THERMAL COLORING MEDIUM AND HEATING DEVICE THEREFOR

PURPOSE:To improve luster on the surface of an image remarkably, by applying conduction processing onto a receiver sheet requiring heating and bringing an element having counter electrodes for locally supplying current to a portion of a medium necessary for producing Joule's heat into contact with the medium perpendicularly to its running direction. CONSTITUTION:Thermally fusible brightener for providing luster onto the surface of an image and improving the density of color is applied onto a receiver sheet 20 applied with electron receptor material which contacts and reacts with colorless dye in microcapsule. A paper substrate constituting the base of the receiver sheet 20 is impregnated with conductive material such as Cu1 (copper iodide) to prepare a paper substrate applied with conduction processing, then a pair of electrodes 7 mounted on a heating device 6 are contacted conductively with the base paper 2 from the rear face thereof so as to supply power. Consequently, very high Joule's heat is produced with high speed in the paper substrate and nearby brightener is transmitted with Joule's heat without direct contact with the image portion and fused.