JP2000029034A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a liquid crystal display using a planar luminous body so that a high temperature treatment which generates a deterioration of the planar luminous body is unnecessitated and to obtain the liquid crystal display thin shaped and light in weight. SOLUTION: Polymer films are laminated to a TFT array substrate 1 and a counter substrate 2 provided with planar luminous body, which are preliminarily produced with separate processes. Subsequently an alignment function toward a liquid crystal composition 4 is added to the polymer films by a normal rubbing treatment to form alignment films 3. Since the temperature applied to the polymer films for laminating is about room temperature to +100 deg.C, not such a high temperature as applied for conventional baking of alignment films, and the time for application is limited within a short time, the TFT array substrate 1 or the counter substrate 2 does not get high temperature and no deterioration of the surface illuminant on the counter substrate 2 is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a direct-view type active matrix liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices having the features of being thin, light, and low in power consumption have been developed using Japanese word processors,
It is actively used as a display device for personal OA equipment such as a notebook personal computer and a desktop personal computer, and as a video display device such as a television. In particular, an active matrix type liquid crystal display device is being actively developed as a portable display since it can realize a thin, lightweight, and high-resolution display (Reference: Hisao Ishii, Electronics Technology, 1997). July issue).

A conventional active matrix type liquid crystal display device is mainly composed of a liquid crystal display panel and a backlight (reference: edited by Tatsuo Uchida, "Next Generation Liquid Crystal Display Technology", Industrial Research Institute, 1994). . In this liquid crystal panel, a liquid crystal composition is sandwiched between two opposing substrates. For example, one TFT array substrate has a plurality of scanning bus lines in a row direction on one main surface of an insulating substrate. A signal bus line is formed in the column direction, and a pixel electrode is connected to a thin film transistor provided at the intersection.
Further, an alignment film is provided on the outermost surface of the substrate. On the other counter substrate, a common electrode or the like is formed on one main surface of the insulating substrate, and an alignment film is also provided on the outermost surface.
A glass substrate is generally used for the TFT array substrate and the counter substrate, and a soluble polyimide solution,
Or after applying a solution of polyamic acid on the substrate,
An organic film fired at a high temperature of about 00 degrees is used.
A bead-like spacer having a diameter of 2 to 5 μm is uniformly spread between these substrates, and a seal material is applied to the periphery of one of the substrates, leaving a liquid crystal injection portion. After that, the liquid crystal composition is vacuum-injected between the two opposing substrates and sealed to form a liquid crystal panel.

On the other hand, there are backlights of an edge light type and a direct type. In the former, a rod-shaped light (a cold cathode tube or a hot cathode tube) is placed at the end of a light guide plate, and this is combined with a reflection plate, a diffusion plate and a lens. It is composed of a sheet (prism sheet or wave sheet) or the like. The latter has a configuration in which a light is placed directly below a liquid crystal panel, and does not require a light guide plate (reference: Keiichi Nakajima, Electronic Technology, July 1997).

[0005]

SUMMARY OF THE INVENTION As described above,
It is an active matrix type liquid crystal display device characterized by its light weight. Conventionally, the thickness of the liquid crystal panel is usually about 3 mm.
In contrast to the following, a normal backlight has a light guide plate of 2 mm or more even in an edge light type thin one,
The overall module thickness was at least 5 mm or more. For this reason, further thinning and lightening were demanded (Reference: Ken Kojima, flat panel display,
1994). As a means for solving this problem, there is a method in which a surface light emitter is used as a backlight, and the surface light emitter is used as a counter substrate to make the liquid crystal panel thinner and lighter. A surface light emitter is a recently developed new light source. A two-layer organic film, an electron transport layer through which electrons easily flow and a hole transport layer through which holes easily flow, is formed on a glass substrate. A typical example is provided with electrodes. When an electric current is applied between the electrodes, electrons and holes flow into the respective layers and reach the bonding surface, and the electrons and holes recombine near the interface via excited molecules. At this time, electron energy is emitted in the form of light (references:
Shinji Okamoto, Electronic Technology, July 1997). As described above, the liquid crystal display device using the surface light emitter as the counter substrate is
Although it is extremely thin and lightweight, there is a problem that the surface light emitter deteriorates when the alignment film is fired at a high temperature in the manufacturing process.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a liquid crystal display device using a surface light-emitting device does not require a high-temperature treatment that causes deterioration of the surface light-emitting device during manufacturing. And an object of the present invention is to reduce the thickness and weight of the liquid crystal display device.

[0007]

According to the present invention, there is provided a liquid crystal display device provided on a display driving substrate and a counter substrate which are opposed to each other at a predetermined distance, and on one or both of the display driving substrate and the counter substrate. An organic film that emits electron energy as light when energized as light, a surface light emitter composed of upper and lower electrodes, an alignment film composed of a polymer film attached to the outermost surface of each of the display drive substrate and the counter substrate by lamination, and a display drive. The liquid crystal display device includes a liquid crystal composition sandwiched between a substrate and a counter substrate with an alignment film interposed therebetween. The alignment film is made of a polymer film having an alignment function by a rubbing treatment.

[0008] The orientation film is made of a polymer film having a regularity in the molecular structure by irradiation with ultraviolet light and having optical anisotropy. In addition, the alignment film,
It is made of a polymer film having an anisotropic surface shape. The alignment film is a film obtained by uniaxially stretching a polymer film having a flat surface. Further, the alignment film is a film obtained by uniaxially stretching a polymer film having convex portions or concave portions regularly arranged on the surface.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the liquid crystal display device according to the first embodiment of the present invention. In the figure, reference numeral 1 denotes a display driving substrate, for example, a TFT array substrate, and 2 denotes an opposing substrate which is arranged to face the TFT array substrate 1 at a predetermined distance, and in this embodiment, emits electron energy by conduction as light. And a surface light emitter composed of upper and lower electrodes. Reference numeral 3 denotes an alignment film made of a polymer film attached to the outermost surface of each of the TFT array substrate 1 and the opposing substrate 2 by lamination. In the present embodiment, the alignment film 3 is made of a polymer film having an alignment function by rubbing. Reference numeral 4 denotes a liquid crystal composition sandwiched between a TFT array substrate 1 and a counter substrate 2 having a surface light emitter via an alignment film 3. The liquid crystal display device according to the present embodiment is obtained by laminating a polymer film on a TFT array substrate 1 and a counter substrate 2 provided with a surface light emitter previously manufactured in separate steps, and then performing a normal rubbing process. An alignment film 3 is obtained by adding an alignment function for the liquid crystal composition 4 to the above polymer film.

FIG. 2 is a schematic view showing a process of laminating the alignment film 3 made of a polymer film in the present embodiment on the surface of the TFT array substrate 1 or the counter substrate 2. In the figure, 5 is a roller for lamination,
Arrows indicate the direction of rotation of the roller 5. Usually roller 5
Is heated, but the temperature applied to the polymer film at the time of lamination is not as high as that at the time of firing the conventional alignment film, but is about room temperature to about 100 ° C., and is short. Therefore, the TFT array substrate 1 or the opposing substrate 2
Does not become hot, and the surface light emitter provided on the counter substrate 2 does not deteriorate. A conventional rubbing treatment can be applied to the polymer film laminated on the TFT array substrate 1 and the counter substrate 2 as in the conventional case. Alternatively, an alignment treatment using polarized ultraviolet light can be performed. As a result, the laminated polymer film becomes an alignment film 3 having an alignment function for the liquid crystal composition 4.

The polymer film used as the alignment film 3 in the present embodiment is not particularly limited as long as it can be laminated on a substrate and can be subjected to a rubbing treatment, and various polymer films are used. . For example, polyimide, polyamide, polyethylene, polyacetylene, polydiacetylene, polyester, polyvinyl, polyvinyl cinnamate, polystyrene, polyphenylene, polyphenylene vinylene, polythienylene, polythienylene vinylene, polyacrylonitrile, polycarbonate, and derivatives thereof alone or in combination. Used. Alternatively, a multilayer structure of these polymers may be used. However, among these, a polyimide film is particularly preferable. If the adhesive strength at the time of lamination is weak as it is, a layer having a strong adhesive strength at the time of lamination may be provided on the lower surface of the polymer film.

As described above, according to the present embodiment, T
In a liquid crystal display device comprising an FT array substrate 1 and a counter substrate 2 provided with a surface light emitter, an alignment film 3 made of a polymer film adhered by lamination is used, so that a conventional soluble polyimide or polyamic acid or the like is used. It has become possible to assemble a liquid crystal display panel without going through a firing step that was necessary when the solution was used as an alignment film. Therefore, a thin and lightweight liquid crystal display device can be obtained epoch-making without deterioration of the surface light emitter.

Embodiment 2 FIG. In the second embodiment of the present invention, as the alignment film 3, a polymer film whose molecular structure has regularity by irradiation with ultraviolet light and has optical anisotropy, for example, polyvinyl cinnamate polymerized by polarized ultraviolet light is used. This is laminated on the TFT array substrate 1 or the counter substrate 2 as in the first embodiment. Note that the structure of the liquid crystal display device according to the present embodiment is the same as that of the above-described first embodiment, and a description thereof will be omitted. The polymer film according to the present embodiment includes:
Although it has an alignment function for the liquid crystal composition 4 without performing the rubbing treatment, the details of the mechanism are still unknown. However, in general, it is considered that a film having optical anisotropy has an alignment function with respect to the liquid crystal composition 4, so that rubbing is not necessary (references: KY Han et al.,
AM-LCD '97).

The polymer film used in the present embodiment is not limited to polyvinyl cinnamate but is not particularly limited as long as it has optical anisotropy and can be laminated on a substrate. Generally, a polymer having a regular molecular structure by ultraviolet curing is used. Alternatively, a film having a regular molecular structure may be used only on the surface of the polymer film. That is, for example, an organic compound having a diazo group called a command surface, a polymer film whose surface is modified with a photochromic material, or the like may be used. If the adhesive strength at the time of lamination is weak as it is, a layer having a strong adhesive strength at the time of lamination may be provided on the lower surface of the polymer film.

Embodiment 3 In the third embodiment of the present invention, a polymer film having anisotropic surface shape, for example, a polymer film having a groove in the longitudinal direction is used as the alignment film 3, and the same as in the above-described first embodiment.
It is laminated on the array substrate 1 or the opposing substrate 2. Note that the structure of the liquid crystal display device according to the present embodiment is the same as that of the above-described first embodiment, and a description thereof will be omitted. Although the polymer film according to the present embodiment has an alignment function with respect to the liquid crystal composition 4 without performing a rubbing treatment, the details of the mechanism are still unknown. However, generally, a polymer film having an anisotropic surface shape is said to have a shape alignment function with respect to the liquid crystal composition 4, and it is considered that rubbing is not required for this purpose (references: Kiyoshi Toda et al., Sharp Technique, No. 39
No. 1998).

The polymer film used in the present embodiment is not particularly limited as long as it has an anisotropic surface shape and can be laminated on a substrate.
Various polymer films are used. For example, polyimide, polyamide, polyethylene, polyacetylene, polydiacetylene, polyester, polyvinyl, polyvinyl cinnamate, polystyrene, polyphenylene, polyphenylenevinylene, polythienylene, polythienylenevinylene, polyacrylonitrile, polycarbonate, and derivatives thereof alone or in combination. Used. Alternatively, a multilayer structure of these polymers may be used. However, among these, a polyimide film is particularly preferable. If the adhesive strength at the time of lamination is weak as it is, a layer having a strong adhesive strength at the time of lamination may be provided on the lower surface of the polymer film. Also,
Although there is no particular limitation on the anisotropy of the surface shape, it is generally preferable that the groove is formed only in one of the X direction and the y direction as shown in FIG. In addition, a projection having a wedge-shaped or conical projection in cross section, or a projection having an ellipsoidal spherical shape when viewed from the top surface having regularity in only one of the x direction and the y direction is used.

Embodiment 4 In the fourth embodiment of the present invention, a polymer film having a flat surface, such as polyimide, is uniaxially stretched as the alignment film 3, and is used as the TFT array substrate 1 or the counter substrate 2 in the same manner as in the first embodiment. Laminated on top. Note that the structure of the liquid crystal display device according to the present embodiment is the same as that of the above-described first embodiment, and a description thereof will be omitted. Although the polymer film according to the present embodiment has an alignment function with respect to the liquid crystal composition 4 without performing a rubbing treatment, the details of the mechanism are still unknown. However, in general, a film obtained by uniaxially stretching a polymer film having a flat surface has no anisotropy in surface shape and the main chains of the polymers are arranged in the stretching direction. It is considered that the compound has a function of uniformly aligning the liquid crystal composition 4.

The polymer film used in the present embodiment is not particularly limited as long as the polymer main chain can be oriented by uniaxial stretching and can be laminated on a substrate. Are used alone or in combination, and a polyimide film is particularly preferable. Also, if the adhesive strength during lamination is weak as it is,
A layer having a strong adhesive force during lamination may be provided on the lower surface of the polymer film.

Embodiment 5 In the fifth embodiment of the present invention, as the alignment film 3, a film obtained by uniaxially stretching a polymer film having regularly arranged convex portions or concave portions on the surface is used. It is laminated on the array substrate 1 or the opposing substrate 2. Note that the structure of the liquid crystal display device according to the present embodiment is as follows.
The description is omitted because it is the same as in the first embodiment. Although the polymer film according to the present embodiment has an alignment function with respect to the liquid crystal composition 4 without performing a rubbing treatment, the details of the mechanism are still unknown. However, in general, when a polymer film having regularly arranged convex portions or concave portions on the surface is uniaxially stretched, the surface shape becomes anisotropic, and the liquid crystal composition 4 has a shape alignment function. It is thought that rubbing is no longer necessary because of this (Reference: Kiyoshi Toda et al., Sharp Technique,
39, 1998).

The polymer film used in the present embodiment is not particularly limited as long as it has convex or concave portions regularly arranged on the surface and can be laminated on a substrate. Although various polymer films similar to those of the third embodiment are used alone or in combination, a polyimide film is particularly preferable. If the adhesive strength at the time of lamination is weak as it is, a layer having a strong adhesive strength at the time of lamination may be provided on the lower surface of the polymer film. There are no particular restrictions on the projections or depressions on the surface, but in general, it is desirable that the surface has anisotropy after uniaxial stretching, and the diameter is 0.1 mm.
A circular shape of about 01 μm to 10 μm is desirable. Alternatively, grooves or wedge-shaped or elliptical protrusions may be regularly formed in only one of the X direction and the y direction.

As described above, in Embodiments 2 to 5,
The same effect as in the first embodiment can be obtained, and a thin and lightweight liquid crystal display device having a surface light emitter can be obtained. In the first to fifth embodiments, the surface light emitter is provided only on the counter substrate 2 side. However, the surface light emitter is provided only on the TFT array substrate 1 side or between the TFT array substrate 1 and the counter substrate 2.
May be provided in both.

[0022]

As described above, according to the present invention, a surface luminous body comprising an organic film which emits electron energy by light conduction as light and upper and lower electrodes is provided on one or both of a display driving substrate and a counter substrate. In the provided liquid crystal display device, an alignment film made of a polymer film is attached to the outermost surface of each of the display drive substrate and the counter substrate by lamination, so that a conventional solution of a soluble polyimide or polyamic acid is used as the alignment film. A baking step, which was necessary when used, is unnecessary, and a liquid crystal display panel can be assembled without going through a high-temperature treatment, so that a thin and lightweight liquid crystal display device can be obtained without deterioration of a surface light emitter. Became possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a laminating step of the liquid crystal display device according to the first embodiment of the present invention.

3A and 3B are a top view and a cross-sectional view illustrating a surface shape of an alignment film of a liquid crystal display device according to a third embodiment of the present invention.

[Explanation of symbols]

1 TFT array substrate, 2 opposing substrate, 3 alignment film, 4
Liquid crystal composition, 5 rollers.

Claims (6)

[Claims] 1. An organic device which is provided on one or both of a display driving substrate and a counter substrate which are disposed opposite to each other at a predetermined distance, and which emits electron energy as light when energized. A surface light-emitting body comprising a film and upper and lower electrodes; an alignment film made of a polymer film adhered to the outermost surface of each of the display drive substrate and the counter substrate by lamination; the alignment film between the display drive substrate and the counter substrate A liquid crystal display device comprising a liquid crystal composition sandwiched between the two. 2. The liquid crystal display device according to claim 1, wherein the alignment film is made of a polymer film having an alignment function by a rubbing process. 3. The liquid crystal display device according to claim 1, wherein the alignment film is made of a polymer film having a molecular structure which is made to have optical anisotropy by irradiation with ultraviolet rays. 4. The liquid crystal display device according to claim 1, wherein the alignment film is made of a polymer film having an anisotropic surface shape. 5. The alignment film according to claim 1, wherein the alignment film is formed by uniaxially stretching a polymer film having a flat surface.
The liquid crystal display device as described in the above. 6. The liquid crystal display device according to claim 1, wherein the alignment film is a film obtained by uniaxially stretching a polymer film having convex portions or concave portions regularly arranged on the surface.