| 摘要 |
A method of electronically photocopying a document in which the copies produced by a series of copying cycles are of uniform contrast. At the start of a photocopying sequence and before any image recording, the photosensitive drum is erased by a lamp and then charged with a charge corotron. This rotating charge is then depleted by a "prefatigue" source of both infrared rays and visible light. The prefatigue source lowers the initial charge density to the level of the subsequent charge densities produced by the normal charge fatigue of the photosensitive material. This "preconditioning" cycle is completed through one revolution of the recording drum, prior to the initiation of normal copying cycles and prior to any imaging upon the drum. Thereafter a series of one or more normal photocopying cycles are performed with perhaps multiple recordings of images on the already preconditioned drum. Thus, the charge densities are uniform throughout the series of copying cycles after the preconditioning and the copies produced thereby are of uniform contrast.
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