Force Detection Circuit Using Frequency Counting for High-Resolution Sensing
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Solution Overview
Problem
Conventional force detection devices face challenges with low resolution and high noise interference due to the use of analog-to-digital converters (ADCs) with higher bit resolution, especially at low signal voltages, and conventional force acquisition methods fail to accurately reflect force values due to logarithmic relationships and restrictive sensor usage.
Innovation Solution
A force detection circuit that includes an oscillator unit, comparator unit, voltage converter unit, and charge/discharge control unit, which converts force into a proportional and continuous linear variation of voltage or frequency, eliminating the need for complex ADCs and enabling accurate force measurement with high resolution and power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ADC with higher bit resolution is used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the conventional ADC (analog-to-digital converter) circuit with a frequency-based measurement system. Instead of using complex high-bit ADCs to directly convert analog force signals to digital values, the system uses a frequency modulation approach where the force signal modulates a carrier frequency, and the frequency variation is counted to obtain digital force information. This substitution of the conversion mechanism eliminates the need for complex high-resolution ADC hardware while achieving equivalent or superior measurement precision.
Solution Approach 2:
The patent transforms the measurement parameter from direct voltage amplitude (which requires high-bit ADC) to frequency variation. By measuring the frequency change of an oscillating system that is influenced by the force applied to the sensor, the system achieves high-resolution force measurement using simple frequency counting circuits instead of complex ADCs. This parameter transformation converts a difficult measurement problem into a simpler one.
2Measurement precision
If ADC with higher bit resolution is used, then measurement precision is improved, but noise interference increases
Solution Approach 1:
The patent replaces the vulnerable high-bit ADC circuit with a frequency-based measurement system that is inherently more noise-resistant. Frequency measurements are less susceptible to noise interference compared to direct voltage measurements, especially at low signal levels. The oscillating system's frequency is modulated by the force signal, and frequency counting provides robust digital output that maintains precision without amplifying noise.
3Device complexity
If conventional RC charging method is used, then device complexity is reduced, but measurement precision deteriorates due to logarithmic relationship
Solution Approach 1:
The patent changes the measurement parameter from charging time (which has a logarithmic relationship with force in RC circuits) to frequency variation. By measuring the frequency change of an oscillating system rather than the charging time of a capacitor, the system achieves a linear relationship between the measured parameter and the applied force. This eliminates the need for complex logarithmic calculations while maintaining circuit simplicity and improving measurement 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 accurate and high-resolution force measurement without the need for complex ADCs, saving power and enhancing the practicality and applicability of force detection devices, suitable for various force acquiring units.
Implementation Method 1
an oscillator unit (11), configured to output an oscillation signal as a count clock signal of a counter unit (12); and the counter unit (12), connected to the oscillator unit (11), and configured to acquire a frequency of the oscillation signal and count
Implementation Method 2
a constant current source charging unit (15), connected to the other input terminal of the comparator unit (13), and configured to supply a linearly and gradually increased comparison voltage to the comparator unit (13)
Data Source
AI summary
The present invention provides a pressure detection circuit including an oscillator unit, configured to output an oscillation signal as a count clock signal of a counter unit; and the counter unit, connected to the oscillator unit and configured to acquire a frequency of the oscillation signal and count. The pressure detection circuit further includes a comparator unit, connected to the counter unit, and configured to detect a voltage variation obtained by a pressure conversion, and send a signal to control the counter unit to count or stop counting; a voltage converter unit, connected to one input terminal of the comparator unit, and configured to supply a fixed or variable comparable voltage to the comparator unit; a constant current source charging unit, connected to the other input terminal of the comparator unit, and configured to supply a linearly and gradually increased comparison voltage to the comparator unit; a charge/discharge control unit, connected to the constant current source charging unit, and configured to control the constant current source charging unit to charge or discharge, such that the comparable voltage output by the voltage converter unit is compared to cause an output terminal of the comparator unit to enable counting of the counter unit; wherein the oscillator unit or the voltage converter unit further includes a pressure acquiring unit, as a component of the voltage converter unit or the oscillator unit, configured to convert a pressure into a variation of the comparable voltage or the frequency of the oscillation signal. The invention also provides a pressure input device pressure detection device. The invention has the technical effects of high sensitivity and resolution, power saving, and wide applicability.