Flexible planar heating unit adapted for mounting on complex curved surfaces

Claim 1

A combination of a flexible planar heating unit and an article to be heated by said heating unit, said heating unit adapted to receive electrical current through spaced bus bars provided therein, said heating unit comprising an inner, semiconductive core layer bearing said bus bars which is laminated between electrically insulating face panels bound to said layer and to one another outwardly of the margins of the core layer about the entire periphery of the heating unit, said unit presenting, in outline, a principal body portion having a core layer provided with bus bar means and, projecting from said body portion in directions generally perpendicular to said bus bar, a plurality of spaced, generally parallel arms each containing a core layer which is integral with that in the principal body portion and which is provided with a bus bar adjacent its outer extremity whereby current supplied to the first mentioned bus bar means passes through the core layer of the principal body portion of the heating unit and then in a parallel flow through the core layer of the projecting arms to the respective bus bars provided therein, thereby heating the heating unit, said article having a curved surface of nonsimple configuration to which is secured one face of the heating unit in good heat transfer relationship, the principal body portion and connecting arms of the heating unit being flexed to accommodate the surface of the heater to the underlying surface of the article without engendering substantial folding or overlapping of the elements of the heating unit as the latter is secured to the said article surface.