Patent US4479090A successfully refreshed from Google Patents.
US4479090A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuitry for measuring magnetic head flying characteristics
Assignee: International Business Machines Corp
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Filing: 1982-09-30
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Granted: 1984-10-23
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Expires: 2002-09-30
Abstract
Abstract A method for monitoring characteristics of a magnetic recording head which is flying in an air bearing relationship over a rotating magnetic recording disk containing Fe 2 O 3 detects triboelectric charges generated by intermittent contact between the head and the disk and also detects modulations in the spacing between the head and the disk surface when the two are not in contact.
Inventors
- 👤 Norman K. Frater
- 👤 Stanley S. Hoo
- 👤 William H. McConnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:33
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/60; G11B5/6005; G11B21/00; G11B21/16; G11B21/20; G11B33/00; G11B33/10; G11B5/62; G11B5/68; G11B5/70; G11B5/708
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
108 words
A method of monitoring characteristics of a magnetic recording head flying in an air bearing relationship relative to a rotating magnetic recording disk, said magnetic recording disk comprising a dispersion of magnetic particles and load-bearing particles in a binder system, at least some of said load-bearing particles extending above said disk surface, the material of the face of said magnetic head adjacent said disk surface being different in the triboelectric series from said load-bearing particles and said disk surface, comprising the step of detecting the triboelectric charge generated by intermittent contact between said head and said disk surface to provide an indication of the frequency of said contacts.
Claim 2
Independent Claim
108 words
A method of monitoring characteristics of a magnetic recording head flying in an air bearing relationship relative to a rotating magnetic recording disk, said magnetic recording disk comprising a dispersion of magnetic particles and load-bearing particles in a binder system, at least some of said load-bearing particles extending above said disk surface, the material of the face of said magnetic head adjacent said disk surface being different in the triboelectric series from said load-bearing particles and said disk surface, comprising the step of detecting the triboelectric charge generated by intermittent contact between said head and said disk surface to provide an indication of the frequency of said contacts.
Claim 3
Dependent Claim
53 words
A method in accordance with claim 1 including the step of detecting the sign and quantity of triboelectric charge generated by intermittent contact between said head and said disk surface to provide an indication of the frequency of said contacts and whether said contact was with said load-bearing particles or said disk surface.
Claim 4
Dependent Claim
74 words
A method in accordance with claim 1 in which said magnetic recording disk has a lubricant material applied to the surface thereof, said lubricant material being different in the triboelectric series from said material in said face of said magnetic head and from unlubricated portions of said disk surface, comprising the step of detecting the difference between contacts of said head with said lubricant material and with said unlubricated portion of said disk surface.
Claim 5
Independent Claim
157 words
A method of monitoring characteristics of a magnetic recording head flying in an air bearing relationship relative to a rotating magnetic recording disk, said magnetic recording disk comprising a magnetic layer, the material of the face of said magnetic head adjacent said disk surface being different in the triboelectric series from said magnetic layer, a voltage existing between said face of said magnetic head and said magnetic layer by virtue of the presence of said magnetic layer, comprising the step of detecting the triboelectric charge generated by intermittent contact between said head and the surface of said said magnetic layer to provide an indication of the frequency of said contacts and detecting variations in the capacitance between said face of said magnetic head and said disk surface as reflected by variations in said charge to provide an indication of modulation in the spacing between said face of said magnetic head and said surface of said magnetic layer.
Claim 6
Independent Claim
157 words
A method of monitoring characteristics of a magnetic recording head flying in an air bearing relationship relative to a rotating magnetic recording disk, said magnetic recording disk comprising a magnetic layer, the material of the face of said magnetic head adjacent said disk surface being different in the triboelectric series from said magnetic layer, a voltage existing between said face of said magnetic head and said magnetic layer by virtue of the presence of said magnetic layer, comprising the step of detecting the triboelectric charge generated by intermittent contact between said head and the surface of said said magnetic layer to provide an indication of the frequency of said contacts and detecting variations in the capacitance between said face of said magnetic head and said disk surface as reflected by variations in said charge to provide an indication of modulation in the spacing between said face of said magnetic head and said surface of said magnetic layer.
Claim 7
Dependent Claim
30 words
A method in accordance with claim 4 including the step of detecting the sign and quantity of triboelectric charge generated to provide an indication of the frequency of said contacts.
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) | 1987-10-23 | 1988-04-23 | 1988-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-23 | 1992-04-23 | 1992-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-23 | 1996-04-23 | 1996-10-23 | $7700.00 | Window Closed / Lapsed |