In the transfer belt unit according to an embodiment of the present invention, rotation of a rear-side detection roller or a front-side detection roller rotated in contact with ribs of a transfer belt is transmitted to a steering roller via a lead screw to tilt the steering roller and control meandering of the transfer belt. As a result the level of accuracy of the screening is significantly increased. If a particular party does not communicate its level of interest within an given timeframe, that party’s level of interest may be assumed to be a default level of interest. As copies accumulate on the platform the weight of the copies causes the springs to stretch and increases the capacity of the output tray. The driving unit includes a stator coupled on the hollow shaft portion, a rotor located outside the stator and a spindle having two ends respectively coupling with the rotor and tool head and running through the hollow shaft portion, ancillary support member and ancillary rotary member.