Area active backlight with steerable backlight

• US 7,982,823 B1
• Filed: 06/17/2010
• Issued: 07/19/2011
• Est. Priority Date: 06/17/2010
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Feng, Xiao-fan
• Primary Examiner(s): Ullah; Akm E
• Application Number:
  US12/817,412
• Time in Patent Office: 397 Days
• Field of Search: 349 62- 69, 349/139, 349/141, 349/15, 362/615, 362/612, 362/607, 362/551, 385/129, 385/140, 385/147, 345/84, 345/86, 345/87, 345/102
• US Class Current: 349/62
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays
• CPC Class Codes: G02F 1/1326 Liquid crystal optical waveguides or liquid crystal cells specially adapted for gating or modulating between optical waveguides
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133602 Direct backlight
• CPC Class Codes: G02F 1/133622 Colour sequential illumination
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A liquid crystal display includes a backlight that provides light and selectively modifies the transmission of light from the backlight to the front of the display. The backlight includes a plurality of spaced apart light waveguides and a plurality of selection elements associated with the light waveguides that change the characteristics of the material of the light waveguides to selectively direct the transmission of light toward the liquid crystal layer. The combination of the waveguides and the selection elements provide light to the front of the display in a temporal manner during a frame.

Claims

1. A display comprising:

(a) a liquid crystal layer;

(b) a backlight that provides light of a plurality of colors to said liquid crystal layer;

(c) said liquid crystal layer selectively modifying the transmission of light from said backlight to the front of said display;

(d) said backlight includes a plurality of spaced apart light waveguides, each said wavequide adapted to guide light characterized as having a color included in a subset of said plurality of colors, where said subset is less than all of said plurality of colors, said waveguide adapted to not guide light characterized as having a color not included in said subset;

(e) said display includes a plurality of selection elements associated with said light waveguides that change the characteristics of the material of said light waveguides to selectively direct the transmission of light toward said liquid crystal layer;

(f) wherein the combination of said waveguides and said selection elements provide light to said front of said display in a temporal manner during a frame.

2. The display of claim 1 wherein said plurality of said waveguides are arranged in a parallel arrangement with respect to one another.

3. The display of claim 2 further including a light steering mechanism that selectively directs light to at least one, and less than all, of said light waveguides at any particular time.

4. The display of claim 3 wherein at least one of said selection elements is associated with a respective one of said plurality of waveguides.

5. The display of claim 4 wherein for a respective one of said plurality of waveguides that light is only substantially emitted from said respective guide at a position associated with a selected respective one of said selection elements.

6. The display of claim 5 wherein said combination results in a temporal multiplexed illumination of said display.

7. The display of claim 1 wherein said material includes at least one of polymer dispersed liquid crystals and in plane switching.

8. The display of claim 1 wherein said waveguides include a plurality of stacked waveguides.

9. The display of claim 8 wherein each of said waveguides receives a different color of light of said backlight.

10. The display of claim 1 wherein said backlight includes a plurality of light emitting diodes that provides light to respective said waveguides.

11. The display of claim 1 wherein said backlight includes a plurality of one-dimensional said waveguides.

12. The display of claim 1 wherein said display provides a color output and is free from including color filters.

13. The display of claim 1 wherein said selection elements use frustrated total internal reflection.

14. The display of claim 1 wherein said temporal aspect of said combination results in a decrease in motion blur.

15. The display of claim 1 wherein a plurality of said waveguides extend across the entire said display.

16. The display of claim 1 wherein regions of an image to be displayed that is determined not to have motion have a slower rate of providing light to said waveguides than regions of said image to be display that is determined to have motion.

17. A display comprising:

(a) a liquid crystal layer;

(b) a backlight that provides light to said liquid crystal layer;

(c) said liquid crystal layer selectively modifying the transmission of light from said backlight to the front of said display;

(d) said backlight includes a plurality of spaced apart light waveguides in both a direction planar to said liquid crystal layer and perpendicular to said liquid crystal layer, wherein each of said light wavequides perpendicular to said liquid crystal layer is provided with a different colored light;

(e) said display includes a plurality of selection elements associated with said light waveguides that change the characteristics of the material of said light waveguides to selectively direct the transmission of light toward said liquid crystal layer;

(f) wherein the combination of said waveguides and said selection elements provide light to said front of said display in a temporal manner during a frame.

18. The display of claim 17 wherein each of said light waveguides perpendicular to said liquid crystal layer has a plurality of regions therein that selectively direct light out of said display in an arrangement consistent with corresponding sub-pixels of said display.

19. The display of claim 18 wherein said corresponding sub-pixels and said plurality of regions have the same color.

20. The display of claim 18 wherein said display is free from including color filters.