OPTICAL POSITION SENSOR

PURPOSE:To simplify construction by providing a slit plate which has slits to allow passage of the light across the two rows of photodetecting region parts between a photodetector having two rows of the photodetecting region parts of a specified width and pitch and a light source and moving relatively the slit plate and the photodetector. CONSTITUTION:An LED20 which is a light source is provided to a movable side object (not shown) moving in the direction X and a photodetector 21 is provided to a stationary side object (not shown), respectively. Photodetecting region parts 22 of the same width (a) are formed into to rows to the detector 12 at the same pitch P of two-fold the width (a) in the direction X. Said parts are disposed by deviating the positions of the respective rows by 1/4 pitch from each other in the direction X. Slender slits 28 of the width (a) are punched at a pitch P to a one- dimensional grating plate 29 in the direction intersecting with the direction X. The plate 29 is disposed between the LED20 and the detector 22 and is provided to the movable side object so that the light of the LED20 passing through the slits 28 can irradiated the two rows of the parts 22. The need for the conventional shielding plate is thus eliminated.