| 摘要 |
PROBLEM TO BE SOLVED: To form images of the same size on both sides of a paper sheet when the toner image transferred on the paper sheet is fixed by heat and pressure. SOLUTION: A paper sensor 17-1 is arranged along a conveyance belt 10 to detect the length of a paper sheet before its surface is fixed, and a paper sensor 17-2 is arranged along a conveyance path 16 to detect the length of the paper sheet after the surface is fixed. The length data of the paper sheet before and after the surface is fixed detected by the paper sensors 17-1, 17-2 are fed to a controller 20 and modulated by the laser beam writing clock and the reference clock of a polygon motor 5-3 when the back face is printed so that the sizes of the images on both faces are made equal when the paper sheet is returned to the original temperature after fixing. The reference clock is fed to LD drivers for Bk, M, Y, C, and the back face image is written on photosensitive drums 6-1 through 6-4 in the desired size. |
