JP3242500B2 - Self-diagnosis method of spectrophotometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow-type absorptiometer installed in a water purification process, a tap water supply terminal, or the like .
Self-examination on the cross-sectional method.

[0002]

2. Description of the Related Art Turbidity meters and chromaticity meters are one of water quality measuring devices such as a water purification process and a tap water supply terminal. Water turbidity is a phenomenon caused by scattering of light by suspended substances in water, and the scattering phenomenon depends on the wavelength of light, the size of particles, the refractive index and absorption of a substance constituting the particles, and the like. For this reason, the value measured by the turbidity meter is the concentration of the turbidity standard solution due to kaolin (weight of kaolin in 1 liter of water mg / l)
It is measured by the value converted to. Chromaticity was also measured at a wavelength of 390 nm due to the first measurement of inflow pollution from peaty soils into rivers in the UK and yellow or tan measurements at a wavelength of 390 nm. Absorption at this wavelength is considered to have chromaticity.

[0003] Fig. 5 shows an example of the configuration of a conventional absorption photometer in which a turbidimeter and a chromaticity meter are integrated, and the operation principle thereof will be described. In FIG. 5, reference numeral 1 denotes a measuring cell into which a sample 1A to be inspected is introduced and led out. One end of the measurement cell 1 has a light source L housed in a lamp house LH, the other end of the measurement cell 1 has a photodetector PD, and a filter wheel 2 is provided between the light source L and the measurement cell 1. Inserted. The filter wheel 2 is formed of a disk-shaped light shielding plate, and is rotationally driven by a motor MT. FIG. 6 shows a plan view of the filter wheel 2. A position on a fixed radius from the center of rotation of the filter wheel 2 is divided into three equal parts, and two holes are provided therein, and the holes are provided with a measurement filter Fm1 having a wavelength of 660 nm and a measurement filter Fm2 having a wavelength of 390 nm.
A reflecting mirror 6A at an angle of 45 ° for extracting the reference light is arranged at the remaining one place, and a reflecting mirror 6B is arranged to face the reflecting mirror 6A. The filter wheel 2 has a notch 5 as a position mark at the opposite end of the optical filter Fm2 with respect to the center of rotation. Further, rectangular frames M and R shown by two dotted lines on the opposite side of the reflecting mirrors 6A and 6B with respect to the rotation center indicate a positional relationship for explaining a traveling relationship of light from the light source L. Light enters the position shown in the rectangular frame M. If the optical filter Fm1 comes to the position of the rectangular frame M, a light component having a wavelength of 660 nm is transmitted and enters the measurement cell 1, and the position of the rectangular frame M When the optical filter Fm2 comes in, the light component having a wavelength of 390 nm is transmitted and enters the measuring cell 1. When the reflecting mirror 6A at an angle of 45 ° comes to the position of the rectangular frame M, the light from the light source L is reflected at right angles by the reflecting mirror 6A, and is reflected by the reflecting mirror 6B coming to the position of R in FIG. The light is reflected in the right-angle direction, enters the incident end face 4A of the reference optical fiber 4 shown in FIG. 5, and passes through the optical fiber 4 (reference optical path) from the emission end face 4B attached to the light receiving section cover 7. The light is optically coupled to the detection element PD (for example, a photoelectric converter) and is incident.

When the optical filter Fm1 or Fm2 is a rectangular frame M
, And the light component having a wavelength of 660 nm or a wavelength of 390 nm that has passed through and entered the measurement cell 1 is detected by the above-described same photodetector PD via the measurement optical path. The measurement signal detected by the photodetector PD is amplified by an amplifier PA, converted into a digital value by an A / D converter, and processed by a calculation unit CAL including a central processing unit (CPU). The operation result is converted to an analog value by the D / A converter. When the notch 5 provided on the filter wheel 2 comes to the position sensor 3, the position sensor 3 detects the position of the notch 5 by optical means or electromagnetic coupling means.

In this configuration, the position timing information from the position sensor 3 is taken into the operation unit CAL via the interface circuit I / O, so that the operation unit CAL receives the measurement signal detected by the photodetector PD. , Optical filter Fm1 (66
0 nm) or a measurement signal passing through Fm2 (390 nm) or a reference light signal passing through the reference optical fiber 4 can be determined. That is, based on this timing, predetermined arithmetic processing is performed, and the measurement arithmetic results of turbidity (660 nm) and chromaticity (390 nm) are output to the D / A converter,
Turbidity and chromaticity are measured via a D / A converter.

Reference numeral 8 denotes a driving mechanism for span calibration at the time of measuring the turbidity and chromaticity, and a calibration filter for wavelengths λ ₁ (660 nm) and λ ₂ (390 nm) is provided at the tip of the driving mechanism. Has been established. At the time of simple span calibration, the water sample in measuring cell 1 is replaced with zero solution, and at the same time, zero solution check is also performed, and the above-mentioned wavelength λ ₁ (660 nm) or λ ₂ (390 nm) calibration filter is used. The optical fiber is inserted into the optical path for measurement, and light absorption equivalent to the light absorption when the measuring cell 1 is filled with the span calibration liquid is caused by this calibration filter to perform span calibration. When performing an accurate span calibration, the measurement is performed by replacing the sample in the measuring cell 1 with a standard solution for span calibration, and the data of the measurement result is stored and used as a subsequent calculation constant.

Next, the principle of measuring turbidity and chromaticity will be described. The measurement light signals transmitted through the measuring cell 1 is detected by the optical conversion element PD (There are two types of I _M is an optical filter of the filter wheel 2 Fm1, Fm2) I _M and then, the reflector 6A, 6B and the optical fiber Assuming that a reference light signal that does not pass through the measurement cell 1 via I 4 is I _R , the measurement light signal is expressed by Equations (1) and (2) according to Lambert-Beer's Law, and the reference light signal is expressed by Equation (3). It is represented by

[0008]

(Equation 1)

[0009]

(Equation 2)

[0010]

(Equation 3)

Here, G _m ; a constant determined by optical and geometrical arrangement and conditions (measuring light side) G _R ; a constant determined by optical and geometrical arrangement and conditions (reference light side) β _m1 ; optical The transmittance β _m2 of the filter Fm1 at the wavelength λ ₁ = 660 nm; the transmittance Iλ _{1 of the} optical filter Fm2 at the wavelength λ ₂ = 390 nm; the radiation intensity Iλ _{2 of the} light source L at the wavelength λ ₁ = 660 nm; the wavelength λ _{2 of the} light source L = Radiation intensity at 390 nm Iλ; Radiation intensity at all wavelengths of light source L by wavelength P ₁ ; Photoelectric conversion constant of photodetector PD at wavelength λ ₁ = 660 nm P ₂ ; Photoelectric conversion at photodetector PD at wavelength λ ₂ = 390 nm Constant Pλ; photoelectric conversion constant for each wavelength in the entire wavelength range of photodetector PD k ₁ ; transmittance at wavelength λ ₁ = 660 nm (0 ≦ k ₁ ≦ 1) due to contamination of measurement cell 1 k ₂ ; contamination of measurement cell 1 Transmittance at wavelength λ ₂ = 390 nm (0 ≦ k ₁ ≦ 1) α ₁ ; wavelength λ ₁ = 660n extinction coefficient α ₂ of turbidity standard solution (kaolin solution) at m; extinction coefficient of chromaticity standard solution at wavelength λ ₂ = 390 nm C ₁ ; true turbidity (mg / l) C ₂ ; true chromaticity (DEG L) Cell length (optical path length) of the measuring cell 1 Here, the expressions (1) to (3) treat the base component signal of the photodetector PD when the filter wheel 2 is blocking light as 0. I have.

Next, it is assumed that the absorbance A is expressed by the logarithm of the ratio between the measurement light signal and the reference light signal, as shown in equation (4).

[0013]

(Equation 4)

1) Relational expression of turbidity measurement The turbidity is measured by using equation (1), using a light flux having a wavelength of λ ₁ = 660 nm and a measurement light signal in a zero turbidity zero liquid (C ₁ = 0). I _M10
In addition, by measuring the measurement light signal I _M1S in the turbidity calibration span solution (C ₁ = C _1S ) in advance, the turbidity (C ₁ = C _1M ) of the test sample can be measured.

[0015] 1.1) Absorbance A ₁₀ at the zero solution of the measurement light signal I _M10 turbidity zero at zero liquid turbidity zero _{(C 1 = 0) (C} 1 = 0) is, C ₁ = 0 in (1) By substituting into the equation (5).

[0016]

(Equation 5)

[0017] 1.2) Absorbance A _1S in the measured optical signal I _M1S turbidity calibration span solution (C ₁ = C _1S) of the turbidity calibration span solution (C ₁ = C _1S), the
By substituting C ₁ = C _1S into equation (1), it is expressed by equation (6).

[0018]

(Equation 6)

Here, the coefficient 0.434 is based on Log ₁₀ e = 0.434, and is introduced to simplify the equation (6). From the equation (6), the extinction coefficient α ₁₀ L over the measurement length L of the measurement cell 1 based on the span calibration concentration value (C _1S ) of the turbidity standard solution (kaolin solution) is obtained from the equation (7).

[0020]

(Equation 7)

1.3) Turbidity of the sample to be measured for turbidity (C ₁ = C _1M )
Measurement (measurement light signal I _M1 ) The absorbance A _1M of the turbidity measurement target water sample (turbidity C ₁ = C _1M ) is
By substituting C ₁ = C _1M into equation (1), it is expressed by equation (8),

[0022]

(Equation 8)

Therefore, the turbidity calculation output T _1M (= C _1M ) is
From equations (7) and (8), it is represented by equation (9),

[0024]

(Equation 9)

From equation (9), the span calibration solution concentration value C _1S and
Absorbance A ₁₀ at zero fluid calibration, by storing the measurement operation data between the absorbance A _1S during span liquid calibration calculation unit CAL comprising a central processing unit (CPU), a subsequent measurement light signal I _M1 Thus, the turbidity T _1M can be calculated. 2) Relational expression for chromaticity measurement The measurement of chromaticity can be obtained in the same manner as the relational expression for turbidity measurement. In the chromaticity measurement, the measurement light signal I in a zero chromaticity zero liquid (C ₂ = 0) using a luminous flux having a wavelength of λ ₂ = 390 nm using equation (2).
_By measuring the measurement light signal I _M2S in _M20 and the chromaticity calibration span liquid (C ₂ = C _2S ) in advance, it is possible to measure the chromaticity (C ₂ = C _2M ) of the sample to be measured. it can.

[0026] 2.1) Zero solution chromaticity zero (C ₂ = 0) Absorbance A ₂₀ at the zero solution of the measurement light signal I _M20 chromaticity zero (C ₂ = 0) in the, C ₂ = 0 in equation (2) By substituting into the equation (10).

[0027]

(Equation 10)

[0028] 2.2) Chromaticity Calibration Span solution (C ₂ = C measured optical signal I _M2S chromaticity calibration span solution in _{2S) (C 2 = C 2S} ) absorbance A _2S in the
By substituting C ₂ = C _2S into equation (2), it is expressed by equation (11).

[0029]

[Equation 11]

From equation (11), measurement cell 1 using the chromaticity standard solution
The extinction coefficient α ₂₀ L over the measurement length L is obtained from equation (12).

[0031]

(Equation 12)

2.3) Chromaticity of water sample to be measured (C ₂ = C _2M )
Measurement (measurement light signal I _M2 ) The absorbance A _2M of the water sample (chromaticity C ₂ = C _2M ) of the chromaticity measurement target is
By substituting C ₂ = C _2M into equation (2), it is expressed by equation (13).

[0033]

(Equation 13)

Therefore, the chromaticity calculation output T _2M (= C _2M ) is (1
From equations (2) and (13), it is expressed by equation (14).

[0035]

[Equation 14]

However, at the chromaticity measurement wavelength λ ₂ = 390 nm,
There is also light absorption based on the turbidity component, and it is necessary to correct this turbidity component. For this reason, the chromaticity calculation output T _{2M of the} equation (14)
And the chromaticity calculation output T corrected by the equation (15)
_{Get 2M} '. (K ₂₁ ; correction coefficient of turbidity component)

[0037]

(Equation 15)

From equation (15), the span calibration solution concentration value C _2S and
Be carried out between the absorbance A ₂₀ at zero fluid calibration, and stores the measurement operation data between the absorbance A _2S during span liquid calibration calculation unit CAL comprising a central processing unit (CPU), a correction operation in turbidity output T _1M , The chromaticity T _2M ′ can be calculated.

[0039]

Prior art absorptiometers have wavelengths λ ₁ = 660 nm (turbidity) and λ ₂ = 390 nm (chromaticity).
The turbidity and chromaticity are measured by logarithmic calculation of the ratio of the measured value of the measured light signal to the measured value of the reference light signal in the above. As the reference light signal, energy in the entire wavelength range of the light source is used. Therefore, a change in the spectrum of the light source over time (a change in the radiation intensity for each wavelength) affects the measurement result. Similarly,
The change over time of the photoelectric conversion coefficient for each wavelength of the photodetector also affects the measurement. Further, as a means for obtaining the reference light signal, the reflecting mirrors 6, 7 shown in FIGS.
As shown in the figure, a flat portion could not be obtained, and it was difficult to obtain a stable reference light signal due to the influence of vibrations caused by rotation. Further, the drive mechanism for span calibration is expensive and has a drawback that the structure is complicated.

The present invention has been made in view of the above points, and an object of the present invention is to solve the above-described problems and to perform measurement even when a change in the spectral characteristics of a light source or a photodetector with time occurs. It is an object of the present invention to provide an absorptiometer that has a simple structure, has no influence, can obtain a stable reference light signal, and does not require a driving mechanism for span calibration, and a method for self-diagnosing the absorptiometer.

[0041]

[0042]

[0043]

[0044]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
, In the invention according to the appended claims 1, and measuring cell test water is introduced, a light source provided at a first gap between the measuring cell at one end of the measuring cell, the measurement A photodetector provided at the other end of the cell, an arithmetic unit for performing arithmetic processing on a detection output of the photodetector, and a first optical fiber in which a part of light emitted from the light source is coupled to one end thereof When,
A second optical fiber that has one end opposed to the other end of the first optical fiber with a second gap therebetween, and guides a part of the light emitted by the light source to the photodetector; A filter for measurement and a filter for calibration provided respectively at predetermined positions on the same radius from the center of rotation thereof, and rotate the filter for measurement or the filter for calibration in the first or second gap. A filter wheel to position,
Wherein a measuring optical path is formed from the light source to the light detecting element through the measuring cell via a measuring filter located in the first gap during measurement, and a calibration optical path located in the first gap during calibration. A reference optical path is formed through the filter, the reference optical path is formed from the light source through the first and second optical fibers to the light detection element, via the measurement filter located in the second gap during measurement, A self-diagnosis method for an absorptiometer formed via a calibration filter positioned in a second gap at the time of calibration, wherein a difference between the measurement filter and the absorptiometer of the calibration filter is determined by measuring a reference optical path. reference light signal transmitted through the use filter and a calibration filter more operations to the logarithm of the ratio of the transmitted reference light signal, based on the temporal change of this calculated value, detecting the deterioration of the calibration filter and the measurement filter things and That.

Further, the light source in the present invention by the appended claims 2, which is provided at the measuring cell test water is introduced, a first gap between the measuring cell at one end of the measuring cell A light detection element provided on the other end side of the measurement cell, a calculation device for performing arithmetic processing on the detection output of the light detection element, and a light source emitted by the light source, a part of which is coupled to the one end. One optical fiber, the other end of the first optical fiber and the second
A second optical fiber that has one end portion disposed to face with a gap, and guides a part of the light emitted by the light source to the light detection element;
It has a measurement filter and a calibration filter provided at a predetermined position on the same radius from the center of rotation so that the measurement filter or the calibration filter can be rotated to the first or second filter. A filter wheel positioned in the gap between the light source and the light detection element through the measurement cell from the light source, is formed via the measurement filter located in the first gap during measurement, during calibration A reference optical path is formed via a calibration filter located in the first gap, and a reference optical path passes from the light source through the first and second optical fibers to the photodetector, and is located in the second gap during measurement. A self-diagnosis method for an absorptiometer formed through a calibration filter and formed through a calibration filter positioned in a second gap at the time of calibration, comprising: a measurement filter and a calibration filter. The absorbance difference between the measurement filter and the calibration filter is calculated from the measurement light signal transmitted through the measurement filter in the measurement optical path and the measurement light signal transmitted through the calibration filter, and the calculated calibration filter is calculated. Is calculated by subtracting the absorbance of the measurement filter from the absorbance of the filter, and the deterioration of the measurement filter and the calibration filter is detected based on the temporal change of the calculated value.

[0046] The light source in the present invention by the appended claims 3, which is provided at the measuring cell test water is introduced, a first gap between the measuring cell at one end of the measuring cell A light detection element provided on the other end side of the measurement cell, a calculation device for performing arithmetic processing on the detection output of the light detection element, and a light source emitted by the light source, a part of which is coupled to the one end. One optical fiber, the other end of the first optical fiber and the second
A second optical fiber that has one end portion disposed to face with a gap, and guides a part of the light emitted by the light source to the light detection element;
It has a measurement filter and a calibration filter provided at a predetermined position on the same radius from the center of rotation so that the measurement filter or the calibration filter can be rotated to the first or second filter. A filter wheel positioned in the gap between the light source and the light detection element through the measurement cell from the light source, is formed via the measurement filter located in the first gap during measurement, during calibration A reference optical path is formed via a calibration filter located in the first gap, and a reference optical path passes from the light source through the first and second optical fibers to the photodetector, and is located in the second gap during measurement. A self-diagnosis method for an absorptiometer formed through a calibration filter and formed through a calibration filter positioned in a second gap at the time of calibration, comprising: a measurement filter and a calibration filter. The difference and the calibration filter and the reference light signal which has passed through the measuring filter of the reference optical path more operations to the logarithm of the ratio of the transmitted reference light signal, the calibration absorbance filter and the measurement filter absorptiometer The absorbance of the measurement filter and the calibration filter is calculated from the measurement light signal transmitted through the measurement filter in the measurement optical path and the measurement light signal transmitted through the calibration filter, and the calculated absorbance of the calibration filter is calculated. Value obtained by subtracting the absorbance of the measurement filter from
More calculated, in reference optical path were measured and calculated in the same wavelength, the absorbance of the calibration optical filter and the difference in absorbance of the measuring optical filter was measured and calculated in the same wavelength in the measuring optical path, an optical filter for calibration when the ratio of the difference in absorbance and the difference in absorbance of the measuring optical filter, both calculated value is outside the predetermined range, it is assumed that the zero solution calibration.

[0047] In the invention according to the claims 4 or zero fluid calibration Note when the ratio of the difference between the two calculated values is outside a predetermined range, based on a change with time in absorbance at zero fluid calibration It is assumed that contamination of the measurement cell of the absorptiometer is detected. In the invention according to the claims 5, in the reference optical path were measured and calculated in the same wavelength, the absorbance of the calibration optical filter and the difference in absorbance of the measuring optical filter, measuring and at the same wavelength in the measuring optical path When the calculated ratio of the difference between the calculated values of the absorbance of the calibration optical filter and the absorbance of the measurement optical filter is within a predetermined range, the gain correction calculation process is performed.

[0048]

According to the above configuration, the filter wheel connects the filter (Fm1, Fm2) for measuring the wavelength for measuring turbidity and chromaticity and the filter (Fc1, Fc2) for calibration with the same radius from the center of rotation. It has a predetermined position and is rotated to set the measurement filter or the calibration filter in the first gap (for measurement) or in the second gap.
In the gap (for reference).

The measuring optical path is a path from the light source to the light detecting element through the measuring cell, and is formed via a measuring filter located in the first gap during measurement, and is located in the first gap during calibration. It is formed via the calibrated filter for calibration. The reference optical path is a path from the light source through the first and second optical fibers to the photodetector, and is formed via a measurement filter located in the second gap at the time of measurement, and is formed at the time of calibration. It is formed via a calibration filter located in the gap 2.

One of the detection signals detected by the light detecting element passes through the measuring optical path and the light from the light source is first.
The measurement light signal obtained by alternately entering the measurement cell or the calibration filter positioned in the gap of the measurement cell and being detected by the photodetector via the measurement cell, and the other one is A part of the light from the light source is extracted through the reference optical path, passes through a separate optical path from the measurement optical path, and alternately passes through the measurement filter or the calibration filter without passing through the measurement cell. This is a reference light signal obtained by being incident on the light detection element and being detected by the light detection element at a timing different from the measurement light signal.

A position mark is provided at a part of the filter wheel, and a position sensor for detecting the position mark and outputting the detection signal to the arithmetic unit is provided. It is possible to determine the measurement light signal and the reference light signal that are to be detected.
With such a configuration, the measurement light signal and the reference light signal are measured in the same wavelength band via the same optical filter (Fm1, Fm2, Fc1, Fc2), and the absorbance is the difference between the measurement light signal and the reference light signal in the same wavelength band. It is calculated by the ratio of the measured values. For this reason, even if there is a change in the spectral characteristics of the light source or the spectral characteristics of the photodetector, the ratio of the measured value as the absorbance is constant, although the individual measurement light signal and the reference light signal fluctuate. Or a change in the spectral characteristics of the photodetector.

The reference optical path is formed from the light source through the first and second optical fibers to the light detecting element via a measuring filter located in the second gap during measurement, and the second optical path during calibration. Since the filter wheel is formed via the calibration filter located in the gap of the filter wheel, the filter wheel can have a rotationally balanced structure without arranging a heavy reflector on the filter wheel, and the vibration is reduced. Thus, a stable reference light signal can be obtained.

Further, since the calibration filters (Fc1, Fc2) are provided on the filter wheel, it is not necessary to separately provide a span calibration driving mechanism. The optical filters provided in the filter wheel are a measurement filter and a calibration filter having transmission wavelength bands of 660 nm (turbidity) and 390 nm (chromaticity), and are used to measure turbidity and chromaticity at this wavelength. And calibration.

The difference between the absorbance of the calibration filter and the absorbance of the measurement filter is determined by measuring the reference light signal passing through the reference optical path and passing through the measurement filter and the calibration filter at the same wavelength and passing through the reference light path. Calculate the logarithmic values (β ₁₂ ) and (β ₂₂ ) of the ratio of the optical signal, or from the measured optical signal measured at the same wavelength via the measuring optical path via the measuring filter and the calibration filter via the measuring optical path. Calculate the absorbance and calculate the value (β ₁₁ ) or (β ₂₁ ) obtained by subtracting the absorbance through the measurement filter from the absorbance through the calibration filter, without replacing the sample in the measurement cell. Calibration span values (β ₁₁ , β ₁₂ ) and (β ₂₁ , β ₂₂ ) can be obtained. As a result, at the time of span calibration in the prior art, it was necessary to replace the sample with a zero solution and measure with a calibration filter, or replace the sample with a calibration standard solution and measure with a measurement filter. Since the operation of replacing the water sample is not required, the span calibration can be always performed without interrupting the measurement of the turbidity and the chromaticity.

The difference between the absorbance of the calibration filter and the absorbance of the measurement filter (β ₁₁ , β ₁₂ ), (β ₂₁ , β
₂₂ ) whether there is a change over time or both calculated values (β ₁₁ , β
₁₂ ) Deterioration of the optical filter of the absorptiometer, transmission of the zero liquid calibration command, defective arithmetic unit, contamination of the measurement cell, depending on whether the ratio of the difference between (β ₂₁ , β ₂₂ ) is within a predetermined range. Self-diagnosis of the absorption photometer such as detection can be performed.

The calculated values (β ₁₁ , β ₁₂ ), (β
₂₁ , β ₂₂ ) is within a predetermined range, the gain correction arithmetic processing of the absorptiometer can be automatically performed.

[0057]

FIG. 1 is a diagram showing a main part of an embodiment of the present invention, FIG. 2 is an arrangement diagram of an optical filter on a filter wheel, and FIG. 3 is a waveform of a measurement light signal and a reference light signal detected by a photoelectric converter. FIG. 4 is a flowchart for self-diagnosis of the absorptiometer of the present invention, and the same members corresponding to FIG. 5 are denoted by the same reference numerals.

In FIG. 1, reference numeral 1 denotes a measuring cell into which a sample 1A to be inspected is introduced and led out. A light source L housed in a lamp house LH at one end of the measuring cell 1
There is a photodetector PD on the other end side of the measurement cell 1,
The filter wheel 2 is inserted into a first gap between the light source L and the measurement cell 1. The filter wheel 2 is formed of a disk-shaped light shielding plate, and is rotationally driven by a motor MT. FIG. 2 shows a plan view of the filter wheel 2. A position on a fixed radius from the rotation center of the filter wheel 2 is divided into four equal parts, and holes are provided at these four positions.
Measurement filter Fm1, wavelength 660nm calibration filter Fc
1.Measurement filter Fm2 with wavelength 390nm and wavelength 390nm
The calibration filter Fc2 is installed. Filter wheel 2
Is an intermediate angle between the optical filter Fm1 and the optical filter Fc1.
It has a notch 5 as a position mark at the 45 ° end position,
The notch 5 is detected by a position sensor 3 shown in FIG.
CAL.

The rectangular frames M and R whose center is on the same radius as the center of the optical filter are shown by the dotted lines in FIG. 2 and indicate the positional relationship of the traveling optical path of the light from the light source L. The rectangular frame R indicates the reference optical path position. The optical path of the measurement optical signal in the rectangular frame M is incident from the light source L to the position shown in the rectangular frame M. If the measurement filter Fm1 (turbidity) comes to the position of the rectangular frame M, the measurement light component having a wavelength of 660 nm is emitted. When the light passes through and enters the measurement cell 1 and the calibration filter Fc1 comes to the position of the rectangular frame M, the span calibration light component having a wavelength of 660 nm is reduced by a distance corresponding to the span from the measurement light component and is transmitted. The light enters the cell 1. When the measuring filter Fm2 (chromaticity) comes to the position of the rectangular frame M, the measuring light component having a wavelength of 390 nm is transmitted and enters the measuring cell 1, and the calibration filter Fc2 comes to the position of the rectangular frame M. For example, a light component for span calibration having a wavelength of 390 nm is reduced by a distance equivalent to the span from the measurement light component, passes through, and enters the measurement cell 1.

The optical filter Fm1 and the optical filter Fc
1 corresponds to a second gap position as an optical path of the reference light signal, and the optical fiber end faces 41B and 42A of FIG. They are arranged facing each other with the filter wheel 2 interposed therebetween. In FIG. 1, in order to obtain a reference light signal, a part of the light from the light source L is taken out at the optical fiber end face 41A, and is passed through the optical fiber 41.
Coupled by the optical fiber end faces 41B and 42A which are arranged facing each other,
Via the optical fiber 42, the light is coupled to the photodetector PD from the optical fiber end face 42B. This reference light signal moves each optical filter (Fm1, Fc1, Fm2, Fc2) to the position of the square frame R,
Select wavelengths of 660nm and 390nm.

The filter wheel 2 rotates clockwise,
When the optical filters (Fm1, Fc1, Fm2, Fc2) come to the position of the rectangular frame M, the light component for measurement or span calibration at 660 nm or 390 nm is transmitted, and the light incident on the measurement cell 1 is as described above. Are detected by the same photodetector PD. Further, the optical filters (Fm1, Fc1, Fm2, Fc2) come to the rectangular frame R position with a phase difference of 45 ° of rotation angle, and the wavelength is 660 nm or 390 nm.
The reference light component or the reference light component for span calibration passes through and is detected by the same light detection element PD. This photodetector
The measurement signal detected by the PD is amplified by an amplifier PA built in the arithmetic unit 9, converted into a digital value by an A / D converter, and processed by an arithmetic unit CAL including a central processing unit (CPU). Then, the operation result is converted to an analog value by the D / A converter. When the notch 5 as a position mark provided on the filter wheel 2 comes to the position of the position sensor 3,
This can be detected by the optical means of the position sensor 3 or the electromagnetic coupling means, and the rotational position of the filter wheel 2 can be known.

With this configuration, the position timing information from the position sensor 3 is taken into the operation unit CAL via the interface circuit I / O, so that the operation unit CAL receives the time-series signal detected by the photodetector PD. , The measurement signal transmitted through the measurement cell 1 through the optical filter (Fm1, Fc1, Fm2, Fc2) at the position of the square frame M, or the measurement signal for span calibration, or the optical filter at the position of the square frame R (Fm1, Fc
1, Fm2, Fc2), it can be determined whether or not the light is due to the reference light guided by the reference light optical fibers 41, 42.
That is, based on this timing, predetermined arithmetic processing is performed,
The measurement operation results of turbidity (660 nm) and chromaticity (390 nm) are demultiplexed, and the turbidity and chromaticity measurement results are output via a D / A converter.

FIG. 3 shows a time series of pulse signals detected by the photodetector PD when the optical filters are arranged as shown in FIG. The measurement signal measured at the position and the measurement signal for span calibration are indicated by a solid line, and the reference light signal measured at the position of the square frame R is indicated by a dotted line. In addition, turbidity (660nm) or chromaticity
When it is desired to detect the (390 nm) measurement light signal and the calibration light signal adjacent to each other, the measurement optical filter and the calibration optical filter having the same wavelength may be arranged at opposing positions with the rotation center of the filter wheel interposed therebetween.

In the prior art, the driving mechanism 8 for calibrating the turbidity and the chromaticity span was required. In the present invention, however, the provision of the calibration filters Fc1 and Fc2 on the same filter wheel 2 allows the measurement cell 1 to be measured. With the water sample inside,
Calibration of the measurement span is possible, and when this measurement span is within the allowable range, the gain of the measured value can be automatically corrected.If it exceeds the allowable range, self-diagnosis of the absorptiometer can be performed by various arithmetic processing. it can.

Hereinafter, the characteristic functions according to the present invention will be described.
First, turbidity and chromaticity used in the present invention will be described. The measurement light signals I _M1 and I _M2 transmitted through the measurement cell 1 and detected by the photodetector PD are the same as the expressions (1) and (2) described in the prior art. Each optical filter (Fm1, Fc1, Fm2, Fc) in which the reference light signal which does not pass through the measurement cell 1 sequentially comes to the position of the rectangular frame R
The light is transmitted through 2) and measured by the photodetector PD. The detection output is expressed by the following equations (16) to (19), corresponding to the optical filters Fm1, Fc1, Fm2, and Fc2.

[0066]

(Equation 16)

[0067]

[Equation 17]

[0068]

(Equation 18)

[0069]

[Equation 19]

Based on this reference light signal, the absorbance B (in the prior art, the absorbance A was determined based on the reference light signal in the entire wavelength range. If the spectral distribution of the light source does not change, the two absorbances are constant. The only difference is that the coefficients should be adjusted so that the measured values match at the time of span calibration.)
As shown in equation (20), the ratio is represented by the logarithm of the ratio between the measurement light signal and the reference light signal.

[0071]

(Equation 20)

3) Relational expression of turbidity measurement in the present invention The turbidity is measured by using the formula (1) with a light flux having a wavelength of λ ₁ = 660 nm and a zero turbidity liquid (C ₁ = 0). Measurement light signal I _M10
Also, by measuring the measurement light signal I _M1S in the turbidity calibration span solution (C ₁ = C _1S ) in advance, the measurement light signal I _M1 of the sample water to be measured is measured, and the ratio with the reference light signal I _R1 is measured. The turbidity (C ₁ = C _1M ) can be determined from the logarithm of

3.1) Zero liquid with zero turbidity (C ₁ = 0, optical filter
Absorbance B ₁₀ at the zero solution of the measurement light signal I _M10 turbidity zero by fm1) (C ₁ = 0), by substituting C ₁ = 0 in equation (1) is expressed by equation (21).

[0074]

(Equation 21)

[0075] 3.2) Turbidity Calibration Span solution (C ₁ = C _1S, measurement light signal I _M1S turbidity calibration span solution (C ₁ = C _1S) absorbance B _1S in by the optical filter Fm1) is
By substituting C ₁ = C _1S into equation (1), it is expressed by equation (22).

[0076]

(Equation 22)

From equation (22), the extinction coefficient α ₁₀ L over the measurement length L of the measuring cell 1 based on the span calibration concentration value (C _1S ) of the turbidity standard solution (kaolin solution) is obtained from equation (23).

[0078]

(Equation 23)

3.3) Turbidity of water sample (C ₁ = C _1M , optical filter Fm
The light absorbance B _1M of the test light signal (turbidity C ₁ = C _1M ) of the measurement light signal I _M1 turbidity measured by 1) is
By substituting C ₁ = C _1M into equation (1), it is expressed by equation (24).

[0080]

(Equation 24)

Therefore, the turbidity calculation output T _1M (= C _1M ) is (2
From equations (3) and (24), it is expressed by equation (25).

[0082]

(Equation 25)

From the equation (25), the span calibration solution concentration value C _1S and
The turbidity T _1M can be calculated by storing the measurement calculation data of the absorbance B ₁₀ at the time of the zero solution calibration and the absorbance B _1S at the time of the span solution calibration in the calculation unit CAL including the central processing unit (CPU). . 3.4) the test water (C ₁ = C _1M) There measured by span calibration filter (Fc1) in a state test water (C ₁ = C _1M) there filter in the state span calibration (Fc
The measurement light signal I _{C1 that} has passed through 1) is obtained by calculating the transmittance β _m1 of the measurement filter Fm1 and the transmittance β of the calibration filter Fc1 according to equation (1).
Replaced with _C1, further by substituting the C ₁ = C _1M in (1), represented by (26).

[0084]

(Equation 26)

Here, when equation (24) is subtracted from equation (26),

[0086]

[Equation 27]

Here, β ₁ is the logarithm of the ratio of the transmittance β _m1 of the measurement filter Fm1 to the transmittance β _C1 of the calibration filter Fc1, which is the difference between the absorbance of the calibration filter and the absorbance of the measurement filter. It means the difference (corresponding to the amount of light absorbed by the standard solution in the measurement cell 1). Next, the light is filtered
And the absorbance A _1M when transmitted through the test water and fm1, the when the difference between the absorbance A _1C when transmitted through the calibration filter Fc1 and test water is calculated as turbidity equivalent value T ₁ (28) Equation .

[0088]

[Equation 28]

Here, assuming that the initial value of the turbidity equivalent value T ₁ is T ₁₀ , T ₁₀ / T ₁ is the turbidity equivalent value T ₁ , the gain variation of the electronic circuit including the photodetector, the optical filter characteristic. It may be considered to represent a deviation from the turbidity equivalent value of the initial value due to some cause such as a temporal variation of the measurement value, contamination of the measurement cell, or the like. Therefore, in order to determine the true turbidity T _B, it is better to adding the correction turbidity operation output T _1M obtained in (25). That is, equation (29) is obtained.

[0090]

(Equation 29)

In the above equations (26) to (29), β ₁ = log (β _m1 /
Although β _c1 ) has been _treated as a constant, it is better to consider that the filter characteristics of the measurement filter and the calibration filter fluctuate in a long term (for example, half a year). Log beta ₁ of the ratio of the transmittance of the calibration filter and the measurement filter for turbidity measurements as a function of time, it expressed using a (16), (17) measured in the reference optical path obtained from equation (30 ) Is obtained.

[0092]

[Equation 30]

4) Relational Expression for Chromaticity Measurement in the Present Invention The measurement of chromaticity can be obtained in the same manner as the relational expression for turbidity measurement. In the chromaticity measurement, the measurement light signal I in a zero chromaticity zero liquid (C ₂ = 0) using a luminous flux having a wavelength of λ ₂ = 390 nm using equation (2).
The chromaticity (C ₂ = C _2M ) of the sample to be measured can be measured by measuring the measurement light signal I _M2S in _M20 and the chromaticity calibration span liquid (C ₂ = C _2S ) in advance.

[0094] 4.1) Zero solution chromaticity zero (C ₂ = 0) Absorbance B ₂₀ at the zero solution of the measurement light signal I _M20 chromaticity zero (C ₂ = 0) in the, C ₂ = 0 in formula (2) By substituting into the equation (31).

[0095]

(Equation 31)

[0096] 4.2) Chromaticity Calibration Span solution (C ₂ = C measured optical signal I _M2S chromaticity calibration span solution in _{2S) (C 2 = C 2S} ) absorbance B _2S in the
By substituting C ₂ = C _2S into equation (2), it is expressed by equation (32).

[0097]

(Equation 32)

From the equation (32), the measurement cell 1 using the chromaticity standard solution was obtained.
The extinction coefficient α ₂₀ L over the measurement length L is obtained from the equation (33).

[0099]

[Equation 33]

4.3) Chromaticity of water sample to be measured (C ₂ = C _2M )
Measurement (measurement light signal I _M2 ) The absorbance B _2M of the water sample (chromaticity C ₂ = C _2M ) of the chromaticity measurement is
By substituting C ₂ = C _2M into equation (2), it is expressed by equation (34).

[0101]

(Equation 34)

Therefore, the chromaticity calculation output T _2M (= C _2M ) is (3
From equations (3) and (34), it is expressed by equation (35).

[0103]

(Equation 35)

As in the equation (15), at the chromaticity measurement wavelength λ ₂ = 390 nm, there is also absorption of light based on the turbidity component, and it is necessary to correct this turbidity component. The chromaticity calculation output T _{2M in} equation (35) is corrected to equation (36). Here, k ₂₁ is a correction coefficient of the turbidity component.

[0105]

[Equation 36]

From equation (36), the span calibration solution concentration C _2S is _calculated as
Absorbance B ₂₀ at zero fluid calibration, and stores the measurement operation data between the absorbance B _2S during span liquid calibration calculation unit CAL comprising a central processing unit (CPU), performs correction calculation in turbidity output T _1M , The chromaticity T _2M ′. 4.4) the test water (C ₂ = C _2M) There measured by the filter (Fc2) for span calibration in the state test water (C ₂ = C _2M) There filter in the state span calibration (Fc
The measurement light signal I _{C2 that} has passed through 2) is calculated by using the transmittance β _m2 of the measurement filter Fm2 and the transmittance β of the calibration filter Fc2 according to equation (2).
_By substituting _C2 and further substituting C ₂ = C _2M into equation (2), it is represented by equation (37).

[0107]

(37)

Here, by subtracting equation (34) from equation (37),

[0109]

(38)

Here, β ₂ is the logarithm of the ratio of the transmittance β _m2 of the measurement filter Fm2 to the transmittance β _C2 of the calibration filter Fc2, and is the difference between the absorbance of the calibration filter and the absorbance of the measurement filter. (Equivalent to the amount of light absorbed by the standard solution in the measurement cell 1). The chromaticity equivalent value T of this absorbance difference
_{When the value of 2} is calculated, Expression (39) is obtained.

[0111]

[Equation 39]

Here, assuming that the initial value of the chromaticity equivalent value T ₂ is T ₂₀ , the chromaticity calculation output obtained by performing the gain variation correction of the equation (36)
Col becomes (40).

[0113]

(Equation 40)

As in the case of the equation (30), the above (37) to (3)
In equation (9), β ₂ = log (β _m2 / β _c2 ) has been _treated as a constant, but the optical filter (for measurement and span calibration)
When be regarded as characteristic of being long term variation even at a wavelength 390nm chromaticity measurement, the ratio of the transmittance of the calibration filter and the measurement filter for chromaticity measurement log beta _2, as a function of time
Expression (41) is obtained by using measured values in the reference optical path obtained from Expressions (18) and (19).

[0115]

[Equation 41]

Next, the relational expression for measuring turbidity and chromaticity according to the present invention will be further examined. In the present invention, since the reference light signal is also configured to enter the detection element via the optical filters (Fm1, Fm2, Fc1, Fc2), the measurement light signal and the reference light signal are the same optical filter (Fm1, Fm2, Through Fc1, Fc2), it is measured in the same wavelength band, and the absorbance is calculated by the logarithm of the ratio of these measured values. In other words, even if there is a change in the spectral characteristics of the light source or the spectral characteristics of the photodetector, the measurement light signal and the reference light signal relatively fluctuate, but the ratio of the measured values is constant and affects the spectral characteristics change Not done.

Taking this relationship as an example of turbidity, the prior art and the present invention are compared. The absorbance output A ₁₀ (t) of the turbidity zero liquid of the prior art is expressed by equation (5) as a function of time, and becomes (42).

[0118]

(Equation 42)

Here, I ₀₁ (t) and P ₀₁ (t) are the radiant intensity of the light source L and the photoelectric conversion constant of the photodetector PD, and are affected by spectral characteristics and changes over time. In the method of the present invention, the absorbance output B ₁₀ (t) of the zero turbidity liquid is expressed by equation (21) as a time function, and becomes (43).

[0120]

[Equation 43]

In the equation (43), the terms I ₀₁ (t) and P ₀₁ (t) in the equation (42) are deleted, and do not affect the absorbance output. The term k ₁ (t) is the influence of the contamination of the measuring cell 1, and the adhesion and growth of the contamination are prevented by the periodic automatic cleaning of the inner wall of the cell. If the stain is not extremely dirty, the influence of the stain can be avoided by updating the value of the zero point output B ₁₀ (t) of the absorbance at the time of zero liquid calibration.

Further, in the measurement / calculation method of the present invention, the transmitted light of the calibration filters (Fc1 and Fc2) and the measurement filters (Fm1 and Fm1) are used.
Difference between the absorbance of the transmitted light fm2) (beta _1, such as beta ₂₎ is (2
Equations 7) and, as shown in equation (38), the present inventors have found that the cells are not affected by the absorbance from the same medium in the same optical path, such as cell contamination. It can be used positively for correction of characteristic fluctuations of electronic circuits such as photodetectors and amplifiers, and also for self-diagnosis of an absorptiometer. Incidentally, the absorbance difference (beta _1, beta _2, etc.) signals,
Complex and expensive span calibration drive mechanism 8 in the prior art
Can be omitted, and when performing conventional span calibration, 3.
As described in section 2), whether the measurement is performed by replacing the sample in the measurement cell 1 with the standard solution, or as a simple method, by replacing the sample in the measurement cell 1 with the zero solution. Although it is a method, in the present invention, the span calibration measurement can always be performed while the water measurement of the measurement cell 1 is in the measurement cell 1 as it is.

Also, the absorbance value B of the span calibration standard solution
Similarly, the difference signal between _1S (t) and the absorbance value B ₁₀ (t) of the zero solution is also canceled by the difference between the expressions (21) and (22), and there is no influence of cell contamination. Can be said. In the equation (29), even if the cell becomes dirty, the denominator term B _1S (t) −B ₁₀ (t) is not affected by the cell contamination, so the data at the time of shipment from the manufacturer is stored in the memory. This data can be used for a long time. As for the concentration C _1S of the span calibration standard solution of the molecule of the equation (29), the data at the time of shipment from the manufacturer can be used for a long time. However, (29)
Since B ₁₀ (t) of the numerator of the formula is affected by cell contamination,
It is necessary to update and store the data each time the zero liquid calibration is performed.

The value of β _{1 in} the equations (27) and (30) is more appropriate when it is considered that there may be a drift after a lapse of more than six months, for example. Measured by the measuring optical path, (27) a beta ₁ values obtained from the beta type ₁₁ (t), the measured with the reference optical path, the beta ₁ of the value obtained from equation (30) beta ₁₂ (t) Then, these values should be originally the same value. However, in practice, the absorbance B ₁₀ (t) of the zero liquid has a variation with time due to the influence of cell contamination, and β ₁₁ (t) is affected by the change. Β in equation (30)
_{Since 12} (t) is a signal that can be more accurately measured in terms of the light receiving signal level, the number of calculations, and the like, β ₁₂ (t) is treated as a positive signal and β ₁₁ (t) is treated as a sub-signal.

Similarly to the case of the turbidity measurement, in the case of the chromaticity measurement, the value of β _{2 in} the equations (38) and (41) should be considered to have a drift. Measured by the measuring optical path, (38) beta ₂ values obtained as the beta ₂₁ (t) from the equation determined by the reference optical path, (41) a beta ₂ values obtained from the equation beta ₂₂
Given (t), these values should essentially be the same. However, in practice, the absorbance B ₂₀ (t) of the zero solution has a temporal variation due to the influence of cell contamination, and β ₂₁ (t) is affected by the change. Since β ₂₂ (t) in equation (41) is a signal that can be more accurately measured, β ₂₂ (t) is a positive signal, β ₂₁ (t)
Are treated as sub-signals. Chromaticity measurement differs from turbidity measurement in that the measurement wavelength changes from 660 nm to 390 nm, and that there is a turbidity correction term to remove the effect of turbidity.
Hereinafter, the turbidity measurement will be mainly described.

In the equation (29), T ₁₀ / T ₁ = β ₁₂ (0) / β
Since it is ₁₂ (t), equation (29) can be expressed as equation (44).

[0127]

[Equation 44]

Here, β ₁₂ (0); data at the time of shipment from the manufacturer β ₁₂ (t); data at time t after the shipment from the manufacturer (44) _1M (t) and β ₁₂ (t). In B ₁₀ (t), measurement and updating are performed each time the zero liquid calibration is performed, and the measurement data obtained in the previous zero liquid calibration is used in the normal calculation. For other items, the data at the time of shipment from the manufacturer can be used.

As described above, according to the present invention, the optical filters Fc1 and Fc2 are added to the filter wheel 2, and
The optical path of the reference light also has a structure that transmits these optical filters, so that the amount of optical information can be dramatically increased as compared with the related art. FIG. 4 is a flow chart for performing a self-diagnosis of the absorptiometer, which can provide a self-diagnosis function for zero liquid calibration, automatic gain correction, and various abnormalities.

In FIG. 4, at step S1, the wavelength λ₁= 660n
The reference optical signal of the reference optical path by the measurement filter Fm1 of m
And the measured value is used as the initial value I of the reference light signal._R1(0) and
Compare. Similarly, in step S2, the wavelength λ₁Calibrated at 660nm
The reference light signal in the reference light path using the filter Fc1
And the initial value I of the reference light signal_R3Compare with (0). Steps
If this value is less than 0.8 for both S1 and S2, the light source L is emitted.
Insufficient intensity, photometer error (1) in step S3
Considering the life of the light source lamp L, replacement of the light source lamp L
The point can be detected. Either step S1 or S2 is 0.8
If No in the following, the process proceeds to step S4, where β₁₂Calculate (t)
I do. In step S5, the calculated value and the initial value β ₁₂(0) and
Compare. For example, in the flowchart of FIG.
If there is, in this case the fluctuation of the absorbance due to the optical filter
Is more than 20% of the initial value,
It is considered that the optical filter has deteriorated as a meter abnormality (2).
Then, the necessity of replacing the optical filter can be detected.

If the change in the absorbance is not more than 20% of the initial value in step S5, the process proceeds to step S7, where the filter Fm1 for measurement and the filter Fm1 for calibration are used at the wavelength λ ₁ = 660 nm.
The measurement optical signal of the measurement optical path by Fc1 is measured, and β ₁₁ (t) is measured and calculated from the difference between the two absorbances. In step S8, the absorbance difference β ₁₁ (t) is compared with β ₁₂ (t), and the difference between the two is
For example, if it exceeds 5%, a change in B ₁₀ (t) at the current measurement is predicted from the data B ₁₀ (0) at the time of the previous periodic zero solution calibration. Is automatically transmitted, and zero liquid calibration is performed in step S10. Normally, the zero liquid calibration is periodically performed based on the periodic instruction from step S9. When the zero solution calibration is performed in step S10, the newly measured and calculated absorbance B ₁₀ (t) and absorbance difference β ₁₁ (t) data of the zero solution are updated and recorded in the memory. In step S11, the data of the newly measured and calculated new absorbance difference β ₁₁ (t) is compared again with the absorbance difference β ₁₂ (t) measured in the optical path for the reference light. If it exceeds 5%, the absorbance B ₁₀ (t) of the zero solution is compared with this initial value B ₁₀ (0) in step S12. If this ratio exceeds 1.2, the photometer is abnormal at step S14.
As (4), it is considered that the measurement cell is very dirty, and the necessity of cleaning the measurement cell can be detected. When this ratio is within 1.2,
The characteristic fluctuation of the electronic circuit including the photodetector
In S13, it is regarded as a photometer abnormality (3), which is regarded as a calculation failure. If the fluctuations are within 5% in both steps S8 and S11, step S1
In step 5, the characteristics of the electronic circuit including the photodetector are changed, and the gain correction calculation is automatically performed on the output of the absorptiometer.

The absorptiometer of the present invention indirectly monitors the drift over time of the absorbance of the zero liquid, monitors the gain fluctuation of the electronic circuit including the photodetector, and corrects this gain in the measuring cell 1. The test can be performed with the sample 1A in place, so the sample 1A can be stopped, the zero solution can be flowed, and the frequency of zero solution calibration can be reduced regularly. By automatically transmitting and performing zero liquid calibration, highly accurate and reliable measurement as an absorptiometer can be performed, and operation time can be extended.

In addition to the above-mentioned calculation of {β ₁₁ (t) −β ₁₂ (t)}, I _R1
Instead of using I _R3 ,

[0134]

[Equation 45]

[0135]

[Equation 46]

It is also possible to directly monitor the difference in the absorbance in the equation (46) and set an allowable value. In the self-diagnosis flow chart of FIG. 4, as an example, 20%, 5%
Although the specific numerical value of% is described, it is appropriately determined depending on the measurement range, the accuracy, and the like as an absorptiometer. Although the turbidity measurement of the present invention has been described above, the chromaticity measurement can be said to be the same as the turbidity except for the wavelength, so that the arithmetic output Col of the chromaticity corresponding to the expression (40) is ( 47) can be expressed as:

[0137]

[Equation 47]

[0138] Similarly to turbidity, self-diagnosis can be performed for chromaticity. Although the present invention has been described only for the measurement of turbidity and chromaticity, the other wavelengths are measured by changing the wavelength, for example, mixing a reagent in a test water, measuring the reaction color at an optimal wavelength, and measuring a trace amount of a specific substance. The present invention can also be applied to the measurement of

[0139]

As described above, according to the structure of the present invention, the filter wheels (Fm1, Fm2) for measuring the turbidity and chromaticity and the calibration filters (Fc1, Fc) are provided on the filter wheel.
2) The measurement light signal at the time of measurement and calibration is such that light from a light source enters the measurement cell alternately through the optical filter for measurement or the optical filter for reference, and passes through the measurement cell. Via the measurement optical path to the detection element. In addition, the reference light signal extracts a part of the light from the light source, passes through an optical path different from the optical path for measurement, enters the photodetector via the optical filter of the filter wheel, and passes through the optical path for measurement. The light enters the photodetector at a different timing from the timing of the light pulse.

In this configuration, the reference light signal enters the same detecting element at different timings via the same optical filter (Fm1, Fm2, Fc1, Fc2). Therefore, the measurement light signal and the reference light signal are measured in the same wavelength band through the same optical filter (Fm1, Fm2, Fc1, Fc2), and from the logarithm of the ratio of the measurement value of the measurement light signal and the reference light signal, The absorbance is calculated. That is, the measurement can be performed without being affected by the change in the spectral characteristic of the light source or the change in the spectral characteristic of the photodetector.

Further, in the above arrangement, the difference in absorbance between the calibration optical filter and the measurement optical filter is determined by the ratio of the reference light signal transmitted through the measurement wavelength filter and the calibration filter having the same wavelength via the reference optical path. Calculates the absorbance of the logarithmic value of β ₁₂ , β ₂₂ , or the light transmitted through the measurement optical filter and calibration optical filter of the same wavelength via the measurement optical path, and is measured by the optical path passing through the calibration optical filter. The values β ₁₁ and β ₂₁ , which are obtained by subtracting the absorbance measured by the optical path passing through the optical filter for measurement from the measured absorbance, are calculated, and the optical filter for measurement and the optical filter for calibration at the measurement wavelength are calculated from the calculated values. Can be measured.

As a result, the conventional span calibration drive mechanism can be dispensed with. Further, without changing the water sample in the measurement cell, the transmittance ratios (β ₁₁ , β ₁₂ ), (β ₁₁ ) of the optical filter for measurement and the optical filter for calibration
₂₁ , β ₂₂ ) can be calculated, so when performing span calibration in the prior art, replace the sample with zero solution and measure with a calibration optical filter, or replace the sample with a calibration standard solution and measure Although it was necessary to measure with a filter, the work of replacing the water sample is not required, so span calibration can be always performed without interrupting the measurement of turbidity and chromaticity.

Further, a major feature of this calculation method is that the initial value (for example, data at the time of shipment from the manufacturer) of the transmittance ratio of the measurement filter and the calibration filter to be measured and calculated, and the measurement filter and the calibration filter at the time of measurement. Diagnostic information such as the life of the light source lamp, deterioration of the optical filter, operation failure, or large cell contamination can be obtained by a predetermined calculation determination procedure based on a temporal change with the transmittance ratio of the filter.

The transmittance ratios of the measurement filter and the calibration filter were both measured at the same wavelength in an optical path passing through a reference optical path and a measurement optical path.
_When the ratio of the difference between ( ₁₁ , β ₁₂ ) and (β ₂₁ , β ₂₂ ) is within a predetermined range, the gain correction calculation process is performed, and the ratio of the difference between the two calculation values is outside the predetermined range. At this time, an instruction for zero liquid calibration can be given.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a main part of an embodiment of the present invention.

FIG. 2 is an arrangement diagram of an optical filter on a filter wheel.

FIG. 3 is an explanatory diagram illustrating waveforms and timing relationships of a measurement optical signal and a reference optical signal.

FIG. 4 is a flowchart for performing self-diagnosis of the absorptiometer of the present invention.

FIG. 5 is a configuration diagram of a main part of a conventional technique

FIG. 6 is a layout diagram of an optical filter on a prior art filter wheel.

FIG. 7 is an explanatory diagram illustrating waveforms and timing relationships of a measurement optical signal and a reference optical signal according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Measurement cell 1A Water sampling 2 Filter wheel 3 Position sensor 4, 41, 42 Optical fiber 4A, 4B, 41A, 41B, 42A, 42B Optical fiber end face 5 Notch 6A, 6B Reflector 7 Receiver cover 8 Span calibration drive Mechanism 9 Arithmetic unit PD Photodetector PA Amplifier A / D, D / AA / D, D / A converter CAL Arithmetic unit I / O Digital input / output circuit L Light source LH Lamp house Fm1, Fm2 Optical filter for measurement Fc1, Fc2 Calibration optical filter M Measurement light path R Calibration light path I _M1, I _M2, measurement light signal I _C1, I _C2 Calibration light signal I _R1, I _R2, I _R3, I _R4 Reference light signal B ₁₀ , B _1S , B _1M absorbance difference between β ₁₁ , β ₁₂ , β ₂₁ , β ₂₂

Continued on the front page (72) Inventor Koji Yamada 613 Kitairiso, Oaza, Sayama, Saitama Prefecture Inside the Sayama Plant (72) Inventor Fumio Toyama 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Fuji Electric Inside (72) Inventor Yasushi Zaitsu 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. (72) Inventor Go Yamamoto 1-1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki, Kanagawa Fuji Electric (56) References JP-A-4-315020 (JP, A) JP-A-49-56688 (JP, A) JP-A-4-244924 (JP, A) JP-A-4-29866 (JP, A) U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/00-21/61

Claims (5)

(57) [Claims] 1. A measuring cell into which water is introduced, a light source provided at one end of the measuring cell with a first gap between the measuring cell, and another end of the measuring cell. A light detecting element provided on the side, a calculating device for calculating the detection output of the light detecting element, a first optical fiber having a part of light emitted from the light source coupled to one end thereof, A second optical fiber which has one end opposed to the other end of the one optical fiber with a second gap therebetween, and guides a part of the light emitted by the light source to the photodetector; A filter for measurement and a filter for calibration provided respectively at predetermined positions on the same radius from the center of rotation thereof, and rotate the filter for measurement or the filter for calibration to the first or second filter. And a filter wheel positioned in the gap between A fixed optical path is formed from the light source through the measurement cell to the photodetector via the measurement filter located in the first gap during measurement, and is located in the first gap during calibration. The reference optical path is formed from the light source through the first and second optical fibers to the light detection element, and the measurement optical path is located in the second gap during measurement. Self-diagnosis method of the absorptiometer formed through the calibration filter formed through the calibration filter and formed at the time of calibration through the calibration filter positioned in the second gap.
A law, the difference in absorbance of the calibration filter and the measurement filter
The reference light transmitted through the measurement filter of the reference optical path.
Of the ratio of the signal and the reference light signal transmitted through the calibration filter
Calculate by logarithmic value, and based on the change over time of the calculated value, the measurement filter
And detecting a deterioration of the calibration filter . 2. A first measuring device, comprising: a measuring cell into which a sample is introduced; and a measuring cell at one end of the measuring cell.
A light source provided with a gap, a light detection element provided on the other end side of the measurement cell, a calculation device for performing arithmetic processing on a detection output of the light detection element, and one of light emitted from the light source. Part is joined to its one end
A first optical fiber, facing the other end of the first optical fiber with a second gap
Part of the light emitted by the light source, having one end disposed
And a second optical fiber that guides the light to the photodetector, and is rotatably provided, and has the same radius from the center of rotation.
Measuring filter and calibration
And a filter for rotating the measurement filter or
Positioning the calibration filter in the first or second gap
And a filter wheel that causes the measurement light path to pass through the measurement cell from the light source.
Up to the photodetector, located in the first gap at the time of measurement
It is formed via the measurement filter, and is
Via the calibration filter located in the first gap
And a reference optical path is formed from the light source to the first and second optical paths.
Through a fiber to the photodetector, during measurement
Formed via the measurement filter located in the gap 2
During calibration, the calibration
Self-diagnosis method of absorption spectrophotometer formed through filter
A law, the difference in absorbance of the calibration filter and the measurement filter
Is the measuring light transmitted through the measuring filter of the measuring optical path.
Measured from signal and measurement optical signal transmitted through calibration filter
Calculate the absorbance of the filter for calibration and the filter for calibration.
The absorption of the measurement filter is calculated based on the calculated absorbance of the calibration filter.
Calculate by the value obtained by subtracting the luminous intensity, and based on the time-dependent change of the calculated value, the measurement filter
And detecting the deterioration of the calibration filter,
Self-diagnosis method of absorptiometer. 3. A first measuring device, comprising: a measuring cell into which a sample is introduced; and a measuring cell at one end of the measuring cell.
A light source provided with a gap, a light detection element provided on the other end side of the measurement cell, a calculation device for performing arithmetic processing on a detection output of the light detection element, and one of light emitted from the light source. Part is joined to its one end
A first optical fiber , facing the other end of the first optical fiber with a second gap
Part of the light emitted by the light source, having one end disposed
And a second optical fiber that guides the light to the photodetector, and is rotatably provided, and has the same radius from the center of rotation.
Measuring filter and calibration
And a filter for rotating the measurement filter or
Positioning the calibration filter in the first or second gap
And a filter wheel that causes the measurement light path to pass through the measurement cell from the light source.
Up to the photodetector, located in the first gap at the time of measurement
It is formed via the measurement filter, and is
Via the calibration filter located in the first gap
And a reference optical path is formed from the light source to the first and second optical paths.
Through a fiber to the photodetector, during measurement
Formed via the measurement filter located in the gap 2
During calibration, the calibration
Self-diagnosis method of absorption spectrophotometer formed through filter
A law, the difference in absorbance of the calibration filter and the measurement filter
The reference light transmitted through the measurement filter of the reference optical path.
Of the ratio of the signal and the reference light signal transmitted through the calibration filter
Calculated by logarithmic value, the difference in absorbance between the measurement filter and the calibration filter
Is the measuring light transmitted through the measuring filter of the measuring optical path.
Measured from signal and measurement optical signal transmitted through calibration filter
Calculate the absorbance of the filter for calibration and the filter for calibration.
The absorption of the measurement filter is calculated based on the calculated absorbance of the calibration filter.
Calibration calculated by subtracting the luminous intensity and measured and calculated at the same wavelength in the reference optical path
The difference between the absorbance of the filter and the absorbance of the
Calibration file measured and calculated at the same wavelength in the fixed optical path
The difference between the absorbance of the filter and the absorbance of the measurement filter.
If the ratio of the calculated value difference is out of the specified range,
A self-diagnosis method for an absorptiometer , wherein calibration is performed . 4. A method for self-diagnosis of an absorptiometer according to claim 3.
After the zero solution calibration, the difference between the two calculated values is calculated.
If the value is outside the specified range, the absorbance at zero solution calibration
Of the measuring cell of the spectrophotometer
A self-diagnosis method for an absorptiometer , which detects . 5. The light absorption according to claim 3 or claim 4.
In the self-diagnosis method of the photometer , calibration and measurement were performed at the same wavelength in the reference optical path.
The difference between the absorbance of the filter and the absorbance of the
Calibration file measured and calculated at the same wavelength in the fixed optical path
The difference between the absorbance of the filter and the absorbance of the measurement filter.
When the ratio of the difference between the calculated values is within the specified range, the gain
Self-correcting absorptiometer that performs a correction calculation process.
Self-diagnosis method.