Patent ID: 7991327

Claim:
An image forming apparatus comprising: a photoconductor configured to be driven to rotate at linear velocity v (millimeters/second) at the time of image formation; a charge roller that is in contact with the photoconductor and that is configured to rotate along with the photoconductor, the charge roller having an outer diameter; and a charging unit configured to apply direct current voltage between the charge roller and the photoconductor, wherein the outer diameter of the charge roller and the linear velocity v of the photoconductor are predetermined such that a ratio w/v is from 0.005 to 0.035 (seconds), wherein w (millimeters) is a distance between two discharge marks occurring on the photoconductor upon intermittent application of the direct current voltage for a predetermined time while the photoconductor and the charge roller are not rotating in an environment where the photoconductor and the charge roller are illuminated with light.