JPH03186816A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain the color high-polymer/liquid crystal composite film (PDLC) of a high contrast by placing color filters in front of the PDLC and a light absorber behind the color filters. CONSTITUTION:An electrode substrate 11 on an observer side of two sheets of the electrode substrates 11, 12 is provided with the color filters 3 and the light absorber 2 is disposed on the side opposite from the observer with the PDLC 1 in-between. The PDLC 1, therefore, scatters and becomes white when the voltage is not impressed. The colors of the color filters 3 in front of the PDLC 1 are consequently brightly visible. On the other hand, the PDLC 1 is transparent when the voltage is impressed and, therefore, the display is blackened by the effect of the light absorber 2 behind the PDLC 1. The dark state is extremely darkened by using the light absorber 2 in such a manner. The color PDLC display of the high contrast is obtd. in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a liquid crystal display element.

[Prior Art] A polymer/liquid crystal composite film (hereinafter referred to as PDLC) has a sponge-like three-dimensional network structure 15 of polymers, as shown in FIG.
It is a special film that holds a low-molecular liquid crystal 14 inside. P.D.
LC changes from a light-scattering state to a light-transmitting state as voltage is applied, and this property has already been put to practical use as light control glass, while applications as displays are also being considered.

In particular, when applied as a color display, a configuration has been proposed in which a black dichroic dye is mixed into the liquid crystal to increase contrast, and a color filter 4 is placed behind the PDLC as shown in Figure 2. .

In this way, when no voltage is applied, it becomes blackish due to the scattering effect of the PDLC and the light absorption effect of the dichroic dye, while when a voltage is applied, both the PDLC and the dichroic dye become light transmitting, and the color placed behind Since you can see the color of the filter, you can display colors.

[Problems to be Solved by the Invention] However, color displays with such a configuration have a problem of low contrast. This is mainly due to the fact that the dark state does not become sufficiently dark due to the dichroic limitations of dichroic dyes.

The present invention solves these problems, and its purpose is to provide a high-contrast color PDLC display by placing a color filter in front of the PDLC and a light absorber behind it. be.

[Means for Solving the Problems] The liquid crystal display element of the present invention includes a PDLC and electrode substrates disposed on both sides of the PDLC. It is characterized in that a color filter is provided on the side electrode substrate, and a light absorber is placed on the side opposite to the viewer with the PDLC in between.

Further, the color filter is characterized in that at least three types of micro color filters having different absorption wavelength bands are arranged.

[Function] In the liquid crystal display element of the present invention, when no voltage is applied, the PDLC is scattered and becomes white, so the color of the color filter in front of the PDLC appears vivid. On the other hand, when a voltage is applied, the PDLC becomes transparent, so the display becomes black due to the action of the light absorber behind the PDLC. Using a light absorber makes the dark state very dark, resulting in high contrast.

Hereinafter, the details of the present invention will be shown by examples.

[Example] FIG. 1 is a cross-sectional view of a liquid crystal display element of the present invention. In the figure, 1 is a PDLC, 2 is a light absorber, and 3 is a micro color filter. Matte black paper was used as the light absorber, and red, green, and blue filters made by a dyeing method were used as the microcolor filters.

Further, 11 is an upper substrate, 12 is a lower substrate, 13 is a transparent electrode,
14 is a liquid crystal, and 15 is a sponge-like polymer. A nematic liquid crystal having positive dielectric anisotropy was used as the liquid crystal, and PMMA was used as the polymer. A distance of about 2 cm is left between the PDLC and the light absorber so that ambient light can be taken in from behind the PDLC.

As described above, the liquid crystal display element of the present invention is in a colored state when no voltage is applied and is in a dark state when a voltage is applied, and can display colors with high contrast. Furthermore, by combining three color filters, multicolor display of eight colors is possible.

Note that this liquid crystal display element does not require a polarizing plate, so it is sufficiently bright even without a backlight.

In addition, an even brighter display can be obtained by placing the light source 5 that illuminates the PDLC from behind in a position that is not directly visible to the observer's eyes.

[Effects of the Invention] As described above, according to the present invention, a high-contrast color PDLC display can be provided by placing a color filter in front of the PDLC and a light absorber behind it.

[Brief explanation of drawings]

5- FIG. 1 is a sectional view of a liquid crystal display element of the present invention. FIG. 2 is a cross-sectional view of a conventional liquid crystal display element. 1.PDLC 2. Light absorber 3. Micro color filter 4. Color filter 5. Light source 11. Upper board 12. Lower board 13. Transparent electrode 14.LCD 15. Sponge-like polymer 16. Liquid crystal mixed with dichroic dye that's all

Claims (2)

[Claims] (1) In a liquid crystal display element consisting of a polymer/liquid crystal composite film in which liquid crystal is dispersed in a thin polymer film, and electrode substrates placed on both sides of the film, an observer of the two electrode substrates 1. A liquid crystal display element comprising a color filter on a side electrode substrate, and a light absorber disposed on a side opposite to an observer with the polymer/liquid crystal composite film in between. (2) The liquid crystal display element according to claim 1, wherein the color filter is an array of at least three types of micro color filters having different absorption wavelength bands.