Inductive thin film head having improved readback characteristics

• US 5,170,303 A
• Filed: 04/30/1990
• Issued: 12/08/1992
• Est. Priority Date: 04/30/1990
• Status: Expired

• Current Assignee: Seagate Technology plc (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology plc (Seagate Technology Holdings Plc)
• Inventors: Mowry, Gregory S., Tolman, Charles H.
• Primary Examiner(s): Heine, A. J.
• Assistant Examiner(s): Garcia, Alfonso
• Application Number:
  US07/516,158
• Time in Patent Office: 953 Days
• Field of Search: 360/110, 360/113, 360/121-126
• US Class Current: 360/125.51
• CPC Class Codes: G11B 5/3113 for improving the magnetic domain structure or avoiding the formation or displacement of undesirable magnetic domains

Abstract

An inductive thin film magnetic head carried on a substrate having a reduced susceptibility to the "glitch" effect or "remote read" effect. The inductive thin film head uses a three point approach using hard axis only drive fields, narrow paddles and shortened pole tips which are spaced apart from a saw alley when the substrate is sliced.

Claims

1. A thin film magnetic recording head comprising:

a substrate;

a magnetic yoke deposited on the substrate including structure defining a top paddle and a bottom paddle for defining a high permeability magnetic flux path, the magnetic yoke deposited upon a nonmagnetic substrate and having an axis of symmetry, the top and bottom paddles having negative magnetostriction;

spaced apart paddle tips for the top and bottom paddles defining a magnetic flux gap in the magnetic yoke for recording and reading data proximate the flux gap, the paddle tips being normal to the axis of symmetry;

the top and bottom paddles including their respective paddle tips having a hard axis of magnetization generally parallel to the axis of symmetry and an easy axis of magnetization normal to the hard axis of magnetization in a plane of the top and bottom paddles;

a plurality of electrically insulated conductor windings, at least one of the plurality of conductor windings lying in a single plane and extending through the magnetic yoke between the top paddle and the bottom paddle; and

the conductor windings are parallel to the easy axis of magnetorization and perpendicular to a hard axis of magnetization of the magnetic paddles for maximizing exposure of the magnetic yoke to hard axis magnetic drive fields and minimizing exposure to easy axis magnetic drive fields whereby drive fields in the easy axis direction are less than local coercivity of the magnetic yoke.

2. The thin film magnetic recording head of claim 1 including a saw alley in the substrate, the saw alley extending generally parallel to the easy axis and spaced apart from the paddle tips.

3. The thin film magnetic recording head of claim 1 wherein the top and bottom poles each comprise:

a paddle tip region having a paddle tip width;

a back region having a back region width and a back side which defines a back region length, the back region width larger than the paddle tip width; and

a middle region extending between the paddle tip region and the back region and having a front edge with a front edge width which contacts the paddle tip region and a back edge with a back edge width which contacts the back region, the front edge width smaller than the back edge width, the middle region including a middle side extending between the back region and the paddle tip region, wherein the back side and the paddle tips form a first angle and the middle side and the paddle tips form a second angle.

5. The thin film magnetic recording head of claim 3 wherein the second angle is between about 45°

and about 90°

.

6. The thin film magnetic recording head of claim 3 wherein the middle region includes a middle region length between the back region and the paddle tip region and the middle region length is less than about 35 microns.

7. The thin film magnetic recording head of claim 1 wherein the back region length plus the middle region length is between about 135 microns and about 165 microns.

4. The thin film magnetic recording head of claim wherein the first angle is between about 85°

and about 95°

.

8. The thin film magnetic recording head of claim 4 wherein:

the first angle is between about 85° and

about 95°

;

the second angle is between about 45° and

about 90°

;

the middle region includes a middle region length between the back region and the paddle tip and the middle region length is less than about 35 microns; and

the back region length plus the middle region length is between about 135 microns and about 165 microns.

9. A thin film magnetic head recording head comprising:

a magnetic yoke including top and bottom poles for defining a high permeability magnetic flux path, the top and bottom poles having a hard axis of magnetization; and

a flattened, generally elliptical coil laying in a single plane and extending through the magnetic yoke including a flattened portion having a plurality of substantially parallel conductors extending through the magnetic yoke and a substantially elliptical portion extending beyond the magnetic yoke wherein the plurality of substantially parallel conductors are perpendicular to the hard axis of magnetization and parallel to the easy axis for maximizing exposure of the magnetic yoke to hard axis magnetic drive fields and minimizing exposure of the magnetic yoke to easy axis magnetic drive fields whereby magnetic drive fields in an easy axis direction are less than local coercivity of the magnetic yoke.

10. A thin film magnetic head, comprising:

a substrate;

a magnetic lower pole piece deposited over the substrate including a lower pole tip;

an insulating layer deposited over the lower pole piece;

a magnetic gap layer deposited over the lower pole tip;

a magnetic upper pole piece deposited over the magnetic lower pole piece and including an upper pole tip deposited over the magnetic gap layer, the magnetic upper and lower pole pieces forming a magnetic flux path to the upper and lower pole tips which form a magnetic flux gap across the magnetic gap layer, the upper and lower pole pieces having a hard axis of magnetization and an easy axis of magnetization which is perpendicular to the hard axis of magnetization, and the magnetic upper and lower pole pieces have a coercivity; and

a plurality of electrical conductors, at least one of the plurality of electrically conductors lying in a single plane and extending through the insulating layer and between the magnetic upper pole piece and the magnetic lower pole piece, the plurality of electrical conductors being oriented parallel with the easy axis of magnetization and perpendicular to the hard axis of magnetization of the magnetic upper and lower pole pieces for maximizing exposure of the magnetic upper and lower pole pieces to hard axis magnetic drive fields produced by the plurality of electrical conductors and minimizing exposure of the magnetic upper and lower pole pieces to easy axis magnetic drive fields produced by the plurality of electrical conductors, whereby an electrical current passed through the plurality of electrical conductors provides a magnetic field parallel to the hard axis of magnetization and perpendicular to the easy axis of magnetization of the magnetic upper and lower pole pieces so that magnetic drive fields in an easy axis direction are less than local coercivity of the pole pieces.

11. The thin film head of claim 10 wherein the substrate includes a saw alley which extends generally parallel with the easy axis and spaced apart from the upper and lower pole tips.

12. The thin film head of claim 10 wherein the magnetic upper and lower pole pieces have an overall length between a back gap which is opposite the upper and lower pole tips and the upper and lower pole tips, and a middle region length and a ratio between the middle region length and the overall length is less than about 0.21.