Double-Wall Ferrule Traps Ink Residue in Writing Instruments
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Solution Overview
Problem
Ink transfer from the writing nib to the inner cap surface and subsequently to the gripping surface of the ferrule occurs due to imprecise alignment of the cap and barrel, leading to ink being transferred to the consumer's fingers, which is undesirable and not immediately apparent, especially with permanent inks.
Innovation Solution
A nib assembly with a double-wall ferrule, comprising an inner and outer ferrule wall forming a well, traps ink residue between the two walls, preventing it from reaching the gripping surface and thus the consumer's fingers, by creating a seal between the inner cap wall and the well formed by the ferrule walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a movable inner cap is used to provide a secondary seal between the cap and writing nib, then sealing performance is improved, but manufacturing complexity and costs greatly increase
Solution Approach 1:
The patent removes the movable inner cap and spring mechanism from the design, extracting the problematic components that caused manufacturing complexity. Instead, a simple static ferrule structure is used to achieve the same sealing function through proper positioning and contact between the cap and ferrule surfaces.
2Ease of operation
If the cap and barrel are not precisely aligned, then ease of operation is improved, but ink transfer to the gripping surface occurs
Solution Approach 1:
The patent introduces a ferrule as an intermediary component between the writing nib and the cap. This ferrule acts as a barrier that intercepts any ink that might transfer from the nib to the cap, preventing the harmful ink transfer to the gripping surface while allowing operational flexibility.
Solution Approach 2:
The patent extracts the problematic direct contact path between the nib and cap by introducing the ferrule structure. The ferrule absorbs the misalignment issue and prevents ink from reaching the cap's gripping surface, solving the contradiction between alignment tolerance and ink transfer prevention.
3Object-generated harmful factors
If a double wall ferrule structure is used to prevent ink transfer, then ink transfer prevention is improved, but device complexity increases
Solution Approach 1:
The ferrule is segmented into a outer wall and an inner wall, creating a double-wall structure with a space between them. This segmentation allows the ferrule to trap any ink that contacts the inner surface, preventing it from reaching the gripping surface while maintaining a relatively simple overall structure.
Data Source
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AI summary
A nib assembly for a writing instrument comprises a ferrule having a first end and a second end. The ferrule includes an inner ferrule wall and an outer ferrule wall, the inner ferrule wall and the outer ferrule wall being separated by a well having an opening. A cap has a first end, a second end, and a first cap wall. The first cap wall is sized and shaped to be at least partially received within the well, the first cap wall being disposed at least partially within the well, between the inner ferrule wall and the outer ferrule wall, when the cap is coupled to the ferrule.