OPTICAL REFLECTION-TYPE REVOLUTION DETECTOR

摘要

PURPOSE:To improve receptor efficiency and resolution and further enable miniaturization by providing revolution-detecting patterns radially in a rotating part and also providing a photodetector so that it is opposed to the revolution- detecting patterns via a slit plate CONSTITUTION:A revolution-detecting pattern plate 16 having radial reflecting patterns 14A and absorbing patterns 14B for detecting the number of revolutions is stuck to a rotor 2. A photodetector 13 composed of an emitter element 13A and a receptor element 13B is provided via a slit plate 15 having slits 15A so as to be opposed to said revolution-detecting pattern plate 16. The receptor element 13B receives brightness changing light according to rotation of the rotor 2 so that the number of revolution of the rotor 2 can be detected in this manner. The reflecting pattern 14A and absorbing pattern 14B are respectively formed to have almost the same width as a slit 15A of the slit plate 15 and the emitter element 13A and receptor element 13B are arranged so as to be in a row in the longer direction of the slit 15A.