摘要 |
A developing device for electrophotographic copying machines using a powder developer avoids the problems associated with a flap-controlled distribution aperture in a hopper holding powder for transfer to an image transfer drum by using a sliding plate-type shutter to control the powder flow. The aperture lies adjacent to the apex of the drum and in a plane inclined to the horizontal. The shutter in its sliding movement is guided against the lower longitudinal edge of the aperture, and the leading edge of the shutter, in its closing movement, moves in an upward path slicing into the powder stream. The shutter is preferably held against the guide of the aperture by the force of spring means acting on the shutter.
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