| 摘要 |
PURPOSE:To display the remaining amount of a developer outside, to supplement it freely, and to set a detection level electrically and optionally, by detecting a developer level as variation in the inductance of a coil. CONSTITUTION:The developer 5 in a developing device 1 drops in level on every copying operation and this level variation appears in the form of variation of the detection coil 6a of a detection part 6. The output of the constant frequency oscillator 9 of the detection part 6 is amplified 10 and passed through a coupling capacitor, and the terminal voltage across the detection coil 6a is led to an output resistance 15 as a rectified and smoothed DC voltage through a diode 13 and a smoothing circuit 14. The inductance variation of the coil 6a corresponding to the level variation is outputted on an indicator 17 as variation in V0 by varying the resonance state of the capacitor 11. The detected voltage is continuous, so plural LEDs, for example, are equipped and turned on selectively according to the level variation of the developer. |
