| 摘要 |
PROBLEM TO BE SOLVED: To provide a light emitting element driving circuit for shortening the rise response delay time at the transition of a light emitting element from a quenched state to a light emitting state without requiring complicated feedback control and increasing a bias current and capable of removing damage due to the influence of a drooping phenomenon. SOLUTION: A circuit constituted of connecting a coil 55 and a resistor 54 in series is connected to an LD 53 in parallel. In the constitution, a drive current ILD which is overshot only in a period determined by the time constants of the coil 55 and the resistor 54, i.e. a period that a high frequency current is allowed to flow at the transition from the quenched state to the light emitting state, is allowed to flow into the LD 53. Thereby the delay of rise time up to the light emission of the LD 53 can be shortened. The drive current ILD allowed to flow into the LD 53 is increased in proportion with the drop of the forward voltage Vop of the LD 53 following temperature rise. Even when the light emitting state is continued for a long period, the emitted light quantity of the LD 53 can be held at a fixed value. COPYRIGHT: (C)2004,JPO
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