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

• US 8,363,212 B2
• Filed: 04/02/2012
• Issued: 01/29/2013
• 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:
  US13/437,392
• Publication Number:
  US 20120188530A1
• Time in Patent Office: 302 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 depth information associated with a target object, comprising:

emitting light during a first operating regime towards the target object, the light emitted during the first operating regime comprises light of a first phase;

detecting light during the first operating regime reflected from the target object using an array of one or more pixels, the light detected during the first operating regime comprises light of a second phase different from the first phase, the array of one or more pixels is associated with a direction of integration, the direction of integration during the first operating regime comprises a first direction of integration;

sampling a first set of intermediate values associated with the array of one or more pixels during the first operating regime;

switching the direction of integration to a second direction of integration different from the first direction of integration;

emitting light during a second operating regime towards the target object, the light emitted during the second operating regime comprises light of a third phase different from the first phase, the second operating regime is performed subsequent to the first operating regime;

detecting light during the second operating regime reflected from the target object using the array of one or more pixels, the light detected during the second operating regime comprises light of a fourth phase different from the third phase;

sampling a second set of intermediate values associated with the array of one or more pixels during the second operating regime;

determining a distance to the target object based on the first set of intermediate values and the second set of intermediate values, the array of one or more pixels is not reset during or between the first operating regime and the second operating regime; and

outputting the distance to the target 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, wherein:

the light emitted during the first operating regime is associated with a first frequency; and

the light emitted during the second operating regime is associated with a second frequency different from the first frequency.

4. The method of claim 1, wherein:

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

5. The method of claim 4, wherein:

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

6. The method of claim 1, wherein:

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

7. The method of claim 1, wherein:

the array of one or more pixels comprises a two-dimensional array of pixel detectors.

8. The method of claim 1, wherein:

each pixel of the array of one or more pixels includes an integration capacitor.

9. The method of claim 1, wherein:

the sampling a first set of intermediate values includes reading out the first set of intermediate values to digital circuitry outside an area of the array of one or more pixels.

10. The method of claim 1, wherein:

the switching the direction of integration is performed prior to the second operating regime.

11. The method of claim 1, wherein:

the switching the direction of integration is performed prior to the sampling a second set of intermediate values.

12. The method of claim 1, wherein:

the direction of integration during the second operating regime comprises the second direction of integration.

13. One or more storage devices containing processor readable code for programming one or more processors to perform a method for determining depth information associated with a target object comprising the steps of:

capturing light during a first operating regime reflected from the target object using an array of one or more pixels, the array of one or more pixels is associated with a direction of integration, the direction of integration during the first operating regime comprises a first direction of integration;

sampling a first set of intermediate values associated with the array of one or more pixels during the first operating regime;

switching the direction of integration to a second direction of integration different from the first direction of integration;

capturing light during a second operating regime reflected from the target object using the array of one or more pixels, the second operating regime is subsequent to the first operating regime, the direction of integration during the second operating regime comprises the second direction of integration;

sampling a second set of intermediate values associated with the array of one or more pixels during the second operating regime;

determining a distance to the target object based on the first set of intermediate values and the second set of intermediate values, the array of one or more pixels is not reset during the first operating regime or the second operating regime, the array of one or more pixels is not reset between the first operating regime and the second operating regime; and

outputting the distance to the target object.

14. The one or more storage devices of claim 13, 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.

15. The one or more storage devices of claim 13, wherein:

the sampling a first set of intermediate values includes reading out the first set of intermediate values to digital circuitry outside an area of the array of one or more pixels.

16. A time-of-flight system for determining depth information associated with a target object, comprising:

a light emitter, the light emitter emits light during a first operating regime towards the target object, the light emitted during the first operating regime comprises light of a first phase, the light emitter emits light during a second operating regime towards the target object, the light emitted during the second operating regime comprises light of a third phase, the second operating regime is subsequent to the first operating regime;

an array of one or more pixels, the array of one or more pixels captures light during the first operating regime reflected from the target object, the light detected during the first operating regime comprises light of a second phase different from the first phase, the array of one or more pixels is associated with a direction of integration, the direction of integration during the first operating regime comprises a first direction of integration, the array of one or more pixels captures light during the second operating regime reflected from the target object, the light detected during the second operating regime comprises light of a fourth phase different from the third phase, the array of one or more pixels is not reset during the first operating regime or the second operating regime, the array of one or more pixels is not reset between the first operating regime and the second operating regime; and

one or more processors in communication with the light emitter and the array of one or more pixels, the one or more processors sample a first set of intermediate values associated with the array of one or more pixels during the first operating regime, the one or more processors switch the direction of integration to a second direction of integration different from the first direction of integration prior to the second operating regime;

the one or more processors sample a second set of intermediate values associated with the array of one or more pixels during the second operating regime, the one or more processors determine a distance to the target 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 light emitted during the first operating regime is associated with a first frequency; and

the light emitted during the second operating regime is associated with a second frequency different from the first frequency.

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

the one or more processors determine the distance based on a first phase shift between the light emitted during the first operating regime and the light detected during the first operating regime.

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

the one or more processors determine the distance based on a second phase shift between the light emitted during the second operating regime and the light detected during the second operating regime.