GB797942A - Improvements in or relating to multiple magnetic reproducing heads for films having multiple magnetic sound tracks - Google Patents

Abstract

797,942. Magnetic recording reproducing heads. SIEMENS & HALSKE AKT.-GES. Oct. 11, 1954 [Oct. 9, 1953], No. 29167/54. Class 40 (2). A multiple magnetic signal reproducing head for film having multiple magnetic sound tracks comprises a plurality of individual heads each having at least one non-magnetic gap and being formed from two half-heads each comprising a stirrup-shaped core 1 of laminated sheet metal or of ferrite; respective half-heads of each head are secured in two symmetrical casing components or half-blocks 5, 5<SP>1</SP> which are joined together in the plane 12 of the gap to form a unit from which project the gap defining poles of the cores. In the embodiment shown the half-heads are moulded into respective half-blocks 5, 51 of shrink-resistant electrically-insulating moulding material but in another embodiment, not shown, they are secured by moulding or adhesives in moulded or milled guide slots in respective pressure or die-cast casing components of synthetic resin, and in both embodiments hollow spaces 6 possibly subdivided by cross-pieces 7 may be provided to avoid shrinkage. Windings 2 are mounted on the cores and may be connected to connection tabs 11. Adjacent pairs of half-heads may be embraced by E-section screening means 8, 9, Fig. 3, of high permeability sheet material and having a tab 10 for connection to earth. Between each adjacent pair of half-heads there also may be provided a screening plate 13, Fig. 4, which extends into the area of the gaps and may be part of or connected to the screening means 8, 9. To assemble, the surfaces of the ends 3, 4 of the cores are ground smooth, thin copper-bronze foil is inserted between one or both ends 3, 4 of each head core, the two half-blocks are joined together by adhesives or screws, not shown, and the projecting poles are ground to be all of the same height. The cores may be earthed by a metal foil, not shown, inserted between each core 1 and winding 2. The assembled block as shown in Fig. 4 is secured by moulding material in an enclosing metal cup, not shown, having a, securing flange and within which some soldering tabs 10, 11 may be connected together, the remainder projecting therefrom. There may be a further screen placed around the block and within the cup such screen having an electrically insulating goil on its outer surface. Reference has been directed by the Comptroller to Specification 721,755.