Watch Dial Attachment with Tangential Elastic Mobility

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Solution Overview

Problem

Dials attached to watch plates made of different materials experience differential expansion due to varying coefficients of expansion, leading to deformation at temperature variations, which can cause the hands to slip out, rendering the watch unsuitable for use, especially in extreme environments.

Innovation Solution

A watch assembly with centering pins and elastic return means, including clipping lugs, that allow tangential mobility to accommodate thermal expansion, ensuring proper dial positioning and attachment without prior machining of the dial.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If rigid attachment means are used to fix the dial to the plate, then the dial is securely held in position, but the dial deforms due to differential thermal expansion

Engineering Contradiction:
Improvedial positioning stabilityVSAvoiddial geometry stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies the dynamics principle by making the holding means elastic rather than rigid. The elastic return means with tangential mobility allows the dial to dynamically adjust to thermal expansion forces while maintaining secure attachment. The elastic clipping lugs can deform elastically in the tangential direction, absorbing expansion stresses without causing dial deformation or detachment.

Inventive Principle:
Principle #15Dynamics

2Strength

If the dial is rigidly fixed to the plate, then attachment strength is maximized, but the dial cannot accommodate thermal expansion

Engineering Contradiction:
Improveattachment strengthVSAvoidthermal expansion adaptability
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by modifying the mechanical properties of the holding means. The elastic return means changes its dimensional parameters under thermal stress through elastic deformation. The tangential mobility allows the clipping lugs to change position slightly in the tangential direction, accommodating expansion while maintaining strong radial attachment through the stop surface cooperation.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If complex fixing mechanisms with prior machining are used, then dial attachment reliability is improved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improvedial attachment reliabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the taking out principle by extracting the complexity from the dial itself and placing it in the holding means on the plate. The dial remains simple without requiring peripheral machining or complex features. All the sophisticated elastic holding and centering mechanisms are integrated into the plate's holding means, simplifying dial manufacturing while ensuring reliable attachment.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies self-service through the elastic return means that automatically exert pressing force on the dial without requiring additional fastening elements like screws or clips. The elastic deformation of the clipping lugs provides self-adjusting attachment pressure, and the tangential mobility provides self-accommodation to thermal stresses, eliminating the need for complex adjustment mechanisms.

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 solution ensures the dial maintains proper geometry and flatness despite thermal expansion, preventing hand slippage and allowing for cost-effective, simple assembly without specialized equipment, ensuring the watch functions across varying temperatures.

Implementation Method 1

said holding means or and complementary holding means comprising elastic return means for pressing said at least one dial against said at least one plate

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2690509B1Dial attachment to a timepiece plate
Publication Date: 2014.12.24 ETA SA MFG HORLOGERE SUISSE
  • EP2690509B1 patent drawingFigure 1~8

AI summary

The assembly has a bottom plate (1) and a cut blank dial (2) secured one on top of the other, where centering pins (3) cooperate with an oblong groove (4) in the dial. Clips (5) are arranged to cooperate with complementary clips integral with the bottom plate. The clips and/or complementary clips include an elastic return unit for pressing the dial resting onto the bottom plate, where the elastic return unit tangentially moves along a plane (PT) perpendicular to a plane (P) of the bottom plate and to a radial line (R) connecting the center (O) of the bottom plate to the elastic return unit.