JPS60191227A - Liquid crystal light valve for thermal writing - Google Patents

Abstract

PURPOSE:To obtain high light absorptivity by setting the refractive index of a dielectric film at the intermediate value of the refractive index of electrodes and the refractive index of a light absorptive film. CONSTITUTION:An ITO electrode 15, a TiO2 dielectric film 16 formed by a resistance heating method, an Mo light absorptive film 17, an Al light reflecting film 18 and an SiO2 liquid crystal oriented film 19 are successively laminated on the inside surface of a glass substrate 14 on the side to be irradiated with laser light. On the other hand, an ITO electrode 22 and an SiO liquid crystal oriented film 21 are successively laminated on the inside surface of a glass substrate 23 on the projecting light side. Two sheets of the substrates 14, 23 are sealed at the peripheral via spacers 24, 25 by adhesive agents 26, 27 and a liquid crystal, i.e., normal octyl cyanobiphenyl 20 is injected into the space therebetween. The reflection at the boundary surface of the light absorptive film is decreased by providing the film 16 and the always higher light absorptivity than the light absorptivity obtd. with the film 17 along is obtd. Contrast is improved as well.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a display device that utilizes the thermo-optic effect of liquid crystal, that is, a thermal writing liquid crystal light pulp.

(Prior art and its problems) By heating and rapidly cooling a liquid crystal, the random orientation state of liquid crystal molecules is frozen, causing a phenomenon in which light is scattered. This is called the thermo-optic effect of liquid crystal. Taking advantage of this phenomenon, an image is written by irradiating a liquid crystal cell with a laser beam to cause a temperature rise in the irradiated area, and to erase the written image, an electric field is applied to the liquid crystal to force the liquid crystal molecules. There is a liquid crystal light pulp that can be oriented. In a projection display using such liquid crystal light pulp, the writing laser power, writing speed, and contrast largely depend on the light absorption rate of the liquid crystal light pulp. That is, the larger the light absorption rate, the smaller the writing laser power is required, the faster the writing speed, and the better the contrast. FIG. 1 shows a cross-sectional view of a liquid crystal light pulp with a conventional structure.

A transparent electrode 2 is provided on the inner surface of the laser source irradiation side substrate 1. Light absorption film 3. Light reflection film 4. Liquid crystal alignment films 5 are sequentially formed.

The written image is read out by the projection light and projected onto the screen, and a transparent electrode 8 is provided on the inner surface of the substrate 9 on the projection light side. Liquid crystal alignment films 7 are sequentially formed. These two substrates are connected through spacers 10 and 11, and the surrounding area is covered with adhesive 12.
13, and liquid crystal 6 is injected into the gap. The light absorption film used conventionally has a low light absorption rate of 0.70 at the maximum at the wavelength of the half-J body laser, and the writing laser power is 100 mW.

At a writing speed of 3 μs/dot, the maximum contrast was only 35. Also, the accumulated laser power is 1
At 00 mW and a writing speed of 1.5 μS/dot, the maximum contrast was only 16.

(Object of the Invention) An object of the present invention is to provide a liquid crystal light pulp that provides a high light absorption rate.

(Four Components of the Invention) The thermal writing liquid crystal light valve of the present invention has a liquid crystal sandwiched between two substrates, and a writing laser beam is applied to at least the entire writing area on the inner surface of the substrate on the side to which the writing laser beam is irradiated. The structure is characterized by sequentially laminating electrodes, dielectric films, and binary absorption films that have a refractive index that is between the refractive index of the electrodes and the refractive index of the light absorption film.

(Example) Is the following implemented? The present invention will be described with reference to the drawings showing lJ. FIG. 2 is a sectional view of an embodiment of the liquid crystal light pulp of the present invention.

ITO liquid crystal alignment films 19 are sequentially laminated on the inner surface of the glass substrate 14 on the laser beam irradiation side. On the other hand, ITO electrodes 22° and SiO liquid crystal alignment film 21 are sequentially laminated on the inner surface of the glass substrate 23 on the projection source side. These two glass substrates were surrounded by adhesives 26 and 27 via spacers 24 and 25, and liquid crystal normal octyl cyan biphenyl 20 was injected into the gap.

When the thickness of the TiO2 film 16 is 50 OA, a light absorption rate that is always higher than that obtained with a light absorption film with a conventional configuration is obtained, and the writing laser power is 100 mW.

The writing speed is 1.5 μS/dot and the maximum contrast value is 6. Also, the writing laser power is 100mW.

At a writing speed of 3 .mu.8/dot, the maximum contrast value was 9, and a KQ value that was always higher than that obtained with the conventional structure when writing was performed under the same conditions was obtained.

Furthermore, it was confirmed that even when the Tie film thickness was other than 50 OA, a light absorption rate that was always higher than that obtained with a conventional light absorption film was obtained, and the contrast was also improved. As described above, it was confirmed that by attaching the dielectric film TiO2, reflection at the light absorption film interface is reduced, and a light absorption rate that is always higher than that obtained with the light absorption film alone is obtained, and the contrast is also improved. It was done.

Furthermore, the dielectric film 16 created by the resistance heating method is made of CeO,
Even when the film thickness was set to 5ooX, a light absorption rate that was always higher than that obtained with a light absorption film with a conventional configuration was obtained, and the writing laser power was 100 mW and the writing speed was 1.5 μs/dot. The maximum contrast value is 5.5.
Also, the writing laser power is 100mW and the writing speed is 3
The maximum value of contrast is 8.5 in μS/dot,
Contrast values were consistently higher than those obtained with the conventional structure when writing under the same conditions. Also CeO
It was confirmed that even when the film thickness of No. 2 was other than 50 OA, a light absorption rate that was always higher than that obtained with a conventional light absorption film was obtained, and the contrast was also improved. As described above, by attaching the dielectric film CeO, reflection at the interface of the light absorption film is reduced, and a light absorption rate that is always higher than that obtained with the light absorption film alone is obtained, and the contrast is also improved. It was confirmed that it does.

The Tie, ZnS other than CeO2, ZrO2,
Even in the case of many other dielectric films having a refractive index between the refractive index of the electrode and the refractive index of the light absorption film, such as SiO, and also in the case of many other light absorption films other than molybdenum, such as manganese, In addition, it was confirmed that in all of the manufactured liquid crystal light lenses, a light absorption rate that was always higher than that obtained with a light absorption film having a conventional structure was obtained, and the contrast was also improved.

(Effects of the Invention) As explained above, according to the present invention, a liquid crystal light valve having a structure that provides a high light absorption rate can be obtained.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a liquid crystal light valve with a conventional structure;
The figure is a cross-sectional view of one embodiment of the liquid crystal light pulp of the present invention. In FIG. 1, 1.9...Substrate, 2,8...Transparent electrode, 3...Light absorption film, 4...Light reflection film, 5,7...Liquid crystal alignment film,
6...Liquid crystal, 10.11...Spacer, 12.13
...Adhesive agent. In Fig. 2, 14.23...Glass substrate, 15.22...ITO
Electrode, 16... Current visiting body film, 17... Light absorption film, 18
...At light reflection film, 19.21...SiO liquid crystal alignment film, 20...liquid crystal normal octyl cyano biphenyl, 24.25...spacer, 26.27...adhesive.

Claims (1)

[Claims] In a thermal liquid crystal light valve in which a liquid crystal is sandwiched between two substrates, an electrode, a fatty electrolyte film, and a light absorption film are sequentially formed on at least the entire writing area of the inner surface of the substrate on the side to which the writing laser beam is irradiated. and the refractive index of the dielectric layer has a value intermediate between the refractive index of the polarization and the refractive index of the light absorption film.