Acceleration Sensor Rod-Shaped Weight Center Mass
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Solution Overview
Problem
Existing acceleration sensors face reduced detection accuracy due to increased rotational moment and potential rotational resonance, particularly when detecting orthogonal accelerations, which affects their ability to accurately measure accelerations in both x-axis and y-axis directions.
Innovation Solution
The acceleration sensor design includes a semiconductor substrate with a rod-shaped weight portion passing through the center of a rectangular frame, reducing the rotational moment by applying the mass of movable electrodes near the frame's center, and symmetrically arranging electrodes to minimize the impact of thermal strain and substrate deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the movable electrodes are positioned away from the center of the frame to enable orthogonal acceleration detection, then the detection capability in multiple directions is improved, but the rotational moment increases causing reduced measurement accuracy
Solution Approach 1:
The patent applies asymmetry by strategically positioning the movable electrodes at specific locations on the frame portion that are optimized for detecting orthogonal accelerations while minimizing rotational moment. The electrodes are arranged in an asymmetric configuration relative to the frame center, allowing differential measurement that cancels out rotational effects and improves both detection capability and measurement accuracy simultaneously.
2Ease of operation
If the frame portion is released from the support substrate to enable movement, then the mobility and detection range are improved, but rotational resonance occurs reducing detection accuracy
Solution Approach 1:
The patent employs counterweight principles by positioning the movable electrodes and their supporting structures to create balanced mass distribution on the frame portion. This balancing reduces the rotational moment of inertia and minimizes rotational resonance effects, allowing the frame to move freely for enhanced mobility while maintaining detection accuracy by counteracting unwanted rotational movements.
3Stability of the object's composition
If multiple beam portions are added to support the frame for orthogonal detection, then the structural stability is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by designing the beam portions to serve multiple functions simultaneously. The same beam structures that provide structural support and stability also serve as the mechanical elements that enable orthogonal acceleration detection and contribute to balancing the rotational moment. This multi-functionality reduces device complexity by eliminating the need for separate components for each function.
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 configuration enhances detection accuracy by reducing rotational resonance and maintaining accuracy even under thermal strain, allowing for precise measurement of accelerations in both orthogonal directions.
Implementation Method 1
a first beam portion J9a that displaces the frame portion J8 in the y-axis direction when an acceleration including a component in the y-axis direction is applied to the first beam portion J9a
Implementation Method 2
the acceleration is detected on the basis of a capacity between the movable electrode and the fixed electrode
Data Source
AI summary
In an acceleration sensor, a semiconductor layer is provided with a rod-shaped weight portion that passes through a center of a frame portion, extends in a second direction, and is connected to the frame portion through a first beam portion. A first-direction movable electrode and a second-direction movable electrode are provided on the weight portion. According to the above configuration, because a mass of the first- and second-direction movable electrodes can be applied to the vicinity of a center of the frame portion, and a rotational moment can be reduced. Thus, detection accuracy can be restrained from being reduced.