Magnetic Seal for Developing Apparatus Leakage
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Solution Overview
Problem
Conventional developing apparatuses for electrophotographic machines face challenges in preventing toner leakage at the boundary area between the confining and fluid regions due to high rotational speeds and shear plane formation, leading to contamination and developer loss.
Innovation Solution
A developing apparatus with a developing sleeve and a magnet having adjacent magnetic poles of the same polarity, where a magnetic seal is provided with a magnet member only in regions opposing the same polarity poles, and a magnetic end plate is used in repelling regions to minimize toner and developer leakage by reducing shear plane formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an elastic sealing member is mounted to press-contact the developing sleeve to prevent developer leakage, then sealing effectiveness is improved, but the load on the developing sleeve increases and the sealing property deteriorates due to wear
Solution Approach 1:
The patent replaces the mechanical contact-based elastic sealing member with a magnetic sealing member that uses magnetic field forces to prevent developer leakage. The magnetic sealing member is positioned adjacent to the developing sleeve without physical contact, using magnetic attraction to hold the magnetic carrier particles and prevent them from migrating to the end portion of the developing sleeve.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the sealing member and the developer. The magnetic field acts as a non-contact force field that confines the magnetic carrier particles, replacing the need for direct mechanical contact between the sealing member and the developing sleeve.
2Productivity
If the developing sleeve rotates at high speed to meet productivity requirements, then productivity is improved, but toner leakage increases due to shear plane formation at the boundary between confining and fluid regions
Solution Approach 1:
The patent replaces mechanical contact-based sealing with a magnetic field-based sealing system. The magnetic sealing member creates a magnetic field that extends along the circumferential direction of the developing sleeve, forming magnetic chains that prevent toner leakage even at high rotational speeds without creating shear planes that would cause contamination.
Solution Approach 2:
The patent changes the magnetic field distribution parameters by positioning magnetic poles of the same polarity adjacent to each other in the circumferential direction of the developing sleeve. This creates a uniform magnetic field configuration that effectively confines the developer without creating shear planes, allowing high-speed operation without toner leakage.
3Duration of action of stationary object
If a magnetic sealing member is positioned adjacent to the developing sleeve without contact to reduce load, then service life is improved, but developer leakage may occur if the magnetic field is insufficient
Solution Approach 1:
The patent optimizes the magnetic field parameters by configuring magnetic poles of the same polarity adjacent to each other in the circumferential direction of the developing sleeve. This creates a strong and uniform magnetic field that effectively confines the magnetic carrier particles without requiring physical contact, ensuring both long service life and reliable sealing.
Solution Approach 2:
The patent positions the magnetic sealing member and configures its magnetic field in advance to create magnetic chains that prevent developer migration. The magnetic field is pre-established to counteract the centrifugal forces and shear stresses that would otherwise cause developer leakage during high-speed rotation.
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
The solution effectively suppresses toner and developer leakage by maintaining a strong magnetic field and reducing friction between the developing sleeve and the magnetic chains, ensuring high sealing efficiency and extended service life.
Implementation Method 1
a magnetic seal portion, provided in said developing container so as to oppose to said developer carrying member along a circumferential direction at a axial end of said developer carrying member, for contacting the developer confined by a magnetic field formed between said developer carrying member and said magnetic seal portion
Implementation Method 2
the magnetic force lines extend from the end magnet (magnetic sealing member) toward the magnet roller in the developing sleeve, so that the magnetic chains of the developer are formed between the developing sleeve and the end magnet
Implementation Method 3
a magnetic carrier in the developer functions as soft developing electrodes, and therefore, the toner can be deposited in proportion to charge densities of the electrostatic latent image
Implementation Method 4
the surface of the magnetic sealing member is magnetized to magnetically attract the developer
Data Source
AI summary
A developing apparatus includes a developing container for accommodating developer including magnetic particles, a developer carrying member, rotatably provided in the developing container, for carrying the developer to a region where the developer carrying member is opposed to image bearing member, and a magnet stationarily provided in the developer carrying member, having a pair of magnetic poles of the same polarity adjacent to each other in a circumferential direction of the developer carrying member. In addition, a magnet member extends at each of longitudinal end portions of the developer carrying member within a circumferential range opposed to and between a half-peak width zone of one of the magnetic poles and a half-peak width zone of the other one of the magnetic poles. A side of the magnet member opposed to the developer carrying member is magnetized only to a polarity which is the same as the polarity of the pair of magnetic poles.