System architecture design for time-of-flight system having reduced differential pixel size, and time-of-flight systems so designed

• US 8,587,773 B2
• Filed: 12/13/2012
• Issued: 11/19/2013
• Est. Priority Date: 06/30/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Bamji, Cyrus, Mehta, Swati
• Primary Examiner(s): RATCLIFFE, LUKE D
• Application Number:
  US13/713,541
• Publication Number:
  US 20130114064A1
• Time in Patent Office: 341 Days
• Field of Search: 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22, 356/28, 356/28.5
• US Class Current: 356/5.01
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/491 Details of non-pulse systems
• CPC Class Codes: G01S 7/4914 of detector arrays, e.g. charge-transfer gates

Abstract

Embodiments of the present invention provide methods to produce a high performance, feature rich TOF system, phase-based or otherwise using small TOF pixels, single-ended or preferably differential, as well as TOF systems so designed. IC chip area required for pixels is reduced by intelligently off-loading or removing from within the pixel certain components and/or functionality. In some embodiments during a single TOF system capture period, analog values from each pixel are repeatedly sampled and converted to digital values, which are combined and manipulated on the sensor chip. Combining this plurality of values enables appropriately compact data from the sensor chip. Embodiments of the present invention implement a TOF system with high ambient light resilience, high dynamic range, low motion blur and dealiasing support, while advantageously reducing pixel area size relative to prior art TOF pixels.

Claims

1. A method for determining a distance to an object, comprising:

capturing light during a first operating regime reflected from the object using a photodetector, the photodetector is in electrical communication with an integration capacitor, the integration capacitor is associated with a first direction of integration during the first operation regime;

sampling a first set of intermediate values associated with the integration capacitor during the first operating regime;

capturing light during a second operating regime reflected from the object using the photodetector, the integration capacitor is associated with a second direction of integration different from the first direction of integration during the second operation regime;

sampling a second set of intermediate values associated with the integration capacitor during the second operating regime;

determining the distance to the object based on the first set of intermediate values and the second set of intermediate values, the integration capacitor is not reset during or between the first operating regime and the second operating regime; and

outputting the distance to the object.

2. The method of claim 1, wherein:

the first direction of integration is associated with a phase 0 integration and the second direction of integration is associated with a phase 180 integration.

3. The method of claim 1, further comprising:

emitting light associated with a first phase during the first operating regime; and

emitting light associated with a second phase different from the first phase during the second operating regime subsequent to the first operating regime.

4. The method of claim 3, wherein:

the determining the distance includes determining a first phase shift between the light emitted during the first operating regime and the light captured during the first operating regime.

5. The method of claim 4, wherein:

the determining the distance includes determining a second phase shift between the light emitted during the second operating regime and the light captured during the second operating regime.

6. The method of claim 3, wherein:

the light emitted during the first operating regime is emitted using a laser diode.

7. The method of claim 1, wherein:

the sampling a first set of intermediate values includes sampling a voltage associated with the integration capacitor.

8. The method of claim 1, wherein:

the photodetector is located within a pixel array.

9. The method of claim 8, wherein:

the sampling a first set of intermediate values includes reading out the first set of intermediate values to digital circuitry located outside the pixel array.

10. The method of claim 1, wherein:

the first direction of integration corresponds with a first direction of charge accumulation on the integration capacitor.

11. The method of claim 1, wherein:

the first direction of integration is associated with a phase 180 integration and the second direction of integration is associated with a phase 0 integration.

12. One or more processor readable storage devices containing processor readable code for programming one or more processors to perform a method for determining a distance to a moving object comprising the steps of:

capturing light during a first operating regime reflected from the moving object using a pixel array, the pixel array includes a first pixel detector in electrical communication with an integration capacitor, the integration capacitor is associated with a first direction of integration during the first operation regime;

sampling a first set of intermediate values associated with the integration capacitor during the first operating regime;

capturing light during a second operating regime subsequent to the first operating regime reflected from the moving object using the pixel array, the integration capacitor is associated with a second direction of integration different from the first direction of integration during the second operation regime;

sampling a second set of intermediate values associated with the integration capacitor during the second operating regime;

determining the distance to the moving object based on the first set of intermediate values and the second set of intermediate values, the pixel array is not reset during the first operating regime or the second operating regime, the pixel array is not reset between the first operating regime and the second operating regime; and

outputting the distance to the moving object.

13. The one or more processor readable storage devices of claim 12, wherein:

the first direction of integration is associated with a phase 0 integration and the second direction of integration is associated with a phase 180 integration.

14. The one or more processor readable storage devices of claim 12, wherein:

the sampling a first set of intermediate values includes sampling a voltage associated with the integration capacitor.

15. The one or more processor readable storage devices of claim 12, wherein:

the sampling a first set of intermediate values includes reading out the first set of intermediate values to digital circuitry located outside the pixel array.

16. A time-of-flight system for determining a distance to an object, comprising:

a pixel array, the pixel array captures light during a first operating regime reflected from the object, the pixel array includes a first pixel detector in electrical communication with an integration capacitor, the integration capacitor is associated with a first direction of integration during the first operation regime, the pixel array captures light during a second operating regime subsequent to the first operating regime reflected from the object, the integration capacitor is associated with a second direction of integration different from the first direction of integration during the second operation regime, the integration capacitor is not reset during or between the first operating regime and the second operating regime; and

one or more processors in communication with the pixel array, the one or more processors cause a sampling of a first set of intermediate values associated with the integration capacitor during the first operating regime, the one or more processors cause a sampling of a second set of intermediate values associated with the integration capacitor during the second operating regime, the one or more processors determine a distance to the object based on the first set of intermediate values and the second set of intermediate values.

17. The time-of-flight system of claim 16, wherein:

the first direction of integration is associated with a phase 0 integration and the second direction of integration is associated with a phase 180 integration.

18. The time-of-flight system of claim 17, wherein:

the sampling of the first set of intermediate values includes sensing a voltage associated with the integration capacitor.

19. The time-of-flight system of claim 17, wherein:

the sampling of the first set of intermediate values includes reading out the first set of intermediate values to digital circuitry located outside the pixel array.

20. The time-of-flight system of claim 19, wherein:

the first direction of integration corresponds with a first direction of charge accumulation on the integration capacitor.