| 摘要 |
PURPOSE:To obtain high resolution by a method wherein detection signals which have phase lags each other by a specified angle are provided and the original signal is divided by those signals to be made into one group and the phses of a plurality of such groups are lagged and the original divisions are again finely divided by those signal groups. CONSTITUTION:Groups of phot-couplers G1 and G2 are provided by the phase difference of 45 deg.. A rotary slitted plate 10 and fixed slitted plates 12 and 13 are positioned between photo-diodes and LEDs of the photo-couplers. The photo- diodes d1-d3 and d11-d13 have phase-lags of 90 deg. each other. The adjacent output signals of the photo-diodes d1-d3 and d11-d13 which detect the lights from the LEDs D1-D3 and D11-D13 are compared with each other by comparator-amplifiers 20-1, 20-2, 30-1 and 30-2 and cross-points of the respetive signals are detected by edge-trigger pulse generators 21-1, 21-2, 31-1 and 31-2. The output signals are then accumulated via an OR-circuit being added or subtracted by a counter 23 according to the output of a direction identifying circuit 24. As the pulse period is finely divided by phase-shifting, high resolution can be obtained. |
