JP2007072094A5 - - Google Patents

Claims (10)

An image carrier that carries an electrostatic latent image, an exposure unit that exposes the image carrier, a unit that changes the image magnification of the first and second sides during duplex printing, and a transfer unit that transfers an image to recording paper Means for detecting the size of the recording paper disposed on the upstream side, and means for calculating an image magnification correction value based on the expansion and contraction ratios of the recording paper sizes of the first and second sides during duplex printing detected by the detecting means. Prepared,
In a series of two-sided print job, if no recording sheet size of the second surface yet detect and yet not the image magnification correction value, the image into bearing member by the exposure means to said image magnification correction value is calculated while the exposure is stopped to resume the exposure to the image carrier by the exposure means in response to the image magnification correction value is calculated,
The recording sheet on which the image of the first surface is transferred is stopped upstream of the transfer portion, the starts conveyance of the recording paper the image magnification correction value from being calculated after a predetermined timing, the recording sheet in the transfer section An image forming apparatus for transferring an image on a second side. The image forming apparatus according to claim 1, wherein the latest image magnification correction value is selected and image magnification correction is performed to form an image on the second surface of the recording paper . The image forming apparatus according to claim 1 or claim 2, wherein said image magnification correction value selected in the image formation, is the difference by comparing the actual the image magnification correction value calculated from the printing after the paper An image forming apparatus that notifies a user of the fact that the predetermined value is exceeded. 4. The image forming apparatus according to claim 3, wherein a predetermined value of the difference between the image magnification correction values notified to a user can be arbitrarily set. The image forming apparatus according to claim 1 or claim 2, wherein said image magnification correction value selected in the image formation, is the difference by comparing the actual the image magnification correction value calculated from the printing after the paper An image forming apparatus, wherein when the predetermined value or more is reached, the recording sheet is discharged to a portion different from other printed recording sheets. 6. The image forming apparatus according to claim 5, wherein a predetermined value of a difference between image magnification correction values for discharging the recording sheet to a different part from other printed recording sheets can be arbitrarily set. Forming equipment.   6. An image forming apparatus, wherein a function of the image forming apparatus according to claim 3 or 5 can be selected.   3. The image forming apparatus according to claim 1, further comprising an intermediate transfer body that holds an image, and performing image formation by transferring the image held on the intermediate transfer body onto a recording sheet. Image forming apparatus.   3. The image forming apparatus according to claim 1, further comprising a conveyance belt that conveys the recording paper, and performing image formation by transferring the image onto the recording paper conveyed by the conveyance belt. Image forming apparatus. 3. The image forming apparatus according to claim 1, wherein a color image is formed on the recording paper.