Patent US4020475A successfully refreshed from Google Patents.
US4020475A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic device operating with the photomagnetic effect
Assignee: US Philips Corp
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Filing: 1975-10-17
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Granted: 1977-04-26
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Expires: 1995-10-17
Abstract
Abstract A magnetic device which can be driven by means of electromagnetic radiation and has a radiation-sensitive element consisting of cobalt-doped yttrium-iron garnet. Exposure to electromagnetic radiation produces a decrease of the magnetic permeability of the element which decrease is permanent until the element is demagnetized and occurs at temperatures from 77 DEG K to room temperature.
Inventors
- 👤 Frederik Karel Lotgering
- 👤 Petrus Helena Gerardus Maria Vromans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:00
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/12; G01R33/1223; C; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2608; G02; G02F; G02F3/00; G03; G03G; G03G5/00; G03G5/16; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/18; H01F10/20; H01F10/24; H01F10/245
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
76 words
A magnetic device having a radiation-sensitive element which comprises a magnetisable material having garnet structure and of which a magnetic parameter can vary under the influence of electromagnetic radiation, the device comprising means to direct electromagnetic radiation onto the radiation-sensitive element, and a magnetic state sensing means to detect a variation in a magnetic parameter of the magnetisable material, said magnetisable material being cobalt doped yttrium-iron garnet having at most 0.02 cobalt atoms per formula Unit.
Claim 2
Dependent Claim
76 words
A magnetic device having a radiation-sensitive element which comprises a magnetisable material having garnet structure and of which a magnetic parameter can vary under the influence of electromagnetic radiation, the device comprising means to direct electromagnetic radiation onto the radiation-sensitive element, and a magnetic state sensing means to detect a variation in a magnetic parameter of the magnetisable material, said magnetisable material being cobalt doped yttrium-iron garnet having at most 0.02 cobalt atoms per formula Unit.
Claim 3
Dependent Claim
20 words
A device as claimed in claim 1, wherein the cobalt is present in the form of bivalent and trivalent cobalt.
Claim 4
Dependent Claim
34 words
A device as claimed in claim 1 wherein the cobalt-doped yttrium-iron garnet contains vanadium in the order of 0.1 vanadium atoms per formula unit and that the device can be operated at room temperature.
Claim 5
Dependent Claim
21 words
A device as claimed in claim 1 wherein the cobalt-doped yttrium-iron garnet contains further dopes which are capable of oxidizing ferro-ions.
Claim 6
Dependent Claim
23 words
A device as claimed in claim 1, wherein in the cobalt-doped yttrium-iron garnet a part of the yttrium is replaced by charge-compensating dopes.
Claim 7
Dependent Claim
28 words
A device as claimed in claim 1, wherein the device comprises electromagnetic means to demagnetise the magnetisable material after exposure in an alternating magnetic field with decreasing amplitude.
Claim 8
Dependent Claim
37 words
A device as claimed in claim 1, wherein the magnetic state sensing means is designed to detect a variation in the magnetic permeability and that the variation to be detected is a decrease of the magnetic permeability.
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) | 1980-04-25 | 1980-10-25 | 1981-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-25 | 1984-10-25 | 1985-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-25 | 1988-10-25 | 1989-04-26 | $7700.00 | Window Closed / Lapsed |