X-ray examination device

Abstract

To provide an X-ray examination device that can distinguish between a slender-shaped foreign matter as a whole and a stubby shape foreign matter as a whole while keeping productivity.SOLUTION: An X-ray examination device comprises: a determination unit that determines whether an article is normal or abnormal on the basis of an X-ray transmission image. The determination unit is configured to: separate the X-ray transmission image to a plurality of regions on the basis of a shading difference between adjacent pixels; and, when there is no region formed so as to be an area, length or a degree of congestion more than a prescribed threshold by the pixel more than a prescribed shading value in the plurality of regions, and there is at least one specific region formed so as to be an area, length or a degree of congestion less than the prescribed threshold by the pixel more than the prescribed shading value in the plurality of regions, determine whether an article is normal or abnormal on the basis of a length of a first side of a circumscription rectangle with respect to at least one of the specific regions, and a length of a second side connecting to the first side, and greater than the length of the first side.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] One aspect of the present invention relates to an X-ray inspection apparatus. [Background technology]

[0002] X-ray inspection devices are known that irradiate transported objects to be inspected with X-rays, receive the X-rays that pass through the object, generate an X-ray transmission image, and then use the X-ray transmission image to inspect the object for foreign objects. Such X-ray inspection devices utilize the characteristic that foreign objects such as metal, stone, and glass appear darker than the object being inspected, such as food, to extract pixels within a predetermined density range from the image and determine the presence or absence of foreign objects. However, increasing the foreign object detection sensitivity of such X-ray inspection devices can lead to the detection of foreign objects of a size that is not dangerous even if mixed in as problematic foreign objects, thereby reducing productivity. Patent Document 1 addresses this issue by configuring an X-ray inspection device to not detect foreign objects smaller than a certain size as problematic foreign objects, based on parameters such as the area and length of pixels within a predetermined density range, thereby preventing false detections and improving productivity. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-172510 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, there is a demand for detecting foreign objects that are generally elongated and pose a risk of becoming lodged in a part of the oral cavity, even if the foreign object is smaller than a predetermined size, as a problematic foreign object. However, among foreign objects that are smaller than a predetermined size, there are foreign objects that are generally short and thick and pose a small risk of becoming lodged in a part of the oral cavity. For this reason, with the above-mentioned conventional X-ray inspection device that determines whether a foreign object is problematic based on size, it is difficult to distinguish between foreign objects that are generally elongated and pose a risk of becoming lodged in a part of the oral cavity, while maintaining productivity.

[0005] Therefore, an object of one aspect of the present invention is to provide an X-ray inspection apparatus that can distinguish between foreign matter that is elongated overall and foreign matter that is thick and short overall while maintaining productivity. [Means for solving the problem]

[0006] (1) An X-ray inspection device according to one aspect of the present invention comprises a conveying unit that conveys an article, an X-ray source that irradiates X-rays onto an article conveyed by the conveying unit, an X-ray detection unit that detects X-rays, an X-ray image generation unit that generates an X-ray transmission image based on the X-ray detection result by the X-ray detection unit, and a judgment unit that judges whether the article is normal or abnormal based on the X-ray transmission image. The judgment unit divides the X-ray transmission image into multiple regions based on the difference in grayscale between adjacent pixels, and judges the article to be abnormal if at least one region among the multiple regions is formed so that it has an area, length, or density greater than a predetermined threshold value and is made up of pixels with a predetermined grayscale value or greater. If there is no region among the multiple regions that has an area, length, or density greater than the predetermined threshold value and the multiple regions includes at least one specific region that has pixels with a predetermined grayscale value or greater than the predetermined threshold value and is made up of pixels with an area, length, or density less than the predetermined threshold value, the judgment unit judges whether the article is normal or abnormal based on the length of a first side of a circumscribing rectangle for at least one of the specific regions and the length of a second side that is greater than or equal to the length of the first side connected to the first side.

[0007] In this X-ray inspection system, a region formed by pixels having a predetermined gray level or greater, with an area, length, or density greater than or equal to a predetermined threshold, is determined to contain a foreign object of a predetermined size or greater. In addition, in this X-ray inspection system, a region formed by pixels having a predetermined gray level or greater, with an area, length, or density less than the predetermined threshold, is determined to contain a foreign object of a smaller size. Based on the ratio of the first and second sides of the circumscribing rectangle for the region containing a foreign object determined to be smaller than the predetermined size, the X-ray inspection system distinguishes whether the foreign object has an overall elongated shape or an overall thick and short shape. This allows for differentiation between an overall elongated shape and an overall thick and short shape while maintaining productivity.

[0008] (2) In the X-ray inspection device described in (1) above, if the ratio of the length of the second side to the length of the first side is within a first set range, or if the ratio of the length of the first side to the length of the second side is within a second set range, it may be determined that the object is abnormal. In this configuration, if the degree of thinness is at a predetermined level, it can be determined that the foreign object is elongated overall.

[0009] (3) The X-ray inspection device of (2) above may include a setting unit that sets the first set range or the second set range. This configuration enables detection of an article that contains a foreign object with a degree of thinness that the user wants to remove.

[0010] (4) Any one of the X-ray inspection devices (1) to (3) above includes a display unit that displays the inspection results by the determination unit, and if a specific region is found, the display unit may display the area, length, density, ratio of the length of the second side to the length of the first side, or ratio of the length of the first side to the length of the second side of the corresponding region. With this configuration, it is possible to easily check the characteristics of foreign matter smaller than a predetermined size.

[0011] (5) In the X-ray inspection device of (4) above, if a specific region is present, the display unit may display the area, length, density, maximum value, minimum value, average value, or standard deviation of the corresponding region's area, length, density, ratio of the second side length to the first side length, or ratio of the first side length to the second side length. With this configuration, it is easy to check the characteristics of foreign matter smaller than a predetermined size. [Effects of the Invention]

[0012] According to one aspect of the present invention, it is possible to distinguish between foreign matter having an elongated shape overall and foreign matter having a thick, short shape overall while maintaining productivity. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a configuration diagram of an X-ray inspection apparatus according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the internal configuration of the shielding box shown in FIG. [Figure 3] FIG. 3 is a functional configuration diagram of the controller. [Figure 4] 4(A) and 4(B) are diagrams each showing an example of an X-ray transmission image including an imaged object. [Figure 5] FIG. 5 is a flowchart showing an example of a method for determining whether or not there is a problematic foreign object in an article. [Figure 6] FIG. 6 is a diagram showing an example of a pixel of interest and a region of interest. [Figure 7] Each of FIG. 7(A) and FIG. 7(B) is a diagram for explaining a circumscribing rectangle corresponding to a specific region. [Figure 8] FIG. 8 is a flowchart showing an example of a method for determining the presence or absence of a problematic foreign object in an article according to a modified example. [Figure 9] 9(A) and 9(B) are diagrams each showing an example of an X-ray transmission image including an imaged object. [Figure 10] Each of FIGS. 10(A) to 10(D) is a diagram showing an X-ray transmission image including a captured object. DETAILED DESCRIPTION OF THE INVENTION

[0014] A preferred embodiment of one aspect of the present invention will be described in detail below with reference to the accompanying drawings. In the description of the drawings, identical or corresponding elements are designated by the same reference numerals, and duplicate explanations will be omitted. Furthermore, in this specification, "A or B" means that either A or B is included, and does not exclude the inclusion of both A and B.

[0015] As shown in Fig. 1, the X-ray inspection apparatus 1 includes an apparatus main body 2, support legs 3, a shielding box 4, a conveying unit 5, an X-ray irradiation unit 6 (X-ray source), an X-ray detection unit 7, a display operation unit 8, and a controller 10. The X-ray inspection apparatus 1 generates an X-ray transmission image of the article G while conveying the article G, and inspects the article G based on the X-ray transmission image. The article G before inspection is carried into the X-ray inspection apparatus 1 by a carry-in conveyor 51. The article G after inspection is carried out of the X-ray inspection apparatus 1 by a carry-out conveyor 52.

[0016] The device main body 2 houses a controller 10 and the like. The support legs 3 support the device main body 2. The shielding box 4 is provided on the device main body 2. The shielding box 4 is a housing that prevents leakage of X-rays (electromagnetic waves) to the outside. Inside the shielding box 4 is provided an inspection room R where inspection of items G is carried out using X-rays. The shielding box 4 is formed with an entrance 4a and an exit 4b. Items G before inspection are carried into the inspection room R from the entrance 4a on the carry-in conveyor 51. After inspection, the items G are carried out from the inspection room R to the exit conveyor 52 via the exit 4b.

[0017] The transport unit 5 is a member that transports the article G, and is disposed so as to pass through the center of the shielding box 4. The transport unit 5 transports the article G in a transport direction A from the entrance 4a through the inspection room R to the exit 4b. The speed (transport speed) at which the article G is transported by the transport unit 5 is set, for example, by the controller 10. The transport unit 5 is, for example, a belt conveyor stretched between the entrance 4a and the exit 4b. Note that the transport unit 5 may protrude outward beyond the entrance 4a and the exit 4b.

[0018] As shown in Figures 1 and 2, the X-ray irradiation unit 6 is an electromagnetic wave irradiation unit arranged inside the shielding box 4, and irradiates X-rays onto the object G transported by the transport unit 5. The X-rays include X-rays in various energy ranges from low energy (long wavelength) to high energy (short wavelength). Therefore, the X-ray irradiation unit 6 irradiates X-rays in multiple energy ranges onto the object G transported by the transport unit 5. Note that the terms "low" and "high" in the above-mentioned low energy and high energy indicate relatively "low" and "high" within the multiple energy ranges irradiated by the X-ray irradiation unit 6, and do not indicate a specific range.

[0019] The X-ray detection unit 7 is a sensor member (electromagnetic wave sensor) that detects electromagnetic waves and is disposed within the shield box 4. The X-ray detection unit 7 detects X-rays in each of a plurality of energy bands that have passed through the article G. In this embodiment, the X-ray detection unit 7 is configured to detect X-rays in a low-energy band and X-rays in a high-energy band. That is, the X-ray detection unit 7 has a first line sensor 11 and a second line sensor 12. The sensor member may be a member that detects X-rays in one energy band, or a member that detects X-rays in a plurality of energy bands (a multi-energy sensor member). The first line sensor 11 and the second line sensor 12 each include a plurality of X-ray detection elements that are linearly arranged along a horizontal direction perpendicular to the conveying direction A. The first line sensor 11 detects X-rays in the low-energy band that have passed through the article G and the conveyor belt of the conveyor unit 5. The second line sensor 12 detects X-rays in the high-energy band that have passed through the article G, the conveyor belt of the conveyor unit 5, and the first line sensor 11. The X-ray detection unit 7 may be a component having a single line sensor, or may be a direct conversion type detection unit that can detect X-rays using a photon counting method. When the X-ray detection unit 7 is the direct conversion type detection unit, the configuration, settings, operation, etc. of the X-ray detection unit 7 are performed, for example, by a method described in JP 2023-132587 A.

[0020] As shown in FIG. 1, a display operation unit (display unit) 8 is provided in the device main body 2. The display operation unit 8 displays various information and accepts input operations of various conditions from the outside. The display operation unit 8 is, for example, a liquid crystal display, and displays an operation screen as a touch panel. In this case, the operator can input various conditions via the display operation unit 8. For example, the operator can set the operating conditions of the X-ray inspection device 1, the conveying speed of the conveying unit 5, various judgment conditions for foreign substance judgment, etc. via the display operation unit 8. The input operations accepted by the display operation unit 8 are output to the conveying unit 5, the X-ray detection unit 7, the controller 10, etc.

[0021] The controller 10 is disposed inside the device main body 2. The controller 10 controls the operation of each part of the X-ray inspection device 1. The controller 10 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. Programs for controlling the X-ray inspection device 1, etc. are stored in the ROM.

[0022] As shown in FIG. 3, the controller 10 includes a detection result acquisition unit 21, an X-ray image generation unit 22, a determination unit 23, an output unit 24, and a storage unit 25.

[0023] The detection result acquisition unit 21 acquires the detection result signal output from the X-ray detection unit 7. The detection result acquisition unit 21 transmits the acquired detection result signal to the X-ray image generation unit 22.

[0024] The X-ray image generation unit 22 is mainly composed of, for example, a GPU (Graphics Processing Unit) and expands the detection result signal into a two-dimensional image in memory. The memory in which the two-dimensional image is expanded is, for example, a memory included in the GPU, but is not limited to this. The X-ray image generation unit 22 generates one or more types of X-ray transmission images used for inspecting the item G, for example, based on the X-ray detection results by the X-ray detection unit 7. As one of the X-ray transmission images, the X-ray image generation unit 22 generates, for example, a total transmission image corresponding to all X-rays in the multiple energy bands based on the detection results. The total transmission image is generated, for example, based on all information included in the detection result signal. When generating the total transmission image, information considered to be noise may be excluded in advance. In this case, the total transmission image is generated based on a portion of the information included in the detection result signal.

[0025] The X-ray image generating section 22 may generate one or more types of transmission images corresponding to some of the X-rays in the plurality of energy bands in addition to the entire transmission image. In this case, the X-ray image generating section 22 may generate, as the transmission images, a first transmission image generated based on the X-ray detection result of the first line sensor 11 included in the detection result signal, a second transmission image generated based on the X-ray detection result of the second line sensor 12 included in the detection result signal, and a difference image obtained by subtraction processing of the first transmission image and the second transmission image.

[0026] The X-ray image generation unit 22 generates the above-mentioned X-ray transmission image using, for example, an image processing algorithm. At least one of the multiple image processing algorithms can be automatically generated from multiple image processing filters based on the specifications of the X-ray inspection device 1, the inspection conditions, etc., by adopting a genetic algorithm (GA), which is a method that applies the mechanisms of heredity and evolution in the biological world. At least some of the multiple image processing algorithms can also be set appropriately by the operator via the display operation unit 8.

[0027] The determination unit 23 determines whether the article G is normal or abnormal based on the X-ray transmission image generated by the X-ray image generation unit 22. When the X-ray image generation unit 22 generates multiple X-ray transmission images, the determination unit 23 determines whether the article G is normal or abnormal based on at least a portion of the multiple X-ray transmission images. The determination unit 23 determines whether the article G is normal or abnormal, for example, based on each of the entire transmission image and the above transmission image. Alternatively, the determination unit 23 determines whether the article G is normal or abnormal based on each of an X-ray transmission image generated using a first image processing algorithm and another X-ray transmission image generated using a second image processing algorithm. When multiple X-ray transmission images are generated, the determination of the article G based on each image may be performed simultaneously or at different times. For example, the determination of the article G based on the entire transmission image may be performed while the X-ray image generation unit 22 is generating the above transmission image.

[0028] The determination unit 23 determines whether the item G is normal or abnormal based on the inspection results for the presence or absence of foreign matter on the item G. For example, if the inspection results indicate that the item G contains problematic foreign matter, the determination unit 23 determines that the item G is abnormal (i.e., the item G is a defective product). Problematic foreign matter includes, for example, foreign matter of a predetermined size or larger and foreign matter smaller than the predetermined size that has an elongated shape overall, and these foreign matter must be removed from the item G. In other words, foreign matter smaller than the predetermined size that has an elongated shape overall is considered to be unproblematic and does not need to be removed from the item G. Therefore, an item G containing only unproblematic foreign matter may be determined to be normal and may be a good product without the need to remove the foreign matter. Note that even if the item G contains only unproblematic foreign matter, if a large number of such foreign matter is included, the item G may be determined to be abnormal. The threshold value for the number of foreign matter may be set appropriately depending on the type of item G, etc.

[0029] An example of a method for determining whether or not a problematic foreign substance exists in an article G will be described below with reference to FIGS. 4(A), 4(B), 5, 6, and 7. X-ray transmission images P1 and P2 are shown in FIGS. 4(A) and 4(B), respectively. Articles G1 and G2 are shown in the X-ray transmission images P1 and P2, respectively. As shown in FIG. 5, before the determination unit 23 determines whether or not a foreign substance exists in the article G, the determination unit 23 divides the X-ray transmission image into multiple regions based on the grayscale difference between adjacent pixels as a preprocessing step (step S11). For example, the determination unit 23 divides the X-ray transmission image P1 into regions R1 to R4 as shown in FIG. 4(A), and divides the X-ray transmission image P2 into regions R11 to R14 as shown in FIG. 4(B). Each of the regions R1 to R4 and the regions R11 to R14 is formed by a pixel group whose grayscale difference is less than a predetermined threshold. That is, each of the regions R1 to R4 and regions R11 to R14 is a collection of pixels whose grayscale difference is less than a predetermined threshold (similar grayscale).

[0030] On the other hand, for example, the difference in shading between a pixel (pixel A) included in region R1 and adjacent to region R2 and a pixel adjacent to pixel A and included in region R2 is equal to or greater than a predetermined threshold. The above-mentioned predetermined threshold can be adjusted as appropriate depending on, for example, the type of article G, the type of foreign matter that may be included in article G, the type of image processing algorithm, etc. This allows the X-ray transmission image to be effectively divided into multiple regions depending on the type of article G, etc.

[0031] In Fig. 4(A), all pixels in region R1 have substantially the same grayscale value, all pixels in region R2 have substantially the same grayscale value, all pixels in region R3 have substantially the same grayscale value, and all pixels in region R4 have substantially the same grayscale value, but this is not limited to this. Also, in Fig. 4(B), all pixels in region R11 have substantially the same grayscale value, all pixels in region R12 have substantially the same grayscale value, all pixels in region R13 have substantially the same grayscale value, and all pixels in region R14 have substantially the same grayscale value, but this is not limited to this.

[0032] For example, in the X-ray transmission image P1 of FIG. 4(A), the average grayscale value of region R1 is the lowest, and the average grayscale values ​​of regions R3 and R4 are the highest. For example, in the X-ray transmission image P2 of FIG. 4(B), the average grayscale value of region R11 is the lowest, and the average grayscale values ​​of regions R13 and R14 are the highest. Regions R1 and R11 indicate imaged portions outside the region of article G. The grayscale values ​​described in this embodiment will be explained taking as an example a case where the darker the pixel, the lower the grayscale value, and the brighter the pixel, the higher the grayscale value. However, it is also possible to use grayscale values ​​that are expressed as higher for darker pixels and lower for brighter pixels.

[0033] In the determination of the presence or absence of a foreign object G by the determination unit 23, as shown in FIG. 5, in a first step, the determination unit 23 determines whether at least one of a plurality of regions in one X-ray transmission image (P1 or P2) is formed by pixels having a first gray value (predetermined gray value) or more, so that the area, length, or density is equal to or greater than a first threshold (predetermined threshold) (step S12). For example, in the case of the X-ray transmission image P1 shown in FIG. 4(A), the determination unit 23 determines whether at least one of a plurality of regions R1 to R4 in one X-ray transmission image P1 is formed by pixels having a first gray value or more, so that the area, length, or density is equal to or greater than the first threshold. Also, for example, in the case of the X-ray transmission image P2 shown in FIG. 4(B), the determination unit 23 determines whether at least one of a plurality of regions R11 to R14 in one X-ray transmission image P2 is formed by pixels having a first gray value or more, so that the area, length, or density is equal to or greater than the first threshold.

[0034] The density used in step S12 is data that serves as the basis for the determination unit 23's determination of the presence or absence of a foreign substance, and is calculated, for example, according to the method disclosed in Japanese Patent Application Laid-Open No. 2005-172510. As an example, as shown in FIG. 6, the density is calculated as the degree of concentration of pixels detected as a foreign substance within a region of a predetermined size (hereinafter, this region is referred to as a region of interest 32) that includes a pixel detected as a foreign substance (hereinafter, this pixel is referred to as a pixel of interest 31) in a portion of an X-ray radiographic image. In FIG. 6, the pixel of interest 31 is a pixel that exhibits a gray value smaller than a predetermined threshold among pixels included in an image obtained by binarizing the X-ray radiographic image, but is not limited to this. Similar to FIGS. 4A and 4B, the pixel of interest 31 may also be a pixel that exhibits a gray value larger than a predetermined threshold. The region of interest 32 is a region whose size is centered around the pixel of interest 31. In one example, the density is calculated as the density of pixels detected as foreign objects in a region of interest 32 centered on the target pixel 31. In another example, the density is calculated using the gray values ​​of adjacent pixels in a specific region that has been subjected to smoothing filtering.

[0035] Here, suppose that the pixels forming each of the regions R3 and R4 included in the X-ray transmission image P1 shown in Fig. 4(A) are equal to or greater than a first gray level. Also, suppose that the area and density of the pixels forming each of the regions R3 and R4 included in the X-ray transmission image P1 shown in Fig. 4(A) are less than a predetermined threshold. Also, suppose that the pixels forming each of the regions R13 and R14 included in the X-ray transmission image P2 shown in Fig. 4(B) are equal to or greater than a first gray level. Also, suppose that the area and density of the pixels forming the region R13 included in the X-ray transmission image P2 shown in Fig. 4(B) are less than the first threshold, and the area and density of the pixels forming the region R14 included in the X-ray transmission image P2 shown in Fig. 4(B) are equal to or greater than the first threshold.

[0036] In this case, the determination unit 23 determines that at least one region (here, region R14) among the plurality of regions R11 to R14 in the X-ray transmission image P2 is formed by pixels having a first gray value or more and has an area, length, or density equal to or greater than the first threshold (S12: YES). That is, the determination unit 23 determines that a problematic foreign object is contained in the article G (step S13), and ends the series of processes.

[0037] Furthermore, when the judgment unit 23 judges that at least one of the multiple regions R1 to R4 in the X-ray transmission image P1 is not formed with pixels having a first gradation value or greater so as to have an area, length, or density greater than or equal to the first threshold (S12: NO), it transitions to the second stage of judging whether or not there is a foreign object in the article G.

[0038] Specifically, the determination unit 23 determines whether there is no region R among the multiple regions R that is formed by pixels having a first gray value or greater so that its area, length, or density is equal to or greater than the first threshold, and whether there is at least one specific region IR among the multiple regions R that is formed by pixels having a first gray value or greater so that its area, length, or density is less than the first threshold. If the determination unit 23 determines that there is at least one specific region IR among the multiple regions R, it determines whether the article G is normal or abnormal based on the ratio between the length of a first side SS of a circumscribing rectangle CR for at least one of the specific regions IR and the length of a second side LS that is connected to the first side SS and is equal to or greater than the length of the first side SS (step S14). Note that the length of the first side SS may be the same as or shorter than the length of the second side LS.

[0039] The circumscribing rectangle CR here refers to a rectangle that contains the specific region IR, and all four sides of the rectangle are in contact with the outside of the specific region IR. The determination unit 23 forms such a circumscribing rectangle CR for each specific region IR. If the ratio of the length of the second side LS to the length of the first side SS is within a first set range (e.g., a range greater than 1.1 to 1.3) or the ratio of the length of the first side SS to the length of the second side LS is within a second set range (e.g., a range smaller than 0.7 to 0.9) (S14: YES), the determination unit 23 determines that the foreign object corresponding to the specific region IR, such as that shown in FIG. 7B, is an elongated foreign object overall. Hereinafter, the "ratio of the length of the second side LS to the length of the first side SS" and the "value of the ratio of the length of the first side SS to the length of the second side LS" are also referred to as the aspect ratio for convenience. The first and second set ranges of the aspect ratio are configured to be settable via the display operation unit (setting unit) 8.

[0040] In this embodiment, the determination unit 23 identifies two regions, region R3 and region R4, in the X-ray transmission image P1 as specific regions IR because they are formed by pixels with a first gray value or more so that their area, length, or density is less than a first threshold. Here, for example, suppose that the value of the ratio of the length of the first side SS to the length of the second side LS of the circumscribing rectangle CR for region R3 is within a first set range, and the value of the ratio of the length of the first side SS to the length of the second side LS of the circumscribing rectangle CR for region R4 is not within the first set range.

[0041] When the determination unit 23 detects that the article G1 contains a foreign object that is small but elongated overall, such as the foreign object corresponding to the region R3, the determination unit 23 determines that the article G1 contains a problematic foreign object (step S13), and ends the series of processes. In other words, the determination unit 23 determines that such a foreign object that is small but elongated overall is a problematic foreign object.

[0042] If the value of the ratio of the length of the second side (long) to the length of the first side SS is not within a first set range (e.g., a range greater than 1.1 to 1.3) or the value of the ratio of the length of the first side SS to the length of the second side LS is not within a second set range (e.g., a range less than 0.7 to 0.9) (S14: NO), the determination unit 23 determines that the foreign object corresponding to the specific region IR shown in FIG. 7(A) is an overall thick and short foreign object. If the determination unit 23 detects that the object G1 contains only small but overall thick and short foreign objects, such as the foreign object corresponding to region R4, the determination unit 23 determines that there is no problematic foreign object in the object G (step S15) and ends the series of processes. In other words, the determination unit 23 does not determine that such small but overall thick and short foreign objects are problematic foreign objects.

[0043] When displaying the determination result on the display operation unit 8, the determination unit 23 may display the foreign matter determined to be a foreign matter by surrounding it with a frame F, as shown in Figures 4(A) and 4(B). Furthermore, when displaying the determination result on the display operation unit 8, as shown in Figures 4(A) and 4(B), information display units W1-W4, W11-W14 that display the area, length, density or aspect ratio for each of the regions R1-R4, R11-R14 may be provided on the X-ray transmission images P1, P2, or a list of the area, length, density or aspect ratio for each of the regions R1-R4, R11-R14 may be displayed separately from the areas where the X-ray transmission images P1, P2 are displayed.

[0044] In addition to the above information, each information display section W1-W4, W11-W14 may display the maximum, minimum, average, or standard deviation of the area, length, density, or aspect ratio of each region R1-R4, R11-R14. While the above embodiment describes an example in which the information display sections W1-W4, W11-W14 are displayed for all of the regions R1-R4, R11-R14 divided in step S11, it is also possible to display only the information display section corresponding to the specific region IR. Examples of content displayed on the information display section include the area, length, density, or aspect ratio of the specific region IR, and the maximum, minimum, average, or standard deviation of the area, density, or aspect ratio of the corresponding region. In this case, it is easy to check the characteristics of foreign particles smaller than a predetermined size.

[0045] The determination unit 23 transmits the determination result as to whether the item G is normal or not to the output unit 24 and the memory unit 25. The output unit 24 outputs the determination result of the determination unit 23 to at least one of a portion of the X-ray inspection apparatus 1 other than the controller 10 and a device different from the X-ray inspection apparatus 1. This allows at least one of the X-ray inspection apparatus 1 and a device different from the X-ray inspection apparatus 1 (for example, a sorting device arranged downstream of the X-ray inspection apparatus 1) to perform an operation when the item G is defective. Other examples of the device different from the X-ray inspection apparatus 1 include an input conveyor 51, an output conveyor 52, an alarm device, etc.

[0046] The storage unit 25 records signals, data, etc. generated by the controller 10. For example, the storage unit 25 records a detection result signal transmitted from the detection result acquisition unit 21, image data transmitted from the X-ray image generation unit 22, and data related to the determination result transmitted from the determination unit 23.

[0047] The effects of the X-ray inspection apparatus 1 of the above embodiment will be described. According to the X-ray inspection apparatus 1 described above, it is determined that a foreign object of a predetermined size or larger is present in a region R formed by pixels having a first gray value or larger so that the region R has an area, length, or density equal to or greater than a first threshold. Furthermore, the X-ray inspection apparatus 1 configured as described above determines that a foreign object of a smaller size is present in a region R formed by pixels having a first gray value or larger so that the region R has an area, length, or density less than the first threshold. The X-ray inspection apparatus 1 configured as described above distinguishes whether a foreign object of a smaller size is elongated or narrow overall based on the ratio of the first side SS to the second side LS of the circumscribing rectangle CR for the region R containing the foreign object determined to be smaller than the predetermined size. This allows for differentiation between elongated and narrow overall foreign objects and narrow and wide overall foreign objects while maintaining productivity.

[0048] In the X-ray inspection apparatus 1 of the above embodiment, if the ratio of the length of the second side LS to the length of the first side SS is within a first set range, or if the ratio of the length of the first side SS to the length of the second side LS is within a second set range, it is determined that there is an abnormality in the object. With this configuration, when the degree of thinness is at a predetermined level, it can be determined that the foreign object is elongated overall.

[0049] The X-ray inspection device 1 of the above embodiment is equipped with a display operation unit 8 that sets the first set range or the second set range, making it possible to detect objects that contain foreign matter of the degree of thinness that the user wants to remove.

[0050] The above describes an embodiment of one aspect of the present invention, but the one aspect of the present invention is not necessarily limited to the above-described embodiment, and various modifications are possible within the scope that does not deviate from the gist of the present invention.

[0051] (Variation 1) In addition to the method for determining the presence or absence of a foreign object in the X-ray inspection apparatus 1 of the above embodiment, step S21 as shown in FIG. 8 may be included. Step S21 is a step executed by the determination unit 23 when the aspect ratio of the circumscribing rectangle CR for the specific region IR is not within a predetermined range in step S14 (S14: NO), i.e., when a foreign object is determined to have an overall thick and short shape. In step S14, a foreign object smaller than a predetermined size and having an elongated shape in the planar direction of the article G can be detected, but a foreign object having an elongated shape in the thickness direction of the article G is difficult to detect. Therefore, in the X-ray inspection apparatus 1 according to the modified example, step S21 is added to determine whether a foreign object that is determined to be small in planar view in step S12 and not having an overall elongated shape in planar view in step S14 has an elongated shape in the thickness direction of the article G.

[0052] In step S21, the determination unit 23 determines that a foreign object having an elongated shape in the thickness direction of the article G is present in the region R determined in step S14 to have an aspect ratio outside the predetermined range if the region R is formed by pixels having a second gray value higher than the first gray value, so that the area, length, or density is equal to or greater than a second threshold value (hereinafter, also referred to as the "first method"). Alternatively, or in addition to the first method, the determination unit 23 determines that a foreign object having an elongated shape in the thickness direction of the article G is present in the region R determined in step S14 to have an aspect ratio outside the predetermined range if the brightness change value in the region R is equal to or greater than a predetermined threshold value (hereinafter, also referred to as the "second method"). At least one of the second gray value and the second threshold value described above can be adjusted as appropriate depending on the type of article G, the type of foreign object that may be contained in the article G, the type of image processing algorithm, etc. This allows the presence or absence of a foreign object in the article G to be determined appropriately depending on the type of article G, etc.

[0053] The determination method in step S21 will be described with reference to FIGS. 9(A) and 9(B). The X-ray transmission image P3 shown in FIG. 9(A) is divided into regions R21 to R23, and the X-ray transmission image P4 shown in FIG. 9(B) is divided into regions R31 to R33. In FIG. 9(A), the grayscale value of the pixels included in region R23 is the highest, and the grayscale values ​​of at least some of the pixels included in region R23 are equal to or greater than a first grayscale value and equal to or greater than a second grayscale value. In FIG. 9(B), the luminance of some pixels included in region R33 is the highest, and is equal to or greater than the first grayscale value and less than a second grayscale value. Note that the difference in luminance between adjacent pixels included in region R33 is less than a predetermined threshold.

[0054] Here, the first method will be described. When the detection result acquisition unit 21 acquires the X-ray transmission image P3 and the X-ray transmission image P4, the region R23 in the X-ray transmission image P3 and the region R33 in the X-ray transmission image P4 are formed by pixels having a first gray value or more so that their area, length, or density is less than the first threshold, so the determination unit 23 identifies the region R23 and the region R33 as the specific region IR (step S12). Here, it is assumed that the determination unit 23 determines that the aspect ratio of the circumscribing rectangle CR for the specific region IR is not within a predetermined range (S14: NO).

[0055] Since the grayscale values ​​of at least some of the pixels constituting region R23 of X-ray transmission image P3 are equal to or greater than the first grayscale value and equal to or greater than the second grayscale value (S21: YES), the determination unit 23 determines that region R23R contains a foreign object that is elongated overall in the thickness direction of article G2 (step S13).On the other hand, since the grayscale values ​​of at least some of the pixels constituting region R33 of X-ray transmission image P4 are equal to or greater than the first grayscale value and less than the second grayscale value (S21: NO), the determination unit 23 determines that region R33R does not contain a foreign object that is elongated overall in the thickness direction of article G2, and therefore does not contain a problematic foreign object (step S15).

[0056] The X-ray inspection device 1 according to the first modification can detect foreign objects that are not problematic in size when viewed in an X-ray transmission image and that are not elongated in shape in plan view, but that may actually be problematic (for example, foreign objects that are elongated in the thickness direction of the article G) as problematic foreign objects. In other words, problematic foreign objects can be detected with high accuracy regardless of the orientation of the foreign object within the article G.

[0057] In the above embodiment and modified example, a foreign object shown in an X-ray transmission image appears dark, but this is not limited thereto. For example, as shown in FIGS. 10(A) to 10(D), a foreign object shown in an X-ray transmission image may appear bright. Each of the X-ray transmission images P11 to P14 shown in FIGS. 10(A) to 10(D) is a negative-positive inversion image of the X-ray transmission images P1 to P4. Therefore, in FIGS. 10(A) to 10(D), the pixels indicating more problematic foreign objects have smaller gray values. When the X-ray transmission images P11 to P14 are used, in step S12, if the length, area, or density of pixels having a first gray value or less in at least one of the multiple regions is equal to or greater than a first threshold, the determination unit 23 determines that the article G is abnormal. In addition, if the length, area or density of pixels below the first threshold in all of the multiple regions is less than the first threshold, the judgment unit 23 judges whether the item G is normal or abnormal based on the brightness change value and / or pixels below a second gray value that is smaller than the first gray value in at least one of the multiple regions.

[0058] In the above embodiment and modified example, an example has been described in which an X-ray transmission image P1 to P4 is divided into a plurality of regions R, and then a region formed by pixels having a first gray value or more so as to have an area, length, or density equal to or greater than a first threshold is identified from among the plurality of regions R, or a region formed by pixels having a first gray value or more so as to have an area, length, or density less than the first threshold is identified. However, the present invention is not limited to this. For example, it is also possible to identify a region formed by pixels having a first gray value or more so as to have an area, length, or density equal to or greater than the first threshold from within a region inside an article G, or to identify a region formed by pixels having a first gray value or more so as to have an area, length, or density less than the first threshold.

[0059] In the above embodiment, the X-ray inspection apparatus includes a controller that performs image processing, but this is not limited to this. For example, the X-ray inspection apparatus does not necessarily include functions such as the image processing function in the controller, the function of determining whether or not a foreign object is present in an object, and the function of displaying the X-ray inspection results. Instead, these functions may be implemented in a control device that can communicate with the X-ray inspection apparatus via wire or wired communication. In this case, an X-ray inspection system can be realized that includes the X-ray inspection apparatus and the control device to which the inspection results of the X-ray inspection apparatus are input. This X-ray inspection system also achieves the same effects as the above embodiment. In addition, the configuration of the controller included in the X-ray inspection apparatus can be simplified. Furthermore, the user can check the inspection results, etc., even when the user is located away from the X-ray inspection apparatus. The control device may be, but is not limited to, a laptop PC, a tablet, or the like.

[0060] Examples of gray values ​​described in this embodiment and the modified examples include luminance values, brightness, contrast, etc. For example, in the case of luminance values, darker pixels may exhibit lower values ​​and brighter pixels may exhibit higher values, or darker pixels may exhibit higher values ​​and brighter pixels may exhibit lower values. [Explanation of symbols]

[0061] 1...X-ray inspection device, 2...device main body, 4...shielding box, 5...transport unit, 6...X-ray irradiation unit, 7...X-ray detection unit, 8...display operation unit (display unit), 10...controller, 21...detection result acquisition unit, 22...X-ray image generation unit, 23...judgment unit, 24...output unit, 25...memory unit, 51...input conveyor, 52...output conveyor

Claims

1. a conveying unit that conveys the article; an X-ray source that irradiates the object being transported to the transport section with X-rays; an X-ray detection unit that detects the X-rays; an X-ray image generating unit that generates an X-ray transmission image based on the X-ray detection result by the X-ray detection unit; a determination unit that determines whether the article is normal or abnormal based on the X-ray transmission image, The determination unit Dividing the X-ray transmission image into a plurality of regions based on the gray level difference between adjacent pixels; If at least one of the plurality of regions is formed by pixels having a predetermined gray value or more and has an area, length, or density that is equal to or greater than a predetermined threshold, the article is determined to be abnormal; If there is no area among the plurality of areas that is formed by pixels having a predetermined gradation value or greater so that the area, length, or density is greater than a predetermined threshold, and there is at least one specific area among the plurality of areas that is formed by pixels having a predetermined gradation value or greater so that the area, length, or density is less than the predetermined threshold, an X-ray inspection device determines whether the item is normal or abnormal based on the length of a first side of a circumscribing rectangle for at least one of the specific areas and the length of a second side that is connected to the first side and is greater than or equal to the length of the first side.

2. 2. The X-ray inspection device according to claim 1, wherein the object is determined to have an abnormality if the ratio of the length of the second side to the length of the first side is within a first set range, or if the ratio of the length of the first side to the length of the second side is within a second set range.

3. The X-ray inspection apparatus according to claim 2 , further comprising a setting unit that sets the first set range or the second set range.

4. a display unit that displays the test result by the determination unit, The X-ray inspection device according to any one of claims 1 to 3, wherein, when the specific region is present, the display unit displays the area, the length, the density, the ratio of the length of the second side to the length of the first side, or the ratio of the length of the first side to the length of the second side of the corresponding region.

5. 5. The X-ray inspection apparatus according to claim 4, wherein, when the specific region is present, the display unit displays the area, the length, the density, the ratio of the length of the second side to the length of the first side, or the maximum value, minimum value, average value, or standard deviation of the corresponding region.

Images