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Flexible warming structure

  • US 3,898,427 A
  • Filed: 07/01/1974
  • Issued: 08/05/1975
  • Est. Priority Date: 06/29/1973
  • Status: Expired due to Term
First Claim
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1. A transparent flexible warming structure comprising:

  • a first flexible transparent plastic sheet having a pair of side edges;

    an electrically conductive transparent heater layer over substantially all of one side of the sheet;

    a second flexible transparent plastic sheet bonded to the heater layer over substantially all of its area except a portion of a strip along each of the pair of side edges; and

    a high conductivity flexible strip electrically and mechanically bonded to the heater layer along each of the pair of side edges;

    said plastic sheets being selected from synthetic resins that are substantially transparent in the visible spectrum and substantially opaque in bulk in the infrared spectrum, have a heat deformation of less than about 1 percent in any direction at about 150* F, have an elastic modulus in the range of about 1.8 X 105 to 4.5 X 105 psi, and are selected from the group consisting of polycarbonate resin, polyimide resin, fluorinated ethylene-propylene resin, polyamide resin, polyester resin, polyacrylic resin and cellulose triacetate resin, at least one of said sheets having a sufficiently low vapor pressure to be vacuum metallizable, the total thickness of the flexible warming structure being up to abouT 30 mils so as to be readily bent by hand.

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