System and method for a MEMS device

• US 7,800,809 B2
• Filed: 08/20/2007
• Issued: 09/21/2010
• Est. Priority Date: 05/05/1994
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Miles, Mark W.
• Primary Examiner(s): Thompson; Timothy J
• Application Number:
  US11/841,833
• Publication Number:
  US 20080088908A1
• Time in Patent Office: 1,128 Days
• Field of Search: 359/223, 359/224, 359/290, 359/291, 345/108
• 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: H01Q 9/26 with folded element or elements, the folded parts being spaced apart a small fraction of operating wavelength resonant loop antennas H01Q7/00

Abstract

Light in the visible spectrum is modulated using an array of modulation elements, and control circuitry connected to the array for controlling each of the modulation elements independently, each of the modulation elements having a surface which is caused to exhibit a predetermined impedance characteristic to particular frequencies of light. The amplitude of light delivered by each of the modulation elements is controlled independently by pulse code modulation. Each modulation element has a deformable portion held under tensile stress, and the control circuitry controls the deformation of the deformable portion. Each deformable element has a deformation mechanism and an optical portion, the deformation mechanism and the optical portion independently imparting to the element respectively a controlled deformation characteristic and a controlled modulation characteristic. The deformable modulation element may be a non-metal. The elements are made by forming a sandwich of two layers and a sacrificial layer between them, the sacrificial layer having a thickness related to the final cavity dimension, and using water or an oxygen based plasma to remove the sacrificial layer.

Claims

1. A device for modulating light comprising:

a first layer and a second layer that define a cavity therebetween, the first layer being movable relative to the second layer along substantially an entire direction of motion of the first layer within the cavity; and

a control circuit configured to apply a continuously variable voltage to cause a continuous movement of the first layer,

wherein the relative movement between the first and second layers provides a continuous frequency selection capability within an operational range.

2. The device of claim 1, wherein the continuous movement of at least one of the first and second layer corresponds to a variation of a dimension of the cavity.

3. The device of claim 1, wherein the relative movement of the first and second layers is controllable by controlling the applied continuously variable voltage.

4. The device of claim 1, wherein the operational range comprises a range of voltages.

5. The device of claim 1, wherein the operational range comprises a range of frequencies.

6. The device of claim 1, wherein the dimension of the cavity comprises a spatial distance between the first and second layer.

7. The device of claim 1, wherein at least one of the first and second layers comprises a reflective surface.

8. The device of claim 7, wherein one of the first and second layers comprises a broadband reflective surface and the other one of the first and second layers comprises a narrow band reflective surface.

9. The device of claim 7, wherein both of the first and second layers comprise narrow band reflective surfaces.

10. The device of claim 1, wherein the movable one of the layers is under tensile stress.

11. A method for driving a device for modulating light, the method comprising:

continuously varying a voltage between a first layer and a second layer of the device; and

causing a continuous variation in a dimension of a cavity formed by the first and second layer, the variation in the dimension in response to the continuously varying voltage,

wherein the relative movement between the first and second layers provides a continuous frequency selection capability within an operational range.

12. The method of claim 11, wherein the dimension of the cavity comprises a spatial distance between the first layer and the second layer.

13. The method of claim 11, wherein both the first layer and the second layer comprise reflective surfaces.

14. The method of claim 11, wherein the first layer is movable relative to the second layer and the first layer is under tensile stress.

15. The method of claim 11, wherein the variation in the dimension of the cavity is controllable by controlling the continuously variable voltage.

16. The method of claim 11, wherein the relative variation in the dimension of the cavity provides a continuous frequency selection capability within an operational range.

17. The method of claim 16, wherein the operational range comprises a range of voltages.

18. The method of claim 16, wherein the operational range comprises a range of frequencies.

19. A device for modulating light comprising:

a first layer and a second layer that define a cavity therebetween, the first layer being movable relative to the second layer and the first layer having sufficient stiffness to maintain a substantially parallel orientation between the first and second layers; and

a control circuit configured to apply a continuously variable voltage to cause a continuous movement of at least one of the first and second layer,

wherein the continuous movement provides a continuous frequency selection capability within an operational range.