Patent ID: 9547261
Date: 2017-01-17
CPC Classifications: G03G

Claim:
1. An image forming apparatus comprising: an image forming unit including a photoconductor drum, and configured to form a toner image on an outer circumferential surface of the photoconductor drum; an intermediate transfer belt disposed so as to oppose the photoconductor drum, so that when the intermediate transfer belt is in contact with the photoconductor drum the toner image is transferred from the photoconductor drum onto an outer surface of the intermediate transfer belt; a brush roller that collects toner remaining on the outer surface of the intermediate transfer belt after the toner image is transferred from the intermediate transfer belt to a recording sheet; a first power source unit that applies a bias of a reverse polarity to a normal charge polarity of the toner to the brush roller; a charging device located upstream of the brush roller in a running direction of the intermediate transfer belt; a charge bias applying unit that applies a bias of a same polarity as the normal charge polarity of the toner to the charging device; a drive mechanism configured to drive the photoconductor drum, the intermediate transfer belt, and the brush roller; a contact control mechanism configured to switch the photoconductor drum and the intermediate transfer belt to a non-contact phase from a contact phase; and an operation control unit configured to: perform a cleaning mode including cleaning the brush roller while an image forming operation is not being performed; cause the contact control mechanism to set the photoconductor drum and the intermediate transfer belt to the non-contact phase in the cleaning mode; and cause the drive mechanism, while the photoconductor drum and the intermediate transfer belt are in the non-contact phase, to drive the brush roller to rotate at a rotation speed higher than a rotation speed of the brush roller in the image forming operation, and drive the intermediate transfer belt, wherein the image forming apparatus in the cleaning mode is configured to: drive the brush roller to rotate at the rotation speed higher than the rotation speed of the brush roller and discharge the toner accumulated in the brush roller from the brush roller; apply, from the charging device, a charge of the same polarity as the normal charge polarity to the discharged toner by the bias of the same polarity as the normal charge polarity that is applied by the charge bias applying unit; and, thereafter, electrically adsorb and collect the discharged toner to the brush roller by the bias of the reverse polarity to the normal charge polarity that is applied by the first power source unit.