| 摘要 |
The present invention provides an image forming apparatus for forming an image on printing paper by rolling up the printing paper around a cylindrical or column-shaped member without any fixture, that can measure with a high accuracy the length of the printing paper during transport thereof. The image forming apparatus of the present invention forms an image on printing paper in a state in which the printing paper is rolled up around an outer circumferential surface of a cylindrical or column-shaped member, and includes a sensor for detecting a front end or a rear end of the printing paper on the outer circumferential surface and a controller for calculating a length of the printing paper. The sensor, after having detected the rear end with the printing paper completely rolled up around the member, detects the front end along with rotation of the member. The controller calculates the length of the printing paper based on an operation amount of the member or a mechanism associated with driving of the member during a period from a detection of the rear end by the sensor until a detection of the front end.
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