Denso Corporation

Hiroaki Asano

Yoichi Kobane

Hidekazu Hattori

Shinichi Okamoto

Satoshi Suzuki

Akira Fujii

Akio Iwase

Shige Kadotani

Atsushi Murai

Kouji Noda

Toshiatu Nagaya

A stacked piezoelectric deviceincluding a ceramic laminate formed by laminating piezoelectric ceramic layers and inner electrode layers alternately and a pair of side electrodes. The inner electrode layersandhave inner electrode portionsandand the recessed portionsand. The ceramic laminatehas the stress absorbing portionsand. A recessed distance of one of two of the recessed portionsandwhich interleave the stress absorbing portionsandtherebetween which is located on the same side surface as the stress absorbing portionoris greater than the depth of the stress absorbing portionand

Stacked piezoelectric device

A laminated piezoelectric element according to the present invention includes a plurality of unit laminates and a plurality of adhesive layers. The unit laminates are stacked together. Each of the unit laminates includes a plurality of piezoelectric ceramic layers and a plurality of internal electrode layers that are alternately laminated with the piezoelectric ceramic layers in the lamination direction of the unit laminate. Each of the adhesive layers is formed between adjacent two of the unit laminates to bond the two unit laminates together. Further, each of the adhesive layers has a thickness of 1 &#x3bc;m or less and an adhesive strength of 1.3 MPa or higher.

Laminated piezoelectric element including adhesive layers having small thickness and high adhesive strength

A laminated-type piezoelectric elementis provided, which comprises a first external electrode layer, which is located at a side area of the laminated-type piezoelectric element, is electrically continuous to internal electrode layers, and comprises plural expansible and contractible opening portionsin a stacking direction of the laminated-type piezoelectric element. As the first external electrode layeris connected to the laminated-type piezoelectric elementwith an electrically conductive adhesive memberand the electrically conductive adhesive memberis narrower than the first external electrode layer, the electrically conductive adhesive memberpenetrates into the opening portionsof the first external electrode layerto form connections in a shape of an anchor. Therefore, the first external electrode layeris firmly connected to the laminated-type piezoelectric element

Laminated-type piezoelectric element

A multilayer piezoelectric element has a pair of outer electrodes and a multilayer ceramic body composed of piezoelectric layers and inner electrode layers which are alternately stacked. The outer electrodes are formed on a pair of electrode connecting surfaces in the outer circumference surfaces of the multilayer ceramic body. Each outer electrode electrically connected to the inner electrode layers through connecting material is composed of a fixed part, a free part having plural expandable-openings, and a rigid part. The fixed part is electrically contacted with the connection material. A sectional area of the rigid part is rather than that of each of the fixed part and the free part in a width direction of the outer electrode. Each outer electrode has at least one part where the fixed part, the free part and the rigid part are arranged in order in the width direction.

Multilayer piezoelectric element

The present invention provides a piezoelectric actuator with excellent durability. In the present invention, a piezoelectric elementin which a plurality of piezoelectric layers that expand in accordance with an applied voltage, and internal electrode layers for supplying an applied voltage, are alternately laminated, and at least a part of the side surfacesandthereof is covered by an external packaging resin, the piezoelectric elementbeing housed in a sealed containerthat substantially isolates it from the external atmosphere, and in which the internal atmosphereis replaced by an inert gas. Alternatively, the piezoelectric elementis housed in a sealed containerthat substantially isolates it from the external atmosphere, and the external packaging resinincludes an antioxidant.

Piezoelectric actuator

A laminated piezoelectric element () comprises a laminated piezoelectric element () piezoelectric layers () composed of a ceramic capable of expanding and contracting upon application of a voltage, and internal electrode layers (and) that supply voltage to the piezoelectric layers, the internal electrode layers and piezoelectric layers being alternately provided, a first external electrode layer () provided on a side of the laminated piezoelectric element () and electrically connected with the internal electrode layers (and), and a second external electrode layer () provided on a side of the laminated piezoelectric element () and electrically connected with the internal electrode layers (and) via the first ecternal electrode layer wherein there are specific external electrode width relationships.

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Kuwana, Japan

Hiroaki Asano