Writing Tool Joint System for Adjustable Tip Flexing
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Solution Overview
Problem
Existing writing implements with tilting writing tips face limitations in flexing range due to the gap between the shaft body and tip member, leading to wobbling and texture changes, and the elastic body deteriorates from external contact.
Innovation Solution
A writing implement with a joint system comprising a center member, a surrounding member, and an interposing member, where the interposing member is made of a softer material than the center and surrounding members, allowing for flexible writing sensation akin to a fountain pen through two-color molding and integral molding of the joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an elastic body is interposed between the shaft body and tip member to enable tilting of the writing tip, then the writing sensation is improved, but the amount of flexing is limited by the gap between the shaft body and tip member
Solution Approach 1:
The joint is divided into three separate members: a center member, a surrounding member, and an interposing member. This segmentation allows the interposing member to be specifically designed as a flexible elastic body that can tilt the writing tip, while the center and surrounding members provide structural support and define the overall joint geometry. The segmentation enables independent optimization of each component's properties.
Solution Approach 2:
The interposing member acts as an intermediary between the center member and surrounding member. It is specifically designed to be flexible and enable tilting motion of the writing tip relative to the shaft body. This intermediary component resolves the contradiction by providing the necessary flexibility without requiring a large gap between the shaft body and tip member, as the interposing member's elasticity provides the flexing capability within a compact structure.
2Ease of operation
If an elastic body is installed at the outer periphery of the shaft body to enable tilting, then the writing tip can be tilted, but the writer may touch the elastic body and promote deterioration
Solution Approach 1:
The interposing member is nested within the joint structure, positioned between the center member and surrounding member. This nested arrangement protects the elastic interposing member from direct contact with the user's finger, as it is enclosed within the joint assembly rather than exposed on the outer periphery. The surrounding member acts as a protective barrier that prevents user contact with the elastic body while still allowing the tilting function to operate.
3Device complexity
If a single elastic body is used for tilting, then the structure is simple, but wobbling and changes in texture arise with degeneration of the elastic body
Solution Approach 1:
The joint is segmented into three distinct members with different functions: the center member provides a stable core structure, the interposing member provides controlled elasticity for tilting, and the surrounding member provides structural support and constraint. This segmentation allows each component to be optimized for its specific function, reducing the likelihood of wobbling and maintaining writing consistency even as the elastic interposing member undergoes degradation over time.
Solution Approach 2:
Different parts of the joint have different material properties and structural characteristics. The center member and surrounding member can be made of rigid materials for stability, while only the interposing member is made of elastic material for tilting. This local differentiation of material properties ensures that the elastic behavior is confined to where it is needed, preventing unwanted wobbling while maintaining writing consistency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables adjustable flexing of the writing tip according to applied force, reducing wobbling and ensuring a consistent writing experience while minimizing elastic body deterioration.
Implementation Method 1
an interposing member that is formed so as to connect the center member and the surrounding member, and wherein the interposing member is made of a different material from that of the center member and the surrounding member
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
To provide a writing implement with which, during writing, the amount of flexing of the pen tip can be varied, and it is possible to obtain a consistent soft writing sensation. A joint 60 connecting an ink supply section 30 and a ballpoint pen tip 40 together is configured from three members. The three members configuring the joint 60 are a substantially cylindrical center member 61, a substantially cylindrical surrounding member 62 formed at the outer periphery of the center member 61, and an interposing member 63 that is molded by a soft member molded so as to cover the outer periphery of the center member 61 and the surrounding member 62. An annular gap section 64 is provided between the center member 61 and the surrounding member 62. The leading end of the ink supply section 30 is fitted into the gap section 64. The joint 60 is formed by two color molding. The center member 61 and the surrounding member 62 are molded by primary molding, and the interposing member 63 is integrally molded onto the center member 61 and the surrounding member 62 by secondary molding.