The sensor allows the pilot light to be automatically re-ignited if the flame is no longer present. The circuit is a surprisingly simple one, with a PNP transistor being turned on by the flame ...

A similar idea using arrays of light-emitting diodes as virtual sensors has also been explored in the internet of things community for skeleton posture and hand pose estimation.

Apple's patent application for "Organic light emitting diode having photodiodes" describes a setup that places photo sensors above, below, or in line with an OLED array to detect and compensate ...