| 摘要 |
PURPOSE:To detect and control the amount of developer with a simple constitution by providing the developer sensitive element comprising constituting a feedback- oscillating circuit through the use of electric coils, in the specified position of a developer vessel and controlling the establishment or not of oscillation conditions with the level of the developer. CONSTITUTION:A developer level detector 14 integrated with a coil unit 20 and a circuit unit 21 is provided to the bottom plate 2 of a developer vessel. The circuit unit 21 consists of a feedback-oscillating circuit, a rectifier circuit and an amplifying output circuit. If the mix ratio (concentration) of the magnetic carrier and colored toner in the developer is within the specified range, the developer level is high and the magnetic influential power acting upon the detector 14 is large, hence the coupling coefficient between electric coils 20a, 20b is large and the feedback- oscillating circuit oscillates as its oscillation conditions are established. When the colored toner is consumed, the developer level becomes lower than the mounting position of the detector 14 and the coupling coefficient between the coils 20a, 20b becomes small, resulting in the failure of establishment of oscillation conditions. The oscillation then stops. |
