Patent ID: 7936137
Filing Date: 2011-05-03
Classification: H05B,Y02B

Abstract:
1. A control circuit of an inverter which drives an external electrode fluorescent lamp connected to a secondary side of a transformer, the control circuit comprising: a soft start circuit which generates a soft start voltage that changes with time at a starting time of lighting the external electrode fluorescent lamp; a pulse modulator which receives a feedback voltage corresponding to an output voltage of the inverter and the soft start voltage, and generates a pulse signal whose duty ratio is feedback-controlled so that the feedback voltage conforms to the soft start voltage; and a logical control unit which performs switching control of a voltage of a primary coil of the transformer on the basis of the pulse signal from the pulse modulator, wherein the soft start circuit executes at least one striking operation in which the soft start voltage is raised with time, lowered when being reached to a first voltage level, and raised again when being lowered to a second voltage level smaller than the first voltage level.