Piezoelectric Gyroscope Transversal Drive Transducer
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Solution Overview
Problem
Piezoelectrically driven and sensed gyroscopes face challenges such as the need for large transducers to generate sufficient actuation force and produce high signal-to-noise ratios, non-orthogonal drive and sense oscillation movements, and non-uniform bending modes of piezoelectric transducers, which hinder their development compared to electrostatically driven gyroscopes.
Innovation Solution
The use of a piezoelectric transducer placed on the transversal synchronization spring connecting inertial masses to synchronize their anti-phase oscillation, ensuring flexible suspenders for sense oscillation, minimizing misalignment effects, and integrating drive transducers into existing device elements without increasing area consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If piezoelectric transducers are used to drive inertial masses into rotational oscillation, then the gyroscope can achieve compact structure and integrated actuation-sensing, but the transducers require large size to generate sufficient actuation force and produce high signal-to-noise ratios
Solution Approach 1:
The patent transitions from in-plane drive oscillation to out-of-plane drive oscillation. The piezoelectric transducer is positioned on the suspender to generate vertical displacement, which converts to rotational motion through the suspender's mechanical leverage. This dimensional change allows more effective force generation without increasing transducer footprint area.
Solution Approach 2:
The suspender acts as an intermediary element between the piezoelectric transducer and the inertial mass. The transducer generates linear displacement, and the suspender converts this into rotational oscillation of the inertial mass. This mechanical transformation allows the transducer to be smaller while still producing sufficient actuation torque.
2Measurement precision
If piezoelectric transducers are placed on suspenders to detect sense oscillation, then integrated sensing is achieved, but non-uniform bending modes and misalignment occur reducing measurement precision
Solution Approach 1:
The patent uses out-of-plane sense oscillation detected by piezoelectric transducers on the suspender. This vertical bending mode is more robust to in-plane misalignment and manufacturing variations. The transducer measures vertical displacement, which directly correlates to rotational rate through the Coriolis effect, providing more accurate measurements despite positioning tolerances.
Solution Approach 2:
The patent changes the oscillation mode from in-plane to out-of-plane, which alters the bending distribution along the suspender. This parameter change ensures more uniform strain distribution and reduces sensitivity to transducer position variations, improving measurement precision while reducing manufacturing precision requirements.
3Device complexity
If drive and sense oscillation are performed in the same plane, then device structure is simplified, but drive and sense movements become non-orthogonal causing quadrature components
Solution Approach 1:
The patent separates drive and sense oscillations into different spatial dimensions: drive oscillation occurs in the device plane (in-plane), while sense oscillation occurs perpendicular to the device plane (out-of-plane). This dimensional separation ensures orthogonality between drive and sense movements, eliminating quadrature components while maintaining relatively simple device structure.
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 arrangement enhances the sense signal strength, reduces quadrature components due to misalignment, and allows for dedicated suspenders for sensing, resulting in improved signal-to-noise ratios and reduced external vibration interference.
Implementation Method 1
At least one of the first and second suspension structures comprises one or more piezoelectric transducers configured to detect oscillating motion of the inertial mass
Implementation Method 2
A synchronization structure includes a synchronization spring coated with a piezoelectric transducer configured to drive the first and the second inertial masses into drive oscillation
Implementation Method 3
MEMS gyroscopes use the Coriolis effect to measure angular velocity. When a gyroscope containing an inertial mass in drive oscillation undergoes an angular rotation rate Ω about a secondary axis, the inertial mass is affected by the Coriolis-effect
Data Source
Figure 1~2a
Figure 2b
Figure 3
AI summary
This disclosure relates to a microelectromechanical gyroscope comprising a substrate with an inertial mass suspended from a suspension structure which allows the first inertial mass to oscillate rotationally both in the device plane and out of the device plane. The suspension structures comprises one or more suspenders coated with piezoelectric transducer structures configured to detect oscillating motion out of the device plane or in the device plane. The gyroscope also comprises a synchronization structure which includes a synchronization spring attached to the first inertial mass at a first attachment point and to the second inertial mass at a second attachment point. The synchronization spring is coated with a piezoelectric transducer structure configured to detect the oscillating motion of the suspended inertial mass out of the device plane.