JP2016099279A - Particle analyzer and particle analysis method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle analyzer and a particle analysis method that can distinguish a gas particle in a liquid sample more accurately.SOLUTION: An image of a particle in a liquid sample is photographed (step S101), a size of the particle is determined (S105), and a floating speed when the particle is a gas particle is calculated (step S106). Then, if the calculated floating speed is identical with a travel speed of the particle determined based of the photographed image (Yes in step S107), the particle is distinguished as a gas particle (step S108). Because a floating speed of a particle in a liquid sample differs among cases where a particle in a liquid sample is a gas particle, a solid particle, and a liquid particle, a gas particle in a liquid sample can be distinguished accurately by distinguishing gas particles based on a floating speed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a particle analysis apparatus and a particle analysis method for capturing an image of particles in a liquid sample and analyzing the particles based on the captured images.

  In recent years, research and use of fine bubbles such as micro bubbles and ultra fine bubbles have been actively conducted. Fine bubbles are fine bubbles having a bubble diameter of 100 μm or less, for example, those having a bubble diameter of 1 μm or more are called microbubbles, and those having a bubble diameter of less than 1 μm are called ultrafine bubbles.

  Fine bubbles are expected to have various effects such as a cleaning effect and a sterilizing effect. For example, if various facilities are cleaned using fine bubbles in factories, plants, public toilets, etc., the amount of detergent used can be reduced. Therefore, a cleaning method using fine bubbles has attracted attention as a new environmentally friendly cleaning method.

  The relationship between the characteristics and effects of the fine bubbles as described above depends on the bubble diameter and bubble amount (concentration) of the fine bubbles. Therefore, a technique for measuring the bubble size distribution (particle size distribution) of fine bubbles using a laser diffraction / scattering type particle size distribution measuring apparatus has been proposed (for example, see Patent Document 1 below).

  However, the liquid sample to be measured may contain solid particles such as dust or soil, and liquid particles such as oil or emulsion, in addition to fine bubbles. In such a case, in a method of measuring the bubble size distribution of fine bubbles using a laser diffraction / scattering type particle size distribution measuring device, gas particles (bubbles) such as fine bubbles, solid particles, and liquid particles Cannot be identified, and the bubble size distribution of the fine bubbles may not be accurately measured.

  Therefore, it is conceivable to take an image of particles in the liquid sample and identify whether each particle is a gas particle based on the taken image (for example, see Patent Document 2 below). This Patent Document 2 discloses a configuration in which, if a photographed particle image is spherical, the particle is identified as a bubble.

JP 2007-263876 A JP 2002-71547 A

  However, the particles in the liquid sample may include spherical solid particles or liquid particles. For example, since liquid particles such as oil or emulsion have a spherical shape, when a liquid sample containing such liquid particles is a measurement target, the liquid particles may be mistakenly identified as gas particles.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a particle analysis apparatus and a particle analysis method that can more accurately identify gas particles in a liquid sample.

  The particle analyzing apparatus according to the present invention includes an image capturing unit, a particle size determining unit, a flying speed calculating unit, a moving speed determining unit, and a gas particle identifying unit. The image capturing unit captures an image of particles in the liquid sample. The particle size determination unit determines the size of the particles in the liquid sample based on the image captured by the image capturing unit. The levitation speed calculation unit calculates the levitation speed when the particle is a gas particle based on the particle size determined by the particle size determination unit. The moving speed determination unit determines the moving speed of the particles based on the image captured by the image capturing unit. The gas particle identifying unit identifies the particle as a gas particle when the particle ascent rate calculated by the ascent rate calculating unit coincides with the particle moving rate determined by the moving rate determining unit. .

  According to such a configuration, by taking an image of the particles in the liquid sample and determining the size of the particles, the ascending speed when the particles are gas particles can be calculated. If the calculated flying speed matches the moving speed of the particle determined based on the captured image, the particle can be identified as a gas particle. The particles in the liquid sample are gas particles and the solid particles or the liquid particles have different ascent rates of particles in the liquid sample, so that the gas particles are identified based on the ascent rate as described above. This makes it possible to more accurately identify gas particles in the liquid sample.

  The particle analysis apparatus may further include a spherical particle identification unit that identifies spherical particles from the liquid sample based on the image photographed by the image photographing unit. In this case, the particle size determination unit may determine the diameter of the particles identified as spherical by the spherical particle identification unit. In addition, the ascent rate calculation unit may calculate the ascent rate when the particle is a gas particle based on the particle diameter determined by the particle size determination unit.

  According to such a configuration, for only the spherical particles identified from the liquid sample, the ascent rate when the particles are gas particles is calculated based on the diameter, and the ascent rate is calculated based on the calculated ascent rate. It can be identified whether the particle is a gas particle. Since the gas particles are spherical, it is possible to prevent particles other than the sphere from being mistakenly identified as gas particles by identifying whether the particles are gas particles only for spherical particles. In addition, it is possible to prevent the calculation of the ascent rate for particles that are not gas particles from being performed wastefully. Therefore, the gas particles in the liquid sample can be identified more accurately, and an improvement in the processing speed can be expected.

  The ascent speed calculation unit may calculate the ascent speed based on Stokes' formula.

  According to such a configuration, by using the diameter of a particle identified as a sphere, the flying speed of the particle can be easily calculated based on the Stokes equation. Thereby, since the process at the time of identifying the gas particle in a liquid sample can be simplified, a processing speed can be improved.

  The particle analysis method according to the present invention includes an image capturing step, a particle size determining step, a flying speed calculating step, a moving speed determining step, and a gas particle identifying step. In the image capturing step, an image of particles in the liquid sample is captured. In the particle size determination step, the size of the particles in the liquid sample is determined based on the image captured in the image capturing step. In the ascent speed calculation step, the ascent speed when the particles are gas particles is calculated based on the particle size determined in the particle size determination step. In the moving speed determining step, the moving speed of the particles is determined based on the image captured in the image capturing step. In the gas particle identification step, the particle is identified as a gas particle when the particle ascent rate calculated in the ascent rate calculating step matches the particle move rate determined in the move rate determining step. .

  The particle analysis method may further include a spherical particle identifying step of identifying spherical particles from the liquid sample based on the image captured by the image capturing step. In this case, in the particle size determination step, the diameter of the particles identified as spherical by the spherical particle identification step may be determined. In the ascent speed calculating step, the ascent speed when the particle is a gas particle may be calculated based on the particle diameter determined in the particle size determining step.

  In the ascent speed calculating step, the ascent speed may be calculated based on Stokes' formula.

  According to the present invention, the gas particles in the liquid sample can be more accurately identified by identifying the gas particles based on the flying speed.

It is the schematic which showed the structural example of the particle | grain analyzer which concerns on one Embodiment of this invention. It is a figure for demonstrating the aspect at the time of analyzing a particle | grain based on the image image | photographed with the camera. It is a figure for demonstrating the aspect at the time of analyzing a particle | grain based on the image image | photographed with the camera. It is a figure for demonstrating the aspect at the time of analyzing a particle | grain based on the image image | photographed with the camera. It is the block diagram which showed the structural example of the control part. It is the flowchart which showed the flow of the process by the control part at the time of analyzing the particle | grains in a liquid sample.

  FIG. 1 is a schematic diagram illustrating a configuration example of a particle analyzing apparatus 1 according to an embodiment of the present invention. The particle analyzing apparatus 1 includes a camera 11 as an image capturing unit. By capturing the particles in the liquid sample in the container 2 using the camera 11, particle processing is performed on the captured image. Analysis can be performed. Since a fine bubble with a small size is an object to be measured, it is desirable to attach a microscope to the camera 11 and magnify and photograph the particles in the container 2.

  The liquid sample in the container 2 is a sample using, as a medium, any liquid such as alcohol or oil in addition to water. Such a liquid sample may be prepared by being accommodated in the container 2 off-line. For example, a liquid sample flowing inside a pipe (not shown) or the like is sampled in the container 2 online. May be prepared. However, as long as the liquid sample is captured by the camera 11 in a stable state, the liquid sample is not limited to the configuration prepared in a state of being accommodated in the container 2.

  The liquid sample includes fine bubbles made of fine bubbles having a bubble diameter of 100 μm or less, for example. Specifically, at least one of ultrafine bubbles having a bubble diameter of less than 1 μm and microbubbles having a bubble diameter of 1 μm or more is contained in the liquid sample as gas particles (bubbles). The gas constituting the gas particles may be air or a gas other than air, such as ozone or hydrogen. In addition, the liquid sample may contain not only gas particles but also solid particles such as dust or earth, and liquid particles such as oil or emulsion.

  In addition to the camera 11, the particle analysis device 1 includes a control unit 12, an operation unit 13, a display unit 14, and a storage unit 15, for example. The control unit 12 includes a CPU (Central Processing Unit), for example, and is electrically connected to the camera 11, the operation unit 13, the display unit 14, and the storage unit 15.

  The operation unit 13 includes, for example, a keyboard or a mouse, and an operator can perform an input operation by operating the operation unit 13. The display unit 14 is configured by, for example, a liquid crystal display, and the operator can perform work while confirming the display content of the display unit 14. The storage unit 15 is configured by, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk, or the like.

  2A to 2C are diagrams for describing an aspect when analyzing particles based on an image 111 photographed by the camera 11. In the example of FIG. 2A, the image 111 captured by the camera 11 includes gas particles 112 and particles 113 and 114 other than gas. In this case, the gas particles 112 are spherical, but the non-gas particles 113 and 114 include both spherical particles 113 and non-spherical particles 114.

  First, if the spherical particles 112 and 113 are identified based on the image 111, the non-spherical particles 114 can be excluded as shown in FIG. 2B. Since the non-spherical particles 114 are not gas particles, by excluding such particles 114, it is possible to select particles that are highly likely to be gas particles.

  FIG. 2C is an image taken after a certain time from the shooting in FIG. 2B. The spherical particles 112 and 113 selected as described above float or settle in the medium. That is, as shown in FIG. 2C, particles 112 having a density lower than that of the medium float in the medium, and particles 113 having a density higher than that of the medium settle in the medium. The moving speed (floating speed or settling speed) of each particle 112, 113 depends on its diameter and density. Therefore, based on the moving speed of each particle 112, 113, it becomes possible to identify whether each particle 112, 113 is a gas particle.

  Such identification of gas particles is possible for both ultrafine bubbles and microbubbles. However, if the number of pixels of the camera 11 necessary for determining whether or not the particles are spherical is considered, This is particularly effective for identifying bubbles. When identifying extremely small gas particles such as ultrafine bubbles, Brownian motion occurs in the gas particles, and therefore it is preferable to apply a centrifugal force to the liquid sample.

  As described above, when a centrifugal force is applied to the liquid sample, the gas particles in the liquid sample are levitated by centrifugation rather than by natural levitation. In this case, for example, when the centrifugal force is applied to the liquid sample and the camera 11 performs imaging in synchronization with the liquid sample, the ascending speed can be calculated based on the captured image. However, not only fine bubbles but also gas particles other than fine bubbles (gas particles having a bubble diameter larger than 100 μm) can be identified.

  FIG. 3 is a block diagram illustrating a configuration example of the control unit 12. When the CPU executes the program, the control unit 12 causes the spherical particle identification unit 121, the particle size determination unit 122, the ascent speed calculation unit 123, the movement speed determination unit 124, the gas particle identification unit 125, and the bubble diameter distribution measurement unit 126. Function as such.

  The spherical particle identification unit 121 performs a process of identifying spherical particles from the liquid sample based on the image taken by the camera 11. Specifically, a particle is specified from an image photographed by the camera 11, and when the particle image is circular or substantially circular, the particle is identified as a spherical particle. That is, in the present embodiment, not only a perfect spherical shape but also a particle having a high possibility of being a spherical shape is identified as a spherical particle.

  The spherical particles as described above can be identified, for example, by comparing the dimensions in a plurality of directions with respect to the image of each particle. For example, the vertical and horizontal dimensions of each particle are compared, and if the dimensions are the same, or if the difference in dimensions is below a certain threshold, the particle is identified as a spherical particle. be able to. However, it is not limited to the configuration in which the vertical and horizontal dimensions of each particle are compared, and in addition to or instead of these, a configuration in which the diagonal dimensions are compared may be used. The configuration may be such that spherical particles are identified by other methods.

  The particle size determination unit 122 performs processing for determining the size of the particles in the liquid sample based on the image photographed by the camera 11. In the present embodiment, the particle size determining unit 122 determines the diameter of the particles identified as spherical by the spherical particle identifying unit 121.

For example, in a configuration in which spherical particles are identified by comparing the vertical and horizontal dimensions of each particle, when the vertical dimension is L1 and the horizontal dimension is L2, the following The diameter D of the particle can be calculated from the equation (1). Thus, the diameter of the particle | grains can be determined by calculating the average value of the dimension of the particle | grains identified as the spherical form in the multiple directions.
D = (L1 + L2) / 2 (1)

The ascending speed calculation unit 123 performs a process of calculating the ascending speed v ₁ when the particle is a gas particle based on the particle size determined by the particle size determination unit. In the present embodiment, the particle diameter calculated in the above-described manner is substituted into the arithmetic expression stored in the storage unit 15, whereby the ascent speed v ₁ when the particle is a gas particle is obtained. It is calculated.

As the arithmetic expression, for example, the particle flying speed v ₁ (m / s) can be calculated by using a Stokes expression as shown in the following expression (2). D _p is the particle diameter (m), ρ _p is the particle density (kg / m ³ ), ρ _f is the medium density (kg / m ³ ), g is the gravitational acceleration (m / s ² ), and μ is It is the viscosity (Pa · s) of the medium. As the particle density ρ _p , the actual gas density when the particle is a gas particle may be substituted, but if the density of the medium is sufficiently high, the gas density should be close to “0”. Therefore, “0” may be substituted.
^{_{v 1 = D p 2 (ρ}} p -ρ f) g / 18μ ··· (2)

The moving speed determination unit 124 performs a process of determining the moving speed v _{2 of the} particles based on the image taken by the camera 11. For example, a plurality of (for example, two) images can be taken by the camera 11 at a constant time interval, and the particle moving speed v ₂ can be determined based on the particle moving distance in the series of images. At this time, it is necessary to specify that a certain target particle in the series of images is the same particle. For this specification, it can be determined that the target particle is on the same vertical line, the size of the target particle calculated from a series of images is the same, and the like. Moving velocity v ₂ of each particle is determined in this way, becomes a floating rate when the density of the particles are smaller than the density of the medium, the sedimentation rate if the density of the particles is greater than the density of the medium .

The gas particle identification unit 125 performs a process of comparing the particle flying speed v ₁ calculated by the flying speed calculation unit 123 with the particle moving speed v ₂ determined by the moving speed determination unit 124. Identifies whether or not is a gas particle. Specifically, when the ascending speed v ₁ and the moving speed v ₂ match, the particle is identified as a gas particle. At this time, if the flying speed v ₁ and the moving speed v ₂ are the same, or, if the difference between the flying velocity v ₁ and the moving speed v ₂ is equal to or less than a predetermined threshold value, the flying velocity v ₁ and the moving velocity v ₂ May be determined to match.

  The bubble diameter distribution measuring unit 126 is based on the number of particles identified as gas particles (bubbles) by the gas particle identifying unit 125 and the diameter (bubble size) of each gas particle determined by the particle size determining unit 122. The bubble diameter distribution of the gas particles contained in the medium is measured. When fine bubbles are included in the liquid sample, the bubble size distribution of the fine bubbles is obtained. The measured bubble size distribution is displayed on the display unit 14, and the operator can evaluate the effect of fine bubbles based on the bubble size distribution displayed on the display unit 14. It is also possible to identify the fine bubble size distribution that best suits the purpose and target, and contribute to the establishment of an authentication system.

  FIG. 4 is a flowchart showing the flow of processing by the control unit 12 when analyzing particles in the liquid sample. When analyzing the particles in the liquid sample, first, an image of the particles in the liquid sample is captured by the camera 11 (step S101: image capturing step). At this time, a plurality of (for example, two) images are taken continuously at a constant time interval, and the moving speed of each particle is determined based on the moving distance of each particle in the series of images (step). S102: Movement speed determination step).

  Further, spherical particles are identified from the liquid sample based on the photographed image (step S103: spherical particle identification step). And about the particle | grains identified as spherical (Yes in step S104), the diameter of the particle is determined (step S105: particle size determination step), and the particle is a gas particle based on the determined particle diameter. The flying speed in a certain case is calculated (step S106: flying speed calculation step).

  When the flying speed calculated in step S106 matches the moving speed of the particles determined in step S102 (Yes in step S107), the particles are identified as gas particles (step S108: gas particle identification step). ). In this way, the processing of steps S104 to S108 is performed for all particles in the captured image, and if the processing for all particles is completed (Yes in step S109), the particles identified as gas particles are detected. Based on the number and the diameter of each gas particle, the bubble diameter distribution of the gas particles contained in the medium is measured (step S110: bubble diameter distribution measuring step).

  As described above, in this embodiment, an image of particles in a liquid sample is taken (step S101), and the size of the particles is determined (step S105), so that the ascent speed when the particles are gas particles. Can be calculated (step S106). If the calculated flying speed matches the moving speed of the particle determined based on the captured image (Yes in step S107), the particle can be identified as a gas particle (step S108). . The particles in the liquid sample are gas particles and the solid particles or the liquid particles have different ascent rates of particles in the liquid sample, so that the gas particles are identified based on the ascent rate as described above. This makes it possible to more accurately identify gas particles in the liquid sample.

  In particular, in the present embodiment, for only spherical particles identified from the liquid sample (Yes in step S104), the ascent rate when the particles are gas particles is calculated based on the diameter (step S106), It is possible to identify whether or not the particle is a gas particle based on the calculated ascent rate (steps S107 and S108). Since the gas particles are spherical, it is possible to prevent particles other than the sphere from being mistakenly identified as gas particles by identifying whether the particles are gas particles only for spherical particles. In addition, it is possible to prevent the calculation of the ascent rate for particles that are not gas particles from being performed wastefully. Therefore, the gas particles in the liquid sample can be identified more accurately, and an improvement in the processing speed can be expected.

  Furthermore, in this embodiment, by using the diameter of a particle identified as a sphere, the flying speed of the particle can be easily calculated based on the Stokes equation. Thereby, since the process at the time of identifying the gas particle in a liquid sample can be simplified, a processing speed can be improved.

  The particle analyzing apparatus 1 as in the present embodiment may be configured as an analyzing apparatus for analyzing particles in a liquid sample. In this case, for example, by providing the camera 11 in an analyzer such as an electron microscope, particle analysis may be realized by image processing of the control unit 12 provided in the analyzer.

  In the above embodiment, the configuration in which the flying speed of the particles is calculated based on the Stokes equation has been described. However, the present invention is not limited to such a configuration, and is a configuration in which the flying speed of particles is calculated by calculation using other formulas such as formulas obtained based on Stokes formulas and formulas other than Stokes formulas. Also good.

  Moreover, in the above embodiment, after identifying spherical particles from the liquid sample, the ascent rate when the particles are gas particles is calculated based on the diameter of the particles identified as the spherical shape. The configuration has been described. However, when the particle ascent rate can be calculated without using the particle size, or when a large number of particles are to be measured at the expense of some accuracy, spherical particles are removed from the liquid sample. It is also possible to omit the identifying step. In this case, a configuration in which the spherical particle identification unit 121 is not provided in the particle analysis device 1 may be employed.

DESCRIPTION OF SYMBOLS 1 Particle analyzer 2 Container 11 Camera 12 Control part 13 Operation part 14 Display part 15 Storage part 111 Image 112 Gas particle 112-114 Particle 121 Spherical particle identification part 122 Particle size determination part 123 Ascent rate calculation part 124 Movement speed determination part 125 Gas particle identification unit 126 Bubble size distribution measurement unit

Claims (6)

An image capturing unit for capturing an image of particles in a liquid sample;
A particle size determination unit that determines the size of particles in the liquid sample based on the image captured by the image capturing unit;
Based on the particle size determined by the particle size determination unit, a flying speed calculation unit that calculates a flying speed when the particle is a gas particle;
A moving speed determining unit that determines a moving speed of the particles based on an image captured by the image capturing unit;
A gas particle identification unit that identifies a particle as a gas particle when the particle ascent rate calculated by the ascent rate calculation unit matches the particle movement rate determined by the movement rate determination unit; A particle analyzer characterized by that. A spherical particle identification unit for identifying spherical particles from the liquid sample based on the image photographed by the image photographing unit;
The particle size determination unit determines the diameter of the particles identified as spherical by the spherical particle identification unit,
2. The particle analysis according to claim 1, wherein the ascent rate calculation unit calculates an ascent rate when the particle is a gas particle based on the particle diameter determined by the particle size determination unit. apparatus.   The particle analysis apparatus according to claim 2, wherein the ascent speed calculation unit calculates the ascent speed based on a Stokes equation. An image capturing step for capturing an image of particles in the liquid sample;
A particle size determination step for determining the size of particles in the liquid sample based on the image captured by the image capturing step;
Based on the particle size determined by the particle size determination step, a flying speed calculation step for calculating a flying speed when the particle is a gas particle;
A moving speed determining step for determining a moving speed of the particles based on the image captured by the image capturing step;
A gas particle identification step for identifying the particle as a gas particle when the particle ascent rate calculated in the ascent rate calculation step matches the particle move rate determined in the move rate determining step. A particle analysis method characterized by the above. A spherical particle identifying step of identifying spherical particles from the liquid sample based on the image captured by the image capturing step;
In the particle size determination step, the diameter of the particles identified as spherical by the spherical particle identification step is determined,
5. The particle analysis according to claim 4, wherein, in the ascent rate calculation step, the ascent rate when the particle is a gas particle is calculated based on the particle diameter determined in the particle size determination step. Method.   6. The particle analysis method according to claim 5, wherein, in the ascent speed calculation step, the ascent speed is calculated based on Stokes' formula.

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