Patent ID: 6137968
Filing Date: 2000-10-24
Classification: B65H

Abstract:
An image forming apparatus, comprising:a main body;a sheet tray disposed removably from said main body;a sheet placement table disposed in said sheet tray, said sheet placement table being movable upwardly and downwardly;a sheet supply roller disposed upwardly of said sheet placement table for discharging and feeding the upper-most one of sheets placed on said sheet placement table of said sheet tray;a sheet position restrict member removably mounted on said sheet tray;control means for detecting that the upper surface of said sheet placement table or the upper-most surface of said placed sheet is in contact with said sheet supply roller and for keeping the position of said upper-most surface of said placed sheet at a constant level; andan optical sensor disposed outside of said sheet tray wherein the optical axis of said optical sensor set parallel to said upper surface of said sheet placement table passes above a contact position between said placed sheet and said sheet supply roller, for outputting a signal used for detecting:a first condition based on information as to whether said sheet is positioned at a sheet suppliable position on said table of said sheet tray or not;a second condition based on information as to whether the sheet position restrict member is set properly or not;a third condition based on information as to whether a foreign object has invaded said main body or not when said sheet tray is removed from said apparatus main body; anda fourth condition based on information on the warped amount and folded amount of said sheet.