MEMS Gyro Phase Delay Feedback for Sensitivity
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Solution Overview
Problem
Downsizing of gyro detection apparatuses leads to reduced detection sensitivity and noise suppression challenges due to decreased Coriolis force and amplitude, necessitating improved methods for stabilizing self-oscillation and enhancing signal-to-noise ratio (S/N) in angular velocity sensing.
Innovation Solution
A detection apparatus comprising a cantilever vibration gyro with a piezoelectric element, bias applying means, adding means, phase delaying means, and amplitude controlling means, which compensates for parasitic capacitance by phase delaying detected signals between 45° and 90°, and optionally uses differential amplification and synchronous detection to improve sensitivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the gyro detection apparatus is downsized using MEMS technology, then the device size and manufacturing cost are reduced, but the detection sensitivity deteriorates due to decreased Coriolis force and vibration amplitude
Solution Approach 1:
The patent applies parameter changes by modifying the phase of the drive signal through phase delaying means. Specifically, the detected signal is delayed by a phase within a predetermined range (45° to 90°) to compensate for parasitic capacitance effects, thereby stabilizing self-oscillation and improving detection sensitivity without changing the physical size of the MEMS device
Solution Approach 2:
The patent implements feedback by using the detected signal from the Coriolis force measurement to generate a phase-delayed drive signal that is fed back to the drive electrode. This feedback loop stabilizes the self-oscillation of the cantilever vibrator, maintaining consistent vibration amplitude and improving signal-to-noise ratio despite the downsized structure
2Volume of moving object
If the power supply voltage is decreased to accommodate downsizing, then the device can be further miniaturized, but the vibration amplitude becomes small and detection sensitivity deteriorates
Solution Approach 1:
The patent changes the phase parameter of the drive signal rather than increasing voltage amplitude. By introducing a phase delay of 45° to 90° to the detected signal and using it as the drive signal, the system achieves stable self-oscillation that maintains sufficient vibration amplitude even with low power supply voltage, thereby preserving detection sensitivity in miniaturized devices
3Device complexity
If conventional signal processing is used without phase delay compensation, then the device structure remains simple, but parasitic capacitance degrades self-oscillation stability and increases noise
Solution Approach 1:
The patent introduces phase delaying means as an intermediary component between the detection electrode and the drive electrode. This intermediary delays the phase of the detected signal by 45° to 90° before feeding it back as the drive signal, thereby compensating for parasitic capacitance effects and stabilizing self-oscillation without significantly increasing device complexity
Solution Approach 2:
The patent modifies the phase parameter of the drive signal to compensate for parasitic capacitance. By delaying the phase within the specific range of 45° to 90°, the system achieves stable self-oscillation and reduced noise, improving reliability 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
The solution stabilizes self-oscillation, suppresses noise, and achieves a high S/N ratio, enabling more accurate angular velocity detection and improved performance in compact electronic devices.
Implementation Method 1
a cantilever vibration gyro including a piezoelectric element which has a first side and a second side, the first side provided with a drive electrode and a pair of detection electrodes
Implementation Method 2
detecting Coriolis force generated due to an influence of the angular velocity by a piezoelectric element
Implementation Method 3
The bias applying means applies a bias voltage to the pair of detection electrodes
Data Source
AI summary
A detection apparatus is provided which includes a cantilever vibration gyro including a piezoelectric element having a first side provided with a drive electrode and a pair of detection electrodes sandwiching the drive electrode with predetermined gaps therebetween and a second side opposed to the first side and provided with a common electrode, which vibrates by a drive signal input between the drive electrode and the common electrode and generates a pair of detected signals corresponding to Coriolis force from the detection electrodes. The detection apparatus also includes a bias applying section for applying a bias voltage to the detection electrodes, an adding section adding the pair of detected signals, a first phase delay section delaying a phase of the detected signal obtained by the addition by a range larger than 45° and smaller than 90°, and an amplitude control section controlling the delayed detected signal to a predetermined voltage amplitude to output as the drive signal.