| 摘要 |
PURPOSE:To prevent the overcurrent of a semiconductor laser element by applying sampling and holding in the timing delayed by a prescribed time more than a forced flush signal. CONSTITUTION:After a laser diode 1a is lighted completely, a sampling and holding signal S4 is turned on and sampled, then the possibility of a bias output circuit 19 outputting an excess current to cause an overcurrent to the laser diode 1a is precluded. Since the lighting signal S5 is turned off after a time T1 from the sampling and holding signal S4 and the laser diode 1a is stopped lighting after the end of holding of the sampling and holding section 22, a correct signal voltage is subject to holding.
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