System and method for pulsed light pattern capturing using a dynamic vision sensor

Patent metadata

Field	Value
Publication number	US-10909824-B2
Application number	US-201816103379-A
Country	US
Kind code	B2
Filing date	Aug 14, 2018
Priority date	Aug 14, 2018
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A pulsed image capturing system includes a pulse generation circuit, a dynamic vision sensor (DVS), and a DVS scanning and readout circuit. A global reset signal is transmitted to pixels of the DVS to set a reference illumination level for the pixels, and then a pulsed light pattern is generated. A global hold signal is transmitted to the pixels, after the pulsed light pattern is generated, to hold an illumination change event indicating a change with respect to the reference illumination level. A DVS scanning and readout operation is performed on event signals received from the pixels, after the global hold signal is transmitted to the pixels. A reflection of the pulsed light pattern is extracted from the DVS output after cleaning artifacts from the DVS output without additional image processing.

First claim

We claim:

1. A pulsed image capturing system, comprising:
a pulse generation circuit configured to generate a pulsed light pattern at an external object;
a dynamic vision sensor (DVS) including a pixel array having a plurality of pixels arranged in matrix form, wherein the plurality of pixels are configured to perform a light sensing operation to sense an amount of light from the pulsed light pattern reflected by the external object and output event signals;
a DVS scanning and readout circuit configured to perform a DVS scanning and readout operation on the event signals received from the plurality of pixels to generate a DVS output; and
a plurality of multiplexers configured to select a plurality of control signals, wherein the plurality of multiplexers comprises:
a first multiplexer configured to select one of an internal light pulse synchronization signal and an external light pulse synchronization signal in response to a first selection signal;
a second multiplexer configured to select one of an internal global reset signal and an external global reset signal in response to a second selection signal; and
a third multiplexer configured to select one of an internal global hold signal and an external global hold signal in response to a third selection signal,
wherein the internal light pulse synchronization signal and the external light pulse synchronization control when the pulsed light pattern is generated,
the internal global reset signal and the external global reset signal control whether each of the plurality of pixels sets a reference illumination level in a current state, and
the internal global hold signal and the external global hold signal control whether the plurality of pixels hold an illumination change event indicating a change with respect to the reference illumination level for each of the plurality of pixels;

wherein the plurality of control signals synchronize operation of the pulsed image capturing system such that the light sensing operation is performed after the pulsed light pattern is generated and before the DVS scanning and readout operation is performed.

2. The pulsed image capturing system of claim 1 , wherein the pulsed light pattern is generated, the light sensing operation is performed, and the DVS scanning and readout operation is performed for a predetermined number of passes, and
the DVS output of the predetermined number of passes is averaged to generate a final DVS output.

3. The pulsed image capturing system of claim 1 , wherein the pulsed light pattern is generated by one of a light emitting diode (LED) or a vertical-cavity surface-emitting laser (VCSEL).

4. The pulsed image capturing system of claim 1 , wherein the pulsed light pattern includes a sequence of patterns.

5. The pulsed image capturing system of claim 1 , further comprising a configuration register configured to store a rate of capture of the pulsed image capturing system and to generate the plurality of control signals.

6. The pulsed image capturing system of claim 1 , wherein the first selection signal, the second selection signal, and the third selection signal are distinct signals.

7. A method of operating a pulsed image capturing system including a dynamic vision sensor (DVS) including a pixel array having a plurality of pixels, the method comprising:
activating a global reset signal and transmitting the global reset signal to each of the plurality of pixels to set a reference illumination level for each of the plurality of pixels;
deactivating the global reset signal to enable each of the plurality of pixels to sense an illumination change amount with respect to the reference illumination level thereof;
activating a pulsed light pattern directed at an external object, wherein the pulsed light pattern includes a sequence of patterns that are the same, wherein for each of the sequence of patterns, a configuration of the pulsed image capturing system is changed;
activating a global hold signal and transmitting the global hold signal to each of the plurality of pixels to hold an illumination change event indicating the illumination change amount thereof;
performing a DVS scanning and readout operation on event signals received from the plurality of pixels and generating a DVS output; and
deactivating the pulsed light pattern;
wherein the DVS output is generated for each of the sequence of patterns, and a weighted sum of the DVS output for each of the sequence of patterns is determined as a final DVS output.

8. The method of claim 7 , wherein the configuration of the pulsed image capturing system includes an adjustable duration between activation of the pulsed light pattern and transmission of the global hold signal.

9. The method of claim 7 , wherein the configuration of the pulsed image capturing system includes adjustable sensitivity thresholds for each of the plurality of pixels.

10. The method of claim 7 , wherein the DVS output is generated at least two times and averaged to generate a final DVS output.

11. A method of operating a pulsed image capturing system including a dynamic vision sensor (DVS) including a pixel array having a plurality of pixels, the method comprising:
activating a global reset signal and transmitting the global reset signal to each of the plurality of pixels to set a reference illumination level for each of the plurality of pixels;
deactivating the global reset signal to enable each of the plurality of pixels to sense an illumination change amount with respect to the reference illumination level thereof;
activating a pulsed light pattern directed at an external object;
activating a global hold signal and transmitting the global hold signal to each of the plurality of pixels to hold an illumination change event indicating the illumination change amount thereof;
performing a DVS scanning and readout operation on event signals received from the plurality of pixels and generating a DVS output; and
deactivating the pulsed light pattern;
wherein the DVS output is generated at least two times and combined to create a grey scale image of the pulsed light pattern.

12. The method of claim 7 , further comprising:
adjusting an intensity of the pulsed light pattern based on an amount of ambient light.

13. The method of claim 7 , further comprising:
increasing a duration between activation of the pulsed light pattern and transmission of the global hold signal to increase a sensitivity to contrast change.

14. The method of claim 7 , wherein the pulsed light pattern is deactivated before performing the DVS scanning and readout operation.

15. A method of operating a pulsed image capturing system including a dynamic vision sensor (DVS) including a pixel array having a plurality of pixels, the method comprising:
synchronizing activation of a global reset signal to be transmitted to the plurality of pixels to set a reference illumination level for each of the plurality of pixels;
deactivating the global reset signal to enable each of the plurality of pixels to sense an illumination change amount with respect to the reference illumination level thereof;
activating a pulsed light pattern directed at an external object after deactivation of the global reset signal, wherein the pulsed light pattern includes a sequence of patterns that are the same, wherein for each of the sequence of patterns, a configuration of the pulsed image capturing system is changed;
generating event signals, by the plurality of pixels, according to a comparison between a predetermined threshold and the sensed illumination change amount resulting from the pulsed light pattern; and
performing a DVS

Assignees

• Samsung Electronics Co Ltd

Inventors

• Yaffe Yoel
• Levy Nathan Henri

Classifications

• H04N25/00

  Circuitry of solid-state image sensors [SSIS]; Control thereof · CPC title

• H04N23/54 Primary

  Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils · CPC title

• H04N23/56 Primary

  provided with illuminating means · CPC title

• H04N25/78

  Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters · CPC title

• H04N25/47

  Image sensors with pixel address output; Event-driven image sensors; Selection of pixels to be read out based on image data · CPC title