US5409791A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Image forming method and apparatus
Assignee: Eastman Kodak Co
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Filing: 1993-05-20
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Granted: 1995-04-25
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Expires: 2013-05-20
Abstract
Abstract An electrostatic image on an image member already containing a loose dry first toner image is toned with a second toner, for example, a toner of a second and different color from the first toner image. The toning is accomplished by a developer having a high coercivity permanently magnetized carrier and toner which is moved through a development zone by a rapidly rotating core inside a sleeve on which the developer moves. Pole transitions caused by the rapidly moving core make the high coercivity permanently magnetized carrier move vigorously in a wave motion having alternating crests and troughs. Scavenging of the first toner image is prevented by separating the sleeve from the image member sufficiently that the crests of the developer do not touch the image member during the toning process. An alternating electrical field is applied between the sleeve and the image member to enhance development.
Inventors
- 👤 Joseph Y. Kaukeinen
- 👤 Thomas A. Jadwin
- 👤 Peter S. Alexandrovich
- 👤 Eric C. Stelter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:18
CPC Classifications
G; G03; G03G; G03G13/00; G03G13/06; G03G13/08; G03G13/09; G03G15/00; G03G15/01; G03G15/0105; G03G15/0126; G03G9/00; G03G9/08; G03G9/10; G03G9/107
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
177 words
An image forming method comprising: forming a first dry unfixed toner image on a frame or area of an image member, without fixing said first toner image, forming an electrostatic image on the frame or area of the image member, without fixing the first toner image, applying toner to the electrostatic image to form a second toner image on the image member, said applying step including: supplying a two component developer including high coercivity, permanently magnetized magnetic carrier particles and toner particles to an applicator having a rotatable magnetic core having alternating poles around its periphery and a shell around said core; rotating said core within said shell to create a rapidly changing magnetic field on the surface of the shell while moving the developer either by core rotation or shell rotation or both along the shell in a wave motion having alternating crests and troughs through close proximity with an image member but without the crests of the developer contacting the image member, and applying an alternating electrical field between the shell and the image member.
Claim 2
Dependent Claim
177 words
An image forming method comprising: forming a first dry unfixed toner image on a frame or area of an image member, without fixing said first toner image, forming an electrostatic image on the frame or area of the image member, without fixing the first toner image, applying toner to the electrostatic image to form a second toner image on the image member, said applying step including: supplying a two component developer including high coercivity, permanently magnetized magnetic carrier particles and toner particles to an applicator having a rotatable magnetic core having alternating poles around its periphery and a shell around said core; rotating said core within said shell to create a rapidly changing magnetic field on the surface of the shell while moving the developer either by core rotation or shell rotation or both along the shell in a wave motion having alternating crests and troughs through close proximity with an image member but without the crests of the developer contacting the image member, and applying an alternating electrical field between the shell and the image member.
Claim 3
Independent Claim
193 words
A method of developing an electrostatic image on an image member that has an unfixed dry toner image in the same frame as the electrostatic image, said method comprising: supplying a two component developer comprising charged toner particles and oppositely charged carrier particles, said carrier particles having a coercivity of at least 300 gauss when magnetically saturated and exhibiting an induced magnetic moment of at least 20 EMU per gram when in an applied field of 1000 gauss, to an applicator having a rotatable magnetic core having at least eight alternating poles around its periphery and a shell around the core, and rotating said core within said shell at a speed of at least 300 rpm to create a rapidly changing magnetic field on the surface of the shell while moving the developer by core rotation, shell rotation or both in a wave motion having alternating crests and troughs through close proximity with the image member but without the crests of the developer contacting the image member, and applying an alternating field of at least 500 peak-to-peak volts and a frequency of at least 300 hertz between the image member and the shell.
Claim 4
Independent Claim
193 words
A method of developing an electrostatic image on an image member that has an unfixed dry toner image in the same frame as the electrostatic image, said method comprising: supplying a two component developer comprising charged toner particles and oppositely charged carrier particles, said carrier particles having a coercivity of at least 300 gauss when magnetically saturated and exhibiting an induced magnetic moment of at least 20 EMU per gram when in an applied field of 1000 gauss, to an applicator having a rotatable magnetic core having at least eight alternating poles around its periphery and a shell around the core, and rotating said core within said shell at a speed of at least 300 rpm to create a rapidly changing magnetic field on the surface of the shell while moving the developer by core rotation, shell rotation or both in a wave motion having alternating crests and troughs through close proximity with the image member but without the crests of the developer contacting the image member, and applying an alternating field of at least 500 peak-to-peak volts and a frequency of at least 300 hertz between the image member and the shell.
Claim 5
Dependent Claim
17 words
The method according to claim 2 wherein the coercivity of the carrier is at least 1000 gauss.
Claim 6
Dependent Claim
17 words
The method according to claim 2 wherein the coercivity of the carrier is at least 1500 gauss.
Claim 7
Dependent Claim
20 words
The method according to claim 2 wherein the induced magnetic moment of the carrier particles is at least 25 EMU/gm.
Claim 8
Dependent Claim
20 words
The method according to claim 4 wherein the induced magnetic moment of the carrier particles is at least 25 EMU/gm.
Claim 9
Dependent Claim
16 words
The method according to claim 4 wherein the induced magnetic moment is at least 30 EMU/gm.
Claim 10
Dependent Claim
25 words
The method according to claim 2 wherein the step of rotating the core includes rotating the core at a speed of at least 1000 rpm.
Claim 11
Dependent Claim
25 words
The method according to claim 8 wherein the step of rotating the core includes rotating the core at a speed of at least 1500 rpm.
Claim 12
Dependent Claim
25 words
The method according to claim 4 wherein the step of rotating the core includes rotating the core at a speed of at least 1500 rpm.
Claim 13
Dependent Claim
24 words
The method according to claim 10 wherein the step of rotating includes rotating a core having at least ten magnetic poles around its periphery.
Claim 14
Dependent Claim
21 words
The method according to claim 2 wherein rotating includes rotating a core having at least 12 magnetic poles around its periphery.
Claim 15
Dependent Claim
24 words
The method according to claim 12 wherein the step of rotating the core includes rotating the core at a speed of at least 1000
Claim 16
Dependent Claim
22 words
The method according to claim 2 wherein said shortest distance between the shell and the image member is at least 0.75 mm.
Claim 17
Dependent Claim
34 words
The method according to claim 2 wherein the number of poles of the core and the speed of the core are such to provide at least 200 pole transitions per second on the shell.
Claim 18
Dependent Claim
18 words
The method according to claim 15 wherein the number of pole transitions is at least 300 per second.
Claim 19
Dependent Claim
24 words
The method according to claim 2 wherein the image member and the developer are moved in the same direction at substantially the same speed.
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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) | 1998-04-24 | 1998-10-24 | 1999-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-24 | 2002-10-24 | 2003-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-24 | 2006-10-24 | 2007-04-25 | $7700.00 | Window Closed / Lapsed |