Patent ID: 7900913
Filing Date: 2011-03-08
Classification: B65H

Abstract:
1. An image forming apparatus comprising: a first sensor that is provided in a conveying path for a sheet and detects a first passage time of the sheet; a second sensor that is provided at a position different from the position of the first sensor in both a transportation direction of the sheet and a direction perpendicular to the transportation direction, and detects a second passage time of the sheet; a skew determining unit that calculates a skew amount of the sheet from a difference between the first passage time detected by the first sensor and the second passage time detected by the second sensor and determines occurrence of skew of the sheet on the basis of the skew amount; a cause estimating unit that estimates, when the skew determining unit determines that the skew occurs, a cause of the occurrence of the skew; a tray-opening-closing detecting unit that detects whether the paper feeding tray is opened and then closed; and a display unit displays, when the cause estimating unit estimates the cause of the occurrence of the skew, the estimated cause or an action based on the estimated cause together with indication of the occurrence of the skew, and wherein the cause estimating unit estimates, when skew of the sheet occurs after the paper feeding tray is opened and then closed, that the skew occurs because of the opened and then closed paper feeding tray, and the display unit performs display for urging a user to check the opened and then closed paper feeding tray.