| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an LED power supply device that maintains the time elapsed until an LED light is turned off constant when a switch of a commercial power supply is turned off. <P>SOLUTION: An LED power supply device 101 includes: a DC-DC converter 120 that inputs a DC voltage from a rectification circuit 110, and outputs the DC voltage by converting the magnitude thereof; a smoothing capacitor 130, whose one end is connected to a positive electrode of an output and the other end is connected to a negative electrode thereof, which is configured to smooth the DC voltage outputted by the DC-DC converter 120 and apply the smoothed DC voltage to an LED unit 200; a bypass circuit 150 which is connected in parallel to the LED unit 200, and is configured to run therein a current that should run in the LED unit 200 when a transistor Q3 is turned on upon receipt of a control, irrespective of the presence or absence of the connection of the LED unit 200; and a turn-off detection circuit 140-1 which monitors the operation of the DC-DC converter 120 and, upon detection of an operation stop, performs control in order to turn on the transistor Q3 of the bypass circuit 150. <P>COPYRIGHT: (C)2013,JPO&INPIT |
