Patent ID: 8400079
Filing Date: 2013-03-19
Classification: H05B,Y02B

Abstract:
1. An LED drive circuit in which an alternating voltage from a phase control dimmer is input and an LED is driven; the LED drive circuit comprising: a phase angle detector for detecting the phase angle at which a phase control element inside said phase control dimmer switches from off to on; a switching power supply for feeding a current to said LED; a switching element connected in series to said LED; and a controller for controlling said switching power supply and said switching element in accordance with the output of said phase angle detector; wherein said controller places said switching element in an always-on state in a case in which the phase angle detected by said phase angle detector is equal to or less than a predetermined value, and said controller pulse-drives said switching element in a case in which the phase angle detected by said phase angle detector is greater than said predetermined value.