| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an LED lighting that can slow a rising speed of the LED lighting to create comfort without giving discomfort like a flash lamp. <P>SOLUTION: A DC power supply for supplying a load current to an LED via a smoothing capacitor C<SB POS="POST">3</SB>connected therewith in parallel by full-wave rectifying an AC current comprises: a conversion circuit 2 for converting the full-wave rectified current into a DC current with a switching element Q<SB POS="POST">1</SB>turned on/off; a detector R<SB POS="POST">4</SB>for detecting the value of the load current; and a control circuit 4 for controlling the switching element Q<SB POS="POST">1</SB>. The control circuit 4 changes its target value in n steps corresponding to the current values of zero to full light emission where the target value is increased step by step for each of n divided periods in a predetermined time between 0.1 and 1.0 second. The value of the load current is compared with the target value in each divided period to correct on-duration of the switching element. Drive of the switching element depending on the corrected on-duration increases the load current of the LED in a predetermined time. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
