Gyro Sensor Beam Structure for Resonant Frequency Stability
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Solution Overview
Problem
The existing gyro sensor manufacturing techniques using dry etching result in variations in the cross-sectional shape of elastic parts, leading to reduced detection accuracy due to variations in resonant frequency, especially at sites with higher or lower aperture ratios.
Innovation Solution
The physical quantity sensor design includes a structure where the first beam facing the outer beam is positioned such that the aperture ratio between the outer beam and the structure is reduced, specifically with T2<T1, to minimize the variation in cross-sectional shape and resonant frequency, with preferred ratios of 0.8<T3/T2<3.0, 0.8<T3/T2≤2.0, and 0.9≤T3/T2≤1.1, and a depth of 20 μm≤D1≤30 μm, to maintain detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry etching is used to manufacture the sensor element, then manufacturing efficiency is improved, but the cross-sectional shape of elastic parts varies due to etching gas spreading, reducing detection accuracy
Solution Approach 1:
The patent introduces auxiliary beams at specific locations (outer side of the elastic part) to locally modify the aperture ratio distribution. This creates non-uniform structural quality that compensates for the non-uniform etching gas spreading, ensuring consistent cross-sectional shapes across different regions of the elastic part while maintaining overall manufacturing efficiency through dry etching.
Solution Approach 2:
The patent modifies the aperture ratio parameter by adding auxiliary beams, changing the local geometric parameters of the elastic part structure. This parameter adjustment ensures that regions with different initial aperture ratios all achieve uniform etching characteristics, resolving the cross-sectional shape variation problem while preserving the benefits of dry etching manufacturing.
2Stability of the object's composition
If the aperture ratio between outer beam and structure is high, then structural flexibility is improved, but side etching progresses further causing greater cross-sectional shape variation
Solution Approach 1:
The patent applies local quality modification by adding auxiliary beams specifically at the outer side of the elastic part where high aperture ratios cause excessive side etching. This localized structural addition reduces the aperture ratio only in problematic regions, maintaining structural flexibility in other areas while preventing cross-sectional shape variation at critical locations.
Solution Approach 2:
The auxiliary beams are designed to preemptively counteract the side etching effect by reducing the aperture ratio in advance. This preliminary anti-action prevents the etching gas from spreading excessively into the elastic part, thereby maintaining cross-sectional shape consistency before the etching process begins.
3Manufacturing precision
If the aperture ratio between beams is low, then cross-sectional shape variation is reduced, but structural flexibility decreases
Solution Approach 1:
The patent implements local quality differentiation by adding auxiliary beams only at the outer side of the elastic part rather than uniformly across the entire structure. This selective modification reduces aperture ratio only where needed to control side etching, preserving structural flexibility in the inner regions where low aperture ratios would unnecessarily constrain motion.
Solution Approach 2:
The patent selectively changes the aperture ratio parameter at specific locations by adding auxiliary beams, rather than uniformly reducing aperture ratios throughout the structure. This targeted parameter modification achieves cross-sectional shape consistency in etched regions while maintaining structural flexibility in non-etched regions.
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 design reduces the variation in resonant frequency and enhances detection accuracy by minimizing the impact of etching gas spreading, resulting in stable output characteristics for angular velocity sensors and composite sensors, and enables the formation of reliable inertial measurement units, portable electronic apparatuses, and vehicles.
Implementation Method 1
the resonant frequency at each site of the elastic part varies
Implementation Method 2
the etching gas spreads unevenly, thus causing the cross-sectional shape of each site to vary
Implementation Method 3
An angular velocity about a Z-axis (or Y-axis) acting on the vibrator in such a vibrating state generates a Coriolis force
Data Source
AI summary
A gyro sensor includes: a spring having an inner span beam connected to an outer span beam via a turnaround beam; and a fixed driver that laterally faces the outer beam. A first beam is provided to the structure side of the outer beam so as to face the outer beam. T1 is a width of a space between the outer beam and the structure, T2 is a width of a space between the inner and outer beams, and T2<T1.