Toner concentration detector
US3999687A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 1975 |
| Grant date | Dec 28, 1976 |
| Priority date | — |
| Expiry date | Nov 17, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S222/01
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A toner concentration detecting and toner replenishing system for use in an electrostatic copier having a magnetic brush which carries dry developer comprising a mixture of ferromagnetic carrier particles and toner particles into contact with the surface of a photoconductor upon which a latent electrostatic image has been formed, in which system a quantity of developer is removed from the magnetic brush after development of the image and the brush leaves the surface. The removed developer is directed into a dielectric tube having a restricted outlet which inhibits unstable flow through the tube so that developer in the tube determines the inductance of a coil surrounding the tube. The coil is one element of the tuned circuit of a sensing oscillator, the output frequency of which is compared with that of a tunable reference oscillator to provide a frequency difference signal which is a measure of the relative proportion of toner to carrier in the developer. This frequency difference signal is employed to actuate a toner replenishing system to feed toner from the supply to the developer supply as required to maintain the toner concentration substantially constant.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.