Patent GB-604012-A (GB)
Title: Improvements in printing and mechanism therefor
IPC: B41M1/42
Filed: 1945-11-20
Abstract: 604,012. Printing. GOSS PRINTING PRESS CO., Ltd. Nov. 20, 1945, No. 31254. Convention date, Nov. 22, 1944. [Class 100 (ii)] In a process of printing electrically by the use of a field of force either magnetic or electrostatic for transferring ink in the form of a pattern or design from an inked member to a sheet such as is described in U.S.A. Specifications 1,820,194. and 2,224,391 means are provided to control the current flow at the instant of ink transfer. As shown in Fig. 1, the web 21 to be printed passes over rollers 22a, 22b, 22c, and moves across a pair of gap-defining members 19, 20 of high specific resistivity and relatively low dielectric constant such as high quality plate glass. Below the gap is arranged a metal printing-cylinder 10 inked by rollers 13c, 13d and above the gap is arranged a cylinder 15 formed of an earthed inner metal cylinder 15a of cast steel, and an outer surface of an electrical resistance material having a high dielectric constant such as glass or ceramic material. The cylinder 15,contacts with a cylinder 16 formed with a conducting inner layer of cast steel 16a which is connected to a variable high voltage supply 27 and is surrounded by a layer of a flexible conducting material 16b such as conductive rubber. The variable voltage is obtained from alternating current lines 25, 26, a rectifier and step-up transformer, and in addition to varying the voltage the current flow across the printing-gap is controlled by the speed of the rollers 10, 15, 16 which are driven at a common speed, and by the area of contact of the rubber coating with the roller 15 and the distance of the gap between the rollers 10, 15 which is adjustable by mounting the rollers 15, 16 in a frame 14 movable by screws 23c and held in adjusted position by screws 23a, 23b. The current is controlled so that the printing gap is in a state of ionization, but so that arcing does not occur. In a modification the members 19, 20 are dispensed with and the web contacts with the roller 15 over a substantial arc. In a further modification, Fig. 4, the ink supply roller is a plain roller, and the design is formed on a roller 40 arranged in a metal housing 41 separated from the roller 40 by means of a layer 41a of glass and having a high dielectric constant. The roller 40 is connected to the source of variable voltage. and is formed of a metallic design part 40a connected to an outer layer 40b by means of a layer of silver or copper, the layer 40b being made of red sealing wax, or of glass. in which is dispersed a metal salt of lead or copper, or titanium oxide. The ionization takes place through a gap between members 42, 43 similar to 19, 20, Fig. 1. In a further modification similar to Fig. 4, a design roller replaced the plain roller 48, and in a housing similar to 41, Fig; 4, is arranged a combined roller having a metal centre connectedto the variable voltage and surrounded by a layer of glass having a metal salt dispersion agent. Between this layer and the outer housing is a layer of glass or polystyrene or other material having a high dielectric constant.