US 12,170,841 B2
Power reduction for LEDs based on infrared pulsing
Ramkrishna Swamy, Morgan Hill, CA (US)
Assigned to Cisco Technology, Inc., San Jose, CA (US)
Filed by Cisco Technology, Inc., San Jose, CA (US)
Filed on Aug. 29, 2022, as Appl. No. 17/898,286.
Prior Publication US 2024/0073517 A1, Feb. 29, 2024
Int. Cl. H04N 23/65 (2023.01); H04N 5/33 (2023.01); H04N 23/73 (2023.01); H04N 23/74 (2023.01)
CPC H04N 23/651 (2023.01) [H04N 5/33 (2013.01); H04N 23/73 (2023.01)] 14 Claims
OG exemplary drawing
 
1. A system for reducing infrared (IR) light emitting diode (LED) power in a night mode for LED operations, the system comprising:
an input power source;
one or more LEDs coupled to the input power source;
an auto-exposure controller (AEC) coupled to one or more LEDs; and
one or more transistor switches coupled between the one or more LEDs and the AEC,
wherein the AEC is coupled to an image sensor of an imaging system and configures attributes of exposure frames for the image sensor, the attributes comprising a beginning of sensor exposure and an end of sensor exposure for image frames captured by the image sensor;
wherein the AEC is configured to generate a plurality of pulses that control the one or more transistor switches, different subsets of the plurality of pulses having different frequencies,
wherein the AEC is configured to synchronize an activation of the one or more LEDs to occur during the exposure frame and disables the activation of one or more LEDs during vertical blanking periods of the image frames,
wherein the one or more transistor switches are configured to switch the power of the one or more LEDs for a time measured in nanoseconds and allow a high current to pass through the one or more LEDs causing the one or more LEDs to produce a pulse of light during the exposure frames,
wherein the AEC is configured to synchronize a first of the plurality of pulses with the beginning of the sensor exposure of one or more of the exposure frames based on latency between the image sensor and a pulse generator;
wherein the pulse generator comprises a first pulse generator configured to generate a first subset of the plurality of pulses having a first frequency with and a second pulse generator configured to generate a second subset of the plurality of pulses having a second frequency with a shift from the first subset of the plurality of pulses.