US3987363A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for testing thin layers of bubble domain material for defects
Assignee: US Philips Corp
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Filing: 1975-05-08
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Granted: 1976-10-19
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Expires: 1995-05-08
Abstract
Abstract A device for testing magnetic thin layers for defects, in particular "bubble" films in which a magnetic medium in which a recurring pattern of elongate areas magnetized alternately in opposite senses is recorded is moved relative to the layer while the layer is opposite the magnetic medium so that a corresponding pattern of mutually parallel strip-shaped "bubble" domains is formed in the film. Deviations in said pattern are an indication of defects in the film.
Inventors
- 👤 Jan Roos
- 👤 Jan Harm Tromp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:05
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/12; G01R33/1207; G01N; G01N27/00; G01N27/72; G01N27/82; G01R33/02; G01R33/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
82 words
A device for testing thin layers of bubble domain material for magnetically active defects comprising a magnetic medium having a spatially alternating and periodic field recorded thereon for forcing, when brought in facing relationship with a layer to be tested, an array of planar, equally spaced magnetic domains into said layer, means for relative movement between the magnetic medium and the layer to be tested in a direction substantially normal to the magnetic domains, and magneto-optical means for visualizing the magnetic domains.
Claim 2
Independent Claim
82 words
A device for testing thin layers of bubble domain material for magnetically active defects comprising a magnetic medium having a spatially alternating and periodic field recorded thereon for forcing, when brought in facing relationship with a layer to be tested, an array of planar, equally spaced magnetic domains into said layer, means for relative movement between the magnetic medium and the layer to be tested in a direction substantially normal to the magnetic domains, and magneto-optical means for visualizing the magnetic domains.
Claim 3
Dependent Claim
34 words
A device as claimed in claim 1 wherein the period of the field configuration is between 1 and 4 times the stable width of the strip-shaped domains in the absence of a magnetic field.
Claim 4
Dependent Claim
30 words
A device as claimed in claim 1, wherein the magnetic medium has subsequent areas which present a strength of the field configuration which increases from one area to the other.
Claim 5
Dependent Claim
43 words
A device as claimed in claim 1, wherein on the surface of the magnetic medium adjacent the layer to be tested, a non-magnetic platelet having a thickness which increases step-by-step is provided, the width of the steps permitting the arrangement of said layer.
Claim 6
Dependent Claim
15 words
A device as claimed in claim 4, wherein the non-magnetic platelet has a reflecting surface.
Claim 7
Dependent Claim
22 words
A device as claimed in claim 1, wherein the surface of the magnetic medium adjacent the layer to be tested is reflective.
Claim 8
Dependent Claim
23 words
A device as claimed in claim 1, wherein means are provided to produce a magnetic auxiliary field in the layer to be tested.
Claim 9
Dependent Claim
15 words
A device as claimed in claim 7, wherein the auxiliary field is an alternating field.
Claim 10
Dependent Claim
15 words
A device as claimed in claim 7, wherein the auxiliary field is a direct field.
References Cited (Backward Citations)
US3893023A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-10-19 | 1980-04-19 | 1980-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-19 | 1984-04-19 | 1984-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-19 | 1988-04-19 | 1988-10-19 | $7700.00 | Window Closed / Lapsed |