JP2002048714A - Turbidity measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbidity measuring device capable of improving measuring accuracy, making effective use of the measuring range of a photo detector. SOLUTION: This turbidity measuring device is provided with a luminous flux separating means 50 for separating luminous flux 80 from a light source 20 into first luminous flux 80a advancing in a first direction and a second luminous flux 80b advancing in a second direction different from the first direction, a first optical path through which at least a part 82 of the first luminous flux 80a is led to a photo detector 36, a second optical path through which a part 84 of scattered light from a measured liquid in a cell 28 irradiated with the second luminous flux 80b is led to the photo detector 36, and a luminous flux selecting means 32 for selectively shutting off either one of the first and second optical paths.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a turbidity measuring device, and more particularly, to a turbidity measuring device having one light source and one photodetector.

[0002]

2. Description of the Related Art Conventionally, a turbidity measuring device which irradiates a liquid to be measured with light, receives scattered light from the liquid to be measured and measures the turbidity of the liquid to be measured has been used. In such a device,
In order not to be affected by the brightness fluctuation of the light source,
The light source light is measured and the measured value of the scattered light from the liquid to be measured is corrected.In this case, the light from the light source and the scattered light from the liquid to be measured are separated by using separate photodetectors. When measurement is performed, variations in characteristics between photodetectors cause measurement errors. Therefore, a turbidity measuring device that measures light from a light source and light scattered from a liquid to be measured by one photodetector has been proposed.

For example, in the turbidity measuring apparatus shown in FIG. 1, light from a light source lamp 1 is converted into a parallel light beam by a collimator lens 2, and then the parallel light beam is stopped down to an appropriate diameter by a stop 3, and filled with the liquid to be measured. The cell 4 having a glass window on the road surface is irradiated.
The light beam from the cell 4 forms an image on the photosensor 7 by the lens 6. In this device, a shutter 5 that rotates between a blocking position indicated by a solid line and a transmission position indicated by a dotted line is provided to selectively block a parallel light flux (transmitted light) 9 transmitted through the cell 4. I have. Thus, when the transmitted light 9 is cut by the shutter 5, only the scattered light is received, and when the transmitted light 9 is not cut, the scattered light and the transmitted light are received. In each case, the intensity of the received light is reduced. The turbidity value is determined based on the turbidity value (for example, JP-A-6-273330).

[0004]

However, in such an apparatus, it is necessary to measure the sum of the intensity of the scattered light and the intensity of the transmitted light within the measurement range of the photosensor 7, so that the intensity of only the scattered light is measured. For the measurement, the measurement range (10
At most, only (intensity of scattered light) / (sum of scattered light and transmitted light) × 100% is available. Therefore, in order to increase the measurement resolution for scattered light and improve the measurement accuracy of turbidity, it is necessary to increase the resolution of the photosensor 7 itself.

[0005] Therefore, a technical problem to be solved by the present invention is to provide a turbidity measuring device capable of improving the measuring accuracy by effectively utilizing the measuring range of the photodetector.

[0006]

The present invention provides a turbidity measuring device having the following configuration in order to solve the above technical problems.

The turbidity measuring device irradiates a liquid to be measured in a cell with a light flux from one light source, receives the light with one photodetector, detects the intensity of light from the cell, and, based on this, This is a type for measuring the turbidity of the liquid to be measured. The turbidity measuring device converts the light beam from the one light source into a first light beam traveling in a first direction and a second light beam different from the first direction.
A light beam separating unit that separates the light beam into a second light beam traveling in the direction of, a first light path through which at least a part of the first light beam is guided to the photodetector, A second optical path, in which a part of the scattered light from the liquid to be measured is irradiated to the liquid to be measured and guided to the photodetector, and one of the first and second optical paths is selected. Light beam selecting means for selectively blocking.

In the above arrangement, the light beam is not necessarily a parallel light beam, but is preferably a parallel light beam. In this case, even if the light beam from the light source is already converted into a parallel light beam before being separated into the first and second light beams, the first and second light beams from the light source have different directions.
May be configured so that each of them becomes a parallel light beam for the first time after being separated into the above light beams.

Further, even if the first optical path is configured such that the first light beam is guided to the photodetector after passing through the cell, the first light beam is guided to the photodetector without passing through the cell. You may be comprised so that it may be.

Further, the light beam selecting means can be arranged at an arbitrary position in the first and second light paths between the light beam separating means and the photodetector.

In the above configuration, the photodetector can receive the light beam from one of the first and second optical paths by the light beam selecting means and measure the intensity of the received light beam. Since the measurement can be performed separately and independently in this way, by configuring the light beam separating means and the first and second optical paths, the second light beam is irradiated to the liquid to be measured in the cell, and the measurement target is thereby measured. Of the scattered light from the liquid, a part of the intensity guided to the photodetector and at least a part of the intensity of the first light flux guided to the photodetector are within the measurement range of the photodetector, respectively. It can be made larger.

Therefore, the measurement accuracy can be improved by effectively utilizing the measurement range of the photodetector.

More specifically, it is configured in various modes as follows.

The light beam separating means is a prism disposed on a part of the optical path of the light beam from the one light source. In this case, the light beam from the light source can be separated into a portion leading to the prism and a portion not leading to the prism, so that two light beams traveling in different directions can be obtained.

In another aspect, the light beam separating means includes:
A reflecting mirror is disposed on a part of the optical path of the light beam from the one light source. In this case, the light beam from the light source can be separated into a portion that is reflected by the reflection mirror and a portion that is not reflected, so that two light beams having different traveling directions can be obtained.

According to still another aspect, the light beam separating means is a semi-transmissive reflection member disposed on an optical path of a light beam from the one light source. In this case, the light beam from the light source can be separated into a transmitting portion and a reflecting portion by a semi-transmissive reflecting member (for example, a half mirror or a dichroic prism), so that two light beams having different traveling directions can be obtained.

[0017] Preferably, at least one of the first and second optical paths includes a variable stop means for adjusting a light beam guided to the photodetector in an adjustable manner.

According to the above configuration, the intensity can be adjusted so that the intensities of the light fluxes of the first and second optical paths respectively received by the photodetectors are substantially equal. Therefore, the measurement range of the photodetector can be more effectively used, and the measurement accuracy of the turbidity can be improved.

Preferably, on the light source side from the cell,
The apparatus further includes a wavelength selection unit that transmits a specific wavelength component of the light from the light source.

According to the above configuration, applications such as measurement of the color of particles contained in the measurement liquid and the color of the liquid itself are possible.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A turbidity measuring apparatus according to each embodiment of the present invention will be described below with reference to the drawings.

First, a turbidity measuring device 10 according to a first embodiment of the present invention will be described with reference to FIGS.

As shown in the configuration of FIG.
0 is the light source lamp 20 arranged in order along the optical axis,
First lens 22, filter unit 40, second lens 2
6, prism 50, cell 28, aperture 30, shutter 3
2, a third lens 34, a light receiving element 36, and an arithmetic processing unit 60 connected to the light receiving element 36.

The light from the light source lamp 20 is transmitted to the first lens 2
2 and the second lens 26 make parallel light 80, and the cell 2
Irradiated toward 8. The cell 28 has a transparent window on the optical path surface, and the inside is filled with the liquid to be measured. The prism 50 is disposed so as to enter a part of the optical path of the parallel light 80 toward the cell 28, and a part 80b of the parallel light 80 enters the cell 28 through the prism 50, and another part 80a is directly ( The light enters the cell 28 (without passing through the prism). Since a part 80b of the parallel light incident on the prism 50 is refracted and the traveling direction is bent, the direction exiting from the prism 50 and proceeding into the cell 28 depends on the other part 80a of the parallel light directly incident on the cell 28. And different.

The aperture 30 has first and second apertures 30.
a and 30b are provided. The first opening 30a passes through a part 82 of the parallel light 80a that is directly incident on the cell 28 and travels straight. In the second aperture 30a, the parallel light 80b incident through the prism 50 hits particles contained in the liquid to be measured, and a part 84 of the scattered light generated thereby passes.

The shutter 32 is configured to move in parallel along the stop 30, and has an opening 32a. The shutter 32 is configured such that the opening 82a moves in parallel between a first position facing the first opening 30a of the diaphragm 30 and a second position facing the second opening 30b of the diaphragm 30. Of the luminous fluxes 82 and 84 that have passed through the first or second apertures 30a and 30b of the diaphragm 30, and pass only one of them, and block the other. The light beams 82 and 84 passing through the opening 32 a of the shutter 32 are received by the
6 are collected. The arithmetic processing unit 60 processes the signal from the light receiving element 36,
Obtains the intensity of the received light, and based on this, measures the turbidity of the liquid to be measured.

As shown in FIG. 2, the filter unit 40 includes a circular main body 41 which rotates around a rotation shaft 46.
Four light transmitting portions 42, 43, 44, 45 for transmitting light
Having. The light transmitting portions 42, 43, 44, 45 are red,
Green, blue and near-infrared color filters.
From the same diameter. Filter unit 40
Is a first lens 22 and a second lens 2 as shown in FIG.
6, the light transmitting portions 42, 43,
The light from the light source lamp 20 is transmitted so as to pass through a specific frequency component, and can be converted into parallel light 80.

Next, a method of measuring turbidity using the turbidity measuring device 10 will be described.

First, the shutter 32 is moved so that the opening 32a of the shutter 32 overlaps the first opening 30a of the aperture 30, and the light beam 82 that has moved straight through the cell 28 and passed through the first opening 30a is received by the light receiving element. The light is received at 36 and its intensity Ia is measured. Next, the shutter 32 is moved so that the opening 32 a of the shutter 32 overlaps the second opening 30 b of the aperture 30, and the second opening 30 b of the scattered light from the liquid to be measured by the light beam refracted by the prism 50 is removed. The transmitted light flux 84 is received by the light receiving element 36, and its intensity Ib is measured. Strength Ia, I
The measured value of b is stored in the arithmetic processing unit 60. In addition,
The measurement may be performed in the reverse order.

Next, the arithmetic processing unit 60 calculates the intensity ratio of the luminous flux corrected by using the aperture areas Sa and Sb of the first and second apertures 30a and 30b of the diaphragm 30 stored in advance, that is, (Ib / Sb) / (Ia / Sa) is calculated, and based on this, the turbidity is determined by referring to a table stored in advance.

The opening areas Sa and Sb of the first and second openings 30a and 30b are substantially equal to the intensity of light transmitted through the first and second openings 30a and 30b according to the degree of scattering of the liquid to be measured. If they are selected to be equal, the measurement range (resolution) of the light receiving element 36 can be effectively used to increase the measurement accuracy (resolution). In this case, the first and second openings 30a, 30
The opening areas Sa and Sb of b may be configured to be adjustable.

Further, the turbidity measuring device 10 can measure the color of the particles contained in the liquid to be measured and the color of the liquid itself by including the filter unit 40.

When measuring the color of the particles, the shutter 32
Sets the first opening 30a of the aperture 30 to a position where the second opening 30a is opened. Then, the main body 41 of the cutoff filter unit 40 is sequentially rotated, and each of the color filters 42 to 45 is rotated.
The cell 28 is irradiated with the luminous flux transmitted therethrough, and the intensity of scattered light is measured by the light receiving element 36. The arithmetic processing unit 60 determines the color based on the ratio of these measured values. For example, a saturation or a color name (color name) is determined.

When measuring the color of the liquid itself, the shutter 32
Is set to a position where the first opening 30a of the aperture 30 is opened and the second opening 30a is closed. Then, the main body 41 of the filter unit 40 is sequentially rotated, and the luminous flux transmitted through each of the color filters 42 to 45 is irradiated on the cell 28 to measure the intensity of the transmitted light. The arithmetic processing unit 60 similarly determines the color based on the ratio of these measured values.

Next, the turbidity measuring device 10a of the second embodiment
Will be described with reference to FIG. The same reference numerals are used for the same components as those in the first embodiment, and the description will be made focusing on the differences from the first embodiment.

As shown in FIG. 4, the light from the light source lamp 20 is collimated by the lens 24. A part of the parallel light passes through the cell 28, and another part is reflected toward the cell 28 by the reflection mirror 52. A stop 30, a shutter 32, a lens 34, and a light receiving element 36 are arranged on the side of the cell 28 opposite to the reflection mirror 52, and the transmitted light reflected by the reflection mirror 52 and transmitted through the cell 28 irradiates the cell 28 directly. The scattered light of the liquid to be measured due to the parallel light is selectively guided to the light receiving element 36, and the arithmetic processing unit 60 determines the turbidity.

Next, the turbidity measuring device 10b of the third embodiment
Will be described with reference to FIG. The same reference numerals are used for the same components as those in the first embodiment, and the description will be made focusing on the differences from the first embodiment.

As shown in FIG. 5, the light from the light source lamp 20 is collimated by a lens 24. All of the parallel light is guided to the half mirror 54, a part of the parallel light passes through the half mirror and is irradiated to the cell 28, and another part is the half mirror 54.
Is to be reflected. An aperture 30, a shutter 32, a lens 34, and a light receiving element 36 are arranged on the reflection side of the half mirror 54 along the half mirror 54 and the cell 28, and the direct light reflected by the half mirror and the half mirror 54 The scattered light of the liquid to be measured by the parallel light that has passed through the cell 28 and irradiates the cell 28 is selectively guided to the light receiving element 36, and the arithmetic processing unit 60 determines the turbidity.

As described above, the turbidity measuring device of each of the above embodiments measures transmitted light and scattered light separately, so that the measurement range of the light receiving element 36 can be effectively used in each measurement. It is possible.

The present invention is not limited to the above embodiment, but can be implemented in various other modes.

For example, the diaphragm 30 and the shutter 32 may be formed as one member instead of being formed as separate members. Also, in FIG.
The shutter 32 can be provided between the prism 50 and the cell 28.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional turbidity measuring device.

FIG. 2 is a configuration diagram of a turbidity measuring device according to the first embodiment of the present invention.

FIG. 3 is a plan view of the filter of FIG. 2;

FIG. 4 is a configuration diagram of a turbidity measuring device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a turbidity measuring device according to a third embodiment of the present invention.

[Description of Signs] 20 light source lamp (light source) 40 filter unit (wavelength selecting means) 50 prism (light beam separating means) 52 reflecting mirror (light beam separating means) 54 half mirror (light beam separating means)

Claims (5)

[Claims] 1. A light beam (80) from one light source (20).
Is irradiated on the liquid to be measured in the cell (28), and the light is received by one photodetector (36) to detect the intensity of light from the cell (28). In the turbidity measuring device for measuring a degree, a light beam (80) from the one light source (20) is converted into a first light beam (80a) traveling in a first direction and a first light beam (80a) different from the first direction. 2 traveling in the second direction (80
b) light beam separating means (50, 52, 54)
A first optical path through which at least a part (82) of the first light beam (80a) is guided to the photodetector (36); and a second light beam (80b) in the cell (28). A second optical path for irradiating the liquid to be measured and a part (84) of scattered light from the liquid to be measured thereby being guided to the photodetector (36); and a second optical path for the first and second optical paths. A turbidity measuring device, comprising: a light beam selecting means (32) for selectively blocking either one of them. 2. The light beam separating means (50, 52, 54).
Is a prism (50) arranged in a part of an optical path of a light beam from the one light source (20),
The turbidity measuring device according to claim 1. 3. The light beam separating means (50, 52, 54).
The turbidity measuring device according to claim 1, wherein a reflection mirror (52) is disposed in a part of an optical path of a light beam from the one light source. 4. The light beam separating means (50, 52, 54).
Is a transflective member (54) arranged in an optical path of a light beam from said one light source.
The turbidity measuring device according to the above. 5. The light source (20) from the cell (28).
The turbidity measuring device according to claim 1, further comprising a wavelength selecting means (40) for transmitting a specific wavelength component of the light from the light source (20).