Feedback controlled infrared proximity sensing system

A feedback controlled infrared proximity system has been presented. It exceeds the ranging performance of a conventional optical reflectance proximity system. Because of the use of dual infrared receivers, the influence of surface reflection properties on the accuracy of the distance measurement is significantly reduced and the measurement accuracy is greatly improved over a relative long distance. A pulse modulation approach has been used to minimise the interference of ambient light and allow the system to have much higher output power and wider dynamic range. Due to the introduction of adaptive control of the output power, the distance can be measured just based on the output of a single infrared receiver.