JP2000146817A - Grain size distribution measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grain size distribution measuring device capable of accurately catching grain properties of sample powder, controlling the dispersed state of the sample powder based on a result of this, and measuring qualities of the sample powder with higher accuracy. SOLUTION: In this grain size distribution measuring device 1, while sample powder is being supplied to a measuring place, laser light is radiated to the sample powder passing through the measuring place and the diffracted/scattered state of laser light is detected, and by arithmetically processing detection data by a computer, grain size distribution of the sample powder is measured. The grain size distribution measuring device 1 is integrally provided with a grain image photographing part 9 comprising a light source 10 and a CCD camera 11, image data obtained by the grain image photographing part 9 are arithmetically processed by the computer, and thereby grain properties including at least the aggregated state of grains of the sample powder are measured while the scattered state of the sample powder supplied to the measuring place is controlled based on a result of the measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a particle size distribution measuring apparatus in the powder industry, and more particularly to a particle size distribution measuring apparatus of a laser beam diffraction / scattering type.
The present invention relates to a particle size distribution measuring device capable of capturing the aggregation / dispersion state of a measurement sample other than the particle size distribution and capable of performing feedback control of the measuring device based on this information, for example.

[0002]

2. Description of the Related Art In general, as a means for confirming the state of a powder and ascertaining the production quality, a method of measuring the particle size (particle size distribution) is widely adopted and is regarded as important. Among them, a laser beam diffraction / scattering method in which a powder sample (particles) is irradiated with a parallel beam such as a laser beam, and the particle size distribution is calculated by measuring and analyzing the pattern of the laser beam diffracted / scattered by the particles. Conventionally, a particle size distribution measuring device is most often used because of its simplicity, quickness, and data reproducibility.

[0003]

However, although this particle size distribution measuring apparatus has many advantages as described above due to the adoption of the laser light diffraction / scattering method,
For example, it is not possible to measure the state of aggregation and dispersion of particles in a scattering field (measurement place), the change thereof, the change of properties such as the shape of the particles being measured, or the particle properties such as the shape of the particles themselves.

In recent years, for example, in order to accurately grasp the production quality of particles, when measuring the particle size distribution of a powder sample,
There is a tendency that demands for confirming these particle properties of powder samples increase. Therefore, there is an attempt to capture, for example, the state of aggregation from the particle size distribution obtained by the laser light diffraction / scattering method described above, but in this case, the particle properties are determined from the particle size distribution based on the intuition and experience of the operator. There is a problem that the actual state is grasped and the accuracy is inferior. In addition, the control of the particle size distribution measuring device (particularly, the dispersion control of the particles of the powder sample) based on the particle properties is currently performed. Not done.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for accurately measuring a particle property other than a particle size distribution of a powder sample. It is an object of the present invention to provide a particle size distribution measuring device capable of measuring the quality of a powder with high accuracy. Another object of the present invention is to not only accurately grasp the particle properties of the powder sample, but also control the dispersion state of the powder sample on the basis of the result to improve the quality of the powder sample. An object of the present invention is to provide a particle size distribution measuring device capable of measuring with high accuracy. Further, the object of the invention described in claim 3 is, in addition to the object of the invention described in claim 1 or 2, in which the state of aggregation of the particles of the powder sample is accurately grasped and the dispersion state of the powder sample is optimally measured. An object of the present invention is to provide a particle size distribution measuring device that can be in a state.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a powder sample is supplied to a measuring field while a laser is applied to the powder sample passing through the measuring field. Irradiate light to detect the diffraction and scattering state of the laser light,
In a particle size distribution measuring device that measures the particle size distribution of a powder sample by performing arithmetic processing on the detected data by a computer, a particle image capturing unit including a light source and a CCD camera is provided integrally with the particle size distribution measuring device. It is characterized in that the particle properties of the powder sample are measured by performing arithmetic processing on the image data obtained by the imaging unit by the computer.

With this configuration, the powder sample passing through the measuring field is irradiated with light such as halogen light from the light source of the particle image pickup unit, and the transmitted light or reflected light of the light is subjected to CC.
By taking an image with the D camera, a particle image is taken. The image data of the particle image is processed in parallel with the arithmetic processing for converting the intensity distribution of the scattered light by the laser beam into the particle size distribution. For example, the particle image is directly monitored and the particle properties are measured. Thereby, the particle properties other than the particle size distribution of the powder sample are captured, and the quality of the powder sample is measured with high accuracy.

According to a second aspect of the invention, a powder sample is supplied to a measuring field, and the powder sample passing through the measuring field is irradiated with laser light to detect a diffraction / scattering state of the laser light. Then, in a particle size distribution measuring device that measures the particle size distribution of the powder sample by performing arithmetic processing on the detected data by a computer, a particle image capturing unit including a light source and a CCD camera is provided integrally with the particle size distribution measuring device. The particle data of the powder sample is measured by performing arithmetic processing on the image data obtained by the particle image capturing unit by the computer, and the dispersion state of the powder sample supplied to the measurement site is controlled based on the measurement result. It is characterized by doing.

According to this structure, the first aspect of the present invention is provided.
As in the case of the described invention, the particle properties of the powder sample are captured by the particle image capturing unit, and a disperser provided in, for example, a measuring device is operated based on the result. By operating the disperser, the dispersion state of the powder sample is controlled and a good dispersion state is obtained in the powder sample, whereby the particle size distribution and particle properties of the powder sample can be more accurately grasped, Quality is more accurately measured.

The invention according to claim 3 is characterized in that the particle property of the powder sample is an aggregated state obtained by measuring the presence of an aggregate of particles of the powder sample. With this configuration, in the particle image capturing unit, the state of aggregation of the particles of the powder sample is detected by the presence of the aggregates. The dispersion state can be controlled to make the state optimal for measurement, and the quality of the powder sample is measured with higher accuracy.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 show an embodiment of a particle size distribution measuring apparatus according to the present invention, FIG. 1 is a basic configuration diagram thereof, and FIG. 2 is a basic block diagram when the present invention is applied to a wet type particle size distribution measuring apparatus. FIG. 3 is a perspective view showing the concept of the measurement field, FIG. 4 is a flowchart showing an example of the operation, and FIG. 5 is an image diagram of the particle image and a projected density distribution diagram.

In FIG. 1, a particle size distribution measuring apparatus 1 includes a laser light source 2 for irradiating a laser beam, a condensing lens 3 for condensing laser light scattered by a powder sample S, and detecting a scattered light intensity distribution. A signal processor 5 for converting the data detected by the detector 4 into a digital signal;
A CPU 6 for calculating and processing an output signal of the signal processor 5 and an output signal of a particle image capturing unit 9 described later;
And a color monitor 8 and the particle image capturing unit 9 for performing a predetermined process based on the signal processed by the computer and the output signal of the particle image capturing unit 9. Note that the CPU 6 can be omitted by giving the function to the computer 7.

The particle image pickup section 9 includes the halogen light source 1
0, a CCD camera 11, an image signal processor 12, and the like. The output side of the image signal processor 12 is connected to the CPU 6 and the computer 7. In other words, the particle size distribution measuring apparatus 1 according to the present invention uses a laser light diffraction / scattering type particle size analyzer formed by the laser light source 2, the condenser lens 3, the detector 4, the signal processor 5, and the CPU 6 to provide a particle image. The image pickup unit 9 is integrally incorporated, and a computer 7 and a color monitor 8 are functionally combined with these components.

The halogen light source 1 of the particle image pickup unit 9
As shown in FIG. 1, the CCD camera 11 and the CCD camera 11 are arranged in the opposite direction to the powder sample S flowing down, for example, in the direction of the arrow. Of course, it is also possible to dispose it on one side of the flow direction of the sample S). The computer 7 is formed of, for example, a personal computer to which a keyboard or the like (not shown) is connected.
The computer 7 has a PU, a RAM, a ROM, and the like.
Are displayed on the color monitor 8 or printed by a printer (not shown).

The particle size distribution measuring device 1 is capable of measuring the particle properties (aggregation state or dispersion state of the particles in the measurement field and the change thereof, as well as the particle size / particle size distribution (particle size distribution) of the powder sample S, The shape and its change) can be grasped and directly confirmed on the color monitor 8, and based on the measured particle property data, the particle size distribution measuring device 1 itself is controlled as described later to obtain the powder. It is configured so that the particle size distribution and particle properties of the sample S can be measured with higher accuracy.

FIG. 2 shows a case in which the present invention is applied to a wet type particle size distribution measuring device. The wet type particle size distribution measuring device 15 (hereinafter, referred to as a particle size distribution measuring device 15) includes a particle size analyzer 16 and a sample. And a circulator 17. The particle size analyzer 16 has a measurement field 18 therein and has basically the same configuration as the particle size analyzer of the particle size distribution measuring device 1. The suspension as the powder sample S is circulated and supplied. The sample circulator 17 is configured to suspend a powder (particles) charged by the operation of the stirring motor 19 in a predetermined liquid (for example, water) to form a suspension 20 and a measurement in the particle size analyzer 16. Place 1
It has a disperser 21 for dispersing the particles in the suspension returned from 8 with an ultrasonic homogenizer (not shown).

The measuring field 18 is, for example, shown in FIGS.
It is formed in one of the three types shown in FIG. First, in a measurement field 18 shown in FIG. 3A, a cell through which a laser beam passes and a cell for capturing a particle image are shared by one glass flow cell 22, and the glass flow cell 22 is a system in which a suspension circulates. Are arranged in the middle of the pipes 23a and 23b. In the case of the measurement site 18, the detection of the scattered light intensity distribution of the powder sample S and the imaging of the particle image are repeated at an arbitrary time under the control of the computer 7 or the like.
The particle size distribution measurement and the other measurement of the particle properties can be performed alternately, for example.

The measurement field 18 shown in FIG. 3B includes a glass flow cell 22a for passing a laser beam and a glass flow cell 22b for capturing a particle image, and a pipe 23a.
23c are arranged in a series (serial), and the measurement field 18 shown in FIG. 3 (c) includes a glass flow cell 22a through which laser light passes, and a glass flow cell 22b for imaging particle images. It is arranged in parallel (parallel) between 23a and 23b and between pipes 23c and 23d. In the case of both the measurement sites 18, the powder sample S is continuously
While measuring the particle size distribution of the particles, the particle properties can also be measured.

Next, an example of the operation of the particle size distribution measuring device 15 will be described with reference to FIGS. FIG. 4 shows the halogen light source 10 and C
This is a flowchart showing particle dispersion processing control based on particle property data when the CD camera 11 is arranged in the opposite direction. This flowchart is automatically executed according to a program stored in the computer 7 in advance. Further, for convenience of explanation, it is assumed that the measurement field 18 has a form shown in FIG.

First, when the distributed processing determination routine of the program is started (S101), a halogen light is irradiated from the halogen light source 10 onto the glass flow cell 22, and a particle image is captured (S102). The imaging of the particle image is performed by transmitting the halogen light emitted from the halogen light source 10 into the suspension passing through the glass flow cell 22 and imaging the transmitted light as a projection by the CCD camera 11. As shown in FIG. 5A, the particles R1,
Captured images (image data) having different projected densities are obtained according to the size and shape of R2. The captured images are sequentially displayed on the color monitor 8 (S300), and are used for a direct confirmation work or the like by visual observation by an operator.

When a particle image is captured, the captured image is binarized at a plurality of slice levels (S103). In this binarization of the captured image, for example, the captured image is in a state shown in FIG. 5A, the projected density distribution is shown in FIG. 5B, and three levels A to C are previously set as a plurality of slice levels. 7 are set as follows.

That is, for example, three levels A to C are:
The projected density of the level A is the highest value, and is set so as to become lower in order at a predetermined width (for example, a constant width). When the captured image of FIG. 5 is binarized at these three levels A to C,
At level A, the number of particles is determined to be one, at level B, the number of particles is determined to be two, and at level C, the number of particles is determined to be one. The determined particle numbers of the levels A to C are temporarily stored in, for example, the RAM of the computer 7.

Then, when the particle image is binarized, the total number of particles in all the set slice levels is counted (S104) and temporarily stored, and thereafter, the change rate Y1 of the number of particles between adjacent slice levels Y1 Is calculated (S10
5) Do it. The calculation of the change rate Y1 is performed by, for example, the aforementioned 3
When binarization is performed between two levels A to C, １ ／ = 0.5 between levels A and B, and 2/1 between levels B and C.
= 2. The change rate Y1 in this example is the degree of change in the number of particles when the projected density of the slice level is moved from a low level to a high level.

By calculating the rate of change Y1, the state of aggregation of the particles is determined.
For example, when the change rate Y1 of the number of particles between the slice levels is large and the particles are not aggregated, the change rate Y1 of the number of particles between the slice levels appears as little change or slight change.

When the change rate Y1 of the number of particles is calculated,
It is determined whether the calculated change rate Y1 is equal to or greater than a preset set value Y1s (S106). If “YES” in the determination S106, that is, if at least one (or a plurality or all) of the change rates Y1 of the number of particles between a plurality of adjacent slice levels is equal to or more than the set value Y1s,
It is determined that the particles in the suspension are agglomerated, that is, it is determined that the dispersion is insufficient, and an operation signal is output to the disperser 21 built in the sample circulator 17, and this disperser 2
1 is turned on (S107).

When the disperser 21 is turned on, the ultrasonic homogenizer is activated, and the ultrasonic waves apply a dispersing action to the suspension circulating between the particle size analyzer 16 and the sample circulator 17, whereby the suspension is dispersed. The aggregated particles therein are dispersed. This dispersion is performed for a predetermined processing time that is set in advance (S108), and when this time has elapsed is determined S108
Is "YES", and it is determined whether or not the image capturing of the particles has been performed a set number of times (S109). This judgment S
If “NO” in 109, the process returns to step S102,
The next particle image is captured, and the steps from step S103 are repeated.

After the image pickup of the particles has been performed a predetermined number of times, "YES" is determined in the judgment S109, the dispersion processing routine is ended (S110), and thereafter, the particle size distribution measurement is started (S111). This particle size distribution measurement is performed by the laser light diffraction / scattering method as described above, and the detection data detected by the detector 4 is processed by the signal processor 5,
This is appropriately processed by the CPU 6 and the computer 7 to create a histogram, which is displayed on the color monitor 8 or printed by a printer, for example.

On the other hand, if the determination in step S106 is "NO", that is, the change rate Y of the number of particles between adjacent slice levels,
If 1 is less than the set value Y1s, it is determined that no aggregation has occurred in the particles in the suspension or the aggregation does not affect the measurement, and the process jumps to step S110 to end the dispersion processing routine. Thus, a series of steps is completed, and the particle properties and particle size distribution of one type of powder sample S are measured.

In the flowchart shown in FIG. 4, the case where the particle size distribution measuring device 15 is of a wet type has been described as an example. However, for example, in the case of a dry type particle size distribution measuring device, the dispersion is composed of, for example, an ejector. In step S107, the compressed air pressure (dispersion pressure) is increased by a predetermined pressure to supply the compressed air to a disperser (not shown) and to suction the powder sample S by setting the inside of the disperser to a negative pressure. This state is performed by continuing (pressurizing) a predetermined processing time set in advance in step S108.

In the above example, when the particle image is binarized, the case where the slice levels are three levels A to C has been described. However, for example, two or four or more levels are set. Alternatively, the level intervals may be set differently without being constant, and may be set appropriately, such as calculating the rate of change Y1 between slice levels at a predetermined position, not limited to the rate of change Y1 between adjacent slice levels. it can. Also, if the dispersion of the particles in the suspension does not reach the predetermined level even after the dispersion process performed a preset number of times, the process is forcibly moved from step S109 to step S110, and the dispersion process routine is terminated, and the particle size distribution The process may proceed to the start of measurement (S111).

Further, the processing time in the judgment S108 can also be made by setting a specific time in advance. For example, the processing time is set in advance according to the degree of the change rate Y1 calculated in step S105. If the degree of aggregation is high, the dispersion processing can be performed for a relatively long time, and if the degree of aggregation is low, the dispersion processing can be performed in a relatively short time.

FIG. 6 shows a flowchart similar to that of FIG. 4 when the halogen light source 10 and the CCD camera 11 of the particle image pickup section 9 are in the same direction with respect to the powder sample S. Hereinafter, a part different from FIG. 4 will be described in detail. First, when the distributed processing routine is started (S201), a particle image is captured (S202). This particle image is obtained when the halogen light source 10 and the CCD camera 11
, The reflected light from the powder sample S is imaged, and for example, a particle image of an image diagram as shown in FIG. 7 is obtained.

When a particle image is captured, binarization is performed at a predetermined slice level (S203), and a boundary L between particles is detected from the binarized data (S204). In the detection of the boundary line L, in the case of the particle image shown in FIG. 7, since three particles R3 to R5 partially overlap, the density of the density is set between the overlapping portion 24 and the non-overlapping portion 25. A sudden change occurs, and the boundary line L is detected by extracting the rapidly changing portion (curve) from the binarized data.

In the case of FIG. 7, two boundary lines L1 and L
2 is detected, and the other two boundary lines L3, L
No. 4 has a small change in density, and is not detected as the boundary line L in step S204. That is, when the particles R3 to R5 are aggregated, the number of the overlapping portions 24 is increased, and the number of the detected boundary lines L is inevitably increased.
When R5 is well dispersed without aggregation, the number of overlapping portions 24 is small, and the number of boundary lines L detected is also small.

When the boundary line L is detected in step S204, the number Y2 of the boundary lines L is counted (S205).
Then, it is determined whether or not the number Y2 of the boundary lines L is equal to or greater than a preset value Y2s (S206). If "YES" in this determination S206, the dispersion is determined to be insufficient, and the wet-type disperser 21 is turned on and the dispersion pressure of the dry-type disperser is increased (S207) as in FIG. This processing is performed for a predetermined time (S208), and when the number of times of capturing the particle image reaches the predetermined number, the processing proceeds from determination S209 to step S2.
The routine goes to 10, and the distributed processing routine ends. After that, the particle size distribution measurement by the laser light diffraction / scattering method is started (S21).
1) Yes.

In this flowchart, the number Y2 of the boundary lines L of the overlapping portion 24 is detected and compared with the set value Y2s to determine the aggregation state of the particles. The number of binarized data of the overlapping portion 24 may be counted (area is calculated) and compared with a set value. According to this processing method,
In the case of the particle image of FIG. 7, two overlapping portions 24 are detected. Also, the number of slice levels is not limited to one, and a plurality of slice levels may be provided to determine the aggregation state according to the determination result of each slice level.

As described above, according to the particle size distribution measuring device 15 of the above embodiment, the halogen light source 1
Since the particle image capturing unit 9 including the CCD camera 11 and the CCD camera 11 is provided integrally, a single particle size distribution measuring device 15 can be used to determine the particle aggregating state other than the particle size distribution, the particle shape, and their changes. For example, the particle properties can be directly monitored by the color monitor 8. With this, it is possible to visualize the quality of the particle property state, which has been relying on intuition and experience with the particle size analyzer of the laser light scattering method, and when the dispersion state is bad, the disperser 21 and the like are automatically activated. Thus, a treatment for accelerating the dispersion can be performed, and various qualities of the powder sample S can be measured with high accuracy.

In particular, the particle image captured by the particle image capturing section 9 is binarized at a plurality of slice levels, for example, to determine the aggregation state of the particles, or binarized at a predetermined slice level to form a boundary line L. Since the aggregation state of the particles is determined by detection, the aggregation state can be accurately grasped, and the disperser 21 can be operated for a predetermined time or the dispersion pressure can be increased according to the result, so that
The agglomerated state of the particles of the powder sample S can be eliminated to achieve an optimal state. As a result, the particle properties and the particle size distribution can be measured in a good dispersion state, and the quality of the powder sample S can be measured with higher accuracy.

In addition to the particle size distribution measurement obtained by image analysis using a conventional laser beam, the particle properties and other various information can be measured by imaging a particle image using a halogen light having a different principle. Multilateral quality evaluation of the body sample S can be performed, and as a result, more accurate measurement can be performed. Furthermore, since the particle image capturing section 9 is integrated into the laser light diffraction / scattering type particle size analyzer 16 and can be controlled by one computer 7, the configuration of the particle size distribution measuring device 15 can be formed relatively simply. And the cost increase can be suppressed.

In the above embodiment, the particle size distribution measuring device 15 itself was controlled by operating the disperser 21 based on the image data of the powder sample S captured by the particle image capturing unit 9. The control of the particle size distribution measuring device 15 based on the image data of not only the operation control of the disperser 21 but also other mechanisms and components such as the stirring motor 19 of the sample circulator 17 to control the particle size of the powder sample S. The state of dispersion can also be controlled. Furthermore, the configuration of the particle size analyzer 16, the sample circulator 17, the disperser 21 and the
The form, the structure of the flow cell, the type of the light source of the particle image capturing unit 9 and the like are also examples, and it is needless to say that various changes can be made without departing from the gist of each invention according to the present invention.

[0041]

As described above in detail, according to the first aspect of the present invention, a particle size measuring apparatus for measuring a particle size distribution by a laser beam diffraction / scattering method is provided with a light source and a CCD camera. The unit is provided integrally, and the image data obtained by this particle image pickup unit is processed by a computer, so that one particle size distribution measuring device can capture the particle properties of the powder sample in addition to the particle size distribution. Therefore, the quality of the powder sample can be measured with high accuracy.

According to the second aspect of the present invention, the particle properties of the powder sample are detected by the particle image capturing unit, and the dispersion state is controlled by operating the disperser or the like of the measuring device based on the result. This allows the powder sample to be in the optimal dispersion state for measurement, and allows the particle size distribution and particle properties of the powder sample to be more accurately grasped, and the quality of the powder sample to be more accurate. Can be measured.

According to the third aspect of the present invention, in addition to the effects of the first or second aspect, the particle image capturing section can capture the aggregation state of the particles of the powder sample. The dispersion state of the body sample can be controlled so as to be in an optimum state for measurement, and the quality of the powder sample can be measured with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing an embodiment of a particle size distribution measuring device according to the present invention.

FIG. 2 is a basic block diagram when the present invention is applied to a wet type particle size distribution analyzer.

FIG. 3 is a perspective view showing the concept of the measurement field shown in FIG. 2;

FIG. 4 is a flowchart showing an example of the operation.

FIG. 5 is an image diagram and a projected density distribution diagram of the captured image.

FIG. 6 is a flowchart showing another example of the operation.

FIG. 7 is an image diagram of the captured image.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Particle size distribution measuring device 2 Laser light source 3 Condensing lens 4 Detector 5 Signal processor 6 CPU 7 Computer 8 Color monitor 9 Particle image pickup part 10 Halogen light source 11 CCD camera 12 Image signal processor 15 Wet type particle size distribution measuring device 16 Particle size analyzer 17 Sample circulator 18 Measurement field 21 Disperser S Powder sample

Claims (3)

[Claims] 1. A powder sample is supplied to a measuring field, and a powder sample passing through the measuring field is irradiated with a laser beam to detect a diffraction / scattering state of the laser beam. In a particle size distribution measuring device that measures the particle size distribution of a powder sample by performing arithmetic processing, a particle image capturing unit including a light source and a CCD camera is integrally provided in the particle size distribution measuring device, and the particle image capturing unit is obtained by the particle image capturing unit. A particle size measurement device for measuring the particle properties of the powder sample by subjecting the processed image data to arithmetic processing by the computer. 2. A laser beam is applied to a powder sample passing through the measurement field while the powder sample is being supplied to the measurement field to detect the diffraction / scattering state of the laser beam. In a particle size distribution measuring device that measures the particle size distribution of a powder sample by performing arithmetic processing, a particle image capturing unit including a light source and a CCD camera is integrally provided in the particle size distribution measuring device, and the particle image capturing unit is obtained by the particle image capturing unit. Calculating the particle properties of the powder sample by calculating the image data with the computer, and controlling the dispersion state of the powder sample supplied to the measurement site based on the measurement result. Particle size distribution measurement device. 3. The particle size distribution measurement according to claim 1, wherein the particle properties of the powder sample are in an aggregated state obtained by measuring the presence of an aggregate of particles of the powder sample. apparatus.