PURPOSE: To enable prevention of a dewing phenomenon by raising a temperature of the backside of the captioned plate above a dew point, by interposing a heat insulation layer made up of foamed plastics into a board body for the top plate of KOTATSU.
CONSTITUTION: A square top plate 1 of KOTATSU is formed by an external frame 2 and a board body 3 contg. foamed plastics between panels 5 and 5 made of plastics. When the KOTATSU with a quilt over it is electrified after the top plate 1 is placed above a frame work 6 through the quilt, the temperature within the frame work 6 is increased causing the temperature increase at a point A above the frame work, and the temperature at a point B on the backside of the top plate 1 is increased. A heat radiation quantity in a point C direction of the surface of the top plate 1 from the point B, however, is inhibited as the intermediate part of the board 3 is made of a heat insulation layer, which results in a comparatively high temperature increase at the point B compared with an ordinary one.
MARUYAMA KAZUO
WADA NORIO
SAITOU KAZUHIDE
