Interference reduction for TOF systems

• US 9,442,186 B2
• Filed: 10/16/2013
• Issued: 09/13/2016
• Est. Priority Date: 05/13/2013
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Payne, Andrew, Bamji, Cyrus, Yee, Dawson, Thompson, Barry, Xu, Zhanping, Roland, Brock, Prather, Larry, Perry, Travis, Fenton, Mike, Acharya, Sunil, Gudaitis, Algird, Morris, Matthew
• Primary Examiner(s): Ratcliffe, Luke
• Assistant Examiner(s): Abraham, Samantha K
• Application Number:
  US14/055,660
• Publication Number:
  US 20140333917A1
• Time in Patent Office: 1,063 Days
• US Class Current: 1/1
• CPC Class Codes: G01S 17/36 with phase comparison between the received signal and the contemporaneously transmitted signal
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• 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 7/4865 Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak peak detection in noise, signal conditioning G01S7/487
• CPC Class Codes: G01S 7/493 Extracting wanted echo signals

Abstract

Embodiments disclosed herein are directed to time-of-flight (TOF) systems, and methods for use therewith, that substantially reduce interference that the TOF system may cause to at least one other system that is configured to wirelessly receive and respond to IR light signals. Some such embodiments involve emitting IR light having a low frequency (LF) power envelope that is shaped to substantially reduce frequency content within at least one frequency range known to be used by at least one other system that may be in close proximity to the TOF system. Such embodiments can also involve detecting at least a portion of the emitted RF modulated IR light that has reflected off one or more objects. A TOF system can produce depth images in dependence on results of the detecting, as well as update an application in dependence on the depth images.

Claims

1. For use by a time-of-flight (TOF) system that emits and detects infrared (IR) light, a method for substantially reducing interference that the TOF system may cause to at least one non-TOF system that is configured to wirelessly receive and respond to IR light remote control signals, the method comprising:

producing a radio frequency (RF) modulated drive signal;

driving an IR light source with the RF modulated drive signal;

in response to the driving emitting IR light having a low frequency (LF) power envelope that is shaped to substantially reduce frequency content within at least a frequency range from 10 kHz to 100 kHz that is available for use by at least one non-TOF system configured to wirelessly receive and respond to IR light remote control signals, wherein at least a portion of IR light being emitted by the TOF system is RF modulated IR light having a carrier frequency of at least 5 MHz; and

detecting at least a portion of the emitted RF modulated IR light that has reflected off one or more objects;

wherein the producing the RF modulated drive signal includes, when transitioning from a period that the drive signal does not include pulses to a period that the drive signal includes pulses, at least one of

incrementally ramping up pulse amplitudes of the drive signal,

incrementally ramping up pulse duty cycles of the drive signal,

incrementally ramping down temporal gaps between pulses or pulse trains of the drive signal, or

incrementally ramping down how often gaps occur between pulses or pulse trains of the drive signal.

2. The method of claim 1, wherein the emitting IR light comprises:

emitting IR light having a LF power envelope that is shaped to substantially reduce frequency content within at least two frequency ranges below 3 MHz that are available for use by non-TOF systems configured to wirelessly receive and respond to IR light signals, wherein one of the at least two frequency ranges is the frequency range from 10 kHz to 100 kHz.

3. The method of claim 1, wherein:

the TOF system is configured to obtain a separate depth image corresponding to each of a plurality of frame periods,

each frame period is followed by an inter-frame period,

each frame period includes at least two integration periods, and

each integration period is followed by a readout period; and

the emitting IR light includes emitting IR light during each of the integration periods; and

to reduce how often there are transitions from times during which IR light is being emitted and times during which IR light is not being emitted, and thereby reduce frequency content associated with the transitions, the emitting IR light also includes emitting IR light during the readout periods between pairs of the integration periods within each frame period.

4. The method of claim 1, wherein:

the TOF system is configured to obtain a separate depth image corresponding to each of a plurality of frame periods,

each frame period is followed by an inter-frame period,

each frame period includes at least two integration periods, and

each integration period is followed by a readout period; and

the emitting IR light includes emitting IR light during each of the integration periods; and

in order to decrease a gain level of an automatic gain control (AGC) circuit for use with an IR light receiver of at least one non-TOF system configured to wirelessly receive and respond to IR light remote control signals, and thereby make the IR light receiver of the at least one non-TOF system less sensitive to interference from the TOF system, the emitting IR light also includes emitting IR light during at least a portion at least one of;

(i) the readout periods between pairs of the integration periods within each frame period, or

(ii) the inter-frame periods between pairs of frames.

5. The method of claim 1, further comprising:

producing depth images in dependence on results of the detecting the at least a portion of the emitted RF modulated IR light that has reflected off one or more objects; and

updating an application in dependence on the depth images.

6. The method of claim 1, wherein:

the producing the RF modulated drive signal includes, when transitioning from a period that the drive signal includes pulses to a period that the drive signal does not include pulses, at least one of

incrementally ramping down pulse amplitudes of the drive signal,

incrementally ramping down pulse duty cycles of the drive signal,

incrementally ramping up temporal gaps between pulses or pulse trains of the drive signal, or

incrementally ramping up how often gaps occur between pulses or pulse trains of the drive signal.

7. The method of claim 6, wherein the producing the RF modulated drive signal comprises:

incrementally ramping up pulse duty cycles of the drive signal when transitioning from a said period that the drive signal does not include pulses to a said period that the drive signal includes pulses; and

incrementally ramping down pulse duty cycles of the drive signal when transitioning from a said period that the drive signal includes pulses to a said period that the drive signal does not include pulses.

8. The method of claim 5, wherein:

the incrementally ramping up the pulse amplitudes of the drive signal occurs over at least 50 μ

sec; and

the incrementally ramping down the pulse amplitudes of the drive signal occurs over at least 50 μ

sec.

9. The method of claim 6, wherein the producing the RF modulated drive signal comprises:

incrementally ramping up pulse duty cycles of the drive signal over a period of at least 50 μ

sec when transitioning from a said period that the drive signal does not include pulses to a said period that the drive signal includes pulses; and

incrementally ramping down pulse duty cycles of the drive signal over a period of at least 50 μ

sec when transitioning from a said period that the drive signal includes pulses to a said period that the drive signal does not include pulses.

10. The method of claim 6, wherein the producing the RF modulated drive signal comprises:

incrementally ramping down temporal gaps between pulses or pulse trains of the drive signal over a period of at least 50 μ

sec when transitioning from a said period that the drive signal does not include pulses to a said period that the drive signal includes pulses; and

incrementally ramping up temporal gaps between pulses or pulse trains of the drive signal over a period of at least 50 μ

sec when transitioning from a said period that the drive signal includes pulses to a said period that the drive signal does not include pulses.

11. The method of claim 6, wherein the producing the RF modulated drive signal comprises:

incrementally ramping down how often gaps occur between pulses or pulse trains of the drive signal over a period of at least 50 μ

sec when transitioning from a said period that the drive signal does not include pulses to a said period that the drive signal includes pulses; and

incrementally ramping up how often gaps occur between pulses or pulse trains of the drive signal over a period of at least 50 μ

sec when transitioning from a said period that the drive signal includes pulses to a said period that the drive signal does not include pulses.

12. A time-of-flight (TOF) system, comprising:

at least one light source configured to emit infrared (IR) light in response to be driven;

a driver configured to produce a radio frequency (RF) modulated drive signal and drive the at least one light source with the RF modulate drive signal to thereby cause the at least one light source to emit IR light having a low frequency (LF) power envelope that is shaped to substantially reduce frequency content within at least a frequency range from 10 kHz to 100 kHz that is available for use by at least one non-TOF system configured to wirelessly receive and respond to IR light remote control signals, wherein at least a portion of IR light emitted in response to the driver driving the at least one light source with the RF modulated drive signal is RF modulated IR light having a carrier frequency of at least 5 MHz;

a clock signal generator configured to produce a clock signal that is provided to the driver;

a processor configured to control at least one of the clock signal generator or the driver; and

an image pixel detector array configured to detect at least a portion of the emitted RF modulated IR light that has reflected off one or more objects and is incident on an image pixel detector array;

wherein at least one of the processor, the clock signal generator or the driver is/are configured to cause the emitted RF modulated IR light to include, when transitioning from a period when RF modulated IR light is not emitted to a period when RF modulated IR light is emitted, at least one of

pulses having amplitudes that incrementally ramp up,

pulses having duty cycles that incrementally ramp up,

pulses or pulse trains having temporal gaps that incrementally ramp down, or

pulses or pulse trains where how often gaps occur between the pulses or pulse trains incrementally ramp down.

13. The system of claim 12, wherein:

the TOF system is configured to obtain a separate depth image corresponding to each of a plurality of frame periods,

each frame period is followed by an inter-frame period,

each frame period includes at least two integration periods, and

each integration period is followed by a readout period; and

the driver is configured to drive a said light source to emit IR light during each of the integration periods;

the driver is configured to drive a said light source to emit IR light during the readout periods between pairs of the integration periods within each frame period, in order to reduce how often there are transitions from times during which IR light is being emitted and times during which IR light is not being emitted, and thereby reduce frequency content associated with the transitions; and

the light source driven to emit IR light during the readout periods can be the same or different than the light source driven to emit IR light during the integration periods.

14. The system of claim 12, wherein:

the TOF system is configured to obtain a separate depth image corresponding to each of a plurality of frame periods,

each frame period is followed by an inter-frame period,

each frame period includes at least two integration periods, and

each integration period is followed by a readout period; and

the driver is configured to drive a said light source to emit IR light during each of the integration periods;

the driver is configured to drive a said light source to emit IR light during at least a portion at least one of (i) the readout periods between pairs of the integration periods within each frame period or (ii) the inter-frame periods between pairs of frames, in order to decrease a gain level of an automatic gain control (AGC) circuit for use with an IR light receiver of at least one non-TOF system configured to wirelessly receive and respond to IR light remote control signals, and thereby make the IR light receiver of the at least one non-TOF system less sensitive to interference from the TOF system; and

the light source that is driven to emit IR light during at least a portion at least one of (i) the readout periods between pairs of the integration periods within each frame period or (ii) the inter-frame periods between pairs of frames, can be the same as or different than the light source driven to emit IR light during the integration periods.

15. The system of claim 12, wherein:

at least one of the processor, the clock signal generator or the driver is/are configured to cause the emitted RF modulated light to include, when transitioning from a period when RF modulated light is emitted to a period when RF modulated light is not emitted, at least one of

pulses having amplitudes that incrementally ramp down,

pulses having duty cycles that incrementally ramp down,

pulses or pulse trains having temporal gaps that incrementally ramp up, or

pulses or pulse trains where how often gaps occur between the pulses or pulse trains incrementally ramp up.

16. The system of claim 15, wherein at least one of the processor, the clock signal generator or the driver is/are configured to:

incrementally ramp up pulse amplitudes of the drive signal when transitioning from a time during which no IR light is emitted to a time during which IR light is emitted; and

incrementally ramp down pulse amplitudes of the drive signal when transitioning from a time during which IR light is emitted to a time during which no IR light is emitted.

17. The system of claim 15, wherein at least one of the processor, the clock signal generator or the driver is/are configured to:

incrementally ramp up pulse duty cycles of the drive signal when transitioning from a time during which no IR light is emitted to a time during which IR light is emitted; and

incrementally ramp down pulse duty cycles of the drive signal when transitioning from a time during which IR light is emitted to a time during which no IR light is emitted.

18. The system of claim 15, wherein at least one of the processor, the clock signal generator or the driver is/are configured to:

incrementally ramp down temporal gaps between, or how often gaps occur between, pulses or pulse trains of the drive signal when transitioning from a time during which no IR light is emitted to a time during which IR light is emitted; and

incrementally ramp up temporal gaps between, or how often gaps occur between, pulses or pulse trains of the drive signal when transitioning from a time during which IR light is emitted to a time during which no IR light is emitted.

19. One or more hardware storage devices having instructions encoded thereon which when executed cause one or more processors to perform a method for substantially reducing interference that a time-of flight (TOF) system may cause to at least one non-TOF system that is configured to wirelessly receive and respond to infrared (IR) light remote control signals, the method comprising:

producing a radio frequency (RF) modulated drive signal that drives at least one light source of the TOF system to emit IR light having a carrier frequency of at least 5 MHz and having a low frequency (LF) power envelope that is shaped to substantially reduce frequency content within at least a frequency range from 10 kHz to 100 kHz that is available for use by at least one non-TOF system configured to wirelessly receive and respond to IR light remote control signals;

producing depth images in dependence on portions of emitted IR light that have reflected off one or more objects and are detected by an image pixel detector array of the TOF system; and

updating an application in dependence on the depth images;

wherein the producing the RF modulated drive signal includes, when transitioning from a period that the drive signal does not include pulses to a period that the drive signal includes pulses, at least one of

incrementally ramping up pulse amplitudes of the drive signal,

incrementally ramping up pulse duty cycles of the drive signal,

incrementally ramping down temporal gaps between pulses or pulse trains of the drive signal, or

incrementally ramping down how often gaps occur between pulses or pulse trains of the drive signal.

20. The one or more hardware storage devices of claim 19, wherein:

the producing the drive signal includes, when transitioning from a period that the drive signal includes pulses to a period that the drive signal does not include pulses, at least one of

incrementally ramping down pulse amplitudes of the drive signal,

incrementally ramping down pulse duty cycles of the drive signal,

incrementally ramping up temporal gaps between pulses or pulse trains of the drive signal, or

incrementally ramping up how often gaps occur between pulses or pulse trains of the drive signal.