US Patent 7880515 Driving circuit for capacitive load and fluid injecting device

A driving circuit that drives a capacitive load includes a drive signal generator that generates a drive signal driving the capacitive load via a transistor pair in response to an analog signal, and a power-source voltage generator that generates a high-voltage power-source voltage and a low-voltage power-source voltage and that supplies the high-voltage power-source voltage and the low-voltage power-source voltage respectively to collectors of the transistors of the transistor pair via a high-voltage output terminal and a low-voltage output terminal. The power-source voltage generator includes multiple power sources connected in parallel, a backcurrent prevention diode connected between the adjacent power sources, and a switch unit that connects the adjacent power sources in series under the on-off control of a controller each time the drive signal rises above a predetermined threshold value or falls below a predetermined threshold value.