| 摘要 |
PROBLEM TO BE SOLVED: To avoid the collision between a sheet which is newly discharged to a discharge tray and a sheet which has already been stacked thereon, in an image forming device. SOLUTION: The presence or absence of paper sheet near a discharge roller 901 at the height of a distance HA from the bottom surface of the discharge tray 91 is detected utilizing a light emitted from the output part 911A of a ranging sensor. When the deflection of the paper sheet discharged onto the discharge tray 91 is relatively large, the ranging sensor emits light through a path indicated by a dotted line L to detect the presence or absence of the sheet on the path. Namely, the presence or absence of the sheet on the discharge tray 91 is detected at the position lower than the upstream-most part (the position where the output part 911A emits light) on the downstream side in the sheet discharging direction R10. COPYRIGHT: (C)2009,JPO&INPIT
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