| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a lighting device which can prevent decrease of power factor at the time of deep dimming. <P>SOLUTION: In this lighting device, a rectified voltage detector 300 is connected to an output side of a rectification circuit 200 which rectifies the entire wave of an AC power, and a power factor improvement circuit 400 having a step-up converter control part 440 is connected to an output side of the rectified voltage detector 300. The output power thereof is supplied to a light source lighting part 500 to light up a light emission diode 910. Dimming determination means 700 controls the light source lighting part 500 to dim and light a light source of load according to an output signal converted from a dimming signal input from the dimming signal input part 600. When a dimming signal of deep dimming level is input to the dimming determination means 700, a voltage determination part 800 connected to the rectified voltage detector 300 generates a driving signal to set a prescribed operation stop period over a zero cross point of the AC power 100, outputs the driving signal to a step-up converter control part 440 to control the power factor improvement circuit 400, thereby preventing decrease of power factor. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
