| 摘要 |
PURPOSE:To reduce the change of repeated use of a used developing agent so as to eliminate the density unevenness in the axial direction of a developing sleeve, by making an upper and lower screws of two passages to independently function in such a way that the one of the passage divided into a top and bottom sections is used as a developing agent supplying path to the developing sleeve and the other is used as a used developing agent carrying path. CONSTITUTION:An upper and lower passages 2a and 2b are formed in a developing device 2 with a horizontal partitioning plate 5 and their both end sections A and B are extended longer than a sleeve 3. Then the partitioning plate 5 is cut at the end sections of screws 6 and 7 and coupling sections 5a and 5b are formed. When the sleeve 3 is rotated in the same direction as the rotating direction of an image carrying body 1, a used developing agent drops to the lower passage 2b from the coupling section 5b of the extended section B and is carried to the extended section A by the lower screw 7. The used developing agent carried to the extended section A is pushed up to the upper passage 2a by means of a shaftless screw 10 provided in the coupling section 5a. When a toner density decline signal is transmitted from a detector 9 while the used developing agent is pushed up, a prescribed quantity of new toner is supplied to the upper passage 2a from a port 11 while it is sufficiently stirred and mixed by means of the screw 10 and carried by the screw 6 along the sleeve 3 for development.
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