Area active backlight with steerable light source

• US 8,026,997 B2
• Filed: 06/26/2009
• Issued: 09/27/2011
• Est. Priority Date: 01/28/2009
• 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:
  US12/492,609
• Publication Number:
  US 20100188602A1
• Time in Patent Office: 823 Days
• Field of Search: 362/612, 362/615, 362/561, 362/607, 362/616, 349/62, 349 65- 69, 349/113, 349/139, 359619-623, 345/33, 385/133
• US Class Current: 349/65
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0078 Side-by-side arrangements, e.g. for large area displays
• CPC Class Codes: G02B 6/3522 the optical element enabling or impairing total internal reflection using evanescent coupling G02B6/3536
• CPC Class Codes: G02B 6/3536 involving evanescent coupling variation, e.g. by a moving element such as a membrane which changes the effective refractive index mode converters G02B6/14; adjustable lateral coupling between waveguides G02B6/283; electro- optical refractive index variations G02F1/0118
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133601 for spatial active dimming

Abstract

A liquid crystal display includes a backlight. The backlight includes a plurality of waveguides to selectively direct light. A set of selection elements in combination with the backlight selectively direct light to the front of the display.

Claims

1. 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;

(e) said display includes a plurality of selection elements associated with said light waveguides that selectively inhibit the transmission of light toward said liquid crystal layer, wherein said selection elements includes liquid crystal material in a polymer matrix and that alternates between an on and an off state, respectively, upon selective application of a voltage;

(f) wherein the combination of said waveguides and said selection elements provide light to regions of said liquid crystal layer in a temporally sequential 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 liquid crystal material in said polymer matrix is sandwiched between conductive layers.

8. The display of claim 7 wherein said transmission is based upon the application of a voltage to at least one of said conductive layers.

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

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

11. The display of claim 1 wherein said selection elements are light extractors.

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

13. The display of claim 1 wherein said selection elements include micro optical structures.

14. The display of claim 6 wherein said micro optic structures include a thin film layer forming a lens and shutter.

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

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

17. The display of claim 10 wherein said light steering mechanism is scanned from top to bottom of said display.

18. The display of claim 10 wherein said light steering mechanism includes a mechanical shutter.

19. 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.

20. 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 arranged in a one-dimensional parallel array extending from one side to the other side of said display;

(e) said backlight includes at least one light source associated with each of said waveguides;

(f) said display includes a plurality of selection elements associated with each of said waveguides such that selective activation of one of said selection elements results in light not being substantially inhibited that is directed light toward said liquid crystal layer while light is substantially inhibited that is directed toward said liquid crystal layer where one of said selection element is not selected;

(g) said selection elements include liquid crystal material in a polymer matrix sandwiched between conductive layers;

(h) each of said waveguides are provided with light in a sequential manner while a plurality of associated selection elements for each of said waveguides are selected so that light is selectively emitted from each of said respective waveguide.

21. The display of claim 20 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.