| 摘要 |
PURPOSE:To detect the toner density while deciding an error of fault to the change of pressure of the developer and accordingly to increase the reliability of a toner density detector, by providing a detecting coil at the positions near the upper and bottom surfaces respectively of a region where the developer stays within a developing device. CONSTITUTION:The lower and upper part detecting coils 10 and 11 are attached at the high and low pressure regions in the developer 3 which is evenly stirred by a mixing roller 8. A toner supply part 13 is controlled by the toner density detected by both coils 10 and 11. Thus a certain degree of toner density is always compensated. In this case, the value of inductance has a big change although the toner density is constant owing to the change of pressure of the developer. An error or a fault due to the change of pressure is decided by the coils 10 and 11. As a result, the accurate toner density is always detected. |
