JPH11231327A - Liquid crystal cell and reflection liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal cell which can form a reflection liquid crystal display device superior in visual recognizability and display sharpness where the shadow of the liquid crystal cell is difficult to appear in the display regardless of omission of a diffusion layer between the liquid crystal cell and a reflection layer and blur is difficult to occur in a display picture. SOLUTION: In this reflection liquid crystal display device, a liquid crystal cell 5 has liquid crystal 3 enclosed between substrates 1 and 4, and columnar spacers 2 having a light diffusion function are interposed between substrates 1 and 4, and a reflection layer is arranged on the rear side of visual recognition of the liquid crystal cell. Thus, light made incident on columnar spacers is effectively used, and oblique incident light made incident on the cell again is efficiently diffused. The reflection liquid crystal display device is obtained which presents a satisfactory display quality without reduction of the contrast in a simple structure with the diffusion layer between the cell and the reflection layer omitted, and ] is given to display light by providing columnar spacers with inclined side faces to improve the field angle characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal cell capable of forming a reflection type liquid crystal display device excellent in brightness, viewing angle, display clarity and the like.

[0002]

BACKGROUND OF THE INVENTION Heretofore, there has been known a reflection type liquid crystal display device in which a diffusion layer is arranged between a liquid crystal cell using fine particles for adjusting a gap between substrates and a reflection layer provided on the viewing back side thereof. Such fine particles are formed so as to absorb light and exhibit as little light scattering properties as possible to achieve high contrast and high chroma.

In the above-mentioned reflection type liquid crystal display device, simplification of the structure and the like are important issues, and for that purpose, the omission of the diffusion layer is required. However, when the diffusion layer is omitted, there is a problem that the shadow of the liquid crystal cell is reflected on the display to reduce the visibility, and in the case of high definition color, there is a problem that the display image is easily blurred.

[0004]

SUMMARY OF THE INVENTION According to the present invention, even if the diffusion layer between the liquid crystal cell and the reflective layer is omitted, the shadow of the liquid crystal cell hardly appears on the display.
It is an object of the present invention to develop a liquid crystal cell which does not easily cause a blur on a display image and can form a reflective liquid crystal display device having excellent visibility and display clarity.

[0005]

According to the present invention, there is provided a liquid crystal cell in which liquid crystal is sealed between substrates, wherein a columnar spacer having a light diffusing ability is interposed between the substrates, and the liquid crystal cell includes the same. It is an object of the present invention to provide a reflection type liquid crystal display device characterized in that a reflection layer is arranged on the viewing back side.

[0006]

According to the present invention, based on the light-diffusing columnar spacer for adjusting the gap between the substrates, the light incident on the columnar spacer is scattered and reaches the reflective layer disposed on the back surface of the cell. By being reflected through the cell and re-entering the cell, the light incident on the columnar spacer can be effectively used to achieve a bright display, and the oblique incident light re-entered the cell is efficiently diffused to achieve a wide viewing angle. be able to.

Further, since the liquid crystal cell exhibits a diffusion effect, a cell shadow does not appear on the display, and a clear display image excellent in visibility due to less bleeding of the display image can be obtained, and the contrast is lowered. Thus, a reflection type liquid crystal display device having a simple structure in which the diffusion layer between the cell and the reflective layer is omitted and exhibiting good display quality can be obtained.

In addition, when the columnar spacer is provided with an inclined side surface to provide a refractive index difference between the columnar spacer and the liquid crystal layer, light diffusing ability due to the refraction effect of the inclined side surface is added, and light incident on the inclined side surface is reduced. Due to the tilted structure anisotropy due to refraction, the light is reflected by the cell substrate to show good directivity, and the viewing angle characteristics can be further improved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The liquid crystal cell of the present invention has a structure in which liquid crystal is sealed between substrates having columnar spacers having light diffusing ability. An example is shown in FIG. 1, 4 is the substrate, 2
Is a columnar spacer, and 3 is a liquid crystal layer. In the present invention, there is no particular limitation except that the gap between the substrates is adjusted via the columnar spacer having the light diffusing ability, and a liquid crystal cell can be formed according to the related art.

Therefore, the liquid crystal cell can be formed of any type, such as an active matrix driving type such as a thin film transistor type, and a simple matrix driving type such as a twist nematic type or a super twist nematic type. As the substrate, an appropriate substrate such as a glass plate or a plastic substrate can be used.

The columnar spacers interposed between the substrates are formed by forming columnar projections on the substrate by an appropriate method such as a method of applying a plastic liquid on the substrate through a mask having a through hole of a predetermined shape. And the like. In addition, perforating plastic film,
It is also possible to form a columnar spacer by forming a hole for liquid crystal in a predetermined pattern and interposing a perforated film between the substrates with a portion serving as a columnar spacer remaining between the holes. it can.

In the above, the provision of the light diffusing ability to the columnar spacer can be performed by an appropriate method, and any known light diffusing means can be applied. It is preferable to use a columnar spacer that has a small haze and easily transmits light while being scattered, rather than being inconspicuous. Incidentally, examples thereof include columnar spacers obtained by mixing an organic or inorganic light diffusing substance or bubble in a transparent plastic or a film thereof, and columnar spacers formed of a mixture of two or more types of transparent plastics having different refractive indexes. Is raised.

Examples of the light diffusing substance include metal oxide particles, metal particles, and other inorganic particles made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like. Any suitable material such as organic fine particles made of a crosslinked or uncrosslinked polymer or the like can be used. Transparent fine particles having a refractive index different from that of the plastic to be mixed base are preferable from the viewpoint of inconspicuousness and the like.

The plastic used for forming the columnar spacer is not particularly limited, and an appropriate plastic can be used. Plastics with excellent transparency are preferred. By the way, examples of plastics include acrylic polymers, silicone polymers, polyester and polyurethane,
Polyether or synthetic rubber, polyether sulfone or polycarbonate, polyamide or polyimide, polyolefin or acetate polymer, polyvinyl alcohol or polystyrene, vinyl acetate polymer, or phenol or melamine, acrylic or urethane, acrylic urethane or epoxy Thermosetting type such as silicone or silicone,
Or an ultraviolet-curable resin.

The dimensions of the columnar spacers can be appropriately determined according to the target gap between the substrates and the like. Generally, 100 μm or less based on one side or diameter,
５０50 μm, especially 5-30 μm. The form of the columnar spacer is arbitrary, and may be an appropriate form such as a cylinder, a triangular prism, a square pillar, or another polygonal pillar.

As shown in FIG. 1, when the shape of the columnar spacer 2 has an inclined side surface 21 and a refractive index difference is provided between the columnar spacer 2 and the liquid crystal layer 3, light is incident on the inclined side surface 21 as shown by an arrow. The refracted light is refracted and diffused, and is reflected by the cell substrate 4 or a reflection layer (not shown) due to the anisotropy of the inclined structure, thereby exhibiting good directivity, which is advantageous for improving the viewing angle characteristics.

The arrangement density of the columnar spacers can be appropriately determined in accordance with the deformability of the substrate.
0.1 to 100 per ^2, 1-50 among other things, in particular 3
There are 30. The height of the columnar spacer can be appropriately determined according to the target gap between the substrates, but is generally 30 μm or less, preferably 0.1 to 20 μm, particularly 0.5 to 10 μm.
μm.

The liquid crystal cell according to the present invention comprises a liquid crystal display device,
In particular, it can be preferably used for forming a reflection type liquid crystal display device. FIG. 2 illustrates a configuration example of a reflection type liquid crystal display device using a liquid crystal cell according to the present invention. This is composed of a liquid crystal cell 5 having a polarizing plate 7 on both sides and a reflective layer 8 arranged on the viewing back side. As in this example, when the liquid crystal cell according to the present invention is used, a reflective liquid crystal display device having excellent display quality can be formed without disposing a diffusion layer between the cell and the reflective layer, and the structure is simplified. It has advantages that can be Note that reference numeral 6 in the drawing denotes an adhesive layer, and 51 denotes a sealing material.

In practical use of the liquid crystal cell according to the present invention,
It can be used as a laminate in combination with an appropriate optical element. Incidentally, examples thereof include a polarizing plate provided on one side or both sides of a liquid crystal cell, and a liquid crystal cell laminated with an optical element formed of a reflective layer or the like provided on the back side of the viewing side of the cell.

The above-mentioned optical elements such as a polarizing plate and a reflective layer are used for forming a liquid crystal display device or the like, and are previously integrated with a liquid crystal cell. As the polarizing plate, for example, an appropriate one such as a polarizing glass, a polarizing film, and a transparent protective layer provided on one or both sides thereof can be used.

In general, iodine and / or a dichroic dye is adsorbed on a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, and an ethylene / vinyl acetate copolymer-based partially saponified film. For example, a polarizing film made of a polyene oriented film or the like provided with a transparent protective layer, such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride, is used.

As the reflection layer, an appropriate one according to the related art can be used. By the way, as an example, a metal foil, a coating layer holding a metal powder with a binder, a reflection plate having the coating layer provided on a support substrate, a metal vapor deposition layer or the metal vapor deposition layer on the support substrate. And a reflection plate provided. In the case of a reflective layer, particularly a reflective layer made of metal, the reflective layer may be provided with a coat layer on one or both sides for the purpose of improving the reflectance and preventing oxidation.

The reflection type liquid crystal display device may be of a type utilizing sunlight or the like having no light source device, or of a type having a light source device and utilizing the light from the light source. Is also good. In the case of a device having a light source device, the light source device is disposed on the opposite side of the liquid crystal cell in which the reflection layer is disposed, that is, on the viewing side.

As a result, it is necessary to arrange the light source device at a position that does not hinder the view of the screen, or to use a light source device that allows the view of the screen. Examples of the light source device include a point light source including an emitting diode and the like,
A sidelight type backlight using a light guide plate capable of transmitting light on both sides is exemplified.

In the above, each layer such as the liquid crystal cell and the polarizing plate may be arranged so as to be separable. However, in view of stability of quality and production efficiency of the liquid crystal display device, the layers are preliminarily bonded as shown in FIG. It is preferable that they are integrated via a layer or the like. An appropriate adhesive such as a pressure-sensitive adhesive can be used for the adhesive treatment.

If necessary, the adhesive layer may contain appropriate additives such as fillers made of glass fibers, glass beads, metal powders and other inorganic powders, and antioxidants. Further, the above-mentioned light-diffusing substance or the like may be contained to form an adhesive layer having a light-diffusing property. Therefore, in the present invention, the arrangement of the diffusion layer other than the columnar spacer is not limited.

Each layer forming the liquid crystal cell, the polarizing plate and the like is mixed with an ultraviolet absorbent such as a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, a nickel complex salt compound, or the like. UV absorbing ability.

[0028]

EXAMPLE 1 A polyester film subjected to a predetermined perforation treatment through an electron gun was placed on a glass substrate provided with an alignment film and a transparent conductive film, and a mixture of poly (methyl methacrylate) and polycarbonate was placed on the film. And then dried and cured, the polyester film was removed, and ^two cylindrical spacers having an average diameter of 7 μm and a height of 3 μm having an inclined slope 21 as shown in FIG. Was obtained. The columnar spacer was made of a polymer alloy having a sea-island structure on the order of submicrons and exhibited light diffusion.

Next, a nematic liquid crystal is developed on the surface of the glass substrate on which the columnar spacers are formed, another glass substrate provided with an alignment film and a transparent conductive film is disposed thereon, and the periphery thereof is sealed. I got a cell. Then, a polyvinyl alcohol-based polarizing plate was adhered to both sides of the liquid crystal cell through an acrylic adhesive layer having a thickness of 20 μm, and a 20 μm-thick
An aluminum foil having a thickness of 30 μm was adhered via the acrylic pressure-sensitive adhesive layer to obtain a reflective liquid crystal display device (FIG. 2).

When the above-obtained reflection type liquid crystal display device was visually recognized under indoor lighting, it was excellent in brightness and viewing angle.
The display was free from cell shadows and bleeding, and a clear display image could be visually recognized with good contrast. In addition, based on the arrangement in which the inclined slope of the columnar spacer is located on the upper side, the display light exhibited good directivity in the vertical direction, and the viewing angle characteristics in the vertical direction were particularly good.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a liquid crystal cell.

FIG. 2 is a cross-sectional view of an example of a liquid crystal display device.

[Explanation of symbols]

 5: liquid crystal cell 1, 4: substrate 2: columnar spacer 21: inclined slope 3: liquid crystal layer 7: polarizing plate 8: reflection layer

Claims (3)

[Claims] 1. A liquid crystal cell in which liquid crystal is sealed between substrates, wherein a columnar spacer having light diffusing ability is interposed between the substrates. 2. The liquid crystal cell according to claim 1, wherein the columnar spacer has an inclined side surface, and exhibits a light diffusing ability based on a refractive index difference from a liquid crystal layer. 3. A reflection type liquid crystal display device comprising a liquid crystal cell according to claim 1 or 2, wherein a reflection layer is arranged on the viewing back side.