| 摘要 |
<p>A heating unit formed by coating metal core wires (l) with heating layers (A)(2) having positive temperature coefficient characteristics, and coating outer circumferential surfaces of these heating layers with a heating layer (Bl)(3) the positive temperature coefficient characteristics of which are different from those of the heating layers (A), or a heating layer (B2)(3) not having the positive temperature characteristics, a distance between the metal core wires (l) being set to within 5 mm, a volume ratio of the metal core wires (l) to these two layers of coating (2, 3) being set to 5-90 %. A heating unit, wherein conductive heating layers (X) are further formed between the metal core wires (l) and heating layers (A) so that a thermal expansion coefficient of the conductive heating layers has a value between that of a thermal expansion coefficient of the metal core wires and that of a thermal expansion coefficient of the heating layers (A). This heating unit is capable of reducing a load on an apparatus power source by reducing a rush current at a current application starting time, minimizing a decrease in the performance of the heating unit, and controlling the resistance temperature characteristics of a heating section easily, and, moreover, has a structure resistant to the use thereof in a high environmental temperature.</p> |
