OPTICAL POSITION SENSOR

PURPOSE:To perform high precision position detection over a long period by providing a rod light guiding body whose brightness linearly decays and a carrier moved in parallel to the light guiding body so that an output value difference between a light receiver fixed near a light emitter and a light receiver fixed to the carrier can be detected. CONSTITUTION:A rod light guiding body 10 has one end provided with a LED light emitter 9, and in order to make its brightness linearly decay a screen 11 is provided on the bottom of the light guiding body 10 where an optical gradient correcting pattern 11a is printed and a reflecting plane 12 is provided thereunder. A light receiving element 6 connected to an output substrate 18 via a signal line 6a is fixed to the left end 2e integrally formed on a mainframe base 2. On the other hand, a carrier 5 to which a light receiving element 7 is fixed is held in the longitudinal direction of the light guiding body 10 in a movable manner and connected to the output substrate 18 via a movable signal line 7e. The output of the light receiving elements 6, 7 with the movement of the carrier 5 is seized as an output value difference through a comparison circuit to detect the position of a moving body. In this way, high precision position detection is performed even if the LED deteriorates.