Wristwatch Strap Change Mechanism Using Rotating Cam and Rods

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Solution Overview

Problem

Existing wristwatch designs are complex and inefficient in allowing easy and quick strap changes without requiring tools, making it difficult to adapt to existing models.

Innovation Solution

A wristwatch design featuring a rotating part with an annular cam and rods that unlock and lock the bracelet strands, allowing for easy detachment and reattachment without radical modifications, using an annular cam secured to the rotating part and rods connecting to the bar end housing to facilitate the strap change process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a box mechanism is used to allow tool-free bracelet removal, then ease of operation is improved, but device complexity increases significantly

Engineering Contradiction:
Improveease of bracelet removalVSAvoidcomplexity of box mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts the essential function of the complex box mechanism and implements it through a simplified system consisting of an annular cam and rods. The cam, when rotated, directly pushes the rods to unlock the bracelet bars from the horns, eliminating the need for a complex box structure while maintaining tool-free operation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a dynamic rotating annular cam that transforms the static locking mechanism into a dynamic one. By rotating the cam, the user actively controls the unlocking process, allowing easy bracelet removal and reattachment without complex mechanical structures.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If existing wristwatch designs are modified to enable easy strap changes, then ease of operation is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveease of strap changeVSAvoidmanufacturing complexity
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The annular cam mechanism serves multiple functions: it unlocks the bracelet bars, controls their movement, and can be integrated into existing watch cases. This multi-functional component can be adapted to various existing wristwatch models without requiring radical redesigns, maintaining ease of manufacture.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent segments the bracelet system into independent components (bars, horns, rods, cam) that can be manufactured separately and assembled. This modular approach allows existing watches to be adapted with minimal modification, as the new components can be added without redesigning the entire watch structure.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If a rotating cam mechanism is added to existing models, then adaptability is improved, but device complexity increases

Engineering Contradiction:
Improveadaptability to existing modelsVSAvoidcomplexity of cam and rod system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the annular cam with the existing rotating crown or bezel of the wristwatch, combining the strap change function with an existing operational element. This integration minimizes the addition of separate components and reduces overall device complexity while maintaining adaptability to existing models.

Inventive Principle:
Principle #5Merging (Combining)

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 quick and easy strap changes without the need for tools, maintaining the existing design and operation of the watch, and can be adapted to existing models, enhancing user convenience and simplicity.

Implementation Method 1

an annular cam secured to the rotating part, at least two rods, one occupying a horn bore of a pair of horns and the other occupying a horn bore of the other pair of horns, each rod being able to connect the annular cam to the bar end housing of the horn in which this rod is located

Methodology Applied
Scientific EffectCam mechanism: Cam

Data Source

PatentEP3338145B1Wristwatch with easy strap change
Publication Date: 2019.10.02 CHOUET CLAUDE
  • EP3338145B1 patent drawingFigure 1~2
  • EP3338145B1 patent drawingFigure 3~5
  • EP3338145B1 patent drawingFigure 6~10

AI summary

The invention concerns a wristwatch of which the strap can be changed easily and quickly. Said wristwatch comprises a rotating part (1, 1bis) mounted on a case (2) comprising two pairs of horns (4,5; 6,7), each horn having a housing (14,15,16,17) receiving one end (10,11,12,13) of a bar (8,9) of a strap strand, and is characterised in that each pair of horns (4,5; 6,7) comprises at least one horn (4,7) pierced with a bore extending from the face of the case (2) located on the dial side to a bar-end housing (14,17), and in that it further comprises: - an annular cam (18,18bis) secured to the rotating part (1,1bis), at least two rods (19, 20), one (19) occupying a bore of a horn (7) of one pair of horns (6,7), the other (20) occupying a bore of a horn (4) of the other pair of horns (4,5), each rod (19,20) being capable of linking the annular cam (18,18bis) to the bar-end housing (17,14) of the horn (7,4) in which said rod (19, 20) is located. The invention also relates to a method for changing the strap of such a wristwatch. Therefore, by simply rotating a rotating part provided on the case, each strap strand can be detached and replaced with another.