Force Detection Circuit Using Frequency Counting for High-Resolution Sensing
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Solution Overview
Problem
Existing force detection devices face challenges with low resolution and interference from noise, especially when using high-bit analog-to-digital converters (ADCs), and conventional methods fail to accurately reflect the relationship between force and sensor charging time, leading to inconvenient usage and high costs.
Innovation Solution
A force detection circuit that converts force into a variation of oscillation frequency or voltage, using an oscillator unit, comparator unit, and counter unit to achieve a proportional and continuous linear relationship between force variation and counting results, eliminating the need for complex ADCs and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-bit ADC is used to improve resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the conventional ADC-based digital conversion system with a frequency-based measurement system. The force sensor output directly modulates the oscillation frequency of an oscillator circuit, and a counter measures the frequency by counting clock cycles within a fixed gate time. This substitution eliminates the need for high-bit ADC circuits, reducing device complexity and cost while maintaining high measurement precision through frequency resolution.
Solution Approach 2:
The patent changes the measurement parameter from voltage amplitude (requiring ADC) to frequency (measurable by counter). By converting the force signal into frequency modulation, the system achieves high-resolution measurement using simple digital counting logic instead of complex analog-to-digital conversion, thereby resolving the contradiction between precision and complexity.
2Measurement precision
If high-bit ADC is used to improve resolution, then measurement precision is improved, but noise interference increases
Solution Approach 1:
The patent substitutes the voltage-based ADC measurement system with a frequency-based counter measurement system. Frequency measurements are inherently more noise-resistant because they depend on timing intervals rather than voltage levels. The counter counts complete oscillation cycles within a gate period, making the measurement robust against voltage noise and interference, thus achieving high resolution without susceptibility to 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 replaces the RC charging time measurement method with a frequency counting method. Instead of measuring the time to charge a capacitor through a resistor (which creates a logarithmic relationship), the system uses a force sensor to directly modulate oscillator frequency, and a counter measures the frequency by counting cycles in a fixed gate time. This substitution establishes a direct linear relationship between force and measurement output, improving precision while keeping the circuit relatively simple.
4Measurement precision
If high-bit ADC is used to improve resolution, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent substitutes the power-hungry ADC circuit with a low-power frequency counting system. The oscillator consumes minimal power, and the counter operates by simple digital logic that counts clock cycles during a gate period. This eliminates the need for high-resolution ADC conversion, which is inherently power-intensive, thereby achieving high measurement precision with significantly reduced power consumption.
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 force detection with high resolution and power savings, applicable to various force-accepting units, achieving high sensitivity and effectiveness with wide applicability and practicality.
Implementation Method 1
a force acquiring unit, as a component of the oscillator unit, configured to acquire a force variation amount and convert a force into a variation of a frequency of the oscillation signal
Implementation Method 2
the second resistor R1 uses a resistive force sensor as the force acquiring unit of the oscillator unit
Implementation Method 3
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
Data Source
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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.