JPH01238619A - Orientation treatment of liquid crystal cell - Google Patents

Abstract

PURPOSE:To obtain an orientation process of a liquid crystal cell permitting regulation of tilt of liquid crystal molecules by arranging a light shielding means having a narrow light transmitting part to between a laser light source and a substrate, and varying the output of the laser light source periodically while moving the light transmitting part along the substrate. CONSTITUTION:An orientation film 3 is formed on a substrate 1 having a transparent electrode 2 formed thereon by applying a photosensitive material on the substrate 1. When laser light 7 emitted from two laser light sources are projected to the orientation film 3 while causing interference between two luminous fluxes, interference fringes comprising alternate light parts and dark parts are generated on the orientation film 3. The direction of the interference fringes is arranged to be parallel to the direction of an arrow mark 9. A light shielding plate 5 provided with a slit-shaped light transmitting part 6 is interposed between the laser light source and the orientation film 3 and moved from an end 8 of the film 3 to another end of the film in the direction of the arrow mark 9, and the output of the laser light source is varied simultaneously periodically. The parts of the orientation film 3 exposed to the laser light are then removed by etching. Thus, many saw teeth-shaped parallel grooves 11 are formed on the surface of the orientation film 3.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for aligning a liquid crystal cell.

(Conventional technique) A schematic cross-sectional view of a typical liquid crystal cell is shown in Part 4.A transparent electrode 2 and an alignment film 3 are formed in this order on a substrate 1 such as a synthetic resin plate or a glass plate. Two such substrates 1 are placed facing each other with the alignment film 3 inside, and a liquid crystal 4 is sealed between these substrates 1.

In a liquid crystal cell, it is necessary to regulate the orientation of the liquid crystal 4 in a certain direction. For this reason, the surface of the alignment film 3 in contact with the liquid crystal 4 is subjected to alignment treatment. The most widely used conventional alignment treatment method is the rubbing method. In this method, the surface of the alignment film 3 is rubbed in one direction with a rubbing cloth to form a large number of grooves on the two surfaces. The liquid crystals become aligned in a direction parallel to the formed grooves.

However, the rubbing method has the drawback that fibers and dirt that fall off from the rubbing cloth during the rubbing process adhere to the surface of the alignment film, which causes defects and abnormal scratches on the surface of the alignment film, which deteriorates the alignment performance in those areas. had. Furthermore, due to wear and tear of the rubbing cloth, the surface of the alignment film cannot be uniformly deformed.

Another problem was that variations in the alignment of liquid crystals occurred.

It was developed to solve such problems.

This is an alignment processing method that utilizes interference fringes produced by two-beam interference of laser beams. In this method, the interference fringes are projected onto an alignment film 3 formed by coating a photosensitive material on a substrate 1,
Thereafter, an etching process is performed to form grating-like irregularities on the alignment film 3. If the photosensitive material is, for example, a positive photoresist, the portion of the alignment film 3 facing the bright portion of the interference fringes is removed by etching. In this way, as shown in FIG. 5, an alignment film 3 having a large number of parallel grooves 12 formed on two surfaces is obtained.

(Problem to be Solved by the Invention) The bottom of the groove 13 formed by the rubbing method has a sawtooth shape as shown in FIG. 6, and the liquid crystal molecules are tilted at an approximately constant angle on the alignment film surface. line up.

On the other hand, in the method using two-beam interference fringes of laser beams, grooves 12 with flat bottoms are formed as shown in FIG. I can't. When tilt regulation is not performed, disclination tends to occur in the liquid crystal when a voltage is applied to the liquid crystal, resulting in a problem that the display quality of the liquid crystal cell deteriorates.

The present invention was made in view of these problems, and its purpose is to provide excellent alignment performance, control the tilt of liquid crystal molecules, and prevent disclination of the liquid crystal when voltage is applied. An object of the present invention is to provide a method for aligning a liquid crystal cell that can prevent the above problems.

(Means for Solving the Problems) The method for aligning a liquid crystal cell of the present invention includes a step of forming an alignment film containing a photosensitive material on one surface of a substrate of a liquid crystal cell, and a step of forming an alignment film containing a photosensitive material on one surface of a substrate of a liquid crystal cell; A method for aligning a liquid crystal cell, which includes a step of projecting interference fringes due to interference onto the alignment film, the projecting step including a light shielding means having at least one narrow light transmitting portion that is connected to the laser light source. The interference fringes and the light transmitting section are arranged in a direction that forms a predetermined angle between the interference fringes and the light transmitting section, and the output of the laser light source is periodically changed while moving the light transmitting section along the substrate. This achieves the above objective.

(Example) The present invention will be described below with reference to Examples.

In the first part, a schematic configuration of an apparatus for carrying out an embodiment of the present invention will be shown. On the substrate 1 on which the transparent electrode 2 is formed, a photosensitive material is applied to form an alignment film 3. As the photosensitive material, it is preferable to use a positive photoresist or a photosensitive resin (polyimide, polyene, polythiol, etc.). For example, two laser beams 7 emitted from two laser light sources (not shown) are caused to interfere with each other and are projected onto the alignment film 3 from above. Therefore, interference fringes are generated on the alignment film 3 in which bright areas and dark areas appear alternately. The direction of the interference fringes is parallel to arrow 9.

Between the laser light source and the alignment film 3, a double light plate 5 having a slit-shaped light transmitting portion 6 is disposed.

The laser beam 7 passes only through the light transmitting section 6 and reaches the alignment film 3 . Both light plates 5 are arranged so that the long sides of the light transmitting portions 6 are substantially orthogonal to the direction of interference fringes.

When projecting the laser beam 7, both light plates 5 are moved in the direction of the arrow 9 so that the portion where interference fringes occur on the alignment film 3 moves from one end 8 of the alignment film 3 to the other end (not shown). . Simultaneously with the movement of both light plates 5, the output of the laser light source is changed periodically. At this time, if necessary, the laser light source is also moved along with the movement of both light plates 5.

Thereafter, two conventional etching processes are performed to remove the exposed portions of the alignment film 3. FIG. 2 shows an enlarged surface of an example of the alignment film 3 subjected to the alignment treatment in this manner. A large number of parallel grooves 11 are formed on the surface of the alignment film 3, corresponding to the exposed portions.

The shape of the bottom of the groove 11 is shown in FIG. Since the interference fringes were projected onto the alignment film 3 without periodically changing the output of the laser light source, the depth of the groove 11 changed periodically, and the groove bottom was formed by the rubbing method. It has a serrated shape. Therefore, the alignment film 3 can regulate the tilt of the liquid crystal.

Note that the shape of the groove bottom is not limited to that shown in FIG.
A desired groove bottom shape can be achieved by changing the output of the laser light source.

(Effects of the Invention) According to the present invention, there is no problem of foreign matter adhering to the alignment film in the rubbing method, and the liquid crystal molecules are tilt-regulated, thereby preventing the occurrence of disclination when voltage is applied. An orientation treatment method is provided. By performing alignment treatment using the method of the present invention, a liquid crystal cell having stable and good display quality can be realized.

4. Day 1 of 4. Figure 1 is a diagram schematically showing an apparatus for carrying out an embodiment of the present invention, and Figure 2 shows a portion of the surface of an alignment film that has been subjected to alignment treatment according to the embodiment. Perspective view, No. 3 bacteria is a joint cross-sectional view of the groove of the alignment film in FIG. 2, FIG. 4 is a partial cross-sectional view of the liquid crystal cell,
The figure is a partial perspective view of the surface of an alignment film that has been aligned by a conventional method using two-light east interference fringes of laser beams, Figure 6 is a vertical cross-sectional view of the groove of an alignment film that has been aligned by a rubbing method, and Figure 7 is a FIG. 2 is a vertical cross-sectional view of the surface of an alignment film that has been subjected to alignment treatment using a conventional method using two-beam interference fringes of laser beams.

l...Substrate, 2...Transparent electrode, 3...Alignment film, 4
...Liquid crystal, 5...Double light plate, 6...Light transmission part, 7.
...Laser light.

that's all

Claims (1)

[Claims] 1. A step of forming an alignment film containing a photosensitive material on one surface of a substrate of a liquid crystal cell, and a step of projecting interference fringes by two-beam interference using a laser light source onto the alignment film. A method for aligning a liquid crystal cell, comprising: in the projection step, a light shielding means having at least one narrow light transmitting portion is placed between the laser light source and the substrate so that the interference fringes and the light transmission A method for aligning a liquid crystal cell, in which the output of the laser light source is periodically changed while the light-transmitting part is moved along the substrate, and the light-transmitting part is oriented at a predetermined angle.