Enhanced off-axis viewing performance and luminous efficiency of a liquid crystal display employing fiberoptic faceplate elements

• US 5,442,467 A
• Filed: 03/21/1994
• Issued: 08/15/1995
• Est. Priority Date: 03/21/1994
• Status: Expired due to Term

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Bruce, Richard, Sprague, Robert A., Silverstein, Louis D., Fiske, Thomas G.
• Primary Examiner(s): Gross, Anita Pellman
• Assistant Examiner(s): MILLER, CHARLES LELAND
• Application Number:
  US08/215,454
• Time in Patent Office: 512 Days
• Field of Search: 359/42, 359/49, 359/68, 359/69, 385/129, 385/130, 385/132, 385/901
• US Class Current: 349/159
• CPC Class Codes: G02B 6/08 with fibre bundle in form of plate
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133524 Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides
• CPC Class Codes: G02F 1/133604 with lamps
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

A transmissive, backlit color twisted-nematic or super-twisted-nematic liquid crystal display employing a front fiber-optic faceplate as a front retaining element of a liquid crystal cell that increases viewing angle between the display and a viewer while minimizing or eliminating undesirable variations in luminance, contrast ratio and chromaticity is described. This novel configuration effectively decouples the liquid crystal cell and other optical elements behind the front fiber optic faceplate from the angular orientation of the viewer with respect to the display. The liquid crystal display described in this invention further provides a high quality color display, without viewing parallax, using a color selection filter mosaic outside of the liquid crystal cell. The display also increases luminous efficiency and improves color saturation by concentrating the transmission of available backlight illumination through the use of a rear fiber-optic faceplate and a second rear-mounted mosaic of color interference filters.

Claims

1. A direct-view, rear-illuminated liquid crystal display device, comprising in sequential order:

a backlight source;

a rear diffuser layer;

a rear linear polarizer; and

a liquid crystal cell including a rear glass layer with addressing elements and pixel ITO electrodes, a liquid crystal layer and a front fiber-optic faceplate as a front containing element substantially adjacent to said liquid crystal layer, said front fiber-optic faceplate having a small light input acceptance cone at a rear face adjacent to said liquid crystal layer and a large light output exit cone at a front face opposite said rear face to improve a viewing angle through the liquid crystal display device.

2. The direct-view liquid crystal display device of claim 1, wherein a mosaic of color selection filters is located outside of said liquid crystal cell.

3. The direct-view liquid crystal display device of claim 1, further comprising a mosaic array of color absorption filters located on said front face of said front fiber-optic faceplate.

4. The direct-view liquid crystal display device of claim 1, further comprising a front polarizer adjacent to said front fiber-optic faceplate.

5. The direct-view liquid crystal display device of claim 4, wherein said front polarizer is located outside of said liquid crystal cell adjacent to said front face of said fiber-optic faceplate.

6. The direct-view liquid crystal display device of claim 1, wherein said front polarizer is located within said liquid crystal cell adjacent to said rear face of said fiber-optic faceplate.

7. The direct-view liquid crystal display device of claim 1, wherein the light input acceptance cone on said rear face is substantially less than the light output exit cone on said front face.

8. The direct-view liquid crystal display device of claim 1, wherein the light output exit cone on said front face is substantially greater than the light input acceptance cone on said rear face.

9. The direct-view liquid crystal display device of claim 1, wherein said liquid crystal layer is comprised of twisted nematic material.

10. The direct-view liquid crystal display device of claim 1, wherein said liquid crystal layer is comprised of super-twisted nematic material.

11. The direct-view liquid crystal display device of claim 1, further comprising a rear fiber-optic faceplate located between said rear diffuser and said rear polarizer.

12. A direct-view backlit liquid crystal display device, comprising in sequential order:

a backlight source;

a rear diffuser layer;

a rear fiber-optic faceplate, said rear fiber-optic faceplate having a large light input acceptance cone at a rear face adjacent to said diffuser and a small light output exit cone output at a front face opposite said rear face;

a rear polarizer; and

a liquid crystal cell including a rear glass layer with addressing elements and pixel ITO electrodes, a liquid crystal layer and a front fiber-optic faceplate as a front containing element substantially adjacent to said liquid crystal layer, said front fiber-optic faceplate having a small light input acceptance cone at a rear face adjacent to said liquid crystal layer and a large light output exit cone at a front face opposite said rear face to improve a viewing angle through the liquid crystal display device.

13. The direct-view liquid crystal display device of claim 12, further comprising a front polarizer located outside of said liquid crystal cell adjacent to said front face of said front fiber-optic faceplate.

14. The direct-view liquid crystal display device of claim 12, further comprising a front polarizer located within said liquid crystal cell adjacent to said rear face of said front fiber-optic faceplate.

15. The direct-view liquid crystal display device of claim 12, wherein the light input acceptance cone on said rear face of said rear fiber-optic faceplate is substantially greater than the light output exit cone on said front face of said rear fiber-optic faceplate.

16. The direct-view liquid crystal display device of claim 12, wherein the light output exit cone on said front face of said rear fiber-optic faceplate is substantially less than the light input acceptance cone on said rear face of said rear fiber-optic faceplate.

17. The direct-view liquid crystal display device of claim 12, wherein said liquid crystal layer is comprised of twisted nematic material.

18. The direct-view liquid crystal display device of claim 12, wherein said liquid crystal layer is comprised of super-twisted nematic material.

19. A direct-view backlit liquid crystal display device, comprising in sequential order:

a backlight source;

a rear diffuser layer;

a rear fiber-optic faceplate, said rear fiber-optic faceplate having a large light input acceptance cone at a rear face adjacent to said diffuser and a small light output exit cone output at a front face opposite said rear face;

a rear polarizer;

a liquid crystal cell including a rear glass layer with addressing elements and pixel ITO electrodes, a liquid crystal layer and a front fiber-optic faceplate as a front containing element substantially adjacent to said liquid crystal layer, said front fiber-optic faceplate having a small light input acceptance cone at a rear face adjacent to said liquid crystal layer and a large light output exit cone at a front face opposite said rear face to improve a viewing angle through the liquid crystal display device;

a mosaic array of color absorption filters located on said front face of said front fiber-optic faceplate; and

a front polarizer.

20. The direct-view liquid crystal display device of claim 19, further comprising a mosaic array of color interference filters or spectrally-selective holographic filters between said rear fiber-optic faceplate and said rear polarizer, said array of color interference or holographic filters corresponding exactly with said array of color absorption filters such that corresponding elements of each array correspond to same color elements of the other array and to same color pixels of the display device.

21. The direct-view liquid crystal display device of claim 19, further comprising a mosaic array of color interference filters or spectrally-selective holographic filters located between said rear fiber-optic faceplate and said front fiber-optic faceplate, said array of color interference or holographic filters corresponding exactly with said array of color absorption filters such that corresponding elements of each array correspond to same color elements of the other array and to same color pixels of the display device.