Patent ID: 7633769

Claim:
A DC-AC converter comprising: a transformer having a primary winding with a center tap, and at least one secondary winding, in which the center tap is connected to a first potential point of a DC power source; a first semiconductor switch which is connected between one end of the primary winding and a second potential point of the DC power source and causes an electric current to flow through the primary winding in a first direction; a second semiconductor switch which is connected between the other end of the primary winding and the second potential point and causes an electric current to flow through the primary winding in a second direction; a first capacitor and a third semiconductor switch, which are connected in series between the other end of the primary winding and the center tap; a second capacitor and a fourth semiconductor switch, which are connected in series between the one end of the primary winding and the center tap; a current detection circuit to be used for detecting an electric current which flows into a load connected to the secondary winding; a logic circuit to be used for outputting a switch drive signal and which produces, on the basis of the electric current flowing through the load, a first switch drive signal to be used for turning on the first semiconductor switch, a second switch drive signal to be used for turning on the second semiconductor switch, a third switch drive signal to be used for turning on the third semiconductor switch, and a fourth switch drive signal to be used for turning on the fourth semiconductor switch; and a third capacitor which is connected to one end of the secondary winding, and a cold cathode fluorescent lamp which is connected to said one end of the secondary winding, wherein the first through fourth switch drive signals are produced at timings of an off-state period where the first though fourth semiconductor switches are turned off, said timings being produced during interval periods such that a first semiconductor switch group, comprising the first semiconductor switch and the third semiconductor switch, and a second semiconductor switch group, comprising the second semiconductor switch and the fourth semiconductor switch, are alternately made on-state synchronously with triangular wave signals of the triangular wave signal train.