Current Output Calibration Using Reference Voltages for Drift
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Solution Overview
Problem
Current output modules face errors due to ambient temperature changes and analog circuit drift, leading to inaccuracies in current output, which are not easily calibrated after shipment, necessitating manual calibration at specific temperatures.
Innovation Solution
Incorporating a current output module with an AD conversion circuit, a reference voltage generator, and a controller that uses reference voltages to automatically calibrate the AD conversion circuit and current output section, allowing for continuous calibration post-shipment by converting reference voltages into digital values and applying correction formulas to eliminate conversion errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration is performed at specific temperatures during manufacturing, then initial accuracy is improved, but the device cannot adapt to temperature changes after shipment
Solution Approach 1:
The current output module performs automatic self-calibration using an integrated reference voltage generator and AD conversion circuit. The system automatically detects conversion errors by comparing reference voltage values and applies correction formulas to calibrate the analog circuit, eliminating the need for external manual calibration services after shipment.
Solution Approach 2:
The system performs preliminary calibration actions automatically by continuously monitoring the AD conversion circuit's performance against known reference voltages. Correction formulas are pre-calculated and applied in advance to compensate for temperature drift and analog circuit errors before they affect current output accuracy.
2Adaptability or versatility
If automatic calibration is implemented post-shipment, then temperature adaptability is improved, but device complexity increases
Solution Approach 1:
The AD conversion circuit serves multiple functions: it converts detection voltages to digital values for current measurement and simultaneously converts reference voltages to digital values for calibration purposes. The reference voltage generator provides both a stable reference for conversion error detection and a means to verify analog circuit performance, reducing the need for separate dedicated calibration components.
Solution Approach 2:
The reference voltage acts as an intermediary standard that mediates between the analog circuit's output and the digital measurement system. By introducing known reference voltage values that are converted to digital values, the system can calculate conversion errors and apply correction formulas without requiring direct access to external calibration equipment.
3Measurement precision
If the AD conversion circuit is calibrated using reference voltages, then conversion error is reduced, but calibration time increases
Solution Approach 1:
The calibration process is designed to be continuous and automatic, occurring in the background during normal operation. The system continuously converts reference voltages to digital values, calculates conversion errors, and applies correction formulas without requiring the device to be taken offline or subjected to lengthy calibration procedures, thus maintaining continuous useful action.
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
Enables automatic calibration of the analog circuit and current output section, ensuring accurate and stable current output even after shipment, reducing the need for manual calibration and maintaining performance across varying temperatures.
Implementation Method 1
an AD conversion circuit configured to convert a detection voltage, which is a voltage according to the current output from the current output section, into a digital value
Implementation Method 2
a reference voltage generator configured to generate a plurality of reference voltages
Implementation Method 3
a corrector configured to calibrate the AD conversion circuit on the basis of each digital value obtained by conversion of the plurality of reference voltages
Implementation Method 4
a reference resistor configured to convert the current output from the current output section into the detection voltage
Data Source
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AI summary
A current output module includes a current output section configured to output a current, an AD conversion circuit configured to convert a detection voltage, which is a voltage according to the current output from the current output section, into a digital value, a controller configured to control a current output from the current output section on the basis of the digital value of the detection voltage output from the AD conversion circuit, and a reference voltage generator configured to generate a plurality of reference voltages. The controller includes a processor configured to cause the AD conversion circuit to convert each of the plurality of reference voltages into a digital value, and a corrector configured to calibrate the AD conversion circuit on the basis of each digital value obtained by conversion of the plurality of reference voltages.