| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To improve the efficiency in controlling light, and at the same time fundamentally prevent the generation of sounds by an output capacitor. <P>SOLUTION: A voltage boosting chopper circuit 1 is provided for supplying an output voltage Vo, which is generated in an output capacitor 5 by operation of switching a main switching element 3, to an LED train 7. In the invention, there are particularly provided a diode 32 serving as a light control circuit for intermittently stopping the switching operation of the main switching element 3 in synchronizing to a pulse light-control signal S controlled in PWM, a switch element 11 connected in series with the output capacitor 5, and a negative voltage generation circuit 21 for blocking electric discharge from the output capacitor 5 by turning off the switch element 11 while the switching operation of the main switching element 3 is stopped. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
