US3640247A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic powder applicator
Assignee: Creed and Co Ltd
•
Filing: 1970-03-18
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Granted: 1972-02-08
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Expires: 1990-03-18
Abstract
Abstract A magnetizable powder applicator arrangement in a printing or display apparatus employing for example a magnetizable drum. The powder is attracted to the outer surface of a nonmagnetizable tube which contains therein a rotatable row of bar magnets having like poles adjacent. The divergent flux field set up by the rotating magnets causes the powder to creep along the surface of the tube in a direction opposite the magnet rotation, and onto a ledge of nonmagnetizable material. The ledge is sufficiently close to the drum, yet sufficiently far from the flux field, for the powder to be attracted to the drum surface without disturbing the selective magnetization thereon.
Inventors
- 👤 Frederick Percival Mason
- 👤 Frank Arthur Oakley Waren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:10
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G19/00
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
128 words
In a magnetic printing and/or display device, apparatus for dusting the movable magnetizable surface of the device with magnetic powder comprising a convex nonmagnetic surface extending from a supply of the powder to a nonmagnetic ledge adjacent the magnetizable surface, and a magnetic rotor disposed behind the nonmagnetic surface and having its axis of rotation parallel thereto for producing at the nonmagnetic surface a system of magnetic flux which is divergent in a plane substantially perpendicular to the axis of rotation, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder to creep in the opposite direction along the nonmagnetic surface and across the ledge by somersaulting of the powder as the flux field repeatedly scans the nonmagnetic surface.
Claim 2
Dependent Claim
128 words
In a magnetic printing and/or display device, apparatus for dusting the movable magnetizable surface of the device with magnetic powder comprising a convex nonmagnetic surface extending from a supply of the powder to a nonmagnetic ledge adjacent the magnetizable surface, and a magnetic rotor disposed behind the nonmagnetic surface and having its axis of rotation parallel thereto for producing at the nonmagnetic surface a system of magnetic flux which is divergent in a plane substantially perpendicular to the axis of rotation, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder to creep in the opposite direction along the nonmagnetic surface and across the ledge by somersaulting of the powder as the flux field repeatedly scans the nonmagnetic surface.
Claim 3
Dependent Claim
146 words
In a magnetic printing and/or display device, apparatus for dusting the movable magnetizable surface of the device with magnetic powder comprising a substantially horizontal nonmagnetic tube, a magnetic rotor inside the tube whose axis of rotation is parallel with the tube, the rotor producing a system of magnetic flux at the outer surface of the tube which is divergent in a plane perpendicular to the tube axis, and a nonmagnetic ledge extending substantially tangentially from the outer surface of the tube to adjacent the magnetizable surface, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder from a supply of the powder to creep up the outer surface of the tube in the opposite direction and across the ledge by somersaulting of the powder as the divergent flux system repeatedly scans the outer surface of the tube.
Claim 4
Dependent Claim
146 words
In a magnetic printing and/or display device, apparatus for dusting the movable magnetizable surface of the device with magnetic powder comprising a substantially horizontal nonmagnetic tube, a magnetic rotor inside the tube whose axis of rotation is parallel with the tube, the rotor producing a system of magnetic flux at the outer surface of the tube which is divergent in a plane perpendicular to the tube axis, and a nonmagnetic ledge extending substantially tangentially from the outer surface of the tube to adjacent the magnetizable surface, the arrangement being such that rotation of the rotor in a given direction causes a layer of magnetic powder from a supply of the powder to creep up the outer surface of the tube in the opposite direction and across the ledge by somersaulting of the powder as the divergent flux system repeatedly scans the outer surface of the tube.
Claim 5
Dependent Claim
28 words
Apparatus according to claim 2 wherein the magnetic rotor is a flat rectangular magnet magnetized from edge to edge in a direction perpendicular to its axis of rotation.
Claim 6
Dependent Claim
25 words
Apparatus according to claim 3 wherein the flat rectangular magnet comprises a plurality of mutually parallel bar magnets disposed side-by-side with their like poles adjacent.
Claim 7
Dependent Claim
21 words
Apparatus according to claim 4 wherein the tube is disposed along a trough in which the supply of powder is contained.
Claim 8
Dependent Claim
31 words
Apparatus according to claim 5 wherein the magnetizable surface is the cylindrical surface of a drum, the axis of rotation of the drum being vertically offset from that of the rotor.
References Cited (Backward Citations)
US3040704A
Cited
US3117891A
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US3392432A
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US3438706A
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US3553464A
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US3552355A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-07 | 1975-08-09 | 1976-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-07 | 1979-08-09 | 1980-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-07 | 1983-08-09 | 1984-02-08 | $7700.00 | Window Closed / Lapsed |