LASER DIODE DRIVING CIRCUIT, ELECTRONIC CIRCUIT, METHOD FOR CONTROLLING LASER DIODE DRIVING CIRCUIT, AND DUTY CONTROL METHOD

摘要

A laser diode driving circuit comprises a duty control amplifier (23) that controls, in accordance with a duty control signal, the duty ratio of a main signal to be used for a laser control; and an AND gate (22) that outputs a duty control signal to the duty control amplifier (23) and also outputs a duty control signal for controlling, in accordance with a shutdown signal of the laser diode, the duty ratio of the main signal in the duty control amplifier (23) such that it is equal to zero percent. This eliminates a necessity of inputting the main signal, the duty ratio of which has been controlled, to the logic circuit that would operate unstably. Thus, both the output shutdown of the semiconductor laser and the control of the output duty can be stably achieved.