Compact Developing Apparatus with Magnetic Mono-Component Developer
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Solution Overview
Problem
In electrophotographic printing methods, compact and high-speed image forming apparatuses face challenges in maintaining image density and preventing fogged or uneven images due to the limitations of smaller diameter developing sleeves, which lead to insufficient toner supply and increased risk of toner fusion bonding, especially when the diameter is 12 mm or less.
Innovation Solution
A developing apparatus with a magnetic mono-component developer that employs a magnet roller with specific magnetic pole configurations and a developing bias system to create an alternating electric field, ensuring adequate toner flight and pullback, while maintaining a suitable magnetic binding force to prevent fogging and uneven density, even with smaller developing sleeve diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the developing sleeve is reduced to achieve compactness, then the apparatus size is reduced, but the developing region becomes narrower causing insufficient toner supply and decreased image density
Solution Approach 1:
The patent changes the magnetic field parameters by introducing a magnet roller with specific magnetic pole configurations (multiple poles arranged circumferentially) to enhance magnetic binding force. This allows the developing sleeve diameter to be reduced while maintaining adequate toner supply and image density through optimized magnetic field distribution.
Solution Approach 2:
The magnet roller is divided into multiple magnetic poles arranged around the circumference, creating segmented magnetic fields that provide distributed magnetic binding force. This segmentation allows the magnetic field to be concentrated effectively in the developing region despite the smaller overall diameter of the developing sleeve.
2Object-affected harmful factors
If the magnetic binding force is weakened to prevent toner fusion bonding, then toner can fly more easily, but fogged images and uneven density occur due to insufficient magnetic binding
Solution Approach 1:
The patent applies local quality by creating different magnetic field strengths in different regions. The magnet roller generates strong magnetic binding force in the developing region to prevent toner fusion bonding, while the overall magnetic field distribution is optimized to allow toner flight where needed. This localized magnetic field control prevents both toner fusion and fogged images.
Solution Approach 2:
The patent uses dynamic control of the magnetic field through the rotating magnet roller with multiple poles. The magnetic field strength varies dynamically as the roller rotates, providing strong binding force in the developing region while allowing controlled toner release. This dynamic magnetic field adjustment prevents toner fusion bonding while maintaining image quality uniformity.
3Volume of moving object
If the developing region is narrowed due to smaller diameter, then compactness is achieved, but the range of electric field intensity sufficient for toner flight is limited
Solution Approach 1:
The patent changes the magnetic field parameters by using a magnet roller with multiple circumferentially arranged poles. This configuration creates a concentrated magnetic field in the developing region, allowing the developing sleeve diameter to be reduced while maintaining adequate developing region area through optimized magnetic field distribution rather than relying solely on geometric size.
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 maintains image density and restricts fogged or uneven images, ensuring high-quality output even with smaller developing sleeve diameters by optimizing the magnetic field and electric field interactions, thus enhancing the reproducibility and durability of the image forming process.
Implementation Method 1
a magnet roller with specific magnetic pole configurations and a developing bias system to create an alternating electric field, ensuring adequate toner flight and pullback, while maintaining a suitable magnetic binding force
Implementation Method 2
a developing bias system to create an alternating electric field, ensuring adequate toner flight and pullback
Implementation Method 3
optimizing the magnetic field and electric field interactions, thus enhancing the reproducibility and durability of the image forming process
Data Source
AI summary
A developing apparatus, a process cartridge and an image forming apparatus which form an image whose image density can be maintained, which form a fogged image and which form an image of uneven density within an acceptable range, even when the diameter of a developer carrying member is not more than 12 mm. The apparatus includes a developer carrying member whose outer diameter is in the range of 8 mm to 12 mm, and a magnetic mono-component developer 43 having a saturation magnetization of in a range of 20 Am2/kg to 37 Am2/kg when the magnetic field of 79.6 kA/m (1000 oersteds) is applied, the magnetization of not less than 70% and not more than 80% of the saturation magnetization when the magnetic field is lowered to 55.7 kA/m (700 oersteds), and the magnetization of not less than 50% and not more than 62% of the saturation magnetization when the magnetic field is lowered to 39.8 kA/m (500 oersteds).