JPH1020283A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the display luminance of the reflection type liquid crystal display device of color display. SOLUTION: This device is provided with a transparent substrate 11 where a first transparent electrode 15 related to liquid crystal driving is formed on an upper surface and a reflection substrate 12 where a color filter 13 and a second transparent electrode 14 are successively formed on the upper surface. In this case, the transparent substrate 11 and the reflection substrate 12 are arranged so as to make the first transparent electrode 15 and the second transparent electrode 14 opposed, and polymer-dispersed liquid crystal 16 formed by sealing liquid crystal 16B in high polymer 16A is sealed between the first transparent electrode 15 and the second transparent electrode 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device, and more specifically, to a PDA (Personal Digital Display).
Assistant), a display device such as a portable information terminal such as a portable personal computer, and a portable game machine, and the like, and relates to an improvement in display brightness of a reflective liquid crystal display device of a color display.

[0002] A conventional color liquid crystal display device is a TN (Twis).
Since a ted Nematic) mode liquid crystal is used, a color filter is built in, and a backlight is required, the power consumption is large, and there is a problem in incorporating it into a portable device. Therefore, attempts have been made to perform color display using a reflective liquid crystal display device that does not require a backlight.

[0003]

2. Description of the Related Art A reflection type liquid crystal display device for color display according to a conventional example will be described below with reference to FIG. As shown in FIG. 2, the reflection type liquid crystal display device has a first ITO film (7) serving as a liquid crystal driving electrode,
Are sequentially formed, a first transparent substrate (1) having a first polarizing plate (3) formed on the back surface, and a color filter (5) and an electrode for driving a liquid crystal on the upper surface. Second I
A TO film (6) and a second alignment film (8) are sequentially formed, and a second transparent substrate (2) on which a second polarizing plate (4) is formed on the back surface forms a first and a second transparent substrate. Are arranged so as to face each other, and a liquid crystal (10) of a TN (Twisted Nematic) mode is sealed therebetween.

According to this reflection type liquid crystal display device, the light (LG) incident from the upper surface receives the first polarizing plate (3), the first transparent substrate (1), the first ITO film (7), After sequentially passing through the first alignment film (9), the liquid crystal (10), the second alignment film (8), the second ITO film (6), the color filter (5), and the second transparent substrate (2). ) To reach the second polarizing plate (4).

The light (LG) is reflected by the second polarizing plate (4), and is again returned to the second transparent substrate (2), the color filter (5), the second ITO film (6), and the second alignment film. (8),
The liquid crystal (10), the first alignment film (9), the first ITO film (7), and the first transparent substrate (1) are sequentially transmitted and emitted from the first polarizing plate (3). Is recognized by the observer.

[0006]

However, in the above-mentioned conventional reflection type liquid crystal display device, a TN mode liquid crystal generally used as a liquid crystal is used. Polarizing plates (3, 4) were required.
Since the transmittance of a polarizing plate is 50% or less, which is commonly used, when light passes through the polarizing plate, its brightness becomes dark. Therefore, there has been a problem that the entire display screen of the display device becomes dark.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional disadvantages. As shown in FIG. 1, as shown in FIG. And a reflective substrate on which a color filter and a second transparent electrode are sequentially formed. The transparent substrate and the reflective substrate are arranged such that the first transparent electrode and the second transparent electrode face each other. Are disposed, and a polymer dispersed liquid crystal in which a liquid crystal is sealed in a polymer is sealed between the first transparent electrode and the second transparent electrode. This problem is solved by a reflective liquid crystal display device for color display.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. This liquid crystal display device is a reflective liquid crystal display device that does not require a backlight, and is a PDA.
And portable information terminals such as portable personal computers and portable game machines, which are required to be driven with low power consumption.

As shown in FIG. 1, a transparent substrate (11) on which a first ITO film (15) serving as a liquid crystal driving electrode is formed on an upper surface thereof, and a color filter (13) on an upper surface thereof. , A second ITO film (1
4) has a reflective substrate (12) formed sequentially,
The transparent substrate (11) and the reflective substrate (12) are arranged such that the ITO film (15) and the second ITO film (14) face each other, and a liquid crystal (16) is sealed between them. Is what is done.

As shown in FIG. 1, the encapsulated liquid crystal (16) is a polymer-dispersed liquid crystal () formed by dispersing a minute spherical nematic liquid crystal (16B) in a polymer film (16A). Polymer diffusion liquid cryst
al) is used. In the polymer-dispersed liquid crystal, the liquid crystal molecules of the nematic liquid crystal (16B) are not scattered and do not transmit light when no electric field is applied, and the liquid crystal molecules are oriented in the direction of the electric field and transmit light when an electric field is applied. Therefore, light can be blocked / transmitted without the need for a polarizing plate.

According to the reflection type liquid crystal display device of the present embodiment, light (LG) incident from the upper surface is applied to the transparent substrate (1).
1), the first ITO film (15), the polymer dispersed liquid crystal (16), the second ITO film (14), and the color filter (13) are transmitted, reflected by the reflective substrate (12), and then returned to the color filter. (13), the second ITO film (14), the polymer-dispersed liquid crystal (16), the first ITO film (15), and the transparent substrate (11) are sequentially transmitted, and are emitted from the transparent substrate (11). The observer recognizes this as a display image.

At this time, since the light (LG) does not pass through a polarizing plate having a transmittance as low as 50% or less as in the conventional TN mode liquid crystal display device, a decrease in luminance is small. Therefore, it is possible to obtain a brighter image display as compared with a reflection type liquid crystal display device using a conventional TN mode liquid crystal. Note that, in the present embodiment, applications such as a PDA, a portable information terminal such as a portable personal computer, and a portable game machine are described. However, the present invention is not limited to this, and can be used for low power consumption driving. If it is applied, the same effect can be obtained regardless of the application.

[0013]

As described above, according to the reflection type liquid crystal display device of the present invention, the transparent substrate on which the first transparent electrode for driving the liquid crystal is formed, the color filter, A transparent substrate having a reflective substrate on which a second transparent electrode is sequentially formed, the transparent substrate and the reflective substrate being arranged such that the first transparent electrode and the second transparent electrode face each other; Since the polymer dispersed liquid crystal in which the liquid crystal is sealed in the polymer is sealed between the second transparent electrode and the second transparent electrode,
Since light can be shielded / transmitted without the need for a polarizing plate, the display image is dark because the polarizing plate is provided. This is brighter than a reflection type liquid crystal display device using a conventional TN mode liquid crystal. Image display can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a reflective liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a structure of a reflective liquid crystal display device according to a conventional example.

[Explanation of symbols]

(11) Transparent substrate (12) Reflective substrate (13) Color filter (14) Second ITO film (second transparent electrode) (15) First ITO film (first transparent electrode) (16) Polymer dispersion Liquid crystal (16A) Polymer (16B) Nematic liquid crystal (LG) Light

Claims (1)

[Claims] 1. A transparent substrate having a first transparent electrode for driving liquid crystal formed on an upper surface thereof, and a reflective substrate on which a color filter and a second transparent electrode are sequentially formed on the upper surface. The transparent substrate and the reflective substrate are disposed so that the first transparent electrode and the second transparent electrode face each other, and a polymer is disposed between the first transparent electrode and the second transparent electrode. A reflection type liquid crystal display device for color display, characterized in that a polymer dispersion type liquid crystal in which a liquid crystal is sealed is sealed in a liquid crystal display device.