Developing Device Magnetic Pole Layout for Developer Mixing Control
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Solution Overview
Problem
The existing developing devices with two developing rollers suffer from issues such as density unevenness and stripe-shaped defects in output images due to the mixing of used developer with normal developer, particularly at high operation speeds, caused by the co-rotation and developer clogging phenomena.
Innovation Solution
The developing device is designed with specific magnetic pole arrangements on the first and second rotatable members, ensuring that the acute angle between certain rectilinear lines satisfies α>β, which controls the direction of used developer peeling and delivery to prevent mixing and clogging, using a first chamber with a first feeding screw, a first rotatable member, a first magnet, a second rotatable member with a second magnet, a second chamber, and a second feeding screw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If two developing rollers are arranged side by side with the second roller positioned above the first roller, then the developer can be delivered from the first roller to the second roller, but the used developer remains on the second roller and is conveyed downstream, causing co-rotation phenomenon and density unevenness
Solution Approach 1:
The invention extracts the harmful used developer from the system by introducing a dedicated peeling roller that removes the developer from the second developing roller at a specific position. This prevents the used developer from being conveyed downstream and mixing with fresh developer, thereby eliminating the co-rotation phenomenon and density unevenness while maintaining the dual-roller developer delivery system.
Solution Approach 2:
The peeling roller acts as an intermediary component between the second developing roller and the downstream area. It mediates the developer transfer process by selectively peeling off the used developer, preventing direct contact and mixing between used and fresh developer, thus resolving the density uniformity issue without compromising the developer delivery efficiency.
2Productivity
If the used developer is dropped on the first developing roller, then the developer circulation is maintained, but the used developer enters the developer delivering portion by magnetic force influence, causing co-rotation and stripe-shaped image defects
Solution Approach 1:
The invention extracts the used developer from the circulation path by using the peeling roller to remove it from the second developing roller before it can be conveyed downstream and dropped on the first roller. This prevents the used developer from entering the developer delivering portion and causing stripe-shaped defects, while maintaining proper developer circulation through controlled delivery.
Solution Approach 2:
The invention converts the potentially harmful effect of magnetic force attraction into a beneficial controlled delivery mechanism. By positioning the peeling roller to take advantage of the magnetic field distribution, the used developer is systematically removed and directed to appropriate collection areas, transforming what could be a source of defects into a controlled process that maintains image quality consistency.
3Productivity
If the developing device operates at high speed, then the productivity is improved, but the temperature rise causes increased co-rotation and developer clogging phenomena
Solution Approach 1:
The invention extracts the used developer continuously through the peeling roller mechanism, preventing accumulation and clogging that would be exacerbated by high-speed operation and temperature rise. This ensures consistent developer distribution and prevents stripe-shaped defects even during high-speed image forming.
Solution Approach 2:
The peeling action is performed preliminarily on the second developing roller before the developer can be conveyed downstream and cause problems. By removing the used developer at this early stage in the circulation path, the system prevents subsequent clogging and co-rotation issues that would be more severe at high operating 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
This configuration effectively suppresses image defects like density unevenness and stripe-shaped images by ensuring proper developer circulation and delivery, maintaining consistent toner density and preventing developer mixing, even at high operation speeds.
Implementation Method 1
a first magnet fixedly provided inside the first rotatable member... to which the developer is delivered from the first rotatable member by a magnetic field generated by the first magnet
Implementation Method 2
a second magnet fixedly provided inside the second rotatable member... which is configured to deliver the developer from the second rotatable member
Data Source
AI summary
A developing device includes a first rotatable member having a rotation center Q and a second rotatable member having a rotation center R. When a rectilinear line connecting the rotation center Q and an intersection point X is a rectilinear line L4, a rectilinear line connecting the rotation center Q and a magnetic flux density peak position Y is a rectilinear line L5, a rectilinear line connecting the rotation center Q and a magnetic flux density peak position Z is a rectilinear line L6, an acute angle formed between the rectilinear line L4 and the rectilinear line L5 is α [°], and an acute angle formed between the rectilinear line L4 and the rectilinear line L6 is β [°], α>β is satisfied.