An improved flexible blanket heater includes a thin, normally flat flexible blanket of elastic dielectric material having a high modulus of elasticity and defining top and bottom surfaces. An elongate flexible resistance element of an alloy having a lower modulus of elasticity than said dielectric material...http://www.google.es/patents/US4695703?utm_source=gb-gplus-sharePatente US4695703 - Flexible blanket heater
