Developing Cartridge Seal Retention via Protrusions
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Solution Overview
Problem
Conventional developing devices in electrophotographic image forming apparatuses face toner leakage issues due to wrinkles in double-sided tapes used to affix seals, requiring careful installation to prevent gaps and leakage.
Innovation Solution
A developing cartridge design featuring a frame with a lower seal and upper seal that are restricted from moving in the longitudinal direction by protrusions, eliminating the need for adhesive and ensuring secure mounting without wrinkles, thus preventing toner leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If double-sided tapes are used to affix seals to the case, then the seals can be mounted, but wrinkles may form in the tapes causing gaps and toner leakage
Solution Approach 1:
The patent removes the adhesive function from the sealing system by eliminating double-sided tapes entirely. The seals are instead retained by protrusions that mechanically hold them in place, separating the sealing function from the mounting function and avoiding the wrinkles and gaps caused by adhesive tapes.
Solution Approach 2:
The patent introduces protrusions as an intermediary mechanical retention structure between the case and the seals. These protrusions serve as a mediator that holds the seals in place without requiring adhesive tapes, thereby preventing wrinkles and ensuring reliable toner containment while maintaining ease of assembly.
2Reliability
If great care is used when affixing seals to prevent wrinkles, then toner leakage is reduced, but the mounting process becomes more difficult and time-consuming
Solution Approach 1:
The patent extracts the problematic adhesive mounting process entirely and replaces it with a simple mechanical retention system using protrusions. This eliminates the need for careful alignment and wrinkle prevention during installation, making the process both easier and more reliable.
Solution Approach 2:
The protrusions are designed to automatically retain the seals in the correct position during assembly without requiring external intervention or careful manipulation. The seals simply snap onto or are held by the protrusions, making the installation process foolproof and eliminating the need for operator skill or attention to prevent wrinkles.
3Reliability
If protrusions are used to restrict seal movement, then seal positioning is improved and toner leakage is prevented, but the frame structure becomes more complex
Solution Approach 1:
The patent divides the seal retention function into discrete protrusion elements distributed at strategic locations along the seal length. This segmentation allows the seals to be retained effectively without requiring a complex continuous structure, simplifying the overall design while maintaining positioning stability.
Solution Approach 2:
The protrusions are placed only at specific critical locations where seal positioning is needed, rather than providing continuous support along the entire seal length. This local application of retention features minimizes the added structural complexity while achieving the required seal stability and toner leakage prevention.
Data Source
AI summary
A developing cartridge includes: a frame defining a developer chamber for accommodating developer and being formed with an opening elongated in a longitudinal direction for allowing the developer to flow out of the developer chamber; a member assembled to the frame at a position opposite to the developer chamber with respect to the opening; a seal extending in the longitudinal direction and interposed between the member and the frame; and a protrusion protruding into the seal from at least one of the frame and the member in a protruding direction crossing the longitudinal direction, the protrusion being configured to restrict the seal from moving in the longitudinal direction.