| 摘要 |
PURPOSE:To prevent wasteful consumption of copying paper and to improve operability at the time of exchanging a developing device by detecting the mounting condition of the developing device and stopping an image forming operation. CONSTITUTION:The developing device 5 in which a color toner is loaded is freely attachably and detachably constructed. The developing device 6 into which a black toner is loaded is fixed. A latent image, if formed on a photosensitive drum 2, is erased by external light and copying is disabled when the image formation is executed while the developing device 5 is not mounted to the machine or said device is removed from the machine during the copying operation. The mounting condition of the developing device 5 is, therefore, detected before the copying operation and during the copying operation and the copying operation is stopped when the absence of the developing device is detected. Processing by CPU based on the decision that the developing device 5 is removed is executed when the CPU detects that both reed switches 49, 50 on the copying machine side to detect magnets 47, 48 for identifying the toner color of the developing device 5 are off.
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