US3553389A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic transducer with a low reluctance massive back gap
Assignee: BARGER CORP
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Filing: 1967-06-09
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Granted: 1971-01-05
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Expires: 1987-06-09
Abstract
Abstract The improved magnetic transducer is designed particularly for recording and reproducing very high frequencies of between 5 and 20 million cycles per second which includes television video frequencies. The transducer is made up of a pair of similar, separate halves, comprising massive body portions of relatively great width and thickness. The abutting surfaces of these body portions are lapped flat and true, and when assembled in contact with each other, constitute a back joint or back gap of extremely low reluctance. The body portion of each half carries integral therewith a head which is relatively small and thin, or narrow. These heads constitute elongated pole pieces, the tips of these pole pieces, when said halves are assembled, facing each other in closely spaced relation, providing between them a front or scanning gap. The cross section of said massive body portion is at least fifty times that of the pole piece tips adjacent the scanning gap, and the relative areas of said back and front gaps are on the order of at least twenty to one. The relative thinness or narrowness of the pole pieces results in there being formed on the body portions, at each of the pole pieces, broad shoulders. Each of the heads has at each end, between the pole pieces and said shoulders, a coil-receiving notch, and a coil is wound in these pairs of notches around each head, these coils engaging the shoulders. These coils are relatively small. The effective coil length lying within a range of .005 to .03 inch. The notches at the gap ends of the pole pieces are substantially semicylindrical, and when in registry with each other, form a substantially circular opening extending transversely of the pole pieces, adjacent the gap. This circular opening lies immediately below the scanning gap, so that the shortest flux path through said gap extends circumferentially around said opening. This results in an exceptionally short flux path length ranging from .02 to .05 inch.
Inventors
- 👤 Theodore W Barger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:52
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/48; G11B5/127; G11B5/17; G11B5/52; G11B5/53
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
199 words
A transducer for use in a rotating head apparatus for recording and reproducing information on a magnetic medium, said transducer being formed of two similar, separate halves of magnetic material, each half comprising a massive body portion and a head integral therewith, said body portion being many times thicker than said head and having relatively broad shoulders on which said head is carried, and said head being relatively narrow and constituting an elongated pole piece, the tips of said pole pieces, when said halves are assembled, facing each other in closely spaced relation, providing between them a front gap, each of said heads having at each end a coil receiving notch, a coil wound around each head in said notches, the coil receiving notches at the gap ends of said pole pieces being in registry with each other, the mating surfaces of the massive body portions being lapped true and flat and in contact with each other, and the joint between them constituting an intimate back gap of relatively low reluctance per unit area as well as low total reluctance, the relative areas of the back and front gaps being on the order of at least 20 to 1.
Claim 2
Dependent Claim
199 words
A transducer for use in a rotating head apparatus for recording and reproducing information on a magnetic medium, said transducer being formed of two similar, separate halves of magnetic material, each half comprising a massive body portion and a head integral therewith, said body portion being many times thicker than said head and having relatively broad shoulders on which said head is carried, and said head being relatively narrow and constituting an elongated pole piece, the tips of said pole pieces, when said halves are assembled, facing each other in closely spaced relation, providing between them a front gap, each of said heads having at each end a coil receiving notch, a coil wound around each head in said notches, the coil receiving notches at the gap ends of said pole pieces being in registry with each other, the mating surfaces of the massive body portions being lapped true and flat and in contact with each other, and the joint between them constituting an intimate back gap of relatively low reluctance per unit area as well as low total reluctance, the relative areas of the back and front gaps being on the order of at least 20 to 1.
Claim 3
Dependent Claim
68 words
A magnetic transducer in accordance with claim 1 in which the coil receiving notches are each substantially semicylindrical in cross section, so that when the halves are assembled, with the said notches in registry with each other, they form a substantially circular opening extending transversely of the plane of said pole pieces immediately below said gap, the shortest flux path through said gap extending circumferentially around said opening.
Claim 4
Dependent Claim
39 words
A magnetic transducer in accordance with claim 2 in which the shortest flux path through said gap follows a circular course concentric with said opening and has a total minimum length substantially no greater than .05 of an inch.
Claim 5
Dependent Claim
217 words
A transducer for use in a rotating head apparatus for recording and reproducing information on a magnetic medium, said transducer being formed of two similar, separate halves of magnetic material, each half comprising a massive body portion and a head integral therewith, said body portion being many times thicker than said head and having relatively broad shoulders on which said head is carried, and said head being relatively narrow and constituting an elongated pole piece, the tips of said pole pieces, when said halves are assembled, facing each other in closely spaced relation, providing between them a front gap, each of said heads having at each end a coil receiving notch, a coil wound around each head in said notches. the coil receiving notches at the gap ends of said pole pieces being in registry with each other, so that the outer surfaces of the two coils are in substantial contact at a point immediately adjacent said front gap, the mating surfaces of the massive body portions being lapped true and flat, and the joint between them constituting an intimate back gap of relatively low reluctance per unit area as well as low total reluctance, the cross section of said massive body portion being at least 50 times that of the pole piece tips adjaceNt said gap.
Claim 6
Dependent Claim
217 words
A transducer for use in a rotating head apparatus for recording and reproducing information on a magnetic medium, said transducer being formed of two similar, separate halves of magnetic material, each half comprising a massive body portion and a head integral therewith, said body portion being many times thicker than said head and having relatively broad shoulders on which said head is carried, and said head being relatively narrow and constituting an elongated pole piece, the tips of said pole pieces, when said halves are assembled, facing each other in closely spaced relation, providing between them a front gap, each of said heads having at each end a coil receiving notch, a coil wound around each head in said notches. the coil receiving notches at the gap ends of said pole pieces being in registry with each other, so that the outer surfaces of the two coils are in substantial contact at a point immediately adjacent said front gap, the mating surfaces of the massive body portions being lapped true and flat, and the joint between them constituting an intimate back gap of relatively low reluctance per unit area as well as low total reluctance, the cross section of said massive body portion being at least 50 times that of the pole piece tips adjaceNt said gap.
Claim 7
Dependent Claim
219 words
A transducer for use in a rotating head apparatus for recording and reproducing information on a magnetic medium, said transducer being formed of two similar, separate halves of magnetic material, each half comprising a massive body portion and a head integral therewith, said body portion being many times thicker than said head and having relatively broad shoulders on which said head is carried, and said head being relatively narrow and constituting an elongated pole piece, the tips of said pole pieces, when said halves are assembled, facing each other in closely spaced relation, providing between them a front gap, each of said heads having at each end a coil receiving notch, a coil wound around each head in said notches, the coil receiving notches at the gap ends of said pole pieces being in registry with each other, so that the outer surfaces of the two coils are in substantial contact at a point immediately adjacent said front gap, the mating surfaces of the massive body portions being lapped true and flat, and the joint between them constituting an intimate back gap of relatively low reluctance per unit area as well as low total reluctance, both the width and the depth of the back joint surfaces being on the order of 1,000 times the length of the front gap.
Claim 8
Dependent Claim
219 words
A transducer for use in a rotating head apparatus for recording and reproducing information on a magnetic medium, said transducer being formed of two similar, separate halves of magnetic material, each half comprising a massive body portion and a head integral therewith, said body portion being many times thicker than said head and having relatively broad shoulders on which said head is carried, and said head being relatively narrow and constituting an elongated pole piece, the tips of said pole pieces, when said halves are assembled, facing each other in closely spaced relation, providing between them a front gap, each of said heads having at each end a coil receiving notch, a coil wound around each head in said notches, the coil receiving notches at the gap ends of said pole pieces being in registry with each other, so that the outer surfaces of the two coils are in substantial contact at a point immediately adjacent said front gap, the mating surfaces of the massive body portions being lapped true and flat, and the joint between them constituting an intimate back gap of relatively low reluctance per unit area as well as low total reluctance, both the width and the depth of the back joint surfaces being on the order of 1,000 times the length of the front gap.
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) | 1974-01-04 | 1974-07-06 | 1975-01-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-04 | 1978-07-06 | 1979-01-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-04 | 1982-07-06 | 1983-01-05 | $7700.00 | Window Closed / Lapsed |