Patent ID: 7786652
Filing Date: 2010-08-31
Classification: F02M,H01L,Y10T

Abstract:
1. A multi-layer piezoelectric element comprising: a stack having an active portion constituted from at least one piezoelectric layer and a plurality of internal electrodes consisting of the first and the second internal electrodes placed one on another, the active portion being subjected to expansion and contraction in response to a voltage applied across the first internal electrode and the second internal electrode; and external electrodes formed on two side faces of the stack, one of said external electrodes being connected to the first internal electrode and the other of said external electrodes being connected to the second internal electrode, wherein each of the external electrodes has three or more layers including a first layer containing a metal oxide and formed in contact with the side face of the stack, a second layer containing a metal oxide and formed on the first layer, and an outermost layer containing a metal oxide, wherein a content of the metal oxide in the first layer is more than a content of the metal oxide in the second layer, and the content of the metal oxide in the second layer is more than a content of the metal oxide in the outermost layer.