Patent CA1177577A successfully refreshed from Google Patents.
CA1177577A
Expired / Lapsed
CA
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Magnetooptical recording medium and recording-and- reproducing device using the same
Assignee: Panasonic Holdings Corp
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Filing: 1981-07-15
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Granted: 1984-11-06
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Expires: 2001-07-15
Abstract
Abstract TITLE OF THE INVENTION: Magnetooptical Recording Medium and Recording-and-Reproducing Device Using the Same ABSTRACT OF THE DISCLOSURE: A Kerr-magnetooptical-effect type recording-and-reproducing device using a recording disk comprising a substrate and magnetic thin films formed over both the major surfaces of the substrate in such a way that their easy directions are perpendicular to the substrate and both the films are magnetized in the same, for instance, upward direction. An optical converging lens and a permanent magnet, which is movable in parallel with or perdencular to the recording disk and rotatable about its axis, are disposed on the opposite sides, respectively t of the recording disk in opposing relationship. A bit is written into or erased from the upper thin film by setting the permanent magnet in such a way that the upwardly or downwardly pointed field is applied to a desired bit yield simultaneous with the focusing of 2 laser beam at the field so as to heat it to a temperature above a Curie point. In like manner the writing or erasing of the lower thin film is effected, but the direction of the write or erasing field is reversed; that is, the downwardly or upwardly pointed field is applied.
Inventors
- 👤 Akira Muto
- 👤 Masahiro Birukawa
- 👤 Hidetsugu Kawabata
Bibliographic Details
Application Number
—
Jurisdiction
CA
Data Source
google_patents
Last Synchronized
2026-11-04 07:10
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10502; G11B11/10504; G11B11/10517; G11B11/10532; G11B11/10534; H; H04; H04N; H04N5/00; H04N5/76; H04N5/78; H04N5/782; H04N5/7824; H04N5/7826; H04N5/78263
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
484 words
A magneto-optic recording and reproducing device for storing information on and reproducing information from a magneto-optic record medium, said record medium having a substrate and upper and lower magneto-optic thin films formed on opposed major surfaces of said substrate, each of said films having an axis of easy magnetization perpendicular to said major surfaces, said recording and reproducing device comprising: an optical head including a converging optical lens for focusing a light beam on a selected region of a selected one of said upper and lower magneto-optic thin films, said optical head having (i) a recording mode in which said focused light beam alters the structure of said selected region of said upper magneto-optic thin film to enable an externally applied magnetic field to record information on said selected region of said upper magneto-optic thin film, (ii) an erase mode in which said focused light beam alters the structure of said selected region of said upper magneto-optic thin film to enable an externally applied magnetic field to erase any information stored wherein, and (iii) a reproduce mode in which said optical head optically detects the light of said focused light beam reflected from said selected region of a selected one of said upper and lower magneto-optic thin films to generate a signal corresponding to information recorded therein; a permanent magnet disposed in alignment with said focused light beam so that said record medium may be disposed between said optical head and said permanent magnet, with said upper magneto optic thin film adjacent said optical head and said lower magneto-optic thin film adjacent said per-manent magnet; means operative in said recording mode to cause the intensity of said focused light beam to be sufficient to (i) heat only said selected region of said upper maqneto-optic thin film to a temperature sufficiently high to enable said permanent magnet to record information on said selected region, and to simultaneously (ii) move said permanent magnet with respect to said selected region so as to magnetically record information on said selected region; and means operative in said erase mode to cause the intensity of said focused light beam to be sufficient to (i) heat only said selected region of said upper magneto-optic thin film to a temperature sufficiently high to enable said permanent magnet to erase information on said selected region by subjecting said upper magneto-optic thin film to a magnetic field having a field strength above a critical or threshold erasing field strength and to simultaneously (ii) move said permanent magnet with respect to said selected region so as to magnetically erase information from said selected region, said critical or threshold erasing field strength being less than the coercive force of said lower magneto--optic thin film, so that said permanent magnet may erase information from said selected region of said upper magneto--optic thin film without disturbing information stored in the adjacent portion of said lower magneto-optic thin film.
Claim 2
Dependent Claim
484 words
A magneto-optic recording and reproducing device for storing information on and reproducing information from a magneto-optic record medium, said record medium having a substrate and upper and lower magneto-optic thin films formed on opposed major surfaces of said substrate, each of said films having an axis of easy magnetization perpendicular to said major surfaces, said recording and reproducing device comprising: an optical head including a converging optical lens for focusing a light beam on a selected region of a selected one of said upper and lower magneto-optic thin films, said optical head having (i) a recording mode in which said focused light beam alters the structure of said selected region of said upper magneto-optic thin film to enable an externally applied magnetic field to record information on said selected region of said upper magneto-optic thin film, (ii) an erase mode in which said focused light beam alters the structure of said selected region of said upper magneto-optic thin film to enable an externally applied magnetic field to erase any information stored wherein, and (iii) a reproduce mode in which said optical head optically detects the light of said focused light beam reflected from said selected region of a selected one of said upper and lower magneto-optic thin films to generate a signal corresponding to information recorded therein; a permanent magnet disposed in alignment with said focused light beam so that said record medium may be disposed between said optical head and said permanent magnet, with said upper magneto optic thin film adjacent said optical head and said lower magneto-optic thin film adjacent said per-manent magnet; means operative in said recording mode to cause the intensity of said focused light beam to be sufficient to (i) heat only said selected region of said upper maqneto-optic thin film to a temperature sufficiently high to enable said permanent magnet to record information on said selected region, and to simultaneously (ii) move said permanent magnet with respect to said selected region so as to magnetically record information on said selected region; and means operative in said erase mode to cause the intensity of said focused light beam to be sufficient to (i) heat only said selected region of said upper magneto-optic thin film to a temperature sufficiently high to enable said permanent magnet to erase information on said selected region by subjecting said upper magneto-optic thin film to a magnetic field having a field strength above a critical or threshold erasing field strength and to simultaneously (ii) move said permanent magnet with respect to said selected region so as to magnetically erase information from said selected region, said critical or threshold erasing field strength being less than the coercive force of said lower magneto--optic thin film, so that said permanent magnet may erase information from said selected region of said upper magneto--optic thin film without disturbing information stored in the adjacent portion of said lower magneto-optic thin film.
Claim 3
Dependent Claim
23 words
The combination according to claim 1, wherein said thin films are pre-magnetized in opposite directions with respect to each other, along said axis.
Claim 4
Dependent Claim
19 words
The combination according to claim 1, wherein said thin films are pre-magnetized in the same direction along said axis.
Claim 5
Dependent Claim
56 words
The recording and reproducing device according to claim 1,further comprising means for reversing the polarity of said permanent magnet with respect to said record medium, for recording information on or erasing information from said first-mentioned optomagnetic thin film relative to the polarity used for recording information on or erasing information from said additional magneto-optic thin film.
References Cited (Backward Citations)
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