Electromechanical Sensor Feedback Circuit for Spring Softening Reduction
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Solution Overview
Problem
Conventional electromechanical sensor technologies are susceptible to changes in sensitivity due to die stress, assembly variations, and operating conditions, leading to a 'spring softening' effect that alters the resonant frequency and gain of the sensor, which is exacerbated by charge-to-voltage architectures maintaining constant voltage across capacitive sense elements.
Innovation Solution
The application of a positive feedback voltage using a voltage-to-voltage converter to maintain a constant charge at the sense electrode, reducing sensitivity by coupling a defined feedback capacitance to the sense electrode, thereby minimizing the spring softening effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a charge-to-voltage (C2V) architecture is used to maintain constant voltage across the sense gap, then the sensor can operate with stable bias conditions, but the spring softening effect is increased
Solution Approach 1:
The patent implements a feedback mechanism where the output voltage from the voltage-to-voltage converter is fed back to the sense electrode through a feedback capacitor. This feedback loop dynamically adjusts the voltage at the sense electrode to compensate for spring softening effects, maintaining stable sensor operation without the harmful side effects of conventional C2V architectures.
Solution Approach 2:
The patent changes the operating parameter from constant voltage (C2V architecture) to constant charge (voltage-to-voltage converter with feedback). By switching from voltage-mode operation to charge-mode operation with feedback, the system eliminates spring softening while maintaining operational stability.
2Ease of manufacture
If conventional sensor technologies are used, then the device can be manufactured with standard processes, but sensitivity changes occur due to die stress and assembly variations
Solution Approach 1:
The feedback capacitor connects the converter output back to the sense electrode, creating a closed-loop system that compensates for sensitivity changes caused by die stress and assembly variations. This feedback mechanism maintains measurement precision while using standard manufacturing processes.
3Reliability
If a voltage-to-voltage converter with feedback capacitance is used to maintain constant charge, then spring softening is reduced, but the device complexity increases
Solution Approach 1:
The feedback capacitor acts as an intermediary element that simplifies the overall system architecture. By using the capacitor to store and transfer charge information, the complex spring softening compensation function is achieved through a simple passive component rather than complex active circuitry.
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 approach effectively reduces the sensitivity of electromechanical sensors like gyroscope and accelerometers to variations in mechanical-to-electrical gain, eliminating the spring softening effect and maintaining stability over time.
Implementation Method 1
maintain a constant charge at the sense electrode, reducing sensitivity by coupling a defined feedback capacitance to the sense electrode
Data Source
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AI summary
Reducing a sensitivity of an electromechanical sensor is presented herein. The electromechanical sensor comprises a sensitivity with respect to a variation of a mechanical-to-electrical gain of a sense element of the electromechanical sensor; and a voltage-to-voltage converter component that minimizes the sensitivity by coupling, via a defined feedback capacitance, a positive feedback voltage to a sense electrode of the sense element - the sense element electrically coupled to an input of the voltage-to-voltage converter component. In one example, the voltage-to-voltage converter component minimizes the sensitivity by maintaining, via the defined feedback capacitance, a constant charge at the sense electrode. In another example, the electromechanical sensor comprises a capacitive sense element comprising a first node comprising the sense electrode. Further, a bias voltage component can apply a bias voltage to a second node of the electromechanical sensor. In yet another example, the electromechanical sensor comprises a piezoelectric sense element.