Gyro Sensor Beam Spacing for Stable Resonant Frequency
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Solution Overview
Problem
Existing gyro sensors face reduced detection accuracy due to variations in the cross-sectional shape of elastic parts caused by uneven etching gas distribution during the dry etching process, leading to variations in resonant frequency.
Innovation Solution
The physical quantity sensor design includes a structure with specific beam configurations and spacing relationships to minimize the aperture ratio variations, reducing the impact of etching gas spreading and maintaining consistent resonant frequencies across the sensor elements.
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 uneven etching gas distribution, reducing detection accuracy
Solution Approach 1:
The patent applies local quality by configuring beams with different spacing relationships. Specifically, the space between adjacent beams (T2) is made smaller than the space between the outer beam and the structure (T1), creating different aperture ratios in different regions. This local variation in aperture ratio ensures uniform etching gas distribution across all beam regions, eliminating the cross-sectional shape variation that would otherwise occur and thereby maintaining high detection accuracy while preserving manufacturing efficiency through dry etching.
2Device complexity
If the aperture ratio between the outer beam and the structure is high, then the structural design is simplified, but side etching progresses further due to etching gas spreading, increasing cross-sectional shape variation
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through differentiated spacing: the space T1 between the outer beam and structure is intentionally made larger than the space T2 between adjacent beams. This creates a local aperture ratio relationship where T1/T2 > 1, ensuring that all beam regions experience similar etching conditions. The result is uniform cross-sectional shapes across all beams while maintaining relatively simple structural design, as the solution is achieved through straightforward dimensional relationships rather than complex structural modifications.
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 stabilizes the detection accuracy by reducing the variation in resonant frequency, resulting in improved output characteristics for angular velocity sensors and enabling the formation of reliable composite sensors and inertial measurement units.
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 and this Coriolis force causes the vibrator to vibrate in the direction of the Y-axis (or Z-axis) (detection vibration)
Implementation Method 4
a voltage applied to the fixed comb-like electrode generates an electrostatic force between the movable electrode and the fixed comb-like electrode and this electrostatic force causes the vibrator to vibrate in the direction of an X-axis (drive detection)
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.