US4551776A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic reference adjustment for position error signal on disk file servo system
Assignee: International Business Machines Corp
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Filing: 1982-12-20
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Granted: 1985-11-05
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Expires: 2002-12-20
Abstract
Abstract A servo system which generates a position error signal (PES) provides for periodically calibrating the magnitude of the PES to increase or decrease its magnitude as required by modifying the gain of a variable gain amplifier in the servo loop.
Inventors
- 👤 Howard J. Roalson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:30
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/54; G11B5/55; G11B5/5521; G11B5/5526; G11B5/553; G11B5/5547; G11B5/58; G11B5/596; G11B5/59605; G11B5/59622
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
154 words
A system for automatically calibrating servo circuitry used with a servo pattern in which a position error signal (PES) is generated, said servo circuitry including a variable gain amplifier involved in generating said PES, said servo pattern having a primary signal P and a quadrature signal component Q in quadrature with said primary signal, said P and said Q signals having linear portions except near their peaks, a signal representing the sum of said P and said Q signals having a flat portion corresponding to said linear portions of said P and said Q signal, comprising means for generating a P signal and a Q signal, means for separately, averaging the following combinations of said signals P+Q, P+Q, P+Q, P+Q means for comparing the amplitudes of said averaged signals with a first reference voltage, and means responsive to the results of said comparison for modifying the gain of said amplifier to change said PES.
Claim 2
Independent Claim
154 words
A system for automatically calibrating servo circuitry used with a servo pattern in which a position error signal (PES) is generated, said servo circuitry including a variable gain amplifier involved in generating said PES, said servo pattern having a primary signal P and a quadrature signal component Q in quadrature with said primary signal, said P and said Q signals having linear portions except near their peaks, a signal representing the sum of said P and said Q signals having a flat portion corresponding to said linear portions of said P and said Q signal, comprising means for generating a P signal and a Q signal, means for separately, averaging the following combinations of said signals P+Q, P+Q, P+Q, P+Q means for comparing the amplitudes of said averaged signals with a first reference voltage, and means responsive to the results of said comparison for modifying the gain of said amplifier to change said PES.
Claim 3
Dependent Claim
32 words
A system in accordance with claim 1 in which said means responsive to the results of said comparison includes an up-down counter to generate a correcting voltage for modifying said amplifier gain.
Claim 4
Dependent Claim
23 words
A system in accordance with claim 2 in which said correcting voltage is added to the reference voltage to modify said amplifier gain.
Claim 5
Dependent Claim
54 words
A system in accordance with claim 3 in which said servo circuitry is employed in a magnetic disk file having at least one magnetic head movable to different concentric recording tracks of a magnetic disk, including means responsive to said head moving from one of said tracks to another for gating said up-down counter.
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) | 1988-11-04 | 1989-05-06 | 1989-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-04 | 1993-05-06 | 1993-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-04 | 1997-05-06 | 1997-11-05 | $7700.00 | Window Closed / Lapsed |