Inertial Sensor Compensation Conductors for Disturbing Current
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Solution Overview
Problem
Piezoelectric inertial sensors experience disturbances in measured current due to interfering currents generated by conductive tracks during acceleration, leading to saturation and malfunction of the sensor electronics.
Innovation Solution
The introduction of compensation branches that counteract the disturbing currents by collecting opposite charges from conductive tracks, with these branches extending parallel and nested to minimize the disturbance, and reducing the width of conductive tracks to less than 50 μm to further reduce the initial disturbing current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive tracks are used in the excitation circuit, then electrical connection is established, but disturbing current is generated that saturates the electronics and causes malfunction
Solution Approach 1:
A compensation conductor is introduced as an intermediary element between the disturbing conductive track and the measurement circuit. This compensation conductor carries a compensating current that is opposite in phase to the disturbing current, thereby canceling out the harmful effect and preventing saturation of the electronics.
Solution Approach 2:
The invention converts the harmful disturbing current into a beneficial effect by using the same conductive track that generates the disturbance as part of the compensation mechanism. The compensation conductor is routed to collect charges of opposite sign from the same structural elements, transforming the harmful charge separation into a useful compensating signal.
2Measurement precision
If compensation branches are added to reduce disturbing current, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The compensation conductor serves multiple functions simultaneously: it acts as an electrical connection path, a charge collection element, and a compensating signal source. By making the compensation conductor multi-functional, the invention reduces measurement precision improvement while minimizing the increase in device complexity.
3Object-generated harmful factors
If the width of conductive tracks is reduced to less than 50 μm, then disturbing current is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention changes the critical parameter from track width (which requires high manufacturing precision) to track length and routing configuration (which are easier to control). By optimizing the length and path of the compensation conductor rather than relying solely on narrow track widths, the disturbing current is reduced while maintaining feasible manufacturing precision requirements.
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 solution effectively reduces the disturbing current, allowing for more accurate measurement of vibration frequency changes and preventing sensor malfunction by partially canceling out the interfering charges, thus enhancing the reliability of the inertial sensor.
Implementation Method 1
The excitation circuit is supplied with an alternating current causing, by a piezoelectric effect, the setting in vibration of the vibrating member according to a natural frequency of vibration of this vibrating element
Implementation Method 2
the compensation branch receives electrical charges of opposite sign to those received by the corresponding disturbing conductive track portion so that the charges collected by the compensation branch at least partially cancel the charges collected by the corresponding disturbing conductive track portion
Data Source
Figure 1~2
AI summary
The inertial sensor includes a piezoelectric plate in which is delimited a vibrating member carrying excitation electrodes connected to an excitation circuit comprising conductive tracks carried by the piezoelectric plate, the excitation circuit comprising a portion of a disturbance circuit (13) in which the excitation circuit includes compensation branches (14) associated with corresponding portions of disturbance conductive tracks (15), each compensation branch having an end connected to the corresponding portion of disturbance conductive track and extending on a side opposite to the corresponding portion of disturbance conductive track with respect to the median plane (M).