US4635139A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Asperity burst writer
Assignee: International Business Machines Corp
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Filing: 1985-08-26
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Granted: 1987-01-06
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Expires: 2005-08-26
Abstract
Abstract A glide head is used to test a rigid magnetic disk surface for projecting asperities. Using a two rail head with the read/write transducer mounted at the rear of the rail at the side of the head toward which the head is being radially advanced and skewing the head so that the trailing edge of the head approaches each track before the leading edge as the head is advanced, it is possible to write a pattern from a known position relative an event or asperity identified by a mechanical transducer associated with the head to the index location. Using a developer, it is then possible to readily identify the asperity during microscopic examination of the disk surface.
Inventors
- 👤 Son V. Nguyen
- 👤 James M. Severson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:22
CPC Classifications
G; G11; G11B; G11B33/00; G11B33/10; G11B27/00; G11B27/36
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
138 words
Apparatus for testing a magnetic recording surface for asperities comprising a glide head which travels over the magnetic surface on a film of air; said glide head being skewed at an acute angle to the magnetic surface track to permit the trailing edge of the slider to first approach each track in the direction of glide head access; a transducer attached to said glide head and adapted to selectively write on said surface; non-magnetic detecting means for ascertaining when said glide head overlies an asperity on the magnetic surface; and means for writing a pattern of data on a portion of the current track beginning when said detecting means indicates that said glide head overlies an asperity, whereby said magnetic surface may be analyzed by examining the asperity that is positioned adjacent the start of a written pattern.
Claim 2
Dependent Claim
138 words
Apparatus for testing a magnetic recording surface for asperities comprising a glide head which travels over the magnetic surface on a film of air; said glide head being skewed at an acute angle to the magnetic surface track to permit the trailing edge of the slider to first approach each track in the direction of glide head access; a transducer attached to said glide head and adapted to selectively write on said surface; non-magnetic detecting means for ascertaining when said glide head overlies an asperity on the magnetic surface; and means for writing a pattern of data on a portion of the current track beginning when said detecting means indicates that said glide head overlies an asperity, whereby said magnetic surface may be analyzed by examining the asperity that is positioned adjacent the start of a written pattern.
Claim 3
Independent Claim
120 words
The method of locating and identifying the position of an asperity on a rigid magnetic surface having parallel data tracks thereon using a glide head with a transducer attached thereto comprising the steps of a. skewing said glide head to cause the trailing edge of said glide head to first overlie an asperity encountered in the direction of head access movement, b. accessing said glide head over said surface from track to track, c. identifying when an asperity has been encountered adjacent the glide head, d. writing a pattern of data on the associated track when the asperity is encountered, and e. examining the magnetic surface by identifying the asperities which occur adjacent the beginning of the pattern of data.
Claim 4
Independent Claim
120 words
The method of locating and identifying the position of an asperity on a rigid magnetic surface having parallel data tracks thereon using a glide head with a transducer attached thereto comprising the steps of a. skewing said glide head to cause the trailing edge of said glide head to first overlie an asperity encountered in the direction of head access movement, b. accessing said glide head over said surface from track to track, c. identifying when an asperity has been encountered adjacent the glide head, d. writing a pattern of data on the associated track when the asperity is encountered, and e. examining the magnetic surface by identifying the asperities which occur adjacent the beginning of the pattern of data.
Claim 5
Dependent Claim
55 words
The method of locating and identifying the position of an asperity on a rigid magnetic disk of claim 2 wherein the examination of said magnetic surface comprises applying a developer to the surface scanned by said glide head and microscopically examining the scanned surface to identify asperities from the written pattern of said developed surface.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-01-05 | 1990-07-07 | 1991-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-05 | 1994-07-07 | 1995-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-05 | 1998-07-07 | 1999-01-06 | $7700.00 | Window Closed / Lapsed |