Patent ID: 7532834

Claim:
A fixing device comprising a first contacting member contacting a toner image surface and a second contacting member contacting a surface opposite to the toner image surface, the fixing device fixing an unfixed toner image on a printing medium by causing the printing medium to pass through a contacting region (i) where the first contacting member and the second contacting member are in contact with each other and (ii) which is heated to a temperature at which fixing of toner is able to be carried out, the fixing device further comprising: heating means for heating the first contacting member and the second contacting member; and control means for controlling said heating means so that a surface temperature of the second contacting member satisfies at least either of the following conditions (1) and (2), namely (1) the surface temperature of the second contacting member is not less than a lower temperature that is defined by a cold offset occurring boundary temperature of the first contacting member and (2) the surface temperature of the second contacting member is not more than an upper temperature that is defined by a hot offset occurring boundary temperature of the first contacting member, wherein the control means controls the surface temperature of the second contacting member so that the surface temperature of the second contacting member is lower than the surface temperature of the first contacting member.