Apparatus for sensing toner density using a stationary ferromagnetic mass within the toner to increase sensitivity
US4210864A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 1978 |
| Grant date | Jul 1, 1980 |
| Priority date | — |
| Expiry date | Apr 18, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S222/01
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A powdered toner mixture comprising a non-magnetic toner component and a ferromagnetic carrier component is caused to flow downwardly through a vertical conduit by gravity. An electromagnetic coil is wound around the conduit and energized with an alternating electric signal. An electrically conductive and magnetic mass is disposed inside the conduit. The permeability of the toner mixture decreases as the toner density, or the ratio of the toner component to the carrier component, increases. The lower the permeability of the toner mixture, the greater the proportion of magnetic flux passing through the mass. The flux passing through the mass induces eddy currents therein which, in combination with hysterisis and skin effect losses, dissipate a portion of the electric signal. The amount of power dissipation is a function of the relative proportion of flux through the mass and thereby the toner density and, when measured, provides a measure of the toner density.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.