Developing Sleeve Magnetic Gap Design for Toner Leakage Control
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Solution Overview
Problem
Existing developing devices in electrophotographic systems face issues with toner particle leakage from the ends of the developing sleeve due to uneven magnetic brush force, leading to scattering and contamination.
Innovation Solution
A developing device with a developing sleeve and magnetic members having an arc-shaped inner surface, where the gap between the magnetic member and the sleeve increases from upstream to downstream, combined with a blade to adjust toner supply, effectively prevents toner particle leakage by maintaining a consistent magnetic force and controlling toner movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic members are provided to form a magnetic brush for preventing toner leakage, then toner particle leakage is prevented, but toner particles scatter around due to reaction force when deviated from the magnetic member
Solution Approach 1:
The magnetic member is designed with different gap distances at different locations: a first gap distance at the upstream end and a second gap distance at the downstream end. This local variation in gap quality allows the magnetic brush to provide appropriate restricting force at each location, preventing toner scattering caused by reaction force while maintaining effective leakage prevention.
Solution Approach 2:
The gap distance between the magnetic member and developing sleeve is changed as a parameter along the rotational direction. By making the gap distance vary (first gap distance upstream, second gap distance downstream), the magnetic restricting force is adjusted to compensate for toner particle deviation and reaction force, preventing both leakage and scattering.
2Stability of the object's composition
If the gap between magnetic member and developing sleeve is constant, then uniform toner restriction is achieved, but toner particles scattered when deviated from downstream end due to reaction force
Solution Approach 1:
Instead of a uniform gap, the magnetic member has different gap distances at different locations along the rotational direction. The upstream end has a first gap distance while the downstream end has a second gap distance, creating local quality variations that address the reaction force issue at the downstream end while maintaining uniform restriction where needed.
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 restricts toner particle leakage from the ends of the developing sleeve, ensuring uniform toner distribution and preventing internal contamination, while maintaining efficient toner supply to the photoconductive drum.
Implementation Method 1
a magnetic member is provided so as to face each of opposite end portions of a peripheral surface of the developing sleeve at a spacing from the peripheral surface of the developing sleeve so that the magnetic members and a magnet included in the developing sleeve form a magnetic brush having magnetic lines of force gathered on the peripheral surface of the developing sleeve
Data Source
AI summary
A developing device includes a developing sleeve for supplying toner particles to a latent image area on a peripheral surface of a photoconductive drum while rotating about an axis. The developing sleeve has a permanent magnet therein. Two magnetic members are provided in the developing device and face opposite ends of a peripheral surface of the developing sleeve at a predetermined distance from the developing sleeve. The magnetic members have arc-shaped inner surfaces. A blade is spaced a predetermined distance from a central portion of the peripheral surface of the developing sleeve. The blade adjusts the amount of toner particles supplied to the photoconductive drum. The gap between the arc-shaped inner surface of the magnetic member and the peripheral surface of the developing sleeve gradually increases from upstream to downstream in a rotational direction of the developing sleeve.