Method and system for sensing light using interferometric elements

• US 7,460,246 B2
• Filed: 02/24/2005
• Issued: 12/02/2008
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Kothari, Manish
• Primary Examiner(s): Lee; Hwa (Andrew) S
• Application Number:
  US11/066,724
• Publication Number:
  US 20060066876A1
• Time in Patent Office: 1,377 Days
• Field of Search: 250/339.04, 250/339.05, 250/339.01, 356/454, 356/480, 356/519, 356/506
• US Class Current: 356/519
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• 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: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Certain embodiments of the invention provide a light sensor comprising at least one interferometric element that absorbs light in at least one wavelength. The interferometric element comprises a first surface and a second surface substantially parallel to the first surface. The second surface is spaced a gap distance from the first surface in a direction substantially perpendicular to the first surface. The light wavelength absorbed is dependent on the gap distance. The interferometric element further comprises a temperature sensor. The temperature sensor is responsive to changes in temperature of at least a portion of the interferometric element due to absorption of light by the interferometric element.

Claims

1. A light sensor having at least one interferometric element, the interferometric element comprising:

a first surface being partially transmissive and partially reflective to at least one wavelength of light;

a second surface substantially parallel to the first surface and spaced a first distance from the first surface in a direction substantially perpendicular to the first surface for reflecting at least a portion of the at least one wavelength of light; and

a temperature sensor responsive to changes of temperature of at least a portion of the interferometric element caused at least in part by absorption of the at least one wavelength of light, wherein the temperature sensor is positioned between the first and second surfaces.

2. The light sensor of claim 1, wherein the temperature sensor comprises a binary device.

3. The light sensor of claim 2, wherein the binary device is in a first state when the temperature is below a predetermined level and is in a second state when the temperature is above a predetermined level.

4. The light sensor of claim 1, wherein the temperature sensor comprises an analog device.

5. The light sensor of claim 4, wherein the analog device comprises a bi-metallic thermocouple.

6. The light sensor of claim 4, wherein the analog device generates a voltage difference as a function of the temperature.

7. The light sensor of claim 1, further comprising a second interferometric modulator comprising:

a third surface being partially transmissive and partially reflective to at least one second wavelength of light;

a fourth surface substantially parallel to the third surface and spaced a second distance from the third surface in a direction substantially perpendicular to the third surface for reflecting at least a portion of the at least one wavelength of light; and

a second temperature sensor responsive to changes of temperature of at least a portion of the second interferometric element from absorption of the at least one second wavelength of light.

8. The light sensor of claim 7, wherein the second temperature sensor comprises a second binary device.

9. The light sensor of claim 8, wherein the second binary device is in a first state when the temperature is below a predetermined level and is in a second state when the temperature is above a predetermined level.

10. The light sensor of claim 7, wherein the second temperature sensor comprises a second analog device.

11. The light sensor of claim 10, wherein the second analog device comprises a bi-metallic thermocouple.

12. The light sensor of claim 10, wherein the second analog device generates a voltage difference as a function of the temperature.

13. The light sensor of claim 1, further comprising a second interferometric modulator comprising,

a third surface being partially transmissive and partially reflective to the at least one wavelength of light;

a fourth surface substantially parallel to the third surface and spaced a first distance from the third surface in a direction substantially perpendicular to the third surface for reflecting at least a portion of the at least one wavelength of light; and

a second temperature sensor responsive to changes of temperature of at least a portion of the second interferometric element from absorption of the at least one wavelength of light, wherein an activation temperature of the second temperature sensor is different than an activation temperature of the temperature sensor.

14. The light sensor of claim 1 further comprising a substrate.

15. The sensor of claim 1, wherein the temperature sensor is responsive to changes of temperature of at least a portion of the first surface.

16. The sensor of claim 7, wherein the second temperature sensor is responsive to changes of temperature of at least a portion of the third surface.

17. The sensor of claim 13, wherein the second temperature sensor is responsive to changes of temperature of at least a portion of the third surface.