US3582918A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic head with dissimilar pole pieces
Assignee: General Electric Co
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Filing: 1968-01-12
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Granted: 1971-06-01
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Expires: 1988-01-12
Abstract
Abstract The corner of a magnetic recording head at one edge of the gap therein is modified by being set back, rounded off, etc., to produce a slowly varying response when a magnetic flux reversal in a magnetic recording medium moving in relation to the head passes the modified corner. A fast response is thus produced only when a flux reversal passes the corner at the other gap edge, obviating nulls in frequency response and yielding the benefits of a large gap without sacrificing resolution. Linear processing of waveforms produced by the head provides a sharp output pulse in response to each passing flux reversal.
Inventors
- 👤 Jerome J Tiemann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:00
CPC Classifications
G; G11; G11B; G11B23/00; G11B23/0007; G11B5/00; G11B5/02; G11B5/127; G11B5/187; G11B5/23
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
344 words
Apparatus for detecting signals magnetically recorded on a recording medium, said apparatus comprising: first and second members of high permeability magnetic material defining a nonmagnetic gap between said members, said first and second members being situated in unequal proximity to said recording medium and movable in relation thereto so that the time rate of change of magnetic flux due to a magnetic flux reversal arising as said medium moves in relation thereto is more gradual in said first member when said flux reversal is at its closest point to the edge of said first member at said gap than the time rate of change of magnetic flux in said second member when said flux reversal is at its closest point to the edge of said second member at said gap; a crosspiece of high permeability magnetic material integrally joined to said first and second members; a coil of wire wound about at least a portion of the magnetic material of said transducer head; the unequal proximity of said first and second pole pieces relative to said recording medium producing a nonsymmetrical variation in output voltage from said coil with time for a sensing of a given flux reversal by said pole pieces; and filter means coupled to said coil of wire for reproducing the recorded signals electrically to a high degree of accuracy; said filter means including means coupled to the output of said coil of wire for amplifying the output signal therefrom, means for generating a signal having an amplitude corresponding substantially to the output from said amplifying means during the interval when a flux reversal on said recording medium is closest to said first member to produce a gradual change in coil output voltage with time and means for substracting the output signal of said generating means from the output signal of said amplifying means to produce a difference signal having a peak amplitude during the interval when a flux reversal on said recording means is closest to said second member to produce a rapid change in coil output voltage with time.
Claim 2
Dependent Claim
344 words
Apparatus for detecting signals magnetically recorded on a recording medium, said apparatus comprising: first and second members of high permeability magnetic material defining a nonmagnetic gap between said members, said first and second members being situated in unequal proximity to said recording medium and movable in relation thereto so that the time rate of change of magnetic flux due to a magnetic flux reversal arising as said medium moves in relation thereto is more gradual in said first member when said flux reversal is at its closest point to the edge of said first member at said gap than the time rate of change of magnetic flux in said second member when said flux reversal is at its closest point to the edge of said second member at said gap; a crosspiece of high permeability magnetic material integrally joined to said first and second members; a coil of wire wound about at least a portion of the magnetic material of said transducer head; the unequal proximity of said first and second pole pieces relative to said recording medium producing a nonsymmetrical variation in output voltage from said coil with time for a sensing of a given flux reversal by said pole pieces; and filter means coupled to said coil of wire for reproducing the recorded signals electrically to a high degree of accuracy; said filter means including means coupled to the output of said coil of wire for amplifying the output signal therefrom, means for generating a signal having an amplitude corresponding substantially to the output from said amplifying means during the interval when a flux reversal on said recording medium is closest to said first member to produce a gradual change in coil output voltage with time and means for substracting the output signal of said generating means from the output signal of said amplifying means to produce a difference signal having a peak amplitude during the interval when a flux reversal on said recording means is closest to said second member to produce a rapid change in coil output voltage with time.
Claim 3
Dependent Claim
68 words
The apparatus of claim 1 wherein said filter means comprises: a differential amplifIer having a pair of inputs for subtracting one applied input signal from another applied input signal; a differentiator circuit; means coupling said coil jointly to one input of said differential amplifier and the input of said differentiator circuit; and means coupling the output of said differentiator circuit to the other input of said differential amplifier.
Claim 4
Dependent Claim
40 words
The apparatus of claim 2 wherein said means coupling said coil jointly to one input of said differential amplifier and the input of said differentiator circuit includes a variable resistance in series with said one input of said differential amplifier.
Claim 5
Dependent Claim
70 words
The apparatus of claim 1 wherein said filter means comprises: a differential amplifier having a pair of inputs for subtracting one applied input signal from another applied input signal; a delay line; means coupling said coil jointly to one input of said differential amplifier and to one end of said delay line; and means coupling the other end of said delay line to the other input of said differential amplifier.
Claim 6
Dependent Claim
41 words
The apparatus of claim 4 wherein said means coupling said coil jointly to one input of said differential amplifier and to one end of said delay line includes a variable resistance in series with said one input of said differential amplifier.
Claim 7
Dependent Claim
142 words
The apparatus of claim 1 wherein the lower face of said second member situated adjacent said recording medium is disposed substantially parallel to the plane of said recording medium and terminates at said gap in a substantially orthogonal attitude relative to the face of said second member forming said nonmagnetic gap therebetween and the lower face of said first member adjacent said recording medium gradually increases in span from said recording medium with increased proximity of said first member to said second member to establish a gradual interface between said nonmagnetic gap and said first member relative to the interface between said nonmagnetic gap and second second member, said apparatus being further characterized by a span across said nonmagnetic gap measured in a plane parallel to the plane of said recording medium which span decreases with increased departure from said recording medium.
Claim 8
Dependent Claim
247 words
A magnetic transducer head for use with a magnetic recording medium movable in relation thereto, said transducer head comprising first and second pole pieces of high permeability magnetic material defining a nonmagnetic gap therebetween, the lower face of said second pole piece situated adjacent said recording medium being disposed substantially parallel to the plane of said recording medium and terminating at said nonmagnetic gap in a substantially orthogonal attitude relative to the face of said second pole piece forming said nonmagnetic gap therebetween to produce a rapid time rate of change of magnetic flux in said transducer head when a flux reversal passes below the orthogonal edge of said second pole piece adjacent said gap, the lower surface of said first pole piece being characterized by a lower face adjacent said recording medium having a gradually increasing span from said recording medium with increased proximity of said first pole piece to said second pole piece to establish a gradual interface between said nonmagnetic gap and said first pole piece relative to the interface between said trailing pole piece and said nonmagnetic gap, said transducer head having a span across said nonmagnetic gap measured in a plane parallel to the plane of said recording medium which span decreases with departure from said recording medium, a crosspiece of high permeability magnetic material integrally joined to said leading and trailing pole pieces and a coil wire wound about at least a portion of the magnetic material of said transducer head.
Claim 9
Dependent Claim
247 words
A magnetic transducer head for use with a magnetic recording medium movable in relation thereto, said transducer head comprising first and second pole pieces of high permeability magnetic material defining a nonmagnetic gap therebetween, the lower face of said second pole piece situated adjacent said recording medium being disposed substantially parallel to the plane of said recording medium and terminating at said nonmagnetic gap in a substantially orthogonal attitude relative to the face of said second pole piece forming said nonmagnetic gap therebetween to produce a rapid time rate of change of magnetic flux in said transducer head when a flux reversal passes below the orthogonal edge of said second pole piece adjacent said gap, the lower surface of said first pole piece being characterized by a lower face adjacent said recording medium having a gradually increasing span from said recording medium with increased proximity of said first pole piece to said second pole piece to establish a gradual interface between said nonmagnetic gap and said first pole piece relative to the interface between said trailing pole piece and said nonmagnetic gap, said transducer head having a span across said nonmagnetic gap measured in a plane parallel to the plane of said recording medium which span decreases with departure from said recording medium, a crosspiece of high permeability magnetic material integrally joined to said leading and trailing pole pieces and a coil wire wound about at least a portion of the magnetic material of said transducer head.
Claim 10
Dependent Claim
35 words
A magnetic transducer head according to claim 7 wherein the lower surface of said first pole piece exhibits a linear increase in span from said recording medium with increased proximity to said second pole piece.
Claim 11
Dependent Claim
70 words
A magnetic transducer head according tO claim 8 wherein said first pole piece exhibits a sharp break in contour at the location where said lower face of said pole piece begins to linearly depart from said recording medium, said lower face of said second pole piece and said alteration in contour of said first pole piece being disposed in a common plane parallel to the surface of said recording medium.
Claim 12
Dependent Claim
35 words
A magnetic transducer head according to claim 7 wherein the lower surface of said first pole piece exhibits an arcuate increase in span from said magnetic medium with increased proximity to said second pole piece.
Claim 13
Dependent Claim
142 words
An apparatus for detecting signals magnetically recorded on a recording medium comprising a magnetic transducer head according to claim 7 and further including means coupled to the output of said coil of wire for amplifying the output signal therefrom, means for generating a signal having an amplitude corresponding substantially to the output from said amplifying means during the interval when a flux reversal on said recording medium is closest to said first pole piece to produce a gradual change in coil output voltage with time and means for substracting the output signal of said generating means from the output signal of said amplifying means to produce a difference signal having a peak amplitude during the interval when a flux reversal on said recording means is closest to said second pole piece to produce a rapid change in coil output voltage with time.
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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) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |