Patent ID: 7536137

Claim:
A wet electrophotographic image forming apparatus comprising: a photosensitive medium on which electrostatic latent images are formed in accordance a light exposure unit based on print data; a plurality of developing units including a developing roller to transfer the developing solution to the photosensitive medium to develop the electrostatic latent images in particular colors, and a developing solution density detecting means to detect the density of the developing solution; a transfer unit to transfer the images developed by the plurality of developing units to a printing medium; a fixation unit to fix the images onto the printing medium; a color detecting unit to detect colors for developing the electrostatic latent images of a printed page; and a controller to selectively turn on and off development bias applied to developing rollers of the plurality of the developing units according to the colors detected by the color detecting unit; wherein the controller selects a separate on or off state for each of pre-printing, printing and post-printing operations based on the detected density of the developing solution detected by the developing solution density detecting means, and selectively turns on or off the development bias during the selected operations according to the selected separate on or off state for each operation.