Patent US3759305A successfully refreshed from Google Patents.
US4331101A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrographic copying device with magnetic cylinder
Assignee: Magnetfabrik Bonn GmbH
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Filing: 1980-05-16
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Granted: 1982-05-25
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Expires: 2000-05-16
Abstract
Abstract The magnetic field which is required to hold image-forming toner particles on the tubular carrier of electrographic copiers is provided by single piece integrally formed permanent magnet bodies extending from end to end of the tubular carrier, the latter comprising a thin layer of ferromagnetic material to reduce the effect on inhomogeneities which may exist in the magnet bodies.
Inventors
- 👤 Werner Muller
- 👤 Erich A. Steingroever
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:16
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/0921; G03G2215/00; G03G2215/06; G03G2215/0634; G03G2215/0636
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
112 words
In electrographic copiers of the type wherein a toner-carrying device comprises a tubular shell of ferromagnetic material which cooperates with an assembly including a permanent magnet body to form images by means of toner particles having high magnetic permeability deposited on said device and the tubular shell comprises ferromagnetic material having a thickness to minimize the inhomogeneities in the magnetic field generated by said permanent magnet body, the improvement wherein said permanent magnet body consists of a single integrally formed body of permanent magnet material extending axially along substantially the entire length of said tubular ferromagnetic shell; and a coaxial tube of diamagnetic or nonmagnetic material to support said ferromagnetic tubular shell.
Claim 2
Dependent Claim
112 words
In electrographic copiers of the type wherein a toner-carrying device comprises a tubular shell of ferromagnetic material which cooperates with an assembly including a permanent magnet body to form images by means of toner particles having high magnetic permeability deposited on said device and the tubular shell comprises ferromagnetic material having a thickness to minimize the inhomogeneities in the magnetic field generated by said permanent magnet body, the improvement wherein said permanent magnet body consists of a single integrally formed body of permanent magnet material extending axially along substantially the entire length of said tubular ferromagnetic shell; and a coaxial tube of diamagnetic or nonmagnetic material to support said ferromagnetic tubular shell.
Claim 3
Dependent Claim
16 words
The invention defined in claim 1, wherein said toner-carrying device comprises a thin tube of iron.
Claim 4
Dependent Claim
60 words
The invention defined in claim 1, wherein said toner-carrying device comprises a tube of diamagnetic or nonmagnetic material, such as aluminum, magnesium, copper, zinc, stainless steel or plastic, or a diamagnetic or nonmagnetic alloy comprising one or more of said materials, such as aluminum-magnesium alloy, brass or fine zinc alloy, said tube being provided with a layer of ferromagnetic material.
Claim 5
Dependent Claim
19 words
The invention defined in claim 3, wherein said layer of ferromagnetic material comprises a thin plating of soft iron.
Claim 6
Dependent Claim
22 words
The invention defined in claim 3, wherein said layer of ferromagnetic material comprises a flame-sprayed coating of a material having ferromagnetic properties.
Claim 7
Dependent Claim
21 words
The invention defined in claim 5, wherein said tube comprises a light metal support provided with flame-sprayed coating of iron-aluminum powder.
Claim 8
Dependent Claim
18 words
The invention defined in claim 3, wherein said layer of ferromagnetic material is electrochemically deposited upon said tube.
Claim 9
Dependent Claim
19 words
The invention defined in claim 7, wherein said tube comprises brass provided with an electrochemically deposited coating of nickel.
Claim 10
Dependent Claim
28 words
The invention defined in any one of claims 1 through 8, wherein the thickness of the ferromagnetic layer lies approximately within the range of 0.1 to 1.0 mm.
Claim 11
Dependent Claim
27 words
The invention defined in any one of claims 1 through 8, wherein the thickness of the ferromagnetic layer lies within the range of 0.4 to 0.6 mm.
Claim 12
Dependent Claim
26 words
The invention defined in any one of claims 1 through 8, wherein said permanent magnet body comprises barium ferrite particles bonded together by a plastic composition.
Claim 13
Dependent Claim
23 words
The invention defined in claim 11, wherein the thickness of the ferromagnetic material lies approximately within the range of 0.1 to 1.0 mm.
Claim 14
Dependent Claim
23 words
The invention defined in claim 11, wherein the thickness of the ferromagnetic material lies approximately within the range of 0.4 to 0.6 mm.
References Cited (Backward Citations)
US4237819A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-24 | 1985-11-23 | 1986-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-24 | 1989-11-23 | 1990-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-24 | 1993-11-23 | 1994-05-25 | $7700.00 | Window Closed / Lapsed |