| 摘要 |
A developing device includes a developing housing which faces an image carrier on which an electrostatic latent image is carried and stores a developer which contains toner and magnetic carrier; a developer carrier that is disposed apart from the image carrier in the developing housing and carries and transports the developer; a developing bias applying unit that is disposed between the image carrier and the developer carrier and applies a developing bias comprising an AC component and an DC component which is superposed to a DC component; a volume resistivity detecting unit which detects a volume resistivity of the developer on the developer carrier; and a developing bias adjusting unit which sets the AC component of the developing bias to a reference value when the volume resistivity of the developer detected by the volume resistivity detecting unit falls within a given range, and corrects the AC component of the developing bias such that an image quality evaluation parameter falls within an allowable range when the volume resistivity of the developer exceeds the given range.
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