JPH11337470A - Flow-type particle image analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flow-type particle image analyzer by which specific particles existing at a very small density can be detected without applying a burden on an image processing operation, by installing a particle-image blurring means by which a quantity of irradiated light is increased more than in an ordinary case and by which the image of particles is blurred. SOLUTION: A sample liquid in a sampling cup 15 is sucked by a suction pipette 1 so as to be stored in a stirring chamber 3. The sample liquid is guided to a flow cell 5 by operating a syringe 4, and it is surrounded by a sheath liquid so as to flow inside the flow cell 5. The flow of the sample liquid is irradiated with pulsed light from an electronic flash 8, and the static image of particles is imaged by a video camera 10. When a particle-image blurring means increases the quantity of light of the electronic flash 8 more than in an ordinary case, small particles whose contour is unclear become an unclear particle image due to the diffraction phenomenon of light, and large particles whose contour is clear are imaged as a clear particle image. Since the image of particles other than an object to be measured is made unclear, specific particles can be detected without applying a burden on an image processing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow type particle image analyzer for analyzing particles based on an image obtained by imaging a flowing particle, and more particularly to a unique particle which is present in a very small amount from a large number of particles. Is suitably used in the field of detecting

[0002]

2. Description of the Related Art Fine ceramics, toners, paints, cosmetics and the like are products made from powder. All of these require powder uniformity. Among them, especially in fine ceramics, even a very small amount (several ppm) of coarse particles or aggregated particles causes fatal defects for ceramic products. Therefore, it is important to know whether coarse particles or aggregated particles are mixed in the raw material.

[0003] As a method for detecting coarse particles, there is a method using sieving. However, there are problems that a large amount of raw materials are required, that accurate weighing after sieving is difficult, that it takes time, and that accuracy is high.

On the other hand, as an automated apparatus, a sample liquid in which particles are suspended in a liquid is flowed around a sheath liquid through a flow cell, a particle image is captured, and information such as the number of particles and the particle diameter is based on the particle image. Are known. In order to detect coarse particles having a concentration of about several ppm using this apparatus, it is necessary to capture and process a large number of images in which a large number of particles are captured.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a flow type particle image analyzer capable of detecting a specific particle existing at a minute concentration without imposing a burden on image processing. And

[0006]

According to the present invention, there is provided a flow type particle image analyzer, comprising: a flow cell in which a sample liquid containing particles to be detected is surrounded by a sheath liquid and flows flat; An apparatus including an apparatus, an imaging apparatus for imaging irradiated particles, a processing apparatus for performing processing such as image processing and analysis on an obtained image, and an output apparatus for outputting a processing result, wherein an image of particles is unclear. And a means for blurring the particle image. The present invention
The specific particles contained in the test particles can be targeted for detection, and other ordinary particles normally contained can be excluded from detection. The term “specific particles” as used herein refers to particles having characteristics such as size, shape, and color different from those of normal particles, and is, for example, a coarse particle (an aggregate formed by aggregation of particles). To make the image of particles unclear means to lower the S / N ratio of the image than usual. The image of the particles not to be detected becomes unclear and can be easily removed, and since only the particles to be detected can be imaged, there is no need to perform image processing on all the particles. For this reason, even a very small amount of specific particles can be detected without imposing a burden on image processing.

Further, from the above viewpoint, it is preferable that the particle image blurring means for blurring the image of the particles is an optical means. This is because it is easy to blur the image of the particles. The particle image blurring means for blurring the image of the particles may be a means for increasing the irradiation light amount of the irradiation device more than usual. In this case, the particle image can be easily blurred by the light diffraction phenomenon due to the increase in the irradiation light amount. The particle image blurring means for blurring the image of the particles may be means for shifting the focus of the particles of the imaging device. In this case, the particle image can be easily blurred by focusing on the large particles and shifting the focus on the small particles. Alternatively, it is a means for attenuating a light image from particles provided between the flow cell and the imaging surface of the imaging device. In this case, by providing a filter between the flow cell and the imaging device, the particle image can be easily blurred. Further, it is preferable that the particle image blurring means for blurring the image of the particles is a fluid means. This is because it is easy to blur the image of the particles. By coloring the sheath liquid or using a solution with high turbidity,
The particle image can be blurred.

[0008]

1 and 2 show the construction of an embodiment of a flow type particle image analyzer according to the present invention. The sample liquid dispersed in the sample cup 15 is suctioned from the suction pipette 1, and after large dirt and agglomerates (diameters of test particles of 160 μm or more) are removed by the sample filter 2, the sample liquid is stored in the stirring chamber 3.

The stored sample liquid is guided into the flow cell 5 by operating the sheath syringe 4 while being stirred in the stirring chamber 3, and the sample liquid is pushed out at a constant flow rate from the tip of the sample nozzle 5a. At the same time, the sheath liquid is also sent from the sheath liquid bottle 6 to the flow cell 5 through the sheath liquid chamber 7, and the sample liquid is surrounded by the sheath liquid. As shown in FIG. It is squeezed, flows through the flow cell 5, and is discharged to the waste liquid chamber 14. In FIG. 2, the sample liquid flows in a flat flow that is wide in the front and back directions of the paper and narrow in the left and right directions.

By irradiating the sample liquid flow, which is narrowed flat, with pulse light periodically from the strobe 8 every 1/30 second, a still image of particles is obtained every 1/30 second. An image is captured by a video camera 10 via a lens 9.

If the flat surface of the sample liquid flow is imaged by the video camera 10, a particle image can be captured over the entire imaging area of the video camera 10, and a large number of particles can be imaged by one imaging. Furthermore, due to the hydrodynamic effect, the orientation of flat particles or elongated particles is easily aligned, and the characteristic parameters obtained by analyzing the particle images have small variations and good reproducibility.

An image signal from the video camera 10 is image-processed by an image processing device 11 and displayed on a monitor television 12. Reference numeral 13 denotes a keyboard and a mouse for performing various input operations and command operations.

FIG. 3 shows the procedure of image processing for a particle image every 1/30 second. In FIG. 3, the processing of S1 to S12 is executed.

The image signal is captured by the image processing device 11, A / D converted, and captured as image data (step S1). First, background correction is performed to correct the intensity unevenness (shading) of the irradiation light with respect to the sample liquid flow (step S2). Specifically, it is performed by comparing and calculating image data obtained by irradiating light when particles do not pass through the flow cell 5 and image data of an actual particle imaging screen. This processing is generally well-known as image processing.

Next, contour emphasis processing is performed as preprocessing for accurately extracting the contour of the particle image (step S3).
Specifically, a Laptian enhancement process is performed.

Next, the image data is binarized at a certain appropriate threshold level (step S4). Next, it is determined whether or not the binarized particle image is an edge point, and information indicating in which direction the edge point adjacent to the focused edge point is located, that is, a chain code is generated. (Step S5). Next, an edge trace of the particle image is performed with reference to the chain code, and the total number of pixels, the total number of edges, and the number of oblique edges of each particle image are obtained (step S6).

If an image processing apparatus capable of high-performance pipeline processing is used, the above image processing can be performed in real time on a screen imaged every 1/30 second. In this apparatus, the above-described image processing is repeatedly performed on a plurality of screens captured at a certain magnification, and the particle images cut out to a predetermined size are stored in the image memory of the image processing apparatus 11 (step S7).

When the imaging is completed (step S8), a circle equivalent diameter (granularity) and a circularity are calculated as characteristic parameters as follows (step S9). First, the projection area S and the perimeter L of each particle image are obtained from the total number of pixels, the total number of edges, and the number of oblique edges obtained for each particle image. Further, using the area S and the perimeter L, the equivalent circle diameter and the circularity are obtained.

After the characteristic parameters have been calculated for each particle image in this way, necessary scattergrams and histograms are created and displayed based on commands from the keyboard 13 (step S10, step S10). S11). The particle images cut out in step S7 are collectively displayed on the monitor television 12 for each size (step S12).

FIG. 4 shows the structure of the first embodiment of the particle image blurring means. In the configuration shown in FIG. 4, the light amount of the strobe 8 is changeable, and the light amount is made larger than usual (more preferably, the binarized threshold level is also made higher than usual), so that the outline is small. The particles become an unclear particle image due to the light diffraction phenomenon, and particles having a large outline are captured as a clear particle image. In the binarization in step S4 in FIG. 3, the small particles are deleted because they are unclear particle images.
Although not stored as image data, the large particles are stored as image data without being deleted because they are clear particle images, and subsequent image processing is performed.

FIG. 5 shows the relationship between the strobe brightness level and the detected particle concentration of large and small particles (particles / μl) when PSL (polystyrene latex) is used. At the normal strobe brightness level 160, the fine particles of the PSL having a diameter of 1.53 μm are over the image processing ability, and the PSL having a diameter of 5 μm is 24.
There are 180 PSLs with 3 pieces and a diameter of 10 μm. When the strobe brightness level is increased to 240, the diameter is 1.53 μm
The PSL having a diameter of 5 μm and the PSL having a diameter of 5 μm had a detection particle concentration of 0, and the PSL having a diameter of 10 μm had a detection particle concentration of 162, which was almost the same as the ordinary strobe luminance level. That is,
No particles having a diameter of 5 μm or less were detected, and only particles having a diameter of 10 μm or more could be imaged. The strobe luminance level is the intensity of the strobe light incident on the CCD camera as 2
The numerical value obtained by dividing 55 is shown.

Next, FIG. 6 shows the evaluation results of the ability to detect coarse particles in fine powder by mixing two types of PSL, which are particles having no impurities and having a uniform particle size. 1.53 diameter in 10 ml of 0.2 wt% aqueous solution of sodium hexametaphosphate
A solution to which 0.2 ml of PSL of 0.2 μm is added (about 1 million /
(μl), a sample adjusted so that the PSL having a diameter of 26 μm was about 1 / μl was measured at a strobe luminance level 240. Since the theoretical concentration is as low as 1 / μl, the measurement time is 2
When the particle concentration was evaluated at 0 times, the particle concentration was almost the same as the theoretical concentration, and the reproducibility was good. From this, 1
Even if the concentration is about 1 in μl, increase the measurement time,
It was found that the particle concentration can be measured with good reproducibility by increasing the number of detected particles.

Next, the evaluation results of the powders other than PSL are shown in FIG. Sodium hexametaphosphate 0.2w
Alumina particles having an average diameter of 15 μm (or silica particles having a diameter of 10 μm) were placed in 90 ml of a t% aqueous solution at 1 pp each.
m, 10 ppm, and 100 ppm, and dispersed in a solution to obtain alumina particles having an average diameter of 3 μm (or 1 μm).
The measurement was carried out by dispersing 10 wt% of silica particles (μm). For the coarse particle concentration of 1 ppm, in order to enhance the accuracy, the average value of 20 measurements and the average value of 5 other measurements were obtained. It can be seen that 15 μm alumina particles were detected regardless of the presence or absence of 3 μm alumina particles as fine powder particles. It can be seen that 10 μm silica particles were detected regardless of the presence or absence of 1 μm silica particles. It was also found that almost the same image was obtained irrespective of the difference in luminance level.

Next, the normal strobe luminance level is 160
At this time, a 1 ppm concentration mixture of 3 μm alumina particles, which are fine powder particles, and 15 μm alumina particles, which are coarse particles, was measured, and the captured particle images are shown in FIG. It can be seen that many 3 μm alumina particles of fine powder particles are imaged, and only a few 15 μm alumina particles of coarse particles are imaged. When the strobe luminance level was increased to 240, a mixture of 3 μm alumina particles and 15 μm alumina particles was measured, and the captured particle images are shown in FIG.
It can be seen that 3 μm alumina particles as fine powder particles were not imaged, and only large 15 μm alumina particles as coarse particles were imaged. As described above, by increasing the strobe brightness level, it becomes possible to image only the coarse particles contained in a very small amount in the particles to be detected and not to image the fine particles.

Next, the configuration of a second embodiment of the particle image blurring means is shown in FIG. In this case, the flow cell is configured to be movable with respect to the objective lens, and can be defocused with respect to the center of the flat sample flow. The state where the flat sample flow is focused is a. The flow cell is shifted with respect to the lens surface so that large particles are in focus and small particles are out of focus.
It was shown to. A state in which the front is out of focus (front pin) b, and a state in which the focus is out of focus (rear focus) c. In the binarization of step S4 in FIG. 3, the small particles are deleted because they are unclear particle images and are not stored as image data. However, the large particles are not deleted because they are clear particle images. It is stored as image data, and the subsequent image processing is performed.

FIG. 11 shows the configuration of a third embodiment of the particle image blurring means. In the configuration of FIG. 11, a filter for attenuating a light image is provided between the objective lens and the CCD camera, and the filter can select a color, a color density, and the like according to the type of the particles. With this filter,
Usually, particles are imaged as unclear particle images, and singular particles are imaged as particle images with clear contours. In the binarization in step S4 in FIG. 3, the normal particles are deleted because they are unclear particle images and are not stored as image data. However, the singular particles are not deleted because they are clear particle images. It is stored as image data, and the subsequent image processing is performed.

Next, in a fourth embodiment of the particle image blurring means, in FIG. 2, by using a colored or turbid sheath fluid, ordinary particles are imaged as a blurred particle image, and unique particles are outlined. It is captured as a clear particle image. In the binarization of step S4 in FIG. 3, the normal particles are deleted because they are unclear particle images.
Although not stored as image data, the singular particles are stored as image data without being deleted because they are clear particle images, and subsequent image processing is performed.

The present invention has the following effects. The present invention provides a flow cell in which a sample liquid containing test particles is surrounded by a sheath liquid and flows in a flat shape, an irradiation device that irradiates a flow region of particles, an imaging device that images the irradiated particles, and an obtained image. On the other hand, in a flow type particle image analyzer including a processing device for performing processing such as image processing and analysis, and an output device for outputting a processing result, a particle image blurring means for blurring an image of particles not to be measured in advance is provided. Therefore, it is possible to detect the specific particles existing at a minute concentration without imposing a burden on the image processing.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the configuration of the present invention.

FIG. 2 is an enlarged view of a flow cell part.

FIG. 3 is a flowchart of image processing.

FIG. 4 is an enlarged view of the first embodiment of the present invention.

FIG. 5 is a table showing a relationship between strobe brightness and detection particles.

FIG. 6 is a table showing the measurement capability of coarse particles in mixed particles.

FIG. 7 is a table showing the measurement capability of coarse particles in mixed particles.

FIG. 8 is an imaged particle image of mixed alumina particles at a normal strobe luminance level.

FIG. 9 is an imaged particle image of mixed alumina particles when the strobe luminance level is increased.

FIG. 10 is an enlarged view of a second embodiment of the present invention.

FIG. 11 is an enlarged view of a third embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 5 flow cell 8 pulse light source 10 video camera 11 image processing device 16 drive circuit 17 control unit

Claims (6)

[Claims] 1. A flow cell in which a sample liquid containing test particles is surrounded by a sheath liquid and flows in a flat shape, an irradiation device for irradiating a flow region of particles, and an imaging device for imaging the irradiated particles are obtained. In a flow-type particle image analyzer including a processing device that performs image processing and analysis on an image and an output device that outputs a processing result, a particle image blurring unit that blurs a particle image is provided. Characteristic flow type particle image analyzer. 2. The flow type particle image analyzer according to claim 1, wherein the particle image blurring means is an optical means. 3. The flow type particle image analyzer according to claim 2, wherein the particle image blurring means is means for increasing the irradiation light amount of the irradiation device more than usual. 4. The flow type particle image analyzer according to claim 2, wherein the particle image blurring means is means for shifting the focus of the particles of the image pickup device. 5. The flow type particle image analyzer according to claim 2, wherein the particle image blurring means is means for attenuating a light image from the particles. 6. The flow type particle image analyzer according to claim 1, wherein the particle image blurring means is a fluid means.