Sheet conveying apparatus, image forming apparatus, sheet conveying distance calculation apparatus and sheet length calculation apparatus

摘要

A sheet conveying apparatus includes a sheet conveying unit that conveys a sheet including a drive roller, a driven roller, and a rotary encoder provided on a rotational axle of one of the drive roller and the driven roller; a conveying amount measuring unit that measures a conveying amount of the sheet; a first detection unit positioned downstream of the sheet conveying unit, the first detection unit being positioned apart from the drive roller and the driven roller not to overlap with the drive roller and the driven roller in the conveying direction; a second detection unit positioned upstream of the sheet conveying unit; and a conveying distance calculation unit that calculates a conveying distance of the sheet based on the measured result by the conveying amount measuring unit and the detected results detected by the first detection unit and the second detection unit.

主权项

1. A sheet conveying apparatus comprising:
a sheet conveying unit that conveys a sheet including
a drive roller which is driven to be rotated by a driving unit,a driven roller which is rotated in accordance with the drive roller while the sheet is interposed between the drive roller and the driven roller, anda rotary encoder provided on a rotational axle of one of the drive roller and the driven roller; a conveying amount measuring unit that measures a conveying amount of the sheet conveyed by the sheet conveying unit by measuring the number of pulses generated by the rotary encoder as a rotation amount; a first detection unit positioned downstream of the sheet conveying unit and detecting passing of a front end portion of the sheet downstream of the sheet conveying unit in a conveying direction of the sheet, the first detection unit being positioned apart from the drive roller and the driven roller not to overlap with the drive roller and the driven roller in the conveying direction, in a plan view; a second detection unit positioned upstream of the sheet conveying unit and detecting passing of a rear end portion of the sheet upstream of the sheet conveying unit in the conveying direction of the sheet; and a conveying distance calculation unit that calculates a conveying distance of the sheet based on the measured result by the conveying amount measuring unit and the detected results detected by the first detection unit and the second detection unit, wherein the distance between the first detection unit and the drive roller and the driven roller is set based on a conveying speed of the sheet and a resonance frequency of the one of the drive roller and the driven roller to which the rotary encoder is provided such that the first detection unit is capable of detecting passing of the front end portion of the sheet after velocity turbulence generated by insertion of the sheet between the drive roller and the driven roller converges.