Piezoelectric Gyroscope Electrode Layout for Signal Isolation
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Solution Overview
Problem
Vibrating gyroscopes using piezoelectric films face challenges in reducing size and improving performance while maintaining detection accuracy, as small gyroscopes often have weakened signals from angular velocities, making it difficult to distinguish between intended signals and external disturbances.
Innovation Solution
A ring-shaped vibrating gyroscope configuration with a unique electrode disposition allows for high processing accuracy through a dry process, enabling the piezoelectric element to excite primary and detect secondary vibrations generated by coriolis forces without being on the side surface, enhancing flexibility in vibration modes and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the gyroscope size is reduced, then the device becomes more compact and suitable for small devices, but the detection signal from angular velocity becomes weakened and harder to distinguish from external disturbances
Solution Approach 1:
The gyroscope is segmented into functionally distinct regions: a first region with piezoelectric elements for generating and detecting vibrations, and a second region without piezoelectric elements for reducing disturbance signals. This spatial segmentation allows the device to maintain compact size while improving signal-to-noise ratio by isolating detection zones from disturbance-prone areas.
Solution Approach 2:
Different regions of the gyroscope are assigned different local qualities: the first region has piezoelectric elements for active vibration control and detection, while the second region is free of piezoelectric elements to minimize disturbance generation. This local differentiation enables the small gyroscope to achieve adequate detection accuracy by optimizing each region's contribution to the overall performance.
2Device complexity
If piezoelectric elements are formed on the side surface of the vibrating body, then the structure can be simplified, but the processing accuracy and manufacturing precision deteriorate
Solution Approach 1:
The piezoelectric elements are positioned on the surface of the vibrating body rather than on the side surface, representing a dimensional repositioning from vertical (side) to horizontal (surface) placement. This dimensional change enables better manufacturing precision through planar processing techniques while maintaining the functional integration of the structure.
3Volume of moving object
If the gyroscope is made small, then it can be mounted in compact devices, but the signal from coriolis force becomes weaker and more difficult to detect accurately
Solution Approach 1:
The second region is specifically designed to extract or remove the source of disturbance signals by eliminating piezoelectric elements from that area. This extraction of harmful elements (piezoelectric actuators that could generate unwanted vibrations) from the detection region reduces noise and improves the detectability of the weak coriolis force signal in compact gyroscopes.
Solution Approach 2:
The design converts the potential harm of piezoelectric element placement into a benefit by strategically positioning them only in the first region. This selective placement transforms what could be a source of disturbance (piezoelectric actuators near detection zones) into a controlled feature where they generate useful vibrations for detection while being isolated from the sensitive measurement areas.
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 solution enables precise detection of angular velocities with improved resistance to external impacts, enhancing the gyroscope's performance and accuracy by isolating signals effectively from disturbances, thus addressing the limitations of existing technologies.
Implementation Method 1
a piezoelectric element for exciting a primary vibration of the ring-shaped vibrating body
Implementation Method 2
a piezoelectric element for detecting a secondary vibration generated when an angular velocity is applied to the ring-shaped vibrating body
Implementation Method 3
a secondary vibration generated when an angular velocity is applied to the ring-shaped vibrating body
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A vibrating gyroscope comprises a ring-shaped vibrating body (11) a leg portion (15) flexibly supporting the body (11) and having a fixed end, a fixed potential electrode (16), and a plurality of electrodes (13a-13d) with a piezoelectric film sandwiched between an upper and a lower-layer metallic film in a thickness direction thereof. When N is a natural number of 2 or more, the plurality of electrodes (13a-13d) include driving electrodes (13a) for a primary vibration in a vibration mode of cosNθ, which are each disposed (360/N)° apart from each other in a circumferential direction, first detection electrodes (13b) and second detection electrodes (13d) for detecting a secondary vibration generated when an angular velocity is applied to the body (11), which are each disposed in a certain region related to the driving electrode (13a) Each of the electrodes is also disposed in a certain region of the body (11).