US3686467A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic transducer system and method
Assignee: IIT Research Institute
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Filing: 1969-08-08
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Granted: 1972-08-22
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Expires: 1989-08-08
Abstract
Abstract A magnetic transducer head having a coupling gap of controllable effective longitudinal dimension. In one embodiment a gap spacer of magnetic material is energized by bias current and/or signal current during recording while being deenergized during playback to provide a larger coupling gap for recording than for playback. Recording gap size may be controlled dynamically, or a very high frequency bias current such as 100 mhz may be supplied to the magnetic gap spacer. A magnetic head may have a zero gap dimension when the magnetic gap spacer is deenergized to prevent any substantial residual external field. An electro-magnetic transducer head with the electric circuit portion including a path through the electrically conductive magnetic corepiece at the transducer gap, thus concentrating the gap field and mininizing core losses at very high bias or signal frequencies.
Inventors
- 👤 Marvin Camras
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 16:21
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/23; G11B5/245; G11B5/2452
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
245 words
A magnetic head comprising a magnetic core having a coupling region for coupling of the core with a magnetic record medium during a recording operation, said coupling region including a leading section and a trailing section across which the record medium successively travels during the recording operation, the leading section of said coupling region being formed of a magnetic material, and electric circuit means connected in an electric circuit with said magnetic material of said leading section of said coupling region for supplying electric current through said magnetic material during recording operation and operable for substantially reducing the magnetic permeability of said magnetic material during said recording operation in comparison to the permeability thereof when the head is deenergized, said trailing section of said coupling region being formed by a non-magnetic material having a thickness which is substantially less than the thickness of said magnetic material of said leading section and which is effective for reproducing signals recorded on the record medium during the recording operation, said leading section of said coupling region directly adjoining said magnetic core at the leading side of said coupling region and having a magnetic permeability substantially corresponding to that of said magnetic core during playback operation to avoid any substantial signal flux pickup from the record medium during playback operation except at said trailing section of said coupling region, and the scanning dimension of the magnetic head for playback operation being determined by the thickness of said non-magnetic material.
Claim 2
Dependent Claim
245 words
A magnetic head comprising a magnetic core having a coupling region for coupling of the core with a magnetic record medium during a recording operation, said coupling region including a leading section and a trailing section across which the record medium successively travels during the recording operation, the leading section of said coupling region being formed of a magnetic material, and electric circuit means connected in an electric circuit with said magnetic material of said leading section of said coupling region for supplying electric current through said magnetic material during recording operation and operable for substantially reducing the magnetic permeability of said magnetic material during said recording operation in comparison to the permeability thereof when the head is deenergized, said trailing section of said coupling region being formed by a non-magnetic material having a thickness which is substantially less than the thickness of said magnetic material of said leading section and which is effective for reproducing signals recorded on the record medium during the recording operation, said leading section of said coupling region directly adjoining said magnetic core at the leading side of said coupling region and having a magnetic permeability substantially corresponding to that of said magnetic core during playback operation to avoid any substantial signal flux pickup from the record medium during playback operation except at said trailing section of said coupling region, and the scanning dimension of the magnetic head for playback operation being determined by the thickness of said non-magnetic material.
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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) | 1975-08-22 | 1976-02-21 | 1976-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-22 | 1980-02-21 | 1980-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-22 | 1984-02-21 | 1984-08-22 | $7700.00 | Window Closed / Lapsed |