Image density control method for an image forming apparatus

Claim 1

An image density control method for an image forming apparatus which executes detection in a pattern detection mode in which an electrostatic latent image formed on an image carrier to have a predetermined potential and representative of a pattern having a reference density is developed under a predetermined potential for development defined by a bias voltage which is applied to a developing station so as to produce a toner image associated with the pattern, and an amount of toner deposited on the toner image is sensed and compared with a reference value, said method performing control of an image condition to set up any of various image forming conditions in response to a result of the detection, said method comprising the steps of: (a) providing a plurality of pattern detection modes each for developing the latent image of the pattern having a reference voltage under a different potential for development; (b) determining a development gamma characteristic representative of a characteristic relationship between the amount of toner deposited on the toner image and the potential for development on the basis of the results of detection which are individually associated with the plurality of pattern detection modes; and (c) controlling the image forming condition such that the determined development gamma characteristic substantially coincides with a target development gamma characteristic.