Patent ID: 8200106

Claim:
An image forming apparatus comprising: a photosensitive member; charging means for electrically charging said photosensitive member; exposure means for exposing to light said photosensitive member electrically charged by said charging means to form an electrostatic image; developing means for developing the electrostatic image with toner to form a first patch and a second patch; detecting means for detecting a density of the first and second patches formed by said developing means; and control means for controlling an image forming condition on the basis of a difference in density between the first patch formed on said photosensitive member at a portion where a surface potential of said photosensitive member is zero volts and the second patch formed on said photosensitive member at a portion electrically charged by applying a predetermined charging bias to said charging means, wherein said control means controls the image forming condition on the basis of the difference in density between the first patch and the second patch formed with substantially no emission of light from said exposure means, and controls density gradation during image formation on the basis of a density of a patch formed by effecting imagewise exposure by said exposure means.