| 摘要 |
The method detects a toner concentration in a developer comprising a mixture of magnetic carrier particles and a non-magnetic toner through the determination of a leakage magnetic flux with a Hall element having a high sensitivity. The mixture is first shaped into a predetermined configuration and brought into a fixed magnetic field where the leakage magnetic flux is sensed by the Hall element. The shaped mixture may be a magnetic brush per se in case of the well-known magnetic brush device used. Such a Hall element is very susceptible to a variation of environmental temperature and thus requires a compensation therefor upon the determination of magnetic field. In one aspect of the invention, the compensation may be conveniently achieved by detecting a voltage across the control current terminals of the Hall element and supplying the detected result into an input of analog calculator. |
