| 摘要 |
PURPOSE:To lessen the overshoot of a current given to a light emitting element so as to protect the light emitting element against damage or to prevent it in deteriorating in service life by a method wherein a part of a current is bypassed when the current given to the control electrode common connection point of a first and a second transistor is made to increase sharply. CONSTITUTION:The output state of an input circuit 2 becomes high in impedance, and transistors Q1 and Q2 and an LD 8 are turned ON. When the LD 8 is in a transient state that it changes from an OFF state to an ON state, a part of a transient current I0 fed to the base of a transistor Q3 from a high potential power supply 3 through the intermediary of a constant current source 5 is bypassed as a charging current Ip for a capacitor C1. |
