Magnet Roller Nonmagnetic Support Rods Axial Flux
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Solution Overview
Problem
Magnet rollers used in electrophotographic image forming apparatuses face challenges in reducing size while maintaining magnetic force, leading to insufficient magnetic force and uneven image density due to edge effects caused by non-uniform magnetic flux density.
Innovation Solution
A magnet roller design featuring a roller-shaped body made of a magnetic field generating material with nonmagnetic support rods that project and bury inside the body, reducing the cross-sectional area of the buried parts to minimize axial differences in magnetic flux density and enhance rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the magnet roller diameter is reduced to make the image forming apparatus compact, then the size of the apparatus is reduced, but the volume of the resin magnet is reduced resulting in insufficient magnetic force
Solution Approach 1:
The magnet roller uses a composite structure combining resin magnet material with embedded permanent magnets. This composite approach allows the roller to maintain compact size while achieving sufficient magnetic force through the synergistic combination of materials with different magnetic properties.
Solution Approach 2:
Permanent magnets are selectively embedded at specific locations within the resin magnet body, particularly at the axial end portions. This local concentration of magnetic material optimizes the magnetic flux density distribution in critical areas without requiring a proportional increase in overall magnet volume.
2Volume of moving object
If the magnet roller diameter is reduced, then the apparatus size is reduced, but axial differences in magnetic flux density increase causing uneven image density
Solution Approach 1:
The resin magnet body is designed with varying properties at different locations, with permanent magnets embedded specifically at axial end portions. This local differentiation compensates for edge effects and ensures uniform magnetic flux density distribution across the axial direction, producing uniform image density.
Solution Approach 2:
The design converts the potentially harmful edge effects at axial ends into a benefit by strategically embedding permanent magnets in these regions. This transforms the area most susceptible to magnetic flux density variations into a zone of enhanced and stabilized magnetic field distribution.
3Strength
If support rods are made larger to increase rigidity, then the durability is improved, but the cross-sectional area available for magnetic material is reduced
Solution Approach 1:
The support rods are designed with a minimized cross-sectional area, using only the necessary amount of nonmagnetic material to provide structural support. This allows maximum volume to be allocated to magnetic materials while maintaining sufficient mechanical strength for the application.
Solution Approach 2:
The support rods are positioned specifically at axial ends where structural support is most needed, with their cross-sectional area optimized locally. This localized support strategy provides sufficient rigidity without unnecessarily reducing the overall magnetic material volume.
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 design alleviates edge effects, maintains sufficient magnetic force, and ensures uniform image density by optimizing the distribution of magnetic flux density along the axial direction, improving the durability and performance of the magnet roller.
Implementation Method 1
a magnet roller for generating magnetic force on a surface of the development sleeve
Data Source
AI summary
A magnet roller includes a roller-shaped body constructed of a magnetic field generating material, a first support rod provided to a first axial end of the body; and a second support rod provided to a second axial end of the body. At least one of the first and second support rods is constructed of a nonmagnetic material and includes a projecting part projecting outside the body from an end face of the body and a buried part united to the projecting part and positioned inside the body. The buried part includes a reduced-area portion smaller than a base end of the projecting part adjacent to the buried part in cross-sectional area perpendicular to an axial direction of the first and second support rods.