US4796241A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for producing a high frequency modulation magnetic field used in magneto-optical recording
Assignee: Sony Corp
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Filing: 1987-01-21
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Granted: 1989-01-03
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Expires: 2007-01-21
Abstract
Abstract A device for producing a high frequency modulating magnetic field is disclosed. The device is especially useful to achieve real-time overwriting in magneto-optical recording. The device produces magnetic field modulated according to a signal to be recorded on a magneto-optical recording medium in which the signal is recorded in the form of magnetization direction on the magneto-optical recording medium under irradiation of a laser beam to raise the temperature of the medium. The device comprises a main magnetic pole formed of a low-loss soft magnetic material and having one end facing to the magnetic-optical recording medium and a sheathed conductor wound around the main magnetic pole and consisting of a parallel connection of a plurality of insulated elementary wires.
Inventors
- 👤 Masatoshi Hayakawa
- 👤 Takehiro Nagaki
- 👤 Koichi Aso
- 👤 Hiroshi Yamanoi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 16:17
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10532
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
172 words
A device for producing a high frequency modulating magnetic field applied to a magneto-optical recording layer to determine the magnetization direction in the magneto-optical recording layer upon locally heating the layer by a focused laser beam, comprising: a main magnetic pole formed of a low-loss soft magnetic material, said main magnetic pole having one end facing said magneto-optical recording layer and having a tapered portion at said one end; a yoke completely surrounding and magnetically connected to said main magnetic pole at the other end of said main magnetic pole, said yoke having an extended portion extending towards said main magnetic pole at the one end facing said magneto-optical recording layer and forming a required gap between it and said tapered portion of said main magnetic pole; and a sheathed conductor wound about said main magnetic pole, said conductor consisting of a parallel connection of a plurality of insulated elementary wires supplied with high frequency current to generate a high frequency magnetic field at said one end of said main magnetic pole.
Claim 2
Independent Claim
172 words
A device for producing a high frequency modulating magnetic field applied to a magneto-optical recording layer to determine the magnetization direction in the magneto-optical recording layer upon locally heating the layer by a focused laser beam, comprising: a main magnetic pole formed of a low-loss soft magnetic material, said main magnetic pole having one end facing said magneto-optical recording layer and having a tapered portion at said one end; a yoke completely surrounding and magnetically connected to said main magnetic pole at the other end of said main magnetic pole, said yoke having an extended portion extending towards said main magnetic pole at the one end facing said magneto-optical recording layer and forming a required gap between it and said tapered portion of said main magnetic pole; and a sheathed conductor wound about said main magnetic pole, said conductor consisting of a parallel connection of a plurality of insulated elementary wires supplied with high frequency current to generate a high frequency magnetic field at said one end of said main magnetic pole.
Claim 3
Dependent Claim
29 words
A device according to claim 1, wherein said tapered portion is formed to have an angle not more than 50 degrees with an axis of said main magentic pole.
Claim 4
Dependent Claim
23 words
A device according to claim 1, wherein said magnetic pole has a diameter between 0.1 and 3.0 mm at said one end thereof.
Claim 5
Dependent Claim
18 words
A device according to claim 1, wherein said extended portion is inclined relative to said magneto-optical recording layer.
Claim 6
Dependent Claim
20 words
A device according to claim 1, wherein said extended portion has a protrusion portion adjacent around said main magnetic pole.
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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) | 1992-01-03 | 1992-07-04 | 1993-01-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-01-03 | 1996-07-04 | 1997-01-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-01-03 | 2000-07-04 | 2001-01-03 | $7700.00 | Window Closed / Lapsed |