| 摘要 |
PURPOSE:To make it possible to perform highly accurate position detection in a broad detection range, by providing at least two slits, and determining the position of a material to be detected by using a detected signal, a scanning signal, and slit position signals. CONSTITUTION:Based on the signal from a driving circuit 22, a light shielding plate 16 shields a slit 15b. A scanning signal is outputted from a driving circuit 21 to a galvanomirror 14. Based on the difference between the amount of reflected light from a surface to be detected 10 and the amount of reflected light from the other surface of a material to be detected, the reflected light from the material to be detected passes a slit 15a. The change in an output level of a photoelectric transducer 17 is read by a comparator circuit 19, and a sampling signal is imparted to a circuit 20. At this time, based on the scanning signal for the galvanomirror 14 from the driving circuit 21 and the position signal of the slit 15a from the driving circuit 22, the position of the material to be detected is computed by an operating circuit 23. The value is read by the sampling circuit 20 and outputted. As a result, the broad scanning range can be obtained without enlarging the maximum rotary angle of the galvanomirror. Thus, the highly accurate position detection can be performed. |
