JP2001153804A - Fine particle constituent analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine particle constituent analyzer for signal processing, which does not result in a time delay, without depending on a type of a filter. SOLUTION: In this fine particle constituent analyzer, a fine particle is emitted for spectral diffraction. A wavelength after spectral diffraction is converted to an electrical signal and amplified. An output signal is inputted and wavelength screened. A size of the fine particle is computed by a computing means from the screened signal. The computing means is provided with a time delay correction means. The time delay correction means corrects the time delay of the output signal caused by the noise filter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine particle component analyzer for analyzing the components of fine particles, and more particularly to a fine particle component analyzer capable of analyzing components of a compound or a substance in which different elements are combined.

[0002]

2. Description of the Related Art For example, fine particle component analysis in which fine particles floating in the air are sucked together with air, the fine particles are collected on a filter, and the number and size of elements constituting the fine particles are measured by using microwave induction plasma. Devices are known.

[0005] FIG. 5 is a diagram showing the configuration of a main part of a fine particle component analyzer utilizing such microwave induced plasma. In the figure, reference numeral 51 denotes a filter unit, on which a filter 52 to which solid fine particles (not shown) to be measured are attached is disposed. 53 is an aspirator,
The solid fine particles attached to the filter 52 are sucked and the discharge tube 54
To supply. 55 is a microwave generator, and 56 is a cavity into which the microwave from the microwave generator 55 is introduced.

Reference numeral 57 denotes a spectroscope for taking in the light emitted from the discharge tube 54 through an optical fiber 80 and dispersing the light. In this example, four spectroscopes are provided. Reference numeral 58 denotes a photoelectric conversion unit provided at the subsequent stage of the spectroscope 57, for example, a photomultiplier tube is used. 61 is an operation means.

FIG. 6 (a) shows the flow of signal processing in such an apparatus. Light emitted using microwave-induced plasma enters a spectroscope 57, where a photomultiplier tube 58 and a preamplifier 59 are provided. , And the selected signal is output to the calculating means 61.

In this case, a method of cutting the DC component of the output signal of the photomultiplier tube 58 or the preamplifier 59 using a high-pass filter having a cut-off frequency of 10 Hz and a low-pass filter having a cut-off frequency of 750 Hz is used. Has adopted.

[0007]

In the above configuration, the output (point A) from the preamplifier 59 is shown in FIG.
As shown in FIG. 6B, the noise component h is included, and at the time of passing through the noise filter, the noise component decreases as shown by h ′ as shown in FIG. 6C.

There are about three types of noise filters depending on the type of element to be measured (eg, metal, organic substance, etc.).
As shown in FIG. 7, a time delay occurs depending on the type of the filter.

FIG. 7 assumes that compounds containing, for example, four kinds of elements emit light simultaneously and with the same intensity.
The horizontal axis represents time, the vertical axis represents output voltage, and the time delay due to the type of filter is schematically shown.

According to the figure, the output of the noise filter 3 is the earliest, and the output has a time delay in the order of 2, 1, 0 filters. For example, there is a problem that it cannot be recognized as a compound or a conjugate.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fine particle component analyzer for performing signal processing without time delay regardless of the type of filter.

[0012]

According to a first aspect of the present invention, there is provided an excitation / emission means for atomizing or ionizing fine particles to excite and emit light.
Spectral means for splitting a plurality of emitted lights having different wavelengths, a plurality of photoelectric conversion means for converting each of the split predetermined wavelengths into electric signals, and a plurality of amplifying each of the electric signals converted by the photoelectric conversion means A signal amplifying means, a plurality of noise filters for inputting each of the output signals from the signal amplifying means to remove noise, and fine particles for calculating the size of the fine particles from the signals selected by the plurality of noise filters by the calculating means In the component analyzer, the arithmetic means is provided with a time delay correcting means for correcting a time delay of an output signal caused by the noise filter.

According to a second aspect of the present invention, in the fine particle component analyzer according to the first aspect, the time delay correcting means compares the output of another filter with reference to the filter having the longest output among the known delay times different depending on the noise filter. The output is delayed based on the known delay time.

[0014]

FIG. 1 shows an example of an embodiment of the present invention, which is different from the conventional example shown in FIG. 6 only in that a time delay correcting means 70 is provided in an arithmetic means 61. FIG. Although not shown in the figure, time delay correction means (storage means)
Is provided with an A / D converter at the preceding stage.

The storage means is a schematic diagram showing a state in which the storage area of the storage element (ring buffer) moves over time as shown in FIG. The storage area is sequentially moved at the timing of A / D conversion. When the storage area is saturated, the process returns to the beginning and rewrites the stored contents.

FIG. 3 shows a method for judging the peak of the A / D converted output. That is, the peak judgment is A / D
A conversion is processed for a fixed time (in the example of the figure, the timing of A / D conversion is set to 90 μ / s), and a peak is recognized only when the increase level of the A / D value is equal to or more than a specified value and continues for 3 times or more. The peak voltage is determined as the voltage immediately before the A / D conversion value decreases.

In FIG. 3, since the voltage value increases from n1 to n4 and decreases to n5 and n6, the voltage value (V4) at n4 is recognized as the peak voltage, and the value is stored corresponding to the detection time. It will be written to the area.

FIG. 4A schematically shows the operation of the time delay correction means (storage means). Here, filters 0 and c are assigned to ch1 for four spectrometers (ch1 to 4).
Three types of filters, such as a filter 1 for h2 and a filter 3 for ch3 and ch4, are used. Also ... 100-1
07 ... are the time axes (A / A) corresponding to the storage area of the storage means.
2 shows a sampling cycle of the D converter.

In this case, it is assumed that the output peaks detected in ch1 to ch3 emit light at the same time, and the filter is provided so that the peak of ch3 is at the timing of 101 and the peak of ch2 is at the timing of 102. ch1
Is detected at the timing of 106.

Note that ch4 is an output peak that does not emit light simultaneously. It is assumed that the delay time that differs depending on the filters 0 to 3 is measured in advance and known as described later.

In the present invention, based on the filter 0 having the largest time delay, 4 corresponding to four sampling timings is added to the output peak of the filter 2, and 5 corresponding to five sampling timings is added to the output peak of the filter 3.
4 and output to the PC 62 (see FIG. 1) at the timing of 106 as shown in FIG. Since the output of ch4, which does not emit light at the same time, is filtered by the filter 3, the sampling timing 5 is added and the output is output to the PC 62 at the timing of 108.

It is to be noted that the above description of the present invention has been presented by way of illustration and example only of a particular preferred embodiment. Thus, it will be apparent to one skilled in the art that the present invention may be modified or modified in many ways without departing from its essentials. For example, although the number of spectroscopes has been described as four, it is not limited to this number.

[0023]

As described above in detail, according to the present invention, fine particles are emitted and separated, the separated wavelength is converted into an electric signal, amplified, the output signal is input, and wavelength selection is performed. In the fine particle component analyzer that calculates the size of the fine particles from the signal by the calculating means, the calculating means is provided with the time delay correcting means for correcting the time delay of the output signal caused by the noise filter. Therefore, it is possible to realize a particle analyzer for performing signal processing without noise.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an embodiment of a fine particle component analyzer of the present invention.

FIG. 2 is a diagram illustrating a method of determining a peak of an A / D converted output.

FIG. 3 is a schematic diagram showing a state in which a storage area of a storage unit (ring buffer) moves as time passes.

FIG. 4 is a diagram schematically showing the operation of a time delay correction unit (storage unit).

FIG. 5 is a diagram showing a main configuration of a fine particle component analyzer using microwave induction plasma.

FIG. 6 is a diagram showing a flow of signal processing.

FIG. 7 is a diagram schematically showing a time delay depending on the type of filter, assuming that compounds containing four types of elements simultaneously emit light with the same intensity.

[0024]

[Explanation of symbols]

51 Filter Unit 52 Filter 53 Aspirator 54 Reaction Tube 55 Microwave Source 56 Cavity 5
7 Spectrometer 58 Photoelectric converter (photomultiplier tube) 59 Preamplifier 6
0 Noise filter 61 Calculation means 62 Personal computer 70 Time delay correction means

Claims (2)

[Claims] 1. Exciting and emitting means for atomizing and ionizing fine particles to excite and emit light, spectral means for spectrally dispersing a plurality of lights having different emitted wavelengths, and converting each of the predetermined wavelengths into electric signals. A plurality of photoelectric conversion means,
A plurality of signal amplifying means for amplifying each of the electrical signals converted by the photoelectric conversion means, a plurality of noise filters for inputting each of the output signals from the signal amplifying means to remove noise, and a plurality of noise filters for selection A fine particle component analyzer for calculating the size of the fine particles from the obtained signal by a calculating means, wherein the calculating means is provided with a time delay correcting means for correcting a time delay of an output signal generated by a noise filter. Analysis equipment. 2. The method according to claim 1, wherein the time delay correction means delays the output of another filter based on the known delay time, based on the filter whose output is the most delayed, among the known delay times that differ depending on the noise filter. 2. The fine particle component analyzer according to claim 1, wherein: