| 摘要 |
<p>An optical encoder which has an offset-adjusting function for bringing DC component levels of outputs of the photodetectors into agreement, which greatly decreases the effect of noise and which is capable of generating correct position signals. A synthesized signal (i10) formed by third current miorror circuits (T17 to T19) that receive output currents (ia11, ia12) from the photodetectors (A11, A12) through first and second current mirror circuits (T11 to T13, T14 to T16) is superposed on the output currents of the two photodetectors as a feedback signal (i10', i10') for removing offset between the DC components of the two output currents. The outputs of the photodetectors from which has been removed the offset of DC components are sent via the first and second current mirror circuits, converted into voltages through resistors (R11, R12) having the same resistance, and applied to a comparator (Cal) where a correct position signal (Pal) is produced.</p> |
