Patent US5532804A successfully refreshed from Google Patents.
US5532804A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for developing an electrostatic image on an image member
Assignee: Fujifilm Business Innovation Corp
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Filing: 1994-07-15
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Granted: 1996-07-02
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Expires: 2014-07-15
Abstract
Abstract A developing device, which has a developer carrying member forming a magnetic brush of a two-component developer and is capable of carrying out a development while it is not in contact with an electrostatic latent image retaining member, is improved so as to reproduce an image at a sufficient image density.
Inventors
- 👤 Kei Hirata
- 👤 Tomoyoshi Chihara
- 👤 Nobumasa Furuya
- 👤 Takeshi Sumikawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:16
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/0921
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
178 words
A developing device for developing a latent image formed on an electrostatic latent image retaining member, comprising: a developer carrying member having a circumferential surface portion for transporting a magnetically attracted two-component developer containing magnetic carriers and nonmagnetic toner disposed facing said electrostatic latent image retaining member, wherein an alternating electric field is formed in a developing area where said electrostatic latent image retaining member faces said developer carrying member, the nonmagnetic toner of the two-component developer, which is kept in noncontact with said developer carrying member, is transferred to said electrostatic latent image retaining member in the alternating electric field, thereby visualizing an electrostatic latent image formed thereon; a magnet concentrically disposed within said developer carrying member and having an array of magnetic poles of different polarities alternately and circumferentially arrayed at the surface thereof at such a pitch that a plural number of the magnetic polarities are contained in the developing area, and wherein said magnetic pole pitch is established to be longer than a distance between said magnet surface and said developer carrying member surface.
Claim 2
Dependent Claim
178 words
A developing device for developing a latent image formed on an electrostatic latent image retaining member, comprising: a developer carrying member having a circumferential surface portion for transporting a magnetically attracted two-component developer containing magnetic carriers and nonmagnetic toner disposed facing said electrostatic latent image retaining member, wherein an alternating electric field is formed in a developing area where said electrostatic latent image retaining member faces said developer carrying member, the nonmagnetic toner of the two-component developer, which is kept in noncontact with said developer carrying member, is transferred to said electrostatic latent image retaining member in the alternating electric field, thereby visualizing an electrostatic latent image formed thereon; a magnet concentrically disposed within said developer carrying member and having an array of magnetic poles of different polarities alternately and circumferentially arrayed at the surface thereof at such a pitch that a plural number of the magnetic polarities are contained in the developing area, and wherein said magnetic pole pitch is established to be longer than a distance between said magnet surface and said developer carrying member surface.
Claim 3
Dependent Claim
25 words
The developing device of claim 1, wherein said magnetic poles of different polarities are alternately arrayed at a part of the circumference of said magnet.
Claim 4
Dependent Claim
23 words
The developing device of claim 1, wherein said magnetic poles of different polarities are alternately arrayed about the entire circumference of said magnet.
Claim 5
Dependent Claim
14 words
The developing device of claim 1, wherein said circumferential portion is a conductive sleeve.
Claim 6
Dependent Claim
20 words
The developing device of claim 1, wherein said circumferential portion is a conductive layer on the surface of said magnet.
Claim 7
Dependent Claim
16 words
The developing device of claim 5, wherein said conductive layer and said magnet are independently turned.
Claim 8
Dependent Claim
30 words
The developing device of claim 1, wherein said circumferential portion and said magnet are combined such that said circumferential portion and said magnet are stuck together and turned in unison.
Claim 9
Dependent Claim
22 words
The developing device of claim 1, wherein said developer carrying member has a magnetic field intensity between 200 Gauss and 1000 Gauss.
Claim 10
Dependent Claim
20 words
The developing device of claim 1, wherein said magnetic carriers have a saturation magnetization between 20 emu/g and 70 emu/g.
Claim 11
Dependent Claim
21 words
The developer device of claim 1, wherein said magnetic carriers have an average particle diameter between 20 μm and 70 μm.
Claim 12
Dependent Claim
20 words
The developing device of claim 1, wherein said toner has an average particle diameter between 5 μm and 10 μm.
Claim 13
Dependent Claim
20 words
The developing device of claim 1, wherein said toner has a charge quantity range between 5 μc/g and 50 μc/g.
Claim 14
Dependent Claim
77 words
The developing device of claim 1, wherein said magnetic pole pitch is smaller than a width of an effective developing area defined by a region in which toners attach to a latent image formed on said electrostatic latent image retaining member when an alternating electric field is applied which is the same as the electric field applied when developing in a state in which said developing carrying member and said electrostatic retaining member are at a standstill.
Claim 15
Dependent Claim
174 words
An image forming device comprising at least one non-contact developing device which comprises: a developer carrying member having a circumferential surface portion for transporting a magnetically attracted two-component developer containing magnetic carriers and nonmagnetic toner disposed facing said electrostatic latent image retaining member, wherein an alternating electric field is formed in a developing area where said electrostatic latent image retaining member faces said developer carrying member, the nonmagnetic toner of the two-component developer, which is kept in noncontact with said developer carrying member, is transferred to said electrostatic latent image retaining member in the alternating electric field, thereby visualizing an electrostatic latent image formed thereon, a magnet concentrically disposed within said developer carrying member and having an array of magnetic poles of different polarities alternately and circumferentially arrayed at the surface thereof at such a pitch that a plural number of the magnetic polarities are contained in the developing area, and wherein said magnetic pole pitch is established to be longer than a distance between said magnet surface and said developer carrying member surface.
Claim 16
Dependent Claim
174 words
An image forming device comprising at least one non-contact developing device which comprises: a developer carrying member having a circumferential surface portion for transporting a magnetically attracted two-component developer containing magnetic carriers and nonmagnetic toner disposed facing said electrostatic latent image retaining member, wherein an alternating electric field is formed in a developing area where said electrostatic latent image retaining member faces said developer carrying member, the nonmagnetic toner of the two-component developer, which is kept in noncontact with said developer carrying member, is transferred to said electrostatic latent image retaining member in the alternating electric field, thereby visualizing an electrostatic latent image formed thereon, a magnet concentrically disposed within said developer carrying member and having an array of magnetic poles of different polarities alternately and circumferentially arrayed at the surface thereof at such a pitch that a plural number of the magnetic polarities are contained in the developing area, and wherein said magnetic pole pitch is established to be longer than a distance between said magnet surface and said developer carrying member surface.
Claim 17
Dependent Claim
44 words
An image forming device according to claim 14 comprising a plural number of developing devices, wherein one of said developing devices is said non-contact developing device for developing an electrostatic latent image formed in advance on an electrostatic latent image retaining member with toner.
Claim 18
Dependent Claim
174 words
A developing device for developing a latent image formed on an electrostatic latent image retaining member, comprising: a non-magnetic developer carrying member having a circumferential surface portion for transporting a magnetically attracted two-component developer containing magnetic carriers and nonmagnetic toner disposed facing said electrostatic latent image retaining member, wherein an alternating electric field is formed in a developing area where said electrostatic latent image retaining member faces said developer carrying member, the nonmagnetic toner of the two-component developer, which is kept in noncontact with said developer carrying member, is transferred to said electrostatic latent image retaining member in the alternating electric field, thereby visualizing an electrostatic latent image formed thereon wherein a magnet concentrically disposed within said developer carrying member and having an array of magnetic poles of different polarities alternately and circumferentially arrayed at the surface thereof at such a pitch that a plural number of the magnetic polarities are contained in the developing area, and wherein said magnetic poles of different polarities are alternately arrayed about the entire circumference of said magnet.
Claim 19
Dependent Claim
174 words
A developing device for developing a latent image formed on an electrostatic latent image retaining member, comprising: a non-magnetic developer carrying member having a circumferential surface portion for transporting a magnetically attracted two-component developer containing magnetic carriers and nonmagnetic toner disposed facing said electrostatic latent image retaining member, wherein an alternating electric field is formed in a developing area where said electrostatic latent image retaining member faces said developer carrying member, the nonmagnetic toner of the two-component developer, which is kept in noncontact with said developer carrying member, is transferred to said electrostatic latent image retaining member in the alternating electric field, thereby visualizing an electrostatic latent image formed thereon wherein a magnet concentrically disposed within said developer carrying member and having an array of magnetic poles of different polarities alternately and circumferentially arrayed at the surface thereof at such a pitch that a plural number of the magnetic polarities are contained in the developing area, and wherein said magnetic poles of different polarities are alternately arrayed about the entire circumference of said magnet.
Claim 20
Dependent Claim
30 words
The developing device of claim 16, wherein said circumferential portion is a conductive layer on the surface of said magnet, wherein said conductive layer and said magnet are independently turned.
Claim 21
Dependent Claim
30 words
The developing device of claim 16, wherein said circumferential portion and said magnet are combined such that said circumferential portion and said magnet are stuck together and turned in unison.
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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) | 1999-07-02 | 2000-01-01 | 2000-07-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-07-02 | 2004-01-01 | 2004-07-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-07-02 | 2008-01-01 | 2008-07-02 | $7700.00 | Window Closed / Lapsed |