Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
1999-04-28
2001-08-28
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
C702S085000
Reexamination Certificate
active
06281499
ABSTRACT:
BACKGROUND OF THE INVENTION
(i) Field of the Invention
The present invention relates to a method for analyzing data by an on-line near infrared spectral analyzer.
(ii) Description of the Related Art
As a manufacturing process management, there are an off-line management and an on-line management. In the off-line management, a specimen sampled from a manufacturing line is sent to an analyzing room which is away from the line, its characteristic value is analyzed, and the result is fed back to the line. In the analysis, a chemical analysis is performed in many cases, so that it takes a long time for the analysis. In the on-line management, a specimen sampled by an automatic sampler is automatically sent to an analytical instrument and is automatically analyzed. An analytical result is fed back to the line.
In recent years, a technique for a non-destructive inspection using a near infrared spectroscopy has progressed and is used to analyze protein or starch of food or feed. Consequently, time and costs are sharply reduced as compared with a conventional chemical analysis. As for an object to be measured as well, not only chemical characteristics but also physical characteristics can be measured. Although the near infrared spectroscopy or an infrared spectroscopy is used in the on-line analysis in few cases so far, as effects of a laboratory analysis become more apparent, needs of the on-line analysis are being raised.
In the near infrared spectroscopy, an object to be measured is analyzed by a chemical means or a physical means to make its characteristic value clear, a spectrum of the same object to be measured is obtained by a laboratory near infrared spectral analyzer, and a calibration indicative of a relation between the spectrum and the characteristic value is formed. The spectrum of the next target to be measured is measured by the laboratory near infrared spectral analyzer and the characteristic value of the object to be measured is estimated from the spectrum and the calibration. In order to form the calibration, works such as chemical analysis and clarification of physical characteristics of a large quantity of objects to be measured are needed.
When the on-line analysis is performed by the near infrared spectroscopy, the calibration formed by the laboratory near infrared spectral analyzer cannot be used as it is. Hitherto, since the structure of the spectral analyzer is complicated, even in case of the spectral analyzers having the same structure, the sampling measurement is performed by each spectral analyzer and the calibration is obtained by each spectral analyzer. Particularly, an optical fiber is used in a near infrared spectral analyzer for on-line in many cases. Since the optical fiber is not used in the near infrared spectral analyzer for laboratory (for off-line) in most of cases, however, a difference in spectral characteristics occurs. In an optical system using a diffraction grating for laboratory, dispersed light is irradiated onto an object. However, in the system for on-line, white light is irradiated onto a sample and there is a case where transmission light or reflection light is dispersed by the diffraction grating. It is impossible to transfer or share the calibration between the spectral analyzers having different structures as mentioned above, so that it is considered that the on-line analysis is difficult.
SUMMARY OF THE INVENTION
The present invention is made in consideration of the above-mentioned problems and it is an object to provide a method for analyzing a measured value by an on-line spectral analyzer in which a calibration for off-line can also be used for on-line.
The invention provides a method for analyzing an object to be measured, by a chemical means or a physical means to make its characteristic value clear, obtaining a spectrum of the same object to be measured, by an off-line near infrared spectral analyzer, obtaining a calibration indicative of a relation between the spectrum and the characteristic value, selecting at least one sample from among the same kind of objects to be measured, obtaining spectra by the off-line near infrared spectral analyzer and an on-line near infrared spectral analyzer, obtaining a difference between both the obtained spectra, measuring a spectrum of the same kind of object to be measured, by the on-line near infrared spectral analyzer, correcting the measured spectrum by the difference between both the spectra, and estimating a characteristic value of the object to be measured, by using the corrected spectrum and the calibration.
In a preferred embodiment, as above-mentioned one sample, a sample showing a substantially central value in a measurement range which is covered by the calibration is used.
In another preferred embodiment, when the object to be measured is changed and an estimated error of the characteristic value exceeds an allowable value in the calibration, a sample of the object to be measured is added and is measured by the off-line infrared spectral analyzer, the calibration is corrected, the corrected calibration is transferred to the on-line spectral analyzer, and the characteristic value of the object to be measured is estimated.
In another preferred embodiment, spectra of the same object to be measured are obtained by the on-line near infrared spectral analyzer and the off-line near infrared spectral analyzer, a difference between both of newly obtained spectra is compared with the difference between both the spectra obtained already and, when the difference between the new spectra is larger, the characteristic value of the object to be measured is estimated by using the difference between the new spectra.
In another preferred embodiment, the calibration obtained by the off-line near infrared spectral analyzer is used by a plurality of on-line near infrared spectral analyzers.
The advantages obtained by the aforementioned present invention will be described hereinbelow.
At least one sample is selected from among the same kind of objects to be measured, the sample is analyzed by the off-line near infrared spectral analyzer and the on-line near infrared spectral analyzer to obtain spectra, and a difference between both the obtained spectra is obtained. Subsequently, a spectrum of the same kind of object to be measured is measured by the on-line near infrared spectral analyzer and the difference between both the spectra is added to or subtracted from the measured spectrum, whereby measurement data of the on-line near infrared spectral analyzer is converted into data of the off-line near infrared spectral analyzer. Consequently, the characteristic value of the object to be measured can be estimated on the basis of the data converted by using the calibration of the off-line near infrared spectral analyzer.
Although the calibration is formed on the basis of a chemical analysis or a physical analysis for a large number of samples, the difference between both the spectra is obtained by using such a sample having a value that is located at a substantially center position of the measurement range at which the calibration is effective. Consequently, a precision of the difference between both the spectra is raised.
There is a case where the characteristic value of the object to be measured serving as a target to be measured is changed. In this case, a sample of the object to be measured is added and is measured by the off-line infrared spectral analyzer and the calibration is corrected, so that the measurement capable of coping with the change in characteristic value of the object to be measured can be performed.
An aging change of the on-line near infrared spectral analyzer appears as a change in spectrum. After an elapse of predetermined using time, the same object to be measured is measured by the on-line and off-line near infrared spectral analyzers to obtain spectra. When a difference between both the spectra is different from the difference which has already been obtained, the characteristic value of the object to be measured is obtained on the basis of the new difference between the spec
Kobayashi Kouji
Kobayashi Tomoyuki
Sato Kouichi
Yamada Takeo
Hannaher Constantine
McDermott & Will & Emery
Nireco Corporation
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