JPH1020304A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease an attenuation of light in a transmitting substrate by making a lower substrate a transmitting substrate, an upper substrate a reflecting substrate and providing an electrode for generating lateral electric field performing optical switching by rotating liquid crystal molecules on a part of the transmitting substrate. SOLUTION: A reflecting substrate 101 is stuck to a transmitting substrate 102 through a gap material 118 and liquid crystal is sealed. The reflecting substrate 101 is formed by sticking white paper 105 to a plastic plate 104 and a transparent resin film 106 and an oriented film 107 are provided on the paper. On the transmitting substrate 102, a gate line, a source line and a thin film transistor TFT 111 on their intersection is provided on a glass substrate 108, a pixel electrode 112 and a common electrode 114 are provided and a SiN film 115 and an oriented film 116 are provided on them. An incident light beam is rotated in parallel with the substrate by means of lateral electric field impressed between the pixel electrode 112 and the common electrode 114 and subjected to light intensity modulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type active matrix liquid crystal display device or a liquid crystal display device used as a reflection plate of a reflection type projector.

[0002]

2. Description of the Related Art In recent years, a reflection type liquid crystal display device capable of obtaining a bright image without a backlight has attracted attention. FIG.
1 is a cross-sectional view of a conventional liquid crystal display device used for a reflection type active matrix liquid crystal display device or a reflection plate of a reflection type projector described in JP-A-6-347828, for example. A metal thin film mainly composed of aluminum is provided on the surface of the reflection substrate 201, and a liquid crystal 203 is sealed between the metal thin film and a glass substrate 202 provided with another transparent electrode 224. The aluminum thin film is divided for each pixel, and the voltage applied to each pixel electrode is controlled by a switching element such as a thin film transistor. The voltage for switching the liquid crystal to ON / OFF mode is determined by the transmission substrate
The transparent electrode 224 formed on the entire surface of the substrate 202 and the reflective substrate 201
Between the SiN film 215 and the vertical direction. The light transmitted through the transmission substrate 202 and reflected by the SiN film 215 of the reflection substrate 201 passes through the transmission substrate 202 again. Substrate for transmission
202 includes a polarizing plate 217, a glass substrate 220, a transparent electrode 224, and an alignment film 207. The reflection substrate 201 is a glass substrate
208, a TFT 211, a pixel electrode 212, a SiN film 215, and an alignment film 216. Reference numeral 218 denotes a gap material that seals the liquid crystal 203 between the two substrates and determines the distance between the substrates.

FIG. 8 shows a transmission type active matrix liquid crystal display device in which a voltage to be applied to a liquid crystal is applied by an electrode provided on one of two substrates sandwiching the liquid crystal.
PROCEEDINGS OF THE 15TH INTERNATIONAL DISPLAY RES
The liquid crystal is driven in the in-plane switching mode as described in EARCH CONFERENCE p577.
A lateral electric field 233 parallel to the substrate is generated at the electrode 234 only on the lower substrate, and the liquid crystal molecules 232 are rotated parallel to the substrate to switch between transmitting and blocking light. (a) is the cut-off state,
(b) shows the transmission state. This is called an in-plane switching mode. 230 and 235 are polarizing plates, and 231 is a polarization state. The electrode 234 for turning on / off the liquid crystal is provided in a stripe shape.

[0004]

In the conventional reflection type liquid crystal display device shown in FIG. 7, it is necessary to provide an electrode for turning on / off the liquid crystal on each of the transmission substrate 202 and the reflection substrate 201. Therefore, the light passes twice through the transparent electrode 224 provided on the entire surface of the transmission substrate 202, and is considerably attenuated here. In addition, since the reflection film of the reflection substrate 201 also serves as an electrode for turning on / off the liquid crystal, the material is limited to a conductive metal thin film. Therefore, since reflection occurs in the metal thin film, the reflected light cannot have a paper-like texture. In addition, light is directed to the alignment film 207, the polarizing plate 217, the liquid crystal 203,
After passing through 224, it will not have the same color tone as the incident light,
It was not possible to compensate for a change in color tone because the light was only reflected specularly by the metal thin film. Since the material of the reflection film was limited to a conductive material, it was not possible to obtain a reflectance higher than that of a conventional mirror surface.

An object of the present invention is to provide a reflection type liquid crystal display device in which light attenuation on a transmission substrate is reduced.
It is another object of the present invention to make it possible to use a non-conductive material as the reflection film of the reflection substrate, thereby to obtain a paper-like texture and to compensate for the color tone. Another object is to improve the reflectance of the reflection substrate.

[0006]

The present invention achieves the above object by making the transmission type liquid crystal display device of FIG. 8 a reflection type. That is, the lower substrate in FIG. 8 is a transmission substrate, and the upper substrate is a reflection substrate. LCD ON / OFF
Since the electrode to be formed may be provided only on the lower transmission substrate, the reflection film of the reflection substrate can be used even if it is not conductive.
The transparent electrode for turning on / off the liquid crystal may be provided in a comb shape, and it is not necessary to provide the transparent electrode on the entire surface of the substrate, so that light attenuation at the transparent electrode is reduced.

A reflection type liquid crystal display device according to the present invention comprises: a transmission substrate for transmitting incident light; and a reflection substrate provided in parallel with the transmission substrate at an interval and reflecting light transmitted through the transmission substrate. Liquid crystal molecules sealed at the intervals, and an electrode provided on the transmission substrate and generating a lateral electric field for switching light by rotating the liquid crystal molecules parallel to the transmission substrate. I have.

Further, the reflection surface of the reflection substrate is formed of paper. At that time, a pigment for compensating coloring may be included in the paper.

Further, the reflection surface of the reflection substrate is formed of a thin film containing a phosphor.

Further, the electrode for generating the lateral electric field is formed in an elongated linear shape.

Further, a thin film transistor connected to the electrode is provided on a transmission substrate to control a lateral electric field.

Further, the main body of the reflection substrate is formed of aluminum oxide.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 shows a sectional structure of an embodiment of the reflection type liquid crystal display device of the present invention. Plate-shaped object 101 serving as a reflection substrate and plate-shaped object serving as a transmission substrate
The liquid crystal 103 is sealed in the space between the two. The gap is determined by a gap material 118 made of spherical plastic.
Plastic plate 104
Paste white paper 105 on top and thin transparent resin thin film 106
And an alignment film 107 coated. The plate-like substrate 102 serving as a transmission substrate has a gate line 109 and a source line 110 on a glass substrate 108, and a thin film transistor TFT111 at an intersection thereof, and a pixel electrode 112 made of Cr connected to the TFT 111 and made up of Cr. The one provided with a common electrode 114 made of Cr connected to the common wiring 113 and coated with a SiN film 115 and an orientation film 116 is used.

FIG. 2 shows a plan view of one pixel of the plate-like object 102 serving as a transmission substrate. A TFT 111 is arranged at an intersection of a gate line 109 and a source line 110 which are orthogonal to each other on a glass substrate 104. A gate line 109 is connected to the gate of the TFT, and a source line 110 is connected to the source of the TFT. A striped pixel electrode 112 is connected to the drain of the TFT. Gate line 10
9 and a common electrode 113 formed in a comb shape so that a uniform electric field is applied between the pixel electrode 112 and the common electrode 114.
112 and a common electrode 114 are arranged. The distance between the pixel electrode 112 and the common electrode 114 is 5 to 20 μm.

A polarizing plate 117 is attached to a surface of the plate-shaped material serving as the transmission substrate 102 which is not in contact with the liquid crystal. The two substrates are bonded together via a spherical gap material 118 for controlling the gap, and the liquid crystal is sealed. A terminal plate for introducing an output of an IC or the like is attached to the terminal portion of the transmission substrate after the two substrates are bonded. The liquid crystal is oriented as shown in FIG. 8, and when the incident light passes through the liquid crystal portion, the pixel electrode 112 and the common electrode 11
The light is rotated in parallel to the substrate by the transverse electric field applied between them, and undergoes modulation of its light intensity. Merck on the LCD
ZLI-2806 manufactured by the company is used. The voltage applied to the liquid crystal is applied for a time given to a specific pixel, and is held until a voltage is written to the pixel next time.

Since the pixel electrode 112 and the common electrode 114 are only formed by a comb-shaped elongated line on a part of the surface of the transparent substrate, the attenuation of light by passing through them is caused by the transparent electrode covering the entire surface of the substrate. It is significantly less than the conventional device of FIG. 7 which has been formed. Since the reflective substrate 101 is not provided with an electrode for turning on and off the liquid crystal 103, the reflective substrate and the reflective surface can be formed of a material having no conductivity at all, which increases the degree of freedom in manufacturing the device and increases the manufacturing cost. Can be reduced. In FIG. 1, the manufacturing cost can be reduced because a plastic material is used for the base of the reflection substrate. FIG.
In this case, since the reflection surface is formed by coating the paper 105 with a transparent resin, the irregular reflection component of the reflected light can be increased as compared with the conventional apparatus, and a paper-like texture can be obtained.

Embodiment 2 FIG. FIG. 3 shows a sectional structure of one embodiment of the reflection type liquid crystal display device of the present invention. A liquid crystal 103 is sealed in a gap between a plate-shaped object 101 serving as a reflection substrate and a plate-shaped object 102 serving as a transmission substrate. As the plate-shaped substrate serving as the reflection substrate 101, an opaque alumina (aluminum oxide) substrate 119 provided with an alignment film 107 is used. As the transmissive substrate 102, a glass substrate having the same configuration as that of the first embodiment shown in FIG. 2 is used. Pixel electrode 11
Cr is used as the material of 2 and the common electrode 114. Reflective substrate 10
1 can be composed of a single alumina substrate 119 except for the alignment film 107, so that the structure is simplified.

Embodiment 3 FIG. 4 shows a sectional structure of another embodiment of the reflection type liquid crystal display device of the present invention. A liquid crystal 103 is sealed in a gap between a plate-shaped object serving as a reflection substrate 101 and a plate-shaped object 102 serving as a transmission substrate.
As the plate-shaped substrate serving as the reflection substrate 101, a substrate provided with an aluminum thin film 121 on a glass substrate 120 and a transparent resin thin film 106 and an alignment film 107 provided thereon is used. As a plate-shaped substrate 102 serving as a transmission substrate, the same substrate as that of the first embodiment shown in FIG.

Embodiment 4 FIG. 5 shows a sectional structure of another embodiment of the reflection type liquid crystal display device of the present invention. A liquid crystal 103 is sealed in a gap between a plate-shaped object 101 serving as a reflection substrate and a plate-shaped object 102 serving as a transmission substrate.
Plastic plate 104
A thin film 122 containing a phosphor is coated thereon, and a thin transparent resin thin film 106 and an alignment film 107 are coated thereon. The phosphor is phosphorescent phosphor ZnC.
dS: Cu is used. As the plate-shaped member 102 serving as a transmission substrate, the same one as in Embodiment 1 of FIG. 2 is used on a glass substrate. Since the thin film containing the phosphor is used as the reflection surface, the reflectance increases.

Embodiment 5 FIG. 6 shows a sectional structure of another embodiment of the reflection type liquid crystal display device of the present invention. A liquid crystal 103 is sealed in a gap between a plate-shaped object 101 serving as a reflection substrate and a plate-shaped object 102 serving as a transmission substrate.
Plastic plate 104
A paper 123 is adhered on top, and a thin transparent resin thin film 106 and an alignment film 107 are coated thereon. The paper 123 contains a pigment so as to compensate for coloring caused by the liquid crystal, the alignment film, and the polarizing plate. The color compensation is performed so that the chromaticity of the reflected light becomes x = 0.33 and y = 0.33 on the chromaticity diagram. As a plate-shaped substrate 102 serving as a transmission substrate, the same substrate as that of the first embodiment shown in FIG. Light is polarizing plate 117
, Alignment films 107 and 116, liquid crystal 103, transparent electrodes 112 and 114
Even when the color is transmitted and the color tone becomes different from that of the incident light, it can be compensated by the pigment contained in the paper 123.

[0021]

In the reflection type liquid crystal display device according to the first aspect of the present invention, an electrode for generating a lateral electric field for switching light by rotating liquid crystal molecules is formed only on a part of the transmission substrate. Therefore, light attenuation by the electrodes is small and a bright image can be obtained.

In the reflection type liquid crystal display device according to the second aspect of the present invention, since the reflection surface of the reflection substrate is formed of paper, the irregular reflection component of the reflected light is increased, and a paper-like texture can be obtained.

In the reflection type liquid crystal display device according to the third aspect of the present invention, since the pigment for compensating for coloring is contained in the paper, even when the color is transmitted when light is transmitted through the transmission substrate or the liquid crystal, it is compensated. can do.

In the reflection type liquid crystal display device according to a fourth aspect of the present invention, since the reflection surface of the reflection substrate is formed of a phosphor,
The reflectivity increases.

In the reflection type liquid crystal display device according to the fifth aspect of the present invention, since the electrodes for generating the lateral electric field are elongated and linear, the attenuation of light by the electrodes is reduced and a bright image is obtained.

In the reflection type liquid crystal display device according to a sixth aspect of the present invention, since the thin film transistor connected to the electrode for generating the lateral electric field is provided on the transmission substrate, active matrix driving becomes possible, and the proximity portion in the same substrate can be driven. Can apply different lateral voltages.

In the reflection type liquid crystal display device of the present invention, since the main body of the reflection substrate is formed of aluminum oxide, the configuration of the reflection substrate is simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a reflection type liquid crystal display device of the present invention.

FIG. 2 is a plan view illustrating one pixel of the transmission substrate of FIG. 1;

FIG. 3 is a sectional view showing another embodiment of the reflection type liquid crystal display device of the present invention.

FIG. 4 is a sectional view showing another embodiment of the reflection type liquid crystal display device of the present invention.

FIG. 5 is a sectional view showing another embodiment of the reflection type liquid crystal display device of the present invention.

FIG. 6 is a sectional view showing another embodiment of the reflection type liquid crystal display device of the present invention.

FIG. 7 is a cross-sectional view illustrating an example of a conventional reflective liquid crystal display device.

FIG. 8 is a cross-sectional view showing the principle of a conventional in-plane switching mode using a lateral electric field.

[Explanation of symbols]

101 reflective substrate, 102 transmissive substrate, 103 liquid crystal, 104
Plastic board, 105 white paper, 106 transparent resin thin film, 107
Alignment film, 108 glass substrate, 109 gate line, 110
Source line, 111 TFT, 112 pixel electrode, 113 common wiring, 114 common electrode, 115 SiN film, 116 alignment film, 117 polarizing plate, 118 gap material, 119 alumina substrate, 120 glass substrate, 121 aluminum thin film,
122 Phosphor-containing membrane, 123 paper

Claims (7)

[Claims] 1. A transmissive substrate that transmits incident light, a reflective substrate that is provided parallel to the transmissive substrate at an interval and reflects light transmitted through the transmissive substrate, and a liquid crystal sealed at the interval. Molecules and a part of the transmissive substrate,
A reflection type liquid crystal display device comprising: an electrode for generating a lateral electric field for switching light by rotating the liquid crystal molecules in parallel with the transmission substrate. 2. The reflection type liquid crystal display device according to claim 1, wherein the reflection surface of the reflection substrate is formed of paper. 3. The reflective liquid crystal display device according to claim 2, wherein a pigment for compensating for coloring is included in the paper. 4. The reflection type liquid crystal display device according to claim 1, wherein the reflection surface of the reflection substrate is formed of a thin film containing a phosphor. 5. The reflection type liquid crystal display device according to claim 1, wherein the electrode for generating the lateral electric field is formed in an elongated linear shape. 6. The reflection type liquid crystal display device according to claim 1, wherein a thin film transistor connected to the electrode is provided on a transmission substrate to control a lateral electric field. 7. The reflection type liquid crystal display device according to claim 1, wherein a main body of the reflection substrate is formed of aluminum oxide.