GB818811A - Improvements in or relating to flux responsive magnetic reproducer heads - Google Patents

Abstract

818,811. Magnetic reproducing heads. CLEVITE CORPORATION. Oct. 12, 1955 [Nov. 26, 1954], No. 29059/55. Class 40 (2). In a flux responsive magnetic reproducer head comprising a magnetic core in the form of a substantially closed figure and having an output coil wound around the core and spaced from a reproducing gap in the latter, there are provided excitation means which intersect the core at a location between the gap and coil and within the path of the major portion of signal flux, from a magnetic record medium, within the core. As shown in Fig. 1, the core comprises two legs 11, 12, of either laminated high permeability or electrically non-conductive magnetic material, each carrying respective output coils 15, 16 and joined together at a butt joint 14 and at the reproducing gap 13 which is filled with aluminium or copper foil; the excitation means comprises a single loop of an electrical conductor 19 fed with A.C. or interrupted D.C. of frequency several times that of the highest signal frequency to a reproduced and disposed perpendicularly to the core leg. The joint 14 may be embraced by a conductor 20 fed with D.C. to generate a bias field. In a multichannel head unit a plurality of such heads may be associated with a common excitation and a common bias field conductor, and they may be supported in aligned parallel relationship by a common plastic housing. The excitation means alternatively may comprise a magnetic conductor 47, Fig. 4, in the form of a loop closed through the two legs of a single head or all the legs 40a, 40b, &c. of the plurality of heads and embraced by winding 48 fed with A.C. or interrupted D.C. excitation current. To reproduce signals of very long wavelength the head, Fig. 9, introduces an artificial magnetic potential difference by making the core on opposite sides of the gap 83 magnetically dissimilar; as shown, this is effected by making the pole tips 84, 85 of different size and shape but alternatively the excitation conductor may intersect only one of the core legs. Reference has been directed by the Comptroller to Specifications 709,655, [Group XXXVI], 721,755, 737,497 and 771,383.