JPS6047944A - Emission spectroscopic analytical apparatus - Google Patents

Abstract

PURPOSE:To enhance analytical efficiency while improving analytical sensitivity, by sampling photometric output in timing suitable for each element in one discharge, and integrating photometric outputs in a large number of times of discharges. CONSTITUTION:Photoelectric converter elements P1-Pn are arranged at bright line positions of elements to be respectively analyzed in the spectrum image surface of a spectroscope. Section integrators I1-In succeeding to the photoelectric converter elements are ones for taking in photometric outputs only during the application of a sampling pulse to integrate the same and the sampling pulse reset prior to the starting of integration is cooperated with the discharge operation in a spark discharge light emitting apparatus S and a trigger signal in synchronous relation to the trigger of spark discharge is applied to a sampling pulse generating circuit G. A multiplexer Mu completes one scanning of each of A/D converters ADC1-ADCn during one cycle of spark discharge while CPU discriminates the sampling photometric output of each element at every one discharge sent from the multiplexer Mu and inputs the same to the address corresponding to each element in memory Me to integrate the same.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention is an optical emission spectrometer using spark discharge as a light source, and is suitable for simultaneous analysis of multiple types of elements.

(B) Conventional technology In optical emission analysis using spark discharge, improvement in analytical sensitivity and analytical accuracy can be obtained by appropriately selecting discharge conditions. Two types of discharge conditions are normally selected: normal spark and arc-like spark.

A normal spark is a high voltage discharge with a short duration of about 60 microseconds, whereas an arc-like spark is a relatively low voltage discharge with a long duration of about 200 microseconds.

Carbon C2 Phosphorus P, Boron B, Arsenic A s, Sulfur S in steel
When using an arc-like spark, the sensitivity is improved by about 2 to 3 times compared to a normal spark. On the other hand, normal spark is suitable for analyzing silicon S1, manganese Mn, etc. in steel.

For this reason, when performing multi-element analysis on a single sample, the conventional method was to divide the analysis into two stages, with the first stage performing analysis using normal spark, and the second stage performing analysis using arc-like spark. . An example of such an analysis schedule is shown in FIG. In this figure, A is the pre-discharge period to clean the sample surface and stabilize the luminescence, B is the analysis period using normal spark, C is the pre-discharge period before performing arc-like spark, and D is analysis using arc-like spark. It is a period.

In each analysis period, the photometric output from several hundred discharge light emissions is integrated, so it takes about 5 seconds, and a two-stage analysis requires at least about 10 seconds.

In quality control in the production process, it is necessary to analyze a large number of samples in a short period of time, and it is difficult to save time by spending more than 10 seconds on each sample, so the time required for analysis is strongly reduced. desired. In addition, in two-stage analysis, when switching the discharge conditions midway through, the instantaneous discharge is stopped, so
Unexpected negative effects appear in the analysis results.

el) Purpose The present invention applies discharge conditions suitable for various elements, and
Moreover, by making it possible to analyze each element in a single stage of analysis, it is possible to analyze each element in a short time and with high sensitivity.

(d) Configuration The present invention uses a combined spark in which a normal spark and a subsequent arc-like spark are performed during one discharge, and sets the timing of photometric output sampling for each discharge to perform time-sharing during one discharge. Provided is a luminescence spectrometer that samples a plurality of photometric outputs and integrates these sampling data separately over the total number of discharges.

Figure 2 shows the photocurrent over time under various discharge conditions. Figure 3A shows the change in photocurrent in one combined spark example, where A is the normal spark region, B is the arc-like spark region, and photometric output sampling. If you set the timing as shown in Figure 3, you will get analysis data using normal spark, and if you set it as shown in Figure 3, you will get analysis data based on arc-like spark.By using both sampling pulses, In one stage of analysis, the analysis by normal spark and the analysis by arc-like spark are completed.

(e) Examples FIG. 4 shows the configuration of an apparatus according to an embodiment of the present invention.

P1 to Pn are photoelectric conversion elements, which are respectively installed at the emission line positions of the elements to be analyzed on the spectral image plane of a spectrometer (not shown). 11 to In are interval integrators that follow each photoelectric conversion element, and are integrators that receive and integrate the photometric output only while the sampling pulse shown in Figure 3 is applied. will be reset prior to. A
:I) C1, ~Ai) Cni-1: A/D converter,
After the integration operation of the corresponding integrator is completed, the integration output is changed to A /
D-convert. Mu is a digital multiplexer, each A
/ Sequentially take out the output data of the D converters ADC1 to ADCn and input them to the control computer CPU. The sampling pulse is interlocked with the discharge operation in the spark discharge light emitting device S, and a trigger signal synchronized with the spark discharge trigger is applied to the sampling pulse generation circuit G.

The sampling pulse generation circuit is a monomulti circuit group whose pulse width can be set independently, and generates a sampling pulse every - discharge and sends it to predetermined interval integrators 1 to In. The width and rise timing of each sampling pulse can be optimally set for each element by adjusting the width of the output pulse of the monomulti. The multiplexer M u connects each A/D converter A during one period of the spark discharge.
After completing one scan of DCI to ADCn, the CPU discriminates the integral data of the sampled photometric output of each element for each discharge sent from the multiplexer Mu, inputs it into the address corresponding to each element in the memory MO, and multiplies it by three. After a predetermined number of discharges have been completed, the CPU reads out the integrated data value for each element in the memo IJMe, displays it on the CRT, and prints it out using the printer R.

FIG. 5 shows an example of an interval integrator. A normal integrating circuit is formed by the operational amplifier OA and the capacitor C, and a reset FET is connected in parallel with the capacitor C.
SH is a sample and hold circuit. ” A reset pulse generated by a trigger signal and a subsequent sampling pulse (
Figure 3 A or Mouth is sent. Reset pulse uFE
It is applied to the gate of T, causing the FET to conduct and resetting the integrating circuit to continue integrating.

The sample and hold circuit has its entrance gate opened by the sampling pulse, takes in the output of the integration circuit, and holds the integration output just before the falling edge of the sampling pulse, and this held signal is sent to the A/D converter ADCI~ in Fig. 4. Input to ADC:n.

(f) Effects According to the present invention, the photometric output is sampled at a timing suitable for each element in the discharge, and the photometric output is integrated for many discharges, so that a wide variety of elements can be analyzed in one analysis period. can be analyzed using their respective optimal discharge conditions,
The analytical efficiency is improved compared to conventional multi-stage analysis, and the analytical sensitivity is good because optimum conditions are obtained for each element. Furthermore, since there is no discharge stop in the middle of multi-stage analysis, adverse effects caused by intervening discharge stops can be avoided.

[Brief explanation of the drawing]

Fig. 1 is a time chart of an example of a two-stage analysis schedule, Fig. 2 is a graph of luminescence curves due to various discharges, Fig. 3 is a graph showing luminescence curves and sampling pulses in a combined spark, and Fig. 4 is a graph of the luminescence curve of the present invention. FIG. 5, a block diagram of an embodiment, is a circuit diagram of an example of an interval integrator. P1~Pn...Photoelectric conversion element, ADC]~AD
Cn...A/D converter, CPU...control computer, Me...memory. Agent Patent Attorney Kosuke Agata

Claims (1)

[Claims] A spark discharge light emitting device that generates a combined spark including a normal spark and an arc-like spark during one discharge; a timing pulse generator that synchronizes with the spark discharge and sets arbitrary timing during one spark discharge; An interval integrator that follows the corresponding photoelectric converter and is controlled by the output pulse of the timing pulse generator and captures and integrates the photoelectric conversion output for a specific period during each discharge for each discharge, and each interval integrator. and integrating means for integrating the output of the output for a predetermined number of discharges.