Monolithic Quartz Vibrating Beam Accelerometer for Thermal Stability
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Solution Overview
Problem
Vibrating beam accelerometers face accuracy and precision issues due to thermally induced strains caused by differential coefficients of thermal expansion between various components, particularly at the bonding mechanism between resonators and the proof mass, leading to inaccurate measurements.
Innovation Solution
The use of a monolithic crystalline quartz substrate with components formed and attached without adhesives, utilizing selective laser etching to create 3D structures with matching coefficients of thermal expansion, ensuring all components, including resonators, proof mass, and support structures, have the same thermal properties, thereby minimizing thermal expansion differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If different materials are used for resonators and proof mass, then manufacturing flexibility is improved, but measurement precision deteriorates due to differential thermal expansion
Solution Approach 1:
The patent applies homogeneity by making the resonators and proof mass from the same material (quartz), eliminating differential thermal expansion between components. This ensures that all parts expand and contract uniformly with temperature changes, preventing measurement errors while maintaining manufacturing feasibility through monolithic fabrication processes
2Ease of operation
If adhesives are used to bond resonators to proof mass, then assembly ease is improved, but measurement precision deteriorates due to thermal expansion differences at bonding interfaces
Solution Approach 1:
The patent extracts the bonding adhesive from the system entirely by using monolithic quartz construction where resonators are directly integrated with the proof mass. This eliminates the bonding interface that would otherwise create thermal expansion mismatches and measurement errors, achieving both precise measurements and feasible assembly through direct monolithic fabrication
3Measurement precision
If monolithic quartz construction is used, then measurement precision is improved by eliminating thermal expansion differences, but device complexity increases
Solution Approach 1:
The patent merges the resonators and proof mass into a single monolithic quartz structure, eliminating the need for separate components and their associated bonding interfaces. This integration reduces the number of parts and assembly steps while simultaneously eliminating thermal expansion mismatches, thereby improving precision without proportionally increasing complexity
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 motion sensing accuracy and robustness by eliminating thermal-induced errors, ensuring precise measurement of acceleration and force changes across varying temperatures.
Implementation Method 1
utilizing selective laser etching to create 3D structures
Implementation Method 2
vibrating beam accelerometers function by detecting the displacement of a proof mass under inertial forces
Implementation Method 3
measure the force induced in resonators as they counteract inertial forces of the proof mass
Implementation Method 4
detecting the displacement of a proof mass under inertial forces
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
A proof mass assembly includes a monolithic substrate, the monolithic substrate including a proof mass, a proof mass support, and a flexure connecting the proof mass to the proof mass support. The proof mass is configured to rotate relative to the proof mass support via the flexure. The monolithic substrate further includes a first resonator connected to a first major surface of the proof mass and a first maj or surface of the proof mass support and a second resonator connected to a second major surface of the proof mass and a second major surface of the proof mass support.