Takeshi Yano

Internal Electrode Piezoelectric Ceramic Actuator

An internal electrode multilayer piezoelectric ceramic actuator element has been investigated. An individual internal electrode has the same area as the element cross section area. It has no piezoelectric inactive part, so that it shows strain/field characteristics similar to plain piezoelectric ceramics. It can be driven by a relatively low voltage (200 V) and has a semipermanent life under a successive voltage pulse application. Typical properties of the element using 0.65Pb(Mg1/3Nb2/3)O3-0.35PbTiO3 ceramics are 8.7×10-4 strain, over 3.5×107 N/m2 stress and within 100 µsec response time driven by 1×106 V/m field.

Multilayer Piezoelectric Ceramic Actuator with Varying Thickness Layers

A structure for a multilayer piezoelectric ceramic actuator has been studied using finite element method analysis for reducing stresses which are induced at an adhesive layer between the ceramic actuator and a certain body to which the actuator is attached. The stresses are induced by a piezoelectric unstiffened effect (or piezoelectric transverse effect) and they cause mechanical rupture of the adhesive layer. They are successfully reduced for the actuator with both piezoelectric inactive layers and layers which induce a small strain on its top and bottom. It was experimentally confirmed that no mechanical rupture occurs, when adopting an actuator with the improved structure.

Pulse Mode Operation for Piezoelectric Ceramic Actuator

Multilayer piezoelectric ceramic actuators were driven in large amplitude pulse modes by a new charge-discharge circuit with a series inductor. About 56% of the supplied electrical energy was recovered for the mechanically unloaded actuator. About 21% was lost as heat at the actuator. The maximum electro-mechanical energy conversion efficiency for the mechanically loaded actuator was 36%.