| 摘要 |
PURPOSE:To perform accurate detection and to maintain an adequate capacity of a developer by disposing a detecting element which detects the change in the capacity of the powder developer by detecting electrostatic capacity, etc., by way of a partition wall between the same and the part where the developer exists. CONSTITUTION:The developer is repeatedly circulated by means of a feed screw 4 and a return screw 5. A level detection type automatic concn. regulator ATR is used to detect the capacity of the developer. When the powder developer contg. iron powder as a carrier decreases to a position lower than the height of the ATR element 23, the element 23 detects the change in the electrostatic capacity or magnetic field around the element and operates a hopper to replenish the toner into the developer. Since a magnet 3 exists near the element 23, the magnetic field that gives disturbance must be shut off. Shield plates 6-8 are magnetic shield walls constituted of a magnetic material and the disturbing magnetic field from the magnet 3 is shut off against the element 23 by these plates. In this way, the accurate detection is accomplished, and the adequate capacity of the developer is maintained. |
