Method and system to correct motion blur and reduce signal transients in time-of-flight sensor systems

• US 7,450,220 B2
• Filed: 10/16/2007
• Issued: 11/11/2008
• Est. Priority Date: 02/08/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Canesta Incorporated (Microsoft Corporation)
• Inventors: Nagabhirana, Rajeev, O'Connor, Patrick, Torunoglu, Ilhami
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): Ratcliffe; Luke D
• Application Number:
  US11/975,059
• Publication Number:
  US 20080036996A1
• Time in Patent Office: 392 Days
• Field of Search: 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22
• US Class Current: 356/5.1
• CPC Class Codes: G01C 25/00 Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass testing, calibrating or compensating compasses G01C17/38
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors

Abstract

TOF system shutter time needed to acquire image data in a time-of-flight (TOF) system that acquires consecutive images is reduced, thus decreasing the time in which relative motion can occur. In one embodiment, pixel detectors are clocked with multi-phase signals and integration of the four signals occurs simultaneously to yield four phase measurements from four pixel detectors within a single shutter time unit. In another embodiment, phase measurement time is reduced by a factor (1/k) by providing super pixels whose collection region is increased by a factor “k” relative to a normal pixel detector. Each super pixel is coupled to k storage units and four-phase sequential signals. Alternatively, each pixel detector can have k collector regions, k storage units, and share common clock circuitry that generates four-phase signals. Various embodiments can reduce the mal-effects of clock signal transients upon signals, and can be dynamically reconfigured as required.

Claims

1. In a time-of-flight (TOF) system that emits periodic signals of optical energy and that determines distance Z to a target object by detecting and examining relative phase shift in optical energy signals reflected from the target object, a detection system comprising:

an array of blocks of at least two pixel detectors, each pixel detector comprising an optical energy collection area, an associated logic circuit, and an associated storage region to store collected charge detected by said pixel detector; and

a phase clock unit outputting to each of said blocks at least two clock phase signals spaced-apart by at least about 90°

;

each said logic circuit coupled to receive at least one of said clock phase signals and to couple a version thereof to at least one of the optical energy collection areas;

each said storage region receiving accumulated detection-generated charge when the associated pixel detector receives an active state clock phase signal.

2. The detection system of claim 1, wherein said system is configured to improve at least one of (a) motion blur measurement error due to relative motion between said detection system and said target object relative to a TOF system that requires more phase clock cycles for detection, and (b) signal integrity error resulting from phase clock switching transients.

3. The detection system of claim 1, wherein said detection system includes a configuration selected from a group consisting of (a) a configuration of said blocks comprising two rows and two columns of said pixel detectors, (b) a configuration of said blocks comprising one row and four columns of said pixel detectors, (c) a configuration of said blocks comprising one column and four rows of said pixel detectors, and (d) a configuration wherein at least two logic circuits are phase inverters.

4. The detection system of claim 1, wherein said detection system is dynamically operable in a manner selected from a group consisting of (a) operation so as to simultaneously obtain and provide time interleaved and phase interleaved detection data, and (b) operation so as to sequentially obtain and provide at least one of time interleaved and phase interleaved detection data, which data is sequentially providable to said TOF system as required by said TOF system.

5. For use with a time-of-flight (TOF) system that emits optical energy and that determines distance Z to a target object by detecting and examining relative phase shift in optical energy signals reflected from the target object, a detection method comprising the following steps:

(a) providing an array of blocks of at least two pixel detectors, each pixel detector comprising an optical energy collection area, an associated logic circuit, and an associated storage region to store collected charge detected by said pixel detector; and

(b) providing a phase clock unit outputting to each of said blocks at least two clock phase signals spaced-apart by at least about 90°

;

each said logic circuit coupled to receive one of said clock phase signals and to couple a version thereof to at least one of the optical energy collection areas;

each said storage region receiving accumulated detection-generated charge when the associated pixel detector receives an active state clock phase signal.

6. The method of claim 5, wherein said method results in said TOF system improving at least one of (i) motion blur measurement error due to relative motion between said TOF system and said target object relative to a TOF system that requires more phase clock cycles for detection, and (ii) signal integrity error resulting from phase clock switching transients.

7. The method of claim 5, wherein step (a) includes at least one step selected from a group consisting of (i) providing a configuration of said blocks comprising two rows and two columns of said pixel detectors, (ii) providing a configuration of said blocks comprising one row and four columns of said pixel detectors, (iii) providing a configuration of said blocks comprising one column and four rows of said pixel detectors, and (iv) providing a configuration wherein at least two logic circuits are phase inverters.

8. The method of claim 5, further including dynamically configuring at least one of said array of blocks and said phase clock unit such that said TOF system is dynamically operable in at least one mode selected from a group consisting of (i) operation so as to simultaneously obtain and provide time interleaved and phase interleaved detection data, and (ii) operation so as to sequentially obtain and provide at least one of time interleaved and phase interleaved detection data, which data is sequentially providable to said TOF system as required by said TOF system.

9. In a time-of-flight (TOF) system that emits optical energy and that determines distance Z to a target object by detecting and examining relative phase shift in optical energy signals reflected from the target object, a detection system comprising:

an array of pixel detectors, each pixel detector comprising an optical energy collection area larger than a conventional pixel detector collection area by a factor of about four, an associated logic circuit, and four associated storage regions to store collected charge detected by said pixel detector; and

at least one phase clock unit outputting to each said pixel detector at least one common clock phase signal from which said associated logic circuit generates four clock phase signals spaced-apart from each other by at least about 90°

;

each of said storage regions receiving accumulated detection-generated charge when one of said four clock phase signals is in an active state.

10. The detection system of claim 9, wherein said system is configured to improve at least one of (i) motion blur measurement error due to relative motion between said detection system and said target object relative to a TOF system whose pixel detector collection area is smaller than said optical energy collection area, and (ii) signal integrity error resulting from phase clock switching transients.

11. The detector system of claim 9, wherein said detector system is dynamically configurable and operable in at least one mode selected from a group consisting of (i) operating so as to simultaneously obtain and provide time interleaved and phase interleaved detection data, and (ii) operating so as to sequentially obtain and provide at least one of time interleaved and phase interleaved detection data, which data is sequentially providable to said TOF system as required by said TOF system.

12. For use with a time-of-flight (TOF) system that emits optical energy and that determines distance Z to a target object by detecting and examining relative phase shift in optical energy signals reflected from the target object, a detection method comprising the following steps:

(a) providing an array of pixel detectors, each pixel detector comprising an optical energy collection area larger than a conventional pixel detector collection area by a factor of about four, an associated logic circuit, and four associated storage regions to store collected charge detected by said pixel detector; and

(b) providing at least one phase clock unit outputting to each said pixel detector at least one common clock phase signal from which said associated logic circuit generates four clock phase signals spaced-apart from each other by at least about 90°

.

each of said storage regions receiving accumulated detection-generated charge when one of said four clock phase signals is in an active state.

13. The method of claim 12, wherein said method results in said TOF system improving at least one of (i) motion blur measurement error due to relative motion between said detection system and TOF system relative to a TOF system whose pixel detector collection area is smaller than said optical energy collection area, and (ii) signal integrity error resulting from phase clock switching transients.

14. The method of claim 12, further including dynamically configuring at least one of said array of pixel detectors and said at least one phase clock signal so as to cause that TOF system to be dynamically operable in at least one mode selected from a group consisting of (i) operating so as to simultaneously obtain and provide time interleaved and phase interleaved detection data, and (ii) operating so as to sequentially obtain and provide at least one of time interleaved and phase interleaved detection data, which data is sequentially providable to said TOF system as required by said TOF system.

15. In a time-of-flight (TOF) system that emits optical energy and that determines distance Z to a target object by detecting and examining relative phase shift in optical energy signals reflected from the target object, a detection system comprising:

an array of pixel detectors, each pixel detector comprising four optical energy collection areas, four storage regions, each of said regions associated with one of said four optical energy collection areas to store collected charge detected by said pixel detector, and a common logic circuit coupled to receive from said TOF system at least one clock phase signal and to generate therefrom and to couple four clock signals phase-shifted from each other by about 90°

to said optical energy collection areas;

each said storage region receiving accumulated detection-generated charge when an associated collection area of said pixel detector receives an active state clock phase signal;

wherein relative to a TOF system that requires more phase clock cycles for detection, said detection system reduces at least one of (a) motion blur measurement error due to relative motion between said detection system and said target object, and (b) signal integrity error resulting from phase clock switching transients.

16. The detection system of claim 15, wherein said detection system is dynamically operable in at least one mode selected from a group consisting of (i) operating so as to simultaneously obtain and provide time interleaved and phase interleaved detection data, and (ii) operating so as to sequentially obtain and provide at least one of time interleaved and phase interleaved detection data, which data is sequentially providable to said TOF system as required by said TOF system.

17. The detection system of claim 16, wherein a shutter time comprising a sequence of four adjacent clock signals phase-shifted from each other by about 90°

is a time duration selected from a group consisting of (i) about 10 ms, (ii) a duration equal to what a prior art detection system would require to acquire a single phase of detection data.

18. For use with a time-of-flight (TOF) system that emits periodic signals of optical energy and that determines distance Z to a target object by detecting and examining relative phase shift in optical energy signals reflected from the target object, a method to reduce at least one of motion blur resulting from relative motion between said TOF system and said target object, and clock signal transients, the method comprising the following steps:

(a) providing a detection system comprising an array of blocks of pixel detectors, each pixel detector comprising four optical energy collection areas, four storage regions, each of said regions associated with one of said four optical energy collection area to store collected charge detected by said pixel detector, and a common logic circuit coupled to receive from said TOF system at least one clock phase signal and to generate therefrom and to couple four clock signals phase-shifted from each other by about 90°

to said optical energy collection areas; and

(b) providing said single clock phase signal from said TOF system;

each of said storage regions receiving accumulated detection-generated charge when an associated collection area of said pixel detector receives an active state clock phase signal;

wherein relative to a TOF system that requires more phase clock cycles for detection, said method reduces at least one of motion blur measurement error due to relative motion between said detection system and said target object, and signal integrity error resulting from clock switching transients.

19. The method of claim 18, further including dynamically configuring at least one of said array of blocks and said phase clock signal such that said detection system is dynamically operable in at least one mode selected from a group consisting of (i) operating so as to simultaneously obtain and provide time interleaved and phase interleaved detection data, and (ii) operating so as to sequentially obtain and provide at least one of time interleaved and phase interleaved detection data, which data is sequentially providable to said TOF system as required by said TOF system.

20. The method of claim 18, wherein a shutter time comprising a sequence of four adjacent clock signals phase-shifted from each other by about 90°

is a time duration selected from a group consisting of (i) about 10 ms, and (ii) a duration equal to what a prior art detection system would require to acquire a single phase of detection data.