GB1344890A - Electromagnetic transducers - Google Patents

Abstract

1344890 Magnetic transducers INTERNATIONAL BUSINESS MACHINES CORP 21 Aug 1971 39316/71 Heading G5R A read/write magnetic transducer has a conductive strip 12 sandwiched between two laminar magnetizable members 13, 14 which are joined magnetically at 17 to form a yolk 15 and a transducing gap 16, the yolk having edge portions 18 and a centre portion 19 which are constructed so that electromagnetic induction occurring in the reading process is relatively less efficient at the gap edges than at the gap centre. The edge portions 18 may form a relatively high reluctance path, or alternatively may produce a greater leakage of flux. As shown, the edge portions 18 of one or both members 13, 14 are of a material (e.g. a Ni-Co-Fe alloy) with a lower permeability than the material (e.g. a Ni-Fe alloy) of the centre portion 19. Alternatively, slots (21), (22), Fig. 2 (not shown); (50), Fig. 4 (not shown); (70), Fig. 6 (not shown), may be provided in one member of the yolk. Alternatively, Fig. 3 (not shown), the edge portions (38) are closer together, and extend further back from the gap, than the centre portions (39). The edge portions may be magnetically joined together beyond the strip as at (51), Fig. 4 (not shown), or through holes (91) in the strip, Fig. 7 (not shown), to form shunt paths. The transducers are made by layer deposition on a substrate such as glass, the members 13, 14 being electroplated and the copper strip 12 being evaporated thereon. A ferrite block may alternatively be used as both substrate and as member 14.