GB608902A - Improvements in or relating to printing apparatus - Google Patents

Abstract

608,902. Printing processes. GOSS PRINTING PRESS CO., Ltd. March 1, 1946, No. 6506. Convention date, March 1, 1945. [Class 100(ii)] In printing-apparatus such as described in Specifications 602,985 and 604,012, in which ink is transferred from an inked member to the web or sheet by an electric field of force, the field of force is set up by widely spaced electrode members. In one form, Fig. 1, a source 20 of high positive potential which may be of the order of 150 to 200 thousand volts is connected to an electrode 19 formed with a knife edge embedded in a rigid glass or other dielectric member 21 the upper portion of which encloses all but the lower edge of the electrode 19, and which is formed with depending spaced portions 21a, 21b. The web 14 passes beneath spaced dielectric members 16, 17, and the distance apart of the printing-cylinder 10 which forms one electrode and the electrode 19 is from 6 to 8 inches. A minimum distance of two inches is desirable, and also a minimum voltage drop of 50,000 volts. The web is distanced from the member 10 less than one-tenth of the distance between the electrodes. In Fig. 3, the electrode 39 is enclosed in a dielectric member 31 with parts 31a, 31b which combine the functions of the parts 21a, 21b, and 16, 17, Fig. 1. In a modification the whole apparatus including the feed and wind-up rolls, and a drying-apparatus is exhausted by means of an electrically are enclosed in a chamber from which air driven suction device, and in Fig. 5 the printing members are enclosed in a similar chamber 76, but the web 64 is fed in by rubber rollers 81 and delivered by rubber rollers 82 driven at a slightly faster speed to maintain the web taut, the rollers 81, 82, being mounted in a housing having arcuate surfaces adapted to contact the surfaces of the rollers throughout the majority of their peripheral lengths so as to prevent passage of air into the chamber 76. In a further modification, Fig. 8, the web 94 is led below gap-forming members 96, 97, and below the member 96 a plate 120 is arranged which is coated with radioactive material 120a, which ionizes the air in the space between the electrodes and assists the passage of the electric current, and increases the glow effect. U.S.A. Specifications 1,820,194, and 2,224,391, also are referred to.