Patent ID: 7503558
Filing Date: 2009-03-17
Classification: G03G

Abstract:
1. A sheet elevating apparatus for use in a sheet tray cassette detachably installable to an image forming apparatus, comprising: an elevation driving source mounted to the image forming apparatus; a first coupling connected to the elevation driving source and having a home position; an elevation member configured to elevate a plurality of recording sheets placed on an elevating base plate of the sheet tray cassette; a second coupling connected to the elevation member so as to engage with the first coupling set at the home position when the sheet tray cassette is installed in the image forming apparatus; an elevation controller configured to drive the elevation driving source to set the first coupling to the home position when the sheet tray cassette is pulled out; and a remaining sheet detector configured to detect an amount of recording sheets remaining on the elevating base plate of the sheet tray cassette, wherein the elevation controller calculates rotation passages in clockwise and counterclockwise directions for the first coupling to return to the home position and drives the elevation driving source to set the first coupling in a shorter course of one of the rotation passages calculated to the home position in accordance with the amount of recording sheets detected by the remaining sheet detector before the sheet tray cassette is pulled out.