Patent ID: 7746004

Claim:
A discharge-lamp lighting apparatus comprising: a first series circuit connected to each end of a DC power source and including a high-side first p-type FET and a low-side first n-type FET that are connected in series; a second series circuit connected to each end of the DC power source and including a high-side second p-type FET and a low-side second n-type FET that are connected in series; a transformer having a primary winding and a secondary winding, a series circuit of the primary winding and a capacitor being connected between a connection point of the first p- and n-type FETs and a connection point of the second p- and n-type FETs, and the secondary winding being connected to a discharge lamp; a control circuit configured to alternately turn on/off the first p-type FET and second n-type FET and the first n-type FET and second p-type FET by providing the FETs with control signals according to a lamp current passed through the discharge lamp; and a first drive circuit configured to drive the first p-type FET and a second drive circuit configured to drive the second p-type FET, each of the first and second drive circuits including: a first switch element configured to discharge a gate-source capacitance of the corresponding p-type FET as being turned on and thereby turn off the p-type FET; a resistance element having one end connected to the DC power source, configured to determine the potential of a control terminal of the first switch element as the first switch element is turned on; a second switch element configured to charge the gate-source capacitance of the corresponding p-type FET as being turned on and thereby turn on said corresponding p-type FET; a constant current circuit connected in series with the resistance element; and a switch connected in series with the series circuit of the constant current circuit and resistance element, configured to turn on/off the constant current circuit under the control of the control circuit.