| 摘要 |
PROBLEM TO BE SOLVED: To provide a toner concentration sensor which doe not require adjustments, is inexpensive, has wide dynamic range, is strong with respect to noise, and will not be affected by temperature fluctuations. SOLUTION: Concentration sensor units 7 and 8 include oscillators. The periphery of the coil of the concentration sensor unit 7 is filled with a developer 2. The oscillation frequency of the concentration sensor unit 7 attains the frequency corresponding to the concentration of the toner as the inductance of the coil changes by a change in magnetic permeability, according to the concentration of the toner. The concentration sensor unit 8 is arranged at a place where the influence of the developer is not received, and the oscillation frequency of the concentration sensor unit 8 attains the natural frequency. Accordingly, the toner concentration can be detected, by detecting the frequency ratio of the oscillation frequency of the concentration sensor unit 7 and the oscillation frequency of the concentration sensor unit 8 or the frequency difference thereof. COPYRIGHT: (C)2006,JPO&NCIPI |
