Patent GB-1478349-A (GB)
Title: Magnetic read-record head
IPC: G11B5/187
Filed: 1974-09-24
Abstract: 1478349 Magnetic heads HEWLETTPACKARD CO 24 Sept 1974 [12 Oct 1973] 41521/74 Heading G5R A magnetic head assembly has a plurality of magnetic transducers each having a transducing gap 84, Fig. 10, defined between a respective magnetic core 28 carrying a coil 30 and a respective magnetic flux return core 48, cover 28 having magnetic shields 36 therebetween and being supported by a frame 22 having a support bar 16 engaging notches 32 in cores 28 to provide mutual alignment of the pole faces thereof, and flux return cores 48 being supported and positioned by a frame 62, Fig. 8, having a flat surface 68 in the working face of the head assembly. A multitrack head with plural read transducers and plural write transducers is formed by an assembly 45, Figs. 5, 10 supporting wound magnetic write cores 28 and a similar assembly of wound read cores, the two assemblies being located one on either side of a central assembly 62, Figs. 8, 10 supporting flux return core parts 48 for the read and write cores. The assemblies 45 are each made by fixing a plug (14), Fig. 1 (not shown), carrying the bar 16 into a cylindrical cavity 12 of a body (10) and machining these parts to expose cavity 12 and form a grooved 26 support surface 24 at the working face 44. Wound cores 28 are then mounted in the exposed cavity 12 of the frame 22 so formed with their core notches 32 engaging bar 16 and their pole piece ends 34 on surface 24, magnetic shields 36 engaging in grooves 26 in surface 24 and in grooves 18 in bar 16 being located between the cores 28. The assembly is then potted in epoxy. The central assembly 62, Fig. 8, is formed by mounting U-shaped magnetic flux return core parts 46 with U-shaped magnetic shields 54 on a frame having portions 64, 64<SP>1</SP> separated by a magnetic shield 66 so that the legs 48 of parts 46 engage surfaces 70 of portions 64, 64<SP>1</SP>, the legs 56 of shields 54 fit in slots 72 of faces 70, and gauge tabs (52), (60) of parts 46, 54 engage the working face 68 to properly align the parts 46, 54 therewith, This assembly is then potted in epoxy and the web portions, including the gauge tabs, of the U-shaped parts 46, 54 are removed. Grooves 76, 76<SP>1</SP>, Fig. 10, are then cut in surfaces 70 and through legs 48, 56 parallel to face 68. The assemblies 45 are then located one on either side of the flux return core assembly 62 so that each read core is defined by a wound core part 28 of one assembly 45 and one leg 48 of a respective (originally U-shaped) part 46 and a corresponding write core is defined by a wound core part 28 of the other assembly 45 and the other leg 48 of that part 46. The depth of the transducing gaps 84, which may be filled with non-magnetic material 86, is defined by the distance of working face 68 from the one edge 77 of grooves 76, 76<SP>1</SP>. The core parts 28, 48 may be in contact at back surfaces 88 or separated by a thin piece of plastics insulation. The frames 22 of assemblies 45, and the parts 64, 64<SP>1</SP> of the return core frame may be of brass, aluminium, copper or tellurium copper, the cores 28, 48 may be laminated, and the shields 36, 66 may be of Munetal laminated with copper.