| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus that more appropriately corrects the density. SOLUTION: A plurality of combinations of a ladder patch and a solid patch 111 to 113, are formed on a belt 51. The densities of the ladder patch and sold patch of the same combination are identical, and density differs between the combinations. Each of the formed patches is detected by an optical sensor 55. The amount of attached toner per unit area of the solid patch is calculated from the detection value of each solid patch. The calculated amount of attached toner of each solid patch is assumed as the amount of attached toner of each of the ladder patches of the identical density. A relational expression between the detected value of each ladder patch and the assumed amount of attached toner is obtained. An estimated detection value which may be detected when a ladder patch is formed with a density corresponding to the maximum amount of attached toner is obtained from the relational expression. A relational expression between the detection value of each ladder patch and the voltage value of a developing bias when the ladder patch is formed is obtained. The value of a developing bias voltage, corresponding to a target ladder detection value, is obtained from the relational expression as a target developing bias voltage value. COPYRIGHT: (C)2011,JPO&INPIT
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