Piezoelectric Gyrometer Electrode Shielding
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Solution Overview
Problem
Existing piezoelectric vibrating gyrometers face challenges in reducing undesirable electrostatic signals on Coriolis detection electrodes while maintaining satisfactory piezoelectric efficiency and low-cost manufacturing, especially when additional ribbon conductors connected to the electric ground are not feasible.
Innovation Solution
The use of ribbon conductors solely on the faces parallel to the plate, with a drive detection ribbon positioned between the drive excitation and Coriolis detection ribbons, connected to an operational amplifier for charge or current amplification, effectively acts as a ground screen to minimize electrostatic interference without additional ground-connected ribbons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If additional ribbon conductors connected to the electric ground are used to reduce electrostatic interference, then the electrostatic shielding effect is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The drive detection electrode serves as an intermediary element between the drive excitation electrode and the Coriolis detection electrode. By positioning the drive detection electrode in this intermediate location and connecting it to the inverting input of the operational amplifier (which maintains virtual ground), it acts as a shielding mediator that reduces electrostatic coupling without requiring additional ground-connected ribbon conductors
Solution Approach 2:
The drive detection electrode performs dual functions: it detects the drive mode vibration amplitude and simultaneously serves as an electrostatic shield for the Coriolis detection electrode. This self-service approach eliminates the need for separate shielding elements, reducing manufacturing complexity while maintaining shielding effectiveness
2Reliability
If electrodes are disposed side-by-side along the tines to maximize piezoelectric efficiency, then the piezoelectric coupling is improved, but the electrostatic interference between electrodes increases
Solution Approach 1:
The drive detection electrode is positioned as an intermediary between the drive excitation and Coriolis detection electrodes. Connected to the inverting input of the operational amplifier, it maintains a virtual ground potential that shields the Coriolis detection electrode from electrostatic interference while allowing close spacing for maximum piezoelectric efficiency
Solution Approach 2:
The patent replaces the mechanical/physical ground screen approach with an electronic solution using the operational amplifier's virtual ground at the inverting input. This electronic grounding mechanism provides electrostatic shielding without requiring additional physical ribbon conductors connected to the electric ground
3Object-affected harmful factors
If the drive detection electrode is connected to the inverting input of the operational amplifier, then the electrostatic shielding effect is improved, but the circuit complexity increases
Solution Approach 1:
The operational amplifier circuit serves multiple functions simultaneously: it amplifies the drive mode vibration signal for detection, maintains the virtual ground potential for electrostatic shielding, and processes the Coriolis detection signal. This multi-functionality reduces the need for separate shielding circuits, offsetting the added circuit complexity
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 significantly reduces undesirable electrostatic charges on Coriolis detection electrodes, maintaining high piezoelectric efficiency and allowing for low-cost production by preserving space for electrodes, achieving precision measurements of angular rotation rates.
Implementation Method 1
the important aspect being to obtain sufficient piezoelectric coupling between extension or compression of the longitudinal fibres of the flexurally vibrating tines and the electric field or displacement of the charges
Implementation Method 2
avoid the alternating electric potentials for excitation of the drive mode giving rise, by the electrostatic effect, to the appearance of undesirable electrical signals on the Coriolis detection electrodes
Implementation Method 3
detection of Coriolis accelerations which act on a vibrating resonator in accordance with a first useful mode referred to as the 'drive mode'
Data Source
AI summary
The Coriolis-effect gyrometer has a tuning fork having two tines, which tuning fork is formed in a plate of piezoelectric crystal and provided with electrodes composed of ribbon conductors supported solely by the faces of the tines parallel to the plate. The drive excitation and drive detection electrodes are connected to an oscillator circuit, and the Coriolis detection electrodes are connected to a detection circuit. For each of the faces parallel to the plate of each of the tines the drive detection ribbon is disposed between the drive excitation ribbon and the Coriolis detection ribbon and is connected to the inverting input of an operational amplifier, the non-inverting input of which is connected to the electric ground, said operational amplifier forming part of the oscillator circuit.