US3836895A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Opto-magnetic memory
Assignee: US Philips Corp
•
Filing: 1972-11-07
•
Granted: 1974-09-17
•
Expires: 1992-11-07
Abstract
Abstract A device for the magnetic storage of data which comprises a plate of a magnetizable material having a periodic structure of magnetic domains. Recording data occurs with an external magnetic field having a value at which 2 types of magnetic domains having different sizes can occur. The size of a magnetic domain can be varied by selective irradiation with light.
Inventors
- 👤 Jonge F De
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:08
CPC Classifications
G; G03; G03G; G03G5/00; G03G5/16; G11; G11C; G11C13/00; G11C13/04; G11C13/06
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
238 words
A device for magnetic storage of data, comprising: a plate of ferrimagnetic material having an axis in which the material is easily magnetized, said axis being substantially normal to the plane of the plate, said material having a compensation temperature for magnetization, said plate having a number of data storage places which are disposed in the plate in the form of a periodic structure of cylindrical domains, said domains having a direction of magnetization which is opposite to that of surrounding areas in said plate; means disposed in proximity to said plate for magnetizing the plate, said means having a magnetic field with a field strength at which cylindrical magnetic domains can exist in the plate with both a circular and elongate cross-section for storing binary information, but wherein domains of circular and elongate cross-section differ in area; at least one source of radiation for supplying radiation to said plate; means for controlling the temperature of the plate so as to maintain said plate at a temperature other than said compensation temperature; deflector means disposed in a radiation path between said radiation source and said plate for directing the radiation to discrete areas of said plate, said areas of radiation containing at least one domain, said radiation increasing the temperature of the radiated areas; and address means connected to and controlling said deflector, whereby the deflector means will direct said radiation to a chosen area of said plate.
Claim 2
Independent Claim
238 words
A device for magnetic storage of data, comprising: a plate of ferrimagnetic material having an axis in which the material is easily magnetized, said axis being substantially normal to the plane of the plate, said material having a compensation temperature for magnetization, said plate having a number of data storage places which are disposed in the plate in the form of a periodic structure of cylindrical domains, said domains having a direction of magnetization which is opposite to that of surrounding areas in said plate; means disposed in proximity to said plate for magnetizing the plate, said means having a magnetic field with a field strength at which cylindrical magnetic domains can exist in the plate with both a circular and elongate cross-section for storing binary information, but wherein domains of circular and elongate cross-section differ in area; at least one source of radiation for supplying radiation to said plate; means for controlling the temperature of the plate so as to maintain said plate at a temperature other than said compensation temperature; deflector means disposed in a radiation path between said radiation source and said plate for directing the radiation to discrete areas of said plate, said areas of radiation containing at least one domain, said radiation increasing the temperature of the radiated areas; and address means connected to and controlling said deflector, whereby the deflector means will direct said radiation to a chosen area of said plate.
Claim 3
Dependent Claim
40 words
The device as claimed in claim 1, wherein the plate comprises a periodic structure of cylindrical magnEtic domains having a circular cross-section and wherein the temperature control means keeps the plate at a temperature which lies above the compensation temperature.
Claim 4
Dependent Claim
38 words
The device as claimed in claim 1, wherein said magnetizing means has a magnetic field having a reduced field strength exceeding a given value in at least a part of the plate for a short period of time.
Claim 5
Dependent Claim
29 words
The device as claimed in claim 1, wherein the address means can increase the temperature at an area of said plate containing a number of adjacently disposed magnetic domains.
References Cited (Backward Citations)
US3787825A
Cited
US3786452A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-16 | 1978-03-18 | 1978-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-16 | 1982-03-18 | 1982-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-16 | 1986-03-18 | 1986-09-17 | $7700.00 | Window Closed / Lapsed |