| 摘要 |
<p>PURPOSE:To decrease the number of sensor signal processing circuits by putting one of optical sensors in operation and processing its signal by one sensor signal processing circuit. CONSTITUTION:A control circuit 1 turns on one transistor TR1 among (n) TRs (n: optional natural number) in a light emitting element turning-on circuit 9 and only one light emitting element PD1 in a light emitting element group 2 illuminates. Consequently, the current generated by one photodetecting element PT1 in a photodetecting element group 3 passes through one diode D1 in a diode group 4 to generate a voltage across a photocurrent detection resistance 5. The voltage is amplified 6 and converted by a voltage comparator 7 into a detection signal indicating whether or not a medium is present and the signal is inputted to one D-FF1 in the D-FF group 8 and latched with the hold signal of the circuit 1. This operation is performed in order as to all the elements PD1 - PDn and then information on the presence/absence state of the medium by all sensors is latched in the D-FF group 8, so the number of sensor signal processing circuits can be decreased.</p> |
