Physical Quantity Sensor Asymmetric Through-Holes
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Solution Overview
Problem
Existing physical quantity sensors, such as acceleration sensors, face challenges in simplifying their configuration due to differences in electrode overlap areas, leading to increased manufacturing complexity and cost, while also requiring adjustments for initial capacitance differences and inefficient damping, which affects detection sensitivity.
Innovation Solution
A physical quantity sensor design featuring a movable body with balanced electrostatic capacitances between electrode portions, utilizing through-holes of varying widths to equalize initial capacitances and reduce damping, allowing for a simpler configuration and enhanced detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If through-holes of different sizes are disposed in the wings to reduce damping, then detection sensitivity is enhanced, but the electrode overlap areas become different causing initial capacitance differences that require additional adjustment processes
Solution Approach 1:
The patent applies asymmetry by intentionally making the through-holes different: a first through-hole with a larger diameter is disposed in the first wing, while a second through-hole with a smaller diameter is disposed in the second wing. This asymmetric design reduces damping effects while the electrode areas are specifically designed to compensate for the different through-hole sizes, ensuring equal initial capacitances without requiring additional adjustment processes.
Solution Approach 2:
The patent applies local quality by making the electrode areas asymmetric to compensate for the asymmetric through-holes. Specifically, the first electrode has an area larger than the second electrode area, which compensates for the larger first through-hole. This local adjustment ensures that the initial capacitances are equal while maintaining the damping reduction benefits of the different-sized through-holes.
2Measurement precision
If through-holes are disposed in the wings to reduce damping, then detection sensitivity is enhanced, but manufacturing processes and cost increase due to electrode area mismatches
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-designing the electrode areas to be different (first electrode area > second electrode area) based on the known through-hole size differences. This preliminary design ensures that the initial capacitances are equal from the start, eliminating the need for post-manufacturing adjustment processes and simplifying the overall manufacturing process.
3Object-generated harmful factors
If the electrode overlap areas are made different to accommodate varying through-hole sizes, then damping is reduced, but initial capacitance differences require additional correction circuits or adjustments
Solution Approach 1:
The patent applies parameter changes by specifically designing the electrode areas to be different (first electrode area > second electrode area) to compensate for the different through-hole sizes. This parameter adjustment ensures that the initial capacitances are equal, eliminating the need for correction circuits while maintaining reduced damping effects from the asymmetric through-holes.
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
The sensor achieves equal initial electrostatic capacitances between electrode portions and efficiently reduces damping, resulting in a simpler configuration and improved detection sensitivity without the need for additional adjustments or increased manufacturing complexity.
Implementation Method 1
an electrostatic capacitance between the one wing and the first electrode and an electrostatic capacitance between the other wing and the second electrode
Implementation Method 2
damping (action to stop the movement of the mass, or flow resistance) caused by the viscosity of the gas can be reduced
Data Source
AI summary
A physical quantity sensor includes: a substrate; a movable body including, with a first axis as a boundary, a first movable electrode portion disposed in a first region, a second movable electrode portion disposed in a second region, and a damping adjusting portion disposed in at least one of the first region and the second region; beam portions supporting the movable body; a first fixed electrode portion; and a second fixed electrode portion. A first through-hole is disposed in the damping adjusting portion. Second through-holes are disposed in the movable electrode portions. The area of a region where the first movable electrode portion overlaps with the first fixed electrode portion is the same as the area of a region where the second movable electrode portion overlaps with the second fixed electrode portion. The width of the first through-hole is greater than the widths of the second through-holes.