| 摘要 |
PURPOSE:To detect the position of the origin with ease and high sensitivity by a constitution wherein a pair of lamps and photosensors arranged oppositely on optical axes are provided at a fixed or movable member and an index for intercepting a light is provided between the lamps and photosensors. CONSTITUTION:A pair of lamps 13 and 14 are fixed to a fixed member 11 at an interval in the direction (shown by an arrow) of the movement of a movable member 12, while a pair of photosensors 15 and 16 are fixed oppositely on optical axes respectively. A scale 17 is fixed at a right angle to optical paths. On the othr hand, an index 18 is fixed to the movable member 12, and when the movable member 12 is moved to and positioned at the position of the origin, the lights of the lamps 13 and 14 pass through light-transmitting windows 19 and 20 and reach the photosensors 15 and 16. The light-transmitting windows 19 and 20 are formed in such a manner that they are deviated somewhat outward from the optical axes, and when the movable member 12 is moved upward, an incident light in the photosensor 15 is intercepted and an output of the sensor 15 decreases. When the member 12 is moved downward, the output of the photosensor 16 decreases. Accordingly, the position of the origin is detected with ease and high sensitivity. |
