JPS61250528A - Apparatus for analyzing emission spectrum - Google Patents

Abstract

PURPOSE:To attain to smoothly perform spectral analysis at a high speed with high accuracy, by constituting the titled apparatus so as to successively scan analogue switches having different amplifying degrees from one having a larger amplifying degree. CONSTITUTION:The output of one selected analogue switch 15 for analytical measurement enters the input side of each of four independent analogue switches 16. Four outputs of shift registers 24 are scanned in synchronous relation to the clock inputted to the shift registers 24 in the order of (e), (f), (g) and (h). Each output is connected to each of inverters 22 to successively transfer the scanning of the analogue switches 16 from the switch in the connection side of a resistor R to the switch in the connection side of a resistor 512R. That is, scanning is in the order from the analogue switch having a large amplifying degree to one having a small amplifying degree and the unsaturated value of an A/D converter 33 is detected by a logical circuit 32. By this method, spectral analysis can be smoothly performed at a high speed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an optical emission spectrometer that simultaneously analyzes many types of metal elements, and particularly to an optical emission spectrum analyzer that utilizes plasma emission.

[Background of the invention]

As a conventional emission spectrum analyzer, for example, the one shown in FIG. 1 of Japanese Unexamined Patent Publication No. 151026/1982 is known.

In such a conventional device, each amplifier is connected in series in a cascade, so the offset of each amplifier! i
It is troublesome that the adjustment must be performed in an orderly and precise manner starting from the amplifier side closest to the input. Further, the offset voltage and current that depend on temperature changes in the first stage amplifier are amplified in the next stage, and affect the subsequent amplifiers. Further, the output selected at the non-saturated position is digitized by the A/D converter 32, and is digitized by the A/D converter 32 via the buffer circuit 34.
The measured spectrum is read in and processed by the 1 display device 36, but the spectrum recording is subject to the above-mentioned disadvantage of drift due to the temperature dependence of the first-stage amplifier and the disadvantage of switching steps each time the amplifier is switched. Creates a natural step. Furthermore, this conventional method uses a four-stage amplification switching method to obtain one A/D conversion value, which requires four times the sum of software discrimination time and hardware processing time. It is unsuitable for signal processing in emission spectrum analyzers that require high-speed sampling. Furthermore, temperature drift and noise have the disadvantage that their baseline is superimposed as a background level, causing instability in accuracy.

[Purpose of the invention]

The purpose of the present invention is to overcome the above-mentioned drawbacks of the prior art.
An object of the present invention is to provide an emission spectrum analyzer that can obtain smooth spectrum analysis results at high speed and with high precision.

[Summary of the invention]

The present invention automatically switches the amplification degree of the amplifier using a scanning method, and determines the saturation value of the A/D conversion capacitance by hardware without relying on computer software processing. High-speed signal processing is possible. Furthermore, the present invention can measure the reference voltage for each type of amplification degree and correct the amplification degree. At the same time, the reference zero point is also automatically recognized.

It also has a number of functions that can correct zero point deviations.

[Embodiments of the invention]

FIG. 1 is a system diagram of an emission spectrum analysis signal processing device according to an embodiment of the present invention, and FIG. 2 is a time chart illustrating the present invention in detail. In FIG. 1, a high frequency magnetic field is applied from a high frequency generating power supply 1 to a plasma torch 2 through an induction coil, and a mixture of the mist of a sample 3 and argon gas 4 is supplied to the plasma torch 2. The flame of the torch is about 70
The temperature also rises to 00C'. Plasma generation torch 2
Drain liquid that is not burned inside is stored in a drain tank 5. Light from the center of the flame necessary for analysis generated in the upper part of the torch 2 is condensed by a lens 6, passes through an entrance slit, is bent by a reflecting mirror 7, and enters a collimating mirror 9. The light beam reflected by the mirror 9 and made parallel is incident on the planar grating 8 and diffracted, and the spectral light of each element is selected, focused by the second collimating mirror 10, and detected by the photomil 11.

Next, the measurement and analysis operation of the present invention will be explained in detail below. In order to select the output of the preamplifier 13, it is input from the microcomputer 35 to the temporary storage circuit 23 through the data line and sends a switch selection signal. At the same time, the microcomputer 35 sends an address signal to the address decoder 30 from the address line. The decoder 30 latches data as a temporary storage command to the temporary storage circuit 23 instead of the command signal. This operation drives the output of input/<-> 21 (selects one switch for 7 analysis measurements).

The output of the selected switch 15 enters the input side of each of four independent analog switches 16. Next, the microcomputer 35 passes through the decoder 30 to the inverter 25.
clears the shift register 24. On the other hand, the decoder 30
The same output signal a )(enters the pulse generator 26.) The pulse generator 26 generates a pulse b, and a trigger is applied to the T terminal of the flip-flop 28 at a time delayed by the pulse width. .

The output C of the Q of the flip-flop 28 is set to H'' level.This is input to one side of the gate 27, and a shift clock pulse is generated from the oscillator 29 at the other input.

This clock pulse d passes through the gate 27 and is shifted to the shift register 24 by the clock signal, the clock signal, and the output signal of the shift register 24 (M).
go shift in hQ order) (/enter the raster 24 and scan the output in synchronization with 512R connection side.Scanning is performed in order from the so-called higher degree of amplification to the lower one.At the same time, the output of the shift register 24 is sent to the buffer circuit 34 as a switch ON or OFF state signal of the analog switch 16. This is necessary to signal the switching state position of the amplification degree. Also, the main amplifier 17
The analog signal enters the A/D converter 33. For the A/D conversion operation, the shift clock d, which is the output of the gate 27, is also input to the A/D converter 33 as an A/D start signal. At this point, A/D conversion is performed, and the converted value is 12
A digital quantity i of bits enters buffer circuit 34. On the other hand, the upper 8 bits i enters the 8-person logical product circuit 32,
When all upper 8 bits are ``H'' V-pel, logic circuit 3
2 output is "L# novell)," the gate circuit 31 inhibits the A/DEND signal j output from the A/D converter 33.Furthermore, the A/D E N D signal enters the microcomputer 35. Notifies the completion of A/D conversion. By scanning the analog switch 16 as explained above, the amplification degree of the amplifier 17 is increased by 512 times.

Switching from 64 times, 8 times, 1 times, the one with higher amplification, A
The logic circuit 32 detects a value at which the /D converter 33 is not saturated. For example, when any one pit of the output i of the A/D converter 33 becomes "L" level, the output of the logic circuit 32 becomes "
'H'V bell and A/D from A/D converter 33
The END signal j passes from the gate 31 to the gate 37 and enters the flip-flop 28 P.
The output signal C of the gate 27 is set to 'L' level.
inhibits the gate, ends the shift operation, and stops scanning the switch. On the other hand, the fcj signal passing through the gate 31 at this time is notified to the IRQ interrupt signal of the microcomputer 35 as a data read signal. Also A/DEND
The signal j notifies the microcomputer 35 that the A/D has been completed and enables reading. The microcomputer 35 outputs I10 at Vs to the address decoder 30, and the address decoder 30 opens the buffer gate of the buffer circuit 34 according to the command, and reads the measured and analyzed digital quantity into the microcomputer 35.

The read data is displayed on the display device 36 with the horizontal axis representing the measurement wavelength and the vertical axis representing the number of elements. FIG. 2 shows a time chart for the above explanation. In addition, the present invention temporarily stores data from the microcomputer 35 in the temporary storage circuit 23, selects the inverter 21, and turns on the analog switch 151r connected to the reference voltage diode 14°, so-called vl+, before measuring the analysis data. Select from the larger one and select the four amplification values from the microcomputer 3.
5 and corrects amplification errors due to variations in resistance values and automatically adjusts the gain to provide highly accurate amplification. The operation at this time is to output a Q output reset signal from the address decoder 30 to the P terminal of the 7-lip flop 38,
It enters the gate circuit 37. This signal inhibits the j signal from the A/D converter 33 and continues the shift operation, allowing the value of each amplification degree to be read and stored. Furthermore, the value V of the reference zero point. It performs automatic zero adjustment, stores electrical reference points, monitors drift, and constantly performs zero point correction. As described above, since the present invention uses the conventional cascade connection of four stages of amplification, the step in the spectral signal waveform due to the drift amplification switching error that depends on the temperature and k changes of the first stage amplifier is eliminated, and the A/ D conversion [(7) Since the saturation state does not depend on the judgment of the computer program, the time is unnecessary. For example, the conversion speed of the A/D converter 33 is 15
When using μ9eIi, the shift clock is 20μ
Can be set as an expression. The maximum processing time at this time is 4 clocks, which corresponds to 80 μm. In reality, most processes can be done within this value. Furthermore, the processing time can be further shortened by using a high-speed A/D converter 33 and increasing the clock frequency of the first oscillator 29. As described above, the emission spectrum analyzer of the present invention is capable of high-speed processing, provides an A/D conversion function with a large dynamic range that can accommodate a wide range of signal levels of input signals, and at the same time is capable of analyzing and measuring highly accurate values. Furthermore, since the circuit configuration does not require adjustment, it is simple and economical.

〔Effect of the invention〕

Since the present invention enables high-speed signal processing, it is possible to sample the same analog signal multiple times and find the average value, which is advantageous for improving S/N. In addition, the increase due to the influence of temperature drift on the amplification factor (1 # 1. The switching contact of the device has no steps, excellent linearity, and a smooth output waveform can be obtained. Also, the t offset due to the 6 amplifiers connected in parallel) There are few zero points due to

Furthermore, this function allows automatic zero point adjustment. In addition, the amplification degree of each stage can be automatically checked at any time using the reference voltage, and a wide range of input signals can be processed at high speed and with high accuracy.Furthermore, the circuit configuration is simple and economical. The present invention is also advantageous in that it provides an extremely effective emission spectrum analysis signal processing device for signal processing systems that analyze spectra of multiple elements.

[Brief explanation of the drawing]

FIG. 1 is an emission spectrum analysis signal processing device of the present invention, and FIG. 2 is a time chart illustrating the present invention in detail. 1...High frequency generation power source %2...Plasma generation torch, 3...Sample, 4...Argon gas, 5...Drainage tank, 6...Lens, 7...Reflection mirror, 8...G V iteng, 9゜10...Collimating mirror, 1
1... Photomaru, 12... High pressure generation circuit, 13...
- Preamplifier, 14... Reference voltage diode, 15.
16...Analog switch, 17.18, 19.20
...Main amplifier, 21°22.25...Inverter,
23... Temporary memory circuit, 24... Shift register,
26...Pulse generator. 28.38...F11 knob 7a knob, 29...Oscillator, 30...Atto Vs decoder, 27,31.37...
...Gate circuit, 32...8 human-powered AND circuit, 33.
・・A/D converter %34・・Buffer circuit, 35・・
- Microcomputer, 36...display device.

Claims (1)

[Claims] 1. An amplifier that amplifies the photoelectronic signal output from the photomal detector; a plurality of independent analog switches that operate with a clock from an oscillator and take in the signal from the amplifier;
An A/D converter for A/D converting the signal from this analog switch.
A D converter and an arithmetic processing unit that performs arithmetic processing on the output from the A/D converter, the plurality of analog switches have different amplification degrees, and are configured to sequentially scan from the one with the larger amplification degree. An emission spectrum analyzer characterized by: