US5202731A
Expired / Lapsed
US
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Image forming apparatus having an alternating bias electric field
Assignee: Canon Inc
•
Filing: 1992-08-26
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Granted: 1993-04-13
•
Expires: 2012-08-26
Abstract
Abstract An image forming apparatus is formed by providing a latent image-bearing member for holding an electrostatic image thereon and a toner-carrying member for carrying a prescribed magnetic toner comprising a binder resin and magnetic powder and having a particle size distribution including 12% by number or more of magnetic toner particles of 5 microns or smaller, 33% by number or less of magnetic toner particles of 8-12.7 microns and 2% by volume or less of magnetic toner particles of 16 microns or larger so as to provide a volume-average particle size of 4-10 microns. At the developing station, an alternating bias voltage comprising a DC voltage and an unsymmetrical AC voltage in superposition is applied between the toner-carrying member and the latent image-bearing member to provide an alternating bias electric field comprising a development-side voltage component and a reverse-development side voltage component. The development-side voltage component has a magnitude equal to or larger than that of the reverse development-side voltage component and a duration smaller than that of the reverse-development side voltage component, so that the magnetic toner on the toner-carrying member, particularly fine powdery fraction thereof effective for high-quality development, is effectively transferred to the latent image-bearing member to develop the electrostatic image thereon at the developing station.
Inventors
- 👤 Hirohide Tanikawa
- 👤 Yasutaka Akashi
- 👤 Masaaki Taya
- 👤 Kuniko Kobayashi
- 👤 Masaki Uchiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:04
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G9/0819; G03G13/00; G03G13/06; G03G13/08; G03G13/09; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/0907
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
284 words
An image forming apparatus, comprising: a latent image-bearing member for holding an electrostatic image thereon, a toner-carrying member for carrying a layer of a magnetic toner thereon, a toner vessel for holding the magnetic toner to be supplied to the toner-carrying member, a toner layer-regulating member for regulating the magnetic toner layer on the toner-carrying member, and a bias application means for applying an alternating bias voltage comprising a DC bias voltage and an unsymmetrical AC bias voltage in superposition between the toner-carrying member and the latent image-bearing member, wherein the latent image-bearing member and the toner-carrying member are disposed with a prescribed gap therebetween at a developing station; the toner layer-regulating member is disposed to regulate the magnetic toner layer on the toner-carrying member in a thickness thinner than the prescribed gap; the magnetic toner comprises a binder resin and magnetic powder and has a particle size distribution including 12% by number or more of magnetic toner particles of 5 microns or smaller, 33% by number or less of magnetic toner particles of 8-12.7 microns and 2% by volume or less of magnetic toner particles of 16 microns or larger so as to provide a volume-average particle size of 4-10 microns; and the bias application means is disposed to provide an alternating bias electric field comprising a development-side voltage component and a reverse-development side voltage component, the development-side voltage component having a magnitude equal to or larger than that of the reverse development-side voltage component and a duration smaller than that of the reverse-development side voltage component, so that the magnetic toner on the toner-carrying member is transferred to the latent image-bearing member to develop the electrostatic image thereon at the developing station.
Claim 2
Dependent Claim
284 words
An image forming apparatus, comprising: a latent image-bearing member for holding an electrostatic image thereon, a toner-carrying member for carrying a layer of a magnetic toner thereon, a toner vessel for holding the magnetic toner to be supplied to the toner-carrying member, a toner layer-regulating member for regulating the magnetic toner layer on the toner-carrying member, and a bias application means for applying an alternating bias voltage comprising a DC bias voltage and an unsymmetrical AC bias voltage in superposition between the toner-carrying member and the latent image-bearing member, wherein the latent image-bearing member and the toner-carrying member are disposed with a prescribed gap therebetween at a developing station; the toner layer-regulating member is disposed to regulate the magnetic toner layer on the toner-carrying member in a thickness thinner than the prescribed gap; the magnetic toner comprises a binder resin and magnetic powder and has a particle size distribution including 12% by number or more of magnetic toner particles of 5 microns or smaller, 33% by number or less of magnetic toner particles of 8-12.7 microns and 2% by volume or less of magnetic toner particles of 16 microns or larger so as to provide a volume-average particle size of 4-10 microns; and the bias application means is disposed to provide an alternating bias electric field comprising a development-side voltage component and a reverse-development side voltage component, the development-side voltage component having a magnitude equal to or larger than that of the reverse development-side voltage component and a duration smaller than that of the reverse-development side voltage component, so that the magnetic toner on the toner-carrying member is transferred to the latent image-bearing member to develop the electrostatic image thereon at the developing station.
Claim 3
Dependent Claim
24 words
The image forming apparatus according to claim 1, wherein the bias application means applies an alternating bias voltage having a frequency of 1.0-5.0 KHz.
Claim 4
Dependent Claim
24 words
The image forming apparatus according to claim 1, wherein the bias application means provides an alternating bias voltage having a duty factor of 10-40%.
Claim 5
Dependent Claim
20 words
The image forming apparatus according to claim 1, wherein the alternating bias voltage has a peak-to-peak value of 1.0-2.0 KV.
Claim 6
Dependent Claim
25 words
The image forming apparatus according to claim 1, wherein the magnetic toner contains 12-60% by number of magnetic toner particles of 5 microns or smaller.
Claim 7
Dependent Claim
93 words
The image forming apparatus according to claim 1, wherein the magnetic toner has a volume-average particle size of 6-10 microns, contains 12-60% by number of magnetic toner particles of 5 microns or smaller, and satisfies the condition of N/V=-0.04N+k, wherein N is a number of 12-60 denoting the content in terms of % by number of the toner particles of 5 microns or smaller, V is a number denoting the content in terms of % by volume of the toner particles of 5 microns or smaller, and k is a number of 4.5-6.5.
Claim 8
Dependent Claim
47 words
The image forming apparatus according to claim 1, wherein said alternating bias voltage has a frequency of 1.0-5.0 KHz, a peak-to-peak voltage of 1.0-2.0 KV and a duty factor of 10-40%, and the magnetic toner contains 12-60% by number of toner particles of 5 microns or smaller.
Claim 9
Dependent Claim
93 words
The image forming apparatus according to claim 7, wherein the magnetic toner has a volume-average particle size of 6-10 microns, contains 12-60% by number of magnetic toner particles of 5 microns or smaller, and satisfies the condition of N/V=-0.04N+k, wherein N is a number of 12-60 denoting the content in terms of % by number of the toner particles of 5 microns or smaller, V is a number denoting the content in terms of % by volume of the toner particles of 5 microns or smaller, and k is a number of 4.5-6.5.
Claim 10
Dependent Claim
19 words
The image forming apparatus according to claim 1, wherein the latent image-bearing member comprises a photosensitive layer of a-Si.
Claim 11
Dependent Claim
27 words
The image forming apparatus according to claim 1, wherein the latent image-bearing member comprises a photosensitive layer of a-Si and a surface protective layer of hydrogenated a-SiC.
Claim 12
Dependent Claim
32 words
The image forming apparatus according to claim 1, wherein the latent image-bearing member comprises a photosensitive layer of a-Si and provides a difference between dark-part potential and light-part potential of 250-400 V.
Claim 13
Dependent Claim
25 words
The image forming apparatus according to claim 11, wherein the latent image-bearing member provides a difference between dark-part potential and light-part potential of 250-350 V.
Claim 14
Dependent Claim
22 words
The image forming apparatus according to claim 1, wherein said toner-carrying member has an uneven surface formed by blasting with definite-shaped particles.
Claim 15
Dependent Claim
19 words
The image forming apparatus according to claim 13, wherein the toner-carrying member has a surface roughness of 0.1-5 microns.
Claim 16
Dependent Claim
30 words
The image forming apparatus according to claim 13, wherein the toner-carrying member has an unevenness originated from the definite-shaped particles having a diameter or a long-axis diameter of 20-250 microns.
Claim 17
Dependent Claim
27 words
The image forming apparatus according to claim 1, wherein the toner-carrying member has an uneven surface formed by blasting with indefinite-shaped particles and then with definite-shaped particles.
Claim 18
Dependent Claim
19 words
The image forming apparatus according to claim 16, wherein the toner-carrying member has a surface roughness of 0.1-5 microns.
Claim 19
Dependent Claim
30 words
The image forming apparatus according to claim 16, wherein the toner-carrying member has an unevenness originated from the definite-shaped particles having a diameter or a long-axis diameter of 20-250 microns.
Claim 20
Dependent Claim
28 words
The image forming apparatus according to claim 1, wherein the toner-carrying member has an uneven surface formed by blasting with a mixture of definite-shaped particles and indefinite-shaped particles.
Claim 21
Dependent Claim
19 words
The image forming apparatus according to claim 19, wherein the toner-carrying member has a surface roughness of 0.1-5 microns.
Claim 22
Dependent Claim
30 words
The image forming apparatus according to claim 19, wherein the toner-carrying member has an unevenness originated from the definite-shaped particles having a diameter or a long-axis diameter of 20-250 microns.
Claim 23
Dependent Claim
59 words
The image forming apparatus according to claim 1, wherein the magnetic toner satisfies a condition of the formula: ##EQU4## wherein R is a number satisfying the relation of 4≦R ≦10 and representing the volume-average particle size (μm) of the magnetic toner, and Q represents the absolute value of the triboelectric charge of the magnetic toner on the toner-carrying member.
Claim 24
Dependent Claim
31 words
The image forming apparatus according to claim 22, wherein the magnetic toner satisfies a condition of the formula: ##EQU5## wherein R and Q are the same as in the formula (1).
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-04-12 | 1996-10-12 | 1997-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-12 | 2000-10-12 | 2001-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-12 | 2004-10-12 | 2005-04-13 | $7700.00 | Window Closed / Lapsed |