Abstract: In a color image forming apparatus, charging, exposure and development are repeated thereby a plurality of color component toner images are formed in superposing on an image carrier and then transferred collectively to an image receptor. As a charging device used in image forming cycle of at least the second color or later, a corona charging device having a discharge electrode and a grid is used. An electrode power source applying at least AC voltage is connected to the discharge electrode, and a grid power source applying AC voltage in nearly the same phase as that of the AC voltage applied to the discharge electrode is connected to the grid, and frequency or peak-to-peak amplitude of the AC voltage from the grid power source is set to optimum range.

Abstract: In a color image forming apparatus, a screen of each of electrostatic latent images to be formed by an exposing device has a parallel lines structure, and phases of the electrostatic latent images each having the parallel lines structure for at least two different colors are made different from each other. Accordingly, the color image forming apparatus can totally solve the problem caused by the rise in potential of exposed portions by toner charges and the dielectric property of toner layers and the problem caused by the toner shielding effect to thereby allow faithful reproduction of a highlight area important for a good halftone image, especially a high-quality color image.