Patent ID: 6620566
Filing Date: 2003-09-16
Classification: G03G

Abstract:
An image forming apparatus comprising:first to fourth image carriers; first to fourth developing devices opposing said first to fourth image carriers in one-to-one correspondence with each other to develop first to fourth electrostatic latent images, formed on said first to fourth image carriers, by using first to fourth developing agents, thereby forming first to fourth developing agent images, first to fourth transfer devices, arranged after said first to fourth developing devices in one-to-one correspondence with each other, for transferring the first to fourth developing agent images onto a transfer medium; and a fixing device for fixing the transferred first to fourth developing agent images on the transfer medium, wherein as each of the first to fourth developing agents, one of a yellow developing agent comprising a yellow toner particle and zinc stearate mixed with the yellow toner particle, said yellow toner particle containing a polyester resin having an acid value of not more than 6, a zirconium complex of a salicylic acid derivative, and a benzimidazolone pigment as a yellow pigment, a magenta developing agent comprising a magenta toner particle and zinc stearate mixed with the magenta toner particle, said magenta toner particle containing a polyester resin having an acid value of not more than 6, a zirconium complex of a salicylic acid derivative, and a naphthol AS insoluble azo pigment as a magenta pigment, a cyan developing agent comprising a cyan toner particle and zinc stearate mixed with the cyan toner particle, said cyan toner particle containing a polyester resin having an acid value of not more than 6, a zirconium complex of a salicylic acid derivative, and a phthalocyanine pigment as a cyan pigment, and a black developing agent comprising a black toner particle and zinc stearate mixed with the black toner particle, said black toner particle containing a polyester resin having an acid value of not more than 6, a zirconium complex of a salicylic acid derivative, and carbon black as a black pigment is applied; wherein development &ggr; characteristics of said first to fourth developing agents are substantially equal; and wherein said first to fourth developing agents are located in the respective first to fourth developing devices.