| CPC G03G 15/5004 (2013.01) [G03G 15/0126 (2013.01); G03G 15/0131 (2013.01); G03G 15/0189 (2013.01); G03G 15/161 (2013.01); G03G 15/5008 (2013.01); G03G 15/5054 (2013.01); G03G 15/80 (2013.01); G03G 21/0058 (2013.01); G03G 21/007 (2013.01)] | 7 Claims |
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1. An image forming apparatus comprising:
a plurality of image forming units each including
an image carrier having a photosensitive layer on a surface thereof,
a charging device that charges the image carrier,
an exposing device that exposes the image carrier charged by the charging device so as to form an electrostatic latent image, and
a developing device having a developer carrier that carries developer containing toner, the developing device allowing the toner to adhere to the electrostatic latent image formed on the image carrier, so as to form a toner image;
an intermediate transfer body that is capable of moving along the plurality of image forming units, so that the toner image formed by the image forming unit is primarily transferred onto the intermediate transfer body;
a primary transfer member that primarily transfers the toner image formed on the image carrier onto the intermediate transfer body;
a secondary transfer member that secondarily transfers onto a recording medium the toner image transferred onto the intermediate transfer body;
a cleaning mechanism that removes the toner adhered to the intermediate transfer body;
a developing voltage power supply that applies a developing voltage to the developer carrier;
a charging voltage power supply that applies a charging voltage to the charging device;
a transfer voltage power supply that applies transfer voltages to the primary transfer member and the secondary transfer member;
a collecting roller disposed in each of the plurality of image forming units, so as to collect transfer residual toner remaining on the image carrier after the primary transfer;
a cleaning voltage power supply that applies a voltage to the collecting roller; and
a control unit that controls the image forming unit, the developing voltage power supply, the transfer voltage power supply, the charging voltage power supply, and the cleaning voltage power supply, wherein
the image forming apparatus performs a transfer residual toner collection operation including
a toner adhesion step of applying the collecting roller with a voltage having opposite polarity to charge polarity of the toner during execution of an image forming operation, so as to allow the transfer residual toner to temporarily adhere to the collecting roller,
a toner moving step of separating the developer carrier and the image carrier from each other after finishing the image forming operation, and then applying the collecting roller with a voltage having the same polarity as the charge polarity of the toner, so as to move the transfer residual toner adhered on the collecting roller to the image carrier, and
a toner collecting step of moving the transfer residual toner from the image carrier to the intermediate transfer body, so that the cleaning mechanism collects the transfer residual toner,
the image forming apparatus further comprises a toner amount detection unit that detects white background toner amount on the intermediate transfer body, and
the control unit controls the image forming unit having the white background toner amount that is a threshold value or more, to apply the collecting roller with the voltage having the same polarity as the charge polarity of the toner in the toner adhesion step, and to apply the collecting roller with the voltage having opposite polarity to the charge polarity of the toner in the toner moving step, so as to perform the transfer residual toner collection operation.
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