Ambient light sensor configured to determine the direction of a beam of ambient light incident thereon

• US 8,681,137 B2
• Filed: 05/17/2011
• Issued: 03/25/2014
• Est. Priority Date: 05/17/2011
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Wong, Chee Heng, Yao, Yu Feng, Ong, Sze Ping
• Primary Examiner(s): Haley, Joseph
• Assistant Examiner(s): ILUYOMADE, IFEDAYO B
• Application Number:
  US13/108,985
• Publication Number:
  US 20120293472A1
• Time in Patent Office: 1,043 Days
• Field of Search: None
• US Class Current: 345/207
• CPC Class Codes: G01J 1/0219 Electrical interface; User interface
• CPC Class Codes: G01J 1/0228 Control of working procedures; Failure detection; Spectral bandwidth calculation
• CPC Class Codes: G01J 1/0437 using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 1/06 Restricting the angle of incident light
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 1/4257 applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam monitoring arrangements for lasers in general H01S3/0014
• 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

Abstract

Various embodiments of an ambient light sensor configured to determine the direction of a beam of light incident thereon are disclosed. In one embodiment, an ambient light sensor is provided that comprises a plurality of light detectors arranged in a spatial array upon a light sensing surface. Each of the light detectors in the array is configured to generate an analog output voltage in response to the beam of ambient light falling thereon. The amount of light incident on the individual light detectors in the spatial array varies according to the position of each such sensor with respect to direction of the beam of ambient light. An analog-to-digital converter (ADC) is operably coupled to the plurality of light detectors and is configured to receive the analog output signals generated thereby as inputs thereto, and to provide digital output values representative of the analog signals. Control logic circuitry is operably coupled to the ADC and configured to receive the digital output values therefrom, and is further configured to process such digital output values to determine the direction of the beam of light incident upon the spatial array.

Claims

1. An ambient light sensor, comprising:

a substantially optically opaque light sensor cover having an aperture, the aperture being configured to permit a portion of an ambient light beam to pass therethrough as a transmitted light beam;

a plurality of light detectors arranged in a array adjacent to the aperture, each of the light detectors having a position in the array and being configured to generate analog output signals when at least a portion of the transmitted light beam falls thereon;

at least one analog-to-digital converter (ADC) operably coupled to the plurality of light detectors and configured to receive as inputs thereto the analog output signals, the ADC further being configured to provide as outputs therefrom digital values representative of the analog output signals, and

a control logic circuitry operably coupled to the ADC and configured to receive the digital values as inputs thereto;

wherein the transmitted light beam transmitted through the aperture has a direction with respect to the plurality of light detectors, each of the plurality of light detectors is configured to receive a varying amount of light according to the position of each of the plurality of light detectors with respect to the transmitted light beam transmitted through the aperture; and

wherein the control logic circuitry is configured to process the digital values to determine the direction of the transmitted light beam.

2. The ambient light sensor of claim 1, wherein at least some of the light detectors are photodiodes.

3. The ambient light sensor of claim 1, wherein the plurality of light detectors in the array comprises at least three light detectors.

4. The ambient light sensor of claim 1, wherein the plurality of light detectors in the array comprises at least seven light detectors.

5. The ambient light sensor of claim 1, wherein the plurality of light detectors in the array comprises at least nine light detectors.

6. The ambient light sensor of claim 1, wherein the control logic circuitry or a host processor operably coupled thereto is configured to provide an output representative of the direction to a host processor.

7. The ambient light sensor of claim 1, wherein the control logic circuitry or a host processor operably coupled thereto is configured to generate a feedback control signal representative of the direction.

8. The ambient light sensor of claim 7, wherein the control logic circuitry or a host processor operably coupled thereto is operably coupled to a device to which the feedback control signal is provided.

9. The ambient light sensor of claim 1, wherein the control logic circuitry or a host processor operably coupled thereto is further configured to detect, on the basis of the digital values, motion proximate the ambient light sensor.

10. The ambient light sensor of claim 1, wherein the control logic circuitry or a host processor operably coupled thereto is further configured to detect, on the basis of the digital values, an object proximate the ambient light sensor.

11. The ambient light sensor of claim 1, further comprising switch control circuitry disposed between the plurality of light detectors and the ADC, the switch control circuitry being configured to read one analog output signal at a time.

12. The ambient light sensor of claim 1, further comprising a front end interface circuit disposed between the plurality of light detectors and the ADC.

13. The ambient light sensor of claim 1, wherein outputs from the control logic circuit or a host processor operably coupled thereto are employed to control operation of a device.

14. The ambient light sensor of claim 13, wherein the operation controlled in accordance with the outputs is turning the device on or off.

15. The ambient light sensor of claim 13, wherein the operation controlled in accordance with the outputs is changing a power consumption level of the device.

16. The ambient light sensor of claim 13, wherein the operation controlled in accordance with the outputs is conserving battery power of the device.

17. The ambient light sensor of claim 13, wherein the device is an LCD and the operation controlled in accordance with the outputs is adjusting a backlight intensity of the LCD.

18. The ambient light sensor of claim 13, wherein the device is a display and the operation controlled in accordance with the outputs is adjusting the brightness of the display.

29. The ambient light sensor of claim 1, wherein the control logic circuitry is configured to determine the direction of the transmitted light beam with a computational technique, the computational technique comprises Toeplitz matrices, invariance techniques and digital filtering techniques.

30. The ambient light sensor of claim 1, wherein the control logic circuitry is configured to determine the direction of the transmitted light beam with a computational technique, the computational technique comprises matrix analyses, contour mapping analyses, least-square fitting techniques and array mapping techniques.

31. The ambient light sensor of claim 1, further comprising an interface to host.

19. An ambient light sensor, comprising:

a substantially optically transmissive light sensor cover comprising an external surface and a substantially optically opaque light blocking element disposed at least one of near, in and on the external surface, the cover being configured to permit portions of an ambient light beam incident thereon to pass therethrough, the light blocking element being configured to cast a corresponding shadow therebeneath when the ambient light beam is incident thereon;

a plurality of light detectors arranged in a spatial array adjacent to the light blocking element, each of the light detectors having a position in the array and being configured to generate analog output signals when at least a portion of the ambient light beam falls thereon;

at least one analog-to-digital converter (ADC) operably coupled to the plurality of light detectors and configured to receive as inputs thereto the analog output signals, the ADC further being configured to provide as outputs therefrom digital values representative of the analog output signals, and

a control logic circuitry operably coupled to the ADC and configured to receive the digital values as inputs thereto;

wherein the ambient light beam and the corresponding cast by the light blocking element substantially share a direction with respect to the plurality of light detectors and the light sensing surface, each of the plurality of light detectors is configured to receive a varying amount of light according to the position of the light detector with respect to the shadow cast by the light blocking element, and the control logic circuitry or a host processor is configured to process the digital values to determine the direction.

20. The ambient light sensor of claim 19, wherein at least some of the light detectors are photodiodes.

21. The ambient light sensor of claim 19, further comprising a front end interface circuit disposed between the plurality of light detectors and the ADC.

22. The ambient light sensor of claim 19, wherein outputs from the control logic circuit or a host processor operably coupled thereto are employed to control operation of a device.

23. The ambient light sensor of claim 22, wherein the operation controlled in accordance with the outputs is turning the device on or off.

24. The ambient light sensor of claim 22, wherein the operation controlled in accordance with the outputs is changing a power consumption level of the device.

25. The ambient light sensor of claim 22, wherein the operation controlled in accordance with the outputs is conserving battery power of the device.

26. The ambient light sensor of claim 22, wherein the device is an LCD and the operation controlled in accordance with the outputs is adjusting a backlight intensity of the LCD.

27. The ambient light sensor of claim 22, wherein the device is a display and the operation controlled in accordance with the outputs is adjusting the brightness of the display.

28. The ambient light sensor of claim 21, wherein the front end interface circuit comprises an analog filtering circuitry.

32. An ambient light sensor, comprising:

an opaque cover;

a plurality of light detectors in a two dimensional array; and

an aperture of the opaque cover, the aperture is configured to permit a portion of an ambient light to pass therethrough as a transmitted light beam that falls on a portion of the plurality of light detectors in the two dimensional array;

wherein the cover and the aperture disposed thereon are configured to generate differences in an amount of light incident on each of the plurality of light detectors, and each of the plurality of light detectors is configured to generate analog output signals that differ from one another in accordance with a direction of the transmitted light beam transmitted through the aperture.

33. The ambient light sensor of claim 32, further comprising a substantially optically transmissive overmolding disposed over the plurality of light detectors.

34. The ambient light sensor of claim 32, wherein the cover is made from a thermosetting material.

35. The ambient light sensor of claim 32, wherein at least one of the plurality of light detectors is a photodiode with N-well/P-sub structure.