JPH1020290A - Liquid crystal display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device having good characteristic of black display, high contrast, at low cost and showing stable performance by comprising one substrate having a part of angled shape and making the angled shape a polygonal cone or circular cone. SOLUTION: An angle-shaped pattern is formed on a whole surface of a resin thin film 3 formed on a glass substrate 1 by a replica method. The highest part 5 of the angle is equivalent to the vertex of a quadratic cone, the lowest part of a bottom is equivalent to the base of the quadratic cone and four slopes exist for a quadratic cone. An ITO thin film 7 is evaporated on the upper surface of the thin film 3. Since a reflected light beam is reflected in four directions, the intensity of the reflected light becoming a noise per unit solid angle is lowered. Since no difference of beams between the vertical direction and the lateral direction exists, the image performance of a liquid crystal cell and reflection type LCD have no difference between the vertical-and lateral directions. When the vertex of the angle is somewhat rounded and the beam is reflected to the front face of a schlieren optical system, since the area of the vertex is minimum, the deterioration of black display is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly to a reflection type liquid crystal display device using a schlieren optical system.

[0002]

2. Description of the Related Art Conventionally, a reflection type liquid crystal display (LCD) in which a polymer dispersed liquid crystal is injected is mainly used for a projection display using a schlieren optical system. The schlieren optical system has a pupil such that light scattered by the reflective LCD does not enter the system. Said L
When the CD performs black display, no voltage is applied to the polymer-dispersed liquid crystal, and the directions of the liquid crystal small droplet groups are varied, and the polymer-dispersed liquid crystal having a difference in refractive index is exposed to light. Is scattered to perform black display.

[0003]

However, in the path through which the light of the LCD liquid crystal cell passes, there are interfaces having respective refractive index differences, and specularly reflected light therefrom enters the pupil of the schlieren optical system. Therefore, the display of the black display becomes gray close to white.

In particular, the interface between an ITO (indium tin oxide) film, which is a transparent electrode deposited on the counter substrate side, and a glass substrate has a difference in refractive index (2.0-1.5 = 0.
5) is large, which is particularly problematic.

As a method of solving the above problem, a method of forming irregularities on the interface is disclosed in, for example, SID 95 DIGE.
ST PP227 "16.2 Reflective
-Type LCPC Projection Dis
play ", USP 5,283,675 and the like.

The polishing method and the etching method introduced above are difficult to obtain uniform unevenness over a wide area, and these methods are liable to cause point defects such as pits.

As another method of preventing reflection due to a difference in refractive index, there is a method of forming an antireflection (AR) coat by laminating thin films having a refractive index intermediate between the two. However, this method requires a thin-film deposition, resulting in an increase in cost.

It is an object of the present invention to solve the above-mentioned problems and to provide a liquid crystal display device having good black display characteristics, high contrast, stable performance at low cost, and a method of manufacturing the same. I do.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive efforts and, as a result, have obtained the following invention. That is, the liquid crystal display device of the present invention is a liquid crystal display device having one transparent substrate, the other substrate facing the one substrate, and a liquid crystal material sandwiched between the one substrate and the other substrate. Wherein the one substrate has a chevron-shaped portion, and the chevron-shaped shape is a polygonal pyramid or a conical shape.

[0010] The present invention also includes a method of manufacturing a liquid crystal display device. That is, the method for manufacturing a liquid crystal display device of the present invention includes one transparent substrate, the other substrate facing the one substrate, and a liquid crystal material sandwiched between the one substrate and the other substrate. In the method for manufacturing a liquid crystal display device, the one substrate has a chevron-shaped portion, the chevron is a polygonal pyramid or a cone, and the chevron is formed by using a replica method or a molding method using a curable resin. It is characterized by being manufactured by Here, the curable resin preferably has an intermediate refractive index between the one substrate and the transparent electrode on the curable resin.

The present invention eliminates the above-mentioned disadvantages, and provides a counter substrate for a reflective LCD which exhibits stable performance at low cost.

It is preferable that a small slope having a rising angle of 5 to 20 ° is formed as the chevron shape on the counter substrate which is the one substrate. Further, by depositing an ITO film on the slope, it is possible to prevent light reflected from the interface between the ITO film and the slope from being incident on a film such as a schlieren optical system.

Since the inclined surface works to gradually narrow the cell gap of the liquid crystal cell, the gap amount of the liquid crystal cell can be kept substantially uniform by folding back at an appropriate distance.

The slope is prevented from generating defects by intentionally forming it as designed using a stable and proven manufacturing method, and by using a manufacturing method such as a molding method or a replica method. Substrates can be provided at low cost.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) FIG. 1 shows a counter substrate for a reflective LCD according to Embodiment 1 of the present invention. (A) is a plan view,
(B) is a side view. 1 is 3cm in size to be a substrate
Square, 1.1 mm thick non-alkali glass, refractive index 1.5
NA35 manufactured by Hoya Co., Ltd., and each side is provided with a 0.2 mm yarn chamfer 2.

Reference numeral 3 denotes a U layer having an average thickness of 30 μm and a refractive index of 1.5 on which the slope 4 is formed by a method called a replica method.
It is a V-curable resin thin film.

The replica method is a method in which a resin is pressed by using a mold. After the pressing, the resin is cured by irradiating UV light, whereby the resin is processed into an arbitrary shape. At this time, the thread chamfer 2 guarantees escape of the resin extruded by the mold.

(C) is an enlarged view of A-
It is A 'sectional drawing. The slope 4 is folded at a pitch of 20 μm, so that the amount of the liquid crystal cell gap increases.
It is preventing it from decreasing.

The slope has a regular quadrangular pyramid shape as shown in FIG. 2A, and the peaks 5 and the valleys 6 run in the horizontal direction of FIG.

An ITO film 7 which is a transparent electrode having a thickness of 1000 ° and a refractive index of 2.0 is formed on the entire surface of the resin 3. A liquid crystal cell is completed by injecting a polymer dispersed liquid crystal between the counter substrate and the substrate on which the reflective electrode is formed.

Light vertically incident from below through the glass substrate 1 is reflected by several percent at the interface between the resin 3 and the ITO film 7. In this embodiment, the rising angles θ ₁ and θ ₂ of the slope 4 are 1
Since the angle is set to 0 degrees, the reflected light is reflected at an angle of ± 20 ° in the horizontal direction according to the inclination of the slope. Thus, the light reflected from the interface does not enter the pupil of the schlieren optical system, and the above-described deterioration of the black display can be prevented.

The glass substrate used in this embodiment has no NA
It is not limited to 35, alkali-free glass or LC
Low alkali glass or plastic that does not adversely affect the operation of D may be used.

The UV-curable resin is not limited to this, and may be a thermosetting resin. Further, the refractive index of the resin is set to an intermediate value of 1.7 between the refractive indices of the glass substrate and the ITO film.
The effect of the anti-reflection (AR) coat can be expected by setting the value to about 5.

The thickness of the resin may be any thickness at which a slope can be accurately formed by the replica method.

The value of the pitch P is larger than a value of about 1 μm at which the function of the diffraction grating is enhanced, and may be any value as long as it is equal to or less than a value at which the gap accuracy is deteriorated. The height difference between the peak and the valley in the present embodiment is p × 1/2 tan θ ≒ 20 × １ ／ × 0.176 ≒ 1.
It is about 8 μm, and ± 0.2 mm for a gap amount of about 10 μm.
9 μm, ± 9%.

The rising angles θ ₁ and θ ₂ do not need to be equal on the left and right, and may be any angle that does not enter the pupil as described above.

In general, the FNo of the Schlieren optical system used for the reflection type LCD is about 2.0, and the minimum value of the rising angle allowed in that case is about 10 degrees. If the rising angle is too large, a problem occurs due to multiple reflections on the slope.
Desirable angles are 5 to 20 depending on the schlieren optical system.
°.

The running direction of the slope may be any direction.

FIG. 2 shows a detailed plan view and a sectional view of this embodiment. (A) is an enlarged plan view of a resin portion, (b)
Is a BB 'sectional view.

The resin thin film 3 formed on the glass substrate 1 has a chevron pattern formed on one surface by a replica method. 5 is the highest part of the mountain, which corresponds to the vertex of the square pyramid. Numeral 6 corresponds to a valley, which is the lowest part, and corresponds to the base of a square pyramid. There are four slopes 4 for one square pyramid, and the rise angle of the slope 4 is also 10 degrees. The light incident on the slope 24 is divided into two directions, up, down, left, and right.
Reflect at an angle of 0 degrees.

The pitch P between the quadrangular pyramids is 20 μm. An ITO thin film is similarly deposited on the upper surface of the resin thin film 3. According to the present embodiment, since the reflected light is reflected in four directions, the intensity of the reflected light that is to be noise per unit solid angle is reduced. Further, since there is no difference between the vertical direction and the horizontal direction, the liquid crystal cell using the counter substrate and the reflection type L
There is no difference between the upper, lower, left and right image quality of the CD.

Also, when the peaks of the peaks are slightly rounded and the reflected light is reflected toward the front of the Schlieren optical system, the area of the peaks is minimized, so that the deterioration of the black display is minimized. Can do things.

The quadrangular pyramid used for forming the slope in the present invention does not need to be a regular quadrangular pyramid, but may be any quadrangular pyramid.
The direction in which the quadrangular pyramids are arranged does not need to be the upper, lower, left and right directions, and may be at an angle of 45 ° or an arbitrary direction.

(Embodiment 2) FIG. 3 shows Embodiment 2 of the present invention.
Is shown.

The resin thin film 33 is formed in an inverted quadrangular pyramid, contrary to the view shown in FIG. The highest part is the ridgeline of 35 mountains, four lines forming a square. The lowest part is the bottom of the valley 36, and the slope 34 is similarly formed in four directions.

According to the present embodiment, the mold used for the replica method is a quadrangular pyramid, and the mold is easily released after the resin is pressed, so that the production is further facilitated.

The shape of the resin thin film used in the present invention may be any shape as long as it has a slope having a specific angle for preventing reflected light from entering the pupil of the Schlieren optical system. The above-mentioned quadrangular pyramids need not be quadrangular pyramids, but may be other pyramids, for example triangular pyramids. It may be a cone.

It is not necessary to form the slope portion on the opposing substrate entirely, but only the effective display area on which light is incident.

The method of forming the structure of the present invention does not need to be a replica method, but may be another forming method, for example, a glass molding method or a plastic molding method.

[0040]

As described above, according to the liquid crystal display device of the present invention, at the time of black display, the incident light can be reflected to a portion other than the pupil such as a schlieren optical system.
Black display characteristics can be improved. In particular, the black display characteristics can be further improved by providing a slope having a rising angle of about 10 degrees on the entire surface of the pixel region of the reflective LCD where light enters.

The molding method of the liquid crystal display device of the present invention,
In the manufacturing method using the replica method, a counter substrate for a reflective liquid crystal display device or a reflective liquid crystal display device can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a counter substrate of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a counter substrate of the liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a counter substrate of a liquid crystal display device according to a second embodiment of the present invention.

[Explanation of symbols]

 1,31 substrate 2 chamfering 3,33 resin 4,34 slope 5,35 mountain 6,36 valley 7,37 ITO

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Kazuyuki Shigeta, Inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Seiji Hashimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Inc.

Claims (3)

[Claims] 1. A liquid crystal display device comprising: one transparent substrate; another substrate facing the one substrate; and a liquid crystal material sandwiched between the one substrate and the other substrate. The substrate has a chevron-shaped portion, and the chevron-shaped shape is a polygonal pyramid or a conical shape. 2. A method for manufacturing a liquid crystal display device, comprising: one transparent substrate; another substrate facing the one substrate; and a liquid crystal material sandwiched between the one substrate and the other substrate. The one substrate has a chevron-shaped portion, and the chevron-shaped shape is a polygonal pyramid or a conical shape, and the chevron-shaped shape is manufactured using a replica method or a molding method using a curable resin. A method for manufacturing a liquid crystal display device. 3. The method according to claim 1, wherein the curable resin comprises:
The method for manufacturing a liquid crystal display device according to claim 2, wherein the liquid crystal display device has an intermediate refractive index with a transparent electrode on the curable resin.