Liquid crystal spatial light modulator with electrically isolated reflecting films connected to electrically isolated pixel portions of photo conductor

• US 5,384,649 A
• Filed: 12/21/1992
• Issued: 01/24/1995
• Est. Priority Date: 12/26/1991
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Akiyama, Koji, Tanaka, Yukio, Asayama, Junko, Takimoto, Akio, Kuratomi, Yasunori, Ogawa, Hisahito
• Primary Examiner(s): GROSS, ANITA P
• Application Number:
  US07/994,127
• Time in Patent Office: 764 Days
• Field of Search: 359/72, 359/67, 359/71
• US Class Current: 349/25
• CPC Class Codes: G02F 1/1354 having a particular photoconducting structure or material

Abstract

Pixel portions of a photoconductive layer each have a pin structure for providing a rectifying function and are substantially electrically isolated from one another by a highly resistant inter-pixel portion for preventing diffusion of electrical carriers. Data written into a liquid crystal layer by writing light is read out as an optical output by reading light. Reflecting films are provided on the pixel portions, respectively, and an output light blocking film is provided on the inter-pixel portion formed into a groove. The reflecting films and the output light blocking film are partially overlapped on each other so as to sufficiently block the reading light.

Claims

1. A spatial light modulator, comprising:

a first electrode;

a second electrode opposed to the first electrode;

a photoconductive layer electrically connected to the first electrode and including a plurality of pixel portions and an inter-pixel portion between the pixel portions, the pixel portions being electrically isolated from one another by the inter-pixel portions and an upper surface of the inter-pixel portion being at a level lower than a level of upper surfaces of the pixel portions;

a plurality of reflecting films electrically connected to the pixel portions of the photoconductive layer respectively, the reflecting films being electrically isolated from one another; and

a liquid crystal layer interposed between the reflecting films and the second electrode,

wherein the pixel portions each have a rectifying function between the reflecting film connected thereto and the first electrode, and the spatial light modulator further includes an input light blocking film for preventing writing light from being incident on the inter-pixel portion of the photoconductive layer.

2. A spatial light modulator according to claim 1, wherein the pixel portions of the photoconductive layer each have a diode structure, to be provided with the rectifying function.

3. A spatial light modulator according to claim 2, wherein the pixel portions of the photoconductive layer each include a p-type semiconductor layer, an i-type semiconductor layer provided on the p-type semiconductor layer, and an n-type semiconductor layer provided on the i-type semiconductor layer, to be provided with the rectifying function.

4. A spatial light modulator according to claim 3, wherein the inter-pixel portion includes an i-type semiconductor layer for substantially preventing electrical carriers generated in each pixel portion of the photoconductive layer from being diffused into the other pixel portions.

5. A spatial light modulator according to claim 4, further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer, for preventing reading light from being incident on the inter-pixel portion.

6. A spatial light modulator according to claim 3, further comprising an outer light blocking film provided on the inter-pixel portion of the photoconductive layer, for preventing reading light from being incident on the inter-pixel portion.

7. A spatial light modulator according to claim 2, further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer, for preventing reading light from being incident on the inter-pixel portion.

8. A spatial light modulator according to claim 1, further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer, for preventing reading light from being incident on the inter-pixel portion.

9. A spatial light modulator according to claim 1, further comprising a first transparent insulating substrate and a second transparent insulating substrate, wherein the first transparent insulating substrate supports the first electrode and the second transparent insulating substrate supports the second electrode.

10. A spatial light modulator according to claim 1, wherein the first electrode and the second electrode are transparent conductive electrodes.

11. A spatial light modulator, comprising:

a first electrode;

a second electrode opposed to the first electrode;

a photoconductive layer electrically connected to the first electrode and including a plurality of pixel portions and an inter-pixel portion between the pixel portions, the pixel portions being electrically isolated from one another by the inter-pixel portion;

a plurality of reflecting films electrically connected to the pixel portions of the photoconductive layer respectively, the reflecting films being electrically isolated form one another; and

a liquid crystal layer interposed between the reflecting films and the second electrode,

wherein the pixel portions each have a diode structure and a rectifying function between the reflecting film connected thereto and the first electrode,

wherein the pixel portions of the photoconductive layer each include a p-type semiconductor layer, an i-type semiconductor layer provided on the p-type semiconductor layer, and an n-type semiconductor layer provided on the i-type semiconductor layer, to be provided with the rectifying function,

wherein the inter-pixel portion includes an i-type semiconductor layer for substantially preventing electrical carriers generated in each pixel portion of the photoconductive layer form being diffused into the other pixel portions, and

wherein an upper surface of the inter-pixel portion of the photoconductive layer is at a level lower than a level of upper surfaces of the pixel portions of the photoconductive layer, and the i-type semiconductor layer is exposed at the upper surface of the inter-pixel portion, and the spatial light modulator further includes an input light blocking film for preventing writing light from being incident on the inter-pixel portion of the photoconductive layer.

12. A spatial light modulator according to claim 11, further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer, for preventing reading light from being incident on the inter-pixel portion.

13. A spatial light modulator according to claim 12, further comprising an insulating layer for covering the output light blocking film and for electrically isolating the output light blocking film from the reflecting films.

14. A spatial light modulator according to claim 13, wherein the insulting layer is formed of an organic polymer containing a material absorbing light having a wavelength in a specified range.

15. A spatial light modulator, comprising:

a first electrode;

a second electrode opposed to the first electrode;

a photoconductive layer electrically connected to the first electrode and including a plurality of pixel portions and an inter-pixel portion between the pixel portions, the pixel portions being electrically isolated from one another by the inter-pixel portion;

a plurality of reflecting films electrically connected to the pixel portions of the photoconductive layer respectively, the reflecting films being electrically isolated from one another; and

a liquid crystal layer interposed between the reflecting films and the second electrode,

wherein the pixel portions each have a rectifying function between the reflecting film connected thereto and the first electrode; and

further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer for preventing reading light from being incident on the inter-pixel portion and an insulating layer for covering the output light blocking film and for electrically isolating the output light blocking film from the reflecting films.

16. A spatial light modulator according to claim 15, wherein the insulting layer is formed of an organic polymer containing a material absorbing light having a wavelength in a specified range.

17. A spatial light modulator comprising:

a first electrode;

a second electrode opposed to the first electrode;

a photoconductive layer electrically connected to the first electrode and including a plurality of pixel portions and an inter-pixel portion between the pixel portions, the pixel portions being electrically isolated from one another by the inter-pixel portion;

a plurality of reflecting films electrically connected to the pixel portions of the photoconductive layer respectively, the reflecting films being electrically isolated from one another; and

a liquid crystal layer interposed between the reflecting films and the second electrode,

wherein the pixel portions each have a diode structure and a rectifying function between the reflecting film connected thereto and the first electrode; and

further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer for preventing reading light from being incident on the inter-pixel portion and an insulating layer for covering the output light blocking film and for electrically isolating the output light blocking film from the reflecting films.

18. A spatial light modulator according to claim 17, wherein the insulting layer is formed of an organic polymer containing a material absorbing light having a wavelength in a specified range.

19. A spatial light modulator, comprising:

a first electrode;

a second electrode opposed to the first electrode;

a photoconductive layer electrically connected to the first electrode and including a plurality of pixel portions and an inter-pixel portion between the pixel portions, the pixel portions being electrically isolated from one another by the inter-pixel portion;

a plurality of reflecting films electrically connected to the pixel portions of the photoconductive layer respectively, the reflecting films being electrically isolated from one another; and

a liquid crystal layer interposed between the reflecting films and the second electrode,

wherein the pixel portions each have a diode structure and a rectifying function between the reflecting film connected thereto and the first electrode,

wherein the pixel portions of the photoconductive layer each include a p-type semiconductor layer, an i-type semiconductor layer provided on the p-type semiconductor layer, and an n-type semiconductor layer provided on the i-type semiconductor layer, to be provided with the rectifying function; and

p1 further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer for preventing reading light from being incident on the inter-pixel portion and an insulating layer for covering the output light blocking film and for electrically isolating the output light blocking film from the reflecting films.

20. A spatial light modulator according to claim 19, wherein the insulting layer is formed of an organic polymer containing a material absorbing light having a wavelength in a specified range.

21. A spatial light modulator, comprising:

a first electrode;

a second electrode opposed to the first electrode;

a photoconductive layer electrically connected to the first electrode and including a plurality of pixel portions and an inter-pixel portion between the pixel portions, the pixel portions being electrically isolated from one another by the inter-pixel portion;

a plurality of reflecting films electrically connected to the pixel portions of the photoconductive layer respectively, the reflecting films being electrically isolated from one another; and

a liquid crystal layer interposed between the reflecting films and the second electrode.

wherein the pixel portions each have a diode structure and a rectifying function between the reflecting film connected thereto and the first electrode,

wherein the pixel portions of the photoconductive layer each include a p-type semiconductor layer, an i-type semiconductor layer provided on the p-type semiconductor layer, and an n-type semiconductor layer provided on the i-type semiconductor layer, to be provided with the rectifying function, and

wherein the inter-pixel portion includes an i-type semiconductor layer for substantially preventing electrical carriers generated in each pixel portion of the photoconductive layer from being diffused into the other pixel portions; and

further comprising an output light blocking film provided on the inter-pixel portion of the photoconductive layer for preventing reading light from being incident on the inter-pixel portion and an insulating layer for covering the output light blocking film and for electrically isolating the output light blocking film from the reflecting films.

22. A spatial light modulator according to claim 21, wherein the insulting layer is formed of an organic polymer containing a material absorbing light having a wavelength in a specified range.

23. A method for producing a spatial light modulator, comprising the steps of:

laminating a plurality of layers to form a photoconductive layer having a diode structure; and

selectively etching a specified area of at least one of the plurality of layers to obtain a plurality of pixel portions with no part thereof being etched and an inter-pixel portion for substantially electrically isolating the pixel portions from one another, the inter-pixel portion being obtained between the pixel portions and an upper surface of the inter pixel portion being at a level lower than a level of upper surfaces of the pixel portions,

further comprising the step of forming an input light blocking film for preventing writing light from being incident on the inter-pixel portion of the photoconductive layer.

24. A method for producing a spatial light modulator according to claim 23, wherein a plurality of reflecting films are formed on the photoconductive layer, and the step of etching is performed using the reflecting films as masks.

25. A method for producing a spatial light modulator, comprising the steps of:

laminating a plurality of layers to form a photoconductive layer having a diode structure; and

selectively etching a specified area of at least one of the plurality of layers to obtain a plurality of pixel portions with no part thereof being etched and an inter-pixel portion for substantially electrically isolating the pixel portions from one another, the inter-pixel portion being obtained between the pixel portions,

wherein a plurality of reflecting films are formed on the photoconductive layer, and the step of etching is performed using the reflecting films as masks; and

further comprising the step of, after the step of etching, depositing a metal simultaneously on the reflecting films and on the inter-pixel portion to form an output light blocking film on the inter-pixel portion.

26. A method for producing a spatial light modulator according to claim 25, further comprising the step of, after the step of forming the output light blocking film, further etching side walls of the photoconductive layer using the output light blocking film as a mask.

27. A method for producing a spatial light modulator according to claim 25, further comprising the step of, after the step of forming the output light blocking films, forming an insulating layer for covering the output light blocking film.