| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power unit capable of suppressing flashing in re-lighting.SOLUTION: An MOSFETQ1 turns OFF in response to a turn-off of a commercial power source AC at a point t5 of time. At a point t6 of time after the turn-off of the commercial power source AC, an LED current detection voltage Vis lower than a target value V1. At a point t61 of time after the point t6 of time, the target value V1 is 0 equally to the LED current detection voltage Vas a charging/discharging circuit 3 is discharged. At a point t71 of time after the point t61 of time, an ON time detection voltage Vbecomes lower than a cutoff voltage Vx. When the commercial power source AC turns off after turning off, a start of switching of the MOSFETQ1 is delayed behind the point t71 of time. Even if the commercial power source AC turns ON, a dimming control IC 60 does not start charging of the charging/discharging circuit 3, i.e. switching of a transistor Q2 until a predetermined wait time Tw passes after the point t5 of time when the commercial power source AC turns OFF.SELECTED DRAWING: Figure 5 |
