ADJUSTABLY TRANSMISSIVE MEMS-BASED DEVICES

• US 20090103166A1
• Filed: 10/21/2008
• Published: 04/23/2009
• Est. Priority Date: 10/23/2007
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Khazeni, Kasra, Gruhlke, Russell W., Xu, Gang, Mignard, Marc, Kothari, Manish
• Granted Patent: US 8,054,527 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• 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 5/281 designed for the infrared light

Abstract

Modulator devices are selectably adjustable between at least two states, wherein the transmission and/or reflection of particular wavelengths of light are modified. Certain modulator devices are substantially uniformly adjustable over a wide range of wavelengths, including visible and infrared wavelengths. Other modulator devices are adjustable over visible wavelengths without significantly affecting infrared wavelengths. In addition, the modulator devices may be used in conjunction with fixed thin film reflective structures.

Claims

1. A MEMS device, comprising:

a first film stack disposed upon a substrate; and

a second film stack spaced apart from the first film stack by a gap, wherein the second film stack is movable between a first position and a second position;

wherein the MEMS device transmits substantially more visible light in said first position than in said second position, and wherein the MEMS device transmits substantially the same amount of infrared light when the MEMS device is in the first position as in the second position.

2. The MEMS device of claim 1, wherein the MEMS device transmits at least about 50% more of the incident visible light when in said first position than in said second position.

3. The MEMS device of claim 1, wherein the difference between the transmitted infrared light in the first position and the transmitted infrared light in the second position is no more than 10% of the incident infrared light.

4. The MEMS device of claim 1, wherein the infrared light comprises infrared light having a wavelength of less than 1.5 microns.

5. The MEMS device of claim 1, wherein the first thin film stack comprises a first conductive layer and a first optical layer, and wherein the second thin film stack comprises a second conductive layer and a second optical layer.

6. The MEMS device of claim 5, wherein the first and second optical layer comprises a material having an index of refraction greater than about 1.8.

7. The MEMS device of claim 6, wherein the first and second optical layer comprises a material having an index of refraction greater than about 1.9.

8. The MEMS device of claim 5, wherein the first and second optical layer comprises one or more of:

titanium dioxide, lead oxide, zinc oxide, and zirconium dioxide.

9. The MEMS device of claim 5, wherein the first and second conductive layers comprise contiguous layers.

10. The MEMS device of claim 1, additionally comprising a fixed thin film stack configured to reflect a substantial portion of incident light.

11. The MEMS device of claim 10, wherein the fixed thin film stack is configured to reflect a substantial portion of incident infrared light.

12. The MEMS device of claim 1, additionally comprising support structures located between said first thin film stack and said second thin film stack.

13. The MEMS device of claim 12, wherein said support structures comprise glass spheres.

14. The MEMS device of claim 1, wherein the MEMS device comprises at least one area wherein a portion of the second film stack is independently movable towards the first film stack.

15. A MEMS device comprising:

a first film stack disposed upon a substrate; and

a second film stack spaced apart from the first film stack by an air gap, wherein the second film stack is movable between a first position and a second position;

wherein the MEMS device transmits substantially more visible light and infrared light when in said first position than is transmitted in said second position.

16. The MEMS device of claim 15, wherein the first and second film stacks comprise dielectric mirrors.

17. The MEMS device of claim 15, wherein the MEMS device transmits greater than about 80% of incident infrared light when in said first position and transmits less than about 55% of incident infrared light when in said second position.

18. The MEMS device of claim 15, wherein the MEMS device functions as a partially reflective broad band mirror which reflects roughly 20% of incident visible and infrared light when in said first position and reflects roughly 50% of incident visible and infrared light when in said second position.

19. The MEMS device of claim 15, additionally comprising a plurality of intermediate layers disposed between the first film stack and the second film stack.

20. The MEMS device of claim 19, wherein:

the first film stack comprises a layer of ITO;

the second film stack comprises a layer of ITO overlying a layer of titanium dioxide; and

the plurality of intermediate layers comprises a plurality of titanium dioxide layers.

21. A glass pane, comprising:

a first glass layer;

a second glass layer sealed to the first glass layer to define a cavity therebetween;

a MEMS device disposed on a surface of the first glass layer facing the second glass layer, the MEMS device comprising a layer movable between a first position wherein the amount of infrared radiation transmitted through said MEMS device is dependent upon the position of the movable layer.

22. The glass pane of claim 21, wherein substantially all of the infrared radiation incident upon the MEMS device having a wavelength of less than 1.5 microns is either reflected or transmitted.

23. The glass pane of claim 21, wherein the MEMS device is substantially transmissive to infrared radiation in said first position.

24. The glass pane of claim 23, wherein substantially more incident infrared light is reflected by the MEMS device when said MEMS device is in the second position.

25. The glass pane of claim 21, additionally comprising a second device disposed on or adjacent a surface of one of the glass layers, wherein said device is switchable between a first state which is substantially transmissive to incident light, and a second state in which the absorption of incident light is increased.

26. The glass pane of claim 25, wherein the second device comprises a suspended particle device.

27. The glass pane of claim 21, wherein the MEMS device comprises:

a conductive layer disposed upon the substrate; and

a plurality of intermediate layers disposed between the first conductive layer and the movable layer.

28. The glass pane of claim 27, additionally comprising a second MEMS device disposed on a surface of the second glass layer facing the first glass layer, the second MEMS device comprising:

a second conductive layer disposed upon the substrate;

a second movable layer movable between a first position wherein the amount of infrared radiation transmitted through said MEMS device is dependent upon the position of the movable layer; and

a plurality of intermediate layers disposed between the second movable layer and the second conductive layer.

29. The glass pane of claim 28, wherein the glass pane is switchable between a first state in which roughly 50% of the incident visible and infrared light is reflected, and a second state in which substantially all of the incident visible and infrared light is reflected.

30. A MEMS device, comprising:

a first composite layer disposed upon a substrate;

said first composite layer comprising;

a first conductive layer; and

a first optical layer;

a second composite layer separated from said first composite layer via an air gap, wherein the second composite layer is movable toward said first composite layer, said second composite layer comprising;

a second conductive layer; and

a second optical layer;

wherein displacement of said second composite layer towards said first composite layer alters the transmission of infrared light through the MEMS device.

31. The MEMS device of claim 30, wherein movement of said second composite layer towards said first composite layer also alters the transmission of visible light through the MEMS device.

32. The MEMS device of claim 30, wherein the movable layer is movable between a first position and a second position, and wherein the MEMS device transmits greater than about 80% of incident infrared light when in said first position and transmits less than about 55% of incident infrared light when in said second position.

33. The MEMS device of claim 30, wherein the first and second optical layers comprise dielectric mirrors.

34. A MEMS system, comprising:

a transparent substrate;

a MEMS device disposed on or adjacent the transparent substrate, said MEMS device comprising a layer movable between a first position wherein said device is switchable between a first state which is substantially transmissive to incident light, and a second state in which the reflection of incident light is increased;

a sensor configured to sense incident light in a location proximate the substrate; and

control circuitry in electrical communication with the sensor, wherein said control circuitry controls the state of the MEMS device based at least in part upon the state of the sensor.