Patent ID: 7688006

Claim:
A fluorescent lamp ballast adapted for effecting stepless dimming with a regular SCR dimmer, comprising a filter and rectifier circuit ( 1 ); a DC high voltage stabilizing circuit ( 2 ) coupled with the filter and rectifier circuit ( 1 ); a voltage signal detection and frequency control circuit ( 6 ) coupled with the DC high voltage stabilizing circuit ( 2 ); a lamp load ( 4 ) coupled with the voltage signal detection and frequency control circuit ( 6 ); and a lamp current feedback circuit ( 5 ) coupled between the lamp load ( 4 ) and the voltage signal detection and frequency control circuit ( 6 ); characterized in that the fluorescent lamp ballast further comprises a voltage signal sampling circuit ( 3 ) coupled between the filter and rectifier circuit ( 1 ) and the voltage signal detection and frequency control circuit ( 6 ), which is configured to detect and convert a variation in phase conduction angle of the SCR dimmer, so as to correspondingly change output of the voltage signal detection and frequency control circuit ( 6 ) or working current and power factor of the lamp load ( 4 ).