Patent US4254204A successfully refreshed from Google Patents.
US4254204A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic brush electrographic developing method
Assignee: Minolta Co Ltd
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Filing: 1979-01-24
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Granted: 1981-03-03
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Expires: 1999-01-24
Abstract
Abstract An electrographic developing method for developing a latent electrostatic image on a support to a toner image by brushing the image bearing surface of the support with a magnetic brush comprising a magnetic toner which comprises core particles having a low resistivity and containing a resin and a finely divided magnetic material, and secondary particles thermally adhered to part of the outer surface of each core particle and said secondary particles consisting predominantly of an insulating resin.
Inventors
- 👤 Hitoshi Kato
- 👤 Koji Nagai
- 👤 Hiromi Kameda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:49
CPC Classifications
G; G03; G03G; G03G13/00; G03G13/06; G03G13/08; G03G13/09; Y; Y10; Y10S; Y10S430/00; Y10S430/001; Y10S430/104
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
217 words
A magnetic brush electrophotographic developing method for developing an electrostatic latent image which comprises: frictionally contacting a magnetic toner which comprises core particles having a low resistivity and containing a resin and a finely divided magnetic material, and secondary particles thermally adhered to a part of the outer surface of each core particle and consisting predominantly of an insulating resin: said secondary particles being triboelectrically charged to a polarity opposite the polarity of the core particles and the latent image when said secondary particles are brought into frictional contact with said core particles, the part of the outer surface of said core particles exposed through the secondary particles being sufficient to permit said core particles to substantially contact each other under the influence of a magnetic field, thereby forming a magnetic brush, said part of said outer surface of said core particles exposed through said secondary particles also being sufficient to permit the core particles to triboelectrically contact the secondary particles which are thermally adhered to the other core particles, said core particles having a low resistivity so as to rapidly dissipate triboelectrical charges; said secondary particles having a high resistivity so as to retain the triboelectrical charges and developing a latent electrostatic image bearing surface on a support by contacting said surface with said magnetic brush.
Claim 2
Dependent Claim
217 words
A magnetic brush electrophotographic developing method for developing an electrostatic latent image which comprises: frictionally contacting a magnetic toner which comprises core particles having a low resistivity and containing a resin and a finely divided magnetic material, and secondary particles thermally adhered to a part of the outer surface of each core particle and consisting predominantly of an insulating resin: said secondary particles being triboelectrically charged to a polarity opposite the polarity of the core particles and the latent image when said secondary particles are brought into frictional contact with said core particles, the part of the outer surface of said core particles exposed through the secondary particles being sufficient to permit said core particles to substantially contact each other under the influence of a magnetic field, thereby forming a magnetic brush, said part of said outer surface of said core particles exposed through said secondary particles also being sufficient to permit the core particles to triboelectrically contact the secondary particles which are thermally adhered to the other core particles, said core particles having a low resistivity so as to rapidly dissipate triboelectrical charges; said secondary particles having a high resistivity so as to retain the triboelectrical charges and developing a latent electrostatic image bearing surface on a support by contacting said surface with said magnetic brush.
Claim 3
Dependent Claim
27 words
An electrophotographic developing method according to claim 1, wherein the insulating resin of the secondary particles differs from the resin of the core particles in melting point.
Claim 4
Dependent Claim
27 words
The electrophotographic developing method according to claim 1 wherein the melting point of the resin of the secondary particles is higher than that of the core particles.
Claim 5
Dependent Claim
21 words
The electrophotographic developing method according to claim 1 wherein the resisitivity of the core particles is lower than 10 12 ohm-cm.
Claim 6
Dependent Claim
21 words
The electrophotographic developing method according to claim 1 wherein the resisitivity of the core particles is lower than 10 10 ohm-cm.
Claim 7
Dependent Claim
25 words
The electrophotographic developing method as claimed in claim 1 wherein the size of the secondary particles does not exceed the size of the core particles.
Claim 8
Dependent Claim
33 words
The electrophotographic developing method according to claim 1 wherein the particle size of the core particles is 10 to 25 μm and that of the secondary particles is 10 to b 25 μm.
Claim 9
Dependent Claim
28 words
The electrophotographic developing method according to claim 1 wherein the particle size of the core particles is 10-25 μm and that of the secondary particles is 3-10 μm.
Claim 10
Dependent Claim
86 words
The method according to claim 1 wherein the resin for said core particles is an epoxy resin having a melting point of 82° C., the finely divided magnetic material is iron oxide and said core particles are 10-25 μm in size and have a volume resistivity of 10 10 ohm-cm, said secondary particles being formed of a styrene resin having a melting point of 125° C. and having a particle size of 3-10 μm, the ratio of said core particles to said secondary particles being 2:1.
Claim 11
Dependent Claim
169 words
A magnetic brush electrophotographic developing method for developing a latent electrostatic image which comprises: frictionally contacting a magnetic toner which comprises core particles having low resistivity and containing a resin and a finely divided magnetic material, and secondary particles thermally adhered to a portion of the outer surface of each core particle and consisting predominantly of an insulating resin; said secondary particles being triboelectrically charged to a polarity opposite the polarity of the core particles and the latent image when said secondary particles are brought into frictional contact with said core particles, the degree of coverage by said secondary particles of the surface of said core particles being in the range of 10-50%: said core particles having a low resistivity so as to dissipate the triboelectrical charges; said secondary particles having a high resistivity so as to retain the triboelectrical charges, and then forming a magnetic brush comprising said magnetic toner and developing a latent image bearing surface on a support by contacting said surface with said magnetic brush.
Claim 12
Dependent Claim
169 words
A magnetic brush electrophotographic developing method for developing a latent electrostatic image which comprises: frictionally contacting a magnetic toner which comprises core particles having low resistivity and containing a resin and a finely divided magnetic material, and secondary particles thermally adhered to a portion of the outer surface of each core particle and consisting predominantly of an insulating resin; said secondary particles being triboelectrically charged to a polarity opposite the polarity of the core particles and the latent image when said secondary particles are brought into frictional contact with said core particles, the degree of coverage by said secondary particles of the surface of said core particles being in the range of 10-50%: said core particles having a low resistivity so as to dissipate the triboelectrical charges; said secondary particles having a high resistivity so as to retain the triboelectrical charges, and then forming a magnetic brush comprising said magnetic toner and developing a latent image bearing surface on a support by contacting said surface with said magnetic brush.
Claim 13
Dependent Claim
27 words
An electrophotographic developing method according to claim 10 wherein the insulating resin of the secondary particles differs from the resin of the core particles in melting point.
Claim 14
Dependent Claim
27 words
The electrophotographic developing method according to claim 11 wherein the melting point of the resin of the secondary particles is higher than that of the core particles.
Claim 15
Dependent Claim
21 words
The electrophotographic developing method according to claim 10 wherein the resistivity of the core particles is lower than 10 12 ohm-cm.
Claim 16
Dependent Claim
21 words
The electrophotographic developing method according to claim 10 wherein the resistivity of the core particles is lower than 10 10 ohm-cm.
Claim 17
Dependent Claim
25 words
The electrophotographic developing method as claimed in claim 10 wherein the size of the secondary particles does not exceed the size of the core particles.
Claim 18
Dependent Claim
32 words
The electrophotographic developing method according to claim 15 wherein the particle size of the core particles is 10 to 25 μm and that of the secondary particles is 10 to 25 μm.
Claim 19
Dependent Claim
28 words
The electrophotographic developing method according to claim 16 wherein the particle size of the core particles is 10-25 μm and that of the secondary particles is 3-10 μm.
Claim 20
Dependent Claim
86 words
The method according to claim 10 wherein the resin for said core particles is an epoxy resin having a melting point of 82° C., the finely divided magnetic material is iron oxide and said core particles are 10-25 μm in size and have a volume resistivity of 10 10 ohm-cm, said secondary particles being formed of a styrene resin having a melting point of 125° C. and having a particle size of 3-10 μm, the ratio of said core particles to said secondary particles being 2:1.
References Cited (Backward Citations)
US3345294A
Cited
US3645770A
Cited
US4082681A
Cited
US4137188A
Cited
US4108786A
Cited
US4155883A
Cited
US4111823A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-03-02 | 1984-09-01 | 1985-03-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-02 | 1988-09-01 | 1989-03-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-02 | 1992-09-01 | 1993-03-03 | $7700.00 | Window Closed / Lapsed |