Patent attributes
A discharge lamp lighting circuit includes a power supplying portion having a series resonant circuit including transistors and a bridge driver, a starting portion for applying a high voltage pulse to a discharge lamp to promote a lighting operation, a lighting confirming portion for generating a lighting confirmation signal Sf indicating that a lighting operation for the discharge lamp fails or is successful by the high voltage pulse, and a control portion for generating a control signal Sc to control a driving frequency of the bridge driver. The lighting confirming portion generates a lighting confirmation signal Sf based on a relationship of the magnitude between a lamp voltage equivalent signal VS and a predetermined voltage V4 at a time that a predetermined time Δt passes since the application of the high voltage pulse to the discharge lamp.
