Ferromagnetic Protective Ring for Watch Movement Magnetic and Shock Protection

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Solution Overview

Problem

Existing watch movements are not adequately protected from magnetic fields and mechanical shocks, particularly from impacts caused by the oscillating weight during angular displacement, and existing solutions are bulky and complicate manufacturing.

Innovation Solution

A tubular-shaped antimagnetic and shockproof protection circle made of ferromagnetic material is fixed to the watch movement, limiting angular displacement of the oscillating weight and channeling magnetic fields, with fixing members ensuring secure attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a ferromagnetic box is used to protect the watch movement from magnetic fields, then magnetic field protection is improved, but the watch becomes bulky and its mass increases

Engineering Contradiction:
Improvemagnetic field protectionVSAvoidwatch mass
Core Design Contradiction:
Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

The invention extracts the magnetic shielding function from a bulky ferromagnetic box and concentrates it into a small protective ring made of ferromagnetic material positioned around the oscillating weight, providing the same protection with minimal mass addition

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The solution transitions from a three-dimensional box enclosing the entire movement to a one-dimensional ring structure positioned strategically around the oscillating weight, reducing the volume and mass required for magnetic protection

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If a ferromagnetic box is used to protect the watch movement from magnetic fields, then magnetic field protection is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvemagnetic field protectionVSAvoidmanufacturing complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The protective structure is segmented into a simple ring shape that can be independently manufactured and then installed, separating the magnetic shielding function from the complex assembly of a complete box structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The protective ring functions as a thin ferromagnetic barrier that provides effective magnetic shielding without requiring the thick walls and complex structure of a full box, simplifying both design and manufacturing

Inventive Principle:
Principle #30Flexible shells and thin films

3Object-affected harmful factors

If elastic supports are used to protect the watch movement from mechanical shocks, then shock protection is improved, but the watch becomes bulky and manufacturing is complicated

Engineering Contradiction:
Improvemechanical shock protectionVSAvoidstructure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The invention merges the shock protection function with the existing protective ring structure, allowing the same component to provide both magnetic field shielding and mechanical shock protection, thereby avoiding additional bulky elements

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The protective ring serves multiple functions simultaneously: it acts as a magnetic shield, a mechanical stop, and a shock-absorbing element, eliminating the need for separate dedicated components for each protection type

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

4Reliability

If the oscillating weight is allowed to displace angularly during impact, then the watch movement is vulnerable, but constraining it reduces the protective ring dimensions

Engineering Contradiction:
Improveprotection effectivenessVSAvoidprotective ring volume
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The protective ring is designed with specific dimensional parameters (thickness, radius, material properties) that allow it to effectively limit angular displacement of the oscillating weight while maintaining a compact size that minimizes impact on the watch overall dimensions

Inventive Principle:
Principle #35Parameter changes

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 solution effectively protects the watch movement from magnetic fields and mechanical shocks while maintaining a compact design, minimizing visible impacts and facilitating easy assembly.

Implementation Method 1

The circle is made of a material having ferromagnetic properties and is adapted to constitute, by its first axial end, a stop limiting the angular displacement

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP4160321B1Protective ring for timepiece movement and timepiece movement comprising said protective ring
Publication Date: 2025.09.03 ETA SA MFG HORLOGERE SUISSE
  • EP4160321B1 patent drawingFigure 1~3

AI summary

The invention relates to an anti-magnetic and anti-shock protective ring (10) for a watch movement (20), intended to be fixed to a watch movement (20), said ring (10) comprising a tubular body extending between a first and a second axial end (11, 12) and being characterized in that it is made of a material having ferromagnetic properties and in that it is adapted to constitute, by the first axial end (11), a stop limiting the angular displacement around a radial axis of an oscillating mass (23) connected to the watch movement (20).