The power supply apparatus is configured to detect the output voltage of a piezoelectric transformer and controls the frequency of a pulse signal to drive the piezoelectric transformer based on the detected output voltage and a preset target voltage so as to perform feedback control of the output voltage of the piezoelectric transformer, the gain when performing the feedback control is switched in accordance with the target voltage.

The present invention is a room temperature superconductor comprising of a wire, which comprises of an insulator core and a metal coating. The metal coating is disposed around the insulator core, and the metal is coating deposited on the core. When a pulsed current is passed through the wire, while the wire is vibrated, room temperature superconductivity is induced.

A piezoelectric sensor with: (i) a capacitive element, comprising piezoelectric material; (ii) a pre-conditioning circuit, comprising circuitry for establishing a polarization of the capacitive element in a polarizing mode; and (iii) signal amplification circuitry for providing a piezoelectric-responsive output signal, in response to charge across the capacitive element in a sensing mode.

A device for generating an atmospheric-pressure plasma is disclosed. In an embodiment the device includes a piezoelectric transformer comprising an input region and an output region, wherein the input region is designed to convert an applied alternating voltage into a mechanical oscillation, wherein the output region is designed to convert a mechanical oscillation into a voltage, and wherein the output region adjoins the input region in a longitudinal direction, a contact element fastened to the piezoelectric transformer, the contact element being designed to apply the alternating voltage to the input region and a holder, wherein the contact element is connected to the holder by a form-fit connection, in such a manner that a movement of the piezoelectric transformer in the longitudinal direction, relative to the holder, is prevented.

A piezoelectric transformer and a method for producing a piezoelectric transformer are disclosed. In an embodiment, the method includes manufacturing a main body having an input region having electrodes and a first piezoelectric material being alternately stacked one on top of the other. An output region includes a second piezoelectric material. The first piezoelectric material is polarized and a removable contact is fitted to an output-side end side of the main body, which end side faces away from the input region. A first electrical potential is applied to the removable contact for polarizing the second piezoelectric material.

An electric circuit for driving an acousto-optic crystal includes a piezoelectric converter configured to drive the acousto-optic crystal to vibrate mechanically. A signaling cable is configured to conduct a first electrical alternating-current signal and a second electrical signal. The electric circuit further includes a first frequency-separating filter and a second frequency-separating filter, each of the frequency-separating filters having an input, a high-frequency output and a low-frequency output. The input of the first frequency-separating filter and the input of the second frequency-separating filter is connected to the signaling cable, and the high-frequency output of the second frequency-separating filter is connected to the piezoelectric converter.

A surface acoustic wave filter includes first and second signal terminals and first and second IDT electrodes that are adjacent to or in a vicinity of each other in an x-axis direction and that each includes a pair of comb-shaped electrodes each including a busbar electrode extending in the x-axis direction and electrode fingers extending in a y-axis direction. One of the comb-shaped electrodes in each of the first and second IDT electrodes is electrically connected to the first and second signal terminals, respectively. The surface acoustic wave filter further includes a bridging capacitance including a pair of comb-shaped electrodes arranged in a region outside an overlap region of the electrode fingers. One of the comb-shaped electrodes of the bridging capacitance is electrically connected to the comb-shaped electrode in the first IDT electrode. The other of the comb-shaped electrodes of the bridging capacitance is electrically connected to the comb-shaped electrode in the second IDT electrode.

An acoustic wave device of the present invention has a piezoelectric substrate, an excitation electrode arranged on the piezoelectric substrate, an electrode pad arranged on the piezoelectric substrate and electrically connected to the excitation electrode, and a cover arranged on the piezoelectric substrate so that a oscillation space is arranged between the cover and the excitation electrode. The cover has inside it a via conductor electrically connected to the electrode pad and is curved so that its surface facing the piezoelectric substrate approaches the excitation electrode side with respect to an upper surface of the piezoelectric substrate from a position of contact with the via conductor.

A method for frequency control of a piezoelectric transformer and a circuit arrangement including a piezoelectric transformer are disclosed. In an embodiment, the method includes exciting a piezoelectric transformer on an input side with an AC voltage of predetermined frequency as input voltage, capturing a phase information for an input impedance of the piezoelectric transformer in a feedback path, evaluating the captured phase information in respect of a predetermined phase criterion, and regulating the frequency of the AC voltage on a basis of the evaluated phase information.

A piezoelectric transformer is disclosed. In an embodiment a piezoelectric transformer includes an input region and an output region, wherein the input region is configured to convert an AC voltage into a mechanical oscillation, wherein the output region is configured to convert a mechanical oscillation into an electrical voltage, wherein the piezoelectric transformer includes a longest edge and a shortest edge, and wherein the longest edge includes a length that is twenty times a length of the shortest edge or less.