JP2002148610A - Reflective liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide an inexpensive reflective liquid crystal display device capable of brightening a screen display with a wide viewing angle. SOLUTION: The reflection type liquid crystal display device has a first electrode plate 3 on which a transparent electrode 31 is formed, a second electrode plate 5 having a light reflection electrode 51 with an uneven surface, and sealing between these electrode plates. And a light scattering sheet 2 disposed between the polarizing plate 1 and the first electrode plate 3 disposed on the front side of the first electrode plate 3. A retardation plate may be provided between the first electrode plate 3 and the polarizing plate 1. The light scattering sheet may have a phase separation structure composed of a plurality of resins having different refractive indexes, for example, an isotropic bicontinuous phase structure formed by spinodal decomposition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a reflection type liquid crystal display device having a wide viewing angle and capable of maintaining the brightness of a display screen even in a dark environment.

[0002]

2. Description of the Related Art Liquid crystal display devices include personal computers (hereinafter referred to as personal computers), word processors,
It is widely used for display parts of electric products such as liquid crystal televisions, watches and calculators. Among such liquid crystal display devices, a backlight for irradiating the liquid crystal unit from the back surface is used except for low-brightness applications such as watches and calculators.

In recent years, infrastructure for information communication such as the Internet has been improved, and networking of information has been advanced by fusing computers and communication devices. With networking, access to information is no longer restricted by time and place. To use such networks efficiently, PDA (Personal Digital Assistance)
And other portable information terminals have been developed. Further, a thinner and lighter mobile personal computer has been developed in place of a notebook personal computer (personal computer).

[0004] Since these portable information communication devices are required to be portable, it is necessary to achieve both long battery drive time and thin and small communication devices. Therefore,
Displays used for these portable information communication devices are required to be thin and lightweight, and to have low power consumption. In particular, in order to achieve low power consumption, a method of using a natural light to brighten a display unit instead of a conventional liquid crystal display device using a backlight is being studied. The most promising display is a reflective liquid crystal display. In particular, in order to cope with the diversification of information accompanying the progress of multimedia in the future, there is a demand for an inexpensive reflective liquid crystal display device capable of displaying color and high image quality (high definition display) on a large screen. .

As a reflection type liquid crystal display device, a TN type (Tw
isted Nematic type) and STN type (Super Twisted Nematic)
Various types of devices such as a type) are known, but a type using a polarizing plate (single polarizing plate type) is advantageous for color display and high-definition display. For example, the liquid crystal layer is formed of HAN (Hybr
id-Aligned Nematic) The aligned R-OCB mode has excellent characteristics such as low voltage, wide viewing angle, high-speed response, halftone display, and high contrast. As a display device capable of forming a fine display on a screen, a TFT (Thin Film Transistor) that controls all pixels one by one.
Active matrix type liquid crystal display devices such as r) are also generally used. In an active matrix type liquid crystal display device such as a TFT type, since it is necessary to form hundreds of thousands or more transistors on a substrate, it is necessary to use a glass substrate liquid crystal display device. In contrast, an STN (Super Twisted Nematic) type liquid crystal display device uses a rod-shaped electrode to display a matrix type image, so it is less expensive than a TFT type, and a plastic substrate is used as an electrode substrate (support substrate). Can be used.

In such a reflection type liquid crystal display device, in order to impart brightness to the screen, light (natural light or external light) incident on the liquid crystal layer is efficiently taken in, the light is reflected by the reflector, and visibility is improved. The reflected light is scattered to such an extent as not to hinder the total reflection. If sufficient brightness cannot be obtained even when natural light or external light is used to the maximum, the light is illuminated from the lateral direction on the front of the liquid crystal display device to compensate for the brightness and use it temporarily. In some cases, a front light is used to perform the operation.

A reflection type liquid crystal display device is disclosed in
Japanese Patent No. 228887, Photographic Fabrication Symposium '92 sponsored by the Printing Society of Japan, applied basic technology of reflective liquid crystal display devices and applied a metal thin film with uneven surface as a back electrode (lower electrode) or a reflector to prevent total reflection. A liquid crystal display device in which the viewing angle of the display surface is enlarged is introduced. As described above, in the reflection type liquid crystal display device, an appropriately roughened rear electrode is used as a reflection electrode in order to avoid specular reflection.

However, in such a reflection type liquid crystal display device, a reflection plate (or a light-reflective back electrode) is appropriately roughened to scatter reflected light. Cost. In particular, when the reflected light is scattered at a wide angle, the brightness of the display surface decreases. For this reason, it is impossible to achieve a high level of both the scattering property at a wide angle and the luminance of the display surface. In particular, since the reflective layer functions as the back electrode of the liquid crystal cell, not only is there a limitation in the processing method and shape of the uneven portion, but also fine and precise processing is required. Further, when the display element is colored, a color filter is used in addition to the polarizing plate. In a color filter, the ratio of loss of reflected light is large, and in the diffuser system, sufficient brightness cannot be given to a display screen. In colorization, it is particularly important to provide high luminance by directional diffusion for directing diffused light in a certain direction. In order to enhance the directivity by the diffuse reflection plate method, it is necessary to precisely control the shape and distribution of the concave and convex portions of the reflection plate, which increases the cost.

In a reflection type liquid crystal display device, it has been proposed to form a light scattering sheet (light scattering layer) inside an electrode support substrate, that is, in a so-called liquid crystal cell. For example, a method is disclosed in which a liquid crystal layer has a dispersed structure in which liquid crystal and a polymer are dispersed in place of a light diffusing reflector in order to scatter reflected light to increase the brightness of the display surface. JP-A-6-258624). Further, a liquid crystal display device using a transmission type light scattering sheet instead of the diffuse reflection plate is also known. For example, a method of forming a light-scattering transparent resin layer inside or outside a liquid crystal cell is known. JP 7
Japanese Patent Application No. 98452/98 discloses a display element having a light diffusion layer formed in a liquid crystal cell, a transparent resin layer (light scattering layer) containing dispersed fine particles between an electrode of an electrode plate and a substrate (electrode supporting substrate). A formed display device is disclosed. Further, Japanese Patent Application Laid-Open No. 7-318926 discloses a display device in which a light diffusion layer in which liquid crystalline polymers are randomly oriented is formed between a liquid crystal layer and a support plate having a transparent electrode. On the other hand, JP-A-7-261171 discloses a display element having a light diffusion layer formed outside of a liquid crystal cell, in which a polarizing film is formed on the outer surface of an electrode plate, and two types having different refractive indices are provided on the surface of the polarizing film. A display element in which a light scattering layer in which the above resins are dispersed in a phase separated state is formed is disclosed. Japanese Patent Publication No. Sho 61-8430 also discloses a liquid crystal display device in which a light scattering layer is laminated on the surface of a polarizing layer formed on the front side of a liquid crystal cell.

Japanese Patent Application Laid-Open Nos. Hei 7-27904 and Hei 9-113902 disclose a particle scattering type sheet having a sea-island structure composed of plastic beads and a transparent resin. A transmission type liquid crystal display device formed therebetween is disclosed.

[0011]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a reflection type liquid crystal display device which can increase the viewing angle and improve the brightness of the display screen and can display brightly even in a dark environment. .

Another object of the present invention is to provide an inexpensive reflection type liquid crystal display device having a characteristic capable of scattering light at a wide angle.

[0013]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, when a liquid crystal cell having a light scattering property, a polarizing plate and a light scattering sheet are combined in a specific order, the visual field is reduced. The present inventors have found that the corners can be widened and the display surface can be made bright, and the present invention has been completed.

That is, the reflection type liquid crystal display device of the present invention comprises a first electrode plate which is located on the light incident side and has a transparent electrode, is disposed opposite to this electrode plate, and has an uneven surface. A second electrode plate having a light-reflecting electrode, a liquid crystal substance sealed between these electrode plates, a polarizing plate provided on the front side of the first electrode plate, A light scattering sheet disposed between the first electrode and the electrode plate. In this device, a light scattering sheet and a retardation plate may be disposed between the first electrode plate and the polarizing plate in any order. The light-scattering sheet may have a phase separation structure composed of a plurality of resins having different refractive indices, and is composed of a plurality of resins having different refractive indices, and at least isotropic bicontinuous phase structure. May be provided.
Furthermore, the light scattering sheet may scatter the incident light isotropically and have a maximum value of the scattered light intensity at a scattering angle of 3 to 60 °. When such a light scattering sheet is used, the intensity of transmitted scattered light can be increased at a specific scattering angle, and directivity can be given to the scattered light. The total light transmittance of the light scattering sheet is, for example, about 70 to 100%. Further, the light scattering sheet includes a sheet formed of a plurality of resins having different refractive indexes from each other and having at least an isotropic bicontinuous phase structure by spinodal decomposition. The difference between the refractive indices of the resins constituting the light scattering sheet is 0.0
It is about 1 to 0.2.

The spinodal decomposition includes not only a wet spinodal decomposition in which a solvent is removed from a liquid phase containing a plurality of resins (particularly, a resin solution dissolved in a common solvent) to separate phases, but also a plurality of resins. Dry spinodal decomposition in which a solid phase (particularly, a resin composition formed by melt-kneading) is separated by heating is also included.

Such a reflection type liquid crystal display device is useful as a reflection type liquid crystal display device using an external light and / or a front light without using a backlight. The polarizing plate usually converts external light and / or light from a front light into linearly polarized light. In such an apparatus, external light and / or front light incident on the liquid crystal material in the liquid crystal cell is reflected by the second electrode plate, and a voltage is applied between the electrodes to drive the liquid crystal material to produce linearly polarized light. To form an image.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings.

[Light-Reflective Liquid Crystal Display] The reflection type liquid crystal display of the present invention has a light scattering layer in a liquid crystal cell. That is, in a reflection type liquid crystal device having a light scattering layer in a liquid crystal cell, by arranging a polarizing plate and a light scattering sheet in a specific order, the viewing angle can be increased and the brightness of the display surface can be improved.

FIG. 1 is a schematic sectional view showing an example of the reflection type liquid crystal display device of the present invention. This reflective liquid crystal display device
A first electrode plate (or electrode substrate) 3 located on the light incident side (and emission side), and a second electrode plate (or electrode substrate) 5 disposed opposite to the first electrode plate And a liquid crystal cell composed of a liquid crystal layer 4 of a liquid crystal substance sealed between the first electrode plate 3 and the second electrode plate 5. Striped transparent electrodes 31 extending in the X-axis direction are formed on the inner surface of the first electrode plate 3, and extend in the Y-axis direction on the inner surface of the second electrode plate 5 to scatter and reflect incident light. (Light scattering reflective electrode or light reflective back electrode) 51 are formed, and the transparent electrode 31 and the light reflective electrode 51 face each other and cross each other to form a lattice matrix. The surface of the light-reflective electrode 51 is formed with irregularities in order to prevent the total reflection of incident light and impart light scattering.

The light scattering sheet 2 is laminated on the first electrode plate 3 constituting the liquid crystal cell with an adhesive 21, and the polarizing plate 1 is laminated on the light scattering sheet with an adhesive 11. . The polarizing plate 1 includes a polarizing layer having a roughened or surface-treated front surface, and a transparent protective film (not shown) laminated on the front and back surfaces of the polarizing layer.

In such a reflection type liquid crystal display device,
External light and / or incident light from the front light is converted into linearly polarized light by the polarizing plate 1 positioned on the front side (the light incident and emission side), and the external light and / or the incident light on the liquid crystal layer 4 in the liquid crystal cell. The front light is reflected by the reflective electrode 51 of the second electrode plate 5. Also, the electrodes 31, 51
A voltage is applied in between to drive the liquid crystal material of the liquid crystal layer 4 to control the transmission of linearly polarized light and form an image. The light reflected and scattered by the reflective electrode 51 is transmitted and scattered by the light scattering sheet 2 on the front side, and the transmitted scattered light is linearly polarized by the polarizing plate 1. Therefore, the viewing angle can be increased by the light scattering sheet 2 and the polarizing plate 1
Thereby, the brightness of the front surface (or the display surface) can be improved.

FIG. 2 is a schematic sectional view showing another example of the reflection type liquid crystal display device of the present invention. In this reflection type liquid crystal display device, the light scattering sheet 2 and the retardation film 6 are sequentially laminated on the first electrode plate 3 constituting the liquid crystal cell shown in FIG. Is the adhesive 21
The polarizing plate 1 is laminated.

In such an apparatus, the reflected light reflected and scattered by the reflective electrode 51 can be further transmitted and scattered by the light scattering sheet 2 on the front side, and the phase of the transmitted scattered light can be changed by the retardation film 6. , And can be linearly polarized by the polarizing plate 1. Therefore, the light scattering sheet 2 can increase the viewing angle, and the polarizing plate 1 can further improve the brightness of the front surface (or display surface),
The display surface can be further sharpened.

In the above-mentioned device, the retardation plate can be disposed at an appropriate position between the first electrode plate and the polarizing plate in combination with the light scattering sheet. For example, the light scattering sheet may be provided between the polarizing plate and the phase difference plate, or between the first electrode plate and the phase difference plate. In order to improve the sharpness of the image, it is basically preferable to be closer to the liquid crystal layer that generates the image, and it is preferable to dispose it between the retardation plate and the first electrode. The liquid crystal display device is an STN (Super Twisted Nematic).
matic) In the case of a liquid crystal display device, a retardation plate is usually used in order to prevent coloring of the screen. Therefore, the light scattering sheet is provided below the retardation plate (the retardation plate and the first electrode). It is preferable to dispose them between the two.

As the electrode plate (electrode substrate), glass, resin sheet or film can be used, and the second electrode plate is not necessarily required to be transparent. If necessary, a reflective layer may be formed on the back surface of the second electrode plate.

The transparent electrode is made of, for example, a metal oxide (ITO).
(Indium tin oxide), InO ₂ , SnO ₂ , ZnO, etc.), metal (Au, Ag, Pt, Pd, etc.) or the like. A preferred transparent conductive layer is an ITO layer.

The light reflective electrode can be formed of, for example, an aluminum thin film. The light-reflective electrode may be subjected to a surface roughening treatment by selecting an evaporation condition, a conventional surface roughening method for roughening a metal surface, or the like. Alternatively, an electrode having an uneven surface may be formed by vapor deposition on a roughened electrode substrate.
When the light-reflective electrode subjected to the surface roughening treatment is used, the incident light is appropriately scattered and reflected without being specularly reflected to generate outgoing light.

The transparent electrode and the light-reflective electrode can be formed by a conventional method, for example, a sputtering method, a vacuum deposition method, an ion plating method and the like. Further, the electrodes (transparent electrodes, light-reflective electrodes) can be patterned into stripes by photolithography or etching to form stripe electrodes. Further, the first and second electrode plates may be arranged so that the stripe-shaped electrode of the transparent electrode and the stripe-shaped electrode of the light-reflective electrode cross each other (for example, orthogonally).

Further, an alignment film (for example, a polyimide-based vertical alignment film) may be formed on each electrode by coating and drying in order to align the liquid crystal in a direction suitable for the reflection type liquid crystal. Rubbing may be performed if necessary.

Conventional optical materials can be used as the polarizing plate, the retardation plate and the reflection plate. For example, the polarizing plate is a polyvinyl alcohol-based film (such as a uniaxially stretched polyvinyl alcohol film adsorbing iodine), and the retardation plate is a And polycarbonate-based retardation plates. Further, the polarizing plate, the light scattering sheet and the retardation plate may be protected by a protective film. As the protective film, an optically isotropic film (eg, a cellulose derivative such as a triacetyl cellulose film) can be used.

Examples of the pressure-sensitive adhesive or adhesive include various pressure-sensitive adhesives and adhesives that do not impair optical properties, such as (meth) acrylic resin, vinyl acetate resin, silicone resin, polyester resin, polyurethane resin, Synthetic rubber can be used. As the acrylic resin of the acrylic pressure-sensitive adhesive, for example, C _1-14 alkyl acrylate (especially ethyl acrylate, n-propyl acrylate,
Examples thereof include homo- or copolymers of at least one monomer selected from isopropyl acrylate, butyl acrylate, C _2-8 alkyl acrylates such as 2-ethylhexyl acrylate) and methacrylate.

Further, the reflection type liquid crystal display device may be provided with a color filter if necessary. The color filter is located at an appropriate position between the first electrode plate and the front optical member, for example, between the first electrode plate and the light scattering sheet,
Between the electrode plate and the retardation plate, between the retardation plate and the light scattering sheet, between the light scattering sheet and the polarizing plate, and the like.

In the liquid crystal display device, adjacent optical members (such as a polarizing plate, a light scattering sheet, and a retardation plate) may be laminated on each other. For example, it may be used as a laminated sheet of a polarizing plate and a retardation plate, or a laminated sheet of a retardation plate and a light scattering sheet.

When a polarizing plate formed of a cellulose derivative resin is used, when the light scattering sheet is also made of a base resin or a cellulose derivative as a transparent support, the peeling stress due to thermal expansion or the like even when bonded to the polarizing plate. Is less likely to occur. Furthermore, a light scattering sheet in which another thermoplastic resin and / or inorganic fine particles are dispersed in a thermoplastic transparent base resin by melt film formation has a low thermal expansion coefficient with a retardation film (retardation film) and is inexpensive. Can be supplied.

It is practically useful to form an adhesive layer on at least one side of the light scattering sheet. It is not necessary to apply an adhesive to both sides of the light scattering sheet, but it is possible to use it without considering whether it is the adhesive layer side or to improve the adhesive strength of the light scattering sheet, etc. May be provided. The pressure-sensitive adhesive formed on one side of the light scattering sheet can be used, for example, for bonding to a retardation plate or a first electrode plate (a glass plate, a plastic substrate, or the like).

When a light scattering sheet is attached to the back surface of the polarizing plate, the light scattering sheet and the polarizing plate can be usually attached using an adhesive applied to the polarizing plate. If the polarizing plate and the light scattering sheet are laminated in advance and supplied to a conventional liquid crystal display device manufacturing line, the reflection type liquid crystal display device of the present invention can be manufactured without changing the process.

When the light-scattering sheet has a functional layer (such as a special light-scattering layer having light-scattering properties) on the surface, an adhesive is applied to the surface of the functional layer in order to protect the functional layer. You may work.

In the laminated sheet of the light scattering sheet and the retardation plate, the light scattering sheet and the retardation plate can be usually bonded together by using an adhesive applied to the retardation plate. The light scattering sheet may be bonded to the front surface of the phase difference plate, but it is necessary to consider the relationship between the coated surface of the adhesive and the front and back surfaces of the phase difference plate. If the retardation plate and the light scattering sheet are preliminarily laminated and supplied to a conventional liquid crystal display device manufacturing line, the reflection type liquid crystal display device of the present invention can be manufactured without changing the process.

Further, a laminated sheet of a polarizing plate, a retardation plate and a light scattering sheet may be used. Such a laminated sheet may be supplied to a conventional liquid crystal display device production line. In the laminated sheet, the laminating position of each optical member is not particularly limited, but it is preferable that the polarizing plate is positioned on the front side and laminated, and the polarizing plate is disposed on the front surface of the reflective liquid crystal display device.

Further, when using an optical member such as a color filter, if necessary, the color filter and one or more adjacent optical members are laminated to form a plurality of optical members as an integrated laminated sheet. A member may be used.

[Light Scattering Sheet] The light scattering sheet used in the present invention contains a plurality of resins having different refractive indexes in a state of phase separation, and has a phase separation structure. The refractive index of the plurality of resins is not particularly limited, but in order to enhance light scattering,
The plurality of resins have a difference in refractive index of, for example, 0.01 to 0.1.
It can be used in combination so as to be about 2, preferably about 0.1 to 0.15.

The plurality of resins are, for example, styrene resins,
(Meth) acrylic resin, vinyl ester resin, vinyl ether resin, halogen-containing resin, olefin resin (including alicyclic olefin resin), polycarbonate resin, polyester resin, polyamide resin, thermoplastic polyurethane resin , Polysulfone-based resins (polyethersulfone, polysulfone, etc.), polyphenylene ether-based resins (2,6-xylenol polymers, etc.), cellulose derivatives (cellulose esters, cellulose carbamates, cellulose ethers, etc.),
Silicone resin (polydimethylsiloxane, polymethylphenylsiloxane, etc.), rubber or elastomer (diene rubber such as polybutadiene, polyisoprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, acrylic rubber, urethane rubber, silicone rubber And the like). Usually, a transparent resin is used as the resin.

The styrene resin includes a styrene monomer homopolymer or copolymer (polystyrene, styrene-α-methylstyrene copolymer, styrene-vinyltoluene copolymer, etc.) or a styrene monomer. Monomer ((meta)
Copolymers with acrylic monomers, maleic anhydride, maleimide monomers, dienes, etc.). Examples of the styrene-based copolymer include a styrene-acrylonitrile copolymer (AS resin), a copolymer of styrene and a (meth) acrylic monomer [styrene-methyl methacrylate copolymer, styrene-methacrylic acid Methyl- (meth) acrylic acid ester copolymer, styrene-methyl methacrylate- (meth) acrylic acid copolymer], and styrene-maleic anhydride copolymer. Preferred styrene resins include polystyrene, copolymers of styrene and (meth) acrylic monomers [copolymers containing styrene and methyl methacrylate as main components, such as styrene-methyl methacrylate copolymer], AS resin, styrene-butadiene copolymer and the like are included.

As the (meth) acrylic resin, a homopolymer or copolymer of a (meth) acrylic monomer or a copolymer of a (meth) acrylic monomer and a copolymerizable monomer can be used. . (Meth) acrylic monomers include, for example, (meth) acrylic acid; methyl (meth) acrylate,
(Meth) acrylic acid C such as ethyl acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate
_1-10 alkyl; phenyl (meth) acrylate; hydroxyalkyl (meth) acrylate such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate; glycidyl (meth) acrylate;
N, N-dialkylaminoalkyl (meth) acrylate; (meth) acrylonitrile; and (meth) acrylate having an alicyclic hydrocarbon group such as tricyclodecane. Examples of the copolymerizable monomer include the above-mentioned styrene monomer, vinyl ester monomer, maleic anhydride, maleic acid, fumaric acid, and the like. These monomers can be used alone or in combination of two or more.

As (meth) acrylic resins, (meth) acrylic resins include C _1-6 alkyl poly (meth) acrylates such as poly (meth) acrylate,
In particular, methyl methacrylate-based resins containing methyl methacrylate as a main component (about 50 to 100% by weight, preferably about 70 to 100% by weight), for example, polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer , Methyl methacrylate- (meth) acrylate copolymer, methyl methacrylate-acrylate-
(Meth) acrylic acid copolymer, methyl methacrylate-styrene copolymer (MS resin and the like) and the like can be mentioned.

As the vinyl ester resin, a vinyl ester monomer alone or a copolymer (eg, polyvinyl acetate), a copolymer of a vinyl ester monomer and a copolymerizable monomer (ethylene- Vinyl acetate copolymer, vinyl acetate
Vinyl chloride copolymer, vinyl acetate- (meth) acrylate copolymer, etc.) or derivatives thereof (polyvinyl alcohol, ethylene-vinyl alcohol copolymer,
Polyvinyl acetal resin).

Examples of the vinyl ether resin include homo- or copolymers of vinyl C _1-10 alkyl ether such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether, and vinyl C _1-10 alkyl ether and copolymerizable monomer. (Vinyl alkyl ether-maleic anhydride copolymer and the like).

Examples of the halogen-containing resin include polyvinyl chloride, polyvinylidene fluoride, vinyl chloride-vinyl acetate copolymer, vinyl chloride- (meth) acrylate copolymer, and vinylidene chloride- (meth) acrylate copolymer. Coalescence and the like.

The olefin resins include, for example, olefin homopolymers such as polyethylene and polypropylene;
Copolymers such as an ethylene-vinyl acetate copolymer, an ethylene-vinyl alcohol copolymer, an ethylene- (meth) acrylic acid copolymer, and an ethylene- (meth) acrylate copolymer are exemplified. Examples of the alicyclic olefin-based resin include homo- or copolymers of cyclic olefins (such as norbornene and dicyclopentadiene) (for example, polymers having an alicyclic hydrocarbon group such as sterically rigid tricyclodecane). And copolymers of the aforementioned cyclic olefins and copolymerizable monomers (such as ethylene-norbornene copolymers and propylene-norbornene copolymers). The alicyclic olefin-based resin is available, for example, under the trade name "ARTON", under the trade name "ZEONEX", and the like.

The polycarbonate resins include aromatic polycarbonates based on bisphenols such as bisphenol A, and aliphatic polycarbonates such as diethylene glycol bisallyl carbonate.

Examples of the polyester resin include aromatic polyesters using an aromatic dicarboxylic acid such as terephthalic acid (such as poly C _2-4 alkylene terephthalate such as polyethylene terephthalate and polybutylene terephthalate and poly C _2-4 alkylene naphthalate). Homopolyester, copolyester containing C _2-4 alkylene arylate unit as a main component (eg, 50% by weight or more)
Can be exemplified. As the copolyester, a part of the C _2-4 alkylene glycol among the structural units of the poly C _2-4 alkylene arylate may be replaced with a polyoxy C _2-4 alkylene glycol, a C _6-10 alkylene glycol, an alicyclic diol (cyclohexane Dimethanol, hydrogenated bisphenol A, etc., diol having an aromatic ring (9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene having a fluorenone side chain), bisphenol A, bisphenol A-alkylene oxide adduct, etc. ) And copolyesters in which part of the aromatic dicarboxylic acid is substituted with an asymmetric aromatic dicarboxylic acid such as phthalic acid and isophthalic acid, and an aliphatic C _6-12 dicarboxylic acid such as adipic acid. It is. Polyester resin, polyarylate resin, aliphatic polyester using aliphatic dicarboxylic acid such as adipic acid, ε-
Lactone homo- or copolymers such as caprolactone are also included. In the wet spinodal decomposition method, a preferable polyester resin is usually an amorphous copolyester (for example, a C _2-4 alkylene arylate copolyester or the like).

As the polyamide resin, nylon 4
6, nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, and other aliphatic polyamides, dicarboxylic acids (eg, terephthalic acid, isophthalic acid, adipic acid, etc.) and diamines (eg, hexamethylene diamine, meta (Xylylenediamine), and homo- or copolymers of lactams such as ε-caprolactam. The polyamide resin is not limited to a homopolyamide, but may be a copolyamide.

Among the cellulose derivatives, cellulose ester
Examples of the fatty acids include aliphatic esters (eg, cellulose diester).
Cellulose such as acetate and cellulose triacetate
Acetate: cellulose propionate, cellulose
Butyrate, cellulose acetate propionate, cellulose acetate
C such as Lurose acetate butyrate_1-6Organic carbo
Acid esters), aromatic esters (cellulose lids)
Rate, C such as cellulose benzoate_7-12Aromatic mosquito
Rubonic acid ester) and the like. Cellulose induction
The body contains cellulose carbamates (eg, cellulose
Sphenylcarbamate), cellulose ethers
(Eg, cyanoethyl cellulose; hydroxyethyl
Hydrate such as cellulose and hydroxypropyl cellulose
Roxy C _2-4Alkyl cellulose; methyl cellulose,
C such as ethyl cellulose_1-6Alkyl cellulose;
Ruboxylmethylcellulose or its salt, benzylcellulo
And acetylalkylcellulose).

Preferred resins include, for example, styrene resins, (meth) acrylic resins, vinyl ester resins,
Examples include vinyl ether resins, halogen-containing resins, alicyclic olefin resins, polycarbonate resins, polyester resins, polyamide resins, cellulose derivatives, silicone resins, and rubbers or elastomers. In the wet spinodal decomposition method, a plurality of resins are usually non-crystalline and soluble in an organic solvent (especially a common solvent capable of dissolving a plurality of resins), in particular, moldability or film-forming properties, Highly transparent or weather-resistant resin, for example,
Styrene-based resins, (meth) acrylic resins, alicyclic olefin-based resins, polyester-based resins, cellulose derivatives (such as cellulose esters) and the like are used.

A plurality of resins can be constituted by a combination of a first resin and a second resin. The first resin and the second resin may be constituted by a single resin, respectively, or may be constituted by a plurality of resins. You may comprise. For example, in wet spinodal decomposition, the first resin is a cellulose derivative (cellulose esters such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate,
Cellulose C such as cellulose acetate butyrate
_2-4 alkyl carboxylic acid esters), the second
Is a styrene resin (polystyrene, styrene-
Acrylonitrile copolymer, etc.), (meth) acrylic resin (polymethyl methacrylate, etc.), alicyclic olefin resin (such as a polymer containing norbornene as a monomer),
Polycarbonate resin, polyester resin (such as the above poly C _2-4 alkylene arylate copolyester)
And so on.

The ratio of the first resin to the second resin is, for example, the former / the latter = about 10/90 to 90/10 (weight ratio), preferably about 20/80 to 80/20 (weight ratio). More preferably, it is about 30/70 to 70/30 (weight ratio), particularly about 40/60 to 60/40 (weight ratio). When a sheet is formed of three or more resins, the content of each resin is usually 1 to 90% by weight (for example, 1 to 70% by weight, preferably 5 to 70% by weight, and more preferably 10 to 70% by weight. To 70% by weight).

The glass transition temperature of the resin is, for example, -10
0 ° C to 250 ° C, preferably -50 to 230 ° C, more preferably about 0 to 200 ° C (for example, 50 to 180 ° C)
Degree). In addition, in view of strength and rigidity of the sheet, at least one of the constituent resins has a glass transition temperature of 50 ° C. or more (for example, 70 to 200 ° C.).
Degree), preferably 100 ° C. or higher (for example, 100 to 1
(Approximately 70 ° C.). In the dry spinodal decomposition method, the glass transition temperature of the constituent resin is 250 ° C. or less (for example, 70 ° C.) from the viewpoint of sheet formability.
To 200 ° C.), preferably 200 ° C. or less (eg, 80
１８０180 ° C.). The weight average molecular weight of the resin can be selected, for example, from 1,000,000 or less (about 10,000 to 1,000,000), preferably from about 10,000 to 700,000.

The light scattering sheet (transmission type light scattering sheet)
It has a phase separation structure composed of a plurality of resins. The phase-separated structure may be a sea-island structure (a phase structure in which particle components such as resin particles are dispersed in a matrix resin), but the light-scattering sheet is usually used in an atmosphere (particularly about 10 to 30).
(At room temperature of about ° C)). The bicontinuous phase structure is sometimes called a bicontinuous structure or a three-dimensionally continuous or connected structure, and means a structure in which a plurality of constituent resin phases are continuous (for example, a network structure).
The preferred light scattering sheet only needs to have at least a co-continuous phase structure, and has a bi-continuous phase structure and a droplet phase structure (a phase structure in which one phase independent or isolated from a matrix phase is dispersed in a droplet form). (Ie, an intermediate structure between the bicontinuous phase structure and the droplet phase structure). In the spinodal decomposition, when a bicontinuous phase structure is formed with the progress of phase separation, and further phase separation proceeds,
The continuous phase becomes discontinuous due to its own surface tension, and becomes a droplet phase structure (sea-island structure of an independent phase such as a sphere and a true sphere). Therefore, depending on the degree of phase separation, an intermediate structure between the bicontinuous phase structure and the droplet phase structure, that is, a phase structure during the transition from the bicontinuous phase to the droplet phase can be formed. In the present invention, the intermediate structure is also referred to as a co-continuous phase structure. When the phase separation structure is a mixed structure of a bicontinuous phase structure and a droplet structure, the ratio of the droplet phase (independent resin phase) is, for example, 30% or less (volume ratio), preferably 10% or less (volume ratio). (Volume ratio). The shape of the bicontinuous phase structure is not particularly limited, and may be a network, particularly a random network.

The bicontinuous phase structure generally has reduced anisotropy in the plane of the layer or sheet and is substantially isotropic. In addition, isotropic means that the average inter-phase distance of the co-continuous phase structure is substantially equal in any direction in the sheet plane.

The bicontinuous phase structure usually has regularity in the inter-phase distance (distance between the same phases). Therefore, as for the light incident on the sheet, the transmitted scattered light is directed in a specific direction by Bragg reflection. Therefore, even if the scattered light is mounted on the reflective liquid crystal display device, the transmitted scattered light can be directed in a certain direction, and the display screen can be highly brightened.

The average inter-phase distance of the co-continuous phase in the light scattering sheet is, for example, 0.5 to 20 μm (for example, 1 to 20 μm).
μm), preferably 1 to 15 μm (for example, 1 to 10 μm).
m). If the average inter-phase distance is too small, it is difficult to obtain a high scattered light intensity, and if the average inter-phase distance is too large, the directivity of the transmitted scattered light is reduced.

The average inter-phase distance of the co-continuous layer can be calculated from a photomicrograph (a transmission microscope, a phase contrast microscope, a confocal laser microscope, etc.) of the light scattering layer or the light scattering sheet. Also, the scattering angle θ at which the scattered light intensity is maximized
May be measured, and the average inter-phase distance d of the co-continuous phase may be calculated from the following equation of the Bragg reflection condition.

2d · sin (θ / 2) = λ (where d is the average interphase distance of the co-continuous phase, θ is the scattering angle,
(λ indicates the wavelength of light) The light scattering sheet having the co-continuous phase structure has a feature that the transmitted light scattering intensity is maximized at a specific scattering angle. Therefore, when the light scattering sheet is used, not only high light transmission and scattering properties can be obtained, but also transmission and scattering light can be highly directed, and both high light transmission and scattering properties and directivity can be achieved. Compared to a light scattering sheet whose light scattering intensity shows a Gaussian distribution, when the transmission type light scattering sheet of the present invention is used, incident light is substantially isotropically scattered, and the transmitted scattered light has a specific direction [for example, Scattering angle θ1 = 1-60 ° (for example, 3-60 °), preferably 2-40 ° (for example, 5
To 30 °), more preferably 10 to 20 °], and shows directivity.

Therefore, in designing a reflection type liquid crystal display device, a liquid crystal cell having a scattering function therein and the light scattering sheet are combined to adjust the required visual field characteristics and the scattering angle at which the light scattering intensity is maximized. Thus, the external light and / or the light source of the front light can be efficiently used for the brightness of the display surface.

The light-scattering sheet may be formed of the light-scattering layer alone, and may be a transparent support (base sheet or film).
And a light-scattering layer laminated on at least one surface of the transparent support.

As the resin constituting the transparent support (substrate sheet), the same resin as the light scattering layer can be used. As a resin constituting a preferable transparent support, for example, a cellulose derivative (cellulose triacetate (TA)
C), cellulose acetates such as cellulose diacetate), polyester resins (polyethylene terephthalate (PET), polybutylene terephthalate (P
BT), polyarylate resin, etc.), polysulfone resin (polysulfone, polyethersulfone (PES))
Etc.), polyetherketone resins (polyetherketone (PEK), polyetheretherketone (PEE)
K)), polycarbonate resin (PC), polyolefin resin, cyclic polyolefin resin, halogen-containing resin, (meth) acrylic resin, styrene resin (such as polystyrene), vinyl ester or vinyl alcohol resin (polyvinyl alcohol) Etc.). The transparent support may be uniaxially or biaxially stretched, such as a uniaxially or biaxially stretched PET (polyethylene terephthalate) sheet, but is preferably optically isotropic. When a dry spinodal decomposition method is used, a sheet having high heat resistance can be used as a transparent support serving as a base.

A preferred transparent support is a support sheet or film having a low birefringence. Optically isotropic transparent supports include, for example, polyesters (PET, PBT, etc.), cellulose esters, especially cellulose acetates (cellulose acetate such as cellulose diacetate, cellulose triacetate, cellulose acetate propionate, cellulose). Examples thereof include a sheet or a film formed of cellulose acetate (C _3-4 organic acid ester such as acetate butyrate).

It is preferable that the light scattering sheet is basically a sheet having no retardation unlike the retardation film. In particular, since the light scattering sheet has the light scattering sheet disposed on the back surface of the polarizing plate, the phase difference is preferably close to zero.

Therefore, even when a transparent support (base film) is used, retardation (R = Δn × d, R: retardation, Δn: sheet birefringence, d: sheet thickness) representing the phase difference (A sheet made of polysulfone resin (such as PES) or cellulose ester (such as TAC)) is preferably used. In addition, even when the base uses a uniaxially stretched PET sheet having a phase difference or the formed light-scattering sheet has a phase difference, the alignment axis thereof is made coincident with the polarization axis of the polarizing plate, and the light is diffused on the back surface of the polarizing plate. By installing the light scattering sheet, the light scattering sheet can be used without impairing displayability.

The thickness of the light scattering layer or the light scattering sheet is not particularly limited and can be selected from a range of about 1 to 500 μm, for example, 0.5 to 300 μm, preferably 1 to 10 μm.
0 μm (for example, 10 to 100 μm), more preferably 1 to 50 μm (for example, 5 to 50 μm, particularly 10 to 5 μm).
0 μm). In order to improve the clarity of display, it is advantageous that the thickness of the light scattering sheet is as small as possible. When the light scattering sheet is composed of a transparent support and a light scattering layer, the thickness of the light scattering layer is, for example, 1 to 1.
It may be about 100 μm, preferably about 5 to 50 μm, and more preferably about 10 to 30 μm.

The light scattering sheet is made of various additives such as stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), plasticizers, coloring agents (dyes and pigments), flame retardants, It may contain an inhibitor, a surfactant and the like. Also,
Various coating layers, for example, an antistatic layer, an antifogging layer, a release layer, and the like may be formed on the surface of the light scattering sheet, if necessary.

The total light transmittance of the light scattering sheet is, for example,
About 70 to 100%, preferably about 80 to 100%,
More preferably, it is about 90 to 100%. The total light transmittance can be measured by a haze meter (NDH-300A) manufactured by Nippon Denshoku Industries Co., Ltd.

[Spinodal Decomposition Method] The bicontinuous phase structure is formed by spinodal decomposition from a liquid phase containing a plurality of resins (a liquid phase at room temperature, for example, a mixed solution or solution) or a solid phase (for example, a solid resin composition). Can be formed.

In the wet spinodal decomposition, the bicontinuous phase structure is usually formed by spinodal decomposition through evaporation of a solvent using a composition (for example, a mixture or solution) containing a plurality of resins and liquid at room temperature. it can. Since such a light scattering layer is formed from a liquid phase, it has a uniform and fine bicontinuous phase structure. More specifically, the light scattering sheet is obtained by casting the mixed solution on a peelable support, evaporating a solvent in the mixed solution, causing spinodal decomposition to induce phase separation, and forming a light having a bicontinuous phase structure. It can be obtained by forming and fixing a scattering layer, and peeling the light scattering layer from the peelable support. Further, the light scattering sheet composed of the transparent support and the light scattering layer, the mixed solution is applied to a transparent support, the solvent in the mixed solution is evaporated, and phase separation is induced by spinodal decomposition, The light scattering layer can be obtained by laminating the light scattering layer on a transparent support (transparent substrate sheet) using a method of forming and fixing a bicontinuous phase structure, or a lamination method such as adhesion.

The above-mentioned mixture is usually used as a dispersion, particularly as a solution in which the resin is dissolved in a common solvent (particularly a homogeneous solution). The common solvent only needs to be able to dissolve each resin,
For example, water, alcohols, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, halogenated carbons, esters, ethers, ketones, cellosolves, cellosolve acetates, sulfoxides, Amides and the like can be exemplified, and the solvent may be a mixed solvent.

After casting or coating the mixture, the mixture is heated to a temperature lower than the boiling point of the solvent (for example, 1 to 1 lower than the boiling point of the solvent).
The solvent can be evaporated at a temperature of 20 ° C., preferably 5 to 50 ° C., especially about 10 to 50 ° C.) to induce phase separation of a plurality of resins and spinodal decomposition. Evaporation of the solvent, for example, 30 ~ 100 ℃, depending on the boiling point of the solvent,
Preferably, it can be carried out by drying at a temperature of about 40 to 80 ° C.

The concentration of the solute (resin) in the mixture is, for example, 1 to 40% by weight, preferably 2 to 30% by weight (for example, 2 to 20% by weight), and more preferably about 3 to 15% by weight. And usually about 5 to 25% by weight.

The bicontinuous phase structure formed by spinodal decomposition can be fixed by solidification or cooling to a temperature lower than the glass transition temperature of the constituent resin (for example, lower than the glass transition temperature of the main resin).

Incidentally, in order to prevent or suppress the dissolution or swelling of the transparent support by the solvent, a solvent-resistant coating agent is applied in advance to the coated surface of the transparent support, and an optically isotropic solvent-resistant coating layer is formed. It is useful to form When a mixed solution or a coating solution containing a plurality of resins is applied to the transparent support, a solvent that does not dissolve, erode, or swell the transparent support may be selected according to the type of the transparent support.

In the dry spinodal decomposition, an at least isotropic bicontinuous phase structure can be formed by subjecting a composition composed of a plurality of resins to sheet molding and spinodal decomposition. Further, in the dry spinodal decomposition, a plurality of resins having phase dependency (or compatibility) having a temperature dependency that changes with temperature can be used. The temperature dependence of phase separation is based on the high-temperature phase-separated type (LCST) type, which is compatible at low temperatures and incompatible at high temperatures.
ion temperature) coexistence system (composite resin system), low temperature phase separation type (incompatible at low temperature and compatible at high temperature) (upper critical solution (UCST) type, upper critical solution
temperature). Preferably, it is LCST type phase separation.

When a plurality of resins form an LCST type or UCST type coexistence system, the lower limit or upper limit critical solution temperature (compatibility / incompatibility critical temperature) is determined by the ambient temperature at which the light scattering sheet is used. It is higher, for example, about 50 to 300 ° C, preferably about 70 to 250 ° C, more preferably about 80 to 250 ° C (for example, 100 to 220 ° C), and usually about 80 to 230 ° C. A composite resin containing a soft resin (silicone resin, rubber, elastomer, or the like) usually shows UCST-type compatibility in many cases.

In the combination of a plurality of resins, the combination of the first resin and the second resin is not particularly limited. For example, when the first resin is a styrene-based resin (polystyrene, styrene-acrylonitrile copolymer, or the like), the second resin is a polycarbonate-based resin, a (meth) acryl-based resin, a vinyl ether-based resin, rubber, an elastomer, or the like. It may be. As a resin system capable of forming a bicontinuous phase structure, a polycarbonate resin / polymethyl methacrylate system is also known. Further, as the LCST type composite resin system, styrene-acrylonitrile copolymer (AS resin) / polymethyl methacrylate system, AS
Resin / poly (ε-caprolactone) type, polyvinylidene fluoride / isotactic polyethyl methacrylate type, polymethyl methacrylate / polyvinyl chloride type and the like can also be mentioned. As the UCST type composite resin system, polystyrene / polymethylphenylsiloxane system, polybutadiene / styrene-butadiene copolymer (SBR) system, A
S resin / acrylonitrile-butadiene copolymer (NB
R) type.

The temperature dependence of the compatibility was determined by LCST,
Since it depends on UCST, glass transition temperature, resin molecular weight, etc., an appropriate combination of resins can be easily selected by experiment.

The dry spinodal decomposition may be performed on a heat-resistant transparent support (such as a polymer sheet) to improve the strength. That is, after coating the resin composition on a heat-resistant transparent support and drying it or laminating it by melt lamination or the like, the solid phase coating layer is heated to a temperature at which it is decomposed by spinodal, and then quenched by rapid cooling. A scattering sheet may be obtained.

[0085]

According to the present invention, in the reflection type liquid crystal display device having the light scattering layer in the liquid crystal cell, the light scattering sheet and the polarizing plate are combined, so that the viewing angle can be enlarged and the brightness of the display screen can be increased. Can be improved. In particular, since the light scattering sheet is used, the display screen can be kept bright even in a dark environment. Further, since it is only necessary to dispose the light scattering sheet, it is possible to provide a reflection type liquid crystal display device which can scatter light at a wide angle at low cost without requiring a large change of the production line and cost.

[0086]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 The reflection type liquid crystal display device shown in FIG. 1 was manufactured as follows. As the polarizing plate 1, a film obtained by laminating a protective film (triacetyl cellulose) on the front and back surfaces of a uniaxially stretched polyvinyl alcohol film on which iodine was adsorbed was used. Note that one surface of the polarizing plate 1 is coated with an adhesive 11, and the other surface is a general polarizing plate that has been roughened or surface-treated.

The first electrode plate 3 is a glass plate (1 mm thick)
The transparent electrode 31 is formed of an indium tin oxide thin film. The second electrode plate 5 is a glass plate (1 m thick).
m), the light-reflective electrode 51 having an uneven surface is formed of a light-reflective mirror-finished aluminum thin film. The first electrode plate 3 and the second electrode plate 5 are opposed to each other,
Liquid crystal is sealed between the liquid crystal and the reflective electrode 51.

The light scattering sheet 2 is made of polymethyl methacrylate (PMMA, manufactured by Mitsubishi Rayon Co., Ltd., “BR88”,
(Refractive index: 1.49) 50 parts by weight and a styrene-acrylonitrile copolymer (SAN, manufactured by Daicel Chemical Industries, Ltd.)
"080", refractive index 1.55) and 50 parts by weight in a methylene chloride / methanol mixed solvent, and
cast on a PES sheet of μm (Sumitomo Chemical Co., Ltd.)
After drying, a coating sheet having a thickness of 115 μm was obtained. Next, the sheet was heat-treated at 230 ° C. for 10 minutes, subsequently immersed in cold water, and then sufficiently dried. Observation of the obtained sheet with a transmission microscope revealed that the sheet had a bicontinuous phase structure, and the average correlation distance of the continuous phase was about 6 μm. The total light transmittance was 93%. A vinyl acetate-based pressure-sensitive adhesive was applied to the surface side of the layer exhibiting a bicontinuous phase structure in this sheet, and dried.

Then, as shown in FIG. 1, the light scattering sheet 2 was adhered on the first electrode plate 3. Further, the polarizing plate 1 was stuck on the light scattering sheet 2 to produce the reflection type liquid crystal display device shown in FIG.

When this reflection type liquid crystal display device was driven under the illumination of a fluorescent lamp, an angle of 70 ° with respect to the vertical direction of the display surface was obtained.
A bright and identifiable display screen up to ° was confirmed. Also,
When the display screen was confirmed in a dark environment with no direct light and only scattered light, a brighter display screen was observed than in the case without the light scattering sheet.

Example 2 A reflection type liquid crystal display device shown in FIG. 2 was produced by disposing a retardation film 6 on the light scattering sheet 2 in the device obtained in Example 1.

Then, when this reflective liquid crystal display device was driven under illumination of a fluorescent lamp, a display screen which could be distinguished brightly up to an angle of 70 ° with respect to the vertical direction of the display surface was confirmed. In addition, when the display screen was checked in a dark environment with no direct light and only scattered light, a brighter display screen was observed than in the case without the light scattering sheet.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a reflection type liquid crystal display device of the present invention.

FIG. 2 is a schematic sectional view showing another example of the reflection type liquid crystal display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Polarizer 11 ... Adhesive 2 ... Light scattering sheet 21 ... Adhesive 3 ... First electrode plate 31 ... Transparent electrode 4 ... Liquid crystal layer 5 ... Second electrode plate 51 ... Reflective electrode 6 ... Retardation film

Claims (7)

[Claims] A first electrode plate located on a light incident side and having a transparent electrode; and a first electrode plate disposed opposite to the first electrode plate.
And a second electrode plate having a light reflecting electrode having an uneven surface,
A liquid crystal material sealed between these electrode plates;
1. A reflection type liquid crystal display device comprising: a polarizing plate provided on the front side of the electrode plate; and a light scattering sheet provided between the polarizing plate and the first electrode plate. 2. The reflection type liquid crystal display device according to claim 1, wherein a light scattering sheet and a phase difference plate are provided between the first electrode plate and the polarizing plate. 3. The reflective liquid crystal display device according to claim 1, wherein the light scattering sheet has a phase separation structure composed of a plurality of resins having different refractive indexes. 4. The reflection type liquid crystal display device according to claim 1, wherein the light scattering sheet is composed of a plurality of resins having different refractive indexes from each other and has at least an isotropic bicontinuous phase structure. 5. The reflection type liquid crystal display device according to claim 1, wherein the difference in refractive index between the plurality of resins constituting the light scattering sheet is 0.01 to 0.2. 6. The light-scattering sheet is a sheet that scatters incident light isotropically, has a maximum scattered light intensity at a scattering angle of 3 to 60 °, and has a total light transmittance of 70 to 100%. The reflective liquid crystal display device according to claim 1. 7. The reflection type liquid crystal display device according to claim 1, wherein the light scattering sheet is made of a plurality of resins having different refractive indexes from each other, and has at least an isotropic bicontinuous phase structure by spinodal decomposition.