Mixture degree determination device and mixture degree determination method

Abstract

To provide a mixture degree determination device and a mixture degree determination method which can stably evaluate a mixture degree of a mixed material formed of plural types of particulate matters.SOLUTION: A mixture degree determination device comprises: an imaging unit 6 and an image acquisition processing unit 5a which acquire an original image obtained by imaging a mixed material 10 at a high resolution; an intermediate image generation unit 5b which generates a plurality of intermediate images which include the original image and in which the resolution of the original image is sequentially reduced; a binarization processing unit 5c which generates a binarized image obtained by discriminating one type of selected particulate matter selected from the plural types of particulate matters with respect to each intermediate image; a mixture degree calculation unit 5d which calculates a mixture degree of the selected particulate matter in each binarized image on the basis of the pixel number of the selected particulate matter in the binarized image; and a mixture degree determination unit 5e which determines the maximum value in the mixture degree of each binarized image as the mixture degree of the selected particulate matter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mixing degree determining device and a mixing degree determining method that can stably evaluate the mixing degree of a mixed material composed of multiple types of powder and granular materials. [Background technology]

[0002] Conventionally, in the preliminary stage of manufacturing resin molded products, a process of mixing multiple types of powders and granules, such as resin pellets, colorants, and foaming agents, is carried out. If the degree of mixing of these multiple types of powders and granules could be quantitatively evaluated, the mixing time of mixing equipment could be minimized. As a result, the quality of resin molded parts and other products could be improved and equipment costs could be reduced.

[0003] Here, a method using the Shannon index has been proposed to calculate the degree of mixing (see Non-Patent Document 1). This method calculates the Shannon entropy, and the value of this Shannon entropy is found as the degree of mixing, which indicates the degree of dispersion of powder particles.

[0004] Patent document 1 discloses a garbage mixing degree evaluation system in which a corrected image is gradated and binarized, the binarized image is divided into two or more evaluation areas each having a plurality of divided areas, and the garbage mixing degree of each evaluation area is evaluated.

[0005] Patent Document 2 discloses a method for evaluating the degree of mixing of a resin product, in which the evaluation is performed using a measured area ratio calculated from a plurality of photographed images.

[0006] Patent Document 3 discloses a powder mixing system that calculates the degree of mixing based on the probability of a specific powder being present in an entire image of the mixed powder, and terminates mixing when the degree of mixing satisfies a predetermined condition. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6457137 [Patent Document 2] Japanese Patent Application Publication No. 2019-60805 [Patent Document 3] Patent Publication No. 2021-58860 [Non-patent literature]

[0008] [Non-Patent Document 1] "Quantitative Evaluation of Mixing Degree of Powder and Granular Materials by Shannon Entropy" by Yoichi Nakata et al., Journal of the Japan Society of Powder Technology, Vol. 57 No. 5 pp. 296-304, 2017 Summary of the Invention [Problem to be solved by the invention]

[0009] The quantitative evaluation of the degree of mixing of powder and granular materials using the Shannon entropy method calculates the degree of mixing using a model that treats each powder and granular material as a single point. However, actual powder and granular materials have a finite size and do not necessarily appear as a single pixel on an image. If the image resolution is appropriate, one pixel corresponds to one powder or granular material. However, if the image resolution is too high, multiple pixels correspond to one powder or granular material, and if the image resolution is insufficient, the pixel corresponding to one powder or granular material disappears. If the image resolution is too high and multiple pixels correspond to one powder or granular material, the calculated degree of mixing is as if multiple particles were aggregated, resulting in a lower value of the degree of mixing than the appropriate degree of mixing (see Figure 2). Furthermore, if the image resolution is insufficient, the pixel of the powder or granular material disappears, resulting in a lower value of the degree of mixing than the appropriate degree of mixing. Therefore, when determining the degree of mixing of a mixed material composed of multiple types of powder or granular materials, the degree of mixing varies depending on the resolution of the image captured of the mixed material, making it difficult to perform a stable quantitative evaluation of the degree of mixing.

[0010] The present invention has been made to solve the above-mentioned problems, and aims to provide a mixing degree determination device and a mixing degree determination method that can stably evaluate the mixing degree of a mixed material composed of multiple types of powder and granular materials. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems and achieve the object, the present invention provides a mixing degree determination device for determining the mixing degree of a mixed material composed of multiple types of powder or granules different from each other in color, the device comprising: an image acquisition unit for acquiring an original image obtained by capturing an image of the mixed material at high resolution; an intermediate image generation unit for generating multiple intermediate images including the original image and having successively lower resolutions of the original image; a binarization processing unit for generating a binary image for each intermediate image in which one type of selected powder or granule is clearly distinguished from the multiple types of powder or granules; a mixing degree calculation unit for calculating the mixing degree of the selected powder or granule in each binary image based on the number of pixels of the selected powder or granule in the binary image; and a mixing degree determination unit for determining the maximum value of the mixing degrees of the selected powder or granule in each binary image as the mixing degree of the selected powder or granule. The mixing degree calculation unit calculates the mixing degree of the selected powder or granular material in each binarized image using a Shannon index. It is characterized by:

[0013] Furthermore, in the above invention, the present invention is characterized in that the mixture degree calculation unit divides each binary image into a plurality of sub-cells and calculates the mixture degree of each binary image based on the mixture degree of each sub-cell.

[0014] Furthermore, in the present invention, the mixture degree calculation unit calculates, as the mixture degree, a value obtained by taking a moving average of the mixture degrees of each binarized image with respect to resolution.

[0015] In the present invention, the original image has a higher resolution than the intermediate image in which one selected powder or granule corresponds to one pixel.

[0016] The present invention also provides a mixing degree determination method for determining the mixing degree of a mixed material composed of a plurality of types of powder or granules different in color, the method including: an image acquisition step for acquiring an original image of the mixed material captured at high resolution; an intermediate image generation step for generating a plurality of intermediate images including the original image and having successively lower resolutions of the original image; a binarization processing step for generating a binary image for each intermediate image in which one selected powder or granule is clearly distinguished from the plurality of types of powder or granules; a mixing degree calculation step for calculating the mixing degree of the selected powder or granule in each binary image based on the number of pixels of the selected powder or granule in the binary image; and a mixing degree determination step for determining the maximum value of the mixing degrees of the respective binary images as the mixing degree of the selected powder or granule. and the mixing degree calculation step calculates the mixing degree of the selected powder or granule in each binarized image using a Shannon index. It is characterized by: [Effects of the Invention]

[0017] According to the present invention, it is possible to stably evaluate the degree of mixing of a mixed material composed of multiple types of powder and granular materials. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a mixing degree determining device according to this embodiment. [Figure 2] FIG. 2 is an explanatory diagram illustrating the relationship between the size of the selected powder particles in the original image and the number of pixels of the selected powder particles due to differences in resolution. [Figure 3] FIG. 3 is an explanatory diagram showing an example of the generation of an intermediate image and the result of binarization processing of the intermediate image. [Figure 4] FIG. 4 is an explanatory diagram for explaining the calculation of Shannon entropy. [Figure 5] FIG. 5 is a diagram showing the change in the degree of mixing relative to the resolution of each binarized image. [Figure 6] FIG. 6 is a diagram showing the change in the degree of mixing with the increase in the mixing time. [Figure 7] FIG. 7 is a flowchart showing the procedure of the mixing degree determination process performed by the control unit. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, a mixing degree determining device and a mixing degree determining method according to the present embodiment will be described with reference to the accompanying drawings.

[0020] <Summary configuration> Fig. 1 is a schematic diagram showing the configuration of a mixing degree determination device 1 according to this embodiment. As shown in Fig. 1, the mixing degree determination device 1 uses an imaging unit 6 to capture an image of the surface of a mixed material 10 made up of multiple types of powders and granules that are different from each other in color, and determines the mixing degree of one selected type of powder and granules selected from the multiple types of powder and granules based on the captured image. The powder and granules include resin pellets, colorants, foaming agents, etc., and the multiple types of powder and granules are mixed material 10 that has been stirred by a stirring device.

[0021] The mixing degree determination device 1 includes a device main body 1a and an imaging unit 6 connected to the device main body 1a. The imaging unit 6 is an imaging device such as a camera. The device main body 1a includes an input unit 2, a display unit 3, a storage unit 4, and a control unit 5.

[0022] The input unit 2 is an input interface such as a mouse or keyboard. The display unit 3 is a display interface such as a liquid crystal display that displays various information. The storage unit 4 is a storage device such as a hard disk drive or nonvolatile memory.

[0023] The control unit 5 is a control unit that controls the entire mixing degree determination device 1, and has an image acquisition processing unit 5a, an intermediate image generation unit 5b, a binarization processing unit 5c, a mixing degree calculation unit 5d, and a mixing degree determination unit 5e. The control unit 5 stores programs corresponding to these functional units in a storage device such as a nonvolatile memory or a magnetic disk device, and loads these programs into memory and executes them on the CPU, thereby causing the corresponding processes to be executed.

[0024] The image acquisition processing section 5a operates the imaging section 6 to acquire a high-resolution original image of the surface of the mixed material 10. The imaging section 6 and the image acquisition processing section 5a function as an image acquisition section.

[0025] The intermediate image generation unit 5b generates a plurality of intermediate images, each having a resolution successively lower than the original image, including the high-resolution original image acquired by the image acquisition processing unit 5a. The intermediate image generation unit 5b generates intermediate images with successively lower resolutions by reducing the image size of the original image. The image size is reduced, for example, by 1% increments, assuming the original image to be 100%, until the size reaches 1% of the original image. The image size reduction interval may be an arithmetic progression, reducing the image size by 1%, or a geometric progression, reducing the image size by half. If the original image has 1 million pixels, the number of pixels of a 1% intermediate image will be 10,000 pixels.

[0026] The binarization processing unit 5c generates a binarized image for each intermediate image, clearly distinguishing one type of selected powder or granular material from multiple types of powder or granular material. The binarization process performs binarization to clearly distinguish the selected powder or granular material from other powder or granular materials. This binarization process may be, for example, adaptive threshold processing or Otsu's binarization process. The adaptive binarization process sets local regions of arbitrary size within the entire image, calculates a threshold for each local region, and binarizes each image. The Otsu's binarization process searches for a threshold that minimizes the weighted intra-class variance to binarize each pixel.

[0027] The mixture degree calculation unit 5d calculates the mixture degree of the selected powder or granule in each binary image based on the number of pixels of the selected powder or granule in each binary image. This mixture degree is obtained by calculating the Shannon entropy, which is the entropy using the Shannon index.

[0028] The mixture degree determining unit 5e determines the maximum value of the mixture degrees of each binarized image calculated by the mixture degree calculating unit 5d as the mixture degree of the selected powder or granular material, and outputs it to the display unit 3 or the storage unit 4.

[0029] The purpose of generating multiple intermediate images with different resolutions is to obtain an image in which one selected powder or granule corresponds to one pixel on the image. As shown in FIG. 2, original image D contains a mixture 10 of white powder or granules 12 and black powder or granules 11. To calculate the mixing degree of the black powder or granules 11, the resolution of binarized image D2a is such that one selected powder or granule 11 corresponds to one pixel on binarized image D2a. However, if the image resolution is too high, multiple pixels (four pixels) are associated with one powder or granule 11 on original image D, and the calculated mixing degree is calculated as if four powder or granules 11 were aggregated, resulting in a lower mixing degree than the appropriate mixing degree. If the resolution of the binarized image is insufficient, the pixel corresponding to one powder or granule 11 will disappear, resulting in an incorrect mixing degree being calculated. Thus, when determining the degree of mixing of a mixed material composed of multiple types of powder or granular materials, the degree of mixing varies depending on the resolution of the image of the mixed material, making it impossible to perform a stable quantitative evaluation of the degree of mixing. Therefore, in this embodiment, multiple intermediate images with different resolutions are generated so that a binary image with an appropriate resolution for one selected powder or granular material is included. Note that the resolution of the original image D must be greater than the appropriate resolution. Note that in this embodiment, it is not necessary to know the average particle size of the powder or granular material in advance when determining the degree of mixing.

[0030] <Intermediate image generation and binarization processing> 3 is an explanatory diagram showing an example of the results of generating an intermediate image and binarizing the intermediate image. As shown in FIG. 3, the image acquisition processing unit 5a acquires a surface image of the mixed material 10 as an original image D0 using the imaging unit 6. Here, the mixed material 10 is assumed to be a mixture of white powder and granular material 12 and black powder and granular material 11, and a case will be described in which the mixing degree of the black powder and granular material 11 is calculated.

[0031] The intermediate image generation unit 5b generates a plurality of intermediate images D1 (D1-1 to D1-n) including the original image D0, each having a resolution successively lower than that of the original image D0. The intermediate image D1-n is the image with the lowest resolution. As described above, a reduction in resolution is the same as a reduction in image size. The intermediate image D1-1 is the same as the original image D0. The intermediate image D1-k is an image in which one pixel is approximately the same as one powder or granular material 11.

[0032] The binarization processing unit 5c performs binarization processing on each of the generated intermediate images D1 to generate multiple binarized images D2 (D2-1 to D2-n). In the binarized image D2-1, the resolution is too high, so there are four pixels corresponding to one powder or granular material 11. In the binarized image D2-k, there is one pixel corresponding to one powder or granular material 11. In the binarized image D2-n, the pixel corresponding to the particle size of one powder or granular material 11 is too large, so the pixel corresponding to one powder or granular material 11 has disappeared.

[0033] <Mixing degree calculation process> The mixture degree calculation unit 5d calculates the mixture degree of the powder or granular material 11 in each binarized image D2 using the Shannon index. The mixture degree is calculated by calculating the entropy (Shannon entropy S) value using the Shannon index using the following equation (1).

number

[0034] where the term A in equation (1) represents the degree of mixing within the subcell Es, A = (percentage of white pixels) x ln (percentage of white pixels) + (percentage of black pixels) x ln (percentage of black pixels) The degree of mixing in the subcell Es is calculated as follows: Note that pi is the ratio of the number of powder particles in sub-cell Es to the total number of powder particles in the inspection area E, but it can be interpreted as the number of black pixels in sub-cell Es to the number of black pixels in the inspection area E, without counting white pixels in the binary image D2.

[0035] As a result, the Shannon entropy S is calculated by multiplying the term A, which indicates the degree of mixing within the subcell Es, by pi for each subcell Es, and then summing up the M values ​​obtained.

[0036] Figure 5 shows the change in the degree of mixture (Shannon entropy S) with respect to the resolution of each binarized image D2. The curve L in Figure 5 shows the change in the degree of mixture with respect to the resolution of the binarized image D2. When the resolution is high, the degree of mixture decreases because multiple black pixels correspond to one powder or granular material 11, and as the resolution increases, the degree of mixture decreases due to the increased aggregation. On the other hand, when the resolution is low, the degree of mixture decreases because the number of black pixels for one powder or granular material 11 disappears. When the resolution is Pa, the degree of mixture reaches its maximum value Smax. The resolution of Pa is the resolution of the binarized image D2-k. When the degree of mixture is at its maximum value Smax, one black pixel corresponds to one powder or granular material 11, and the degree of mixture is determined to be appropriate, and this maximum value Smax is output as the degree of mixture of the powder or granular material 11. This allows for a stable determination of an appropriate degree of mixture. Furthermore, even when there is variation in the particle size of a single selected powder or granular material, a stable and appropriate degree of mixture can be determined. In addition, in this embodiment, it is not necessary to know the particle size of one selected powder or granular material.

[0037] The degree of mixing determined in this way increases with the increase in the mixing time of the mixer, as shown in Figure 6. Then, once a certain mixing time is exceeded, the degree of mixing becomes saturated, so it is possible to determine the optimal mixing time.

[0038] As shown in FIGS. 5 and 6, the change in the degree of mixture may fluctuate as the resolution changes, so it is preferable to obtain the average degree of mixture obtained by taking a moving average for a plurality of adjacent resolutions.

[0039] <Mixture Degree Determination Processing Procedure> 7 is a flowchart showing the procedure of the mixing degree determination process performed by the control unit 5. As shown in FIG. 7, first, the image acquisition processing unit 5a acquires an original image D0 obtained by capturing an image of the mixed material 10 at high resolution (step S110). The resolution of the original image D0 is higher than the resolution at which one selected powder or granular material corresponds to one pixel. Thereafter, the intermediate image generating unit 5b generates a plurality of intermediate images D1 including the original image D0 and having successively lower resolutions than the original image D0 (step S120).

[0040] Thereafter, the binarization processing unit 5c generates a binarized image D2 in which one type of selected powder or granule is clearly distinguished from the multiple types of powder or granule for each intermediate image D1 (step S130). Then, the mixture degree calculation unit 5d calculates the mixture degree (Shannon entropy S) of the selected powder or granule in each binarized image D2 based on the number of pixels of the selected powder or granule in the binarized image D2 using the Shannon index (step S140). Thereafter, the mixture degree determination unit 5e determines the maximum value of the mixture degrees of each binarized image as the mixture degree of the selected powder or granule (step S150), outputs it to the display unit 3 or the storage unit 4, and ends this process.

[0041] In the above embodiment, an example was shown in which the degree of mixing of the powder 12 in a mixed material 10 containing a mixture of black powder 11 and white powder 12 was calculated. However, the degree of mixing can also be calculated for a single color of powder in a mixed material composed of multiple types of powders of different colors. For example, to calculate the degree of mixing of red powder, an image of the mixed material is captured using a color image sensor, and a binarized image containing only the R component is generated. Furthermore, for powders of any color, an image of the extracted color components is generated, and the image is then binarized.

[0042] Note that the configurations illustrated in the above embodiments and modifications are merely functional schematics and do not necessarily have to be physically configured as shown. In other words, the distribution and integration of each device is not limited to that illustrated, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc. [Industrial Applicability]

[0043] The device and method for determining the degree of mixing of the present invention are useful for stably evaluating the degree of mixing of a mixed material made up of multiple types of powder and granular material. [Explanation of symbols]

[0044] 1 Mixing degree determination device 1a Device body 2 Input section 3 Display section 4 Storage section 5. Control section 5a Image acquisition processing section 5b Intermediate image generation unit 5c Binarization processing section 5d Mixing degree calculation part 5e Mixing degree determination section 6. Imaging unit 10 Mixed materials 11,12 Powder D,D0 Original image D1, D1-1 to D1-n intermediate images D2, D2-1 to D2-n, D2a, D2b binarized images E Inspection area Es subcell L curve S Shannon entropy Smax Maximum value

Claims

1. A mixing degree determination device for determining the mixing degree of a mixed material composed of multiple types of powder and granular materials with different colors, an image acquisition unit that acquires an original image of the mixed material captured at high resolution; an intermediate image generating unit that generates a plurality of intermediate images including the original image and having successively lower resolutions of the original image; a binarization processing unit that generates a binarized image for each intermediate image in which one type of selected powder or granule is clearly distinguished from the plurality of types of powder or granule; a mixture degree calculation unit that calculates a mixture degree of the selected powder or granule in each binary image based on the number of pixels of the selected powder or granule in each binary image; a mixture degree determination unit that determines the maximum value of the mixture degrees of each binary image as the mixture degree of the selected powder or granular material; Equipped with The mixing degree determining device is characterized in that the mixing degree calculation unit calculates the mixing degree of the selected powder or granular material in each binarized image using a Shannon index.

2. 2. The device according to claim 1, wherein the mixture degree calculation unit divides each binary image into a plurality of subcells and calculates the mixture degree of each binary image based on the mixture degree of each subcell.

3. 3. The apparatus according to claim 1, wherein the mixture degree calculation unit calculates, as the mixture degree, a moving average of the mixture degrees of the binarized images with respect to the resolution.

4. 4. The mixing degree determination device according to claim 1, wherein the resolution of the original image is higher than that of the intermediate image in which one selected powder or granule corresponds to one pixel.

5. A method for determining the degree of mixing of a mixed material composed of multiple types of powder or granular material having different colors, comprising: an image acquisition step of acquiring an original image of the mixed material at high resolution; an intermediate image generating step of generating a plurality of intermediate images including the original image and having successively lower resolutions of the original image; a binarization processing step for generating a binarized image for each intermediate image in which one type of selected powder or granule is clearly distinguished from the plurality of types of powder or granule; a mixing degree calculation step of calculating a mixing degree of the selected powder or granule in each binary image based on the number of pixels of the selected powder or granule in each binary image; a mixing degree determination step of determining the maximum value of the mixing degrees of each binarized image as the mixing degree of the selected powder or granule; Including, The method for determining a degree of mixture, wherein the degree of mixture calculation step calculates the degree of mixture of the selected powder or granular material in each binarized image using a Shannon index.

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