A piezo-electric device has a base including a cavity opened on a first surface of the base, a first electrode layer formed on a second surface of the base, a piezo-electric layer laminated on the first electrode layer, and an auxiliary electrode layer formed on the second surface of the base. Between...http://www.google.com/patents/US6921160?utm_source=gb-gplus-sharePatent US6921160 - Piezo-electric device and ink cartridge having the same
