High-efficiency task heater

Claim 1

A radiant electric heater comprising: (a) an elongated thermal insulating material having a thermal conductivity at 1500° F. in the range of about 0.07-0.15 BTU's per hour-foot-degree Fahrenheit; (b) mounted on one surface of said insulating material there is a corrugated ribbon radiant heating element; (c) an elongated reflector having a parabolic cross section and being positioned relative to the ribbon heating element without any structural element being positioned therebetween, the heating element being positioned at the focus of the parabolic shape of the reflector and the thermal insulation being positioned on the side of the focus opposite from the side of the focus where the reflector is positioned; (d) said elongated reflector having an open side from which radiant energy is directed in a fixed pattern; (e) said thermal insulating material being positioned on the side of the radiant heating element which faces the open side of the elongated reflector whereby the thermal insulating material functions to limit heat flow directly downward from the side of the radiant heating element facing the open side of the elongated reflector to less than 5% of the total heat flow generated by the radiant heating element; and (f) said radiant heating element being deeply corrugated with the height of each corrugation being a multiple of 2 to 3 times the width of each corrugation whereby the deep corrugations not only provide mechanical strength, but also increase effective emissivity per unit area of the radiant heating element.