θ ₁ = θ ₂ and θ ₂ ≠ 0 °.

In order to achieve the above object, a rubbing treatment method according to a second aspect of the present invention includes:
A rubbing treatment method for performing a rubbing treatment by bringing a rotating rubbing roll into contact with the alignment film with respect to a substrate having an alignment film on the surface,
In a plane parallel to the surface of the substrate, an inclination angle θ _{1 of the} substrate with respect to a direction perpendicular to the traveling direction of the rubbing roll, and a traveling direction of the rubbing roll and a direction perpendicular to the rotation axis of the rubbing roll are formed. The angle θ ₂ is characterized in that θ ₁ = θ ₂ and θ ₂ ≠ 0 °.

In order to achieve the above object, a method for manufacturing a liquid crystal display element according to the third aspect of the present invention includes:
Performing a rubbing treatment on the alignment film formed on the surface of the substrate by the rubbing treatment method as described above;
Two substrates having the alignment film subjected to the rubbing treatment are opposed to each other with the alignment film facing inward so that the rubbing directions are parallel and opposite to each other, and liquid crystal is sealed between the two substrates. And steps to
Attaching a polarizing plate to the surface of the two substrates opposite to the surface on which the alignment film is formed.

  According to the present invention, a rubbing processing apparatus, a rubbing processing method, and a method for manufacturing a liquid crystal display element using the rubbing processing method capable of suppressing the occurrence of rubbing lines without changing the viewing angle characteristics of the vertically aligned liquid crystal display element Can provide.

(A) is a perspective view which shows schematic structure of the rubbing processing apparatus which concerns on embodiment of this invention, (b) is a figure which shows arrangement | positioning of the board | substrate and rubbing roll which concern on embodiment of this invention. (A)-(c) is a figure which shows arrangement | positioning of the board | substrate and rubbing roll in predetermined (theta) ₁ , (theta) ₂ . It is a figure which shows the light absorption direction of the polarizing plate in each arrangement | positioning of Fig.2 (a)-(c), the direction in which a liquid crystal molecule falls, and the rubbing direction. It is a figure which shows the microscope picture of the vertical liquid crystal display element in each arrangement | positioning of Fig.2 (a)-(c). It is a figure which shows the contrast viewing angle characteristic of the vertical liquid crystal display element in each arrangement | positioning of Fig.2 (a)-(c).

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a diagram showing a schematic configuration of a rubbing processing apparatus 1 according to the present embodiment. As shown in FIG. 1A, the rubbing processing apparatus 1 according to this embodiment includes a stage 10 on which a substrate 30 is placed and a rubbing roll 20. As shown in FIG. 1B, in the mounting surface of the stage 10, the traveling direction of the substrate 30 is the positive direction of the X axis, and the traveling direction of the rubbing roll 20 is the positive direction of the Y axis perpendicular to the X axis. The XY coordinate system is defined as follows.

The stage 10 moves the substrate 30 placed on the placement surface in parallel with the surface of the substrate 30 in the positive direction of the X axis in FIG. The stage 10 moves in the positive direction or the negative direction of the X axis, for example, when driven by a motor or the like. The mounting surface of the stage 10 is placed in a state where the substrate 30 is theta ₁ rotates with respect to the X-axis positive direction.

  The substrate 30 is formed by applying an alignment film made of polyimide on the surface of a transparent substrate made of glass or the like on which a transparent electrode is formed.

The rubbing roll 20 is configured by winding a cloth (rubbing cloth) such as rayon or cotton around a cylindrical roll body. As shown in FIG. 1A, the rubbing roll 20 has a predetermined angle θ ₂ (θ ₂ ≠ 0) with respect to the positive Y-axis direction by a motor 40 corresponding to the rubbing roll rotating means. It rotates in an inclined state (for example, 15 °). Further, the rubbing roll 20 moves in the positive or negative direction of the Y axis and is brought into contact with the substrate 30 when driven by, for example, a rubbing roll moving unit including a motor.

Next, a rubbing processing method using the rubbing processing apparatus 1 configured as described above will be described.
First, the substrate 30 is placed on the stage 10 with the side on which the alignment film is formed as the upper surface. At this time, the substrate 30 is placed so that an inclination angle θ ₁ with respect to a direction perpendicular to the traveling direction of the rubbing roll 20 (X-axis positive direction) is equal to θ ₂ (θ ₁ = θ ₂ ).

  Next, the stage 10 is moved in the X-axis positive direction so that the substrate 30 is positioned on the movement line of the rubbing roll 20 and then stopped. Further, the rubbing roll 20 is moved in the positive Y-axis direction while being driven to rotate. When the rubbing roll 20 passes over the substrate 30, the rubbing roll 20 passes while rubbing the alignment film on the surface of the substrate 30. Therefore, the alignment film is rubbed in a certain direction by a rubbing cloth provided on the outer peripheral surface of the rubbing roll 20. In addition, since the moving speed of the rubbing roll 20 is sufficiently smaller than the rotational speed of the rubbing roll 20, the rubbing direction can be regarded as a direction perpendicular to the rotational axis of the rubbing roll 20.

  The rubbing process is performed on the alignment film formed on the surface of the substrate 30 as described above. Further, the two substrates 30 having the alignment film subjected to the rubbing treatment described above are opposed to each other with the alignment film facing inward so that the rubbing directions are parallel and opposite to each other, and liquid crystal is sealed between them. A liquid crystal display element is manufactured by attaching a polarizing plate to the outer surface of 30.

  Here, the presence or absence of the occurrence of rubbing streaks on the alignment film that has been subjected to the rubbing process using the rubbing apparatus 1 configured as described above will be described in comparison with the case where a conventional rubbing apparatus is used.

2A and 2B show the positional relationship between a rubbing roll and a substrate in a conventional rubbing processing apparatus, FIG. 2A shows θ1 = θ2 = 0 °, FIG. 2B shows θ ₁ = 0 °, θ _2. = 15 °. FIG. 2C illustrates an example of an arrangement relationship between the rubbing roll 20 and the substrate 30 in the rubbing processing apparatus 1 according to this embodiment, and θ ₁ = θ ₂ = 15 °.

  Sample groups of 100 vertically aligned liquid crystal display elements that have been subjected to the rubbing process using the rubbing apparatus having the arrangement shown in FIGS. 2A to 2C are referred to as groups A, B, and C, respectively. Here, the rubbing processing method is that the rubbing roll 20 is rotated and moved in the Y-axis direction only in the arrangement of the rubbing roll 20 and the substrate 30 in each of the cases of FIGS. Are the same.

  FIG. 3 shows the light absorption direction, the liquid crystal molecule tilt direction, and the rubbing direction of the front and back polarizing plates of the vertically aligned liquid crystal display element in each group. In Group A and Group C, the relative arrangement relationship between the roller and the substrate is the same, and therefore, the light absorption direction of the polarizing plate, the direction in which the liquid crystal molecules are tilted, and the rubbing direction are represented by the same diagram.

  Table 1 below shows the rate of occurrence of rubbing stripes in groups A to C in the cases of FIGS. Here, the occurrence rate of rubbing stripes is a ratio of the total number (100) of vertically aligned liquid crystal display elements having rubbing stripes that can be visually confirmed.

From the above results, the rubbing stripe occurrence rate of group A is 55%, while the rubbing stripe occurrence rate of groups B and C is 0%. Therefore, it is considered that θ ₂ = 15 °, that is, preventing the rubbing roll 20 from moving in the same direction as the rubbing roll 20 in the rotational direction (rubbing direction) is effective in preventing the occurrence of rubbing lines.

  Next, the figure which shows the microscope picture of the vertical alignment liquid crystal display element of group AC is shown in FIG. 4A to 4C correspond to groups A to C, respectively. In FIG. 4A, which shows a photograph of group A, it can be seen that the alignment film is not uniformly processed and rubbing lines are generated. On the other hand, in FIGS. 4B and 4C showing the photographs of the groups B and C, it can be seen that the alignment film is uniformly processed and no rubbing streaks are generated. This result can also be seen from Table 1.

Further, from FIG. 4B of Group B, the substrate 30 is not inclined from the X axis (θ ₁ = 0 °), and only the rubbing roll 20 is inclined 15 ° from the Y axis (θ ₂ = 15 °), It can be seen that the rotation direction of the rubbing roll 20 is also inclined by 15 °, and the rubbing direction is also inclined by 15 ° from the axis perpendicular to the horizontal pattern of the vertically aligned liquid crystal display element. Therefore, the rubbing direction of the vertically aligned liquid crystal display elements of group B is inclined by 15 ° compared to that of group A.

Further, from FIG. 4C of group C, not only the rubbing roll 20 but also the substrate 30 is inclined by 15 ° (θ ₁ = θ ₂ = 15 °) similarly to the rubbing roll 20, so that the rubbing roll 20 and the substrate 30 The relative positional relationship is similar to that of group A. Accordingly, the rubbing direction of group C is a direction perpendicular to the horizontal pattern of the vertically aligned liquid crystal display element, similarly to the rubbing direction of group A.

  From the above results, it can be seen that the rubbing direction is determined by the relative positional relationship between the rubbing roll 20 and the substrate 30.

  Next, FIG. 5 shows the results of measuring the contrast viewing angle characteristics of the vertically aligned liquid crystal display elements of each of the groups A to C using a viewing angle characteristic measuring apparatus for liquid crystal display elements (EZ-CONTRAST manufactured by ELDIM). When comparing the viewing angle characteristics of group A shown in FIG. 5 (a) with the viewing angle characteristics of group B shown in FIG. 5 (b), the viewing angle characteristics of group B are rotated by 15 ° as a whole with respect to those of group A. You can see that This is because the rubbing direction of group B is inclined by 15 ° with respect to the rubbing direction of group A.

  Further, comparing the viewing angle characteristics of group A shown in FIG. 5A with the viewing angle characteristics of group C shown in FIG. 5C, it can be seen that the viewing angle characteristics of group C are equivalent to those of group A. . This is because the rubbing direction of group C matches the rubbing direction of group A.

As described above, the rubbing treatment apparatus 1 according to this embodiment includes the angle θ ₁ formed by the substrate 30 and the direction perpendicular to the traveling direction of the rubbing roll 20, the direction perpendicular to the rotation axis of the rubbing roll 20, and the rubbing roll. The angle θ ₂ formed by the traveling direction of 20 has a relationship of θ ₁ = θ ₂ and θ ₂ ≠ 0 °. Thereby, it is possible to prevent the rubbing streak from occurring without changing the viewing angle characteristic.

1 rubbing treatment apparatus 10 stage 20 rubbing roll 30 substrate 40 motor

Claims (3)

Substrate transport means for moving a substrate having an alignment film on its surface in parallel with the surface;
A rubbing roll disposed so as to be in contact with the alignment film;
Rubbing roll moving means for moving the rubbing roll parallel to the surface of the substrate;
A rubbing roll rotating means for rotating the rubbing roll,
In a plane parallel to the surface of the substrate, an inclination angle θ _{1 of the} substrate with respect to a direction perpendicular to the traveling direction of the rubbing roll, and a traveling direction of the rubbing roll and a direction perpendicular to the rotation axis of the rubbing roll are formed. The angle θ ₂ is θ ₁ = θ ₂ and θ ₂ ≠ 0 °.
A rubbing treatment apparatus characterized by the above. A rubbing treatment method for performing a rubbing treatment by bringing a rotating rubbing roll into contact with the alignment film with respect to a substrate having an alignment film on the surface,
In a plane parallel to the surface of the substrate, an inclination angle θ _{1 of the} substrate with respect to a direction perpendicular to the traveling direction of the rubbing roll, and a traveling direction of the rubbing roll and a direction perpendicular to the rotation axis of the rubbing roll are formed. The angle θ ₂ is θ ₁ = θ ₂ and θ ₂ ≠ 0 °.
The rubbing processing method characterized by the above-mentioned. Performing a rubbing treatment on the alignment film formed on the surface of the substrate by the rubbing treatment method according to claim 2;
Two substrates having the alignment film subjected to the rubbing treatment are opposed to each other with the alignment film facing inward so that the rubbing directions are parallel and opposite to each other, and liquid crystal is sealed between the two substrates. And steps to
Attaching a polarizing plate to a surface opposite to the surface on which the alignment film of the two substrates is formed;
A method for producing a liquid crystal display element, comprising: