Photosensitive Drum Positioning via Asymmetric Force Segmentation
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Solution Overview
Problem
Conventional electrophotographic printers face issues in maintaining the constant position of photosensitive drums relative to the main casing while moving developing rollers into contact and separating them, leading to image formation problems.
Innovation Solution
The image forming apparatus includes a cartridge with a photosensitive drum, a developing roller, and a separating member, where the separating member moves the developing roller between contact and separated positions, exerting a reaction force, and a positioning member with surfaces supporting the drum end portions in different directions to maintain constant positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the separating member presses against the developing roller ends in an obliquely upward and forward direction to separate it from the photosensitive drum, then the developing roller can be separated from the drum, but the photosensitive drum position relative to the main frame becomes unstable due to the opposite force direction of the fixing members
Solution Approach 1:
The patent applies asymmetry by designing the separating member with a pressing surface that is obliquely upward and forward, while the fixing members press in an obliquely downward and rearward direction. This asymmetric force application allows the separating member to effectively separate the developing roller without causing the photosensitive drum to shift position, as the force directions are coordinated to maintain drum stability during separation.
2Stability of the object's composition
If the fixing members press against the protection part and drum shaft in an obliquely downward and rearward direction to fix the photosensitive drum, then the drum is secured in position, but the developing roller cannot be separated without causing image formation problems
Solution Approach 1:
The patent segments the force application system into distinct fixing members and a separating member with different force directions. The fixing members apply force in an obliquely downward and rearward direction to secure the photosensitive drum, while the separating member applies force in an obliquely upward and forward direction to separate the developing roller. This segmentation allows both functions to be performed simultaneously without interference.
3Productivity
If the developing roller is pressed into contact with the photosensitive drum for image formation, then toner can be supplied to the drum, but the drum position may shift when the separating member acts on the developing frame
Solution Approach 1:
The patent introduces the developing frame as an intermediary element between the developing roller and the photosensitive drum. The separating member acts on the developing frame rather than directly on the drum, allowing the developing roller to be separated while the photosensitive drum remains stable. The developing frame serves as a mediator that transmits the separation force without causing drum position shifts.
Data Source
AI summary
An image forming apparatus includes a cartridge and a casing. The cartridge includes a photosensitive drum, a developing roller, a developing frame, and a drum frame. The developing frame is movable between a contact position and a separated position. A separating member provided on the drum frame acts on the developing frame, so that a reaction force is exerted in a reaction force direction. The casing includes a positioning member, an urging member, and a separation pressing member. The positioning member has a first surface and a second surface. The urging member is configured to urge an end portion of the photosensitive drum toward the positioning member in an urging direction. The first surface is configured to support the end portion at a position downstream of the urging direction. The second surface is configured to support the end portion at a portion downstream of the reaction force direction.