Patent US4356245A successfully refreshed from Google Patents.
US4356245A
Expired / Lapsed
US
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Method and apparatus for electrophotographic, image development with magnetic toner
Assignee: Canon Inc
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Filing: 1980-04-21
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Granted: 1982-10-26
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Expires: 2000-04-21
Abstract
Abstract A method and apparatus for developing an electrostatic image on an electrostatic image holding member by feeding toner particles thereto, in which a layer of the toner particles is formed on a toner carrying member, and the toner carrying member and the electrostatic image holding member are brought to a mutually closer position and maintained in such a range that the surface of a non-image section of the electrostatic image holding member and the surface of the toner particle layer on the toner carrying member may not be contacted with each other, but the surface of the toner particle layer is in contact with the surface of the image region of the electrostatic image holding member, whereby uniform development of the electrostatic image on the image holding member can be effected.
Inventors
- 👤 Nagao Hosono
- 👤 Koichi Kinoshita
- 👤 Toru Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 05:50
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/09
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
269 words
A development method for developing an electrostatic image held on an electrostatic image holding member which can be used repeatedly for electrostatic latent image formation, said method comprising the steps of: forming a layer of magnetic toner particles on a surface of a toner carrying member, said toner carrying member being made of a non-magnetic material and having a stationary magnetic pole at a developing zone on the opposite side of said toner particle layer forming surface thereof to establish a stationary magnetic field directed toward the surface of the electrostatic image holding member; bringing said toner carrying member provided with the magnetic toner particle layer on the surface thereof adjacent to the electrostatic image holding member provided with an electrostatic image on its surface; and maintaining said toner carrying member and the electrostatic image holding member in a spacing range at the developing zone to form a space gap between the electrostatic image holding member and the surface of the layer of toner particles where the stationary magnetic field at the developing zone is effective to orient the magnetic toner particles in the direction of the magnetic field to assist in the deposition of toner particles on the image region of the electrostatic image holding member due to the attraction of the electrostatic field generating therefrom, the stationary magnetic field alone being insufficient to transfer the magnetic toner particles to the non-image background region of the electrostatic image holding member which has no substantial electrostatic field such that in the absence of an electrostatic image on the image holding member, no toner particles contact the image holding member.
Claim 2
Dependent Claim
269 words
A development method for developing an electrostatic image held on an electrostatic image holding member which can be used repeatedly for electrostatic latent image formation, said method comprising the steps of: forming a layer of magnetic toner particles on a surface of a toner carrying member, said toner carrying member being made of a non-magnetic material and having a stationary magnetic pole at a developing zone on the opposite side of said toner particle layer forming surface thereof to establish a stationary magnetic field directed toward the surface of the electrostatic image holding member; bringing said toner carrying member provided with the magnetic toner particle layer on the surface thereof adjacent to the electrostatic image holding member provided with an electrostatic image on its surface; and maintaining said toner carrying member and the electrostatic image holding member in a spacing range at the developing zone to form a space gap between the electrostatic image holding member and the surface of the layer of toner particles where the stationary magnetic field at the developing zone is effective to orient the magnetic toner particles in the direction of the magnetic field to assist in the deposition of toner particles on the image region of the electrostatic image holding member due to the attraction of the electrostatic field generating therefrom, the stationary magnetic field alone being insufficient to transfer the magnetic toner particles to the non-image background region of the electrostatic image holding member which has no substantial electrostatic field such that in the absence of an electrostatic image on the image holding member, no toner particles contact the image holding member.
Claim 3
Dependent Claim
50 words
The development method as claimed in claim 1, wherein the space gap between the surface of the toner particle layer on said toner carrying member and the surface of the electrostatic image holding member is maintained 10 times or below as large as the thickness of the toner particle layer.
Claim 4
Dependent Claim
49 words
The development method as claimed in claim 2 or 1, wherein the space gap between the surface of the toner particle layer on said toner carrying member and the surface of the electrostatic image holding member is maintained 1/5 or above of the thickness of the toner particle layer.
Claim 5
Dependent Claim
27 words
The development method as claimed in claim 3, wherein the thickness of the toner particle layer formed on said toner carrying member is 30 microns and above.
Claim 6
Dependent Claim
55 words
The development method as claimed in claim 1, wherein, at the time of forming the toner particle layer on said toner carrying member, the thickness of the toner particle layer to be applied to said toner carrying member is regulated by a layer thickness regulating member to obtain a toner particle layer of uniform thickness.
Claim 7
Dependent Claim
65 words
The development method as claimed in claim 1, wherein said toner carrying member is provided with an electrically conductive electrode, and the development is effected in a relationship of D<5c, where D represents the space gap between said electrically conductive electrode and the electrostatic image holding member, and c denotes the minimum image width of the electrostatic image formed on the electrostatic image holding member.
Claim 8
Dependent Claim
56 words
The development method as claimed in claim 6, wherein the development is effected in such a relationship that the space gap D between said electrically conductive electrode and the electrostatic image holding member is greater than the space gap between the surface of said toner particle layer and the surface of the electrostatic image holding member.
Claim 9
Dependent Claim
253 words
A development device for developing an electrostatic image held on an electrostatic image holding member which can be used repeatedly for electrostatic latent image formation, said device comprising in combination: toner carrying means having a surface to hold a toner particle layer thereon, said toner carrying means being made of a non-magnetic material; magnet means for generating a stationary magnetic field at a developing zone through said non-magnetic toner carrying means toward the surface of the electrostatic image holding member; means for forming a layer of magnetic toner particles of substantially uniform thickness on said surface of said toner carrying means; means for moving the magnetic toner layer from said toner layer forming means to a developing zone; and means for maintaining a space between said toner carrying means and the electrostatic image holding member at the developing zone within a predetermined range to form a space gap between the electrostatic image holding member and the surface of the layer of toner particles, wherein the stationary magnetic field at the developing zone is directed toward the electrostatic image holding member to thereby assist in depositing toner particles on the image region of the electrostatic image holding member due to the attraction of the electrostatic field generating therefrom, the stationary magnetic field being insufficient to transfer the magnetic toner particles to the non-image background region of the electrostatic image holding member such that in the absence of an electrostatic image no toner particles contact with the image holding member, whereby background development is prevented.
Claim 10
Dependent Claim
253 words
A development device for developing an electrostatic image held on an electrostatic image holding member which can be used repeatedly for electrostatic latent image formation, said device comprising in combination: toner carrying means having a surface to hold a toner particle layer thereon, said toner carrying means being made of a non-magnetic material; magnet means for generating a stationary magnetic field at a developing zone through said non-magnetic toner carrying means toward the surface of the electrostatic image holding member; means for forming a layer of magnetic toner particles of substantially uniform thickness on said surface of said toner carrying means; means for moving the magnetic toner layer from said toner layer forming means to a developing zone; and means for maintaining a space between said toner carrying means and the electrostatic image holding member at the developing zone within a predetermined range to form a space gap between the electrostatic image holding member and the surface of the layer of toner particles, wherein the stationary magnetic field at the developing zone is directed toward the electrostatic image holding member to thereby assist in depositing toner particles on the image region of the electrostatic image holding member due to the attraction of the electrostatic field generating therefrom, the stationary magnetic field being insufficient to transfer the magnetic toner particles to the non-image background region of the electrostatic image holding member such that in the absence of an electrostatic image no toner particles contact with the image holding member, whereby background development is prevented.
Claim 11
Dependent Claim
26 words
The development device as claimed in claim 8, wherein the toner carrying surface of said toner carrying means is formed in a movable and endless shape.
Claim 12
Dependent Claim
41 words
The development device as claimed in claim 8, wherein said toner carrying means is provided with a toner particle layer thickness regulating member to regulate the toner particle layer to be formed on the toner carrying surface to a predetermined thickness.
Claim 13
Dependent Claim
45 words
The development device as claimed in claim 9, wherein said toner carrying means is provided with a corona discharge generating source to apply corona discharge on the toner carrying surface thereof prior to formation of the toner particle layer on the toner carrying surface thereof.
Claim 14
Dependent Claim
31 words
The development device as claimed in claim 10, wherein said toner particle layer thickness regulating member is made of a material which imparts a predetermined charge characteristic to the toner particles.
Claim 15
Dependent Claim
56 words
The development device as claimed in claim 8, wherein said gap maintaining means maintains the space gap between the surface of the toner particle layer on said toner carrying surface and the surface of the electrostatic image holding member at a value 10 times or below as large as the thickness of the toner particle layer.
Claim 16
Dependent Claim
56 words
The development device as claimed in claim 13 or 8, wherein said space gap maintaining means maintains the space gap between the surface of the toner particle layer on said toner carrying surface and the surface of the electrostatic image holding member at a value 1/5 and above of the thickness of the toner particle layer.
Claim 17
Dependent Claim
40 words
The development device as claimed in claim 8, wherein said space gap maintaining means is provided with a space roller inserted between the surface of the electrostatic image holding member and the toner carrying surface of said toner carrying means.
Claim 18
Dependent Claim
14 words
A method according to claim 1, wherein said toner carrying member is electrically conductive.
Claim 19
Dependent Claim
15 words
A developing device according to claim 8, wherein said toner carrying member is electrically conductive.
Claim 20
Dependent Claim
27 words
The development device as claimed in claim 14, wherein the thickness of the toner particle layer formed on said toner carrying means is 30 microns or more.
Claim 21
Dependent Claim
14 words
A development method according to claim 1, wherein said toner particles are electrically insulative.
Claim 22
Dependent Claim
14 words
A development device according to claim 8, wherein said toner particles are electrically insulative.
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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) | 1985-10-25 | 1986-04-26 | 1986-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-25 | 1990-04-26 | 1990-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-25 | 1994-04-26 | 1994-10-26 | $7700.00 | Window Closed / Lapsed |