| 摘要 |
A developing unit includes a developer consumption calculator, a consumption shift unit, a supply amount setting unit and a developer supply controller. The developer consumption calculator calculates consumptions of developer in zones and stores the consumption in each zone into a corresponding storage region. The consumption shift unit shifts the consumption stored in the storage region corresponding to each zone to a storage region corresponding to a zone located on a downstream side in a developer conveyance direction in response to the conveying of the developer by the circulation conveyance member. The supply amount setting unit sets a supply amount from a developer supply portion based on the consumption stored in the storage region corresponding to the zone corresponding to the developer supply position. The developer supply controller controls supply of the developer from the developer supply portion based on the set supply amount.
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