Developing Unit Toner Leakage Prevention via Backup Member Support
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Solution Overview
Problem
In electrophotographic image forming apparatuses, toner leakage occurs due to high contact pressure areas between the developing roller and sealing members, leading to toner being scraped and potentially blown out from the developer container during high-speed rotation and long-term use.
Innovation Solution
The implementation of a toner leakage preventing unit with a sealing member and backup members, where the sealing member is fixed to the developer container and contacts the developing roller, and the backup members are positioned next to the sealing members to reduce contact pressure and prevent toner leakage by catching any scraped toner between the developing roller and the sealing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing member is provided to seal the gap between the developer bearing member and the developer container, then developer leakage is prevented, but high contact pressure areas cause toner to be scraped and blown out during high-speed rotation
Solution Approach 1:
The sealing structure is divided into multiple segments: a sealing member for basic sealing and a toner leakage preventing unit with backup members for additional support. This segmentation allows each component to perform its specific function without interfering with the other, solving the contradiction between sealing effectiveness and toner scraping prevention
Solution Approach 2:
The backup members act as intermediary elements between the sealing member and the developer bearing member. They provide additional support and distribute the contact pressure, preventing the sealing member from directly pressing against the developer bearing member with excessive force that would scrape toner
2Stability of the object's composition
If the sealing member is fixed to the developer container and contacts the developer bearing member, then sealing is achieved, but contact pressure increases causing toner to be scraped during rotation
Solution Approach 1:
The backup members are strategically positioned at specific locations where high contact pressure occurs during rotation. This local reinforcement provides support exactly where needed without increasing pressure across the entire sealing interface, maintaining sealing stability while preventing toner scraping in critical areas
3Productivity
If the developer bearing member rotates at high speed, then productivity increases, but centrifugal force causes scraped toner to blow out from the developer container
Solution Approach 1:
The backup members are installed in advance to provide cushioning support before toner scraping can occur. They prevent the sealing member from pressing too hard against the developer bearing member during high-speed rotation, thereby preventing toner scraping at the source and eliminating the risk of toner blowout
Data Source
AI summary
A developing unit includes a developer bearing member, a container, an end seal, a sheet, and a backup member. The container contains a developer. The container has an opening for supplying the developer to the developer bearing member. The end seal is disposed between the developer bearing member and the developer container. The end seal is disposed at an area of the container outside a longitudinal end of the opening. The sheet seals a gap between the developer bearing member and the container. One widthwise end of the sheet is fixed to the container. The other widthwise end is in contact with the developer bearing member. A longitudinal end of the sheet includes a sandwiched portion between the end seal and the developer bearing member. The backup member is provided in an area facing a surface of the sheet opposite to a surface in contact with the developer bearing member.