Current Output Module Self-Calibration for Drift-Accurate Control

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Solution Overview

Problem

Current output modules face errors in current output due to ambient temperature changes and analog circuit drift over time, requiring post-shipment calibration to maintain accurate current control, which is often manual and inefficient.

Innovation Solution

Incorporating a reference voltage generator and AD conversion circuit that converts reference voltages into digital values, allowing for automatic calibration of both the AD conversion circuit and current output section, enabling continuous correction and reducing the need for pre-shipment calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual calibration is performed before shipping, then initial accuracy is achieved, but post-shipment drift due to temperature changes and aging cannot be corrected

Engineering Contradiction:

Improvecurrent output accuracyVSAvoidcalibration frequency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary calibration actions automatically at predetermined intervals after shipment by switching the switching section to connect the reference voltage generator to the AD conversion circuit, eliminating the need for repeated manual calibration interventions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback control by comparing the digital value from the AD conversion circuit with the target value, and the controller adjusts the current output section to maintain accurate current output despite drift from temperature changes or aging

Inventive Principle:

Principle #23Feedback

2Reliability

If automatic calibration is implemented, then post-shipment accuracy is maintained, but device complexity increases

Engineering Contradiction:

Improvecurrent output accuracyVSAvoidcircuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The switching section serves multiple functions: it switches between the detection voltage from the current output section and the reference voltage from the reference voltage generator, allowing a single component to handle both operational measurement and calibration functions

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The reference voltage generator acts as an intermediary standard that provides known voltage values for calibration, enabling the system to self-correct without external intervention while maintaining simplicity through a dedicated calibration path

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If pre-shipment calibration is reduced, then manufacturing efficiency improves, but post-shipment calibration capability is needed

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidcalibration system

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The system performs self-calibration automatically after shipment by using its own reference voltage generator and switching section to recalibrate the AD conversion circuit at predetermined intervals, eliminating dependency on external manual calibration processes

Inventive Principle:

Principle #25Self-service

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 after shipment, ensuring consistent current output and reducing the workload associated with pre-shipment calibration, while maintaining accurate control over output current levels despite temperature changes.

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

Methodology Applied

Scientific EffectAnalog-to-Digital Conversion:

Implementation Method 2

a reference voltage generator configured to generate a plurality of reference voltages

Methodology Applied

Scientific EffectVoltage Generation:

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

Methodology Applied

Scientific EffectCalibration:

Data Source

PatentUS11876529B2Current output module

Publication Date: 2024.01.16 YOKOGAWA ELECTRIC CORP

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.