A circuit assembly is used for controlling a piezoelectric transformer having an input capacitance in a first circuit branch. The circuit assembly also includes a second circuit branch for compensating for the input capacitance, preferably by means of a capacitive element, and a differential amplifier having two inputs. The first input is coupled to the first circuit branch and the second input is coupled to the second circuit branch.

A power supply apparatus with a plurality of power supply circuits each having a piezoelectric transformer and a voltage-controlled oscillator which generates a signal at an operating frequency used to drive the piezoelectric transformer in accordance with a control signal, includes a frequency-dividing circuit which divides the operating frequency generated by a voltage-controlled oscillator in at least one power supply circuit, and outputs a signal at a driving frequency to drive a piezoelectric transformer in the one power supply circuit. When at least one power supply circuit and remaining power supply circuits output voltages, the operating frequency generated by the voltage-controlled oscillator in the one power supply circuit is controlled to be higher than the operating frequency generated by the voltage-controlled oscillator in another power supply circuit.

A drive signal generating apparatus includes a transducer configured to convert electromagnetic energy of a signal received through a first port into a different type of energy, convert the different type of energy into electromagnetic energy, and transfer the converted electromagnetic energy to a second port, and a switching circuit configured to perform a gate switching operation, upon receiving a signal from the second port, to generate a drive signal.

A method and apparatus for converting power comprising an input bridge having an input adapted for coupling to a DC source, a piezoelectric transformer having an input coupled to an output of the input bridge, and an output bridge having an input coupled to an output of the piezoelectric transformer and an output adapted to couple to a load. A trajectory controller, coupled to the input bridge and output bridge, (1) measures current and voltage in the input bridge, the output bridge or both, (2) measures a current into or out of the piezoelectric transformer, (3) determines switch timing for control signals for the input bridge and output bridge based upon the measured current and/or voltage, and (4) applies the control signals to the input bridge and output bridge.

A direct current (DC)-alternating current (AC) power convertor is disclosed. The DC-AC power converting circuit may include an inverter configured to convert the DC power into first output power, a piezoelectric transforming unit including piezoelectric transformers connected in parallel to an output terminal of the inverter, and each piezoelectric transformer of the piezoelectric transformers configured to transform the first output power to second output power, and an output configured to add the second output power output from the each of the piezoelectric transformer and to output AC power, wherein each piezoelectric transformer has a resonance frequency.

The present disclosure relates to circuitry for driving a piezoelectric transducer. The circuitry may be implemented as an integrated circuit and comprises driver circuitry configured to supply a drive signal to cause the transducer to generate an output signal and active inductor circuitry configured to be coupled with the piezoelectric transducer. The active inductor circuitry may be tuneable to adjust a frequency characteristic of the output signal.

Provided are a driver unit of a headphone, in which, in a case where a driver unit including a piezoelectric film having a formed curved portion is applied to the headphone, deformation of the curved portion of the piezoelectric film in a case of wearing the headphone can be suppressed, and deterioration in sound quality can be suppressed; and a headphone. The driver unit includes a piezoelectric film which has a piezoelectric layer consisting of a polymer-based piezoelectric composite material containing piezoelectric particles in a matrix containing a polymer material and electrode layers provided on both surfaces of the piezoelectric layer, and a perforated plate having at least one through-hole, in which the piezoelectric film has a curved portion which is formed to protrude to one main surface side and to be recessed to the other main surface side, the perforated plate is laminated on a concave surface side of the curved portion of the piezoelectric film, and in the through-hole, a first air chamber defined by the concave surface of the piezoelectric film and the perforated plate communicates with an outside.