JP2634464B2 - Automatic qualitative analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of the Invention The present invention relates to qualitative analysis such as an electron beam microanalyzer (EPMA), a fluorescent X-ray analyzer, a powder X-ray spectrometer, and an infrared absorption spectrum analyzer. The present invention relates to an automatic qualitative analyzer that detects peak data from spectral data collected by an apparatus and automatically determines a substance name corresponding to each peak data.

B. Conventional technology An overview of the analysis process using a conventional automatic qualitative analyzer
A description will be given using an automatic MA qualitative analyzer as an example.

Characteristic X-rays obtained by irradiating the sample surface with an electron beam are spectrally analyzed simultaneously using a plurality of X-ray spectral crystals.

Many peaks corresponding to the elements included in the sample surface are present in the spectrum data for each X-ray crystal, and peak data including the wavelength and intensity of these peak portions is detected.

The peak most suitable for specifying the element is selected from these peak data. Usually, the peak having the highest intensity is selected as such a peak. It is determined whether the main line or the sub line corresponding to this peak is in the wavelength table stored in the data file in advance, and if so, the element name and the line name are identified (named) for the peak. At the same time, the element name and the line name are similarly identified for other peaks that will appear if the element exists.

Here, the wavelength table is an EPMA as shown in FIG.
It is created for each X-ray spectral crystal provided in
A table in which all elements that can be qualitatively analyzed by each X-ray spectral crystal are associated with element lines, and judgment criteria data including respective peak wavelengths and peak-to-peak intensity ratios is described. An element line is a general term for a plurality of peaks that appear when a characteristic X-ray of a certain element is spectrally analyzed. The element line includes a main line that is the most suitable peak for specifying the element, a sub line that is the next most suitable peak, and a higher-order line that is another group of peaks.

Next, among the remaining peak data not identified by the above, the most appropriate peak for identifying the element is selected, and the wavelength table is referred to as described above,
An element name and a line name are identified for the peak, and other peaks related to the element are also identified.

Hereinafter, similarly, the element name and the line name are identified in descending order of the peak.

A series of processing as described above is performed on the peak data for each X-ray spectral crystal.

C. Problems to be Solved by the Invention However, the above-described conventional apparatus has the following problems.

That is, in the qualitative analysis using the conventional apparatus, the substance name is identified by a uniform procedure for each substance to be identified as described above, so that when the number of peak data is large or a special peak is detected. In such a case, there is a problem that a peak cannot be determined or an erroneous determination is made. Therefore, according to the conventional apparatus, there is also an annoyance that the expert needs to add or correct the determination result after performing the qualitative analysis by the apparatus.

The present invention has been made in view of such circumstances, and provides an automatic qualitative analyzer that can automatically perform accurate qualitative analysis based on peak data detected from collected spectral data. It is intended to be.

D. Means for Solving the Problems To achieve the above object, the present inventor
As a result, an automatic qualitative analyzer with higher reliability than that of the conventional device was realized by acquiring, organizing, and making rules of the empirical knowledge of experts as follows.

(1) Acquisition of knowledge Experts who routinely conduct qualitative analysis with EPMA made detailed judgments on several types of data, and acquired their empirical knowledge.

Analytical specialists combine the data obtained by using multiple X-ray diffraction crystals, and select peaks, peak-to-peak intensity ratios, half-widths, etc. from the elements that can be separated by each X-ray diffraction crystal. The element name and the line name corresponding to are added. Especially when a plurality of elements correspond to one peak, the determination method is complicated.

(2) Organization of knowledge As a result of organizing the acquired knowledge into rules, it was found that the expert's knowledge on judgment can be classified into "knowledge on judgment" and "knowledge on procedure".

"Knowledge on judgment" refers to knowledge for estimating which line of which element is the peak collected as data. Such knowledge differs for each analyzable element of each X-ray crystal.

The “knowledge on the procedure” is a procedure of determining a peak from among a large number of collected peaks. The determination order is determined according to the intensity of the collected peak. That is, among short-wavelength data in which there are relatively few competing elements, the determination is advanced from the data having a high peak intensity and being clear.

(3) Rule formation of knowledge A knowledge base for an expert system was created by expressing the organized specialized knowledge in the form of "IF ~ THEN ..." production rules.

The knowledge base is divided into a plurality of X-ray spectral crystals, and the “knowledge on judgment” of each X-ray spectral crystal is created as a knowledge base for backward inference by its nature, and the “knowledge on procedure” of each X-ray spectral crystal. Was created as a forward-looking inference knowledge base by its very nature. Also, considering the ease of description of rules and the necessity of different judgment conditions for each element, the production rules constituting each knowledge base are described for each element.

From the above, the automatic qualitative analyzer according to the present invention has the following features.

In the automatic qualitative analyzer that detects peak data from the collected spectrum data and identifies the substance name corresponding to each peak data, each substance is identified for multiple types of substances that can be analyzed by that apparatus Criteria data storage means for storing individual criteria data as criteria for performing the analysis, and a substance name corresponding to the peak data in the spectrum data by using a production rule of the form "IF to THEN ..." for each substance. Backward inference means for inferring backwards, and matching determination means for comparing peak data and the determination reference data in the spectrum data during the backward inference to determine the presence or absence of a corresponding peak,
For a candidate substance determined to be possibly present by the backward inference means, a peak intensity calculation means for calculating peak intensity as necessary, and a substance name with reference to the peak intensity calculated by the peak intensity calculation means. Forward inference means for determining the presence of the candidate substance using a production rule of the form “IF to THEN...” For each substance including a condition for identification.

E. Operation According to the present invention, the substance name corresponding to each peak data is deduced backward while referring to the result of the matching process between the peak data detected from the spectrum data and the determination reference data. Therefore, since an individual production rule is used for each substance, inference is accurately performed according to the unique conditions of each substance.

Then, in the backward inference, for example, when a plurality of types of candidate elements are listed for one peak data, the intensity of the main peak of each candidate element is calculated as necessary, and the result is referred to. By performing forward inference, the presence of the candidate element is determined.

F. Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an EPMA automatic qualitative analyzer according to one embodiment of the present invention, and FIG. 2 is a block diagram showing a program module and a data flow of an expert system portion of the device. .

In FIG. 1, reference numeral 1 denotes an electron beam microanalyzer (EPMA), which is provided with a plurality of X-ray spectral crystals (not shown) for simultaneously detecting characteristic X-rays from a sample. In the EPMA automatic qualitative analyzer according to this embodiment, lithium fluoride (LiF),
Pentaerythritol (PET), rubidium acid phthalate (RAP), ammonium dihydrogen phosphate (ADP), and lead stearate (PbST) can be used. Usually, three or four types of X-ray spectral crystals are appropriately used. Of course, by appropriately changing and expanding the wavelength table 7 and the knowledge base 8 described later, other types of X can be obtained.
It is also possible to use a line spectral crystal.

The spectrum data obtained by each X-ray spectral crystal of the EPMA 1 is provided to the data collection unit 2. The data collection unit 2
The spectrum data obtained by qualitative analysis of MA1 (point analysis in this embodiment) is analyzed, and peak data including the wavelength, peak intensity, half width, and the like of data that can be regarded as a peak is detected. The detected peak data is stored in the peak data file 3.

Reference numeral 4 denotes an expert system for inferring an element name or a line name corresponding to each peak data stored in the peak data file 3, and includes a data processing unit 5, an inference control unit.
6, a wavelength table 7, and a knowledge base 8.

As shown in FIG. 2, the data processing unit 5 reads the peak data of each X-ray spectral crystal from the peak data file 3, and reads a main line of an element that can be analyzed for each X-ray spectral crystal from the wavelength table 7. A data reading program module 5a for reading the sub-line determination reference data, a matching program module 5b for performing matching between the read determination reference data and the peak data, and backward inference for the peak data. A naming program module 5c for assigning the element names and line names of the elements listed as candidates, a peak intensity calculation program module 5d for calculating the intensity of peak data, and inference obtained by the inference control unit 6. And a write program module 5e for writing the result of the determination to the peak data file 3. No.

Knowledge base 8 is a meta-knowledge that controls the flow of the entire inference.
8a, module knowledge 8b for examining the presence or absence of data of each X-ray crystal, and the five types of X-ray crystal (LiF, PET, RAP,
For each ADP, PbST), backward inference module knowledge 8c, 8e, 8g, 8i, 8k expressing "knowledge on judgment" and forward inference module knowledge 8 expressing "knowledge on procedures"
d, 8f, 8h, 8j, 8l.

In each of the above-described knowledges 8a to 8l, the organized knowledge of the expert is expressed by a production rule in the form of "IF to THEN ...". The inference control unit 6 performs inference as described below according to the module knowledges 8a to 8l stored in the knowledge base 8.

As shown in FIG. 3, the wavelength table 7 as the criterion data storage means stores the X-ray spectral crystals (LiF, PET, RAP,
For each element line of each element that can be spectrally analyzed by DP, PbST), a peak wavelength, a peak-to-peak intensity ratio, a half width, and the like are stored as determination reference data.

Returning to FIG. 1, the inference result obtained by the expert system 4 is written to the peak data file 3. The display control unit 9 reads the inference result written in the peak data file 3, displays the element name and the line name on each peak in the peak waveform of each X-ray spectral crystal projected on the CRT 10, and identifies the peak. Wavelength for the peak
Displays necessary data such as intensity ratio and half width.

Next, the inference processing executed in the expert system 4 of the apparatus according to the above-described embodiment will be specifically described with reference to a flowchart shown in FIG.

Step S1: The data reading program module 5a of the data processing unit 5 is started, and each X is read from the wavelength table 7.
The determination reference data of the X-ray crystal is read, and the peak data is read from the peak data file 3 for each X-ray crystal. The read criterion data is supplied to the data processing unit 5, and the peak data is supplied to the data processing unit 5 and the inference control unit 6, respectively.

Step S2: The peak data file 3 contains the above-described 5
There is a file for individually storing peak data of each type of X-ray crystal. The inference controller 6 is based on the module knowledge 8b for crystal data confirmation in the knowledge base 8,
It is determined whether or not each read peak data file has peak data, and an inference process is performed for a file having data.

Step S3: The inference control unit 6 sends the meta knowledge 8a from the knowledge base 8 and the module knowledge 8c, 8e, 8g, 8i, 8k for backward inference.
The module knowledge about the X-ray crystal having the peak data present therein is read out, and for the peak data of the X-ray crystal having the peak data, for all the elements in the wavelength table of the corresponding X-ray crystal, If necessary, the matching program module 5b of the data processing unit 5
Is started, and backward inference is performed with reference to the matching result in step S4.

The rules as knowledge for determining the possibility of the presence of an element differ for each X-ray crystal and even for each element.
Since the number reaches several hundreds, an example is shown below.

For example, in a production rule for determining whether or not a peak of the element A1 appears in the data of the X-ray crystal C1, the X-ray crystal that should be given priority over the X-ray crystal C1 when determining the element A1. If there is C2, there is no absence of the peak of element A1 in the data of X-ray crystal C2. The peak (main line) most suitable for the determination of element A1 in the data of X-ray crystal C1 If there is a possibility that the main line may not be detected due to interference from other element lines, etc., a peak (sub line) equivalent to the main line must be detected, When the conditions such as that the width and peak shape are similar to those of the element A1 are satisfied, it is presumed that the element A1 may be present, and the element A1 is listed as a candidate element.

As described above, the conditions of the production rules are different for each element. For example, which X-ray spectral crystal data is given priority is different for each element. In addition, since the peak line of some elements cannot be disturbed, when such an element is determined, the determination may be made only by the peak line, and conversely, the peak line may be disturbed. If the element is an easy element, the presence or absence of the sub-line may be determined with priority. Furthermore, since the presence of many elements can be estimated by focusing on the peak wavelength, the above conditions are often sufficient, but the above conditions are not sufficient for elements that are difficult to determine only by the peak wavelength. Is added.

Step S4: The matching program module 5b of the data processing unit 5 is started by the inference control unit 6 as necessary during the backward inference of the step S3, and the peak data contains the elements that can be analyzed by the X-ray spectral crystal. Whether or not there is a peak corresponding to the main line or the sub line is determined by comparing the peak data with the determination reference data (the wavelength of the main line / sub line, the peak-to-peak intensity ratio, and the half width).

Step S5: When the candidate element is listed for the peak for each X-ray crystal by the backward inference, the naming program module 5b of the data processing unit 5 is activated, and the candidate element name and line name for each peak are activated. Is attached. When the main line or sub line of a certain element is specified, the wavelength position of other higher-order lines can be determined from the wavelength table of the X-ray diffraction crystal. Named.

Step S6: According to the backward inference of the step S3, two or more element names may be listed as candidates for the same peak. In such a case, all the element names listed as candidates may be correct, but one of the candidate elements may be correct and the other candidate element may be incorrect. Therefore,
In the following processing, forward inference is performed in order to determine elements that have been nominated as candidates by backward inference.
For this forward reasoning, module knowledge 8d, 8f, 8h, 8j,
8l is read.

Similar to the rule for backward inference, there are a large number of rules for forward inference for each element that can be analyzed by each X-ray spectral crystal, and an example is shown below.

For example, in the production rule for determining the element A1 estimated to be present in the data of the X-ray crystal C1 in the backward inference, the fact that the element A1 is listed as a candidate element, the peak corresponding to the element A1 If the element lines (peaks) of the element do not overlap, and if the peaks of other elements overlap, calculate the peak intensity of each element, and as a result, determine that the peak of element A1 overlaps When the conditions such as and are satisfied, the element name and line name identified as the candidate element A1 are determined as correct. On the other hand, when the existence of the candidate element is denied in the forward inference, the naming of the candidate element performed in step S5 is deleted.

In such forward inference, by referring to the results of the peak intensity calculation program module 5d of the data processing unit 5 and proceeding with inference in order from those that can be determined among the candidate elements, the presence or absence of all candidate elements is determined. Is determined.

As described above, the production rule used in the forward inference is also determined for each element, but generally has the above-described features. However, since peaks of some elements cannot overlap, the peak intensity is not referred to in a production rule for determining such elements.

Step S7: As described above, the presence of the candidate element is confirmed by forward inference for all the elements listed as candidates for each X-ray crystal, and the result is written in the data processing unit 5. Program module 5e
Is written to the peak data file 3.

As described above, when the inference processing by the expert system 4 is completed, the display control unit 9 reads the inference result of the peak data file 3 as described above, and
It is displayed on the CRT 10 or output to a printer (not shown).

The following table shows the percentage of correct answers as a result of the determination made in the above embodiment, in comparison with the conventional apparatus.

It should be noted that the production rules described in the above examples are based on knowledge of the material of the sample (for example, whether the sample is an alloy, a mineral, a compound, or a ceramic). Is advantageous in the following points.

That is, the peak wavelength of each element is stored with a certain width (range) in the wavelength table 7 as the judgment reference data storage means. In some cases, the peak wavelength shifts and deviates from the range of the peak wavelength as the criterion data. In such a case, if the operator gives knowledge about the material of the sample as a condition of the production rule in advance, and performs the matching process using the criterion data in which the range of the peak wavelength is changed accordingly, Even if the peak wavelength shifts as described above, the presence of the element is estimated, so that accurate determination can be performed.

In addition, depending on the sample, since an element that can never exist may be known in advance, in such a case,
By removing the element from the target of the matching processing or the like from the beginning, the determination can be speeded up.

Further, in the above embodiment, the EPMA is described as an example, but the present invention can be applied to the following qualitative analyzer.

(1) Fluorescent X-ray analyzer The fluorescent X-ray analyzer irradiates a sample with X-rays and spectrally analyzes the secondary X-rays emitted. When the detected spectral data is EPMA Therefore, the same element determination method as that of the above-described embodiment can be applied.

(2) Powder X-ray spectrometer A powder X-ray spectrometer is a device that detects an angle at which X-rays irradiated on a powder sample are reflected. The detected reflection angle is unique to a compound (eg, quartz, iron oxide, etc.) in the sample, and the detected peak data is matched with pre-stored judgment reference data of a plurality of types of compounds. By doing so, the compounds in the sample are identified. In this identification process, the compounds in the sample can be inferred using the production rules created for each of the compounds that can be analyzed.

(3) Infrared absorption spectrum analyzer The infrared absorption spectrum analyzer is a device that irradiates a sample with infrared light whose wavelength is continuously changed and measures the spectrum of the infrared light absorbed at that time. Infrared absorption shows a spectrum unique to the bonding group in the molecule of the sample, so spectral data of a plurality of types of substances that are expected to be present are stored in the database as judgment reference data in advance, and each judgment reference data and detection By matching the data, the molecules in the sample can be identified. In this analysis method, a plurality of spectra are obtained for one molecule, and these data may overlap with the data of another molecule. Therefore, the present invention is applied to the case where such data is determined. be able to.

G. Effects of the Invention As is apparent from the above description, according to the present invention,
Refer to the matching result between the peak data obtained from the collected spectrum data and the judgment reference data for each substance as a reference for fixing the substance to be analyzed, and change the substance name of the peak data. In inferring,
Since the inference is made using a unique production rule set for each substance, compared to the case where each substance is determined by a uniform rule as in the conventional example, the The possibility of existence can be accurately estimated.

In addition, after elements which may be present by backward inference are listed as candidates, in order to infer forward to determine the candidate elements, production rules for each substance are used. Is used to determine whether the peak intensity of the candidate substance is determined.
Even when two or more substance names are listed as candidates for one peak data in the backward inference, the possibility of the existence of each candidate substance can be accurately determined.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of an EPMA automatic qualitative analyzer according to one embodiment of the present invention, FIG. 2 is a block diagram showing a program module and a data flow of an expert system part of the device, and FIG. FIG. 4 is an explanatory diagram of a wavelength table, and FIG. 4 is a flowchart of inference processing performed by the expert system. 1. Electron beam micro analyzer (EPMA) 2. Data collection unit 3. Peak data file 4. Expert system 5. Data processing unit 5b Matching program module 5d Peak intensity calculation program module 6. ...... Inference controller 7 ... Wavelength table 8 ... Knowledge base 8c, 8e, 8g, 8i, 8k ... Module knowledge for backward inference 8d, 8f, 8h, 8j, 8l Module knowledge for forward inference

 ──────────────────────────────────────────────────の Continued on the front page (72) Kozo Ogimoto, Inventor Koichi Ogimoto Nishi-no-Kyowaharacho, Nakagyo-ku, Kyoto, Kyoto Prefecture Shimazu Seisakusho Sanjo Plant (72) Inventor Satoshi Hasegawa 1, Kunohara-cho, Nishino-Kyoto, Kyoto, Kyoto (56) References JP-A-63-58240 (JP, A) "Introduction to Knowledge Engineering" by Haruki Ueno (published on May 30, 30, ohm), pp. 35-73

Claims (1)

(57) [Claims] 1. An automatic qualitative analyzer for detecting peak data from collected spectrum data and identifying a substance name corresponding to each peak data, wherein a plurality of types of substances which can be analyzed by the apparatus are provided. A criterion data storage unit storing individual criterion data serving as a criterion for identifying each substance; and `` IF to TH '' for each substance.
A backward inference means for backward inferring a substance name corresponding to peak data in the spectrum data using a production rule in the form of "EN ..."; and a peak data in the spectrum data and the determination reference data during the backward inference. Matching determination means for comparing the presence of the corresponding peak, and a peak intensity calculation means for calculating a peak intensity as necessary for a candidate substance determined to be possibly present by the backward inference means; and “IF to TH” for each substance, including conditions for identifying the substance name with reference to the peak intensity calculated by the calculation means.
An automatic qualitative analyzer, comprising: forward inference means for determining the presence of the candidate substance using a production rule of the form "EN ...".