JP2001004987A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device which is bright and has high visibility and which can be easily produced at a low cost by assembling a liquid crystal cell having a liquid crystal layer formed between electrode substrates, a reflection layer, and a transmission type diffraction element layer consisting of a cholesteric liquid crystal film having a region showing diffractive performance in a part. SOLUTION: The reflection type liquid crystal display device is equipped with a liquid crystal cell having a liquid crystal layer formed between two electrode substrates facing each other, a reflection layer and a transmission type diffraction element layer consisting of a cholesteric liquid crystal film in which specific cholesteric alignment is fixed. The cholesteric liquid crystal film which constitutes the transmission type diffraction element layer has a region showing diffractive performance in a part of the film. The region showing diffractive performance means a region having an effect to allow the light transmitting through the region or reflected by the region to propagate into a region which is geometrically a shadow region. The region having the diffractive performance can be recognized, for example, by irradiating the objective region with laser light or the like and observing whether the light is straightly transmitted or reflected or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bright and highly visible reflection type liquid crystal display device having a transmission type diffraction element layer.

[0002]

2. Description of the Related Art The use of liquid crystal display devices has expanded from calculators to word processor and personal computer displays due to the remarkable improvement in display performance. Furthermore, expectations for market expansion as displays for portable information terminal equipment, which can make full use of the thin and lightweight features of liquid crystal display devices, are increasing. For portable applications, since it is usually driven by a battery, it is important to reduce power consumption. For this reason, a liquid crystal display device for portable use requires a reflective type liquid crystal display device that does not require a backlight that consumes a large amount of power, and in particular, a type having a reflective plate with high contrast and high display quality has low power consumption. It can be made thinner, thinner and lighter, and is attracting attention.

In a reflection type liquid crystal display device, display is performed by light from a viewer side (indoor light or external light such as sunlight) without using a backlight. Therefore, improvement in brightness is strongly demanded. In recent years, in order to solve these problems, a single polarizing plate, which was conventionally required two, suppresses light loss. A fine structure is provided on the surface of the reflecting plate to collect incident light. And a diffusion film, and using a reflection hologram having a light condensing function.

However, of the above techniques, the method of reducing the number of polarizing plates or the combination of a specular reflection plate and a diffusion film can improve brightness, but the effect is not sufficient, and the surface of the reflection plate is not sufficiently effective. The method of providing a fine structure and the method of using a reflection hologram have a problem of an increase in cost and a decrease in productivity as compared with the case of using a conventional reflector.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises a transmission type diffractive element layer made of a cholesteric liquid crystal film having a specific orientation fixed, thereby providing a bright, high visibility, and We have invented a reflective liquid crystal display element which can be manufactured easily at low cost.

[0006]

That is, the first aspect of the present invention is as follows.
Is a reflective liquid crystal display comprising at least a liquid crystal cell having a liquid crystal layer formed between two opposing electrode substrates, a reflective layer and a transmissive diffractive element layer composed of a cholesteric liquid crystal film partially having a diffractive region. Related to the element.

A second aspect of the present invention relates to the reflective liquid crystal display device further comprising one or more polarizing layers. Further, the third aspect of the present invention relates to the reflective liquid crystal display device further including one or more optical compensation layers.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The reflection type liquid crystal display element of the present invention is a transmission type diffraction element layer comprising a liquid crystal cell having a liquid crystal layer formed between two opposing electrode substrates, a reflection layer and a cholesteric liquid crystal film having a specific cholesteric alignment fixed. And

The electrode substrate is not particularly limited, and a known electrode substrate for controlling a material exhibiting liquid crystallinity as a liquid crystal layer at the time of screen display can be used, and the object of the present invention can be achieved. If it is, there is no particular limitation.

The liquid crystal layer can be formed by filling the material having the liquid crystal property between the electrode substrates and disposing the material. The material exhibiting liquid crystallinity is not particularly limited, and examples thereof include ordinary low-molecular liquid crystals, high-molecular liquid crystals, and mixtures thereof that can form various liquid crystal cells. Dyes, chiral agents, and the like can be added to these as long as the liquid crystallinity is not impaired.

The liquid crystal cell may include, in addition to the electrode substrate and the material exhibiting liquid crystal properties, various components necessary for forming various types of liquid crystal cells described below.

The type of the liquid crystal cell is not particularly limited. For example, a GH (Guest Host) type, a TN (T
wisted nematic), STN (Super Twisted Nemati)
c) Method, ECB (Electrically Controlled Birefring)
ence), IPS (In-Plane Switching), VA
(Vertical Alignment) method, OCB (Optically Comp
ensated birefringence method, HAN (Hybrid Aligne)
d Nematic) method, halftone gray scale method,
Various methods such as a domain division method, a display method using a ferroelectric liquid crystal, and an antiferroelectric liquid crystal can be given.

There is no particular limitation on the driving method of the liquid crystal cell. A simple matrix method used for STN-LCDs and the like, a TFT (Thin Film Transistor) electrode, an MIM
(Metal Insulator Metal) electrode and TFD (Thin
Any driving method such as an active matrix method using an active electrode such as a film diode (electrode) or a plasma addressing method may be used.

The reflective layer provided in the reflective liquid crystal display element of the present invention is not particularly limited as long as it has a sufficiently high reflectance.
Examples thereof include metals such as gold, chromium and platinum, oxides such as magnesium oxide, dielectric multilayer films, liquid crystal films exhibiting selective reflection, and combinations thereof. These reflective layers may be flat or curved. Further, it may also serve as an electrode on the electrode substrate on the side opposite to the viewing side. The reflective layer may be not only a layer that does not transmit light but only reflects light but also a semi-transmissive layer that partially transmits light.

The position of the reflection layer in the reflection type liquid crystal display device of the present invention is not particularly limited as long as it is usually provided at a position opposite to the viewing side of the liquid crystal layer.
Next, the cholesteric liquid crystal film constituting the transmission type diffractive element layer has a region exhibiting diffractive ability in a part of the film. Here, the region exhibiting the diffractive power means a region which produces an effect such that the light transmitted through the region or the light reflected by the region wraps around a portion which is geometrically shadow. The presence or absence of a region having a diffractive ability is confirmed by, for example, the presence or absence of light (higher-order light) emitted at a certain angle other than light (0th-order light) that enters a laser beam or the like into the above-mentioned region and transmits or reflects linearly. can do. Alternatively, whether or not the region is formed can be confirmed by observing the surface shape or cross-sectional shape of the liquid crystal layer using an atomic force microscope, a transmission electron microscope, or the like.

Such a cholesteric liquid crystal film is not particularly limited as long as the cholesteric orientation is fixed and at least a part of the film has a region exhibiting a diffractive ability. It can be formed from molecular liquid crystals or a mixture thereof. The region exhibiting diffractive ability may be any region on the film surface and / or inside the film. For example, a region having a part of the film surface (film surface region) and a part of the film inside (film internal region) may be used. Good. In addition, the region may be provided in a plurality of regions of the cholesteric liquid crystal film, for example, a film front and back surface region and a plurality of film internal regions. Further, the region exhibiting diffractive power is not necessarily required to be formed as a layer having a uniform thickness on the film surface or inside, for example, and the region is formed on at least a part of the film surface or inside the film. It should just be. Further, when there are a plurality of regions exhibiting diffractive power, it is not necessary that all the regions exhibit the same diffractive power, and each region may exhibit a different diffractive power. The orientation state of the region exhibiting diffractive power is such that the helical axis orientation is not uniformly parallel to the film thickness direction, preferably the helical axis orientation is not uniformly parallel to the film thickness direction, and the helical pitch is the film pitch. It is desirable to form a cholesteric alignment that is not uniformly spaced in the thickness direction. In other regions, a helical structure in which the helical axis orientation is uniformly parallel to the film thickness direction and the helical pitch is uniformly spaced uniformly in the film thickness direction is the same as the normal cholesteric orientation. It is desirable to form. In the present invention, the film surface means a portion of the cholesteric liquid crystal film alone which comes into contact with the outside, and the inside of the film means a portion other than the portion which comes into contact with the outside.

In the present invention, any of the above cholesteric liquid crystal films can be used, but from the viewpoint of the film production method, the method of imparting diffractive power, etc., at least a part of the film surface region, preferably the entire surface of the film surface region. A cholesteric liquid crystal film having a region exhibiting a diffractive ability can be suitably used as a transmission type diffraction element layer. In addition, when one of the film surface regions has a diffractive power, the front and back surfaces of the film, that is, a film surface having a diffractive power and a film surface having a slightly different optical effect from the opposite surface. Thus, the arrangement position and the like on the reflective liquid crystal display device of the present invention can be selected according to the application and the intended function. Further, when the region exhibiting the diffractive ability is formed in a layer state, the thickness of the layer (region) exhibiting the diffractive ability is usually 70% or less, preferably 50% or less with respect to the film thickness of the cholesteric liquid crystal film.
%, More preferably 30% or less. If the thickness of the layer (region) exhibiting the diffraction ability exceeds 70%, the effect of the present invention may not be obtained.

The above-mentioned cholesteric liquid crystal film constituting the transmission type diffractive element layer which is a component of the present invention comprises:
A cholesteric alignment film having cholesteric alignment fixed using a polymer liquid crystal or a low molecular weight liquid crystal or a mixture thereof is prepared in advance, and a diffraction element substrate is bonded to the cholesteric alignment film, and heat and / or pressure is applied to the alignment film. Method of transferring the diffraction pattern of the diffraction element substrate onto the substrate, or using the diffraction element substrate as an alignment substrate to cholesterically align a polymer liquid crystal or a low-molecular liquid crystal or a mixture thereof, and then fixing the liquid crystal while maintaining its alignment state. According to the method, a cholesteric liquid crystal film having a region exhibiting diffractive ability in a part of the film can be obtained.

The material of the diffraction element substrate used for the transfer of the diffraction pattern may be a material such as a metal or a resin, or a material having a diffraction function on the film surface, or a thin film having a diffraction function on the film. Any material may be used as long as it has a diffractive function, such as a material obtained by transferring the same. Above all, in view of ease of handling and mass productivity, a film or a film laminate having a diffraction function is more desirable.

The term "diffraction element" as used herein includes, as its definition, all diffraction elements that generate diffracted light, such as an original flat hologram. The type may be a diffraction element derived from the surface shape, a so-called film thickness modulation hologram type, or a phase element independent of the surface shape or a surface shape converted into a refractive index distribution, a so-called refraction. A rate modulation hologram type may be used. In the present invention, the type of the film thickness modulation hologram is more preferably used because the diffraction pattern information of the diffraction element can be more easily given to the liquid crystal. In addition, any type of refractive index modulation can be suitably used in the present invention as long as it has undulations that cause diffraction in the surface shape.

As a method of transferring a diffraction pattern, for example, generally used heat rollers, laminators,
Using a hot stamp, an electric heating plate, a thermal head, or the like, it can be performed under pressure and heating conditions. The conditions of pressurization and heating differ depending on the physical properties of the polymer liquid crystal and low-molecular liquid crystal to be used, the type of the diffraction element substrate, and the like, and cannot be unconditionally determined, but are usually 0.01 to 100 MPa, preferably 0.1 to 100 MPa. It is appropriately selected depending on the type of liquid crystal, substrate and the like used in the range of 0.05 to 80 MPa and the temperature of 30 to 400 ° C, preferably 40 to 300 ° C.

The polymer liquid crystal used as the film material of the cholesteric liquid crystal film is not particularly limited as long as the cholesteric orientation can be fixed, and any of a main chain type and a side chain type polymer liquid crystal can be used. . Specifically, polyester, polyamide, polycarbonate,
A main-chain type liquid crystal polymer such as polyesterimide, or a side-chain type liquid crystal polymer such as polyacrylate, polymethacrylate, polymalonate, or polysiloxane is exemplified. Among them, a liquid crystalline polyester which has good orientation in forming cholesteric orientation and is relatively easy to synthesize is desirable. Preferred examples of the constituent units of the polymer include an aromatic or aliphatic diol unit, an aromatic or aliphatic dicarboxylic acid unit, and an aromatic or aliphatic hydroxycarboxylic acid unit.

The low-molecular liquid crystal used as a film material of the cholesteric liquid crystal film is, for example, a compound having a basic skeleton of a biphenyl derivative, a phenylbenzoate derivative, a stilbene derivative, etc., into which a functional group such as an acryloyl group, a vinyl group or an epoxy group is introduced. Is mentioned. As the low-molecular liquid crystal, both lyotropic properties and thermotropic properties can be used, but those exhibiting thermotropic properties are more preferable from the viewpoint of workability, process and the like.

In order to form a cholesteric alignment film having a cholesteric alignment fixed without a region exhibiting a diffractive ability, a known method, for example, when a high molecular liquid crystal is used, a high molecular liquid crystal is arranged on an alignment substrate. After that, a method may be used in which a cholesteric liquid crystal phase is developed by heat treatment or the like, and the state is rapidly cooled to fix the cholesteric alignment. When using a low-molecular liquid crystal,
After disposing a low-molecular liquid crystal on an alignment substrate, a method of expressing a cholesteric liquid crystal phase by heat treatment or the like and fixing the cholesteric alignment by cross-linking with light, heat or electron beam while maintaining that state is appropriately adopted. can do. In addition, as described above, by using a diffraction element substrate or the like as the alignment substrate, a cholesteric liquid crystal film in which a region exhibiting diffractive ability is formed in the alignment stage can be obtained.

In order to improve the heat resistance and the like of the finally obtained cholesteric liquid crystal film, for example, a bisazide compound or glycidyl methacrylate is used as long as the cholesteric phase is not impaired in the polymer liquid crystal or low molecular liquid crystal used as the film material. And the like, and by adding these cross-linking agents, cross-linking can be performed while a cholesteric phase is developed. Further, various additives such as dichroic dyes, dyes, and pigments may be appropriately added to the high-molecular liquid crystal and the low-molecular liquid crystal as long as the effects of the present invention are not impaired.

The structure of the transmission type diffractive element layer, which is a component of the present invention, usually comprises one layer of a cholesteric liquid crystal film as described above. In addition, a configuration in which a plurality of cholesteric liquid crystal films are laminated according to the application and required optical characteristics, etc., and a single layer of a cholesteric liquid crystal film or a single layer of a cholesteric alignment film or the like which does not have a region exhibiting a diffractive ability. Alternatively, a configuration in which a plurality of layers are stacked may be employed. When two or more cholesteric liquid crystal films and cholesteric alignment films having no diffractive area are laminated, two or more cholesteric liquid crystal films and cholesteric alignment films may be alternately laminated.

The thickness of the cholesteric liquid crystal film constituting the transmission type diffraction element layer is usually 0.3 to 20 μm, preferably 0.5 to 10 μm, more preferably 0.7 to 3 μm.
μm. If the ratio is out of this range, the effects of the present invention may not be effectively exhibited. The diffraction angle in the region showing the diffractive power of the film can be adjusted, for example, by adjusting the type of the diffractive element substrate to which the diffraction pattern is transferred or the interval of the refractive index distribution in the region showing the diffractive power inside the film. . The diffraction angle is not particularly limited, but is usually in the range of 5 ° to 80 °, preferably 10 ° to 70 °, and more preferably 15 ° to 60 °. Further, the diffraction angle may be uniform in the region or may be different depending on the location in the region. The lattice structure of the cholesteric liquid crystal film in the region exhibiting the diffractive ability is not particularly limited as long as a diffraction phenomenon occurs, and may be one-dimensional, two-dimensional, or three-dimensional.
It may be inclined with respect to the film surface. Further, these diffraction angles and grating structures may be either continuously changed or discontinuously changed in the film.

The cholesteric liquid crystal film used in the present invention preferably has a wavelength band of cholesteric selective reflection of usually 30 to 150 nm, and a central wavelength of cholesteric selective reflection is usually 380 to 380.
A visible region of 780 nm, preferably 420 to 700 nm,
Or 800 to 2000 nm, preferably 850 to 11
The number of spiral turns in the cholesteric orientation is usually 2 or more, preferably 2.2 or more, particularly preferably 2.5 or more. The ratio is usually 15% or more, preferably 20% or more and 90% or more.
%, Particularly preferably 30% or more and 80% or less. Here, the wavelength bandwidth of the cholesteric selective reflection referred to in the present invention is a wavelength at which the reflectance by selective reflection becomes 70% or more when circularly polarized light in the same direction as the twist direction of the liquid crystal molecules forming the cholesteric alignment is incident. Means range. The diffusivity of the cholesteric liquid crystal film in the present invention is defined as the ratio of the specular reflection removal reflectance (SCE) to the specular reflection reflectance (SCI) ((SCE / SCI) × 1).
00). The regular reflection-inclusive reflectance (SCI) refers to the total reflectance when an object to be measured is uniformly illuminated by diffuse illumination. The specular reflection elimination reflectance (SCE) refers to a diffusion (consisting of a component of light diffused on the surface of the object to be measured) excluding a regular reflection light component from a total reflectance when the object to be measured is uniformly illuminated by diffuse illumination. It means the reflectance (total reflectance = specular reflectance + diffuse reflectance). These regular reflection removal reflectance and regular reflection-inclusive reflectance are based on JIS-Z-8.
722 can be determined by measuring according to “Method for measuring color—reflective and transmissive objects”. As a specific measuring method, a measuring instrument having a d / 8 (diffuse illumination 8 ゜ light receiving) illumination / light receiving optical system, for example, a spectrophotometer C manufactured by Minolta Co., Ltd.
It can be measured using M-3500d.

The position of the transmission type diffraction element layer in the reflection type liquid crystal display element of the present invention is not particularly limited, but may be, for example, between the reflection layer and the liquid crystal layer and / or on the viewing side of the liquid crystal layer. It can be arranged at any position on the viewing side of the reflective layer. Specifically, when the reflective liquid crystal display element of the present invention does not have a polarizing layer, it is desirable to provide one or more layers on the viewing side of the liquid crystal layer and / or between the liquid crystal layer and the reflective layer. On the other hand, when the reflective liquid crystal display element of the present invention has a polarizing layer, it is desirable to provide one or more layers outside the polarizing layer and / or between the liquid crystal layer and the polarizing layer on the viewing side of the reflective layer.

The reflection type liquid crystal display device of the present invention comprises, in addition to a liquid crystal cell, a reflection layer and a transmission type diffraction element layer, at least one polarizing layer, at least one optical compensation layer, a protective layer, an antireflection film,
Other components such as a prism sheet, a diffusion sheet, a light guide plate, or an adhesive layer or a pressure-sensitive adhesive layer for bonding them may be included.

The polarizing layer is not particularly limited as long as the object of the present invention can be achieved, and a normal layer used for a liquid crystal display device can be used. The arrangement position when the polarizing layer is provided in the reflective liquid crystal display element of the present invention,
It may be arranged directly in contact with the outer surface of the liquid crystal cell, or may be arranged separately from the surface of the electrode substrate via a transmission diffraction element layer or another layer.

As the optical compensation layer, a known material such as a stretched polymer film, one using a nematic liquid crystal substance, and one using a discotic liquid crystal substance can be used. By providing the optical compensation layer in the reflection type liquid crystal display element of the present invention, a more remarkable visibility improving effect can be obtained by combination with the transmission type diffraction element layer.

The protective layer is not particularly limited, and various plastic films and the like can be used. By providing a protective layer, effects such as surface protection, increase in strength, and improvement in environmental reliability can be obtained.

The prism sheet, the diffusion sheet and the light guide plate are not particularly limited, and known ones can be provided in the reflection type liquid crystal display device of the present invention. The method for producing the reflective liquid crystal display device of the present invention is not particularly limited, and a reflective layer, a transmission type diffractive element layer and other layers provided as necessary may be provided outside the liquid crystal cell assembled by a known method. And the like in the order in which the layer structure is obtained. The method for obtaining each of the layers is not particularly limited, and can be obtained by appropriately employing a known method.

In order to obtain a stretched polymer film as an optical compensation layer, a polymer material is stretched, formed, rolled, drawn, solid extruded, blow-molded, vapor-deposited, and the like, and subjected to a known molding method. Can be. As a compensation layer using a liquid crystal material, a liquid crystal material including a nematic liquid crystal material or a discotic liquid crystal material was oriented in a desired state such as nematic alignment, twisted nematic alignment, cholesteric alignment, hybrid alignment, or twisted hybrid alignment. Thereafter, it can be obtained by a method of fixing by the same method as the fixing of the alignment in the cholesteric liquid crystal film described above, or the like.

[0036]

EXAMPLES Examples will be described below, but the present invention is not limited to these examples.

Reference Example 1 51 mmol of terephthalic acid,
Hydroxybenzoic acid 21 mmol, catechol 21 mm
ol, (R) -2-methyl-1,4-butanediol 7
mmol and 100 mg of sodium acetate in a nitrogen atmosphere at 180 ° C. for 1 hour, 200 ° C. for 1 hour, 25
The polycondensation reaction was performed while the temperature was raised stepwise at 0 ° C. for 1 hour.

Next, the polycondensation reaction was continued at 250 ° C. for 2 hours while flowing nitrogen, and the polycondensation was further performed at the same temperature under reduced pressure for 1 hour. After dissolving the obtained polymer in tetrachloroethane, reprecipitation was performed with methanol to obtain a liquid crystalline polyester.

An N-methyl-2-pyrrolidone solution (20% by weight) of the obtained liquid crystalline polyester was prepared, and the solution was applied to a rubbed polyphenylene sulfide film by a spin coating method. After the application, a drying treatment was performed to remove N-methyl-2-pyrrolidone, and a liquid crystalline polyester coating film was formed on the polyphenylene sulfide film.

Next, the coating film of the liquid crystalline film was
A heat treatment was performed for 5 minutes in a heating atmosphere at a temperature of 5 ° C., and the mixture was cooled to room temperature to obtain a liquid crystalline polyester film on a polyphenylene sulfide film. The film was coated on a UV-visible-near infrared spectrophotometer V-570 manufactured by JASCO Corporation.
When the transmission spectrum was measured at, the center wavelength was about 8
It was confirmed that the film was a cholesteric alignment film having a fixed cholesteric alignment having a selective reflection wavelength band of about 130 nm and a fixed reflection wavelength band of about 130 nm. When the orientation state of the cholesteric alignment film was observed with a polarizing microscope and a transmission electron microscope of the cross section of the film, the helical axis orientation in the cholesteric phase was uniformly parallel to the film thickness direction, and the helical pitch was uniform in the film thickness direction. It was confirmed that the cholesteric orientation was formed at regular intervals.

(Reference Example 2) An adhesive made of a commercially available photocurable acrylic oligomer was applied to the cholesteric alignment surface of the cholesteric alignment film obtained in Reference Example 1 using a bar coater so as to have a thickness of 5 μm. did. Next, a triacetyl cellulose (TAC) film was adhered to the adhesive applied surface of the film using a desktop laminator, and irradiated with ultraviolet rays to cure the adhesive.

After the adhesive is cured, the end of the polyphenylene sulfide film used as the alignment substrate is held by hand, and the polyphenylene sulfide film is peeled and removed in the 180 ° direction at the interface between the film and the cholesteric alignment film. Oriented film / adhesive layer /
The laminated body laminated | stacked in order of the TAC film was obtained.

Next, a diffraction grating film (900 / m
m) and the cholesteric alignment film surface are superposed on each other, and a laminator DX manufactured by Tokyo Laminex Co., Ltd.
Using -350, heating and pressing were performed under the conditions of 120 ° C., 0.3 MPa, and a roll contact time of 1 second (diffraction grating film / cholesteric alignment film / adhesive layer / TAC film). After cooling to room temperature, the diffraction grating film was removed. Observation of the cholesteric alignment film surface on which the diffraction grating film was superimposed revealed that iridescent color caused by the diffraction pattern and selective reflection peculiar to the cholesteric liquid crystal were clearly recognized. Also, when the orientation state of the cholesteric alignment film surface from which the diffraction grating film was removed was observed by a polarizing microscope and a transmission electron microscope of the liquid crystal layer cross section, the helical axis orientation in the cholesteric phase was not uniformly parallel to the film thickness direction. It was also confirmed that cholesteric alignment in which the helical pitch was not uniformly spaced in the film thickness direction was formed in the surface region of the liquid crystal layer. In other regions, it was confirmed that a cholesteric orientation in which the helical axis orientation was uniformly parallel to the film thickness direction and the helical pitch was uniformly uniform in the film thickness direction was formed. When a He-Ne laser (wavelength 632.8 nm) was perpendicularly incident on the cholesteric alignment film surface, laser light was observed at an emission angle of 0 ° and about ± 35 °.

From the above, it was confirmed that a cholesteric liquid crystal film having a region exhibiting diffractive ability in the surface region of the film was obtained. The laminate composed of the cholesteric liquid crystal film / adhesive layer / TAC film was used in the following examples as a transmission type diffraction element substrate.

(Example 1) The cholesteric liquid crystal film surface of the transmission type diffraction element substrate obtained in Reference Example 2 was brought into contact with a commercially available reflective liquid crystal display device so that the cholesteric liquid crystal film surface side was in contact with the display surface of the device. Bonded. When the brightness of the display was measured using a color luminance meter BM-5A manufactured by Topcon under a general illumination of a reflective liquid crystal display device in which the film was bonded to the display surface,
It was confirmed that the brightness was improved by about 60% as compared with the reflection type liquid crystal display device in which the cholesteric liquid crystal film was not bonded.

Example 2 As a liquid crystal material, a liquid crystal dye S-42 manufactured by Mitsui Toatsu Co., Ltd. was added to ZLI-1840 manufactured by Merck.
8 was dissolved at 2% by weight to obtain a liquid crystal composition. The liquid crystal composition was injected between two electrode substrates each having an ITO transparent electrode and having a cell gap of 10 μm to form a liquid crystal layer, thereby producing a liquid crystal cell. An aluminum vapor-deposited reflection plate is attached to the opposite side of the viewing side of the liquid crystal cell, and the cholesteric liquid crystal film side of the transmission type diffraction element substrate obtained in Reference Example 2 is attached to the viewing side of the liquid crystal cell. A GH type liquid crystal display device was manufactured.

When the brightness of the obtained GH type liquid crystal display device was measured in the same manner as in Example 1, it was confirmed that the brightness was greatly improved as compared with the device having no cholesteric liquid crystal film. Was.

Example 3 A liquid crystal material was obtained by adding 2.7% by weight of Merck C-15 as a chiral agent to ZLI-2293 manufactured by Merck as a chiral agent. The liquid crystal composition was injected between two electrode substrates each having an ITO transparent electrode and having a cell gap of 6.2 μm, and a liquid crystal layer was formed to manufacture a liquid crystal cell. A polarizing plate is stuck on both sides of this liquid crystal cell, a reflecting plate is stuck on the polarizing plate opposite to the viewing side, and a TAC film side of the transmission type diffraction element substrate obtained in Reference Example 2 is further stuck on the viewing side. To produce a reflective STN liquid crystal display device having a twist angle of 240 °.

When the brightness of the obtained reflective STN liquid crystal display device was measured in the same manner as in Example 1, it was confirmed that the brightness was greatly improved as compared with the device having no cholesteric liquid crystal film. Was done.

Example 4 A liquid crystal composition was obtained by adding 1.3% by weight of Merck C-15 as a chiral agent to ZLI-4792 manufactured by Merck as a liquid crystal material. The liquid crystal composition was injected between two electrode substrates each having an ITO transparent electrode and having a cell gap of 4.8 μm, and a liquid crystal layer was formed to produce a liquid crystal cell. A polarizing plate is stuck on both sides of the liquid crystal cell, a reflecting plate is stuck on the polarizing plate opposite to the viewing side, and a cholesteric liquid crystal film of the transmission type diffractive element substrate obtained in Reference Example 2 obtained on Reference side 2 on the viewing side. Reflective TN with 90 ° twist angle
A liquid crystal display device was manufactured.

When the brightness of the obtained reflective TN liquid crystal display device was measured in the same manner as in Example 1, it was confirmed that the brightness was significantly improved as compared with the device having no cholesteric liquid crystal film. Was done.

Example 5 A liquid crystal composition was obtained by adding 2.0% by weight of Merck C-15 as a chiral agent to ZLI-4792 manufactured by Merck as a liquid crystal material. An electrode substrate provided with an ITO transparent electrode and an electrode substrate provided with an aluminum reflective electrode were placed at a cell gap of 2.2 μm.
m, the liquid crystal composition was injected between two electrode substrates to form a liquid crystal layer, whereby a liquid crystal cell was manufactured. Two optical compensation layers were stuck on the viewing side of this liquid crystal cell, that is, on the surface on the side of the ITO transparent electrode substrate, and a polarizing plate was stuck thereon. Furthermore, the T of the transmission type diffraction element substrate obtained in Reference Example 2 was placed on a polarizing plate.
Attaching the AC film side, reflection type TN with a twist angle of 63 °
A liquid crystal display device was manufactured.

When the brightness of the obtained reflective TN liquid crystal display device was measured in the same manner as in Example 1, it was confirmed that the brightness was greatly improved as compared with the device having no cholesteric liquid crystal film. Was done.

[0054]

The reflection type liquid crystal display element of the present invention is provided with a transmission type diffraction element layer made of a cholesteric liquid crystal film partially having a region exhibiting a diffractive power, thereby providing a bright, high visibility and low cost. A reflective liquid crystal display element that can be easily manufactured can be obtained.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Ryo Nishimura 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Pref. HA08 HA09 HA10 HA12 KA03 LA16 5C094 AA10 AA43 AA44 BA43 DA13 ED14 ED20 HA08

Claims (3)

[Claims] 1. A reflection device comprising at least a liquid crystal cell having a liquid crystal layer formed between two opposing electrode substrates, a reflection layer, and a transmission type diffraction element layer made of a cholesteric liquid crystal film partially having a region exhibiting diffractive power. Liquid crystal display device. 2. The reflective liquid crystal display device according to claim 1, further comprising one or more polarizing layers. 3. The reflective liquid crystal display device according to claim 1, further comprising at least one optical compensation layer.