| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a sheet length measuring device which can accurately measure a sheet length with a simple configuration where the number of detection means in sheet ends is reduced without being affected by deflection or slack generated in a conveyed sheet nor forming image patterns, and to provide an image forming apparatus including the sheet length measuring device. <P>SOLUTION: The sheet length measuring device includes: a driving roller 1 rotatably driving in a conveyance path of a sheet P to be conveyed; a driven roller 2 for holding the sheet between the driving roller and itself; a driving means for rotatably driving the driving roller; an end part detection means 10 for detecting the passage of the sheet end in the conveyance path of the sheet; and a rotational amount measuring means for measuring a rotational amount of the driving roller, wherein the length in a sheet conveyance direction is calculated based on a measurement result of the rotational amount measuring means while the end part detection means detects that the rear end of the sheet passes after detecting that the front end of the sheet passes. The detection position by the end part detection means is set within a range where the sheet is held by the driving roller and the driven roller in the sheet conveyance direction. <P>COPYRIGHT: (C)2013,JPO&INPIT |
