Patent GB-740162-A (GB)
Title: Improvements in or relating to method of and apparatus for printing
IPC: G03G19/00
Filed: 1952-11-28
Abstract: 740,162. Printing processes etc.; printing- surfaces. STROMBERG.CARLSON CO. Nov. 28, 1952 [July 26, 1952], No. 30207/52. Class 100 (2). A magnetic printing method comprises magnetically impressing a pattern on a magnetic member, coating the member with substantially dry comminuted magnetic substance which adheres with greater density to the pattern areas, and bringing the magnetic member and a dry non-sticky material to be printed into contact with sufficient pressure to cause transfer of comminuted magnetic substance to the material, the transferred material being in a greater density in the pattern areas, so as to reproduce the pattern on the material. A magnetic pattern is impressed on the surface of a continuously rotating drum 3, Fig. 1, by a recording head 6. Comminuted magnetic substance is applied to the drum surface from a hopper 8, and adheres in greater quantity to the pattern areas. A cylinder 1 rotates the drum by friction and also feeds web material 10 to be printed on in contact with the drum, so that a large amount of the magnetic substance is fed to the web. The web may have a wax or paraffin coating, which is melted by a heated roller 16 so as to retain the magnetic substance, the remainder of which is removed by a suction device 18. A magnetic eraser 21 removes the pattern from the drum. The eraser 21 and head 6 are rendered inoperative for repeat printing. The drum has a peripheral portion 4 of permanent magnetic material. The magnetic substance may be a carbonyl iron powder, consisting of 98.1-98.7 per cent iron, 0.6- 0.8 per cent carbon, 0.1-0.3 per cent oxygen, and 0.55-0.75 per cent nitrogen, or may be an oxide of iron. The web may be heated by an infra-red lamp to melt the wax. Alternatively to the use of wax or paraffin, the web may be a rough fibre which will hold the material, or may be sized with a substance which reacts with the powder to fix and, if necessary, intensify the iron particles. Instead of a drum, a reel of magnetic recording tape may be used, or an endless belt of such tape. The recording head may comprise a concave block 23, Fig. 3, of insulating material such as plastic, having grooves to accommodate seven loops of insulated wiro 30-36, capable of being selectively energized to form any of the numerals 0-9. The loops are selectively energized by depressing keys, which energize relays of a translator through the contacts of which circuits are completed for discharging previously charged capacitors through the selected loops, thus providing a magnetic flux of short duration to give a sharp image. Additional loops, forming an arrangement as shown in Fig. 7, may be provided to enable printing of either numerals or block letters. The relays may alternatively be energized by means of a perforated tape reading machine. Instead of relays, vacuum tubes or transistors may be used. In another form, Fig. 10, the loops are replaced by members 80 surrounded by coils 79, to produce dots selectively arranged to form characters. A number of heads may be arranged across the drum to form a complete line pattern. In one form, Fig. 11, the heads 81-86 for forming a complete line pattern are arranged along a helical line 102, and a sequential switch means connects the translator successively to the various heads, the switch means being synchronized with the drum so that the resulting line is produced transversely across the drum. Specification 686,009, [Group XL (b)], is referred to.