ILLUMINATION DEVICES AND METHODS OF FABRICATION THEREOF

• US 20100302616A1
• Filed: 05/27/2010
• Published: 12/02/2010
• Est. Priority Date: 05/29/2009
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Bita, Ion, Ganti, SuryaPrakash, Arbuckle, Brian W., Chan, Clayton Ka Tsun, Patel, Sapna
• Granted Patent: US 9,121,979 B2
• Time in Patent Office: Days
• US Class Current: 359/291
• 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 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02F 1/133616 Front illuminating devices

Abstract

Illumination devices and methods of making same are disclosed. In one embodiment, a display device includes a light modulating array and a light guide configured to receive light into at least one edge of the light guide. The light guide can be characterized by a first refractive index. The display device can also include a light turning layer disposed such that the light guide is at least partially between the turning layer and the array. The turning layer can comprise an inorganic material characterized by a second refractive index that is substantially the same as the first refractive index.

Claims

1. A display device comprising:

an array of light modulating elements;

a light guide disposed over the array, the light guide having at least one edge configured to receive light into the light guide, the light guide characterized by a first refractive index; and

a turning layer disposed such that the light guide is at least partially between the turning layer and the array, the turning layer comprising an inorganic material characterized by a second refractive index that is substantially the same as the first refractive index.

2. The device of claim 1, wherein the light guide comprises an inorganic material.

3. The device of claim 2, wherein the light guide comprises an aluminosilicate.

4. The device of claim 2, wherein the light guide comprises sapphire.

5. The device of claim 1, wherein the turning layer comprises silicon oxynitride (SiO_xN).

6. The device of claim 5, wherein the light guide comprises sapphire or an aluminosilicate.

7. The device of claim 1, wherein the first refractive index is between about 1.45 and 2.06.

8. The device of claim 1, further comprising a light source configured to provide light into the edge of the light guide.

9. The device of claim 1, further comprising an isolation layer disposed at least partially between the light guide and the array, the isolation layer characterized by a third refractive index that is substantially less than the first refractive index.

10. The device of claim 1, wherein the turning layer further comprises a plurality of light turning features, each light turning feature being configured to receive at least a portion light which is propagating through the turning layer and reflect at least a portion of the received light toward the array.

11. The device of claim 10, wherein each light turning feature comprises a depression formed in a surface of the turning layer.

12. The device of claim 10, wherein each light turning feature has a generally frustoconical shape.

13. The device of claim 10, wherein each light turning feature has a tapered sidewall.

14. The device of claim 13, wherein each turning feature comprises an interferometric modulator disposed on the tapered sidewall.

15. The device of claim 14, wherein the interferometric modulator comprises a first reflective layer, a second layer, and a third partially reflective layer disposed respectively on the tapered sidewall, wherein the first layer is configured to receive light propagating within the turning layer and reflect at least a portion of the received light toward the array.

16. The device of claim 15, wherein the first, second, and third layers are configured to block a portion of light incident on the turning layer from reflecting from the light guide.

17. The device of claim 1, wherein the light guide further comprises a plurality of light turning features, each light turning feature comprising a tapered sidewall and an optical stack formed thereon.

18. The device of claim 1, further comprising:

a processor that is configured to communicate with the array of light modulating elements, said processor being configured to process image data; and

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

19. The device of claim 18, further comprising a driver circuit configured to send at least one signal to the array of light modulating elements.

20. The device of claim 19, further comprising a controller configured to send at least a portion of the image data to said driver circuit.

21. The device of claim 18, further comprising an image source module configured to send the image data to the processor.

22. The device of claim 21, wherein said image source module comprises at least one of a receiver, transceiver, and transmitter.

23. The device of claim 18, further comprising an input device configured to receive input data and to communicate said input data to said processor.

24. A display device comprising:

a light modulating device; and

a light guide disposed over the light modulating device, the light guide being configured to receive light into at least one edge of the light guide, the light guide light comprising

a first light-transmissive inorganic substrate layer characterized by a first refractive index, and

a second light-transmissive inorganic substrate layer disposed over the first light-transmissive inorganic substrate layer, the second light-transmissive inorganic substrate layer characterized by a second refractive index that is substantially the same as the first refractive index, the second inorganic substrate layer comprising a plurality of light turning features configured to receive at least a portion of light propagating within the light guide and reflect at least a portion of the received light toward the light modulating device.

25. The display device of claim 24, further comprising a plurality of optical masks formed on the light turning features.

26. The display device of claim 25, wherein the optical masks comprise dark coatings.

27. The display device of claim 25, wherein the optical masks comprise interferometric stacks.

28. A display device, comprising:

means for modulating light;

means for guiding light disposed over the modulating means, the guiding means characterized by a first refractive index; and

means for turning light disposed such that the guiding means is at least partially between the modulating means and the turning means, the turning means comprising an inorganic material characterized by a second refractive index that is substantially the same as the first refractive index.

29. A method of making a light guide for a reflective display, comprising:

providing an inorganic substrate, the inorganic substrate having an upper surface, a lower surface, and a first refractive index;

depositing an inorganic layer over the upper surface of the inorganic substrate;

adjusting a chemical characteristic of the layer such that the refractive index of the layer has a second refractive index, the second refractive index substantially matching the first refractive index; and

etching the layer to form at least one light turning feature in the layer, the light turning feature configured to receive light propagating in the light guide and reflect at least a portion of the received light toward the lower surface of the inorganic substrate.

30. The method of claim 29, wherein the layer comprises silicon oxynitride.

31. The method of claim 30, wherein the chemical characteristic is the N₂O:

NH₃ molar ratio.

32. A method of making a light guide for a reflective display, comprising:

molding a layer on a top surface of an inorganic substrate to form at least one light turning feature in the layer, the light turning feature configured to reflect light propagating in the light guide toward a bottom surface of the inorganic substrate; and

exposing the layer to heat until the refractive index of the layer substantially matches the refractive index of the inorganic substrate.