Optical microstructures for light extraction and control

• US 7,486,854 B2
• Filed: 01/24/2006
• Issued: 02/03/2009
• Est. Priority Date: 01/24/2006
• Status: Expired due to Fees

• Current Assignee: Rambus Delaware
• Original Assignee: Uni-Pixel Displays Incorporated (Uni-Pixel Incorporated)
• Inventors: Gobell, Garth, Van Ostrand, Dan, King, Carey
• Primary Examiner(s): KIM, ELLEN E
• Application Number:
  US11/338,251
• Publication Number:
  US 20070172171A1
• Time in Patent Office: 1,106 Days
• Field of Search: 385/31, 385/39
• US Class Current: 385/31
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/122 Basic optical elements, e.g. light-guiding paths
• CPC Class Codes: G02B 6/125 Bends, branchings or intersections
• CPC Class Codes: G02B 6/2852 using tapping light guides arranged sidewardly, e.g. in a non-parallel relationship with respect to the bus light guides (light extraction or launching through cladding, with or without surface discontinuities, bent structures)
• CPC Class Codes: G02B 6/351 involving stationary waveguides with moving interposed optical elements G02B6/3538 takes precedence; interposed waveguides G02B6/3502
• CPC Class Codes: G09G 3/3473 based on light coupled out of a light guide, e.g. due to scattering, by contracting the light guide with external means

Abstract

The application of microstructures which improve the quality of light available to the viewer of an optical display system, or any display which works on the concept of moving one surface into direct contact or close proximity of a light guide to extract light through frustrated total internal reflection. Optical microstructures are introduced on one or both of the surfaces of the active layer to enhance its performance. Since the active layer has both an input and an output function, means for enhancing both are presented. The input function to the active layer occurs on the internal surface, so this is where the present invention adds a collector-coupler, a means for facilitating the migration of light from the waveguide into the active layer. The output function occurs on the external surface, where the present invention adds a collimator, a means for both increasing the probability that a light wave will be released from the active layer, and improving the apparent intensity by redirecting light waves so that more of them reach the viewer. Compound microlenses on the internal surface of the active layer can serve as both collector-couplers and collimators, substantially improving light extraction from the light guide and light distribution to the viewer. Depositing a reflective or colored material in the interstitial spaces between these compound microlenses improves the contrast ratio and mitigate pixel cross-talk. The opaque material can be conductive for use in actuating the display.

Claims

1. A pixel, comprising:

a light guide containing total internal reflected light waves; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves to exit the light guide and enter the first set of collector-coupler features, wherein a material is disposed interstitially between the collector-coupler features of said first set of collector-coupler features, and wherein said material is color absorbing or reflective.

2. The pixel as recited in claim 1, wherein said first set of collector-coupler features are angled or curved.

3. The pixel as recited in claim 1, wherein optical properties of each collector-coupler of said first set of collector-coupler features are selected such that light entering the collector-coupler from the light guide will contact a side boundary of the collector-coupler under conditions sufficient for total internal reflection within the collector-coupler before said light contacts a boundary between said collector-coupler and said active layer.

4. The pixel as recited in claim 1, wherein said material comprises an electrical conductor.

8. The pixel as recited in claim 1, wherein the first set of collector-coupler features comprises a plurality of compound microlenses.

9. The pixel as recited in claim 8, wherein a shape of the compound microlens is configured so that light coupled into a first end of the compound microlens will contact an internal side of the compound microlens under conditions sufficient for total internal reflection within the compound microlens before it exits from a second end of the compound microlens that is parallel to and opposite of the first end of the compound microlens.

10. The pixel as recited in claim 8, wherein the compound microlens comprises a pyramidal frustrum.

11. The pixel as recited in claim 8, wherein the compound microlens comprises a conical frustrum.

12. The pixel as recited in claim 8, wherein the compound microlens comprises a compound parabolic.

5. A display system, comprising:

a plurality of pixels on a display, wherein each of said plurality of pixels comprises;

a light guide; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves within the light guide to exit the light guide and enter the first set of collector-coupler features, wherein a material is disposed interstitially between the collector-coupler features of said first set of collector-coupler features, and wherein said material is opaque.

6. The display system as recited in claim 5, wherein said first set of collector-coupler features are angled or curved at their ends.

7. The display system as recited in claim 5, wherein said material comprises an electrical conductor.

13. The display system as recited in claim 5, wherein the first set of collector-coupler features comprises a plurality of compound microlenses.

14. The display system as recited in claim 13, wherein a shape of the compound microlens is configured so that light coupled into a first end of the compound microlens will contact an internal side of the compound microlens under conditions sufficient for total internal reflection within the compound microlens before it exits from a second end of the compound microlens that is parallel to and opposite of the first end of the compound microlens.

15. The display system as recited in claim 13, wherein the compound microlens comprises a pyramidal frustrum.

16. The display system as recited in claim 13, wherein the compound microlens comprises a conical frustrum.

17. The display system as recited in claim 13, wherein the compound microlens comprises a compound parabolic.

18. The display system as recited in claim 5, wherein the active layer is configured to physically move towards the light guide, when the pixel is activated to emit light, in a manner so that at least some of the first set of collector-coupler features contact the light guide.

19. The display system as recited in claim 18, wherein, when the pixel is inactivated to emit light, the active layer is positioned so that the first set of collector-coupler features are not in contact with the light guide.

20. The display system as recited in claim 5, wherein said material is color absorbing or reflective.

21. A display system, comprising:

a plurality of pixels on a display, wherein each of said plurality of pixels comprises;

a light guide; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves within the light guide to exit the light guide and enter the first set of collector-coupler features, wherein a material is disposed interstitially between the collector-coupler features of said first set of collector-coupler features, wherein said material comprises an electrical conductor.

22. A display system, comprising:

a plurality of pixels on a display, wherein each of said plurality of pixels comprises;

a light guide; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves within the light guide to exit the light guide and enter the first set of collector-coupler features, wherein optical properties of each collector-coupler of said first set of collector-coupler features are selected such that light entering the collector-coupler from the light guide will contact a side boundary of the collector-coupler under conditions sufficient for total internal reflection within the collector-coupler before said light contacts a boundary between said collector-coupler and said active layer, wherein a material is disposed interstitially between the collector-coupler features of said first set of collector-coupler features, and wherein said material is color absorbing or reflective.

23. A pixel, comprising:

a light guide containing total internal reflected light waves; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves to exit the light guide and enter the first set of collector-coupler features, wherein an opaque material is disposed interstitially between the collector-coupler features of said first set of collector-coupler features.

24. A pixel, comprising:

a light guide containing total internal reflected light waves; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves to exit the light guide and enter the first set of collector-coupler features, wherein a material comprising an electrical conductor is disposed interstitially between the collector-coupler features of said first set of collector-coupler features.

25. A display system, comprising:

a plurality of pixels on a display, wherein each of said plurality of pixels comprises;

a light guide; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves within the light guide to exit the light guide and enter the first set of collector-coupler features, wherein a material is disposed interstitially between the collector-coupler features of said first set of collector-coupler features, and wherein said material is color absorbing or reflective.

26. A pixel, comprising:

a light guide containing total internal reflected light waves; and

an active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein the active layer is configured to move said first set of collector-coupler features into close proximity to a surface of said light guide so as to cause light waves to exit the light guide and enter the first set of collector-coupler features, wherein a color absorbing material is disposed interstitially between the collector-coupler features.

27. A pixel, comprising:

a light guide containing total internal reflected light waves; and

a positionable active layer having a first set of collector-coupler features on an internal surface of said active layer, wherein when the pixel is activated to emit light, the active layer is positioned such that said first set of collector-coupler features are in close proximity to a surface of said light guide so as to cause said light waves to exit the light guide and enter the first set of collector-coupler features, wherein an opaque material is disposed interstitially between the collector-coupler features of said first set of collector-coupler features.

28. The pixel as recited in claim 27, wherein said opaque material is electrically conductive.

29. The pixel as recited in claim 27, wherein said opaque material is color absorbing or reflective.

30. The pixel as recited in claim 27, wherein when the pixel is inactivated to emit light, the active layer is positioned so as to form a sufficient space between said first set of collector-coupler features and the surface of said light guide such that said light waves do not enter the first set of collector-coupler features at the pixel location.