US3582877A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal magnetic information recording
Assignee: Bell and Howell Co
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Filing: 1969-05-02
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Granted: 1971-06-01
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Expires: 1989-05-02
Abstract
Abstract In information recording methods in which a magnetic recording medium is magnetized by subjection to heating above a transition temperature and subsequent subjection to a cooling cycle in the presence of a magnetic field, the improvement of selecting a pattern of first regions of the recording medium representative of the information, heating the information-representative pattern of first regions to a first temperature above the transition temperature, heating second regions of the recording medium to a second temperature above the first temperature, applying the magnetic field to the recording medium, subjecting the recording medium to the cooling cycle whereby the first regions are magnetized when such first regions cool through and below the transition temperature, removing the magnetic field from the recording medium before the second regions cool through the transition temperature, and permitting the second regions to cool through and below the transition temperature.
Inventors
- 👤 Luc P Benoit
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:38
CPC Classifications
G; G03; G03G; G03G19/00
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
148 words
In a method of recording information, the improvement comprising: providing a magnetic recording medium which is susceptible to magnetization upon subjection to heating above a transition temperature and subsequent subjection to a cooling cycle in the presence of a magnetic field; selecting a pattern of first regions of said recording medium representative of said information; heating said information-representative pattern of first regions to a first temperature above said transition temperature; heating second regions of said recording medium to a second temperature above said first temperature; applying said magnetic field to said recording medium; subjecting said recording medium to said cooling cycle whereby said first regions are magnetized when said first regions cool through and below said transition temperature; removing said magnetic field from said recording medium before said second regions cool through said transition temperature; and permitting said second regions to cool through and below said transition temperature.
Claim 2
Dependent Claim
148 words
In a method of recording information, the improvement comprising: providing a magnetic recording medium which is susceptible to magnetization upon subjection to heating above a transition temperature and subsequent subjection to a cooling cycle in the presence of a magnetic field; selecting a pattern of first regions of said recording medium representative of said information; heating said information-representative pattern of first regions to a first temperature above said transition temperature; heating second regions of said recording medium to a second temperature above said first temperature; applying said magnetic field to said recording medium; subjecting said recording medium to said cooling cycle whereby said first regions are magnetized when said first regions cool through and below said transition temperature; removing said magnetic field from said recording medium before said second regions cool through said transition temperature; and permitting said second regions to cool through and below said transition temperature.
Claim 3
Dependent Claim
24 words
A method as claimed in claim 1, wherein said second regions include substantially all regions of said recording medium other than said first regions.
Claim 4
Dependent Claim
20 words
A method as claimed in claim 1, wherein said transition temperature is the Curie temperature of said magnetic recording medium.
Claim 5
Dependent Claim
140 words
In a method of recording an image, the improvement comprising: providing a magnetic recording medium which is susceptible to magnetization upon subjection to heating above a transition temperature and subsequent subjection to a cooling cycle in the presence of a magnetic field; heating first regions of said recording medium corresponding to said image to a first temperature above said transition temperature; heating second regions of said recording medium to a second temperature above said first temperature; applying said magnetic field to said recording medium; subjecting said recording medium to said cooling cycle whereby said first regions are magnetized when said first regions cool through and beloW said transition temperature; removing said magnetic field from said magnetic recording medium before said second regions cool through said transition temperature; and permitting said second regions to cool through and below said transition temperature.
Claim 6
Dependent Claim
140 words
In a method of recording an image, the improvement comprising: providing a magnetic recording medium which is susceptible to magnetization upon subjection to heating above a transition temperature and subsequent subjection to a cooling cycle in the presence of a magnetic field; heating first regions of said recording medium corresponding to said image to a first temperature above said transition temperature; heating second regions of said recording medium to a second temperature above said first temperature; applying said magnetic field to said recording medium; subjecting said recording medium to said cooling cycle whereby said first regions are magnetized when said first regions cool through and beloW said transition temperature; removing said magnetic field from said magnetic recording medium before said second regions cool through said transition temperature; and permitting said second regions to cool through and below said transition temperature.
Claim 7
Dependent Claim
19 words
A method as claimed in claim 4, wherein said second regions correspond to a negative representation of said image.
Claim 8
Dependent Claim
60 words
A method as claimed in claim 4, wherein said first and second regions are heated by heating said first and second regions to said first temperature, by establishing a thermal image corresponding to a negative representation of said image, and by applying said thermal image to said recording medium to effect heating of said second regions to said second temperature.
Claim 9
Dependent Claim
24 words
A method as claimed in claim 4, wherein said thermal image is established by reflecting thermal radiations from a master record of said information.
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) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |