Particle measurement device and particle measurement method

Abstract

The particle measuring device and the particle measuring method of the present application can simultaneously perform measurement of particle size and material discrimination with a less expensive configuration, which includes a first light source and a second light source that irradiate parallel light to a sample of particles containing a prescribed material, an imaging section that photographs a scattered light image of the particles from the parallel light irradiated from the first light source and a shadow image of the particles from the parallel light irradiated from the second light source, and an image processing section that performs material discrimination of the particles and calculates particle size of the particles based on a correspondence relationship of scattered light intensity of the particles determined from the scattered light image and a shadow size of the particles determined from the shadow image, and a theoretical correlation curve that represents a theoretical value of the correspondence relationship of the particles.

Description

Technical Field

[0001] This invention relates to a particle measuring apparatus and a particle measuring method. This invention claims priority to Japanese Patent Application No. 2021-114557, filed on July 9, 2021, the contents of which are incorporated herein by reference in any designated country that acknowledges inclusion by reference. Background Technology

[0002] Patent document 1 describes a technique for measuring particle size distribution and identifying materials in samples, which includes "a particle group measuring device capable of non-contactly calculating the particle size, average particle size, variance of particle size, number of particles, and refractive index of the measured particles in a very short time. The particle group measuring device generates a theoretical value table of scattered light intensity in advance through pre-calculation processing. Then, at the position of the scattering angle ±θ determined during the pre-calculation processing, a first polarization camera and a second polarization camera are set. The distance minimum value calculation unit determines the first wavelength of the first scattered light intensity (I) output from the first polarization camera." 1λ1 ), Measure the intensity of the second scattered light at the first wavelength (I) 2λ1 The measured intensity of the first scattered light at the second wavelength, output from the second polarization camera (I) 1λ2 ), Measure the intensity of the second scattered light at the second wavelength (I) 2λ2 The table records the theoretical values ​​of the scattered light intensity with the highest similarity, and outputs the refractive index m and standard deviation σ. g Average particle size D g "Number of particles n".

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2020 / 096038 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the technology of Patent Document 1, a color filter is used to extract the wavelength components corresponding to the two light sources from the scattered light scattered by the particle cluster, and a polarization camera is used to extract the longitudinal and transverse polarization components. Furthermore, in this technology, the average particle size, standard deviation, particle number, and refractive index of the particle cluster are calculated using these four extracted values. However, this technology suffers from increased equipment costs because it uses two polarization cameras, which are more expensive than typical CCD (Charge-Coupled Device) cameras.

[0008] The present invention was developed in view of the above-mentioned problems, and aims to simultaneously measure particle size and identify materials using a more cost-effective structure.

[0009] Technical solutions for solving the problem

[0010] This application includes multiple technical solutions that address at least a portion of the aforementioned problems, one example of which is described below. One aspect of the present invention for measuring particles, addressing the aforementioned problems, includes: a first light source and a second light source that irradiate a sample containing particles of a specified material with parallel light; an imaging unit that captures a scattered light image of the particles obtained from the parallel light irradiated by the first light source and a shadow image of the particles obtained from the parallel light irradiated by the second light source; and an image processing unit that performs material identification of the particles and calculates the particle size based on a correspondence between the scattered light intensity of the particles determined from the scattered light image and the shadow size of the particles determined from the shadow image, and a theoretical correlation curve representing the theoretical value of this correspondence.

[0011] The effects of the invention

[0012] According to the present invention, it is possible to simultaneously measure particle size and identify materials using a more cost-effective structure. Attached Figure Description

[0013] Figure 1 This is a diagram showing an example of the schematic structure of the particle measuring device according to the first embodiment.

[0014] Figure 2 This is a diagram illustrating an example of the hardware structure of a processing device.

[0015] Figure 3 This is a diagram showing an example of a cross-section of the measuring section.

[0016] Figure 4 This is a diagram showing an example of the cross-sectional structure of the measuring section during particle measurement.

[0017] Figure 5 This is an example of an image of scattered light.

[0018] Figure 6 This is a diagram representing an example of a shadowed image.

[0019] Figure 7 This is a flowchart illustrating an example of particle measurement processing.

[0020] Figure 8 This is a flowchart illustrating an example of image analysis and processing.

[0021] Figure 9 This is a graph representing an example of a theoretical correlation curve.

[0022] Figure 10 This is a diagram illustrating an example of the schematic structure of the particle measuring device according to the second embodiment.

[0023] Figure 11 This is a flowchart illustrating an example of the camera and image analysis processing in the second embodiment.

[0024] Figure 12 This is an example of a graph depicting the theoretical correlation curves for samples with different refractive indices.

[0025] Figure 13 This is an example of a graph showing the intensity of scattered light in two samples where the refractive index is not wavelength-dependent.

[0026] Figure 14 This is a diagram illustrating an example of the schematic structure of the particle measuring device according to the third embodiment.

[0027] Figure 15 This is a flowchart illustrating an example of the camera and image analysis processing in the third embodiment.

[0028] Figure 16 This is a flowchart illustrating an example of the refractive index calculation process in the fourth embodiment. Detailed Implementation

[0029] Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings.

[0030] <First Implementation>

[0031] Figure 1 This is a diagram showing an example of the schematic structure of the particle measuring device 100 according to this embodiment. The particle measuring device 100 includes a first light source 1, a second light source 2, a measuring unit 3, a microscope 4, a camera unit 5, a light shield 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.

[0032] The first light source 1 is a device that illuminates a parallel beam A onto a sample flowing within the sample container of the measuring unit 3. The first light source 1 can be, for example, a light-emitting element such as an LED or a laser. However, when using a laser, there is a possibility of light interference caused by particle groups contained in the sample, resulting in speckles. In this case, the interference can be reduced by, for example, by providing a diffuser or a speckle reduction device.

[0033] As shown in the figure, the first light source 1 is positioned approximately opposite to the measuring unit 3 and the microscope 4. The "approximately opposite" position means that the parallel light A of the first light source 1 is not parallel to the optical axis X of the microscope 4; that is, the parallel light A of the first light source 1 intersects the optical axis X of the microscope 4.

[0034] Specifically, the first light source 1 and the microscope 4 are arranged opposite each other such that parallel light A intersects the optical axis X at a predetermined angle θth of less than 90°. Furthermore, the parallel light A is set such that the distribution amplitude of its parallelism relative to the optical axis X is sufficiently small compared to the angle θth. Additionally, the angle θth is preferably set, for example, in the range of 10° to 30°.

[0035] The beam size and shape of the parallel light A are designed so that the light scattered only by the particles of the sample in the sample container can be captured by the imaging unit 5 of the microscope 4 (i.e., the component that is not scattered but travels in a straight line is not incident on the imaging unit 5), and can illuminate the entire field of view of the microscope 4 in the fluid flowing in the sample container.

[0036] In addition, in order to prevent unwanted light (such as light directly incident from the first light source 1) from entering the microscope 4 at the incident part, a light shield 6 can be provided between the sample and the microscope 4. Through the action of the light shield 6, only the scattered light within a specified angle range (scattered light below a specified angle θth) from the scattered light scattered by the particles of the sample is incident on the microscope 4.

[0037] The second light source 2 is a device that irradiates parallel light B onto the sample flowing inside the sample container of the measuring unit 3. As the second light source 2, it uses a light-emitting element such as an LED or a laser, similar to the first light source 1.

[0038] Furthermore, the second light source 2 is positioned approximately opposite to the measuring unit 3 and the microscope 4. Additionally, the second light source 2 is configured such that the optical axis of the parallel light B is approximately aligned with the optical axis X of the microscope 4.

[0039] The measuring unit 3 is a device for receiving parallel light A and parallel light B, respectively, from the first light source 1 and the second light source 2, onto a sample filled in an internally held sample container. Further details of the measuring unit 3 will be described later.

[0040] The microscope 4 is positioned approximately opposite the first light source 1 and the second light source 2, separated by the measuring unit 3. It is a device that converts incident light (parallel light A obtained from the first light source 1 and parallel light B obtained from the second light source 2) into electrical signals using the imaging unit 5 to generate image information. The microscope 4 is designed with an optical system that focuses the object-side focus on the sample and allows the imaging unit 5 of the microscope 4 to capture the scattered light from each particle and the shadows cast by the particles.

[0041] Furthermore, for microscope 4, the focal length and lens diameter are preset to prevent the linearly advancing component of parallel light A from incident on the imaging unit 5. Specifically, microscope 4 is set to make the focal length as long as possible relative to the lens diameter in order to capture the component of scattered light that is approximately parallel to the optical axis X (the component whose angle relative to the optical axis X is less than a specified angle θth).

[0042] The imaging unit 5 is an imaging device (image sensor) that receives light incident on the microscope 4 and captures scattered light images and shadow images by converting it into electrical signals. Specifically, when illuminated by parallel light A from the first light source 1, the imaging unit 5 receives scattered light scattered by particles within the sample container and captures a scattered light image. Additionally, when illuminated by parallel light B from the second light source 2, the imaging unit 5 captures a shadow image representing the shadows of the particles within the sample container. Furthermore, the imaging unit 5 outputs the captured image information to the image processing unit 7.

[0043] The image processing unit 7, control unit 8, light source switching unit 9, storage unit 10, and communication unit 11 are functional units implemented by the processing device of the particle measuring device 100 for performing various processes such as image processing, light source control and switching, storage of specified information, and communication with external devices.

[0044] Specifically, the image processing unit 7 is a functional unit that analyzes and processes image information acquired from the imaging unit 5. More specifically, the image processing unit 7 calculates the particle size distribution and material identification of particles contained in the sample based on the intensity of scattered light and the size of shadows. In addition, the image processing unit 7 includes a scattered light intensity processing unit 71 and a shadow size measurement processing unit 72.

[0045] The scattered light intensity processing unit 71 is a functional unit that uses the scattered light image acquired from the imaging unit 5 to calculate the intensity of the scattered light from each particle included in the scattered light image. Specifically, the scattered light intensity processing unit 71 acquires a scattered light image from the imaging unit 5, which is obtained by capturing the scattered light from the parallel light A irradiating the sample from the first light source 1 at a predetermined angle θth or less on the particles, and uses it to calculate the intensity of the scattered light from each particle.

[0046] The shadow size measurement and processing unit 72 is a functional unit that uses the shadow image acquired from the imaging unit 5 to calculate the size of each particle included in the shadow image. Specifically, the shadow size measurement and processing unit 72 acquires a shadow image from the imaging unit 5, which is obtained by capturing the shadow of each particle formed by parallel light B illuminating the sample from the second light source 2, and uses it to calculate the size of each particle.

[0047] Furthermore, the image processing unit 7 obtains 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 accordingly, based on the analysis results of the captured image based on the calculation results. Additionally, the image processing unit 7 can also output information for monitoring measurement conditions to an external display or the like.

[0048] The control unit 8 is a functional unit that controls the operation of the particle measuring device 100. Specifically, the control unit 8 outputs instructions to the light source switching unit 9 for controlling the first light source 1 and the second light source 2. In addition, the control unit 8 controls the operation of the measuring unit 3.

[0049] Furthermore, the control unit 8 can also output an alarm signal based on the analysis and processing results of the image information by the image processing unit 7. Additionally, the control unit 8 can also communicate with external devices via the communication unit 11. In this case, the control unit 8 may, for example, send the analysis results of the image information obtained from the image processing unit 7 (e.g., particle size distribution and material identification results) via the communication unit 11 to an external device connected to a network such as a LAN (Local Area Network) or a public network.

[0050] The light source switching unit 9 is a function that switches the illumination of the first light source 1 and the second light source 2 based on the control instructions obtained from the control unit 8.

[0051] Storage unit 10 is a functional unit that stores specified information. Specifically, storage unit 10 stores theoretical correlation curves corresponding to the material types of particles contained in the sample. Details of the theoretical correlation curves will be described later.

[0052] The communication unit 11 is a functional unit that performs information communication with external devices. For example, the communication unit 11 sends information representing the analysis results of image information to the external device. In addition, the communication unit 11 obtains specified information (such as a request to obtain analysis results) from the external device.

[0053] Figure 2 This is a diagram illustrating an example of the hardware structure of a processing device that implements 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, the processing device includes an arithmetic unit 110, a main storage unit 120, an auxiliary storage unit 130, a communication unit 140, and a bus 150 that electrically connects them to each other.

[0054] The computing device 110 may be a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), or other semiconductor devices if it is the main body performing the specified processing. The main storage device 120 is a memory device such as RAM (Random Access Memory) or ROM (Read Only Memory).

[0055] The auxiliary storage device 130 is a non-volatile storage device such as a hard disk drive (HDD), SSD (Solid State Drive), or flash memory, which is capable of storing digital information.

[0056] Communication device 140 is a device that performs wired communication via a network cable or a device that performs wireless communication via an antenna. Communication device 140 communicates with other devices connected to network N.

[0057] The above describes an example of the hardware structure of the processing device in the particle measuring device 100.

[0058] Furthermore, the image processing unit 7, the control unit 8, and the light source switching unit 9 are implemented using a program that is processed by the arithmetic unit 110. This program is stored in the main storage device 120 or the auxiliary storage device 130, and is loaded into the main storage device 120 during program execution and executed by the arithmetic unit 110. Additionally, the storage unit 10 is implemented using the main storage device 120, the auxiliary storage device 130, or a combination thereof. Furthermore, the communication unit 11 is implemented using a communication device 140.

[0059] Furthermore, the various structures, functions, processing units, and processing modules of the processing device can be partially or entirely implemented in hardware, for example, through design in integrated circuits. Alternatively, the aforementioned structures and functions can be implemented in software by a processor interpreting and executing programs that perform each function. Information such as programs, tables, and files that implement each function can be stored in memory, storage devices such as hard disks or SSDs, or recording media such as IC cards, SD cards, and DVDs.

[0060] Next, the detailed structure of the measuring unit 3 will be explained.

[0061] Figure 3 This is a diagram showing an example of a cross-section of the measuring unit 3. As shown, the measuring unit 3 includes a sample container 31 with openings at both ends, a pipe 32 connected to the openings of the sample container 31, and a first valve 33 (see reference) for controlling the injection (flow) of the sample into the sample container 31 through the pipe 32. Figure 1 The sample container 31 includes an irradiation window drive unit 34 on the wall, an irradiation window 35 at one end of the irradiation window drive unit 34, an observation window 36 on the wall of the sample container 31 opposite to the irradiation window 35, a nozzle 37 with the nozzle outlet disposed inside the sample container 31, a pipe 38 connected to the nozzle 37, and a second valve 39 connected to the pipe 38.

[0062] Furthermore, the first valve 33 includes an upstream valve and a downstream valve. When the upstream valve is open, a sample is injected into the sample container 31. When the downstream valve is open, the sample in the sample container 31 is discharged from the measuring unit 3. In addition, by controlling the opening and closing of the upstream and downstream valves, the flow of the sample in the sample container 31 can be controlled, and the movement of particles during imaging by the camera unit 5 can be suppressed.

[0063] Additionally, tube 38 is connected to the cleaning solution storage container, using pump 40 (reference). Figure 1 The cleaning solution is sprayed into sample container 31 and stored in container 41 (reference). Figure 1 ).

[0064] In addition, the second valve 39 includes a cleaning valve for the irradiation window side and a cleaning valve for the observation window side. When the cleaning valve for the irradiation window side is opened, cleaning fluid 41 is sprayed onto the irradiation window 35, and when the cleaning valve for the observation window side is opened, cleaning fluid 41 is sprayed onto the observation window 36.

[0065] The sample container 31 is sealed to prevent external air from entering, and functions as a sample holding area that can hold the sample or cleaning solution 41 inside.

[0066] Sample container 31 may be connected to a manufacturing line (not shown) via piping 32, for example, to directly inject samples drawn from the manufacturing line. Alternatively, sample container 31 may not be connected to the manufacturing line and may be located in a remote location.

[0067] The cleaning solution 41 differs from the sample; it is a liquid that removes solid components from water or the sample without damaging the window. Alternatively, a liquid with cleaning properties, such as water containing dispersants and surfactants, can be used. This improves the wettability of the window, preventing the sample or air bubbles from adhering to it. Furthermore, the cleaning solution 41 can also be a slurry containing low-hardness particles such as resins that will not damage the window. These low-hardness particles collide with particles firmly attached to the window, thereby removing them.

[0068] The observation window 36 is used to observe the sample inside the sample container 31 using the microscope 4. The observation window 36 is transparent at least for the wavelengths of parallel light A and parallel light B. The optical system is configured such that the focal point of the microscope 4 is located near the sample-side surface of the observation window 36.

[0069] Irradiation window 35 is used to illuminate the sample container 31 with parallel light A and parallel light B. Irradiation window 35 is disposed on the sample container 31 opposite to observation window 36. Irradiation window 35 is transparent at least for the wavelengths of parallel light A and parallel light B.

[0070] The illumination window drive unit 34 is a drive mechanism that drives the illumination window 35 in the direction of the optical axis X of the microscope 4. Specifically, the illumination window drive unit 34 adjusts the distance between the illumination window 35 and the observation window 36 by driving the illumination window 35 closer to or further away from the observation window 36. In addition, the illumination window drive unit 34 can also be moved manually by the user.

[0071] Figure 3 The position of the irradiation window drive unit 34 shown indicates the position during cleaning. At this time, the nozzle 37 sprays cleaning fluid 41 towards the irradiation window 35 and the observation window 36, respectively.

[0072] In addition, a sealing mechanism is provided between the irradiation window drive unit 34 and the sample container 31 to prevent external air from entering the sample container 31 and to enable the irradiation window drive unit 34 to move. The sealing mechanism may include an O-ring or a diaphragm.

[0073] The nozzle 37's outlet is positioned upstream of both the irradiation window 35 and the observation window 36, relative to the direction of sample flow. Thus, the cleaning solution 41 ejected from the nozzle 37 is discharged from the sample container 31 along with the sample.

[0074] In addition, in order to prevent the particles from overlapping when photographing the sample in the sample container 31 with the microscope 4, the sample is diluted and dispersed as needed.

[0075] Additionally, parallel light A and parallel light B enter through the illumination window 35 and irradiate the sample. The component of parallel light A that is not scattered by particles in the sample and travels in a straight line exits through the observation window 36 towards the measuring unit 3. The imaging unit 5 of the microscope 4 captures, through the observation window 36, the component of parallel light A that is scattered in the direction of the optical axis X of the microscope 4 due to particles in the sample (scattered light scattered at a scattering angle θth or less). Furthermore, the imaging unit 5 of the microscope 4 captures, through the observation window 36, the component of parallel light B that is not scattered by particles in the sample and travels in a straight line.

[0076] In addition, the observation window 36 is preferably set to a sufficient size so that the entire linear component of the parallel light A can pass through. This is to prevent light reflected or scattered inside the sample container 31 from entering the microscope 4 and deteriorating the S / N (Signal-to-Noise ratio) of the captured image information.

[0077] In addition, in order to suppress diffuse reflection of light inside the sample container 31, a light-absorbing material can be coated on the inner wall of the sample container 31, or a light-absorbing component can be provided on the inner side of the sample container 31.

[0078] Figure 4This diagram shows an example of the cross-sectional structure of the measuring unit 3 during particle measurement. As shown, the irradiation window 35 and the irradiation window drive unit 34 move accordingly from the position during cleaning to near the observation window 36. Therefore, the gap between the irradiation window 35 and the observation window 36 narrows, the thickness of the microscope 4 in the X direction of the optical axis becomes thinner, and the area (volume) of the sample irradiated by parallel light A and parallel light B shrinks.

[0079] This prevents particle overlap during sample imaging and suppresses the effect of scattered light caused by particles outside the focal range of microscope 4. Furthermore, by bringing the illumination window 35 and the observation window 36 as close as possible, particle movement can be suppressed, as well as positional deviations caused by vibrations during imaging and particle movement when switching light sources.

[0080] After the imaging by microscope 4 is completed, the illumination window 35 moves away from the observation window 36 due to the action of the illumination window drive unit 34. After the distance between the illumination window 35 and the observation window 36 increases, the sample in the sample container 31 is replaced.

[0081] Furthermore, the measuring unit 3 has an operation control mechanism (not shown) that operates the first valve 33, the illumination window drive unit 34, the second valve 39, and the pump 40 respectively. The operation control mechanism is, for example, a drive motor that performs the opening and closing of the first valve 33 and the second valve 39, and the movement of the illumination window drive unit 34 (movement in the X-axis direction), and a switch that switches the pump 40 on / off. Moreover, these operation control mechanisms perform predetermined operations such as opening and closing the first valve 33 and the second valve 39, moving the illumination window drive unit 34, and switching the pump 40 on / off, based on the control performed by the control unit 8 (for example, by changing the voltage applied to the operation control mechanisms).

[0082] Figure 5 This is an example of an image of scattered light captured by camera unit 5. Specifically, Figure 5 (a) is an example of an image showing the scattered light captured by alumina particles. Figure 5 (b) is a schematic diagram showing an image of scattered light. Additionally, Figure 5 The schematic diagram in (b) is used to illustrate the image of scattered light and does not correspond to... Figure 5 The image of scattered light in (a).

[0083] like Figure 5 (a) and Figure 5 As shown in (b), each point in the scattered light image represents the scattered light from each particle. The scattered light intensity processing unit 71 uses this scattered light image to identify each particle that is the object of measurement and obtains the scattered light intensity on each particle.

[0084] Specifically, the scattered light intensity processing unit 71 determines the pixel group (pixel group) in the scattered light image that corresponds to each particle, and obtains the value of the pixel with the highest brightness value in the pixel group as the scattered light intensity of that particle. Alternatively, the scattered light intensity processing unit 71 may also use the peak intensity of a curve obtained by fitting it according to a Gaussian distribution or the like as the scattered light intensity.

[0085] In addition, if the intensity of the scattered light is outside the brightness range of the captured image, the output of the first light source 1, the exposure time of the camera unit 5, or the gain of the camera unit 5 can be adjusted.

[0086] Furthermore, since the intensity of scattered light varies considerably for each particle, and the brightness range of the scattered light image cannot accommodate the scattered light intensity of all particles, multiple shots can be taken by changing, for example, the output of the first light source 1, the exposure time of the imaging unit 5, or the gain of the imaging unit 5. Moreover, such adjustments can be performed by the image processing unit 7 analyzing the captured image and outputting instructions to the control unit 8 accordingly based on the analysis results.

[0087] Figure 6 This is an example diagram showing a shadow image. Each point in the diagram represents the shadow of a specific particle. The shadow size measurement and processing unit 72 uses the shadow image captured by the camera unit 5 to identify each particle and obtain the shadow size at each particle.

[0088] Specifically, the shadow size measurement processing unit 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, for the shadow area, for example, if the particle shape is assumed to be circular, the area can be converted into the equivalent circle diameter.

[0089] Furthermore, the shadow size of the particles obtained from the shadow image is larger than the actual particle shape due to light diffraction caused by the lens. The effect of diffraction is inversely proportional to the numerical aperture of the lens, and correction is required when using a lens with an insufficient numerical aperture. In this case, the diffraction profile is given by equation (1), so the true shadow shape can be calculated by fitting using equation (1).

[0090] [Mathematical Expression 1]

[0091]

[0092] In equation (1), y represents the intensity of the diffracted light. Additionally, x represents the diffraction radius. Furthermore, j1 represents the Bessel function.

[0093] [Description of the action]

[0094] Next, the particle measurement process will be explained.

[0095] Figure 7 This is a flowchart illustrating an example of particle measurement processing. First, the motion control mechanism (not shown) of the measuring unit 3 performs the following actions based on the control of the control unit 8. Specifically, the motion control mechanism opens the first valve 33 (upstream valve and downstream valve) to introduce (inject) the sample into the sample container 31 (step S10). After a predetermined time, when the sample container 31 is replaced with the sample, the motion control mechanism closes the first valve 33 (upstream valve and downstream valve) to stop the sample introduction (step S20).

[0096] Additionally, the motion control mechanism moves the illumination window drive unit 34 so that the illumination window 35 is in position. Figure 4 The measurement location shown (step S30).

[0097] Additionally, 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 irradiates parallel light A from the first light source 1 based on the instruction from the control unit 8.

[0098] Additionally, the imaging unit 5 captures a scattered light image (step S50). Specifically, the imaging unit 5 captures a scattered light image by receiving the scattered light scattered at a predetermined angle θth or less on the particles by receiving parallel light A illuminating the sample. Furthermore, the imaging unit 5 outputs the image information of the captured scattered light image to the image processing unit 7.

[0099] Additionally, 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 irradiates parallel light B from the second light source 2 based on the instruction from the control unit 8.

[0100] Additionally, the imaging unit 5 captures a shadow image (step S70). Specifically, the imaging unit 5 captures the shadows of each particle formed by the parallel light B illuminating the sample. Furthermore, the imaging unit 5 outputs the image information of the shadow image to the image processing unit 7.

[0101] Furthermore, the camera unit 5 uses the scattered light image and shadow image acquired from the camera unit 5 to perform image analysis processing (step S80). Details of the image analysis processing performed by the image processing unit 7 will be described later.

[0102] Next, the motion control mechanism opens the downstream valve in the first valve 33 (step S90), turns the pump 40 ON, opens the second valve 39 (in this case, both the cleaning valve for the irradiation window side and the cleaning valve for the observation window side), and begins to spray cleaning fluid into the sample container 31 (step S100).

[0103] In addition, the motion control mechanism moves the illumination window drive unit 34 to bring the illumination window into position. Figure 3 The cleaning location shown (step S110).

[0104] In addition, after the irradiation window 35 is moved to the cleaning position, the motion control mechanism closes the cleaning valve on the observation window side and sprays cleaning fluid onto the irradiation window 35 for a specified time to remove the attached particles (step S120).

[0105] Next, the motion control mechanism opens the cleaning valve on the observation window side and closes the cleaning valve on the irradiation window side, continuously spraying cleaning fluid onto the observation window 36 for a predetermined time to remove attached particles (step S130). Afterward, the motion control mechanism turns pump 40 OFF, closes the cleaning valve on the observation window side and stops spraying cleaning fluid (step S140), and closes the downstream valve (step S150), leaving the sample container 31 filled with cleaning fluid. Then, if continuous measurement continues ("Yes" in step S160), the particle measuring device 100 waits for the next measurement opportunity (S170), starting the process from step S10 at the next measurement. On the other hand, if continuous measurement is not continued ("No" in step S160), the particle measuring device 100 ends the particle measurement process.

[0106] The above explains the particle measurement process.

[0107] Next, the image analysis and processing performed in the particle measuring device 100 will be explained.

[0108] Figure 8 This is a flowchart illustrating an example of image analysis and processing. This processing is equivalent to… Figure 7 The processing of step S80.

[0109] At the start of processing, 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) within the scattered light image and the scattered light intensity I1i obtained based on the brightness value.

[0110] Next, the shadow size measurement processing unit 72 calculates the shadow size of each particle using the shadow image acquired from the camera unit 5 (step S210). Specifically, the shadow size measurement processing unit 72 identifies each particle included in the shadow image. In addition, for each identified particle j, the shadow size measurement processing unit 72 calculates its position (x2j, y2j) within the shadow image and its shadow size (size of the shadow) D2j.

[0111] Next, the image processing unit 7 determines the same particles 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 the particle j obtained from the shadow image to determine whether the two image information are the same particle.

[0112] More specifically, if the distance between particle i and particle j is below a predetermined threshold, the image processing unit 7 determines that the two particles are the same particle. Thus, it identifies particles that are identical in both the scattered light image and the shadow image.

[0113] In addition, the reason for setting the judgment condition as the distance between particle i and particle j being below a specified threshold is to take into account the deviation between the position of particle i in the scattered light image and the corresponding position of particle j in the shadow image caused by the time difference when switching light sources.

[0114] Next, the image processing unit 7 generates a graph showing the correspondence between scattered light intensity and shadow size (equivalent to particle size described later) 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 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 scattered light intensity on the vertical axis and shadow size on the horizontal axis.

[0115] In addition, at this time, the image processing unit 7 obtains a predetermined number (e.g., 2) of theoretical correlation curves corresponding to the predicted predetermined sample and scattering angle (θth) from the storage unit 10, and plots them superimposed on the graph.

[0116] Furthermore, the theoretical correlation curves between particles and each sample can be calculated based on Mie scattering theory. The intensity of scattered light for each sample depends on the particle size, refractive index, and scattering angle. That is, for samples with different refractive indices, the correlation between particle size and scattered light intensity is different. Therefore, the theoretical correlation curves for samples with different refractive indices can be expressed as curves with different shapes. Thus, by using the refractive index corresponding to each sample as an input parameter based on Mie scattering theory, the scattered light intensity for each particle size can be calculated. In this way, theoretical correlation curves can be generated according to the material type of each sample as theoretical values ​​representing the correspondence between scattered light intensity and particle size (equivalent to shadow size).

[0117] Figure 9 This is a graph showing an example of the theoretical correlation curves between a specified material (alumina particles and silicon oxide particles in this example) and a specified scattering angle (θth). Specifically, Figure 9Figure (a) shows the theoretical correlation curves for alumina and silica particles at a scattering angle of 10°. Additionally, Figure 9 Figure (b) shows the theoretical correlation curves for alumina and silica particles at a scattering angle of 45°. Additionally, Figure 9 (c) is a graph representing the theoretical correlation curves of alumina particles and silicon oxide particles when the scattering angle is 90°. Figure 9 (d) is a graph showing the theoretical correlation curves for alumina and silica particles at a scattering angle of 170°. Additionally, the vertical axis of these graphs represents the scattered light intensity, and the horizontal axis represents the particle size corresponding to the shaded area.

[0118] like Figure 9 (a)~ Figure 9 As shown in (d), the theoretical correlation curves for materials with different refractive indices exhibit different shapes. Furthermore, it can be seen that even for the same sample, different scattering angles will result in theoretical correlation curves of different shapes.

[0119] When plotting the theoretical correlation curves that predict the types of materials, the measurement points for each particle are plotted on or near the corresponding theoretical correlation curves. Thus, if the types of materials and their refractive indices in the sample can be predicted, the particle at each measurement point can be identified by plotting the theoretical correlation curves corresponding to these materials. The specific processing for material identification is described later.

[0120] In addition, in this embodiment, the theoretical correlation curves corresponding to various materials and scattering angles are stored in the storage unit 10 in advance, but these theoretical correlation curves can also be generated during the processing in step S230.

[0121] Next, the image processing unit 7 calculates the particle size distribution and identifies the material based on the comparison between the theoretical correlation curve plotted on the graph and the measurement points (step S240). Specifically, the image processing unit 7 calculates the shortest distance between each measurement point plotted on the graph and the theoretical correlation curve plotted on the graph corresponding to the specified material type and scattering angle (θth).

[0122] More specifically, the diagram depicts Figure 9 In the case of the two theoretical correlation curves shown in (a), the image processing unit 7 calculates all the shortest distances from each measurement point to each theoretical correlation curve.

[0123] Furthermore, the image processing unit 7 determines the theoretical correlation curve corresponding to the minimum shortest distance among the calculated shortest distances. Then, the image processing unit 7 identifies the sample corresponding to the determined theoretical correlation curve as the sample of the measured particle. In this way, the image processing unit 7 performs material identification of the measured particle (sample).

[0124] Furthermore, the method for material identification is not limited to this. For example, the image processing unit 7 can also calculate the average of the shortest distances from each measurement point to each theoretical correlation curve, and determine the material corresponding to the theoretical correlation curve with the smaller average value as the material of the measured particle.

[0125] Furthermore, the image processing unit 7 determines from the image the shaded area 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. Additionally, the image processing unit 7 determines the particle size corresponding to the determined shaded area as the particle size of the measured particle at each measurement point.

[0126] Then, the image processing unit 7 calculates the particle size distribution of the particles in the determined sample based on the number of measurement points and the determined particle size.

[0127] In addition, the image processing unit 7 ends the process after performing material identification and calculating particle distribution.

[0128] The above explains the analysis and processing of captured images.

[0129] According to such a particle measurement device, particle size measurement and material identification can be performed simultaneously using a more cost-effective structure. In particular, the particle measurement device allows for the identification of the material at each measurement point using theoretical correlation curves corresponding to each material. Furthermore, the particle measurement device can simultaneously calculate the particle size distribution corresponding to each sample along with material identification.

[0130] In addition, since the smaller the scattering angle, the higher the intensity of the scattered light, it is preferable to improve the measurement sensitivity by minimizing the scattering angle θth as much as possible during measurement.

[0131] In addition, for example, Figure 9 As shown in (a), (c), and (d), the theoretical correlation curves for silica particles and alumina particles intersect with the scattering angle at several points, making material identification difficult near these points. In this case, as... Figure 9 As shown in (b), by setting the scattering angle to 45°, material identification can be performed using theoretical correlation curves that do not have intersecting points.

[0132] Furthermore, the optimal scattering angle varies depending on the type of material and the predicted range of particle size. Therefore, a mechanism for adjusting the illumination angle of the parallel light A in the first light source 1 can be appropriately provided to allow for changing the scattering angle.

[0133] in addition, Figure 9 The theoretical correlation curve shown represents the case where the particle shape is spherical. In the case of non-spherical particles or particles with uneven surfaces, the intensity of scattered light is measured with an error centered on the theoretical correlation curve. Therefore, by calculating the variance or 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.

[0134] In addition, the particle measuring device 100 can easily remove particles attached to or remaining on the irradiation window 35 and the observation window 36 using a cleaning mechanism with nozzle 37.

[0135] Furthermore, this embodiment shows an example of an optical system in which the linearly advancing component of the parallel light A does not incident on the imaging unit 5. However, it is also possible to modify it by placing a polarizing filter between the sample and the imaging unit 5 and using a polarizing light source as the first light source 1. Examples of polarizing light sources include a polarized laser source or a combination of a polarizing filter and the first light source 1. Using such a polarizing light source, it is also possible to prevent the linearly advancing component of the parallel light A from incident on the imaging unit 5.

[0136] Furthermore, in this embodiment, it is shown that in Figure 3 The example shown is that the nozzles 37 are arranged in positions to spray the cleaning fluid 41 alternately, but the nozzles 37 can also be arranged in positions where the sprayed cleaning fluid 41 does not collide, so that the cleaning fluid 41 can be sprayed from each nozzle 37 at the same time.

[0137] In addition, this embodiment shows an example in which the cleaning fluid 41 is stored in a cleaning fluid storage container inside the measuring unit 3 and supplied, but it can also be configured to supply the cleaning fluid 41 from a supply facility outside the measuring unit 3.

[0138] In addition, this embodiment shows an example in which the flow of the sample is temporarily suppressed during shooting based on the movement of the illumination window drive unit 34, but it is also possible to keep the sample flowing while shooting by switching the light source or keeping the shooting time sufficiently short relative to the movement speed of the particles.

[0139] <Second Implementation>

[0140] Figure 10This figure shows an example of the schematic structure of the particle measuring device 100 according to the second embodiment. As shown, the particle measuring device 100 of this embodiment differs from the first embodiment in that it has a third light source 12, a reflector 13, and a wavelength selective reflector 14 instead of the second light source 2. Furthermore, for structures identical to those of the first embodiment, the same reference numerals are used, and repeated descriptions are omitted.

[0141] The third light source 12 outputs a different wavelength than the first light source 1, and illuminates the sample held by the measuring device with parallel light C via a reflector 13 and a wavelength-selective reflector 14. Furthermore, the optical axis of the parallel light C is set to be approximately aligned with the optical axis of the parallel light A from the first light source 1. Such a third light source 12 may be, for example, a light-emitting element such as an LED or a laser.

[0142] The wavelength-selective reflector 14 has the property of allowing light from the first light source to pass through and reflecting light from the third light source 12.

[0143] The camera unit 5 splits the incident light into multiple wavelengths and captures images corresponding to each wavelength. For example, a color CCD with RGB wavelengths can be used as such a camera unit 5.

[0144] Furthermore, by aligning the wavelengths of the first light source 1 and the third light source 12 with the respective wavelengths of the beam splitting bands of the imaging unit 5, the imaging unit 5 captures images of the scattered light from each light source due to the particles in the sample. Specifically, when using a color CCD with RGB beam splitting as the imaging unit, the output wavelength of the first light source 1 is set to red, and the imaging unit 5 captures the scattered light of this red light using R pixels. Similarly, the output wavelength of the third light source 12 is set to blue, and the imaging unit 5 captures the scattered light of this blue light using B pixels.

[0145] Figure 11 This is a flowchart illustrating an example of the imaging and image analysis processing in this embodiment. Furthermore, the particle measurement processing is essentially the same as in the first embodiment, so its description is omitted.

[0146] At the start of the process, the particle measuring device 100 illuminates the sample with parallel light A from the first light source 1 and captures an image of the scattered light scattered at a specified scattering angle θth or less using the imaging unit 5 (S300).

[0147] 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 for each identified particle i, calculates its position (x1i, y1i) within the scattered light image and the scattered light intensity I1i obtained based on the brightness value.

[0148] Next, the particle measuring device 100 switches the light source via the control unit 8 and the light source switching unit 9, and uses the imaging unit 5 to capture an image of the scattered light scattered at a specified scattering angle θth or less by irradiating the sample with parallel light C from the third light source 12 (S320).

[0149] 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 for each identified particle j, calculates its position (x2j, y2j) within the scattered light image and the scattered light intensity I2j obtained based on the brightness value.

[0150] Next, the image processing unit 7 determines the consistent particles in the two captured scattered light images (step S340). Specifically, the image processing unit 7 compares the positional relationship of each particle i and j obtained from the two scattered light images, determines whether the two image information are the same particle, and determines the consistent particles.

[0151] Next, the image processing unit 7 generates a graph showing the correspondence between the scattered light intensities I1i and I2j in the two scattered light images for each particle determined to be the same particle (step S350). Specifically, the image processing unit 7 assigns a 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.

[0152] In addition, at this time, the image processing unit 7 obtains a predetermined number (e.g., 2) of theoretical correlation curves corresponding to the predicted predetermined sample and scattering angle (θth) from the storage unit 10, and plots them superimposed on the graph.

[0153] Figure 12 This is an example of a graph depicting the theoretical correlation curves for two samples, A and B, with different refractive indices. Specifically, Figure 12 (a)~ Figure 12 Figure (f) shows the theoretical correlation curves for samples A and B at scattering angles of 5°, 10°, 20°, 45°, 90°, and 170°. The vertical axis of these figures represents the scattered light intensity when illuminated by light at a wavelength of 635 nm, and the horizontal axis represents the scattered light intensity when illuminated by light at a wavelength of 455 nm. The refractive index of sample A is 1.45 regardless of wavelength, while the refractive index of sample B is 1.5 at 455 nm and 1.45 at 635 nm. The figures also show results for particle sizes ranging from 0.1 μm to 2 μm.

[0154] As mentioned above, the intensity of scattered light depends on the refractive index of the particles. Therefore, based on Mie scattering theory, samples A and B can exhibit theoretical correlation curves with different shapes. Furthermore, as... Figure 12 (a)~ Figure 12 As shown in (f), even for the same sample, different scattering angles will result in theoretical correlation curves of different shapes.

[0155] When plotting the theoretical correlation curves of the predicted sample, the measurement points of each particle are plotted on or near the corresponding theoretical correlation curves. Thus, if the types of materials and their refractive indices contained in the sample can be predicted, the particle at each measurement point can be identified by plotting the theoretical correlation curves corresponding to these materials.

[0156] Furthermore, when calculating the theoretical correlation curves used in this embodiment, it is important to consider the wavelength dependence of the particle's refractive index. The wavelength dependence of the refractive index will be explained below.

[0157] Figure 13 This is an example graph showing the scattered light intensity of two samples (sample A and sample C) whose refractive index is not wavelength-dependent. The vertical axis represents the scattered light intensity when illuminated by light at a wavelength of 635 nm, and the horizontal axis represents the scattered light intensity when illuminated by light at a wavelength of 455 nm. Furthermore, the refractive index of sample A is 1.45, independent of wavelength, and the refractive index of sample C is 1.5, independent of wavelength. Results are also shown with a scattering angle of 10° and particle sizes ranging from 0.1 μm to 2 μm. As shown in the figure, although there are slight differences between the curves of sample A and sample C, they are similar to... Figure 12 The differences between the curves shown are significantly smaller. This indicates that the wavelength dependence of the particle's refractive index contributes considerably to material identification. Most materials exhibit some degree of wavelength dependence in their refractive index, so it is important to consider this when inputting the refractive index in the calculation of theoretical correlation curves.

[0158] Next, the image processing unit 7 performs particle size distribution calculation and material identification using the same method as in step S240 (step S360). Specifically, the image processing unit 7 performs material identification based on the shortest distance between each measurement point plotted on the graph and the theoretical correlation curve depicted on the graph corresponding to the specified material type and scattering angle (θth).

[0159] In addition, the image processing unit 7 calculates the particle size at each measurement point based on the relationship between the intensity of scattered light at each wavelength corresponding to the point on the theoretical correlation curve closest to each measurement point corresponding to the determined material, and the refractive index and scattering angle of the material.

[0160] Then, the image processing unit 7 calculates the particle size distribution of the sample of the determined material based on the number of each measurement point and the determined particle size.

[0161] In addition, the image processing unit 7 ends the process after performing material identification and calculating particle distribution.

[0162] The above describes the image analysis and processing of the camera and captured images in this embodiment.

[0163] According to such a particle measuring device, particle size measurement and material identification can be performed simultaneously with a more cost-effective structure. In particular, the particle measuring device of this embodiment can calculate the particle size distribution corresponding to each material while identifying it, even for samples containing tiny particles that cannot be detected as shadow images, by using scattered light images obtained by capturing scattered light at different wavelengths.

[0164] In addition, such as Figure 12 (a)~ Figure 12 As shown in (f), the theoretical correlation curves of samples A and B become more complex in shape as the scattering angle increases, resulting in intersection points. It is difficult to distinguish materials near such intersection points. Therefore, the scattering angle is preferably set to minimize such intersection points.

[0165] Furthermore, this embodiment shows an example of switching between the first light source 1 and the third light source 12 for imaging. However, it is also possible to simultaneously illuminate parallel light from these two light sources and capture the scattered light intensity corresponding to each wavelength separately in the imaging unit 5, separating the R image and B image. In this way, simultaneous imaging can be achieved without switching light sources, thus shortening the measurement time.

[0166] Furthermore, this embodiment shows an example where the optical axes of parallel light A and parallel light C are approximately aligned using a reflector 13 and a wavelength-selective reflector 14. However, for example, a structure with a deviated optical axis could be used instead of a reflector 13. Alternatively, the incident angles of the parallel light beams on the sample could be different.

[0167] <Third Implementation Method>

[0168] Figure 14This figure shows an example of the schematic structure of the particle measuring device 100 according to the third embodiment. The particle measuring device 100 of this embodiment is characterized by its ability to expand the range of measurable particle sizes. For example, in the second embodiment described above, even tiny particles that cannot be detected as shadow images as described in the first embodiment can be measured using scattered light images obtained by using parallel light of different wavelengths. On the other hand, in the image analysis processing of the second embodiment, as the particle size increases, the theoretical correlation curves between samples become close or intersect, making material identification difficult. Therefore, in the third embodiment, a particle measuring device 100 that can expand the measurable range of particle sizes by simultaneously using the image analysis processing of the first and second embodiments will be described. Furthermore, for structures identical to those in the first and second embodiments, the same reference numerals are used, and repeated descriptions are omitted.

[0169] 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 in the first embodiment, and a third light source 12, a reflector 13 and a wavelength selective reflector 14 in the second embodiment.

[0170] Figure 15 This is a flowchart illustrating an example of the video recording and image analysis processing in this embodiment.

[0171] At the start of the process, the particle measuring device 100 illuminates the sample with parallel light A from the first light source 1, and the imaging unit 5 captures an image of the scattered light scattered at a predetermined angle θth or less (S400). Additionally, similarly to step S200, the scattered light intensity processing unit 71 calculates the position (x1i, y1i) within the scattered light image and the scattered light intensity I1i based on the brightness value for each particle i identified from the scattered light image (S410).

[0172] Next, the particle measuring device 100 switches the light source via the control unit 8 and the light source switching unit 9, irradiating the sample with parallel light C from the third light source 12, thereby capturing an image of scattered light at a specified scattering angle θth or less using the imaging unit 5 (S420). Additionally, the scattered light intensity processing unit 71, similar to step S200, calculates the position (x2j, y2j) within the scattered light image and the scattered light intensity I2j based on the brightness value for each particle j identified from the scattered light image (S430).

[0173] Next, the particle measuring device 100 switches the light source via the control unit 8 and the light source switching unit 9, irradiating the sample with parallel light B from the second light source 2, thereby capturing a shadow image of each particle (S440). In addition, the shadow size measurement and processing unit 72, similar to step S210, calculates the position (x3k, y3k) and shadow size (size of the shadow) D3k of each particle k identified from the shadow image (step S450).

[0174] Next, the image processing unit 7 uses the same method as in step S220 to determine the consistent particles in each image (step S460).

[0175] Next, the image processing unit 7 assigns scattered light intensity I1i, scattered light intensity I2j, and shadow size D3k to each particle that is determined to be the same particle.

[0176] At this point, two types of particles are obtained: particles with values ​​for scattered light intensity I1i, scattered light intensity I2j, and shadow size D3k, and particles with values ​​for only scattered light intensity I1i and scattered light intensity I2j. The latter are particles with smaller particle sizes that failed to be detected as shadow images.

[0177] Next, the image processing unit 7 plots the measurement points on the first graph with the scattered light intensity I1i as the vertical axis and the scattered light intensity I2j as the horizontal axis, and on the second graph with the scattered light intensity I1i as the vertical axis and the shadow size D3k as the horizontal axis (S470).

[0178] Specifically, the image processing unit 7 generates a first graph plotting measurement points for particles that have values ​​only for scattered light intensities I1i and I2j (i.e., tiny particles whose shadow size is less than a predetermined threshold), and a second graph plotting measurement points for all other particles (i.e., particles whose shadow size is above the predetermined threshold). Additionally, the image processing unit 7 obtains the predicted theoretical correlation curves for the predetermined sample from the storage unit 10 and overlays them onto these graphs.

[0179] Furthermore, there are various methods for setting the threshold in step S470. For example, a first method is to set a limit value that enables the identification of particle size from the shadow image as a reference. Another method, for example, is to set a particle size where the difference between the scattered light intensity I1i and the scattered light intensity I2j is below the resolution, provided that the scattered light intensity characteristics of the particles of the measurement object can be predicted in advance.

[0180] Next, similarly to the first and second embodiments, the image processing unit 7 uses the first and second images to calculate the particle size distribution and identify the material based on each image (step S480). Furthermore, the image processing unit 7 terminates the process after performing material identification and calculating the particle size distribution.

[0181] The above describes the image analysis and processing of the camera and captured images in this embodiment.

[0182] According to such a particle measuring device 100, particle size measurement and material identification can be performed simultaneously with a more cost-effective structure. In particular, by selecting an appropriate pattern type corresponding to the particle size, the particle measuring device can expand the range of measurable particle sizes.

[0183] <Fourth Implementation>

[0184] Figure 16 This is a flowchart illustrating an example of the refractive index estimation process in the fourth embodiment. The particle measuring apparatus 100 of this embodiment is characterized by its ability to estimate the refractive index of a sample whose refractive index is unknown. Furthermore, the basic structure of the particle measuring apparatus 100 is the same as that of the particle measuring apparatus 100 of the first embodiment.

[0185] At the start of the process, the particle measuring device 100 performs the same processing as steps S200 to S220 of 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).

[0186] Next, the image processing unit 7 calculates the refractive index of the particles contained in the sample by searching for and measuring the theoretical correlation curve corresponding to the material type of the sample. Specifically, the image processing unit 7 sets an initial value for the refractive index (step S620) and generates a theoretical correlation curve on the graph obtained by plotting the measurement points (on a graph with the vertical axis representing the intensity of scattered light and the horizontal axis representing the size of the shading) (step S630).

[0187] Furthermore, the image processing unit 7 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). Additionally, the image processing unit 7 determines whether the error is below a specified threshold (S650).

[0188] Then, if it is determined that the error is not below the threshold ("No" in step S650), the image processing unit 7 sequentially changes the set value of the refractive index (step S660), and returns the process to step S630. On the other hand, if it is determined that the error is below the threshold ("Yes" in step S650), the image processing unit 7 calculates the refractive index corresponding to the material type of the sample being measured from the set value (step S670). Furthermore, when the image processing unit 7 calculates the refractive index, the process ends.

[0189] The above explains the refractive index calculation process of the fourth embodiment.

[0190] Based on such a particle measuring device, the refractive index of particles in a sample with an unknown refractive index can be estimated using a more inexpensive structure.

[0191] Alternatively, the analysis and processing in this embodiment can also utilize the structure of the particle measuring device of 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 wavelength of the other light can be calculated with high accuracy.

[0192] Furthermore, in the first to third embodiments described above, the image processing unit 7 may also output a graph showing both the measurement points and the theoretical correlation curve based on Mie scattering theory to a display connected to the particle measuring device 100. This allows the user to visually confirm the distribution of each particle contained in the sample by referring to the graph representing the measurement status. Additionally, by plotting several representative particle sizes on the theoretical correlation curve, the user can more easily visualize the distribution.

[0193] Furthermore, the present invention is not limited to the above-described embodiments and modifications, but includes various modifications within the scope of the same technical concept. For example, the above embodiments are described in detail for ease of understanding of the present invention and are not limited to having all the structures described. Additionally, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and structures of other embodiments can be added to the structure of one embodiment. Furthermore, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0194] Furthermore, the control lines and information lines shown in the above description are those deemed necessary for the purpose of explanation, and do not necessarily represent all control lines and information lines on the product. In fact, it can be assumed that almost all structures are interconnected.

[0195] Explanation of reference numerals in the attached figures

[0196] 100…particle measuring device, 1…first light source, 2…second light source, 3…measuring unit, 4…microscope, 5…camera unit, 6…light shield, 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…computing device, 120…main storage device, 130…auxiliary storage device, 140…communication device, 150…bus, N…network.

Claims

1. A particle measuring device, characterized in that, include: A first and second light source of parallel light are used to irradiate a sample containing particles of a specified material. The camera unit captures an image of the particle's scattered light obtained from the parallel light illuminating the first light source, and an image of the particle's shadow obtained from the parallel light illuminating the second light source. and The image processing unit determines the theoretical correlation curve closest to the measurement point based on the distance relationship between the theoretical correlation curve and the measurement point. The theoretical correlation curve represents the theoretical value of the correspondence between the scattered light intensity and particle size of the particle at each specified scattering angle for each material type. The measurement point represents the correspondence between the scattered light intensity and shadow size of the particle determined based on the scattered light image and the shadow image. The image processing unit performs material identification based on the material type corresponding to the determined theoretical correlation curve and calculates the particle size of the particle in the sample based on the particle size corresponding to the measurement point represented by the determined theoretical correlation curve.

2. The particle measuring device as described in claim 1, characterized in that: The illumination angle of the parallel light emanating from the first light source is set such that the scattered light scattered by the particles at a scattering angle below a predetermined scattering angle can be received by the camera unit.

3. The particle measuring device as described in claim 1, characterized in that: It also has an illumination angle adjustment mechanism for adjusting the illumination angle of the parallel light irradiated from the first light source.

4. The particle measuring device as described in claim 1, characterized in that: The image processing unit calculates the refractive index of the unknown particle based on the theoretical correlation curve generated according to a predetermined refractive index as a theoretical value corresponding to the material of the unknown particle, and the positional relationship between the curve and the measurement point, wherein the measurement point represents the correspondence between the scattered light intensity and the shadow size determined according to the scattered light image and the shadow image.

5. The particle measuring device as described in claim 1, characterized in that: It also has an illumination window driving unit that drives the parallel light irradiated from the second light source in the direction of the optical axis to suppress the flow of the sample in the sample container, and is provided with an illumination window that allows the parallel light irradiated from the first light source and the second light source to enter.

6. The particle measuring device as described in claim 1, characterized in that: It also has a valve for controlling the injection and discharge of the sample into the sample container. The valve controls the flow of the sample within the sample container to suppress particle movement.

7. The particle measuring device as described in claim 1, characterized in that: It also has a cleaning mechanism disposed in a sample container capable of injecting the sample, which is capable of spraying cleaning fluid onto the sample attached to a pair of windows irradiated by the first light source and the second light source with the parallel light.

8. The particle measuring device as described in claim 1, characterized in that: The theoretical correlation curve is generated based on Mie scattering theory, using the refractive index of the particles contained in the sample as the input parameter.

9. A particle measuring device, characterized in that, include: A first light source and a second light source, each with a different wavelength, are used to irradiate a sample containing particles of a specified material. The camera unit captures a first image of the particle's scattered light obtained by parallel light of a first wavelength irradiated from the first light source, and a second image of the particle's scattered light obtained by parallel light of a second wavelength irradiated from the second light source. and The image processing unit determines the theoretical correlation curve closest to the measurement point based on the distance relationship between the theoretical correlation curve and the measurement point. The theoretical correlation curve represents the theoretical values ​​of the scattered light intensities of different wavelengths of the particle at various specified scattering angles for each material type. The measurement point represents the correspondence between the first and second scattered light intensities of the particle determined based on the first and second scattered light images. The image processing unit performs material identification based on the material type corresponding to the determined theoretical correlation curve, and calculates the particle size of the particle in the sample based on the relationship between the refractive index of the material type corresponding to the determined theoretical correlation curve, the first and second scattered light intensities corresponding to the measurement point represented by the theoretical correlation curve, and the scattering angle corresponding to the theoretical correlation curve.

10. The particle measuring device as described in claim 9, characterized in that: The camera unit captures a first scattered light image and a second scattered light image obtained by parallel light of a first wavelength and parallel light of a second wavelength simultaneously irradiated by the first light source and the second light source, respectively.

11. The particle measuring device as described in claim 9, characterized in that: It also has a third light source for irradiating the sample containing particles of the specified material with the parallel light. The camera unit captures a shadow image of the particle obtained using parallel light irradiated from the third light source. The image processing unit, For particles whose size is less than the specified value, the first scattered light image and the second scattered light image are used to identify the material of the particle and calculate its size. For particles with a particle size above a specified value, the first scattered light image and the shadow image are used to identify the material of the particle and calculate its particle size.

12. A particle measurement method performed by a particle measuring device, characterized in that: The particle measuring device performs the following: The step of irradiating a sample containing particles of a specified material with parallel light from a first light source and a second light source; The camera step involves capturing an image of the particle's scattered light obtained from the parallel light illuminating the first light source, and an image of the particle's shadow obtained from the parallel light illuminating the second light source. and In the image processing step, the theoretical correlation curve closest to the measurement point is determined based on the distance relationship between the theoretical correlation curve and the measurement point. The theoretical correlation curve represents the theoretical value of the correspondence between the scattered light intensity and particle size of the particle at each specified scattering angle for each material type. The measurement point represents the correspondence between the scattered light intensity and shadow size of the particle determined based on the scattered light image and the shadow image. In this image processing step, material identification is performed based on the material type corresponding to the determined theoretical correlation curve, and the particle size of the particles in the sample is calculated based on the particle size corresponding to the measurement point represented by the determined theoretical correlation curve.

13. The particle measurement method as described in claim 12, characterized in that: In the image processing step, the refractive index of the unknown particle is estimated based on the theoretical correlation curve generated according to the theoretical value corresponding to the material of the unknown particle according to the specified refractive index, and the positional relationship with the measurement point, wherein the measurement point represents the correspondence between the scattered light intensity and the shadow size determined according to the scattered light image and the shadow image.

14. A particle measurement method performed by a particle measuring device, characterized in that: The particle measuring device performs the following: The step of irradiating a sample containing particles of a specified material with parallel light of different wavelengths from a first light source and a second light source; The camera step involves capturing a first image of the particle's scattered light obtained from parallel light of a first wavelength illuminated by the first light source, and a second image of the particle's scattered light obtained from parallel light of a second wavelength illuminated by the second light source. and In the image processing step, the theoretical correlation curve closest to the measurement point is determined based on the distance relationship between the theoretical correlation curve and the measurement point. The theoretical correlation curve represents the theoretical values ​​of the scattered light intensities of different wavelengths of the particle at various specified scattering angles for each material type. The measurement point represents the correspondence between the first and second scattered light intensities of the particle determined based on the first and second scattered light images. In this image processing step, material identification is performed based on the material type corresponding to the determined theoretical correlation curve. Furthermore, the particle size of the particle in the sample is calculated based on the relationship between the refractive index of the material type corresponding to the determined theoretical correlation curve, the first and second scattered light intensities corresponding to the measurement point represented by the theoretical correlation curve, and the scattering angle corresponding to the theoretical correlation curve.

15. The particle measurement method as described in claim 14, characterized in that: In the irradiation step, the parallel light is irradiated onto the sample containing particles of the specified material from a third light source. In the imaging step, a shadow image of the particle is captured using parallel light emanating from the third light source. In the image processing step, For particles whose size is less than the specified value, the first scattered light image and the second scattered light image are used to identify the material of the particle and calculate its size. For particles with a particle size above a specified value, the first scattered light image and the shadow image are used to identify the material of the particle and calculate its particle size.

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