Patent ID: 8727471

Claim:
A fluid ejection system, comprising: a substrate having a chamber formed therein; a membrane that forms a wall of the chamber and is operable to expand or contract the chamber by flexing; and an actuator supported on the membrane, the actuator comprising: a piezoelectric layer disposed between a drive electrode layer and a reference electrode layer, wherein: the piezoelectric layer comprises a continuous planar piezoelectric material spanning the chamber and having a uniform poling direction substantially perpendicular to the continuous planar piezoelectric material; the drive electrode layer comprises a plurality of drive electrodes, the plurality of drive electrodes including an inner electrode and an outer electrode surrounding the inner electrode; and the reference electrode layer comprises a reference electrode, the reference electrode having a first portion spanning the inner electrode and a second portion spanning the outer electrode, where creation of a voltage differential between at least one of the plurality of drive electrodes and the reference electrode generates an electric field in the continuous planar piezoelectric material, and the electric field results in actuation of the continuous planar piezoelectric material to flex the membrane, wherein the membrane has a lateral dimension of D, and the inner electrode has lateral dimension of approximately ⅔ of D, and wherein the outer electrode is in a shape of a ring, the ring has an inner lateral dimension and an outer lateral dimension, and the inner lateral dimension of the ring is greater than the lateral dimension of the inner electrode.