Force Sensor Charge Storage Circuit for Stable Pulse Measurement
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Solution Overview
Problem
Conventional force measurement methods and sensors, particularly piezoelectric sensors, face challenges in meeting automotive manufacturer requirements due to high cost, mechanical deformation, rapid signal decay, and sensitivity to mechanical disturbances, necessitating complex and expensive electronics for accurate data processing.
Innovation Solution
A method and device utilizing a charge amplifier and a current mirror to store voltage values from a force sensor in a storage capacitor, preventing charge dissipation and maintaining signal level, allowing for longer evaluation times and temperature compensation, enabling accurate force measurement through a comparator circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If piezoelectric sensors are used for force measurement, then sensitivity and mechanical deformation resistance are improved, but signal stability and measurement precision deteriorate due to rapid charge dissipation
Solution Approach 1:
The patent introduces an intermediary capacitor to store the charge signal from the piezoelectric sensor, preventing direct charge dissipation. This capacitor acts as a mediator between the sensor and the measurement system, maintaining signal stability over extended periods while preserving the high sensitivity of piezoelectric sensors.
Solution Approach 2:
The patent replaces complex mechanical signal conditioning circuits with an electrical charge storage mechanism using a capacitor. This substitution simplifies the system while maintaining measurement precision, avoiding the need for complex electronic signal processing that would be required to handle rapidly decaying piezoelectric signals.
2Measurement precision
If conventional charge amplifiers are used, then force signal amplification is achieved, but device complexity and cost increase due to high-precision electronic requirements
Solution Approach 1:
The patent extracts the essential function of charge amplification from complex electronic circuits and implements it through a simple capacitor-based charge storage mechanism. This extraction eliminates the need for high-precision operational amplifiers and complex signal conditioning electronics, significantly reducing device complexity while maintaining measurement accuracy.
Solution Approach 2:
The patent uses a simple, low-cost capacitor instead of expensive, high-precision electronic components. The capacitor is a straightforward electrical component that can be easily manufactured and replaced, providing the same functional benefit as complex charge amplifiers but at a fraction of the cost and complexity.
3Speed
If high sampling rates are used for pulse evaluation, then measurement speed is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent performs preliminary charge storage in the capacitor before any measurement or evaluation takes place. By pre-storing the charge signal, the system eliminates the need for high-speed sampling during the measurement process, allowing for slower, simpler data acquisition while maintaining measurement speed and accuracy.
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 provides stable and accurate force measurement by maintaining signal levels and reducing temperature influence, facilitating precise actuation and release evaluation, suitable for automotive applications.
Implementation Method 1
Sensing a force application with almost no mechanical deformation is possible using a piezoelectric sensor. Piezoelectric sensors are based on the principle of electrical charge displacement during mechanical deformation.
Implementation Method 2
Applying a force to the piezoelectric element generates an electrical charge proportional to the force. This charge is then converted into a voltage by an integrator circuit.
Implementation Method 3
storing a voltage value derived from the voltage pulse in a storage capacitor using a current mirror... the voltage level of the output of the integrator or the charge amplifier is stored in a capacitor using a current mirror, thus preventing charge dissipation
Data Source
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AI summary
The present invention relates to a method and a device for measuring a force. The invention also relates to an input device that uses such a device or such a method. In a first step, a voltage pulse resulting from a force acting on a force sensor is generated by means of a charge amplifier (S1). Using this voltage pulse, a trigger pulse can be generated by means of a comparator circuit (S2). A voltage value derived from the voltage pulse is then stored in a storage capacitor by means of a current mirror (S3). The resulting capacitor voltage can be evaluated by means of an evaluation unit (S4).