Ball-Shaped Cap Connection for Writing Instruments
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Solution Overview
Problem
Existing writing instruments with protective caps often have bothersome features such as push buttons or external threads that can interfere with the user's hand during writing, and existing connection methods can lead to wear and difficulty in frequent use.
Innovation Solution
A writing instrument with a protective cap that uses ellipsoidal or ball-shaped connecting means spaced apart on the writing part, which engage with an internal thread on the cap, allowing for a smooth, screw-like connection that reduces wear and discomfort, and can be mounted in a rotatable or stationary manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external threads or push buttons are used for cap connection, then the cap can be securely fastened to the writing part, but the user's hand contacts these features during writing causing discomfort
Solution Approach 1:
The invention extracts the connecting means (balls or semi-spheres) from the traditional external thread or push button configuration and relocates them to engage with an internal thread on the cap's inner surface. This removes the problematic external features that contact the user's hand during writing, while preserving the secure fastening function through the internal engagement mechanism.
Solution Approach 2:
Instead of having external threads on the writing part that protrude outward and contact the user's hand, the invention inverts the configuration by placing the internal thread on the cap and having connecting means engage from the inside. This reversal eliminates the harmful external features while maintaining the connection function.
2Ease of operation
If traditional external threads are used for cap connection, then the cap can be screwed on and off, but frequent use leads to wear and difficulty in operation
Solution Approach 1:
The invention employs balls or semi-spheres as connecting means that engage with the internal thread. The spherical geometry allows for smooth rotational movement during cap attachment and detachment, reducing friction and wear compared to traditional external threads. The curved surface of the balls distributes contact stress more evenly across the engagement points.
Solution Approach 2:
The invention changes the geometric parameters of the connection interface by using spherical connecting means with specific radius values (e.g., 0.5-2mm) that optimize both the smoothness of rotation and the durability of engagement. The internal thread geometry is also optimized to work with these spherical elements, creating a more durable connection system.
Data Source
AI summary
A writing instrument having a writing part, having a writing tip, and having a protective cap which protects, the writing tip and is releasably connectable to the writing part. For the releasable connection between the cap and writing part, the writing part has several connecting structures, each with a connecting region which is curved in an ellipsoidal, ball-shaped manner, such as balls or semi-spheres, and the cap has an internal thread on the inside. The internal thread of the cap and the connecting structure of the writing part are positioned and aligned with each other in such a manner that, in each case with the cap in a state fastened on the writing part, the connecting region of the respective connecting structure engages completely or in part in a or the thread of the internal thread.