Analog Unit Calibration Using Factory and User Correction Values
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Solution Overview
Problem
Existing methods for calibrating analog units require extensive man-hours and suffer from uneven calibration accuracy, especially when analog signals and ADC codes are nonlinearly correlated, and incur cost increases due to the need for data tables and comparator circuits to correct for temperature drift.
Innovation Solution
An analog unit that includes a converter circuit, storage for factory-set values, and a user-set value calculating part to determine user-set values based on one user-measured value, allowing calibration without increasing man-hours and reducing cost by using factory-set and user-set values to adjust output values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-point measurement method is used to obtain offset value and gain value, then calibration can be performed, but a large number of man-hours are required
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in a correction value table during the manufacturing process. Instead of performing two-point measurements during calibration, the system uses pre-computed correction values that account for nonlinearity, thereby eliminating the time-consuming measurement process while maintaining calibration accuracy.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing correction values in a correction value table during the manufacturing process. Instead of performing two-point measurements during calibration, the system uses pre-computed correction values that account for nonlinearity, thereby eliminating the time-consuming measurement process while maintaining calibration accuracy.
2Measurement precision
If three-point measurement method is used to divide range into regions 1 and 2, then calibration accuracy may be improved, but a large number of man-hours are required and greater unevenness in calibration accuracy occurs
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in a correction value table during the manufacturing process. Instead of performing three-point measurements and dividing into regions, the system uses pre-computed correction values that inherently account for nonlinearity across the entire range, thereby eliminating the time-consuming measurement process while maintaining uniform calibration accuracy.
Solution Approach 2:
The patent applies homogeneity by providing uniform correction resolution across the entire input range through the correction value table. Unlike the three-point method that creates different correction characteristics in different regions, this approach ensures consistent correction quality throughout the full range, eliminating regional unevenness in calibration accuracy.
3Reliability
If data table and comparator circuit are added to correct output value for temperature drift, then temperature drift correction is achieved, but cost increases
Solution Approach 1:
The patent applies merging by combining the temperature drift correction functionality with the existing correction value table. Instead of adding a separate comparator circuit and data table infrastructure, the system integrates temperature compensation into the existing correction mechanism, thereby achieving temperature drift correction without additional hardware cost.
Solution Approach 2:
The patent applies self-service by enabling the correction value table to automatically provide temperature-dependent correction values without requiring external comparator circuits. The system uses the stored correction values directly to compensate for temperature drift, eliminating the need for additional active components and reducing overall device complexity and cost.
Data Source
AI summary
An ADC code given in response to input of an analog input value to an A/D converter circuit is measured at a site where an A/D converter unit is used to measure a user-measured value. A user-set value calculating part calculates a user offset value and a user gain value on the basis of one user-measured value, a factory offset value, and a factory gain value, and stores the calculated user offset value and the user gain value in a nonvolatile memory.