| 摘要 |
1496473 Copying machine INTERNATIONAL BUSINESS MACHINES CORP 9 April 1976 [27 May 1975] 14642/76 Heading G2H In an electro-photographic copier of the two cycle kind in which an image developed on a photo-conductor 12 is transferred to a substrate, a single corona discharge device 18 acts alternately as a transfer and a pre-charge device and a further single corona discharge device 22 acts alternately as a pre-clean and a final charge device, the charge deposited on the photo-conductor 12 by the device 22 being controlled such that, in an imaging operation, it reduces a pre-charge formed on the photoconductor by the device 18 to a level suitable for exposure to form a latent image, and, in a cleaning operation, it reduces charges remaining on the photo-conductor after a transfer operation at the device 18 location to substantially zero. Device 18 comprises a corotron, whereas device 22 comprises a scorotron the control grid 24 of which is switched to one of two controlled voltage sources according to which of its two alternative functions is required in the particular cycle in which it is operating. |
