JP5239892B2 - Luminescence analyzer - Google Patents

Description

  The present invention relates to an emission analyzer that excites a sample by so-called spark discharge such as spark discharge or arc discharge and performs spectroscopic measurement of the emitted light.

  In an emission spectrometer, generally, a solid sample that is a metal or a nonmetal is given energy by spark discharge or arc discharge, and the sample is evaporated and excited to emit light. Then, the emitted light is introduced into a spectroscope, a spectral line having a wavelength peculiar to each element is taken out, the intensity is detected, and the element in the sample is identified and the impurity in the sample is detected based on the detection result. Perform quantification. Such an emission analyzer is capable of highly accurate analysis, and is therefore widely used, for example, to analyze the composition of a produced metal body in a production factory for ferrous materials and non-ferrous metal materials.

  As disclosed in Patent Document 1 and the like, the above-mentioned emission analyzer has slits arranged at positions where wavelength-dispersed light of each wavelength reaches in order to obtain spectral lines having wavelengths peculiar to a plurality of elements, respectively. Multiple photodetectors (usually photomultiplier tubes) that detect the light that has passed through, multiple integrators that integrate the photocurrent output from each photodetector in discharge units, and the signals integrated by each integrator A photometric unit including a switching unit that switches as appropriate, an analog / digital (A / D) converter that converts a signal selected by the switching unit into a digital value, and the like is provided. Further, as disclosed in Patent Document 2 and the like, a light receiving portion that detects light emission of a control discharge from the starting portion is attached to the discharge portion that discharges the sample, and based on a detection signal from the light receiving portion. The integration operation of the photometry unit is executed by a pulse signal synchronized with the actual discharge timing.

  In the emission analyzer as described above, since there are individual differences in circuit components such as the A / D converter and the capacitor used in the integrator included in the photometry unit, the ratio between the input and output of the photometry unit (hereinafter referred to as the following) This is called “gain”). That is, as shown in FIG. 3, the photometric unit has an inherent gain for each device, and an error (gain deviation) between the inherent gain and a design gain is different for each device. Due to such a gain deviation, the larger the input of the photometry unit, the larger the deviation between the designed output and the actual output.

  Therefore, conventionally, in order to reduce the influence of the gain deviation, the measurement data is corrected in accordance with the gain deviation amount for each individual apparatus obtained by the manufacturer. In other words, the manufacturer of the emission analyzer, in the final adjustment stage of the device, performs discharge with the fixed value given to the input of the integrator and obtains the output of the photometry unit, thereby providing a unique photometry for each device. Measure the gain of the part. Then, correction data for correcting the gain deviation from this intrinsic gain is obtained and stored, and the measurement data acquired for the sample is corrected using the correction data.

However, these conventional gain deviation correction methods have the following problems.
(1) Conventionally, the device-specific gain is measured only during manufacturing. For this reason, fluctuations depending on the installation environment of the apparatus (such as ambient temperature) and changes with time of parts are not taken into consideration, and correction with sufficiently high accuracy may not be performed during actual sample measurement.
(2) Since it is necessary for the device manufacturer to determine the intrinsic gain for each integrator corresponding to each wavelength while actually discharging each device, the adjustment work is troublesome and troublesome.
(3) Since the discharge is actually performed when the intrinsic gain is measured, dust inside the device is burned into the lens that collects the emitted light during the discharge, and the contamination is removed before the device is shipped. Cleaning work is required. In addition, by repeating unnecessary discharge for adjustment, there is a possibility that the life of electrical components such as a relay of the discharge part may be shortened.

  In addition to the above-described gain deviation correction, there is a similar problem with the offset correction of the photometry unit. In other words, a minute value appears in the output of the photometry unit even when there is no light emitted from the sample due to the dark current of the photodetector, and this becomes an offset error. In order to reduce such an offset error, conventionally, as in the case of the above-described intrinsic gain, the device manufacturer sets the measurement sensitivity as low as possible and sets the measurement time as short as possible in the final adjustment stage of the device. The discharge is performed under the condition that the incident light to the detector can be regarded as almost zero, and the offset amount is measured by obtaining the output of the photometry unit. Then, correction data for correcting the offset is obtained from the offset amount, and the measurement data acquired for the sample is corrected using the correction data. However, the problems (1) to (3) mentioned above as the correction method for the gain deviation are the same for the offset correction.

JP-A-6-281580 (FIG. 1, paragraphs 0008-0009) JP-A-8-210980 (FIG. 4, paragraph 0018)

  The present invention has been made to solve the above-mentioned problems, and its purpose is to correct the difference between the intrinsic gain of the photometric unit and the design gain and the offset of the photometric unit with high accuracy, It is an object of the present invention to provide an emission analyzer that eliminates the need for troublesome measurement and adjustment work in the manufacturing stage for such correction, and that can also avoid problems associated with discharge.

In order to solve the above problems, the present invention includes a discharge unit that discharges a predetermined region on a sample surface, a photodetector, and an integrator, and splits light emitted from the sample by the discharge. A photometric unit that performs photometry, and that integrates the output of the photodetector with the integrator in synchronization with a discharge notification signal output from the discharge unit in accordance with an actual discharge at the discharge unit In the device
a) control means for sending a pseudo-discharge notification signal corresponding to the discharge notification signal to the photometry unit;
b) integration input setting means for giving a fixed input to the integrator instead of the output of the photodetector;
c) an intrinsic gain acquisition means for obtaining an intrinsic gain of the photometry unit using an output obtained by the photometry unit in synchronization with the pseudo-discharge notification signal with respect to the fixed input;
d) correction means for correcting the signal obtained by actual measurement on the sample based on the difference between the intrinsic gain obtained by the intrinsic gain obtaining means and the designed gain;
The control means repeatedly sends a pseudo-discharge notification signal a predetermined number of times, the integral input setting means sequentially gives a plurality of different input values to the integrator, and the intrinsic gain acquisition means is based on the same measurement condition The measurement is performed for each of the plurality of different input values, and the intrinsic gain of the photometry unit is obtained based on the result .

In the emission analysis apparatus according to the present invention, the integrator of the photometry unit is fixed input given by the integral input setting means in synchronization with the pseudo discharge notification signal given from the control means without actually performing discharge. Perform the integration of. Since the intrinsic gain of the metering unit is obtained from the relationship between this fixed input and the output of the metering unit, the difference between this intrinsic gain and the designed gain, that is, the gain deviation is also obtained, and the correction means eliminates the gain deviation. Thus, the signal obtained by actual measurement of the sample is corrected.
In particular, in the emission analysis apparatus according to the present invention, the integral input setting unit sequentially gives a plurality of different input values, and the intrinsic gain acquisition unit performs measurement for different input values based on the same measurement condition, Since the characteristic gain is calculated based on the result, even if there is nonlinearity in the relationship between the input and output of the photometry unit, the characteristic gain that reflects the nonlinearity is obtained and the gain deviation is corrected well. Can do.

In the emission analysis apparatus according to the present invention, preferably, after the actual measurement conditions (discharge conditions and the like) for the sample are set, the intrinsic gain is acquired by the intrinsic gain acquisition means before the measurement for the sample is performed, Based on the difference between the intrinsic gain and the designed gain, it is preferable to correct the signal obtained by the actual measurement for the sample to be subsequently executed.

  According to this configuration, the latest intrinsic gain is acquired prior to each actual measurement of the sample, so correction of gain deviation that reflects the time-dependent changes in the installation environment and circuit of the device Is done.

In emission analyzer according to the present invention, the control means of the pseudo discharge notification signal a predetermined number of times repeatedly sent, the inherent gain acquisition unit executes a plurality of measurements for one fixed input values based on the same conditions it may be the measurement result obtained the configuration for the one input value based on the result.

  According to this configuration, variation in the output value of the photometry unit with respect to a fixed input value is reduced, so that the gain deviation can be corrected more accurately.

According to the emission analyzer according to the present invention, on the user side instead of the manufacturer side, the intrinsic gain and offset of the photometry unit are measured under the same conditions as in actual measurement without actually performing discharge, and the gain deviation And offset correction can be performed. That is, it is not necessary to actually discharge the discharge unit in order to acquire the intrinsic gain and offset of the photometry unit, and it is only necessary to output a pseudo discharge notification signal from a control means generally constituted by a microcomputer or a hardware circuit. Therefore, it is possible to avoid problems associated with discharge, such as contamination of the condenser lens due to burning of dust or the like, and shortening of the life of the relay for discharge. Moreover, since it becomes easy to employ inexpensive electrical components that have a relatively large change with time, it is advantageous in reducing the cost of the apparatus.

  In addition, by measuring the intrinsic gain and offset of the photometric unit prior to actual measurement of the sample, the latest intrinsic characteristics that reflect all the measurement conditions such as the installation environment and measurement sensitivity, and the changes over time of the circuit are all reflected. Gain and offset can be measured and corrected. As a result, gain deviation and offset can be corrected with higher accuracy than before, and the accuracy of identification and quantification can be improved.

  In addition, for the device manufacturer, it is not necessary to perform measurement and adjustment based on the intrinsic gain and offset for each device in the manufacturing stage, and the manufacturing cost can be reduced.

The block diagram of the principal part of the emission spectrometer which is one Example of this invention. 5 is a control / processing flowchart for the correction operation of the photometry unit in the emission analyzer of the present embodiment. The conceptual diagram which shows the relationship between the intrinsic gain of the photometry part in a light emission analyzer, and the design gain.

  An embodiment of an emission analyzer according to the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of a main part of an emission analyzer according to the present embodiment.

  In this emission analyzer, the discharge unit 1 can generate one or both of spark discharge and arc discharge, and the discharge conditions (applied voltage, voltage application time, voltage application pattern, etc.) set by the discharge condition setting unit 2 ) To discharge a predetermined small area on the sample S. Although not shown, the discharge unit 1 includes an ignition circuit and a light receiving unit that receives light emitted by the ignition spark, and outputs a discharge notification signal synchronized with the actual discharge occurrence timing by a detection signal of the light receiving unit.

  Due to the discharge, a minute region on the sample S is excited and emitted, and the emitted light is introduced into the spectroscope 4 through the condenser lens 3 and wavelength-dispersed. The spectroscope 4 has a Paschen-Lunge configuration, and includes an entrance slit, a concave diffraction grating, and a plurality of exit slits arranged on a Roland circle, although not shown. The plurality of exit slits are positions where wavelength light unique to each specific element of the wavelength-dispersed light (here, the wavelengths are λ1, λ2, and λ3, but the number of wavelengths may be four or more). Is arranged. Single-wavelength light extracted from each exit slit of the spectroscope 4 is introduced into different photodetectors 5 a, 5 b, and 5 c included in the photometry unit 13. The photodetectors 5a, 5b, and 5c are typically photomultiplier tubes, and all generate photocurrents according to the intensity of incident light.

  Integrators 6a, 6b, and 6c are individually provided corresponding to the photodetectors 5a, 5b, and 5c, and current signals from the photodetectors 5a, 5b, and 5c are set from this signal and the input value setting unit 12. Are input to the integrators 6a, 6b, and 6c through the switching unit 7 that alternatively selects the fixed value to be selected. The integrators 6a, 6b and 6c integrate the current signal generated at each discharge, and the integration condition setting unit 9 sets the integration start timing and integration end timing for one discharge. One of the integration values by the integrators 6 a, 6 b, 6 c is selected in a predetermined order by the switching unit 8, converted into a digital value by the A / D converter 11, and input to the data processing unit 20.

  The discharge notification signal supplied from the discharge unit 1 and the pseudo-discharge notification signal supplied from the control unit 24 are selected by the switching unit 10 and input to the integration condition setting unit 9 as a signal notifying the timing of discharge. However, as described above, the discharge notification signal is a signal corresponding to the actual discharge from the discharge unit 1 to the sample S, whereas the pseudo discharge notification signal does not perform the actual discharge. A timing signal similar to that at the time of discharging is given in a pseudo manner.

  The data processing unit 20 includes a data storage unit 21, an averaging calculation unit 22, a correction calculation unit 23, and the like. The control unit 24 controls the operation of the data processing unit 20 and each of the above-described units. The control unit 24 displays an input unit 25 in which a user can set discharge condition parameters and various parameters described later, and a discharge profile waveform. A display unit 26 is attached. The data processing unit 20 and the control unit 24 can be realized centering on a personal computer, for example.

  In the emission analyzer of the present embodiment, automatic gain deviation correction and automatic offset correction of the photometry unit 13 are executed prior to performing analysis on the target sample. A control / processing procedure for this automatic correction will be described with reference to the flowchart of FIG.

  The measurer inputs and sets various measurement conditions such as the number of repeated measurements for one minute region on the sample S, the measurement cycle, the discharge power, and the integration time condition together with parameters necessary for the analysis of the target sample. To do. At this time, the offset acquisition measurement number n and the intrinsic gain acquisition measurement number m are also input and set (step S1). Note that the offset acquisition measurement number n and the intrinsic gain acquisition measurement number m may be values held in advance by the control unit 24 or the integration condition setting unit 9.

  When the measurer instructs the start of analysis (step S2), the control unit 24 first controls each unit to execute the offset measurement operation (step S3). That is, first, the switching unit 7 is switched to the photodetectors 5a, 5b, and 5c, and the outputs of the photodetectors 5a, 5b, and 5c are input to the integrators 6a, 6b, and 6c. Further, the integration condition setting unit 9 sets the measurement sensitivity of the photometry unit 13 including the integrators 6a, 6b, 6c and the like as low as possible, and sets the integration time as short as possible (step S4).

  Then, with the switching unit 10 switched to the control unit 24 side, the control unit 24 outputs a pseudo-discharge notification signal (step S5). The pseudo discharge notification signal is input to the integration condition setting unit 9 through the switching unit 10, and the integration condition setting unit 9 receives the pseudo discharge notification signal and gives an integration start instruction to each integrator 6a, 6b, 6c. Further, when the integration time according to the integration condition parameter elapses, an instruction to end integration is given to each integrator 6a, 6b, 6c. Since the discharge unit 1 does not discharge and light is not incident on the photodetectors 5a, 5b, and 5c, the integrators 6a, 6b, and 6c are connected from the integration start instruction time to the integration end instruction time. During the period, the outputs of the photodetectors 5a, 5b, and 5c are integrated (step S6). Ideally, the dark current signal in each of the photodetectors 5a, 5b, and 5c is integrated (when the incident light to the photodetectors 5a, 5b, and 5c is completely zero). In general, the light other than the light passing through the exit slit is not incident on the photodetectors 5a, 5b, and 5c so as not to be affected by external light. However, a mechanical shutter or the like is used to further improve the light shielding property. May be provided immediately before the photodetectors 5a, 5b, and 5c.

  When the integration operation in the integrators 6a, 6b, 6b for one pseudo discharge notification signal is completed, the integration values are sequentially selected by the switching unit 8 and converted into digital values by the A / D converter 11 (step S7). ) And stored in the data storage unit 21 of the data processing unit 20 (step S8). The control unit 24 determines whether or not the pseudo-discharge notification signal has been repeatedly output for the number of acquisitions n set as the integration condition parameter (step S9), and returns to step S5 if the predetermined number n has not been reached. Therefore, by repeating steps S5 to S9, n integrated value data corresponding to n pseudo discharge notification signals under the condition that no light is incident on the photodetectors 5a, 5b, and 5c are stored in the data storage unit 21. Stored in

  When n pieces of integral value data are obtained, the control unit 24 next controls each unit so as to execute the intrinsic gain measurement operation (step S11). That is, the switching unit 7 is switched to the input value setting unit 12 side, and a predetermined fixed value is output from the input value setting unit 12 to the integrators 6a, 6b, and 6c. Also, the integration condition parameter is sent to the integration condition setting unit 9, and the integration condition setting unit 9 sets the integration condition parameter in the integration condition setting unit 9 (step S12).

  Then, with the switching unit 10 switched to the control unit 24 side, the control unit 24 outputs a pseudo discharge notification signal (step S13). The pseudo discharge notification signal is input to the integration condition setting unit 9 through the switching unit 10, and the integration condition setting unit 9 receives the pseudo discharge notification signal and gives an integration start instruction to each integrator 6a, 6b, 6c. Further, when the integration time according to the integration condition parameter elapses, an instruction to end integration is given to each integrator 6a, 6b, 6c. Each integrator 6a, 6b, 6c integrates an input, that is, a fixed value, from the integration start instruction time to the integration end instruction time (step S14).

  When the integration operation in the integrators 6a, 6b, and 6b for one pseudo discharge notification signal is completed, the integration values are sequentially selected by the switching unit 8 and converted into digital values by the A / D converter 11 (step S15). ) And stored in the data storage unit 21 of the data processing unit 20 (step S16). The control unit 24 determines whether or not the pseudo-discharge notification signal has been repeatedly output for the number of acquisitions m set as the integration condition parameter (step S17), and returns to step S13 if the predetermined number of times m has not been reached. Therefore, m pieces of integrated value data for m times of pseudo discharge notification signals are stored in the data storage unit 21 by repeating steps S13 to S17.

  When necessary integral value data is stored in the data storage unit 21, the averaging calculation unit 22 reads n pieces of integral value data previously stored in the data storage unit 21, calculates the average value, and calculates the average value. The value data is stored in the data storage unit 21 as offset data Q (1) (step S18). In addition, when calculating the average value, a simple addition average of n pieces of integral value data may be taken, but extremely excessive or excessive data that deviates extremely from the distribution of the integral value data values is removed first. Then, an appropriate modification such as calculating an average value can be added.

  Subsequently, the averaging calculation unit 22 reads m pieces of integral value data stored in the data storage unit 21, calculates the average value thereof, and sets the average value data as fixed input data P (1) in the data storage unit 21. save. It should be noted that, as described above, it is possible to add an appropriate modification such as first removing extremely excessive or excessive data when calculating the average value.

  Next, the intrinsic gain (inclination) of the photometry unit 13 is obtained for each wavelength from the zero point and the fixed input data P (1), and is stored in the data storage unit 21 as intrinsic gain data P (2) (step S19). . However, the intrinsic gain is obtained at these two points when the intrinsic gain of the photometry unit 13 can be regarded as having linearity. When the intrinsic gain has nonlinearity, the input value setting unit 12 has a plurality of fixed gains. Prepare a value, execute n times of pseudo discharge notification signal while changing the fixed value and perform integration according to it, calculate the average value of the integrated value data, and calculate the intrinsic gain from the multiple fixed input data It is good to ask for.

  If the intrinsic gain data P (2) and the offset data Q (1) are obtained as described above, the emission analysis of the sample S is performed according to the original measurement conditions (step S20). That is, the switching unit 7 selects the outputs of the photodetectors 5a, 5b, and 5c, and the switching unit 10 selects the discharge unit 1 side. When the control unit 24 instructs the discharging unit 1 to start discharging, the discharging unit 1 repeats discharging a predetermined number of times in a predetermined cycle according to the discharging condition set by the discharging condition setting unit 2. When the discharge unit 1 actually discharges, a discharge notification signal is output each time a discharge is performed. Therefore, the integration condition setting unit 9 outputs an integration start signal and an integration end signal corresponding to the discharge notification signal. Output to the integrators 6a, 6b and 6c, and integrate current signals based on the light emitted from the sample S corresponding to the discharge.

  The integral values are sequentially selected by the switching unit 8, converted to a digital value by the A / D converter 11, and stored in the data storage unit 21 of the data processing unit 20. When integrated value data corresponding to a predetermined number of discharges is collected, the averaging calculation unit 22 reads the integrated value data stored in the data storage unit 21 and calculates the average value. Further, the correction calculation unit 23 reads the inherent gain data P (2) and the offset data Q (1) from the data storage unit 21, and executes a calculation for correcting the gain deviation and the offset between the inherent gain data and the design value. This is stored in the data storage unit 21 as final measurement data (step S21). Since measurement data corrected for each wavelength is obtained, the data processing unit 20 executes identification and quantitative analysis based on the measurement data, and the result is displayed on the display unit 26.

  The above-described embodiment is an example of the present invention, and it is a matter of course that modifications, corrections, and additions may be appropriately made within the scope of the present invention, and included in the scope of the claims of the present application.

DESCRIPTION OF SYMBOLS 1 ... Discharge part 2 ... Discharge condition setting part 3 ... Condensing lens 4 ... Spectroscope 5a, 5b, 5c ... Photo detector 6a, 6b, 6c ... Integrator 7, 8, 10 ... Switching part 9 ... Integration condition setting part DESCRIPTION OF SYMBOLS 11 ... A / D converter 12 ... Input value setting part 13 ... Photometry part 20 ... Data processing part 21 ... Data storage part 22 ... Averaging calculating part 23 ... Correction calculating part 24 ... Control part 25 ... Input part 26 ... Display part

Claims (3)

A discharge unit that discharges in a predetermined region on the sample surface; and a photometry unit that includes a light detector and an integrator, and that splits and measures light emitted from the sample by the discharge, the discharge unit In the emission analysis device that integrates the output of the photodetector with the integrator in synchronization with the discharge notification signal output from the discharge unit according to the actual discharge of
a) control means for sending a pseudo-discharge notification signal corresponding to the discharge notification signal to the photometry unit;
b) integration input setting means for giving a fixed input to the integrator instead of the output of the photodetector;
c) an intrinsic gain acquisition means for obtaining an intrinsic gain of the photometry unit using an output obtained by the photometry unit in synchronization with the pseudo-discharge notification signal with respect to the fixed input;
d) correction means for correcting the signal obtained by actual measurement on the sample based on the difference between the intrinsic gain obtained by the intrinsic gain obtaining means and the designed gain;
The control means repeatedly sends a pseudo-discharge notification signal a predetermined number of times, the integral input setting means sequentially gives a plurality of different input values to the integrator, and the intrinsic gain acquisition means is based on the same measurement condition And measuring the plurality of different input values, and determining the intrinsic gain of the photometric unit based on the results . The emission analyzer according to claim 1,
After the actual measurement conditions for the sample are set, the intrinsic gain is acquired by the intrinsic gain acquisition means before the measurement for the sample is executed, and the execution is continued based on the difference between the intrinsic gain and the designed gain. A light emission analyzing apparatus for correcting a signal obtained by actual measurement on a sample to be measured. The emission analyzer according to claim 1 or 2,
Before SL intrinsic gain acquisition means, based on the same condition to perform a plurality of measurements for one fixed input values, emission spectrometry, characterized in that to obtain measurement results for the one input value based on the results apparatus.

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