Compact Gas Analyzer Filter Wheel Cross-Talk Reduction
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Solution Overview
Problem
Existing gas analyzers face challenges in accurately analyzing multigas mixtures, particularly in main stream applications, due to issues with filter wheel design, leading to cross-talk and impaired signal-to-noise ratios, which complicates the analysis of multiple gases like carbon dioxide, oxygen, nitrous oxide, and anesthetic agents.
Innovation Solution
A compact gas analyzing system that uses a filter component with filters of different transmission wavelength ranges, where the signal processing circuitry identifies peaks in the measurement signal during light periods, estimating intensity without requiring a traditional reference or null intensity, allowing for smaller filter wheels and improved accuracy by reducing the spacing between filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the filter wheel is made smaller to reduce device size, then the device becomes more compact and suitable for main stream applications, but the spacing between filters must be reduced which causes cross-talk between filters and deteriorates measurement accuracy
Solution Approach 1:
The patent extracts the reference intensity measurement from the traditional filter wheel operation by introducing a separate reference channel with its own detector. This reference channel continuously monitors the light source intensity without being affected by filter positioning, allowing the filter wheel to be made smaller without compromising measurement accuracy. The reference intensity is subtracted from the measured signal to eliminate effects of source intensity variations and filter imperfections.
Solution Approach 2:
The patent introduces a reference channel as an intermediary element that mediates between the light source and the measurement process. This reference channel provides a stable reference signal that compensates for variations in the light source intensity and filter characteristics, enabling accurate gas concentration measurements even when the filter wheel is compact with reduced spacing between filters.
2Adaptability or versatility
If more filters are added to analyze more gases, then the multigas analysis capability is improved, but the filter wheel size and complexity increase making it difficult to maintain small spacing without cross-talk
Solution Approach 1:
The patent segments the measurement system into multiple independent detection channels, each with its own detector and reference channel. This segmentation allows each channel to operate independently with simplified filter requirements, enabling multigas analysis capability while keeping individual filter wheel sections compact and reducing overall system complexity.
Solution Approach 2:
The patent implements a universal reference channel that serves all measurement channels simultaneously. This reference channel provides a common reference signal for compensating intensity variations across all gas analysis channels, eliminating the need for separate reference mechanisms for each gas and thereby reducing overall device complexity while maintaining versatile multigas analysis capability.
3Volume of moving object
If the spacing between filters is reduced to maintain small filter wheel size, then cross-talk between filters occurs which impairs the signal to noise ratio and deteriorates measurement reliability
Solution Approach 1:
The patent implements a feedback mechanism where the reference channel continuously monitors the light source intensity and provides a reference signal that is fed back to compensate for intensity variations in the measurement channels. This feedback loop maintains measurement reliability by correcting for source fluctuations and filter imperfections, allowing the system to operate reliably even with reduced filter spacing in a compact filter wheel.
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 a small, accurate, and reliable multigas analyzer that can be adapted for both main stream and side stream configurations, improving measurement accuracy and reliability by utilizing light periods for peak intensity estimation, thus overcoming the limitations of traditional designs.
Implementation Method 1
The light from an IR-emitter passes through the gas mixture of a measuring chamber and is filtered by a narrow-band optical bandpass filter. The gases absorb infrared light at gas specific wavelengths and during the passage through the gas mixture, the gases in the mixture hence absorb some of the light.
Implementation Method 2
the light from an IR-emitter passes through the gas mixture of a measuring chamber and is filtered by a narrow-band optical bandpass filter
Data Source
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AI summary
The present invention concerns a gas analyzing system for the analysis of respiratory gases to and from a mammal. The gas analyzing system (10) comprises a light transmitter (11) which includes an IR-emitter adapted to emit at least one measuring beam (12), sad light transmitter being arranged to emit the measuring beam into a gas mixture (13) including the respiratory gases, a filter component (14) including a number of filters (14a,14b) having different transmission wavelength ranges, the filter component being arranged to position the filters such that the at least one measuring beam passes through the number of filters one at a time, a light receiver (16) including an IR-detector adapted to receive the measurement beam and to generate at least one measurement signal representative of an optical energy of the measurement beam, and a signal processing circuitry (20) adapted to receive the at least one measurement signal. The signal processing circuitry comprises a peak detector (22) and is adapted to determine an intensity measure of each identified peak using at least one predetermined estimation function. Furthermore, the intensities can be used to determine gas concentrations.