Optical distance measuring device and printing apparatus using the same

摘要

An optical distance measuring device has an objective lens that condenses light from a light emission element to irradiate a measuring object and to form on the measuring object a light spot having a diameter not smaller than 10 mum and not larger than 30 mum. A light receiving lens condenses light reflected from the light spot on the measuring object to make the light incident on a photodetector through a pinhole having a diameter not smaller than 10 mum and not larger than 50 mum. With movement of the measuring object, detection signal of which an amplitude and an output level change according to a distance to the measuring object is obtained from the photodetector.