Patent US2476990A successfully refreshed from Google Patents.
Patent US5021910A successfully refreshed from Google Patents.
US5021910A
Expired / Lapsed
US
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Buried servo magnetic head
Assignee: NEC Corp
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Filing: 1990-03-06
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Granted: 1991-06-04
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Expires: 2010-03-06
Abstract
Abstract A device for reading servo information from a medium in a buried servo magnetic head system. The device consists of a coil for reading/writing data in the medium and a coil for reading the low-frequency servo signal, both coils being wound around the same core. The servo coil has a greater number of turns than the read/write coil which results in the servo signal having a lower resonance frequency than the read/write signal. By obtaining a separate read/write signal and a servo signal produced from a single core in a single head, physical positional errors are avoided without sacrificing the optimization of the separate signals.
Inventors
- 👤 Yoichi Murakami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:18
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/58; G11B5/596; G11B5/488; G11B5/4886; G11B5/59633; G11B5/5965
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
68 words
A buried servo magnetic head using an exclusive continuous low-frequency signal for servo which is recorded in a data surface of a medium, comprising: a core; a first coil wound around said core for reading/writing data from or to the medium; and a second coil wound around said core for reading said low-frequency servo signal, said second coil having a different number of turns than said first coil.
Claim 2
Dependent Claim
68 words
A buried servo magnetic head using an exclusive continuous low-frequency signal for servo which is recorded in a data surface of a medium, comprising: a core; a first coil wound around said core for reading/writing data from or to the medium; and a second coil wound around said core for reading said low-frequency servo signal, said second coil having a different number of turns than said first coil.
Claim 3
Dependent Claim
19 words
A magnetic head as claimed in claim 1, wherein said first coil forms a part of said second coil.
Claim 4
Dependent Claim
22 words
A magnetic head as claimed in claim 1, wherein said second coil has a greater number of turns than said first coil.
Claim 5
Dependent Claim
25 words
A magnetic head as claimed in claim 1, wherein said second coil has a resonance frequency three times the frequency of said low-frequency servo signal.
Claim 6
Dependent Claim
25 words
A magnetic head as claimed in claim 1, wherein said second coil has a resonance frequency lower than the lowest frequency of said data signal.
Claim 7
Dependent Claim
26 words
A magnetic head as claimed in claim 1, wherein said first coil has a resonance frequency approximately three times the highest frequency of said data signal.
Claim 8
Dependent Claim
108 words
A buried servo magnetic head using an exclusive continuous low-frequency signal for servo which is recorded in a data surface of a medium, comprising: a core; a first coil wound around said core for reading/writing data in the medium; a second coil wound around said core for reading said low-frequency servo signal, said second coil having a different number of turns than said first coil; and a signal processing unit, for processing said low-frequency servo signal and said read signal comprising first means for amplifying, filtering, and shaping said low-frequency servo signal to produce an error signal, and second means for amplifying, filtering and detecting said read signal.
Claim 9
Dependent Claim
108 words
A buried servo magnetic head using an exclusive continuous low-frequency signal for servo which is recorded in a data surface of a medium, comprising: a core; a first coil wound around said core for reading/writing data in the medium; a second coil wound around said core for reading said low-frequency servo signal, said second coil having a different number of turns than said first coil; and a signal processing unit, for processing said low-frequency servo signal and said read signal comprising first means for amplifying, filtering, and shaping said low-frequency servo signal to produce an error signal, and second means for amplifying, filtering and detecting said read signal.
Claim 10
Dependent Claim
115 words
A magnetic head as claimed in claim 7, wherein: said first means comprises a first amplifier for amplifying said servo signal, a first band pass filter, connected to said first amplifier, for filtering said low-frequency servo signal, and an error signal detector, connected to said first band pass filter, for shaping the waveform received from said first band pass filter and producing an error signal; and said second means comprises a second amplifier for amplifying said read signal, a second band pass filter, connected to said second amplifier, for filtering said read signal, and a read signal detector, connected to said second band pass filter, for detecting said read signal and producing said read signal.
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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) | 1994-06-03 | 1994-12-03 | 1995-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-03 | 1998-12-03 | 1999-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-03 | 2002-12-03 | 2003-06-04 | $7700.00 | Window Closed / Lapsed |