JPS59116680A - Color display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] This invention relates to a color display device.

Conventionally, color display devices that combine twisted nematic liquid crystals and color polarizing plates have been known. Since this display device uses high light sheet metal, the amount of light decreases and becomes dark.Also, since there is no fully functional color ray plate, parts other than the color display part are colored similarly, resulting in low contrast in appearance. There were drawbacks such as. Guest-host type liquid crystal display devices are also known, but the contrast is low because the two-color ratio of the pigment is insufficient, and the display and non-display areas become similar in color, resulting in poor visual contrast. Since the number of dyes that can be used is limited, there are drawbacks such as the inability to produce clear colors when mixed dyes are used to produce various colors.

This invention provides a clear color display device using an optically active material.

Next, examples will be described.

An optically active material layer 2 that selectively scatters light of a specific wavelength in the visible range is provided on the front surface of a display panel 1 of a color display device.

As described above, cholesteric polymer films are known as optically active substances.

This is a polymer film made of liquid crystal that exhibits a cholesteric color and can be polymerized and fixed.By changing the polymerization eddy current or the polymer composition, a film with arbitrary selective scattering wavelengths can be obtained. Other optically active substances that can be used include cholesteric liquid crystals, chiral nematic liquid crystals, and mixed liquid crystals thereof, as well as optically active substances that do not form a liquid crystal phase by themselves, and mixed liquid crystals with optically inactive substances. The illustrated example uses a cholesteric polymer film, or if a liquid crystal is used, it is naturally sandwiched between glass substrates. However, a method of micro-encapsulating liquid crystals has now been developed, so micro-encapsulated liquid crystals are dispersed in a transparent binder and a transparent substrate VC is used.
When coated, it is easy to manufacture and can be made thin. A display layer 3 is arranged behind this optically active material layer 2. This display layer 3 must be able to fully control the transparent mode and the scattering mode. Examples of materials used for the display layer 3 include liquid crystal and ferroelectric transparent ceramic. As a liquid crystal,
A phase change type that is a P-type nematic liquid crystal mixed with a chiral material, an electro-thermo-optic effect type that is a P-type smectate liquid crystal that is mixed with a chiral material, a DSM type that is an n-type nematic liquid crystal that is mixed with an ion dopant, etc. However, in short, any device that can control the transparent mode and the scattering mode will suffice. As a ferroelectric transparent ceramic, a PLZT ceramic whose optical properties change depending on an applied voltage is known. This display layer 3 is made of liquid crystal, and is held between transparent glass substrates 4 and 5, and a transparent electrode 6 is provided on these side substrates to form a display segment shape. A specular reflection plate 7 is formed as a specular electrode. A transparent electrode 8 provided on the lower surface of the mirror electrode is for extraction. In addition, like this, the specular reflector plate 7? In the case of a mirror electrode, it is possible to use the mirror electrode as a segment electrode and the transparent electrode 6 as a common electrode. The mirror reflecting plate 7 and the transparent electrode 8, which form the twisted mirror electrode, may be reversed. Furthermore, the specular reflection plate 7 may be provided on the back surface of the glass substrate 5. In short, the specular reflection plate 7 may have a segment shape and be positioned behind the display layer 3. Further behind this display layer 3, a light-colored scattering/reflection plate 9 is arranged. Scattering reflection plate 9
The materials used include white paper and polyester film with gelast treatment on the surface and aluminum vapor-deposited on the back. Of course, the material is not limited to a plate-like material, and the back surface of the glass substrate 5 may be coated with paint. Note that the above-mentioned specular reflection plate 7 may be provided on the front surface of this scattering reflection plate 9 by vapor deposition or the like.

Next, the display effect will be explained.

Assume now that the cholesteric polymer film of the optically active substance layer 2 selectively scatters green light and transmits other light, that is, reddish-violet light.

In the part A where the display layer 3 is in the transparent mode, the middle edge color light of the incident light is selectively scattered, and the reddish-violet light is transmitted, passes through the display layer 3, is reflected by the specular reflector 7, and exits. Display panel 1
In normal use, when the camera is stood vertically and light enters mainly from diagonally above, most of the reddish-purple light reflected by the specular reflector 7 is reflected diagonally downward, which means that when viewed from the front, In this case, green light is better than reddish-violet light, and this person's parts appear bright green. B in which the display layer 3 is in scattering mode
Among the incident lights, green light is selectively scattered by the cholesteric polymer film. The transmitted reddish-violet light is scattered by the display layer 5, and a part of it is transmitted therethrough, reflected by the specular reflection plate 7, and scattered again to come out. In other words, since green light and reddish-violet light are both scattered here, they look like a bright scattering mortar.

Now, in the part C where no display electrode is provided, the display layer 3 is always in the transparent mode, and the reddish-violet light that has passed through the optically active material layer 2 is transmitted through the display layer 5 and is reflected by the scattering reflection plate 9. It comes out as a reflection. Therefore, this part C looks bright white like the part B.

Rather, it is necessary to make the part C look the same as the part B, so when selecting all the materials for the light-colored scattering reflector 9, compare it with the part B and choose one that is not conspicuous. It is essential to do so. Due to this display action, numbers, etc. can be displayed by applying a voltage to the display segments that are not used for display to set them to total scattering mode, making the display the same color and brightness as the ground, and erasing it. . In the above example, green can be displayed on a bright white background.

The above explanation assumes that the display panel 1 is placed upright and light enters from above, but if you turn the display panel 1 to various angles, you will see a reddish-purple reflection from light sources such as the sun or electric lights. As long as the display was not placed at an angle where a large amount of light could be seen, the display could be displayed externally as described above, and could be put to practical use.

One of the features of this invention is that the mirror reflectors are arranged in a segment shape rather than over the entire surface. In order to display green on a bright white background, which is easy to read, if a specular reflector is provided on the entire surface, the entire display layer on the background must be in the scattering mode, and normally the scattering mode is It is in a state where voltage is applied, and the current consumption increases. Also, since voltage cannot be applied to the so-called gear line between segments or around the lead wire, when a display is made, this gap line runs as a green line on the ground, making it difficult to see.

According to the color display device of the present invention having the above-described configuration,
The color segment display on a bright white background provides high contrast and easy-to-read display, and because voltage only needs to be applied to segment parts that are not needed for display, current consumption is low.

[Brief explanation of drawings]

The drawing is an explanatory cross-sectional view of an embodiment of the present invention. 2...Optically active material layer 3...Display layer 7...Specular reflector 9...Scattered reflector that's all 7

Claims (1)

[Claims] (1) An optically active material layer that selectively scatters light at a specific wavelength in the visible range is disposed on the entire front surface, and behind it is a display layer that can control the transparent mode and the scattering mode to display the segment i. A color display device comprising: a specular reflective plate provided behind the specular reflective plate in a portion facing the display segment; and a light-colored scattering reflective plate provided behind the specular reflective plate. (2) The color display device according to claim 1, wherein the optically active substance is a cholesteric polymer film. (6) The color display device according to claim 1, wherein the optically active substance is a cholesteric liquid crystal.