To securely prevent adverse influence on various nearby devices by preventing toner from being jetted out with air increasing in pressure on the downstream side of the conveyance path of a toner conveyance device applied to the cleaning device of a copying machine.
The upstream conveyance path part 69 of each image formation station is provided with a 1st return pipe 66.... While one end of each 1st return pipe is made open to a downstream end upper position corresponding to the anti-gravitation side of a discharge opening 62c of a dedicated conveyance pipe 62a, the other end is made open to the upper part of a conveyance part 60b of an upstream conveyance path part by penetrating the rear surface of a cleaning box 60, so that air which is compressed by being carried to the downstream side of the upstream conveyance part as toner is carried is returned to the upstream side of the upstream conveyance path part. A common conveyance pipe 62b is also provided with a 2nd return pipe 67. One end of this 2nd return pipe is made open to the upstream end of the common conveyance pipe and the other is made open at a halfway position of a connecting pipe 63a on the downstream side of the common conveyance path, so that the compressed air carried to the downstream side of the common conveyance pipe as the toner is carried is returned to the upstream side of the common conveyance pipe.
KADOWAKI HIDEAKI
HARADA NAOYUKI
YAMAMOTO HIRANAGA
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