| 摘要 |
PURPOSE:To extend service life of a developer by preventing color mixing, by outputting to a driving part a driving stop command for one of the developing devices which became unnecessary accompanying an input of a monochromatic printing command. CONSTITUTION:The titled device has a first developing device 5' for allowing a first toner to adhere to a photosensitive body 1, and a second developing device 5'' for allowing the second toner (toner whose color tone is different from that of the first tone), and provided with a driving part 12 for executing a driving control of the developing devices 5', 5'', and a control part 13 for outputting to the driving part 12 a driving stop command of one developing device 5'' which becomes unnecessary by following up an input of a monochromatic printing command. The control part 13 decides a printing command from a host signal, drives only the developing device 5'' of the pre-stage in case of monochromatic printing, and stops driving of the developing device 5'' of the post-stage. Accordingly, a toner does not adhere to a magnetic roller of the developing device 5'' of the post-stage, and it does not occur that the surface of the photosensitive body 1 is rubbed with the toner (developer) of the developing device 5''. In such a way, a replacement period of the developer due to a color mixture can be extended.
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