Patent ID: 8145091
Filing Date: 2012-03-27
Classification: G03G

Abstract:
1. An image forming apparatus including: a bias voltage controller-that controls a bias voltage to be applied to a developing roller; an image former that performs image formation by forming a toner image on an image carrier using a toner supplied from the developing roller to which the controlled bias voltage is applied, primarily transfers the toner image onto a running intermediate transfer member, and secondarily transfers the toner image onto a recording sheet using a transfer voltage applied to a secondary transfer roller; and a cleaner that cleans the secondary transfer roller by applying the bias voltage to the secondary transfer roller as a cleaning voltage necessary for cleaning the secondary transfer roller, and reversely transferring the toner adhered to a circumferential surface of the secondary transfer roller onto the intermediate transfer member, the cleaner comprising: a switcher operable to switch between electric paths such that the bias voltage is applied to the secondary transfer roller as the cleaning voltage, instead of the transfer voltage; an instruction part operable to, if a present absolute value of the bias voltage is less than a threshold value, instruct the bias voltage controller to control the absolute value so as to be no less than the threshold value; and a secondary transfer roller driver operable to, if the bias voltage controller receives the instruction by the instruction part and controls the absolute value, move the secondary transfer roller such that the secondary transfer roller is kept separated from the intermediate transfer member for a predetermined period, and if the bias voltage controller does not receive the instruction by the instruction part, keep the secondary transfer roller in pressure-contact with the intermediate transfer member.