Angle sweeping holographic illuminator

• US 7,845,841 B2
• Filed: 08/28/2006
• Issued: 12/07/2010
• Est. Priority Date: 08/28/2006
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Sampsell, Jeffrey B.
• Primary Examiner(s): Negron; Ismael
• Application Number:
  US11/467,879
• Publication Number:
  US 20080049450A1
• Time in Patent Office: 1,562 Days
• Field of Search: 362/615, 362/603, 362/606, 362/607, 362/619, 362/625, 362/626, 362/620, 362/561, 362/612, 362/555, 362/511, 362/330, 359/34, 359/13, 359/14, 359/15, 359/32, 359/33
• US Class Current: 362/625
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0048 with stepwise taper

Abstract

Light guides of various shapes are configured to adjust the angle of the individual light rays in a bundle of light within the light guide so that the angle of the respective rays are adjusted towards an acceptance angle of a hologram embedded within the light guide. The hologram embedded in the light guide is configured to eject individual rays towards the display elements when the respective rays are within a range of acceptance angles.

Claims

1. An apparatus comprising:

a light guide having first and second planar opposing surfaces with at least a portion of the first surface tilted with respect to the second surface to define a taper angle, the light guide further including sides disposed about the first and second surfaces; and

a hologram disposed in the light guide, the hologram configured to eject injected light out of the light guide, the tilted first surface altering the distribution of angles that light is incident on the hologram as the light propagates through the light guide, wherein

the hologram ejects light rays that are incident on the hologram within a range of acceptance angles,

the taper angle is less than about one-half of the range of acceptance angles and is less than about 2 degrees, and

the light guide is configured to allow some of the light rays to reflect more than once off of one of the first and second opposing surfaces so that the light rays are incident on the hologram within the range of acceptance angles.

2. The apparatus of claim 1, wherein the hologram is positioned on the first surface.

3. The apparatus of claim 1, wherein the hologram is positioned on the second surface.

4. The apparatus of claim 1, wherein the hologram is positioned between the first and second surfaces.

5. The apparatus of claim 1, wherein the range of acceptance angles is less than about 0.25 degree.

6. The apparatus of claim 1, wherein the range of acceptance angles is less than about 0.5 degree.

7. The apparatus of claim 1, wherein the range of acceptance angles is less than about 1 degree.

8. The apparatus of claim 1, further comprising a spatial light modulator disposed with respect to the light guide to receive the light ejected from the light guide, said spatial light modulator comprising interferometric modulators.

32. The apparatus of claim 1, wherein the first surface comprises at least one step, wherein the hologram is disposed on the second surface.

33. The apparatus of claim 32, wherein the at least one step comprises a surface that is normal to the hologram.

34. The apparatus of claim 32, wherein the at least one step comprises a surface that is inclined with respect to the hologram.

9. An apparatus comprising:

a light source;

a light guide having first and second planar opposing surfaces with at least a portion of the first surface tilted with respect to the second surface to define a taper angle, the light guide further including sides disposed about the first and second surfaces, the light source disposed with respect to one of the sides to inject light into the light guide;

a hologram disposed in the light guide, the hologram configured to eject the injected light out of the light guide, the tilted first surface altering the distribution of angles that the light is incident on the hologram as the light propagates through the light guide, wherein

the hologram ejects light rays that are incident on the hologram within a range of acceptance angles,

the taper angle is less than about one-half of the range of acceptance angles,

the light guide is configured to allow some of the light rays to reflect more than once off of one of the first and second opposing surfaces so that the light rays are incident on the hologram within the range of acceptance angles, and

the taper angle is less than about 2 degrees; and

a display element disposed with respect to the light guide to receive the light ejected from the light guide.

10. The apparatus of claim 9, wherein the light guide is wedge shaped.

11. The apparatus of claim 9, wherein at least a portion of the second surface is tilted with respect to the hologram.

12. The apparatus of claim 9, wherein the light guide comprises a plurality of tilted portions, and wherein each of the plurality of tilted portions are at a first angle with respect to the hologram.

13. The apparatus of claim 9, wherein a first tilted portion is at a first angle with respect to the hologram and a second tilted portion is at a second angle with respect to the hologram.

14. The apparatus of claim 9, wherein the hologram is configured to eject light out of the light guide through the first surface of the light guide.

15. The apparatus of claim 9, wherein the hologram is configured to eject light out of the light guide through the second surface of the light guide.

16. The apparatus of claim 9, wherein the hologram is positioned on the first surface.

17. The apparatus of claim 9, wherein the hologram is positioned on the second surface.

18. The apparatus of claim 9, wherein the hologram is positioned between the first and second surfaces.

19. The apparatus of claim 9, wherein the range of acceptance angles is less than about 0.25 degree.

20. The apparatus of claim 9, wherein the range of acceptance angles is less than about 0.5 degree.

21. The apparatus of claim 9, wherein the range of acceptance angles is less than about 1 degree.

22. The apparatus of claim 9, wherein the hologram reflects light incident on the hologram that is within the range of acceptance angles so that the reflected light is ejected from the light guide towards the display element.

23. The apparatus of claim 9, wherein the hologram transmits light incident on the hologram that is within the range of acceptance angles so that the transmitted light is ejected from the light guide towards the display element.

24. The apparatus of claim 9, wherein an angle of respective light rays with respect to the hologram is increased when the respective light rays are reflected from the first surface.

25. The apparatus of claim 9, wherein the display element is positioned proximate to the first surface.

26. The apparatus of claim 9, wherein the display element is positioned proximate to the second surface.

27. The apparatus of claim 9, wherein the light source and the light guide comprise a backlight.

28. The apparatus of claim 9, wherein the light source and the light guide comprise a frontlight.

29. The apparatus of claim 9, wherein the display element comprises one of an EL, LCD, OLED, STN LCD, and TFT LCD display element.

30. The apparatus of claim 9, wherein the display element comprises a spatial light modulator.

31. The apparatus of claim 30, wherein the spatial light modulator comprises an interferometric modulator.

35. The apparatus of claim 9, wherein the light source is positioned proximate a first end of the light guide.

36. The apparatus of claim 35, wherein a second light source is positioned proximate a second end of the light guide.

37. The apparatus of claim 35, wherein a reflector is positioned proximate a second end of the light guide.

38. The apparatus of claim 9, further comprising:

a display comprising the light source, the light guide, the hologram, and the display element;

a processor that is configured to communicate with the display element, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

39. The apparatus of claim 38, further comprising an input device configured to receive input data and to communicate the input data to the processor.

40. The apparatus of claim 38, further comprising a driver circuit configured to send at least one signal to the display element.

41. The apparatus of claim 40, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

42. The apparatus of claim 38, further comprising an image source module configured to send the image data to the processor.

43. The apparatus of claim 42, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.