Particle measuring device and particle measuring method

Abstract

Providing technology to prevent contamination of flow cells during particle measurement. [Solution] When a liquid sample is poured into the flow cell 30 and the irradiation light is focused onto the detection area, scattered light is generated as particles and bubbles pass through the detection area, as well as scattered light is generated by the interaction between the irradiation light and the liquid sample and the walls of the flow cell, and the detector 60 outputs a signal of a magnitude corresponding to the intensity of the scattered light. The calculation unit 70 passes this signal through a low-pass filter 71 to extract the low-frequency component, performs calculations regarding the change in the signal over time after passing through the filter, and considers the presence of a gas layer if the calculation result exceeds a predetermined threshold. In addition, based on the output signal of the detector 60, the calculation unit 70 performs calculations regarding the frequency and magnitude of scattered light pulses per unit time, and considers the presence of high-density particles or bubbles if the calculation result exceeds a predetermined threshold. In either case, the calculation unit 70 notifies the control unit 80. Accordingly, the control unit 80 controls the irradiation light in a manner different from the normal.

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for measuring the number of particles, particle size, refractive index, etc., contained in a liquid sample. [Background technology]

[0002] When measuring fine particles present in a liquid sample, in addition to the particles being measured, bubbles containing trapped gases such as air, and gas layers—regions where gas occupies the entire cross-section of a flow path cut perpendicular to the flow direction—may also be present.

[0003] For example, in the comparative example measuring apparatus 1' shown in Figure 7(A), the sample flows in the direction of the flow meter 90' in the piping 32' connected to the flow cell 30', and a gas layer is located upstream of the flow cell 30'. Irradiation light L from light source 10' a Before the gas layer reaches the detection region formed when the gas is incident on the flow cell 30', scattered light L generated in the detection region s The output signal from the photodetector 60' that detects the particles, as shown in Figure 7(B), mainly consists of low-frequency components including DC due to liquid scattering, with particle or bubble scattering appearing as pulses with high peak values ​​(maximum values) (waveforms with a narrow rise time). On the other hand, when the gas layer passes through the detection region, as shown in Figure 7(C), the waveform appears as if the low-frequency components including DC have been boosted. Depending on the type of liquid sample, the low-frequency components including DC may also be lower.

[0004] In measuring fine particles in a liquid using this type of irradiation light, high-density particles can contaminate the walls of the flow cell. Furthermore, if there are areas with high bubble density or gas layers, the heat from the irradiation light can cause the liquid to evaporate, leading to the precipitation or burning of dissolved substances into the flow cell, which also contaminates the flow cell walls. Since this contamination of the flow cell walls affects particle measurement, some kind of countermeasure is necessary.

[0005] Reference 1 discloses a method for measuring fine particles in a liquid by measuring the time during which the magnitude of the signal based on scattered light from a liquid exceeds a predetermined threshold. Signals with a duration shorter than the predetermined time are considered to correspond to scattered light from fine particles in the liquid, while those with a duration longer than the predetermined time are considered to correspond to scattered light from bubbles in the liquid and are excluded, thereby discriminating between fine particles in a liquid and bubbles and counting only fine particles in the liquid.

[0006] Furthermore, References 2 and 3 disclose an optical liquid particle counter system in which a fluid monitoring system is separately provided in the conduit through which the liquid sample to be analyzed passes, which is connected to the flow chamber of the liquid particle counter. A processor analyzes the monitoring data received from the fluid monitoring system and, if it determines the presence of bubbles in the liquid, activates an optical interrupter that redirects, reshapes, or reduces the fluence of electromagnetic radiation from the light source. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 6-323982 [Patent Document 2] Patent No. 6973801 [Patent Document 3] Patent No. 7255049 [Overview of the project] [Problems that the invention aims to solve]

[0008] According to the technology disclosed in Patent Document 1, it is thought that liquid-based fine particles and bubbles can be distinguished to some extent, but the distinction is limited to bubbles that are sufficiently large relative to the fine particles being measured.

[0009] Regarding the technologies disclosed in Patent Documents 2 and 3, it is not disclosed how the fluid monitoring system specifically detects bubbles. Furthermore, although an optical interrupter is activated based on the analysis results of the monitoring data, particle measurement and fluid monitoring are performed separately in different locations, and it is unclear how much time is required from the time the monitoring data is collected until the response is taken based on the analysis results. If the response is delayed, the flow cell will become contaminated in the meantime, so immediate response is required. In addition, a fluid monitoring system separate from the liquid particle counter is provided, but such a configuration makes the entire installation large, which imposes constraints on the installation environment.

[0010] This invention has been made in view of these problems, and aims to provide a technology for preventing contamination of flow cells associated with particle measurement. [Means for solving the problem]

[0011] To solve the above problems, the present invention employs the following particle measuring device and a method implemented by this particle measuring device. Note that the following statements in parentheses are merely examples, and the present invention is not limited thereto.

[0012] In other words, the particle measuring device of the present invention comprises a flow cell into which a liquid sample is poured, a light source that emits irradiation light, a photodetector that detects scattered light generated by the action of the irradiation light in a detection area within the flow cell and outputs a detection signal of a magnitude corresponding to the intensity of the scattered light, a calculation unit that measures at least one of the size, number, and refractive index of particles contained in the liquid sample based on the detection signal, determines the state of the liquid sample from the result of a predetermined calculation based on the detection signal, and provides a predetermined notification according to the determination result, and a control unit that limits the irradiation light incident on the flow cell when a predetermined notification is received. Furthermore, the calculation unit determines the presence or absence of high-density particles or bubbles in the liquid sample as a state of the liquid sample. Alternatively, the calculation unit determines the presence or absence of a gas layer in the liquid sample as a state of the liquid sample.

[0013] Restricting the illumination light refers to control measures such as dimming or turning off the illumination light, blocking the illumination light with a shutter, or changing the optical path of the illumination light so that it does not enter the flow cell. Under normal circumstances, the illumination light is controlled to enter the flow cell directly or indirectly (through lenses, mirrors, etc.) with a sufficient amount of light required for measurement. In other words, under normal control of the illumination light, dimming, turning off, blocking, or changing the optical path of the illumination light is not performed. Furthermore, restricting the illumination light can be rephrased as controlling the illumination light in a manner different from normal, and releasing the restriction of the illumination light can be rephrased as returning the control of the illumination light to its normal manner.

[0014] In this embodiment of the particle measuring device, while the particles contained in the liquid sample are measured based on the detection signal of scattered light generated in the detection area, a determination is made regarding the state of the liquid sample. If it is determined that a gas layer or high-density particles or bubbles are present, the irradiation light is controlled in a manner different from the usual.

[0015] Therefore, with this embodiment of the particle measuring device, the incidence of irradiation light into the flow cell can be quickly restricted when a gas layer, high-density particles, or bubbles are present, thereby reducing the occurrence of situations in which the liquid sample may be excessively heated and evaporated by the irradiation light, and thus preventing contamination of the flow cell during measurement. Furthermore, with this embodiment of the particle measuring device, there is no need to provide a separate structure for monitoring the state of the liquid sample, so there is no concern that such a structure may generate new particles, and the overall size of the device can be avoided.

[0016] Preferably, in a particle measuring device according to any of the above-described embodiments, the calculation unit provides a predetermined notification to the control unit when the frequency of pulses with an intensity exceeding a certain value exceeds a predetermined threshold.

[0017] Generally, the higher the density of particles or bubbles, the more easily the flow cell becomes contaminated. According to the particle measuring device of this aspect, when the frequency of pulses whose detection signal intensity exceeds a certain value exceeds the threshold, the incidence of irradiation light to the flow cell is restricted. Therefore, in a situation where high-density particles or bubbles are present, it is possible to prevent the evaporation of the liquid sample due to the heat of the irradiation light, and as a result, it becomes possible to prevent the contamination of the flow cell.

[0018] More preferably, in the particle measuring device of any of the above-described aspects, when a predetermined statistical value based on the magnitude of pulses regarding the detection signal within a unit time exceeds a predetermined threshold, the calculation unit gives a predetermined notification to the control unit.

[0019] Generally, the larger the particles or bubbles, the more easily the flow cell becomes contaminated. According to the particle measuring device of this aspect, when a predetermined statistical value based on the magnitude of pulses regarding the detection signal within a unit time exceeds the threshold, the incidence of irradiation light to the flow cell is restricted. Therefore, in a situation where the flow cell is likely to be contaminated, it is possible to prevent the evaporation of the liquid sample due to the heat of the irradiation light, and as a result, it becomes possible to prevent the contamination of the flow cell.

[0020] Even more preferably, in the particle measuring device of any of the above-described aspects, the calculation unit calculates a predetermined statistical value by multiplying the frequency of pulses by a weighting constant according to the magnitude of the pulses regarding the detection signal within a unit time, and when the statistical value exceeds a predetermined threshold, gives a predetermined notification to the control unit.

[0021] According to the particle measuring device of this aspect, since a weighting constant is used for the frequency of pulses according to the magnitude of the pulses, it is possible to increase the weight for pulses (the magnitude of the pulses or the number of pulses for each range of magnitudes) that are likely to contribute to the contamination of the flow cell and calculate a predetermined statistical value, and it is possible to more appropriately determine whether the situation is one where the flow cell is likely to be contaminated, and it becomes possible to limit the irradiation light at a more appropriate timing.

[0022] Furthermore, preferably, in the particle measuring device according to any of the above embodiments, the calculation unit provides a predetermined notification to the control unit when the change in the low-frequency component of the detection signal exceeds a predetermined threshold.

[0023] The low-frequency components of the detected signal may include components originating from the liquid sample or the gaseous layer. According to this embodiment of the particle measuring device, the irradiation light is restricted when the change in the low-frequency components exceeds a threshold. Therefore, the presence of a gaseous layer (that the signal is not originating from the liquid sample) can be detected from the magnitude of the change in the low-frequency components, preventing the liquid sample from evaporating due to the heat of the irradiation light in such situations, and as a result, contamination of the flow cell can be prevented.

[0024] More preferably, in a particle measuring device according to any of the above embodiments, the control unit releases the restriction on the irradiation light incident on the flow cell when a predetermined condition is met after a predetermined notification has ceased to be made.

[0025] According to this type of particle measuring device, the irradiation light incident on the flow cell is restricted (the irradiation light is controlled in a manner different from normal) in response to a predetermined notification. After the predetermined notification is no longer given and predetermined conditions (for example, after a certain period of time has elapsed) are met, the restriction on the irradiation light is released (the irradiation light control returns to the normal manner), allowing measurement to be automatically resumed without human intervention. [Effects of the Invention]

[0026] As described above, the particle measuring device of the present invention can prevent contamination of the flow cell that may occur during particle measurement. [Brief explanation of the drawing]

[0027] [Figure 1] This is a block diagram showing the configuration of particle measuring device 1. [Figure 2] This flowchart shows an example of a procedure for pollution prevention treatment based on the detection of the atmospheric layer. [Figure 3]This flowchart shows an example procedure for contamination prevention treatment (first embodiment) based on the detection of high-density particles or bubbles. [Figure 4] This flowchart shows an example procedure for a contamination prevention treatment (second embodiment) based on the detection of high-density particles or bubbles. [Figure 5] This flowchart shows an example procedure for contamination prevention treatment (third embodiment) based on the detection of high-density particles or bubbles. [Figure 6] This flowchart shows an example procedure for contamination prevention treatment (fourth embodiment) based on the detection of high-density particles or bubbles. [Figure 7] This diagram illustrates the waveform that appears in the detection signal of scattered light during the measurement of fine particles in a liquid. [Modes for carrying out the invention]

[0028] Embodiments of the present invention will be described below with reference to the drawings. The following embodiments are preferred examples, and the present invention is not limited to these examples.

[0029] [Configuration of the particle measuring device] Figure 1 is a block diagram showing the configuration of a particle measuring device 1 according to one embodiment. In Figure 1, the direction of light traveling between components is indicated by dashed arrows, and the direction of signals is indicated by solid arrows.

[0030] The particle measuring device 1 includes, for example, a light source 10, a first focusing lens 20, a flow cell 30, a beam damper 40, a second focusing lens 50, a photodetector 60, a calculation unit 70, and a control unit 80.

[0031] The light source 10 emits a predetermined light (e.g., laser light) used for measurement. Hereinafter, the light emitted from the light source 10 will be referred to as "irradiated light". The first focusing lens 20 receives the illumination light L emitted from the light source 10. a The degree of light concentration on the flow cell 30 is adjusted, and the irradiation light L a The light is focused into a predetermined area within the flow cell 30 (hereinafter referred to as the "detection area").

[0032] The flow cell 30 is made of a glass material such as synthetic quartz or optical glass, or a crystalline material such as synthetic corundum. When irradiation light L is applied to the detection region with a liquid sample flowing into the interior of the flow cell 30 a is condensed, when particles or bubbles pass through the detection region, irradiation light La hits them and scattered light is generated. Also, in the detection region, scattered light is generated by the interaction between the irradiation light L a and the liquid sample, and by the interaction between the irradiation light L a and the wall surface of the flow cell 3o. If there is dirt on the wall surface of the flow cell 30, absorption and scattering of the irradiation light will occur due to this, leading to a decrease in detection sensitivity and false detection. The second condenser lens 50 adjusts the degree of condensation of the scattered light L s generated in the detection region onto the photodetector 60, and adjusts the spreading manner of the scattered light L s so that the photodetector 60 can detect efficiently. Incidentally, the irradiation light L a transmitted through the flow cell 30 is absorbed by the beam damper 40. Thereby, it is possible to prevent the irradiation light L a transmitted through the flow cell 30 from diffusing inside the particle measuring device 1 and affecting the measurement.

[0033] The photodetector 60 outputs an electrical signal having a magnitude corresponding to the intensity of the light received by the light receiving element inside it. The light receiving element of the photodetector 60 may form a single continuous light receiving surface, or a plurality of light receiving elements may be arranged in one dimension (column) or two dimensions (plane) to form a light receiving surface divided in a grid pattern.

[0034] The calculation unit 70 is composed of, for example, a low-pass filter 71, a counting unit 72, and a determination unit 73. The low-pass filter 71 receives the signal output from the photodetector 60. The low-pass filter 71 performs calculations such as time averaging on the input signal and allows only components of the input signal below a predetermined cutoff frequency to pass through. The counting unit 72 receives the signal output from the photodetector 60 and the signal that has passed through the low-pass filter 71. The counting unit 72 calculates the particle size from the magnitude of the peak value of the pulse in the output signal of the photodetector 60, counts the number of particles from the number of pulses whose peak value exceeds a predetermined threshold, and also calculates the refractive index of the particles. Furthermore, the counting unit 72 performs predetermined calculations necessary to prevent contamination of the flow cell 30 based on each of the two input signals (the output signal of the photodetector 60 and the signal after passing through the low-pass filter 71).

[0035] The determination unit 73 determines whether the result of a predetermined calculation performed by the counting unit 72 exceeds a predetermined threshold for determination corresponding to each calculation. If it exceeds the threshold, it considers that there is a gas layer or a part with a high density of particles or bubbles in the liquid sample, that is, there is a high possibility that the flow cell 30 is contaminated, and notifies the control unit 80 accordingly. Upon receiving this notification, the control unit 80 controls the light source 10 to limit the output of the irradiation light. For example, the control unit 80 may reduce or stop the output of the irradiation light. Furthermore, based on the situation during the period without notification from the determination unit 73, the control unit 80 controls the irradiation light, which had its output limited, to return to its original state (normal output) according to predetermined conditions such as the passage of a set time. Note that a different value from the above-mentioned threshold for determination may be used as the condition for discontinuing notifications from the determination unit 73 (changing the notification from ON to OFF). Furthermore, when the irradiation light is returned to its original state, a different value from the threshold for determination described above may be used as the condition for the determination unit 73 to issue a notification (change the notification from OFF to ON), and in that case, the threshold may be returned to the threshold for determination described above after a certain period of time has elapsed since the irradiation light was returned to its original state.

[0036] Thus, the predetermined calculations performed by the counting unit 72 calculate values ​​necessary for determining the state of the liquid sample, i.e., whether or not there is a gas layer or high-density particles or bubbles in the liquid sample. The determination unit 73 determines and monitors the state of the liquid sample based on the results of the predetermined calculations, and the control unit 80 controls the operation of the light source 10 to prevent contamination of the flow cell 30 according to the determination result regarding the state of the liquid sample.

[0037] Incidentally, in measurements, the frequency of scattered light pulses increases when the density of particles or bubbles in a liquid sample is high. The intensity of scattered light produced when the irradiated light strikes particles or bubbles is related to the difference in refractive index between the liquid sample and the particles, as well as the particle size. Therefore, bubbles do not necessarily produce weaker scattered light than particles of the same size. By focusing on the pulse frequency, it is possible to detect the presence of high density of particles or bubbles of similar size being measured.

[0038] Furthermore, when particles or bubbles are present at very high density, individual pulses overlap in close proximity, increasing the low-frequency components, including DC. On the other hand, the gas layer that fills the entire cross-section of the flow channel of the flow cell 30 can be considered as a very large bubble, but the mechanism of scattered light by the gas layer is different from that of scattered light by bubbles. That is, scattered light by bubbles is due to the difference in refractive index between the gas and the liquid of the liquid sample, whereas scattered light by the gas layer is due to the non-uniform refractive index within the gas. This is similar to how light scattering by the liquid in a liquid sample is due to non-uniform refractive index within the liquid. Since non-uniform refractive index occurs throughout the gas, scattered light by the gas layer appears as a low-frequency component, including DC, in the output signal from the photodetector 60, similar to the case of very high-density bubbles, but it is not necessarily stronger than the light scattering from the liquid.

[0039] Furthermore, scattered light is also generated at the boundary between the flow cell 30 and the liquid, or at the boundary between the flow cell 30 and the gas layer. For example, when quartz is used as the material for the flow cell 30, the refractive index is about 1.5, while the refractive index of the gas layer (air) is about 1.0, and the refractive index of water is about 1.3. In this configuration, the difference in refractive index at the boundary between the flow cell 30 and the gas layer is greater than the difference in refractive index at the boundary between the flow cell 30 and the water, and therefore the scattered light generated at the boundary between the flow cell 30 and the gas layer is stronger. Depending on the properties of the flow cell 30 and the liquid, the intensity of the scattered light may be reversed. In any case, the intensity of the scattered light generated at the boundary between the flow cell 30 and the liquid or gas layer does not change much, and therefore appears as a low-frequency component output including DC from the photodetector 60. Therefore, by focusing on changes in the strength or weakness of the low-frequency component including DC, the presence of the gas layer can be detected.

[0040] Therefore, in the particle measurement device 1, the presence of a gas layer is detected by focusing on changes in the strength or weakness of the low-frequency component, including DC, in the output signal of the photodetector 60, and the presence of particles or bubbles at high density is detected by focusing on the characteristics of the pulse within a unit time. When the presence of a gas layer or high-density particles or bubbles is detected, the light source 10 is controlled to limit the output of the irradiated light. This control makes it possible to prevent contamination of the flow cell 30 that may occur during measurement.

[0041] The details of the contamination prevention treatments that can be performed in particle measurement device 1 will be described below with reference to Figures 2 to 6. Each contamination prevention treatment is performed continuously in parallel with particle measurement.

[0042] [Contamination prevention treatment based on gas layer detection] Figure 2 is a flowchart illustrating an example of a contamination prevention procedure based on gas layer detection. The following explanation will follow this example procedure.

[0043] Step S1: The signal X(t) output from the photodetector 60 at a certain time t is passed through the low-pass filter 71 to obtain the filtered signal XL(t). The typical cutoff frequency of the low-pass filter 71 is approximately 1 / 10 to 1 / 10000 of the frequency of the signal caused by the particles. The filtered signal XL(t) is input to the counting unit 72.

[0044] Typically, the diameter of particles and bubbles is determined by the irradiation light L a Because the pulse width of the signals originating from these is smaller than the beam width, the pulse width of the signals originating from them is determined by the time it takes to pass through the beam. In contrast, the length of the gas layer is greater than the beam width and can be greater than the width of the flow channel cross-section of the flow cell 30 (the cross-section perpendicular to the direction in which the flow channel extends). Therefore, the duration of the signal from the gas layer is inevitably longer. From this, signals originating from particles or bubbles and signals originating from the liquid or gas layer can be distinguished to some extent by the time width of the signal. By passing the signal through the low-pass filter 71, the low-frequency component, i.e., the component originating from the liquid or gas layer, can be roughly extracted from the signal X(t), and this becomes the signal XL(t).

[0045] Step S2: A determination is made based on a comparison of the current signal value (at time t) and the previous signal value (at time t-1). Specifically, the counting unit 72 calculates the magnitude of the difference between signal XL(t) and signal XL(t-1) (|XL(t)-XL(t-1)|), and the determination unit 73 checks whether this calculation result is greater than a predetermined threshold corresponding to the calculation. If the calculation result is greater than the threshold (Step S2: Yes), the determination unit 73 considers that the signal is not caused by liquid, i.e., that a gas layer or particles or bubbles of very high density are mixed in, notifies the control unit 80, and proceeds to step S3.

[0046] Step S3: Light source control processing is performed. In this process, in response to a notification from the determination unit 73, the control unit 80 performs control such as stopping the emission of light from the light source 10 (turning off the light) or weakening the light output (dimming the light).

[0047] The threshold used for the determination in step S2 may be a fixed value, or a variable value may be set, for example, a range of 10% from the previous signal value (in this example, the threshold is set as XL(t-1) × 0.1). Alternatively, instead of making a determination based on the magnitude of the difference between the current signal value and the previous signal value, the determination may be made based on whether the current signal value deviates from a predetermined range of values. Or, instead of comparing the current signal value with the previous signal value (the signal value at the previous point in time), the current signal value may be compared with the signal value at two or more points in time, and the determination may be made based on the magnitude of the difference between them.

[0048] [Contamination prevention treatment based on detection of high-density particles or bubbles: First embodiment] Figure 3 is a flowchart showing an example procedure of a first embodiment of a contamination prevention treatment based on the detection of high-density particles or bubbles. The procedure will be described below in accordance with this example.

[0049] Step S11: The counting unit 72 counts the peak value of the output signal of the photodetector 60 within a certain time (e.g., 1 second) to a predetermined threshold V. th Count the number of times N exceeds the limit.

[0050] Step S12: The determination unit 73 checks whether the number of counts N is greater than a predetermined threshold corresponding to the calculation. If the number of counts N is greater than the threshold (Step S12: Yes), the determination unit 73 considers that there is a portion with a high density of particles or bubbles, notifies the control unit 80, and proceeds to step S13.

[0051] Step S13: Light source control processing is performed. The content of this processing is the same as the light source control processing in step S3 in Figure 2 above.

[0052] Thus, the first embodiment of the contamination prevention treatment based on the detection of high-density particles or bubbles focuses solely on the number of particles or bubbles per unit time (pulse frequency) to detect their presence at high density and controls the operation of the light source 10 accordingly.

[0053] In contrast, the second to fourth embodiments described below control the flow cell 30 by focusing not only on the number of measured particles or bubbles (pulse frequency) but also on their size (pulse height). Generally, the higher the density of particles or bubbles, and the larger the particles or bubbles, the more easily the flow cell 30 becomes contaminated. Therefore, by determining the possibility of contamination from the relationship between the number and size of measured particles or bubbles, the operation of the light source 10 can be controlled more effectively, and contamination of the flow cell 30 can be prevented more reliably.

[0054] [Contamination prevention treatment based on detection of high-density particles or bubbles: Second embodiment] Figure 4 is a flowchart showing an example procedure of a second embodiment of a contamination prevention treatment based on the detection of high-density particles or bubbles. The procedure will be described below in accordance with this example.

[0055] Step S21: The counting unit 72 integrates the output signal of the photodetector 60 over a certain period of time (for example, 1 second).

[0056] Step S22: The determination unit 73 checks whether the integral value obtained in step S21 exceeds a predetermined threshold for the calculation. If the integral value exceeds the threshold (step S22: Yes), the determination unit 73 considers that there is a high possibility that the flow cell 30 is contaminated, notifies the control unit 80, and proceeds to step S23.

[0057] Step S23: Light source control processing is performed. The content of this processing is the same as the light source control processing in step S3 in Figure 2 above.

[0058] [Contamination prevention treatment based on detection of high-density particles or bubbles: Third embodiment] Figure 5 is a flowchart showing an example procedure of a third embodiment of a contamination prevention treatment based on the detection of high-density particles or bubbles. The procedure will be described below in accordance with this example.

[0059] Step S31: The counting unit 72 counts the peak value of the output signal of the photodetector 60 within a certain time (e.g., 1 second) to a predetermined threshold V. th The number of times Np exceeds a certain threshold is counted, and the magnitude (peak value) of the i-th pulse is taken as Hi. The sum of the products of a predetermined constant α (e.g., 1.0) and the pulse magnitude Hi, Ap, is calculated. Specifically, the sum Ap is calculated using the following formula.

[0060]

number

[0061] Step S32: The determination unit 73 checks whether the sum Ap calculated in step S31 exceeds a predetermined threshold corresponding to the calculation. If the sum Ap exceeds the threshold (step S32: Yes), the determination unit 73 considers that there is a high possibility that the flow cell 30 is contaminated, notifies the control unit 80, and proceeds to step S33.

[0062] Step S33: Light source control processing is executed. The content of this processing is the same as the light source control processing in step S3 in Figure 2 above.

[0063] In the example procedure above, a single constant α is used to calculate the sum Ap, but instead, different constants may be used depending on the pulse magnitude Hi. For example, if the pulse magnitude Hi falls within the low range (e.g., 30-120mV), a low-range constant αl (e.g., 1.0) is used; if it falls within the medium range (e.g., 120-900mV), a medium-range constant αm (e.g., 2.0) is used; and if it falls within the high range (e.g., 900mV or higher), a high-range constant αh (e.g., 4.0) is used. It is possible to calculate the sum of the products of the pulse magnitude Hi and the corresponding constants. This allows for effective weighting according to the pulse magnitude (and thus, the size of the particle or bubble). Furthermore, instead of multiplying the pulse magnitude Hi by the constant α, it is possible to use a power of Hi (i.e., Hi) αIt is also possible to perform weighting using other operations such as (as in other embodiments).

[0064] [Contamination prevention treatment based on detection of high-density particles or bubbles: Fourth embodiment] Alternatively, instead of weighting the pulse size, the pulse size may be divided into defined ranges, and weighting may be applied to the number of particles in each range. Figure 6 is a flowchart showing an example procedure of the fourth embodiment of a contamination prevention treatment based on the detection of high-density particles or bubbles, in which weighting is applied according to the number of particles in each pulse size range. The procedure will be explained below in accordance with this example.

[0065] Step S41: The counting unit 72 counts the peak value of the output signal of the photodetector 60 within a certain time (e.g., 1 second) to a predetermined threshold V. th The number of times the peak value (pulse magnitude) exceeds a certain threshold is counted for each range. For example, the number of times the peak value (pulse magnitude) falls within the low range (Nl), the number of times it falls within the medium range (Nm), and the number of times it falls within the high range (Nh) are counted, respectively.

[0066] Step S42: The counting unit 72 then uses the constants αl, αm, and αh for each range, as exemplified in the modified example of the third embodiment described above, to calculate the sum of the products of the number of steps for each range and the constants (αl × Nl + αm × Nm + αh × Nh).

[0067] Step S43: The determination unit 73 checks whether the sum calculated in step S42 exceeds a predetermined threshold corresponding to that calculation. If the sum exceeds the threshold (Step S43: Yes), the determination unit 73 considers that there is a high possibility that the flow cell 30 is contaminated, notifies the control unit 80, and proceeds to step S44.

[0068] Step S44: The light source control process is executed. The content of this process is the same as the light source control process in step S3 in Figure 2 above.

[0069] As described above, in the particle measuring device 1, contamination prevention treatment based on the detection of a gas layer (Figure 2) and contamination prevention treatment based on the detection of high-density particles or bubbles (any of Figures 3 to 6) are performed, and predetermined calculations are made according to each treatment. From the results, the state of the liquid sample is determined, and if it is determined that a gas layer or high-density particles or bubbles are present, the operation of the light source 10 (the mode of irradiation) is controlled in a manner different from the normal, and the output of the irradiation light is limited. Therefore, with the particle measuring device 1, it is possible to reduce the occurrence of situations in which the liquid sample may be excessively heated and evaporated by the irradiation light, and thus it is possible to prevent the walls of the flow cell 30 from becoming contaminated by the precipitation or burning of substances dissolved in the liquid.

[0070] [Advantages of the present invention] As described above, the following effects can be obtained using the particle measurement device 1 described above.

[0071] (1) In the particle measuring device 1, during the contamination prevention process based on the detection of a gas layer (Figure 2), which is performed in parallel with the measurement of particles, calculations are made regarding the changes over time in the low-frequency components, including DC, extracted by passing the output signal of the photodetector 60 through the low-pass filter 71. A comparison is then made with a predetermined threshold corresponding to these calculations, thereby enabling the detection of the presence of a gas layer in the liquid sample that causes contamination of the wall surface of the flow cell 30.

[0072] (2) In the particle measuring device 1, during the contamination prevention treatment (any of Figures 3 to 6) which is performed in parallel with particle measurement and is based on the detection of high-density particles or bubbles, a calculation is performed to obtain statistical values ​​for scattered light pulses per unit time, and a comparison is made with a predetermined threshold corresponding to this calculation, so that the presence of high-density particles or bubbles in the liquid sample that cause contamination of the wall surface of the flow cell 30 can be detected.

[0073] (3) During the process of performing the contamination prevention treatment (Figures 2 to 6), if a gas layer or high-density particles or bubbles are detected in the liquid sample (it is determined that there is a high possibility of contamination of the flow cell 30), the output of the irradiation light from the light source 10 is limited (the irradiation pattern is changed to a pattern different from the normal one). This reduces the occurrence of situations in which the sample fluid may be excessively heated and evaporated by the irradiation light, thereby preventing dirt from adhering to the walls of the flow cell 30.

[0074] (4) In a modified or fourth embodiment of the third embodiment of the contamination prevention treatment based on the detection of high-density particles or bubbles, statistical values ​​are calculated using weighting constants αl, αm, and αh corresponding to the pulse magnitude, so that it is possible to more appropriately determine whether the flow cell 30 is in a condition where it is easily contaminated, and the output of the irradiation light can be limited at a more appropriate timing according to this determination result.

[0075] (5) Since both the particle measurement process and the flow cell contamination prevention process are performed based on the output signal of the photodetector 60, the output of the irradiation light can be quickly limited according to the result of the determination of the state of the liquid sample (detection of a gas layer or high-density particles or bubbles). Furthermore, since there is no need to provide a separate configuration to monitor the state of the liquid sample, there is no concern about the generation of new particles from such a configuration that would be expected if a separate configuration were added, and the overall size of the apparatus does not increase.

[0076] The present invention can be implemented in various ways without being limited to the embodiments described above.

[0077] In the embodiments described above, contamination prevention processing based on the detection of a gas layer (Figure 2) and contamination prevention processing based on the detection of high-density particles or bubbles (any of Figures 3 to 6) are performed. However, instead, only one of the contamination prevention processing methods shown in Figures 2 to 6 may be performed, or multiple methods may be performed simultaneously. Furthermore, when multiple contamination prevention processing methods are performed simultaneously, the light source control processing may be performed when a threshold is exceeded in any of the contamination prevention processing methods, or the light source control processing may be performed only when a threshold is exceeded in two or more contamination prevention processing methods.

[0078] In the above-described embodiment, the light output from the light source 10 is limited (the light is turned off or dimmed) in the light source control process. However, instead, a shutter capable of shielding the outlet of the light source 10 may be provided separately, and the control unit 80 may control the closing of the shutter to block the irradiated light and limit the irradiated light directed toward the flow cell 30. Alternatively, the incidence of irradiated light may be limited by changing the optical path of the irradiated light by controlling the light source 10 or the first focusing lens 20 to prevent the irradiated light from entering the flow cell 30. Furthermore, an alarm may be issued in conjunction with the restriction of irradiated light by issuing warning information to other devices such as a computer, or by providing a means capable of outputting sound (e.g., a buzzer) to emit an alarm sound. With such a configuration, the user can be notified that the irradiated light is limited, that is, that a gas layer or high-density particles or bubbles are present, and the user can take subsequent action as needed.

[0079] In the embodiment described above, a first condensing lens 20 is provided between the light source 10 and the flow cell 30, and a second condensing lens 50 is provided between the flow cell 30 and the photodetector 60. However, the configuration may be such that one or both of these condensing lenses 20 and 50 are omitted. Furthermore, one or both of these condensing lenses 20 and 50 may be composed of multiple condensing lenses.

[0080] In the embodiment described above, particle size, number, refractive index, etc., are measured based on the output signal of the photodetector 60. However, the particle measuring device does not need to be able to measure all of these; it is sufficient if it can measure at least one of them.

[0081] Furthermore, the configurations and numerical values ​​mentioned in the explanation of the particle measuring device 1 are merely examples, and it goes without saying that they can be modified as appropriate when implementing the present invention. [Explanation of Symbols]

[0082] 1. Particle measuring device 10 light source 30 flow cells 60 Photodetectors 70 Arithmetic section 80 Control Unit

Claims

1. A flow cell into which the liquid sample is poured, A light source that emits irradiating light, A photodetector that detects scattered light generated by the action of the irradiated light in a detection region within the flow cell and outputs a detection signal corresponding to the intensity of the scattered light, A calculation unit measures at least one of the size, number, and refractive index of particles contained in the liquid sample based on the detection signal, determines the state of the liquid sample from the result of a predetermined calculation based on the detection signal, and provides a predetermined notification according to the determination result. Upon the aforementioned predetermined notification, a control unit that limits the irradiation light incident on the flow cell and A particle measuring device equipped with [the necessary components].

2. In the particle measuring device according to claim 1, The aforementioned arithmetic unit, A particle measuring device characterized by determining the presence or absence of high-density particles or bubbles in the liquid sample as the state of the liquid sample.

3. In the particle measuring device according to claim 1, The aforementioned arithmetic unit, A particle measuring device characterized by determining the presence or absence of a gas layer in the liquid sample as the state of the liquid sample.

4. In a particle measuring device according to any one of claims 1 to 3, The aforementioned arithmetic unit, A particle measuring device characterized in that it provides a predetermined notification to the control unit when the frequency of pulses with an intensity exceeding a certain value exceeds a predetermined threshold.

5. In a particle measuring device according to any one of claims 1 to 3, The aforementioned arithmetic unit, A particle measuring device characterized in that it provides a predetermined notification to the control unit when a predetermined statistical value, based on the pulse magnitude of the detection signal within a unit time, exceeds a predetermined threshold.

6. In a particle measuring device according to any one of claims 1 to 3, The aforementioned arithmetic unit, A particle measuring device characterized in that, with respect to the detection signal within a unit time, a predetermined statistical value is calculated by multiplying the pulse frequency by a weighting constant according to the pulse magnitude, and when the statistical value exceeds a predetermined threshold, the control unit is given the predetermined notification.

7. In a particle measuring device according to any one of claims 1 to 3, The aforementioned arithmetic unit, A particle measuring device characterized in that it provides a predetermined notification to the control unit when the change in the low-frequency component of the detection signal exceeds a predetermined threshold.

8. In a particle measuring device according to any one of claims 1 to 3, The control unit, A particle measuring device characterized in that, once the aforementioned predetermined notification ceases to be made and predetermined conditions are met, the restriction on the irradiation light incident on the flow cell is released.

9. The irradiation process involves emitting irradiation light, A detection step involves detecting scattered light generated by the action of the irradiated light in a detection area within a flow cell into which a liquid sample is poured, and outputting a detection signal of a magnitude corresponding to the intensity of the scattered light. A calculation step which measures at least one of the size, number, and refractive index of particles contained in the liquid sample based on the detection signal, determines the state of the liquid sample from the result of a predetermined calculation based on the detection signal, and provides a predetermined notification according to the determination result, A control step to limit the irradiation light incident on the flow cell, triggered by the aforementioned predetermined notification, A particle measurement method that includes [specific particle measurement method].

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