Abstract: A drive apparatus is comprised of a driven shift of a rotary photosensitive drum, a drive motor and a gear mechanism for rotatably driving the driven shaft, and a flywheel rotated around a wheel rotary shaft, for stabilizing the rotations of the driven shaft. A pulley having a large diameter is mounted on a rotary shaft directly coupled to the driven shaft, whereas a pulley having a small diameter is mounted on the wheel rotary shaft. An endless belt is wound on these pulleys, so that drive force is transferred from the rotary shaft to the wheel rotary shaft, and an angular velocity of the flywheel is made higher than that of the driven shaft.

Abstract: A sheet feed tray on which sheets are stored, a feed member for feeding out sheets one at a time from the sheet feed tray, a separating member for separating sheets when a plurality of sheets are fed out at a time from the sheet feed tray by the feed member, to feed the sheets one at a time, a transporting member for transporting the sheet delivered from the separating member to a image forming member, a sheet detecting member for detecting the passage of the leading edge of the sheet past a first position in the transporting member, a calculation member which, based on the behavior of a sheet which is fed by the feed member, but is then detained by the separating member, determines a target time at which a sheet should arrive at a second position downstream of said first position, and calculates from the detection result provided by the sheet detecting member the deviation from said target time of the sheet, and control member for varying the sheet transport speed on the basis of the results of calculation m

Abstract: A plurality of containers store sheets to be fed, and a plurality of sheet guides bias the sheets in the containers toward a predetermined location. Detectors determine the positions of the sheet guides and output position data corresponding to the size of sheets disposed in each of the plurality of containers. A memory circuit store sheet size data for a plurality of sheet size groups, and include, and at least a portion of sheet sizes from the plurality of sheet size groups are of similar dimension. A first comparison circuit compares selected position data with sheet size data stored in the memory to determine if sheets in a selected container are included in either a first group, a second group or the similarly dimensioned portion of the first and second groups.