| 摘要 |
PROBLEM TO BE SOLVED: To set developing bias in an appropriate and accurate way in a developing method of transferring all toner layers formed on a developing roller onto an image carrier for development.SOLUTION: A developing bias setting unit 41 sets developing bias to a target developing bias value to transfer all toner layers on a developing roller 14 onto a photoreceptor drum 1a during normal printing. A conveyance bias setting unit 42 sets conveyance bias to at least two different levels during the adjustment period, and the developing bias setting unit 41 changes the developing bias with respect to a plurality of toner marks for the at least two different levels of the conveyance bias, specifies the minimum developing bias value from the density measurements of the plurality of toner marks, and determines a target developing bias value from the density measurements and minimum developing bias value for the at least two different levels of the conveyance bias. |
