| 摘要 |
PURPOSE:To reduce effort required for matching a plurality of processing systems by a method where a signal which has been amplified and output earlier in a time- series manner is stored, another signal is then generated by a time-series formation means, both signals are operated and distance information is detected. CONSTITUTION:An operation amplifier MA converts output currents of photodetectors SPC1, SPC2 into voltages. A preamplifier PA receives a signal whose DC portion has been cut at a noninverting input terminal, and it amplifies the signal. The potential of the output of an operational amplifier INT which integrates the output of the PA becomes nearly equal to the threshold voltage of an operational amplifier CP3. As a result, the terminal voltage of a capacitor C3 becomes a difference voltage between the potential of the inverted input terminal of the INT and the potential of the noninverting input terminal. As a result, the offset voltage of the INT and of the CP 3 can be compensated automatically, and the output level in a signalless state of the INT is set to a reference level or lower. At this time, when the output of the INT is swung to only the positive direction with reference to the output level in the signalless state, the dynamic range of the output of the INT is expanded, and an S/N ratio is enhanced. |
