A pyroelectric element includes a plurality of electrodes formed on one major surface of a pyroelectric film and constituting a first group and at least one electrode formed on the other major surface of the pyroelectric film and constituting a second group, wherein directions of proximal end portions...http://www.google.es/patents/US4983838?utm_source=gb-gplus-sharePatente US4983838 - Pyroelectric element
