Optical movement detecting device and transport system using the same

摘要

In an optical movement detecting device, two semiconductor lasers irradiate an object with respective light beams to form two light spots on the object. Two light-receiving elements receive the two light beams reflected from the two light spots respectively and travelling in a predetermined direction. Based on a difference in phase between two signals S1, S2 outputted from the two light-receiving elements, a signal processor derives a movement speed of the object.