Hairspring Length Modulation for Clock Resonator Stability

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional impulse escapements in mechanical watches introduce disturbances that limit chronometric performance, and existing solutions have not effectively avoided these disturbances.

Innovation Solution

A method for maintaining and regulating a clockwork resonator mechanism around its natural frequency by implementing a regulating device with a periodic movement that imposes a periodic modulation of the resonant frequency, specifically varying the active length of the spring with a regulation frequency between 0.9 and 1.1 times an integer multiple of the natural frequency, greater than or equal to 2, to reduce the influence of the escapement mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional impulse escapement is used in a mechanical watch, then the mechanism can maintain oscillations, but the chronometric performance is limited due to disturbances introduced by the escapement

Engineering Contradiction:
Improveoscillation maintenanceVSAvoidchronometric performance
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies periodic action by modulating the hairspring length at a frequency that is an integer multiple (greater than or equal to 2) of the natural oscillation frequency. This periodic modulation creates parametric excitation that sustains oscillations without requiring a conventional impulse escapement, thereby maintaining reliability while reducing harmful disturbances and improving chronometric performance.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The invention changes the physical parameter of the hairspring length dynamically during operation. By periodically varying the hairspring length at a frequency equal to an integer multiple of the natural frequency, the system achieves parametric resonance that maintains oscillations. This parameter change approach eliminates the need for impulsive escapement forces, resolving the contradiction between maintaining oscillations and achieving high precision.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the active length of the hairspring is modulated to reduce escapement influence, then precision is improved, but the complexity of the regulating device increases

Engineering Contradiction:
ImproveaccuracyVSAvoidregulating device structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the functions of oscillation maintenance and precision regulation into a single mechanism. The periodic hairspring length modulation serves both to sustain oscillations and to eliminate escapement disturbances simultaneously. By combining these functions, the invention improves accuracy without proportionally increasing device complexity, as the same periodic action achieves both goals.

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

This approach enhances the precision of mechanical timepieces by reducing the instability caused by the escapement mechanism, leading to improved accuracy and oscillation maintenance.

Implementation Method 1

said periodic movement imposing a periodic modulation at least of the rigidity of said resonator mechanism, with a regulation frequency which is between 0.9 times and 1.1 times the value of an integer multiple of said natural frequency

Methodology Applied
Scientific EffectParametric resonance: Resonance

Data Source

PatentEP2908187B1Adjustment of a clock piece resonator by changing the active length of a hairspring
Publication Date: 2016.10.19 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP2908187B1 patent drawingFigure 1~6
  • EP2908187B1 patent drawingFigure 7~11
  • EP2908187B1 patent drawing

AI summary

Method for maintaining and regulating a clockwork resonator (1) around its natural frequency (ω0). A regulating device (2) acts on said resonator (1) with a periodic movement that imposes a periodic modulation of at least the resonance frequency of said resonator (1), by imposing at least a modulation of the active length of a spring that comprises said resonator mechanism (1), with a regulation frequency (ωR) that is between 0.9 times and 1.1 times the value of an integer multiple of said natural frequency (ω0), said integer being greater than or equal to 2.