JP2008070293A - Water quality measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact water-quality measuring apparatus having no mechanical operation section. <P>SOLUTION: In the water quality measuring apparatus for measuring the characteristics of measured liquid based on the absorbance of the measured liquid in a cell, light from a light source 1 is made to come into the cell 3, the light having transmitted through the cell 3 is made to come into a light condensing optical means 4, the light having reflected and condensed by the light condensing optical means 4 is made to come into a first detector 5, the light having reflected and condensed by the light condensing optical means 4 and then having transmitted through the cell 3 is made to come into a second detector 6, and the absorbance is measured based on the ratio between the output from the first detector 5 and the output from the second detector 6. The turbidity and chromaticity of the measured liquid is measured. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a water quality measuring apparatus for measuring characteristics of a liquid to be measured such as chromaticity and turbidity by measuring absorbance.

FIG. 2 is a diagram illustrating a configuration example of a conventional water quality measurement apparatus. Reference numeral 11 denotes a light source, and reference numerals 12a and 12b denote optical means (hereinafter referred to as "mirror") including a concave mirror for converting the light emitted from the light source 11 into a parallel light beam. Reference numeral 13 denotes a measurement cell having a predetermined length that can fill the inside with the reference liquid and the measurement liquid, and the parallel light from the mirror 12a is incident thereon. Reference numeral 14 is a comparison cell provided for comparison with the measurement value in the measurement cell 13 and having a predetermined length (here, shorter than the cell length of the measurement cell 13) that can fill the reference liquid and the measurement liquid. Parallel light from the mirror 12b is incident. The measurement cell 13 and the comparison cell 14 are connected by a flow path (not shown) so that the same sample solution can pass therethrough. Reference numeral 15 denotes a disk-shaped filter wheel on which 390 nm and 660 nm filters 16 are attached one by one at an angle of 90 degrees, and are rotated at a constant speed. The measurement light exiting from the measurement cell 13 and the comparison light exiting from the comparison cell 14 intermittently pass through the two filters 16 and then are reflected and converged by the concave mirrors 17a and 17b, respectively, to be focused at the position of the detector 18. . Then, the detector 18 detects the intensity of two kinds of light of each of the measurement light and the comparison light, and the total of four kinds of transmitted light. Absorbances Ac and At in the effective cell length of chromaticity light (390 nm) and turbidity light (660 nm) are expressed by the following equations.
Absorbance in chromatic light: Ac = -log [(I _CMM / I _CM0 ) / (I _CRM / I _CR0 )] = k ₁ · C (l _M −l _R ) (1)
Absorbance in turbidity light: At = -log [(I _TMM / I _TM0 ) / (I _TRM / I _TR0 )] = k ₂ · T (l _M −l _R ) (2)

From these two absorbances, the concentrations of chromaticity C and turbidity T are calculated by the following equation.
Chromaticity: C = β ₁ (Ac−αAt) (3)
Turbidity: T = γ ₁ At (4)

However,
α: Turbidity compensation coefficient β ₁ : Chromaticity coefficient γ ₁ : Turbidity coefficient
I _CR0 : Comparison cell light intensity (chromaticity light) when zero liquid (reference liquid) is added
I _CRM : Light quantity transmitted through the comparison cell (chromatic light)
I _CM0 : Measurement cell transmitted light (chromatic light) when zero liquid is added
I _CMM : Light intensity transmitted through measurement cell (chromatic light)
I _TR0 : Comparison cell transmitted light (turbidity light) when zero solution (reference solution) is added
I _TRM : Comparison cell transmitted light amount (turbidity light) when measuring solution is put
I _TM0 ： Transmitted light quantity (turbidity light) in the measurement cell when zero liquid is added
I _TMM : Transmitted light quantity (turbidity light) when measuring liquid is added
l _M : Measurement cell length
l _R : Comparison cell length
C: Chromaticity
T: Turbidity.

  Prior art documents related to the water quality measuring apparatus as described above include the following.

No. 8-9633

  In the water quality measuring apparatus having the above-described configuration, the ratio of the amount of transmitted light between the measurement cell 13 and the comparison cell 14 is taken in the calculation of absorbance, so that the influence of fluctuations in lamp brightness and the like can be offset.

Moreover, since two wavelengths are used, chromaticity and turbidity can be measured simultaneously with one apparatus.

Further, since two wavelengths are used, chromaticity that compensates for turbidity mixed in the sample liquid can be measured.

However, since two cells of the measurement cell 13 and the comparison cell 14 are used, there is a problem that the apparatus becomes large.

In addition, since a motor is used to rotate the filter wheel 15 and there is a mechanical operating part, periodic replacement is necessary, and there is a problem that maintenance is troublesome.

  An object of the present invention is to provide a water quality measuring apparatus that can be downsized and does not have a mechanical operating unit.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In the water quality measuring device for measuring the characteristics of the liquid to be measured based on the absorbance of the liquid to be measured in the cell,
A light source;
Condensing optical means for collecting light emitted from the light source and transmitted through the cell;
A first detector for detecting the light collected by the condensing optical means;
A second detector that is detected after the light condensed by the condensing optical means passes through the cell again,
The absorbance is measured based on a ratio between the output of the first detector and the output of the second detector.

The invention according to claim 2
In the water quality measuring device according to claim 1,
The detector includes a turbidity detector and a chromaticity detector.

  As described above, according to the present invention, the transmitted light of the forward light and the round-trip light of a single cell is detected, and the chromaticity and turbidity are measured based on the absorbance obtained from the ratio of both detection outputs. Therefore, it is possible to realize a water quality measuring apparatus that can be miniaturized and does not require a mechanical operating unit.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory view showing an embodiment of a water quality measuring apparatus according to the present invention.

In FIG. 1, light emitted from a light source 1 is converted into parallel light by a lens 2 constituting optical means. In the measurement cell 3, parallel light from the lens 2 is incident on an incident window 3 a made of, for example, glass (window glass) provided on the front surface of the cell. The light that has passed through the incident window 3a enters the cell 3b. The cell 3b has a predetermined optical path length and can be filled with a reference solution or a measurement solution. The exit window 3c is provided on the rear surface of the cell 3b, and the light that has passed through the inside of the cell 3b is incident thereon. The spherical mirror 4 constitutes condensing optical means, and the light that has passed through the exit window 3c is incident thereon. A part of the light reflected and collected by the spherical mirror 4 is incident on the first detector 5 and detected. Another part of the light collected by the spherical mirror 4 is incident on the second detector 6 via the exit window 3c, the cell 3b, and the entrance window 3a of the measurement cell 3 and detected. Here, the light source 1, the lens 2, the entrance window 3a, the cell 3b, the exit window 3c, the spherical mirror 4, the first detector 5, and the second detector 6 are disposed on the same optical axis.

Although two detectors are shown in FIG. 1, actually, a total of four detectors are used, two each for chromaticity and turbidity. That is, in FIG. 1, the first detector 5 includes a turbidity detector 5a and a chromaticity detector 5b arranged in a direction perpendicular to the paper surface, and the second detector 6 includes a turbidity detector 6a and a chromaticity detector. The detector 6b is arranged side by side in the direction perpendicular to the paper surface. In this case, a turbidity light (660 nm) filter is affixed to the front surfaces of the turbidity detectors 5a and 6a, and a chromaticity light (390 nm) filter is affixed to the front surfaces of the chromaticity detectors 5b and 6b.

The operation of the water quality measuring apparatus will be described below. The parallel light emitted from the lens 2 is absorbed by the liquid (reference liquid or measurement liquid) in the cell 3b while propagating through a predetermined optical path length in the cell 3b in the forward path. The first detector 5 detects the transmitted light that has been absorbed in the forward path. In the transmitted light incident on the second detector 6, the light converged by the spherical mirror 4 is again absorbed by the liquid in the cell 3b in the return path (in the opposite direction to the forward path). The optical path length is twice that of the incident light from the first detector 5. At this time, the absorbance, turbidity, and chromaticity are calculated by the following equations.

For turbidity,
I _T1 / I _T10 = 10 ^{-kT * l * T}
I _T2 / I _T20 = 10 ^{-kT * 2 * l * T}
Abs (T) = − log {( _IT2 / _IT20 ) / ( _IT1 / _IT10 )}
= K _T * T * (2 * l−l)
= K _T * l * T (5)
T = γ ₂ * Abs (T) (6)
It becomes. However,
I _T10 : Transmitted light signal of turbidity detector 5a when zero solution (reference solution) is added
I _T1 : Transmitted light signal of the turbidity detector 5a when the measuring solution is added
I _T20 : Transmitted light signal of turbidity detector 6a when zero liquid is added
I _T2 : Transmitted light signal of turbidity detector 6a when measuring solution is put
k _T : Absorption coefficient of turbidity
l: Optical path length of single optical path of measurement cell 3
T: Turbidity
Abs (T): Absorbance of turbidity γ ₂ : Turbidity coefficient (Actually, the absorbance Abs (T) of the turbidity standard solution is measured by equation (6))
It is.

For chromaticity,
I _C1 / I _C10 = 10 ^{-kC * l * C}
I _C2 / I _C20 = 10 ^{-kC * 2 * l * C}
Abs (C) = − log {(I _C2 / I _C20 ) / (I _C1 / I _C10 )}
= K _C * C * (2 * l−l)
= K _C * l * C (5)
C = β ₂ * Abs (C) (6)
It becomes. However,
I _C10 : Transmitted light signal of chromaticity detector 5b when zero liquid (reference liquid) is added
I _C1 : Transmitted light signal of the chromaticity detector 5b when the measurement solution is added
I _C20 : Transmitted light signal of chromaticity detector 6b when zero liquid is added
I _C2 : Transmitted light signal of chromaticity detector 6b when measuring solution is put
k _C : Chromatic extinction coefficient
l: Optical path length of single optical path of measurement cell 3
C: Chromaticity
Abs (C): chromaticity of absorbance beta _2: chromaticity coefficient (actually determined by measuring the absorbance Abs (C) chromaticity standard solution in (6))
It is.

  According to the water quality measuring apparatus having the above-described configuration, it is not necessary to use two types of cells, a comparison cell and a measurement cell, as in the prior art, and a single measurement cell is used. .

  In addition, since the absorbance is measured based on the detection output of the round trip light and the forward light, a mechanical operating unit is unnecessary and periodic replacement is unnecessary.

  Further, as shown in the equation (5), since the ratio of the transmitted light signal between the round trip path and the forward path is taken when calculating the absorbance, the influence of fluctuations in the lamp luminance of the light source 1 can be offset.

Moreover, since two wavelengths are used, chromaticity and turbidity can be measured simultaneously with one apparatus.

Since two wavelengths are used, the chromaticity that compensates for the turbidity mixed in the sample liquid can be measured in the same manner as the equation (3).

  In the above embodiment, the case where the characteristic of the liquid to be measured is chromaticity and turbidity is shown. However, even if one of chromaticity or turbidity is detected using a chromaticity detector or turbidity detector, Good.

Further, the present invention is not limited to chromaticity and turbidity, and can be applied to measurement of various characteristics of a liquid to be measured that is measured based on absorbance.
In the above embodiment, a spherical mirror is used as the condensing optical means, but various condensing optical means that can be re-incident on the measuring cell 3 such as an interference film can be used.

It is explanatory drawing which shows one Example of the water quality measuring apparatus which concerns on this invention. It is explanatory drawing which shows an example of the conventional water quality measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 3 Cell 4 Condensing optical means 5 1st detector 6 2nd detector

Claims (2)

In the water quality measuring device for measuring the characteristics of the liquid to be measured based on the absorbance of the liquid to be measured in the cell,
A light source;
Condensing optical means for collecting light emitted from the light source and transmitted through the cell;
A first detector for detecting the light collected by the condensing optical means;
A second detector that is detected after the light condensed by the condensing optical means passes through the cell again,
An apparatus for measuring water quality, wherein the absorbance is measured based on a ratio between an output of the first detector and an output of the second detector. The water quality measuring apparatus according to claim 1, wherein the detector includes a turbidity detector and a chromaticity detector.

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