Developing Device Conveying Screw for Stable Toner Density Detection

The patent introduces a magnetic conductor plate as an intermediary component between the inductance sensor and the developer. This plate concentrates and guides the magnetic field from the coil pattern on the circuit board, enabling the sensor to accurately detect toner density despite the absence of an iron core. The magnetic conductor plate acts as a mediator that compensates for the reduced magnetic field concentration capability of the printed coil structure.

The patent applies local quality by creating a non-uniform magnetic field distribution through the magnetic conductor plate. The plate is designed with specific patterns (such as grooves or varying thickness) that concentrate the magnetic field in specific local regions corresponding to the detection area. This ensures that the magnetic field is strongest where developer density needs to be measured, while limiting the overall detection area to avoid excessive sensitivity to developer amount fluctuations.

The patent employs dynamics by making the magnetic field distribution adjustable through the magnetic conductor plate design. The plate can be configured with varying magnetic permeability regions or adjustable positioning that allows optimization of magnetic field concentration for different detection scenarios. This dynamic capability enables the system to achieve high detection sensitivity when needed while maintaining adequate detection range through proper design of the magnetic field distribution pattern.