Patent ID: 6855468

Claim:
A method for the formation of a color image which comprises the steps of forming an electrostatic latent image in accordance with an electrophotographic process, visualizing said electrostatic latent image by a developer transported by a developer support to form a multicolored toner image whereby monochromatic color toner images are formed by mutually independent developing steps comprising a contact type non-magnetic one-component developing method, and superposing then the resulting monochromatic toner images with one another to form a multicolored toner image, and in which method a toner used in each developing step contains an external additive which comprises inorganic fine particles having a mean particle diameter of 30 to 100 nm, said inorganic fine particles comprising particles of hydrophobic silica having a negative charge polarity, and fine particles having a positive charge polarity and a diameter within the range of 0.3 to 1.5 μm, the addition amount of the external additive to a non-added toner containing no external additive is within the range of 1.5 to 10.0 parts by weight on the basis of 100 parts by weight of said non-added toner, and the aggregation degree of said toner is within the range of 30 to 80%, and the change ratio of the aggregation degree satisfies the following formula: 1.0≦(initial aggregation degree)/(aggregation degree after 20 hours of no-load revolution of developing roller used as the developer support)≦1.2; and wherein said developer is a nonmagnetic one-component developer.