Event driven shared memory pixel

Patent metadata

Field	Value
Publication number	US-12481065-B2
Application number	US-202017607056-A
Country	US
Kind code	B2
Filing date	May 1, 2020
Priority date	May 1, 2019
Publication date	Nov 25, 2025
Grant date	Nov 25, 2025

Abstract

A Time of Flight (TOF) system includes an incrementing circuit and a plurality of pixels. Each pixel includes a plurality of detectors configured to output respective detection signals responsive to detection of a plurality of photons incident thereon and a shared memory configured to store a respective count of the photons incident on each of the plurality of detectors. The incrementing circuit is configured to update the respective count for each of the plurality of detectors in the shared memory based on the respective detection signals.

First claim

The invention claimed is:

1 . A Time of Flight (TOF) system, comprising:
an incrementing circuit; and a plurality of pixels, each pixel comprising:
a plurality of detectors configured to output respective detection signals responsive to detection of a plurality of photons incident thereon; and
a shared memory configured to store a respective count of the photons incident on each of the plurality of detectors,
wherein the incrementing circuit is configured to update the respective count for each of the plurality of detectors in the shared memory based on the respective detection signals, wherein the shared memory comprises a plurality of bins, and wherein a subset of the plurality of bins is associated with a first detector of the plurality of detectors, and each bin of the subset is configured to store the respective count of the photons incident on the first detector during a time period.

2 . The TOF system of claim 1 , further comprising a bin sampling circuit configured to select a first bin from among the subset of the plurality of bins into which the respective count of the photons incident on the first detector is stored.

3 . The TOF system of claim 2 , wherein the bin sampling circuit is further configured to be activated responsive to detection of the photons by the first detector.

4 . The TOF system of claim 2 , wherein the bin sampling circuit is further configured to be held in reset by the first detector prior to the first detector detecting the photons.

5 . The TOF system of claim 2 , wherein respective ones of the plurality of pixels further comprise a bus arbiter that controls access to the shared memory by the plurality of detectors of the pixel.

6 . The TOF system of claim 5 , wherein the bus arbiter is configured to receive a plurality of requests from multiple ones of the plurality of detectors for access to the shared memory and, responsive thereto, select one detector of the plurality of detectors to be given access to the shared memory.

7 . The TOF system of claim 1 , wherein the incrementing circuit is further configured to update the respective count for each of the plurality of detectors in the shared memory responsive to the respective detection signals output by one or more of the plurality of detectors.

8 . The TOF system of claim 1 , wherein the incrementing circuit is an arithmetic logic unit (ALU) that is shared among the plurality of pixels.

9 . The TOF system of claim 8 , wherein the ALU is configured to perform a read-increment-write operation on the shared memory of each of the pixels.

10 . The TOF system of claim 1 , wherein at least one of the plurality of detectors is a Single Photon Avalanche Diode (SPAD).

11 . The TOF system of claim 1 , wherein the incrementing circuit is further configured to update the respective count for each of the plurality of detectors for each of the plurality of pixels.

12 . The TOF system of claim 1 , wherein at least one of the pixels has an area of less than 10 μm by 10 μm.

13 . The TOF system of claim 1 , wherein at least one of the pixels has an area of less than 3 μm by 3 μm.

14 . The TOF system of claim 1 , wherein the pixel has a full-well depth of at least 10000 photons.

15 . The TOF system of claim 1 , wherein the shared memory is a static random access memory (SRAM) or a dynamic random access memory (DRAM).

16 . The TOF system of claim 1 , wherein the incrementing circuit comprises a Linear Feedback Shift Register (LFSR).

17 . The TOF system of claim 1 , wherein the TOF system comprises a plurality of tiers,
wherein a first tier of the plurality of tiers comprises the detectors; and wherein a second tier of the plurality of tiers comprises the shared memory.

18 . The TOF system of claim 1 , wherein the incrementing circuit is further configured to update the respective count for each of the plurality of detectors responsive to comparison to a threshold value.

19 . The TOF system of claim 18 , wherein the threshold value is based on a background level of light associated with a field of view of the ToF system or a capacity of the shared memory.

20 . The TOF system of claim 18 , wherein the incrementing circuit is further configured to associate a respective counter with each bin of the subset of the plurality of bins and to update the counter based on whether the respective count of the photons incident on the first detector during the time period exceeds the threshold value.

21 . A Time of Flight (TOF) system, comprising:
an incrementing circuit; and a plurality of pixels, each pixel comprising:
a plurality of detectors configured to output respective detection signals responsive to detection of a plurality of photons incident thereon;
a shared memory comprising a plurality of bins, each bin configured to store a respective count of photons incident on one of the plurality of detectors during a respective time period; and
a bin sampling circuit configured to select a first bin from among the plurality of bins into which the respective count of the photons incident on a first detector of the plurality of detectors is stored,
wherein the incrementing circuit is configured to update the respective count of the photons incident on the first detector in the shared memory at the first bin in the shared memory indicated by the bin sampling circuit.

22 . The TOF system of claim 21 , wherein the bin sampling circuit is further configured to be activated responsive to detection of the photons by the first detector.

23 . The TOF system of claim 21 , wherein the bin sampling circuit is further configured to be held in reset by the first detector prior to detection of the photons by the first detector.

24 . The TOF system of claim 21 , wherein respective ones of the plurality of pixels further comprise a bus arbiter that controls access to the shared memory by the plurality of detectors of the pixel.

25 . The TOF system of claim 24 , wherein the bus arbiter is configured to receive a plurality of requests from multiple ones of the plurality of detectors for access to the shared memory and, responsive thereto, select one detector of the plurality of detectors to be given access to the shared memory.

26 . The TOF system of claim 21 , wherein the incrementing circuit is further configured to update the respective count for the first detector responsive to comparison to a threshold value.

27 . The TOF system of claim 26 , wherein the threshold value is based on a background level of light associated with a field of view of the ToF system, a capacity of the shared memory, and/or a saturation level of digital conversion circuitry associated with the TOF system.

28 . The TOF system of claim 26 , wherein a subset of the plurality of bins are associated with the first detector, and
wherein the incrementing circuit is further configured to associate a respective counter with each bin of the subset of the plurality of bins and to update the counter based on whether the respective count of the photons incident on the first detector during the time period exceeds the threshold value.

29 . A Time of Flight (TOF) system, comprising:
an incrementing circuit; and a plurality of pixels, each pixel comprising:
a plurality of detectors configured to output respective detection signals responsive to detection of a plur

Assignees

• Sense Photonics Inc

Inventors

• Henderson Robert
• Finkelstein Hod

Classifications

• G01S7/4915

  Time delay measurement, e.g. operational details for pixel components (signal extraction and conditioning G01S7/493); Phase measurement · CPC title

• G01S7/4865

  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 title

• G01S7/4816

  of receivers alone · CPC title

• G01S7/4815

  using multiple transmitters · CPC title

• G06F13/1605

  based on arbitration (arbitration in handling access to a common bus or bus system G06F13/36) · CPC title