Abnormal charge and toner density detecting system and method for use in

Abstract

An image forming apparatus which detects the cause of the image unevenness in the image formation of an electrostatic recording system used for a copying machine, laser beam printer or the like, and automatically takes measures responding thereto. This image forming apparatus includes a surface potential sensor for detecting charge unevenness after charging a photoconductive drum by a charger and a toner density sensor for detecting toner adhesion unevenness after developing by a developing unit, and based on the results of detections of these sensors, when charge unevenness exits, the apparatus judges that the cause of the image unevenness is an abnormal state of the charger, and cleans a charge wire, and when no charge unevenness exists and density unevenness exists, the apparatus judges that the developing unit is abnormal, and displays this abnormality and inhibits the operation of the apparatus. The apparatus further includes a toner sensor for detecting density unevenness after transfer, and when density unevenness is detected by this sensor, it is judged that the cause of the image unevenness is an abnormal state of a transferring charger, and displays this abnormality and inhibits the operation of the apparatus.