Optical Moisture Measurement Compensating for Colorant Spectral Disturbance
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Solution Overview
Problem
Existing moisture measurement techniques for paper, especially those with colorants like ink, face challenges in providing reliable results due to spectral disturbances caused by coloring substances, leading to inaccurate attenuation measurements.
Innovation Solution
A system that uses a broad band optical source and a detector with multiple channels and interference filters to measure the attenuation of optical radiation through paper, compensating for spectral disturbances by determining the general dependence of attenuation across various wavelengths, allowing for accurate moisture content determination even in the presence of coloring substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared light attenuation measurement is used to determine moisture content, then moisture measurement is possible, but the presence of colorants such as ink causes spectral disturbances that lead to inaccurate measurements
Solution Approach 1:
The measurement spectrum is segmented into multiple wavelength channels, with specific channels selected to avoid absorption bands of colorants while targeting water absorption features. This segmentation allows the system to isolate moisture-related spectral information from colorant interference.
Solution Approach 2:
The system applies local quality by selecting specific wavelength regions that are sensitive to water but less sensitive to colorant absorption. Different wavelength channels are optimized for different measurement purposes, with some channels targeting moisture and others used for reference or colorant characterization.
2Reliability
If traditional single-wavelength infrared measurement is used, then the system is simple, but it cannot compensate for spectral disturbances caused by coloring substances
Solution Approach 1:
The optical system is designed with multi-functionality, using a single broadband infrared source that provides multiple wavelength channels simultaneously. The same optical path and detector system handle both moisture measurement and colorant compensation functions, reducing overall system complexity while improving reliability.
Solution Approach 2:
The system changes the measurement parameter from a single wavelength to multiple wavelengths, enabling spectral analysis that can distinguish between water absorption and colorant absorption. This parameter change allows the system to extract moisture information while compensating for colorant effects through ratio or difference calculations.
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 accurate and reliable moisture measurement in paper products with coloring substances, enhancing process control in printing and drying processes by providing precise moisture values.
Implementation Method 1
Moisture content of paper may be measured by directing infrared light from an optical source to the paper
Implementation Method 2
water attenuates strongly at known, narrow optical bands in infrared region. The attenuation of water depends on the amount of the water in the paper
Implementation Method 3
A system that uses a broad band optical source and a detector with multiple channels and interference filters to measure the attenuation of optical radiation
Data Source
AI summary
Detector receives optical radiation transmitted through measured object and is responsive to one or more predetermined optical absorption bands of water and cellulose and two or more separate optical bands related to spectral disturbance caused by coloring substance. The measuring unit measures, on basis of responses of the detector, a water dependent value on basis of attenuation of optical radiation in predetermined optical absorption band of water, a cellulose dependent value on basis of attenuation of optical radiation in predetermined optical absorption band of cellulose, determines general dependence of attenuation with respect to wavelength including spectral disturbance caused by coloring substance by measuring attenuations in predetermined separate optical bands apart from predetermined bands of water and cellulose, and forms a moisture value on basis of moisture dependent value, cellulose dependent value, and general dependence of attenuation for compensating for spectral disturbance of at least one coloring substance.