| 摘要 |
PURPOSE:To reduce the size of the device by deriving variation in brightness which occurs during relative movement with an object of measurement as the quantity of light and outputting a pulse signal when signals of a photoelectric converter and a reference signal generator are equivalent to each other. CONSTITUTION:A front end surface 12A is moved one-sidedly opposite a projection image 4A of the object of measurement and crosses an edge of the image 4A, which is then made incident and projected from the other end surface 12B through an optical fiber 12. The projected light is photodetected by the photoelectric converter 14, which outputs an electrical signal (a) corresponding to variation in the quantity of the light to a peak holding circuit 16, thereby outputting the maximum value signal A of the input signal (a) to the reference signal generator 18. Then, a signal 1/2A is outputted to a comparator 22 and compared with the signal (a); when both signals becomes equal to each other, an edge signal generator 20 outputs a pulse (b) to detect the edge of the image 4A. |
