Developing Unit Edge Contact Pressure Uniformity
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the developing blade experiences varying contact pressures along its longitudinal direction, leading to inconsistent image formation due to differential elastic forces between the middle and edge portions, resulting in potential defective images.
Innovation Solution
A developing unit and process cartridge design that incorporates an edge portion seal member and an elastic member positioned near the middle portion, ensuring consistent contact pressure across the developing blade's length by assisting the contact pressure at the edge portion relative to the developer bearing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the developing blade is made shorter in the longitudinal direction to reduce cartridge size, then the cartridge becomes more compact, but the contact pressure at the edge portion becomes lower than at the middle portion
Solution Approach 1:
The patent applies local quality by introducing an elastic member specifically at the edge portion of the developing blade, where contact pressure deficiency occurs. This localized reinforcement provides additional contact pressure exactly where it is needed, without affecting the overall blade structure or requiring a longer blade length. The elastic member compensates for the reduced contact pressure at the edge portion while maintaining the compact blade design.
2Area of stationary object
If the developing blade is made longer to ensure sufficient contact area, then image formation coverage is improved, but the cartridge size increases
Solution Approach 1:
Instead of extending the entire developing blade length to ensure sufficient contact area, the patent applies local quality by placing an elastic member specifically at the edge portion where contact pressure is insufficient. This allows the blade to maintain its compact length while the elastic member provides the necessary contact pressure enhancement at the critical edge area, thus achieving adequate image formation coverage without increasing cartridge size.
3Stress or pressure
If the developing blade is made more rigid to maintain constant contact pressure, then contact pressure uniformity is improved, but the blade cannot accommodate deformation in the middle portion
Solution Approach 1:
The patent applies segmentation by dividing the contact pressure support function into two separate components: the developing blade itself (which can deform to accommodate middle portion requirements) and the elastic member (which provides additional contact pressure at the edge portion). This segmentation allows the blade to maintain its deformation flexibility while the elastic member independently compensates for contact pressure uniformity issues at the edge area.
Solution Approach 2:
The elastic member acts as an intermediary element between the developing blade and the developing roller at the edge portion. It mediates the contact pressure interaction by providing an additional elastic force that compensates for the reduced contact pressure at the edge, while allowing the blade itself to maintain its deformation characteristics for accommodating middle portion requirements.
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 reduces differences in contact pressure between the developing blade and the developing roller, preventing defective images by maintaining uniform contact pressure along the longitudinal direction, thereby enhancing image quality.
Implementation Method 1
a developing blade (a regulation member) for regulating a thickness of toner layer on a developing roller that bears toner... a contact pressure between the developing blade and a developing roller... generation of a defective image... reducing differences in contact pressure... assisting a contact pressure of a longitudinal edge portion
Data Source
AI summary
A developing unit includes an elastic member that is disposed nearer a middle portion in a rotational axis direction in relation to an edge portion seal member disposed between a developing roller and a developer container, in an edge portion of a regulation member in a rotational axis direction, and contacts a confronting surface at a side opposite to a contact portion in a developing blade, wherein the developing roller, the developing blade, and the elastic member are arranged so as to make contact with one another in sequence in a normal direction in the contact portion of the developing roller.