X-ray inspection equipment

Abstract

The object of the present invention is to provide an X-ray inspection apparatus that automatically selects X-ray transmission images to be saved. [Solution] The X-ray inspection apparatus 10 comprises a conveyor 12, an X-ray irradiator 13, an X-ray line sensor 14, a foreign object inspection unit 21b, an HDD 25, and a controller 20. The foreign object inspection unit 21b performs a predetermined processing on the X-ray transmission image of the item G generated based on the detection result of the X-ray line sensor 14 to create a judgment image. Furthermore, the foreign object inspection unit 21b determines whether the item G is good or bad by comparing the pixel value indicated by each pixel of the judgment image with a preset threshold Th. The controller 20 decides whether or not to store the X-ray transmission image corresponding to the judgment image in the HDD 25 based on the difference between the pixel value indicated by each pixel of the judgment image and the threshold Th.

Description

Technical Field

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[0003]

[0001] The present invention relates to an inspection apparatus that determines the quality of an inspection object based on a transmission image of X-rays irradiated on the inspection object.

Background Art

[0002] As an apparatus for inspecting the presence or absence of defects such as foreign matter混入 in an article, an X-ray inspection apparatus is widely used. For example, the inspection apparatus disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2019-12011) includes correction means for correcting an X-ray transmission image in order to perform more accurate inspection. Therefore, the corrected image can be confirmed in real time.

[0003] In the above X-ray inspection apparatus, the processed result of the corrected image can be confirmed only for the latest X-ray transmission image, and it is not known what result will be obtained when the same correction is performed on a past X-ray transmission image.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, in order to correct a past X-ray transmission image and be able to inspect how much the inspection performance changes, it is necessary to save the X-ray inspection transmission image. However, saving all X-ray transmission images is against reason.

[0005] An object of the present invention is to provide an X-ray inspection apparatus that automatically selects X-ray transmission images to be saved.

Means for Solving the Problems

[0006] The X-ray inspection apparatus according to the first aspect comprises a transport unit, an X-ray irradiation unit, an X-ray detection unit, an inspection unit, a storage unit, and a control unit. The transport unit transports the articles. The X-ray irradiation unit irradiates the transported articles with X-rays. The X-ray detection unit detects the X-rays that have passed through the articles. The inspection unit creates a judgment image by performing predetermined processing on the X-ray transmission image of the articles generated based on the detection results of the X-ray detection unit. Furthermore, the inspection unit determines whether the articles are good or bad by comparing the pixel value indicated by each pixel of the judgment image with a preset threshold. The storage unit stores the X-ray transmission images. The control unit decides whether or not to store the X-ray transmission image corresponding to the judgment image in the storage unit based on the comparison evaluation result between the pixel value indicated by each pixel of the judgment image and the threshold.

[0007] This X-ray inspection device does not retain all X-ray transmission images, but rather selects which X-ray transmission images to save based on a comparative evaluation result between the pixel value shown by each pixel in the evaluation image and the threshold. This reduces the burden of selection on the operator and saves storage capacity compared to retaining all X-ray transmission images. Here, comparative evaluation refers to evaluating the magnitude of the deviation from the threshold, such as the "difference between the pixel value and the threshold" or the "ratio between the pixel value and the threshold."

[0008] The X-ray inspection apparatus relating to the second viewpoint is the same as the X-ray inspection apparatus relating to the first viewpoint, wherein when the control unit determines that the difference between the maximum value of the pixel indicated by each pixel of the determination image and the threshold is within a predetermined range, it stores the X-ray transmission image corresponding to the determination image in the storage unit.

[0009] In this X-ray inspection system, if X-ray transmission images of clearly good or clearly defective products are saved, re-inspecting them after correction (sensitivity adjustment) will have little impact on inspection performance. Therefore, by saving images where the difference from the threshold is within a predetermined range, it becomes easier to understand the impact of re-inspection on inspection performance.

[0010] The X-ray inspection apparatus relating to the third viewpoint is the same as the X-ray inspection apparatus relating to the first viewpoint, and when the control unit determines that the difference between the maximum value of the pixel indicated by each pixel of the judgment image and the threshold is outside a predetermined range, the X-ray transmission image corresponding to the judgment image is not stored in the storage unit.

[0011] The X-ray inspection apparatus relating to the fourth viewpoint is an X-ray inspection apparatus relating to any one of the first, second, or third viewpoints, wherein the judgment image is an image generated by performing arbitrary filtering on the X-ray transmission image.

[0012] The X-ray inspection apparatus relating to the fifth viewpoint is an X-ray inspection apparatus relating to one of the first, second, or fourth viewpoints, wherein the inspection unit creates a judgment image from past X-ray transmission images stored in the storage unit. When the control unit determines that the difference between the maximum value of the pixel indicated by each pixel of the judgment image and the threshold is outside a predetermined range, it deletes the X-ray transmission image corresponding to the judgment image from the storage unit.

[0013] In this X-ray inspection system, if X-ray transmission images of clearly good or clearly defective products are saved, re-inspecting them after correction (sensitivity adjustment) will not significantly affect inspection performance. Therefore, by deleting images where the difference from the threshold is outside a predetermined range and saving those where the difference from the threshold is within a predetermined range, it becomes easier to understand the impact of re-inspection on inspection performance.

[0014] The X-ray inspection apparatus relating to the sixth viewpoint is an X-ray inspection apparatus relating to either the first viewpoint or the fifth viewpoint, and when the number of X-ray transmission images stored in the storage unit exceeds a predetermined number, the control unit deletes the X-ray transmission images from the storage unit in order of the largest difference between the maximum value of the pixel indicated by each pixel of the judgment image corresponding to each stored X-ray transmission image and the threshold.

[0015] This X-ray inspection device can save storage capacity while preserving past X-ray transmission images necessary for adjusting inspection performance.

[0016] The X-ray inspection apparatus relating to the seventh viewpoint is an X-ray inspection apparatus relating to either the first viewpoint or the sixth viewpoint, and when the threshold is changed, the inspection unit creates a determination image for past X-ray transmission images stored in the storage unit. When the control unit determines that the difference between the maximum pixel value shown by each pixel of the determination image and the changed threshold is outside a predetermined range, it deletes the X-ray transmission image corresponding to the determination image from the storage unit.

[0017] In this X-ray inspection device, when the threshold is changed, some X-ray transmission images inspected with the previous threshold will not be useful for adjusting the inspection performance. Therefore, the inspection performance is optimized by excluding those where the difference between the new threshold and the old threshold falls outside a predetermined range.

[0018] The X-ray inspection apparatus of the eighth perspective is an X-ray inspection apparatus relating to one of the first to seventh perspectives, wherein the inspection unit creates a judgment image from past X-ray transmission images stored in the memory unit and performs a re-inspection without transporting the item currently being inspected.

[0019] The X-ray inspection apparatus according to the ninth perspective is the same as the X-ray inspection apparatus according to the first perspective, wherein the control unit stores only the X-ray transmission images corresponding to the items that the inspection unit has determined to be defective in the storage unit.

[0020] The X-ray inspection apparatus of the 10th perspective is an X-ray inspection apparatus of either the 1st perspective or the 9th perspective, in which the inspection unit performs different processing on the X-ray transmission image to create multiple judgment images. Furthermore, the inspection unit determines the quality of the item by comparing the pixel value shown by each pixel in each judgment image with a threshold value set for each judgment image.

[0021] The X-ray inspection apparatus relating to the 11th viewpoint is an X-ray inspection apparatus relating to any one of the 10th viewpoints from the 1st viewpoint, and further includes a display unit that displays the results of the pass / fail judgment by the inspection unit. The display unit displays a predetermined number of X-ray transmission images from among the X-ray transmission images stored in the storage unit.

[0022] In this X-ray inspection apparatus, an operator can view past X-ray transmission images from above, making it easy to extract those with doubts about the pass / fail judgment.

[0023] The X-ray inspection apparatus according to the 12th aspect is the X-ray inspection apparatus according to the 11th aspect, wherein the display unit performs batch display in a state not produced by the X-ray inspection apparatus. In this X-ray inspection apparatus, by performing batch display before the start of production or when production is in progress, the work of changing inspection conditions by the operator can be assisted.

[0024] The X-ray inspection apparatus according to the 13th aspect is the X-ray inspection apparatus according to the 11th or 12th aspect, wherein the display unit enlarges and displays one selected X-ray transmission image among the batch-displayed X-ray transmission images.

[0025] In this X-ray inspection apparatus, an operator can determine the appropriateness of the pass / fail judgment by enlarging and displaying those with doubts about the pass / fail judgment.

Advantages of the Invention

[0026] In the X-ray inspection apparatus according to the present invention, instead of leaving all X-ray transmission images, the X-ray transmission images to be saved are selected based on the difference between the pixel value indicated by each pixel of the determination image and the threshold value. Therefore, the burden of selection is not imposed on the operator, and the capacity of the storage unit is saved compared to the case of leaving all X-ray transmission images.

Brief Description of the Drawings

[0027] [Figure 1] It is an external perspective view of an X-ray inspection apparatus according to an embodiment of the present invention. [Figure 2] It is a front and rear process configuration diagram of the X-ray inspection apparatus. [Figure 3] It is an internal configuration diagram of the shield box of the X-ray inspection apparatus. [Figure 4] It is a schematic diagram showing the principle of X-ray inspection. [Figure 5] It is a block configuration diagram of the controller. [Figure 6]This is a front view of a screen displaying multiple detection units and an X-ray transmission image of chicken breast with marks placed in the areas identified as foreign objects by these units. [Figure 7] This is a flowchart of the program for saving X-ray transmission images during X-ray inspection. [Figure 8] This is a flowchart of the operation when adjusting the inspection performance of the foreign object inspection department. [Figure 9] This is a front view of a monitor screen displaying an X-ray transmission image of chicken breast meat that was determined to contain foreign matter. [Figure 10] Figure 9 shows an enlarged view of image P6. [Figure 11] This is the result of a re-examination performed by the seventh determination unit J7 on the past X-ray transmission image corresponding to image P6, after changing the threshold to 68 in the seventh determination unit J7. [Figure 12] This is a partial front view of the screen showing the sensitivity filter and density filter of each judgment unit side by side. [Modes for carrying out the invention]

[0028] (1) Overall configuration of the X-ray inspection device 10 Figure 1 is an external perspective view of an X-ray inspection apparatus 10 according to one embodiment of the present invention. Figure 2 is a diagram showing the process configuration before and after the X-ray inspection apparatus 10. In Figures 1 and 2, the X-ray inspection apparatus 10 is incorporated into a production line for goods G such as food products to perform quality inspections of the goods G. The X-ray inspection apparatus 10 determines the quality of the goods G by irradiating them with X-rays as they are continuously transported.

[0029] The item G to be inspected is transported to the X-ray inspection device 10 by the upstream conveyor 60. The item G is classified as good or defective in the X-ray inspection device 10. The inspection results from the X-ray inspection device 10 are sent to the sorting mechanism 70 located downstream of the X-ray inspection device 10.

[0030] The sorting mechanism 70 sends items G determined to be good products by the X-ray inspection device 10 to the conveyor 80 that discharges good products, and sorts items G determined to be defective products by the X-ray inspection device 10 into the defective product discharge directions 90 and 91.

[0031] (2) Detailed configuration Figure 3 is an internal configuration diagram of the shield box 11 of the X-ray inspection apparatus 10. In Figures 1 and 3, the X-ray inspection apparatus 10 consists of a shield box 11, a conveyor 12, an X-ray irradiator 13, an X-ray line sensor 14, a monitor 30 with touch panel functionality, and a controller 20 (see Figure 5).

[0032] (2-1) Shield box 11 Openings 11a are formed on both sides of the shield box 11 to allow articles G to be moved in and out of the shield box 11. The openings 11a are covered by shielding curtains 11b to prevent X-ray leakage to the outside of the shield box 11. The shielding curtains 11b are molded from lead-containing rubber and are pushed aside by the articles G as they pass through the openings 11a.

[0033] The shield box 11 houses the conveyor 12, the X-ray irradiator 13, the X-ray line sensor 14, and the controller 20. The upper front of the shield box 11 also features a monitor 30, a key slot, and a power switch.

[0034] (2-2) Conveyor 12 The conveyor 12 transports the articles G inside the shield box 11, and as shown in Figure 1, it is positioned to pass through the openings 11a formed on both sides of the shield box 11. The conveyor 12 transports the articles G placed on the belt by rotating an endless belt with drive rollers driven by a conveyor motor 12a (see Figure 5).

[0035] The conveying speed of the conveyor 12 is precisely controlled by the inverter control of the conveyor motor 12a via the controller 20 so that it matches the set speed entered by the operator. The conveyor motor 12a is also equipped with an encoder 12b (see Figure 5) that detects the conveying speed of the conveyor 12 and sends the information to the controller 20.

[0036] (2-3)X-ray irradiator 13 As shown in Figure 3, the X-ray irradiator 13 is positioned above the conveyor belt 12 and irradiates X-rays in a fan-shaped irradiation range Rx toward the X-ray line sensor 14 below.

[0037] (2-4) X-ray line sensor 14 Figure 4 is a schematic diagram illustrating the principle of X-ray inspection. In Figure 4, the X-ray line sensor 14 is positioned below the conveyor 12 and mainly consists of a large number of pixel sensors 14a. These pixel sensors 14a are arranged horizontally in a straight line perpendicular to the direction of transport by the conveyor 12. Each pixel sensor 14a detects X-rays that have passed through the object G or the conveyor 12 and outputs an X-ray transmission signal. The X-ray transmission signal indicates the brightness of the X-rays.

[0038] (2-5) Monitor 30 Monitor 30 is a full-dot liquid crystal display that shows a screen prompting the operator to input the necessary judgment unit, filter, and parameter threshold values ​​required during inspection. Monitor 30 also has a touch panel function to accept input from the operator.

[0039] (2-6) Controller 20 Figure 5 is a block diagram of the controller 20. In Figure 5, the controller 20 is equipped with a CPU (Central Processing Unit) 21, ROM (Read-Only Memory) 22, RAM (Random Access Memory) 23, HDD (Hard Disk Drive) 25, and a drive 24 for inserting storage media.

[0040] The CPU 21 executes various programs stored in the ROM 22 and HDD 25. The HDD 25 also stores and saves inspection results. The conditions and items required for inspection can be set and changed by the operator using the touch panel function of the monitor 30. The operator can configure the system to save this data not only on the HDD 25 but also on the storage media inserted in the drive 24.

[0041] The controller 20 is also connected to the conveyor motor 12a, encoder 12b, X-ray irradiator 13, X-ray line sensor 14, and photoelectric sensor 15. The photoelectric sensor 15 is a synchronization sensor for detecting the timing when the object G to be inspected passes through the fan-shaped X-ray irradiation range Rx (see Figure 3).

[0042] (3) Configuration of CPU21 The HDD 25 of the controller 20 stores inspection programs, including an image generation module and a foreign object inspection module. The CPU 21 of the controller 20 then reads and executes these program modules, thereby operating as the image generation unit 21a and the foreign object inspection unit 21b.

[0043] (3-1) Image generation section 21a The image generation unit 21a generates an X-ray transmission image of object G based on the X-ray transmission signal output from the X-ray line sensor 14. The image generation unit 21a acquires X-ray transmission signals output from each pixel sensor 14a of the X-ray line sensor 14 at fine time intervals as object G passes through the fan-shaped X-ray irradiation range Rx (see Figure 3), and generates an X-ray transmission image of object G based on the acquired X-ray transmission signals. The timing of object G passing through the fan-shaped X-ray irradiation range Rx is determined by the signal from the photoelectric sensor 15. The image generation unit 21a generates an X-ray transmission image of object G by concatenating the data on X-ray brightness obtained from each pixel sensor 14a of the X-ray line sensor 14 in a matrix in a time series.

[0044] Furthermore, the image generation unit 21a has an edge processing function that emphasizes spatial changes in brightness in the X-ray transmission image as contours in order to identify contours. In other words, by detecting areas (edges) in the X-ray transmission image where brightness changes sharply, the boundary between object G and other objects (contour of object G) can be detected.

[0045] (3-2) Foreign object inspection department 21b The foreign object inspection unit 21b has multiple determination units that use an X-ray transmission image of the item G to determine whether or not the item G contains foreign objects and to detect foreign objects. Figure 6 is a front view of screen 30a, which displays the multiple determination units and an X-ray transmission image of "chicken breast" with marks placed in the areas determined to contain foreign objects by these units.

[0046] In Figure 6, an X-ray transmission image is displayed in the first region 31 of screen 30a, and multiple determination units are displayed in the second region 32 adjacent to the first region 31. The multiple determination units include the first determination unit J1 to the ninth determination unit J9. Each of the first determination unit J1 to the ninth determination unit J9 uses a different process for determination, or even if the same process is used, the conditions differ. Each determination unit performs, for example, edge processing or binarization processing.

[0047] Each of the first to ninth determination units J1 to J9 performs a predetermined processing on the X-ray transmission image, as set for each determination unit, to create a determination image. Each determination unit compares the pixel value indicated by each pixel in the determination image with a preset threshold.

[0048] Hereinafter, a "sensitivity filter" is defined as a device that creates a judgment image from an X-ray transmission image and allows comparison between the pixel value indicated by each pixel in the judgment image and a pre-set threshold. The sensitivity threshold Th is set by moving the cursor 32b of the sensitivity adjustment bar 32a of each judgment unit in Figure 6 left or right.

[0049] Here, the pixel value is a value that indicates the degree of darkness or opacity. A grayscale image, which represents the shades of black and white, uses 8 bits to represent each pixel and contains only brightness information, without any color information. A pixel value of 0 represents black, and a pixel value of 255 represents white.

[0050] The contrast is reversed between the X-ray transmission image and the diagnostic image. Dark areas in the X-ray transmission image appear bright in the diagnostic image, and the pixel values ​​of those areas are large. Conversely, bright areas in the X-ray transmission image appear dark in the diagnostic image, and the pixel values ​​of those areas are small.

[0051] Therefore, moving the cursor 32b on the sensitivity adjustment bar 32a to the left will decrease the threshold, and setting it too low will increase the sensitivity, making it easier to detect a foreign object even when there is none. Conversely, moving the cursor 32b on the sensitivity adjustment bar 32a to the right will increase the threshold, and setting it too high will decrease the sensitivity, making it easier to detect a foreign object even when there is one, making it easier to detect no foreign object.

[0052] The foreign object inspection unit 21b marks the pixels in the X-ray transmission image that correspond to pixels in the judgment image that show a pixel value greater than the threshold, so that it is clear which judgment unit has identified them as foreign objects.

[0053] (4) Saving X-ray images In this embodiment, X-ray transmission images to be saved are automatically selected in order to correct past X-ray transmission images and to inspect how much the inspection performance has changed. Figure 7 is a flowchart of the X-ray transmission image saving program in the X-ray inspection device 10. This saving program is controlled by the cooperation of the CPU 21, which includes the image generation unit 21a and the foreign object inspection unit 21b, and the HDD 25 as a storage device, so the controller 20, which includes these, is the main operator. The following explanation will be given with reference to Figure 7.

[0054] (Step S1) The controller 20 determines whether or not the threshold Th setting of the sensitivity filter has been changed. If the controller 20 determines that the threshold Th setting has been changed, it proceeds to step S2; if it determines that the threshold Th setting has not been changed, it proceeds to step S3.

[0055] (Step S2) The controller 20 resets the number of X-ray transmission images stored N in the HDD 25 to 0. Since the examination conditions change when the threshold Th of the sensitivity filter is changed, the accumulation of X-ray transmission images stored due to the determination of the determination unit where the threshold Th of the sensitivity filter was changed will start from 0.

[0056] Therefore, past X-ray transmission images saved before the sensitivity filter threshold Th was changed will have less value and will either be retained for re-examination or completely deleted.

[0057] (Step S3) The controller 20 generates an X-ray transmission image of the inspected item via the image generation unit 21a.

[0058] (Step S4) The controller 20 performs a predetermined processing on the X-ray transmission image via the foreign object inspection unit 21b to create a judgment image.

[0059] (Step S5) The controller 20 obtains the pixel value Pi of each pixel in the judgment image.

[0060] (Step S6) The controller 20 extracts the maximum pixel value Pmax, which is the maximum value of the pixel value Pi.

[0061] (Step S7) The controller 20 determines whether Dmax, which is the absolute value of the difference between the maximum pixel value Pmax and the threshold Th, is less than or equal to the set value R. If the controller 20 determines that "Dmax ≤ R", it proceeds to step S8, and if it determines that "Dmax ≤ R", it returns to step S3. In this embodiment, the comparison evaluation of the maximum pixel value Pmax and the threshold Th is performed using the difference between the maximum pixel value Pmax and the threshold Th, but it is not limited to this, and it is also possible to evaluate by the magnitude of the deviation from the threshold Th, such as "the ratio of the maximum pixel value Pmax to the threshold Th".

[0062] (Step S8) The controller 20 saves the X-ray transmission image corresponding to the determination image that has been determined to be "Dmax≦R" to the HDD 25. In other words, it saves images in which the maximum pixel value Pmax is within the range of threshold Th±R. In this embodiment, R=5.

[0063] (Step S9) The controller 20 adds 1 to the number of X-ray transmission images stored N in the HDD 25. This is because an X-ray transmission image was saved in step S8, increasing the number of saved images by 1.

[0064] (Step S10) The controller 20 determines whether the number of X-ray transmission images N to be saved exceeds the allowable number of saved images M. The allowable number of saved images M is set in advance by the operator, taking into account the capacity of the HDD 25. In this embodiment, the allowable number of saved images M is 10 for each determination unit.

[0065] If the controller 20 determines that "N > M", it proceeds to step S11; otherwise, it returns to step S3.

[0066] (Step S11) The controller 20 deletes the X-ray transmission image stored in the HDD 25 that has the largest difference between the maximum pixel value Pmax of the corresponding determination image and the threshold Th. This ensures that the number of past X-ray transmission images stored in the HDD 25 is always maintained at the allowable storage number M for each determination unit.

[0067] (Step S12) The controller 20 determines whether or not there is an inspection termination command. An inspection termination command is issued by an operator when production is stopped, when inspection performance is adjusted, or when there is a problem. If the controller 20 determines that there is an inspection termination command, it terminates the inspection; if it determines that there is no inspection termination command, it returns to step S3.

[0068] (5) Adjustment of examination performance using past X-ray transmission images This section describes the procedure for adjusting the inspection performance of the foreign object inspection unit 21b using past X-ray transmission images. As a prerequisite, it is assumed that 10 X-ray transmission images are stored for each judgment unit on the HDD 25 by the above-mentioned storage program. Here, the stored X-ray transmission images are image data before any processing has been performed. Figure 8 is an operation flowchart for adjusting the inspection performance of the foreign object inspection unit 21b. Here again, the controller 20 is the main operator. The following explanation will refer to Figure 8.

[0069] (Step S21) The controller 20 determines whether or not there is a command to retrieve the X-ray transmission image of a defective product. The command is entered by the operator from the monitor 30. Before or during inspection, the operator can retrieve the X-ray transmission image of "chicken breast" that has already been saved by the storage program and adjust the judgment criteria.

[0070] (Step S22) The controller 20 reads the X-ray transmission image stored in the HDD 25 and displays it on the monitor 30. Figure 9 is a front view of the screen 30a of the monitor 30 displaying the X-ray transmission image of "chicken breast".

[0071] In Figure 9, the 10 images displayed on screen 30a of monitor 30 are X-ray transmission images of "chicken breast" stored on HDD 25. Each X-ray transmission image is numbered from 1 to 10 in chronological order. Each image P1 to P10 has a frame drawn around the area identified as a foreign object.

[0072] (Step S23) The controller 20 determines whether there is an instruction to enlarge any of the 10 X-ray transmission images P1 to P10 displayed on the monitor 30. For example, if the operator finds an image among the images P1 to P10 that is suspected of being misidentified, they press the enlarge button 301 located below that image to enlarge only that screen.

[0073] If the zoom button 301 is pressed, the controller 20 determines that there is an instruction to zoom in and proceeds to step S24. The following explanation assumes that "image P6" has been selected.

[0074] (Step S24) The controller 20 displays a magnified view of the selected X-ray transmission image. Figure 10 is a magnified view of image P6 shown in Figure 9. In Figure 10, the first region 31 on the left side in the front view displays a magnified image of the X-ray transmission image of "chicken breast".

[0075] Furthermore, the second region 32 on the right side in the front view displays the first to ninth determination units J1 to J9, which are among the multiple determination units of the foreign object inspection unit 21b and were used to determine the quality of the "chicken breast meat". The first to ninth determination units J1 to J9 are explained in [(3-2) Foreign object inspection unit 21b] and will not be discussed here.

[0076] (Step S25) The controller 20 determines whether there has been any change in the first determination unit J1 to the ninth determination unit J9. The enclosed area labeled "J7" with a leader line in Figure 10 indicates a part where the seventh determination unit J7 previously determined that "foreign object present".

[0077] The boxes other than the one labeled "J7" clearly enclose areas that can be identified as foreign objects. In contrast, the box labeled "J7" appears to contain no areas that can be identified as foreign objects. The following explanation assumes that the seventh determination unit J7 has made a misjudgment.

[0078] If the operator has doubts about the judgment, they can adjust the inspection performance by changing the threshold Th of the sensitivity filter in the seventh judgment unit J7 and performing a re-examination on past X-ray transmission images stored in the HDD25.

[0079] In the sensitivity filter of the seventh judgment unit J7, the sensitivity threshold Th was set to 18, which was likely a value that frequently resulted in a "foreign object present" judgment. Therefore, the operator adjusted the inspection performance by increasing the threshold Th. The following explanation assumes that the operator changed the threshold Th in the seventh judgment unit J7 from 18 to 68.

[0080] (Step S26) The controller 20 re-examines using the seventh determination unit J7, in which the threshold Th has been changed to 68, and the first to sixth determination units J6, the eighth determination unit J8, and the ninth determination unit J9, which remain unchanged, and displays the results on the monitor 30.

[0081] Figure 11 shows the results of a re-examination performed by the seventh determination unit J7 on the past X-ray transmission image corresponding to image P6 after changing the threshold Th to 68. In Figure 11, the area that was judged as having a "foreign body" in Figure 10 is no longer enclosed, indicating that the misjudgment has been resolved.

[0082] The operator re-examines all past X-ray transmission images stored on the HDD25 to confirm whether the changed threshold Th is appropriate. The foreign object inspection unit 21b can display the re-examination results on the monitor 30 in a unified display as shown in Figure 9.

[0083] Furthermore, if the X-ray transmission image of item G, which was previously determined to contain a foreign object, still shows a false detection of "foreign object" after sensitivity adjustment (after changing the threshold Th), the sensitivity adjustment may be performed again.

[0084] As described above, the controller 20 can check how much the inspection performance changes by changing the threshold Th of the seventh determination unit J7 using past X-ray transmission images without passing the item G through.

[0085] (6) Variant (6-1) First variation In the above embodiment, each determination unit stores in the HDD25 X-ray transmission images in which the difference between the maximum pixel value Pmax in the determination image and the sensitivity threshold Th is determined to be within a predetermined range, so that the inspection performance using past X-ray transmission images can be performed after adjusting the sensitivity of the sensitivity filter.

[0086] On the other hand, in the first modified example, when selecting the X-ray transmission images to be saved, the selection criteria for the X-ray transmission images to be saved are not based solely on the sensitivity filter, but also include the density of the density filter. The density filter detects foreign objects in the judgment image based on the density of pixels whose pixel values ​​exceed the sensitivity threshold Th.

[0087] Figure 12 is a partial front view of the screen showing the sensitivity filter and density filter of each determination unit side by side. In Figure 12, for example, the density of the density filter in the 7th determination unit J7 is set to 3, so if the pixel value in a 3x3 grid of 9 pixels is less than or equal to the threshold of 68, it is determined to be "no foreign object," and if it exceeds the threshold of 68, it is determined to be "foreign object present." As shown in Figure 12, the density can be changed by sliding the cursor 35b of the density adjustment bar 35a left or right.

[0088] For example, if the pixel value exceeds the threshold Th for only one pixel, it is more likely to be noise rather than a foreign object. On the other hand, if the pixel values ​​exceed the threshold Th for 9 pixels in a 3x3 grid, it is more likely to be a foreign object.

[0089] As described above, X-ray transmission images corresponding to judgment images where the difference between the maximum pixel value Pmax and the threshold Th is within a predetermined range and the density requirement is met are stored in HDD25. As a result, the storage of X-ray transmission images of items G that have been identified as foreign objects due to noise is suppressed.

[0090] (6-2) Second variation In the above embodiment, each determination unit stores X-ray transmission images in the HDD25 if it is determined that the difference between the maximum pixel value Pmax and the sensitivity threshold Th in the determination image is within a predetermined range. When the number of stored images exceeds the allowable storage number M, images with the largest difference between the maximum pixel value Pmax and the threshold Th are deleted in order.

[0091] On the other hand, in the second modified example, instead of maintaining the number of saved pixels at the allowable number of saved pixels M for each determination unit, the number of saved pixels for the entire determination unit is maintained at the allowable number of saved pixels M. Therefore, comparisons can be made between determination units, and pixels with the largest difference between the maximum pixel value Pmax and the threshold Th may be deleted first.

[0092] These saving methods are effective when you want to save images where the maximum pixel value Pmax is close to the threshold Th.

[0093] (6-3) Third Variation In the above embodiment, each determination unit is configured to always store M X-ray transmission images in the HDD25 in which the difference between the maximum pixel value Pmax in the determination image and the sensitivity threshold Th is determined to be within a predetermined range. However, it is not specified how many X-ray transmission images of good products with the difference within the predetermined range and how many images of defective products with the difference within the predetermined range are stored.

[0094] On the other hand, in the third modified example, it is possible to select one of the following: (a) only M X-ray transmission images of good products where the above difference is within a predetermined range are saved; (b) only M X-ray transmission images of defective products where the above difference is within a predetermined range are saved; or (c) X-ray transmission images of good and defective products where the above difference is within a predetermined range are saved equally.

[0095] Specifically, in case (a), X-ray transmission images determined to be defective are not saved, and when the number of saved X-ray transmission images determined to be good exceeds the allowable number of saved images M, images with the largest difference between the maximum pixel value Pmax and the threshold Th should be deleted first. This ensures that only X-ray transmission images determined to be good are maintained within the allowable number of saved images M.

[0096] In case (b), X-ray transmission images that are judged to be good are not saved, and when the number of saved X-ray transmission images that are judged to be defective exceeds the allowable number of saved images M, images with the largest difference between the maximum pixel value Pmax and the threshold Th should be deleted first. This allows only X-ray transmission images that are judged to be defective to be maintained at the allowable number of saved images M.

[0097] In case (c), when the number of X-ray transmission images determined to be good (N1) exceeds half of the allowable number of images to be stored (M), the X-ray transmission images determined to be good are deleted in order of the largest difference between the maximum pixel value Pmax and the threshold Th. Furthermore, when the number of X-ray transmission images determined to be defective (N2) exceeds half of the allowable number of images to be stored (M), the X-ray transmission images determined to be defective are deleted in order of the largest difference between the maximum pixel value Pmax and the threshold Th. This ensures that both good and defective X-ray transmission images are stored equally.

[0098] (6-4) In the above embodiment, each determination unit stores X-ray transmission images in the HDD25 if it is determined that the difference between the maximum pixel value Pmax and the sensitivity threshold Th in the determination image is within a predetermined range. When the number of stored images exceeds the allowable storage number M, images with the largest difference between the maximum pixel value Pmax and the threshold Th are deleted in order.

[0099] On the other hand, in Modification 4, when the number of saved images exceeds the allowable number of saved images M, the oldest images are deleted first. This ensures that the number of past X-ray transmission images saved on HDD25 is always maintained at the allowable number of saved images M for each determination unit.

[0100] (7) Characteristics (7-1) The X-ray inspection apparatus 10 comprises a conveyor 12, an X-ray irradiator 13, an X-ray line sensor 14, a foreign object inspection unit 21b, an HDD 25, and a controller 20. The foreign object inspection unit 21b creates a judgment image by performing a predetermined processing on the X-ray transmission image of the article generated based on the detection result of the X-ray line sensor 14. Furthermore, the foreign object inspection unit 21b determines whether the article G is good or bad by comparing the pixel value indicated by each pixel of the judgment image with a preset threshold Th. The controller 20 decides whether or not to store the X-ray transmission image corresponding to the judgment image in the HDD 25 based on the comparative evaluation result of the pixel value indicated by each pixel of the judgment image and the threshold Th. In this embodiment, the comparative evaluation of the maximum pixel value Pmax and the threshold Th is performed by evaluating the difference between the maximum pixel value Pmax and the threshold Th. However, it is not limited to this, and it is also acceptable to evaluate by the magnitude of the deviation from the threshold Th, for example, "the ratio of the maximum pixel value Pmax to the threshold Th". The X-ray inspection device 10 does not retain all X-ray transmission images, but rather selects which X-ray transmission images to save based on the difference between the pixel value indicated by each pixel in the judgment image and the threshold Th. Therefore, it does not place a burden on the operator to select images, and it saves storage capacity compared to the case where all X-ray transmission images are retained.

[0101] (7-2) When the controller 20 determines that the difference between the maximum pixel value Pmax, which is the maximum pixel value shown by each pixel of the judgment image, and the threshold Th is within a predetermined range, it stores the X-ray transmission image corresponding to the judgment image in the HDD 25. In the X-ray inspection device 10, if X-ray transmission images of items that are clearly good or clearly defective are saved, the impact on inspection performance is unlikely to be apparent even if they are re-inspected after correction (sensitivity adjustment). Therefore, by saving images where the difference with the threshold Th is within a predetermined range, it becomes easier to grasp the impact on inspection performance due to re-inspection.

[0102] (7-3) When the controller 20 determines that the difference between the maximum pixel value Pmax, which is the maximum pixel value shown by each pixel of the judgment image, and the threshold Th is outside a predetermined range, the controller 20 does not store the X-ray transmission image corresponding to the judgment image in the HDD 25.

[0103] (7-4) The image used for determination is an image generated by processing the X-ray transmission image with a sensitivity filter, or by processing it with both a sensitivity filter and a density filter.

[0104] (7-5) When the number of X-ray transmission images stored in the HDD 25 exceeds the allowable storage number M, the controller 20 deletes the X-ray transmission images from the HDD 25 in order of the largest difference between the maximum pixel value Pmax of the judgment image corresponding to each stored X-ray transmission image and the threshold Th. The X-ray inspection device 10 can save the capacity of the HDD 25 while saving past X-ray transmission images necessary for adjusting the inspection performance.

[0105] (7-6) The controller 20 stores in the HDD 25 only the X-ray transmission images corresponding to the items that the foreign object inspection unit 21b has determined to be defective, or only the X-ray transmission images corresponding to the items that the foreign object inspection unit 21b has determined to be good, or an equal number of X-ray transmission images corresponding to both defective and good items.

[0106] (7-7) Each of the first to ninth determination units J1 to J9 of the foreign object inspection unit 21b performs different processing on the X-ray transmission image to create multiple determination images, and determines whether an item is good or bad by comparing the pixel value shown by each pixel of each determination image with a threshold Th set for each determination image.

[0107] (7-8) The X-ray inspection device 10 is further equipped with a monitor 30 that displays the results of the pass / fail judgment by the foreign object inspection unit 21b. The monitor 30 can display a predetermined number of X-ray transmission images from the X-ray transmission images stored in the HDD 25 all at once. In the X-ray inspection device 10, the operator can get an overview of past X-ray transmission images and easily extract those for which there are doubts about the pass / fail judgment.

[0108] (7-9) The monitor 30 displays a magnified view of one selected X-ray transmission image from the X-ray transmission images displayed together. In the X-ray inspection device 10, the operator can determine whether the pass / fail judgment is appropriate by magnifying the image in which there is doubt about the pass / fail judgment.

[0109] (8) Other embodiments (8-1) The foreign object inspection unit 21b creates a judgment image from past X-ray transmission images stored in the HDD 25. When the controller 20 determines that the difference between the maximum pixel value Pmax, which is the maximum pixel value shown by each pixel of the judgment image, and the threshold Th is outside a predetermined range, it deletes the X-ray transmission image corresponding to the judgment image from the HDD 25. In the X-ray inspection device 10, if X-ray transmission images of items that are clearly good or clearly defective are saved, the impact on inspection performance is unlikely to be apparent even if they are re-inspected after correction (sensitivity adjustment). Therefore, by deleting those whose difference with the threshold Th is outside a predetermined range and saving those whose difference with the threshold Th is within a predetermined range, it becomes easier to grasp the impact on inspection performance due to re-inspection.

[0110] (8-2) When the threshold Th is changed, the foreign object inspection unit 21b creates a judgment image from past X-ray transmission images stored in the HDD 25. When the controller 20 determines that the difference between the maximum pixel value Pmax, which is the maximum pixel value indicated by each pixel of the judgment image, and the changed threshold Th is outside a predetermined range, it deletes the X-ray transmission image corresponding to the judgment image from the HDD 25. In the X-ray inspection device 10, when the threshold Th is changed, some X-ray transmission images inspected with the threshold Th before the change are included that are not useful for adjusting the inspection performance. Therefore, the inspection performance is optimized by excluding those whose difference with the changed threshold Th is outside a predetermined range.

[0111] (8-3) When the foreign object inspection unit 21b creates a judgment image from past X-ray transmission images stored in the HDD 25 and performs a re-inspection, the inspection may be performed without transporting the item currently being inspected.

[0112] (8-4) The monitor 30 may be configured to display past X-ray transmission images in a batch when the X-ray inspection device 10 is not in production. Displaying the images in a batch on the monitor 30 before production starts or when production is in a pause can assist the operator in changing inspection conditions.

[0113] (8-5) In addition to sensitivity filters and density filters, filters that use AI to detect foreign objects may also be employed.

[0114] (9) Others In the above embodiment, the CPU 21 performs X-ray inspection of foreign objects contained in the article G. However, it may also perform X-ray inspection of defective products due to cracks or chips in the article G, or due to a shortage in the quantity of individual parts in an article composed of multiple individual parts. In this case, the controller 20 stores the shape of a reference individual part and determines cracks or chips by comparing it with the shape recognized as an individual part in the obtained image. The controller 20 also stores the area of ​​an individual part and determines the quantity by dividing the area recognized as an article by the area of ​​the individual part. [Explanation of Symbols]

[0115] 10 X-ray inspection equipment 12. Conveyor (transport section) 13 X-ray irradiator (X-ray irradiator) 14. X-ray line sensor (X-ray detection unit) 21b Foreign Object Inspection Department (Inspection Department) 25 HDD (storage unit) 30 Monitor (Display Unit) J1-J9 Judging Section 1-9 (Multiple Judging Sections) G Goods Th threshold [Prior art documents] [Patent Documents]

[0116] [Patent Document 1] Japanese Patent Publication No. 2019-12011

Claims

1. A conveying unit for transporting goods, An X-ray irradiation unit that irradiates the transported article with X-rays, An X-ray detection unit for detecting the X-rays that have passed through the aforementioned article, An inspection unit performs a predetermined processing on the X-ray transmission image of the article generated based on the detection results of the X-ray detection unit to create a judgment image, and performs an inspection to determine whether the article is good or bad by comparing the pixel value indicated by each pixel of the judgment image with a preset threshold. A storage unit for storing the aforementioned X-ray transmission image, A control unit that determines whether or not to store the X-ray transmission image corresponding to the determination image in the storage unit, based on the comparison evaluation result between the pixel value indicated by each pixel of the determination image and the threshold value, Equipped with, X-ray inspection equipment.

2. When the control unit determines that the difference between the maximum pixel value shown by each pixel of the determination image and the threshold is within a predetermined range, it stores the X-ray transmission image corresponding to the determination image in the storage unit. The X-ray inspection apparatus according to claim 1.

3. When the control unit determines that the difference between the maximum pixel value indicated by each pixel of the determination image and the threshold is outside a predetermined range, it does not store the X-ray transmission image corresponding to the determination image in the storage unit. The X-ray inspection apparatus according to claim 1.

4. The aforementioned determination image is an image generated by applying an arbitrary filter to the X-ray transmission image. An X-ray inspection apparatus according to any one of claims 1 to 3.

5. The inspection unit creates the determination image from the past X-ray transmission images stored in the memory unit. When the control unit determines that the difference between the maximum pixel value indicated by each pixel of the determination image and the threshold is outside a predetermined range, it deletes the X-ray transmission image corresponding to the determination image from the storage unit. An X-ray inspection apparatus according to any one of claims 1 to 3.

6. When the number of X-ray transmission images stored in the storage unit exceeds a predetermined number, the control unit deletes the X-ray transmission images from the storage unit in order of the largest difference between the maximum pixel value shown by each pixel of the determination image corresponding to each stored X-ray transmission image and the threshold value. An X-ray inspection apparatus according to any one of claims 1 to 3.

7. When the threshold is changed, the inspection unit creates the determination image for past X-ray transmission images stored in the storage unit. When the control unit determines that the difference between the maximum pixel value indicated by each pixel of the determination image and the modified threshold is outside a predetermined range, it deletes the X-ray transmission image corresponding to the determination image from the storage unit. An X-ray inspection apparatus according to any one of claims 1 to 3.

8. When the inspection unit creates the judgment image from the past X-ray transmission images stored in the memory unit and performs the inspection again, the inspection is performed without transporting the item that is currently being inspected. An X-ray inspection apparatus according to any one of claims 1 to 3.

9. The control unit stores in the storage unit only the X-ray transmission images corresponding to the articles that the inspection unit has determined to be defective. The X-ray inspection apparatus according to claim 1.

10. The inspection unit creates multiple judgment images by performing different processing on the X-ray transmission image, and determines the quality of the article by comparing the pixel value shown by each pixel in each judgment image with a threshold value set for each judgment image. An X-ray inspection apparatus according to any one of claims 1 to 3.

11. The system further includes a display unit that displays the pass / fail judgment result from the inspection unit, The display unit displays a predetermined number of the X-ray transmission images stored in the storage unit all at once. An X-ray inspection apparatus according to any one of claims 1 to 3.

12. The display unit performs the batch display when the product is not being manufactured by the X-ray inspection device. The X-ray inspection apparatus according to claim 11.

13. The display unit displays an enlarged view of one of the selected X-ray transmission images from the X-ray transmission images displayed together. The X-ray inspection apparatus according to claim 11 or claim 12.

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