Patent attributes
A lighting circuit includes a DC/DC converting circuit for boosting an input DC voltage so as to produce boosted DC power, a detecting circuit for producing a detection signal in response to the output voltage of the DC/DC converting circuit, a DC/AC converting circuit for producing AC power to be supplied to the discharge tube from the boosted DC power, a starting circuit for starting up the discharge tube, and a control circuit for receiving the detection signal from the detecting circuit. The control circuit contains a capacitor which is charged based upon the detection signal, a first discharging unit for discharging the capacitor, a second discharging unit for providing a discharging path for the capacitor in response to turning-OFF of the input DC voltage, and a signal producing unit for producing a control signal used to adjust the output of the DC/DC converting circuit in response to a terminal voltage of the capacitor.
