Patent EP0423369A1 successfully refreshed from Google Patents.
US4342283A
Expired / Lapsed
US
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Developing apparatus for electrostatic duplicator
Assignee: Hitachi Ltd
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Filing: 1980-11-21
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Granted: 1982-08-03
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Expires: 2000-11-21
Abstract
Abstract A developing apparatus is provided in which the toner concentration of a developing agent for electrostatic duplicator is detected with high precision by positively magnetizing the developing agent present in the detection region in a toner concentration detecting container. The developing agent within the detecting container is magnetized within a range of a magnetic flux density under which the permeability is not so changed with the change of magnetic field, even if a change of the magnetic flux of a magnetic roll or the like is produced.
Inventors
- 👤 Isamu Terashima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:34
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/0822; G03G15/0848; G03G15/0849; G03G15/0853
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
135 words
A developing apparatus for electrostatic duplicator comprising: a developing agent including a magnetic carrier and a nonmagnetic toner; a container in which said developing agent is placed; means for transporting the developing agent in said container to an electrostatic latent image surface of a recording medium; means for passing part of said developing agent into a detecting container; means for detecting permeability of the developing agent passing in the detecting container; and means for magnetizing the developing agent within a detection region in said detecting container in the direction of flow of the developing agent and within the range of a magnetic flux density such that the permeability of the developing agent is little changed with a change in the magnetic field whereby the developing agent is allowed to pass readily through the detection region.
Claim 2
Dependent Claim
135 words
A developing apparatus for electrostatic duplicator comprising: a developing agent including a magnetic carrier and a nonmagnetic toner; a container in which said developing agent is placed; means for transporting the developing agent in said container to an electrostatic latent image surface of a recording medium; means for passing part of said developing agent into a detecting container; means for detecting permeability of the developing agent passing in the detecting container; and means for magnetizing the developing agent within a detection region in said detecting container in the direction of flow of the developing agent and within the range of a magnetic flux density such that the permeability of the developing agent is little changed with a change in the magnetic field whereby the developing agent is allowed to pass readily through the detection region.
Claim 3
Dependent Claim
25 words
A developing apparatus for electrostatic duplicator according to claim 1, wherein said magnetizing means includes permanent magnets placed at the outside of the detecting container.
Claim 4
Dependent Claim
25 words
A developing apparatus for electrostatic duplicator according to claim 1, wherein said magnetic flux density is in the range from about 50 to 200 gauss.
Claim 5
Dependent Claim
28 words
A developing apparatus for electrostatic duplicator according to claim 1, wherein said magnetizing means includes an electromagnetic coil provided on the outer peripheral surface of said detecting container.
Claim 6
Dependent Claim
29 words
A developing apparatus for electrostatic duplicator according to claim 2, wherein said transporting means includes a magnetic roll having a transporting magnetic pole and a magnetizing magnetic pole magnetized.
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) | 1985-08-02 | 1986-02-01 | 1986-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-02 | 1990-02-01 | 1990-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-02 | 1994-02-01 | 1994-08-03 | $7700.00 | Window Closed / Lapsed |