Optical distance detector.

摘要

The optical distance detector comprises a light-emitting diode 14, 16, 31 and a pair of photodiodes 15, 17, 30 which detect the amount or light incident thereon after being reflected at a surface of an object the distance to which is measured. The geometric parameters of the photodiodes are selected in such a manner that the output of a first photodiode decreases as the measured distance increases while the output of a second photodiode increases as the measured distance increases. Thus, the normalized differential output of the two photodiodes, from which the measured distance is determined, varies substantially linearly with respect to the measured distance. In preferred forms, the photodetectors have stepped concentric configurations so that small distances can be measured accurately and efficiently. <IMAGE> <IMAGE> <IMAGE>