| 摘要 |
PURPOSE:To improve reliability of a cable by detecting the arbitrary position of a movable element by partly interrupting an incident light to a phototransistor array in an image sensor by a sensor yoke when the yoke longitudinally moves through a gap between a light emitting source and a lens without contact. CONSTITUTION:A light emitting source LED 12 emits a light to a chip 11 through an optically focusing fiber lens 13. The chip 11, the lens 13 and the LED 12 are so disposed longitudinally as to cover the operating stroke of a movable element 3. A sensor yoke 7 longitudinally moving together with the element 3 and having a predetermined width is so disposed as to partly interrupt the LED 12 and the optical axis of the lens 13, and the light to the chip 1 is interrupted at a place where the yoke 7 exists. Thus, the arbitrary absolute position of the element 3 is detected. In this manner, improvement of the reliability of a cable for long stroke motion, high speed motion of the element 3, highly frequent reciprocation are achieved. |
