Sensors making PCs greener and more secure

ST’s FlightSense ToF sensor, hidden behind a cover glass in the bezel of a laptop, monitors the user’s presence in front of their PC. When the user leaves, the ToF sensor detects their absence and immediately locks the system and directs it into the Windows Modern-Stand-by low-power state, improving security and reducing power consumption.

The ToF sensor then enters a low-power autonomous mode, scanning the scene for the user returning while keeping the PC asleep to save power. When the user returns, the ToF sensor wakes the PC and automatically enables facial recognition to log in without waiting for a key press or mouse movement.

The ST patented algorithm used in the system can distinguish an immobile person sitting in front of a PC from an inanimate object, such as a chair, without relying on video analytics from the power-hungry and potentially intrusive webcam. 

“By leveraging ST’s market-leading FlightSense Time-of-Flight ranging technology, the development of user presence detection brings extended battery life, improved data protection, and increased convenience to PC users,” said Eric Aussedat, Executive Vice President and General Manager Imaging, STMicroelectronics. 

ST’s ToF FlightSense technology hopes to improve ranging and proximity sensing by providing accurate distance measurements using miniature and low-cost sensors. The sensor works by measuring the time taken by a photon to travel from the sensor, reflect from a target, and be received again by the sensor. This photon ‘travel time’ is multiplied by the speed of light to compute the precise distance to the subject.

Traditional infra-red (IR) ranging sensors rely on reflected signal strength and cannot directly measure distance. Unlike ToF sensors, the effectiveness and accuracy of these IR sensors are affected by the reflectivity of the target. ST’s ToF sensors combine accurate target-range measurement with class-leading miniature size and low power consumption.