Multi-Axis Acceleration Sensor with Capacitance Control
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Solution Overview
Problem
Conventional acceleration sensors are unable to accurately detect acceleration along the X-axis and Y-axis due to the design, which causes limited movement of the weight, resulting in small changes in capacitance between electrodes, leading to inaccurate measurements.
Innovation Solution
The acceleration sensor incorporates a mount section, a flexible section, and weights with opposed electrode units arranged along different axes, allowing for detection of acceleration components in multiple directions by changing the capacitance between electrodes in response to applied forces, using control voltages to adjust for simultaneous increases or decreases in capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If weight is placed on the lower surface of flexible substrate and located above away from mount substrate, then the weight can be displaced easily along the Z-axis, but the sensor cannot detect acceleration along the X-axis or Y-axis accurately
Solution Approach 1:
The patent transitions from a single-axis (Z-axis) capacitance measurement to multi-axis detection by arranging electrode pairs in both X and Y directions. The first electrode pair detects X-axis acceleration while the second electrode pair detects Y-axis acceleration, enabling three-dimensional acceleration measurement capability.
Solution Approach 2:
The sensor is divided into multiple functional components: first electrode pair for X-axis detection, second electrode pair for Y-axis detection, and multiple weights distributed on the flexible substrate. Each component serves a specific detection function, allowing independent measurement of acceleration along different axes.
2Device complexity
If single electrode pair is used for capacitance measurement, then the structure is simple, but only one direction of acceleration can be detected
Solution Approach 1:
The flexible substrate with distributed weights and multiple electrode pairs serves multiple functions simultaneously: it acts as both the sensing element and the structural support, while the electrode pairs enable detection along both X and Y axes using the same basic capacitance measurement principle.
3Measurement precision
If control voltage is applied to opposed electrode units, then accurate acceleration detection is achieved, but additional control circuitry is required
Solution Approach 1:
The patent applies control voltage to the opposed electrode units based on feedback from capacitance measurements. When both first and second capacitances simultaneously increase or decrease, the control voltage is adjusted to compensate for these changes, maintaining accurate acceleration detection despite variations in electrode spacing or environmental factors.
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 design enables accurate detection of acceleration in all three axes, improving the sensor's ability to measure angular velocity and Coriolis forces, enhancing its performance in attitude-control and navigation systems for mobile carriers.
Implementation Method 1
This displacement changes the distance between flexible substrate 63 and glass substrate 65, accordingly changing a capacitance between opposed electrodes 66. The sensor detects the acceleration based on the change in the capacitance due to the change in the distance between electrodes 66.
Data Source
AI summary
An acceleration sensor includes first and second opposed electrode units. The first opposed electrode unit includes a first electrode and a second electrode spaced away from and facing the first electrode, and provides a first capacitance. The second opposed electrode unit includes a third electrode and a fourth electrode spaced away from and facing the third electrode, and provides a second capacitance. The first and third electrodes are arranged along a first direction. A component of acceleration along the first direction applied to the object is detected based on the first and second capacitances. A control voltage is applied to the first and second opposed electrode units. The control voltage is changed when both of the first capacitance and the second capacitance simultaneously increase or decrease. This acceleration sensor detects the acceleration accurately.