JPS59116615A - Color display device - Google Patents

Abstract

PURPOSE:To form a color display which is bright and is easy to see by utilizing the layer of an optically active material having a characteristic to scatter selectively visible light of a specific wavelength. CONSTITUTION:A display body layer 3 (a liquid crystal controllable of a transparent mode and a scattering mode, or a ferrodielectric transparent ceramic) is sandwiched between a transparent substrate 1 provided with segment electrodes 4 and a transparent substrate 2 provided with a counter electrode 5. An optically active material layer (cholesteric polymer film) 6, and a specular reflection plate 7 are disposed in this order behind the layer 3 thereby forming a display panel. If a material which scatters electively, for example, green light and allows the transmission of red purple light is used for the layer 6, the above-mentioned panel is capable of displaying a bright green color on the background of a white color which is slightly greenish.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color display device, and more particularly, to a color display device using a polymer film having a property of selectively scattering light of a specific wavelength in the visible range.

Conventionally, color display devices that combine twisted nematic liquid crystals and color polarizing plates have been known. Since this display device uses a polarizing plate, the amount of light decreases and it becomes dark, and since there is no fully functional color polarizing plate yet, similar colors appear on areas other than the color display, resulting in low visual contrast. There was a drawback. Deaf guest-host type liquid crystal display devices are also known, but because the two-color ratio of the pigment is not sufficient, the contrast is low, and the display and non-display areas are of similar color, resulting in poor visual contrast. Currently, there are a limited number of pigments that can be used, so there are drawbacks such as the inability to produce clear colors when mixing pigments to produce various colors. The present invention provides a novel color display device using a multicolor film.

Next, in the embodiment, the display layer 3 is held between the transparent substrates 1 and 20. This display layer 3 must be capable of controlling transparent mode and scattering mode. Examples of materials used as the display layer 3 include liquid crystal and ferroelectric transparent ceramic. Liquid crystals include Noise change type liquid crystals, which are P-type nematic liquid crystals mixed with chiral material, and P
Examples include a thermo-optical effect type in which a chiral material is mixed into a type smectic liquid crystal, and a DSM type in which an ion dopant is mixed in an n-type nematic liquid crystal, but in short, they are capable of controlling the transparent mode and the scattering mode. Good to have. As a ferroelectric transparent ceramic, a PLZT ceramic whose optical properties change depending on an applied voltage is known.

Transparent electrodes 4 and 5 are formed on opposing surfaces of the transparent substrates 1.2. A polymer film 6 that selectively scatters light of a specific wavelength in the visible range is provided on the back surface of the transparent substrate 2. Cholesteric polymer films are known as such polymer films.

This is a polymer film made of a liquid crystal that exhibits a cholesteric color and can be fixed by polymerization.By changing the polymerization temperature or polymer composition, a film with any selective scattering wavelength can be obtained. Further behind this polymer film 6, a specular reflection plate 7 is provided. As the material of the specular reflection plate 7, aluminum, silver, etc. are used.

Next, the display function of the color display device shown in FIG. 1 will be explained.

Now assume that the polymer film selectively scatters green light and transmits light of other wavelengths, namely red-violet light. In the part A where the display layer 3 is in the transparent mode, incident light is transmitted through the display layer 3, green light is selectively scattered by the polymer film 6, and other light is transmitted. The transmitted light is reflected by the specular reflector 7 and goes out through the polymer film 6 and the display layer 3 again, but in normal use when the display panel 1 is vertically erected and light enters diagonally from above, Most of the reflected red-purple light is reflected diagonally downward;
When viewed from the front, this reddish-purple color is invisible.

Therefore, in part A, only green light enters the eye and appears bright and clear green. Next, in the part B where the display layer 3 is in the scattering mode, the incident light is partially scattered by the display layer 3. The light transmitted through this is selectively scattered by the polymer film 6, while the other light is transmitted, reflected by the specular reflector 7, and scattered again by the display layer, but compared to the green light, The amount of this reddish-purple light is reduced by the amount of light that passes through the polymer film 6 back and forth. Therefore, this part B appears to be white scattering with a slight green tinge. For example, if characters or numbers are displayed in part A with part B as the background part, the characters will be displayed in clear green in a white scattered background with a slight green tinge.

The embodiment shown in FIG. 2 differs from the embodiment shown in FIG. 1 in that the positional relationship between the display layer and the polymer film is reversed.

A polymer film 8 that selectively scatters light of a specific wavelength in the visible range is placed on the front surface, followed by a transparent substrate 9 and a back substrate [10
A display layer 11 is held between the substrates, and a transparent electrode 12 and a specular reflection plate 13 which also serves as an electrode are formed on each substrate.

Let's look at the display effect of the embodiment shown in the second figure. Display layer J
In the part C where 1 is the transparent mode, green light is selectively scattered by the polymer film 8, and red-violet light of the complementary color is transmitted. The transmitted light passes through the display layer 11, is reflected by the specular reflection plate 13, and goes out. When viewing the display panel in an upright position, this reflected red-purple light exits diagonally downward. Therefore, this part appears bright and clear green. Next, in a portion D where the display layer 11 is in the scattering mode, the green light of the incident light is selectively scattered by the polymer film 8, and the reddish-violet light is transmitted i8. Part of the transmitted light is scattered by the display layer 11, and the light transmitted through this is reflected by the reflection plate 13 and scattered again by the display layer, but these scattered lights reduce the visibility of the scene. There is. Therefore, this part is a combination of green light selectively scattered by the polymer film 8 and reddish-purple scattered light to a lesser extent, and appears to be white scattered light with a slight green tinge.

Comparing this situation with the example shown in the first diagram, A, C9B, and D
are displayed in the same way.

In the embodiment shown in FIG. 2, the specular reflection plate 13 is also used as an electrode, but it goes without saying that a separate specular reflection plate may be provided on the back side of the rear substrate 10.

In the present invention, a specular reflector is used as the reflector, but good results were not obtained when other reflectors were used. When a dark color scattering reflector was used instead of a specular reflector, the clear color of the selective scattering wavelength and the same scattering color were displayed, making it difficult to maintain high contrast. 'Also, when a bright color scattering plate was used, there was almost no contrast between the white of the scattering plate and the bright scattering. In other words, good contrast was achieved only when a specular reflector was used.

According to the color display device of the present invention having the above-described structure, it is possible to display bright colors clearly, and also to have high contrast, and it is also simple in structure and can be made thinner.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram of an embodiment of the present invention, and FIG. 2 is a cross-sectional explanatory diagram of another round embodiment. 3... Display layer 6... Polymer film 7... Specular reflection plate 8... Polymer film 11... Display layer 13. ...More than a specular reflector Applicant: Saya Kosha Co., Ltd. Attorney Mogami Figure 1 Figure 2

Claims (5)

[Claims] (1) A color display device comprising a polymer film that selectively scatters light of a specific wavelength in the visible range, a display layer that can control transparent mode and scattering mode, and a specular reflector provided behind the polymer film. (2) The color display device according to claim 1, wherein the display layer is disposed on the front side, an Ueuta polymer film is provided behind it, and the specular reflection plate is further provided behind it. (3) The color display device according to claim 1, wherein the polymer film is disposed on the front surface, the display layer is provided behind the polymer film, and the 100 million surface reflector is provided behind the polymer film. (4) The display layer is made of liquid crystal as claimed in claim 1.
Color display of section. (5) The color display device according to claim 1, wherein the display layer is made of ferroelectric transparent ceramic.