Inductance Sensor with Magnet Rib for Toner Density Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inductance sensors with coils printed on circuit boards, lacking an iron core, face challenges in maintaining accurate toner density detection due to fluctuations in developer density within the detection area, leading to inappropriate toner replenishment in image forming apparatuses.
Innovation Solution
The implementation of an inductance sensor configuration with a detection sensitivity that remains effective at positions 1 mm away from the detection area, combined with a conveying screw featuring a spirally formed blade and a rib with a magnet, ensures stable magnetic permeability detection even when the developer density fluctuates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an inductance sensor with a coil whose pattern is printed on a circuit board is used, then the manufacturing cost is reduced, but the detection precision deteriorates due to fluctuation in developer density in the detection area
Solution Approach 1:
A magnet is introduced as an intermediary element that generates a magnetic field to concentrate and stabilize the developer density in the detection area. The magnet acts as a mediator between the inductance sensor and the developer, creating a controlled magnetic field that ensures consistent developer distribution regardless of overall developer amount fluctuations, thereby enabling accurate detection with the simplified printed coil sensor
Solution Approach 2:
The magnetic field parameter is changed by introducing a magnet to alter the developer density distribution in the detection area. By changing the magnetic field strength and distribution, the developer is concentrated in a controlled manner, transforming the detection area into a region with stable developer density that compensates for fluctuations in the total developer amount
2Device complexity
If the developer amount in the developing container decreases, then the device complexity is reduced, but the measurement precision deteriorates due to increased fluctuation in developer density in the detection area
Solution Approach 1:
The magnet serves as a mediator that maintains stable developer density in the detection area even when the total developer amount decreases. By generating a localized magnetic field, the magnet concentrates the available developer in a controlled manner, ensuring that the density in the detection area remains consistent despite reductions in overall developer quantity
Solution Approach 2:
The magnetic field parameter is adjusted to compensate for changes in developer amount. The magnet creates a concentrated magnetic field that redistributes the developer, maintaining stable density parameters in the detection area even when the total developer amount varies, thereby preserving detection precision across different operating conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration stabilizes the detection of magnetic permeability, reducing toner density detection errors and maintaining accurate toner replenishment, even with varying developer amounts, thereby enhancing the reliability of image formation processes.
Implementation Method 1
an inductance sensor which includes a detecting portion which detects magnetic permeability of the developer accommodated in the developing container
Implementation Method 2
The inductance sensor changes its output according to the amount of magnetic material present in the detection area to detect the toner density of the developer
Implementation Method 3
the rib is provided with a magnet... the rib is disposed opposite the detection portion with respect to the conveying direction of the conveying screw
Data Source
AI summary
A developing device includes a developer bearing member, a developing container which accommodates developer, a conveying screw which conveys the developer accommodated in the developing container, and an inductance sensor which includes a detecting portion which detects magnetic permeability of the developer accommodated in the developing container. The conveying screw includes a rotary shaft, a blade which is spirally formed on an outer circumference of the rotary shaft, and a rib formed to protrude outwardly from the outer circumference of the rotary shaft. The rib is disposed opposite the detection portion with respect to a conveying direction of the conveying screw and is provided with a magnet, with magnetic flux density of the magnet being in the range of 20 mT to 60 mT.