US3890928A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic brush for use in developing electrophotographic images
Assignee: WIFO FORSCHUNGSINST AG
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Filing: 1973-12-20
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Granted: 1975-06-24
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Expires: 1993-12-20
Abstract
Abstract A magnetic brush for use in applying to a latent electrophotographic image on a carrier sheet a developer powder constituted by a mixture of particles of magnetizable material and a powdered toner and comprising a rotatable hollow cylinder of non-magnetic material and a stationary permanent magnet disposed within the cylinder, in which the cylinder also contains a screen of magnetizable material, the magnet and the screen being so disposed in relation to the cylinder as to produce at the surface thereof successive magnetic field zones of medium intensity sufficient to take up developer powder, of higher intensity for causing filaments to project radially from the cylinder for application of toner powder to the image and of intensity low enough to shed developer powder from the cylinder.
Inventors
- 👤 Peter Jeanmaire
- 👤 Paul Heinzer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:16
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/0921
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
176 words
A magnetic brush for use in applying to a latent electrophotographic image on a carrier sheet a developer powder composed of a mixture of particles of magnetizable material and a powdered toner, comprising a rotatable hollow cylinder of nonmagnetic material and a stationary magnetic excitation system disposed within the cylinder and producing at the surface of the cylinder successive magnetic field zones of medium intensity sufficient to take up the developer powder zones, of higher intensity for causing filaments to project radially from the cylinder for application of toner powder to the image and zones of intensity low enough to shed the developer powder from the cylinder, the magnetic excitation system comprising a permanent magnet extending axially of the cylinder in a position offset from the axis of the cylinder with its axis of magnetization extending radially with respect to the cylinder and one pole in close proximity to the inner wall of the cylinder, and a screen of magnetizable material also extending axially of the cylinder and disposed adjacent the other pole of the magnet.
Claim 2
Dependent Claim
176 words
A magnetic brush for use in applying to a latent electrophotographic image on a carrier sheet a developer powder composed of a mixture of particles of magnetizable material and a powdered toner, comprising a rotatable hollow cylinder of nonmagnetic material and a stationary magnetic excitation system disposed within the cylinder and producing at the surface of the cylinder successive magnetic field zones of medium intensity sufficient to take up the developer powder zones, of higher intensity for causing filaments to project radially from the cylinder for application of toner powder to the image and zones of intensity low enough to shed the developer powder from the cylinder, the magnetic excitation system comprising a permanent magnet extending axially of the cylinder in a position offset from the axis of the cylinder with its axis of magnetization extending radially with respect to the cylinder and one pole in close proximity to the inner wall of the cylinder, and a screen of magnetizable material also extending axially of the cylinder and disposed adjacent the other pole of the magnet.
Claim 3
Dependent Claim
26 words
A magnetic brush according to claim 1, in which the screen has fan shaped ends extending to The vicinity of the inner walls of the cylinder.
Claim 4
Dependent Claim
18 words
A magnetic brush according to claim 2, in which the screen consists of laminations attached to the magnet.
Claim 5
Dependent Claim
29 words
A magnetic brush as claimed in claim 1, in which the magnet is a cylindrical bar magnet and has a diameter not less than the radius of the cylinder.
Claim 6
Dependent Claim
30 words
A magnetic brush as claimed in claim 1, in which the magnet is a rectangular bar magnet and has a curved pole piece facing the inner wall of the cylinder.
Claim 7
Dependent Claim
53 words
Apparatus for developing latent electrophotographic images, comprising a container for developer powder, means for agitating the developer powder, and a magnetic brush as claimed in claim 1 rotatably mounted in the container with its axis horizontal and in position to pick up developer powder from the container and transfer it to the images.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-23 | 1978-12-23 | 1979-06-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-23 | 1982-12-23 | 1983-06-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-23 | 1986-12-23 | 1987-06-24 | $7700.00 | Window Closed / Lapsed |