Surface scattering type turbidimeter and turbidity measurement method

Abstract

The invention provides a surface scattering type turbidimeter and a turbidity measuring method, which change the position relation between the light irradiation position of the liquid surface and a light receiving element to improve the accuracy of turbidity measurement. The measurement tank stores a liquid to be measured. The light source emits light to the liquid surface of the liquid to be measured stored in the measuring tank. The light receiving element receives scattered light generated in the measurement tank by light from the light source. The changing mechanism changes the irradiation position of the light from the light source on the liquid surface and the relative position of the component of the light receiving element with respect to the traveling direction of the light, said component being horizontal to the liquid surface. The turbidity value calculation unit calculates the turbidity value of the liquid to be measured on the basis of the scattered light received by the light receiving element.

Description

Technical Field

[0001] The present invention relates to a surface scattering turbidimeter and a turbidity measuring method. Background Art

[0002] Turbidimeters are known for optically measuring the turbidity of liquids such as those used in water treatment plants and industrial water. Turbidity is an indicator of the degree of cloudiness in a liquid. Turbidimeters use various measurement methods, including transmitted light, scattered light, transmitted scattered light, surface scattered light, and integrating sphere methods.

[0003] Among the aforementioned measurement methods, the surface scattered light method utilizes the fact that the intensity of scattered light is proportional to the concentration of turbid substances in the liquid. In this method, light irradiated from a light source is reflected by turbid substances in the liquid to be measured in the measurement chamber, generating scattered light. This scattered light is received by a light-receiving element and converted into an electrical signal corresponding to the light intensity. The turbidity corresponding to this electrical signal is then calculated.

[0004] As surface scattered light turbidimeters, there are proposed turbidimeters that use two types of scattered light with different wavelengths to perform comparative correction and calculation of turbidity. In addition, there are proposed turbidimeters that use forward scattered light to measure turbidity.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-144868

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2006-300858 Summary of the Invention

[0007] However, in current surface scattering turbidimeters that measure turbidity using surface scattered light, the positional relationship between the light source, measuring cell, and light receiving element is fixed. Turbidity is determined by irradiating light from the light source to the same position of the liquid being measured, which is stored in the measuring cell. As described above, the fixed positional relationship between the light source, measuring cell, and light receiving element makes it difficult to adjust the optical path length in the liquid, making it difficult to accurately measure turbidity in accordance with the state of the liquid being measured.

[0008] In contrast, even turbidimeters that use two types of light with different wavelengths or turbidimeters that measure turbidity using forward scattered light have fixed positional relationships among the light source, measuring chamber, and light receiving element, making it difficult to measure turbidity with high accuracy according to the state of the liquid being measured.

[0009] One aspect of the present invention improves the accuracy of turbidity measurements.

[0010] A turbidity measuring device according to one aspect includes the following components. A measuring tank stores a liquid to be measured. A light source irradiates light onto the liquid surface of the liquid to be measured stored in the measuring tank. A light receiving element receives scattered light generated in the measuring tank by the light from the light source. A changing mechanism changes the relative position of the light from the light source irradiating the liquid surface and the component of the light receiving element at the liquid surface level relative to the direction of travel of the light. A turbidity value calculation unit calculates the turbidity value of the liquid to be measured based on the scattered light received by the light receiving element.

[0011] Effects of the Invention

[0012] According to the present invention, the accuracy of turbidity measurement can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a structural diagram of the turbidity meter according to the first embodiment.

[0014] Figure 2 This diagram shows scattered light when the liquid surface is brought close to the light receiving element.

[0015] Figure 3 This diagram shows scattered light when the liquid surface is moved away from the light receiving element.

[0016] Figure 4 This is a graph showing the relationship between the height of the measuring groove and linearity.

[0017] Figure 5 This is a diagram showing the correspondence between a plurality of turbidity thresholds and positions in the Z-axis direction.

[0018] Figure 6 This is a structural diagram of a turbidity meter according to the second embodiment.

[0019] Figure 7 This is a flowchart of a turbidity value calculation process performed by the turbidimeter according to the second embodiment.

[0020] Figure 8 This is a hardware configuration diagram of the control terminal device. DETAILED DESCRIPTION

[0021] Below, embodiments of a surface scattering turbidimeter and a turbidity measurement method are described with reference to the accompanying drawings. Identical elements are denoted by the same reference numerals, and duplicate descriptions are omitted as appropriate. Furthermore, the various embodiments may be combined as appropriate within the scope of non-contradiction.

[0022] (Implementation 1)

[0023] (Overall structure)

[0024] Figure 11 is a block diagram of a turbidimeter according to Embodiment 1. The turbidimeter 1 includes a measuring cell 10 , an illumination control circuit 21 , a light source 22 , a light receiving circuit 30 , lenses 41 and 42 , and a control terminal 50 .

[0025] The light source 22 of this embodiment emits light in a specific direction toward the liquid surface of the liquid to be measured stored in the measuring tank 10. The direction of the light emitted from the light source 22 of this embodiment is fixed. The light emitted from the light source 22 is focused by the lens 41 and travels toward the liquid surface of the liquid to be measured stored in the measuring tank 10.

[0026] like Figure 1 As shown in the path R1, light emitted from the light source 22 and focused by the lens 41 is directed toward the liquid surface of the measuring tank 10 from a direction inclined at a constant angle relative to the liquid surface maintained constant. The light source 22 is, for example, a tungsten filament lamp.

[0027] The illuminance of the light source 22 varies due to factors such as degradation of the light source 22 and fluctuations in the power supply voltage. Therefore, the illuminance control circuit 21 controls the illuminance of the light source 22 to eliminate the effects of degradation of the light source 22 and fluctuations in the power supply voltage. Thus, the illuminance control circuit 21 maintains a constant illuminance of the light emitted from the light source 22.

[0028] The light receiving circuit 30 converts scattered light from the liquid to be measured into a current and outputs a current signal proportional to the scattered light to the control terminal device 50. The light receiving circuit 30 includes a light receiving element 31, an amplifier 32, and a current converter 33.

[0029] The light receiving element 31 is, for example, a silicon photodiode. The light receiving element 31 receives scattered light from the liquid being measured, which is focused by the lens 42. The light receiving element 31 detects the received scattered light and outputs an optical signal based on the detected light to the amplifier 32.

[0030] The amplifier 32 receives an input of the optical signal from the light receiving element 31 and amplifies the intensity of the optical signal. The amplifier 32 then outputs the intensity-amplified scattered light optical signal to the control terminal device 50 and the current conversion unit 33.

[0031] The current converter 33 receives the intensity-amplified scattered light signal from the amplifier 32. The current converter 33 converts the light signal into a current signal. The current converter 33 then outputs the current signal, obtained by converting the scattered light signal, to the control terminal 50 as a current signal indicating the intensity of the scattered light.

[0032] The measuring tank 10 is equipped with a darkroom 11 and a lifting mechanism 12. The measuring tank 10 continuously allows the measured liquid to flow in at a constant pressure. Furthermore, the measuring tank 10 allows the flowing measured liquid to overflow, maintaining a constant liquid level. The measuring tank 10 then discharges the overflowed measured liquid to the outside of the measuring tank 10.

[0033] Here, a coordinate system for the measuring tank 10 is set. The axis representing the component of the direction of travel of the light emitted from the light source 22 that is horizontal on the liquid surface is set as the X-axis. Here, the direction of the component of the direction of travel of the light emitted from the light source 22 that is horizontal on the liquid surface is set as the positive direction of the X-axis. In addition, the normal to the liquid surface is set as the Z-axis. Here, the direction in which the light is reflected from the liquid surface, that is, the direction from the liquid surface toward the light receiving element 31 is set as the positive direction of the Z-axis. Moreover, the direction orthogonal to both the X-axis and the Z-axis is set as the Y-axis. That is, the Y-axis is the axis relative to the normal direction of the plane formed by the path R1 of the light emitted from the light source 22 and the X-axis. Here, the direction toward Figure 1 The direction toward the inner side of the paper is set as the positive direction of the Y axis.

[0034] Part of the light irradiated from the light source 22 is reflected at a position P1 that is an intersection of the light and the liquid surface as shown by a path R2 , and part of the light penetrates into the liquid as shown by a path R3 . Figure 1 The reflected position of the light on the liquid surface, that is, the position P1, coincides with the center of the light receiving element 31 in the Z direction, that is, the XY coordinates of the position P1 and the center of the light receiving element 31 coincide with each other. Figure 1 When the intersection of the light irradiated from the light source 22 and the liquid surface, i.e., the position P1, coincides with the center of the light receiving element 31 in the Z direction, the Z coordinate of the measuring tank 10 is set to 0. Figure 1 The state is called the "baseline state".

[0035] The reflected light reflected from the liquid surface travels to the darkroom 11 and is absorbed and disappears. Furthermore, the transmitted light that penetrates the liquid is also absorbed and disappears by the liquid being measured. This suppresses the influence of the reflected and transmitted light on the turbidity measurement.

[0036] On the other hand, light penetrating the liquid from the liquid surface generates scattered light in the positive direction from the liquid surface toward the Z axis due to the turbidity (turbidity component) of the liquid surface and the liquid being measured. As shown by path R4, the scattered light is converged at a position opposite to the liquid surface, that is, by lens 42 arranged in the positive direction of the Z axis relative to the liquid surface, and is irradiated onto light receiving element 31.

[0037] The more scattered light generating locations are included in the area of ​​the liquid surface that overlaps the light-receiving element 31 in the Z-axis direction, the more light enters the light-receiving element 31. In other words, when considering the overall intensity of scattered light, the size of the area of ​​the liquid surface that overlaps the light-receiving element 31 in the Z-axis direction is more important. Therefore, for simplicity of explanation, the illustration shows scattered light traveling forward in the Z-direction from the location where scattered light is generated. For example, in the baseline state, scattered light generated at position P1 of the liquid surface is directed toward the center of the light-receiving element 31. Furthermore, position P2, which generates scattered light toward the forward end of the light-receiving element 31 in the X-direction, is the deepest location where scattered light is generated in the baseline state. In the following description, the area of ​​the liquid surface that overlaps the light-receiving element 31 in the Z-axis direction is referred to as the "range seen from the light-receiving element 31." In reality, scattered light travels in various directions, and scattered light directed toward the lens 42 converges and illuminates the light-receiving element 31.

[0038] The lifting mechanism 12 is a mechanism that moves the measuring tank 10 in the Z-axis direction. It can move the measuring tank 10 in both the positive and negative Z-axis directions. In this embodiment, the lifting mechanism 12 manually rotates a gear to change the Z-axis position of the measuring tank 10. However, the lifting mechanism 12 can also be a mechanism that uses a drive source such as a motor to move the measuring tank 10 in the Z-axis direction.

[0039] When the measuring tank 10 is moved in the positive direction of the Z-axis by the lifting mechanism 12, the liquid level in the measuring tank 10 approaches the light receiving element 31. On the other hand, when the measuring tank 10 is moved in the negative direction of the Z-axis by the lifting mechanism 12, the liquid level in the measuring tank 10 moves away from the light receiving element 31. The lifting mechanism 12 can move the measuring tank 10 in the Z-axis direction, for example, at intervals of 0.5 mm.

[0040] Figure 2 This diagram shows scattered light when the liquid surface is brought close to the light receiving element. Figure 2 The state in which the measuring tank 10 is moved from the reference state to the positive direction of the Z axis by the lifting mechanism 12 is shown. Figure 2 In the embodiment, the liquid surface approaches the light receiving element 31 by a distance L1 from the reference state.

[0041] In this case, the irradiation position of the light irradiated from the light source 22 on the liquid surface, that is, the intersection of the irradiated light and the liquid surface, is the position P11 moved from the position P1 to the negative direction of the X-axis direction. Figure 2As shown, in the reference state, scattered light generated at a location deeper than position P2, the deepest point of scattered light generation, enters the light receiving element 31. Specifically, position P12 coincides with the center of the light receiving element 31 in the Z-axis direction, and the deepest point of scattered light generation entering the light receiving element 31 is position P13. In other words, scattered light generated by light having a longer optical path length in the liquid compared to the reference state enters the light receiving element 31. Furthermore, in this case, the number of scattered light generation locations within the range visible from the light receiving element 31 increases compared to the reference state. Therefore, scattered light from more locations in the liquid enters the light receiving element 31, increasing the measured light intensity compared to the reference state.

[0042] Figure 3 This diagram shows scattered light when the liquid surface is moved away from the light receiving element. Figure 3 The state in which the measuring tank 10 is moved from the reference state to the negative direction of the Z axis by the lifting mechanism 12 is shown. Figure 3 In the embodiment, the liquid surface is separated from the light receiving element 31 by a distance L2 from the reference state.

[0043] In this case, the intersection of the light emitted from light source 22 and the liquid surface is position P21, which is shifted in the positive direction of the X-axis from position P1. In this case, position P22 coincides with the center of light receiving element 31 in the Z direction, and the deepest scattered light within the range seen by light receiving element 31 is generated at position P23. In other words, the maximum optical path length of the scattered light entering light receiving element 31 in the liquid is shorter than in the reference state. Furthermore, in this case, the number of scattered light generation locations within the range seen by light receiving element 31 is reduced compared to the reference state, resulting in fewer scattered light entering light receiving element 31, and a lower measured light intensity compared to the reference state.

[0044] The lifting mechanism 12 is equivalent to an example of a "changing mechanism". The lifting mechanism 12 changes the relative position of the irradiation position of the light from the light source 22 on the liquid surface and the light receiving element 31, and changes the relative position of the component at the liquid surface level relative to the direction of travel of the light (that is, relative to the X-axis direction). According to another viewpoint, the lifting mechanism 12 changes the position in the X-axis direction of the intersection (irradiation position) of the light from the light source 22 and the liquid surface. More specifically, the lifting mechanism 12 is a mechanism that changes the above relative position by changing the distance between the measuring tank 10 and the light receiving element 31, and in particular, changes the distance between the measuring tank 10 and the light receiving element 31 by moving the measuring tank 10.

[0045] The control terminal device 50 calculates and displays the turbidity value based on the current signal indicating the intensity of the scattered light. The control terminal device 50 includes a turbidity value calculation unit 51 and a display unit 52. The control terminal device 50 is an example of a "turbidity value calculation device."

[0046] The turbidity value calculator 51 receives an input of a current signal representing the intensity of the scattered light from the current converter 33. The turbidity value calculator 51 has a mathematical formula (1) in which a constant K corresponding to the liquid to be measured is set. The turbidity value calculator 51 calculates the turbidity value of the liquid to be measured using the current signal representing the intensity of the acquired scattered light and the mathematical formula (1). The turbidity value calculator 51 then outputs the calculated turbidity value of the liquid to be measured to the display 52. ​​In this manner, the turbidity value calculator 51 calculates the turbidity value of the liquid to be measured based on the scattered light received by the light receiving element 31.

[0047] The display unit 52 receives an input of the turbidity value of the liquid to be measured from the turbidity value calculation unit 51. The display unit 52 displays the acquired turbidity value of the liquid to be measured on a display or the like to provide information to the user.

[0048] (Linear relationship between the intersection of light irradiated from the light source and the liquid surface)

[0049] Here, the intensity of scattered light in the measuring cell 10 has the relationship shown in the following mathematical formula (1): Here, K is a constant, S is turbidity, Q is the light intensity of the light source, and L is the intensity of scattered light.

[0050] L=K×Q×S……(1)

[0051] Thus, the intensity L of scattered light depends on the light source light quantity Q and the turbidity S. Therefore, if the light source light quantity Q is constant, then theoretically, the turbidity S is proportional to the intensity L of scattered light. The degree to which the relationship between the turbidity S and the intensity L of scattered light approaches a linear relationship (a proportional relationship) is called linearity. That is, if the relationship between the turbidity S and the intensity L of scattered light approaches a linear relationship (a proportional relationship), the linearity improves, and if it deviates from linearity, the linearity decreases. The turbidimeter 1 measures the intensity L of scattered light and calculates the turbidity S using mathematical formula (1). Therefore, the smaller the change in linearity, the higher the accuracy of the turbidity S estimated using mathematical formula (1).

[0052] Here, in the surface scattering turbidimeter 1, the linearity trend changes depending on a slight misalignment of the intersection point between the light emitted from the light source 22 and the liquid surface. Specifically, when the intersection point between the light emitted from the light source 22 and the liquid surface is misaligned in the X-axis direction, the linearity change significantly. In contrast, when the intersection point between the light emitted from the light source 22 and the liquid surface is misaligned in the Y-axis direction, the amount of detected scattered light decreases, the linearity change is minimal, and the impact on turbidity calculations falls within an acceptable range. This is because when the intersection point is misaligned in the X-axis direction, the path length of the scattered light in the water at the location of generation significantly changes, affecting the linearity.

[0053] Furthermore, when measuring the turbidity of a measured liquid using scattered light, absorption of scattered light by turbid substances occurs. Therefore, when the measured liquid has high turbidity, absorption of scattered light by turbid substances is greater. Here, high turbidity refers to, for example, 250 NTU (Nephelometric Turbidity Unit) or greater. In contrast, when the measured liquid has low turbidity, absorption of scattered light by turbid substances is less. Here, low turbidity refers to, for example, 0-250 NTU.

[0054] Therefore, when the measured liquid has high turbidity, the optical path length of the light generating scattered light in the liquid is preferably short to suppress the influence of scattered light absorption by turbid substances. Conversely, when the measured liquid has low turbidity, the influence of scattered light absorption by turbid substances is less, so the optical path length of the light generating scattered light in the liquid can be extended. Furthermore, a high measurement light intensity is preferred in both high and low turbidity situations.

[0055] Here, the position P1 of the intersection of the light irradiated from the light source 22 in the reference state and the liquid surface is set as the reference, and the position of the intersection of the light irradiated from the light source 22 and the liquid surface is set as Figure 2 When the light is displaced in the negative direction in the X-axis direction, the optical path length in the liquid in the range viewed from the light receiving element 31 is longer than that in the reference state.

[0056] When the measured liquid has a high concentration, if the optical path length in the liquid visible from the light receiving element 31 increases, the influence of the absorption of scattered light by turbid substances increases, and the signal amount decreases. Therefore, when the measured liquid has a high concentration, the linearity decreases.

[0057] On the contrary, when the concentration of the measured liquid is low, if the intersection point is Figure 2 By shifting in the negative direction of the X-axis, the amount of light to be measured increases, thereby improving linearity when the concentration of the measured liquid is low.

[0058] On the other hand, the position P1 of the intersection of the light irradiated from the light source 22 in the reference state and the liquid surface is set as the reference, and the position of the intersection of the light irradiated from the light source 22 and the liquid surface is as follows: Figure 3 When the light is displaced in the positive direction of the X-axis direction, the optical path length in the liquid in the range viewed from the light receiving element 31 is shortened.

[0059] When the measured liquid has a high concentration, the optical path length in the liquid visible from the light receiving element 31 is shortened. This reduces the influence of scattered light absorption by turbid substances and allows surface scattering to dominate. Therefore, linearity improves when the measured liquid has a high concentration.

[0060] On the contrary, when the concentration of the measured liquid is low, if the intersection point is Figure 3 If the measurement light quantity is deviated in the positive direction of the X-axis, the linearity is reduced when the concentration of the measured liquid is low.

[0061] Figure 4 : is a graph showing the relationship between the height of the measuring tank and the linearity. If the relationship between the height of the measuring tank 10 and the linearity is summarized, it can be seen that Figure 4 The results are shown in Table 101. Specifically, as shown in Table 101, increasing the height of the measuring tank 10 shifts the intersection of the optical axis and the liquid surface toward the negative direction of the X-axis. This reduces linearity when the measured liquid has high turbidity, while improving linearity when the measured liquid has low turbidity. Conversely, increasing the height of the measuring tank 10 shifts the intersection of the optical axis and the liquid surface toward the positive direction of the X-axis. This improves linearity when the measured liquid has high turbidity, while reducing linearity when the measured liquid has low turbidity.

[0062] As described above, when the turbidity of the liquid to be measured is greater than or equal to a predetermined high turbidity threshold, the Z coordinate of the measuring cell 10 is preferably shifted more negatively than in the reference state. Conversely, when the turbidity of the liquid to be measured is less than a predetermined low turbidity threshold, which is less than or equal to the high turbidity threshold, the Z coordinate of the measuring cell 10 is preferably shifted more positively than in the reference state.

[0063] (Turbidity measurement based on height adjustment of the measuring tank)

[0064] Here, the turbidity measurement based on the height adjustment of the measuring tank 10 is described. The measuring tank 10 is set to Figure 1 Therefore, the user causes the turbidimeter 1 to calculate the turbidity value of the liquid to be measured in the reference state and causes the display unit 52 to display the turbidity value.

[0065] Next, the user checks the turbidity value of the liquid to be measured under the reference state by referring to the display unit 52. This first measured turbidity value of the liquid to be measured under the reference state is referred to as the "preliminary turbidity value." The user then determines whether the preliminary turbidity value is greater than or equal to the upper turbidity threshold and whether the preliminary turbidity value is less than the lower turbidity threshold.

[0066] If the pre-measured turbidity value is greater than or equal to the high turbidity threshold, the user uses the lifting mechanism 12 to move the measurement chamber 10 in the negative direction of the Z-axis to a predetermined high turbidity measurement position. Then, with the measurement chamber 10 moved to the high turbidity measurement position, the user causes the turbidimeter 1 to calculate the turbidity value of the measurement fluid and displays it on the display unit 52. The user then sets the provided turbidity value of the measurement fluid as the actual turbidity value of the measurement fluid.

[0067] On the other hand, if the pre-measured turbidity value is less than the low turbidity threshold, the user moves the measurement chamber 10 in the positive direction of the Z-axis to the predetermined low turbidity measurement position using the lifting mechanism 12. Then, with the measurement chamber 10 moved to the low turbidity measurement position, the user causes the turbidimeter 1 to calculate the turbidity value of the measurement fluid and displays it on the display unit 52. Furthermore, the user sets the provided turbidity value of the measurement fluid as the actual turbidity value of the measurement fluid.

[0068] Furthermore, when the estimated turbidity value is greater than or equal to the low turbidity threshold value and less than the high turbidity threshold value, the user can set the estimated turbidity value as the actual turbidity value of the liquid to be measured.

[0069] Alternatively, the low turbidity threshold and the high turbidity threshold may be the same turbidity value. In this case, the user compares the single turbidity threshold with the pre-determined turbidity value to determine the position of the measurement tank 10. In this case, the user does not need to set the pre-determined turbidity value measured at the position of the measurement tank 10 under the reference state as the actual turbidity value of the liquid to be measured.

[0070] Here, in the turbidimeter 1 according to this embodiment, the position of the intersection of the optical axis and the liquid surface in the X-axis direction is changed by changing the position of the measuring tank 10 in the Z-axis direction. However, the turbidimeter 1 can also utilize other mechanisms by changing the relative position of the liquid surface irradiation position of the light from the light source 22 and the liquid surface component of the light receiving element 31 relative to the direction of light travel between high and low turbidity.

[0071] For example, the turbidimeter 1 can change the X-axis position of the intersection of the light from the light source 22 and the liquid surface by changing the direction of the optical axis of the light source 22. In this case, the turbidimeter 1 has a changing mechanism that changes the relative position by changing the direction of the optical axis of the light from the light source 22.

[0072] Furthermore, the turbidimeter 1 can change the X-axis position of the intersection of the optical axis and the liquid surface by moving the light source 22 in at least one of the Z-axis and the X-axis directions. In this case, the turbidimeter 1 includes a changing mechanism for changing the relative position by changing the position of the light source 22.

[0073] In addition, the turbidimeter 1 can move the light receiving element 31 in the X-axis direction. In this case, the turbidimeter 1 has a changing mechanism that moves the light receiving element 31 to change the relative position and also changes the distance between the measuring tank 10 and the light receiving element 31.

[0074] As described above, the turbidimeter 1 according to this embodiment can change the position of the intersection of the optical axis of the light emitted from the light source 20 and the liquid surface. This allows for the acquisition of scattered light at an appropriate optical path length in the liquid for both high and low turbidity conditions. This improves linearity in both high and low turbidity conditions, thereby enhancing the accuracy of turbidity measurements.

[0075] (Variation)

[0076] In Example 1, the position of the measuring cell 10 is determined using one high turbidity threshold and one low turbidity threshold. However, the position can be changed stepwise according to the turbidity in both the case of a liquid to be measured having high turbidity and a liquid to be measured having low turbidity.

[0077] Figure 5 is a diagram showing the correspondence between multiple turbidity thresholds and positions in the Z-axis direction. Figure 5 Table 200 is shown. In Table 200, the turbidity value decreases as the position moves upward toward the paper. In addition, the turbidity threshold value corresponding to the reference position does not need to be set, so it is omitted from Table 200.

[0078] Figure 5 The turbidity threshold values ​​#1 to #3 in the figure are threshold values ​​on the low turbidity side. The turbidity value on the low turbidity side refers to a turbidity value less than or equal to 250 NTU, for example. Turbidity threshold values ​​#3 to #1 are set as threshold values ​​respectively so that the positive positions in the Z-axis direction of the measuring tank 10, namely Z(1) to Z(3), are associated. Z(1) to Z(3) have a spacing of several millimeters, for example, and indicate higher positions in the Z-axis direction in order. Turbidity threshold value #3 can also be set as the low turbidity threshold value in embodiment 1. In this case, when the turbidity value is less than the low turbidity threshold value, the measuring tank 10 is moved in stages according to the turbidity value.

[0079] Turbidity thresholds ##1 to ##3 are thresholds on the high turbidity side. Turbidity values ​​on the high turbidity side refer to, for example, turbidity values ​​greater than or equal to 250 NTU. Turbidity thresholds ##1 to ##3 are set as thresholds so that the negative positions in the Z-axis direction of the measuring tank 10, i.e., Z(-1) to Z(-3), are associated. Z(-1) to Z(-3) also have intervals of several millimeters, for example, and indicate lower positions in the Z-axis direction in this order. In addition, the reference position in Table 200 is Figure 1 The Z-axis position of the measuring cell 10 in the reference state is shown. Turbidity threshold ##1 may be set to the high turbidity threshold in Embodiment 1. In this case, the measuring cell 10 is moved stepwise according to the turbidity value when the turbidity value is greater than or equal to the high turbidity threshold.

[0080] The user confirms the turbidity value based on the preliminary determination measured under the reference state displayed on the display unit 52. The user then compares the preliminary turbidity value with the turbidity threshold values ​​#1 to #3 and ##1 to ##3.

[0081] In the case where the turbidity value to be determined is greater than or equal to the turbidity threshold value #2 and less than the turbidity threshold value #3, the user refers to the table 200 to confirm whether the Z coordinate of the measuring tank 10 corresponds to Z(1). Therefore, the user operates the lifting mechanism 12 and moves the measuring tank 10 from the reference position to the positive direction of the Z-axis direction, thereby setting the Z coordinate of the measuring tank 10 to Z(1). In addition, in the case where the turbidity value to be determined is greater than or equal to the turbidity threshold value #1 and less than the turbidity threshold value #2, the user refers to the table 200 to confirm whether the Z coordinate of the measuring tank 10 corresponds to Z(2). Therefore, the user operates the lifting mechanism 12 and moves the measuring tank 10 from the reference position to the positive direction of the Z-axis direction, thereby setting the Z coordinate of the measuring tank 10 to Z(2). In addition, in the case where the turbidity value to be determined is less than the turbidity threshold value #1, the user refers to the table 200 to confirm whether the Z coordinate of the measuring tank 10 corresponds to Z(3). Therefore, the user operates the lifting mechanism 12 to move the measuring tank 10 from the reference position to the positive direction of the Z-axis direction, and sets the Z coordinate of the measuring tank 10 to Z(3).

[0082] Furthermore, if the turbidity value to be determined is greater than or equal to turbidity threshold ##1 and less than turbidity threshold ##2, the user refers to table 200 to confirm whether the Z coordinate of the measuring tank 10 corresponds to Z(-1). Therefore, the user operates the lifting mechanism 12 to move the measuring tank 10 from the reference position in the negative direction of the Z axis, setting the Z coordinate of the measuring tank 10 to Z(-1). Furthermore, if the turbidity value to be determined is greater than or equal to turbidity threshold ##2 and less than turbidity threshold ##3, the user refers to table 200 to confirm whether the Z coordinate of the measuring tank 10 corresponds to Z(-2). Therefore, the user operates the lifting mechanism 12 to move the measuring tank 10 from the reference position in the negative direction of the Z axis, setting the Z coordinate of the measuring tank 10 to Z(-2). Furthermore, if the turbidity value to be determined is greater than or equal to turbidity threshold ##3, the user refers to table 200 to confirm whether the Z coordinate of the measuring tank 10 corresponds to Z(-3). Therefore, the user operates the lifting mechanism 12 to move the measuring tank 10 from the reference position to the negative direction of the Z-axis direction, and sets the Z coordinate of the measuring tank 10 to Z(-3).

[0083] After moving the measuring tank 10 in the Z-axis direction according to the pre-measured turbidity value as described above, the user measures the liquid to be measured with the turbidimeter 1 and calculates the turbidity value.

[0084] As described above, the turbidimeter 1 according to this modified example allows the Z-axis position of the measuring cell 10 to be adjusted in stages according to the turbidity value. This allows for more precise measurement of scattered light with an appropriate optical path length in the liquid, tailored to the state of the liquid being measured, further improving linearity. Consequently, the accuracy of turbidity measurements can be enhanced.

[0085] (Implementation Method 2)

[0086] Figure 6 This is a structural diagram of a turbidimeter according to Embodiment 2. The turbidimeter 1 according to this embodiment automatically adjusts the position of the measuring cell 10 in the Z-axis direction based on the measured and predicted turbidity value. Figure 6 In the Figure 1 Components with the same reference numerals have the same functions as those in Embodiment 1. In the following description, automatic adjustment of the position of the measurement tank 10 in the Z-axis direction is mainly described, and description of the operations of components identical to those in Embodiment 1 may be omitted.

[0087] Regarding the turbidimeter 1 involved in this embodiment, Figure 6 As shown, the control terminal device 50 further includes a control unit 53 .

[0088] The measuring tank 10 is set to Figure 1 The height of the reference state is obtained. Therefore, the turbidity value calculator 51 calculates the pre-determined turbidity value using the scattered light from the measurement cell 10 in the reference state. Next, the turbidity value calculator 51 uses the control unit 53 to move the measurement cell 10 in the Z-axis direction according to the pre-determined turbidity value. The turbidity value calculator 51 then receives an input of a current signal representing the intensity of the scattered light and recalculates the turbidity value. The turbidity value calculator 51 then outputs the recalculated turbidity value of the measurement liquid to the display unit 52, which displays the re-measured turbidity value of the measurement liquid on a display or the like.

[0089] Furthermore, upon receiving notification of turbidity value determination from the control unit 53 , the turbidity value calculation unit 51 outputs the pre-determined turbidity value to the display unit 52 , causing the display or the like to display the turbidity value as the turbidity value of the liquid to be measured.

[0090] Here, the pre-determined turbidity value is an example of a "first turbidity value." Furthermore, the turbidity value measured by the turbidity value calculator 51 after the measurement cuvette 10 has moved in accordance with the pre-determined turbidity value is an example of a "second turbidity value." Furthermore, the turbidity value calculator 51 calculates the first turbidity value of the liquid to be measured at a predetermined position in the measurement cuvette 10 and calculates the second turbidity value of the liquid to be measured after the measurement cuvette 10 has moved from the predetermined position.

[0091] The control unit 53 has a communication path with the lifting mechanism 12, and sends a command signal through the communication path to drive the lifting mechanism 12 to change the position of the measuring tank 10 in the Z-axis direction. Figure 5 The table 200 shown here is a correlation between the turbidity threshold value and the position of the measuring tank 10 in the Z-axis direction.

[0092] The control unit 53 acquires the estimated turbidity value from the turbidity value calculation unit 51. Next, the control unit 53 compares the estimated turbidity value with the threshold values ​​registered in the table 200, namely, turbidity threshold values ​​#1 to #3 and ##1 to ##3.

[0093] When the turbidity value to be determined is greater than or equal to turbidity threshold #2 and less than turbidity threshold #3, the control unit 53 drives the lifting mechanism 12 to move the measuring tank 10 from the reference position to the positive direction of the Z-axis direction, and sets the Z coordinate of the measuring tank 10 to Z(1). In addition, when the turbidity value to be determined is greater than or equal to turbidity threshold #1 and less than turbidity threshold #2, the control unit 53 drives the lifting mechanism 12 to move the measuring tank 10 from the reference position to the positive direction of the Z-axis direction, and sets the Z coordinate of the measuring tank 10 to Z(2). In addition, when the turbidity value to be determined is less than turbidity threshold #1, the control unit 53 drives the lifting mechanism 12 to move the measuring tank 10 from the reference position to the positive direction of the Z-axis direction, and sets the Z coordinate of the measuring tank 10 to Z(3).

[0094] Furthermore, if the predicted turbidity value is greater than or equal to turbidity threshold ##1 and less than turbidity threshold ##2, the control unit 53 drives the elevating mechanism 12 to move the measuring tank 10 from the reference position toward the negative direction of the Z-axis, and the Z coordinate of the measuring tank 10 is set to Z(-1). Furthermore, if the predicted turbidity value is greater than or equal to turbidity threshold ##2 and less than turbidity threshold ##3, the control unit 53 drives the elevating mechanism 12 to move the measuring tank 10 from the reference position toward the negative direction of the Z-axis, and the Z coordinate of the measuring tank 10 is set to Z(-2). Furthermore, if the predicted turbidity value is greater than or equal to turbidity threshold ##3, the control unit 53 drives the elevating mechanism 12 to operate the elevating mechanism 12 to move the measuring tank 10 from the reference position toward the negative direction of the Z-axis, and the Z coordinate of the measuring tank 10 is set to Z(-3).

[0095] When the estimated turbidity value is greater than or equal to turbidity threshold #3 and less than turbidity threshold ##1, the control unit 53 notifies the turbidity value calculation unit 51 of a turbidity value determination to set the estimated turbidity value as the actual turbidity value.

[0096] In this manner, the control unit 53 causes the elevating mechanism 12, which serves as a change mechanism, to move the measuring cell 10 from a predetermined position based on the first turbidity value. Furthermore, turbidity threshold #1 can be set to a low turbidity threshold, and turbidity threshold ##1 can be set to a high turbidity threshold. Specifically, when the first turbidity value is greater than or equal to a predetermined high turbidity threshold, the control unit 53 gradually moves the measuring cell 10 away from the light receiving element 31 based on the first turbidity value. Furthermore, when the first turbidity value is less than the low turbidity threshold, the control unit 53 gradually moves the measuring cell 10 toward the light receiving element 31 based on the first turbidity value.

[0097] While the above description utilizes three or more turbidity thresholds, the control unit 53 can also adjust the Z-axis position of the measurement cuvette 10 using a high turbidity threshold and a low turbidity threshold, similar to Embodiment 1. Specifically, when the first turbidity value is greater than or equal to a predetermined high turbidity threshold, the control unit 53 moves the measurement cuvette 10 away from the light receiving element 31. When the first turbidity value is less than a low turbidity threshold, the control unit 53 can move the measurement cuvette 10 toward the light receiving element 31. This low turbidity threshold is less than or equal to the high turbidity threshold.

[0098] Here, the control unit 53 may use the same value as the high turbidity threshold and the low turbidity threshold. In this case, the control unit 53 determines the position of the measuring tank 10 in the Z-axis direction based on whether the turbidity threshold is greater than or equal to the single turbidity threshold.

[0099] (Flow of turbidity value calculation process)

[0100] Figure 7 This is a flowchart of the turbidity value calculation process of the turbidity meter involved in embodiment 2. Figure 7 , the processing in which the position of the measuring tank 10 in the Z-axis direction is adjusted using the high turbidity threshold and the low turbidity threshold is shown as an example. Figure 7 The flow of turbidity value calculation processing by the turbidimeter 1 according to the second embodiment will be described.

[0101] The measurement tank 10 is placed at a position in a reference state (step S1 ).

[0102] The light source 22 irradiates light toward the liquid surface of the liquid to be measured stored in the measuring tank 10 via the lens 41 (step S2 ).

[0103] The light receiving element 31 receives scattered light of the light emitted from the light source 22 on the liquid surface and in the liquid via the lens 42 (step S3 ).

[0104] The light receiving element 31 detects the received scattered light. The amplifier 32 amplifies the intensity of the scattered light. The current conversion unit 33 converts the scattered light optical signal into a current signal indicating the intensity of the scattered light and outputs it to the control terminal device 50. The turbidity value calculation unit 51 calculates the turbidity value of the liquid to be measured using the current signal indicating the intensity of the scattered light (step S4).

[0105] The turbidity value calculation unit 51 determines whether the measurement being performed is a pre-measurement (step S5 ).

[0106] If the measurement being performed is pre-measurement (step S5: Yes), the turbidity value calculator 51 outputs the pre-measured turbidity value to the controller 53. The controller 53 determines whether the pre-measured turbidity value is greater than or equal to the high turbidity threshold (step S6).

[0107] If the estimated turbidity value is greater than or equal to the high turbidity threshold value (step S6: Yes), the control unit 53 uses the lifting mechanism 12 to move the measuring tank 10 in the negative direction of the Z axis to the high turbidity measurement position (step S7). The turbidity value calculation process then returns to step S2.

[0108] On the other hand, when the estimated turbidity value is smaller than the high turbidity threshold value (step S6 : No), the control unit 53 determines whether the estimated turbidity value is smaller than the low turbidity threshold value (step S8 ).

[0109] If the estimated turbidity value is less than the low turbidity threshold value (step S8: Yes), the control unit 53 uses the lifting mechanism 12 to move the measurement tank 10 in the positive direction of the Z axis to the low turbidity measurement position (step S9). The turbidity value calculation process then returns to step S2.

[0110] On the other hand, if the pre-determined turbidity value is greater than or equal to the low turbidity threshold value (step S8: No), the control unit 53 notifies the turbidity value determination to the turbidity value calculation unit 51. If the turbidity value determination is notified by the control unit 53 or if the measurement being performed is not pre-determined (step S5: No), the turbidity value calculation unit 51 sets the calculated turbidity value as the actual turbidity value of the measured liquid and displays it on the display unit 52 (step S10).

[0111] As described above, the turbidimeter 1 according to this embodiment pre-measures the turbidity value using the measurement cell 10 in a reference state and automatically adjusts the position of the measurement cell 10 in the Z-axis direction based on the calculation result of the pre-measured turbidity value. The turbidimeter 1 then re-calculates the turbidity value using the measurement cell 10 in the adjusted position and provides the user with the actual turbidity value of the specific test solution.

[0112] This allows the Z-axis position of the measuring cell 10 to be accurately and automatically adjusted in stages according to the turbidity value, without the need for manual intervention by the user. This allows for the acquisition of scattered light with an appropriate optical path length in the liquid, automatically and more precisely tailored to the state of the liquid being measured. This further improves linearity. This reduces the burden on the user, reduces human error, and improves the accuracy of turbidity measurements.

[0113] As described above, in Embodiment 2, the control unit 53 automatically adjusts the Z-axis position of the measuring cell 10 based on the pre-determined turbidity value. However, if the turbidimeter 1 includes a mechanism for changing the orientation of the optical axis of the light source 22, the control unit 53 may control this mechanism to automatically change the orientation of the optical axis of the light source 22 based on the pre-determined turbidity value. Alternatively, if the turbidimeter 1 includes a mechanism for changing the position of the light source 22, the control unit 53 may control this mechanism to automatically change the position of the light source 22 based on the pre-determined turbidity value. Alternatively, if the turbidimeter 1 includes a mechanism for changing the position of the light source 22, the control unit 53 may control this mechanism to automatically change the position of the light source 22 based on the pre-determined turbidity value. Alternatively, if the turbidimeter 1 includes a mechanism for changing the position of the light receiving element 31, the control unit 53 may control this mechanism to automatically change the position of the light receiving element 31 based on the pre-determined turbidity value.

[0114] (system)

[0115] Information including the processing sequence, control sequence, specific names, various data, and parameters described above and shown in the drawings can be arbitrarily changed unless otherwise specified.

[0116] Furthermore, the components of the devices shown in the diagrams are functional concepts and do not necessarily need to be physically configured as shown. Specifically, the specific methods of distributing and integrating the devices are not limited to those shown. Specifically, all or part of the components can be functionally or physically distributed / integrated in arbitrary units based on various loads, usage conditions, and the like.

[0117] Furthermore, all or any part of each processing function performed by each device may be realized by a CPU (Central Processing Unit) and a program analyzed and executed by the CPU, or may be realized as hardware based on wired logic.

[0118] (hardware)

[0119] Next, a hardware configuration example of the control terminal device 50 will be described. Figure 8 This is the hardware structure diagram of the control terminal device. Figure 8 As shown, the control terminal device 50 includes a processor 91, a memory 92, a hard disk 93, a network interface 94, and a display device 95. The processor 91 is connected to the memory 92, the hard disk 93, the network interface 94, and the display device 95 via a bus.

[0120] The network interface 94 is a network interface card or the like, and is used for communication with other information processing devices. The display device 95 is a monitor, a display, or the like, and realizes the function of the display unit 52.

[0121] The hard disk 93 is an auxiliary storage device. The hard disk 93 can store, for example, Figure 5The hard disk 93 stores various programs including a program for realizing the functions of the turbidity value calculation unit 51 and the control unit 53 .

[0122] The processor 91 reads various programs stored in the hard disk 93 and executes them in the memory 92. Thus, the processor 91 realizes the functions of the turbidity value calculation unit 51 and the control unit 53.

[0123] In this way, the control terminal device 50 operates as an information processing device that performs various processing methods by reading and executing programs. Furthermore, the control terminal device 50 can also read the program from a recording medium using a media reader and execute the read program, thereby achieving the same functions as the above-described embodiment. Furthermore, the program described herein is not limited to being executed solely by the control terminal device 50. For example, the present invention can also be applied to programs executed by other computers or servers, or when these computers and servers collaborate to execute the program.

[0124] The program can be distributed via a network such as the Internet. In addition, the program can be recorded on a computer-readable recording medium such as a hard disk, a floppy disk (FD), a CD-ROM, an MO (Magneto-Optical disk), or a DVD (Digital Versatile Disc), and executed by being read from the recording medium by a computer.

[0125] Description of the label

[0126] 1 Turbidimeter

[0127] 10 Measuring tank

[0128] 11 Darkroom

[0129] 12 Lifting mechanism

[0130] 21 Illumination control circuit

[0131] 22 Light Source

[0132] 30 Light receiving circuit

[0133] 31 Light receiving element

[0134] 32 amplifiers

[0135] 33 Current conversion unit

[0136] 41, 42 lenses

[0137] 50 Control terminal device

[0138] 51 Turbidity value calculation unit

[0139] 52 Display unit

[0140] 53 Control Department

Claims

1. A surface scattering turbidimeter, characterized in that The surface scattering turbidimeter has: a measuring tank for storing the liquid to be measured; a light source for irradiating light onto a liquid surface of the liquid to be measured stored in the measuring tank; a light receiving element for receiving scattered light generated in the measuring cell by the light from the light source; a changing mechanism for changing a relative position of a position of the light from the light source on the liquid surface and a component of the light receiving element at the liquid surface level with respect to a traveling direction of the light; as well as A turbidity value calculation unit calculates the turbidity value of the liquid to be measured based on the scattered light received by the light receiving element.

2. The surface scattering turbidimeter according to claim 1, wherein The changing mechanism changes the relative position by changing the distance between the measuring slot and the light receiving element.

3. The surface scattering turbidimeter according to claim 2, wherein: The changing mechanism is a mechanism that changes the distance between the measuring slot and the light receiving element by moving the measuring slot.

4. The surface scattering turbidimeter according to claim 3, wherein The turbidity value calculation unit calculates a first turbidity value of the liquid to be measured when the relative position is in a first state, and calculates a second turbidity value of the liquid to be measured when the relative position is in a second state. The surface scattering turbidimeter further includes a control unit that controls the changing mechanism based on the first turbidity value so that the relative position changes from the first state to the second state.

5. The surface scattering turbidimeter according to claim 4, wherein When the first turbidity value is greater than or equal to a high turbidity threshold, the control unit controls the changing mechanism to change the relative position in a manner that shortens the optical path length of the light in the measured liquid. When the first turbidity value is less than a low turbidity threshold, the control unit controls the changing mechanism to change the relative position in a manner that lengthens the optical path length, and the low turbidity threshold is less than or equal to the high turbidity threshold.

6. The surface scattering turbidimeter according to claim 5, wherein When the first turbidity value is greater than or equal to the high turbidity threshold, the control unit controls the changing mechanism to change the relative position in a manner that shortens the optical path length in stages according to the first turbidity value. When the first turbidity value is less than the low turbidity threshold, the control unit controls the changing mechanism to change the relative position in a manner that extends the optical path length in stages according to the first turbidity value.

7. The surface scattering turbidimeter according to claim 2, wherein: The changing mechanism is a mechanism that moves the light receiving element to change the distance between the measuring slot and the light receiving element.

8. The surface scattering turbidimeter according to claim 1, wherein The changing mechanism changes the relative position by changing the direction of the optical axis of the light from the light source.

9. The surface scattering turbidimeter according to claim 1, wherein The changing mechanism changes the relative position by changing the position of the light source.

10. A turbidity measurement method using a surface scattering turbidimeter comprising: a measuring cell storing a liquid to be measured; a light source irradiating light onto the liquid surface of the liquid to be measured stored in the measuring cell; and a light receiving element receiving scattered light generated in the measuring cell by the light from the light source, wherein: The changing mechanism changes the relative position of the irradiation position of the light from the light source on the liquid surface and the component of the light receiving element at the liquid surface level with respect to the traveling direction of the light, The turbidity value calculation device is configured to calculate the turbidity value of the liquid to be measured based on the scattered light received by the light receiving element.

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