JP2008157821A - Device for inspecting x-ray foreign matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for inspecting X-ray foreign matters, capable of detecting small foreign matters on an inspection target of relatively large size, being realizable at a low cost. <P>SOLUTION: In the whole inspection, a first X-ray detection means 4a outputs an overall perspective image having a pixel of the density value corresponding to the intensity of X rays and including the overall inspection target 1. A decision means 7 acquires the overall perspective image, not only for deciding the presence of foreign matters in the inspection target 1 on the basis of the whole perspective image but also to decide if there are foreign matter candidates, and if the presence of foreign matter is not established, to start reinspection. In reinspection, a movement control means 6 moves a second X-ray detection means 4b by controlling a moving means 5. A second X-ray detection means 4b magnifies a part of the inspection target 1 having a pixel of the density value, corresponding to the intensity of X rays and containing the foreign matter candidate to output a magnified perspective image. The decision means 7 acquires the magnified perspective image to decide whether the foreign matter candidates are foreign matters, on the basis of the magnified perspective image. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an X-ray foreign substance inspection apparatus that acquires a fluoroscopic image of an inspection object by irradiating the inspection object with X-rays and determines the presence or absence of a foreign substance in the inspection object using the fluoroscopic image. is there.

  As an example of this type of X-ray foreign matter inspection apparatus, as shown in FIG. 9, an X-ray that detects X-rays from an X-ray source 3 that emits X-rays and an X-ray source 3 that passes through an inspection object 1. An apparatus including an X-ray detector 4 in which a plurality of detection units are arranged, and a transport unit 2 that transports the inspection object 1 between the X-ray source 3 and the X-ray detector 4 has been proposed. The X-ray foreign substance inspection apparatus uses a fluoroscopic image having pixels having density values corresponding to the intensity of X-rays detected by each X-ray detection unit in the X-ray detector 4 to inspect the inspection object 1 and the inspection object 1. By detecting a decrease in the intensity of the X-rays blocked by the foreign matter inside, it is inspected whether or not the foreign matter is mixed in the inspection object 1.

  By the way, the X-ray foreign substance inspection apparatus uses the fluoroscopic image to determine the presence or absence of the foreign substance in the inspection object 1, so that the higher the resolution of the fluoroscopic image, the smaller the foreign substance can be detected. However, a general X-ray foreign substance inspection apparatus has a low resolution of the fluoroscopic image, and it is difficult to detect a small foreign substance.

  Therefore, in order to improve the resolution of the fluoroscopic image, as shown in FIG. 10, the arrangement direction of the X-ray detection units (elements) in the X-ray detector 4 is orthogonal to the conveyance direction of the inspection object 1 by the conveyance means 2. By setting the angle to be inclined by an angle θ (θ ≠ 90 degrees), the pitch of the X-ray detector in the plane orthogonal to the transport direction is set to cos θ times the pitch of the actual X-ray detector. A reduced X-ray foreign substance inspection apparatus has been proposed (see, for example, Patent Document 1).

  However, in the X-ray foreign substance inspection apparatus described in Patent Document 1, the effective length of the X-ray detector 4 in the plane orthogonal to the transport direction is reduced to cos θ times the entire length of the X-ray detector 4. Therefore, the entire fluoroscopic image cannot be acquired for the inspection object 1 having a relatively large size. In order to inspect the presence or absence of a foreign substance in the inspection object 1, it is necessary to obtain a fluoroscopic image of the entire inspection object 1, so that the X-ray foreign substance inspection apparatus of Patent Document 1 has a relatively large size inspection. The object 1 cannot be inspected for the presence of foreign matter.

On the other hand, a plurality of sensors having a plurality of X-ray detection units arranged in a row so that the entire fluoroscopic image can be acquired and the presence or absence of foreign matter can be inspected even for a relatively large size inspection object 1 are conveyed by means of the conveying means 2. An X-ray foreign substance inspection apparatus in which the plurality of sensors are used as the X-ray detector 4 (detection unit) by arranging them in a line in a plane orthogonal to the conveyance direction of the inspection object 1 is proposed. (For example, refer to Patent Document 2). In this configuration, a high-resolution fluoroscopic image can be acquired for the entire inspection object 1 by a plurality of sensors, so that a small foreign object can be detected for the inspection object 1 having a relatively large size.
Japanese Patent Laying-Open No. 2004-301684 (page 4-5, FIG. 1) Japanese Patent Laying-Open No. 2005-283147 (page 4-5, FIG. 1)

  However, in the invention described in Patent Document 2, as the size of the inspection object 1 increases, a larger number of sensors are required, the cost for the X-ray detector 4 increases, and the X-ray foreign substance inspection apparatus becomes expensive. There is a problem.

  The present invention has been made in view of the above-described reasons, and provides an X-ray foreign matter inspection apparatus capable of detecting a small foreign matter with respect to an inspection object having a relatively large size, which can be realized at a low cost. The purpose is to do.

  According to the first aspect of the present invention, the conveying means for conveying the inspection object, the X-ray source for emitting X-rays to the inspection object, and the X-ray detection for detecting X-rays from the X-ray source transmitted through the inspection object. A plurality of sections are arranged, and at the time of the entire inspection for inspecting the presence or absence of foreign matter in the inspection object, the entire inspection object has pixels with density values corresponding to the intensity of the X-ray detected by each X-ray detection section. First X-ray detection means for outputting a whole fluoroscopic image including the whole X-ray detection unit, acquiring the whole fluoroscopic image at the time of the whole examination, and detecting the foreign substance in the inspection object based on the combination of the pixel density value and the number of pixels in the whole fluoroscopic image. A plurality of determination means and a plurality of the X-ray detectors are arranged to determine the presence / absence, to determine that there is a foreign matter candidate if the presence / absence of the foreign matter is not determined, and to start a reexamination to inspect whether the foreign matter candidate is a foreign matter Detected by each X-ray detector during re-examination A second X-ray detection unit for outputting an enlarged fluoroscopic image having a pixel having a density value corresponding to the intensity of the line and enlarging a part of the inspection object including at least a foreign substance candidate; and a second X-ray detection unit A moving means for moving; and a movement control means for moving the second X-ray detection means so as to obtain an enlarged fluoroscopic image at the time of reexamination by controlling the moving means. An image is acquired, and it is determined whether or not a foreign substance candidate is a foreign substance based on a combination of a pixel density value and the number of pixels in the enlarged fluoroscopic image.

  According to this configuration, in the re-inspection when it is determined that there is a foreign substance candidate in the overall inspection, the enlarged part of the inspection object including the foreign substance candidate is enlarged by moving the second X-ray detection unit. Since the fluoroscopic image is acquired from the second X-ray detection unit and it is inspected whether the foreign matter candidate is a foreign matter, it is possible to reliably determine whether the foreign matter candidate is a foreign matter in the reexamination. That is, it is possible to reliably detect even a small foreign object using a high-resolution enlarged fluoroscopic image in the reexamination while inspecting the entire inspection object using the overall fluoroscopic image in the overall inspection. In addition, this configuration does not require a large number of X-ray detection means even when the size of the inspection object increases, so that the number of sensors increases as the size of the inspection object increases. Thus, an X-ray foreign substance inspection apparatus can be realized at low cost. Accordingly, there is an advantage that a small foreign object can be detected for an inspection object having a relatively large size, although it can be realized at a low cost.

  The invention of claim 2 is the invention of claim 1, wherein the distance between the X-ray source and the transport means is constant, and the X-ray from the X-ray source spreads away from the X-ray source. When the re-examination is performed, the movement control unit adjusts the distance between the second X-ray detection unit and the X-ray source in accordance with the size of the foreign substance candidate, thereby the enlarged fluoroscopic image. It is characterized by adjusting the enlargement ratio.

  According to this configuration, at the time of re-examination, the magnification ratio of the enlarged fluoroscopic image is adjusted by adjusting the distance between the second X-ray detection means and the X-ray source according to the size of the foreign object candidate. Therefore, the smaller the foreign substance candidate is, the higher the magnification rate of the enlarged fluoroscopic image can be improved and the resolution of the enlarged fluoroscopic image can be improved, and the inspection accuracy in the reinspection is improved.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the determination means obtains the whole fluoroscopic image of the normal inspection object without foreign matter as a standard image in advance before the whole inspection. A difference image between the acquired image and the standard image is generated by using the entire fluoroscopic image acquired from the first X-ray detection means at the time of the entire inspection as an acquired image, and the difference image is generated. A pixel having a density value equal to or higher than a predetermined value is determined as an abnormal pixel, and it is determined whether there is a foreign substance in the inspection target or whether there is the foreign substance candidate based on a combination of the density value and the number of pixels of adjacent abnormal pixels. Features.

  According to this configuration, the determination unit determines whether there is a foreign object in the inspection object or the foreign object candidate using a difference image obtained by taking a difference between the acquired image and the standard image at the time of the entire inspection. It is possible to avoid erroneously determining a contour or the like of a normal inspection object having no foreign matter as a foreign matter or a foreign matter candidate.

  According to a fourth aspect of the present invention, there is provided the X-ray source according to any one of the first to third aspects, wherein the first and second X-ray detection means include a plurality of X-ray detection units arranged two-dimensionally. And the movement means is configured to move the X-ray detector, and the movement control means is at a reference position where the whole fluoroscopic image is obtained during the whole examination. A period in which the X-ray detector is moved by the moving means, the X-ray detector is moved by the moving means to the enlarged position where the enlarged fluoroscopic image is obtained at the time of the re-examination, and the entire inspection is performed on one inspection object When the inspection object stops at a predetermined inspection position set between the X-ray source and the X-ray detector, and the re-inspection is performed, the inspection object continues at the stop position until the re-inspection is completed. Said conveying means to stop Characterized in that it comprises a conveyance control means for controlling.

  According to this configuration, since both the first and second X-ray detection means comprise one X-ray detector, the configuration is simpler than when both the first and second X-ray detection means are provided separately. become. In addition, the conveyance control means stops the inspection object at a predetermined inspection position during the period for performing the entire inspection on one inspection object, and when re-inspecting, stops the inspection object until the re-inspection is completed. Since the stop is continued at the position, the movement range of the X-ray detector can be kept between the reference position and the enlarged position, leading to simplification of the moving means and the movement control means.

  According to a fifth aspect of the present invention, in any one of the first to third aspects, the X-rays from the X-ray source are arranged in the transport direction of the inspection object between the X-ray source and the transport means. The transport unit is irradiated with two fan beams, and the first X-ray detection unit detects a fan beam on the upstream side in the transport direction in which a plurality of the X-ray detection units are arranged one-dimensionally, and The second X-ray detection means is characterized in that a plurality of the X-ray detection units are arranged one-dimensionally to detect a fan beam on the downstream side in the transport direction.

  According to this configuration, since the entire inspection is performed on the upstream side in the conveyance direction of the inspection object and the re-inspection is performed on the downstream side in the conveyance direction of the inspection object, the conveyance of the inspection object by the conveyance unit is temporarily stopped. Both the overall inspection and the re-inspection can be performed. Therefore, the time required for the inspection of the inspection object can be shortened compared to the case where the inspection object is temporarily stopped and the inspection object is inspected.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the center of a part corresponding to the foreign substance candidate in the enlarged fluoroscopic image is determined when the movement control unit performs the reexamination. The position of the second X-ray detection means is adjusted by the moving means so as to overlap the measurement center of the second X-ray detection means.

  According to this configuration, at the time of re-examination, the center of the part corresponding to the foreign substance candidate in the enlarged fluoroscopic image overlaps with the measurement center of the second X-ray detection unit. By avoiding protruding from the X-ray detection means, all the X-rays that have passed through the foreign substance candidate can be received by the second X-ray detection means. Thereby, the enlargement ratio of the enlarged fluoroscopic image can be increased in the re-examination, and the resolution of the enlarged fluoroscopic image is further improved.

  The invention of claim 7 is the invention according to any one of claims 1 to 6, wherein when the determination means detects a plurality of the foreign substance candidates from one inspection object in the overall inspection, A defect index indicating the degree of possibility of being a foreign substance is calculated for each foreign substance candidate based on the density value and the number of pixels of each foreign substance candidate in the fluoroscopic image, and the foreign substance candidate having the highest defect index is subject to the re-examination. When the foreign object candidate is determined not to be a foreign object in the re-inspection, the presence or absence of the foreign object is determined by separately inspecting the inspection object.

  According to this configuration, among the plurality of foreign matter candidates, the degree of possibility of being a foreign matter, that is, the foreign matter candidate with the highest defect index is targeted for re-examination, so compared to the case where all the foreign matter candidates are re-inspected. Thus, the time required for inspection of one inspection object can be shortened.

  The present invention is capable of reliably detecting even small foreign objects using a high-resolution enlarged fluoroscopic image in re-examination while inspecting the entire inspection object using the overall fluoroscopic image in the overall inspection. There is an effect that a small foreign object can be detected for a large-sized inspection object.

(Embodiment 1)
As shown in FIG. 1, the X-ray foreign substance inspection apparatus according to this embodiment includes a transport unit 2 that transports an inspection object 1, an X-ray source 3 that irradiates the inspection object 1 with X-rays, and an inspection object 1. X-ray detector 4 for detecting X-rays from the X-ray source 3 that has passed through, moving means 5 for moving the X-ray detector 4, and controlling the moving means 5 to adjust the position of the X-ray detector 4 A movement control means 6 that performs the detection, and a determination means 7 that determines the presence or absence of foreign matter in the inspection object 1 using the detection result of the X-ray detector 4.

  Here, the transport means 2 transports the inspection object 1 in one direction (the direction indicated by the arrow A in FIG. 1) between the X-ray source 3 and the X-ray detector 4. The X-ray detector 4 includes a plurality of X-ray detection units (not shown) that detect X-rays, and performs output according to the intensity of the X-rays detected by each X-ray detection unit. The determination means 7 acquires a fluoroscopic image of the inspection object 1 composed of a plurality of pixels each having a density value corresponding to the intensity of the X-ray detected by each X-ray detector of the X-ray detector 4, and the fluoroscopic image Is used to determine the presence or absence of foreign matter in the inspection object 1. In addition, the density value of a corresponding pixel becomes low, so that the intensity | strength of the X-ray detected by the X-ray detection part is large.

  Here, the X-ray foreign substance inspection apparatus according to the present embodiment performs an overall inspection for inspecting the presence or absence of foreign substances in the inspection object 1 using an entire fluoroscopic image including the entire inspection object 1. However, in this overall inspection, the determination means 7 not only determines the presence or absence of foreign matter in the inspection object 1, but also determines that there is a foreign matter candidate for which it is not certain whether or not there is a foreign matter if the presence or absence of the foreign matter is not determined. . When it is determined that there is a foreign object candidate, re-inspection for inspecting whether the foreign object candidate is a foreign object is started. In the reexamination, it is inspected whether or not the foreign matter candidate is a foreign matter by using an enlarged perspective image in which a part of the inspection object 1 including at least the foreign matter candidate is enlarged.

  Here, the X-ray detector 4 includes a first X-ray detection means 4a that outputs an entire fluoroscopic image including the entire inspection object 1 during the entire inspection, and an inspection object 1 that includes at least a foreign substance candidate during the re-inspection. And the second X-ray detection means 4b for outputting an enlarged fluoroscopic image in which a part of the image is enlarged. The movement control means 6 controls the movement means 5 to move the second X-ray detection means 4b so that an enlarged fluoroscopic image can be obtained at the time of reexamination.

  The determination means 7 of the present embodiment obtains the whole fluoroscopic image of the normal inspection object 1 without foreign matter in advance as a standard image before the whole inspection, and the first X-ray detection means at the time of the whole inspection. Image processing for comparing the acquired image with the standard image is performed using the entire fluoroscopic image acquired from the output of 4a as the acquired image. Specifically, as shown in FIG. 2, the difference image is obtained by taking the difference between the acquired image and the standard image. If the difference image obtained here is the difference between the inspection object 1 actually being inspected and the normal inspection object 1 and there is a foreign object in the inspection object 1 being inspected, the foreign object A difference image corresponding to is obtained. Note that the X-ray foreign substance inspection apparatus of the present embodiment inspects for the presence or absence of a foreign substance having a lower X-ray transmittance than the inspection object 1, and when the foreign object exists in the inspection object 1. In the difference image, the density value of the portion corresponding to the foreign matter is higher than the surrounding density value.

  Here, the judging means 7 uses the pixel having the density value equal to or higher than a predetermined value in the difference image of the inspection object 1 as an abnormal pixel, and the inspection object based on the combination of the average density value of adjacent abnormal pixels and the number of pixels. The presence or absence of foreign matter in 1 is determined. However, if the presence or absence of foreign matter is not determined from the combination, it is determined that there is a foreign matter candidate as described above. Specifically, the determination means 7 determines the abnormality determination zone Z1 (see FIG. 7), normal determination zone Z2 (see FIG. 7), and gray zone Z0 (see FIG. 7) for the combination of the average density value of adjacent abnormal pixels and the number of pixels. 7) is set in advance before acquiring the whole fluoroscopic image. When the combination corresponds to the abnormality determination zone Z1, it is determined that there is a foreign object. When the combination corresponds to the normal determination zone Z2, the foreign object is It is determined that there is a foreign object candidate when the combination corresponds to the gray zone Z0. Specific examples of the abnormality determination zone Z1, the normality determination zone Z2, and the gray zone Z0 will be described later.

  Further, when it is determined that there is a foreign substance candidate in the above-described overall inspection, re-inspection is started, and the movement control means 6 adjusts the position of the second X-ray detection means 4b by the movement means 5 in accordance with the position of the foreign substance candidate. At the same time, the determination means 7 obtains an enlarged fluoroscopic image enlarged from at least a part of the inspection object 1 including the foreign substance candidate from the second X-ray detection means 4b, and uses the enlarged fluoroscopic image to determine the foreign substance candidate. It is determined whether or not is a foreign object.

  In the reexamination, the determination unit 7 determines whether or not the foreign object candidate is a foreign object based on the combination of the average density value of adjacent abnormal pixels and the number of pixels in the enlarged fluoroscopic image. However, at the time of re-examination, the gray zone Z0 is not set for the combination of the average density value of adjacent abnormal pixels and the number of pixels, the abnormality determination zone Z1 for determining that there is a foreign object, and the normal determination zone Z2 for determining that there is no foreign object. Only two areas are set. Therefore, in the re-inspection, it is not determined that there is a foreign object candidate as in the entire inspection, and the presence or absence of the foreign object in the inspection object 1 is finally determined.

  Hereinafter, a more detailed configuration of each part of the X-ray foreign substance inspection apparatus described above will be described with reference to FIG.

  Both the first and second X-ray detection means 4a and 4b are composed of one X-ray detector 4, and the moving means 5 is configured to move the entire X-ray detector 4. A belt conveyor passing between the X-ray source 3 and the X-ray detector 4 is adopted as the conveying means 2, and the inspection object 1 is placed on the upper surface side of the conveying means 2, and the X-ray source 3 and the X-ray detector 4 are conveyed in one direction (direction indicated by arrow A in FIG. 3). The X-ray source 3 is disposed immediately above the transport unit 2 and irradiates the inspection object 1 positioned immediately below the X-ray source 3 with X-rays. Here, in the X-ray detector 4, a plurality of X-ray detectors are two-dimensionally arranged in a plane along the upper surface of the conveying means 2 irradiated with X-rays from the X-ray source 3. Opposed.

  By the way, the movement control means 6 moves the X-ray detector 4 with the movement means 5 to the reference position where the whole fluoroscopic image is obtained so that the X-ray detector 4 operates as the first X-ray detection means 4a during the whole examination. On the other hand, at the time of re-examination, the X-ray detector 4 is moved by the moving means 5 to an enlarged position where an enlarged fluoroscopic image is obtained so that the X-ray detector 4 is operated as the second X-ray detecting means 4b.

  Here, the moving means 5 is configured to be able to move the X-ray detector 4 in the three axial directions of the vertical direction, the front-rear direction (the conveyance direction of the inspection object 1 by the conveyance means 2), and the left-right direction. Here, in this embodiment, the X-rays from the X-ray source 3 diverge so as to spread away from the X-ray source 3, and the distance between the X-ray source 3 and the conveying means 2 is constant. Therefore, if the distance from the foreign object candidate to the X-ray detector 4 is changed, the enlargement ratio of the image of the foreign object candidate projected on the X-ray detector 4 changes, and the enlargement ratio of the fluoroscopic image acquired by the determination means 7 Changes. By utilizing this, the magnification (magnification position) of the X-ray detector 4 at the time of re-examination is adjusted, thereby adjusting the magnification of the enlarged fluoroscopic image of the foreign object candidate 8 in the inspection object 1.

  Specifically, the enlargement ratio of the enlarged perspective image of the foreign object candidate 8 in the inspection object 1 is determined by the positional relationship among the X-ray source 3, the foreign object candidate 8, and the X-ray detector 4, and is shown in FIG. Thus, if the distance between the X-ray source 3 and the foreign object candidate 8 is y and the distance between the X-ray detector X4 and the foreign object candidate 8 is y, the enlargement ratio r is r = {(x + y) / x}. expressed. That is, as the X-ray detector 4 is moved away from the X-ray source 3, the enlargement ratio is improved and re-inspection can be performed with higher resolution. In the present embodiment, based on the size of the foreign object candidate 8 detected in the overall inspection (that is, the number of adjacent abnormal pixels), the enlarged fluoroscopic image having the maximum magnification within the range including the entire foreign object candidate 8 is included. Is determined so that the distance between the X-ray detector 4 and the inspection object 1 at the time of re-examination is determined.

  Therefore, the movement control means 6 moves the distance between the inspection object 1 and the X-ray detector 4 by lowering the X-ray detector 4 by the movement means 5 when it is determined that there is a foreign substance candidate 8 in the entire inspection. And the determination means 7 can acquire an enlarged perspective image. At this time, by appropriately moving the X-ray detector 4 back and forth, right and left, the center of the part corresponding to the foreign substance candidate 8 in the enlarged fluoroscopic image (that is, the image of the foreign substance candidate 8 projected on the X-ray detector 4). The position (enlarged position) of the X-ray detector 4 is adjusted so that the center of the X-ray detector 4 is positioned at the measurement center of the X-ray detector 4. As a result, the X-rays that have passed through the foreign object candidate 8 as shown in FIG. 5A can be prevented from protruding from the X-ray detector 4, and all the X-rays that have passed through the foreign object candidate 8 as shown in FIG. It can be received by the X-ray detector 4. Here, the intersection of the center line between both ends in the front-rear direction and the center line between both ends in the left-right direction of the part corresponding to the foreign substance candidate 8 in the enlarged fluoroscopic image is positioned at the measurement center of the X-ray detector 4. However, the present invention is not limited to this. For example, the X-ray detector 4 may be positioned at the measurement center with the center of gravity of the part corresponding to the foreign object candidate 8 in the enlarged fluoroscopic image as the center.

  By the way, the X-ray foreign substance inspection apparatus has a predetermined inspection position in which the inspection object 1 is set between the X-ray source 3 and the X-ray detector 4 during the period of performing the entire inspection on one inspection object 1. Is provided with a conveyance control means 9 for controlling the conveyance means 2 so as to stop at the above. Thereby, the conveying means 2 will intermittently convey the inspection object 1 while repeating the movement and stop of the inspection object 1. Then, when performing re-inspection, the conveyance control means 9 continues to stop the inspection object 1 at the inspection position until the re-inspection is completed. That is, the X-ray foreign substance inspection apparatus performs a whole inspection within a period when the inspection object 1 is stopped at the inspection position, and also performs a re-inspection within the period when performing a re-inspection.

  The X-ray foreign substance inspection apparatus described above uses, for example, a synthetic resin sealing material used for sealing parts in an electronic device or the like as the inspection object 1, so that foreign substances such as metal pieces in the inspection object 1 are removed. Used to determine the presence or absence by nondestructive inspection. For the inspection object 1 that is determined to be contaminated, measures such as discarding are taken.

  Below, the operation example of the X-ray foreign material inspection apparatus of this embodiment is shown.

  For example, if the density value in the difference image is defined as 0 (white) to 1.0a (black) and a pixel having a density value of 0.5a or more is defined as an abnormal pixel 10, the abnormal pixel 10 having a density value of 1.0a. In the case of the example of FIG. 6A in which there are four abnormal pixels 10 having a density value of 0.8a and four abnormal pixels 10 having a density value of 0.6a in the vicinity thereof, the adjacent abnormal pixels 10 The number of pixels is 9, and the average density value of the adjacent abnormal pixels 10 is {1.0a + (4 × 0.8a) + (4 × 0.6a)} / 9 to 0.73a. In FIG. 6, the density value of each pixel is shown in each pixel.

  Here, each of the above-described abnormality determination zone Z1, normality determination zone Z2, and gray zone Z0 is defined in association with both the number of adjacent abnormal pixels 10 and the average density value, as shown in FIG. As described above, the entire range in which the number of abnormal pixels 10 is 5 to 10 and the range in which the number of abnormal pixels 10 exceeds 10 and the average density value is 0.3a or less are defined as a gray zone Z0. On the other hand, the range in which the number of abnormal pixels 10 is less than 5 is the normal determination zone Z2 regardless of the average density value, and the range in which the number of abnormal pixels 10 exceeds 10 and the average density value exceeds 0.3a. The abnormality determination zone Z1.

  That is, the judgment means 7 determines whether the foreign object candidate is 5 to 10 in the overall inspection, or if the number of abnormal pixels 10 exceeds 10 and the average density value is 0.3a or less. If the number of abnormal pixels 10 does not reach 5, it is determined that there is no foreign matter regardless of the average density value, the number of abnormal pixels 10 exceeds 10, and the average density value Is greater than 0.3a, it is determined that there is a foreign object. Here, it is conceivable to set the range of the gray zone Z0 only for the number of pixels. However, when a large number of abnormal pixels 10 having a low density value are detected due to noise or the like, it is erroneously determined that there is a foreign object. In order to avoid this, it is desirable to set the range of the gray zone Z0 for the combination of the number of abnormal pixels 10 and the average density value as described above.

  In the example shown in FIG. 6A, since the number of abnormal pixels 10 is 9 and the average density value of abnormal pixels 10 is 0.73a, it corresponds to the gray zone Z0. 8 is judged. Therefore, the determination unit 7 starts reinspection.

  At the time of re-inspection, the movement control means 6 moves the X-ray detector 4 by the moving means 5 according to the position of the foreign object candidate 8 on the inspection object 1, and at least a part of the inspection object 1 including the foreign object candidate 8. An enlarged magnified perspective image can be obtained. The determination unit 7 acquires an enlarged fluoroscopic image from the X-ray detector 4 and performs reexamination using the enlarged fluoroscopic image. In the re-examination, it is not determined that there is the foreign object candidate 8 as in the entire inspection, and the presence or absence of the foreign object is finally determined.

  By the way, in the above description, the case where the foreign object candidate 8 is detected only at one place of one inspection object 1 has been described, but actually, the foreign object candidate 8 is detected at a plurality of places of one inspection object 1. There is also. In the latter case, each of the plurality of foreign matter candidates 8 may be reexamined to determine whether or not it is a foreign matter. However, in this configuration, it is necessary to repeat the reexamination for the number of foreign matter candidates 8. There is a problem that it takes a long time to stop the inspection object 1 at the inspection position between the X-ray source 3 and the X-ray detector 4. Therefore, in the present embodiment, by adopting the following configuration, the time for stopping the inspection object 1 at the inspection position when a plurality of foreign object candidates 8 are detected is shortened.

  When a plurality of foreign object candidates 8 are detected from one inspection object 1, the determination means 7 calculates a defect index indicating the degree of possibility of being a foreign object for each foreign object candidate 8, and the foreign object candidate 8 having the highest defect index. Are subject to re-examination. Here, the defect index is calculated using a predetermined evaluation function with the number of pixels and the density value of the abnormal pixels 10 in each foreign substance candidate 8 as parameters, and the higher the defect index, the higher the possibility of being a foreign object. . Here, as an example, the sum of the density values of the abnormal pixels 10 in each foreign substance candidate 8 is used as each defect index.

  As shown in FIG. 6 (a), there are four abnormal pixels 10 having a density value of 0.8a and four abnormal pixels 10 having a density value of 0.6a around the abnormal pixel 10 having a density value of 1.0a. 6 foreign object candidates 8, as shown in FIG. 6 (b), the abnormal pixel 10 having a density value of 1.0a, four abnormal pixels 10 having a density value of 0.8a, and a density value of 0.7a. The defect index is calculated when two foreign pixels 10, three abnormal pixels 10 with a density value of 0.6 a, and foreign object candidate 8 with one abnormal pixel 10 with a density value of 0.5 a are detected. An example is shown. For the foreign object candidate 8 in FIG. 6A, the defect index is 0.6a + 0.8a + 0.6a + 0.8a + 1.0a + 0.8a + 0.6a + 0.8a + 0.6a = 6.6a, whereas the foreign object candidate in FIG. 6B. For 8, the defect index is 0.5a + 0.6a + 0.6a + 0.7a + 0.8a + 0.8a + 1.0a + 0.8a + 0.7a + 0.8a + 0.6a = 7.9a.

  Therefore, the judging means 7 re-inspects only the foreign substance candidate 8 of FIG. 6A having the highest defect index, and does not re-examine the foreign substance candidate 8 of FIG. 6B. As a result of the re-examination, when it is determined that the foreign object candidate 8 is a foreign object, it is determined that a foreign object is mixed in the inspection object 1. On the other hand, when it is determined that the foreign object candidate 8 is not a foreign object, it is assumed that the remaining foreign object candidates 8 are also not foreign objects. That is, if the foreign object candidate 8 having the highest possibility of being a foreign object is not a foreign object, it can be estimated that the remaining foreign object candidate 8 is not a foreign object. In this case, the remaining foreign object candidate 8 is reproduced using an enlarged perspective image. There is no inspection. According to this configuration, since only the foreign object candidate 8 with the highest defect index is re-inspected, the time for stopping the inspection object 1 at the inspection position is shortened compared to the case where all the foreign object candidates 8 are re-inspected. it can. However, for the inspection object 1 determined that the foreign object candidate 8 having the highest possibility of being a foreign object is not a foreign object, for example, an inspector performs a separate inspection to visually inspect the entire fluoroscopic image. Inspect again for the presence of foreign material.

(Embodiment 2)
As shown in FIG. 8, the X-ray foreign substance inspection apparatus according to the present embodiment irradiates the transport means 2 with two fan beams arranged in the transport direction of the inspection object 1 with X-rays from the X-ray source 3. The X-ray foreign substance inspection apparatus according to the first embodiment is that the point and the X-ray detector 4 have first X-ray detection means 4a and second X-ray detection means 4b separately receiving each fan beam. Is different.

  The X-ray foreign substance inspection apparatus illustrated in FIG. 8 is downstream in the transport direction between the X-ray source 3 and the transport unit 2 in the transport direction of the inspection object 1 relative to the first slit S1 and the first slit S1. The second slit S2 located on the side is arranged in parallel, and the X-ray from the X-ray source 3 is irradiated as two fan beams by passing through the first and second slits S1 and S2, respectively. The light means 11 is provided. Both the first and second slits S <b> 1 and S <b> 2 are extended in a direction orthogonal to the transport direction of the inspection object 1 by the transport unit 2 in a plane along the upper surface of the transport unit 2. In FIG. 8, by forming the second slit S2 longer than the first slit S1, the opening angle θ2 of the fan beam that has passed through the second slit S2 is set to the fan that has passed through the first slit S1. It is larger than the beam opening angle θ1.

  In the first X-ray detection means 4a, a plurality of X-ray detection units are arranged one-dimensionally in the longitudinal direction of the first slit S1, and the X-ray that has passed through the first slit S1 on the upstream side in the transport direction Is detected. On the other hand, in the second X-ray detection means 4b, a plurality of X-ray detection units are one-dimensionally arranged in the longitudinal direction of the second slit S2, and have passed through the second slit S2 on the downstream side in the transport direction. X-rays are detected. In each of the first and second X-ray detection means 4a and 4b, the X-ray detection units are one-dimensionally arranged. However, the inspection object 1 is in the plane along the upper surface of the conveyance means 2 by the conveyance means 2. Since it is conveyed in the direction orthogonal to the arrangement direction of the detectors, it is possible to scan the entire length of the inspection object 1 along the conveyance direction. In the determination means 7, the first and second X-ray detection means A fluoroscopic image of the inspection object 1 can be obtained from the outputs 4a and 4b. In the present embodiment, the first X-ray detector 4a and the second X-ray detector 4b have the same structure, and the same number of X-ray detectors are arranged at the same pitch.

  By the way, in the first X-ray detection unit 4a and the second X-ray detection unit 4b, the magnification of the image of the inspection object 1 to be projected is set separately. That is, the distance between the first X-ray detection means 4a and the inspection object 1 is set so that the entire image of the inspection object 1 is projected on the first X-ray detection means 4a, and the second X-ray is detected. The distance between the second X-ray detection means 4b and the inspection object 1 is set so that the image of the foreign object candidate 8 in the inspection object 1 is projected on the detection means 4b. Here, the determination means 7 of the present embodiment includes a first determination unit 7a that acquires an overall fluoroscopic image from the output of the first X-ray detection means 4a during the entire examination, and a second X-ray detection means 4b during the re-examination. And a second determination unit 7b that acquires an enlarged perspective image from the output of.

  Further, the moving means 5 for moving the X-ray detector 4 is provided only for the second X-ray detection means 4b. The moving means 5 is configured to be able to move the second X-ray detecting means 4b in the biaxial direction of the vertical direction and the horizontal direction. Here, as the second X-ray detection means 4b is moved away from the X-ray source 3, the enlargement ratio of the enlarged fluoroscopic image is improved, and reexamination can be performed with higher resolution. In the present embodiment, based on the size of the foreign object candidate 8 detected in the overall inspection (that is, the number of adjacent abnormal pixels 10), the maximum enlargement ratio is expanded within the range including the entire foreign object candidate 8. An enlargement ratio is determined so that a fluoroscopic image can be obtained, and a distance between the second X-ray detection means 4b and the inspection object 1 is determined based on the enlargement ratio.

  Furthermore, the movement control means 6 moves the second X-ray detection means 4b in the left-right direction by the movement means 5 at the time of re-examination, so that the center of the part corresponding to the foreign substance candidate 8 in the enlarged fluoroscopic image (that is, The position of the second X-ray detection unit 4b is set so that the center of the image of the foreign object candidate 8 projected on the second X-ray detection unit 4b is positioned at the measurement center of the second X-ray detection unit 4b. Adjust. Thereby, it is possible to avoid the X-rays that have passed through the foreign object candidate 8 from protruding from the second X-ray detection unit 4b, and all the X-rays that have passed through the foreign object candidate can be received by the second X-ray detection unit 4b.

  According to the above-described configuration, the X-ray foreign substance inspection apparatus is a fluoroscopic image of the entire inspection object 1 (obtained from the output of the first X-ray detection unit 4a provided on the upstream side in the transport direction of the inspection object 1). When a whole inspection is performed using the whole fluoroscopic image) and it is determined that there is a foreign substance candidate 8 in this whole inspection, the second X-ray detection means 4b provided on the downstream side in the transport direction of the inspection object 1 Since the reexamination is performed using the fluoroscopic image (enlarged fluoroscopic image) obtained by enlarging the foreign substance candidate 8 obtained from the output, the inspection object 1 can be conveyed at a constant speed without stopping the conveying means 2. The time required for the inspection of the inspection object 1 can be shortened. Moreover, since the conveyance control means 9 for controlling the conveyance means 2 so as to intermittently convey the inspection object 1 can be omitted in the present embodiment, the configuration is simplified.

  Other configurations and functions are the same as those of the first embodiment.

It is a schematic block diagram of Embodiment 1 of the present invention. It is operation | movement explanatory drawing same as the above. It is a schematic block diagram same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is explanatory drawing which shows the fluoroscopic image of a foreign material candidate same as the above. It is explanatory drawing which shows the abnormality determination zone used normally, a normal determination zone, and a gray zone. It is a schematic block diagram of Embodiment 2 of this invention. It is a schematic block diagram which shows a prior art example. It is a schematic block diagram which shows another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection object 2 Conveyance means 3 X-ray source 4 X-ray detector 4a 1st X-ray detection means 4b 2nd X-ray detection means 5 Movement means 6 Movement control means 7 Judgment means 8 Foreign substance candidate 9 Conveyance control means A Transport direction

Claims (7)

  A plurality of transport means for transporting the inspection object, an X-ray source that emits X-rays to the inspection object, and a plurality of X-ray detection units that detect X-rays from the X-ray source that has passed through the inspection object are arranged. In the entire inspection for inspecting the presence or absence of foreign matter in the inspection object, the entire fluoroscopic image including the entire inspection object is output with pixels having a density value corresponding to the intensity of the X-ray detected by each X-ray detection unit. The first X-ray detection means, an overall fluoroscopic image is acquired at the time of the entire inspection, and the presence / absence of a foreign object in the inspection object is determined based on the combination of the pixel density value and the number of pixels in the entire fluoroscopic image. If the presence or absence is not confirmed, it is judged that there is a foreign substance candidate, and a determination means for inspecting whether or not the foreign substance candidate is a foreign substance and a plurality of the X-ray detection units are arranged, and at the time of re-examination, The density corresponding to the intensity of X-rays detected by each X-ray detection unit A second X-ray detection means for outputting an enlarged fluoroscopic image in which a part of an inspection target including at least a foreign object candidate is included and a moving means for moving the second X-ray detection means; Movement control means for moving the second X-ray detection means so as to obtain an enlarged fluoroscopic image at the time of reexamination by controlling the means, and the judging means acquires the enlarged fluoroscopic image at the time of reexamination, and An X-ray foreign matter inspection apparatus characterized by determining whether a foreign matter candidate is a foreign matter based on a combination of a pixel density value and the number of pixels in a fluoroscopic image.   The distance between the X-ray source and the transport unit is constant, and the X-ray from the X-ray source spreads away from the X-ray source, and the movement control unit is configured to detect the foreign object candidate during the re-examination. 2. The enlargement ratio of the enlarged fluoroscopic image is adjusted by adjusting the distance between the second X-ray detection means and the X-ray source by the moving means according to the size. The X-ray foreign matter inspection apparatus described.   The determination means obtains the whole fluoroscopic image of the normal inspection object without foreign matter as a standard image in advance before the whole examination, and the whole fluoroscopy obtained from the first X-ray detection means during the whole examination. Using the image as an acquired image, a difference image between the acquired image and the standard image is generated to generate a differential image of the inspection object. A pixel having a density value greater than or equal to a predetermined value for the differential image is defined as an abnormal pixel, and adjacent abnormal pixels 3. The X-ray foreign substance inspection apparatus according to claim 1, wherein the presence or absence of a foreign substance in the inspection target or the presence of the foreign substance candidate is determined based on a combination of the density value and the number of pixels. .   Both the first and second X-ray detection means comprise a single X-ray detector in which a plurality of the X-ray detection units are two-dimensionally arranged and arranged opposite to the X-ray source, and the moving means is an X-ray detection The movement control means moves the X-ray detector to a reference position where the whole fluoroscopic image is obtained during the whole examination, and obtains the enlarged fluoroscopic image during the reexamination. The X-ray detector is moved by the moving means to the enlarged position, and the inspection object is set to a predetermined value set between the X-ray source and the X-ray detector during a period for performing the entire inspection on one inspection object. And a conveyance control means for controlling the conveyance means so that the inspection object is continuously stopped at the stop position until the re-inspection is completed. Item 1 to Claim X-ray foreign substance inspection apparatus according to any one of.   The X-ray from the X-ray source is irradiated between the X-ray source and the transfer means as two fan beams arranged in the transfer direction of the inspection object, and the first X-ray detection is performed. A plurality of X-ray detectors arranged one-dimensionally to detect a fan beam upstream in the transport direction; and the second X-ray detector comprises a plurality of X-ray detectors arranged one-dimensionally The X-ray foreign substance inspection apparatus according to any one of claims 1 to 3, wherein a fan beam on the downstream side in the transport direction is detected.   The movement control means includes second X-ray detection means such that a center of a portion corresponding to the foreign substance candidate in the enlarged fluoroscopic image overlaps a measurement center of the second X-ray detection means during the reexamination. The X-ray foreign substance inspection apparatus according to any one of claims 1 to 5, wherein the position of the X-ray is adjusted by the moving means. The determination means is a foreign object based on the density value and the number of pixels of each foreign object candidate in the overall fluoroscopic image when a plurality of the foreign object candidates are detected from one inspection object in the overall inspection. A defect index indicating the degree of possibility is calculated for each foreign substance candidate, and the foreign object candidate with the highest defect index is the target of the re-examination, and it is determined in the re-inspection that the foreign object candidate is not a foreign object. The X-ray foreign matter inspection apparatus according to claim 1, wherein the presence or absence of foreign matter is determined by performing a separate inspection.