JPWO2017159851A1 - Optical inspection device - Google Patents

Abstract

The optical inspection device includes a light irradiation unit that irradiates light to the article, a light detection unit that detects light transmitted through the article, an image generation unit that generates a light transmission image of the article based on the light transmitted through the article, The quality of the article based on at least two images of the light transmission image and the emphasized image, and an image conversion unit that converts the light transmission image so as to emphasize a part belonging to the specific density range in the light transmission image and generates the enhanced image Or an inspection unit that inspects the quality of an article based on at least two emphasized images that are images converted by an image conversion unit and that belong to different density ranges. .

Description

  One embodiment of the present disclosure relates to an optical inspection device that inspects an article using light.

  In the conveyance line of articles that contain and ship contents such as food in packaging materials such as film packaging materials, the contents (for example, biting of the contents into the sealing portion (sealing portion) of the packaging material) In order to prevent the shipment of the article in which the contents in the packaging material are damaged, foreign matter is mixed in the packaging material, etc., it is necessary to inspect the condition of the article. As an apparatus for inspecting the state of such an article, for example, in Patent Document 1, it is determined whether or not the seal portion is bitten in the packaging material, and it is determined that the contents are bitten in the seal portion. A near-infrared inspection apparatus that excludes an article as a defective product from a production line is disclosed.

Japanese Patent Laying-Open No. 2015-232461

  In the conventional near-infrared inspection apparatus, for example, a region of a horizontal seal portion, a region of a vertical seal portion (so-called back pasting portion) extending in a direction intersecting the horizontal seal portion, and a horizontal seal portion and a vertical seal portion The presence / absence of biting is determined by changing the inspection threshold for each region such as the region of the overlapping portion. However, when there are unevenness differences in the entire article to be inspected, the entire article may not be accurately inspected.

  Then, one form of this indication aims at providing the optical inspection device which can inspect the whole article accurately.

  An optical inspection device according to an embodiment of the present disclosure includes a light irradiation unit that irradiates light to an article, a light detection unit that detects light transmitted through the article, and a light transmission image of the article based on light transmitted through the article. An image generating unit for generating, an image converting unit for generating an emphasized image by converting the light transmissive image so that a portion belonging to the specific density range in the light transmissive image is emphasized, and at least two of the light transmissive image and the enhanced image Inspect the quality of the article based on the image, or inspect the quality of the article based on at least two emphasized images that have been converted by the image conversion unit and in which parts belonging to different density ranges are emphasized. An inspection unit.

  In the optical inspection apparatus having this configuration, for example, when the change in the color of the inspection region is small, it is easy to determine the quality of the article by performing image conversion that enhances the density range of the region to obtain an enhanced image. I have to. Usually, in such an emphasized image, it may be difficult to determine the quality of the article in this area because the area outside the density range emphasized by image conversion may have a color jump or a small color change. . In the optical inspection apparatus having this configuration, in addition to the previous emphasized image, a density range different from the original light transmission image before conversion to the emphasized image or a portion belonging to the density range emphasized by the previous emphasized image is emphasized. The quality of the article is determined using at least two images of the emphasized image. For this reason, it is possible to easily determine the quality of the article in a range that is difficult to detect in the previous emphasized image. As a result, the entire article can be inspected with high accuracy.

  In the optical inspection device according to an embodiment of the present disclosure, the inspection unit may determine the quality of the article based on a change in density when the light transmission image and / or the enhanced image is scanned in one direction.

  With the optical inspection apparatus having this configuration, it is possible to accurately and easily determine the quality of an article.

  In the optical inspection device according to an embodiment of the present disclosure, the light detection unit can detect with 12 bits, and the image conversion unit converts the light transmission image generated with 12 bits into an 8-bit enhanced image. Good.

  In the optical inspection apparatus having this configuration, the image capacity can be reduced, so that the load on the image processing in the inspection unit can be reduced and the processing speed can be increased.

  In the optical inspection device according to an aspect of the present disclosure, the image conversion unit may automatically set the specific density range based on a histogram related to density that can be acquired from the light transmission image.

  For example, when an area in which a density value in a light transmission image is distributed in a certain range is set as an inspection target area, it is difficult to determine whether the article is good or bad. In the optical inspection apparatus having this configuration, it is possible to automatically extract the deviation of the density value from the light transmission image and obtain an emphasized image in which the portion belonging to the density range is emphasized. Can do.

  In the optical inspection device according to an aspect of the present disclosure, the image conversion unit includes a first enhanced image in which a portion belonging to the first density range in the light transmission image is emphasized, and a lighter image than the first density range in the light transmission image. The inspection unit may inspect the quality of the article based on the first emphasized image and the second emphasized image by converting into two images of the second emphasized image in which the portion belonging to the two density range is emphasized.

  In the optical inspection apparatus with this configuration, for example, a portion where the contents exist and a relatively dark image portion as a light transmission image, and a portion where the contents do not exist and a relatively bright image portion as a light transmission image Are emphasized, and the quality of the article is determined based on each emphasized image. When a foreign object exists in a relatively dark image part as a light transmission image where the content exists, the color change of the light transmission image is small and it is difficult to detect the foreign object. In the one-enhanced image, a relatively dark image portion is emphasized as the light transmission image, so that foreign matter can be easily detected. In addition, when a foreign object exists in a relatively bright image portion as a light transmission image where there is no content, in the second enhanced image converted as described above, a relatively bright image as a light transmission image Since the portion is emphasized, the quality of the article can be more easily determined.

  The optical inspection apparatus according to an aspect of the present disclosure may further include an inspection result storage unit that stores an image that explicitly indicates the inspection result in the second emphasized image.

  For example, in an article in which the contents are packaged by a packaging material, the portion where the contents exist and a relatively dark image portion often occupies a large proportion in the light transmission image. In the optical inspection apparatus having this configuration, an image in which symbols or the like that explicitly indicate the inspection result are superimposed on an image in which a lot of regions where foreign matters are easily detected in a light transmission image is accumulated. Can be confirmed effectively.

  You may further provide the image storage part which compresses and accumulate | stores a light transmission image and / or an emphasis image.

  In the optical inspection apparatus having this configuration, an increase in storage capacity can be suppressed even when the number of images to be accumulated increases.

  The light transmission image may be a gray scale image.

  The optical inspection apparatus may be an X-ray inspection apparatus. The X-ray inspection apparatus having this configuration can accurately inspect the entire article.

  According to one form of the present disclosure, the entire article can be inspected with high accuracy.

FIG. 1 is a configuration diagram of an X-ray inspection apparatus which is an optical inspection apparatus according to an embodiment. FIG. 2 is a functional block diagram showing a functional configuration of the X-ray inspection apparatus of FIG. FIG. 3 is a flowchart showing inspection processing of the X-ray inspection apparatus of FIG. FIG. 4A is an example of a conversion table. FIG. 4B is an example of gradation conversion in image conversion. FIG. 5A is an example of a conversion table. FIG. 5B is an example of gradation conversion in enhancement conversion. FIG. 6A is an example of a converted image. FIG. 6B is an example of a foreign object image. FIG. 7 is an example of an emphasized image. FIG. 7A is a graph showing changes in density in the X-axis direction at the center of the emphasized image. FIG. 7B is a graph showing changes in density in the X-axis direction at the end of the converted image. FIG. 7C is a graph showing changes in density in the X-axis direction at the center of the converted image. FIG. 7D is a graph showing the density change in the X-axis direction at the end of the enhanced image. FIG. 9 is an example of an inspection result image. FIG. 10A is an example of gradation conversion of a portion belonging to the density range between L1 and H1. FIG. 10B is an example of gradation conversion of a portion belonging to the density range between L2 and H2. FIG. 11 is an example of the first emphasized image. FIG. 12 is an example of the second emphasized image.

  Hereinafter, an embodiment will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

[Configuration of X-ray inspection equipment]
As shown in FIG. 1, an X-ray inspection apparatus (optical inspection apparatus) 1 includes an apparatus main body 2, support legs 3, a shield box 4, a transfer conveyor 5, and an X-ray irradiation unit (light irradiation unit) 6. And an X-ray detection unit (light detection unit) 7, a display operation unit 8, and a control unit 10. The X-ray inspection apparatus 1 obtains an X-ray transmission image (light transmission image) of the article G while conveying the article G, and inspects the article G based on the X-ray transmission image (for example, foreign matter contamination inspection, biting) Inspection, cracking chipping inspection, missing item inspection, or storage number inspection).

  The article G before inspection is carried into the X-ray inspection apparatus 1 by the carry-in conveyor 51, and the article G after inspection is carried out from the X-ray inspection apparatus 1 by the carry-out conveyor 52. The article G determined to be defective by the X-ray inspection apparatus 1 is distributed outside the production line by a sorting apparatus (not shown) arranged downstream of the carry-out conveyor 52, and is determined to be non-defective by the X-ray inspection apparatus 1. The article G passes through the sorting device as it is.

  The apparatus main body 2 accommodates the control unit 10 and the like. The support leg 3 supports the apparatus main body 2. The shield box 4 is provided in the apparatus body 2 and prevents X-ray leakage. In the shield box 4, a carry-in port 4a and a carry-out port 4b are formed. The article G before inspection is carried into the shield box 4 from the carry-in conveyor 51 via the carry-in entrance 4a, and the article G after examination is carried out from the shield box 4 to the carry-out conveyor 52 via the carry-out opening 4b. . Each of the carry-in entrance 4a and the carry-out exit 4b is provided with an X-ray shielding curtain (not shown) that prevents X-ray leakage.

  The transport conveyor 5 is disposed in the shield box 4 and transports the article G along the transport direction A from the carry-in port 4a to the carry-out port 4b. The conveyor 5 is a belt conveyor that is stretched between the carry-in port 4a and the carry-out port 4b, for example.

  The X-ray irradiation unit 6 is disposed in the shield box 4 and irradiates the article G conveyed by the conveyor 5 with X-rays (light). The X-ray irradiation unit 6 includes, for example, an X-ray tube that emits X-rays and a collimator that spreads the X-rays emitted from the X-ray tube in a fan shape in a plane perpendicular to the transport direction A.

  The X-ray detection unit 7 is disposed in the shield box 4 and detects X-rays that have passed through the article G and the conveyor 5. The X-ray detection unit 7 is configured as a line sensor, for example. Specifically, the X-ray detection unit 7 includes a plurality of photodiodes arranged one-dimensionally along a horizontal direction perpendicular to the transport direction A, and a scintillator disposed on the X-ray incident side with respect to each photodiode. And have. In this case, in the X-ray detection unit 7, X-rays incident on the scintillator are converted into light, and light incident on each photodiode is converted into an electric signal.

  The display operation unit 8 is provided in the apparatus main body 2 and displays various information, accepts input of various conditions, and the like. The display operation unit 8 is a liquid crystal display, for example, and displays an operation screen as a touch panel. In this case, the operator can input various conditions via the display operation unit 8.

  The control unit 10 is disposed in the apparatus main body 2 and controls the operation of each unit of the X-ray inspection apparatus 1. The control unit 10 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. As illustrated in FIG. 2, the control unit 10 includes an image generation unit 12, an image conversion unit 13, an inspection unit 14, and a storage unit 15. In the control unit 10, the image generation unit 12, the image conversion unit 13, and the inspection unit 14 are configured as software. However, each of these units may be configured as hardware. The storage unit 15 is configured by an mSATA standard SSD (Solid State Drive) or a hard disk as an auxiliary storage device.

  The image generation unit 12 generates a light transmission image (not shown) of the article G based on the light transmitted through the article G. The image generation unit 12 receives an A / D converted signal output from the X-ray detection unit 7 and generates an X-ray transmission image of the article G based on the signal. The A / D converted signal output from the X-ray detector 7 is a 12-bit signal. Therefore, the image generation unit 12 generates a 12-bit X-ray transmission image. The X-ray transmission image generated by the image generation unit 12 is a gray scale image.

  The image conversion unit 13 converts a 12-bit (4096 gradation) X-ray transmission image into an 8-bit (256 gradation) X-ray transmission image. The conversion from 12 bits to 8 bits is executed based on, for example, a table as shown in FIG. As shown in FIG. 4B, the image conversion unit 13 converts 4096 gradations to 256 gradations linearly. As a result, a converted image P1 shown in FIG. 6A is obtained.

  In addition to the converted image P1, the image conversion unit 13 converts a 12-bit X-ray transmission image into an enhanced image by converting the X-ray transmission image so that a portion belonging to the specific density range in the X-ray transmission image is emphasized. P3 (see FIG. 7) is generated. The generation of the emphasized image P3 by the image conversion unit 13 of the present embodiment is executed in the process of converting a 12-bit X-ray transmission image into an 8-bit X-ray transmission image. For example, the image conversion unit 13 generates the enhanced image P3 based on a table as illustrated in FIG. Based on such a table, as shown in FIG. 5B, an enhanced image P3 (FIG. 5) in which a portion belonging to a specific density range (0 to 512 gradations), that is, a portion having a relatively high density is emphasized. 7) can be obtained in the process of converting a 12-bit X-ray transmission image into an 8-bit X-ray transmission image.

  The inspection unit 14 inspects the quality of the article G based on the two images of the converted image P1 and the emphasized image P3. In the present embodiment, the inspection unit 14 determines the presence or absence of the foreign matter F based on the change in density when the converted image P1 and the emphasized image P3 are scanned in one direction. FIG. 8A is a graph showing changes in density when the central portion CA in the emphasized image P3 is scanned in the X-axis direction. FIG. 8B is a graph showing changes in density when the end EA in the converted image P1 is scanned in the X-axis direction.

  The inspection unit 14 determines whether or not there is a sudden change portion of the concentration in such a graph, and when the sudden change portion is extracted, the inspection unit 14 determines that the foreign matter F is mixed in the article G and is shown in FIG. As a result, the inspection result image P5 is generated. The inspection result image P5 is an image obtained by explicitly superimposing the inspection result on the emphasized image P3. In order to explicitly indicate the inspection result, for example, as shown in FIG. 9, there is a method of surrounding the foreign substance F with a frame M or the like or inserting a character.

  The accumulating unit (inspection result accumulating unit) 15 accumulates an inspection result image P5 (see FIG. 9) obtained by explicitly superimposing the inspection result on the emphasized image P3. The storage unit (image storage unit) 15 further compresses and stores the converted image P1 and the emphasized image P3. The conversion of the converted image P1 and the emphasized image P3 can be performed by a known method.

[Inspection process by control unit 10]
The inspection procedure by the control unit 10 described above will be described in more detail with reference to the flowchart of FIG. In the present embodiment, a relatively large amount of contents are present in the central portion CA in the Y-axis direction, and there are not many contents in both end portions EA and EA in the Y-axis direction. Article G was prepared. In such an X-ray transmission image of the article G, the density at the center CA is high and the density change is small. In such an X-ray transmission image of the article G, it is difficult to detect the foreign matter F when the foreign matter F is mixed in the central portion CA in the Y-axis direction. Therefore, in such an article G, an article G in which foreign matter F as shown in FIG. 6B may be mixed in the central portion CA in the Y-axis direction and one end portion EA in the Y-axis direction. The procedure will be described by taking the case of inspection as an example.

  First, the image generation unit 12 acquires an X-ray transmission image of the article G (step S1). Subsequently, the image conversion unit 13 generates an 8-bit converted image P1 from the 12-bit X-ray transmission image (see FIG. 6A). The conversion from the X-ray transmission image to the conversion image P1 is executed based on a table as shown in FIG. 4A, and an image with 4096 gradations is linear (linear) as shown in FIG. 4B. ) Is converted into an image having 256 gradations (step S2). Next, the image conversion unit 13 generates an 8-bit enhanced image P3 from the 12-bit X-ray transmission image (see FIG. 7). Conversion from the X-ray transmission image to the emphasized image P3 is executed based on a table as shown in FIG. 5A, and a specific density range (0 to 512 gradations) as shown in FIG. 5B. An emphasized image P3 in which the portion belonging to is emphasized is generated (step S3).

  Next, the inspection unit 14 determines the presence or absence of the foreign matter F based on the change in density when the converted image P1 and the emphasized image P3 are scanned in the X-axis direction (one direction). The inspection unit 14 inspects the foreign matter F in the center CA of the article G by scanning the emphasized image P3 in the X-axis direction, and scans the converted image P1 in the end EA of the article G by scanning in the X-axis direction. The foreign object F is inspected. FIG. 8A is a graph showing a change in density in the central portion CA of the article G in the emphasized image P3. The inspection unit 14 determines that there is a foreign substance F in the center CA of the article G based on the density change in the X-axis direction in the emphasized image P3 shown in FIG. 8A (step S4). FIG. 8B is a graph showing the density change in the X-axis direction at the end EA of the article G in the converted image P1. The inspection unit 14 determines that there is a foreign substance F at the end EA of the article G based on the density change in the converted image P1 shown in FIG. 8B (step S5).

  The inspection unit 14 determines the presence or absence of the foreign matter F in the article G based on both the determination based on the converted image P1 and the determination based on the emphasized image P3 (step S6). In the present embodiment, when it is determined that there is a foreign substance F based on at least one of the converted image P1 and the emphasized image P3, it is determined that the foreign substance F is mixed in the article G.

  When the inspection unit 14 determines the presence or absence of the foreign matter F in the article G, the inspection unit 14 generates an inspection result image P5 in which the inspection result is explicitly superimposed on the emphasized image P3 as illustrated in FIG. 9 (step S7). The inspection unit 14 compresses the inspection result image P5 (step S8) and stores it in the storage unit 15 (step S9). The inspection result image P5 can be compressed by a known method. Further, the inspection unit 14 may store the enhanced image P3 and the converted image P1 in the storage unit 15 in association with the inspection result image P5. In the X-ray inspection apparatus 1 of the present embodiment, it is determined whether or not the foreign matter F is mixed in the article G through such a series of processes.

[Characteristics and functions / effects]
In the X-ray inspection apparatus 1 of the above embodiment, as shown in FIG. 8C, when the density change of the central portion CA in the X-ray transmission image is small, an image that emphasizes the density range in the central portion CA. By executing the conversion to obtain the emphasized image P3, it is easy to determine the presence or absence of the foreign matter F in the central portion CA. As a result, the concentration range is expanded as shown in FIG. Usually, in such an enhanced image P3, it is difficult to determine the presence / absence of the foreign matter F in this portion because the area other than the density range enhanced by the image conversion has a color skip or a small color change. There is. For example, the change in density in the X-axis direction at the edge EA of the emphasized image P3 is shown in FIG. 8D. Although a sudden change part of density change can be confirmed at a position where some foreign matter F exists, At the position where the foreign object F exists, the color is lost (left side of the drawing), and it is impossible to determine the presence or absence of the foreign object F. In the X-ray inspection apparatus 1 of the present embodiment, using the two images of the previous enhanced image P3 and the converted image P1 obtained by converting the original X-ray transmission image before being converted into the enhanced image P3 into 8 bits, The presence / absence of foreign matter F is determined. Therefore, it is possible to easily determine the presence or absence of the foreign matter F at the end EA that is difficult to detect in the previous emphasized image P3. As a result, the entire article G can be inspected with high accuracy.

  In the X-ray inspection apparatus 1 of the above embodiment, the presence or absence of the foreign matter F is determined based on the change in density when the converted image P1 and the emphasized image P3 are scanned in the X-axis direction. Presence / absence can be determined.

  In the X-ray inspection apparatus 1 of the above embodiment, detection is possible with 12 bits, and an X-ray transmission image generated with 12 bits is converted into an 8-bit enhanced image P3, so that the image capacity can be reduced, The load on image processing can be reduced. In addition, the processing speed in determining the presence or absence of the foreign matter F can be increased.

  The X-ray inspection apparatus 1 according to the above embodiment further includes the storage unit 15 that compresses and stores the inspection result image P5, the converted image P1, and the enhanced image P3, so that it can be stored even when the number of stored images increases. An increase in capacity can be suppressed.

[Modification]
Although one embodiment has been described above, the present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the disclosure.

  In the above embodiment, the example in which the presence or absence of the foreign matter F is determined based on the two images of the converted image P1 and the enhanced image P3 has been described, but the present disclosure is not limited thereto. For example, the inspection unit 14 is an image converted by the image conversion unit 13, and for example, as shown in FIGS. 10A and 10B, portions belonging to different density ranges are emphasized. The presence or absence of the foreign matter F may be determined based on the two emphasized images. Even in this case, the entire article G can be inspected with high accuracy.

  In this case, the image conversion unit 13 includes a first enhanced image in which a portion belonging to the first density range (L1 to H1) in the X-ray transmission image is emphasized, and a second lighter than the first density range in the X-ray transmission image. The inspection unit 14 determines whether or not there is a foreign substance F based on the first emphasized image and the second emphasized image by converting the second emphasized image in which the portion belonging to the density range (L2 to H2) is emphasized. May be.

  In the X-ray inspection apparatus having this configuration, for example, a relatively dark image portion as an X-ray transmission image and a relatively dark image portion as an X-ray transmission image. Emphasized images (first emphasized image and second emphasized image) each emphasizing a bright image portion are generated, and the presence or absence of foreign matter F is determined based on each emphasized image. When the foreign matter F is present in a relatively dark image portion as the X-ray transmission image where the contents exist, the color change of the X-ray transmission image is small and the detection of the foreign matter F is difficult. In the converted first enhanced image, a relatively dark image portion is enhanced as an X-ray transmission image, so that the foreign object F can be easily detected. In addition, when the foreign matter F is present in a portion where the contents do not exist and is relatively bright as an X-ray transmission image, the second emphasized image converted as described above has a relative X-ray transmission image. Since brighter image portions are emphasized, the determination of the presence or absence of foreign matter F is further facilitated. In particular, the inspection accuracy can be increased when a foreign substance F or the like having a small thickness (when viewed as an X-ray transmission image has a color similar to a packaging material) is mixed in this portion.

  An example will be described in which the foreign matter F is determined using the first emphasized image P10 (see FIG. 11) and the second emphasized image P20 (see FIG. 12). For example, a case where a product G1 in which a circular article G11 and an oxygen scavenger G12 are contained in a bag is inspected will be described as an example. First, in this case as well, as in step S1, the image generation unit 12 acquires an X-ray transmission image of a product. Based on the histogram information of the X-ray transmission image of the product, the image conversion unit 13 determines two ranges having relatively high histogram values as specific density ranges (hereinafter, these two specific densities are referred to as “high density range” and (Referred to as “low concentration range”). Specifically, the concentration range of the portion corresponding to the oxygen scavenger G12 is adopted as the high concentration range, and the concentration range of the portion corresponding to the article G11 is adopted as the low concentration range. The specific density range may be specified by an operator's selection. For example, a certain range of the oxygen scavenger G12 may be specified as a high density range, and the low density range may be specified by an image in which the oxygen scavenger G12 is masked.

  Subsequently, the image conversion unit 13 generates an 8-bit first enhanced image P10 from the 12-bit X-ray transmission image for the high density range (see FIG. 11). The conversion from the X-ray transmission image to the first emphasized image P10 is executed based on a previously stored table, and the first emphasized image in which the portion belonging to the high density range is emphasized as shown in FIG. P10 is generated. Subsequently, the image conversion unit 13 generates an 8-bit second emphasized image P20 from the 12-bit X-ray transmission image for the low density range excluding the high density range (see FIG. 12). The conversion from the X-ray transmission image to the second enhanced image P20 is executed based on a previously stored table, and the second enhanced image in which the portion belonging to the low density range is enhanced as shown in FIG. 10B. P20 is generated.

  Next, the inspection unit 14 determines the presence or absence of the foreign matter F based on a change in density when the first enhanced image P10 and the second enhanced image P20 are scanned in the X-axis direction (one direction). As shown in FIG. 11, the inspection unit 14 detects the density change portion surrounded by the frame M1 from the first emphasized image P10 as the foreign matter F, and changes the density surrounded by the frames M2 and M3 from the second emphasized image P20. The portion can be detected as the foreign matter F. Note that the frame M1 and the frame M3 indicate that the foreign matter F is detected, and the frame M2 indicates that the oxygen scavenger is detected.

  In the X-ray inspection apparatus 1 according to the modification, by performing image conversion that emphasizes the concentration range in the oxygen scavenger on the entire X-ray transmission image, the first enhanced image P10 (see FIG. 11) is obtained. A foreign substance F having a concentration close to that of the oxygen scavenger G12 in the X-ray transmission image can be detected. In general, in such a first emphasized image P10, in a region other than the density range emphasized by the image conversion, the color jumps or the color change becomes small, and the presence / absence of the foreign matter F in this portion is determined. Can be difficult. For such a situation, the X-ray inspection apparatus 1 according to the modification generates the second emphasized image P20 (see FIG. 12) for a low density region that is a region other than the density range emphasized by the previous image conversion. doing. As a result, it is possible to easily determine the presence or absence of the foreign matter F present in a portion that does not overlap with the oxygen scavenger G12 and is difficult to detect in the previous first emphasized image P10. As a result, the entire product G1 can be inspected with high accuracy.

  Further, in addition to the above-described two enhanced images (first enhanced image P10 and second enhanced image P20), a density range (between L1 and H1 as shown in FIGS. 10A and 10B) is also provided. And the presence / absence of the foreign matter F is determined based on three emphasized images that take into consideration an emphasized image in which a portion belonging to a density range other than (between L2 and H2) (for example, between H1 and L2) is emphasized. Good. That is, the presence or absence of the foreign matter F may be determined based on at least two emphasized images in which portions belonging to different density ranges are emphasized.

  In the above-described embodiment or modification, an example in which the 12-bit image is downsized to the 8-bit image at the same time as generating the enhanced image P3 has been described. However, the enhanced image P3 is generated as it is with the 12-bit image. It may be. For the generation of the emphasized image P3, a known straight line emphasis process or a curve emphasis process can be used. Further, an X-ray detection unit 7 that outputs an 8-bit signal may be employed. In this case, an enhanced image P3 is generated based on an 8-bit (256 gradations) X-ray transmission image, or 8 The presence / absence of the foreign matter F may be determined based on the bit-enhanced image P3.

  In the above-described embodiment or modification, an X-ray inspection apparatus (light inspection apparatus) including an X-ray detection unit (light detection unit) that acquires a 12-bit image has been described as an example. For example, 16-bit (65536) is described. An X-ray detector that can acquire (gradation) images may be used. In this case as well, the 16-bit image may be downsized to a 12-bit or 8-bit image at the same time that the enhanced image P3 is generated.

  In the above-described embodiment or modification, when executing the process of emphasizing a specific density range, description will be given with reference to an example (for example, FIG. 5, FIG. 10A and FIG. 10B) in which straight line emphasis processing is performed. However, curve gradation processing may be executed. In this case, a γ curve may be used for this curved portion.

  In the above-described embodiment or modification, an example in which a predetermined specific density range is emphasized has been described. However, for example, based on a histogram relating to density that can be acquired from an X-ray transmission image generated by the image generation unit 12. The specific concentration range may be set every time. In this case, it is possible to automatically extract the deviation of the density value from the X-ray transmission image and obtain an enhanced image in which the portion belonging to the density range in which it is difficult to determine the presence or absence of the foreign substance F is emphasized. The accuracy of determining the presence or absence of can be improved.

  In the above embodiment, the inspection unit 14 replaces or in addition to the determination of the presence or absence of the foreign matter F based on the converted image P1 and the emphasized image P3, for example, the presence or absence of biting in the horizontal seal portion of the packaging material, the content You may determine at least one of the presence or absence of a crack of an object, the presence or absence of a missing part of a content, and the quantity of the content.

  Further, the present disclosure generates a light transmission image by detecting light (near infrared rays, other electromagnetic waves) transmitted through the article, and inspects the article based on the light transmission image. Applicable to optical inspection equipment. However, when X-rays are used as light, even if the article G is packaged, the lack of the article G is inspected without being affected by the packaging material or the printing applied to the packaging material. can do.

  Various embodiments and modifications described above may be combined in various ways without departing from the spirit of the present disclosure.

  DESCRIPTION OF SYMBOLS 1 ... X-ray inspection apparatus (optical inspection apparatus), 6 ... X-ray irradiation part, 7 ... X-ray detection part (light detection part), 8 ... Display operation part, 10 ... Control part, 12 ... Image generation part, 13 ... Image conversion unit, 14 ... inspection unit, 15 ... accumulation unit, F ... foreign matter, G ... article, G1 ... product, G12 ... deoxygenating agent, P1 ... converted image, P3 ... enhanced image, P5 ... inspection result image, P10 ... First enhanced image (enhanced image), P20 ... second enhanced image (enhanced image), CA ... center portion, EA ... end portion.

Claims (9)

A light irradiation unit for irradiating the article with light;
A light detection unit for detecting light transmitted through the article;
An image generator that generates a light transmission image of the article based on the light transmitted through the article;
An image conversion unit that generates an enhanced image by converting the light transmitted image so that a portion belonging to a specific density range in the light transmitted image is enhanced;
Based on at least two images of the light transmission image and the emphasized image, the quality of the article is inspected, or an image converted by the image conversion unit, and parts belonging to different density ranges are emphasized respectively. And an inspection unit that inspects the quality of the article based on at least two of the emphasized images.   The optical inspection apparatus according to claim 1, wherein the inspection unit determines the quality of the article based on a change in the density when the light transmission image and / or the emphasized image is scanned in one direction. The light detection unit can detect with 12 bits,
The optical inspection apparatus according to claim 1, wherein the image conversion unit converts the light transmission image generated by 12 bits into the enhanced image of 8 bits.   The optical inspection apparatus according to claim 1, wherein the image conversion unit automatically sets the specific density range based on a histogram relating to a density that can be acquired from the light transmission image. The image conversion unit emphasizes a first emphasized image in which a portion belonging to the first density range is emphasized in the light transmission image, and a portion belonging to a second density range brighter than the first density range in the light transmission image. Converted into two images of the second enhanced image,
The optical inspection apparatus according to claim 1, wherein the inspection unit inspects the quality of the article based on the first emphasized image and the second emphasized image.   The optical inspection apparatus according to claim 5, further comprising an inspection result storage unit that stores an inspection result image obtained by explicitly superimposing the inspection result on the second emphasized image.   The optical inspection apparatus according to claim 1, further comprising an image storage unit that compresses and stores the light transmission image and / or the emphasized image.   The optical inspection apparatus according to claim 1, wherein the light transmission image is a grayscale image.   The optical inspection apparatus according to claim 1, which is an X-ray inspection apparatus.