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US3742471A
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Bubble domain apparatus
Assignee: Hitachi Ltd
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Filing: 1972-02-24
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Granted: 1973-06-26
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Expires: 1992-02-24
Abstract
Abstract Bubble domain apparatus comprising a plurality of bubble domain elements, each of which has a bias magnetic field applied thereto by a permanent magnet sheet having an equivalent diameter sufficiently large relative to its thickness and being magnetized normally to the sheet surface, and which are received in a magnetic shielding box so that the permanent magnet sheets may be in parallel arrangement. In the bubble domain apparatus, even when one of said bubble domain elements is taken out from said apparatus, the bias magnetic fields applied to the respective bubble domain elements change scarcely.
Inventors
- 👤 I Mikami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:47
CPC Classifications
G; G11; G11C; G11C19/00; G11C19/02; G11C19/08; G11C19/085; C; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2683
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
169 words
Bubble domain apparatus, comprising: n pairs of a permanent magnet sheet and a bubble domain element; each of said paired permanent magnet sheet and bubble domain element being stacked in close proximity with each other; each of said bubble domain elements having a magnetic sheet capable of moving bubble domains in its sheet and means for moving bubble domains in its sheet; each of said permanent magnet sheets having an equivalent diameter of d and a thickness of t wherein said d and said t are selected to fulfill the condition of d/t >> 1 and being magnetized normally to its sheet surface for applying a bias magnetic field to said magnetic sheet being paired with said permanent magnet sheet; a magnetic shielding box having an inside height of h; and said n permanent magnet sheets being stacked in parallel and fixed spaced apart relationship with respect to one another by distances which fulfill the condition of h/n about 2d/ pi in said magnetic shielding box above and below.
Claim 2
Dependent Claim
169 words
Bubble domain apparatus, comprising: n pairs of a permanent magnet sheet and a bubble domain element; each of said paired permanent magnet sheet and bubble domain element being stacked in close proximity with each other; each of said bubble domain elements having a magnetic sheet capable of moving bubble domains in its sheet and means for moving bubble domains in its sheet; each of said permanent magnet sheets having an equivalent diameter of d and a thickness of t wherein said d and said t are selected to fulfill the condition of d/t >> 1 and being magnetized normally to its sheet surface for applying a bias magnetic field to said magnetic sheet being paired with said permanent magnet sheet; a magnetic shielding box having an inside height of h; and said n permanent magnet sheets being stacked in parallel and fixed spaced apart relationship with respect to one another by distances which fulfill the condition of h/n about 2d/ pi in said magnetic shielding box above and below.
Claim 3
Dependent Claim
26 words
Bubble domain apparatus according to claim 1, in which said n stacked permanent magnet sheets are further arranged in said magnetic shielding box right and left.
Claim 4
Dependent Claim
28 words
Bubble domain apparatus according to claim 1, in which said n stacked permanent magnet sheets are further arranged in said magnetic shielding box right, left, before and behind.
References Cited (Backward Citations)
US3678478A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-06-25 | 1976-12-25 | 1977-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-25 | 1980-12-25 | 1981-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-25 | 1984-12-25 | 1985-06-26 | $7700.00 | Window Closed / Lapsed |