US4200388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Toner density sensor for electrostatic copying machine
Assignee: Ricoh Co Ltd
•
Filing: 1977-11-16
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Granted: 1980-04-29
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Expires: 1997-11-16
Abstract
Abstract A toner mixture comprising ferromagnetic carrier particles and non-magnetic toner particles are caused to flow through a conduit for measuring the toner density which is the ratio of toner particles to carrier particles in the mixture. The effective inductance of an electromagnetic coil disposed in the conduit varies in accordance with toner density. The coil is designed so that the magnetic lines of force thereof are substantially confined within the conduit and are not influenced by external bodies.
Inventors
- 👤 Mitsuo Hasebe
- 👤 Mutsuo Watanabe
- 👤 Kunio Hibi
- 👤 Masayosi Watanuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:27
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/0822; G03G15/0848; G03G15/0849; G03G15/0853; Y; Y10; Y10S; Y10S222/00; Y10S222/01
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
112 words
A toner density sensor comprising: a conduit through which a toner mixture of ferromagnetic carrier particles and non-magnetic toner particles is caused to flow; and an electromagnetic coil disposed inside the conduit, said coil being constructed and arranged so that the magnetic lines of force of the coil are substantially confined within the conduit, the effective inductance of the coil varying in accordance with the toner density which is a ratio of toner particles to carrier particles in the toner mixture, said coil comprising two hollow, flattened coil sections which are symmetrically transversely disposed in the conduit, the axes of the coil sections being generally parallel to an axis of the conduit.
Claim 2
Dependent Claim
112 words
A toner density sensor comprising: a conduit through which a toner mixture of ferromagnetic carrier particles and non-magnetic toner particles is caused to flow; and an electromagnetic coil disposed inside the conduit, said coil being constructed and arranged so that the magnetic lines of force of the coil are substantially confined within the conduit, the effective inductance of the coil varying in accordance with the toner density which is a ratio of toner particles to carrier particles in the toner mixture, said coil comprising two hollow, flattened coil sections which are symmetrically transversely disposed in the conduit, the axes of the coil sections being generally parallel to an axis of the conduit.
Claim 3
Dependent Claim
27 words
A sensor as in claim 1, in which the coil sections are elongated along the axis of the conduit and are convexly curved away from each other.
Claim 4
Dependent Claim
37 words
A sensor as in claim 1, in which outer surfaces of the coil sections are flush with inner surfaces of the conduit, the sensor further comprising means for preventing flow of toner mixture between the coil sections.
Claim 5
Dependent Claim
13 words
A sensor as in claim 3 in which said means comprises a spacer.
Claim 6
Dependent Claim
49 words
A sensor as in claim 1, in which the coil sections are arranged so that current flow therethrough causes generation of magnetic lines of force extending in opposite directions respectively which are generally parallel to the axis of the conduit, the magnetic fields combining to form a closed loop.
References Cited (Backward Citations)
US3802381A
Cited
US3896279A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-29 | 1983-10-29 | 1984-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-29 | 1987-10-29 | 1988-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-29 | 1991-10-29 | 1992-04-29 | $7700.00 | Window Closed / Lapsed |