Hitachi Koki Co., Ltd.

Hiroshi Tsunoda

Yoshitaka Fujinuma

Masayuki Ainoya

Yuichiro Suzuki

An image forming apparatus includes a developing unit having a photoreceptor, for making an electrostatic latent image on a surface of the photoreceptor visible as a toner image. A toner hopper stores toner to be supplied to the developing unit and a cleaning device removes and recovers the toner remaining on the surface of the photoreceptor after the toner image has been transferred onto a recording material. A toner transporting passage is connected between the cleaning device and the toner hopper, through which the toner recovered by the cleaning device is returned to the toner hopper. A toner exhausting port is disposed at a part of the toner transporting passage, from which the toner being returned from the cleaning device side is exhausted outside the toner transporting passage. An opening and closing member selectively opens or closes the toner exhausting port, wherein an inner diameter of the toner exhausting port is made larger than that of the toner transporting passage.

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Ibaraki, Japan

Hiroshi Tsunoda