Developing Roller Magnetic Pole Configuration for Toner Control
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the jumping development scheme for developing electrostatic latent images on photoconductor drums leads to increased toner consumption at edge portions, especially when forming images with numerous edges or fine lines, due to toner adherence and the magnetic brush state, and results in fogging at higher process speeds due to air flow effects.
Innovation Solution
A developing apparatus with a magnetic one-component developer that operates in a cloud state, where toner particles are carried on a developer carrier and adhere to the electrostatic latent image, with a specific magnetic pole arrangement and angle configuration to reduce toner consumption and fogging, by ensuring the toner particles track developing bias effectively and are less affected by air flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If toner particles are in a magnetic brush state on the developing roller, then toner can be effectively supplied to the electrostatic latent image, but toner consumption at edge portions increases significantly
Solution Approach 1:
The patent changes the magnetic field parameters by positioning the magnetic pole downstream in the rotation direction of the developing roller. This parameter change transforms the toner distribution from a magnetic brush state to a cloud state, reducing toner consumption at edge portions while maintaining effective toner supply to the electrostatic latent image.
2Productivity
If the process speed of the image forming apparatus is increased, then productivity improves, but fogging occurs due to air flow effects on cloud-state toner particles
Solution Approach 1:
The patent applies preliminary anti-action by positioning the magnetic pole downstream to create a magnetic field that counteracts the air flow effects at high process speeds. This preliminary configuration prevents cloud-state toner particles from being excessively displaced by air flow, thereby reducing fogging while maintaining high productivity.
3Quantity of substance
If the magnetic constraining force of the magnet within the developing roller is weakened to bring toner to a cloud state, then toner consumption at edge portions is reduced, but fogging increases at higher process speeds
Solution Approach 1:
The patent applies local quality by creating different toner states at different locations on the developing roller. The downstream positioning of the magnetic pole creates a localized magnetic field that maintains cloud state near the development region while providing sufficient magnetic constraining force downstream to prevent fogging at high process speeds.
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 reduces toner consumption at edge portions and minimizes fogging even at higher process speeds by maintaining the toner in a cloud state, enhancing the efficiency and quality of image formation.
Implementation Method 1
a magnetic body having a magnetic pole being provided inside the developer carrier, and the developer carried on the developer carrier being caused to fly between the image carrier and the developer carrier
Data Source
AI summary
With a first line segment being a line segment that joins an axis line of a developer carrier and an axis line of an image carrier, a second line segment being a line segment that joins a position, which is a position on the surface of the developer carrier at which the magnetic flux density of a magnetic pole is maximal, and the axis line of the developer carrier, and a third line segment being a line segment that joins a downstream end portion, in a rotation direction of the developer carrier, then among angles in the rotation direction of the developer carrier, a first angle formed by the first line segment and the second line segment is larger than 0° and equal to or smaller than a second angle formed by the first line segment and the third line segment.