| 摘要 |
PURPOSE:To surely separate and remove toner mixed into each developing device of the 2nd and subsequent developing devices from the next developing device ahead, by constituting rotatably the magnetic roller at the inside of the developing roller provided in each developing device of the 2nd and subsequent developing devices. CONSTITUTION:Each of plural developing devices arranged in the vicinity of a photosensitive drum 1 has a developing roller 41 provided with a rotatable magnetic roller 41b in its sleeve 41a and bucket roller 42 and, when, for example, toner of the 1st color charged with positive polarity in the 1st developing device mixes into the 2nd developing device, the 1st color toner is repeatedly hotly rotated and moved upside down together with the 2nd developing agent on the sleeve 41a by the magnetic roller 41b which is rotated at a high speed in the direction shown by the arrow in the sleeve 41a and frictional charging is sufficiently performed between the 1st color toner and 2nd carrier. Therefore, the polarity of the 1st color toner is inverted to negative and, as a result, the mixed 1st color toner is separated and scattered from the sleeve in the 2nd developing device by centrifugal force, etc. |
