JP2000074816A - Particle analytical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a particle analytical device capable of measuring securely the volume and the number of particles, and capable of three-dimensional analysis from the volume and the projected area of the particles. SOLUTION: This particle analytical device is equipped with a particle detecting device 8 for measuring the volume and the number of particles 5 by measuring the change of an electric resistance between both electrodes at the time of passing of the particles 5 through an opening 3, after arranging a tube 2 having the opening 3 in electrolytic solution 4 and after installing electrodes 6, 7 in the inside and the outside of the tube 2, a stroboscope 11 for illuminating the opening 3 at the timing of the change of the electric resistance, a camera 12 for imaging the particles 5 illuminated by the stroboscope 11, and a picture image processing device 16 for executing image analysis of the particles 5 from the picture image imaged by the camera 12 and the particle data detected by the particle detecting device 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle analyzer for electrically capturing particles dispersed in an electrolyte and optically capturing and analyzing the particles.

[0002]

2. Description of the Related Art Several methods have been used for measuring the shape and quantity of metal powder and toner particles.
The Coulter method is well known as a method for electrically measuring such particles, and FIG. 4 shows a particle measuring apparatus using the Coulter method. In the Coulter method, as shown in FIG. 4, an electrolytic solution 4 in which particles are dispersed is placed in a container 1, and a tube 2 provided with an opening 3 through which particles 5 can pass is arranged.
The electrodes 6 and 7 are provided inside and outside the
The inside is filled with the electrolytic solution 4 and the electrolytic solution 4 is sucked from above. The particles 5 pass through the opening 3 and enter the tube 2 through the opening 3 together with the electrolytic solution 4. At this time, the electrolyte 4 in the opening 3 decreases by an amount corresponding to the volume of the particles 5, and the electric resistance of the opening 3 increases in proportion to the amount of the eliminated electrolyte. Therefore, a change in electric resistance proportional to the volume of the particles 5 occurs in the opening. When a constant current is applied between the electrodes 6 and 7, the amount of voltage change between the electrodes 6 and 7 increases in proportion to the amount of change in the electrical resistance of the opening 3. The volume of the particle can be measured from the voltage change amount, and the particle opening 3 can be determined from the number of voltage changes.
Can be counted. This is called the Coulter principle, and a device that measures particles using this method is called a Coulter counter.

In FIG. 4, reference numeral 9 denotes a first monitor,
This shows the fluctuation of the voltage when the individual particles 5 pass. The integral value of this waveform represents a value proportional to the volume of the particle 5. Reference numeral 10 denotes a second monitor, which shows a histogram (particle size distribution) of the volume distribution of particles that have passed for a certain period of time based on the number of voltage changes and the integral value of the voltage waveform. The horizontal axis shows the volume of the particles, and the vertical axis shows the number of particles.

FIG. 5 is a view showing a sample and an image pickup device of an apparatus for measuring the size and number of particles by taking an image of particles dispersed in a liquid with a camera and analyzing the image. A sample made of a liquid containing particles flows in the center of a transparent flow path called a sheath flow cell, and a transparent liquid called a sheath liquid flows on both sides of the sample so that the sample flows in the center. Arrange the strobe and CCD camera across the sheath flow cell,
An objective lens is placed in front of the camera to obtain an enlarged image of the particles. The strobe emits light at fixed time intervals, and the sample at this time is photographed by a CCD camera. The obtained image is analyzed by an image processing device (not shown), and the two-dimensional shape and the number of particles are measured.

[0005]

However, in the case of the coulter counter shown in FIG. 4, when two particles enter the opening in an overlapping manner, the volume and the number may be measured as one particle. I do. Further, in the case of the apparatus shown in FIG. 5, since a strobe light is emitted at regular time intervals, for example, every 1/30 second to take an image, a screen without particles or an overly overlapped image is obtained. In some cases, the size and number of particles cannot be analyzed by the image processing device.

The present invention has been made in view of the above-mentioned problems, and provides a particle analyzing apparatus capable of reliably measuring the volume and number of particles and performing three-dimensional analysis from the volume and projected area of the particles. The purpose is to do.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, a tube having an opening in an electrolytic solution is provided, electrodes are provided inside and outside the tube, and particles pass through the opening. A particle detector that measures the change in electric resistance between the two electrodes to measure the volume and number of particles, a strobe that illuminates the opening at a timing when the electric resistance changes, and particles illuminated by the strobe And an image processing device that performs image analysis of particles from the image captured by the camera and the particle data detected by the particle detection device.

Since the strobe light is emitted when the electric resistance between the electrodes changes, an image of particles passing through the aperture can be obtained. Also, when a plurality of particles pass through the opening, a plurality of particles can be confirmed from the image. By excluding such data, the total volume of the plurality of particles can be set to the volume of one particle, Incorrect measurement of one particle can be prevented. In addition, the three-dimensional analysis of the particles can be performed by combining the two-dimensional image with the volume of the particles. Further, since the field of view of the camera is adjusted to the opening and the particles passing through the opening are photographed, a clear image of the particles can be obtained.

According to a second aspect of the present invention, the camera has a half mirror in the optical system, reflects light from the strobe by the half mirror, irradiates the particles, and captures the reflected light transmitted through the half mirror. I do.

[0010] By imaging the reflected light of the particles with a camera using a half mirror, not only the shape of the particles but also the color can be imaged, which is useful for analyzing the particles. For example, it is possible to reliably specify the particles from the difference in color.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of the particle analyzer of the first embodiment. Reference numeral 1 denotes a transparent container into which an electrolyte 4 in which particles 5 are dispersed is put. A transparent tube 2 is disposed in the container 1, an opening 3 through which particles 5 pass is provided at a lower portion, and an upper portion is connected to a hose connected to a pump for sucking an internal electrolyte 4. In addition, you may make it suction by the principle of a siphon. The size of the diameter of the opening 3 is in accordance with the particle 5 to be measured, for example, 15 μm for a small one and 2000 μm for a large one.
m and a wide range of particles. Particles having a diameter of about 2% to 60% of the diameter of the opening 3 can be measured.

A positive electrode 6 is provided in the tube 2 and a negative electrode 7 is provided in the container 1 outside the tube 2, and a constant current flows. The current flows between the electrodes 6 and 7 through the opening 3. The opening 3 is thick and has electrical resistance by itself. When the electrolyte 4 is sucked from the upper part of the tube 2, the particles 5 pass through the opening 3 together with the electrolyte 4. At this time, the amount of the electrolyte 4 corresponding to the volume of the particles 5 decreases, and the electric resistance of the opening 3 becomes a large value in proportion to the amount of the electrolyte 4 that has decreased. A constant current flows between the electrodes 6 and 7, and this resistance change appears as a voltage change.
Can be measured, and the number of particles 5 is measured from the number of voltage changes. The inside of the tube 2 may be a negative electrode, and the outside may be a positive electrode.

The coulter counter 8 has a computer, receives voltage change signals of both electrodes 6 and 7, integrates the voltage change waveform to determine the volume of the particles, counts the number of voltage changes, and counts the number of voltage changes for a certain period of time. The number of particles 5 passing through the opening 3 and the particle size distribution of the particles 5 can be output. The first monitor 9 shows the voltage change waveform of the particle 5 and the second monitor 10
Shows a histogram showing the distribution of the particles 5 according to the size. This device is commercially available.

The center line of the container 1 is sandwiched between the tube 2
A camera 12 equipped with a strobe 11 and a microscope 13 is disposed so as to pass through the opening 3. The trigger signal generator 14 receives voltage change signals from both electrodes 6 and 7 and outputs them as voltage pulses. This voltage pulse is strobe 1
1 light emission signal. The camera controller 15 controls the camera 12 and outputs an image captured by the camera 12 to the image processing / analysis device 16.

The image processing / analyzing device 16 receives the voltage pulse from the trigger signal generator 14 and outputs it to the strobe 11 as a strobe light emission signal. At this time, by setting the strobe light emission signal so as to emit light at the rising, falling, or the middle of the voltage pulse, the state before the particle 5 enters the opening 3, the state after passing through the opening 3, and the state during passing Etc. can be imaged.

The image processing / analysis device 16 inputs a particle analysis signal from the coulter counter 8 and image data from the camera 12 and analyzes the image. The imaging data is the projection shape of the particle 5, and the shape and area are analyzed. By using the volume data of the particle 5 from the coulter counter 8, three-dimensional analysis of the particle is also possible. For example, if the particle 5 is known to have a spheroidal shape or a cylindrical shape, the major and minor diameters of the ellipse and the diameter and length of the cylinder can be accurately analyzed.

The monitor 17 displays images captured by the camera 12 and analysis results in real time. 2A and 2B show a situation where the particles 5 pass through the opening 3, wherein FIG. 2A shows a situation before passing through the opening 3, FIG. 2B shows a situation after passing through the opening 3, and FIG. Show.

FIG. 3 shows a second embodiment. 1 denote the same components. The second embodiment is different from the first embodiment in that the first embodiment captures the transmitted light of the particles, whereas the second embodiment captures the reflected light. A half mirror 19 is provided in the optical system of the microscope 18 at an angle of 45 ° with respect to the optical axis 20.
When the irradiation light of the strobe 11 is irradiated from a direction perpendicular to 0,
The irradiation light reflected by the half mirror 19 is reflected by the particles 5,
The light passes through the half mirror 19 and is imaged by the CCD color camera 21. When the transmitted light shown in FIG. 1 is imaged, the color of the particles 5 cannot be obtained because the light is projected light, but by using reflected light as shown in FIG. 3, a clear color of the particles 5 can be obtained. This enables accurate analysis of the particles 5.

[0019]

As is apparent from the above description, the present invention uses the Coulter method (electrical resistance method) and the image processing analysis method, which are characterized by the conventional measurement of particles, by utilizing signals specific to the electric resistance method. In addition to realizing the superior analysis methods of both methods, three-dimensional analysis of particles based on data obtained by both methods is now possible. In addition, a state in which particles pass through the opening of the tube, which cannot be obtained by the electric resistance method, can be clearly imaged, and the analysis of the particles can be performed with high accuracy. By irradiating the illumination with the camera coaxially, a clear color image can be obtained. Further, since the status of the particles is displayed on the monitor screen in real time, erroneous measurement such as determining that a plurality of particles are one is also eliminated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a process in which particles pass through a tube opening.

FIG. 3 is a diagram showing a configuration of a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a conventional particle measuring apparatus based on the Coulter method.

FIG. 5 is a view for explaining a particle measuring apparatus using a conventional image processing analysis method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Tube 3 Opening 4 Electrolyte 5 Particles 6,7 Electrode 8 Coulter counter 9 First monitor 10 Second monitor 11 Strobe 12 Camera 13 Microscope 14 Trigger signal generator 15 Camera controller 16 Image processing / analysis device 17 Monitor 18 Microscope 19 Half mirror 20 Optical axis 21 CCD color camera

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Masaaki Kobayashi 2951-4 Ishikawa-cho, Hachioji-shi, Tokyo Inside Nireco Co., Ltd. 72) Inventor Hideaki Imai 1-1-10 Atago, Minato-ku, Tokyo Coulter Co., Ltd. (72) Inventor Yang 1-1-1 Atago, Minato-ku, Tokyo Coulter Co., Ltd. (72) Invention Person Takahiro Iida Inside Coulter Co., Ltd. 1-1-10 Atago, Minato-ku, Tokyo

Claims (2)

[Claims] 1. A tube having an opening in an electrolytic solution, electrodes provided inside and outside the tube, and a change in electric resistance between the electrodes when the particle passes through the opening is measured to measure the volume of the particle. A particle detection device that measures the number and a strobe that illuminates the opening at a timing when the electric resistance changes,
A camera for imaging particles illuminated by the strobe, and an image processing device for analyzing the image of the particles from the image captured by the camera and the particle data detected by the particle detection device. Particle analyzer. 2. The camera according to claim 1, wherein the camera has a half mirror in the optical system, reflects light from the strobe by the half mirror, irradiates the particles, and captures an image of the reflected light passing through the half mirror. The particle analysis device according to claim 1.