| 摘要 |
PURPOSE:To detect the toner density in a developer with high precision by detecting whether or not the gap between a conductor and an antenna electrode is filled with the developer. CONSTITUTION:The antenna electrode 10 is arranged in a housing 1 at specific distance from a developing sleeve 2 applied with a developing bias voltage from a developing bias power source E, a metallic roller 11 is arranged as the conductor closely to the antenna electrode 10, and the fine gap is formed between the tip of the antenna electrode 10 and the surface of the metallic roller 11. When toner 4 is supplied into the housing from a hopper 3 and the developer in the housing 1 increases in volume, the electrostatic capacity between the developing sleeve 2 and antenna electrode 10 does not vary much, but that between the metallic roller 11 and antenna electrode 10 varies abruptly because the developer is charged between their opposite surfaces, thereby improving the detection precision of the toner density. |
