Patent ID: 9699851
Date: 2017-07-04
CPC Classifications: H05B

Claim:
1. A dimming lighting circuit which receives an AC voltage which is phase-controlled, and supplies a light source with a DC current, the dimming lighting circuit comprising: a rectifier circuit which rectifies the AC voltage to output a DC voltage; a phase detection circuit which detects a conduction phase angle of the AC voltage and outputs a dimming signal having a signal level corresponding to the conduction phase angle detected; and a converter which receives the DC voltage output from the rectifier circuit and supplies the light source with a DC current corresponding to a signal level of the dimming signal output from the phase detection circuit, wherein, if the conduction phase angle detected when the dimming lighting circuit receives the AC voltage at power-on is less than or equal to a predetermined angle, the phase detection circuit outputs, as the dimming signal, a substitute signal having a signal level corresponding to a conduction phase angle greater than the conduction phase angle detected, for a predetermined time period after the power-on, and outputs, as the dimming signal, the dimming signal having the signal level corresponding to the conduction phase angle detected, after the predetermined time period.