US4633338A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magneto-optical recording and reproducing apparatus having a magnetization direction detecting apparatus for a magnetic recording medium
Assignee: Sony Corp
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Filing: 1984-09-05
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Granted: 1986-12-30
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Expires: 2004-09-05
Abstract
Abstract In a magneto-optical recording and reproducing apparatus using a magnetic recording medium having a perpendicular magnetization layer, a magnetization direction detecting apparatus for detecting the magnetization direction of its perpendicular magnetization layer is provided to correctly carry out the recording, reproducing and erasing. In this magnetization direction detecting apparatus, a rectilineally polarized laser light (14) is made incident on a perpendicular magnetization layer (11-2) of a magnetic recording medium magnetized in the same direction previously and a reflected light of this laser light from the perpendicular magnetization layer is detected through an analyzer (19) by a photo detecting element (21) to thereby detect the magnetization direction of the perpendicular magnetization layer by the output level from the photo detecting element.
Inventors
- 👤 Noboru Sato
- 👤 Kenjirou Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:42
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/02; G11B5/09; G11B11/00; G11B11/10; G11B11/105; G11B11/10502; G11B11/10515; G11B11/10582; G11B11/10595; G11B11/10597
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
117 words
A magneto-optical recording and reproducing apparatus having a direction of magnetization detecting apparatus of a magnetic recording medium, characterized in that a rectilineally polarized laser light beam is projected onto a perpendicular magnetization layer of the magnetic recording medium which has been previously magnetized in a first direction, a reflected light beam from said laser light beam from said perpendicular magnetization layer is detected after passing through an analyzer to a photo detecting element, and a means for detecting the direction of the magnetization of said perpendicular magnetization layer by the output signal level of said photo detecting element, and the polarity of a magnetic field is changed by said means for detecting the direction of magnetization.
Claim 2
Dependent Claim
117 words
A magneto-optical recording and reproducing apparatus having a direction of magnetization detecting apparatus of a magnetic recording medium, characterized in that a rectilineally polarized laser light beam is projected onto a perpendicular magnetization layer of the magnetic recording medium which has been previously magnetized in a first direction, a reflected light beam from said laser light beam from said perpendicular magnetization layer is detected after passing through an analyzer to a photo detecting element, and a means for detecting the direction of the magnetization of said perpendicular magnetization layer by the output signal level of said photo detecting element, and the polarity of a magnetic field is changed by said means for detecting the direction of magnetization.
Claim 3
Dependent Claim
34 words
A magneto-optical recording and reproducing apparatus having a direction of magnetization detecting apparatus of a magnetic recording medium according to claim 1, characterized in that said magnetic field is an auxiliary biasing magnetic field.
Claim 4
Dependent Claim
59 words
A magneto-optical recording and reproducing apparatus having a direction of magnetization detecting apparatus of a magnetic recording medium according to claim 2, characterized in that said auxiliary biasing magnetic field is generated from a coil which has the direction of its current supply changed in response to said output signal from said means for detecting the direction of magnetization.
Claim 5
Dependent Claim
33 words
A magneto-optical recording and reproducing apparatus having a direction of magnetization detecting apparatus of a magnetic recording medium according to claim 1, characterized in that said magnetic field is an erasing magnetic field.
Claim 6
Dependent Claim
59 words
A magneto-optical recording and reproducing apparatus having a direction of magnetization detecting apparatus of a magnetic recording medium according to claim 4, characterized in that said erasing magnetic field is generated with a coil in which the direction of its current supply is changed in response to an output signal from said means for detecting the direction of magnetization.
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) | 1989-12-29 | 1990-06-30 | 1990-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-12-29 | 1994-06-30 | 1994-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-12-29 | 1998-06-30 | 1998-12-30 | $7700.00 | Window Closed / Lapsed |