Developing Roller Bearing Radial Adjustment for Image Shading
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Solution Overview
Problem
Conventional electrophotographic image forming apparatuses face issues with varying pressing force between the photosensitive drum and the developing roller due to component tolerances, leading to image shading, and existing solutions that optimize this force increase costs by adding additional components.
Innovation Solution
An image forming apparatus with a drum unit, developing unit, developing roller bearing, guide portion, and urging portion, where the developing roller bearing can move radially and rotate axially, and a restriction portion limits its rotation, allowing the developing roller to follow the photosensitive drum's radial displacement without additional components, thus maintaining consistent pressing force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the developing roller is fixed rigidly to the developing unit, then the structure is simple, but the pressing force varies due to component tolerances causing image shading
Solution Approach 1:
The bearing is designed to be movable rather than fixed, allowing radial movement and axial rotation within predetermined ranges. This dynamic capability enables the developing roller to adapt to photosensitive drum displacement and maintain consistent pressing force throughout the rotation cycle, eliminating image shading while using a relatively simple bearing structure.
Solution Approach 2:
The bearing's degree of freedom is controlled by allowing movement within specific predetermined ranges rather than complete freedom or complete constraint. This partial freedom parameter change enables the system to compensate for tolerance variations while maintaining structural simplicity.
2Reliability
If additional components are added to optimize pressing force, then pressing force consistency improves, but device complexity and cost increase
Solution Approach 1:
The movable bearing structure enables the developing roller to self-adjust its position relative to the photosensitive drum, compensating for tolerance variations without requiring additional adjustment mechanisms or components. The system uses its own inherent degrees of freedom to maintain optimal pressing force.
Solution Approach 2:
The single movable bearing structure performs multiple functions: it supports the developing roller, allows radial adjustment for pressure compensation, and permits axial rotation to accommodate drum displacement. This multi-functionality eliminates the need for separate adjustment components.
3Adaptability or versatility
If the bearing can move radially and rotate axially freely, then the developing roller can follow the photosensitive drum, but the pressing force control becomes insufficient
Solution Approach 1:
The bearing is designed with different degrees of freedom in different directions: radial movement is allowed to accommodate drum displacement, while axial rotation is limited to a predetermined range to maintain pressing force control. This localized differentiation of movement freedom achieves both adaptability and control.
Solution Approach 2:
The bearing provides dynamic adjustment capability within controlled limits, allowing the developing roller to follow the photosensitive drum's radial displacement while maintaining sufficient pressing force through controlled axial rotation rather than complete freedom of movement.
Data Source
AI summary
An image forming apparatus includes a drum unit, a developing unit, a developing roller bearing, a guide portion, and an urging portion. The drum unit includes a photosensitive drum. The developing unit includes a developing roller. The developing roller bearing supports the developing roller and can move radially and rotate axially with respect to the developing unit. The guide portion is formed in the drum unit and guides the developing roller bearing in directions toward and away from the photosensitive drum. The urging portion urges the developing unit in such a direction that it presses the developing roller against the photosensitive drum. The developing unit includes a restriction portion that restricts the rotation of the developing roller bearing with respect to the developing unit within a predetermined range.