Monocrystalline Silicon Oscillator with 45-Degree Lattice Offset
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Solution Overview
Problem
Existing mechanical oscillators in monocrystalline silicon exhibit varying mechanical characteristics across different directions of a plane, and their stiffness is temperature-dependent, making them challenging to manufacture and maintain consistent quality, especially in precision applications like watch balance springs.
Innovation Solution
A mechanical oscillator is created using a composite structure of two monocrystalline silicon layers with crystal lattices offset by 45 degrees, combined with a thermal compensation layer having a Young's modulus thermal coefficient opposite to silicon, to ensure isotropic mechanical behavior and temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single crystal silicon wafer is used to manufacture mechanical oscillators, then manufacturing precision and design regularity are improved, but the Young's modulus varies in different crystallographic directions causing anisotropic mechanical behavior
Solution Approach 1:
The single crystal silicon wafer is segmented into multiple layers with different crystallographic orientations. Each layer maintains the advantages of monocrystalline silicon while the combination of layers with different orientations (e.g., <100>, <110>, <111>) compensates for the anisotropic behavior, achieving overall isotropic mechanical properties.
Solution Approach 2:
The patent creates a composite structure by stacking multiple monocrystalline silicon layers with different crystallographic orientations. This composite approach combines the high manufacturing precision of monocrystalline silicon with isotropic mechanical behavior, as the different orientations compensate for each other's anisotropy.
2Temperature
If complex alloys are used to compensate for temperature variations in Young's modulus, then temperature stability is improved, but manufacturing complexity and production cost increase
Solution Approach 1:
The patent changes the crystallographic orientation parameters of the silicon layers to achieve temperature compensation. By selecting specific orientations (<100>, <110>, <111>) and combining them in particular configurations, the structure exploits the different thermal behaviors of silicon in various directions to compensate for Young's modulus variations with temperature.
Solution Approach 2:
Instead of using complex alloys, the patent creates a composite structure of monocrystalline silicon layers with different orientations. This composite approach achieves temperature stability through the synergistic combination of layers, where the thermal expansion and Young's modulus variations of different orientations compensate for each other.
3Manufacturing precision
If monocrystalline silicon is used for mechanical oscillators, then manufacturing precision is improved, but tuning is time-consuming and requires many manual interventions
Solution Approach 1:
The oscillator structure is segmented into multiple layers with predetermined crystallographic orientations that are designed to self-compensate for mechanical variations. This segmentation allows the structure to achieve isotropic behavior and temperature stability without requiring manual tuning, as the compensation is built into the layered architecture.
Solution Approach 2:
The multi-layered structure with different crystallographic orientations performs self-compensation for anisotropic effects and temperature variations. The structure is designed to automatically maintain consistent mechanical properties without requiring manual intervention for tuning, thereby reducing production time and eliminating defective parts.
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 results in a mechanical oscillator with identical mechanical properties in all directions and reduced temperature-induced variations, simplifying manufacturing and enhancing precision, particularly suitable for spiral springs in mechanical timepieces.
Implementation Method 1
a thermal compensation layer (Co1) consisting of a material having a thermal coefficient of the Young's modulus of sign opposite to that of silicon
Data Source
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AI summary
The invention relates to a mechanical oscillator equipped with a bar (11), said bar (11) including a first silicon layer (Cs1) having a crystal lattice extending in a first direction (Ds1) of a plane, a thermally compensating layer (Co1) formed from a material having a Young's modulus of thermal coefficient of opposite sign to that of silicon, and a second silicon layer (Cs2) having a crystal lattice extending in a second direction (Ds2) of the plane, the first and second directions (Ds1, Ds2) being shifted by an angle of 45° in the plane of the layers, and the thermally compensating layer (Co1) extending between the first and second silicon layers (Cs1, Cs2).