Imaging circuit capable of sensing flickering light

Patent metadata

Field	Value
Publication number	US-11750941-B1
Application number	US-202217737190-A
Country	US
Kind code	B1
Filing date	May 5, 2022
Priority date	May 5, 2022
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

An imaging circuit includes plural pixel circuits which are arranged in a pixel array. Each of the plural pixel circuits includes an image sensing device which is configured to sense a normal imaging light shedding on the imaging circuit with a predetermined frame rate. At least a portion of the plural pixel circuits are first type pixel circuits. Each of the first type pixel circuit further includes a flicker sensing device. Plural flicker sensing devices in the pixel array are coupled in parallel to sense a flickering light shedding on the imaging circuit to generate a flicker indicating signal.

First claim

What is claimed is:

1. An imaging circuit, comprising:
plural pixel circuits, which are arranged in a pixel array, wherein each of the plural pixel circuits includes an image sensing device which is configured to sense a normal imaging light shedding on the imaging circuit with a predetermined frame rate, wherein at least a portion of the plural pixel circuits are first type pixel circuits, wherein each of the first type pixel circuit further includes a flicker sensing device, wherein plural flicker sensing devices in the pixel array are coupled in parallel to sense a flickering light shedding on the imaging circuit to generate a flicker indicating signal.

2. The imaging circuit of claim 1 , wherein the plural pixel circuits generate corresponding image sensing signals according to the corresponding image sensing devices when the flicker indicating signal indicates that intensity of the flickering light exceeds an intensity threshold;
wherein when the flicker indicating signal indicates intensity of the flickering light does not exceed the intensity threshold, the plural pixel circuits stop generating the image sensing signals, or the imaging circuit stops processing the image sensing signals or generates the image sensing signals according to a preset frequency.

3. The imaging circuit of claim 1 , further comprising a flicker detection circuit, configured to generate the flicker indicating signal by comparing a flicker sensing signal generated by at least one of the flicker sensing device to a reference signal to determine whether the intensity of the flickering light exceeds the intensity threshold.

4. The imaging circuit of claim 1 , wherein a frequency of the flicker indicating signal is related to or is equal to a frequency of the flickering light.

5. The imaging circuit of claim 1 , wherein image frames formed by image sensing signals are compared for motion detection.

6. The imaging circuit of claim 1 , wherein the first type pixel circuits are arranged to be evenly distributed in the pixel array.

7. The imaging circuit of claim 1 , wherein each of the pixel circuits includes the flicker sensing device.

8. The imaging circuit of claim 6 , wherein each of another portion of the plural pixel circuits is a second type pixel circuit, wherein in at least one dimension, at least one first type pixel circuit and at least one second type pixel circuit are arranged in a predetermined pattern which is repeated in the at least one dimension;
wherein the second type pixel circuit is irresponsive to the flickering light in continuous time.

9. The imaging circuit of claim 8 , wherein the predetermined pattern is repeated in a first dimension, and is duplicated along a second dimension.

10. The imaging circuit of claim 8 , wherein the predetermined pattern is duplicated along the other dimension with a linearly changing shift in position or with an oscillating shift in position.

11. The imaging circuit of claim 8 , wherein in the at least one dimension, each pair of the first type pixel circuits which are located in neighbor with each other are separated by at least one second type pixel circuit.

12. The imaging circuit of claim 8 , wherein in the at least one dimension, each pair of the second type pixel circuits which are located in neighbor with each other are separated by at least one first type pixel circuit.

13. The imaging circuit of claim 1 , wherein the first type pixel circuits are arranged in plural ringed areas in the pixel array, wherein the first type pixel circuits located in neighboring ringed areas are separated by a ringed area which is formed by second type pixel circuits, wherein the second type pixel circuit is irresponsive to the flickering light.

14. The imaging circuit of claim 1 , wherein a first portion of the plural flicker sensing devices in the pixel array are coupled in parallel to form a first flicker sensing unit to operably sense the flickering light shedding on the first portion of the plural flicker sensing devices, and a second portion of the plural flicker sensing devices in the pixel array are coupled in parallel to form a second flicker sensing unit to operably sense the flickering light shedding on the second portion of the plural flicker sensing devices, wherein the first flicker sensing unit and the second flicker sensing unit are coupled, other than being electrically coupled directly in parallel, to generate the flicker indicating signal.

15. The imaging circuit of claim 14 , wherein the first flicker sensing unit is electrically coupled to a first resistor as a first branch and the second flicker sensing unit is electrically coupled to a second resistor as a second branch, wherein the first branch and the second branch are coupled to sense the flickering light shedding on the imaging circuit to generate the flicker indicating signal.

16. The imaging circuit of claim 1 , wherein a first portion of the plural flicker sensing devices in the pixel array are coupled in parallel to form a first flicker sensing unit to operably sense the flickering light shedding on the first portion of the plural flicker sensing devices to generate a first flicker sensing signal, and a second portion of the plural flicker sensing devices in the pixel array are coupled in parallel to forma second flicker sensing unit to operably sense the flickering light shedding on the second portion of the plural flicker sensing devices to generate a second flicker sensing signal;
wherein the imaging circuit further comprising a first flicker detection circuit and a second flicker detection circuit, wherein the first flicker detection circuit is configured to generate a first flicker indicating signal according to the first flicker sensing signal to determine whether the intensity of the flickering light shedding on the first portion of the plural flicker sensing devices exceeds an intensity threshold, and the second flicker detection circuit is configured to generate a second flicker indicating signal according to the second flicker sensing signal to determine whether the intensity of the flickering light shedding on the second portion of the plural flicker sensing devices exceeds an intensity threshold.

17. The imaging circuit of claim 1 , wherein the flicker sensing device and the image sensing device are arranged as one of the following:
at least a portion of periphery of the flicker sensing device is adjacent to a portion of periphery of the image sensing device; or
the flicker sensing device is enclosed by the image sensing device.

18. The imaging circuit of claim 1 , wherein the image sensing device and the flicker sensing device have the same light to electrical characteristic, or have different light to electrical characteristics.

19. The imaging circuit of claim 1 , wherein the image sensing device includes a silicon P-N junction, and/or the flicker sensing device includes another silicon P-N junction.

20. The imaging circuit of claim 1 , wherein the flicker sensing device is configured to sense the flickering light in continuous time.

21. The imaging circuit of claim 1 , wherein the area of the image sensing device is larger than the area of the flicker sensing device.

22. The imaging circuit of claim 1 , wherein each of another portion of the plural pixel circuits is a second type pixel circuit, wherein the first type pixel circuits and the second type pixel circuits are arranged in a random sequence in the at least one dimension, wherein the second type pixel circuit is irr

Assignees

• Pixart Imaging Inc

Inventors

• Lim Wooi-Kip
• Tan Shan-Chong

Classifications

• H04N25/53 Primary

  Control of the integration time · CPC title

• H04N25/76

  Addressed sensors, e.g. MOS or CMOS sensors · CPC title

• H04N25/703

  SSIS architectures incorporating pixels for producing signals other than image signals · CPC title