Capacitive Pressure Sensor Frequency Variation for Interference Immunity
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Solution Overview
Problem
Capacitive pressure measuring devices are susceptible to interference from external signal sources, leading to resonance formation when operating at fixed frequencies, especially in environments with frequency converters.
Innovation Solution
The operating frequency of the pressure measuring device is continuously varied using a transistor circuit controlled by a microcontroller to prevent resonance formation with externally injected frequencies, achieved by altering the timing of the triangular signal's reversal points within defined time windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed operating frequency is used in the capacitive pressure measuring device, then the device structure and operation are simple, but resonance formation occurs with external signal sources leading to measurement interference
Solution Approach 1:
The patent applies the dynamics principle by continuously varying the operating frequency of the capacitive pressure measuring device instead of using a fixed frequency. The microcontroller dynamically adjusts the frequency within a defined range, ensuring that the operating frequency never matches external interfering frequencies, thus preventing resonance formation and improving measurement reliability.
Solution Approach 2:
The patent implements parameter changes by modifying the operating frequency parameter over time. The frequency is continuously changed within a specified range under microcontroller control, transforming the static frequency parameter into a dynamic one that adapts to avoid external interference, thereby resolving the contradiction between measurement accuracy and device complexity.
2Object-affected harmful factors
If the operating frequency is continuously varied to avoid resonance, then insensitivity to external signal sources is achieved, but the control mechanism becomes more complex
Solution Approach 1:
The patent uses a microcontroller as an intermediary to manage the frequency variation. The microcontroller automatically adjusts the operating frequency based on predefined parameters, shielding the user from the complexity of frequency control while effectively eliminating external signal interference through continuous frequency modulation.
Solution Approach 2:
The system implements self-service by automatically varying its own operating frequency without requiring external intervention. The microcontroller autonomously controls the frequency adjustment within the defined range, enabling the device to protect itself from resonance interference while maintaining simple operation for the user.
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 ensures that the pressure measuring device remains insensitive to external signal sources, maintaining accurate pressure measurements by introducing variability in the operating frequency, thereby avoiding resonance buildup.
Implementation Method 1
Due to the action of pressure a deformation of the membrane is caused, resulting in a change in capacitance of the measuring capacitor
Implementation Method 2
The operating frequency of the pressure measuring device is continuously varied using a transistor circuit controlled by a microcontroller to prevent resonance formation with externally injected frequencies, achieved by altering the timing of the triangular signal's reversal points within defined time windows
Data Source
AI summary
The disclosure relates to a method for operating a capacitive pressure measurement device. In order to achieve an insensitivity to external signal sources, the disclosure proposes continuously varying the working frequency of the pressure measurement device so that a resonance formation with externally injected (interfering) frequencies is avoided.