| 摘要 |
PURPOSE:To prevent mixing of each color toner in successively executing the first and second developments using 2 different color toners, by using the toner used for the second development stage having larger particle diameter than that of the toner used for the first stage. CONSTITUTION:Each of developing devices 5, 6 uses a nonmagnetic toner composed essentially of a resin, and carries out jumping development using a one- component type nonmagnetic developer contg. no carrier iron powder. The toner of the device 5 is smaller in particle diameter than that of the device 6, and the former is black, while the latter is red. The cylindrical sleeves 11, 12 in contact with the toner in the device 5, 6 face a photoreceptor 1 at the interval of about 300mum, and rotate at a peripheral speed similar to the movement of the photoreceptor 1. A urethane blade 13, 14 having about 60 deg. hardness is used for coating each sleeve 11, 12 with each toner to 60-80mum thickness. |
