Device for lighting emergency escape route and/or displaying emergency escape direction, compares optical sensor signal with modulated driving current of LED and determines whether a portion of sensor signal comprises the driving current

摘要

The device comprises a LED functioning as a light source, a LED power supply unit which is driven using a one time-varying current, and an optical sensor which detects the light emitted from the LED and converts it into electrical sensor signal. An evaluation device receives the sensor signal, compares it with the modulated driving current of LED, and determines whether at least a portion of the sensor signal comprises the modulated driving current of LED. An independent claim is included for method of monitoring the device used for lighting emergency escape route and/or displaying emergency escape direction.