Patent ID: 7493058

Claim:
An image forming apparatus comprising: a developing device that applies a two-component developer containing toner and magnetic carrier to a latent image so that the toner adheres to the latent image, and develops an image, a detection area being predetermined in the developing device; a stirring and carrying member that is located in the developing device, and stirs and carries the two-component developer in the detection area at different stirring and carrying speeds that correspond to a plurality of image forming modes including a first image forming mode and a second image forming mode, the stirring and carrying speeds including a reference stirring and carrying speed that corresponds to the first image forming mode, and a second stirring and carrying speed that corresponds to the second image forming mode; a detecting unit that detects magnetic carrier contained in the two-component developer in the detection area, and outputs, based on detected magnetic carrier, a reference output value when the two-component developer is stirred and carried at the reference stirring and carrying speed, and a second output value when the two-component developer is stirred and carried at the second stirring and carrying speed; and a controlling unit that performs an image forming process while switching the image forming modes, and controls toner concentration, for performing the image forming process in the first image forming mode, based on the reference output value, and controls the toner concentration, for performing the image forming process in the second image forming mode, based on a corrected output value obtained by correcting an output value of the detecting unit in the second image forming mode with a difference value between the reference output value and the second output value.