Nec Corporation

Kaneo Uehara

Yasuhiro Sasaki

Takeshi Inoue

Atsushi Ochi

Osamu Ohnishi

Yoshiki Inoue

Akio Iwamoto

A piezoelectric ceramic transformer includes a high impedance portion having internal electrode layers which are opposite each other in a thickness direction in a radial central portion of a piezoelectric ceramic disc; an annular insulating portion disposed externally of the high impedance portion and having no electrode; and a low impedance portion disposed externally of the annular insulating portion and having annular internal electrode layers which are opposite each other in a thickness direction, the internal electrode layers of the high impedance portion being exposed on the side end face of the piezoelectric ceramic disc at respective ends thereof without being in contact with the annular internal electrode layer of the low impedance portion and being alternately connected on the side end face with external electrodes, each of which is connected with an electric terminal, and the internal electrode layers of the low impedance portion being exposed on the side end face of the piezoelectric ceramic disc at respective ends thereof and being alternately connected on the side end face with external electrodes, each of which is connected with an electric terminal. The transformer is operable in a high frequency band and can be used for an onboard power supply.

Piezoelectric ceramic transformer

A piezoelectric ceramic transformer comprises a low impedance portion 11 including a plurality of piezoelectric ceramic layers 111 to 115 having different thicknesses, a high impedance portion 12 and internal electrodes 16. The low and high impedance portions 11 and 12 are subjected to a uniform polarization treatment in a thickness direction and with the same vector of polarization. The low impedance portion 11 includes one or more piezoelectric ceramic layers having a thickness different from those of the other layers therein. No delamination of electrodes or breaking of ceramics occur upon polarization treatment. Therefore, a compact piezoelectric ceramic transformer for power source which has a high mechanical quality coefficient Qm and a high electric power transmission efficiency is provided.

Piezoelectric ceramic transformer being driven with thickness

In a piezoelectric actuator of the type which has a plurality of grooves on the outer side surface of the actuator body, mechanical reliability of the actuator is enhanced by providing grooves also in the respective layers of a material exhibiting electrostrictive effect located over and below the top and the bottom ends of the actuator. Moreover, a further improvement of mechanical strength can be attained by providing additional grooves onto the outer most grooves.

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Tokyo, Japan

Kaneo Uehara