Humidity-Resistant Balance Spring Coating for Thermally Compensated Resonators
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Solution Overview
Problem
Existing balance springs in watch movements are sensitive to climatic variations, particularly during severe condensation, affecting the rate of the watch movements.
Innovation Solution
A compensating balance spring with a non-metallic core, such as quartz or doped silicon, partially coated with a moisture-resistant and impermeable layer of chromium, titanium, or tantalum, to minimize sensitivity to climatic variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a balance spring is made from non-metallic materials like quartz or silicon with silicon dioxide coating, then thermal compensation is improved, but sensitivity to humidity and condensation increases
Solution Approach 1:
The balance spring combines multiple materials with complementary properties: a non-metallic core (quartz or silicon) for thermal compensation, silicon dioxide coating for additional protection, and a moisture-resistant metallic layer (chromium, titanium, or tantalum) for humidity barrier. This composite structure resolves the contradiction by integrating materials that address both thermal stability and moisture resistance simultaneously.
Solution Approach 2:
The moisture-resistant layer is applied selectively to specific regions of the balance spring rather than uniformly coating the entire structure. This localized application provides humidity protection where most needed while minimizing the overall mass and maintaining the spring's mechanical properties for thermal compensation.
2Object-affected harmful factors
If a moisture-resistant layer is added to the balance spring, then humidity resistance is improved, but device complexity increases
Solution Approach 1:
The moisture-resistant layer is designed with optimized parameters: thickness between 1-50 nanometers and specific material composition (chromium, titanium, or tantalum). By carefully controlling these parameters, the coating provides effective humidity protection while maintaining thin-film characteristics that minimize impact on the balance spring's mechanical behavior and keep the overall device simple.
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 balance spring operates less disturbed by climatic changes, maintaining the stability of the resonator's operation under severe condensation conditions.
Implementation Method 1
a coating of silicon dioxide characterized in that the core is partially coated with a layer which is resistant and impermeable to humidity
Data Source
Figure 1~7
AI summary
The invention relates to a compensating balance-spring (1) for a thermally compensated resonator with a balance and spring assembly, comprising a core (9a, 9b, 9c, 9d, 9e, 9f) formed from at least one non-metal material (11a, 11b, 13b, 15b, 11c, 17c, 19c, 11d, 13d, 15d, 17d, 19d, 11e, 13e, 15e, 17e, 19e, 11f, 21 f). According to the invention, the core (9a, 9b, 9c, 9d, 9e, 9f) is partially coated with at least one layer (7) which is humidity-stable in order to render the compensating balance-spring (1) less sensitive to climatic variations. The invention relates to the field of timepieces.