A liquid charging method for charging a liquid container with a liquid, the liquid container being provided with a piezo-electric device for detecting a consumption condition of the liquid in said liquid container, the piezo-electric device being provided with a cavity connecting to an inside of the...http://www.google.com.au/patents/US7156506?utm_source=gb-gplus-sharePatent US7156506 - Liquid charging method, liquid container, and method for manufacturing the same
