US4670368A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic developer for developing latent electrostatic images
Assignee: Ricoh Co Ltd
•
Filing: 1986-01-30
•
Granted: 1987-06-02
•
Expires: 2006-01-30
Abstract
Abstract A developer comprises a mixture of (a) magnetic toner particles comprising a polymeric material and finely-divided magnetic particles, having an electric resistivity of 10 12 Ωcm or more, and (b) electroconductive magnetic particles having an electric resistivity of 10 9 Ωcm or less, a smaller volume mean diameter than that of the magnetic toner particles, with the saturation magnetic moment of the electroconductive magnetic particles being in the range of from 25 emu/g to 75 emu/g, which is larger than the saturation magnetic moment of the magnetic toner particles.
Inventors
- 👤 Hachiro Tosaka
- 👤 Kimitoshi Yamaguchi
- 👤 Motoi Orihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:15
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/083; G03G9/0835; G03G9/0836
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
89 words
A developer comprising a mixture of (a) magnetic toner particles comprising a polymeric material and finely-divided magnetic particles, having an electric resistivity of 10 12 Ωcm or more, and (b) electroconductive magnetic particles having an electric resistivity of 10 9 Ωcm or less, a smaller volume mean diameter than that of said magnetic toner particles, with the saturation magnetic moment of the electroconductive magnetic particles being in the range of from 25 emu/g to 75 emu/g, which is larger than the saturation magnetic moment of said magnetic toner particles.
Claim 2
Dependent Claim
89 words
A developer comprising a mixture of (a) magnetic toner particles comprising a polymeric material and finely-divided magnetic particles, having an electric resistivity of 10 12 Ωcm or more, and (b) electroconductive magnetic particles having an electric resistivity of 10 9 Ωcm or less, a smaller volume mean diameter than that of said magnetic toner particles, with the saturation magnetic moment of the electroconductive magnetic particles being in the range of from 25 emu/g to 75 emu/g, which is larger than the saturation magnetic moment of said magnetic toner particles.
Claim 3
Dependent Claim
35 words
The developer as claimed in claim 1, wherein the volume mean diameter of said electroconductive magnetic particles is in the range of from 1/5 to 4/5 the volume mean diameter of said magnetic toner particles.
Claim 4
Dependent Claim
42 words
The developer as claimed in claim 1, wherein said polymeric material included in said magnetic toner particles is selected from the group consisting of styrene-type resin, acrylic resin, vinyl-type resin, epoxy resin, polyester resin, phenolic resin, polyurethane resin, natural resin and celluloses.
Claim 5
Dependent Claim
42 words
The developer as claimed in claim 1, wherein said finely-divided magnetic particles included in said magnetic toner particles are selected from the group consisting of magnetizable particles of metals, metal oxides and alloys, having a particle size of 1 μm or less.
Claim 6
Dependent Claim
38 words
The developer as claimed in claim 1, wherein said magnetic toner particles further comprising a colorant selected from the group consisting of carbon black, Aniline Black, Crystal Violet, Rhodamine B, Malachite Green, Nigrosin, copper phthalocyanines and azo dyes.
Claim 7
Dependent Claim
51 words
The developer as claimed in claim 1, wherein said magnetic toner particles further comprises a polarity control agent selected from the group consisting of Nigrosin, mono-azo dyes, zinc hexadecyl succinate, alkyl esters of naphthoic acid, alkylamides of nathphtoic acid, nitrohumic acid, N,N'-tetramethyldiamine benzophenone, N, N'-tetrabenzidine, triazine and salicylic acid metal complexes.
Claim 8
Dependent Claim
35 words
The developer as claimed in claim 1, wherein the volume mean diameter of said electroconductive magnetic particles is within the range of from 3/10 to 2/3 the volume mean diameter of said magnetic toner particles.
Claim 9
Dependent Claim
37 words
The developer as claimed in claim 1, wherein the volume resistivity of said electroconductive magnetic particles ranges up to 10 9 Ωcm and the volume resistivity of the magnetic powder particles is at least 10 12 Ωcm.
Claim 10
Dependent Claim
72 words
The developer as claimed in claim 1, wherein the relative amounts of said magnetic toner particles to said electroconductive magnetic particles ranges from a composition of the two particles of 70 parts by weight of the magnetic toner particles with 30 parts by weight of the electroconductive magnetic particles to a composition comprising 85 parts by weight of the magnetic toner particles with 30 parts by weight of the electoconductive magnetic particles.
Claim 11
Dependent Claim
100 words
A developer comprising a mixture of (a) magnetic toner particles comprising a polymeric material and finely-divided magnetic particles which have an electric resistivity of at least 10 12 Ωcm, and (b) electroconductive magnetic particles having an electric resistivity of up to 10 9 Ωcm and a saturation magnetic moment ranging from 25 emu/g to 75 emu/g, which is larger than the saturation magnetic moment of said magnetic toner particles (b), and the volume mean diameter of said electroconductive magnetic particles (b) being within the range of from 1/5 to 4/5 the volume mean diameter of said magnetic toner particles (a).
Claim 12
Dependent Claim
100 words
A developer comprising a mixture of (a) magnetic toner particles comprising a polymeric material and finely-divided magnetic particles which have an electric resistivity of at least 10 12 Ωcm, and (b) electroconductive magnetic particles having an electric resistivity of up to 10 9 Ωcm and a saturation magnetic moment ranging from 25 emu/g to 75 emu/g, which is larger than the saturation magnetic moment of said magnetic toner particles (b), and the volume mean diameter of said electroconductive magnetic particles (b) being within the range of from 1/5 to 4/5 the volume mean diameter of said magnetic toner particles (a).
References Cited (Backward Citations)
JPS5616145A
Cited
EP0053492A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-01 | 1990-12-01 | 1991-06-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-01 | 1994-12-01 | 1995-06-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-01 | 1998-12-01 | 1999-06-02 | $7700.00 | Window Closed / Lapsed |