Patent ID: 7417718

Claim:
An optical distance measuring apparatus for measuring a transit time of light between a time when the light is emitted and a time when the light reflected by an object to be measured is received, to detect a distance to the object, comprising: a light-emitting device for emitting an optical signal which is synchronized with a modulating signal having a predetermined repetition frequency; a photodetector for receiving the optical signal from the light-emitting device reflected by the object and converting the optical signal to an electrical signal; a switch for alternately choosing at least two channels for the electrical signal from the photodetector with a predetermined timing; a storage/differential operation section for storing electrical signals on the channels alternately chosen by the switch and performing a differential operation on the stored electrical signals; and a distance determining section for determining the distance to the object on the basis of a result of the differential operation of the storage/differential operation section.