JP2009080031A - X-ray inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detect a foreign matter contamination in an article including a plurality of parts having different X-ray absorption rates. <P>SOLUTION: An X-ray inspection device 10 including an X-ray irradiator 13, an X-ray line sensor 14, a correction part 21b and a foreign matter detection part 21c, inspects the contamination of foreign matters D1-D3 to a commodity G. The commodity G includes: a part where the commodity main body C1 and a deoxidizer C2 overlap with each other (corresponding to the area P2 on a X-ray image P); a part where the commodity main body C1 exists but the deoxidizer C2 does not exist (corresponding to the area P1 on the X-ray image P); and an empty part of a bag C3 (corresponding to the area P3 on the X-ray image P). The correction part 21b corrects a concentration value Sr of the X-ray transmitted through the commodity G detected by the X-ray line sensor 14, so that the difference of the rate of decrease of the X-ray in each part of the commodity G is negated. The foreign matter detection part 21c detects presence of the foreign matters D1-D3 based on a concentration value Sc obtained after the correction by the correction part 21b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an X-ray inspection apparatus, and more particularly to an X-ray inspection apparatus that inspects contamination of an article having a plurality of portions having different X-ray absorption rates.

  In a production line for commodities such as food, inspection may be performed by an X-ray inspection apparatus as shown in Patent Document 1, for example, so as not to ship commodities mixed with foreign matters. Such an X-ray inspection apparatus irradiates a product with X-rays, detects a density value of X-rays transmitted through the product, and a foreign matter that greatly attenuates X-rays in the product based on the detected density value. Judge whether it is not mixed. For example, the presence of a foreign substance can be confirmed when the detected density value is below a predetermined threshold value.

  And about such a threshold value, it is necessary to set appropriately beforehand for every goods. This is because not only foreign matter but also the product itself attenuates X-rays, so that X-ray attenuation caused by foreign matters can be reliably identified.

However, depending on the product, for example, in a product in which a plurality of types of contents are included in the package, the X-ray absorption rate may be different for each part of the product. Therefore, the X-ray inspection apparatus disclosed in Patent Document 1 tries to detect a foreign object with high accuracy by preparing different threshold values for each part of a product, that is, for each area on an X-ray image showing the product. .
JP 2004-028768 A

  However, in patent document 1, in order to test | inspect one goods, many threshold values must be set in advance and the preparation for a test | inspection becomes complicated.

  An object of the present invention is to easily detect contamination of foreign matters into an article having a plurality of portions having different X-ray absorption rates.

  An X-ray inspection apparatus according to a first aspect of the present invention includes an X-ray irradiation unit, an X-ray detection unit, a correction unit, and a foreign matter detection unit, and mixes foreign matter into an article having a first portion and a second portion. inspect. The X-ray irradiation unit irradiates the article with X-rays. The X-ray detection unit outputs a signal corresponding to the density value of X-rays that have passed through the article. The correction unit corrects the density value indicated by the signal so that the difference between the attenuation rates of the X-rays in the first portion and the second portion is canceled out. The foreign matter detection unit detects the presence of foreign matter based on the density value corrected by the correction unit.

  This X-ray inspection apparatus detects the presence of foreign matter based on the concentration value of X-rays that have passed through the article, as in the conventional X-ray inspection apparatus. However, a predetermined foreign matter detection process (for example, comparison with a predetermined threshold) is not performed on the density value detected by the X-ray detection unit as it is, but a correction process is performed before the foreign matter detection process. The said correction process is a process which correct | amends a density value so that the difference of the attenuation factor of the X-ray which permeate | transmitted the different part of articles | goods may be negated. For example, the density value of the X-ray transmitted through the portion that greatly attenuates the X-ray is increased so as to approach the density value of the X-ray transmitted through the portion that does not attenuate the X-ray so much. As a result, in the subsequent foreign object detection process, a result similar to that inspecting the mixing of foreign substances into an article having a uniform physical property and thickness throughout is obtained.

  In other words, the influence of variation in the X-ray absorption rate depending on the portion of the article is eliminated, and foreign matters are not buried in the article. Therefore, it is possible to easily detect the contamination of foreign matters into an article having a plurality of portions having different X-ray absorption rates.

  An X-ray inspection apparatus according to a second aspect is the X-ray inspection apparatus according to the first aspect, wherein the first part and the second part do not overlap each other when viewed from the X-ray irradiation direction by the X-ray irradiation unit.

  An article as a specimen of the X-ray inspection apparatus can be divided into a plurality of portions having different X-ray absorption rates when viewed from the X-ray irradiation direction.

  An X-ray inspection apparatus according to a third aspect of the present invention is the X-ray inspection apparatus according to the first or second aspect of the present invention, wherein the foreign matter detection unit has a density value corresponding to the first part and a density value corresponding to the second part. Are compared with the same threshold value to detect the presence of foreign matter.

  In the foreign matter detection process of the X-ray inspection apparatus, the same threshold value is used for each density value corresponding to a plurality of portions of articles having different X-ray absorption rates. That is, the number of inspection parameters that should be set before the start of inspection is reduced as compared with the prior art as disclosed in Patent Document 1.

  An X-ray inspection apparatus according to a fourth aspect is the X-ray inspection apparatus according to any one of the first to third aspects, wherein the X-ray attenuation rate in the second part is the X-ray attenuation in the first part. Significantly greater than the rate.

  An article which is a specimen of the X-ray inspection apparatus has a portion having an extremely large X-ray absorption rate (which can appear darker than a foreign object). As such an article, for example, a product containing an oxygen scavenger containing a lot of metal components can be mentioned.

  Conventionally, when such a product is used as a specimen, a portion that significantly attenuates X-rays is masked and excluded from inspection. However, if such a dead zone portion is provided, the foreign matter cannot be detected when the foreign matter overlaps a portion (for example, a portion where the oxygen scavenger exists) that significantly attenuates X-rays.

  On the other hand, in this X-ray inspection apparatus, it is possible to detect foreign matter over the entire article without providing a dead zone portion.

  An X-ray inspection apparatus according to a fifth aspect of the present invention is the X-ray inspection apparatus according to any of the first to third aspects of the present invention, wherein the first part and the second part are compartments containing different types of contents. is there.

  An article to be a specimen of the X-ray inspection apparatus is an article having a plurality of sections each packed with different types of contents, such as a lunch box.

  An X-ray inspection apparatus according to a sixth aspect of the present invention is the X-ray inspection apparatus according to any one of the first to fifth aspects of the present invention, wherein the correction unit is configured to select the first portion and the second portion based on the density value indicated by the signal. Identify the part.

  This X-ray inspection apparatus automatically divides an article that is a specimen virtually into a plurality of portions having different X-ray absorption rates based on the density value before correction.

  An X-ray inspection apparatus according to a seventh aspect is the X-ray inspection apparatus according to any one of the first to fifth aspects, wherein the correction unit relates to the positions of the first part and the second part stored in advance. With reference to the information, the first part and the second part are identified.

  This X-ray inspection apparatus holds in advance information relating to the positions of a plurality of portions of articles having different X-ray absorption rates. Then, based on the information, the article which is a virtual sample is cut into a plurality of parts having different X-ray absorption rates.

  In the present invention, the density value detected by the X-ray detection unit is not subjected to a predetermined foreign object detection process (for example, compared with a predetermined threshold value) as it is, but is subjected to a correction process before the foreign object detection process. The said correction process is a process which correct | amends a density value so that the difference of the attenuation factor of the X-ray which permeate | transmitted the different part of articles | goods may be negated. As a result, in the subsequent foreign object detection process, a result similar to that inspecting the mixing of foreign substances into an article having a uniform physical property and thickness throughout is obtained. In other words, the influence of variation in the X-ray absorption rate depending on the portion of the article is eliminated, and foreign matters are not buried in the article. Therefore, it is possible to easily detect the contamination of foreign matters into an article having a plurality of portions having different X-ray absorption rates.

  Hereinafter, X-ray inspection apparatuses 10 and 110 according to first and second embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 shows an appearance of an X-ray inspection apparatus 10 according to the first embodiment of the present invention. The X-ray inspection apparatus 10 is an apparatus for inspecting the quality of the product G by irradiating the product G that is continuously conveyed with X-rays, which is incorporated in the production line of the product G such as food. is there. The X-ray inspection apparatus 10 inspects the presence or absence of foreign matter in the product G as one of quality inspections. In this foreign matter contamination inspection, the foreign matter that is mainly a detection target is a metal piece that can greatly attenuate X-rays.

  As shown in FIG. 4, the product G as a specimen is carried to the X-ray inspection apparatus 10 by the front conveyor 60. The product G is classified as a non-defective product or a defective product in the X-ray inspection apparatus 10. The inspection result in the X-ray inspection apparatus 10 is sent to a distribution mechanism 70 disposed on the downstream side of the X-ray inspection apparatus 10. The distribution mechanism 70 sends the product G determined to be a non-defective product in the X-ray inspection apparatus 10 to the regular line conveyor 80, and the product G determined to be a defective product in the X-ray inspection apparatus 10 to the defective product storage conveyor 90. And send.

[Configuration of X-ray inspection equipment]
As shown in FIGS. 1, 2, and 5, the X-ray inspection apparatus 10 includes a shield box 11, a conveyor 12, an X-ray irradiator 13, an X-ray line sensor 14, an LCD monitor 30 with a touch panel function, and a control computer 20. Etc.

(1) Shield box On both side surfaces of the shield box 11, openings 11 a for carrying the product G in and out of the shield box 11 are formed. The opening 11 a is blocked by a shielding nolen 16 in order to prevent leakage of X-rays to the outside of the shield box 11. The shielding nolen 16 is molded from rubber containing lead, and is pushed away by the product G when the product G passes through the opening 11a.

  In the shield box 11, a conveyor 12, an X-ray irradiator 13, an X-ray line sensor 14, a control computer 20 and the like are accommodated. Further, in addition to the LCD monitor 30, a key slot, a power switch, and the like are disposed on the upper front portion of the shield box 11.

(2) Conveyor The conveyor 12 conveys the product G in the shield box 11, and is disposed so as to penetrate through the openings 11a formed on both side surfaces of the shield box 11, as shown in FIG. . And the conveyor 12 conveys the goods G mounted on the belt, rotating an endless belt with the drive roller driven by the conveyor motor 12a (refer FIG. 5).

  The conveyance speed by the conveyor 12 is finely controlled by the inverter control of the conveyor motor 12a by the control computer 20 so as to be the set speed input by the operator. The conveyor motor 12a is equipped with an encoder 12b (see FIG. 5) that detects the conveying speed of the conveyor 12 and sends it to the control computer 20.

(3) X-ray irradiator As shown in FIG. 2, the X-ray irradiator 13 is an X-ray source disposed above the central portion of the conveyor 12 and is fan-shaped toward the lower X-ray line sensor 14. X-rays are irradiated to the irradiation range X.

(4) X-ray line sensor As shown in FIG. 3, the X-ray line sensor 14 is arrange | positioned under the conveyor 12, and is mainly comprised from many pixel sensors 14a. These pixel sensors 14 a are horizontally arranged in a straight line in a direction orthogonal to the conveying direction by the conveyor 12. Each pixel sensor 14a detects X-rays that have passed through the product G or the conveyor 12, and outputs an X-ray fluoroscopic image signal. The X-ray fluoroscopic image signal indicates X-ray brightness (density value Sr).

(5) LCD monitor The LCD monitor 30 is a full-dot liquid crystal display, and displays an X-ray image and a determination result of the presence or absence of foreign matter. The LCD monitor 30 also has a touch panel function, displays a screen that prompts the operator to input inspection parameters necessary for inspection, and accepts input of inspection parameters from the operator.

(6) Control Computer As shown in FIG. 5, the control computer 20 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, a RAM (Random Access Memory) 23, an HDD (Hard Disk) 25, and a storage medium. The drive 24 for inserting etc. is mounted.

  In the CPU 21, various programs stored in the ROM 22 and the HDD 25 are executed. The HDD 25 stores and accumulates inspection parameters and inspection results. The inspection parameter can be changed by an input from the operator using the touch panel function of the LCD monitor 30. The operator can set so that these data are stored and accumulated not only in the HDD 25 but also in a storage medium inserted in the drive 24.

  Further, the control computer 20 includes a display control circuit (not shown) for controlling data display on the LCD monitor 30, a key input circuit (not shown) for capturing data keyed by the operator via the LCD monitor 30, A communication port (not shown) that enables connection to an external device such as a printer or a network such as a LAN (local area network) is also provided.

  And each part 21-25 of the control computer 20 is mutually connected via bus lines, such as an address bus and a data bus.

  The control computer 20 is connected to a conveyor motor 12a, an encoder 12b, a photoelectric sensor 15, an X-ray irradiator 13, an X-ray line sensor 14, an LCD monitor 30, and the like.

  The photoelectric sensor 15 is a synchronous sensor for detecting the timing when the product G as a specimen passes through the fan-shaped X-ray irradiation range X (see FIG. 2), and is mainly a pair of sensors arranged with the conveyor 12 interposed therebetween. It consists of a projector and a light receiver.

[Inspection of contamination by control computer]
The HDD 25 of the control computer 20 stores an inspection program including an image generation module, a correction module, and a foreign object detection module. Then, the CPU 21 of the control computer 20 operates as an image generation unit 21a, a correction unit 21b, and a foreign matter detection unit 21c (see FIG. 5) by reading and executing these program modules.

  Based on the X-ray fluoroscopic image signal output from the X-ray line sensor 14, the image generation unit 21a generates an X-ray image of the product G that is a specimen.

  The correcting unit 21b corrects the density value Sr indicated by the X-ray fluoroscopic image signal output from the X-ray line sensor 14 so that the difference in the X-ray attenuation rate in each part of the product G is canceled out.

  The foreign matter detection unit 21c detects foreign matter contained in the product G based on the density value Sc corrected by the correction unit 21b.

  When a foreign object is detected by the foreign object detection unit 21c, the fact is notified from the control computer 20 to the distribution mechanism 70. The sorting mechanism 70 that has recognized that a foreign object has been detected distributes the product G containing the foreign object to the defective product storage conveyor 90.

  Hereinafter, details of operations of the image generation unit 21a, the correction unit 21b, and the foreign object detection unit 21c will be described.

(1) Image Generation Unit The image generation unit 21a performs X-ray fluoroscopy that is output from each pixel sensor 14a of the X-ray line sensor 14 when the product G passes through the fan-shaped X-ray irradiation range X (see FIG. 2). An image signal is acquired at fine time intervals, and an X-ray image of the product G is generated based on the acquired X-ray fluoroscopic image signal. The timing at which the product G passes through the fan-shaped X-ray irradiation range X is determined by a signal from the photoelectric sensor 15. More specifically, the image generating unit 21a connects X-ray density values Sr obtained from each pixel sensor 14a in fine time intervals in a time series in a matrix form, thereby copying the product G. Generate an image. This X-ray image is displayed on the LCD monitor 30 in accordance with an operator instruction.

  Hereinafter, in the description of the present embodiment, it is assumed that the product G is packaged in a bag C3 in which the product main body C1 is overlaid with the oxygen scavenger C2.

  FIG. 6A is an X-ray image P showing the product G. On the X-ray image P, there are three areas P <b> 1 to P <b> 3 that constitute an area for copying the product G. And the area P3 that appears brightest among the three areas P1 to P3 shows the empty portion of the bag C3, and the area P2 that appears next brightly is the deoxygenated product main body C1 is present. The part where the agent C2 does not exist is shown, and the darkest area P2 shows the overlapping part of the product main body C1 and the oxygen scavenger C2. Moreover, as shown to Fig.6 (a), the dark small area Q1-Q3 which exists in each area P1-P3 has shown the metal foreign material D1-D3 mixed in the goods G. As shown in FIG.

(2) Correction Unit Similar to the image generation unit 21a, the correction unit 21b acquires X-ray fluoroscopic image signals indicating X-ray density values Sr from the pixel sensors 14a of the X-ray line sensor 14 at fine time intervals. FIG. 6B shows the X-ray density value Sr along the line A1 shown in FIG. As shown in FIG. 6B, the concentration value Sr corresponding to the portion where the foreign substances D1, D3 are present is brighter than the concentration value Sr corresponding to the portion where the oxygen scavenger C2 is present. Therefore, as it is, only the foreign matter D1 to D3 cannot be detected as a foreign matter without error by comparing the density value Sr with the threshold value of 1.

  Therefore, the correction unit 21b compares each density value Sr received from each pixel sensor 14a with a threshold value T1. When it is determined that the density value Sr is darker than the threshold value T1, the density value Sr is corrected so as to be brightened by the correction amount O. The threshold T1 is a value slightly brighter than the average concentration value Sr of the area P2 corresponding to the portion where the oxygen scavenger C2 is present, and the correction amount O is equal to the average concentration value Sr of the area P1 and the area It is equal to the difference between the average density value Sr of P2. These control parameters are calculated in advance using a sample product G before the start of the inspection and stored in the HDD 25.

  FIG. 6C shows a density value Sc obtained by correcting the X-ray density value Sr shown in FIG. 6B by the above method.

(3) Foreign matter detection unit The foreign matter detection unit 21c compares each density value Sc after correction by the correction unit 21b with a threshold value T2. If it is determined that at least one density value Sc is darker than the threshold value T2, it is determined that a foreign substance is mixed in the product G, and all density values Sc are determined to be brighter than the threshold value T2. If it is determined that the product G contains no foreign matter.

[Characteristics of the X-ray inspection apparatus according to the first embodiment]
(1)
In the X-ray inspection apparatus 10, the correction process by the correction unit 21b is performed before the foreign object detection process by the foreign object detection unit 21c.

  The correction process is a process of correcting the density value Sr detected by each pixel sensor 14a of the X-ray line sensor 14 to the density value Sc. The correction amount O from the density value Sr to the density value Sc includes the average brightness of the area P2 in which the overlapping part of the product body C1 and the oxygen scavenger C2 in the product G and the product body C1 of the product G are present. This is equal to the difference from the average brightness of the area P1 where the portion where the oxygen scavenger C2 does not exist is shown.

  That is, by the correction process, the attenuation rate of the X-rays transmitted through the overlapping portion of the product main body C1 and the oxygen scavenger C2, and the attenuation of the X-rays transmitted through the portion where the product main body C1 is present and the oxygen scavenger C2 is not present. The difference from the rate will be canceled out. As a result, the influence of the variation in the X-ray absorption rate depending on the portion of the product G is eliminated, and it is easy to detect the contamination of foreign matter as if the product G is homogeneous throughout.

(2)
The commodity G contains an oxygen scavenger C2 that can attenuate X-rays more than foreign substances.

  Conventionally, when such a product G is used as a specimen, a concentration value Sr corresponding to a portion where the oxygen scavenger C2 is present is obtained by applying a mask to the portion where the oxygen scavenger C2 is present. Not subject to processing. However, in this case, the foreign matter D2 overlapping with the oxygen scavenger C2 cannot be detected.

  However, the X-ray inspection apparatus 10 can also detect the foreign matter D2 overlapping with the oxygen scavenger C2.

[Modification]
(1)
In the above embodiment, the correction unit 21b automatically detects a portion where the oxygen scavenger C2 is present by determining the magnitude relationship between the concentration value Sr and the threshold value T1. However, when the position of the oxygen scavenger C2 in the product G is fixed, information indicating the position of the portion where the oxygen scavenger C2 is present may be stored in advance in the HDD 25 or the like. In this case, only the concentration value Sr determined to correspond to the portion where the oxygen scavenger C2 is present based on the information can be the target of correction processing by the correction unit 21b.

(2)
In the above-described embodiment, the correction amount O of the density value Sr is calculated in advance using the product G as a sample before the start of inspection, and is stored in the HDD 25. However, such advance processing may be omitted, and the correction amount O may be automatically calculated during the inspection.

  For example, the correction unit 21b detects pixels whose density value Sr is darker than the threshold value T1 on the X-ray image P, and an area in which such pixels are gathered and spread to have a predetermined area. Is identified as an area P2 where the oxygen scavenger C2 is copied. Then, a representative value (for example, an average value) of the density values Sr corresponding to the pixels constituting the area P2 is obtained. Further, a representative value (for example, an average value) of the density values Sr corresponding to the pixels constituting the area other than the area P2 is obtained. The difference between these representative values is taken as a correction amount O.

  Further, in this modified example, when the area other than the area P2 that captures the oxygen scavenger C2 on the X-ray image P is divided into a plurality of areas based on the concentration value Sr (for example, the area P1 that captures the product main body C1 and the bag The area P3 that captures the empty portion of C3 and the area that captures the background of the product G) are areas that surround the area P2 that captures the oxygen scavenger C2, and are the areas closest to the area P2 (that is, A representative value (for example, an average value) of density values Sr corresponding to the pixels constituting area P1) is obtained. Then, the difference between the representative value and the representative value (for example, average value) of the density value Sr corresponding to the pixels constituting the area P2 may be used as the correction amount O. This is because it can be inferred that the oxygen scavenger C2 is overlapped with an item (product main body C1) shown in the area P1 surrounding the area P2 showing the oxygen scavenger C2.

  In addition, as a method of obtaining the representative value, there is a method of obtaining an average value of density values Sr corresponding to all pixels excluding a pixel that captures a foreign substance from pixels constituting the target area.

(3)
In the above embodiment, the density value Sr determined to correspond to the background of the product G may be masked. That is, the correction process and the foreign object detection process may be executed while ignoring the density value Sr corresponding to the background of the product G on the X-ray image P.

(4)
In the embodiment described above, the image generation unit 21a performs X based on the density value Sc corrected by the correction unit 21b in addition to or instead of the X-ray image P based on the density value Sr before correction by the correction unit 21b. A line image may be generated.

  Further, the X-ray image may be displayed on the LCD monitor 30.

  Furthermore, the foreign matter detection unit 21c may determine whether foreign matter is mixed in the product G by performing image processing on the X-ray image.

(5)
In the above-described embodiment, the method of the foreign object detection processing by the foreign object detection unit 21c is not limited to the above-described method, and any other method for detecting a foreign object can be adopted.

(6)
In the above-described embodiment, the process related to the control computer 20 may be executed in an apparatus provided separately from the main body of the X-ray inspection apparatus 10. For example, various data may be sent from the control computer 20 to a separate computer via a network, and all or part of the above processing may be executed in the computer.

(7)
The above modifications can be arbitrarily combined.

Second Embodiment
Next, an X-ray inspection apparatus 110 according to the second embodiment of the present invention will be described.

  As shown in FIG. 7, in the X-ray inspection apparatus 110 according to the second embodiment, the correction unit 21b is replaced with a correction unit 121b as compared with the X-ray inspection apparatus 10 according to the first embodiment, and the foreign matter detection unit. The difference is only in that 21c is replaced with the foreign object detection unit 121c, and the other points are the same. That is, the X-ray inspection apparatus 110 is obtained by replacing the correction module and the foreign object detection module stored in the HDD 25 of the control computer 20 of the X-ray inspection apparatus 10 with different ones. Accordingly, only the details of the correction processing and foreign matter detection processing according to the second embodiment will be described below, and the other configurations and operations of the X-ray inspection apparatus 110 are the same as those of the first embodiment, and the description thereof is omitted. To do.

[Inspection of contamination by control computer]
The HDD 25 of the control computer 20 stores an inspection program including an image generation module, a correction module, and a foreign object detection module. Then, the CPU 21 of the control computer 20 operates as the image generation unit 21a, the correction unit 121b, and the foreign object detection unit 121c (see FIG. 7) by reading and executing these program modules.

  Based on the X-ray fluoroscopic image signal output from the X-ray line sensor 14, the image generation unit 21a generates an X-ray image of the product G that is a specimen.

  The correction unit 121b corrects the density value Sr indicated by the X-ray fluoroscopic image signal output from the X-ray line sensor 14 so that the difference in the X-ray attenuation rate in each part of the product G is cancelled.

  The foreign matter detection unit 121c detects foreign matter contained in the product G based on the density value Sc corrected by the correction unit 121b.

  When a foreign object is detected by the foreign object detection unit 121c, the fact is notified from the control computer 20 to the distribution mechanism 70. The sorting mechanism 70 that has recognized that a foreign object has been detected distributes the product G containing the foreign object to the defective product storage conveyor 90.

  Details of the operations of the correction unit 121b and the foreign object detection unit 121c will be described below.

  In the description of the present embodiment, the product G is a lunch box having four compartments in which different types of contents E1 to E4 are stored.

  FIG. 8A is an X-ray image R in which the product G is copied. On the X-ray image R, there are four areas R <b> 1 to R <b> 4 that constitute an area for copying the product G. And four areas R1-R4 have shown the contents E1-E4, respectively. Moreover, as shown to Fig.8 (a), the dark small area Y1-Y3 which exists in each in area R1-R3 has shown the metal foreign material F1-F3 mixed in the goods G. As shown in FIG.

(1) Correction Unit Similar to the image generation unit 21a, the correction unit 121b acquires an X-ray fluoroscopic image signal indicating the X-ray density value Sr from each pixel sensor 14a of the X-ray line sensor 14 at fine time intervals. FIG. 8B shows the X-ray density value Sr along the line A2 shown in FIG. As shown in FIG. 8B, the density value Sr corresponding to the part where the foreign substance F2 exists is brighter than the density value Sr corresponding to the part where the contents E3 exist. Therefore, as it is, only the foreign matters F1 to F3 cannot be detected as foreign matters without error by comparing the density value Sr with the threshold value of 1.

  Therefore, the correction unit 121b divides the X-ray image R into five areas R1 to R5 based on information indicating the positions of the contents E1 to E4 stored in advance in the HDD 25 or the like. The area R5 is an area that captures the background of the product G, and is an area that is masked in the following foreign object detection processing.

Then, the correction unit 121b corrects the density value Sr corresponding to the pixels constituting the areas R1 to R4 other than the masked area R5. More specifically, the correction unit 121b includes the average value U1 of the density values Sr corresponding to all the pixels constituting the area R1, the average value U2 of the density values Sr corresponding to all the pixels constituting the area R2, and the area. An average value U3 of density values Sr corresponding to all pixels constituting R3 and an average value U4 of density values Sr corresponding to all pixels constituting area R4 are calculated. In addition, the magnitude relationship of these values U1-U4 is clear also from FIG. 8 (a) and (b),
U2>U1>U3> U4
It has become.

Then, the correction unit 121b is adding the correction amount O ₁₂ to the density value Sr corresponding to all the pixels constituting the area R1. The correction amount O ₁₂ is equal to the difference between the average brightness of the area R1 and the average brightness of the area R2, and specifically, O ₁₂ = U2−U1. Similarly, the correction unit 121b is adding the correction amount O ₃₂ to the density value Sr corresponding to all the pixels constituting the area R3. The correction amount O ₃₂ is equal to the difference between the average brightness of the area R3 and the average brightness of the area R2, and specifically, O ₃₂ = U2−U3. Similarly, the correction unit 121b is adding the correction amount O ₄₂ to the density value Sr corresponding to all the pixels constituting the area R4. The correction amount O ₄₂ is equal to the difference between the average brightness of the area R4 and the average brightness of the area R2, and specifically, O ₄₂ = U2−U4.

  FIG. 8C shows a density value Sc obtained by correcting the X-ray density value Sr shown in FIG. 8B by the above method.

(2) Foreign object detection unit The foreign object detection unit 121c compares each density value Sc after correction by the correction unit 121b with a threshold value T3. If it is determined that at least one density value Sc is darker than the threshold value T3, it is determined that foreign matter is mixed in the product G, and all density values Sc are determined to be brighter than the threshold value T3. If it is determined that the product G contains no foreign matter.

[Characteristics of X-ray Inspection Apparatus According to Second Embodiment]
In the X-ray inspection apparatus 110, the correction process by the correction unit 121b is performed before the foreign object detection process by the foreign object detection unit 121c.

The correction process is a process of correcting the density value Sr detected by each pixel sensor 14a of the X-ray line sensor 14 to the density value Sc. It should be noted that the density value Sr corresponding to the pixels constituting the brightest area R2 is used as a correction reference and is not changed (Sr = Sc). On the other hand, the density values Sr corresponding to all the pixels constituting the other areas R1, R3, and R4 are uniform for each of the areas R1, R3, and R4 so as to approach the average brightness U2 of the reference area P2. It is corrected to. The correction amounts O ₁₂ , O ₃₂ , and O _{42 at} this time are the differences between the average brightness U1, U3, U4 of the areas R1, R3, R4 and the average brightness U2 of the reference area P2. equal.

  That is, the correction process cancels the difference in the attenuation rate of the X-rays transmitted through the contents E1 to E4 of the product G. As a result, the influence of the variation in the X-ray absorption rate depending on the portion of the product G is eliminated, and it is easy to detect contamination with high accuracy as if the product G is homogeneous throughout.

[Modification]
(1)
In the above embodiment, the correction unit 121b divides the X-ray image R into five areas R1 to R5 based on information indicating the positions of the contents E1 to E4 stored in advance in the HDD 25 or the like. However, such information is not stored in advance in the HDD 25 or the like, but the correction unit 121b automatically detects five areas R1 to R5 by performing known image processing on the X-ray image R. It may be like this.

(2)
In the above embodiment, the correction amounts O ₁₂ , O ₃₂ , and O ₄₂ are automatically calculated during the inspection. However, it may be calculated in advance using the product G as a sample before starting the inspection and stored in the HDD 25 or the like.

(3)
In the above embodiment, the representative values of the density values Sr of the areas R1 to R4 are calculated as the average values U1 to U4 of the density values Sr corresponding to all the pixels constituting the areas R1 to R4. It may be calculated by a method.

  Alternatively, the representative value may be calculated by ignoring the pixels constituting the areas Y1, Y2, and Y3 that are judged to be foreign objects.

(4)
In the above-described embodiment, the image generation unit 21a performs the X based on the density value Sc corrected by the correction unit 21b in addition to or instead of the X-ray image R based on the density value Sr before correction by the correction unit 21b. A line image may be generated.

  Further, the X-ray image may be displayed on the LCD monitor 30.

  Furthermore, the foreign matter detection unit 21c may determine whether foreign matter is mixed in the product G by performing image processing on the X-ray image.

(5)
In the above-described embodiment, the method of the foreign object detection processing by the foreign object detection unit 121c is not limited to the above-described method, and any other method for detecting a foreign object can be adopted.

(6)
In the above-described embodiment, the processing related to the control computer 20 may be executed in an apparatus provided separately from the main body of the X-ray inspection apparatus 110. For example, various data may be sent from the control computer 20 to a separate computer via a network, and all or part of the above processing may be executed in the computer.

(7)
The above modifications can be arbitrarily combined.

  INDUSTRIAL APPLICABILITY The present invention is useful as an X-ray inspection apparatus, particularly an X-ray inspection apparatus that inspects contamination of articles having a plurality of portions having different X-ray absorption rates.

1 is an external perspective view of an X-ray inspection apparatus according to a first embodiment of the present invention. The block diagram inside the shield box of a X-ray inspection apparatus. The schematic diagram which shows the principle of a X-ray inspection. The block diagram before and behind an X-ray inspection apparatus. The block block diagram of the control computer concerning 1st Embodiment of this invention. (A) The figure which shows the X-ray image of goods. (B) The figure which shows the density value along line A1 before correction | amendment. (C) The figure which shows the density value along line A1 after correction | amendment. The block block diagram of the control computer concerning 2nd Embodiment of this invention. (A) The figure which shows the X-ray image of goods. (B) The figure which shows the density value along line A2 before correction | amendment. (C) The figure which shows the density value along line A2 after correction | amendment.

Explanation of symbols

10,110 X-ray inspection device 13 X-ray irradiator (X-ray irradiation unit)
14 X-ray line sensor (X-ray detector)
20 control computer 21a image generation unit 21b, 121b correction unit 21c, 121c foreign matter detection unit C1 product main body C2 oxygen scavenger C3 bag D1-D3 foreign matter E1-E4 content F1-F3 foreign matter G product (article)
P, R X-ray image Sr Density value before correction Sc Density value after correction

Claims (7)

An X-ray inspection apparatus for inspecting contamination of a foreign object into an article having a first part and a second part,
An X-ray irradiation unit for irradiating the article with X-rays;
An X-ray detector that outputs a signal corresponding to a density value of X-rays transmitted through the article;
A correction unit that corrects the density value indicated by the signal so that the difference between the attenuation rates of the X-rays in the first part and the second part is canceled;
A foreign matter detection unit for detecting the presence of the foreign matter based on the density value after correction by the correction unit;
Comprising
X-ray inspection equipment. The first part and the second part do not overlap each other when viewed from the X-ray irradiation direction by the X-ray irradiation unit,
The X-ray inspection apparatus according to claim 1. The foreign object detection unit compares the density value corresponding to the first part and the density value corresponding to the second part with the same threshold value, and detects the presence of the foreign object.
The X-ray inspection apparatus according to claim 1 or 2. The X-ray attenuation factor in the second part is significantly greater than the X-ray attenuation factor in the first part;
The X-ray inspection apparatus according to claim 1. The first part and the second part are compartments containing different types of contents,
The X-ray inspection apparatus according to claim 1. The correction unit identifies the first portion and the second portion based on a density value indicated by the signal;
The X-ray inspection apparatus according to claim 1. The correction unit identifies the first part and the second part with reference to information on the positions of the first part and the second part stored in advance.
The X-ray inspection apparatus according to claim 1.

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