Gas Flow Rate Measuring Apparatus with Variable Resolution Correction
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Solution Overview
Problem
Existing gas flow rate measuring apparatuses face challenges in achieving high accuracy across the entire flow rate range due to temperature-dependent errors, which are exacerbated by the need for increased data points in correction tables, leading to higher costs and slower arithmetic operations.
Innovation Solution
The apparatus incorporates a gas flow rate detection circuit, a gas temperature detection element, and a substrate temperature detection element, using signal conversion means to correct characteristics of the gas flow rate detection signal based on temperature detection signals, employing coordinate conversion tables to improve resolution at characteristic bends without increasing the number of data points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of data points in the correction table is increased to improve correction accuracy, then the correction accuracy improves, but the arithmetic operation time increases and processing speed decreases
Solution Approach 1:
The correction table data area is divided into multiple regions (first correction table data area and second correction table data area) based on flow rate ranges. Each region stores correction data with different resolutions, allowing the system to use appropriate data density for each operating condition without uniformly increasing the total data size.
Solution Approach 2:
Different regions of the correction table are assigned different data resolutions. The first correction table data area uses a first resolution while the second correction table data area uses a second resolution. This local differentiation allows high accuracy where needed while maintaining fast processing in other regions.
2Measurement precision
If the number of data points in the correction table is increased to improve correction accuracy, then the correction accuracy improves, but the cost of the arithmetic operation circuit increases
Solution Approach 1:
The correction table is segmented into multiple data areas with different resolutions. This segmentation allows the circuit to maintain a compact overall structure while providing high-resolution correction data only in specific regions where it is most needed, rather than uniformly increasing the circuit scale throughout.
Solution Approach 2:
High-resolution correction data is provided locally in the first correction table data area where it is most beneficial, while other regions use lower resolution data. This local quality differentiation improves correction accuracy in critical regions without proportionally increasing the overall circuit complexity and cost.
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 enhances the accuracy of flow rate signal correction, reducing errors and maintaining operational efficiency while minimizing the need for extensive data storage and arithmetic processing.
Implementation Method 1
a gas flow rate detection circuit configured to detect a current flowing through at least one resistive element disposed in a gas flow path, or a voltage generated in response to the current
Implementation Method 2
a gas temperature detection element configured to detect a temperature of the gas in the gas flow path
Implementation Method 3
a substrate temperature detection element configured to detect a temperature of a substrate provided in the inside of an integrated circuit
Data Source
AI summary
A gas flow rate measuring apparatus including a gas flow rate detection circuit configured to output a first analog signal of a gas flow rate of a gas; a gas temperature detection element configured to output a second analog signal of a temperature of the gas or a temperature of an integrated circuit; analog-to-digital converters for converting the analog signals into respective digital signals; a digital signal correction device comprising a map table and configured to correct a characteristic bend of the first digital signal based on the map table and the second digital signal, wherein the map table comprises correction constants arranged as lattice points, wherein a first number of lattice points in a first region of the characteristic bend of the gas flow rate signal is larger than a second number of lattice points of a second region outside the first region of the characteristic bend.