Developing Sleeve End Toner Leakage Prevention
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Solution Overview
Problem
Conventional developing devices fail to effectively prevent toner particles from leaking from the end portions of the developing sleeve, especially at high-speed image forming processes, due to insufficient magnetic flux coverage.
Innovation Solution
The developing device incorporates a developing sleeve with an immovable sleeve magnet and a pair of arc-shaped magnetic members at the end portions, where the magnetic member magnets face the sleeve magnet with the same polarity, creating repelling magnetic fluxes to prevent toner particles from leaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a half-ring shaped magnet with multiple sets of opposite magnetic poles is used, then the magnetic flux covers the end portions of the developing sleeve, but the toner particles still leak at high rotation speeds due to insufficient magnetic force coverage
Solution Approach 1:
The magnet is divided into multiple sets of magnetic poles (north and south poles arranged alternately) around the developing sleeve. This segmentation creates multiple magnetic flux paths that collectively cover the entire end portion circumference, preventing toner leakage even at high rotation speeds where inertial forces are greater.
Solution Approach 2:
The magnetic flux is configured to extend not only end-to-end between opposite poles but also radially across the air gap between the magnet and the developing sleeve. This multi-dimensional flux distribution ensures comprehensive coverage of the toner particles in the gap region, preventing them from straying to the end portions despite high-speed rotation.
2Productivity
If the developing sleeve rotates at high speed for high-speed image forming, then productivity increases, but toner particles gain greater inertial force and are harder to prevent from leaking
Solution Approach 1:
The magnetic flux is established in advance in the air gap between the magnet and the developing sleeve to create a preparatory magnetic field. This pre-established field exerts magnetic force on toner particles before they can stray to the end portions due to inertial forces during high-speed rotation, effectively preventing leakage.
Solution Approach 2:
The inertial forces that cause toner particles to stray toward end portions at high speeds are countered by utilizing the magnetic flux to create an opposing magnetic force. The magnetic field converts the harmful effect of high-speed rotation into a controlled environment where magnetic forces dominate, preventing toner leakage despite the increased inertial forces.
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 ensures that toner particles are effectively prevented from leaking from the end portions of the developing sleeve, improving the reliability of toner supply and image formation, especially in high-speed operations.
Implementation Method 1
the magnetic member magnets face the sleeve magnet with the same polarity, creating repelling magnetic fluxes to prevent toner particles from leaking
Data Source
AI summary
A developing device (50) includes a developing sleeve (53) for supplying toner particles (T) to a latent image area (22) on a peripheral surface of a photoconductive drum (20) while rotating about a central shaft (534). The developing sleeve (53) has an immovable sleeve magnet (533) therein. Two magnetic members (82) are disposed in opposite end portions of the developing sleeve (53) and are spaced a predetermined distance from the peripheral surface of the developing sleeve. Each magnet member (82) has an arc shape. A magnetic member magnet (83) is mounted in the magnet member (82) and faces a sleeve magnet (533) so that opposite facing portions of the magnetic member magnet (83) and the sleeve magnet (533) have the same polarity. With this construction, toner particles are prevented from leaking from the end portions of the developing sleeve (53).