Particle measuring device and particle measuring method

Abstract

To make it possible to simultaneously perform particle size measurement and material discrimination at a lower cost.SOLUTION: The particle measuring system includes: a first light source and a second light source for irradiating a sample including particles of predetermined material with parallel light; an imaging unit that captures a scattered light image of the particles by the parallel light emitted from the first light source and a shadow image of the particles by the parallel light emitted from the second light source; and an image processing unit that discriminates the materials of the particles and calculates the particle size of the particles based on the correspondence between the scattered light intensity of the particle identified based on the scattered light image and the shadow size of the particle identified based on the shadow image and the theoretical correlation curve showing the theoretical value of the correspondence of the particle.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a particle measuring device and a particle measuring method. [Background technology]

[0002] Patent Document 1 relates to a technique for measuring the particle size distribution and material discrimination of a sample, and states that "We provide a particle group measurement device that is capable of estimating the particle size, average particle size, particle size dispersion, number of particles, and refractive index of particles to be measured without contact and in an extremely short time. The particle group measurement device creates a scattered light intensity theoretical value table in advance by preliminary calculation processing. Then, a first polarization camera and a second polarization camera are installed at positions of the scattering angle ±θ determined at the time of the preliminary calculation processing. The distance minimum value calculation unit calculates the measured first wavelength first scattered light intensity (I 1λ1 ), measured first wavelength second scattered light intensity (I 2λ1 ) and the measured second wavelength first scattered light intensity (I 1λ2 ), measured second wavelength second scattered light intensity (I 2λ2 ) is identified, and the refractive index m and standard deviation σ g , average particle size D g , and outputs the particle number n. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 096038 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, wavelength components corresponding to two light sources are extracted from the scattered light scattered by the particle group using color filters, and vertical polarization components and horizontal polarization components are extracted using a polarization camera. In addition, in the technology of the same document, the average particle size, standard deviation, particle number, and refractive index of the particle group are estimated using these four extracted values. However, the technology of the same document has a problem of high equipment costs because it uses two polarization cameras, which are more expensive than general CCD (Charge-Coupled Device) cameras.

[0005] The present invention has been made in consideration of the above problems, and has an object to simultaneously measure particle size and discriminate materials using a less expensive configuration. [Means for solving the problem]

[0006] The present application includes a plurality of means for solving at least part of the above problems, examples of which are as follows: A particle measuring device according to one aspect of the present invention for solving the above problems comprises a first light source and a second light source for irradiating parallel light onto a sample containing particles of a predetermined material, an imaging unit for capturing a scattered light image of the particles by the parallel light irradiated from the first light source and a shadow image of the particles by the parallel light irradiated from the second light source; Based on a distance relationship between a theoretical correlation curve for each material type, which indicates a theoretical value of a correspondence relationship between the scattered light intensity and the particle size of the particle for each predetermined scattering angle, and a measurement point, which indicates a correspondence relationship between the scattered light intensity and the shadow size of the particle and is specified based on the scattered light image and the shadow image, the theoretical correlation curve that is closer to the measurement point is specified, and based on the material type corresponding to the specified theoretical correlation curve, In addition to material discrimination, The particle sizes in the sample corresponding to the measurement points indicated by the identified theoretical correlation curve are and an image processing unit that calculates the particle size of the particles. Effect of the Invention

[0007] According to the present invention, it is possible to simultaneously measure particle size and discriminate materials with a less expensive configuration. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing an example of a schematic configuration of a particle measuring device according to a first embodiment. [Diagram 2] FIG. 2 illustrates an example of a hardware configuration of a processing device. [Diagram 3] FIG. 4 is a diagram showing an example of a cross section of a measuring portion. [Figure 4] FIG. 4 is a diagram showing an example of a cross-sectional configuration of a measurement unit during particle measurement. [Diagram 5] FIG. 13 is a diagram illustrating an example of a scattered light image. [Figure 6] FIG. 13 is a diagram showing an example of a shadow image. [Figure 7] FIG. 4 is a flow diagram showing an example of a particle measurement process. [Figure 8] FIG. 11 is a flow diagram showing an example of a captured image analysis process. [Figure 9] FIG. 1 is a diagram showing an example of a theoretical correlation curve. [Figure 10] FIG. 13 is a diagram showing an example of a schematic configuration of a particle measuring device according to a second embodiment. [Figure 11] FIG. 11 is a flow diagram showing an example of imaging and captured image analysis processing according to the second embodiment. [Figure 12] FIG. 1 is a diagram showing an example of a graph plotting theoretical correlation curves of samples with different refractive indices. [Figure 13] FIG. 1 is a diagram showing an example of a graph of scattered light intensity in two types of samples whose refractive index does not depend on wavelength. [Figure 14] FIG. 13 is a diagram showing an example of a schematic configuration of a particle measuring device according to a third embodiment. [Figure 15] FIG. 13 is a flow diagram showing an example of imaging and captured image analysis processing according to the third embodiment. [Figure 16] FIG. 13 is a flowchart illustrating an example of a refractive index estimation process according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, each embodiment of the present invention will be described with reference to the drawings.

[0010] First Embodiment

[0011] 1 is a diagram showing an example of a schematic configuration of a particle measuring device 100 in this embodiment. The particle measuring device 100 has a first light source 1, a second light source 2, a measuring unit 3, a microscope 4, an imaging unit 5, a light shielding plate 6, an image processing unit 7, a control unit 8, a light source switching unit 9, a storage unit 10, and a communication unit 11.

[0012] The first light source 1 is a device that irradiates parallel light A toward the sample flowing in the sample container of the measurement unit 3. For the first light source 1, a light emitting element such as an LED or a laser is used. When a laser is used, speckles may occur due to optical interference of particles contained in the sample. In that case, for example, a diffuser or speckle reducer may be installed to reduce such coherence.

[0013] As shown in the figure, the first light source 1 is disposed at a position substantially opposite to the microscope 4 across the measurement unit 3. Note that the term "substantially opposite" means that the parallel light A of the first light source 1 and the optical axis X of the microscope 4 do not coincide with each other, that is, the parallel light A of the first light source 1 and the optical axis X of the microscope 4 are not parallel but intersect with each other.

[0014] Specifically, the first light source 1 and the microscope 4 are disposed facing each other so that the parallel light A and the optical axis X intersect at a predetermined angle θth less than 90°. The parallel light A is set so that the distribution width of the parallelism with respect to the optical axis X is sufficiently smaller than the angle θth. The angle θth is preferably set in the range of, for example, 10° to 30°.

[0015] The beam size and shape of the parallel light A are designed so that only the light scattered by the sample particles in the sample container is imaged by the imaging section 5 of the microscope 4 (i.e., the components that do not scatter and travel straight ahead are prevented from entering the imaging section 5), and so that the entire field of view of the microscope 4 in the fluid flowing in the sample container is irradiated.

[0016] A light shielding plate 6 may be provided between the sample and the microscope 4 at the entrance of the microscope 4 in order to prevent unnecessary light (for example, light directly incident from the first light source 1) from entering the microscope 4. The light shielding plate 6 allows only light scattered by the particles of the sample within a predetermined angle range (light scattered at a predetermined angle θth or less) to enter the microscope 4.

[0017] The second light source 2 is a device that irradiates parallel light B toward the sample flowing in the sample container of the measurement unit 3. As with the first light source 1, the second light source 2 uses a light emitting element such as an LED or a laser.

[0018] The second light source 2 is disposed at a position substantially opposite to the microscope 4 across the measurement unit 3. The second light source 2 is set so that the optical axis of the parallel light B substantially coincides with the optical axis X of the microscope 4.

[0019] The measurement unit 3 is a device that irradiates a sample filled in a sample container held therein with parallel light A and parallel light B from a first light source 1 and a second light source 2, respectively. The measurement unit 3 will be described in detail later.

[0020] The microscope 4 is disposed at a position substantially opposite the first light source 1 and the second light source 2 across the measurement unit 3, and is a device that converts the incident light (parallel light A based on the first light source 1 and parallel light B based on the second light source 2) into an electrical signal by the imaging unit 5 to generate image information. The objective side of the microscope 4 is focused on the sample, and the optical system is designed so that the scattered light from each particle and the shadow of the particle can be imaged by the imaging unit 5 of the microscope 4.

[0021] Moreover, the microscope 4 is preset with a focal length and a lens diameter for suppressing the straight-line component of the parallel light A from entering the imaging unit 5. Specifically, the microscope 4 is set so that the focal length relative to the lens diameter is as long as possible in order to image a component of the scattered light that is approximately parallel to the optical axis X (a component whose angle from the optical axis X is equal to or smaller than a predetermined angle θth).

[0022] The imaging unit 5 is an imaging device (image sensor) that receives light incident on the microscope 4 and converts it into an electrical signal to capture a scattered light image and a shadow image. Specifically, when the imaging unit 5 is irradiated with parallel light A from the first light source 1, it receives the scattered light scattered by the particles in the sample container and captures a scattered light image. When the imaging unit 5 is irradiated with parallel light B from the second light source 2, it captures a shadow image showing the shadow of the particle in the sample container. The imaging unit 5 also outputs captured image information to the image processing unit 7.

[0023] The image processing unit 7, the control unit 8, the light source switching unit 9, the memory unit 10 and the communication unit 11 are functional units realized by a processing device provided in the particle measuring device 100 to execute various processes such as image processing, control and switching of the light source, storage of specified information, and communication with external devices.

[0024] Specifically, the image processing unit 7 is a functional unit that performs analysis processing of the image information acquired from the imaging unit 5. More specifically, the image processing unit 7 calculates the particle size distribution of particles contained in the sample and performs material discrimination based on the scattered light intensity and shadow size of the particles. The image processing unit 7 has a scattered light intensity processing unit 71 and a shadow size measurement processing unit 72.

[0025] The scattered light intensity processing unit 71 is a functional unit that calculates the intensity of scattered light of each particle contained in the scattered light image, using the scattered light image acquired from the imaging unit 5. Specifically, the scattered light intensity processing unit 71 acquires from the imaging unit 5 a scattered light image that captures scattered light produced when parallel light A, irradiated onto the sample from the first light source 1, is scattered by a particle at an angle equal to or smaller than a predetermined angle θth, and uses this to calculate the scattered light intensity of each particle.

[0026] The shadow size measurement processing unit 72 is a functional unit that calculates the size (magnitude) of each particle contained in the shadow image by using the shadow image acquired from the imaging unit 5. Specifically, the shadow size measurement processing unit 72 acquires from the imaging unit 5 a shadow image in which the shadow of each particle is captured by the parallel light B irradiated from the second light source 2 onto the sample, and uses this to calculate the size of each particle.

[0027] The image processing unit 7 acquires the calculation results calculated by the scattered light intensity processing unit 71 and the shadow size measurement processing unit 72, and outputs control instructions to the control unit 8 according to the analysis results of the captured image based on the calculation results. The image processing unit 7 may output information for monitoring the measurement status, etc. to an external display, etc.

[0028] The control unit 8 is a functional unit that controls the operation of the particle measuring device 100. Specifically, the control unit 8 outputs an instruction to the light source switching unit 9 to control the first light source 1 and the second light source 2. The control unit 8 also controls the operation of the measurement unit 3.

[0029] The control unit 8 may also output an alarm signal based on the result of the analysis processing of the image information by the image processing unit 7. The control unit 8 may also communicate information with an external device via the communication unit 11. In this case, the control unit 8 transmits, for example, the analysis result of the image information acquired from the image processing unit 7 (for example, the particle size distribution state or the result of material discrimination) via the communication unit 11 to the external device connected via a network such as a LAN (Local Area Network) or a public network.

[0030] The light source switching unit 9 is a functional unit that switches between lighting of the first light source 1 and the second light source 2 based on a control instruction obtained from the control unit 8.

[0031] The storage unit 10 is a functional unit that stores predetermined information. Specifically, the storage unit 10 stores theoretical correlation curves corresponding to the material types of particles contained in the sample. The theoretical correlation curves will be described in detail later.

[0032] The communication unit 11 is a functional unit that communicates information with an external device. For example, the communication unit 11 transmits information indicating an analysis result of image information to the external device. The communication unit 11 also acquires predetermined information (for example, an acquisition request for the analysis result) from the external device.

[0033] 2 is a diagram showing an example of a hardware configuration of a processing device that realizes an image processing unit 7, a control unit 8, a light source switching unit 9, a storage unit 10, and a communication unit 11. As shown in the figure, the processing device has an arithmetic unit 110, a main storage unit 120, an auxiliary storage unit 130, a communication unit 140, and a bus 150 that electrically interconnects these units.

[0034] The arithmetic device 110 may be a processor such as a central processing unit (CPU) or a graphics processing unit (GPU), or may be another semiconductor device that executes a predetermined process. The main memory device 120 is a memory device such as a random access memory (RAM) or a read only memory (ROM).

[0035] The auxiliary storage device 130 is a non-volatile storage device capable of storing digital information, such as a so-called hard disk drive, a solid state drive (SSD), or a flash memory.

[0036] The communication device 140 is a device that performs wired communication via a network cable, or a device that performs wireless communication via an antenna. The communication device 140 performs information communication with other devices connected to the network N.

[0037] An example of the hardware configuration of the processing device of the particle measuring device 100 has been described above.

[0038] The image processing unit 7, the control unit 8, and the light source switching unit 9 are realized by a program that causes the arithmetic device 110 to perform processing. This program is stored in the main storage device 120 or the auxiliary storage device 130, and is loaded onto the main storage device 120 when the program is executed, and is executed by the arithmetic device 110. The storage unit 10 is realized by the main storage device 120, the auxiliary storage device 130, or a combination of these. The communication unit 11 is realized by the communication device 140.

[0039] The configurations, functions, processing units, processing means, etc. of the processing device may be realized in part or in whole by hardware, for example by designing them as integrated circuits. The configurations and functions may also be realized in software by a processor interpreting and executing a program that realizes each function. Information such as the programs, tables, and files that realize each function may be stored in a storage device such as a memory, a hard disk, or an SSD, or in a recording medium such as an IC card, an SD card, or a DVD.

[0040] Next, the detailed configuration of the measurement unit 3 will be described.

[0041] 3 is a diagram showing an example of a cross section of the measurement unit 3. As shown in the figure, the measurement unit 3 includes a sample container 31 having openings at the top and bottom ends, a pipe 32 connected to the opening of the sample container 31, a first valve 33 (see FIG. 1) for controlling the injection (flow) of the sample into the sample container 31 through the pipe 32, an irradiation window drive unit 34 provided on the wall surface of the sample container 31, an irradiation window 35 provided at one end of the irradiation window drive unit 34, an observation window 36 provided on the wall surface of the sample container 31 facing the irradiation window 35, a nozzle 37 whose discharge port is located inside the sample container 31, a tube 38 connected to the nozzle 37, and a second valve 39 connected to the tube 38.

[0042] The first valve 33 has an upstream valve and a downstream valve, and when the upstream valve is opened, the sample is injected into the sample container 31. When the downstream valve is opened, the sample in the sample container 31 is discharged to the outside of the measurement unit 3. By controlling the opening and closing of the upstream valve and the downstream valve, the flow of the sample in the sample container 31 can be controlled, and the movement of particles can be suppressed when imaging by the imaging unit 5.

[0043] Furthermore, the tube 38 is connected to a cleaning liquid storage container, and a cleaning liquid 41 (see FIG. 1) in the cleaning liquid storage container is discharged into the sample container 31 by a pump 40 (see FIG. 1).

[0044] The second valve 39 includes an irradiation window side cleaning valve and an observation window side cleaning valve. When the irradiation window side cleaning valve is opened, a cleaning liquid 41 is discharged onto the irradiation window 35, and when the observation window side cleaning valve is opened, the cleaning liquid 41 is discharged onto the observation window 36.

[0045] The sample container 31 is sealed to prevent the intrusion of outside air from the outside, and functions as a sample holding area capable of holding a sample or a cleaning solution 41 therein.

[0046] The sample container 31 is connected to a production line (not shown) via, for example, a pipe 32, and the sample extracted from the production line is directly injected into the sample container 31. Note that the sample container 31 may be installed at a location remote from the production line without being directly connected thereto.

[0047] The cleaning liquid 41 is different from the sample and is a liquid that does not scratch the window, such as water or a sample from which solid components have been removed. A liquid with a cleaning effect, such as water to which a dispersant or surfactant has been added, may also be used. This improves the wettability of the window and makes it possible to suppress adhesion of the sample or air bubbles to the window. A slurry containing low-hardness particles, such as resin particles, that do not scratch the window may also be used for the cleaning liquid 41. The low-hardness particles collide with particles that are strongly attached to the window, thereby removing such particles.

[0048] The observation window 36 is a window for observing the sample in the sample container 31 by the microscope 4. The observation window 36 is transparent to at least the wavelengths of the parallel light A and the parallel light B. The optical system is set so that the focal point of the microscope 4 is located near the surface of the observation window 36 on the sample side.

[0049] The irradiation window 35 is a window for irradiating the parallel light A and the parallel light B into the sample container 31. The irradiation window 35 is provided in the sample container 31 so as to face the observation window 36. The irradiation window 35 is transparent to at least the wavelengths of the parallel light A and the parallel light B.

[0050] The irradiation window drive unit 34 is a drive mechanism that drives the irradiation window 35 in the direction of the optical axis X of the microscope 4. Specifically, the irradiation window drive unit 34 adjusts the distance between the irradiation window 35 and the observation window 36 by driving the irradiation window 35 to move closer to or away from the observation window 36. The irradiation window drive unit 34 may be moved manually by a user.

[0051] 3 shows the position during cleaning. At this time, the outlet of the nozzle 37 is directed toward the irradiation window 35 and the observation window 36, respectively, and the cleaning liquid 41 is discharged toward the irradiation window 35 and the observation window 36.

[0052] A seal mechanism is provided between the irradiation window drive unit 34 and the sample container 31 to prevent outside air from entering the sample container 31 and to enable movement of the irradiation window drive unit 34. The seal mechanism may be an O-ring or a diaphragm.

[0053] The outlet of the nozzle 37 is disposed upstream of the irradiation window 35 and the observation window 36 in the direction in which the sample flows. As a result, the cleaning liquid 41 discharged from the nozzle 37 is discharged from the sample container 31 together with the sample.

[0054] In order to prevent particles from overlapping each other when the sample in the sample container 31 is imaged by the microscope 4, the sample is subjected to dilution and dispersion treatment as necessary.

[0055] Moreover, the parallel light A and the parallel light B are incident from the irradiation window 35 and irradiated to the sample. Of the parallel light A, the component that travels straight without being scattered by particles in the sample passes through the observation window 36 and passes outside the measurement unit 3. The imaging unit 5 of the microscope 4 images, via the observation window 36, the component of the parallel light A that is scattered in the direction of the optical axis X of the microscope 4 by particles in the sample (scattered light scattered at a scattering angle θth or less). Also, the imaging unit 5 of the microscope 4 images, via the observation window 36, the component of the parallel light B that travels straight without being scattered by particles in the sample.

[0056] The observation window 36 is desirably set to a sufficient size so that all of the linear components of the parallel light A can pass through it. This is to prevent light reflected and scattered inside the sample container 31 from entering the microscope 4, which would deteriorate the signal-to-noise ratio (S / N) of the captured image information.

[0057] In order to suppress diffuse reflection of light within the sample container 31, the inner wall of the sample container 31 may be coated with a light absorbing agent or a light absorbing member may be placed inside the sample container 31.

[0058] 4 is a diagram showing an example of the cross-sectional configuration of the measurement unit 3 during particle measurement. As shown in the figure, the irradiation window 35 moves from the position during cleaning toward the observation window 36 in response to the movement of the irradiation window drive unit 34. Therefore, the distance between the irradiation window 35 and the observation window 36 is narrowed, the thickness of the microscope 4 in the optical axis X direction is reduced, and the area (volume) of the sample irradiated with the parallel light A and the parallel light B is reduced.

[0059] This prevents particles from overlapping when the sample is imaged, and suppresses the effects of scattered light from particles outside the focal range of the microscope 4. In addition, by bringing the irradiation window 35 and the observation window 36 as close as possible, the movement of particles is suppressed, and blurring during imaging and positional deviation due to particle movement when switching the light source can be suppressed.

[0060] After the imaging by the microscope 4 is completed, the irradiation window 35 is moved in a direction away from the observation window 36 by the operation of the irradiation window drive unit 34. After the distance between the irradiation window 35 and the observation window 36 increases, the sample in the sample container 31 is replaced.

[0061] The measurement unit 3 is assumed to include an operation control mechanism (not shown) for operating each of the first valve 33, the irradiation window driving unit 34, the second valve 39, and the pump 40. The operation control mechanism is, for example, a drive motor for opening and closing the first valve 33 and the second valve 39 and for moving the irradiation window driving unit 34 (movement in the optical axis X direction), and a switch for switching the pump 40 ON / OFF. These operation control mechanisms perform predetermined operations, such as opening and closing the first valve 33 and the second valve 39, moving the irradiation window driving unit 34, and turning the pump 40 ON / OFF, based on control by the control unit 8 (for example, control by change in applied voltage to the operation control mechanism).

[0062] FIG. 5 is a diagram relating to an example of a scattered light image captured by the imaging unit 5. Specifically, FIG. 5(a) is a diagram showing an example of a scattered light image captured of an alumina particle. FIG. 5(b) is a diagram showing a schematic diagram of the scattered light image. Note that the schematic diagram of FIG. 5(b) is a diagram for explaining the scattered light image, and does not correspond to the scattered light image of FIG. 5(a).

[0063] As shown in Figures 5(a) and 5(b), each point in the scattered light image represents scattered light from one particle. The scattered light intensity processing unit 71 uses such scattered light images to identify each particle that is the measurement target, and obtains the scattered light intensity of each particle.

[0064] Specifically, the scattered light intensity processing unit 71 identifies a pixel group corresponding to each particle included in the scattered light image, and obtains the value of the pixel with the highest luminance value in the pixel group as the scattered light intensity of the particle. The scattered light intensity processing unit 71 may also determine the peak intensity of a curve obtained by fitting with a Gaussian distribution or the like as the scattered light intensity.

[0065] When the scattered light intensity falls outside the luminance range of the captured image, the output of the first light source 1, the exposure time of the image capturing section 5, or the gain of the image capturing section 5 may be adjusted.

[0066] Furthermore, if the scattered light intensity differs significantly for each particle and the scattered light intensity of all particles does not fall within the luminance range of the scattered light image, images may be captured multiple times by changing, for example, the output of the first light source 1, or the exposure time of the image capture unit 5, or the gain of the image capture unit 5. Note that such various adjustments may be performed by the image processing unit 7 analyzing the captured image and outputting instructions to the control unit 8 according to the analysis results.

[0067] 6 is a diagram showing an example of a shadow image. Each point in the figure represents the shadow of each particle. The shadow size measurement processing unit 72 uses the shadow image captured by the imaging unit 5 to identify each particle and obtain the shadow size of each particle.

[0068] Specifically, the shadow size measurement processor 72 obtains the area of ​​the pixel group corresponding to each particle included in the shadow image as the shadow area of ​​the particle. In addition, the shadow area may be calculated by converting the area into a circle-equivalent diameter, assuming that the particle shape is circular.

[0069] The size of the particle shadow obtained in the shadow image is larger than the actual particle shape due to the diffraction of light by the lens. The effect of diffraction is inversely proportional to the numerical aperture of the lens, and correction is required when a lens with an insufficient numerical aperture is used. In that case, the diffraction profile is given by equation (1), so the true shadow shape can be estimated by performing fitting using equation (1).

[0070]

number

[0071] In the formula (1), y represents the diffracted light intensity, x represents the diffraction radius, and j1 represents the Bessel function.

[0072] [Explanation of operation] Next, the particle measurement process will be described.

[0073] 7 is a flow diagram showing an example of a particle measurement process. First, the operation control mechanism (not shown) of the measurement unit 3 performs the following operations based on the control of the control unit 8. Specifically, the operation control mechanism opens the first valve 33 (upstream valve and downstream valve) and introduces (injects) the sample into the sample container 31 (step S10). After a predetermined time has elapsed, when the inside of the sample container 31 is replaced with the sample, the operation control mechanism closes the first valve 33 (upstream valve and downstream valve) to stop the introduction of the sample (step S20).

[0074] Moreover, the operation control mechanism moves the irradiation window drive unit 34 so that the irradiation window 35 is at the measurement position shown in FIG. 4 (step S30).

[0075] Furthermore, the particle measuring device 100 irradiates the sample with parallel light A from the first light source 1 (step S40). Specifically, the light source switching unit 9 causes the first light source 1 to irradiate the parallel light A based on an instruction from the control unit 8.

[0076] Furthermore, the imaging unit 5 captures a scattered light image (step S50). Specifically, the imaging unit 5 captures the scattered light image by receiving the scattered light that is generated when the parallel light A irradiated to the sample is scattered by the particles at an angle equal to or smaller than a predetermined angle θth. The imaging unit 5 outputs image information of the captured scattered light image to the image processing unit 7.

[0077] Furthermore, the particle measuring device 100 irradiates the sample with parallel light B from the second light source 2 (step S60). Specifically, the light source switching unit 9 causes the second light source 2 to irradiate the sample with parallel light B based on an instruction from the control unit 8.

[0078] Furthermore, the imaging unit 5 captures a shadow image (step S70). Specifically, the imaging unit 5 captures an image of the shadow of each particle caused by the parallel light B irradiated onto the sample. The imaging unit 5 outputs image information of the captured shadow image to the image processing unit 7.

[0079] Furthermore, the imaging section 5 performs an analysis process of the captured image using the scattered light image and the shadow image acquired from the imaging section 5 (step S80). The analysis process of the captured image by the image processing section 7 will be described in detail later.

[0080] Next, the operation control mechanism opens the downstream valve of the first valve 33 (step S90), turns on the pump 40, and opens the second valve 39 (in this case, both the valve for cleaning the irradiation window side and the valve for cleaning the observation window side) to begin ejecting cleaning liquid into the sample container 31 (step S100).

[0081] Moreover, the operation control mechanism moves the irradiation window drive unit 34 so that the irradiation window is at the cleaning position shown in FIG. 3 (step S110).

[0082] After the irradiation window 35 has moved to the cleaning position, the operation control mechanism closes the observation window side cleaning valve and discharges a cleaning liquid onto the irradiation window 35 for a predetermined period of time to remove adhering particles (step S120).

[0083] Next, the operation control mechanism opens the observation window side cleaning valve, closes the irradiation window side cleaning valve, and discharges cleaning liquid into the observation window 36 for a predetermined time to remove adhering particles (step S130). Thereafter, the operation control mechanism turns off the pump 40, closes the observation window side cleaning valve to stop discharging the cleaning liquid (step S140), and closes the downstream valve (step S150) to fill the sample container 31 with cleaning liquid. If continuous measurement is to be continued (Yes in step S160), the particle measuring device 100 waits until the next measurement timing (S170) and starts the process from step S10 at the next measurement. On the other hand, if continuous measurement is not to be continued (No in step S160), the particle measuring device 100 ends the particle measurement process.

[0084] The particle measurement process has been described above.

[0085] Next, the analysis process of the captured image executed by the particle measuring device 100 will be described.

[0086] 8 is a flow diagram showing an example of the captured image analysis process, which corresponds to the process of step S80 in FIG.

[0087] When the process starts, the scattered light intensity processing unit 71 calculates the scattered light intensity of each particle using the scattered light image acquired from the imaging unit 5 (step S200). Specifically, the scattered light intensity processing unit 71 identifies each particle included in the scattered light image. In addition, for each identified particle i, the scattered light intensity processing unit 71 calculates the position (x1i, y1i) in the scattered light image and the scattered light intensity I1i based on the luminance value.

[0088] Next, the shadow size measurement processing unit 72 calculates the shadow size of each particle using the shadow image acquired from the imaging unit 5 (step S210). Specifically, the shadow size measurement processing unit 72 identifies each particle included in the shadow image. In addition, the shadow size measurement processing unit 72 calculates the position (x2j, y2j) and the shadow size (size of the shadow) D2j in the shadow image for each identified particle j.

[0089] Next, the image processing unit 7 identifies particles that match in the scattered light image and the shadow image (step S220). Specifically, the image processing unit 7 compares the positional relationship between each particle i obtained from the scattered light image and particle j obtained from the shadow image, and determines whether or not the particles are the same in both pieces of image information.

[0090] More specifically, when the distance between the identified particle i and particle j is equal to or less than a predetermined threshold, the image processing unit 7 determines that the two particles are the same particle, thereby identifying particles that match in the scattered light image and the shadow image.

[0091] The reason why the judgment condition is that the distance between particle i and particle j is equal to or less than a predetermined threshold is to take into consideration the fact that a time difference when switching the light source can cause a shift in the position of particle i in the scattered light image and the position of the corresponding particle j in the shadow image.

[0092] Next, the image processing unit 7 generates a graph showing the correspondence between the scattered light intensity and the shadow size (corresponding to the particle size described below) for each particle determined to be the same particle (step S230). Specifically, the image processing unit 7 assigns a corresponding scattered light intensity I1i and a shadow size D2j to each particle determined to be the same. Furthermore, based on the assigned scattered light intensity and shadow size, the image processing unit 7 plots the measurement points of each particle on a graph with the scattered light intensity on the vertical axis and the shadow size on the horizontal axis.

[0093] At this time, the image processing unit 7 also obtains from the storage unit 10 a predetermined number (for example, two) of theoretical correlation curves corresponding to the expected predetermined sample and scattering angle (θth), and draws them superimposed on the graph.

[0094] The theoretical correlation curve corresponding to each particle sample can be calculated based on the Mie scattering theory. The scattered light intensity of each sample depends on the particle size, the refractive index of the particle, and the scattering angle. That is, samples with different refractive indexes have different correlations between particle size and scattered light intensity. Therefore, the theoretical correlation curves of samples with different refractive indexes can be expressed as curves with different shapes. Therefore, based on the Mie scattering theory, the refractive index corresponding to each sample can be used as an input parameter to determine the scattered light intensity for each particle size. In this way, a theoretical correlation curve can be generated as a theoretical value that indicates the correspondence between the scattered light intensity and particle size (corresponding to the shadow size) for each material type of each sample.

[0095] FIG. 9 is a diagram showing an example of a theoretical correlation curve corresponding to a predetermined scattering angle (θth) for a predetermined material (alumina particles and silica particles in this example). Specifically, FIG. 9(a) is a diagram showing a theoretical correlation curve of alumina particles and silica particles when the scattering angle is 10°. FIG. 9(b) is a diagram showing a theoretical correlation curve of alumina particles and silica particles when the scattering angle is 45°. FIG. 9(c) is a diagram showing a theoretical correlation curve of alumina particles and silica particles when the scattering angle is 90°. FIG. 9(d) is a diagram showing a theoretical correlation curve of alumina particles and silica particles when the scattering angle is 170°. In addition, the vertical axis of these graphs indicates the scattered light intensity, and the horizontal axis indicates the particle size corresponding to the shadow size.

[0096] As shown in Figures 9(a) to 9(d), the theoretical correlation curves of materials with different refractive indices are expressed as curves with different shapes. In addition, even for the same sample, if the scattering angle is different, the theoretical correlation curves are expressed as curves with different shapes.

[0097] When the measurement points of each particle are plotted on a graph that depicts the theoretical correlation curves of the predicted material types, the measurement points are plotted on or near the corresponding theoretical correlation curves. Therefore, if the material types and refractive indices contained in a sample can be predicted, the particles at each measurement point can be distinguished as to which material they are by drawing the theoretical correlation curves corresponding to those materials on a graph. The specific process of material discrimination will be described later.

[0098] In this embodiment, the theoretical correlation curves corresponding to various materials and scattering angles are stored in advance in the storage unit 10, but such theoretical correlation curves may be generated at the processing timing of step S230.

[0099] Next, the image processor 7 performs calculation of particle size distribution and material discrimination based on a comparison between the theoretical correlation curve drawn on the graph and the measurement points (step S240). Specifically, the image processor 7 calculates the shortest distance between each measurement point plotted on the graph and the theoretical correlation curve corresponding to a given material type and scattering angle (θth) drawn on the graph.

[0100] More specifically, when the two types of theoretical correlation curves shown in FIG. 9(a) are plotted on the graph, the image processing unit 7 calculates all of the shortest distances from each of the plotted measurement points to each of the theoretical correlation curves.

[0101] Furthermore, the image processing unit 7 identifies a theoretical correlation curve corresponding to the smallest shortest distance among the calculated shortest distances. Then, the image processing unit 7 identifies a sample corresponding to the identified theoretical correlation curve as a sample of the measured particle. In this manner, the image processing unit 7 performs material discrimination of the measured particle (sample).

[0102] However, the method of material discrimination is not limited to this. For example, the image processor 7 may obtain an average value of the shortest distance from each measurement point to each theoretical correlation curve, and identify the material corresponding to the theoretical correlation curve with the smaller average value as the material of the measured particle.

[0103] The image processor 7 also identifies the shadow size corresponding to the point on the theoretical correlation curve (in this case, the theoretical correlation curve corresponding to the sample of the measured particle) closest to each measurement point from the graph, and identifies the particle size corresponding to the identified shadow size as the particle size of the measured particle at each measurement point.

[0104] Then, the image processing unit 7 calculates the particle size distribution of the identified particles of the sample based on the number of measurement points and the identified particle size.

[0105] After the image processing unit 7 has completed the material discrimination and calculated the particle size distribution, the process of this flow ends.

[0106] The captured image analysis process has been described above.

[0107] Such a particle measuring device can simultaneously perform particle size measurement and material discrimination with a less expensive configuration. In particular, the particle measuring device can discriminate which material each measurement point is made of by using a theoretical correlation curve corresponding to each material. In addition to material discrimination, the particle measuring device can also calculate the particle size distribution of particles corresponding to each sample.

[0108] In addition, since the scattered light intensity increases as the scattering angle decreases, it is desirable to increase the measurement sensitivity by making the scattering angle θth as small as possible during measurement.

[0109] In addition, as shown in Figures 9(a), (c), and (d), the theoretical correlation curves of silica particles and alumina have several intersecting points depending on the scattering angle, and it is difficult to perform material discrimination near these points. In that case, as shown in Figure 9(b), material discrimination can be performed by setting the scattering angle to 45° and using a theoretical correlation curve with no intersecting points.

[0110] In addition, the optimal scattering angle differs depending on the type of material and the expected range of particle sizes. Therefore, a mechanism may be provided that allows the irradiation angle of the parallel light A from the first light source 1 to be adjusted so that the scattering angle can be changed appropriately.

[0111] In addition, the theoretical correlation curve shown in Fig. 9 is for cases where the particle shape is spherical, and for non-spherical particles or particles with uneven surfaces, the scattered light intensity is measured with variation centered on the theoretical correlation curve. Therefore, by determining the variance and standard deviation of the shortest distance between the theoretical correlation curve and the measurement point, the particle shape and the degree of unevenness of the particle surface can be evaluated.

[0112] Furthermore, in the particle measuring device 100, particles adhering to and remaining on the irradiation window 35 and the observation window 36 can be easily removed by a cleaning mechanism using the nozzle 37.

[0113] In addition, in the present embodiment, an example of an optical system in which the linear component of the parallel light A does not enter the imaging unit 5 has been shown, but instead, a polarizing filter may be placed between the sample and the imaging unit 5, and a polarized light source may be used as the first light source 1. Examples of polarized light sources include a laser light source having polarized light, or a combination of a polarizing filter and the first light source 1. Such a polarized light source can also prevent the linear component of the parallel light A from entering the imaging unit 5.

[0114] In addition, in this embodiment, an example has been shown in which each nozzle 37 is arranged at the position shown in FIG. 3 and the cleaning liquid 41 is alternately ejected, but each nozzle 37 may be arranged at a position where the ejected cleaning liquid 41 does not collide with each other, so that the cleaning liquid 41 can be ejected simultaneously from each nozzle 37.

[0115] In addition, in this embodiment, an example has been shown in which the cleaning liquid 41 is stored in a cleaning liquid storage container in the measurement unit 3 and supplied, but the cleaning liquid 41 may be supplied from a supply utility outside the measurement unit 3.

[0116] In addition, in this embodiment, an example has been shown in which the flow of the sample is temporarily suppressed during imaging based on the movement of the irradiation window driving unit 34. However, it is also possible to image the sample while keeping it flowing by switching the light source according to the particle movement speed, or by making the imaging time sufficiently short.

[0117] Second Embodiment 10 is a diagram showing an example of a schematic configuration of a particle measuring device 100 according to a second embodiment. As shown in the figure, the particle measuring device 100 according to this embodiment differs in that it has a third light source 12, a mirror 13, and a wavelength selection mirror 14 instead of the second light source 2 of the first embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and repeated explanations will be omitted.

[0118] The third light source 12 has an output wavelength different from that of the first light source 1, and irradiates parallel light C toward a sample held by the measurement device via a mirror 13 and a wavelength selection mirror 14. The optical axis of the parallel light C is set so as to substantially coincide with the optical axis of the parallel light A from the first light source 1. For such a third light source 12, a light emitting element such as an LED or a laser is used.

[0119] The wavelength selection mirror 14 has the property of transmitting the light from the first light source 1 and reflecting the light from the third light source 12 .

[0120] The imaging unit 5 separates the incident light into a plurality of wavelength regions and captures images corresponding to each wavelength region. For example, a color CCD that separates into RGB is used for such imaging unit 5.

[0121] The wavelengths of the first light source 1 and the third light source 12 are made to correspond to the respective spectral wavelength ranges of the imaging unit 5, and the imaging unit 5 captures a scattered light image in which the parallel light from each light source is scattered by the particles of the sample. Specifically, when the imaging unit 5 is a color CCD that disperses light into RGB, the imaging unit 5 sets the output wavelength of the first light source 1 to red, and captures the scattered light caused by this red light with R pixels. The imaging unit 5 also sets the output wavelength of the third light source 12 to blue, and captures the scattered light caused by this blue light with B pixels.

[0122] 11 is a flow diagram showing an example of imaging and image analysis processing according to this embodiment. Note that the particle measurement processing is basically the same as in the first embodiment, and therefore a description thereof will be omitted.

[0123] When the process starts, the particle measuring device 100 causes the first light source 1 to irradiate the sample with parallel light A, and causes the imaging unit 5 to capture an image of scattered light scattered at a predetermined scattering angle θth or less (S300).

[0124] Next, the scattered light intensity processing unit 71 calculates the scattered light intensity of each particle based on the parallel light A (step S310). Specifically, similar to step S200, the scattered light intensity processing unit 71 identifies each particle from the scattered light image, and calculates, for each identified particle i, the position (x1i, y1i) in the scattered light image and the scattered light intensity I1i based on the luminance value.

[0125] Next, the particle measuring device 100 switches the light source via the control unit 8 and the light source switching unit 9, and causes the third light source 12 to irradiate parallel light C onto the sample, thereby capturing an image of the scattered light scattered at a predetermined scattering angle θth or less by the imaging unit 5 (S320).

[0126] Next, the scattered light intensity processing unit 71 calculates the scattered light intensity of each particle based on the parallel light C (step S330). Specifically, similar to step S200, the scattered light intensity processing unit 71 identifies each particle from the scattered light image, and calculates, for each identified particle j, the position (x2j, y2j) in the scattered light image and the scattered light intensity I2j based on the luminance value.

[0127] Next, image processing unit 7 identifies particles that match in both captured scattered light images (step S340). Specifically, image processing unit 7 compares the positional relationship of each particle i and j obtained from both scattered light images, determines whether or not the particles are the same in both image information, and identifies particles that match.

[0128] Next, the image processing unit 7 generates a graph showing the correspondence relationship between the scattered light intensity I1i and the scattered light intensity I2j in both scattered light images for each particle determined to be the same particle (step S350). Specifically, the image processing unit 7 assigns the corresponding scattered light intensity I1i and scattered light intensity I2j to each particle determined to be the same. Furthermore, based on the assigned scattered light intensities, the image processing unit 7 plots the measurement points of each particle on a graph with the scattered light intensity I1i on the vertical axis and the scattered light intensity I2j on the horizontal axis.

[0129] At this time, the image processing unit 7 also obtains from the storage unit 10 a predetermined number (for example, two) of theoretical correlation curves corresponding to the expected predetermined sample and scattering angle (θth), and draws them superimposed on the graph.

[0130] FIG. 12 is a diagram showing an example of a graph plotting theoretical correlation curves of two types of samples A and B with different refractive indices. Specifically, FIG. 12(a) to FIG. 12(f) are diagrams plotting theoretical correlation curves of samples A and B when the scattering angles are 5°, 10°, 20°, 45°, 90°, and 170°, respectively. The vertical axis of these graphs indicates the scattered light intensity when irradiated with light having a wavelength of 635 nm, and the horizontal axis indicates the scattered light intensity when irradiated with light having a wavelength of 455 nm. The refractive index of sample A is 1.45 regardless of wavelength, and the refractive index of sample B is 1.5 when the wavelength is 455 nm and 1.45 when the wavelength is 635 nm. Each figure shows the results for particle sizes from 0.1 μm to 2 μm.

[0131] As mentioned above, the scattered light intensity depends on the refractive index of the particles, and therefore, based on the Mie scattering theory, sample A and sample B can be expressed as theoretical correlation curves with different shapes. In addition, as shown in Figures 12(a) to 12(f), it can be seen that even the same sample can be expressed as theoretical correlation curves with different shapes if the scattering angle is different.

[0132] When the measurement points of each particle are plotted on a graph that depicts the predicted theoretical correlation curve of the sample, the measurement points are plotted on or near the corresponding theoretical correlation curve. Therefore, if the material types and refractive indices contained in a sample can be predicted, it is possible to distinguish which material the particles at each measurement point are made of by plotting the theoretical correlation curves corresponding to those materials on a graph.

[0133] In addition, when calculating the theoretical correlation curve used in this embodiment, it is important to take into consideration the wavelength dependency of the refractive index of the particles. The wavelength dependency of the refractive index will be described below.

[0134] FIG. 13 shows an example of a graph of scattered light intensity for two types of samples (sample A and sample C) whose refractive index does not depend on wavelength. The vertical axis shows the scattered light intensity when irradiated with light of a wavelength of 635 nm, and the horizontal axis shows the scattered light intensity when irradiated with light of a wavelength of 455 nm. The refractive index of sample A is 1.45 regardless of wavelength, and the refractive index of sample C is 1.5 regardless of wavelength. The scattering angle is set to 10°, and the particle size is shown to be 0.1 μm to 2 μm. As shown in the figure, there is a slight difference between the curves of sample A and sample C, but the difference is clearly smaller than the difference between the curves shown in FIG. 12. This suggests that the wavelength dependency of the refractive index of the particles contributes greatly to material discrimination. Since many materials have more or less wavelength dependency in the refractive index, it is important to input the refractive index taking this into consideration when calculating the theoretical correlation curve.

[0135] Next, the image processor 7 performs calculation of particle size distribution and material discrimination in the same manner as in step S240 (step S360). Specifically, the image processor 7 performs material discrimination based on the shortest distance between each measurement point plotted on the graph and a theoretical correlation curve corresponding to a given material type and scattering angle (θth) drawn on the graph.

[0136] In addition, the image processing unit 7 calculates the particle size at each measurement point based on the relationship between the scattered light intensity of each wavelength corresponding to a point on the theoretical correlation curve that is closest to each measurement point, the refractive index of the material, and the scattering angle, which is a theoretical correlation curve corresponding to the identified material.

[0137] Then, the image processing unit 7 calculates the particle size distribution of the particles of the specified material based on the number of each measurement point and the specified particle size.

[0138] After the image processing unit 7 has completed the material discrimination and calculated the particle size distribution, the process of this flow ends.

[0139] The imaging and captured image analysis process according to this embodiment has been described above.

[0140] Such a particle measuring device can simultaneously perform particle size measurement and material discrimination with a less expensive configuration. In particular, the particle measuring device according to this embodiment can calculate the particle size distribution of particles corresponding to each material as well as material discrimination by using scattered light images obtained by capturing scattered light of different wavelengths, even for a sample containing microparticles that cannot be detected as a shadow image.

[0141] As shown in Figures 12(a) to 12(f), the theoretical correlation curves of sample A and sample B become more complex as the scattering angle increases, and intersecting points occur. It is difficult to perform material discrimination in the vicinity of such intersecting points. Therefore, it is desirable to set the scattering angle so as to minimize such intersecting points.

[0142] In addition, in this embodiment, an example has been shown in which imaging is performed by switching between the first light source 1 and the third light source 12, but it is also possible to simultaneously irradiate parallel light from these two light sources and capture scattered light intensities corresponding to the respective wavelengths by separating them into an R image and a B image in the imaging unit 5. In this way, imaging can be performed simultaneously without switching between the light sources, thereby shortening the measurement time.

[0143] In addition, in this embodiment, an example has been shown in which the optical axes of the parallel light A and the parallel light C are substantially aligned using the mirror 13 and the wavelength selection mirror 14, but for example, a configuration in which the optical axes are shifted without using the mirror 13 may be used. Also, the angles of incidence of each of the parallel light beams on the sample may be made different.

[0144] <Third embodiment> FIG. 14 is a diagram showing an example of a schematic configuration of a particle measuring device 100 according to the third embodiment. The particle measuring device 100 according to this embodiment is characterized in that it can expand the range of measurable particle sizes. For example, in the above-mentioned second embodiment, even for microparticles that cannot be detected as a shadow image like the first embodiment, the particle size can be measured by using a scattered light image by parallel light of different wavelengths. On the other hand, in the analysis process of the captured image according to the second embodiment, when the particle size becomes large, the theoretical correlation curves between samples may approach or cross, making material discrimination difficult. Therefore, in the third embodiment, a particle measuring device 100 that can expand the measurable range of particle sizes by using the analysis process of the captured image according to the first embodiment and the second embodiment in combination will be described. Note that the same reference numerals are attached to the same configurations as those in the first embodiment and the second embodiment, and repeated explanations will be omitted.

[0145] As shown in the figure, the particle measuring device 100 of this embodiment has a first light source 1 and a second light source 2 of the first embodiment, and a third light source 12, a mirror 13 and a wavelength selection mirror 14 of the second embodiment.

[0146] FIG. 15 is a flow diagram showing an example of imaging and captured image analysis processing according to this embodiment.

[0147] When this process is started, the particle measuring device 100 irradiates the sample with parallel light A from the first light source 1, and captures an image of the scattered light scattered at an angle equal to or smaller than a predetermined angle θth with the imaging section 5 (S400). Similarly to step S200, the scattered light intensity processing section 71 calculates, for each particle i identified from the scattered light image, the position (x1i, y1i) in the scattered light image and the scattered light intensity I1i based on the luminance value (S410).

[0148] Next, the particle measuring device 100 switches the light source via the control unit 8 and the light source switching unit 9, and causes the third light source 12 to irradiate the sample with parallel light C, thereby causing the imaging unit 5 to capture an image of scattered light scattered at a predetermined scattering angle θth or less (S420). Similarly to step S200, the scattered light intensity processing unit 71 calculates, for each particle j identified from the scattered light image, the position (x2j, y2j) in the scattered light image and the scattered light intensity I2j based on the luminance value (S430).

[0149] Next, the particle measuring device 100 switches the light source via the control unit 8 and the light source switching unit 9, and captures a shadow image of each particle by irradiating the sample with parallel light B from the second light source 2 (S440). Similarly to step S210, the shadow size measurement processing unit 72 calculates the position (x3k, y3k) in the shadow image and the shadow size (magnitude of the shadow) D3k for each particle k identified from the shadow image (step S450).

[0150] Next, the image processing unit 7 identifies matching particles in each image by the same method as in step S220 (step S460).

[0151] Next, the image processing unit 7 assigns a scattered light intensity I1i, a scattered light intensity I2j, and a shadow size D3k to each particle determined to be the same particle.

[0152] At this time, two types of particles are obtained: particles with scattered light intensity I1i, scattered light intensity I2j, and shadow size D3k, and particles with only scattered light intensity I1i and scattered light intensity I2j. The latter are particles that are too small to be detected in the shadow image.

[0153] Next, the image processing unit 7 plots the measurement points on a first graph with the scattered light intensity I1i on the vertical axis and the scattered light intensity I2j on the horizontal axis, and a second graph with the scattered light intensity I1i on the vertical axis and the shadow size D3k on the horizontal axis (S470).

[0154] Specifically, the image processor 7 generates a first graph plotting measurement points related to particles having values ​​only in the scattered light intensity I1i and the scattered light intensity I2j, i.e., microparticles whose shadow size is less than a predetermined threshold, and a second graph plotting measurement points related to other particles, i.e., particles whose shadow size is equal to or greater than a predetermined threshold. At this time, the image processor 7 also obtains an expected theoretical correlation curve of a given sample from the memory unit 10 and draws it superimposed on these graphs.

[0155] There are several methods for setting the threshold value in step S470. For example, a first method is to set the limit value at which the particle size can be recognized from the shadow image as a reference. Another method is to set the particle size at which the difference between the scattered light intensity I1i and the scattered light intensity I2j is equal to or smaller than the resolution when the scattered light intensity characteristics of the particles to be measured can be predicted in advance.

[0156] Next, the image processing unit 7 uses the first graph and the second graph to calculate the particle size distribution of the particles from each graph and to perform material discrimination (step S480), in the same manner as in the first and second embodiments. After calculating the material discrimination and the particle size distribution, the image processing unit 7 ends the processing of this flow.

[0157] The imaging and captured image analysis process according to this embodiment has been described above.

[0158] Such a particle measuring device 100 can simultaneously measure particle sizes and discriminate materials with a less expensive configuration. In particular, the particle measuring device can expand the range of measurable particle sizes by selecting an appropriate graph type according to the particle size.

[0159] <Fourth embodiment> 16 is a flow chart showing an example of a refractive index estimation process according to the fourth embodiment. The particle measuring device 100 according to this embodiment is characterized in that it can estimate the refractive index of a sample whose refractive index is unknown. The basic configuration of the particle measuring device 100 is the same as that of the particle measuring device 100 of the first embodiment.

[0160] When the process starts, the particle measuring device 100 performs the same processes as steps S200 to S220 in the first embodiment (step S600). In addition, the image processing unit 7 plots the measurement points of each particle on a graph with the scattered light intensity on the vertical axis and the shadow size on the horizontal axis (step S610).

[0161] Next, the image processor 7 estimates the refractive index of the particles contained in the sample by searching for a theoretical correlation curve corresponding to the material type of the measured sample. Specifically, the image processor 7 sets an initial value of the refractive index (step S620), and creates a theoretical correlation curve on a graph plotting the measurement points (on a graph with the vertical axis representing the scattered light intensity and the horizontal axis representing the shadow size) (step S630).

[0162] The image processor 7 also calculates the error between each measurement point and the theoretical correlation curve based on the variance or standard deviation of the shortest distance between each measurement point and the generated theoretical correlation curve (step S640).The image processor 7 also determines whether the error is equal to or smaller than a predetermined threshold (S650).

[0163] If it is determined that the error is not equal to or less than the threshold (No in step S650), the image processor 7 sequentially changes the refractive index setting value (step S660) and returns the process to step S630. On the other hand, if it is determined that the error is equal to or less than the threshold (Yes in step S650), the image processor 7 estimates the setting value as the refractive index corresponding to the material type of the measured sample (step S670). After estimating the refractive index, the image processor 7 ends the process of this flow.

[0164] The refractive index estimation process according to the fourth embodiment has been described above.

[0165] According to such a particle measuring device, it is possible to estimate the refractive index of particles in a sample whose refractive index is unknown, with a less expensive configuration.

[0166] The analysis process of this embodiment may use the configuration of the particle measuring device according to the second embodiment. In this case, if the refractive index at one wavelength of the parallel light is known, the refractive index corresponding to the other wavelength can be estimated with high accuracy.

[0167] In the first to third embodiments described above, the image processor 7 may output a graph showing both the measurement points and the theoretical correlation curve based on the Mie scattering theory to a display connected to the particle measuring device 100. In this way, the user can refer to the graph showing the measurement status and visually confirm the distribution of each particle contained in the sample. In addition, for example, by drawing several representative particle sizes on the theoretical correlation curve, the user can more easily imagine the distribution state.

[0168] Furthermore, the present invention is not limited to the above-mentioned embodiment and modified examples, and various modified examples are included within the scope of the same technical idea. For example, the above-mentioned embodiment has been described in detail to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all of the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0169] In addition, in the above explanation, the control lines and information lines are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it can be considered that almost all components are connected to each other. [Explanation of symbols]

[0170] 100...particle measuring device, 1...first light source, 2...second light source, 3...measuring unit, 4...microscope, 5...imaging unit, 6...light shielding plate, 7...image processing unit, 71...scattered light intensity processing unit, 72...shadow size measurement processing unit, 8...control unit, 9...light source switching unit, 10...storage unit, 11...communication unit, 110...arithmetic unit, 120...main storage unit, 130...auxiliary storage unit, 140...communication unit, 150...bus, N...network

Claims

1. a first light source and a second light source for irradiating a sample containing particles of a predetermined material with parallel light; an imaging unit that captures a scattered light image of the particle by the parallel light irradiated from the first light source and a shadow image of the particle by the parallel light irradiated from the second light source; based on a distance relationship between a theoretical correlation curve for each material type, which indicates a theoretical value of the correspondence relationship between the scattered light intensity and the particle size of the particle for each predetermined scattering angle, and a measurement point, which is specified based on the scattered light image and the shadow image and indicates the correspondence relationship between the scattered light intensity and the shadow size of the particle, the theoretical correlation curve which is closer to the measurement point is specified, and material discrimination is performed based on the material type corresponding to the specified theoretical correlation curve; an image processing unit that calculates a particle size of the particle in the sample based on the particle size corresponding to the measurement point indicated by the identified theoretical correlation curve; Equipped A particle measuring device characterized by:

2. 2. The particle measuring device according to claim 1, The irradiation angle of the parallel light emitted from the first light source is The imaging unit is configured to receive light scattered by the particles at a scattering angle equal to or smaller than a predetermined scattering angle. A particle measuring device characterized by:

3. 2. The particle measuring device according to claim 1, The illumination device further includes an illumination angle adjustment mechanism for adjusting an illumination angle of the parallel light emitted from the first light source. A particle measuring device characterized by:

4. a first light source and a second light source for irradiating a sample containing particles of a predetermined material with parallel light having mutually different wavelengths; an imaging unit that captures a first scattered light image of the particle by the parallel light of the first wavelength irradiated from the first light source and a second scattered light image of the particle by the parallel light of the second wavelength irradiated from the second light source; based on a distance relationship between a theoretical correlation curve for each material type, which indicates a theoretical value of a correspondence relationship between scattered light intensities of different wavelengths of the particle for each predetermined scattering angle, and a measurement point, which indicates a correspondence relationship between a first scattered light intensity and a second scattered light intensity of the particle, specified based on the first scattered light image and the second scattered light image, a theoretical correlation curve which is closer to the measurement point is specified, and material discrimination is performed based on the material type corresponding to the specified theoretical correlation curve; an image processing unit that calculates a particle size of the particle in the sample based on a relationship between a refractive index of the material type corresponding to the specified theoretical correlation curve, the first scattered light intensity and the second scattered light intensity corresponding to the measurement point indicated by the theoretical correlation curve, and the scattering angle corresponding to the theoretical correlation curve. A particle measuring device characterized by:

5. The particle measuring device according to claim 4, The imaging unit includes: The first scattered light image and the second scattered light image are captured by parallel light of the first wavelength and parallel light of the second wavelength, respectively, which are simultaneously irradiated from the first light source and the second light source. A particle measuring device characterized by:

6. The particle measuring device according to claim 4, a third light source that irradiates the sample containing particles of the predetermined material with the parallel light, The imaging unit includes: capturing a shadow image of the particle caused by the parallel light irradiated from the third light source; The image processing unit includes: using the first scattered light image and the second scattered light image, material discrimination is performed on the particles having a particle size less than a predetermined value, and the particle size of the particles is calculated; The particles having a particle size equal to or larger than a predetermined value are subjected to material discrimination using the first scattered light image and the shadow image, and the particle size of the particles is calculated. A particle measuring device characterized by:

7. 2. The particle measuring device according to claim 1, The image processing unit includes: A refractive index of the unknown particle is estimated based on a positional relationship between the theoretical correlation curve generated as a theoretical value corresponding to a material of the unknown particle based on a predetermined refractive index, and a measurement point indicating the correspondence between the scattered light intensity and the shadow size specified based on the scattered light image and the shadow image. A particle measuring device characterized by:

8. 2. The particle measuring device according to claim 1, The sample container further includes an irradiation window drive unit that drives the sample container in the direction of the optical axis of the parallel light irradiated from the second light source to suppress a flow of the sample in the sample container and that has an irradiation window through which the parallel light irradiated from the first light source and the second light source is incident. A particle measuring device characterized by:

9. 2. The particle measuring device according to claim 1, Further comprising a valve for controlling the injection and discharge of the sample into the sample container; The valve is The flow of the sample in the sample vessel is controlled to suppress the movement of the particles. A particle measuring device characterized by:

10. 2. The particle measuring device according to claim 1, A sample container into which the sample is injected is provided. The apparatus further includes a cleaning mechanism that ejects a cleaning liquid toward the sample attached to a pair of windows onto which the parallel light is irradiated from the first light source and the second light source. A particle measuring device characterized by:

11. 2. The particle measuring device according to claim 1, The theoretical correlation curve is generated based on the Mie scattering theory, using the refractive index of the particles contained in the sample as an input parameter. A particle measuring device characterized by:

12. A particle measurement method performed by a particle measurement device, comprising: The particle measuring device is An illumination step of irradiating a sample containing particles of a predetermined material with parallel light from a first light source and a second light source; an imaging step of capturing a scattered light image of the particle by the parallel light irradiated from the first light source and a shadow image of the particle by the parallel light irradiated from the second light source; based on a distance relationship between a theoretical correlation curve for each material type, which indicates a theoretical value of a correspondence relationship between the scattered light intensity and the particle size of the particle for each predetermined scattering angle, and a measurement point, which indicates a correspondence relationship between the scattered light intensity and the shadow size of the particle and which is specified based on the scattered light image and the shadow image, the theoretical correlation curve which is closer to the measurement point is specified, and material discrimination is performed based on the material type corresponding to the specified theoretical correlation curve; and an image processing step of calculating the particle size of the particles in the sample based on the particle size corresponding to the measurement point indicated by the identified theoretical correlation curve. A particle measuring method comprising:

13. A particle measurement method performed by a particle measurement device, comprising: The particle measuring device is an irradiating step of irradiating a sample containing particles of a predetermined material with parallel light having different wavelengths from a first light source and a second light source; an imaging step of capturing a first scattered light image of the particle by the parallel light of the first wavelength irradiated from the first light source and a second scattered light image of the particle by the parallel light of the second wavelength irradiated from the second light source; based on a distance relationship between a theoretical correlation curve for each material type, which indicates a theoretical value of a correspondence relationship between scattered light intensities of different wavelengths of the particle for each predetermined scattering angle, and a measurement point, which indicates a correspondence relationship between a first scattered light intensity and a second scattered light intensity of the particle, specified based on the first scattered light image and the second scattered light image, a theoretical correlation curve which is closer to the measurement point is specified, and material discrimination is performed based on the material type corresponding to the specified theoretical correlation curve; an image processing step of calculating a particle size of the particle in the sample based on the relationship between the refractive index of the material type corresponding to the identified theoretical correlation curve, the first scattered light intensity and the second scattered light intensity corresponding to the measurement point indicated by the theoretical correlation curve, and the scattering angle corresponding to the theoretical correlation curve. A particle measuring method comprising:

14. 14. The particle measurement method according to claim 13, In the irradiation step, Irradiating a sample containing particles of the predetermined material with the parallel light from a third light source; In the imaging step, capturing a shadow image of the particle caused by the parallel light irradiated from the third light source; In the image processing step, using the first scattered light image and the second scattered light image, material discrimination is performed on the particles having a particle size less than a predetermined value, and the particle size of the particles is calculated; The particles having a particle size equal to or larger than a predetermined value are subjected to material discrimination using the first scattered light image and the shadow image, and the particle size of the particles is calculated. A particle measuring method comprising:

15. 13. A particle measurement method according to claim 12, comprising: In the image processing step, A refractive index of the unknown particle is estimated based on a positional relationship between the theoretical correlation curve generated as a theoretical value corresponding to a material of the unknown particle based on a predetermined refractive index, and a measurement point indicating the correspondence between the scattered light intensity and the shadow size specified based on the scattered light image and the shadow image. A particle measuring method comprising:

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