Patent US4240375A successfully refreshed from Google Patents.
US4240375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for detecting concentration of toner in developing powder
Assignee: Hitachi Ltd
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Filing: 1978-04-11
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Granted: 1980-12-23
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Expires: 1998-04-11
Abstract
Abstract An apparatus for detecting the concentration of toner particles contained in the developing powder is disclosed wherein the developing powder comprising a mixture of magnetic carrier particles and the toner particles is transported while being adsorbed by a magnet roll, and rubbing an electrostatic recording surface lightly to develop an electrostatic latent image. After development, the developing powder is separated from the magnet roll, flows along a guide path, and forms a magnetic path for a flat detecting coil with the flat surfaces thereof placed in the guide path in the same direction as the flow of the developing powder. In response to the magnitude of the inductance of the detecting coil, an electrical circuit produces an electrical signal corresponding to the mixing ratio between the magnetic carrier particles and the toner particles in the developing powder.
Inventors
- 👤 Isamu Terashima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:44
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/0822; G03G15/0848; G03G15/0849; G03G15/0853
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
133 words
An apparatus for detecting the concentration of toner particles in the developing powder, the developing powder comprised of a mixture of magnetic carrier particles and pigmented toner particles, comprising means for containing said developing powder, means for transporting said developing powder in said container means to the surface to be developed, a hollow member, means for separating said developing powder from said transport means and for guiding said developing powder to said hollow member, and a sensor element operated in response to the magnetism of the developing powder flowing in said hollow member, said sensor element being formed flat and disposed in said hollow member in a manner that the flat surfaces of said sensor element are in parallel to the direction of flow of said developing powder moving in said hollow member.
Claim 2
Independent Claim
133 words
An apparatus for detecting the concentration of toner particles in the developing powder, the developing powder comprised of a mixture of magnetic carrier particles and pigmented toner particles, comprising means for containing said developing powder, means for transporting said developing powder in said container means to the surface to be developed, a hollow member, means for separating said developing powder from said transport means and for guiding said developing powder to said hollow member, and a sensor element operated in response to the magnetism of the developing powder flowing in said hollow member, said sensor element being formed flat and disposed in said hollow member in a manner that the flat surfaces of said sensor element are in parallel to the direction of flow of said developing powder moving in said hollow member.
Claim 3
Dependent Claim
43 words
An apparatus for detecting the concentration of toner particles in the developing powder according to claim 1, in which said hollow member is formed by a recess in the side wall of said container and a guide plate closing part of said recess.
Claim 4
Dependent Claim
27 words
An apparatus for detecting the concentration of toner particles in the developing powder according to claim 1, in which said sensor element includes a flat spiral coil.
Claim 5
Dependent Claim
40 words
An apparatus for detecting the concentration of toner particles in the developing powder according to claim 1, in which said sensor element is fixedly mounted by being inserted into said hollow member from a window formed in said hollow member.
Claim 6
Dependent Claim
32 words
An apparatus for detecting the concentration of toner particles in the developing powder according to claim 4, in which said sensor element comprises a flat spiral coil formed as a resin mold.
Claim 7
Dependent Claim
57 words
An apparatus for detecting the concentration of toner particles in the developing powder according to claim 1, wherein said means for transporting said developing powder in said container means to the surface to be developed includes magnet means, and further including magnetic shield means for shielding said hollow member from the magnetic fluxes of said magnet means.
Claim 8
Dependent Claim
100 words
An apparatus for detecting concentration of toner particles in the developing powder according to claim 1, wherein said means for separating said developing powder from said transport means and for guiding said developing powder to said hollow member is adapted to guide said developing powder to the top of said hollow member, whereby said developing powder flows from the top to the bottom of said hollow member, and wherein the bottom of said hollow member has a multiplicity of pores therethrough through which the developing powder flows, whereby the developing powder flows in a laminar flow through said hollow member.
Claim 9
Dependent Claim
47 words
An apparatus for detecting concentration of toner particles in the developing powder according to claim 1 or 2, further including rotatable magnetic roll means, positioned adjacent to location where said developing powder leaves said hollow member, for controlling flow of said developing powder through said hollow member.
Claim 10
Dependent Claim
33 words
An apparatus for detecting concentration of toner particles in the developing powder according to claim 8, wherein said rotatable magnetic roll means is positioned outside of said means for containing said developing powder.
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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) | 1983-12-23 | 1984-06-23 | 1984-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-23 | 1988-06-23 | 1988-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-23 | 1992-06-23 | 1992-12-23 | $7700.00 | Window Closed / Lapsed |