JP2001099793A - X-ray analysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray analysis device, such as a fluorescent X-ray analysis device of a wavelength dispersion type, an X-ray diffraction device or the like, capable of making a prompt and accurate analysis by continuous scan. SOLUTION: A count time for a predetermined scanning section is obtained by a count time counter 15 and a divider 16, and a count value of each section is corrected based on a corresponding count time by a correction operating means 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for performing continuous scanning in an X-ray analyzer such as a wavelength-dispersive X-ray fluorescence analyzer or an X-ray diffractometer.

[0002]

2. Description of the Related Art Conventionally, for example, in a wavelength-dispersive X-ray fluorescence spectrometer, a sample is irradiated with primary X-rays, X-rays generated from the sample are separated by a spectroscopic element, and the separated fluorescent X-rays are used. The line is detected by a detector to generate a pulse. The voltage of the pulse, that is, the peak value, is based on the energy of the fluorescent X-ray, and the number per unit time is based on the intensity of the fluorescent X-ray. The number is sorted by a wave height analyzer and the number is measured by a scaler. That is, the count value of the selected pulse is obtained by the scaler.

Here, in a scanning (scanning) type apparatus, while changing the wavelength of the fluorescent X-rays separated by the spectroscopic element by the interlocking means such as a so-called goniometer, the separated fluorescent X-rays are sent to the detector. The spectroscopic element and the detector are scanned in association with each other so as to be incident. In particular, when performing qualitative analysis or semi-quantitative analysis, rapidity is required, so that the spectroscopic element and the detector are continuously scanned. That is, instead of the step scan in which the goniometer is driven at a fixed angle and then stopped and counted for a certain time, a continuous scan for counting while the goniometer is continuously driven is performed. At this time, the count value obtained by the scaler is read out at every 1/100 degree in a predetermined scanning section, for example, at a rotation angle (so-called 2θ) of the detector, and is set as the fluorescent X-ray intensity in each section.

[0004]

FIG. 2 shows an example of the relationship between the scanning range (2θ) of the goniometer and the scanning speed. The goniometer is continuously driven at a desired high speed as shown by B in the figure. Before driving, acceleration driving is required as shown by A. Further, in order to stop the goniometer driven at a desired high speed, it is necessary to drive at a reduced speed as shown by C. During the operation of the goniometer during the acceleration or deceleration, the time required for the counting is different from each other even with the same count value every 1/100 degree, so that the accurate fluorescent X-ray intensity in each section cannot be obtained.

On the other hand, if the accuracy of the goniometer is not counted during driving of the goniometer at the acceleration or deceleration for accuracy, the vicinity of both ends of the scanning range of the goniometer cannot be analyzed. In addition, as shown by the two-dot chain line, if the counting is performed by lowering the driving speed of the goniometer to the extent that acceleration and deceleration are practically unnecessary, accurate analysis can be performed including the vicinity of both ends of the scanning range. This does not allow quick analysis. Therefore, qualitative analysis and semi-quantitative analysis cannot be performed quickly and accurately in a wide wavelength range.

In addition, the intensity of diffracted X-rays diffracted by the sample is measured by the detector while changing the angle of incidence of the incident X-rays on the sample by linking the sample stage on which the sample is mounted with the goniometer and the detector. Thus, in an X-ray diffractometer for analyzing a crystal structure or the like of a sample, high-precision measurement is performed by a step scan, but requires a long time. On the other hand, quick measurement can be performed by continuous scanning, but accurate measurement cannot be performed because the counting time for each predetermined scanning section is not exactly constant.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and performs rapid and accurate analysis by continuous scanning in an X-ray analyzer such as a wavelength-dispersive X-ray fluorescence analyzer or an X-ray diffractometer. It is an object of the present invention to provide a device capable of performing the above.

[0008]

In order to achieve the above object, an X-ray fluorescence spectrometer according to a first aspect of the present invention comprises a sample stage on which a sample is placed and an X-ray for irradiating the sample with primary X-rays. Source,
A spectroscopic element that disperses fluorescent X-rays generated from a sample, and a detector that receives the fluorescent X-rays separated by the spectroscopic element and generates a number of voltage pulses corresponding to the energy of the fluorescent X-rays according to the intensity. While changing the wavelength of the fluorescent X-rays split by the spectroscopic element, the spectroscopic element and the detector are linked and continuously scanned so that the split fluorescent X-rays enter the detector. Interlocking means.

The apparatus further comprises a pulse height analyzer for selecting pulses in a predetermined voltage range among the pulses generated by the detector, a scaler for calculating a count value of the pulses selected by the pulse height analyzer, A counting time counter for measuring a counting time required for counting pulses by the scaler. Further, the apparatus includes a frequency divider for issuing a read command for each predetermined scanning section in the interlocking means, a count value obtained by the scaler in response to the read command from the frequency divider, and the count time counter. And a correction operation means for reading out the counting time measured in the step (a) and correcting the counted value based on the counting time.

According to the first aspect of the present invention, the counting time for each predetermined scanning section is obtained by the counting time counter and the frequency divider, and the count value of each section is corrected by the correction calculating means based on the corresponding counting time. Therefore, when the interlocking means is driven at a high speed, accurate fluorescent X-ray intensity in each section can be obtained even during driving at acceleration and deceleration. Therefore, in X-ray fluorescence analysis, qualitative analysis and semi-quantitative analysis can be performed quickly and accurately in a wide wavelength range. That is, rapid and accurate analysis can be performed by continuous scanning.

In the X-ray diffractometer according to the present invention, first, a sample stage on which a sample is mounted, an X-ray source for irradiating the sample with incident X-rays, and diffracted X-rays diffracted by the sample are incident on the sample stage. A detector that generates a number of voltage pulses according to the intensity of the diffracted X-rays in accordance with the intensity, and the sample stage such that the diffracted X-rays are incident on the detector while rotating the sample stage. Interlocking means for interlocking the detectors for continuous scanning.

The apparatus further comprises a pulse height analyzer for selecting pulses in a predetermined voltage range among the pulses generated by the detector, a scaler for calculating a count value of the pulses selected by the pulse height analyzer, A counting time counter for measuring a counting time required for counting pulses by the scaler. Further, the apparatus includes a frequency divider for issuing a read command for each predetermined scanning section in the interlocking means, a count value obtained by the scaler in response to the read command from the frequency divider, and the count time counter. And a correction operation means for reading out the counting time measured in the step (a) and correcting the counted value based on the counting time.

According to the second aspect of the present invention, the counting time for each predetermined scanning section is obtained by the counting time counter and the frequency divider, and the count value of each section is corrected by the correction calculating means based on the corresponding counting time. Therefore, accurate diffraction X-ray intensity in each section can be obtained, and in X-ray diffraction analysis, rapid and accurate analysis can be performed by continuous scanning.

According to a third aspect of the present invention, in the first or second aspect, the frequency divider issues the read command based on a signal from a rotary encoder provided on a main shaft of the interlocking means. .

According to the device of the third aspect, the count value of each section is corrected including the fact that the counting time for each predetermined scanning section becomes unstable due to the mechanical structure of the interlocking means. More accurate X-ray intensity in each section can be obtained, and in X-ray analysis, rapid and more accurate analysis can be performed by continuous scanning.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus according to a first embodiment of the present invention will be described below. First, regarding the configuration of this device,
This will be described with reference to FIG. This apparatus is a fluorescent X-ray analyzer, and firstly, a sample table 2 on which a sample 1 is placed, an X-ray source 4 such as an X-ray tube for irradiating the sample 1 with primary X-rays 3, and a sample 1 A spectroscopic element 6 for dispersing fluorescent X-rays 5 generated from
Fluorescent X-rays 7 split by the spectroscopic element 6 are incident thereon, and a detector 8 such as an SC or F-PC that generates a number of voltage pulses corresponding to the energy of the fluorescent X-rays 7 in accordance with the intensity; While changing the wavelength of the fluorescent X-rays 7 split by the element 6,
An interlocking unit 10 such as a goniometer for continuously scanning the spectroscopic element 6 and the detector 8 so that the spectroscopic X-rays 7 enter the detector 8 is provided.

That is, when the fluorescent X-rays 5 enter the spectroscopic element 6 at a certain incident angle θ, the extension line 9 of the fluorescent X-rays 5 and the fluorescent X-rays 7 spectrally (diffracted) by the spectroscopic element 6 become incident angles θ. Is twice as large as the spectral angle 2θ.
While changing the wavelength of the fluorescent X-rays 7 to be dispersed by changing θ, the spectroscopic element 6 is positioned on a paper surface passing through the center of the surface so that the spectrally separated fluorescent X-rays 7 continue to be incident on the detector 8. , And the detector 8 is rotated along the circle 12 about the axis O by twice the rotation angle. Specifically, a pulse motor and a 2θ axis for rotating the detector 8 are respectively provided on the θ axis for rotating the spectroscopic element 6 and the 2θ axis for rotating the detector 8.
Worm attached to the rotating shaft of the pulse motor,
And a worm wheel on which the spectroscopic element 6 or the detector 8 is attached so as to mesh with the worm, and the pulse motors of the θ axis and the 2θ axis are electrically interlocked in the pulse start timing and pulse number control. The whole of these mechanisms is the interlocking means 10.

The apparatus comprises a pulse height analyzer 13 for selecting pulses within a predetermined voltage (wave height) from the pulses generated by the detector 8, and a counting value of the pulses selected by the pulse height analyzer 13. Find (count the number of selected pulses)
The scaler 14 includes a scaler 14 and a count time counter 15 that measures a count time required for counting pulses by the scaler 14 based on a reference pulse from a crystal oscillator or the like. Further, the apparatus includes a frequency divider 16 for issuing a read command for each predetermined scanning section in the interlocking means 10, and a count value and a count time obtained by the scaler 14 in response to the read command from the frequency divider 16. A correction operation unit for reading the count time measured by the counter and correcting the count value based on the count time;

Specifically, for example, if one pulse to the pulse motor for driving the interlocking means 10 is 2θ, 5/10
In the case of equivalent to 00 degrees, the frequency divider 16 receives the interlocking means driving pulse, and every two pulses, that is, for each predetermined scanning section in the interlocking means 10 of 1/100 degrees in 2θ, the frequency divider 16 11, the correction operation means 11 reads out the count value obtained by the scaler 14 and the count time measured by the count time counter 15 every 1/100 ° in 2θ, and divides the count value by the count time. To make the fluorescent X-ray intensity in that section. The predetermined scanning section is, for example, in the range of 1/100 to 1/10 degrees,
Settings can be changed.

Next, the operation of this apparatus will be described by taking a case where a qualitative analysis is performed as an example. First, when the sample 1 is placed on the sample stage 2 and irradiated with primary X-rays 3 from the X-ray source 4, the generated fluorescent X-rays 5 are separated by the spectral element 6, and the separated fluorescent X-rays 7 are detected. The number of pulses corresponding to the intensity of the voltage is generated according to the intensity of the fluorescent X-rays 7 when the light enters the detector 8. Among the pulses, those having a predetermined voltage range are selected by the pulse height analyzer 13, and the count value of the selected pulses is obtained by the scaler 14.

Here, the spectroscopic element 6 and the detector 8 are interlocked by the interlocking means 10 and are continuously scanned (continuously scanned), whereby the fluorescent X-rays 5 generated from the sample 1 are separated into respective wavelengths and detected. However, because of the speed, the interlocking means 10
Is driven at a scan speed of 240 degrees / minute at 2θ as shown by B in FIG. The numerical values to be graduated in the scanning range (2θ), which is the horizontal axis in FIG. 2, are not described because they differ depending on the detector 8 and the spectroscopic element 6 (FIG. 1) used, but the maximum from the left end to the right end is 100 degrees. It is about.

As described above, in order to drive at such a high speed, before and after the driving, for example, 5 times each in the scanning range (2θ).
It is necessary to drive by acceleration and deceleration by degrees (shown exaggerated in FIG. 2 for easy understanding).
Even if the count value is read from the scaler 14 for each predetermined scanning interval of 1/100 degrees using the frequency divider 16, the time required for counting differs for each interval. On the other hand, the number of pulses per unit time entering the scaler 14 depends on the intensity of the fluorescent X-rays 7. Therefore, during driving during acceleration and deceleration (A and C in FIG. 2), even if the count value is read from the scaler 14 for each predetermined scanning section, the fluorescent X-ray intensity in each section does not become accurate.

Therefore, in this apparatus, the counting time required for counting the pulses by the scaler 14 is measured by the counting time counter 15, and the correction calculating means 11 divides the frequency every predetermined scanning section of 1/100 degree. In response to the read command from the scale 16, not only the count value obtained by the scaler 14 but also the count time measured by the count time counter 15 is read. Thus, the counting time for each 1/100 degree section is obtained. Then, for each 1/100 degree section, the correction calculating means 11 corrects the count value obtained by the scaler 14 by dividing the count value by the count time measured by the count time counter 15 to obtain the fluorescent X-ray intensity in that section. .

Thus, the fluorescence X at each spectral angle 2θ is obtained.
A spectrum indicating the intensity of the line 7 is obtained, and peak search and identification analysis are performed, that is, qualitative analysis is performed. The result is displayed on a display means such as a CRT (not shown). Further, a so-called semi-quantitative analysis can be performed based on the qualitative analysis result. In this apparatus, correction is performed in the entire scanning range without determining whether the scanning speed is constant or not. Such correction is performed during scanning at a constant high speed (B in FIG. 2). Assuming that the speed is 1, the driving may be performed only during driving during acceleration and deceleration (A and C in FIG. 2).

As described above, according to the apparatus of the first embodiment, the counting time counter 15 and the frequency divider 16 determine the counting time for each predetermined scanning interval of, for example, 1/100 degree, and the correction calculating means 11 Since the count value of the section is corrected based on the corresponding counting time, when the interlocking means 10 is driven at a high speed, the accurate value of each section including the driving during acceleration and deceleration (A and C in FIG. 2) is included. Fluorescent X-ray intensity can be obtained. Therefore, in X-ray fluorescence analysis, qualitative analysis and semi-quantitative analysis can be performed quickly and accurately in a wide wavelength range. That is, rapid and accurate analysis can be performed by continuous scanning.

Although the interlocking means 10 is driven by a pulse motor in the apparatus of the first embodiment, a servo motor may be used. In this case, during driving at a constant high speed (FIG. 2)
Even in the case of (B), fine speed unevenness may occur. Therefore, in order to correct the influence, it is better to perform correction in the entire scanning range without determining whether the scanning speed is constant.

Next, an apparatus according to a second embodiment of the present invention will be described. This apparatus is an X-ray diffraction apparatus. As shown in FIG. 3, first, a sample stage 2 on which a sample 1 is mounted and an incident X-ray (often monochromatic) 23 on the sample 1 are formed. An X-ray source 4 such as an X-ray tube to be irradiated and a detector that receives diffracted X-rays 27 diffracted by the sample 1 and generates a number of voltage pulses corresponding to the energy of the diffracted X-rays 27 according to the intensity. 8 and an interlocking means 20 such as a goniometer that interlocks the sample stage 2 and the detector 8 to continuously scan so that the diffracted X-rays 27 enter the detector 8 while rotating the sample stage 2. .

That is, when the incident X-ray 23 enters the sample 1 at a certain incident angle θ, the extension line 29 of the incident X-ray 23 and the diffracted X-ray 27 diffracted by the sample 1 are twice as large as the incident angle θ. Although the bending angle 2θ is formed, the interlocking means 20 changes the incident angle θ, and the diffraction X-rays 27 generated at the incident angle θ are detected by the detector 8.
The sample stage 2 on which the sample 1 is placed is
The detector 8 is rotated about an axis O perpendicular to the paper surface passing through the center of the surface of the sample 1, and the detector 8 is rotated about the axis O along the circle 12 by twice the rotation angle. Specifically, the interlocking means 20 includes, for example, a worm attached to a rotation shaft of a pulse motor and a worm wheel meshing with the worm, which is fixed with the axis O as a common center, and the rotation shaft to which the sample stage 2 is attached. And a base on which the detector 8 is attached by being mechanically connected to the main shaft, and driven by rotation of a pulse motor.

This apparatus comprises a peak analyzer 13, a scaler 14, a counting time counter 15, a frequency divider 16 and a correction operation means 11, similarly to the apparatus of the first embodiment. However, in the device of the second embodiment, the frequency divider 16 issues a read command based on a signal from a high-resolution (for example, 1/10000 degree) rotary encoder 30 provided on the main shaft of the interlocking means 20.

More specifically, for example, as shown in FIG. 4, the signal from the rotary encoder 30 corresponds to 4 / 10,000 degrees when the period T is θ, and the ON length is half the period. , Two-phase rectangular waves A whose phases are shifted by 1/4 cycle,
In the case of B, the frequency divider 16 receives the signals A and B from the rotary encoder 30 and every time the B phase is OFF and the A phase is ON, that is, 4/100 in θ.
For every predetermined scanning section of the interlocking means 20 of FIG. 3 of 00 degrees, a read command is given to the correction calculating means 11, and the correction calculating means 11 calculates the count value obtained by the scaler 14 every 4 / 10,000 degrees θ. The count time measured by the count time counter 15 is read out, the count value is divided by the count time, and the divided value is corrected to be the diffracted X-ray intensity in that section. The setting of the predetermined scanning section can be changed.

According to the apparatus of the second embodiment having such a configuration, the counting time counter 15 and the frequency divider 16 determine the counting time for each predetermined scanning section, and the correction calculating means 11 calculates the count value of each section. Since the correction is performed based on the corresponding counting time, an accurate diffracted X-ray intensity in each section can be obtained, and the X-ray diffraction analysis can be performed quickly and accurately by continuous scanning. Moreover, the frequency divider 16 is not based on the pulse to the pulse motor that drives the interlocking means 20,
Since a read command is issued based on the signals A and B from the high-resolution rotary encoder 30 provided on the main shaft of the interlocking means 20, every predetermined scanning interval occurs due to a mechanical processing error or backlash in the interlocking means 20. The count value of each section including the instability of the counting time is corrected, and more accurate X-ray intensity of each section can be obtained. In X-ray diffraction analysis, rapid and more accurate analysis can be performed by continuous scanning. It can be carried out.

Further, in the conventional measurement by the step scan, it takes a long time, and an error of the minimum resolution of the rotary encoder occurs in positioning at a specified angle to be stopped for a certain time for counting (see FIG. 4). If
1/10000 when B phase is OFF and A phase is ON
In the range of degrees X, it is not possible to specify where it has stopped)
However, in the device of this embodiment, the rotary encoder 3
A-phase edge of signal from 0 (moment of rising edge)
Is detected and a read command is issued, so that such an error does not occur.

[0033]

As described above in detail, according to the present invention, the counting time for each predetermined scanning section is obtained by the counting time counter and the frequency divider, and the correction operation means corresponds to the count value of each section. Since the correction is performed based on the counting time, accurate X-ray intensity in each section can be obtained, and in X-ray analysis, quick and accurate analysis can be performed by continuous scanning.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a fluorescent X-ray analyzer according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a relationship between a scanning range (2θ) and a scanning speed in a goniometer (an interlocking unit).

FIG. 3 is a schematic diagram illustrating an X-ray diffraction apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a signal from a rotary encoder in the device.
FIG. 7 is a diagram illustrating an example of a relationship between a phase signal and a read command issued by a frequency divider.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... sample, 2 ... sample stage, 3 ... primary X-ray, 4 ... X-ray source, 5
... X-ray fluorescence generated from the sample, 6 ... Spectroscopy element, 7 ... X-ray fluorescence separated by the spectroscopy element, 8 ... Detector, 10, 20 ...
Interlocking means, 11 correction operation means, 13 pulse height analyzer, 1
4 scaler, 15 counting time counter, 16 frequency divider, 23 incident X-ray, 27 diffraction X diffracted by the sample
Line, 30 ... Rotary encoder.

Continued on the front page (72) Inventor Toshiyuki Kato 3-9-1, Matsubara-cho, Akishima-shi, Tokyo F-term in Rigaku Electric Co., Ltd. (reference) 2G001 AA01 BA04 BA18 CA01 EA01 EA03 GA01 GA06 GA13 HA01 JA06 JA08 KA01 PA12 SA07

Claims (3)

[Claims] A sample stage on which a sample is placed; an X-ray source for irradiating the sample with primary X-rays; a spectroscopic element for separating fluorescent X-rays generated from the sample; Fluorescent X-rays are incident, and fluorescent X
A detector that generates a number of voltage pulses according to the intensity of the X-rays in accordance with the intensity; and changing the wavelength of the fluorescent X-rays separated by the spectroscopic element, and converting the separated fluorescent X-rays to the detector. Interlocking means for intermittently scanning the spectroscopic element and the detector so as to be incident so as to interlock, a wave height analyzer for selecting a pulse generated by the detector within a predetermined voltage range, and a wave height thereof. A scaler for calculating a count value of the pulses selected by the analyzer, a count time counter for measuring a count time required for counting pulses by the scaler, and a read command for each predetermined scanning section in the interlocking means. A frequency divider that generates the signal, and receives a read command from the frequency divider, reads the count value obtained by the scaler and the count time measured by the count time counter, and counts the count value by the count time. X-ray fluorescence analyzer and a correction calculating means for correcting, based. 2. A sample table on which a sample is mounted, an X-ray source for irradiating the sample with incident X-rays, a diffracted X-ray diffracted by the sample is incident, and a voltage corresponding to the energy of the diffracted X-rays is applied. A detector that generates pulses by the number corresponding to the intensity, and continuously scans the sample stage and the detector in conjunction with each other so that the diffracted X-rays are incident on the detector while rotating the sample stage. Interlocking means for causing a pulse height analyzer to select a pulse having a predetermined voltage range among the pulses generated by the detector; a scaler for calculating a count value of the pulse selected by the pulse height analyzer; and a pulse generated by the scaler. A counting time counter for measuring a counting time required for counting, a frequency divider for issuing a read command for each predetermined scanning section in the interlocking means, and receiving a read command from the frequency divider, Seeking with a scaler Count value and reads the counting time measured by the count time counter, X-rays diffractometer equipped with a correction calculation means for correcting, based a count value in the counting time. 3. The X-ray analyzer according to claim 1, wherein the frequency divider issues the read command based on a signal from a rotary encoder provided on a main shaft of the interlocking means.