Physical Quantity Sensor Short Electrode Fingers Impact Resistance
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Solution Overview
Problem
Existing acceleration sensors have elongated electrode fingers that are prone to damage due to impacts, leading to reduced reliability and accuracy in detecting physical quantities.
Innovation Solution
A physical quantity sensor design featuring shorter electrode fingers with tilted trunks and strategically arranged movable and stationary electrodes, which are supported by a frame-shaped movable member and connected via springs, enhancing impact resistance and detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrode fingers are elongated to increase detection sensitivity, then measurement precision is improved, but reliability deteriorates due to increased susceptibility to impact damage
Solution Approach 1:
The electrode structure is divided into multiple segments: a trunk portion and multiple finger portions. The finger portions are made shorter and thinner, while the trunk provides structural support. This segmentation allows the sensitive finger portions to be short for impact resistance, while maintaining sufficient detection area through multiple fingers arranged in parallel.
Solution Approach 2:
Different parts of the electrode structure have different properties: the trunk portion has larger cross-sectional area and higher structural strength for impact resistance, while the finger portions have smaller cross-sectional area optimized for capacitive detection sensitivity. This local differentiation resolves the contradiction between overall structural strength and local detection performance.
2Reliability
If electrode fingers are shortened to improve impact resistance, then reliability is improved, but measurement precision deteriorates due to reduced detection area
Solution Approach 1:
The electrode is segmented into multiple finger portions that can be arranged in parallel. Each finger is short for impact resistance, but the collective detection area of multiple fingers compensates for the reduced length, maintaining sufficient capacitive coupling for accurate acceleration detection.
Solution Approach 2:
Multiple electrode fingers are combined in parallel configuration, where each short finger contributes to the total capacitive detection area. The combined effect of multiple short fingers achieves detection sensitivity comparable to or exceeding that of a single long finger, while maintaining superior impact resistance.
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 design results in a sensor with improved impact resistance and higher accuracy in detecting physical quantities, as the shorter electrode fingers are less susceptible to damage and the frame-shaped movable member increases the sensor's mass, enhancing sensitivity.
Implementation Method 1
the first movable electrode section has first movable electrode fingers extending from the movable member toward the positive side in the Y-axis direction, and opposing the first stationary electrode fingers in the X-axis direction
Data Source
AI summary
A physical quantity sensor includes a stationary electrode, an X-axis displaceable movable member, and a movable electrode. The stationary electrode includes first and second movable electrodes arranged side by side along the Y-axis direction. The first and second stationary electrodes respectively include first and second stationary electrode fingers extending from first and second trunks in the ±Y-axis directions. The movable electrode includes first and second movable electrodes arranged side by side in the Y-axis direction. The first and second movable electrodes respectively include first and second movable electrode fingers located on both sides in the Y-axis direction of the first and second trunks, and opposed to the first and second stationary electrode fingers.