POTENTIOMETER

PURPOSE:To detect the number of rotations other than an angle of rotation, by irradiating a two-dimensional semiconductive light position detector with a ligth spot from the light irradiation means constituted at the center of the cylinder of the two-dimensional semiconductive light position detector to detect the position of said detector. CONSTITUTION:An optical fiber 6, having an opening part at the leading end of the ball screw 4 advancing while rotating on the center axis of cylindrical body 1 operating in conjunction with the rotation of an object to be measured and supporting said object, vertically guides the light from a light source to the semiconductive light position detector 3 provided to the inner wall of the cylindrical body 1. The position of the light spot moves along the circumference of a circle corresponding to the angle of rotation of the object to be measured and displaces in the axis direction corresponding to quantity of rotation to detect an angle of rotation by one shaft of a two-dimensional detector 3. Further, the linear displacement corresponding to the quantity of rotation is detected by the other shaft of said detector 3. Therefore, processing the output of the detector 3 by an operational processing circuit enables calculation of the quantity of rotation and the angle of rotation.