US4957840A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Developer and image forming device
Assignee: Canon Inc
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Filing: 1988-10-25
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Granted: 1990-09-18
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Expires: 2008-10-25
Abstract
Abstract A developer for developing electrostatic images, comprising a magnetic toner comprising a binder resin and magnetic powder, the developer containing 17-60% by number of magnetic toner particles of 5 microns or smaller, containing 1-23% by number of magnetic toner particles of 8-12.7 microns, and containing 2.0% by volume or less of magnetic toner particles of 16 microns or larger; wherein the magnetic toner has a volume-average particle size of 4-9 microns, and the magnetic toner particles of 5 microns or smaller have a particle size distribution satisfying the following formula: N/V=-0.04N+k, wherein N denotes % by number of magnetic toner particles of 5 micron or smaller, V denotes % by volume of magnetic toner particles of 5 microns or smaller, k denotes a positive number of 4.5-6.5, and N denotes a positive number of 17-60.
Inventors
- 👤 Kiichiro Sakashita
- 👤 Toshiaki Nakahara
- 👤 Hirohide Tanikawa
- 👤 Naoki Matsushige
- 👤 Satoshi Yoshida
- 👤 Masatsugu Fujiwara
- 👤 Yasuo Mitsuhashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:37
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/0819; Y; Y10; Y10S; Y10S430/00; Y10S430/001; Y10S430/104
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
161 words
A developer for developing electrostatic images, comprising a magnetic toner comprising a binder resin and magnetic powder, said developer containing 17-60% by number of magnetic toner particles having a particle size of 5 microns or smaller, containing 1-23% by number of magnetic toner particles having a particle size of 8-12.7 microns, and containing 2.0% by volume or less of magnetic toner particles having a particle size of 16 microns or larger; wherein the magnetic toner has a volume-average particle size of 4-9 microns, and the magnetic toner particles having a particle size of 5 microns or smaller have a particle size distribution satisfying the following formula: N/V=-0.04N+k, wherein N denotes the percentage by number of magnetic toner particles having a particle size of 5 microns or smaller, V denotes the percentage by volume of magnetic toner particles having a particle size of 5 microns or smaller, k denotes a positive number of 4.5-6.5, and N denotes a positive number of 17-60.
Claim 2
Dependent Claim
161 words
A developer for developing electrostatic images, comprising a magnetic toner comprising a binder resin and magnetic powder, said developer containing 17-60% by number of magnetic toner particles having a particle size of 5 microns or smaller, containing 1-23% by number of magnetic toner particles having a particle size of 8-12.7 microns, and containing 2.0% by volume or less of magnetic toner particles having a particle size of 16 microns or larger; wherein the magnetic toner has a volume-average particle size of 4-9 microns, and the magnetic toner particles having a particle size of 5 microns or smaller have a particle size distribution satisfying the following formula: N/V=-0.04N+k, wherein N denotes the percentage by number of magnetic toner particles having a particle size of 5 microns or smaller, V denotes the percentage by volume of magnetic toner particles having a particle size of 5 microns or smaller, k denotes a positive number of 4.5-6.5, and N denotes a positive number of 17-60.
Claim 3
Dependent Claim
19 words
A developer according to claim 1, wherein the magnetic toner has a true density of 1.45-1.70 g/cm 3 .
Claim 4
Dependent Claim
19 words
A developer according to claim 1, wherein the magnetic toner has a true density of 1.50-1.65 g/cm 3 .
Claim 5
Dependent Claim
27 words
A developer according to claim 1, wherein the magnetic toner contains 25-50% by number of magnetic toner particles having a particle size of 5 microns or smaller.
Claim 6
Dependent Claim
27 words
A developer according to claim 1, wherein the magnetic toner contains 30-50% by number of magnetic toner particles having a particle size of 5 microns or smaller.
Claim 7
Dependent Claim
25 words
A developer according to claim 1, wherein the magnetic toner contains 8-20% by number of magnetic toner particles having a particle size of 8-12.7 microns.
Claim 8
Dependent Claim
39 words
A developer according to claim 1, wherein the magnetic toner particles having a particle size of 5 microns or smaller satisfy the following formula: N/V=-0.04N+k, wherein k denotes a number of 4.5-6.0, and N denotes a number of 25-60.
Claim 9
Dependent Claim
39 words
A developer according to claim 1, wherein the magnetic toner particles having a particle size of 5 microns or smaller satisfy the following formula: N/V=-0.04N+k, wherein k denotes a number of 4.5-5.5, and N denotes a number of 30-50.
Claim 10
Dependent Claim
18 words
A developer according to claim 1, wherein the magnetic toner has a volume-average particle size of 4-8 microns.
Claim 11
Dependent Claim
59 words
A developer according to claim 1, wherein the magnetic toner has a true density of 1.45-1.70 g/cm 3 , magnetic toner particles having a particle size of 8-12.7 microns are contained in an amount of 8-20% by number, and the magnetic powder is contained in an amount of 60-110 wt. parts per 100 wt. parts of a resin component.
Claim 12
Dependent Claim
27 words
A developer according to claim 10, wherein the magnetic powder is contained in an amount of 65-100 wt. parts per 100 wt. parts of the resin component.
Claim 13
Dependent Claim
19 words
A developer according to claim 10, wherein the magnetic toner has a true density of 1.50-1.65 g/cm 3 .
Claim 14
Dependent Claim
37 words
A developer according to claim 1, wherein the magnetic toner has a residual magnetization (σ r ) of 1-5 emu/g, a saturation magnetization (σ s ) of 20-40 emu/g and a coercive force (Hc) of 40-100 Oe.
Claim 15
Dependent Claim
17 words
A developer according to claim 1, wherein the magnetic toner has been mixed with silica fine powder.
Claim 16
Dependent Claim
26 words
A developer according to claim 14, wherein 0.01-8 wt. parts of the silica fine powder has been mixed with 100 wt. parts of the magnetic toner.
Claim 17
Dependent Claim
26 words
A developer according to claim 14, wherein 0.1-5 wt. parts of the silica fine powder has been mixed with 100 wt. parts of the magnetic toner.
Claim 18
Dependent Claim
21 words
A developer according to claim 14, wherein the magnetic toner has positive chargeability and the silica fine powder has positive chargeability.
Claim 19
Dependent Claim
21 words
A developer according to claim 14, wherein the magnetic toner has negative chargeability and the silica fine powder has negative chargeability.
Claim 20
Dependent Claim
19 words
A developer according to claim 1, wherein the magnetic toner has been mixed with powder of a fluorine-containing polymer.
Claim 21
Dependent Claim
30 words
A developer according to claim 19, wherein the powder of the fluorine-containing polymer is contained in an amount of 0.01-2.0 wt. % based on the weight of the magnetic toner.
Claim 22
Dependent Claim
30 words
A developer according to claim 19, wherein the powder of the fluorine-containing polymer is contained in an amount of 0.02-1.0 wt. % based on the weight of the magnetic toner.
Claim 23
Dependent Claim
23 words
A developer according to claim 1, wherein the magnetic toner has been mixed with silica fine powder and powder of a fluorine-containing polymer.
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) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |