Thin film inductive transducer

• US 4,295,173 A
• Filed: 10/18/1979
• Issued: 10/13/1981
• Est. Priority Date: 10/18/1979
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Romankiw, Lubomyr T., Thompson, David A.
• Primary Examiner(s): Eddleman, Alfred H.
• Application Number:
  US06/083,182
• Time in Patent Office: 726 Days
• Field of Search: 360/125, 360/122, 360/123, 360/119-120, 360/126-127
• US Class Current: 360/125.53
• CPC Class Codes: G11B 5/3113 for improving the magnetic domain structure or avoiding the formation or displacement of undesirable magnetic domains
• CPC Class Codes: G11B 5/3116 Shaping of layers, poles or gaps for improving the form of the electrical signal transduced, e.g. for shielding, contour effect, equalizing, side flux fringing, cross talk reduction between heads or between heads and information tracks G11B5/3113, G11B5/245 take precedence
• CPC Class Codes: G11B 5/313 Disposition of layers

Abstract

A thin film inductive transducer head includes a magnetic circuit with a pair of legs and inductive coils. The legs are thinner near the pole tip than in the back gap region. The legs are also narrower in the pole tip region than in the back gap region. Resolution is enhanced by the thin pole tips and saturation of the yoke structure is avoided by increasing the cross-sectional area of the yoke structure away from the pole tip region.

Claims

1. A thin film inductive transducer for recording and reading magnetic transitions on a selectable one of a plurality of tracks on a magnetic recording medium, said transducer being of the type comprising two layers of a magnetic material forming a yoke structure that is activated by a conductor coil characterized in that

said yoke structure adjacent its one end comprises a pole tip region including a portion which is of a predetermined substantially constant width and a preselected substantially constant thickness, said predetermined width not exceeding the width of a track on the medium, said pole tip region extending a relatively short distance normal to the magnetic medium, thereby to maximize resolution of transitions during recording, and

said yoke structure comprises a back region which joins said pole tip region and increases in width from said predetermined width and has a back gap adjacent its wider end, the thickness of the layers of magnetic material in said back region being greater than the thickness of those layers in said portion of said pole tip region, thereby to oppose saturation of the yoke structure with applied current and enhance efficiency of the transducer by increasing the cross-sectional area of the yoke structure.

2. A transducer according to claim 1 wherein said coil contains more than one turn, at least all but one of which are mutually insulating from each other and from said yoke structure by means of electrical insulation material.

3. A transducer according to claim 3 wherein said coil includes gaps between windings tending to cause ripples in said insulation material, said insulation material being composed of polymer materials with a smooth upper surface so as to provide a substantially smooth supporting surface for the subsequently deposited upper magnetic yoke layer, whereby said ripples are substantially filled over by said polymer materials.

4. A thin film inductive transducer for recording and reading magnetic transitions on a magnetic recording medium,

said transducer being of the type comprising two layers of a magnetic material forming a yoke structure that is in a flux coupling relationship with a conductor coil characterized in that,

said yoke structure comprises a pole tip region and a back gap region which are integrally joined together,

said layers of magnetic material in said pole tip region being of a predetermined substantially constant width and a preselected substantially constant thickness,

said pole tip region extending a relatively short distance normal to the magnetic medium,

the thickness and the cross-sectional area of said layers of magnetic material in said back region being greater than the thickness and cross-sectional area of said layers of magnetic material in said pole tip portion,

whereby said smaller cross-sectional area pole tip portions increase magnetic resolution of magnetic transitions during recording/reading and said larger thickness and cross-sectional area back gap layers oppose saturation of the yoke structure and enhance efficiency of the transducer by increasing the permeance by maximizing the cross-sectional area of the back gap region of the yoke structure.

5. A transducer according to claim 4 wherein said coil contains more than one turn, at least all but one of which are mutually insulated from each other and from said yoke structure by means of electrical insulation material.

6. A transducer according to claim 5 wherein said insulation material being composed of polymer materials with a substantially smooth upper surface so as to provide a smooth supporting surface for the subsequently deposited upper magnetic yoke layer, whereby said ripples are substantially filled over by said polymer materials.