JPS5962829A - Optical control method - Google Patents

Abstract

PURPOSE:To enable shuttering of incident light simply by varying the incident angle of the incident light by making the incident angle larger or smaller than the critical angle in the stage of making parallel or approximately parallel linearly polarized light incident to a liquid crystal cell. CONSTITUTION:A nematic liquid crystal which is homogeneously oriented and has 1.63 ne is sandwiched between glass 1 and 2 having 1.80 refractive index ng. A polarization plate 4 is disposed on the side of incident light 5 with the axial direction 6 of the transmission thereof made parallel or approximately parallel with the homogeneous orientation. The refractive index of a liquid crystal 3 is made to ne=1.63 with respect to the incident light 5. Therefore, if the incident light 5 is made incident at the incident angle theta1 larger than the angle theta=sin<-1> (1.63/1.80)=64.9 deg., the incident light is shut off as total reflection light 5 and if said light is made incident at the incident angle theta2 smaller than said angle, the light 5 is made to transmitted light 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical control method using a liquid crystal cell, and more particularly to a novel liquid crystal-optical shutter that does not require voltage application means.

Liquid crystal-optical shutter is 1, for example, Japanese Patent Application Laid-Open No. 47-11737.
No. 3,731,986, U.S. Pat. No. 3,700
It is disclosed in Publication No. 306 and the like.

This liquid crystal-optical shutter has a nematic liquid crystal with positive dielectric anisotropy with a horizontally twisted orientation arranged between a pair of transparent plates, and a pair of transparent plates and a pair of transparent plates outside [111j]. It has a configuration with parallel or crossed polarizers. Therefore, this liquid crystal-optical shutter can be
A voltage can be applied to the counter electrodes to transform the optical properties of the twisted nematic liquid crystal, and this change can be detected by a polarizer.

With such conventional liquid crystal-optical shutters, light rays from a few to several 10000 ahead pass through the polarizing plate when the voltage is on or off, so it is impossible to create an optical shutter that completely blocks the light, so it is difficult to use, for example, in cameras. It is difficult to apply the above-mentioned liquid crystal-optical shutter to a shutter such as the following. Moreover, since two polarizing plates are used, there are drawbacks such as a large loss of light quantity.

An object of the present invention is to provide a novel optical control method that can be used in liquid crystal-optical systems.

Another object of the present invention is to provide an optical control method that can completely block the light beam.

Another object of the present invention is to provide an optical control method that reduces the amount of light that is lost.

Such an object of the present invention is to provide a liquid crystal cell having a relationship of ng>ne between transparent substrates and sandwiching homogeneously aligned liquid crystals, which is parallel to or approximately parallel to the alignment direction of the liquid crystals on the light incident side. An optical control method characterized in that when linearly polarized light having parallel transmission axes is incident, the linearly polarized light is controlled by varying the linearly polarized light (where h ng is the refractive index of the transparent substrate). , is the refractive index of the extraordinary rays of the liquid crystal molecules).

The optical control method of the present invention will be explained below with reference to the drawings.

FIGS. 1(a) and 1(b) are cross-sectional views showing an embodiment of the optical control method of the present invention. The liquid crystal cell used in the present invention has a liquid crystal 3 (horizontally aligned) between transparent substrates 1 and 2 with a refractive index of ng (for example, glass with ng of 180).
For example, Merck's l'-'ZLI-1 with ne of 1.63
A 565J nematic liquid crystal) is sandwiched between the transparent substrates 1 and 2, and a constant distance (t) is maintained between the transparent substrates 1 and 2 by a Shields-Baser 9. The orientation direction of the liquid crystal 3 is
Alignment film installed on! 8 can be determined by orientation treatment such as rubbing. At this time, the alignment film 8 is not necessarily required;
, polyvinyl alcohol II, and ceratin membrane.

Orientation 11i' of 5in2 film, TiO2 film, etc. , 8
It is desirable to form it as In fact, when forming the S-mountain 21 area, by using oblique vapor deposition, it is possible to perform orientation treatment at the same time as the formation. In this liquid crystal cell, a polarizing plate 4 is arranged on the side of incident light 5 with its transmission axis direction 6 parallel or substantially parallel to the homogeneous arrangement.

In the liquid crystal cell used in the present invention, the difference between the refractive index n of the extraordinary ray of the liquid crystal 3 and the refractive index ng of the transparent substrate l is, for example, in the case of the above-mentioned Merck & Co., Ltd. [Z L l-1565J nematic liquid crystal, ng (=1.80) > ne (=1.
63). Transmission axis direction 6 of polarizing plate 4
This is parallel or substantially parallel to the homogeneous alignment direction of the liquid crystal 3, so the refractive index of the liquid crystal 3 with respect to the incident light 5 is nP (=1.63).

= 64.9°, this incident light 5 (I!Linally polarized '#J light) becomes 2g.
As shown in Figure 1 (al), the reflected light 7 is turned around.

On the other hand, if the incident light 5 is made incident at an incident angle θ which is 80 degrees smaller than θ-5in-appliance)=64.9°, then this incident light 5
((α-polarized light) is transmitted through the shuttle shown in Figure 1 (bl) at 110
(becomes transparent).

In the present invention, the angle of incidence of the incident light 5 can be varied by mechanically or dynamically rotating the liquid crystal cell, or by similarly rotating the light source.

Furthermore, the liquid crystal used in the method of the present invention may be a nematic liquid crystal or a smethoctic liquid crystal. Even if the dielectric anisotropy of a nematic liquid crystal is E, it can still be negative. In any case, the relationship between the refractive index (T1+y) of the transparent substrate and the refractive index (ne) of the extraordinary ray of the transparent substrate is rig > I+ (! Any material may be used as long as it satisfies the following relationship.

The transparent substrates l and 2 are not limited to those having the shape shown in FIG. convex lens.

A concave lens, a flat glass plate, a plastic lens, a plastic plate, etc. may also be used.

The optical control method of the present invention has 1ζ11 points as shown below.

(1) The pressure applying means can be set up as a shutter.

(2) Just by varying the angle of incidence of the incident light, it is possible to shut out the light from a person.

(3) Since only one polarizing plate is used, there is less loss in the Tenney path and it is possible to print bright transmitted light.

(4) Since the incident light can be completely reflected by total reflection, high contrast control is possible.

(5) Application to the shutter mechanism of a camera is advantageous. (6) Application to the shutter of an electrophotographic printer is possible.

[Brief explanation of drawings]

Figures 1 fa) and 4 (1) are cross-sectional views showing an embodiment of the method of the invention. 1.2... Transparent substrate, 3... Crystal 4... Polarizing plate 5, Incident light, 6 Transmission axis direction. 7... & reflected light, 8... orientation &! , 9...
Seal spacer 10...Incidence angle g larger than "0°θt・sin'(") for transmission Canon Co., Ltd.

Claims (1)

[Claims] In a liquid crystal cell having a relationship of ng > ne between transparent substrates and sandwiching homogeneously aligned liquid crystals, there is a transmission line parallel or substantially parallel to the alignment direction of the liquid crystals on the incident side of light. When linearly polarized light having an axial direction is incident, the angle of incidence of the linearly polarized light is varied by making it larger or smaller than the angle determined by θ=:5in-'(r'-!-)0g. An optical control method characterized in that the linearly polarized light is controlled by (where, face is the refractive index of the transparent substrate, and ne is the anomalous JC, pure refractive index of the liquid crystal molecules).