ILLUMINATION APPARATUS AND METHODS

• US 20090284985A1
• Filed: 05/16/2008
• Published: 11/19/2009
• Est. Priority Date: 05/16/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Xu, Gang, Bita, Ion
• Granted Patent: US 8,118,468 B2
• Time in Patent Office: Days
• US Class Current: 362/617
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• 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 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area

Abstract

Disclosed are apparatus and methods for illuminating a display. In certain embodiments, the illumination apparatus includes a light guide that receives light from a light generator along an edge of the light guide and directs the received light via light extractor features (e.g., grooves) towards a display. The light guide includes at least two sets of light extractor features that are rotated with respect to each other so as to reduce a shadowing effect on the display when the display is viewed from within a specific range of viewing angles. In further embodiments, the spacing or orientation of each or one of the extractor feature sets may also be adjusted so that other visual artifacts, such as a Moiré effect, are reduced.

Claims

1. An apparatus for illuminating a display, comprising:

a light source for providing a plurality of light beams; and

a light guide positioned to receive the light beams at a side surface of the light guide, wherein the light guide further includes at least a first and second set of light extractor features that are arranged with respect to each other so as to direct at least some of the received light beams out a bottom surface of the light guide towards a display, wherein the first and second set of light extractor features are rotated with respect to each other so that when the first set of light extractor features causes a shadow along a first region of the display as would be viewed from one of a predetermined range of viewing angles, the second set of light extractor features illuminates such first region so as to substantially eliminate the shadow in such first region.

2. The apparatus as recited in claim 1, wherein the predetermined range of viewing angles are within a plane that is perpendicular to the display and substantially parallel to said side surface.

3. The apparatus as recited in claim 1, wherein the first and second light extractor features each have a feature spacing that is selected so as to minimize a Moiré

effect produced when viewing the display.

4. An apparatus as recited in claim 3, wherein the first set and the second set of light extractor features each include a plurality of parallel grooves with varying spacing between adjacent pairs of grooves.

5. The apparatus as recited in claim 1, wherein the first and second light extractor features each have an orientation that is selected to minimize a Moiré

effect produced when viewing the display.

6. The apparatus as recited in claim 5, wherein the first set and the second set of light extractor features each include a plurality of parallel grooves with varying rotations, with respect to each other, that are selected to minimize a Moiré

effect produced when viewing the display.

7. The apparatus as recited in claim 1, wherein the one or more light guide substrate(s) take the form of a single transparent light guide substrate having the first and second set of light extractor features.

8. The apparatus as recited in claim 1, wherein the one or more light guide substrate(s) take the form of a first transparent light guide substrate having the first set of light extractor features and a second transparent light guide substrate having the second set of light extractor features positioned over or beneath the first transparent light guide substrate.

9. The apparatus as recited in claim 8, wherein the first and second light guide substrates form part of a stack of transparent layers that include one or more other transparent light guide substrates.

10. The apparatus as recited in claim 1, wherein the predetermined range of viewing angles include ±

30°

from a normal to a surface of the display.

11. The apparatus as recited in claim 1, wherein the predetermined range of viewing angles include ±

60°

from a normal to a surface of the display.

12. The apparatus of claim 1, further comprising:

a display;

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

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

13. The apparatus of claim 12, wherein the first and second sets of light extractor features are arranged to provide a front light for the display.

14. The apparatus of claim 12, wherein the first and second sets of light extractor features are arranged to provide a backlight light for the display.

15. The apparatus as recited in claim 12, further comprising:

a driver circuit configured to send at least one signal to said display.

16. The apparatus as recited in claim 15, further comprising:

a controller configured to send at least a portion of said image data to said driver circuit.

17. The apparatus as recited in claim 12, further comprising:

an image source module configured to send said image data to said processor.

18. The apparatus as recited in claim 17, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

19. The apparatus as recited in claim 12, further comprising:

an input device configured to receive input data and to communicate said input data to said processor.

20. The apparatus of claim 12, wherein the display is an interferometric modulator.

21. The apparatus of claim 12, wherein the display is a liquid crystal display.

22. The apparatus of claim 12, further comprising a diffuser placed in front of the display to further spread light distribution from the light guide across the display.

23. The apparatus of claim 1, wherein the one or more light sources are arranged to generate the light beams along a line.

24. The apparatus of claim 1, wherein a feature depth of one or more features is varied within a same feature to compensate for a reduced illumination caused by the rotation of such feature.

25. The apparatus of claim 1, wherein a feature depth varies across the first and/or second feature set.

26. The apparatus as recited in claim 1, wherein the first and second light extractor features each have an orientation that is further selected to compensate for off-center emission of the light beams from the light generator.

27. An apparatus for illuminating a display, comprising:

means for generating a plurality of light beams; and

means for directing at least some of the light beams out a bottom surface of the light guide substrate(s) towards a display so as to provide a predetermined range of viewing angles for the display while substantially eliminating shadows within the predetermined range of viewing angles and minimize a Moiré

effect.

28. A method of illuminating a display, comprising:

generating a plurality of light beams at a side surface of a light guide substrate(s) having at least a first and second set of light extractor features; and

directing at least some of the received light beams out a bottom surface of the light guide substrate(s) towards a display so as to provide a predetermined range of viewing angles for the display, wherein when the first set of light extractor features cause a shadow along a first region of the display at a particular one of the viewing angles, the second set of light extractor features illuminate such first region so as to substantially eliminate the shadow in such first region.