| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit for supplying power to a light source including a filter, a transformer, and a controller.SOLUTION: A filter receives and filters an input voltage to provide a stabilized voltage. A transformer converts the stabilized voltage into an output voltage, and supplies power to a light source. A controller generates a drive signal, and alternately operates a switch between a first state and a second state. The controller controls continuous times of the first state and the second state to modify a power factor of the circuit so that an input current reduces to a preliminarily-defined level during the second state and increases from the preliminarily-defined level to a maximum level proportional to the input voltage during the first state. The controller controls a ratio of the time in the first state and the time in the second state to adjust an output current to be flown in the light source to a target level. |
