US3611329A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Longitudinal digital recording with perpendicular dc bias
Assignee: Fujitsu Services Ltd
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Filing: 1968-12-04
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Granted: 1971-10-05
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Expires: 1988-12-04
Abstract
Abstract A digital information recording apparatus is disclosed in which a high-coercivity planar recording member is moved across a gap between pole-pieces of a recording head. A first winding is energized to produce a varying magnetic field, representative of the digital information to be recorded, across the recording gap. A second winding is energized to produce a steady DC magnetic bias field at a substantial angle to the surface of the recording member such that the digital information is recorded in the presence of the steady DC magnetic bias field. In a second embodiment, one pole-piece is common to the varying field representative of the digital information to be recorded and the steady DC magnetic bias field.
Inventors
- 👤 John Edmund Lee
- 👤 Norman Nathan Truman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:50
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/127; G11B5/187; G11B5/02; G11B5/027; G11B5/03
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
123 words
A method of recording digital information on a moveable highcoercivity planar magnetizable member including the steps of moving said member across a recording gap between two pole-pieces of a recording head, energizing a first winding to produce a varying magnetic field across the gap substantially parallel to and in the plane of the magnetizable member, said varying magnetic field representing digital information to be recorded on said magnetizable member, and energizing a second winding simultaneously with energization of said first winding to produce a steady DC magnetic bias field substantially perpendicular to the surface of said magnetizable member at the recording gap between said pole-pieces such that information is recorded on said magnetizable member in the presence of said steady DC bias field.
Claim 2
Independent Claim
123 words
A method of recording digital information on a moveable highcoercivity planar magnetizable member including the steps of moving said member across a recording gap between two pole-pieces of a recording head, energizing a first winding to produce a varying magnetic field across the gap substantially parallel to and in the plane of the magnetizable member, said varying magnetic field representing digital information to be recorded on said magnetizable member, and energizing a second winding simultaneously with energization of said first winding to produce a steady DC magnetic bias field substantially perpendicular to the surface of said magnetizable member at the recording gap between said pole-pieces such that information is recorded on said magnetizable member in the presence of said steady DC bias field.
Claim 3
Dependent Claim
44 words
A method of recording information on a movable high-coercivity planar magnetizable member as claimed in claim 1 in which said steady DC magnetic bias field is maintained for longer than said first winding is energized by signals to be recorded on said magnetizable member.
Claim 4
Dependent Claim
183 words
Apparatus for recording digital information on a movable, high-coercivity planar magnetizable member including a recording head having first and second pole-pieces separated by a gap, said first and second pole-pieces being positioned on one side of said magnetizable member, means to move said magnetizable member across said gap, the recording head having a third pole-piece positioned on the other side of said magnetizable meMber and underlying said gap, a first winding, means to energize said first winding to produce a varying magnetic field representative of said digital information, said variable magnetic field being produced across said gap substantially parallel to and in the plane of said magnetizable member, a second winding, and means to energize said second winding simultaneously with energization of said first winding to produce a steady DC magnetic bias field extending from said first and second pole-pieces through said magnetizable member to said third pole-piece in a direction substantially perpendicular to the surface of said magnetizable member at said recording gap and over at least that area of said magnetizable member onto which said varying magnetic field is simultaneously applied.
Claim 5
Dependent Claim
183 words
Apparatus for recording digital information on a movable, high-coercivity planar magnetizable member including a recording head having first and second pole-pieces separated by a gap, said first and second pole-pieces being positioned on one side of said magnetizable member, means to move said magnetizable member across said gap, the recording head having a third pole-piece positioned on the other side of said magnetizable meMber and underlying said gap, a first winding, means to energize said first winding to produce a varying magnetic field representative of said digital information, said variable magnetic field being produced across said gap substantially parallel to and in the plane of said magnetizable member, a second winding, and means to energize said second winding simultaneously with energization of said first winding to produce a steady DC magnetic bias field extending from said first and second pole-pieces through said magnetizable member to said third pole-piece in a direction substantially perpendicular to the surface of said magnetizable member at said recording gap and over at least that area of said magnetizable member onto which said varying magnetic field is simultaneously applied.
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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) | 1974-10-04 | 1975-04-05 | 1975-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-04 | 1979-04-05 | 1979-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-04 | 1983-04-05 | 1983-10-05 | $7700.00 | Window Closed / Lapsed |