Interference reduction for TOF systems

Patent metadata

Field	Value
Publication number	US-9442186-B2
Application number	US-201314055660-A
Country	US
Kind code	B2
Filing date	Oct 16, 2013
Priority date	May 13, 2013
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

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.

First claim

What is claimed is:

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 μsec; and
the incrementally ramping down the pulse amplitudes of the drive signal occurs over at least 50 μsec.

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 μsec 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 μsec 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 μsec 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 μsec 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 μsec 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 μsec 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 substan

Assignees

• Microsoft Corp
• Microsoft Technology Licensing Llc

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

Classifications

• G01S17/87

  Combinations of systems using electromagnetic waves other than radio waves · CPC title

• G01S17/36

  with phase comparison between the received signal and the contemporaneously transmitted signal · CPC title

• G01S17/894

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title

• G01S7/493 Primary

  Extracting wanted echo signals · CPC title

• G01S17/89

  for mapping or imaging · CPC title