US3593333A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Position detection for a track following servo system
Assignee: International Business Machines Corp
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Filing: 1969-11-26
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Granted: 1971-07-13
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Expires: 1989-11-26
Abstract
Abstract The invention relates to the positioning of a transducer relative to a desired information track on a magnetic disc. Alternate reference tracks on the disc are 90* out of phase with each other. Position error detection circuitry derives an error position signal and an automatic gain signal simultaneously from the signal induced in the transducer as a function of its position relative to the reference tracks on the disc. The automatic gain signal is provided even when the transducer is properly placed and allows for more accurate error position signals to be generated by the position error detection circuitry.
Inventors
- 👤 Richard K Oswald
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:40
CPC Classifications
G; G05; G05D; G05D3/00; G05D3/12; G05D3/20; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/59605; G11B5/59622
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
354 words
A memory system comprising: a magnetic disc having a plurality of positioning control sectors interspersed with a plurality of information sectors, each of said positioning control sectors having a plurality of concentric reference tracks, each said reference track having a series of signal inducing areas defining a signal of frequency f, the boundary between adjacent ones of said reference track defining the centers of data tracks in said information sectors; a transducer adjacent to and movable with respect to said magnetic disc, said transducer being responsive to the magnetic states of both said reference track in said positioning control sectors and said data tracks in said information sectors; a variable gain amplifier for receiving said signals developed from said reference tracks by said transducer; a first sampling means for sampling the output of said variable gain amplifier at a first frequency; a second sampling means for sampling the output of said variable gain amplifier at a second frequency, where said first and said second frequencies are the same frequencies but 90* out of phase with respect to each other; a first converting means connected to said first sampling means for generating a first analog signal proportional to the output of said first sampling means; a second converting means connected to the output of said second sampling means for generating a second analog signal proportional to the output of said second sampling means; a first generating means for generating a position error signal from said first and second analog signals, said position error signal being indicative of the position relationship between said transducer and two of said reference tracks in said positioning control sectors; a second generating means for generating an amplitude signal from said first and second analog signals, said amplitude signals being indicative of the amplitude of the signals being developed from said reference tracks by said transducer; a third generating means for generating a variable gain amplifier control signal by comparing said amplitude signal and a given reference signal, the output of said third generating means being connected to said variable gain amplifier for controlling the gain of said variable gain amplifier.
Claim 2
Dependent Claim
354 words
A memory system comprising: a magnetic disc having a plurality of positioning control sectors interspersed with a plurality of information sectors, each of said positioning control sectors having a plurality of concentric reference tracks, each said reference track having a series of signal inducing areas defining a signal of frequency f, the boundary between adjacent ones of said reference track defining the centers of data tracks in said information sectors; a transducer adjacent to and movable with respect to said magnetic disc, said transducer being responsive to the magnetic states of both said reference track in said positioning control sectors and said data tracks in said information sectors; a variable gain amplifier for receiving said signals developed from said reference tracks by said transducer; a first sampling means for sampling the output of said variable gain amplifier at a first frequency; a second sampling means for sampling the output of said variable gain amplifier at a second frequency, where said first and said second frequencies are the same frequencies but 90* out of phase with respect to each other; a first converting means connected to said first sampling means for generating a first analog signal proportional to the output of said first sampling means; a second converting means connected to the output of said second sampling means for generating a second analog signal proportional to the output of said second sampling means; a first generating means for generating a position error signal from said first and second analog signals, said position error signal being indicative of the position relationship between said transducer and two of said reference tracks in said positioning control sectors; a second generating means for generating an amplitude signal from said first and second analog signals, said amplitude signals being indicative of the amplitude of the signals being developed from said reference tracks by said transducer; a third generating means for generating a variable gain amplifier control signal by comparing said amplitude signal and a given reference signal, the output of said third generating means being connected to said variable gain amplifier for controlling the gain of said variable gain amplifier.
Claim 3
Dependent Claim
33 words
A memory system as set forth in claim 1 wherein said transducer has a working area equal to the width of a reference track, all of said reference tracks having the same widtH.
Claim 4
Dependent Claim
52 words
A memory system as set forth in claim 2 wherein said series of signal inducing areas of the even numbered reference tracks are offset by 90* as defined by said frequency f from the series of signal inducing areas in the odd number reference tracks in each of said positioning control sectors.
References Cited (Backward Citations)
US3404392A
Cited
US3430215A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-07-12 | 1975-01-11 | 1975-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-07-12 | 1979-01-11 | 1979-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-07-12 | 1983-01-11 | 1983-07-13 | $7700.00 | Window Closed / Lapsed |