JP7805764B2 - Particle size distribution measuring device - Google Patents

Description

The present invention relates to a particle size distribution measuring device.

Conventionally, when measuring the particle size of granular materials such as aggregates such as sand and gravel that are mixed with cement to make concrete, or fill materials that are piled on land to level or slope it, and calculating a particle size accumulation curve that shows the particle size distribution, a method has been used in which the granular material is sieved using multiple sieves with different mesh sizes, and the proportion of the mass of the granular material that passed through each sieve to the total mass of the granular material is calculated.
This method has the problem of requiring a great deal of manual effort and time.
Therefore, Patent Document 1 proposes a technique for determining the particle size of a granular material from image data generated by capturing an image of the granular material with a digital camera.
In addition, Patent Document 2 proposes a technology in which a granular material is imaged to generate image data, the particle size of the granular material is calculated based on the image data, and a particle size accumulation curve is calculated based on the calculated particle size of the granular material.

JP 2010-038865 A Patent No. 6319791

To calculate the particle size of the granular material, the image data, which is a color image, is binarized and converted into grayscale image data, the contour (area) data of the granular material is extracted from the grayscale image data, and the particle size of the granular material is determined from the contour data.
Here, the granular materials that make up aggregates and fill materials are not usually uniform in color, but have a variety of colors depending on the location where the granular materials are collected.
Processes such as binarizing image data and extracting contour data are affected by the color of the granular material contained in the image data, so the accuracy of the contour data depends on the color of the granular material, and since the calculation results of the particle size of the granular material are affected by the color of the granular material, there is room for improvement in improving the accuracy of the particle size calculation results.
The present invention was devised in consideration of the above-mentioned circumstances, and its object is to provide a particle size distribution measuring device that is advantageous for accurately measuring the particle size of granular material and accurately calculating the particle size accumulation curve of the granular material.

One embodiment of the present invention is a particle size distribution measuring device comprising: a loading surface onto which a granular material containing a mixture of granular materials of different particle sizes is introduced and dispersed; an imaging unit that images the granular material dispersed on the loading surface to generate image data; an image processing unit that calculates the particle size of the granular material based on the image data; and a particle size distribution calculation unit that calculates a particle size accumulation curve showing the particle size distribution of the granular material in the granular material based on the particle size of the granular material calculated by the image processing unit, and is characterized by comprising a color change unit that changes the color of the loading surface.
One embodiment of the present invention is characterized in that the placement surface portion is formed to be light-transmitting and has a surface on which the granular material is dispersed and a back surface located on the opposite side, and the color-changing portion is composed of a light source device that irradiates light from the back surface side of the placement surface portion to the front surface side and is configured to be able to change the color of the light.
In one embodiment of the present invention, the light source device is configured as a liquid crystal display or an organic EL display.
One embodiment of the present invention is characterized in that the placement surface portion has a predetermined specified color over the entire surface on which the granular material is dispersed, and the color-changing portion is arranged at a location spaced above the surface and is composed of a light source device that irradiates light onto the surface and the granular material dispersed on the surface and is configured to change the color of the light.
One embodiment of the present invention is characterized in that the entire surface of the placement surface on which the granular material is dispersed is constructed of a plurality of replaceable sheets, and the color-changing portion is constructed of the plurality of sheets which are different in color from each other.
In one embodiment of the present invention, the placement surface portion is divided into a plurality of divided placement surface portions, and the color-changing portion changes color independently for each of the divided placement surface portions.
In one embodiment of the present invention, the image processing unit includes a grayscale image data generation unit that generates grayscale image data from the image data consisting of RGB image data based on the following equation (1), and is configured to be able to adjust the values of the coefficients a, b, and c relative to predetermined default values:
Y=a*R+b*G+c*B…(1)
However, Y: brightness, R: R image data, G: G image data, B: B image data, a, b, c: coefficients. One embodiment of the present invention is characterized in that the image processing unit includes a binary data generation unit that generates binary data from the grayscale image data, a contour data generation unit that extracts contour data indicating the contour of the granular material from the binary data, and a particle size calculation unit that calculates the particle size of the granular material based on the contour data.
One embodiment of the present invention is characterized in that the particle size calculation unit calculates the particle size by calculating the area of the closed area defined by the contour data, and from the area calculation result, determining the diameter of the sphere assuming that the granular material is a sphere as the particle size.

According to one embodiment of the present invention, a color-changing portion is provided that changes the color of the placement surface onto which the granular material is poured and dispersed.
Therefore, while evaluating the accuracy of the contour data of the granular material obtained based on the image data, the color of the placement surface portion can be changed by the color changing portion so as to improve the recognition accuracy of the contour of the granular material.
Therefore, the particle size of each granular material can be accurately measured based on highly accurate contour data, which is advantageous for accurately calculating the particle size accumulation curve of the granular material and for accurately evaluating the granular material.
Furthermore, if the placement surface portion is formed to be light-transmittable and the color-changing portion is constructed from a light source device that irradiates light from the back side to the front side of the placement surface portion and is configured to be able to change the color of the light, this is advantageous in changing the color of the placement surface portion with a simple configuration.
Furthermore, if the light source device is configured as a liquid crystal display or an organic EL display, it is advantageous in that the color of the light emitted from the light source device can be changed simply and easily.
Furthermore, if the placing surface portion is configured so that the color of the entire surface on which the granular material is dispersed is a predetermined specified color, and the color changing portion is configured as a light source device that irradiates light onto the surface and the granular material dispersed on the surface and is configured so that the color of the light can be changed, then by changing the color of the light irradiated from the light source device, it is possible to realize a greater number of combination patterns of the color of the placing surface portion and the color of the granular material on the acquired image data.
Therefore, it is more advantageous to evaluate the accuracy of the contour data of the granular material obtained based on image data, and to change the color of the placing surface using the color changing section so as to improve the recognition accuracy of the contour of the granular material; it is more advantageous to be able to accurately measure the particle size of each granular material based on highly accurate contour data, and to accurately calculate the particle size accumulation curve of the granular material, and it is more advantageous to accurately evaluate the granular material.
Furthermore, if the color-changing portion is made up of multiple sheets of different colors, the color of the placing surface portion can be changed by replacing the sheets so as to improve the recognition accuracy of the contours of the granular material while evaluating the accuracy of the contour data of the granular material obtained based on the image data.
Therefore, the particle size of each granular material can be accurately measured based on highly accurate contour data, which is advantageous for accurately calculating the particle size accumulation curve of the granular material and for accurately evaluating the granular material.
Furthermore, if the mounting surface is divided into multiple divided mounting surface sections and the color-changing section is made to change color independently for each divided mounting surface section, image data corresponding to divided mounting surface sections of different colors can be obtained at once, which is advantageous in increasing efficiency when evaluating the accuracy of the contour data of the extracted granular material and in shortening the work time required to obtain a particle size accumulation curve.
Furthermore, if the image processing unit includes a grayscale image data generating unit that generates grayscale image data based on the following formula (1), and is configured to be able to adjust the values of the coefficients a, b, and c relative to predetermined default values,
Y=a*R+b*G+c*B…(1)
By evaluating the accuracy of the contour data of the granular material obtained based on image data and adjusting the values of the above coefficients a, b, and c so as to improve the recognition accuracy of the contour of the granular material, it is more advantageous for obtaining highly accurate contour data, more advantageous for accurately calculating the particle size accumulation curve of the granular material, and more advantageous for accurately evaluating the granular material.
Furthermore, if the image processing section is configured to include a binary data generating section, a contour data generating section, and a particle size calculating section, it is advantageous in simplifying the configuration of the image processing section.
Furthermore, if the particle size is calculated by calculating the area of the closed region defined by the contour data and then using the area calculation results to determine the diameter of the sphere assuming that the granular material is a sphere, the particle size of the granular material can be calculated with high accuracy, which is more advantageous for accurately calculating the particle size accumulation curve of the granular material and more advantageous for accurately evaluating the granular material.

1 is an explanatory diagram showing the configuration of a particle size distribution measuring device according to a first embodiment; FIG. 2 is a block diagram showing the configuration of a control system of the particle size distribution measuring device according to the first embodiment. FIG. 2 is a perspective view showing a container of the particle size distribution measuring device according to the first embodiment. 3 is an operation flowchart of the particle size distribution measuring device according to the first embodiment. 10 is an explanatory diagram showing an example of contour data of granular material dispersed on a placement surface portion. FIG. 3 is a diagram showing an example of a particle size accumulation curve calculated by the particle size distribution measuring device according to the first embodiment. FIG. 1A is an explanatory diagram showing the configuration of a particle size distribution measuring device according to a second embodiment, and FIG. 1B is a view taken along the arrow B in FIG. 1A. 10A is a perspective view showing a container and a sheet of a particle size distribution measuring device according to a third embodiment, FIG. 10B is a perspective view showing a state in which a sheet is placed on the placement surface, and FIG. 10C is a perspective view showing a state in which another sheet is placed on the placement surface. 10A is a perspective view showing a state in which the back surface of the mounting surface of the container of the particle size distribution device of the fourth embodiment is placed on top of the display screen of the light source device, and FIG. 10B is a plan view thereof. 10A is a perspective view showing a container and three sheets of a particle size distribution measuring device according to a fifth embodiment, and FIG. 10B is a perspective view showing a state in which a sheet is placed on each of three divided placement surfaces.

(First embodiment)
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, the terms used in this specification will be explained.
Granular materials are materials used in civil engineering and construction projects, for example, and specifically include aggregates such as sand and gravel that are mixed with cement to make concrete, and fill materials that are piled on land to level or slope it.
Aggregates and fill materials are made up of granular materials that are a mixture of granular materials of different particle sizes.
The area equivalent diameter is known as a definition of the particle size of granular materials.
The area equivalent diameter is the area defined by the outline of the granular material when it is assumed to be a sphere and projected onto a plane; in other words, the area defined by the outline of the granular material as identified on image data captured by an imaging device is taken as the projected area of the sphere, and is calculated as the diameter of this sphere.
The reason why the area equivalent diameter is calculated as the particle diameter of the granular material is that the granular material has an irregular shape of various shapes.

Granular materials that make up aggregates and embankment materials are classified as follows according to the range of particle size D (JIS A0207:2018 (geotechnical engineering terminology)).
Clay content: Particle size D<0.005mm
Silt content: 0.005 mm≦particle size D<0.075 mm
Sand content: 0.075mm≦particle size D<2mm
Gravel: 2 mm≦particle size D<75 mm
Stone content: 75mm≦particle size D

The particle size accumulation curve indicates the distribution of particle sizes of the granular materials that make up the granular material.
As shown in Figure 6, the particle size accumulation curves C1 and C2 are represented by a semi-logarithmic graph with the particle size D of each granular material on the horizontal axis (logarithmic scale) and the passing mass percentage P (also called the accumulated passing rate) on the vertical axis (linear scale).
The passing mass percentage P is the mass percentage of granular material having a particle size D or less relative to the total, i.e., the percentage value of the total mass of granular material having a particle size D or less relative to the total mass of all granular material.

Next, the configuration of the particle size distribution measuring device 10 according to this embodiment will be described.
As shown in FIGS. 1 and 2, the particle size distribution measuring device 10 includes a container 12A, an imaging unit 14, a color change unit 16, and a computer 18.
As shown in Figure 3, the container 12A is used to pour granular material containing a mixture of granular materials of different particle sizes, and is open at the top and has a mounting surface 20 and a side wall 22 that extends from the periphery of the mounting surface 20.
In this embodiment, the mounting surface portion 20 has a rectangular plate shape of uniform thickness having long and short sides, but the shape of the mounting surface portion 20 is not limited and may be circular, polygonal, or the like.
The loading surface 20 is where the granular material is poured and dispersed.
In this embodiment, the placement surface portion 20 is formed to be light transmissive and includes a front surface 2002 on which granular material is dispersed, and a back surface 2004 located on the opposite side.
The placement surface unit 20 only needs to be light-transmittable, and may be colorless and transparent or white and translucent, as long as the color of light (light color) irradiated from the color changing unit 16 (described later) can be captured by the imaging unit 14 when viewed from the surface 2002 side of the placement surface unit 20. In other words, the color of the light only needs to be reflected in the image data of the placement surface unit 20 captured by the imaging unit 14.
The material that can be used to form the mounting surface portion 20 is a light-transmitting material such as synthetic resin or glass.
The side walls 22 are provided to prevent the granular material dispersed on the placement surface 20 from falling off the edge of the placement surface 20 and may be omitted.
Similarly to the mounting surface portion 20, the material forming the side wall 22 may be either a light-transmitting material or an opaque material.

The color-changing portion 16 changes the color of the placement surface portion 20 .
In this embodiment, the color changing section 16 is configured with a light source device 24 that is configured to irradiate light from the back surface 2004 side to the front surface 2002 side of the mounting surface section 20 and to be able to change the color of the light.
The light source device 24 can be a liquid crystal display or an organic EL display.
The light source device 24 comprises a rectangular plate-shaped main body 2402, a rectangular display screen 2404 located on the upper surface of the main body 2402 and extending in a horizontal plane when the main body 2402 is installed on the base 26, an operation unit 2406, and a display control unit (not shown).
The display screen 2404 has an outline that is the same as or larger than the placement surface 20 , and the entire rear surface 2004 of the placement surface 20 is superimposed on the display screen 2404 .
The operation unit 2406 includes an operation switch for changing the color of the light emitted from the display screen 2404, an operation switch for changing the amount of light emitted from the display screen 2404, and the like.
A display control unit (not shown) receives an operation from the operation unit 2406 to control the light source device 24 and adjusts the color and amount of light irradiated onto the display screen 2404 .
In this embodiment, the light source device 24 is configured to irradiate the entire display screen 2404 with light of a uniform color and a uniform amount.
The color of the light emitted from the display screen 2404 may be any color that is expressed by a combination of the three primary colors of light: R (red), G (green), and B (blue).

The light source device 24 only needs to be configured to irradiate light from the back surface 2004 side of the mounting surface portion 20 to the front surface 2002 side and to be capable of changing the color of the light, and various conventionally known lighting devices capable of changing the color of light can be used, and are not limited to liquid crystal displays or organic EL displays.
For example, a light source unit that emits white light may be combined with a plurality of color filters for illumination that are detachably attached to the light source unit, and the color of the light may be changed by replacing the color filters.

The imaging unit 14 is composed of an imaging device 14A such as a digital camera, and when the mounting surface unit 20 is superimposed on the display screen 2404 of the light source device 24, it captures an image of the granular material dispersed on the surface 2002 of the mounting surface unit 20 to generate image data (still image).
The imaging unit 14 is supported at a location spaced above the mounting surface 20 via a stand 28 arranged on a base 26, and is configured to be able to image the entire mounting surface 20 from above.

As shown in FIG. 2, the computer 18 includes an input device 30, an output device 32, and an external storage device 34 in addition to a CPU, ROM, RAM, a hard disk drive, and an input/output interface, all of which are not shown.
The ROM stores predetermined control programs and the like, and the RAM provides a working area.
The hard disk device stores control programs for realizing an input unit 18A, an image processing unit 18B, a particle size distribution calculation unit 18C, an output unit 18D, and a communication unit 18E, which will be described later.
The input/output interface is an interface with the following input device 30, output device 32, and network 36.
The input device 30 receives operational input from an operator, and includes a keyboard 3002 and a mouse 3004 .
The output device 32 outputs information and includes a display 3202 and a printer 3204 .
The external storage device 34 stores information and includes an external hard disk device, an external SSD (solid state drive), a semiconductor recording medium such as a memory card or USB memory, or an optical disk recording medium such as a DVD.

The CPU executes the control program of the hard disk device, thereby realizing an input unit 18A, an image processing unit 18B, a particle size distribution calculation unit 18C, an output unit 18D, and a communication unit 18E.
The input unit 18A receives image data captured by the imaging device 14A.

The image processing unit 18B calculates the particle diameter D of the granular material based on the image data, calculates the area of the granular material from the image data by image recognition, and calculates the particle diameter D (area equivalent diameter) from the calculated area.
More specifically, the image processing unit 18B includes a grayscale image data generating unit 40, a binary data generating unit 42, a contour data generating unit 44, and a particle size calculating unit 46.

The grayscale image data generating section 40 generates grayscale image data from image data made up of RGB image data supplied from the imaging device 14A, based on the following equation (1).
Y=a*R+b*G+c*B…(1)
where Y is luminance, R is R image data, G is G image data, B is B image data, a, b, c are coefficients, and the symbol * indicates a multiplication symbol.
Each of the R, G, and B data is expressed in 8 bits, and therefore the luminance Y is expressed in 24 bits.
The values of the coefficients a, b, and c can be set according to various known standards.
For example, according to the coefficients defined in the ITU-R Rec BT.601 standard, equation (1) becomes equation (2) below.
Y=0.299*R+0.587*G+0.114*B...(2)
In this embodiment, the grayscale image data generating unit 40 is configured to be able to adjust the values of these coefficients a, b, and c relative to predetermined default values.
Specifically, the grayscale image data generating unit 40 is configured to display a setting screen for each coefficient on a display, and to allow the values of each coefficient a, b, and c to be adjusted by setting each coefficient using the keyboard or mouse.

The binary data generating section 42 compares the grayscale image data with a predetermined threshold value to binarize the grayscale image data and generate binary data.
Such processing can be realized, for example, by using the threshold function of OpenCV, a known open source library.

The contour data generating section 44 extracts contour data indicating the contours of the granular material from the binarized data.
Such processing can be realized by using the findContours function of OpenCV, for example.

The particle size calculation unit 46 calculates the particle size D of the granular material based on the contour data. Specifically, it calculates the area of the closed region defined by the contour data, and from the area calculation result, determines the diameter of a sphere if the granular material is assumed to be a sphere, in other words, the area equivalent diameter, as the particle size D.
That is, since the area of the closed region is calculated in pixel units, the area S1 of the closed region calculated in pixel units is multiplied by the square of the calibration coefficient α, which indicates the area per pixel, to calculate the area S2 in real space = α*α*S1, and the area equivalent diameter is calculated from the area S2.

The particle size distribution calculation unit 18C calculates the particle size accumulation curves C1 and C2 in Figure 6, which show the distribution of particle size D of the granular material in the granular material, based on the particle size D of the granular material calculated by the image processing unit 18B.
The output section 18D supplies data of the particle size accumulation curve calculated by the particle size distribution calculation section 18C to the output device 32 or the external storage device 34.
The communication unit 18E communicates with a terminal (computer) not shown via a network 36 including the Internet or a dedicated line, and in this embodiment, transmits data on the particle size accumulation curve calculated by the particle size distribution calculation unit 18C to the terminal not shown.

Next, the operation of the particle size distribution measuring apparatus 10 according to this embodiment will be described with reference to the flowchart of FIG.
First, a granular material, such as aggregate or fill material, whose particle size distribution is to be measured, is sampled (step S10).
Next, the collected granular material is poured onto the mounting surface 20 of the container 12A to disperse the granular material (step S12).
The container 12A is set in advance with the rear surface 2004 of the placement surface portion 20 superimposed on the display screen 2404 of the light source device 24.
Then, the color of light emitted from the light source device 24 is appropriately set, and the set light is emitted from the rear surface 2004 of the mounting surface portion 20 toward the front surface 2002 (step S14).

Once the light is irradiated, the imaging device 14A captures an image of the entire mounting surface 20 (inclined mounting surface 38) to obtain image data composed of RGB image data (step S16).

Next, the grayscale image data generating unit 40 generates grayscale image data from the image data made up of RGB image data supplied from the imaging device 14A, based on, for example, the above-mentioned equation (1) or equation (2) (step S18).
Next, the binary data generating unit 42 binarizes the grayscale image data to generate binary data (step S20).
Next, the contour data generating unit 44 extracts contour data indicating the contours of the granular material from the binarized data (step S22).
FIG. 5 shows an example of granular material contour data, in which the contour lines of each granular material 2 are shown.
Next, the particle size calculation unit 46 calculates the particle size D of the granular material based on the contour data (step S24).

Then, the particle size distribution calculation unit 18C accumulates the number of granular materials 2 for each particle size D (step S26), and determines whether accumulation has been completed for the entire number of granular materials 2 contained in the captured image data (step S28).If the determination result is negative, the unit returns to step S26 and continues accumulation, and if the determination result is positive, the unit proceeds to step S30.
The particle size distribution calculation unit 18C calculates the particle size accumulation curve shown in FIG. 6 based on the result of accumulating the number of granular materials 2 for each particle size D (step S30).
The output unit 18D outputs the calculated particle size accumulation curve to the display 3202 for display on the screen, or prints it out from the printer 3204. Alternatively, the output unit 18D supplies the calculated particle size accumulation curve to the external storage device 34 (step S32).
Furthermore, the output unit 18D transmits the calculated particle size accumulation curve from the communication unit 18E to another terminal via the network 36 (step S34).
This completes the series of operations.

The calculated particle size accumulation curve is used to estimate the particle size of the granular material.
FIG. 6 illustrates an example of a particle size accumulation curve C1 with a gentle slope and a particle size accumulation curve C2 with a steep slope.
Generally, the gentler the slope of the particle size accumulation curve, the wider the range of particle size D of the granular material 2 contained, resulting in smaller gaps between the granular materials 2 and a more stable state, and therefore the higher the particle size evaluation of the granular material.
Conversely, the steeper the slope of the particle size accumulation curve, the more granular material 2 with uniform particle size D is contained, resulting in larger gaps between the granular materials 2 and an unstable state, which results in a lower evaluation of the particle size of the granular material.

Next, the effects will be described.
The granular materials 2 constituting the granular material have various colors depending on the land where they were collected, etc. Furthermore, granular materials 2 constituting the granular material collected from the same land also have various colors.
The inventors conducted an experiment using granular materials 2 of various colors as samples, changing the combination of the color of the mounting surface portion 20 and the color of the granular material 2, generating grayscale image data from image data (RGB image data) obtained from the imaging device 14A, binarizing the grayscale image data to generate binary data, and extracting contour data showing the contours of the granular material 2 from the binary data.
As a result, we found that depending on the combination of the color of the mounting surface 20 and the color of the granular material 2, the outline of the resulting granular material 2 may become unclear, or the outlines of multiple independent granular materials 2 may be mistakenly recognized as a single outline, or the outline itself may disappear in the case of small granular materials 2.
In other words, it is believed that the combination of the color of the placement surface portion 20 and the color of the granular material 2 affects the recognition accuracy of the contour of the granular material 2, and therefore affects the accuracy of the contour data obtained.
For example, if the color of the mounting surface portion 20 is similar to the color of the granular material 2, it is conceivable that the accuracy of recognizing the contour of the granular material 2 is likely to decrease when contour data showing the contour of the granular material 2 is extracted from the image data.
Alternatively, when the combination of the color of the mounting surface portion 20 and the color of the granular material 2 is a specific combination, it is conceivable that the accuracy of recognizing the contour of the granular material 2 is likely to decrease when extracting contour data showing the contour of the granular material 2 from the image data.
Therefore, by conducting experiments combining the color of the mounting surface 20 and the color of the granular material 2 in various patterns and evaluating the accuracy of the obtained contour data, it is thought possible to find a combination of the color of the mounting surface 20 and the color of the granular material 2 that can ensure the accuracy of recognizing the contour of the granular material 2.

Therefore, in this embodiment, a color-changing section 16 is provided that changes the color of the placement surface section 20 onto which the granular material, which is a mixture of granular materials 2 of different particle sizes D, is poured and dispersed.
Therefore, while evaluating the accuracy of the contour data of the granular material 2 extracted based on the image data obtained from the imaging device 14A, the color of the placing surface portion 20 can be changed by the color changing portion 16 so as to improve the recognition accuracy of the contour of the granular material 2.
Therefore, the particle size D of each granular material 2 can be accurately measured based on highly accurate contour data, which is advantageous for accurately calculating the particle size accumulation curve of the granular material 2 and for accurately evaluating the granular material.

In addition, in this embodiment, the placement surface portion 20 is formed to be light transmissive, and the color-changing portion 16 is configured as a light source device 24 that irradiates light from the back surface 2004 side to the front surface 2002 side of the placement surface portion 20 and is configured to be able to change the color of the light, which is advantageous in changing the color of the placement surface portion 20 with a simple configuration.

In addition, in this embodiment, the light source device 24 is configured as a liquid crystal display or an organic EL display, which is advantageous in that the color of the light emitted from the light source device 24 can be changed simply and easily.

Furthermore, in this embodiment, the image processing unit 18B includes a grayscale image data generating unit 40 that generates grayscale image data based on the following equation (1), and is configured to be able to adjust the values of the coefficients a, b, and c relative to predetermined default values.
Y=a*R+b*G+c*B…(1)
Therefore, by evaluating the accuracy of the contour data of the granular material 2 extracted based on the image data obtained from the imaging device 14A and adjusting the values of the above coefficients a, b, and c so as to improve the recognition accuracy of the contour of the granular material 2, it is more advantageous in obtaining highly accurate contour data, more advantageous in accurately calculating the particle size accumulation curve of the granular material 2, and more advantageous in accurately evaluating the granular material.

Furthermore, according to this embodiment, the image processing unit 18B is configured to include a binary data generation unit 42, a contour data generation unit 44, and a particle size calculation unit 46, which is advantageous in simplifying the configuration of the image processing unit 18B.

Furthermore, according to this embodiment, the particle size calculation unit 46 calculates the particle size D by calculating the area of the closed region defined by the contour data, and from the calculation result of that area, assuming that the granular material 2 is a sphere, determines the diameter of the sphere as the particle size D.
Therefore, the particle size D of the granular material 2 can be calculated with high accuracy, which is more advantageous for accurately calculating the particle size accumulation curve of the granular material 2 and more advantageous for accurately evaluating the granular material.

Second Embodiment
Next, a second embodiment will be described with reference to FIG.
In the following embodiments, parts and members similar to those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted, and the description will focus on the differences.
The second embodiment differs from the first embodiment in the configuration of the placement surface portion 20 and the color changing portion 16, but the other configurations are the same as those shown in the block diagram of FIG.
As shown in Figure 7 (A), similar to the first embodiment, the container 12B has a mounting surface portion 20 and a side wall 22 that stands up from the periphery of the mounting surface portion 20, is formed in an open shape at the top, and is placed on a base 26.
The placement surface portion 20 has a front surface 2002 on which the granular material 2 is dispersed, and a back surface 2004 located on the opposite side.
In the second embodiment, the surface 2002 has a predetermined color over its entire area.
The specified color is preferably white or a color similar to white, which can accurately reflect the color of light irradiated onto the surface 2002 of the placement surface portion 20.

Unlike the first embodiment, the color-changing section 16 is positioned at a location spaced above the surface 2002 of the mounting surface section 20, and is composed of a light source device 48 that irradiates light onto the surface 2002 and the granular material 2 dispersed on the surface 2002 and is configured to be able to change the color of the light.
For example, the light source device 48 is configured as a known ring light 48A that uses an LED as a light source, and is configured so that the color and amount of light emitted can be adjusted by operating an operating unit not shown.
The ring light 48A extends in a circular ring shape around a central axis 4802, is spaced upward from the surface 2002 of the mounting surface 20, and is supported on the base 26 via a stand 50 with its central axis approximately aligned with the optical axis La of the imaging device 14A and its irradiation surface that emits light facing the mounting surface 20.
By using such a ring light 48A, it is possible to irradiate the entire area of the placement surface 20 with light of a uniform color and a uniform amount.
As in the first embodiment, the color of the light emitted from the ring light 48A may be any color that can be expressed by a combination of RGB.
The light source device 48 is not limited to ring light 48A and can be any device that can irradiate light from above the mounting surface 20 toward the mounting surface 20 and change the color of the light, and can be any of a variety of conventionally known lighting devices that can change the color of light.
As in the above, a light source unit that emits white light may be combined with a plurality of color filters for illumination.

Similar to the first embodiment, the imaging unit 14 is supported at a distance above the mounting surface 20 via a stand 28 arranged on a base 26, and is configured to capture images of the entire mounting surface 20 from above.

According to the second embodiment, as in the first embodiment, the accuracy of the contour data of the granular material 2 extracted based on image data obtained from the imaging device 14A can be evaluated, and the color of the placing surface portion 20 can be changed by the color changing portion 16 so as to improve the recognition accuracy of the contour of the granular material 2.
Therefore, the particle size D of each granular material 2 can be accurately measured based on highly accurate contour data, which is advantageous for accurately calculating the particle size accumulation curve of the granular material 2 and for accurately evaluating the granular material.

In addition, in the second embodiment, the loading surface portion 20 is configured so that the color of the entire surface 2002 on which the granular material 2 is dispersed is a predetermined specified color, and the color changing portion 16 is arranged at a location spaced above the surface 2002 of the loading surface portion 20, and is configured with a light source device 48 that irradiates light onto the surface 2002 and the granular material 2 dispersed on the surface 2002 and is configured to be able to change the color of the light.
Therefore, by changing the color of the light emitted from the light source device 48, it is not only possible to change the combination of the color of the mounting surface portion 20 and the color of the granular material 2, but the color of the granular material 2 also changes depending on the light emitted, so it is possible to realize a greater number of combination patterns of the color of the mounting surface portion 20 and the color of the granular material 2 on the image data acquired by the imaging device 14A.
Therefore, it is more advantageous to evaluate the accuracy of the contour data of the granular material 2 extracted based on the image data obtained from the imaging device 14A, while changing the color of the placing surface portion 20 using the color changing portion 16 so as to improve the recognition accuracy of the contour of the granular material 2.
This allows the particle size D of each granular material 2 to be accurately measured based on highly accurate contour data, which is more advantageous for accurately calculating the particle size accumulation curve of the granular material 2 and more advantageous for accurately evaluating the granular material.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG.
The third embodiment differs from the first and second embodiments in the configuration of the placement surface portion 20 and the color changing portion 16, but other configurations are the same as those shown in the block diagram of FIG.
7, an imaging device 14A and an illumination device 48 are installed above the placement surface portion 20, similar to the second embodiment.
8A, 8B, and 8C, the entire surface 2002 of the container 12C is configured so that the entire surface 2002 on which the granular material 2 is dispersed is replaceably covered with a plurality of sheets 52 (first sheet 52A and second sheet 52B in this embodiment) of different colors. In the drawings, different hatching indicates different colors.
Specifically, the surface 2002 of the placement surface 20 can be replaced by selecting and placing each sheet 52 on the placement surface 20 .
Therefore, unlike the first and second embodiments, the color changing section 16 is made up of a plurality of sheets 52 that are different in color from one another.
Each sheet 52 is formed with an outline having the same shape and size as the placement surface portion 20, and is made of a sheet material that is colored a uniform color over the entire area.
The sheet material may be any material on which the granular material 2 is placed and dispersed, and various conventionally known materials such as paper, synthetic resin, woven fabric, nonwoven fabric, and felt can be used as such a sheet material.
As the nonwoven fabric, for example, a commercially available punch carpet can be used.
Punch carpet is a nonwoven carpet made by entangling fibers with needles, and is preferred because it is inexpensive and readily available.
The illumination light irradiated onto the placement surface 20 from the illumination device 14 is preferably white light that does not affect the color of each sheet 52 .
In the third embodiment, the same process as that shown in the flowchart of FIG. 4 described in the first embodiment is carried out to obtain a particle size accumulation curve.

According to the third embodiment, the color of the loading surface portion 20 can be changed by replacing the sheet 52 on the surface 2002 of the loading surface portion 20 so as to improve the recognition accuracy of the contour of the granular material 2, while evaluating the accuracy of the contour data of the granular material 2 extracted based on the image data obtained from the imaging device 14A.
Therefore, the particle size D of each granular material 2 can be accurately measured based on highly accurate contour data, which is advantageous for accurately calculating the particle size accumulation curve of the granular material 2 and for accurately evaluating the granular material.
Furthermore, in the third embodiment, the color changing section 16 is made up of a plurality of sheets 52, so that the color changing section 16 can be realized inexpensively, which is advantageous in reducing the cost of the particle size distribution measuring device.

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG.
The fourth embodiment is a modification of the first embodiment.
9A is a perspective view showing a state in which the back surface 2004 of the placement surface portion 20 of the container 12D is placed on the display screen 2404 of the light source device 24, and FIG. 9B is a plan view thereof.
The support surface portion 20 is divided into a plurality of divided support surface portions 54, and in the fourth embodiment, the plurality of divided support surface portions 54 are composed of first, second, and third divided support surface portions 54A, 54B, and 54C.
Each divided mounting surface portion 54 has a rectangular shape of the same shape and size.
The color-changing section 16 is configured by a light source device 24 and is configured to change color independently for each divided placement surface section 54 .
The light source device 24 is configured by a liquid crystal display or an organic EL display, similar to the first embodiment.
The display control unit (not shown) of the light source device 24 accepts operation of the operation unit 2406 and controls the light source device 24 to divide the display screen 2404 into first, second, and third divided areas 2404A, 2404B, and 2404C corresponding to the three divided mounting surface sections 54, and to make the color of light emitted from each area different.
Therefore, the operation unit 2406 is configured so that the color and light intensity of the light of each of the divided areas 2404A, 2404B, and 2404C can be controlled independently.
Also, as in the first embodiment, the color of light emitted from each of the first, second, and third divided areas 2404A, 2404B, and 2404C may be any color expressed by a combination of the three primary colors of light: R (red), G (green), and B (blue).
Therefore, the imaging device 14A can capture images with different colors on the three divided mounting surface portions 54. In the drawing, different hatching indicates different colors of light.
The number of divided placement surface portions 54 (the number of divided areas of the display screen 2404) may be two or four or more.
In the fourth embodiment, the same process as that shown in the flowchart of FIG. 4 described in the first embodiment is carried out to obtain a particle size accumulation curve.

According to the fourth embodiment, the color of each divided loading surface portion 54 is changed independently by the color changing section 16 formed by the light source device 24, so that image data of the granular material 2 dispersed on the divided loading surface portions 54 having different colors can be obtained by a single image capture by the imaging device 14A.
Therefore, image data corresponding to divided loading surface portions 54 of different colors can be obtained at once, which is advantageous in improving efficiency when evaluating the accuracy of the contour data of the extracted granular material 2.
Therefore, as in the first embodiment, this is advantageous in accurately calculating the particle size accumulation curve of the granular material 2, and not only has the effect of being advantageous in accurately evaluating the granular material, but it is also advantageous in reducing the working time required to obtain the particle size accumulation curve.
Furthermore, using a liquid crystal display or an organic EL display as light source device 24 is advantageous in that it is possible to simply and easily realize multiple divided regions 2404A, 2404B, and 2404C. Furthermore, it is possible to easily change the color of light emitted from multiple divided regions 2404A, 2404B, and 2404C, which is advantageous in terms of improving workability.

Fifth Embodiment
Next, a fifth embodiment will be described with reference to FIG.
The fifth embodiment is a modification of the third embodiment.
10A is a perspective view showing three independent sheets 56 of different colors and a container 12E, and FIG. 10B is a perspective view showing the three independent sheets 56 placed side by side on the placement surface 20.
In the fifth embodiment, the mounting surface portion 20 is also divided into first, second and third divided mounting surface portions 54A, 54B and 54C, and each divided mounting surface portion 54 has a rectangular shape of the same shape and size.
The color-changing section 16 is composed of three independent sheets 56 (first, second, and third independent sheets 56A, 56B, and 56C), and the independent sheets 56 are placed on each of the divided mounting surface sections 54 so that the color of each divided mounting surface section 54 changes independently.
In the drawing, different hatching indicates different colors of the independent sheets 56 .
Specifically, the three independent sheets 56 are each a different color, have the same rectangular shape and size corresponding to each of the three divided loading surface sections 54, and are configured to be placed on the three divided loading surface sections 54 without any gaps.
In this way, by preparing a large number of independent sheets 56 of different colors and placing appropriately selected independent sheets 56 on the three divided mounting surface portions 54, it is possible to perform imaging using the imaging device 14A with the three divided mounting surface portions 54 having different colors.
In the fifth embodiment, the same process as that shown in the flowchart of FIG. 4 described in the first embodiment is carried out to obtain a particle size accumulation curve.
As with the sheet 52 described above, the three independent sheets 56 can be made of various conventionally known materials such as paper, synthetic resin, woven fabric, nonwoven fabric, and felt.

According to the fifth embodiment, the color of each divided loading surface portion 54 is changed independently by the color changing section 16 made up of multiple independent sheets 56, so that image data of the granular material 2 dispersed on the divided loading surface portions 54, each having a different color, can be obtained by a single image capture using the imaging device 14A.
Therefore, as in the fourth embodiment, image data corresponding to divided loading surface portions 54 of different colors can be obtained at once, which is advantageous in improving efficiency when evaluating the accuracy of the contour data of the extracted granular material 2.
Therefore, it goes without saying that the same effects as those of the first embodiment can be achieved, and this is advantageous in terms of shortening the working time required to obtain the particle size accumulation curve.
Furthermore, by preparing a plurality of independent sheets 56 and placing an appropriately selected independent sheet 56 on the divided mounting surface portion 54, the color of each divided mounting surface portion 54 can be easily changed, so the color-changing portion 16 can be realized inexpensively, which is advantageous in reducing the cost of the particle size distribution measuring device.

2 Granular material 10 Particle size distribution measuring device 12A, 12B, 12C, 12D, 12E Container 14 Imaging unit 14A Imaging device La Optical axis 16 Color change unit 18 Computer 18A Input unit 18B Image processing unit 18C Particle size distribution calculation unit 18D Output unit 18E Communication unit 20 Placing surface unit 2002 Surface 2004 Back surface 22 Side wall 24 Light source device 2402 Main body unit 2404 Display screen 2404A, 2404B, 2404C Divided area 2406 Operation unit 26 Base 28 Stand 30 Input device 3002 Keyboard 3004 Mouse 32 Output device 3202 Display 3204 Printer 34 External storage device 36 Network 40 Grayscale image data generation unit 42 Binary data generation unit 44 Contour data generation unit 46 Particle size calculation unit 48 Light source device 48A Ring light 4802 Center axis 50 Stand 52 Sheets 52A and 52B Sheet 54 Divided mounting surface portions 54A, 54B, and 54C First, second, and third divided mounting surface portions 56 Independent sheets 56A, 56B, and 56C First, second, and third independent sheets C1 and C2 Particle size accumulation curve

Claims (8)

a loading surface portion onto which a granular material containing a mixture of granular materials of different particle sizes is introduced and dispersed;
an imaging unit that captures an image of the granular material dispersed on the placement surface and generates image data;
an image processing unit that calculates the particle size of the granular material based on the image data;
a particle size distribution calculation unit that calculates a particle size accumulation curve that indicates a particle size distribution of the granular material in the granular material based on the particle sizes of the granular material calculated by the image processing unit,
a color-changing portion that changes the color of the placement surface portion;
The mounting surface is divided into a plurality of divided mounting surface portions,
the color-changing portion changes color independently for each of the divided mounting surface portions;
A particle size distribution measuring device characterized by: the placement surface portion is formed to be light transmissive and includes a surface on which the granular material is dispersed and a back surface located opposite thereto;
the color changing unit is configured to irradiate light from the back surface side of the placement surface unit to the front surface side thereof and to change the color of the light;
2. The particle size distribution measuring device according to claim 1. The light source device is configured as a liquid crystal display or an organic EL display.
3. The particle size distribution measuring device according to claim 2. the mounting surface portion has a predetermined color over the entire surface on which the granular material is dispersed,
The color-changing unit is arranged at a position spaced above the surface, and is configured as a light source device that irradiates light onto the surface and the granular material dispersed on the surface and is configured to be able to change the color of the light.
2. The particle size distribution measuring device according to claim 1. The entire surface of the placement surface portion on which the granular material is dispersed is configured to be replaceable with a plurality of sheets,
The color-changing portion is composed of the plurality of sheets having different colors.
2. The particle size distribution measuring device according to claim 1. the image processing unit includes a grayscale image data generation unit that generates grayscale image data from the image data configured from RGB image data based on the following formula (1):
The values of the coefficients a, b, and c in the following formula (1) are configured to be adjustable relative to predetermined values.
6. The particle size distribution measuring device according to claim 1, wherein the particle size distribution measuring device is a particle size distribution measuring device.
Y=a*R+b*G+c*B…(1)
where Y: luminance, R: R image data, G: G image data, B: B image data, a, b, c: coefficients The image processing unit
a binary data generation unit that generates binary data from the grayscale image data;
a contour data generating unit that extracts contour data indicating contours of the granular material from the binarized data;
a particle size calculation unit that calculates the particle size of the granular material based on the contour data,
7. The particle size distribution measuring device according to claim 6 . The particle size calculation unit calculates the particle size by calculating the area of a closed region defined by the contour data, and then, assuming that the granular material is a sphere, determining the diameter of the sphere as the particle size from the calculation result of the area.
8. The particle size distribution measuring device according to claim 7 .