| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent occurrence of transfer insufficiency or transfer excess after the correction of image density while satisfactorily maintaining print productivity. <P>SOLUTION: After performing an ATVC (Auto Transfer Voltage Control) control that a voltage derived from a voltage Vi obtained when a constant current voltage is applied to a primary transfer roller 14 and preset table and/or arithmetic expression is determined as a transfer voltage Vt, an image density correcting operation is performed for correcting the density of an image of each color to predetermined density. In this image density correcting operation, for a development bias voltage Vd to be applied to a developer carrier 36 for each color, the variable values of a plurality of surface potential control means 91 are controlled so that the image density is controlled so as to have predetermined density of a correctable magnitude and the surface potential of an electrostatic latent image carrier 4 has a predetermined voltage Vp corresponding to the development bias voltage Vd. If the absolute value of a difference between the maximum and minimum variable values of the plurality of surface potential control means 91 is greater than a predetermined magnitude V<SB>B</SB>after the image density correcting operation, the ATVC control is exerted again. <P>COPYRIGHT: (C)2008,JPO&INPIT |
