| 摘要 |
PURPOSE:To preven laser outputs from being generated excessively at initiation of light emission, by feeding back to an adder circuit a polar signal for inhibiting the laser from light emission instead of an error signal during the period when the semiconductor laser is turned OFF. CONSTITUTION:During the laser-OFF period, or while a laser-ON signal 31 is ''L'', a switch 20 is turned ON such that electric current of negative porarity from a circuit for generating light emission control signal 26 is supplied as a feedback current. Therefore, a laser drive indicating current 31 obtained by adding said feedback current to a bias current 21 is positively held at a value less than a threshold limit value for light emission. The switch is turned OFF upon the laser is ON so that an error signal 13 instead of the inhibiting current is fed back to the adder 8. The feedback current 14 switched in this way provides an effect to lower the bias current 21 at the initiation of light emission by the laser, whereby the outputs can be prevented from being generated excessively just after the light emission. |
