Variable Current Source for High-Resolution Resistance Sensing
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Solution Overview
Problem
Existing resistance sensing systems face a loss in resolution when attempting to cover a wide range of resistance values, as they often require different input circuitry for various sensor ranges, leading to suboptimal performance across the full scale of an analog-to-digital converter.
Innovation Solution
A processor-controlled system that uses a variable current source and analog-to-digital converter to maximize resolution by adjusting current levels through a digital-to-analog converter, allowing for precise determination of resistance values across a wide range without compromising resolution, utilizing algorithms and data structures to optimize accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single circuit is used to sense a wide range of resistance values (e.g., 0-1000 and 0-2000 ohm), then the device complexity is reduced, but the measurement precision is lost because only half of the full scale range of the analog to digital converter is utilized
Solution Approach 1:
The patent implements a variable current source that dynamically adjusts its output current based on the sensed resistance value. The controller modifies the current level in real-time to match the resistance range being measured, ensuring the analog-to-digital converter always operates within its optimal full-scale range. This dynamic adjustment resolves the contradiction by maintaining high measurement precision across a wide resistance range without requiring multiple static circuits.
Solution Approach 2:
The system changes the electrical parameter (current) being supplied to the sensor based on the resistance value detected. By adjusting the current parameter dynamically, the system optimizes the voltage output for different resistance ranges, thereby maximizing the utilization of the analog-to-digital converter's full scale range and maintaining high resolution across all resistance values.
2Measurement precision
If different input circuitry is used for each sensor range, then the measurement precision is maintained, but the device complexity increases due to expanded circuitry requirements
Solution Approach 1:
The patent creates a universal sensing circuit that can handle multiple sensor ranges (e.g., 0-1000 ohm, 0-2000 ohm, and beyond) through a single integrated design. The variable current source and controller work together to adapt the circuit's behavior to different resistance ranges, eliminating the need for separate input circuitry for each sensor type while maintaining high measurement precision across all ranges.
Solution Approach 2:
The system employs feedback control where the controller continuously monitors the resistance value and adjusts the current source accordingly. This feedback mechanism allows a single circuit to automatically adapt to different sensor ranges, maintaining optimal measurement precision without requiring manual switching or multiple dedicated circuits for each range.
3Adaptability or versatility
If hardware switches are employed to select various components, then the adaptability to different sensor types is improved, but the ease of operation deteriorates due to manual intervention requirements
Solution Approach 1:
The system performs automatic range selection and circuit adaptation without requiring manual intervention. The controller autonomously detects the sensor type and resistance range, then automatically adjusts the current source and circuit configuration accordingly. This self-service capability maintains high adaptability to different sensor types while completely eliminating the need for manual switching or user intervention.
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 enables accurate and high-resolution sensing of resistance values across a wide range, maintaining optimal performance by dynamically adjusting current settings based on sensed voltage, thereby enhancing the system's ability to handle diverse resistance types without loss of resolution.
Implementation Method 1
A processor-controlled system that uses a variable current source and analog-to-digital converter to maximize resolution by adjusting current levels through a digital-to-analog converter
Implementation Method 2
The voltage is converted into a digital value via an analog-to-digital (A/D) converter that is processed by a controller
Implementation Method 3
A resistance value is changed in a variable resistor and the current passing through that resistance is converted to a voltage
Data Source
Figure 1
Figure 2
Figure 3~4b
AI summary
An approach for maximizing the resolution of a resistance sensor with a variable current source.