Patent US4374191A successfully refreshed from Google Patents.
US4374191A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dry reversal developer for electrostatic photography and electrostatic photographic method using the same
Assignee: Koki Holdings Co Ltd
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Filing: 1980-05-27
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Granted: 1983-02-15
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Expires: 2000-05-27
Abstract
Abstract An electrostatic photographic method for reversal development using a magnetic brush, with the magnetic brush and photoconductive drum being grounded, and with the development being performed using a dry reversal developer comprising 100 parts by weight of a carrier having ferromagnetic properties and 1 to 10 parts by weight of a toner having a volume specific resistance falling within the range between 3.5x109 and 1x1011 OMEGA -cm.
Inventors
- 👤 Akio Mukoh
- 👤 Hirosada Morishita
- 👤 Masayasu Anzai
- 👤 Kazuyoshi Tokunaga
- 👤 Yasuo Kikuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:39
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/10; G03G9/107; G03G9/1075
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
223 words
A method for recording electrostatic photography comprising the steps of charging a photoconductive drum, exposing said drum to light to form an electrostatic latent image corresponding to an image to be recorded, on said drum; reversal-developing said electrostatic latent image using dry reversal developer, said developer being deposited on said drum from a magnetic brush comprising a sleeve surrounding a magnetic roll; transferring toner deposited on said drum during said reversal-developing step to a record medium and fixing the transferred toner, characterized in that said reversal development is carried out with said sleeve and said photoconductive drum being grounded, whereby said sleeve and said photoconductive drum are non-biased relative to each other, and further characterized in that said dry reversal developer includes 100 parts by weight of individual carrier particles having ferromagnetic properties and 1-10 parts by weight of individual toner particles as essential ingredients and has a volume specific resistance that is sufficiently high such that the proximate counterelectrode effect of the magnetic brush created on the sleeve of the magnetic roll is reduced and a self-biasing voltage is produced substantially only by crests of the magnetic brush comprised of developer, wherein said volume specific resistance of the dry reversal developer is from 3.5×10 9 to 1×10 11 Ω-cm, and wherein the magnetic brush has a resistance of above 4.5×10 7 Ω.
Claim 2
Independent Claim
223 words
A method for recording electrostatic photography comprising the steps of charging a photoconductive drum, exposing said drum to light to form an electrostatic latent image corresponding to an image to be recorded, on said drum; reversal-developing said electrostatic latent image using dry reversal developer, said developer being deposited on said drum from a magnetic brush comprising a sleeve surrounding a magnetic roll; transferring toner deposited on said drum during said reversal-developing step to a record medium and fixing the transferred toner, characterized in that said reversal development is carried out with said sleeve and said photoconductive drum being grounded, whereby said sleeve and said photoconductive drum are non-biased relative to each other, and further characterized in that said dry reversal developer includes 100 parts by weight of individual carrier particles having ferromagnetic properties and 1-10 parts by weight of individual toner particles as essential ingredients and has a volume specific resistance that is sufficiently high such that the proximate counterelectrode effect of the magnetic brush created on the sleeve of the magnetic roll is reduced and a self-biasing voltage is produced substantially only by crests of the magnetic brush comprised of developer, wherein said volume specific resistance of the dry reversal developer is from 3.5×10 9 to 1×10 11 Ω-cm, and wherein the magnetic brush has a resistance of above 4.5×10 7 Ω.
Claim 3
Dependent Claim
42 words
A method for recording electrostatic photography according to claim 1, wherein said carrier has on the surface thereof an oxide coating of the iron particle carrier material to the extent of 0.1-5% by weight as measured by the amount of surface oxygen.
Claim 4
Dependent Claim
27 words
A method for recording electrostatic photography according to claim 1, wherein 80 to 100% of said carrier is flat iron particles having particle size of 30-200 μm.
Claim 5
Dependent Claim
27 words
A method for recording electrostatic photography according to claim 1, wherein 80 to 100% of said carrier is spherical iron particles having particle size of 30-400 μm.
Claim 6
Dependent Claim
27 words
A method for recording electrostatic photography according to claim 3, wherein 3-7 parts by weight of toner is included per 100 parts of flat iron particle carrier.
Claim 7
Dependent Claim
29 words
A method for recording electrostatic photography according to claim 4, wherein 1-5 parts by weight of toner is included per 100 parts by weight of spherical iron particle carrier.
Claim 8
Dependent Claim
47 words
A method for recording electrostatic photography according to claim 1, wherein said volume specific resistance is achieved by having said carrier having ferromagnetic properties coated with an organic insulative material selected from the group consisting of fluorine resin, polystyrene resin, epoxy resin, styrene-methacrylate resin, and synthetic rubber.
Claim 9
Dependent Claim
46 words
A method for recording electrostatic photography according to claim 1, wherein said volume specific resistance is achieved by having powders of a metal selected from the group consisting of Cr, Mo, W, Ni, Co, Mn, Si, Bi, Pb, Zn, Se, and Te admixed with said carrier.
Claim 10
Dependent Claim
20 words
A method for recording electrostatic photography according to claim 1, wherein said sleeve and said photoconductive drum are grounded together.
Claim 11
Dependent Claim
21 words
A method for recording electrostatic photography according to claim 5, wherein the particle size of the toner particles is 1-50 μm.
Claim 12
Dependent Claim
21 words
A method for recording electrostatis photography according to claim 6, wherein the particle size for the toner particles is 1-50 μm.
Claim 13
Dependent Claim
52 words
A method for recording electrostatic photography according to claim 1, wherein said volume specific resistance is achieved by having said carrier particles coated with an oxide of or complex compound of a metal selected from the group consisting of Cr, Mo, W, Ni, Co, Mn, Si, Bi, Pb, Zn, Se and Te.
Claim 14
Dependent Claim
40 words
A method for recording electrostatic photography according to claim 1, 10 or 11, wherein the toner particles include a toner coloring agent and a vinyl resin that has a melting point or melting range beginning at least about 43° C.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-14 | 1986-08-16 | 1987-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-14 | 1990-08-16 | 1991-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-14 | 1994-08-16 | 1995-02-15 | $7700.00 | Window Closed / Lapsed |