Bracelet Clasp With Elastic Stud Locking to Prevent Hole Deformation

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Solution Overview

Problem

Existing watch strap clasps either deform the holes in the bracelet or use screws that can break or wear out, leading to potential loss and requiring replacement.

Innovation Solution

A clasp design that adjusts the bracelet length without damaging the holes and uses a stud mechanism with elastic interlocking, eliminating the need for screws and ensuring secure attachment without tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a stud with ridge is forced into a hole in the bracelet to prevent unintentional dislodgement, then the attachment security is improved, but the hole is deformed and enlarged to the point where the bracelet could be lost

Engineering Contradiction:
Improveattachment securityVSAvoidhole deformation
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Instead of forcing the stud into the hole from the outside, the invention inverts the approach by having the stud engage with the hole from the inside through elastic interlocking. The elastic arms flex outward to allow the stud to pass through and then return to their original position, capturing the stud without deforming the hole.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The invention changes the physical state of the attachment mechanism by using elastic deformation of the arms. The arms flex from a rigid state to an elastic state during engagement, allowing the stud to pass through without permanent deformation of the hole, then return to their original rigid state to secure the attachment.

Inventive Principle:
Principle #35Parameter changes

2Object-affected harmful factors

If a screw is used for attachment instead of a stud, then the need for forcing into holes is eliminated, but the screw can break and/or get lost, and the threads can wear down over time

Engineering Contradiction:
Improvehole deformationVSAvoidattachment durability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The invention extracts the problematic threaded portion from the attachment mechanism, eliminating the screw entirely. Instead of using a screw that can break, lose threads, or require threading operations, the design uses a simple stud with elastic interlocking that has no threads and cannot suffer from thread wear or stripping.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the complex, potentially failure-prone screw mechanism with a simpler, more robust stud design. While the stud itself is simple, the elastic interlocking mechanism provides durability without the complexity and failure modes of threaded connections.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If traditional attachment mechanisms are used, then secure attachment is achieved, but tools are required for disassembly or adjustment

Engineering Contradiction:
Improveattachment securityVSAvoidtool-free operation
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The elastic interlocking mechanism is designed to be self-operating. The user can simply press the release button to disengage the stud from the elastic arms, or adjust by moving the stud between holes, without requiring any external tools. The elastic arms automatically engage and disengage the stud through their flexibility.

Inventive Principle:
Principle #25Self-service

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 clasp allows adjustable length without deforming the bracelet holes and prevents parts from detaching due to wear, providing a secure, tool-free, and durable attachment.

Implementation Method 1

The arms 14 of the support 4 deform elastically to allow the pin 2 to pass through when the fastening system is locked. Alternatively, both the pin 2 and the arm 14 could have elastic properties.

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3679824B1Clasp for bracelet
Publication Date: 2025.11.12 PATEK PHILIPPE SA
  • EP3679824B1 patent drawingFigure 1~2
  • EP3679824B1 patent drawingFigure 3~4
  • EP3679824B1 patent drawingFigure 5~6

AI summary

The invention relates to a clasp (100) for a bracelet comprising at least one cover (1) and a support (4), movable relative to each other, a first of said cover (1) and support (4) having a stud (2), said stud (2) being intended to pass through a hole selected from a series of holes in a first strand (3) of a flexible bracelet and to couple with the second of said cover (1) and support (4) to fix said first strand (3) of bracelet between said cover (1) and support (4). The invention also relates to a timepiece such as a wristwatch comprising a flexible bracelet equipped with such a clasp.