Writing Instrument Capsule Fastening via Segmented Screws
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Solution Overview
Problem
Existing writing instruments with a capsule to receive a watch movement face issues with inadvertent opening due to the central screw, affecting the reliability and sealing of the assembly, particularly in the field of watchmaking where precision is critical.
Innovation Solution
The writing instrument features at least two screws arranged to be screwed into corresponding foot-screws on the capsule, preventing it from being unscrewed accidentally, with the bottom fixed to the casing via a central screw and angularly distributed screws for balanced mechanical forces, ensuring the capsule remains securely attached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single central screw is used to fix the capsule to the casing, then the device complexity is reduced and ease of manufacture is improved, but the reliability deteriorates due to inadvertent opening of the capsule
Solution Approach 1:
The single central screw fastening system is segmented into multiple screws (at least two, preferably three) distributed around the capsule perimeter. Each screw independently secures the capsule to the casing, eliminating the risk of inadvertent opening while maintaining manufacturing feasibility through standardized fastening components.
Solution Approach 2:
The fastening system transitions from a single central point of attachment to multiple distributed attachment points around the capsule perimeter. This local quality change ensures that the capsule is secured at multiple locations, preventing rotation and inadvertent opening while distributing mechanical stresses evenly.
2Reliability
If multiple screws are used to fix the capsule to the casing, then the reliability is improved by preventing inadvertent opening, but the device complexity increases
Solution Approach 1:
The multiple screws serve multiple functions simultaneously: they secure the capsule to the casing, prevent rotation and inadvertent opening, distribute mechanical stresses, and maintain sealing integrity. This multi-functionality justifies the increased number of components while avoiding unnecessary complexity.
Solution Approach 2:
The fastening system parameters are optimized by using at least two screws (preferably three) positioned at specific angular intervals around the capsule perimeter. This parameter configuration provides sufficient reliability while keeping the overall device complexity manageable through standardized geometric distribution.
3Reliability
If the capsule is securely fixed to prevent rotation, then the reliability is improved, but the ease of operation deteriorates if the crown needs to be accessed
Solution Approach 1:
The capsule is segmented from the casing through the use of multiple discrete screws positioned around the perimeter, allowing the crown to be accessed and operated independently. The segmented fastening system maintains secure attachment while preserving access to operational components like the crown for winding and time adjustment.
Data Source
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AI summary
The invention relates to a writing instrument (1) comprising a casing (2) and a capsule (4) arranged to receive a clock movement (6), said capsule comprising a body (12) defining an internal housing (14) for receiving said clock movement, the body being provided at one of its ends with a base with fastening means (18) for securing the capsule to one end of the casing, the fastening means comprising at least two screws (30) arranged to be screwed from the end of the casing into corresponding screw feet (32) attached to the base of the capsule, so that the capsule is not removable from outside the writing instrument.