JP2001117089A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device capable of reduction of its power consumption, thickness and weight, which has high brightness and visibility and can be easily manufactured at low costs. SOLUTION: The reflection type liquid crystal display device provided with a liquid crystal cell having a liquid crystal layer formed between two transparent substrates having electrodes and a reflection layer is provided with a transmission type diffraction layer consisting of a cholesteric liquid crystal phase.

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 reflective liquid crystal display device incorporating a transmission type diffractive layer or film made of cholesteric liquid crystal.

[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, since the thin and light weight features of the liquid crystal display device are greatly utilized, expectations for market expansion as a display of a portable information terminal device are increasing. Since such a portable device is usually driven by a battery, it is important to reduce power consumption.
Therefore, a reflective liquid crystal display device that does not require a backlight that consumes a large amount of power, and in particular, a reflective liquid crystal display device having a reflective plate with high contrast and high display quality, has low power consumption, is thin, and is lightweight. It is attracting attention as a portable liquid crystal display device that can be used. In a reflection type liquid crystal display device, since a display is performed by light from a viewer side (indoor light or external light such as sunlight) without a backlight, improvement in brightness is strongly demanded. In recent years, in order to solve these problems, it is possible to reduce light loss by using one polarizing plate, which was conventionally required two sheets (T. Sonehara et al., JAPAN D.
ISPLAY, 192 (1989)), a fine structure is provided on the surface of a reflector to collect incident light (JP-A-9-258219), and a specular reflector and a diffusion film are combined (T. Uchida et al., Asia).
Display95, p599 (1995)), and a technique using a reflection hologram having a light condensing function (JP-A-10-142424) are reported. However, with the method of reducing the number of polarizing plates used or the method of combining a specular reflector and a diffusion film, although the brightness is improved, the effect is not sufficient, and the surface of the reflector has a fine structure. And the method using a reflection hologram have a problem that the cost increases and the productivity decreases as compared with the case where a conventional reflector is used.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reflection type liquid crystal display device which can be reduced in power consumption, thinned and lightened, and which can be easily manufactured at low cost with high brightness and high visibility. To provide a liquid crystal display device.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a cholesteric liquid crystal element provided in a liquid crystal cell having a liquid crystal layer provided between two transparent substrates having electrodes and a reflection type liquid crystal display device having a reflection layer or a reflection plate. The above-mentioned problems pointed out in the conventional reflection type liquid crystal display device are solved by providing a transmission type diffraction layer comprising:

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to the present invention includes a liquid crystal cell having a liquid crystal layer provided between two transparent substrates having electrodes, a reflection layer, and a transmission type diffraction element layer. The two transparent substrates having electrodes used in the liquid crystal cell have no particular restrictions on the materials of the electrodes and the transparent substrate. Both a transparent substrate and an electrode used in a known driving liquid crystal cell capable of controlling a liquid crystal layer at the time of screen display can be used. The liquid crystal layer of the liquid crystal cell is formed of a liquid crystal material, but the material is not particularly limited. Various low-molecular liquid crystal substances, high-molecular liquid crystal substances, and mixtures thereof used for preparing various known driving liquid crystal cells can be used as materials for forming the liquid crystal layer of the present invention.
A dye, a chiral agent, or the like can be added to such a liquid crystal material as long as the liquid crystallinity is not impaired. The liquid crystal cell of the present invention has a GH (Guest Host) system, a TN (Twist
ed Nematic), STN (Super Twisted Nematic), ECB (Electrically Controlled Birefringence)
System, IPS (In-Plane Switching) system, VA (Vertica
l Alignment), OCB (Optically Compensated Bir
efringence), HAN (Hybrid Aligned Nematic), halftone gray scale, domain division, or display using ferroelectric liquid crystal or antiferroelectric liquid crystal. There is no particular limitation on the driving method of the liquid crystal cell.
Simple matrix method used for LCD, etc., and TF
T (Thin Film Transistor) electrode, MIM (Metal Insulat)
or an active matrix method using an active electrode such as a TFD (Thin Film Diode) electrode or a plasma addressing method. However, it goes without saying that, depending on the adopted method, a component specific to the method is added to the liquid crystal cell.

The material of the reflection layer (reflection plate) provided in the reflection type liquid crystal display device of the present invention is not limited as long as the light reflectance required for the reflection type liquid crystal display device can be obtained. Preferred reflective layers for the present invention include aluminum, silver,
There are metal foils such as gold, chromium, and platinum, oxide films such as magnesium oxide, multilayer films of dielectrics, liquid crystal layers exhibiting selective reflection, and combinations thereof. The reflection surface of the reflection layer may be a flat surface or a curved surface, or may have a processed surface shape. Further, the reflective layer can also serve as one electrode of the liquid crystal cell. The reflective layer may transmit a part of the light. The reflection layer in the reflection type liquid crystal display device of the present invention is usually provided at a position opposite to the viewing side of the liquid crystal cell.

The transmission type diffraction layer incorporated in the reflection type liquid crystal display device of the present invention is formed of cholesteric liquid crystal. The transmission type diffraction layer is different from the transmission type diffraction layer in that a wave represented by light has a geometrical shape behind an obstacle. Refers to a layer that causes a phenomenon that wraps around a shaded area. That is, it refers to a layer that bends straight light. The reflection type liquid crystal display device of the present invention uses the transmission type diffraction layer to improve the brightness and visibility of the reflection type liquid crystal display device. In short, the present invention improves the characteristics by making use of the light-bending property of the transmission-type diffraction layer and making external light necessary for display coincide with the viewing direction. In general, transmission diffraction layers are classified into amplitude diffraction layers and phase diffraction layers. The amplitude type diffraction layer is formed by periodically arranging a uniform member that does not transmit light, such as a long and thin wire, and transmitting light through the member to obtain diffracted light. On the other hand, in the phase type diffraction layer, for example, a substrate having no absorption of light and a periodic groove is provided to change the thickness of the substrate, or a periodic refractive index is provided inside a layer having a uniform thickness. Some distributions are provided. The transmission type diffraction layer made of cholesteric liquid crystal used in the present invention corresponds to the phase type diffraction layer. The diffraction angle in the transmission type diffraction layer of the present invention can be adjusted by adjusting the structure in the layer and the interval of the refractive index distribution, that is, the grating interval. The lattice spacing is not particularly limited, but is usually in the range of 0.6 to 10 μm, preferably 0.8 to 7 μm, and more preferably 1 to 5 μm. The lattice spacing may be uniform in the xy direction or non-uniform, assuming that the thickness direction of the layer is the z direction. The structure of the grating in the transmission type diffraction layer is not particularly limited as long as a diffraction phenomenon occurs, and may be one-dimensional, two-dimensional, or three-dimensional, or may be inclined with respect to the diffraction layer. . Further, these grating intervals and grating structures may be either continuously changed or discontinuously changed in the diffraction layer. The transmissive diffraction layer in the reflection type liquid crystal display device of the present invention is usually arranged as a single layer or multiple layers on the viewing side of the liquid crystal cell. However, in a reflection type liquid crystal display device in which a liquid crystal cell is sandwiched between two polarizing plates, a transmission diffraction layer can be disposed between the liquid crystal cell and the reflection plate. In a reflection type liquid crystal display device in which one polarizing plate is placed on the viewing side of a liquid crystal cell, a transmission type diffraction layer can be located between the liquid crystal cell and the polarizing plate. It is also possible to reverse the positional relationship between the diffraction layer and the polarizing plate.

The most important feature of the present invention is that the transmission type diffraction layer is made of a cholesteric liquid crystal phase. In the cholesteric liquid crystal phase, liquid crystal molecules form a layer and are arranged, and the molecular arrangement of each layer is slightly rotated for each layer, so that the molecular arrangement as a whole has a helical structure. In the cholesteric liquid crystal phase having such a helical structure, the rotation axis of the molecular arrangement is called a helical axis, and one rotation of the molecular arrangement is called a helical pitch.
When light enters the cholesteric liquid crystal phase, the angle formed between the incident light and the liquid crystal molecules differs depending on the position in the helical structure, regardless of the angle of incidence. Elevations occur, which results in light being diffracted. The diffraction direction when light passes through the transmission type diffraction layer made of the cholesteric liquid crystal phase is related to the direction of the helical axis of the cholesteric liquid crystal phase forming the diffraction layer,
For example, if the helical axis is parallel to the plane of the diffraction layer,
Light that is perpendicularly incident on the diffraction layer is diffracted in a helical axis manner. In the reflection type liquid crystal display device of the present invention, the helical axis direction of the cholesteric liquid crystal phase forming the transmission type diffraction layer is a direction in which the liquid crystal phase functions as the transmission type diffraction layer and brings about improvement in brightness and visibility. There are no special restrictions. For example, it may be parallel or perpendicular to the display surface of the reflective liquid crystal display device, or may be inclined. The inclination in the case of inclination may be constant or change, and the change may be continuous or discontinuous. The direction (direction) of the helical axis in the cholesteric liquid crystal phase microscopically refers to the direction of the helical axis in an alignment region (domain) having orientation, but macroscopically, the direction of the helical axis varies. Refers to the orientation of the entire multi-domain phase. The diffraction angle when light passes through a transmission type diffraction layer made of a cholesteric liquid crystal phase having a helical structure depends on the helical pitch of the helical structure. Therefore, the diffraction angle of the transmission type diffraction layer can be easily adjusted by adjusting the helical pitch of the cholesteric liquid crystal phase. The helical pitch of the helical structure is not particularly limited, but is usually 0.6 to 10 μm, preferably 0.8 to 7 μm, and more preferably 1 to 5 μm. The helical pitch may be constant within the cholesteric liquid crystal phase, but may be non-uniform. As a reminder, this helical pitch can be used to create transmissive diffraction layers from cholesteric liquid crystal materials.
It can be easily adjusted by adjusting the alignment conditions such as temperature, adjusting the optical purity of the optically active site of the liquid crystal material, the mixing ratio of the optically active substance, and the like.

In the cholesteric liquid crystal phase forming the transmission type diffraction layer used in the present invention, the alignment state of the liquid crystal molecules does not necessarily have to be fixed, but is preferably fixed. The fixation of the alignment state means that the liquid crystal material showing a specific liquid crystal phase does not disturb the alignment under the conditions where the transmission type diffraction layer is used while maintaining the phase and the alignment exhibited by the liquid crystal. Means a stable state. In the reflection type liquid crystal display device of the present invention, it is desirable that the alignment of the liquid crystal phase is fixed by some means from the viewpoint of ease of production and high practicality. An example of a transmissive diffraction layer in which the alignment state of the cholesteric liquid crystal phase is not fixed is a cell in which a liquid crystal substance capable of forming a cholesteric liquid crystal phase at room temperature is injected between two substrates. The transmission type diffraction layer in which the alignment state of the cholesteric liquid crystal phase is fixed, the liquid crystal material exhibiting the cholesteric liquid crystal phase is formed by raising the liquid crystal phase to a temperature equal to or higher than the glass transition temperature, and then cooled. A liquid crystal material exhibiting a cholesteric liquid crystal phase is formed by holding the liquid crystal material at a temperature at which the liquid crystal phase is exhibited, forming a liquid crystal phase, and then polymerizing the liquid crystal material while maintaining the orientation state of the liquid crystal phase. be able to. In a transmission type diffraction layer in which the orientation state of the cholesteric liquid crystal phase is fixed, the orientation of the cholesteric liquid crystal phase is not particularly uniform in the helical axis and the helical pitch is not evenly spaced in the film thickness direction. A cholesteric liquid crystal film having a fixed state is preferred. In this type of liquid crystal film, the helical axis direction changes continuously or discontinuously, and the helical pitch changes continuously or discontinuously in the film thickness direction. Examples of the cholesteric liquid crystal film having such an alignment state include a film having a steric liquid crystal phase structure with a curved structure, a film having a polydomain structure such as a focal conic structure, and the like. The liquid crystal material as a raw material when obtaining the transmission diffraction layer of the present invention is not particularly limited as long as it has a cholesteric liquid crystal phase in a phase series, and various low-molecular liquid crystal materials, high-molecular liquid crystal materials or These mixtures and the like can be used.

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 layer comprising a cholesteric liquid crystal phase, one or more polarizing plates, one or more optical compensation layers, and a protective layer. , An antireflection film, a prism sheet, a diffusion sheet, a light guide plate, or an adhesive layer or an adhesive layer for adhering them. As the polarizing plate, those commonly used in liquid crystal display devices can be used. The position of the polarizing plate is not particularly limited, but is usually provided on both the viewing side and the reflection side of the liquid crystal cell, or provided only on the viewing side of the liquid crystal cell. In any case, the polarizing plate provided on the viewing side of the liquid crystal cell can be adjacent to the liquid crystal cell, and a transmission diffraction layer or other optical element can be interposed between the liquid crystal cell and the polarizing plate. As the optical compensation layer, for example, a stretched film, a film composed of a nematic liquid crystal phase, a film composed of a discotic liquid crystal phase, and the like can be used. By combining the optical compensation layer and the transmission type diffraction layer, a remarkable visibility improving effect can be imparted to the reflection type liquid crystal display device of the present invention. The stretched film used for the optical compensation layer can be obtained by subjecting a polymer material that can be the material to a known molding process such as stretching, film formation, rolling, drawing, solid extrusion, and blow molding. Film from the nematic liquid crystal phase or discotic liquid crystal phase,
Various transparent plastic films can be used for the protective layer that can be obtained by aligning the substances exhibiting the respective liquid crystal phases to a desired state and then fixing the alignment state as necessary. By providing the protective layer, effects such as surface protection, increase in strength, and improvement in environmental reliability can be obtained. Known prism sheets, diffusion sheets and light guide plates can be used. The method of manufacturing the reflection type liquid crystal display device of the present invention is not particularly limited, and a reflection layer, a transmission type diffraction element layer, and other layers provided as necessary outside the liquid crystal cell assembled by a known method,
A method of forming the layers in a sequence in which a desired layer structure is obtained can be given.

[0011]

Since the reflection type liquid crystal display device of the present invention has a transmission type diffraction layer composed of a cholesteric liquid crystal phase, the display image is brighter and more visible than the conventional reflection type liquid crystal display device. Is also expensive.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto. Example 1 and Comparative Example 1 FIGS. 1 and 2 show two types of reflective GHs schematically showing the layer structure.
A liquid crystal display device was manufactured. As a liquid crystal material, a dye S for liquid crystal manufactured by Mitsui Toatsu Co., Ltd. was added to ZLI-1840 manufactured by Merck.
-428 was dissolved at 2% by weight to obtain a liquid crystal composition. ITO
The liquid crystal composition described above was injected between two substrates (1, 1 ') having a cell gap of 10 μm each provided with a transparent electrode (2, 2'), and a liquid crystal layer 3 was formed. Produced. An aluminum-evaporated reflective plate 4 was attached to the surface of the liquid crystal cell opposite to the viewing side, to produce a reflective GH liquid crystal display device as a comparative example (see FIG. 1). Further, a reflective GH liquid crystal display device in which a transmission type diffraction element 5 made of a cholesteric liquid crystal film having a helical pitch of 1 μm was further adhered on the viewing side surface of the liquid crystal display device was produced (see FIG. 2). The brightness of the display of these two liquid crystal display devices under general illumination was measured by a color luminance meter BM-5A manufactured by Topcon Corporation. The brightness of the liquid crystal display device shown in FIG. 2 is shown in FIG. It was confirmed that the improvement was about 60% as compared with the liquid crystal display device. Example 2 and Comparative Example 2 FIGS. 3 and 4 show two types of reflection type S schematically showing the layer structure.
A TN liquid crystal display device was manufactured. Merck's ZLI-2293 as a liquid crystal material and Merck's C as a chiral agent
-15 was added to a concentration of 2.7% by weight to obtain a liquid crystal composition. Between two substrates (1, 1 ') having a cell gap of 6.2 μm each having an ITO transparent electrode (2, 2'),
The above liquid crystal composition was injected to form a liquid crystal layer 3 to prepare a liquid crystal cell. Polarizing plates (6,
6 ′) was adhered, and the reflective plate 4 was further adhered on the polarizing plate 6 ′ on the side opposite to the viewing side, thereby producing a reflective STN liquid crystal display device having a twist angle of 240 ° shown in FIG. The spiral pitch is 0.8 μm on the viewing side surface of the liquid crystal display device.
Further, a transmission type diffractive element comprising a cholesteric liquid crystal film was further attached to produce a reflective STN liquid crystal display device of the present invention (see FIG. 4). For these two liquid crystal display devices, when the display brightness under general illumination was measured in the same manner as in Example 1, the brightness of the liquid crystal display device shown in FIG.
It was confirmed that the improvement was about 55% as compared with the liquid crystal display device shown in FIG. Example 3 A reflective STN liquid crystal display device whose layer structure was schematically shown in FIG. 5 was produced. Polarizing plates (6, 6 ') are bonded to both sides of a liquid crystal cell produced in the same manner as in Example 2, and a cholesteric liquid crystal film having a helical pitch of 0.8 μm is formed on the polarizing plate 6' on the side opposite to the viewer side. The reflective diffractive layer 5 and the reflective plate 4 were sequentially adhered in this order to produce a reflective STN liquid crystal display device having a twist angle of 240 °. The brightness of the display of this liquid crystal display device under general illumination was measured in the same manner as in Example 1. As a result, it was confirmed that the brightness was improved by about 55% compared to the liquid crystal display device shown in FIG. Example 4 and Comparative Example 3 FIGS. 6 and 7 show two types of reflection type S schematically showing the layer structure.
A TN liquid crystal display device was manufactured. An optical compensation film (7, 7 ') and a polarizing plate (6, 6') are sequentially adhered to both surfaces of the liquid crystal cell produced in the same manner as in Example 2, and a reflecting plate 4 is provided on the polarizing plate opposite to the viewing side. To produce a reflective STN liquid crystal display device having a twist angle of 240 ° shown in FIG. Further, a transmission type diffractive layer made of a cholesteric liquid crystal film having a helical pitch of 3 μm was further adhered on the surface on the viewing side of the liquid crystal display device, thereby producing a reflective STN liquid crystal display device of the present invention (see FIG. 7). . When the brightness of the display under general illumination was measured for these two types of liquid crystal display devices in the same manner as in Example 1, the brightness of the liquid crystal display device shown in FIG. 7 was compared with that of the liquid crystal display device shown in FIG. As a result, it was confirmed that it was improved by about 65%. Example 5 and Comparative Example 4 FIGS. 3 and 4 show two types of reflective T's schematically showing the layer structure.
An N liquid crystal display device was manufactured. Merck's ZLI-4792 as a liquid crystal material and Merck's C-
15 was added so as to be 1.3% by weight to obtain a liquid crystal composition. A liquid crystal layer 3 is formed by injecting the above liquid crystal composition between two substrates (1, 1 ') having a cell gap of 4.8 μm each having an ITO transparent electrode (2, 2'). Was prepared. Polarizing plates (6, 6 ') on both sides of this liquid crystal cell
And a reflection plate 4 is pasted on the polarizing plate 6 'on the side opposite to the viewing side, and a reflection type T having a twist angle of 90 ° shown in FIG.
An N liquid crystal display device was manufactured. Further, a transmission type diffractive layer made of a cholesteric liquid crystal film having a helical pitch of 2 μm was further adhered on the surface on the viewing side of the liquid crystal display device, thereby producing a reflection type TN liquid crystal display device of the present invention (see FIG. 4). . When the brightness of the display under general illumination was measured for these two types of liquid crystal display devices in the same manner as in Example 1, the brightness of the liquid crystal display device shown in FIG. 4 was compared with that of the liquid crystal display device shown in FIG. As a result, it was confirmed that it was improved by about 60%. Example 6 and Comparative Example 4 FIGS. 8 and 9 show two types of reflective TN liquid crystal display devices whose layer configurations are schematically shown. Merck ZL as liquid crystal material
I-4792, C-15 manufactured by Merck as a chiral agent
Was added so as to be 2.0% by weight to obtain a liquid crystal composition. I
A cell 1 having a transparent electrode 2 ″ and a substrate 1 ″ having a reflective electrode 2 ″ made of aluminum were combined with a cell gap 2.2.
μm, and the liquid crystal composition was injected during that time to form a liquid crystal layer 3 to produce a liquid crystal cell. Two optical compensatory films (7, 7 ') are adhered on the viewing side of the liquid crystal cell, that is, on the surface of the substrate 1, and a polarizing plate 6 is further adhered thereon. A reflection type TN liquid crystal display device having an angle of 63 ° was manufactured. Further, a transmission type diffractive element made of a cholesteric liquid crystal film having a helical pitch of 5 μm was further adhered on the viewing side surface of the liquid crystal display device, thereby producing a reflection type TN liquid crystal display device of the present invention (FIG. 9).
reference). When the brightness of the display under general illumination was measured for these two liquid crystal display devices in the same manner as in Example 1, the brightness of the liquid crystal display device shown in FIG. 9 was compared with that of the liquid crystal display device shown in FIG. About 60%. Example 7 and Comparative Example 5 Two types of reflective TN liquid crystal display devices whose layer configurations were schematically shown in FIGS. 8 and 10 were produced. Merck ZLI-4792 as a liquid crystal material and Merck C as a chiral agent
-15 was added to 2.0% by weight to obtain a liquid crystal composition. The substrate 1 provided with the ITO transparent electrode 2 and the substrate 1 "provided with the aluminum reflective electrode 2" face each other with a cell gap of 2.2 [mu] m, during which the above-mentioned liquid crystal composition is injected to form the liquid crystal layer 3. And a liquid crystal cell was fabricated. Two optical compensatory films (7, 7 ') are adhered on the viewing side of the liquid crystal cell, that is, on the surface of the substrate 1, and a polarizing plate 6 is further adhered thereon. A reflection type TN liquid crystal display device having an angle of 63 ° was manufactured. On the other hand, a liquid crystal cell manufactured in the same manner as above was provided with two optical compensation films (7, 7).
7 ′), a transmissive diffraction layer 5 made of a cholesteric liquid crystal film having a helical pitch of 5 μm is pasted thereon, and a polarizing plate 6 is pasted thereon in the same manner as described above. A liquid crystal display device was manufactured (see FIG. 10).
For these two liquid crystal display devices, the display brightness under general illumination was measured in the same manner as in Example 1.
It was confirmed that the brightness of the liquid crystal display device shown in FIG. 8 was improved by about 60% as compared with the liquid crystal display device shown in FIG. Example 8 As the transmission type diffraction layer 5, the helical axis direction is 2 from the film surface.
Except for using a transmissive diffraction layer made of a cholesteric liquid crystal film inclined at 0 °, a reflective liquid crystal display device was prepared in the same manner as in Examples 1 to 7, and the brightness of the display was measured.
Compared to a liquid crystal display device of the same type except that it does not have a transmission type diffraction layer, it is about 70%, about 65%, and about 65%, respectively.
%, About 75%, about 70%, about 70%, and about 70% brightness improvement was confirmed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a layer configuration of a liquid crystal display device of Comparative Example 1.

FIG. 2 is a schematic diagram illustrating a layer configuration of the liquid crystal display device of Example 1.

FIG. 3 is a schematic diagram illustrating a layer configuration of liquid crystal display devices of Comparative Examples 2 and 4.

FIG. 4 is a schematic diagram showing a layer configuration of the liquid crystal display devices of Examples 2 and 5.

FIG. 5 is a schematic diagram illustrating a layer configuration of a liquid crystal display device according to a third embodiment.

FIG. 6 is a schematic diagram illustrating a layer configuration of a liquid crystal display device of Comparative Example 3.

FIG. 7 is a schematic diagram illustrating a layer configuration of a liquid crystal display device of Example 4.

FIG. 8 is a schematic diagram illustrating a layer configuration of the liquid crystal display devices of Comparative Examples 4 and 5.

FIG. 9 is a schematic diagram illustrating a layer configuration of a liquid crystal display device of Example 6.

FIG. 10 is a schematic diagram illustrating a layer configuration of a liquid crystal display device of Example 7.

[Explanation of symbols]

 1, 1 ', 1' ': electrode substrate 2, 2': transparent electrode 2 '': reflective electrode 3: liquid crystal layer 4: reflective plate 5: transmission type diffractive layer composed of a cholesteric liquid crystal film 6, 6 ': polarizing plate 7, 7 ': Optical compensation film

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinichi Komatsu 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Pref. Nishiishi Mitsui Co., Ltd. (72) Inventor Takehiro Toyooka 8 Chidori-cho, Naka-ku, Yokohama-shi, Kanagawa Address: Nishiishi Mitsubishi Co., Ltd.

Claims (2)

[Claims] 1. A reflection type liquid crystal display device comprising a liquid crystal cell having a liquid crystal layer provided between two transparent substrates having electrodes, a reflection layer, and a transmission type diffraction layer made of cholesteric liquid crystal. 2. The reflection type liquid crystal display device according to claim 1, wherein the lattice spacing of the transmission type diffraction layer made of cholesteric liquid crystal is in the range of 0.6 to 10 μm.