| 摘要 |
PURPOSE:To record a two-color image well without color mixture, by charging frictionally a toner of the first color, which is mixed in a developing device for the second color, with a polarity different from that of the second latent image charge to prevent accumulation of the toner of the first color. CONSTITUTION:A positive-polarity latent image formed on a photosensitive drum 1 is developed in the first developing device 5 using a toner 4 of the first color having a positive polarity. The second positive-polarity latent image is formed on the drum 1 by exposure and is developed in the second developing device 8 using a toner 7 of the second color having a positive polarity. In this case, a part of the toner 4 on the drum 1 is peeled by a magnetic brush due to the device 8 and is mixed into the toner 7 of the device 8 and is charged frictionally by the carrier and the toner 7 of the device 8. Then, the mixed toner 4 which is charged frictionally in a prescribed order has a negative polarity and is not accumulated and is stuck to the nonimage part of the drum 1. Positive-polarity toners forming respective color images are transferred to a recording paper 9 by a negative-polarity bias voltage due to a charger 10 for transfer, and thus, good recording without color mixture is performed. |
