| 摘要 |
1,199,462. Electroluminescence. RANK XEROX Ltd. 28 Sept., 1967 [29 Sept., 1966], No. 44121/67. Heading C4S. [Also in Division G2] A method for amplifying charge variations in a latent electrostatic charge image comprises forming the image on a surface of a photoconductive material contiguous to or forming a field effect semi-conductor layer, contacting the surface with an electroluminescent layer and applying a potential to produce an electric field at the e.1. layer having an intensity in accord with the conductivity of the f.e.s.c. layer; preferably the f.e.s.c. is able to retain the surface charge when current passes, e.g. Zn, Cd or Pb oxide. A sheet of paper 15 coated with ZnO 17 is placed on a grounded conductor 35, the ZnO is uniformly negatively charged then exposed to an optical image causing discharge over illuminated areas resulting in the reversed charge image. The paper is then placed on an e.1. layer 7 and A.C. applied between adjacent electrodes 8 below the e.1. layer. In illuminated discharged areas the conductivity of the f.e.s.c. ZnO is high and a high current passes through the e.1. layer via the ZnO generating light which results in a further discharge of the charge image. In areas not illuminated the high negative charge reduces the conductivity of the ZnO and little or no current flows through the e.1. material which therefore emits no light and the charge is retained. The process is stopped by removing the paper or stopping the current when it reaches a predetermined value. If the ZnO is on a conductive A1 substrate the electrodes 8 may be replaced by a conductive layer and potential applied between this and the substrate. In another embodiment the latent image is formed on a layer of photoconductive vitreous Se on a f.e.s.c. layer, e.g. vacuum deposited n-type CdS, the layers being separated by an insulating layer. If the p.c. layer is initially charged positive areas of high charge have a high conductivity resulting in decreased contrast. The e.1. material is ZnS: CuCl 2 or ZnS, ZnSe: Cu in P.V.C. resin and electrodes 8 are vapour deposited An or Cu.
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