| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a pulse width modulation (PWM) control method and an apparatus capable of effectively suppressing the generation of noise, and to provide a dimming device. <P>SOLUTION: The PWM control apparatus comprises: a generating section 11 for generating a PWM signal having a duty ratio that can be increased and decreased with a prescribed resolution; a setting section 12 for setting the duty ratio of the PWM signal; a transistor 2 which includes a gate terminal, is turned on/off by applying the PWM signal to the gate terminal and generates a PWM control signal; and a capacitor 5 which reduces a time change rate in the rising and falling of the PWM signal. When a duty ratio high term of the PWM signal is shorter than a rising time of the PWM signal or a duty ratio low term of the PWM signal is shorter than a falling time of the PWM signal, the setting section 12 enlarges the resolution of the duty ratio of the PWM signal to surely carry out the on/off operation of the PWM signal. <P>COPYRIGHT: (C)2009,JPO&INPIT |
