| 摘要 |
PROBLEM TO BE SOLVED: To effectively suppress squeaking at PWM light control on light-emitting element drive circuit.SOLUTION: A light-emitting element drive circuit for light control of a plurality of light-emitting elements by a PWM signal, includes a control circuit for generating a control signal, having greater frequency component than an input PWM signal, by having ON periods in both of an ON period and an OFF period on an input PWM signal, and drives a plurality of light-emitting elements by the control signal. The control circuit also generates a divided signal, having narrower pulse widths than a passing PWM signal, which is an input PWM signal passed through as it is, or an inverted PWM signal, which is an inverted signal of the input PWM signal, based on the passing PWM signal or the inverted signal, and a delayed PWM signal, which is either a passing PWM signal or an inverted PWM signal, whose ON period is delayed, generates a synthesized control signal synthesized by periodically switching between either the passing PWM signal or the inverted PWM signal and the divided signal, and generates a control signal composed of either the synthesized control signal or an inverted signal generated by inverting the synthesized control signal. |
