CHARGING DEVICE AND IMAGE FORMING APPARATUS USING THE SAME

A charging device includes: a charging member that faces an image carrier and charges a surface of the image carrier; a charging voltage controller that controls a charging voltage to be applied to the charging member when the surface of the image carrier is to be charged, and applies the charging voltage obtained by superposing an AC voltage which is subjected to constant-current control on a DC voltage; a variation range detector that detects a variation range of the AC voltage which changes according to the characteristic change of the charging member; and a response speed controller that reduces a response speed for the variation of the AC voltage in correspondence with the characteristic change when the variation range is larger than a predetermined set value.