Writing Implement with Retractable Ink Core for Variable Line Width
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Solution Overview
Problem
Existing writing implements with ink supply cores housed inside a shaft tube experience ink leakage between the ink supply core and the core surrounding member, leading to unsightly ink rise within the shaft tube and obstruction of ink discharge due to dried ink blocking ventilation holes, affecting the writing function.
Innovation Solution
A writing implement design featuring a retractable ink supply core under writing pressure, with a core surrounding member that includes an elastic portion allowing the ink supply core to retract, and a specific dimension and diameter relationship between the ink supply core and core surrounding member to control line width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ink supply core projects from the core surrounding member to enable ink discharge, then writing function is improved, but ink leaks between the ink supply core and core surrounding member and rises into the shaft tube interior
Solution Approach 1:
The patent introduces an elastic member that surrounds the ink supply core and can elastically deform. This flexible structure maintains close contact with the ink supply core while allowing controlled movement, preventing ink from leaking into the shaft tube interior while still permitting ink discharge at the tip during writing.
Solution Approach 2:
The elastic member is pre-configured to counteract the harmful effect of ink leakage before it occurs. By maintaining constant elastic pressure on the ink supply core, it prevents ink from escaping laterally into the shaft tube, while the design allows controlled ink discharge only at the exposed tip during actual writing.
2Adaptability or versatility
If the ink supply core retracts completely under writing pressure to improve line width variation, then adaptability is improved, but ink may be blocked by the core surrounding member
Solution Approach 1:
The elastic member acts as a flexible guide that moves with the ink supply core during retraction. It maintains sufficient clearance to prevent blocking ink flow while providing lateral support to prevent buckling, enabling smooth retraction for line width variation without compromising ink discharge reliability.
Solution Approach 2:
The system transitions from a static configuration to a dynamic one where the ink supply core can move axially under writing pressure. The elastic member dynamically adjusts its position and shape to accommodate this movement, ensuring continuous ink flow while enabling line width control through core retraction.
3Reliability
If the projection dimension of the ink supply core is increased to improve ink discharge, then writing function is improved, but the gap between the ink supply core and core surrounding member increases causing ink to rise
Solution Approach 1:
The elastic member provides continuous lateral support to the ink supply core, maintaining a consistent minimal gap along its length. This prevents ink from escaping laterally and rising into the shaft tube, while still allowing the tip to project sufficiently for effective ink discharge during writing.
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
Enables the width of the drawn line to be freely adjusted by writing pressure, preventing ink leakage and maintaining effective ink discharge, thus enhancing the writing experience.
Implementation Method 1
an ink supply core that is housed inside the shaft tube and that is capable of guiding ink by capillary action
Implementation Method 2
The elastic portion enables the ink supply core to retract together with the rear end portion. The elastic portion elongates rearward under writing pressure.
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
An object is to provide a writing implement allowing the width of a drawn line to be freely changed by writing pressure that is capable of application to a narrow-shafted felt-tip pen or marker pen. The writing implement (1) includes a shaft tube (10), an ink supply core (20) that is housed inside the shaft tube (10) and that guides ink by capillary action, and a core surrounding member (30) that is fitted to a leading end of the shaft tube (10), that is penetrated by the ink supply core (20), and from which a tip of the ink supply core (20) projects. The ink supply core (20) is configured to retract at a tip of the core surrounding member (30) under writing pressure, and a projection dimension of the ink supply core (20) from the tip of the core surrounding member (30) is from 0.05 mm to 0.7 mm.