Magnetic Sealing Member Design for Developer Flow Control
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Solution Overview
Problem
Magnetic sealing members in developing devices for electrophotographic image forming apparatuses can cause developer stagnation at the taking-in portion and deterioration due to sliding, leading to issues like 'developer dropping' and 'toner dropping', where the developer or toner is not satisfactorily fed or is liberated, affecting image quality.
Innovation Solution
The developing device incorporates a magnet roller with specific magnetic pole arrangements and grooved sleeve design, along with strategically positioned magnetic seals and plates, to manage developer feeding and sealing, ensuring adequate developer flow and preventing stagnation and deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing property of the magnetic sealing member is enhanced, then the sealing performance is improved, but the developer stagnates at the taking-in portion causing developer dropping
Solution Approach 1:
The magnetic sealing member is designed with different magnetic flux density distributions at different locations. The region corresponding to the taking-in portion has a specific magnetic flux density that prevents stagnation while maintaining sealing, creating local quality variation to resolve the contradiction between sealing and feeding
2Productivity
If the developer feeding power is enhanced, then the developer is fed satisfactorily, but the developer confined by magnetic lines of force is deteriorated by sliding with the developing sleeve causing toner dropping
Solution Approach 1:
The magnetic sealing member creates different magnetic field conditions at different axial positions. The taking-in portion region has optimized magnetic flux density to enable adequate feeding without excessive sliding, while other regions maintain sealing function, thus resolving the contradiction locally
3Reliability
If the magnetic sealing member is positioned with a certain gap to the developing sleeve, then the magnetic sealing function is achieved, but the developer may stagnate or deteriorate depending on the gap size
Solution Approach 1:
The magnetic flux density distribution is optimized as a parameter to resolve the contradiction. By controlling the magnetic flux density at the taking-in portion region to be within a specific range, the system achieves both adequate feeding and prevention of stagnation/deterioration
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 stagnation and deterioration, maintaining a stable developer flow and preventing 'developer dropping' and 'toner dropping', thus ensuring consistent image quality and extending the lifespan of the magnetic sealing members.
Implementation Method 1
The magnetic sealing member closes the gap between the outer peripheral surface of the developing sleeve and the surface thereof by a magnetic brush formed by erection of a chain of the developer formed along each of magnetic lines of force
Implementation Method 2
The magnetic sealing member is constituted using a magnet
Implementation Method 3
a magnet roller (3) serving as a magnetic field generating means and rotatable together with the developing sleeve (2)
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A developing device, a process cartridge and an image forming apparatus which are capable of suppressing inconveniences such as stagnation of a developer at a taking-in portion of the developer and deterioration of the developer due to sliding of the developer with a developer carrying member in the case where a magnetic sealing member is used are provided. A developing device 104 includes, with respect to an axial direction of a developer carrying member 2, a first region 2a including a developing region X and a second region 2b outside the first region 2a, adjacent to the first region 2a, and having lower developer feeding power than in the first region 2a or having substantially no feeding power, at an outer peripheral surface of the developer carrying member 2, and has a constitution in which a boundary 2d between the first region 2a and the second region 2b of the outer peripheral surface of the developer carrying member 2 at end portions of the developer carrying member 2 with respect to the axial direction of the developer carrying member 2 is positioned between a magnetic sealing member 4 and a magnetic member 5 with respect to the axial direction of the developer carrying member 2.