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EP-4740487-A1 - SPAD SENSOR FOR NIGHT VISION APPLICATIONS

EP4740487A1EP 4740487 A1EP4740487 A1EP 4740487A1EP-4740487-A1

Abstract

Techniques to provide a low-power single-photon avalanche diode (SPAD) image. An example imaging device includes a SPAD array having a plurality of pixels configured to detect electromagnetic radiation, and a processing device configured to deactivate, based on an event count, a pixel of the SPAD array for a remaining duration of a first detection frame of the SPAD array. The pixel can remain deactivated for the remaining duration, and the remaining duration can span from a deactivation time until an end of the first SPAD frame. The processing device can be further configured to reactivate the pixel in a subsequent detection frame of the SPAD array.

Inventors

  • YI, XIANMIN
  • LU, ALEXANDER
  • HU, SHANLI
  • TAM, EDMOND
  • LOPEZ, ANGEL
  • TIAN, William G.

Assignees

  • Fairchild Imaging, Inc.

Dates

Publication Date
20260513
Application Date
20240123

Claims (20)

  1. 1. A method of providing a single-photon avalanche diode (SPAD) image, the method comprising: deactivating, based on an event count, a pixel of a SPAD array for a remaining duration of a first SPAD frame, wherein the pixel remains deactivated for the remaining duration and the remaining duration spans from a deactivation time until an end of the first SPAD frame; and reactivating the pixel in a subsequent SPAD frame.
  2. 2. The method of claim 1, wherein the event count comprises an event count forthe pixel, and deactivating the pixel is in response to the event count for the pixel reaching or exceeding a threshold count.
  3. 3. The method of claim 2, wherein the event count for the pixel comprises an event count for the pixel during the first SPAD frame.
  4. 4. The method of claim 2, wherein the event count for the pixel corresponds to a number of avalanche events counted by a counter.
  5. 5. The method of claim 2, wherein the threshold count is based on a square of a predetermined signal-to-noise ratio.
  6. 6. The method of claim 1, wherein the event count comprises an event count forthe pixel, and further comprising estimating an intensity for the pixel for the first SPAD frame based on a count rate for the pixel, the count rate based on the event count for the pixel and a time measure corresponding to the event count.
  7. 7. The method of claim 6, wherein the count rate for the pixel comprises the event count for the pixel divided by the time measure corresponding to the event count, and the estimated intensity for the pixel comprises a product of the count rate and a full duration of the first SPAD frame.
  8. 8. The method of claim 7, wherein: the event count for the pixel comprises a number of events measured during the first SPAD frame; the first SPAD frame is divided into a plurality of time windows; the time measure for the event count comprises a number of the time windows for the event count; and the full duration of the first SPAD frame comprises a total number of the plurality of time windows of the first SPAD frame.
  9. 9. The method of claim 6, wherein the estimated intensity for the pixel for the first SPAD frame corresponds to a dynamic range of the pixel for the first SPAD frame.
  10. 10. The method of claim 1, further comprising: deactivating a plurality of pixels of the SPAD array for respective remaining durations of the first SPAD frame; wherein reactivating the pixel in the subsequent SPAD frame includes reactivating the plurality of pixels at a start of the subsequent SPAD frame.
  11. 11. The method of claim 1, wherein the SPAD image comprises a 2-dimensional (2D) night vision image.
  12. 12. An imaging device, comprising: a single-photon avalanche diode (SPAD) array having a plurality of pixels configured to detect electromagnetic radiation; and a processing device configured to deactivate, based on an event count, a pixel of the SPAD array for a remaining duration of a first SPAD frame of the SPAD array, wherein the pixel remains deactivated for the remaining duration and the remaining duration spans from a deactivation time until an end of the first SPAD frame, and reactivate the pixel in a subsequent SPAD frame of the SPAD array.
  13. 13. The imaging device of claim 12, wherein the event count comprises an event count for the pixel during the first SPAD frame, and to deactivate the pixel comprises to deactivate the pixel in response to the event count for the pixel during the first SPAD frame reaching or exceeding a threshold count.
  14. 14. The imaging device of claim 13, wherein the event count for the pixel corresponds to a number of avalanche events counted by a counter.
  15. 15. The imaging device of claim 12, wherein the event count comprises an event count for the pixel, and the processing device is further configured to estimate an intensity for the pixel for the first SPAD frame based on a count rate for the pixel, the count rate based on the event count for the pixel and a time measure corresponding to the event count.
  16. 16. The imaging device of claim 15, wherein: the first SPAD frame is divided into a plurality of time windows; the count rate for the pixel comprises the event count for the pixel divided by the time measure for the event count; the event count for the pixel comprises a number of events measured during the first SPAD frame; the time measure for the event count comprises a number of the time windows for the event count; and the estimated intensity for the pixel comprises a product of the count rate and a total number of the plurality of time windows of the first SPAD frame.
  17. 17. One or more non-transitory machine-readable mediums storing instructions that when executed by one or more processors cause an imaging process to be carried out to: deactivate, based on an event count, a pixel of a single-photon avalanche diode (SPAD) array for a remaining duration of a first SPAD frame, wherein the pixel remains deactivated for the remaining duration and the remaining duration spans from a deactivation time until an end of the first SPAD frame; and reactivate the pixel in a subsequent SPAD frame.
  18. 18. The one or more non-transitory machine-readable mediums of claim 17, wherein the event count comprises an event count for the pixel during the first SPAD frame, and to deactivate the pixel comprises to deactivate the pixel in response to the event count for the pixel during the first SPAD frame reaching or exceeding a threshold count.
  19. 19. The one or more non-transitory machine-readable mediums of claim 17, wherein the event count comprises an event count for the pixel, and the instructions further comprise instructions to estimate an intensity for the pixel for the first SPAD frame based on a count rate for the pixel, the count rate based on the event count for the pixel and a time measure corresponding to the event count.
  20. 20. The one or more non-transitory machine-readable mediums of claim 19, wherein the count rate for the pixel comprises the event count for the pixel divided by the time measure for the event count, and the estimated intensity for the pixel comprises a product of the count rate and a full duration of the first SPAD frame.

Description

SPAD SENSOR FOR NIGHT VISION APPLICATIONS BACKGROUND [0001] Night vision generally refers to the ability to see in relatively low-light conditions, and can be achieved to some extent naturally by way of scotopic vision, and to a higher extent by way of night-vision technology. Night vision requires both sufficient spectral range and sufficient intensity range. A standard night vision sensor is based on a complementary metal oxide semiconductor (CMOS) image sensor (CIS) design. Unfortunately, the power consumption of such designs is relatively high (e.g., 500 milliwatts, or more). To this end, nontrivial issues with night vision remain. SUMMARY [0002] In an example, a method of providing a single-photon avalanche diode (SPAD) image is provided. The method can comprise deactivating, based on an event count, a pixel of a SPAD array for a remaining duration of a first SPAD frame, wherein the pixel remains deactivated for the remaining duration and the remaining duration spans from a deactivation time until an end of the first SPAD frame. The method can further comprise reactivating the pixel in a subsequent SPAD frame. In some cases, the event count comprises an event count for the pixel, and deactivating the pixel is in response to the event count for the pixel reaching or exceeding a threshold count. In some cases, the event count for the pixel comprises an event count for the pixel during the first SPAD frame. In some cases, the threshold count is based on a square of a predetermined signal-to-noise ratio. In some cases, the event count for the pixel corresponds to a number of avalanche events counted by a counter. In some cases, the event count comprises an event count for the pixel, and the method further comprises estimating an intensity for the pixel for the first SPAD frame based on a count rate for the pixel, the count rate based on the event count for the pixel and a time measure corresponding to the event count. In some cases, the count rate for the pixel comprises the event count for the pixel divided by the time measure corresponding to the event count. The estimated intensity for the pixel can comprise a product of the count rate and a full duration of the first SPAD frame. In some cases, the event count for the pixel comprises a number of events measured during the first SPAD frame. The first SPAD frame can be divided into a plurality of time windows. The time measure for the event count can comprise a number of the time windows for the event count. The full duration of the first SPAD frame can comprise a total number of the plurality of time windows of the first SPAD frame. In some cases, the estimated intensity for the pixel for the first SPAD frame corresponds to a dynamic range of the pixel for the first SPAD frame. In some cases, the method further comprises deactivating a plurality of pixels of the SPAD array for respective remaining durations of the first SPAD frame. Reactivating the pixel in the subsequent SPAD frame can include reactivating the plurality of pixels at a start of the subsequent SPAD frame. In some cases, the SPAD image comprises a 2-dimensional (2D) night vision image. [0003] In another example, an imaging device is provided. The imaging device can comprise a single-photon avalanche diode (SPAD) array having a plurality of pixels configured to detect electromagnetic radiation. The imaging device can further comprise a processing device configured to deactivate, based on an event count, a pixel of the SPAD array for a remaining duration of a first SPAD frame of the SPAD array, wherein the pixel remains deactivated for the remaining duration and the remaining duration spans from a deactivation time until an end of the first SPAD frame. The processing device can be further configured to reactivate the pixel in a subsequent SPAD frame of the SPAD array. [0004] In some cases, the event count comprises an event count for the pixel during the first SPAD frame, and to deactivate the pixel comprises to deactivate the pixel in response to the event count for the pixel during the first SPAD frame reaching or exceeding a threshold count. In some cases, the event count for the pixel corresponds to a number of avalanche events counted by a counter. In some cases, the event count comprises an event count for the pixel, and the processing device is further configured to estimate an intensity for the pixel for the first SPAD frame based on a count rate for the pixel, the count rate based on the event count for the pixel and a time measure corresponding to the event count. In some cases, the first SPAD frame is divided into a plurality of time windows. The count rate for the pixel can comprise the event count for the pixel divided by the time measure for the event count. The event count for the pixel can comprise a number of events measured during the first SPAD frame. The time measure for the event count can comprise a number of the time windows for the event count. The estimated intensi