| 摘要 |
PURPOSE:To detect a rotary reference position with high accuracy, by detecting optically an object to be detected and differentiating the detecting signal of the detected object to detect the part corresponding to an edge. CONSTITUTION:For the output signal of a phototransistor 5B of an optical sensor 5, the areas of codes 12 and 13 correspond to black and white tapes 4 and 3 respectively. That is, the output voltage is set at an L level while the white tape 3 is detected and then set at an H level while the black tape 4 is detected. When this signal is transmitted through a differentiation circuit 9A, the pulse signals reverse to each other are obtained at the rise and fall parts of an output signal 12. This pulse signal is compared with a reference level V1 of a comparator 9C and then amplified with inversion. Thus an output signal 14 is generated at an output terminal 11 and then turned into a rotary reference position signal V0. In such a way, a detecting signal is differentiated to detect the edge part of a black tape. Thus it is possible to detect a rotary reference position with high accuracy. |
