Abstract: An image forming machine equipped with a transfer belt unit includes a safety detecting means for detecting the completion of setting of an opening/closing member constituting the image forming machine, and a controlling means for controlling the operation of a driving means for a driving roller on the basis of a signal from the safety detecting means. When the safety detecting means signals the completion of the setting after signaling the incompletion of the setting, the controlling means controls the driving means so as to perform a reverse driving, thereby driving the driving roller reversely by a predetermined amount.

Abstract: A transfer device of an image forming machine has a belt unit comprising a pair of supporting plates disposed with a predetermined spacing, a driving roller journaled rotatably at one end portion of the pair of supporting plates, a driven roller journaled rotatably at the other end portion of the pair of supporting plates with a predetermined spacing from the driving roller, a transfer roller disposed between the driving roller and the driven roller, journaled rotatably on the pair of supporting plates, and given a predetermined voltage, and a transfer belt looped among the driving roller, the driven roller and the transfer roller, and disposed opposite an image bearing member. The transfer belt of the belt unit is formed so as to have a width larger than the spacing between the pair of supporting plates, and is disposed such that its side end portions surround at least part of the pair of supporting plates.

Abstract: A transfer device for an image forming machine has a driving roller, a driven roller disposed at a distance from the driving roller, a transfer belt extending between the driving roller and the driven roller, a transfer roller disposed opposite an image bearing member, with the transfer belt interposed therebetween and pressing the transfer belt against the image bearing member, and a voltage source for applying a predetermined voltage onto the transfer roller. The transfer roller consists of a rotating shaft and a roller portion mounted on the rotating shaft, and the hardness of the roller portion is set to result in a compression of 0.45 to 2.00 mm at a linear pressure of 3 g/cm. The volume resistivity of the roller portion of the transfer roller is set at 10.sup.2 to 10.sup.9 ohm-centimeters.