Inertial Sensor Curved Surface Reduces Capacitance Variation
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Solution Overview
Problem
Existing inertial sensors face challenges in achieving high sensitivity and accuracy due to variations in the capacitance caused by tilting of the micro vibration body with respect to the mounting substrate, leading to decreased sensor accuracy.
Innovation Solution
The inertial sensor incorporates a micro vibration body with a curved surface portion and a recessed portion, where the mounted surface and the rim lower surface are located on the same plane, reducing variations in the capacitance when the micro vibration body is tilted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the micro vibration body is mounted on the mounting substrate, then the sensor can detect angular velocity, but tilting of the micro vibration body causes variation in capacitance between the micro vibration body and electrode portions, decreasing measurement precision
Solution Approach 1:
The micro vibration body is designed with a curved surface portion having a specific radius of curvature. This curvature ensures that even when the micro vibration body tilts relative to the mounting substrate, the distance between the curved surface and the electrode portions remains relatively constant, minimizing capacitance variation and maintaining measurement precision
Solution Approach 2:
The patent optimizes the radius of curvature parameter of the micro vibration body's curved surface. By carefully selecting this geometric parameter, the design compensates for tilting effects and maintains stable capacitance characteristics, thereby improving angular velocity detection accuracy
2Measurement precision
If the micro vibration body is made thin-walled to achieve high Q factor, then sensitivity is improved, but manufacturing precision becomes more difficult to control
Solution Approach 1:
The micro vibration body is constructed as a thin-walled hollow structure with controlled wall thickness. This thin-walled design reduces mass and increases the Q factor, enhancing sensitivity while the hollow structure provides structural integrity that facilitates manufacturing control
Solution Approach 2:
The micro vibration body is formed as a hollow structure by creating an inner cavity within an outer shell. This nested configuration allows the thin-walled structure to maintain mechanical strength while achieving the low mass required for high sensitivity, and the manufacturing process can control wall thickness independently
Data Source
AI summary
A micro vibration body includes a curved surface portion, which has an annular curved surface, and a recessed portion, which is recessed from the curved surface portion. A mounting substrate includes an inner frame portion and electrode portions, which surround an inner frame portion. A joining member is provided in an inner region of the mounting substrate surrounded by the inner frame portion. The recessed portion of the micro vibration body has a bottom surface defining a mounted surface located in the inner region and joined to the mounting substrate via the joining member. The curved surface portion has a rim that includes an end portion of the curved surface portion on an opposite side to the recessed portion. The rim has a rim lower surface located on a same plane as the mounted surface or a tip end portion of the mounted surface.