| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an LED turn-on device which will not have an overcurrent flowing in the LED even when the LED turn-on device and an LED module are temporarily separated while being supplied with power from a commercial power supply and are connected back again. <P>SOLUTION: When an LED module 4 is removed from a connection connector 3 causing the voltage of a smoothing capacitor 15 to exceed a threshold voltage, an overvoltage detection circuit 7 is actuated and a DC-DC converter 6 is thereby stopped operating. At the same time, a transistor 23 turns on, causing a trigger terminal 24a of a timer IC 24 to turn off momentarily, whereby an output terminal 24b of the timer IC 24 is turned on. While in this on state, a transistor 28 turns on, causing a discharge circuit 60 to turn on. Consequently, a thyristor 29 being supplied with power now has its gate voltage gone and thus turns off. <P>COPYRIGHT: (C)2013,JPO&INPIT</p> |
