JP2000221496A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low-cost liquid crystal display element having a simple structure in a few production steps by providing one of gas barrier layers with a light reflecting function. SOLUTION: A liquid crystal 3 is held in a gap formed by an upper substrate 11 and a lower substrate 12 and it is hermetically sealed with a sealing agent 5. An ordinary resin substrate is used as the upper substrate 11 and the substrate 11 is obtained by forming a transparent gas barrier layer and a hard coat layer on a base film The lower substrate 12 is obtained by forming a gas barrier layer comprising Al and having a light reflecting function and a hard coat layer on an base film. The light reflecting gas barrier layer functions as a light reflecting plate of the resulting element, unnecessitates a reflecting plate disposed on the outside of a liquid crystal cell, reduces the number of the constituent members of the cell and unnecessitates a step for sticking a reflecting plate. A film of a metal such as Al, Ag or Au or an alloy of those or a dielectric multilayered film may be used as the gas barrier layer.

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 using a notebook or film resin substrate as a substrate.

[0002]

2. Description of the Related Art Liquid crystal display devices employing a sheet-like or film-like resin substrate instead of a glass substrate have been put to practical use. This element is used as a display element for portable equipment because it is lighter than a glass substrate and can be made thinner. In a conventional liquid crystal display device using a resin substrate, since the resin itself has high gas permeability, it is common to provide an organic or inorganic transparent gas barrier layer on the substrate for high reliability. In addition, it is common to provide a layer called an overcoat or a hard coat in order to secure solvent resistance and scratch resistance in the process. Further, when the element is used as a reflection type, it is necessary to provide a reflection plate and a polarizing plate outside the cell, which results in an extremely multilayer structure. For this reason, there has been a problem that the cost of the liquid crystal display element on the resin substrate is higher than that of the liquid crystal element on the glass substrate.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in a liquid crystal display device employing a resin substrate and has a simple structure, a small number of manufacturing processes, and a low cost. The purpose is to provide.

[0004]

According to the present invention, there is provided a liquid crystal display device having a gas barrier layer for reducing gas permeability of at least one substrate and having a structure in which liquid crystal is sandwiched between resin substrates. The above problem was solved by providing a liquid crystal display element characterized in that at least one of the gas barrier layers has a function of reflecting light.

In the present invention, the above-mentioned gas barrier layer having a function of reflecting light functions as a light reflecting plate of an element, and usually eliminates the need for a reflecting plate disposed outside a liquid crystal cell. The number of constituent members is reduced, and the step of attaching the reflection plate is not required. The gas barrier layer preferably has a reflectance of at least 50% or more.

The gas barrier layer is made of Al, Ag, A
metals such as u, Cr, Ni, Zn, Zr, Cu, Mg,
Alternatively, examples thereof include alloys thereof and dielectric multilayer films. In order to form these films, a vacuum film forming method such as a vacuum evaporation method, a sputtering method, or an ion plating method may be applied. An organic or inorganic protective layer can be formed on the surface of these films as necessary. When a plurality of gas barrier layers are provided, they may be provided on the same substrate or may be provided on a counter substrate. However, when provided on the opposite substrate, at least one of them must be transparent.

[0007] The gas barrier layer having the function of reflecting light is provided on the substrate on the side opposite to the observer among the substrates, and silicon oxide, aluminum oxide, magnesium oxide is provided on the observer-side substrate. , A transparent inorganic film such as titanium oxide or zirconium oxide, or a transparent organic film such as an ethylene-vinyl alcohol copolymer or an acrylonitrile copolymer is provided as a gas barrier layer.

The base film is preferably an optically isotropic resin having a heat resistance of at least 100 ° C. or higher, such as polycarbonate, polyarylate, polyethersulfone, and polynorbornene resin.

When a gas barrier layer having a reflecting function is provided on the liquid crystal layer side of the base film, a stretched film such as polyethylene terephthalate or polyethylene naphthalate having optical anisotropy can also be used.

Examples of the hard coat layer include materials such as an acrylate resin, an epoxy acrylate resin, an epoxy resin, an epoxy melamine resin, and a urethane acrylate resin, but are not limited to these resins.

In the liquid crystal display device of the present invention, particularly when a gas barrier layer having a reflection function without an uneven structure is used, a forward scattering plate may be provided in the device. The position of the forward scattering plate is located at the frontmost position of the liquid crystal cell or between the polarizing plate and the liquid crystal cell. Further, fine particles having different refractive indices can be mixed into the hard coat layer of the substrate to replace the forward scattering plate. Further, a layer composed of a resin and fine particles having a different refractive index from the resin may be formed separately from the hard coat layer, and may be used instead of the forward scattering plate. Such a configuration is preferable because the viewing angle dependency of the element can be reduced. Further, depending on the material of the gas barrier layer, the substrate may be warped by heating or the like. In order to reduce such a phenomenon, an anti-curl layer for canceling the deformation of the substrate may be further provided.

The display system which can be used in the liquid crystal display device of the present invention includes a polymer dispersion system which does not require a polarizing plate, a phase transition system, a dynamic shuttering system, a guest-host system, and a single polarizing plate. Examples thereof include a swissed nematic (TN) system, a super twisted nematic (STN) system, an electric field control birefringence system, and a guest-host system, which use only a swept nematic system.

[0013]

The present invention will be specifically described below with reference to examples. In each of the following embodiments, the display system is a guest-host system in which a black dichroic dye using a single polarizing plate is added to a nematic liquid crystal for simplicity. The polarizer was arranged so that it was parallel to the substrate at the time of application, and the orientation direction of the liquid crystal was perpendicular to the transmission axis of the polarizer. The gas barrier layer also serving as a reflective layer is 100
Al having a thickness of 0 A was used, and SiO ₂ having a thickness of 500 A was used for the gas barrier layer of the upper substrate. Also for simplicity,
Unless otherwise noted, display electrodes, alignment films, and the like are omitted from the drawings. The hard coat layer is made of 2 μm thick epoxy acrylate resin, and the base film is made of 100 μm thick epoxy acrylate resin.
An m-thick polycarbonate film was used.

Embodiment 1 FIG. 1 is a sectional view showing a configuration example of a first liquid crystal display element of the present invention. The liquid crystal 3 is sandwiched in a gap formed by the upper substrate 11 and the lower substrate 12, and is sealed by a sealant 5. 4 is a polarizing plate. FIG. 2 shows an upper substrate, which uses a substrate used for a liquid crystal display element using a normal resin substrate. That is, the transparent gas barrier layer 111 and the hard coat layers 112 and 113 are formed on the base film 110.

FIG. 3 illustrates the lower substrate.
The base film 120 has a gas barrier layer 121 and a hard coat layer 122, which have a reflection characteristic made of Al.
23 are formed. With such a configuration, it is no longer necessary to provide a reflection plate, which was conventionally required, outside the cell,
Further, since the configuration of the cell is almost the same as the conventional one, there is no increase in the number of steps or processes.

Embodiment 2 FIG. 4 shows a second configuration example of the present invention. In this configuration, in the present configuration in which the light reflective barrier layer (121) provided on the back surface side of the lower substrate in Example 1 is provided on the liquid crystal side,
Since there is almost no influence of parallax due to the thickness of the substrate, there is no feeling of floating characters, and high quality display performance can be obtained. In the case where a metal barrier layer is used in this structure, it is necessary to provide an insulating layer 123 as shown in FIG. Examples of the insulating layer include the same materials as the hard coat layer, and inorganic oxides such as silicon oxide, aluminum oxide, magnesium oxide, titanium oxide, and zirconium oxide.

Embodiment 3 In this embodiment, as shown in FIG. 5, irregularities are formed on the gas barrier layer 121 having a function of reflecting light. The size of the unevenness is preferably such that it cannot be recognized by the naked eye.
The range is preferably from m to 100 μm. In this embodiment, a hemispherical concavo-convex structure having a pitch of 5 μm and a height of 2 μm is formed by press-molding a substrate base, and Al (1
21) Such a structure was formed by vapor deposition and subsequently forming a hard coat (122). This embodiment has a feature that the element can be observed at a wider viewing angle because the light reflectivity is diffused.

Embodiment 4 In this embodiment, as shown in FIG. 6, a gas barrier layer having a function of reflecting light is provided on both sides of a base film. With such a configuration, curling of the substrate due to a difference in thermal deformation between the barrier layer and the base can be effectively reduced.

[0019]

[Effect] 1. (1) A liquid crystal display device which does not require a reflection plate, simplifies the structure, and can reduce the cost. 2. (2) In addition to the effect of (1), since the reflection plate and the liquid crystal layer are close to each other, a double image is reduced, and a liquid crystal display device with high image quality can be obtained. 3. (3) A liquid crystal display element having the same effect as the liquid crystal display element according to (2) can be obtained with an inexpensive metal reflector. 4. (4) A liquid crystal display device having a wide viewing angle is obtained. 5. Claim 5 A liquid crystal display element in which warpage or the like in a manufacturing process is prevented can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first configuration example of a liquid crystal display element of the present invention.

FIG. 2 is a cross-sectional view showing a substrate (upper substrate) that is usually used as a substrate of a liquid crystal display element.

FIG. 3 is a lower substrate of a liquid crystal display device having a gas barrier layer.

FIG. 4 is a sectional view showing a second configuration example of the liquid crystal display element of the present invention.

FIG. 5 is a cross-sectional view showing a gas barrier layer having irregularities and having a function of reflecting light.

FIG. 6 is a cross-sectional view of a structure in which gas barrier layers having a function of reflecting light are provided on both sides of a base film.

[Explanation of symbols]

 Reference Signs List 3 liquid crystal 4 polarizing plate 5 sealant 11 upper substrate 12 lower substrate 110 base film 111 gas barrier layer 112 hard coat layer 113 hard coat layer 120 base film 121 gas barrier layer having reflection characteristics 122 hard coat layer 123 hard coat layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H090 HA01 HD01 HD06 JB03 JD11 KA02 KA06 KA07 KA08 KA11 LA01 LA10 LA20 2H091 FA08X FA14Y FA31Y FB06 FB08 FC02 FC03 FC07 FD09 GA01 GA02 GA07 GA16 HA02 HA08 HA09 LA10 LA02

Claims (5)

[Claims] 1. A liquid crystal display device having a gas barrier layer for reducing gas permeability of at least one substrate and having a structure in which liquid crystal is sandwiched between resin substrates, wherein at least one of the gas barrier layers is A liquid crystal display element having a function of reflecting light. 2. A liquid crystal display device in which a gas barrier layer having a function of reflecting light is provided on a resin substrate in contact with a liquid crystal. 3. The gas barrier layer according to claim 1, wherein the gas barrier layer having a function of reflecting light is a conductor, and an insulating layer is provided between the gas barrier layer and the display electrode. Liquid crystal display element. 4. The liquid crystal display device according to claim 1, wherein the gas barrier layer having a function of reflecting light is formed in an uneven shape. 5. The liquid crystal display device according to claim 1, wherein gas barrier layers having a function of reflecting light are formed on both surfaces of the resin substrate.