JPS60217339A - Liquid crystal display panel and its manufacture - Google Patents

Abstract

PURPOSE:To manufacture a uniform product which scarcely has an uneven orientation by forming an oriented film of a polyimide compound between a pair of electrode substrates, packing a liquid crystal, irradiating two luminous flux interference fringes of a laser to the oriented film, and forming a grating-shaped uneven part. CONSTITUTION:A luminous flux from a laser light source 15 is made to pass through a lens 18 through mirrors 16, 17, and made incident on a beam splitter 22 through a pin hole 19, a collimating lens 20 and a mirror 21. The luminous flux which is divided into two by the beam splitter 22 is reflected by mirrors 23, 24 and becomes two luminous flux interference fringes, and becomes an uneven shape after irradiating a photosensitive resin 13 on an electrode substrate 2 and developing the photosensitive resin. At the time of development, a polyimide resin 12 is also patterned selectively by using the photosensitive resin as a mask. When the electrode substrate 2 is inclined, a saw tooth-shaped pattern is obtained. In this way, an oriented film which scarcely has an uneven orientation is obtained, and the display quality is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a liquid crystal display panel for displaying characters or images and a method for manufacturing the same, and in particular a structure in which liquid crystal orientation is imparted by a novel method in forming an alignment film. The present invention provides a liquid crystal display panel and a method for manufacturing the same.

Conventional configuration and its problems The basic configuration of a liquid crystal display device is a panel filled with liquid crystal between a pair of electrode substrates, combined with a polarizing plate. The density of light passing through the liquid crystal display device is controlled by the difference in birefringence with the aligned liquid crystal molecules. To initially align the liquid crystal, a series of treatments called alignment treatments are usually performed on the inner wall of the panel in contact with the liquid crystal.

An example of orientation treatment is to apply a thin layer (approximately Q1 μm) of an organic material such as polyimide resin, harden it by heat treatment at approximately 200°C or higher, and then rub nylon or vinyl fibers in a certain direction many times. This is called the rubbing method for orientation treatment.

In the rubbing method, the material of the organic alignment film and the curing conditions.

The reality is that the optimum conditions are determined empirically by experimenting with combinations of the material of the rubbing cloth, the fiber structure, the pressing force of rubbing, the relative speed twice, etc.

However, in the case of rubbing, since the surface of the alignment film is mechanically rubbed, defects and abnormal scratches are likely to occur on the surface of the alignment film due to fallen rubbing cloth fibers, dirt, and dust, and the durability of the rubbing cloth is not sufficient. There are drawbacks such as the alignment performance changing each time it is used and non-uniform alignment.

Furthermore, in liquid crystal panels for displaying images, in which switching elements such as thin film transistors are configured on electrode substrates corresponding to each of a large number of picture elements 6, the surface of the substrate is inevitably uneven, and the rubbing method is difficult. In this case, alignment may occur in the vicinity of the unevenness. This is especially true when the difference in level is large. In addition, charging due to rubbing often causes electrostatic damage to switching elements and other elements.

OBJECTS OF THE INVENTION The present invention provides a liquid crystal display panel having an alignment film processed by a novel method that avoids or solves the disadvantages of the conventional alignment film, and a method for manufacturing the same.

Structure of the Invention In order to achieve the above object, the present invention does not form weak traces on the atomic or molecular scale on the surface of the alignment film as in the conventional rubbing method, but uses two-beam interference fringes of laser light. A shallow groove is formed on the surface of the alignment film.

Description of examples 6. −.

FIG. 1 shows a configuration diagram of a liquid crystal display panel according to the present invention, in which a lower electrode substrate 2 has a transparent electrode 1 corresponding to a large number of pixels, and another electrode substrate 4 has a transparent electrode 3 on the entire surface.
A liquid crystal 6 is sealed around the periphery with a seal 6 and filled between the two. This liquid crystal self is sandwiched between two polarizing plates 8 and 9, and by using external light in some way or by adding a surface light source 1o, the whole becomes a transmissive liquid crystal display device or panel 11 for image display. It consists of

In order to initially align the liquid crystal 5, it is necessary to apply an alignment film to the electrode surface side of the lower electrode substrate 2 and the electrode surface side of the other electrode substrate 4, and to perform an alignment treatment. Instead of the rubbing method, two-beam interference fringes of laser light are used. The present invention is characterized in that a polyimide resin is used for the alignment film and a photosensitive resin is used as the alignment treatment material.
0.1 to 0.2 μm) and heat treated at around 160'C. After that, 3.7 liters of positive photosensitive tree vinegar
.

For example, Shipley's AZ-1350 is also thin (0
, 1 to 0.2 μm), and after prebaking, irradiation with two-beam interference fringes of laser light is performed as shown in FIG. The light beam emitted from the laser light source 16 passes through the reflecting mirrors 16 and 17, enters the condenser lens 18, passes through the pinhole 19, and then passes through the collimator lens 2° to become a parallel light beam with a spread beam. After that, this parallel ray is further reflected by the reflecting mirror 21.
After being reflected by the beam splitter 22, it is split into two by the beam splitter 22, reflected by the reflecting mirrors 23 and 24, and incident on the electrode substrate 2 (→ the photosensitive resin 13 coated on the top.) Two beams of parallel laser light are split into two. interference occurs in the space near this sample, producing slit-shaped interference fringes on the sample surface. In Figure 2, the optical axes of the two beams are incident at equal angles to the normal direction of the sample surface. The light intensity distribution on the sample surface at this time and the cross-sectional pattern obtained after developing the photosensitive resin are shown in FIG. 3 (&).

If, for example, 5P-910 manufactured by Toshi Co., Ltd. is used as the polyimide resin 12, the polyimide resin is also selectively patterned using the photosensitive resin as a mask during development, and an uneven grating is formed on the electrode substrate corresponding to the light intensity distribution. (lattice) shape 1
3', 12'. After that, by removing only the photosensitive resin pattern 13' with a solvent such as acetone or methyl ethyl ketone, a polyimide resin pattern 12' having grating-like irregularities as shown in FIG. If heat treatment is applied, it will no longer dissolve in the liquid crystal material as an alignment film.

Figure 4 shows the case where the optical axes of the two light beams are incident on the sample surface at an inclined angle, and the light intensity distribution on the sample surface at this time and the cross-sectional pattern obtained after developing the photosensitive resin are shown in Figure 6. As shown in the figure. In this way, when the two light beams are incident on the sample surface at an angle, a photosensitive resin pattern 13'' is formed.
becomes serrated, and the resin pattern 12' also becomes serrated,
It can be seen that the symmetry with the case in Figure 3 is lost.

FIG. 6 is a perspective view of an embodiment in which grating-like irregularities are formed in directions substantially orthogonal to each other using the two methods described above. In the figure, the liquid crystal molecules 25 arranged on the sample surface are schematically shown in a cylindrical shape.

The liquid crystal molecules are aligned in one direction at a tilt angle θ along the long edges of the sawtooth cross section. Such a tilt angle is TN (
In a twisted nematic (twisted nematic) type liquid crystal display panel, it is effective in giving directionality to the display and suppressing unevenness in display shading due to occurrence of reverse tilt.

It is desirable that the pitch of the grating be small in order to increase the degree of alignment of the liquid crystal, but the pitch of the grating is α2 μm
Even gratings with pitch and depth of 500 to 1 oOo showed good orientation. As a laser light source, a He-Cd laser with λ = 4416 was used, but it is easy to reduce the pitch by using a laser with a shorter wavelength or by changing the incident angle of the two beams. A color filter is required to color the panel, and in order to prevent the difference in optical path from diffusing due to the thickness of the electrode substrate, the color filter is installed in the space consisting of the electrode substrate 2, liquid crystal 5, and electrode substrate 4. Placed. Another embodiment of the present invention is a color filter according to the arrangement of the color filter. The transparent conductive layer is placed on either side of the other electrode substrate 4 which has a conductive layer.In order to prevent the voltage applied to the liquid crystal layer 5 from decreasing due to the intervention of the color filter, the transparent conductive layer and The alignment film is naturally formed on the color filter (in the case of →, there is a means for connecting the transparent electrode formed on the color filter and the switching element through the opening formed on the color filter). Needless to say, when a color filter is introduced, a pair of electrode substrates 2 and 4
There are some combinations that require alignment with the

Note that the electrode substrate material requires transparency and insulation, and is preferably made of glass, for example, but depending on the method of forming the switching element, quartz or resin may also be used, and the switching element has a wide range of choices, such as MIS transistors and varistors. is wide.

11.

Effects of the Invention As described above, according to the present invention, since the alignment treatment is performed using photofabrication technology, various defects and abnormal scratches on the surface, which were problems caused by conventional mechanical surface rubbing, are avoided. Therefore, it is possible to obtain a uniform alignment quality with less macroscopic and microscopic unevenness in alignment, thereby providing a liquid crystal display device with excellent display quality. Furthermore, there is no possibility of electrostatic damage to the device.

Furthermore, in the present invention, it is possible to use a photosensitive resin with high resolution and high sensitivity, and it is easy to further reduce the pitch, and it has excellent effects such as shortening exposure time and significantly improving productivity. Obtained.

[Brief explanation of the drawing]

Figure 1 is an exploded view of a liquid crystal display panel according to the present invention, Figure 2 is an exploded view of a liquid crystal display panel according to the present invention;
4 and 4 are system diagrams of the irradiation device for two-beam interference fringes of a laser beam according to the present invention. FIG. 6 is a perspective view of a main part of the surface of a sample in which grating-like irregularities are formed to be substantially perpendicular to each other. 2.4... Electrode substrate, 5... Liquid crystal, 1
2, 12'. 12' (...polyimide resin, 13, 13'
, 131<... photosensitive resin, 16... laser light source, 26... liquid crystal molecule. Name of agent: Patent attorney Toshio Nakao and 1 other name To IR

Claims (1)

[Claims] (1) Liquid crystal is filled between a pair of electrode substrates via an alignment film, the alignment film is made of polyimide resin, and its surface has grating-like irregularities for irradiation with two-beam interference fringes of laser light. A liquid crystal display panel featuring: ('4) The grating-like unevenness consists of a grating parallel to the orientation direction of the liquid crystal, and a grating having a sawtooth cross section that provides a tilt angle of the liquid crystal substantially perpendicular to the grating. The liquid crystal display panel according to claim 1. ('4) The liquid crystal display panel according to claim 1, characterized in that a color filter is disposed on the surface of one of the electrode substrates. Claim 3, characterized in that a transparent conductive layer is formed over the entire surface of the
The liquid crystal display panel described in section. 2.. (→ The liquid crystal display panel according to claim 3, characterized in that the transparent conductive layer on the color filter is connected to and independent of a switching element corresponding to the picture element. (@ A pair of electrodes) When manufacturing a liquid crystal panel in which liquid crystal is filled between substrates via an alignment film, the process includes a step of applying a polyimide resin that is soluble in a photosensitive resin developer, a step of applying the photosensitive resin, and a step of applying the photosensitive resin. A grating-shaped grating obtained by irradiating the resin with two-beam interference fringes of laser light, selectively removing the polyimide resin while developing the photosensitive resin, and removing the photosensitive resin with a solvent. A method for manufacturing a liquid crystal panel characterized by forming the entire alignment film with unevenness. (?) Prior to forming the alignment film with grating-like unevenness, a color filter is formed on one of the electrode substrates. A method for manufacturing a liquid crystal display panel according to claim 6, characterized in that (@3 according to claim 7, characterized in that a transparent conductive layer is formed on the color filter) A method for manufacturing a liquid crystal display panel. (Synchronization) A step of forming all openings in a Kalani filter, a step of forming a transparent conductive layer on a color filter corresponding to a picture element, a switching element in the picture element and the transparent conductive layer. 8. The method for manufacturing a liquid crystal display panel according to claim 7, further comprising the step of connecting the two.