JPS6410033A - Flat warmer - Google Patents

Abstract

PURPOSE:To obtain speedy warmth as in contact space heating and keep warmth comfortably at the stable tine by a method wherein a warm surface plate for receiving conduction heat is composed of material with small heat conductivity and an opening part is formed into a radiation and convection part. CONSTITUTION:Warm surface plates 7 for receiving conduction heat, uniformly heated 8, and belt-shaped heating elements 9 are brought in the condition of laminated adhesion and formed into a vessel shape and by covering the vessel with insulating material from its outside the bottom wall and side walls of the main body of a sunken kotatsu (Japanese foot warmer) are constituted. On the plate 7 opening parts from which alumina fiber put on the surface of the plate 8 is visible are formed. In the element 9 a pair of electrodes 11 are placed on both surfaces of a thin laminar resistance 10 with a positive resistant temp. coefficient and an insulating film 12 is laminated on the electrodes from the outside. The heat conductivity k of the plate 7 is, e.g. about 0.05[kcal/mh deg.C] in the range from ordinary temp. to 100 deg.C and its thickness L is e.g. 2.5 [mm]. The resistance 10 is made of high density polyethylene containing e.g. carbon and indicates suddenly a positive temp. coefficient around 120 deg.C as its crystal transformation point.