US 11,991,465 B2
Low power event driven pixels with passive, differential difference detection circuitry, and reset control circuits for the same
Andreas Suess, San Jose, CA (US); and Shoushun Chen, Shanghai (CN)
Assigned to OmniVision Technologies, Inc., Santa Clara, CA (US)
Filed by OMNIVISION TECHNOLOGIES, INC., Santa Clara, CA (US)
Filed on Jul. 27, 2022, as Appl. No. 17/815,526.
Prior Publication US 2024/0040278 A1, Feb. 1, 2024
Int. Cl. H04N 25/709 (2023.01); H04N 25/50 (2023.01); H04N 25/74 (2023.01); H04N 25/778 (2023.01)
CPC H04N 25/709 (2023.01) [H04N 25/50 (2023.01); H04N 25/74 (2023.01); H04N 25/778 (2023.01)] 34 Claims
OG exemplary drawing
 
1. An event driven pixel, comprising:
a photosensor configured to generate photocurrent in response to incident light received from an external scene;
photocurrent-to-voltage converter coupled to the photosensor to convert the photocurrent to a voltage; and
a difference circuit coupled to the photocurrent-to-voltage converter, wherein the difference circuit includes:
a first circuit branch configured (i) to sample a reference light level based at least in part on the voltage and assertion of a reset signal applied to the event driven pixel and (ii) to output a first analog light level onto a first column line, wherein the first analog light level is based at least in part on the reference light level, and
a second circuit branch configured (i) to sample a light level based at least in part on the voltage and assertion of a switch signal applied to the event driven pixel and (ii) to output a second analog light level onto a second column line, wherein the second analog light level is based at least in part on the light level,
wherein a difference between the second analog light level and the first analog light level is indicative of whether the event driven pixel has detected an event in the external scene.