Patent ID: 7518318
Filing Date: 2009-04-14
Classification: H05B,Y02B

Abstract:
1. A circuit for a lamp, comprising: a first sub-circuit for connecting to mains voltage of a predetermined frequency for rectifying the mains voltage and forming a rectified mains voltage having a first frequency; a second sub-circuit connected to the first sub-circuit for providing an alternating current required for the lamp, the alternating current having a second frequency; a control circuit which is connected to the first sub-circuit and the second sub-circuit and which controls the second frequency of the alternating current subject to the first frequency of the mains voltage rectified by the first sub-circuit, the control circuit controlling a first transistor having a first terminal and a second transistor having a second terminal, the first transistor and the second transistor being connected together at a common terminal; a first buffer capacitor connected between the lamp and the first terminal; and a second buffer capacitor connected between the lamp and the second terminal; wherein the second frequency of the alternating current provided by the second sub-circuit is synchronized with the first frequency, and wherein a peak-to-peak value of a voltage signal of the rectified mains voltage having the first frequency depends on a combined capacitance of the first buffer capacitor and the second buffer capacitor.