EP0331425A2
Expired / Lapsed
EP
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Image forming method and image forming apparatus
Assignee: Canon Inc
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Filing: 1989-02-28
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Granted: —
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Expires: 2009-02-28
Abstract
Abstract An image forming apparatus, comprises an electrostatic image-bearing member for holding an electrostatic charge image and a toner-carrying member having a surface for carrying a magnetic toner thereon, wherein the surface of the toner-carrying member has an unevenness comprising sphere-traced concavities formed by blasting with particles with a definite spherical shape; the magnetic toner comprises 17 - 60 % by number of particles of 5 microns or smaller, 1 - 23 % by number of particles of 8 - 12.7 microns, and 16 microns or larger and has a volume-average particle size of 4 - 11 microns; the electrostatic image-bearing member and the toner-carrying member are disposed with a prescribed gap therebetween at a developing station; means for forming a magnetic toner layer on the toner-carrying member in a thick which is thinner than the prescribed gap; and means for applying an alternating electric field for development with the magnetic toner at the developing station. The surface of the toner-carrying member comprising the sphere-traced concavities shows a function of uniformly forming a thin toner layer thereon when combined with the magnetic toner having a specific particle size distribution while the soiling of the surface is prevented for a long period.
Inventors
- 👤 Toshiaki Nakahara
- 👤 Hirohide Tanikawa
- 👤 Satoshi Yoshida
- 👤 Kiichiro Sakashita
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 23:04
CPC Classifications
G; G03; G03G; G03G13/00; G03G13/06; G03G13/08; G03G13/09; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/0921; G03G15/0928; G03G9/00; G03G9/08; G03G9/0819
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
155 words
An image forming apparatus, comprising: an electrostatic image-bearing member for holding an electrostatic charge image and a toner-carrying member having a surface for carrying a magnetic toner thereon, wherein the surface of the toner-carrying member has an unevenness comprising sphere-traced concavities formed by blasting with particles with a definite spherical shape; the magnetic toner comprises 17 - 60 % by number of particles of 5 microns or smaller, 1 - 23 % by number of particles of 8 - 12.7 microns, and 16 microns or larger and has a volume-average particle size of 4 - 11 microns; the electrostatic image-bearing member and the toner-carrying member are disposed with a prescribed gap therebetween at a developing station; means for forming a magnetic toner layer on the toner-carrying member in a thickness which is thinner than the prescribed gap; and means for applying an alternating electric field for development with the magnetic toner at the developing station.
Claim 2
Dependent Claim
155 words
An image forming apparatus, comprising: an electrostatic image-bearing member for holding an electrostatic charge image and a toner-carrying member having a surface for carrying a magnetic toner thereon, wherein the surface of the toner-carrying member has an unevenness comprising sphere-traced concavities formed by blasting with particles with a definite spherical shape; the magnetic toner comprises 17 - 60 % by number of particles of 5 microns or smaller, 1 - 23 % by number of particles of 8 - 12.7 microns, and 16 microns or larger and has a volume-average particle size of 4 - 11 microns; the electrostatic image-bearing member and the toner-carrying member are disposed with a prescribed gap therebetween at a developing station; means for forming a magnetic toner layer on the toner-carrying member in a thickness which is thinner than the prescribed gap; and means for applying an alternating electric field for development with the magnetic toner at the developing station.
Claim 3
Dependent Claim
26 words
An image forming apparatus according to Claim 1, wherein the toner-carrying member has sphere-traced concavities having a diameter of 20 - 250 microns on the surface.
Claim 4
Dependent Claim
23 words
An image forming apparatus according to Claim 2, wherein the toner-carrying member has sphere-traced concavities on the entire surface for carrying the toner.
Claim 5
Dependent Claim
33 words
An image forming apparatus according to Claim 3, wherein the toner-carrying member has the sphere-traced concavities so as to provide a surface unevenness pitch P of 2 to 100 microns on the surface.
Claim 6
Dependent Claim
34 words
An image forming apparatus according to Claim 4, wherein the toner-carrying member has the sphere-traced concavities so as to provide a surface roughness d of 0.1 to 5 microns on the toner-carrying member surface.
Claim 7
Dependent Claim
24 words
An image forming apparatus according to Claim 1, wherein the sphere-traced concavities on the toner-carrying member have been formed by blasting of solid spheres.
Claim 8
Dependent Claim
42 words
An image forming apparatus according to Claim 6, wherein the sphere-traced concavities on the toner-carrying member have been formed by blasting of definite-shaped particles containing 80 % by number or more of glass beads having a diameter of 53 to 62 microns.
Claim 9
Dependent Claim
22 words
An image forming apparatus according to Claim 1, wherein the magnetic toner has a volume-average particle size of 6 to 10 microns.
Claim 10
Dependent Claim
86 words
An image forming apparatus according to Claim 1, wherein the magnetic toner has a particle size distribution satisfying the following formula: N/V = -0.04N + k, wherein N denotes the value of % by number of magnetic particles having a size of 5 microns or smaller, V denotes the value of % by volume of magnetic particles having a size of 5 microns or smaller, k is a positive number of from 4.5 to 6.5, and the N is a positive number of 17 to 60.
Claim 11
Dependent Claim
16 words
An image forming apparatus according to Claim 1, wherein the magnetic toner contains a charge controller.
Claim 12
Dependent Claim
26 words
An image forming apparatus according to Claim 10, wherein the magnetic toner contains a nigrosine compound or an organic quaternary ammonium salt as the charge controller.
Claim 13
Dependent Claim
26 words
An image forming apparatus according to Claim 10, wherein the magnetic toner contains an organic metal complex or an organic metal salt as the charge controller.
Claim 14
Dependent Claim
24 words
An image forming apparatus according to Claim 12, wherein the magnetic toner contains a salicylic acid-type metal salt or a salicylic acid-type metal complex.
Claim 15
Dependent Claim
26 words
An image forming apparatus according to Claim 1, wherein the magnetic toner contains 0.5 to 5 wt. % of a wax based on the binder resin.
Claim 16
Dependent Claim
30 words
An image forming apparatus according to Claim 1, wherein the magnetic toner comprises 60 - 120 wt. parts of a magnetic material per 100 wt. parts of a resinous component.
Claim 17
Dependent Claim
22 words
An image forming apparatus according to Claim 15, wherein the magnetic material has an average particle size of 0.1 to 1 micron.
Claim 18
Dependent Claim
24 words
An image forming apparatus according to Claim 1, wherein the magnetic toner is triboelectrically charged by contact with the surface of the toner-carrying member.
Claim 19
Dependent Claim
38 words
An image forming apparatus according to Claim 17, wherein the toner-carrying member is a cylindrical electroconductive sleeve containing a magnetic field generating means inside thereof, and the magnetic field generating means and the electroconductive sleeve are relatively moved.
Claim 20
Dependent Claim
29 words
An image forming apparatus according to Claim 1, wherein 100 wt. parts of the magnetic toner is mixed with 0.01 to 8 wt. parts of a silica fine powder.
Claim 21
Dependent Claim
29 words
An image forming apparatus according to Claim 19, wherein 100 wt. parts of the magnetic toner is mixed with 0.01 to 5 wt. parts of the silica fine powder.
Claim 22
Dependent Claim
44 words
An image forming apparatus according to Claim 19, wherein the magnetic toner is a positively chargeable magnetic toner, and the silica fine powder comprises a positively chargeable hydrophobic silica fine powder treated with a silicone oil having a nitrogen atom in its side chain.
Claim 23
Dependent Claim
25 words
An image forming apparatus according to Claim 1, wherein the magnetic toner is mixed with a silica fine powder and a fluorine-containing polymer fine powder.
Claim 24
Dependent Claim
19 words
An image forming apparatus according to Claim 1, wherein the toner-carrying member comprises an electroconductive sleeve of stainless steel.
Claim 25
Dependent Claim
153 words
An image forming method, comprising: disposing an electrostatic image-bearing member for holding an electrostatic charge image and a toner-carrying member for carrying a magnetic toner with a prescribed gap therebetween at a developing station, wherein the surface of the toner-carrying member has an unevenness comprising sphere-traced concavities formed by blasting with particles with a definite spherical shape; the magnetic toner comprises 17 - 60 % by number of particles of 5 microns or smaller, 1 - 23 % by number of particles of 8 - 12.7 microns, and 2.0 % by volume or less of particles of 16 microns or larger and has a volume-average particle size of 4 - 11 microns; conveying the magnetic toner in a layer regulated in a thickness thinner than the prescribed gap to the developing station; and applying an alternating electric field to the toner-carrying member at the developing station to effect development with the magnetic toner.
Claim 26
Dependent Claim
153 words
An image forming method, comprising: disposing an electrostatic image-bearing member for holding an electrostatic charge image and a toner-carrying member for carrying a magnetic toner with a prescribed gap therebetween at a developing station, wherein the surface of the toner-carrying member has an unevenness comprising sphere-traced concavities formed by blasting with particles with a definite spherical shape; the magnetic toner comprises 17 - 60 % by number of particles of 5 microns or smaller, 1 - 23 % by number of particles of 8 - 12.7 microns, and 2.0 % by volume or less of particles of 16 microns or larger and has a volume-average particle size of 4 - 11 microns; conveying the magnetic toner in a layer regulated in a thickness thinner than the prescribed gap to the developing station; and applying an alternating electric field to the toner-carrying member at the developing station to effect development with the magnetic toner.
Claim 27
Dependent Claim
55 words
An image forming method according to Claim 24, wherein the magnetic toner having a triboelectric charge is reciprocally moved between the electrostatic image-bearing member and the toner-carrying member to develop the electrostatic image in a magnetic field and under the action of an alternating electric field formed by superposition of AC bias and DC bias.
Claim 28
Dependent Claim
57 words
An image forming method according to Claim 24 or 25, wherein the toner carrying member is as claimed in any of claims 2 to 7 and/or the magnetic toner is as claimed in any of Claims 8 to 17 or 19 to 22 or wherein the toner carrying member is as claimed in Claim 18 or 23.
Claim 29
Dependent Claim
28 words
A member for holding an electrostatic charge image having a surface rendered uneven by generally spherical cavities formed by blasting the surface with spherical or generally spheroidal particles.
Claim 30
Dependent Claim
28 words
A member for holding an electrostatic charge image having a surface rendered uneven by generally spherical cavities formed by blasting the surface with spherical or generally spheroidal particles.
References Cited (Backward Citations)
No citation records indexed.
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