Developing Device Magnetic Pole Segmentation
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Solution Overview
Problem
The existing hybrid developing device experiences developer movement with rotation of the supplying roller, leading to a low toner ratio and reduced image quality due to the developer being peeled off and scooped back onto the supplying roller, causing toner to be supplied from a developer low in toner ratio.
Innovation Solution
A developing device with a first and second chamber, partitioned by a wall, featuring feeding screws for developer circulation, a developing roller, and a supplying roller with strategically positioned magnetic poles and a guiding portion to manage the developer's movement, ensuring the developer is efficiently conveyed and preventing re-attraction to the supplying roller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the supplying roller is equipped with a magnet for carrying developer, then the developer can be supplied to the developing roller, but the developer may be peeled off and scooped back onto the supplying roller, causing developer movement with rotation
Solution Approach 1:
The magnet is divided into multiple poles (first magnetic pole, second magnetic pole, third magnetic pole, fourth magnetic pole) arranged in specific patterns around the supplying roller. This segmentation allows different regions to perform different functions: some poles attract developer while others repel it, preventing the developer from being scooped back onto the supplying roller and thus eliminating developer movement with rotation.
Solution Approach 2:
Different regions of the supplying roller have different magnetic properties through the multi-pole configuration. The first and second magnetic poles create magnetic fields that attract developer, while the third and fourth magnetic poles create fields that repel developer. This local differentiation of magnetic properties ensures stable developer flow without re-attraction to the supplying roller.
2Productivity
If the developer is peeled off from the supplying roller, then the toner can be supplied to the developing roller, but the developer may stagnate between the supplying roller and the wall member and be scooped again
Solution Approach 1:
The harmful magnetic field effect that causes developer re-attraction is extracted and replaced by introducing specific repelling magnetic poles (third and fourth magnetic poles) that actively prevent developer from being scooped back onto the supplying roller. This removes the root cause of developer loss while maintaining the necessary toner supply function.
3Productivity
If the supplying roller rotates to convey developer, then the developer can be supplied continuously, but the toner ratio in the developer decreases over time, lowering image quality
Solution Approach 1:
The multi-pole magnetic field configuration maintains continuous and stable developer flow onto the developing roller throughout the supplying roller's rotation. By ensuring uniform magnetic field distribution and preventing developer re-attraction at any point in the rotation cycle, the system maintains consistent toner ratio and image quality over extended operation without depletion.
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 effectively suppresses developer movement with rotation of the supplying roller, stabilizes the scooping property, and maintains a consistent toner supply, thereby improving image quality by preventing toner depletion and ensuring a stable developer flow.
Implementation Method 1
a guiding portion configured to guide, to the first chamber, the developer peeled off from the supplying roller by a repelling magnetic field formed by the third magnetic pole and the fourth magnetic pole
Implementation Method 2
a second magnet provided non-rotationally and fixedly inside the supplying roller and including: a second magnetic pole which is provided opposed to the first magnetic pole in a position where the supplying roller opposes the developing roller and which is different in polarity from the first magnetic pole
Data Source
AI summary
A developing device includes first and second chambers, a partition wall, first and second feeding screws, a developing roller, a supplying roller, a first magnet including a first magnetic pole, a second magnet including second to fourth magnetic poles, and a guiding portion. With respect to a supplying roller rotational direction, in a position downstream of the third magnetic pole, a magnetic flux density of the fourth magnetic pole in a normal direction is 20% of a maximum value thereof is a first position positioned downstream of a second position where a line connecting a lowermost end of the guiding portion and a supplying roller center crosses an outer peripheral surface of the supplying roller, and upstream of a third position where a line connecting an uppermost end of the first feeding screw and the supplying roller center crosses the outer peripheral surface of the supplying roller.