Minolta Camera Kabushiki Kaisha

Hiroshi Ozawa

Masashi Sakamoto

Hidekazu Nakagami

Masao Tokumoto

An image forming apparatus provided with a toner replenishing device attachable to a position of any one of a plurality of developing units. The toner replenishing device replenishes toner to another developing unit through the space of a developing unit to which the toner replenishing device is interchangeably attached.

Image forming apparatus having toner replenishing device interchangeable

An image forming apparatus equipped with a sensor for detecting the requirement of replenishment and exchange of expendable supplies, parts and the like and an image forming structure capable of forming on the same sheet of paper a prewarning image in addition to a regular image formed corresponding to an original or image information to be copied. The image forming structure receives different control depending on whether or not the sensor is detecting the requirement of replenishment and exchange, wherein if the sensor is not detecting the requirement, it forms only a regular image while when the sensor detects the requirement, it forms a prewarning image together with a regular image thereby indicating the requirement of replenishment and exchange by the prewarning image on the same sheet on which a regular image is formed.

Image forming apparatus

A method of controlling toner concentration for an electrophotographic copying apparatus in which voltage to be impressed on a toner collecting or recovering roller disposed to contact a flow of a developing material after developing is arranged to vary so that a voltage lower than that for a reference density image is applied thereto for an image having a high density requiring a large toner consumption, while a voltage higher than that for the reference density image is applied thereto for an image having a low density requiring a small toner consumption.

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Osaka, Japan

Hiroshi Ozawa