Abstract: An electron beam tube assembly has a pattern of conductors 20 at least partially provided by being deposited on a major surface of a face plate 16, of the tube 13, the conductors to extend from within the tube 13, at least to an edge 18 of the face plate spaced from the remainder of the tube, and at the edge providing a plurality of exposed, spaced apart ends 22, comprising electrodes, the opposite end of each conductor being coupled by resistive material 28 deposited on the tube to a conductive coating 26 also on the tube, the coating being maintained at a high positive potential with respect to the cathode, in response to the information signals, supplied to the electron beam deflection means 41 and/or to the electron beam modulation means 42, electrical discharges occur to mark an associated sheet 30 of material sensitive to electrical discharges each such electrical discharge being when the electron beam impinges on a conductor.