JPS58198081A - Reflection plate for light scattering liquid crystal - 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 The present invention relates to a reflecting plate for a light scattering type liquid crystal display element such as a dynamic scattering type, cholesteric, or nematic phase transition type (hereinafter abbreviated as 0NFT).

In recent years, field effect type TIJ liquid crystal display elements have become widely used as display devices for wristwatches, calculators, and the like.

Dynamic scattering ffJ (DSM), cholesteric, and nematic phase transition light scattering type liquid crystal display elements have the characteristic that they have no viewing angle and are brighter than TN type liquid crystal display elements, and displays that take advantage of these characteristics. It is being put into practical use as a device.

In addition to DSM and ONFT, there are various types of light-scattering liquid crystal display elements, such as memory type display elements using cholesteric liquid crystals, and display elements using smectic and nematic phase transitions. Compared to elements, it does not use a polarizing plate, so the contrast is low. Therefore, it is used as a projection type display device, or as a display device with a light source using a colored diffuser as a reflector.
Or, the mirror surface is used as a reflector.

A light scattering liquid crystal display device using a mirror surface as a reflecting plate is shown in Fig. 1.
As shown in FIG. 2, a thin film 4 with a mirror surface of aluminum or silver, etc. is formed directly on the back substrate 3, or a reflector plate with a mirror surface 5 is placed on the back as shown in FIG. There is. In order to bring variety to the display of this type of light-scattering liquid crystal display device, a method has been devised in which a reflector plate is made to have a partial silver mirror surface and a full mirror surface mixed together.

9 - The present invention provides a light scattering type liquid crystal display element with beautiful colors. The purpose of the present invention is to provide a reflective plate for displaying a wide variety of displays.

The present invention will be described below.

The present invention involves forming a transparent thin film whose thickness changes continuously by vapor deposition or sputtering on a metal plate having a silver mirror surface or a substrate having a silver mirror thin film such as aluminum or silver on its surface. This is a characteristic reflecting plate that can be used for light scattering type liquid crystal display elements.

When a transparent thin film 6 with a refractive index outside is formed on a silver mirror surface 5, white light incident perpendicularly as shown in FIG.
=tnα (22 is usually an integer, d indicates the thickness of the thin film), and the light of wavelength α is strengthened by interference and reflected. However, when looking only at this mirror surface, the color change caused by interference is hardly noticeable because the image reflected on the mirror surface is almost invisible. becomes. Furthermore, if a thin film 7 with a continuously changing thickness d is formed on a mirror surface as shown in FIG. 4, and a light scattering layer is placed in front of it, the wavelength strengthened by interference changes continuously, so that rainbow A beautiful light-scattering layer whose color changes continuously can be obtained. Since a light-scattering liquid crystal display element displays in a light-scattering state and a transparent state, when such a reflector is used, the light-scattering part has a pale rainbow pattern, and the transparent part can realize a beautiful display with no noticeable coloring.

Such a transparent thin film whose thickness changes continuously is produced by placing a mask 8 at a certain distance in front of a substrate whose surface is a silver mirror surface 5, as shown in FIG.
oxides such as n, OuF.

, MpF, etc., by vapor deposition or sputtering. The larger the distance between the substrate and the mask, the more
Also, the lower the degree of vacuum during vapor deposition or sputtering, the more
A film with a small rate of change in thickness d can be obtained. 2? LX△d(
22, n is the refractive index of the thin film, Δd is the difference in film thickness] is approximately 75O
As explained by A, when the film thickness changes, it changes continuously like a rainbow from purple to red, and if 2n x △d is doubled to about 150 OA, then the rainbow colors from purple to red change. This will result in two obi bands.

By changing the rate of change in film thickness and by changing the size of 2n x △d, the degree of rainbow color change can be adjusted, and by changing the shape of the mask during vapor deposition or sputtering. You can choose from various patterns.

In the light-scattering liquid crystal display device using the reflector of the present invention, the rainbow color stands out only in the light-scattering part, so it is better to use a negative type display in which the background is in a glossy disordered state and the displayed characters and numbers are transparent. Embodiments will be described below, which are more beautiful and more effective than the positive tiled display.

Embodiment 1 As shown in FIG. 6, using a sputtering apparatus having a sputtering surface 9 with a width of 10 crn, upper and lower middle 2 cr IM substrates 10 on which aluminum thin films are formed are placed 15 crn below the sputtering source, and a substrate is placed on the substrate 13. The mask 8 was placed so that only half of the sample was covered, the target value was set to 150OA, the degree of vacuum was set to ax1o-a, and the sho was heated to 5-5. This reflector was glued to the back of a negative type dot matrix DSMi display element, with the thick side of Sto*M facing up, as shown in FIG. When the display device is driven, the background light scattering part changes from pale red at the top to orange, yellow, green, and blue in that order.
The lower part was a pale purple color, and the transparent part of the displayed letters and numbers meant that I could not see the image reflected on the mirror surface, so I could hardly notice the change in color of the reflector. When viewed from the front, the sign appears in a dark color with a rainbow-colored background, and when the viewing angle is shifted up or down, the rainbow color changes, creating an extremely beautiful and fantastic display.

Embodiment 2 As shown in FIG. 8, an aluminum plate 13 with a mirror surface is placed above 40z from the evaporation source 12, and a striped mask 14 is placed at a position 2α below the aluminum plate. os O2000Ae 5X10-”
The deposition was carried out at a vacuum degree of to γ. When this reflector is used as a reflector for a negative type cholesteric nematic +6 one-phase transition type liquid crystal display element and a 0 display device glued to the back is driven as in Example 1, the light scattering part in the background becomes rainbow-colored. The result was a pale striped pattern of purple and white that changed continuously. - As shown in the above embodiments, according to the present invention, a light-scattering liquid crystal display device can display a beautiful light iridescent color display, resulting in an extremely fashionable display. This can have a significant effect in improving the practicality of light scattering liquid crystal display elements.

[Brief explanation of the drawing]

Figures 1 and 2 are structural examples of a light-scattering liquid crystal display device that uses a mirror surface as a reflector, and Figure 3 is for explaining the reflection of light on a reflector that has a transparent thin film formed on the mirror layer. FIG. 4 is an example of a reflector according to the present invention. FIGS. 5, 6, and 8 are layout diagrams for vapor depositing and sputtering a transparent thin film to produce a reflector according to the present invention. FIG. 7 is a structural diagram showing an example in which a reflector according to the present invention is attached to a display device. 100 front board 2°. Liquid crystal layer 116. Applicant for adhesives and above: Daini Seikogo Co., Ltd.

Claims (1)

[Claims] A transparent thin film whose thickness is continuously varied by distillation or sputtering is formed on a metal plate with a silvery specular luster or on a substrate on which a thin film of aluminum, silver, etc. is formed on the surface. Reflector plate for light-scattering liquid crystal display element characterized by