Patent GB-943401-A (GB)
IPC: G03B27/30
Abstract: 943,401. Copying documents; stencils. IMAGIC PROCESS Ltd. Feb. 4, 1960 [Feb. 11, 1959; Sept. 22, 1959], Nos. 4809/59 and 32261/59. Heading B6C. [Also in Division G2] In a method of producing a copy of an original design, the original to be copied is located in contact with a receiving surface and is subjected to heat in such a way that oil is caused to evaporate from the original over areas representative of the original design and to condense on the receiving surface to form an image. The original may contain the oil imagewise, as in newsprint, or it may be applied imagewise, as from a typewriter ribbon, carbon paper or pencil, in which cases any form of heating may be applied; or the oil may be applied over the whole surface over the image, or previously to the original sheet, or to the rear of a translucent sheet, in which cases radiant heat is applied by an infra-red lamp to be absorbed in the image areas. The original and the copy may be in strip or sheet form, opaque or translucent. The oil forms on the copy sheet a latent image, which is developed with powder or liquid, forming a visible or invisible image, and then fused by an infra-red lamp or offset on to a further sheet or lithographic plate and fused thereto. The developer may be powdered ink comprising a pigment and a binder such as shellac, colophony, epoxy or polyester resins. Liquid developers may be ferrous sulphate or other ferrous salts, potassium bichromate, ammonia or water, which produce colour where the latent image is pyrogallic acid or tannic acid in an oil carrier. The oil should be colourless and may be an essential, vegetable or mineral oil, glycerine, glycols, hydrogenated terphenyls, chlorinated diphenyls and polyphenols kerosine; or pyrogallic or tannic acid may be used in the oil acting as a carrier; the oil is applied by roller. The copy sheet may be paper; for offsetting cellulose acetate or " Cellophane " (Registered Trade Mark) are suitable. Where the copy sheet is translucent for reverse viewing, the image may be covered with a white coating of paper, plastic film or pigment. The copy is aircooled to cause condensation of the oil. The original and copy may be laid on a flat support and traversed by an elongated infra-red lamp, or the original may pass round or be attached to a rotary drum which moves it and the copy sheet past a stationary lamp. By making the copy on a stretched elastic sheet of latex or vinyl plastic which is relaxed before offsetting, or on a relaxed such sheet which is stretched before offsetting, reduced or enlarged copies can be produced. The original 1 is fed by rollers 3, 2, the latter applying oil, round a drum 10 in contact with a copy strip 11 and past a lamp 20 and fan 22. The copy strip then passes through a developer hopper 26 having a diaphragm 27 vibrated by a driven hexagonal member 30 and past a fusing lamp 32. For offsetting, a receiving strip is fed with the strip 11 between the roller 31 and a heated pressure roller or an unheated pressure roller and then past a fixing lamp. The strip or strips are cut into sheets by blades 37. The drum 10 may be transparent and contain the lamp. The strip nearer the lamp must be translucent. If the copy is to be made on separate sheets, the latter are inserted manually. For forming a litho plate, the latter may be heated before contact with the copy or the two heated together. The plate may be fed manually to the roller 31 and co-operating pressure roller, and may be supported between the copy strip and a further strip fed from a reel to the rollers. For making several copies, the original is clamped to the drum, or if it is too long to an endless belt passing round the drum, and intermittently oiled thereon. Stencils.-An image of ink or powdered graphite is developed on the strip 11 and offset on to a coated stencil blank. The blank is then inverted in the machine past the lamp 20, and the coating is displaced locally; alternatively, the image is developed by finely powdered pyrogallic acid, tannic acid or gum, and pressed against a moistened stencil blank, the coating being removed locally by mechanical adhesion. Specifications 943,402 and 943,403 are referred to.