| 摘要 |
1, 011, 793. Developing electrostatic images. RANK XEROX Ltd. April 17, 1962 [May 1, 1961], No. 27679/65. Divided out of 1,009,509. Heading G2H. A latent electrostatic image, on a substantially uniformly charged photoconductive layer, formed by exposure to an image having image areas of non-uniform illumination intensity, e.g., a PPT tubes in which illumination intensity decreases towards its edges, is developed non-uniformly in inverse relationship with the non-uniformity of illumination intensity to produce a developed image of substantially uniform density. On one embodiment, an insulating donor sheet 61, Fig. 1, is non-uniformly charged by a corona discharge device as described in Specification 1,009,509 and then dusted by a powder cloud with electroscopic particles 62. The sheet 61 is brought into transfer contact with a scerographic plate that has been exposed to a PPI display of non-uniform illumination intensity to produce an image of substantially uniform density. In another embodiment a development electrode, Fig. 2 (not shown) has a series of concentric conductive rings 36 connected to tappings in a voltage dividing circuit. The voltage gradient across the concentric rings corresponds to that across a non-uniformly exposed xerographic plate previously given an initial uniform charge. A powder cloud of electroscopic particles deposits with greater density in areas having a greater potential difference between rings 36 and the electrostatic image to produce a developed image of substantially uniform density.
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