GB1156461A - Improvements in or relating to Printing Methods and apparatus - Google Patents

Abstract

1,156,461. Selective printing; printing apparatus. POSTMASTER GENERAL. 8 Aug., 1966 [10 Aug., 1965], No. 34184/65. Headings B6C and B6F. Apparatus for imprinting code marks on a surface comprises at least one printing pin 22, at least one container 1 holding printing medium, a reservoir 4 holding printing medium, means defining a flow path from the container(s) to the reservoir and back, means for holding the or each pin 22 in a rest position with its printing face located in the flow path, support means for supporting a surface to be printed adjacent the printing face(s) of the pin(s) such that the surface is normal to the direction of movement of the or each pin and means for moving the or each pin between the rest position and a printing position in which the face of the pin is in contact with the surface. Preferably a selected combination of such pins are moved into contact with the surface. As shown in Figs. 4 and 5, molten printing medium (heated by electric cartridge heaters in holes 60) is held in upper containers 1A and 1B. Cranked pins 22A, 22B are slidably mounted in guides 11A and 11B and also in guide tubes 11C and 11D. Printing medium flows from container 1A through orifices 12, see Fig. 4, over the printing surfaces of pins 22A into trough 66 and is then similarly directed over the surfaces of pins 22B and into reservoir 4 from which it is recycled by impeller 62 into container 1A. Plate 69 is apertured at 70A and 70B to allow the pins to contact a postal item to be printed, which item is held against plate 69. The pins may be moved by a requisite combination of rotating cams (28, Fig. 1) and following levers (24). When a pin has been moved into contact with the surface to be printed, further movement of its lever (24) comprises a spring (25) so that the pin does not damage the surface. In a preferred embodiment each pin carries a latching extension (50, Fig. 2) associated with a latch (52) and an armature (53) of a solenoid (54), such that rotation of the cam of a particular pin produces direct movement of the pin to its printing position only if the latch is disengaged by actuation of its solenoid. In other embodiments two reservoirs of printing medium, with the pins situated in the flow path from one to the other, are immersed in an electrically heated water bath or are each provided with heating coils. The printing medium may consist of particles of a solid phosphorescent material (e.g. a cyanuric acid-formaldehyde resin activated by carbazole sulphonic acid) dispersed in a carrier (e.g. a 5% solution of polystyrene or gum dammor in diphenyl).