Patent attributes
Within a fixing roller (231) are disposed a main heater lamp (234a) for heating a central portion of the fixing roller and a sub-heater lamp (235a) for heating opposite end portions of the fixing roller. MRnh, SRnh and ΣRnh satisfy the formula (1) or (2):ΣRnh≧30.5·Ln(Ht)+382 formula (1)MRnh≦−21.9·Ln(Ht)−198, formula (2)where MRnh is a mean value of heat distribution in a no-heat generating section of the main heater lamp; SRnh is a mean value of heat distribution in the a no-heat generating section of the sub-heater lamp; ΣRnh is the sum total of these mean values; and Ht=vp/(Mh·λ) where vp is a fixing speed (m/s), Mh a heat capacity per unit length of the heating member (J/(° C.·m)) and λ a heat conductivity of a material forming the heating member (W/(m·° C.)).
