JP2000074831A - Turbidemeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute continuous turbidity measurement even by a compact and low-cost turbidimeter. SOLUTION: In this turbidimeter, light is radiated to measurement water in a cylindrical tube 1 through the cylindrical tube 1, and scattered light of the light is received by a light-receiving element 3, to thereby measure turbidity. A shielding board 4 equipped with a long slit in the axial direction of the cylindrical tube 1 is arranged between the cylindrical tube 1 and a light source 2. A shielding board 5 equipped with a long slit in the axial direction of the cylindrical tube 1 is arranged between the cylindrical tube 1 and the light- receiving element 3. The positions on the inner wall surface of the cylindrical tube 1 corresponding to the slits are made transparent, and the other parts on the inner wall surface of the cylindrical tube 1 is made opaque. Turbidity detection based on the scattered light can be executed without receiving the influence by reflected light or disturbing light from the inner wall surface of the cylindrical tube 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbidity meter for measuring turbidity (turbidity) of water such as water and sewage or bath water.

[0002]

2. Description of the Related Art The turbidity of water is generally measured by irradiating light on the measured water and measuring the transmitted light and scattered light. In this case, the measured water is placed in a dedicated measuring container. Perform the measurement. If the container here is not clean, dirt on the container will affect the measured turbidity of the water. For this purpose, Japanese Patent Application Laid-Open No. Hei 7-209186 discloses a method in which turbidity is measured from the surface scattered light of measurement water so as not to be affected by the measurement container.

[0003]

However, even in the technique disclosed in the above-mentioned publication, the measurement error increases if the surface of the measurement water is not stable, and the bubbles generated in the measurement water also have a turbidity. Continuous measurement is difficult unless a defoaming device is installed to affect the measured value.Therefore, if it is desired to continuously measure low turbidity measurement water, water surface stabilization means and defoaming It is quite large and expensive, including the means.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a turbidimeter capable of performing continuous turbidity measurement while being compact and inexpensive.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a turbidity meter for irradiating a measuring water in a cylindrical tube with light through the cylindrical tube and receiving scattered light of the light by a light receiving element to measure turbidity. In the above, a shielding plate provided with a slit elongated in the axial direction of the cylindrical tube between the cylindrical tube and the light source, and a shielding plate provided with a slit elongated in the axial direction of the cylindrical tube between the cylindrical tube and the light receiving element Is arranged so that the position corresponding to each slit on the inner wall surface of the cylindrical tube is transparent, and the other portion on the inner wall surface of the cylindrical tube is non-light-transmitting.

[0006] Turbidity detection based on scattered light can be performed without being affected by reflected light or disturbance light from the inner wall surface of the cylindrical tube. In this case, the cylindrical pipe is most preferably a cylindrical pipe.

[0007] The slit width of the shielding plate between the cylindrical tube and the light source is made smaller than the width of the corresponding transparent portion on the inner wall surface of the cylindrical tube, and the slit width of the shielding plate between the cylindrical tube and the light receiving element is reduced. If the width is smaller than the width of the corresponding transparent portion on the inner wall surface of the cylindrical tube, the influence of disturbance light and the like can be further blocked, and the influence of the displacement between the slit, the transparent portion, and the light source can be suppressed.

When a light receiving element for receiving transmitted light for correcting turbidity detection by scattered light is provided and a shielding plate provided with a slit is provided between the light receiving element and the cylindrical tube, the cylindrical tube The turbidity measurement excluding the influence of dirt can be performed.

The non-light-transmitting portion can be easily obtained if the non-light-transmitting portion of the cylindrical tube is formed by coating the transparent portion with masking applied thereto.

It is preferable that the light-transmitting portion of the cylindrical tube is provided with a coating to which dirt does not easily adhere.

It is also preferable that the cylindrical tube is provided with a coating layer to which dirt is hardly attached on the entire innermost peripheral surface.

The turbidity can be measured without being affected by bubbles by setting the baseline level of the output of the light receiving element as the detected turbidity.

[0013] Further, the measurement water introduced into the cylindrical tube is electrolytically sterilized, so that the adhesion of dirt to the inner wall of the cylindrical tube can be suppressed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment. FIG. 1 shows a horizontal cross section of a detection unit of a turbidimeter, in which a light source 2 is disposed outside a fixing member 7 made of a non-translucent material and containing a cylindrical tube 1 formed of a transparent material. In addition, a shielding plate 4 having a slit having a predetermined length that is long in the axial direction of the cylindrical tube 1 is disposed between the cylindrical tube 1 and the light source 2 and near the cylindrical tube 1. The fixture 7 is also provided with a slightly larger slit at a position facing the slit of the shielding plate 4 so that the irradiation light 9 from the light source 2 passes through the axis of the cylindrical tube 1.

On the other hand, the light receiving element 3 is arranged on the outside of the cylindrical tube 1 at a fixed angle (about 30 to 150 °) with respect to the irradiation light 9 from the light source 2 with respect to the axis of the cylindrical tube 1. In the vicinity of the cylindrical tube 1 between the cylindrical tube 1 and the light receiving element 3, a shielding plate 5 having a slit of a fixed length in the axial direction of the cylindrical tube 1 is arranged via a fixing device 7, A slightly larger slit is also provided at a position facing the slit of the closing plate 5 so that the light receiving element 3 is irradiated with the scattered light 10 of the irradiation light 9 from the light source 2. Further, a lens 11 is arranged between the light receiving element 3 and the shielding plate 5 to efficiently collect the scattered light on the light receiving element 3.

A non-light-transmitting film 6 is coated on the inner wall surface of the cylindrical tube 1 at a position corresponding to each of the slits except for a portion slightly larger than the slit. Further, an inorganic coating material 8 that is hardly contaminated is applied to the entire inner wall surface of the cylindrical tube 1 including the non-light-transmitting coating 6. Here, the cylindrical tube 1
This is realized by pre-masking the inner wall of the transparent portion with a masking tape or the like, coating the non-light-transmitting film 6, removing the masking tape, and coating the inorganic coating material 8 which is hardly stained again. . Here, titanium oxide may be used as the inorganic coating material 8 to decompose the dirt by a photocatalytic phenomenon so that the dirt is not stained. Then, a transparent inorganic coating material that is hardly adhered to the transparent portion may be applied.

FIG. 2 is a block diagram of the turbidity detecting circuit.

Next, the operation will be described. After water is supplied to the inside of the cylindrical tube 1 by a pump (not shown), the light emitting circuit 13 emits light (LE
The light source 2 composed of D) is pulse-driven, and the irradiation light 9 irradiates the measuring water from the transparent portion of the cylindrical tube 1 through the shielding plate 4 and the slit of the fixture 7. At this time, when the irradiating light irradiates the pollutant which is the cause of the turbidity in the measurement water, the scattered light 10 proportional to the turbidity is transmitted from the other transparent portion of the cylindrical tube 1 to the fixture 7.
The light is condensed on the light receiving element 3 including the photodiode via the slit of the shielding plate 5 and the lens 11.

The light receiving element 3 generates an electric signal corresponding to the amount of the scattered light 10. After the electric signal is amplified by the light receiving and amplifying circuit 14, the noise is removed by the band-pass filter 15, and the signal is input to the sample and hold 17 by the detection circuit 16 in synchronization with the signal of the oscillation circuit 12, and the level shift 18 , A voltage output corresponding to the scattered light 10 is obtained by the DC amplification circuit 19.

The voltage output obtained here is as shown in FIG. In this voltage output, the signal in the pulse area that is frequently generated is noise caused by bubbles generated in the measured water by sending water with the pump. Therefore, the signal in the pulse range disappears when the water supply is stopped. The voltage output corresponding to the turbidity is a baseline portion from which this noise has been removed, and an output proportional to the turbidity can be obtained by removing this noise by the baseline detection circuit 20. The removal of the noise by the base line detection circuit 20 is performed by digital processing after being taken into a low-pass filter or a microcomputer. By doing this,
An output proportional to the turbidity as shown in FIG. 4 is obtained.

Before sending the measuring water into the cylindrical tube 1,
The measurement water may be electrolytically sterilized, and the sterilization can prevent the inner wall of the cylindrical tube 1 from being stained.

FIG. 5 shows another example of the turbidity detecting section. Here, a light receiving element 21 is arranged at a position facing the light source 2 on the outer side of the cylindrical tube 1, and the cylindrical tube 1 and the light receiving element 3 are connected to each other. A shielding plate 22 having a slit of a fixed length in the axial direction of the cylindrical tube 1 is arranged in the vicinity of the cylindrical tube 1 between the fixing members 7 so as to face the slit of the shielding plate 22 of the fixing device 7. A slightly larger slit is also provided at the position to irradiate light (transmitted light) 9 from the light source 2.
Is irradiated on the light receiving element 21. Further, a lens 23 is disposed between the light receiving element 21 and the shielding plate 22 in order to efficiently collect the irradiation light (transmitted light) 9 on the light receiving element 21.

The output of the light receiving element 21 is also processed using the same circuit configuration as that for the output of the light receiving element 3 to detect the irradiation light (transmitted light) 9 and to obtain the scattered light based on the detected value. By correcting the turbidity output of 10, the turbidity can be accurately detected even when the inner wall surface of the cylindrical tube 1 becomes dirty.

[0024]

As described above, according to the present invention, a shielding plate having a long slit in the axial direction of a cylindrical tube is arranged between the cylindrical tube and the light source, and the cylindrical plate is interposed between the cylindrical tube and the light receiving element. In order to arrange a shielding plate provided with a long slit in the axial direction of the tube, to make the position corresponding to each slit on the inner wall surface of the cylindrical tube transparent, and to make other parts on the inner wall surface of the cylindrical tube non-translucent In addition, turbidity detection based on scattered light can be performed without being affected by light reflected from the inner wall surface of the cylindrical tube or disturbance light. In this case, the cylindrical tube is the most preferable because it can reduce the influence of the reflected light on the inner surface of the cylindrical tube.

The slit width of the shielding plate between the cylindrical tube and the light source is made smaller than the width of the corresponding transparent portion on the inner wall surface of the cylindrical tube, and the slit width of the shielding plate between the cylindrical tube and the light receiving element is reduced. If the width is smaller than the width of the corresponding transparent portion on the inner wall surface of the cylindrical tube, the influence of disturbance light and the like can be further blocked, and the influence of the displacement between the slit, the transparent portion, and the light source can be suppressed.

When a light receiving element for receiving transmitted light for correcting turbidity detection by scattered light is provided and a shielding plate provided with a slit is provided between the light receiving element and the cylindrical tube, the cylindrical tube The turbidity measurement can be performed accurately without the influence of dirt.

If the non-light-transmitting portion of the cylindrical tube is formed by coating the transparent portion with masking applied thereto, the non-light-transmitting portion can be easily obtained.

The effect of reflected light due to dirt can be reduced by providing the light transmitting portion of the cylindrical tube with a coating to which dirt does not easily adhere.

Further, if the cylindrical tube is provided with a coating layer to which dirt is hardly attached on the entire innermost peripheral surface thereof, it is possible to reduce the attenuation of irradiation light and scattered light due to dirt. Turbidity detection can be performed.

Furthermore, by setting the baseline level of the output of the light receiving element to the detected turbidity, turbidity measurement can be performed without being affected by air bubbles without providing a defoaming device.

Further, by setting the measurement water introduced into the cylindrical tube to be electrolytically sterilized, the adhesion of dirt to the inner wall of the cylindrical tube can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic horizontal sectional view of an example of an embodiment of the present invention.

FIG. 2 is a block circuit diagram of the same.

FIG. 3 is an explanatory diagram of an amplifier circuit output according to the first embodiment;

FIG. 4 is an explanatory diagram of an output of a baseline detection circuit according to the first embodiment;

FIG. 5 is a schematic horizontal sectional view of another example.

[Explanation of symbols]

 Reference Signs List 1 cylindrical tube 2 light source 3 light receiving element 4,5 shielding plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G057 AA01 AA02 AA10 AB01 AC01 BA05 BD10 CB10 DA06 DB08 DC07 JA20 2G059 AA05 BB05 DD01 EE01 EE02 GG02 GG08 HH02 KK01 LL02 LL04 LL10 MM11 MM20 NN07

Claims (9)

[Claims] 1. A turbidity meter that irradiates light to measurement water in a cylindrical tube through a cylindrical tube and receives scattered light of the light by a light receiving element to measure turbidity. Along with disposing a shielding plate with a long slit in the axial direction of the cylindrical tube, and disposing a shielding plate with a long slit in the axial direction of the cylindrical tube between the cylindrical tube and the light receiving element, the inner wall surface of the cylindrical tube A turbidimeter, wherein a position corresponding to each of the slits is made transparent, and other portions on the inner wall surface of the cylindrical tube are made non-translucent. 2. The turbidity meter according to claim 1, wherein the cylindrical tube is a cylindrical tube. 3. The slit width of the shielding plate between the cylindrical tube and the light source is smaller than the width of the corresponding transparent portion on the inner wall surface of the cylindrical tube, and the slit of the shielding plate between the cylindrical tube and the light receiving element. The turbidimeter according to claim 1 or 2, wherein the width is smaller than the width of the corresponding transparent portion on the inner wall surface of the cylindrical tube. 4. A light receiving element for receiving transmitted light for correcting turbidity detection by scattered light is provided, and a shielding plate having a slit is arranged between the light receiving element and a cylindrical tube. The turbidity meter according to any one of claims 1 to 3, characterized in that: 5. The turbidity meter according to claim 1, wherein the non-light-transmitting portion of the cylindrical tube is formed by coating the transparent portion with masking applied. 6. The turbidimeter according to claim 1, wherein the light-transmitting portion of the cylindrical tube is coated with a coating to which dirt does not easily adhere. 7. The turbidity meter according to claim 1, wherein a coating layer to which dirt hardly adheres is provided on the entire innermost peripheral surface of the cylindrical tube. 8. The turbidity meter according to claim 1, wherein the baseline level of the output of the light receiving element is used as the detection turbidity. 9. The turbidity meter according to claim 1, wherein the measuring water introduced into the cylindrical tube has been subjected to electrolytic sterilization.