Toner concentration detector for dry powder magnetic brush toning system
US3970036A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 17, 1974 |
| Grant date | Jul 20, 1976 |
| Priority date | — |
| Expiry date | Jul 17, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G15/0853
- 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.