Patent US4912585A successfully refreshed from Google Patents.
US4912585A
Expired / Lapsed
US
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Discrete track thin film magnetic recording disk with embedded servo information
Assignee: International Business Machines Corp
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Filing: 1988-04-28
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Granted: 1990-03-27
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Expires: 2008-04-28
Abstract
Abstract A discrete track thin film metal alloy or metal oxide magnetic recording disk has a plurality of angularly spaced sectors, each sector being formed of a plurality of discrete blocks of magnetic material which are magnetically polarized in the disk's circumferential direction. These discrete servo blocks and the discrete magnetic tracks are both formed at the same time during the fabrication of the thin film disk such that each servo block is precisely and permanently radially aligned with an associated discrete data track. Following the fabrication of the disk, each of the servo blocks is exposed to the magnetic field generated by passing a direct current (DC) through a recording head. In this manner each of the servo blocks becomes magnetized in the circumferential direction and thereby presents two discrete magnetic transitions to a servo read head or a read/write head.
Inventors
- 👤 Karl A. Belser
- 👤 Tarek Makansi
- 👤 Ian L. Sanders
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:49
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/74; G11B5/82; B; B82; B82Y; B82Y10/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59633; G11B5/5965; G11B5/743
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
125 words
A magnetic recording disk comprising: a disk substrate; a plurality of concentric generally circular discrete data tracks of magnetic material located on the substrate, each of the discrete data tracks being separated from a radially neighboring data track by a concentric guard track of nonmagnetic material; and a plurality of discrete servo blocks of magnetic material magnetically polarized in the circumferential direction and located on the substrate in at least one angular sector of the disk, each of the servo blocks being separated from neighboring servo blocks and data tracks by regions of nonmagnetic material and having at least one generally circumferentially directed edge located on the substrate at a fixed predetermined radial distance from the centerline of the data track radially nearest said edge.
Claim 2
Dependent Claim
125 words
A magnetic recording disk comprising: a disk substrate; a plurality of concentric generally circular discrete data tracks of magnetic material located on the substrate, each of the discrete data tracks being separated from a radially neighboring data track by a concentric guard track of nonmagnetic material; and a plurality of discrete servo blocks of magnetic material magnetically polarized in the circumferential direction and located on the substrate in at least one angular sector of the disk, each of the servo blocks being separated from neighboring servo blocks and data tracks by regions of nonmagnetic material and having at least one generally circumferentially directed edge located on the substrate at a fixed predetermined radial distance from the centerline of the data track radially nearest said edge.
Claim 3
Dependent Claim
38 words
The disk according to claim 1 wherein the servo blocks are located in a plurality of sectors generally equally angularly spaced around the disk, whereby the generally circular data tracks are divided into a plurality of circular arcs.
Claim 4
Dependent Claim
22 words
The disk according to claim 1 wherein the servo blocks in each sector form a pattern which repeats in a radial direction.
Claim 5
Dependent Claim
22 words
The disk according to claim 1 further comprising synchronization and gain stripes of circumferentially magnetically polarized magnetic material located in the sector.
Claim 6
Dependent Claim
13 words
The disk according to claim 4 wherein the pattern is a quadrature pattern.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-26 | 1993-09-25 | 1994-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-26 | 1997-09-25 | 1998-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-26 | 2001-09-25 | 2002-03-27 | $7700.00 | Window Closed / Lapsed |