JPH0436728A - Photoconduction type liquid crystal light valve - Google Patents

Abstract

PURPOSE:To improve the safety of images and productivity by eliminating the cross-interference by the electric fields of the impressing electrode of a liquid crystal layer and the impressing electrode of an electroluminescence element. CONSTITUTION:A transparent conductive film 21 connected to the ground and transparent insulating dielectrics 22 and 23 disposed on both surfaces of this transparent conductive film 21 are laminated and inserted between the writing side transparent conductive film 9 and the electroluminescence element 10. The transparent conductive film 21 shuts off the electric fields to the electroluminescence element 10 by the transparent conductive films 8 and 9 and shuts off the electric fields by the transparent electrodes 14 and 18 to the photoconduction type liquid crystal light valve.

Description

TECHNICAL FIELD The present invention relates to a photoconductive liquid crystal light valve used in a projection type liquid crystal display device.

BACKGROUND ART FIG. 2 shows a cross-sectional structure of a conventional photoconductive liquid crystal light valve disclosed in Japanese Patent Application No. 83-284970.

In this photoconductive liquid crystal light valve, a spacer 2 is provided around the liquid crystal layer 1, and alignment films 3.4 are arranged on both sides of the liquid crystal layer 1. The liquid crystal layer 1 and the photoconductive film 5 are laminated with a light reflecting film 6 and a light absorbing film 7 interposed therebetween.

The light reflecting film 6 is for reflecting the projected light incident from the reading side, and the light absorbing film 7 is for absorbing the light leaking from the light reflecting film 6. A transparent conductive film 8.9 as a transparent electrode is disposed on the outside of the liquid crystal layer 1 and the photoconductive film 5, and an electroluminescent element 10 is disposed on the outside of the transparent conductive film 9 on the writing side. are all sealed by glass substrates 11 and 12. Transparent conductive film 8
, 9, an alternating voltage is applied between them.

The electroluminescent element 10 includes a transparent insulating layer 13, a transparent electrode 14, a transparent insulating layer 15, and a zinc sulfide (ZnS) layer 16, which are laminated in this order from the transparent conductive film 9 side on the writing side.
, a transparent insulating layer 17 and an electrode 18. In this electroluminescent device 10, the transparent electrode 14 is composed of a plurality of strip-shaped electrode groups arranged to extend parallel to each other in the X direction, and
Reference numeral 8 consists of a plurality of strip-shaped electrode groups arranged to extend parallel to each other in the Y direction.

FIG. 3 shows an example of the configuration of the X, X-direction electrode group and its drive circuit. In the figure, an X-direction electrode group that is the transparent electrode 14 and an X-direction electrode group that is the metal electrode 18 are arranged in a matrix, and the intersection of each electrode corresponds to one pixel. From this group of X and X direction electrodes, each one electrode forming an intersection corresponding to a desired pixel is connected to a drive circuit 19.2.
By selecting 0 and applying an alternating current voltage between the electrodes, the corresponding portion of the Zn5 layer 16 sandwiched between the electrode groups emits light. This emitted light lowers the electrical resistance of the portion of the photoconductive liquid crystal light valve corresponding to the photoconductive film 5, increases the voltage applied to the corresponding portion of the liquid crystal layer 1, and writes an image on the liquid crystal layer 1. It is. In this way, on the readout side, it is possible to read out the image written on the liquid crystal layer 1 using the projected light.

By the way, in order to produce photoconductive liquid crystal light valves with good image stability, high precision is required in configuring each layer, and this poses a problem that hinders the improvement of production yield. Ta. Regarding this point, according to research conducted by the inventor of the present application, it has been found that the AC voltage application electrodes, that is, the transparent conductive films 8 and 9 that drive the liquid crystal layer of the photoconductive liquid crystal light valve, and the AC voltage that drives the electroluminescent element 10. It has been found that the mutual interference caused by the electric field between the voltage application electrodes, that is, the transparent electrode 14 and the electrode 18, adversely affects the stability of the image.

Summary of the Invention [Purpose of the Invention] This invention has been made to solve the above-mentioned problems. The object of the present invention is to obtain a photoconductive liquid crystal light valve that has good image stability and can improve productivity by eliminating mutual interference caused by electric fields.

[Structure of the Invention] The photoconductive liquid crystal light valve according to the present invention includes a photoconductive layer and a liquid crystal layer that are stacked on each other, a pair of transparent electrodes that sandwich the photoconductive layer and the liquid crystal layer from the outside, and a pair of transparent electrodes that sandwich the photoconductive layer and the liquid crystal layer from the outside. A photoconductive liquid crystal light valve having an electroluminescent element disposed outside a write side electrode of an electrode, the light valve having a conductive layer disposed between the write side electrode and the electroluminescent element. It is characterized by

[Operation of the invention] The photoconductive liquid crystal light valve of the present invention eliminates mutual interference due to electric fields between the application electrode of the liquid crystal layer of the photoconductive liquid crystal light valve and the application electrode of the electroluminescent element by the conductive layer. There is.

EXAMPLE Hereinafter, an example of the present invention will be explained in detail based on the drawings. In FIG. 1, numerals 1 to 20 are the same as those in FIG. 2 in the conventional example, but a transparent conductive film 21 connected to ground is provided between the writing side transparent conductive film 9 and the electroluminescent element 10. Transparent insulating dielectric materials 22 and 23 arranged on both sides of this transparent conductive film 21 are laminated and inserted. Note that, for example, the transparent conductive film 21 is made of ITO, and the transparent insulating dielectrics 22 and 23 are made of 5i02.

Is the operation similar to that in the conventional example shown in Fig. 2?
During operation, the transparent conductive film 21 blocks the electric field applied to the electroluminescent element 10 by the electrodes for applying the AC voltage that drives the liquid crystal layer 1, that is, the transparent conductive films 8 and 9, and also blocks the electric field applied to the electroluminescent element 10. The electric field applied to the photoconductive liquid crystal light valve by the electrodes to which the alternating current voltage is applied, that is, the transparent electrode 14 and the electrode 18, is cut off. Note that the transparent insulating dielectrics 22 and 23 also play the role of maintaining and protecting the shielding effect of the transparent conductive film 21.

In this example, the potential of the transparent conductive film 21 is lowered to ground, but other effective reference potentials may be used.

Effects of the Invention As described above, the present invention provides a photoconductive liquid crystal light valve having a structure in which a photoconductive layer and a liquid crystal layer are laminated, and a pair of transparent electrodes are disposed outside the photoconductive layer and the liquid crystal layer. Since a conductive layer is provided between the electroluminescent element and the electroluminescent element, there is no mutual interference of electric fields, resulting in good image stability. Furthermore, each layer can be easily configured and uniform performance can be obtained, which has the effect of contributing to an improvement in production yield.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional structural diagram showing an embodiment of the present invention, Fig. 2 is a cross-sectional structural diagram showing a conventional embodiment, and Fig. 3 is a structural diagram of the drive section of each electrode constituting the X-Y matrix. It is. Explanation of symbols of main parts 1...Liquid crystal layer 5...Photoconductive film 8.9...Transparent conductive film 10...Electroluminescent element 11. 1
2...Glass substrate 14...Transparent electrode 16...Zinc sulfide layer 18...Metal electrode 21...
・Transparent conductive film 22゜23...Transparent insulating dielectric material

Claims (1)

[Claims] A photoconductive layer and a liquid crystal layer stacked on each other, a pair of transparent electrodes sandwiching the photoconductive layer and liquid crystal layer from the outside, and an electroluminescent element disposed outside a writing side electrode of the pair of transparent electrodes. 1. A photoconductive liquid crystal light valve comprising: a conductive layer disposed between the write-side electrode and the electroluminescent element.