| 摘要 |
PURPOSE:To obtain a double-sided image or a synthetic image satisfactorily by installing a paper detection sensor which measures the size of recording paper at the upstream and downstream sides of a paper carrying direction holding a fixing device, and setting an image forming magnification in the next image formation based on a measured value. CONSTITUTION:The size of paper before and after fixing 12 is measured with the paper detection sensors 21, 22 installed at the upstream and downstream sides of the fixing 12, respectively, and a ratio of size of recording paper before and after fixing, i.g. the reduction ratio of the recording paper by fixing is calculated based on the measured value. And the image forming magnification in the next image formation can be calculated based on the obtained reduction ratio of the recording paper, and the lens of an exposure optical system 8, etc., is changed to prescribed arranging relation according to a decided image forming magnification in the next time, and the next image forming process is executed. Thereby, it is possible to prevent magnification difference between forming images generated, and to obtain the double-sided image or the synthetic image satisfactorily. |
