Patent ID: 7379681
Filing Date: 2008-05-27
Classification: G03G,H04N

Abstract:
1. An image forming apparatus comprising: a rotatable image bearing member; a charging device configured to charge the image bearing member with a different applied bias for each predetermined timing; an exposure device exposing surface areas of the charged image bearing member by scanning with an optical beam, while changing an exposure intensity of the optical beam; an electric potential detecting device detecting respective surface electric potentials of the surface areas in which the exposure intensity is changed; a control device controlling the applied bias to the charging device necessary for obtaining a predetermined electric potential of a dark section and the exposure intensity of the optical beam necessary for obtaining a predetermined electric potential of a bright section, on the basis of the surface electric potentials that are detected respectively from the different applied biases and the different exposure intensities; an applied bias determining part obtaining a first correspondence relation between the different applied biases and the surface electric potentials on the basis of the surface electric potentials that are detected when the exposure intensity takes a first value, and determining the applied bias necessary for obtaining the predetermined electric potential of the dark section on the basis of the obtained first correspondence relation; and an exposure intensity determining part obtaining a second correspondence relation between the different exposure intensities and the surface electric potentials on the basis of the surface electric potentials that are detected when the exposure intensity takes a second value and the surface electric potentials that are detected when the exposure intensity takes a third value, and determining the exposure intensity necessary for obtaining the predetermined electric potential of the bright section on the basis of the obtained second correspondent relation.