GB1409735A - Ionpermeable control member for an imaging system - Google Patents

Abstract

1409735 Electro-photography HORIZONS Inc 24 Aug 1972 [27 Aug 1971] 39561/72 Heading G2H [Also in Divisions H1 and H4] Apparatus for preparing an electrostatic image conforming to a radiant image comprises an electrically conductive element 16 (see Division H1) on to one side of which may be projected a radiant image, an image receiving member 12 located on the other side of said element, and a corona source 18 located on said one side of said element and adapted to spray ions through said element on to said member. The element 16 defines an array of ionpermeable locations and is coated with photosensitive material asymmetrically disposed relatively to said locations. The asymmetry is stated to improve the contract ratio, i.e. the ratio of ion current passing through the screen between illuminated and non-illuminated conditions, as compared with known evenly coated screen. The image receiving member 12 may be conducting paper having a thin dielectric coating 14 and supported on a conductive platen 10 maintained at a selected potential by a power supply 21. Corona discharge wire 18 is connected to power supply 20. Projector 22 focuses an image to be copied on screen 16. The power supplies are connected to electronic controls 24. The projector 22 may be replaced by any suitable light projector e.g. a cathode-ray tube projection system or by a projector using other forms of radiation, e.g. x-rays, γ-rays, α and # particles. The corona wire 18 or wires may be moved relative to the screen 16 Fig. 5, (not shown) during exposure to eliminate image defects due to mesh irregularities, and the screen may be wound on rollers to provide both movement and a continuous supply of new screen Fig. 6, (not shown). An additional vibrated screen may be provided between screen 16 and the chargeable member Fig. 11, (not shown). A number of different forms of apparatus are described Figs. 7-10 and 12, (not shown) for producing colour images or involving successive or simultaneous charging and developing utilizing liquid, normal or dry aerosol developers to produce a final image on plain paper. Images may also be formed on a deformable thermoplastic film and developed by softening the film by exposure to either heat or solvent vapours.