Patent US3736385A successfully refreshed from Google Patents.
US3736385A
Expired / Lapsed
US
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Storage and retrieval of analog information with magnetooptic readout
Assignee: EIDP Inc
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Filing: 1971-06-01
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Granted: 1973-05-29
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Expires: 1991-06-01
Abstract
Abstract A method is disclosed for the storage and retrieval of analog information by magnetic recording of the information as a modulated carrier frequency on magnetic recording member such as magnetic tape followed by magneto-optic read out. The signal field from the tape is combined with a bias field constant with time and directed at an angle to the signal field from the tape so that a resultant field is produced for application to the magneto-optic surface which varies angularly with the intensity of the signal field. The direction of magnetization of elements of the magneto-optic film can be varied transiently by the signal and bias field, or, with suitable framing techniques storage type transfer to suitable magneto-optic surfaces can be accomplished. Read-out of the pattern of magnetization on the magneto-optic surface with polarized light effects full wave rectification of the carrier frequency and recovery of the analog information.
Inventors
- 👤 R Waring
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:47
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10502; G11B11/10532; G11B11/10534; G11B11/10536; G11B5/00; G11B5/02; G11B5/027; G11B5/03; G11B5/127
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
141 words
Method of retrieving analog information stored as an amplitude-modulated periodic carrier signal recorded on a magnetic recording member which comprises: I. applying the magnetic field from the magnetic signals recorded on the recording member to a magneto-optic film; II. simultaneously applying a time-wise constant bias field to said magneto-optic film directed in the plane of said film and at an angle to the direction of said signal field, whereby the magnetic field at each point of the magneto-optic film is alligned in accordance with the signal field strength at that point; III. magnetizing the magneto-optic film in accordance with the field produced by the signal field and the bias field; and IV. detecting the pattern of magnetization on said magneto-optic film by detecting the change in rotation of polarized light reflected from said film whereby the carrier signal is fullwave demodulated.
Claim 2
Dependent Claim
141 words
Method of retrieving analog information stored as an amplitude-modulated periodic carrier signal recorded on a magnetic recording member which comprises: I. applying the magnetic field from the magnetic signals recorded on the recording member to a magneto-optic film; II. simultaneously applying a time-wise constant bias field to said magneto-optic film directed in the plane of said film and at an angle to the direction of said signal field, whereby the magnetic field at each point of the magneto-optic film is alligned in accordance with the signal field strength at that point; III. magnetizing the magneto-optic film in accordance with the field produced by the signal field and the bias field; and IV. detecting the pattern of magnetization on said magneto-optic film by detecting the change in rotation of polarized light reflected from said film whereby the carrier signal is fullwave demodulated.
Claim 3
Dependent Claim
19 words
Method of claim 1 in which said bias field is applied in a direction perpendicular to said signal field.
Claim 4
Dependent Claim
22 words
Method of claim 2 wherein said bias field has a maximum strength about 10 to 20 percent of the maximum field strength.
Claim 5
Dependent Claim
50 words
Method of claim 3 in which the magneto-optic film is anisotropic and has an anisotropy field less than the bias field, said bias field being applied along the easy axis of magnetization whereby said magneto-optic film is magnetized by the combined action of said bias field and said signal field.
Claim 6
Dependent Claim
80 words
Method of claim 3 wherein the magneto-optic film is isotropic and has a coercivity less than the maximum bias field and said bias field is supplied by a periodic pattern of magnetization on a platen having the same wavelength as the carrier signal, said platen and said recording member being maintained in fixed spatial relationship and means to move said platen and said recording member whereby said bias field and said signal field are applied transiently to said magneto-optic surface.
Claim 7
Dependent Claim
63 words
Method of claim 3 wherein said magneto-optic film is isotropic and has a coercivity greater than the resultant of the maximum signal field and the bias field, said transfer being accomplished by a collapsing rotating magnetic field having a maximum strength greater than the algebraic sum of said resultant field and the coercivity and less than the coercivity of said magnetic recording member.
Claim 8
Dependent Claim
85 words
Method of claim 6 wherein said magnetic recording member is a magnetic tape having recorded thereon a sequence of frames of information each said frame being composed of a periodic carrier signal amplitude modulated with an information signal; said magnetic recording member being moved continuously past said magneto-optic film, said film being within the magnetic field of signals recorded on said tape, said collapsing rotating magnetic field being applied periodically when each said frame is positioned at a predetermined position adjacent to said magneto-optic film.
Claim 9
Dependent Claim
125 words
Apparatus for the storage and retrieval of analog information comprising a magnetic recording member means to record a periodic carrier signal of constant amplitude on said recording member; means to demagnetize said carrier signal in accordance with information, whereby said carrier signal is amplitude modulated with said information; means to apply the field from said magnetic recording member to a magneto-optic film; means to apply a time-wise constant bias field to said magneto-optic film in the plane of said magneto-optic film and directed at an angle to the field from said recording member; means to magnetize the magneto-optic film in accordance with the magnetic field applied by said signal and said bias field; and means to detect the pattern of magnetization on said magneto-optic film.
Claim 10
Dependent Claim
125 words
Apparatus for the storage and retrieval of analog information comprising a magnetic recording member means to record a periodic carrier signal of constant amplitude on said recording member; means to demagnetize said carrier signal in accordance with information, whereby said carrier signal is amplitude modulated with said information; means to apply the field from said magnetic recording member to a magneto-optic film; means to apply a time-wise constant bias field to said magneto-optic film in the plane of said magneto-optic film and directed at an angle to the field from said recording member; means to magnetize the magneto-optic film in accordance with the magnetic field applied by said signal and said bias field; and means to detect the pattern of magnetization on said magneto-optic film.
Claim 11
Dependent Claim
38 words
Apparatus of claim 8 in which said magneto-optic film is an anisotropic film having an anisotropy field less than said bias field and the bias field is applied along the easy axis of magnetization of said magneto-optic film.
Claim 12
Dependent Claim
68 words
Apparatus of claim 8 in which said magneto-optic film is an isotropic film having a coercivity greater than the resultant of the bias field and the maximum signal field, and said means to magnetize the magneto-optic field comprises a collapsing rotating magnetic field having a maximum strength greater then the algebraic sum of said resultant and said coercivity and less than the coercivity of said magnetic recording member.
Claim 13
Dependent Claim
92 words
Apparatus of claim 8 wherein said magneto-optic film is an isotropic film having a coercivity less than the bias field; and said means to magnetize the magneto-optic film comprises a platen having a periodic pattern of magnetization of the same wavelength as said carrier signal; means to maintain said magnetic recording member and said platen at a fixed distance from each other; and means to move said platen and said magnetic recording member whereby the magneto-optic film is transiently exposed to the combined field of said magnetic recording member and said platen.
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) | 1976-05-28 | 1976-11-27 | 1977-05-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-28 | 1980-11-27 | 1981-05-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-28 | 1984-11-27 | 1985-05-29 | $7700.00 | Window Closed / Lapsed |