Patent US1655875A successfully refreshed from Google Patents.
US4339760A
Expired / Lapsed
US
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Magnetic printing head having a high signal-to-noise ratio
Assignee: Ericsson Inc
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Filing: 1981-03-06
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Granted: 1982-07-13
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Expires: 2001-03-06
Abstract
Abstract The signal-to-noise ratio as measured by the ratio of the full select magnetic field levels to the half select magnetic field levels, is improved in a coincident current magnetic printing head by providing means for producing a bias magnetic field which is at least somewhat opposed to the signal magnetic fields.
Inventors
- 👤 Jish M. Wang
- 👤 Richard O. McCary
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 01:56
CPC Classifications
G; G03; G03G; G03G19/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
163 words
A magnetic printing head, having a high signal-to-noise ratio, for writing information on a magnetic recording medium moving relative to said head, said head comprising: an elongate magnetic member having along the length thereof a plurality of regularly spaced projections, said member being composed of material having a high permeability; means to produce a full select signal magnetic field between the tips of selected adjacent pairs of projections, said means being operated by energizing a pair of electrical conductors disposed between said selected projections, each of said conductors producing a half select signal magnetic field, the half-select magnetic fields combining to produce said full select signal magnetic field; and bias means operating to produce a bias magnetic field at least between said selected pairs of projections, said bias magnetic field being opposed to said full select and half select signal magnetic fields so as to increase the ratio of the resultant full select magnetic field strength to the resultant half-select magnetic field strength.
Claim 2
Dependent Claim
163 words
A magnetic printing head, having a high signal-to-noise ratio, for writing information on a magnetic recording medium moving relative to said head, said head comprising: an elongate magnetic member having along the length thereof a plurality of regularly spaced projections, said member being composed of material having a high permeability; means to produce a full select signal magnetic field between the tips of selected adjacent pairs of projections, said means being operated by energizing a pair of electrical conductors disposed between said selected projections, each of said conductors producing a half select signal magnetic field, the half-select magnetic fields combining to produce said full select signal magnetic field; and bias means operating to produce a bias magnetic field at least between said selected pairs of projections, said bias magnetic field being opposed to said full select and half select signal magnetic fields so as to increase the ratio of the resultant full select magnetic field strength to the resultant half-select magnetic field strength.
Claim 3
Dependent Claim
39 words
The printing head of claim 1 in which said magnetic recording medium exhibits a hysteresis loop having a zero magnetization value of H c and in which the magnitude of said bias field is approximately 0.5 H c .
Claim 4
Dependent Claim
17 words
The printing head of claim 1 in which said bias means comprises at least one permanent magnet.
Claim 5
Dependent Claim
28 words
The printing head of claim 1 in which said bias means comprises an electrical conductor disposed between said projections and oriented to produce said opposing bias magnetic field.
Claim 6
Dependent Claim
21 words
The magnetic printing head of claim 1 further including support means for maintaining said magnetic member adjacent to said recording medium.
Claim 7
Dependent Claim
34 words
The printing head of claim 5 in which said support means comprises an elongate anodized aluminum block having an arched surface thereon, said elongate member being disposed along the peak of said arched surface.
Claim 8
Dependent Claim
36 words
The magnetic printing head of claim 1 in which said means to produce said signal magnetic fields and said means to produce said bias magnetic field comprise conductors mounted on at least one printed circuit board.
Claim 9
Dependent Claim
159 words
A magnetic print head, having a high signal-to-noise ratio, for recording information on a magnetic recording medium, said head comprising: an elongated magnetic member having along the length thereof a plurality of spaced pole pieces, said member being composed of material having a high permeability; said head requiring a full select signal magnetic field between selected adjacent pairs of pole pieces to effect such recording, a plurality of means each producing a partial select signal magnetic field between selected adjacent pairs of pole pieces, and means for combining a required plurality of such partial select magnetic field to produce said full select signal magnetic field; and bias means operating to produce a bias magnetic field at least between said selected pairs of pole pieces, said bias magnetic field being opposed to said combined partial select magnetic fields so as to increase the ratio of the resultant full select magnetic field strength to the resultant half select magnetic field strength.
Claim 10
Dependent Claim
159 words
A magnetic print head, having a high signal-to-noise ratio, for recording information on a magnetic recording medium, said head comprising: an elongated magnetic member having along the length thereof a plurality of spaced pole pieces, said member being composed of material having a high permeability; said head requiring a full select signal magnetic field between selected adjacent pairs of pole pieces to effect such recording, a plurality of means each producing a partial select signal magnetic field between selected adjacent pairs of pole pieces, and means for combining a required plurality of such partial select magnetic field to produce said full select signal magnetic field; and bias means operating to produce a bias magnetic field at least between said selected pairs of pole pieces, said bias magnetic field being opposed to said combined partial select magnetic fields so as to increase the ratio of the resultant full select magnetic field strength to the resultant half select magnetic field strength.
Claim 11
Dependent Claim
52 words
The printing head of claim 8 in which said magnetic recording medium exhibits a hysteresis loop having a zero magnetization value of H C and in which the resultant magnitude of the combined partial select fields is approximately 1.0 H C and the bias magnetic field is approximately 0.5 H C .
Claim 12
Dependent Claim
43 words
The printing head of claim 8 in which the difference between the half-select magnetic field and bias magnetic field has a resultant magnitude of approximately 0.5 H c and the maximum magnitude of the bias magnetic field is approximately 0.5 H c .
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-07-12 | 1986-01-11 | 1986-07-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-07-12 | 1990-01-11 | 1990-07-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-07-12 | 1994-01-11 | 1994-07-13 | $7700.00 | Window Closed / Lapsed |