COMPOSITE VARIABLE LIGHT ATTENUATOR

• US 20150323795A1
• Filed: 05/06/2014
• Published: 11/12/2015
• Est. Priority Date: 05/06/2014
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Ackerman, Nathan, Alton, Daniel J.
• Granted Patent: US 9,442,293 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G02B 1/005 made of photonic crystals or photonic band gap materials photonic band-gap structures or photonic lattices in integrated optics G02B6/1225; photonic band-gap structures or photonic lattices in optical fibres G02B6/02295
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02C 11/10 Electronic devices other than hearing aids
• CPC Class Codes: G02C 7/101 having an electro-optical light valve electro-optical elements per se G02F
• CPC Class Codes: G02C 7/104 having spectral characteristics for purposes other than sun-protection
• CPC Class Codes: G02F 1/0121 Operation of devices; Circuit arrangements, not otherwise provided for in this subclass
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence

Abstract

An optical stack includes a first variable element and a second variable element. The first variable element is configured to vary light transmission through the first variable element as a function of a first control signal. The second variable element is in series with the first variable element and is configured to vary light transmission through the second variable element as a function of a second control signal. A controller dynamically supplies the first control signal to the first variable element and supplies the second control signal to the second variable element.

Claims

1. An optical stack assembly, comprising:

a first variable element configured to vary light transmission through the first variable element as a function of a first control signal; and

a second variable element in series with the first variable element and configured to vary light transmission through the second variable element as a function of a second control signal; and

a controller to dynamically supply the first control signal to the first variable element and to supply the second control signal to the second variable element to achieve a greater range of light transmission than either the first variable element or the second variable element provide individually, while providing a switching speed between light transmission levels that is as fast as a switching speed of a faster of the first variable element and the second variable element.

2. The optical stack of claim 1, wherein the first control signal and the second control signal are electronically synchronized.

3. The optical stack of claim 1, wherein the first variable element has two or more discreet tunable light transmission intervals.

4. The optical stack of claim 3, wherein the second variable element has a continuously tunable light transmission gradient.

5. The optical stack of claim 4, wherein a range of light transmission of the first variable element is greater than a range of light transmission of the second variable element.

6. The optical stack of claim 3, wherein the first variable element comprises a photonic crystal material.

7. The optical stack of claim 4, wherein the second variable element comprises a liquid crystal material.

8. The optical stack of claim 1, further comprising:

one or more static elements in series with the first and second variable elements and configured to vary light transmission through the optical stack.

9. The optical stack of claim 1, further comprising:

one or more additional variable elements in series with the first and second variable elements.

10. The optical stack of claim 9, further comprising:

one or more substrates in series with the first and second variable elements and configured to not vary light transmission through the optical stack.

11. A head-mounted display system, comprising:

a see-through display configured to display an image of a virtual object while transmitting ambient light from a surrounding environment;

an optical stack, including;

a first variable element in series with the see-through display and configured to vary ambient light transmission through the see-through display as a function of a first control signal; and

a second variable element in series with the see-through display and the first variable element and configured to vary light transmission through the see-through display as a function of a second control signal; and

a controller to dynamically supply the first control signal to the first variable element and to supply the second control signal to the second variable element to achieve a greater range of light transmission through the see-through display than either the first variable element or the second variable element provides individually while providing a switching speed between light transmission levels that is as fast as a switching speed of a faster of the first variable element and the second variable element.

12. The head-mounted display system of claim 11, further comprising:

an ambient light sensor; and

wherein the first and second control signals synchronously vary light transmission through the first and second variable elements based on a level of ambient light detected by the ambient light sensor.

13. The head-mounted display system of claim 12, wherein the first and second control signals synchronously vary light transmission through the first and second variable elements based on a display application.

14. The head-mounted display system of claim 13, wherein the first and second control signals synchronously vary light transmission through the first and second variable elements based on a minimum power consumption required to achieve a desired light transmission level.

15. The head-mounted display system of claim 12, wherein the first variable element has two or more discreet tunable light transmission intervals, and wherein the second variable element has a continuously tunable light transmission gradient.

16. The head-mounted display system of claim 15, wherein the first variable element comprises a photonic crystal material, and the second variable element comprises a liquid crystal material.

17. A head-mounted display system, comprising:

a see-through display configured to display an image of a virtual object while transmitting ambient light from a surrounding environment;

an ambient light sensor;

an optical stack, including;

a clear plastic substrate;

a passive infra-red light blocking film in series with the see-through display;

a passive ultra-violet light blocking film in series with the see-through display;

a photonic crystal element configured to vary ambient light transmission through the see-through display at discrete light transmission intervals as a function of a first control signal based on an amount of ambient light detected by the ambient light sensor; and

a liquid crystal element configured to vary ambient light transmission through the see-through display over a continuous light transmission gradient as a function of a second control signal based on the amount of ambient light detected by the ambient light sensor; and

a controller to dynamically supply the first control signal to the photonic crystal element and to supply the second control signal to the liquid crystal element.

18. The head-mounted display system of claim 17, wherein the photonic crystal element and the liquid crystal element cooperatively realize maximum light transmission when a control signal with a zero value is supplied.

19. The head-mounted display system of claim 18, wherein the first control signal consumes more power than the second control signal when the first and second control signals each have non-zero values.

20. The head-mounted display system of claim 19, wherein the controller is configured to:

dynamically supply a first control signal with a zero value if a commanded light transmission can be realized when the photonic crystal element has maximum light transmission.