| 摘要 |
PROBLEM TO BE SOLVED: To prevent toner from being fused on the 1st side of a medium sheet where an image has been already formed in a period when the image is fused on the 2nd side of the medium sheet in a double-sided printing mode by keeping the operation temperature of a pressure roller lower than the cold offset temperature of the toner in a specified printing mode by specified degrees. SOLUTION: In order to prevent the image already formed on either side of the medium sheet 29 from being fused again or from getting indefinite the temperature of a fusing roller 49 and the pressure roller 50 must be controlled so that it may not jet high enough to fuse the toner image on the 1st side of the sheet 29 again. Then, the temperature of the roller 50 in the midst of double-sided printing operation is kept lower than the toner cold offset temperature in the specified printing mode to be utilized at least by 5 deg.C, desirably at least by about 10 deg.C, most desirably, at least by about 15 deg.C. |
