Patent ID: 8860388

Claim:
A driver circuit for driving a capacitive load with a drive pulse having a rise time, a predetermined voltage period and a fall time, the circuit comprising: an input for coupling to a power supply; an inductance having a first electrode coupled to the input via a first charge path including a first switching device, and a second electrode coupled to a first discharge path including a second switching device and to an output of the circuit for selectively charging a capacitive load via a second charge path; a transformer having a primary side coupled between a second discharge path including a third switching device and the output of the circuit for selectively discharging the capacitive load, the transformer further having a secondary side coupled to the first electrode of the inductance; and a controller coupled to the first, second and third switching devices for: enabling the first charge path and the first discharge path so that the inductance is charged from the power supply; disabling the first charge path and the first and second discharge paths so that current flows from the inductance to the output for charging the capacitive load via the second charge path during the drive pulse rise time; enabling the first discharge path at the end of the drive pulse rise time, whereby current flows from the inductance through the first discharge path via the second switching device during the predetermined voltage period of the drive pulse; and enabling the second discharge path during the fall time of the drive pulse so that the capacitive load discharges via the output and the primary side of the transformer, whereby voltage is induced on the secondary side of the transformer and is used to recharge the inductance.