| 摘要 |
A driving circuit comprises: a constant-current source which supplies a current to a photodiode so as to forward-bias the photodiode; detecting means for detecting the forward voltage of the photodiode; determining means for determining whether or not the forward voltage detected by the detecting means is smaller than a predetermined reference voltage; and control means for controlling the supply of current from a current source to a laser diode, wherein when the determining means determines that the forward voltage is smaller than the predetermined reference voltage, the control means controls the current source so as to stop the supply of current to the laser diode.
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