Polycrystalline Silicon Balance Spring Temperature Compensation
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Solution Overview
Problem
Mechanical oscillating systems in clocks face challenges with deformation and accuracy issues due to thick silicon oxide layers on balance springs, leading to temperature compensation problems and production inconsistencies.
Innovation Solution
A mechanical oscillating system using a balance spring made of polycrystalline silicon with a silicon oxide layer of maximum 4 μm thickness and an oscillating body made of molybdenum or its alloys, combined with adjusting elements and a spring retainer block for improved temperature compensation and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thick silicon oxide layer is applied to the balance spring for temperature compensation, then temperature stability is improved, but deformation of the balance spring occurs leading to accuracy deterioration
Solution Approach 1:
The patent changes the material parameter from conventional metal to silicon, which has a negative thermal expansion coefficient. This allows the balance spring to compensate for temperature changes intrinsically through its material properties rather than relying on a thick silicon oxide coating, thereby avoiding deformation while maintaining temperature stability.
Solution Approach 2:
The patent uses silicon, a non-metallic crystalline material, as the base material for the balance spring. This composite approach combines the advantages of silicon's thermal properties with precise mechanical characteristics, achieving temperature compensation without the harmful effects of thick oxide layers.
2Temperature
If a thick silicon oxide layer is applied to the balance spring, then temperature compensation is improved, but production reproducibility deteriorates
Solution Approach 1:
By changing from a thick silicon oxide coating approach to using silicon as the base material with inherent negative thermal expansion properties, the patent eliminates the variability associated with thick oxide layer application processes, thereby improving production reproducibility while maintaining temperature compensation.
3Strength
If the balance spring is made from conventional metal, then mechanical strength is sufficient, but temperature-independent accuracy deteriorates
Solution Approach 1:
The patent employs silicon, a non-metallic crystalline material, which combines adequate mechanical strength for balance spring application with unique thermal properties (negative thermal expansion coefficient). This material choice achieves temperature-independent accuracy while maintaining sufficient mechanical strength.
Solution Approach 2:
The patent fundamentally changes the material class from metallic to non-metallic crystalline silicon, utilizing silicon's negative thermal expansion coefficient to achieve temperature compensation, thereby improving temperature-independent accuracy while maintaining adequate mechanical strength.
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 provides a temperature-independent and accurate oscillating system by minimizing deformation risks and enhancing the dynamic moment of inertia, ensuring precise frequency stability across temperature changes.
Implementation Method 1
a linear thermal expansion coefficient smaller than 8×10−6/K
Implementation Method 2
enhancing the dynamic moment of inertia, ensuring precise frequency stability
Data Source
AI summary
A mechanical oscillating system for a clock including a balance spring manufactured from a non-metallic, polycrystalline material with a grain size between 10 and 50,000 nm, with a winding area of the balance spring 0.001 mm2 to 0.3 mm2, an oscillating body and a shaft for mounting of the oscillating body and the balance spring on the shaft. A spiral spring for a clock being manufactured from a non-metallic material, wherein the non-metallic material is a polycrystalline material with a grain size between 10 and 50,000 nm, and having a linear thermal expansion coefficient smaller than 8×10−6/K.