Magnetic Flux Density Distribution for Developing Device Stability
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Solution Overview
Problem
Conventional developing devices face instability in developer weight per unit area due to fluctuations in the SB gap caused by component part tolerances and assembly tolerances, leading to unstable developer supply and image quality.
Innovation Solution
A developing device with a cylindrical developing sleeve and a curved developer regulating member, featuring a magnetic flux generating means with a magnetic flux density distribution that includes a first local maximum portion upstream, a second local maximum portion downstream, and a local minimum portion between them, to stabilize the developer weight per unit area even when the SB gap fluctuates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single maximum value magnetic flux density distribution is used in the regulating magnetic pole, then the magnetic flux density concentrates effectively, but the developer weight per unit area becomes unstable when SB gap fluctuates
Solution Approach 1:
The magnetic flux density distribution is divided into multiple local maximum portions (first and second) with a local minimum portion between them. This creates different magnetic flux density zones within the regulating magnetic pole, allowing the system to maintain stable developer weight despite SB gap fluctuations by distributing the magnetic flux concentration across multiple regions rather than relying on a single concentrated point.
2Manufacturing precision
If the SB gap is minimized for precise developer control, then developer weight per unit area is stabilized, but any tolerance in component parts or assembly causes significant M/S fluctuation
Solution Approach 1:
The magnetic flux density distribution is designed with multiple local maximum and minimum portions to preemptively compensate for SB gap fluctuations caused by manufacturing and assembly tolerances. This distribution pattern creates a magnetic field configuration that is inherently more tolerant to gap variations, cushioning against the negative effects of tolerance accumulation before they can significantly impact M/S stability.
3Device complexity
If a simple cylindrical developer regulating member is used, then the device complexity is reduced, but the ability to maintain stable developer supply under gap variation is insufficient
Solution Approach 1:
The regulating magnetic pole's magnetic flux density distribution is modified to include multiple local maximum and minimum portions. This parameter change in the magnetic field configuration allows the simple cylindrical structure to achieve stable developer supply control by creating a more robust magnetic flux pattern that maintains effectiveness despite variations in the SB gap, without adding mechanical complexity to the regulating member itself.
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 stable developer weight per unit area on the developing sleeve, maintaining high image quality despite fluctuations in the SB gap, by distributing magnetic flux in a manner that minimizes changes in developer supply.
Implementation Method 1
a magnetic flux generating means which is provided inside the developing sleeve and which has a plurality of magnetic poles including a regulating magnetic pole provided opposed to the developer regulating member
Implementation Method 2
In the developing region, the developer forms a chain-like magnetic chain by a magnetic flux generated by the magnet roller
Implementation Method 3
toner charged in a developing device is brought near to a photosensitive drum which is an example of an image bearing member and is electrostatically deposited on an electrostatic latent image on the photosensitive drum
Data Source
AI summary
A developing device includes a rotatable developer carrying member, a developer regulating member, and a cylindrical magnetic field generating member provided inside the developer carrying member and including a regulating magnetic pole provided opposed to the developer regulating member. A magnetic flux distribution provided by the regulating magnetic pole includes a first local maximum portion on a side upstream of a closest position between the magnetic field generating member and the developer regulating member, a second local maximum portion on a side downstream of the closest position, and a local minimum portion between the first local maximum portion and the second local maximum portion. A rectilinear line connecting the closest position and a center of the magnetic field generating member is positioned between the first local maximum portion and the second local maximum portion.