Patent ID: 8754584

Claim:
A silicon-controlled rectifier (SCR) dimming circuit, comprising: a) an SCR rectifying circuit having an SCR element configured to receive an AC power supply, and to generate a lack-phase AC voltage; b) a rectifier bridge configured to convert said lack-phase AC voltage to a lack-phase DC voltage that is configured to be filtered through a filter capacitor to generate a smooth DC voltage; c) a conduction phase angle signal generator configured to receive said lack-phase DC voltage, and to generate a controlling signal that indicates a conduction phase angle range of said SCR element; and d) a dimming signal generator configured to compare said controlling signal and a slope reference signal, and to output a dimming signal, said dimming signal generator having a dimming phase angle range from a predetermined start-up phase angle to a cut-off phase angle, wherein said cut-off phase angle is determined by said filter capacitor and said AC power supply, and wherein said slope reference signal is configured to indicate an average value at each phase angle of said AC power supply in a half cycle having a first reference corresponding to said start-up phase angle and a second reference corresponding to said cut-off phase angle.