| 摘要 |
<p>PURPOSE:To improve of a detection speed by executing read-in of a low level signal at the time of non-light emission of a photodetecting output signal after read-in of a high level signal at the time of light emission to a storage device. CONSTITUTION:When a switch 15a goes to ON by an analog switch 15a driving pulse and a current is connected to a photodetector 12a, an impulsive noise caused by a transient current is generated, but a switch 15b goes to ON and a light emitting element 11a goes to ON and a light beam is emitted for a prescribed time by an analog switch 15b driving pulse without waiting until the noise is attenuated enough. As a result, a photodetecting output signal 18 is superposed on the noise and generates a photodetecting output of a high level, therefore, during this time, by a high level signal read-in pulse, a high level signal is read in a storage device. Also, when a driving pulse of the switch 15b is disconnected and the light emission is stopped, the photodetector 12a returns to a stationary state, and before the driving pulse of the switch 15a is disconnected, a low level signal can be read in the storage device by a low level signal read-in pulse.</p> |
