DIMMING DEVICE OF LIGHT-EMITTING DIODE

PROBLEM TO BE SOLVED: To provide a dimming device of an LED capable of controlling an LED load at low loss with an alternating-current power source, and that, capable of avoiding dimming mistakes. SOLUTION: With the LED dimming device, a control circuit 7 changes a phase of a trigger point t10 by a phase control signal FC11 as a trigger signal outputted to a photo triac coupler 3 in a variable range R11 narrower than a half cycle of the alternating-current voltage SV. With this, the control circuit 7 can avoid outputting a trigger signal into the photo triac coupler 3 in the vicinity of a zero cross point of the alternating-current voltage SV out of the half cycle of the alternating-current voltage SV. Thus, a phenomenon that the LED does not at all light itself can be avoided despite a setting of light dimming near an upper limit. COPYRIGHT: (C)2009,JPO&INPIT