Image forming apparatus and fixing device therefor

摘要

A fixing device for forming a toner image formed on a recording medium includes a heat roller accommodating a halogen heater. The halogen heater includes a glass tube formed of transparent quartz and provided with a wall thickness of 0.8 mm or below to increase transmission thereof. The increased transmission reduces a heat loss ascribable to the glass tube at the time of warm-up of the fixing device. The heat roller has such a thermal capacity that it can be warmed up in 10 seconds or loss. The glass tube is filled with inactive gas whose major component is krypton or xenon. A tungsten filament accommodated in the glass tube has its diameter reduced in order to implement a color temperature of 2,500 K or above. An image forming apparatus using the fixing device is also disclosed.