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US3609723A
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Piezoreflective-magnetostrictive film transducer
Assignee: International Business Machines Corp
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Filing: 1969-12-24
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Granted: 1971-09-28
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Expires: 1989-12-24
Abstract
Abstract Magnetic information is converted to optical signals by placing a coupled piezoreflective-magnetostrictive film layer between the information-containing medium and a light source; and the pattern of magnetization on the medium induces a similar pattern of elongation or contraction in the magnetostrictive film which imparts a strain at corresponding locations in the piezoreflective film and a resulting change in reflectivity of the film. Accordingly, the reflectance of light incident upon the piezoreflective film surface can be sensed to determine the presence or absence of magnetization at particular locations on the information-containing medium.
Inventors
- 👤 John K Alstad
- 👤 James R Wiitala
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 22:27
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G02; G02B; G02B26/00; G02B26/06; G02F; G02F1/00; G02F1/01; G02F1/09; G02F1/29; G02F1/31; G02F1/315; G11B11/105; G11B11/10532; G11B11/10541; G11B11/10543; G11B11/10547
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
30 words
In a magnetic reproduction system according to claim 1, said film transducer further including a transparent substrate supporting said magnetostrictive and piezoreflective films in close alignment with the recorded medium.
Claim 2
Dependent Claim
22 words
In a magnetic reproduction system according to claim 1, further including a transparent prism overlying the piezoreflective surface of said film transducer.
Claim 3
Dependent Claim
37 words
In a magnetic reproduction system according to claim 1, said magnetostrictive film being composed in percentage by weight of 60 percent nickel, 25 percent iron, and 15 percent cobalt, and said piezoreflective film being composed of silver.
Claim 4
Dependent Claim
38 words
In a magnetic reproduction system according to claim 4, the thickness of said magnetostrictive and piezoreflective films each being on the order of 100 to 10,000 angstroms, said piezoreflective film being coated by evaporation to said magnetostrictive film.
Claim 5
Dependent Claim
159 words
A magnetic reproduction system for converting magnetic information contained on a recorded medium to optical signals comprising a film transducer composed of a magnetostrictive film contiguous to and in close alignment with the recorded medium to undergo localized changes in elongation or contraction in response to and corresponding to changing patterns of magnetization on the recorded medium and a piezoreflective layer mechanically coupled to the magnetostrictive film layer to undergo localized changes in reflectivity corresponding to localized changes in elongation or contraction in said magnetostrictive film, a transparent substrate supporting said film transducer in close alignment to the recorded medium with the piezoreflective film overlying said magnetostrictive film, light transmitting means for transmitting light incident to said piezoreflective film, and photodetector means for intercepting reflected light from said piezoreflective film and for producing signals according to the intensity of light from said piezoreflective film surface whereby to indicate the presence or absence of magnetic information on the recorded medium.
Claim 6
Dependent Claim
36 words
A magnetic reproduction system according to claim 6, said magnetostrictive film selected from the group consisting of permalloys and nickel/iron alloys, and said piezoreflective layer being selected from the group consisting of silver, gold, and copper.
Claim 7
Dependent Claim
19 words
A magnetic reproduction system according to claim 6, said light transmitting means transmitting light perpendicular to said piezoreflective film.
Claim 8
Dependent Claim
29 words
A magnetic reproduction system according to claim 8, said light transmitting means including a light source and a beam splitter interposed between said light source and said piezoreflective film.
Claim 9
Dependent Claim
165 words
A magnetic reproduction system for converting magnetic bits of information contained on a magnetic tape medium to optical signals comprising a film transducer composed of a mechanicaLly coupled piezoreflective-magnetostrictive film layer in close alignment with the magnetic tape, said magnetostrictive film undergoing changes in elongation or contraction in response to changing patterns of magnetization on the magnetic tape to impart changes in strain in said piezoreflective film at locations corresponding to the magnetized areas on the magnetic tape, a transparent substrate supporting said magnetostrictive film in contiguous relation to the recorded medium with said piezoreflective film overlying said magnetostrictive film, light transmitting means for transmitting light perpendicular to said piezoreflective film, a beam splitter intercepting the light reflected from said piezoreflective film, and photodetector means intercepting reflected light from said beam splitter and for producing optical signals according to the intensity of light from selected locations on said piezoreflective film surface whereby to indicate the presence or absence of magnetic information on the magnetic tape.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-27 | 1975-03-29 | 1975-09-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-27 | 1979-03-29 | 1979-09-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-27 | 1983-03-29 | 1983-09-28 | $7700.00 | Window Closed / Lapsed |