GB837034A - Improvements in or relating to duplicating machines - Google Patents

Abstract

837,034. Copying documents. CARIBONUM Ltd. May 9, 1958 [May 29, 1957], No. 17086/57. Class 100(2) A duplicating machine comprises a rotatable cylinder for supporting a mirrorscript master sheet carrying a pressuretransferable coating which comprises a colourless acid-sensitive dyestuff derivative, a pressure roller arranged to be driven by contact with the rotatable cylinder and thereby to subject a copy sheet carrying an acid fixing substance for the dyestuff derivative and fed between the cylinder and the roller to pressure contact with the master sheet; and a source of heat disposed beyond the rotatable cylinder in the direction of advance of the copy sheet for raising the temperature of the copy sheet almost immediately after its pressure contact with the master sheet so as to cause a colour-forming reaction to occur thereon. After passing between the cylinder 10, Fig. 1, and roller 14, the copy sheet passes between a roller 15 driven from the roller 14 and a roller 16 driven by friction from the roller 15 and heated by an electric coil 17. A housing 18 comprises a hinged portion 20 to allow access to the cylinder, a baffle plate 32 to lessen the passage of heat to the master sheet, openings 27, 30 for entry and exit of the copy sheet, and openings 21 to dissipate heat from the machine. In another form, Fig. 2, the copy sheet is carried by a conveyer comprising tapes or a belt 41 under infra-red lamps or heaters 47 and over a heating element 47a. The lamps or heaters 47 may be replaced by one or more hot air jets directed by a fan, ducts and heaters on to the copy sheet, the air being at 200-350‹C., or by an open coiled wire heater, in which case the papercarrying base and the inside upper surfaces of the housing are covered with polished aluminium foil to intensify the heating effect, the heater and sheet-transporting surfaces being enclosed in a separate cover lower than the housing. The roller 14 can be moved away from the cylinder 10 during attachment of the master sheet, its spindle 14a being mounted on a pivoted lever. In another form, the source of heat is a hot plate containing an electric heating element mounted above the conveyer, and the cylinder 10 is arranged below the roller 14, the lower right-hand part of the casing being hinged. Specification 835,930 is referred to.