| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an LED type lighting system capable of carrying out light modulation control up to 0-100% even when a lighting frequency is high. <P>SOLUTION: Power for lighting an LED load 12 is inputted through an input circuit 11 and a power factor of the power inputted from the input circuit 11 is improved by a power factor improvement circuit 14. A constant-voltage circuit 16 obtains a current supplied to the LED load 12 from the output of the power factor improvement circuit 14. A lighting control circuit 18 determines a light modulation ratio based on a light modulation component identified by an input detection circuit 17, controls the lighting of the LED load 12 by PWM control when the light modulation ratio is higher than a predetermined value, and controls the lighting of the LED load 12 by crest value control when the light modulation ratio is lower than the predetermined value. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
