JPH01174938A - Reduction of mutual interference in fluid analyser by multi-fluid modulation system - Google Patents

Abstract

PURPOSE:To reduce the measuring error caused by the interference noise component of the other frequency signal of a system using one frequency signal as a measuring signal, by supplying a fluid sample having lower concn. to a fluid modulation means of high modulation frequency. CONSTITUTION:Fluid modulation means V1, V2 respectively modulate two high and low concn. sample fluids S1, S2 at frequencies F1, F2Hz different from each other on the basis of comparing fluids R1, R2. An analyzing part A has one detector D and the modulated fluids S1, S2 are supplied simultaneously and continuously. A signal processing means B separates the output signal from the detector D into signal components of frequencies F1, F2 to the respective fluids S1, S2 to respectively apply rectifying and smoothing processing and only the signals of the bands in the vicinity of the frequencies F1, F2 are allowed to respectively pass by a BPF in order to obtain the analytical value relating to each of the fluids S1, S2. The output signal from the BPF is detected and rectified before smoothed. The sample fluid S2 having lower concn. among both samples is supplied to the means V2 having higher modulation frequency among the means V1, V2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention employs a unique method that has not been seen before, called a multi-fluid modulation method (this is the name given by the present inventors). Although only one detector is used, two (or split into two systems)
In a completely new fluid analysis device that can analyze sample fluids simultaneously and continuously with high precision, the interaction between the two sample fluids is used to obtain even higher measurement accuracy. This was done to provide a usage method that can reduce measurement errors.

[Conventional technology]

For example, residual components (NOx) such as automobile exhaust gas and factory exhaust gas contained in the atmosphere, which is an example of a sample fluid, are used.
Conventionally, a chemical luminescence detector (C
An analyzer equipped with an LD) or a flame ion detector (
A non-dispersive infrared analyzer (ND I Fluid analysis devices that employ various types of detectors (sensors) such as R) are used.

By the way, when performing the above-mentioned fluid analysis, it is necessary to analyze two components in the sample fluid, such as No and Nov, methane (CH4) and HC other than methane (NMHC), or CO and Cog. It is often necessary to measure component concentrations simultaneously and continuously, but in order to achieve this with a conventional fluid analysis device, two detectors (sensors) are required.

In other words, when measuring NO and NOx simultaneously and continuously,
The sample fluid is divided into two measurement systems, one system is equipped with a first NO detector for independently measuring the NO concentration in the sample gas, and the other system is equipped with a first NO detector to independently measure the NO concentration in the sample gas.
Two NO detectors are required (No The concentration is obtained as the difference between the total NOs concentration detected by the second NO detector and the NO concentration detected by the first NO detector (this method is called the difference method), and also the difference between methane and non-methane HC (NMHC). ), the sample fluid is divided into two measurement systems,
One system is equipped with a first HC detector for measuring the total HC concentration (THC) in the sample fluid, and the other system is equipped with a process to remove IC other than methane from the sample fluid by catalytic combustion. In this case, two HC detectors are required, such as a second HC detector to measure the methane concentration in the process gas produced by (obtained as the difference between the THC concentration detected by the first HC detector and the methane concentration detected by the second HC detector), and CO and CO in the sample fluid.
8 and 8, the sample fluid is divided into two measurement systems, and one system is equipped with a CO detector, and the other system is equipped with a CO□ detector. Two different detectors are required: a detector and a CO1 detector.

By dividing the same sample fluid into two systems as described above, it is possible not only to perform simultaneous and continuous analysis of two components in the sample fluid, but also to analyze two different sample fluids in each system. Similarly, two detectors (
(sensor) is clearly required.

However, as described above, when performing simultaneous and continuous analysis of two components in the same sample fluid, or simultaneous and continuous analysis of specific components contained in two different sample fluids, it is difficult to use the conventional apparatus as described above. Having to use two detectors not only causes problems such as (a) the large size of the analyzer and high manufacturing costs, but also (b) the need to perform zero and span adjustments for each of the two detectors. (1) When the adjustment of each detector is insufficient and there is a zero adjustment error or sensitivity difference between the two detectors, This causes various problems such as very large measurement errors.

Therefore, in order to avoid such problems, two components in the same sample fluid can be measured alternately using an analyzer equipped with only one detector, or alternatively, two components in the same sample fluid can be measured alternately. It is also possible to use a so-called batch analysis method, in which measurements are taken in batches, but in that case, there is a disadvantage that the measurement data becomes discontinuous because simultaneous and continuous measurements cannot be performed. When performing analysis using the difference method, there is a risk of significant deterioration in measurement accuracy. Therefore, it is not a good idea to adopt such a batch analysis method simply to save the number of detectors, as this may greatly sacrifice the original purpose of fluid analysis.

Therefore, in view of the conventional situation, the present inventors have conducted intensive research and have adopted an innovative method called a multi-fluid modulation method. (or divided into multiple systems)
We have developed a completely new fluid analysis method and fluid analysis device that can analyze sample fluids simultaneously and continuously.
The date of December 11, 1982 is the patent application filed and the date of December 1, 1986.
The date of February 12th has already been proposed based on prior filings such as patent applications.

In other words, a fluid analysis device using the multi-fluid modulation method! i
``(method applied in this device)'' means a plurality of (methods applied in this device) In the example, two sample fluids 31 and 32 (these may be originally different, or a single sample fluid may be divided into two systems) are different from each other by comparison fluids R1 and R2, respectively. Frequency Fl
, having fluid modulation means Vl, V2 for fluid modulation at F2 (Hertz) and only one detector;
Each of the fluid-modulated sample fluids 31. An analysis part A to which S2 is simultaneously and continuously supplied, and an output signal ○ from the detector in the analysis part A is suitably frequency separated means and signal rectification/smoothing means l first.
(shown conceptually in Figure 0) is used to determine each modulation frequency F1 . F
By separating the two signal components 01°02 and rectifying and smoothing them, the sample fluids S1 and S2 are
and a signal processing means B for obtaining an analytical value of , two bandpass filters al that respectively pass only signals in bands around the respective modulation frequencies Fl and F2.

a2 are provided in parallel with each other, and at the downstream of each of the bandpass filters al(a2), in synchronization with the actual fluid modulation operation by the fluid modulation means Vl(V2) corresponding to the passband frequency Fl(F2) thereof. , a synchronous detection rectifier bl (b2) for detecting and rectifying the output signal from the band pass filter al (a2) is provided, and a synchronous detection rectifier bl (b2) is provided at the subsequent stage of each of the synchronous detection rectifiers bl (b2) for smoothing the output signal therefrom. Smoothing element cl (c2) for
It has the following characteristics:

That is, in a multi-fluid modulation type fluid analysis device having such a configuration, an appropriate fluid modulation means Vl is configured, for example, by a rotary valve, a three-way switching solenoid valve, a four-way switching solenoid valve, or the like.

(2) Different frequencies F1. ．． First, by simultaneously and continuously supplying two sample fluids 31 and S2 (or divided into two systems) fluid-modulated by F2 to the analysis section A having only one detector, From that single I★ output device, one measurement signal 0 (=○l+02) in which the individual measurement signal components (01, 02) corresponding to all sample fluids SJ, 32 are collectively superimposed is obtained. At the same time, the output signal O from the single detector is adjusted to an appropriate frequency as shown in FIG. 10, for example. By using a signal processing means B configured by combining a separation means and a signal rectification/smoothing means, each modulation frequency Fl, F2 for each sample fluid 31°s2 is determined.
By performing signal processing of separating the signal components into signal components 01.02 and rectifying and smoothing them, the analytical values for each of the sample fluids 31.32 are obtained. Even when performing simultaneous and continuous analysis of two components or simultaneous and continuous analysis of a specific component contained in two different sample fluids, only one detector (sensor) is required. Compared to conventional fluid analysis devices that required two detectors, the entire device can be made smaller and simpler, and costs can be reduced.Also, the detector can be adjusted easily and in a short time. Unlike the conventional method, zero adjustment errors and sensitivity differences between multiple detectors cannot occur, so it has the fundamentally superior advantage of always ensuring good measurement accuracy.

Moreover, as the signal processing means B, a computer capable of performing numerical analysis processing such as Fourier analysis (corresponding to frequency separation processing) and absolute value averaging processing (corresponding to rectification/smoothing processing) is used. Alternatively, it is possible to configure appropriate means using various software or hardware, such as using an electric circuit such as a lock-in amplifier. ), a synchronous detection rectifier bl (b2), and a smoothing element CI (C2) composed of, for example, a low-pass filter or a capacitor, are connected in series. It is not only much simpler and cheaper to construct than a J-stage using a computer or lock-in amplifier, but also has a frequency separation effect that may not be sufficient with band-pass filters alone. Since it is configured to be supplemented by the synchronous detection rectifier BL (b2) to perform even more accurate frequency separation, for example, it is possible to perform absolute value rectification immediately after frequency separation using only a bandpass bus filter. Signal processing performance (S
There is also the advantage that it is possible to obtain a /N ratio).

[Problem that the invention seeks to solve]

However, even in the fluid analysis device using the multi-fluid modulation method, which has various useful advantages as described above, the following problems still remain.

That is, as explained using FIG. 10, in the signal processing means B, the measurement signal 0 inputted from the detector is first passed through the bandpass filters al and a2 to both sample fluids Sl.

Individual measurement signal components Of (frequency Fl) corresponding to S2
, 02 (frequency F2), but both fluid modulation frequencies F1. Either set F2 to a sufficiently large difference, or set both bandpass filters a
Unless measures are taken that are extremely difficult in practice, such as using high-grade materials with fairly sharp frequency cut characteristics as l and a2, reliable frequency separation results cannot be obtained. The signal that has passed through each bandpass filter al(a2) has the original frequency Fl(
In addition to the signal 0 of F2), a noise component of the other fluid modulation frequency F2 (Fl) inevitably mixes, resulting in a mutual interference effect.

In this way, if the noise component of the other fluid modulation frequency F2 (Fl) due to mutual interference is mixed into the signal that has passed through each bandpass filter al (a2), the following problems will occur. .

In other words, the fluid modulation frequencies Fl and F2 can usually be set arbitrarily, but in that case, generally even after the signal is synchronously detected and rectified by the synchronously detected rectifier b1 (b2). , the signal corresponding to the interference noise component will remain as a measurement error factor (that is, its smoothed value will not become 0).

Further, the above-mentioned problem is not limited to noise components due to mutual interference effects, but also, for example, when the fluid modulation means Vl (V2>
The same problem occurs when a noise component of the frequency F2 (Fl) of another system is mixed in due to other factors such as a mechanical duty shift.

Therefore, in order to find a clue to solving such problems, the present inventors investigated the above-mentioned ``measurement caused by interference noise components of the other frequency signal in a system where one frequency signal is the measurement signal''. As a result of trying various experimental and theoretical considerations regarding the error, for example, one fluid modulation frequency Fl is 1Hz, and the other fluid modulation frequency F2 is 3Hz.
As can be easily understood from FIGS. 11 (a) and (b), which show examples in the case of r It appears very strongly in a system where the measurement signal is a frequency signal of The interference to the prefecture side, which uses the lower frequency signal as the measurement signal, is very large, but conversely, the interference is from the prefecture side, which uses the lower frequency signal as the measurement signal, to the prefecture side, which uses the higher frequency signal as the measurement signal. It was confirmed that the interference was not that large).

The present invention has been made in view of the above-mentioned actual circumstances and results of consideration, and its purpose is to improve the fluid analysis device using the multi-fluid modulation method according to the prior application, which has various advantages as described above. For example, making any changes that are difficult in practice, such as setting the modulation frequencies of both fluids to be sufficiently different, or using high-grade bandpass filters with sharp frequency cut characteristics as both bandpass filters in the signal processing means. Using a practical method that is unnecessary and can be implemented extremely easily, it is possible to reliably reduce measurement errors caused by interference noise components of the other frequency signal in a system where one frequency signal is the measurement signal as described above. It is important to be as careful as possible.

[Means for solving problems]

In order to achieve the above object, according to the present invention, 7. .

As is clear from the basic conceptual diagram and claim correspondence diagram shown in Fig. 1, the method for reducing mutual interference in a fluid analysis device using the fluid modulation method is based on two sample fluids 31 (also divided into two systems).
．． 32 are comparative fluids, respectively, and R1 and R2 have mutually different frequencies F1. an analysis section having fluid modulation means Vl, V2 for fluid modulation at F2 (Hertz) and only one detector, and to which each fluid modulated sample fluid SL, 32 is supplied simultaneously and continuously; A, and the output signal from the detector in the analysis section A,
Each sample fluid S1. Each modulation frequency F for S2
By separating the signal components 01.02 of 1 and F2 and rectifying and smoothing them, each sample fluid
．． In order to obtain an analytical value regarding S2, two bandpass filters al and a2 are connected in parallel to each other, which respectively pass only signals in bands around the respective modulation frequencies Fl and F2 from the output signal 0 from the detector. At the same time, a bandpass filter al(a2>) is provided at the subsequent stage of each bandpass filter al(a2>) in synchronization with the actual fluid modulation operation by the fluid modulation means Ml(V2) corresponding to the passband frequency Fl(F2) of the bandpass filter al(a2>). A synchronous detection rectifier bl (b2) is provided to detect and rectify the output signal from (a2),
Further, a smoothing element C1 (c
2), and a signal analysis means B provided with said fluid modulation means V1. towards the fluid modulating means (v2) with the higher modulation frequency of V2, both sample fluids Sl, 3
The present invention is characterized by adopting a method of supplying a fluid sample (S2) with a lower concentration (or a smaller change in concentration) of the two.

[Effect]

The effects achieved by adopting the above-mentioned characteristic method are as follows.

That is, in the method of the present invention, first, the method shown in FIG.

As explained with reference to (b), ``In a multi-fluid modulation fluid analysis device having the basic configuration as described above, the lower frequency signal is sent from the prefecture side, which uses the higher frequency signal as the measurement signal. The interference from the prefectural side, which uses the lower frequency signal as the measurement signal, is very large, but conversely, the interference from the prefectural side, which uses the lower frequency signal as the measurement signal, to the prefectural side, which uses the higher frequency signal as the measurement signal, is not so large. This skillfully takes advantage of the fact that there is no sample fluid S2. Either one (S2) of the two sample fluids S2 has a low concentration, or
If it is known in advance that the concentration change will be small, for example, non-methane (NMHC) in the atmosphere? ) When measuring 1 degree using the differential method, the concentration of methane alone, which is one measurement target, is higher than the total HC concentration (
In a case where the fluid sample (S2) with the lower concentration (or with a smaller concentration change) is known to have a clearly lower concentration (this also has a very small change in concentration) than the fluid sample (S2) , the fluid modulation means (
v2), and the sample fluid (Sl) with the other quotient concentration (or with a large concentration change) has the advantageous property that the interference effect on the other measurement system is not so large. , to the fluid modulation means (■2) in a system with a low modulation frequency, by simply adopting a practical method that is extremely easy to implement, for example, it is possible to make the two fluid modulation frequencies sufficiently different. It is possible to measure one frequency signal as described above without having to make any changes that are difficult in practice, such as setting or using high-quality bandpass filters with sharp frequency cut characteristics as both bandpass filters in the signal processing means. Measurement errors caused by interference noise components of the other frequency signal in the signal system can be reliably reduced.

〔Example〕

Hereinafter, a specific example of the mutual interference reduction method in a fluid analysis device using a multi-fluid modulation method according to the present invention is shown in the drawings (
This will be explained based on FIGS. 2 to 8).

FIG. 2 shows an overall schematic configuration of a fluid analysis device using a multi-fluid modulation method according to a first embodiment of the present invention. NOx or H, C, contained in
It is used when analyzing the concentration of etc.

As shown in Figure 2, two sample fluids SL
, 32 (which may be different in nature or may be a single sample fluid divided into two systems as will be explained in more detail later), respectively, by means of fluid modulation means Vl. , V2, and the comparison fluids R1, R2 (generally zero gas is used) make the frequencies Fl different from each other.

After fluid modulation at F2 (Hertz) (i.e. passing the sample fluid and reference fluid alternately at a predetermined frequency),
Each of these fluid-modulated sample fluids St, S2 (R
1, R2) are simultaneously and continuously supplied to the analysis section A, which has only one detector D (sensor).

The fluid modulation means Vl, V2 are arranged so that the ratio of their fluid modulation frequencies Fl, F2 is 1:2.
That is, one modulation frequency F1 is set to IHz (small), and the other modulation frequency F2 is set to 2Hz (large).

Incidentally, in the case of this embodiment, the detector in the analysis section A is generally a chemical luminescence detector (CLD) for detecting NO, or a flame ion detector (CLD) for detecting hydrocarbon HC. Since a type through which the sample fluid directly passes, such as FID), is used, both the fluid-modulated sample fluids 31. S2 is supplied to the detector in a mixed state.

Therefore, the signal 0 outputted from the detector via the preamplifier 2 has individual measurement signal components (C
)1,02) are collectively superimposed on one measurement signal (
0=01 +02).

Therefore, the output signal O from the detector is transferred to a frequency separation circuit 3, as conceptually illustrated in FIG.
and a signal rectifier circuit 4, each modulation frequency Fl (IHz), F for each of the sample fluids SL, S2 is
2 (2 Hz) signal components 01 and 02 and rectify them respectively, each of the sample fluids S1. An analysis value regarding S2 is obtained.

The specific circuit configuration of the signal processing means B is as follows.
It is supposed to be as shown in the figure.

That is, the signal O output from the detector via the preamplifier 2 is branched into a plurality of signal processing series (two series in this example) provided in parallel with each other, and one signal processing series has a sample output. Modulation frequency (IHz) for fluid S1
A band pass filter a1 is provided for detecting and extracting only the signal 01 of the sample fluid S1, and at the subsequent stage, a synchronizing signal ( Signal representing actual fluid modulation operation by fluid modulation means v1: F1=I
Hz), it is possible to supplement the frequency separation effect that may be insufficient with the bandpass filter a1 alone and perform frequency separation with even higher accuracy, and at the same time, to convert the separated alternating current into direct current, A synchronous detection rectifier b1 is provided for synchronously rectifying the output signal 01 from the band-pass filter a1, and a synchronous detection rectifier b1 is provided at a subsequent stage for smoothing the output signal from the synchronous detection rectifier b1 and removing high frequency noise. A low-pass filter (L, P, F) is provided as the smoothing element c1, and the other signal processing series has a modulation frequency (
In addition to providing a band pass filter a2 for detecting and extracting (passing) only the signal 02 (2Hz),
At the subsequent stage, a fluid modulation means for the sample fluid S2 is provided.
A synchronizing signal from the synchronizing signal generator 1b attached to V2 (a signal representing the actual fluid modulating operation by the fluid modulating means v2:
F2-2H2), the bandpass filter 3
The output from the bandpass filter a2 can be used to supplement the frequency separation effect, which may be insufficient with 2 alone, to achieve even more accurate frequency separation, and at the same time, to convert the separated alternating current into direct current. A synchronous detection rectifier b2 for synchronously rectifying the signal 62 is provided, and a low-pass filter (as a smoothing element C2) for smoothing the output signal from the synchronous detection rectifier b2 and removing high frequency noise is provided at the subsequent stage. L, P, F).

Now, for example, when measuring the concentration of non-methane (NMHC) in the atmosphere by the differential method using a fluid analyzer using the multi-fluid modulation method configured as described above, one of the measurement targets, methane In cases where it is known that the methane concentration alone is clearly lower (or the concentration change is very small) than the total HC concentration (THC), which is the other measurement target, the methane concentration alone A sample fluid for measuring, that is, a sample fluid with a lower concentration (or a smaller concentration change) (S2 in the illustrated example)
is supplied to the fluid modulating means with a higher modulation frequency (in the illustrated example, 2) of the two fluid modulating means Vl and V2. As is clear from the above, it is possible to reliably and easily reduce measurement errors caused by interference noise components of the other frequency signal in a system in which one frequency signal is used as the measurement signal.

Furthermore, in this embodiment, one (lower) fluid modulation frequency F1 is set to IHz, and the other (higher) fluid modulation frequency F2 is set to 2H2, which is an even multiple (twice) of the fluid modulation frequency F1. There are also advantages such as.

That is, as shown in FIG. 4(a), the original signal 01 (
Even if an interference noise component of a higher fluid modulation frequency (2Hz) is mixed in in addition to IHz), if the signal is synchronously rectified by the synchronous detection rectifier b1, the noise component (2Hz) will be The smoothed value by smoothing element C1 is plus/minus canceled and synchronously detected and rectified in the form of O. Therefore, from smoothing element c1, correct measurement corresponding only to the original signal 01 (1'Hz) is performed. You will get a signal.

Also, contrary to the above, even in a system where the higher frequency signal (2H2) is the measurement signal, the lower frequency signal (I
Similarly, the smoothed value of the interference noise component (Hz) is plus/
It can be easily understood from FIG. 4(b) that the negative values are canceled out to 0, and a correct measurement signal without any measurement error is obtained.

FIG. 5 shows a schematic configuration of main parts of a fluid analysis device using a multi-fluid modulation method according to a second embodiment to which the method of the present invention is applied. It is used when analyzing the concentration of COX, etc. contained in

In this case, the analysis part A of the device is generally composed of a non-dispersive infrared analyzer (NDIR), and therefore the detector D (sensor) is a condenser microphone type or a micro flow one type. A type that does not allow the sample fluid to pass through directly, such as a pneumatic ink type detector, a thermopile, or a solid state detector such as a semiconductor, is used. However, as shown in this figure, when the analysis section A is configured with a so-called single cell type NDIR using only one cell C, the fluid modulation is also performed as in the case of the first embodiment. Both sample fluids 31, 32 (R1, R2) are supplied in a mixed state to the cell C, and the absorbance of the measuring infrared rays passing through the cell C is measured by a detector.

Regarding other configurations in this example,
Since it is the same as that of the first embodiment, the same reference numerals are given to the members having the same functions, and the explanation thereof will be omitted.

FIG. 6 shows a schematic configuration of main parts of a fluid analysis device using a multi-fluid modulation method according to a third embodiment to which the method of the present invention is applied, and this is also used when analyzing the concentration of COX or the like.

In this case, the analysis section A is divided into two cells CI.

Since it is configured with a so-called double cell type non-dispersive infrared analyzer (ND I R) having C2, both fluid-modulated sample fluids St and S2 (R1°R2) are not mixed with each other. Although the infrared rays are supplied into separate cells CI and C2, the absorbance of each measuring infrared ray that has passed through both cells C1 and C2 is simultaneously measured by one detector. Although not shown, the above 2
For example, one of the cells C1 and C2 has a solid filter for CO measurement, and the other has a solid filter for CO measurement. A solid filter for measurement is attached to each.

In addition, regarding other configurations in this example,
Since it is the same as that of the first and second embodiments, members having the same functions will be given the same reference numerals and their explanation will be omitted.

By the way, as in the case where the two sample fluids S1.32 are led separately from two exhaust channels, for example,
It may be originally different, or the seventh
As illustrated in the figure, a single sample fluid SO may be divided into two systems, typically co and COt or No and No in the same sample fluid SO.
It is applied to cases where methane and HC other than methane (NMHC) are simultaneously and continuously measured.
A converter 5 for converting x to NO or CO to COt is not shown, but
Usually, a non-methane removal device or a necessary filter is provided. In addition, as illustrated in FIG. 7, the comparative fluids R1 and R2 also have the following:
It may be configured to use a common RO (e.g. zero gas).

Further, each of the fluid modulation means Vl and V2 may have any configuration as long as it can alternately switch between the sample fluid 31 (32) and the comparison fluid R1 (R2) at a predetermined frequency. For example, , it may be constructed with a rotary valve as shown in Figure 8 (A), or it may be constructed with a four-way switching solenoid valve as shown in Figure 8 (B). However, it may be configured using a three-way switching solenoid valve.

〔Effect of the invention〕

As is clear from the detailed explanation above, the method for reducing mutual interference in a fluid analysis device using a multi-fluid modulation method according to the present invention has the disadvantageous characteristic that the interference effect on the other measurement system is large. However, in a system with a high modulation frequency, a sample fluid with a lower concentration (or a smaller change in concentration) is supplied to the fluid modulation means, which has the advantage of having less interference with the other measurement system. A practical method that is extremely easy to implement is to supply a sample fluid with a higher concentration (or a larger change in concentration) to the fluid modulation means in a system with a lower modulation frequency, which has the characteristic By adopting this method, an excellent effect is achieved in that in a system where one frequency signal is used as a measurement signal, measurement errors caused by interference noise components of the other frequency signal can be reliably reduced.

[Brief explanation of the drawing]

FIG. 1 shows a basic conceptual diagram (diagram corresponding to claims) of a mutual interference reduction method in a fluid analysis device using a multi-fluid modulation method according to the present invention. Further, FIGS. 2 to 8 show various specific embodiments of the method of the present invention, and FIG. 2 shows the overall schematic configuration of a fluid analysis device using a multi-fluid modulation method according to the first embodiment to which the method of the present invention is applied. Figure 3 is a detailed circuit configuration diagram of the main part,
Figures 4(a) and 4(b) are explanatory diagrams of their effects, respectively.
FIG. 5 is a schematic diagram of the main parts of a fluid analysis device using a multi-fluid modulation method according to a second embodiment to which the method of the present invention is applied, and FIG. FIG. 7 is a schematic diagram of the main part of a fluid analysis device using a fluid modulation method; FIG. 7 is a schematic diagram of the main part for supplementary explanation of each of the above embodiments; FIGS. FIG. 7 is a schematic configuration diagram of main parts for providing another supplementary explanation to each of the above embodiments. Furthermore, FIGS. 9 to 11 are for explaining the technical background of the present invention and problems in the prior art, and FIGS. 9 and 10 illustrate the multi-fluid modulation system according to the prior art. shows the basic concept of a fluid analysis device by and an explanatory diagram of the specific configuration of its main parts, and
Figure 11 (a). (b) shows an explanatory diagram of each problem. 31, S2: sample fluid, R1, R1 comparison fluid, Fl, Fl fluid modulation frequency, Vl, V2: fluid modulation means A: analysis section, D: detector, B: signal processing means, 0: from the detector Output signal, 01.02 = each modulation frequency Fl for each sample fluid 31.32. Signal components of F2, al, a2: band pass filter, bl, b2: synchronous detection rectifier, cl, c2: low pass filter. Applicant Horiba Manufacturing Co., Ltd. Representative Patent Attorney Hideo Fujimoto

Claims (1)

[Claims] Two sample fluids (also divided into two systems),
fluid modulation means for modulating the fluid at different frequencies with reference fluids; and an analysis section having only one detector and to which each of the fluid-modulated sample fluids is supplied simultaneously and continuously; The output signal from the detector in the analysis section is separated into signal components of each modulation frequency for each of the sample fluids, and rectified and smoothed, respectively, to obtain analysis values for each of the sample fluids. Two bandpass filters are provided in parallel to each other to pass only signals in a band near each of the modulation frequencies from the output signal from the detector, and a filter corresponding to the passband frequency of each of the bandpass filters is provided at a subsequent stage of each of the bandpass filters. A synchronous detection rectifier for detecting and rectifying the output signal from the bandpass filter in synchronization with the actual fluid modulation operation by the fluid modulation means, and downstream of each of the synchronous detection rectifiers,
and a signal analysis means provided with a smoothing element for smoothing an output signal therefrom, in a fluid analysis device using a multi-fluid modulation method, the fluid modulation means having a higher modulation frequency of the two fluid modulation means. A method for reducing mutual interference in a fluid analysis device using a multi-fluid modulation method, characterized in that a fluid sample having a lower concentration (or having a smaller concentration change) of the two sample fluids is supplied to the sample fluid.