| 摘要 |
<P>PROBLEM TO BE SOLVED: To collect tonner remaining on a developing roller to the side of a magnetic roller and to prevent the collected toner from accumulating on the magnetic roller, in a developing device comprising the developing roller and the magnetic roller. <P>SOLUTION: A control unit 90 applies a collection bias Br including an alternate-current component and performs a collecting operation that collects toner from a developing roller 83 to a magnetic roller 82 at a predetermined timing when no developing operation is performed. The control 90 checks, in advance of performance of the collecting operation, a set value of the most recent developing bias and determines a value of the collection bias Br corresponding to the checked developing bias. In this case, a Duty ratio component, of a polarity on the side where toner moves from the developing roller to the magnetic roller, can be changed among alternate-current biases constituting the collection bias Br. <P>COPYRIGHT: (C)2013,JPO&INPIT |
