GB1021882A - Improvements in or relating to electrophotographic apparatus - Google Patents

Abstract

1, 021, 882. Electro-photographic processes. RANK XEROX Ltd. Aug. 3, 1962 [Aug. 11, 1961], No. 29924/62. Heading G2H. [Also in Division H1] An electro-photographic plate is capable of being uniformly changed at its first surface which is insensitive to visible light, and may be selectively discharged to form a developable electrostatic latent image at the first surface by a radiation pattern applied to the second surface. Those plates described which are to be used with visible (or near visible) light have the photo-conductive layer with its second surface in contact with a transparent support. In one process the plate is mounted in a slide holder fitted with a dark slide to cover the light sensitive surface. The plate is corona charged in the holder with the slide in position and then exposed with the dark slide removed in a light-tight camera. The dark slide is replaced and the plate may then be subjected to the further steps of development and image transfer in ordinary daylight. In the apparatus of Figure 4 (not shown) the plate 10 is held within a box 50 with its light-insensitive face exposed through an aperture. An original may be placed on side 52 and swung into position in the box. The plate is charged by a corona discharge from grid 57 and then exposed by means of the optical system 53, 54, 55 in the box. Lips 58 on the box hold developer powder so that cascade development may be achieved by rocking the box. The charging grid 57 is pivoted so that it may be swung clear for the insertion of paper and then swung back for use in transfering the image from plate to paper. In the apparatus of Figure 5 (not shown) the plate 10 may be moved to a position within the box 50 for initial corona charging and then to a position flush with the walls of the box for development, as with the apparatus of Figure 4. In this case, however, a roller 41 connected to a high voltage supply is used for the image transfer process. With both these apparatus the operator may work in ordinary daylight. In xero-radiography using a plate sensitive to X-rays, y-rays, #-rays, or to other high energy radiation the support may be made opaque to visible radiation so that the plate may be used in daylight. Exposure to the high energy radiation may take place at the first surface of the plate or at the second surface if the support is sufficiently transparent to the high energy radiation.