Tdk Corporation

Syuuzi Itoh

Kazuo Mochizuki

Satoshi Ozawa

Hiroshi Hatanaka

Kenji Horino

Masahito Furukawa

Makoto Morita

Haruo Taguchi

Minami Kudoh

An element body having a first and second internal electrodes exposure surface comprising a piezoelectric active area, wherein a first internal electrode faces a second internal electrode sandwiching piezoelectric body layer in-between along laminating direction, and a piezoelectric inactive area, wherein the piezoelectric body layer contacts only first or second internal electrode at one face along laminating direction, or the first internal electrodes or the second internal electrodes respectively face each other sandwiching piezoelectric body layer in-between along laminating direction, an insulating layer which covers the piezoelectric active area of the first and second internal electrodes exposure surface, and a resistance layer which is isolated from the piezoelectric active area by the insulating layer, placed at the first and second internal electrodes exposure surface connecting at least a part of the first and that of the second internal electrode in the piezoelectric inactive area and has lower electrical resistance value relative to that of the piezoelectric body layer.

Multilayer piezoelectric element

A laminated piezoelectric device comprising a device bodyon which a number of piezoelectric layersand internal electrodesare laminated, external electrodeselectrically connected to the internal electrodesand formed on the surface of the device body, an insulation layerand a resistance layer. The insulation layercovers at least a portion wherein internal electrodesare exposed on the surface of the device body, where mechanical displacement is generated by applying voltage. The resistance layeris formed to connect between external electrodesand has a lower electric resistance value than the insulation layer

Laminated piezoelectric actuator

A multilayer piezoelectric element is provided with a multilayer body, a first external electrode on a side face of the multilayer body, and a second external electrode outside the first external electrode. The multilayer body consists of an alternate stack of a plurality of piezoelectric members and a plurality of internal electrodes. The first external electrode is electrically connected to predetermined internal electrodes. The second external electrode extends in a wave pattern along a stack direction of the multilayer body and is of flat plate shape. The first external electrode and the second external electrode are electrically and physically connected through a plurality of connections.

Provided is a multilayer piezoelectric device high in reliability and easy in formation of a unit when incorporated into various devices. In a multilayer piezoelectric device, each second external electrode is integrally formed including a main body part electrically and physically connected to a first external electrode, and an extending part having an upper end projecting with respect to an upper face of laminate in a stack direction. This permits the extending part of the second external electrode to be used as a terminal, and, because the second external electrode is integrally formed, the second external electrode can be prevented from breaking. Therefore, it results in improving the reliability of piezoelectric device. Furthermore, between second external electrodes facing each other, a distance between extending parts is larger than a distance between main body parts, and thus it becomes easy to form a unit of the piezoelectric device when incorporated in various devices; e.g., a plate for application of a preload is placed on the upper face of the laminate.

Multilayer piezoelectric device

An electronic part comprises a main part, a terminal electrode, and a film. The main part includes a sintered piezoelectric ceramic element, wherein a plurality of internal electrode layers and piezoelectric layers are alternately stacked. The terminal electrode is provided at an edge of the sintered piezoelectric ceramic element and electrically conducting to the internal electrodes. The film is provided on a surface of the sintered piezoelectric ceramic element and the exposed internal electrodes, and is made of a glass insulating material.

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Tokyo, Japan

Syuuzi Itoh