Optical microstructures for light extraction and control

• US 8,218,920 B2
• Filed: 12/30/2008
• Issued: 07/10/2012
• Est. Priority Date: 01/24/2006
• Status: Expired due to Fees

• Current Assignee: Rambus Delaware
• Original Assignee: Rambus Inc.
• Inventors: King, Carey, Gobeli, Garth, Van Ostrand, Daniel K.
• Primary Examiner(s): KIM, ELLEN E
• Application Number:
  US12/346,377
• Publication Number:
  US 20090142020A1
• Time in Patent Office: 1,288 Days
• Field of Search: 385/31, 385/39, 385/16, 359/291, 361/704, 361/707, 361/709, 361/710
• 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 optical microstructures 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. Certain ones of the microstructures can act to assist in overcoming stiction between the surface and the light guide.

Claims

1. A pixel comprising:

a light guide configured for containing total internal reflected light waves;

a positionable active layer configured to physically move between an on state position and an off state position, the positionable active layer located in proximity to the light guide;

a first set of collector-coupler features on an internal surface of the positionable active layer; and

a second set of collector-coupler features on the internal surface of the positionable active layer interspersed with the first set of collector-coupler features, wherein each of the second set of collector-coupler features is longer than each of the first set of collector-coupler features;

wherein each of the collector-coupler features of the first set are discrete from each of the collector-coupler features of the second set.

2. The pixel as recited in claim 1, wherein during the on state position, when the pixel is activated to emit the light waves, the positionable active layer is positioned such that the first set of collector-coupler features are in close proximity to a surface of the light guide so as to cause the light waves to exit the light guide and enter the positionable active layer via the first set of collector-coupler features, and wherein the second set of collector-coupler features are elastically compressed against the surface of the light guide in such a manner as to build potential energy within the second set of collector-coupler features.

3. The pixel as recited in claim 2, wherein upon repositioning the positionable active layer to the off state position after completion of the on state position, when the pixel is inactivated to thereby not emit the light waves, the second set of collector-coupler features decompress and release the potential energy in a form of a separation force that assists in moving the first set of collector-coupler features away from the surface of the light guide to overcome stiction between the surface of the light guide and the first set of collector-coupler features.

4. The pixel as recited in claim 2, further comprising:

a layer of compliant material, positioned adjacent to the second set of collector-coupler features, wherein compression of the second set of collector-coupler features causes elastic compression of the layer of compliant material in such a manner as to build potential energy within the layer of compliant material.

5. The pixel as recited in claim 4, wherein upon repositioning the positionable active layer to the off state position after completion of the on state position, the layer of compliant material is configured to decompress and release the potential energy in a form of a restorative force that assists in moving the first set of collector-coupler features away from the surface of the light guide to overcome stiction between the surface of the light guide and the first set of collector-coupler features.

6. The pixel as recited in claim 2, wherein optical properties of each collector-coupler feature of the first set of collector-coupler features are configured such that the light waves entering the collector-coupler feature from the light guide will contact a side boundary of the collector-coupler feature under conditions sufficient for total internal reflection within the collector-coupler feature before the light waves contact an interface between the collector-coupler feature and the internal surface of the positionable active layer.

7. The pixel as recited in claim 2, further comprising:

a plurality of collimator features on an external surface of the positionable active layer configured to increase a probability of the light waves exiting the positionable active layer for emission from the pixel, wherein the plurality of collimator features are configured to interact with the light waves that approach a vicinity of an interface between the external surface of the positionable active layer and the plurality of collimator features causing the light waves to enter and traverse the plurality of collimator features for subsequent emission from the pixel.

8. The pixel as recited in claim 7, wherein optical properties of the plurality of collimator features are configured to direct the light waves that traverse the plurality of collimator features to exit external surfaces of the plurality of collimator features in a direction more nearly perpendicular to the external surface of the positionable active layer.

9. The pixel as recited in claim 1, wherein a distal end of each of the first set of collector-coupler features is angled.

10. The pixel as recited in claim 9, wherein during the on state position, when the pixel is activated to emit the light waves, the positionable active layer is positioned such that the distal ends of the first set of collector-coupler features are compressed onto a surface of the light guide so as to cause the light waves to exit the light guide and enter the positionable active layer via the first set of collector-coupler features, and wherein the distal ends are elastically deformed in such a manner as to build potential energy within the first set of collector-coupler features.

11. The pixel as recited in claim 10, wherein upon repositioning the positionable active layer to the off state position after completion of the on state position, when the pixel is inactivated to thereby not emit the light waves, the first set of collector-coupler features decompress and release the potential energy in a form of a separation force that assists in moving the first set of collector-coupler features away from the surface of the light guide to overcome stiction between the surface of the light guide and the first set of collector-coupler features.

12. The pixel as recited in claim 1, wherein an opaque material is disposed interstitially between the collector-coupler features of the first set of collector-coupler features.

13. The pixel as recited in claim 12, wherein the opaque material is electrically conductive.

14. The pixel as recited in claim 12, wherein the opaque material is color absorbing.

15. The pixel as recited in claim 12, wherein the opaque material is reflective.

16. A display system comprising:

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

a light guide configured for containing total internal reflected light waves;

a positionable active layer configured to physically move between an on state position and an off state position, the positionable active layer located in proximity to the light guide;

a first set of discrete collector-coupler features on an internal surface of the positionable active layer; and

a second set of discrete collector-coupler features on the internal surface of the positionable active layer interspersed with the first set of discrete collector-coupler features, wherein each of the second set of discrete collector-coupler features is longer than each of the first set of discrete collector-coupler features.

17. The display system as recited in claim 16, wherein an opaque material is disposed interstitially between the discrete collector-coupler features of the first set of discrete collector-coupler features.

18. A display system comprising:

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

a light guide configured for containing total internal reflected light waves;

a positionable active layer configured to physically move between an on state position and an off state position, the positionable active layer located in proximity to the light guide;

a first set of collector-coupler features on an internal surface of the positionable active layer; and

a second set of collector-coupler features on the internal surface of the positionable active layer interspersed with the first set of collector-coupler features, wherein each of the second set of collector-coupler features is longer than each of the first set of collector-coupler features, wherein during the on state position, when the pixel is activated to emit the light waves, the positionable active layer is positioned such that the first set of collector-coupler features are in close proximity to a surface of the light guide so as to cause the light waves to exit the light guide and enter the positionable active layer via the first set of collector-coupler features, and the second set of collector-coupler features are elastically compressed against the surface of the light guide in such a manner as to build potential energy within the second set of collector-coupler features.

19. The display system as recited in claim 18, wherein optical properties of each collector-coupler feature of the first set of collector-coupler features are configured such that the light waves entering the collector-coupler feature from the light guide will contact a side boundary of the collector-coupler feature under conditions sufficient for total internal reflection within the collector-coupler feature before the light waves contact an interface between the collector-coupler feature and the internal surface of the positionable active layer.

20. The display system as recited in claim 18, wherein upon repositioning the positionable active layer to the off state position after completion of the on state position, when the pixel is inactivated to thereby not emit the light waves, the second set of collector-coupler features decompress and release the potential energy in a form of a separation force that assists in moving the first set of collector-coupler features away from the surface of the light guide to overcome stiction between the surface of the light guide and the first set of collector-coupler features.

21. The display system as recited in claim 18, further comprising:

a layer of compliant material, positioned adjacent to the second set of collector-coupler features, wherein compression of the second set of collector-coupler features causes elastic compression of the layer of compliant material in such a manner as to build potential energy within the layer of compliant material.

22. The display system as recited in claim 21, wherein upon repositioning the positionable active layer to the off state position after completion of the on state position, the layer of compliant material is configured to decompress and release the potential energy in a form of a restorative force that assists in moving the first set of collector-coupler features away from the surface of the light guide to overcome stiction between the surface of the light guide and the first set of collector-coupler features.

23. The display system as recited in claim 18, further comprising:

a plurality of collimator features on an external surface of the positionable active layer configured to increase a probability of the light waves exiting the positionable active layer for emission from the pixel, wherein the plurality of collimator features are configured to interact with the light waves that approach a vicinity of an interface between the external surface of the positionable active layer and the plurality of collimator features causing the light waves to enter and traverse the plurality of collimator features for subsequent emission from the pixel.

24. The display system as recited in claim 23, wherein optical properties of the plurality of collimator features are configured to direct the light waves that traverse the plurality of collimator features to exit external surfaces of the plurality of collimator features in a direction more nearly perpendicular to the external surface of the positionable active layer.

25. The display system as recited in claim 18, wherein an opaque material is disposed interstitially between the collector-coupler features of the first set of collector-coupler features.