| 摘要 |
PURPOSE:To perform position detection with high precision by detecting optically the position of a moving body, moving in proportion to a process variable, by using optical fibers. CONSTITUTION:Optical fiber 14 having projector 19 and projection window 15 and optical fiber 17 having photodetection wondow 18, photodetector 20 and measuring circuit 21 are provided. Inside of indication piece 11 rotating along the periphery of a measuring instrument, reflective mirror M1 is fitted. Body 12 rotating at a prescribed speed has reflective mirror M0 fitted to both its surfaces. In this constitution, light form projector 19 is reflected by reflective mirror M1 of indication piece 11 and, when reflective mirror M0 opposes to point Z, photodetected by photodetector 20, so that circuit 21 starts counting operation in response to the 1st pulse signal. Rotating body 12 further rotates and reaches indication piece 11 again, thereby stopping the counting operation in response to the 2nd pulse signal. The counting value during this period corresponds to the distance of rotation of indication piece 11. Consequently, the measurement value can immediately be known by bearing the relation between the count value and measurement value previously. |
