Patent JPS63227779A successfully refreshed from Google Patents.
Patent EP0709746A1 successfully refreshed from Google Patents.
EP0709746A1
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Image forming method, image forming apparatus and process cartridge
Assignee: Canon Inc
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Filing: 1995-10-31
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Granted: —
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Expires: 2015-10-31
Abstract
Abstract The image forming method comprises, electrostatically charging an image bearing member using a contact charging assembly (2), forming an electrostatic latent image on the image bearing member (1) thus charged, developing the electrostatic latent image with a magnetic toner to form a toner image and transferring the toner image to a transfer medium, wherein the charging assembly (2) comprises a magnetic brush (23) formed from conductive magnetic particles magnetically bound, and the charging assembly comes into contact with the image bearing member (1) to charge the surface of the image bearing member by directly injecting charges into the electron level present on the surface of the image bearing member and the magnetic toner has a value of σ·D·δ of 150 or less, where the value is obtained by multiplying i) a magnetization quantity σ (Am/kg) in a magnetic field of 1 K oersted as measured by a vibration magnetometer, ii) a weight average particle diameter (D₄) D (µm) of the magnetic toner and iii) a density δ (g/cm³) thereof.
Inventors
- 👤 Yasunori Chigono
- 👤 Harumi Ishiyama
- 👤 Tadashi Furuya
- 👤 Seiji Mashimo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 15:33
CPC Classifications
G; G03; G03G; G03G15/00; B; B82; B82Y; B82Y15/00; G03G15/02; G03G15/0208; G03G15/0241; G03G9/00; G03G9/08; G03G9/0819; G03G9/0821; G03G9/0823; G03G9/093; G03G2215/00; G03G2215/02; G03G2215/021; G03G2215/022
Claims Analysis
Total Claims: 53
Claim 1
Independent Claim
170 words
An image forming method comprising: electrostatically charging an image bearing member by a charging means; forming an electrostatic latent image on the image bearing member thus charged, by a latent image forming means; developing the electrostatic latent image with a magnetic toner to form a toner image; and transferring the toner image to a transfer medium; wherein: said charging means comprises a charging assembly having a magnetic brush formed from conductive magnetic particles magnetically bound; said charging assembly coming into contact with the image bearing member and being capable of electrostatically charging the surface of the image bearing member by directly injecting charges into the surface of the image bearing member; and said magnetic toner has a value of σ·D·δ of 150 or less, the value being obtained by multiplying i) a magnetization quantity σ (Am/kg) in a magnetic field of 1 K oersted as measured by a vibration magnetometer, ii) a weight average particle diameter (D₄) D (µm) of the magnetic toner and iii) a density δ (g/cm³) thereof.
Claim 2
Dependent Claim
27 words
The image forming method according to claim 1, wherein said image bearing member is charged by applying a direct current voltage to said magnetic brush charging assembly.
Claim 3
Dependent Claim
37 words
The image forming method according to claim 1, wherein said image bearing member is charged by applying a voltage produced by superimposing an alternating current voltage on a direct current voltage, to said magnetic brush charging assembly.
Claim 4
Dependent Claim
28 words
The image forming method according to any of claims 1 to 3 wherein said transfer medium to which the toner image is transferred is a final transfer medium.
Claim 5
Dependent Claim
28 words
The image forming method according to any of claims 1 to 3, wherein said transfer medium to which the toner image is transferred is an intermediate transfer medium.
Claim 6
Dependent Claim
26 words
The image forming method according to claim 5, wherein the toner image transferred to said intermediate transfer medium is again transferred to a final transfer medium.
Claim 7
Dependent Claim
65 words
The image forming method according to any of the preceding claims, wherein magnetic toner retained on said image bearing member after the transfer is removed by a cleaning means provided between a transfer zone and a charging zone, and the magnetic toner partly not removed by the cleaning means enters said magnetic brush charging assembly and thereafter is unloaded from the magnetic brush charging assembly.
Claim 8
Dependent Claim
71 words
The image forming method according to any of the preceding claims 1 to 6, wherein magnetic toner retained on said image bearing member after transfer enters said magnetic brush charging assembly and thereafter is unloaded from the magnetic brush charging assembly, and the magnetic toner thus unloaded is simultaneously removed during development by a developing means that develops the electrostatic latent image on the image bearing member with the magnetic toner.
Claim 9
Dependent Claim
190 words
An image forming apparatus comprising: an image bearing member for bearing an electrostatic latent image: a charging means for electrostatically charging the image bearing member; a latent image forming means for forming an electrostatic latent image on the charged image bearing member; a developing means holding a magnetic toner, for rendering the electrostatic latent image visible by development to form a toner image; and a transfer means for transferring the toner image to a transfer medium; wherein: said charging means comprises a charging assembly having a magnetic brush formed of conductive magnetic particles magnetically bound; said charging assembly coming into contact with the image bearing member and being capable of electrostatically charging the surface of the image bearing member by directly injecting charges into the surface of the image bearing member; and said magnetic toner has a value of σ·D·δ of 150 or less, said value being obtained by multiplying i) a magnetization quantity σ (Am/kg) in a magnetic field of 1 K oersted as measured by a vibration magnetometer, ii) a weight average particle diameter (D₄) D (µm) of the magnetic toner and iii) a density δ (g/cm³) thereof.
Claim 10
Dependent Claim
31 words
The image forming apparatus according to claim 9, having a cleaning means, for removing magnetic toner retained on said image bearing member, located between said transfer means and said charging means.
Claim 11
Dependent Claim
66 words
The image forming apparatus according to claim 9, wherein said developing means is adapted not only to develop an electrostatic latent image on the image bearing member using magnetic toner but also to simultaneously remove surplus magnetic toner still retained on the image bearing member after a previous transfer, as also surplus magnetic toner unloaded from the magnetic brush charging assembly onto said image bearing member.
Claim 12
Dependent Claim
178 words
A process cartridge detachably mountable to a main assembly of an image forming apparatus, comprising: an image bearing member for bearing an electrostatic latent image; a charging means for elecrostatically charging the image bearing member; and a developing means holding a magnetic toner, for rendering visible the electrostatic latent image held on the image bearing member, by development to form a toner image; wherein: said charging means comprises a charging assembly having a magnetic brush formed of conductive magnetic particles magnetically bound; said charging assembly coming into contact with the image bearing member and being capable of electrostatically charging the surface of the image bearing member by directly injecting charges into the surface of the image bearing member; and said magnetic toner has a value of σ·D·δ of 150 or less, said value being obtained by multiplying i) a magnetization quantity σ (Am/kg) in a magnetic field of 1 K oersted as measured by a vibration magnetometer, ii) a weight average particle diameter (D₄) D (µm) of the magnetic toner and iii) a density δ (g/cm³ ) thereof.
Claim 13
Dependent Claim
27 words
The process cartridge according to claim 12, having a cleaning means, preceding said charging means, for removing magnetic toner retained on said image bearing member following transfer.
Claim 14
Dependent Claim
65 words
The process cartridge according to claim 12, wherein said developing means is adapted not only to develop an electrostatic latent image on the image bearing member using magnetic toner but also to simultaneously remove surplus magnetic toner still retained on the image bearing member after transfer, as also surplus magnetic toner unloaded from said magnetic brush of said charging assembly onto said image bearing member.
Claim 15
Independent Claim
48 words
The method according to any of claims 1 to 8, the apparatus according to any of claims 9 to 11, or the cartridge according to any of claims 12 to 14, wherein said magnetic toner has a value of σ·D·δ within a range of from 50 to 150.
Claim 16
Dependent Claim
28 words
The method, the apparatus, or the cartridge according to claim 15, wherein said magnetic toner has a value of σ·D·δ within a range of from 100 to 130.
Claim 17
Independent Claim
51 words
The method according to any of claims 1 to 8, 15, 16; the apparatus according to any of claims 9 to 11, 15, 16; or the cartridge according to any of claims 12 to 16, wherein said magnetic toner has a magnetization quantity σ of from 10 Am/kg to 30 Am/kg.
Claim 18
Independent Claim
51 words
The method according to any of claims 1 to 8, 15, 16, the apparatus according to any of claims 9 to 11, 15, 16, or the cartridge according to any of claims 12 to 16, wherein said magnetic toner has a magnetization quantity σ of from 5 Am/kg to 20 Am/kg.
Claim 19
Independent Claim
55 words
The method according to any of claims 1 to 8, 15 to 18, the apparatus according to any of claims 9 to 11, 15 to 18, or the cartridge according to any of claims 12 to 18, wherein said magnetic toner has a weight average particle diameter D of from 2 µm to 20 µm.
Claim 20
Dependent Claim
29 words
The method, the apparatus, or the cartridge according to claim 19, wherein said magnetic toner has a weight average particle diameter D of from 4 µm to 8 µm.
Claim 21
Independent Claim
50 words
The method according to any of claims 1 to 8, 15 to 20, the apparatus according to any of claims 9 to 11, 15 to 20, or the cartridge according to any of claims 12 to 20, wherein said magnetic toner has a density δ of from 1.1 to 2.0.
Claim 22
Dependent Claim
24 words
The method, the apparatus, or the cartridge according to claim 21, wherein said magnetic toner has a density δ of from 1.1 to 1.6.
Claim 23
Independent Claim
51 words
The method according to any of claims 1 to 8, 15 to 22, the apparatus according to any of claims 9 to 11, 15 to 22, or the cartridge according to any of claims 12 to 22, wherein said magnetic toner has a volume resistivity of 10⁹ Ω ·cm or more.
Claim 24
Dependent Claim
25 words
The method, the apparatus, or the cartridge according to claim 23, wherein said magnetic toner has a volume resistivity of 10¹⁰ Ω ·cm or more.
Claim 25
Independent Claim
46 words
The method according to any of claims 1 to 8, 15 to 24, the apparatus according to any of claims 9 to 11, 15 to 24, or the cartridge according to any of claims 12 to 24, wherein said magnetic toner is a spherical magnetic toner.
Claim 26
Dependent Claim
33 words
The method, the apparatus, or the cartridge according to claim 25, wherein said spherical magnetic toner has a shape coefficient SF-1 of from 100 to 150 and SF-2 of from 100 to 130.
Claim 27
Dependent Claim
33 words
The method, the apparatus, or the cartridge according to claim 25, wherein said spherical magnetic toner has a shape coefficient SF-1 of from 100 to 145 and SF-2 of from 100 to 125.
Claim 28
Independent Claim
51 words
The method according to any of claims 1 to 8, 15 to 27, the apparatus according to any of claims 9 to 11, 15 to 27, or the cartridge according to any of claims 12 to 27, wherein said image bearing member comprises an organic photoconductor having a charge injection layer.
Claim 29
Dependent Claim
26 words
The method, the apparatus, or the cartridge according to claim 28, wherein said charge injection layer comprises a resin layer containing conductive fine particles dispersed therein.
Claim 30
Dependent Claim
46 words
The method, the apparatus, or the cartridge according to claim 29, wherein said conductive fine particles are contained in said charge injection layer in an amount of from 20 parts by weight to 100 parts by weight based on 100 parts by weight of the resin.
Claim 31
Independent Claim
35 words
The method, the apparatus, or the cartridge according to either of claims 29 or 30, wherein said conductive fine particles contain at least one member selected from the group consisting of Sn0₂, Ti0₂ and ITO.
Claim 32
Independent Claim
40 words
The method, the apparatus, or the cartridge according to any of claims 29 to 31, wherein said resin layer is formed of at least one member selected from the group consisting of acrylic resin, polycarbonate, polyester, polyethylene terephthalate and polystyrene.
Claim 33
Independent Claim
32 words
The method, the apparatus, or the cartridge according to any of claims 29 to 32, wherein said charge injection layer has a volume resistivity of 1 x 10⁸ Ω ·cm or above.
Claim 34
Independent Claim
54 words
The method according to any of claims 1 to 8, 15 to 33; the apparatus according to any of claims 9 to 11, 15 to 33; or the cartridge according to any of claims 12 to 33, wherein said conductive magnetic particles contain single-component crystals or mixed crystals of a conductive metal or metals.
Claim 35
Independent Claim
53 words
The method according to any of claims 1 to 8, 15 to 34; the apparatus according to any of claims 9 to 11, 15 to 34; or the cartridge according to any of claims 12 to 34, wherein said conductive magnetic particles comprise a particulate conductive magnetic material dispersed in a binder polymer.
Claim 36
Independent Claim
54 words
The method according to any of claims 1 to 8, 15 to 35; the apparatus according to any of claims 9 to 11, 15 to 35; or the cartridge according to any of claims 12 to 35, wherein the surface of said conductive magnetic particles are coated with a resin containing a conductive agent.
Claim 37
Independent Claim
54 words
The method according to any of claims 1 to 8, 15 to 36; the apparatus according to any of claims 9 to 11, 15 to 36; or the cartridge according to any of claims 12 to 36, wherein said conductive magnetic particles have an average particle diameter of from 1 µm to 100 µm.
Claim 38
Dependent Claim
28 words
The method; the apparatus; or the cartridge according to claim 37, wherein said conductive magnetic particles have an average particle diameter of from 5 µm to 50 µm.
Claim 39
Independent Claim
52 words
The method according to any of claims 1 to 8, 15 to 38; the apparatus according to any of claims 9 to 11, 15 to 38; or the cartridge according to any of claims 12 to 38, wherein said conductive magnetic particles have a volume resistivity of 10¹⁰ Ω ·cm or below.
Claim 40
Dependent Claim
28 words
The method; the apparatus; or the cartridge, according to claim 39, wherein said conductive magnetic particles have a volume resistivity of 10⁶ Ω ·cm to 10⁹ Ω ·cm.
Claim 41
Independent Claim
51 words
The method according to any of claims 1 to 8, 15 to 40; the apparatus according to any of claims 9 to 11, 15 to 40; or the cartridge according to any of claims 12 to 40, wherein said conductive magnetic particles have a saturation magnetization of 30 Am/kg or above.
Claim 42
Dependent Claim
27 words
The method; the apparatus; or the cartridge, according to claim 41, wherein said conductive magnetic particles have a saturation magnetization of from 40 Am/kg to 300 Am/kg.
Claim 43
Independent Claim
64 words
The method according to any of claims 1 to 8, 15 to 42; the apparatus according to any of claims 9 to 11, 15 to 42; or the cartridge according to any of claims 12 to 42, wherein said magnetic brush has a magnetised core, an insulative sleeve surrounding said core, and a magnetic strength at the periphery of said sleeve of 400-1500 Gauss.
Claim 44
Dependent Claim
21 words
The method; the apparatus, or the cartridge, according to claim 43 wherein said magnetic core has two magnetic poles or more.
Claim 45
Independent Claim
36 words
The method; the apparatus; or the cartridge according to either of claims 43 and 44 wherein a gap between said insulative sleeve and said image bearing member is in a range of 0.3 - 1.0 mm.
Claim 46
Dependent Claim
31 words
The method according to claim 45 wherein a voltage potential difference of between 5 and 50 V is developed between the surface of said insulative sleeve and said image bearing member.
Claim 47
Dependent Claim
32 words
The apparatus according to claim 45 including means for developing a voltage potential difference of between 5 and 50 V between the surfaces of said insulative sleeve and said image bearing member.
Claim 48
Independent Claim
32 words
The method according to any of claims 1 to 8, 15 to 46 wherein an electrostatic field of strength 50-1600 V/cm is produced between said charging assembly and said image bearing member.
Claim 49
Independent Claim
34 words
The apparatus according to any of claims 9 to 11, 15 to 45, 47 including means for producing an electrostatic field of strength 50-1600 V/cm between said charging assembly and said image bearing member.
Claim 50
Independent Claim
69 words
The method; the apparatus; or the cartridge, according to any of claims 44 to 49, wherein the position of said magnetic pole4s is set to produce a peak magnetic force within an angle of 20°, preferably within 10°, in a rotation direction of said image bearing member, measured from a reference line joining a centre of said magnetic brush and a centre of rotation of said image bearing member.
Claim 51
Dependent Claim
143 words
An image forming method comprising: electrostatically charging an image bearing member by a charging means; forming an electrostatic latent image on the image bearing member thus charged, by a latent image forming means; developing the electrostatic latent image with a magnetic toner to form a toner image; and transferring the toner image to a transfer medium; wherein: said charging means comprises a charging assembly having a magnetic brush formed from conductive magnetic particles magnetically bound; said charging assembly coming into contact with the image bearing member and being capable of electrostatically charging the surface of the image bearing member by directly injecting charges into the surface of the image bearing member; wherein the magnetic toner is chosen such that it shall not accumulate in said magnetic brush and shall not be scattered upon unloading from said magnetic brush onto said image bearing member.
Claim 52
Dependent Claim
163 words
An image forming apparatus comprising: an image bearing member for bearing an electrostatic latent image: a charging means for electrostatically charging the image bearing member; a latent image forming means for forming an electrostatic latent image on the charged image bearing member; a developing means holding a magnetic toner, for rendering the electrostatic latent image visible by development to form a toner image; and a transfer means for transferring the toner image to a transfer medium; wherein: said charging means comprises a charging assembly having a magnetic brush formed of conductive magnetic particles magnetically bound; said charging assembly coming into contact with the image bearing member and being capable of electrostatically charging the surface of the image bearing member by directly injecting charges into the surface of the image bearing member; wherein the magnetic toner is chosen such that it shall not accumulate in said magnetic brush and shall not be scattered upon unloading from said magnetic brush onto said image bearing member.
Claim 53
Dependent Claim
152 words
A process cartridge detachably mountable to a main assembly of an image forming apparatus, comprising: an image bearing member for bearing an electrostatic latent image; a charging means for elecrostatically charging the image bearing member; and a developing means holding a magnetic toner, for rendering visible the electrostatic latent image held on the image bearing member, by development to form a toner image; wherein: said charging means comprises a charging assembly having a magnetic brush formed of conductive magnetic particles magnetically bound; said charging assembly coming into contact with the image bearing member and being capable of electrostatically charging the surface of the image bearing member by directly injecting charges into the surface of the image bearing member; which cartridge, containing magnetic toner, is operable so as not to accumulate magnetic toner in said magnetic brush and to unload magnetic toner from said magnetic brush onto said image bearing member without scattering.
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