Resistive Sensor Circuit for Stray Capacitance Reduction
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Solution Overview
Problem
Conventional electronic circuits for measuring physical parameters like acceleration or pressure face issues with stray capacitances, non-linearities, reduced sensitivity, and slow signal processing due to capacitive sensors, which result in erroneous measurements and prolonged cycle times.
Innovation Solution
A method utilizing an electronic resistive sensor circuit with a resistive divider and an amplifier-comparator, where the connection node of the resistors is connected to a moving mass, allowing for digital signal processing and reducing the effects of stray capacitances through controlled polarization phases, enabling faster and more accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive sensor is used for measurement, then the measurement can be made along one direction of motion, but stray capacitances are added which create non-linearities and reduce sensitivity
Solution Approach 1:
The patent replaces the capacitive sensing mechanism with a resistive sensing mechanism. Instead of measuring capacitance changes in a capacitive sensor, the invention uses a resistive sensor with a movable contact that slides along a resistive track, converting mechanical displacement into electrical resistance changes. This substitution eliminates the stray capacitance problem inherent in capacitive sensors while maintaining the ability to measure physical parameters accurately.
Solution Approach 2:
The patent changes the measurement parameter from capacitance to resistance. By using a resistive divider configuration where the movable contact divides the resistive track into two segments, the system measures resistance ratios instead of capacitance values. This parameter change fundamentally eliminates stray capacitance effects since resistive measurements are not affected by parasitic capacitances in the same way capacitive measurements are.
2Adaptability or versatility
If digital-to-analogue converter is used with switching unit, then measurement voltage can be provided to sensor electrodes, but four phases must be provided per measurement cycle which slows down signal supply
Solution Approach 1:
The patent replaces the capacitive sensor with a resistive sensor that uses a simple voltage divider configuration. The movable contact on the resistive track directly provides an analog output voltage proportional to its position, eliminating the need for complex digital-to-analogue converters and multi-phase switching sequences. This substitution dramatically simplifies the measurement cycle and increases measurement speed.
Solution Approach 2:
The patent extracts and removes the unnecessary digital-to-analogue converter and complex switching unit from the measurement system. By using a direct resistive voltage divider configuration, the system obtains analog measurement signals without requiring DAC conversion or multi-phase control sequences, thereby eliminating the bottleneck that slowed down signal supply in capacitive sensor systems.
3Measurement precision
If capacitive sensor with moving electrode is used, then capacitance value varies with electrode movement, but the analogue output signal requires complex electronic interface which adds more stray capacitances
Solution Approach 1:
The patent replaces the capacitive sensor with a resistive sensor that has a movable contact sliding along a resistive track. This substitution changes the sensing mechanism from capacitive to resistive, eliminating the need for complex electronic interfaces designed for capacitive sensors. The resistive voltage divider configuration provides a simple, direct analog output that can be read by standard voltage-measuring circuits without adding parasitic capacitances.
Solution Approach 2:
The patent creates a simplified version of the sensor output by using a resistive voltage divider that directly replicates the position information as a voltage signal. Instead of using a complex capacitive interface that requires specialized electronics, the resistive configuration provides a direct voltage copy of the mechanical position that can be measured by simple voltage-divider circuits, reducing overall system 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 approach allows for rapid digital measurement signal generation, reduces noise and offset effects, and enhances measurement speed by completing each cycle in two phases, improving sensitivity and responsiveness with a self-adaptive algorithm for dynamic adjustments.
Implementation Method 1
electronic resistive sensor circuit with a resistive divider with at least two resistors mounted in series, wherein a connection node of the two resistors is connected to a moving mass
Implementation Method 2
connection node of the two resistors is connected to a moving mass, which is elastically retained in a fixed structure of the sensor, and to a first input of an amplifier-comparator, a second input of the amplifier-comparator receiving a reference voltage
Implementation Method 3
a digital-to-analogue converter capable of providing a measurement voltage to a free end of the first resistor or to a free end of the second resistor via a switching unit
Implementation Method 4
connection node of the two resistors is connected to a moving mass, which is elastically retained in a fixed structure of the sensor
Data Source
AI summary
The physical parameter measurement method is performed using an electronic circuit (1) with a resistive sensor (2). The resistive sensor includes two resistors (R1, R2) mounted in series, whose connection node connected to a moving mass (M), is connected to a first input of an amplifier-comparator (3). A second input of the amplifier-comparator receives a reference voltage. One output of the amplifier-comparator is connected to a logic unit (4), which provides a digital output signal (OUT). A digital-to-analog converter (5) provides a measurement voltage (Vdac), as a function of a digital signal provided by the logic unit, to the first resistor (R1) in a first phase of a measurement cycle, whereas the second resistor (R2) is polarized by a polarization voltage, and to the second resistor in a second phase, whereas the first resistor is polarized by a polarization voltage via a switching unit.