JPH03186815A - liquid crystal display element - 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] [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 used as a color display, it has been proposed to mix a black dichroic dye into the liquid crystal to increase contrast, and then place a color filter 3 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 PDLC and the light absorption effect of dichroic dye, while when voltage is applied, both PDLC and 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 is intended to solve these problems, and its purpose is to create a high-contrast color PDLC display by mixing a dichroic dye into the liquid crystal and placing a light absorber behind the PDLC. Our goal is to provide the following.

[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, in which a dichroic dye is contained in the liquid crystal of the PDLC. and a light absorber is disposed on the opposite side of the viewer with the PDLC in between.

[Function] In the liquid crystal display element of the present invention, when no voltage is applied, the PDLC scatters light, and at the same time, the dichroic dye develops color, so that colors corresponding to the dye appear vivid. On the other hand, when voltage is applied, PDL
Since both C1 dichroic dyes become transparent, 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.

3- 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 12 which is a light absorber.

Matte black paper was used as the light absorber. Further, 11 is an upper substrate, 12 is a lower substrate, 13 is a transparent electrode, 14 is a liquid crystal, 1
5 is a sponge-like polymer. A nematic liquid crystal having positive dielectric anisotropy was used as the liquid crystal, and a dichroic dye of red, green, or blue is mixed in the liquid crystal according to each pixel. PMMA was used as one of the polymers. PDL
Leave a distance of about 2 cm between C and the light absorber, and
Ambient light can also be taken in from behind the LC.

As described above, the liquid crystal display element of the present invention is colored in red, green, or blue when no voltage is applied, and is in a dark state when voltage is applied, and can display colors with high contrast. Also 3
Multi-color display of eight colors is possible by combining color pixels.

Note that this liquid crystal display element requires a polarizing plate. There is no backlight, so it is bright enough even without a backlight.

Furthermore, an even brighter display can be obtained by placing the light source 4 that illuminates the PDLC from behind in a position that does not directly enter the observer's eyes.

[Effects of the Invention] As described above, according to the present invention, a high-contrast color PDLC display is provided by mixing a dichroic dye in the liquid crystal and placing a light absorber behind the PDLC. be able to.

[Brief explanation of drawings]

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. Color filter 4. Light source 11. Upper board − 2゜ 3゜ 4゜ 5゜ 6゜ lower board transparent electrode Liquid crystal containing a mixture of red, green, or blue dichroic pigments sponge-like polymer Liquid crystal mixed with black dichroic dye that's all

Claims (1)

[Claims] (1) A liquid crystal display element comprising a polymer/liquid crystal composite film in which liquid crystal is dispersed in a polymer thin film, and electrode substrates disposed on both sides of the film, the liquid crystal containing a dichroic dye, A liquid crystal display element, further comprising a light absorber disposed on the opposite side of the viewer across the polymer/liquid crystal composite film.