Abstract: An image forming apparatus has an image bearing member, a charging member which contacts with the image bearing member to charge it, detecting device for detecting an electric current flowing through the charging member when a predetermined voltage is applied thereto, and a display device for displaying an information about a life of the image bearing member in conformity with the result of detection by the detecting device. The display device can display at least two different kinds of information corresponding to at least two different electric currents detected by the detecting device.

Abstract: An object of the present invention is to perform a well tonality reproduction according to a state of an image support body. In order to achieve the object, the present invention is featured by comprising the image support body for supporting an image which is to be formed on a medium, a signal generation means for generating an image signal representing the image, a detection means for detecting a value according to a membrane thickness of the image support body, and a conversion means for converting the image signal on the basis of the detected value according to the membrane thickness.

Abstract: An image forming apparatus includes an image bearing member; a charging member contactable the image bearing member to charge the image bearing member at a charging position; wherein an AC current applied to the charging member is constant-current-controlled when a region of the image bearing member which is going to be an image formation region is at the charging position, and wherein a current flowing through the charging member is detected when a region of the image bearing member which is going to be a non-image-formation region is at the charging position, and the AC current is determined on the basis of the detected current.