JP2012122927A - X-ray foreign matter detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray foreign matter detection device capable of reducing positional deviation of an object to be inspected on an image during image composition, and preventing a decrease in foreign matter detection capability.SOLUTION: The X-ray foreign matter detection device comprises: X-ray tubes 12a, 12b for irradiating an object W to be inspected conveyed on a conveyance path with X-rays of mutually different intensity; X-ray line sensors 50, 60 which are arranged in a conveyance direction of the object W to be inspected, have resolution higher than that needed for foreign matter determination, and respectively output image data according to X-rays which are radiated from the X-ray tubes 12a, 12b and transmitted through the object W to be inspected; an image composition part 44 for composing the image data from the X-ray line sensors 50, 60 and outputting the image data as one image data corresponding to the object W to be inspected; an image reduction part 46 for reducing image size of the image data from the image composition part 44; and a determination part 48 for determining presence or absence of foreign matter in the object W to be inspected based on the image data output by the image reduction part 46.

Description

  The present invention relates to an X-ray foreign object detection device that detects foreign substances mixed in an object to be inspected such as meat, fish, processed foods, and pharmaceuticals, and in particular, combines foreign images by synthesizing images from a plurality of X-ray line sensors. The present invention relates to an X-ray foreign matter detection apparatus that employs an energy subtraction method for obtaining an enhanced image.

  In general, an X-ray foreign object detection apparatus irradiates X-rays from X-ray generators on various types of inspection objects (for example, meat, fish, processed foods, pharmaceuticals, etc.) that are sequentially conveyed on a conveyance path at predetermined intervals. The inspection object is inspected for foreign substances such as metal, glass, stones, and bones, and a lack of the inspection object, based on the amount of transmitted X-rays.

  Conventionally, in this type of X-ray foreign object detection apparatus, the influence of the thickness of the object to be inspected can be reduced by synthesizing a plurality of images (for example, two images) obtained using X-ray sources having different tube voltages. An apparatus employing an energy subtraction method for obtaining an image in which foreign matter is emphasized is known (for example, see Patent Document 1).

JP 2010-91483 A

  However, in the conventional technique described in Patent Document 1, when the images from the two X-ray line sensor cameras are synthesized using the energy subtraction method, the element size of the X-ray line sensor camera is approximately the same as the inspection object. Therefore, there is a problem in that the edge of the inspection object is emphasized due to the displacement of the inspection object on the synthesized image, and the foreign matter detection sensitivity is lowered.

  Therefore, the present invention has been made to solve the conventional problems as described above, and can reduce the positional deviation of the inspection object on the image at the time of image composition and prevent the foreign matter detection ability from being reduced. An object of the present invention is to provide an X-ray foreign object detection device.

  An X-ray foreign matter detection apparatus according to the present invention is a first X-ray source that irradiates X-rays having different intensities to a conveying unit that conveys an object to be inspected on a conveying path and to the object to be inspected conveyed on the conveying path And the second X-ray source and the second X-ray source, which are arranged in the conveyance direction of the object to be inspected, have a resolution higher than that required for foreign object determination and are irradiated from the first X-ray source and the second X-ray source A first X-ray line sensor and a second X-ray line sensor that respectively output image data corresponding to X-rays transmitted through the inspection object, and the first X-ray line sensor and the second X-ray line Image combining means for combining image data from sensors and outputting as one image data corresponding to the object to be inspected, image reducing means for reducing the image size of the image data from the image combining means, and the image reduction Image output by means Determining means for determining whether the foreign matter of the object to be inspected in the basis of the data, characterized by comprising a.

  With this configuration, it is possible to reduce the positional deviation of the inspection object on the image derived from the element size by synthesizing using high-resolution image data by the image synthesizing means, and to reduce the image after the synthesis. By reducing by means, it is possible to further reduce the positional deviation of the inspection object remaining on the combined image as the image size is reduced.

  Further, by reducing the combined image by the image reducing unit, foreign matter can be determined without changing the specification of the determining unit.

  Therefore, it is possible to reduce the positional deviation of the inspection object on the image at the time of image synthesis and to prevent the foreign matter detection capability from being reduced.

  In addition, the X-ray foreign object detection device according to the present invention shortens the scanning cycle of the first X-ray line sensor and the second X-ray line sensor to thereby reduce the first X-ray line sensor and the first X-ray line sensor. The X-ray line sensor 2 outputs image data having a resolution higher than that required for foreign object determination.

  With this configuration, without using a high-resolution sensor for the first X-ray line sensor and the second X-ray line sensor, the positional deviation of the inspection object on the image at the time of image synthesis is reduced at a low cost. It is possible to prevent the foreign matter detection capability from being reduced.

  In the X-ray foreign object detection apparatus according to the present invention, the first X-ray line sensor and the second X-ray line sensor are made to be foreign objects by reducing the conveyance speed of the inspection object by the conveyance means. Image data having a resolution higher than that required for determination is output.

  With this configuration, without using a high-resolution sensor for the first X-ray line sensor and the second X-ray line sensor, the positional deviation of the inspection object on the image at the time of image synthesis is reduced at a low cost. It is possible to prevent the foreign matter detection capability from being reduced.

  In addition, the X-ray foreign object detection device according to the present invention can reduce the size of the detection elements of the first X-ray line sensor and the second X-ray line sensor, thereby reducing the first X-ray line sensor and The second X-ray line sensor outputs image data having a resolution higher than that required for foreign object determination.

  With this configuration, it is possible to obtain a high-resolution image in the main scanning direction in which the detection elements are arranged without causing a decrease in the inspection speed, reducing the displacement of the inspection object on the image during image synthesis, It is possible to prevent the foreign matter detection capability from being reduced.

  The present invention can provide an X-ray foreign object detection device capable of reducing the positional deviation of an inspection object on an image at the time of image composition and preventing the foreign object detection capability from being reduced.

It is a perspective view which shows schematic structure of the X-ray foreign material detection apparatus which concerns on one embodiment of this invention. It is a figure which shows the side surface and internal structure of the X-ray foreign material detection apparatus which concern on one embodiment of this invention. It is a figure which shows the concept of the image processing of the X-ray foreign material detection apparatus which concerns on one embodiment of this invention. It is a figure which shows the relationship between the magnitude | size (resolution) of the pixel size of the X-ray foreign material detection apparatus which concerns on one embodiment of this invention, and the position shift of the to-be-inspected object W. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the configuration will be described.

  As shown in FIG. 1, the X-ray foreign object detection device 1 includes a transport unit 2 and a detection unit 3 inside a housing 4, and a display 5 at the upper front of the housing 4.

  The conveyance unit 2 sequentially conveys the inspection object W at a predetermined interval. This conveyance part 2 is comprised by the belt conveyor arrange | positioned horizontally with respect to the housing | casing 4, for example. The transport unit 2 serves as a transport surface for the inspection object W loaded from the carry-in port 7 at a transport speed set in advance by driving the drive motor 6 shown in FIG. 1 toward the carry-out port 8 side (X direction in the figure). The belt surface 2a is conveyed. A space that penetrates the belt surface 2 a from the carry-in port 7 to the carry-out port 8 in the housing 4 forms a transport path 21.

  The detection unit 3 irradiates the inspection object W sequentially conveyed with X-rays in the inspection space 22 in the middle of the conveyance path 21 and detects X-rays transmitted through the inspection object W. 21 includes an X-ray generator 9 disposed at a predetermined height above the examination space 22 in the middle of the 21 and an X-ray detector 10 disposed opposite to the X-ray generator 9 in the transport unit 2. Yes.

  An X-ray generator 9 as an X-ray generation source has a configuration in which cylindrical X-ray tubes 12a and 12b provided inside a metal box 11 are immersed in insulating oil (not shown). X-rays are generated by irradiating an anode target with an electron beam from the cathodes of the ray tubes 12a and 12b. The X-ray tubes 12a and 12b are arranged such that the longitudinal direction thereof is the conveyance direction (X direction) of the inspection object W. The X-rays generated by the X-ray tubes 12a and 12b are irradiated toward the lower X-ray detector 10 so as to cross the transport direction (X direction) in a substantially triangular screen shape by a slit (not shown). It has become so.

  Here, the intensity of the X-rays generated by the X-ray tubes 12a and 12b changes in proportion to the current (tube current) flowing between the anode and the cathode of the X-ray tubes 12a and 12b, and the generated X-rays. Is shortened according to the voltage (tube voltage) applied between the anode and cathode of the X-ray tubes 12a and 12b, and the transmission power is increased. In the present embodiment, the intensity of the X-ray generated by the X-ray tube 12a is different from the intensity of the X-ray generated by the X-ray tube 12b. For example, the X-ray tube 12a has a high output and the X-ray tube 12b As low output, image data having different contrasts are output by X-rays having different transmission characteristics. Note that the intensity of X-rays generated by the X-ray tubes 12a and 12b is not necessarily fixed at a constant value, and depends on the type of foreign matter to be detected and the object W to be detected and the conveyance speed. The tube current or tube voltage of 12a, 12b is adjusted.

  The X-ray detector 10 includes an X-ray line sensor 50 and an X-ray line sensor 50 in which a plurality of detection elements are linearly arranged in the Y direction orthogonal to the transport direction on the plane in the transport direction (X direction) of the object W to be transported. The line line sensor 60 is provided in the conveyance direction of the inspection object W. The X-ray line sensor 50 outputs a detection signal (image of density data) irradiated from the high-output X-ray tube 12a and transmitted through the object W, and the X-ray line sensor 60 is a high-output X-ray tube. A detection signal (image of density data) irradiated from 12b and transmitted through the inspection object W is output.

  Here, in the present embodiment, the X-ray detector 10 converts the detection signals (luminance value data) of the X-ray line sensors 50 and 60 into digital data by a built-in A / D converter (not shown), and density data. The A / D converter is provided outside the X-ray detector 10, or the luminance value data before A / D conversion is output to the control unit 40 in the subsequent stage. A configuration may be adopted, and conversion into density data, which is digital data, is not an essential requirement.

  The X-ray detector 10 including the X-ray line sensors 50 and 60 outputs image data with a resolution higher than the resolution necessary for determining the presence or absence of foreign matter in a determination unit 48 (see FIG. 2) described later. It has become.

  For example, by reducing the size of the plurality of detection elements included in each of the X-ray line sensors 50 and 60 to be smaller than the size necessary for determining the presence or absence of contamination, high-density and high-resolution images from the X-ray detector 10. Data can be obtained.

  Moreover, by shortening the scanning cycle of the X-ray line sensors 50 and 60, the X-ray detector 10 is limited to the conveyance direction of the inspection object W. However, the X-ray detector 10 has a higher density and higher resolution than when the scanning cycle is long. Image data can be obtained.

  Further, by reducing the conveyance speed of the inspection object W, it is possible to obtain high-density and high-resolution image data from the X-ray detector 10 with respect to a certain scanning period.

  Note that the above-described methods for obtaining high-resolution image data from the X-ray detector 10 can be used in combination.

  As shown in FIG. 2, X-ray shielding shielding curtains 16 are suspended and arranged at a plurality of locations along the conveyance direction (X direction) on the ceiling portion 21 a in the conveyance path 21. The shielding curtain 16 is composed of a rubber sheet mixed with lead powder that shields X-rays and processed into a good shape (a state in which the upper part is connected and the lower part is divided into strips) and is conveyed from the inspection space 22. This prevents X-rays from leaking outside the housing 4 via the path 21. In the present embodiment, two shielding curtains 16 are provided between the carry-in entrance 7 and the inspection space 22 and between the examination space 22 and the carry-out exit 8, respectively. Even when a gap is generated due to elastic deformation due to contact with the inspection object W, the other shielding curtain 16 shields X-rays, so that leakage of X-rays can be prevented without exceeding the leakage reference amount. An inner space surrounded by the shielding curtain 16 in the conveyance path 21 constitutes an inspection space 22.

  The X-ray foreign object detection apparatus 1 includes a control unit 40 that receives density data from the X-ray detector 10 and determines the presence or absence of foreign substances in the inspection object W.

  The control unit 40 synthesizes a storage unit 42 that stores a plurality of density data from the X-ray line sensors 50 and 60 and an image of density data from the X-ray line sensors 50 and 60 (hereinafter simply referred to as an image). A combination unit 44, an image reduction unit 46 that reduces the combined image output from the image combination unit 44, and an image reduced by the image reduction unit 46 are discriminated from the object W to be inspected. The determination part 48 which determines the presence or absence of mixing of a foreign material, and the indicator 5 which displays a determination result are provided.

  The storage unit 42 temporarily stores images from the X-ray line sensors 50 and 60, and includes a memory capable of storing and reading images at high speed.

  The image synthesizing unit 44 synthesizes the image from the X-ray line sensor 50 and the image from the X-ray line sensor 60 as they are, that is, with a high resolution with a small element size (pixel size). As a result, the accuracy of alignment of the inspection object W on the image when the image from the X-ray line sensor 50 and the image from the X-ray line sensor 60 are combined is improved, and the positional deviation between the two images is increased. Is reduced.

  Specifically, as shown in FIG. 3, the image A from the X-ray line sensor 50 and the image B from the X-ray line sensor 60 are both images with a small element size (high resolution), By synthesizing these images A and B by the image synthesizing unit 44, the positional deviation between the two inspection objects W on the synthesized image AB derived from the pixel size is reduced.

  Here, the relationship between the size (resolution) of the pixel size and the positional deviation of the inspection object W will be described. As shown in FIG. 4, there is a difference between the position of the inspection object W on the image A from the X-ray line sensor 50 and the position of the inspection object W on the image B from the X-ray line sensor 60. Even when the positional deviation due to the image acquisition timing between the line sensors is excluded, the positional deviation occurs by about the element size of the X-ray line sensors 50 and 60. That is, this positional deviation is derived from the size of the pixels of the X-ray line sensors 50 and 60, that is, the resolution, and the positional deviation increases when the pixel is large and the resolution is low. By using a small and high-resolution image, the positional deviation is reduced.

  The image reduction unit 46 reduces the image synthesized by the image synthesis unit 44 to an element size necessary for foreign substance determination in the lower determination unit 48, that is, reduces the image to a low resolution image.

  Specifically, as shown in FIG. 3, the image size of the synthesized image AB after being synthesized by the image synthesizing unit 44 is reduced, so that the position shift of the inspection object remaining on the synthesized image AB after the synthesis is performed. Are further reduced as the image size is reduced. Further, by reducing the image to the element size necessary for the foreign substance determination in the lower determination unit 48 by the image reduction unit 46, it is not necessary to change the design related to the corresponding image size of the determination unit 48.

  As described above, in the present embodiment, the positional deviation is reduced by combining two images using a higher resolution image than the conventional one, and the foreign matter in the subsequent stage is reduced by reducing the combined high resolution image. In addition, a low-resolution image for the determination is determined, and the positional deviation is further reduced.

  The determination unit 48 detects foreign matter from the inspected object W on the image reduced by the image reduction unit 46 and determines whether foreign matter is mixed.

  Further, the control unit 40 includes a setting unit 49, from which the X-ray output of the X-ray generator 9, the conveyance speed of the inspection object W, the scanning cycle of the X-ray detector 10, etc. Inspection parameter setting operations and selection operations are performed.

  Next, the operation will be described.

  The control unit 40 drives the transport unit 2 at a preset speed to transport the inspection object W, and irradiates the inspection object W with X-rays from the X-ray generator 9 with a predetermined intensity.

  Next, the control unit 40 stores the image from the X-ray line sensor 50 and the image from the X-ray line sensor 60 in the storage unit 42.

  Next, the control unit 40 uses the image combining unit 44 to combine the image from the X-ray line sensor 50 and the image from the X-ray line sensor 60 with a small element size.

  Next, the control unit 40 reduces the image combined by the image combining unit 44 by the image reducing unit 46.

  Next, the control unit 40 detects foreign matter from the inspected object W on the image with respect to the image reduced by the image reduction unit 46 by the determination unit 48, determines whether foreign matter is mixed, and determines The result is displayed on the display 5.

  As described above, the X-ray foreign object detection device 1 according to the present embodiment has different strengths of X for the conveyance unit 2 that conveys the inspection object W on the conveyance path and the inspection object W that is conveyed on the conveyance path. X-ray tube 12a and X-ray tube 12b for irradiating rays, and arranged in the transport direction of inspection object W, being higher in resolution than necessary for foreign matter determination and being irradiated from X-ray tube 12a and X-ray tube 12b The X-ray line sensor 50 and the X-ray line sensor 60 that respectively output image data corresponding to the X-rays that pass through the inspection object W, and the image data from the X-ray line sensor 50 and the X-ray line sensor 60 are combined. An image composition unit 44 that is output as one image data corresponding to the object W to be inspected, an image reduction unit 46 that reduces the image size of the image data from the image composition unit 44, and image data that is output by the image reduction unit 46 Base There are provided with a determination unit 48 the presence or absence of a foreign object in the object to be inspected is W, the.

  With this configuration, it is possible to reduce the positional deviation of the inspection object W on the image derived from the element size by combining the high-resolution image data in the image combining unit 44, and to display the combined image. By reducing the size by the image reduction unit 46, it is possible to further reduce the positional deviation of the inspection object W remaining on the combined image as the image size is reduced.

  Further, by reducing the combined image by the image reduction unit 46, it is possible to determine the foreign matter without changing the specification of the determination unit 48.

  Therefore, it is possible to reduce the positional deviation of the inspection object W on the image at the time of image composition and to prevent the foreign matter detection capability from being reduced.

  In addition, the X-ray foreign object detection apparatus 1 according to the present embodiment shortens the scanning cycle of the X-ray line sensor 50 and the X-ray line sensor 60 so that the X-ray line sensor 50 and the X-ray line sensor 60 Image data having a resolution higher than that required for determination is output.

  With this configuration, the X-ray line sensor 50 and the X-ray line sensor 60 do not use a high-resolution sensor, reduce the positional deviation of the inspection object W on the image at the time of image synthesis at low cost, and detect foreign matter. Can be prevented.

  In addition, the X-ray foreign object detection apparatus 1 according to the present embodiment makes the X-ray line sensor 50 and the X-ray line sensor 60 perform foreign object determination by reducing the conveyance speed of the inspection object W by the conveyance unit 2. It is characterized in that image data having a higher resolution than necessary is output.

  With this configuration, the X-ray line sensor 50 and the X-ray line sensor 60 do not use a high-resolution sensor, reduce the positional deviation of the inspection object W on the image at the time of image synthesis at low cost, and detect foreign matter. Can be prevented.

  In addition, the X-ray foreign object detection apparatus 1 according to the present embodiment reduces the size of the detection elements of the X-ray line sensor 50 and the X-ray line sensor 60 so that the X-ray line sensor 50 and the X-ray line sensor 60 are The image data having a resolution higher than that required for foreign object determination is output.

  With this configuration, it is possible to obtain a high-resolution image in the main scanning direction in which the detection elements are arranged without causing a decrease in inspection speed, and to reduce the positional deviation of the inspection object W on the image during image synthesis. It is possible to prevent a reduction in foreign object detection capability.

  Further, in the above-described embodiment, the two X-ray line sensors 50 and 60 having different X-ray intensities are provided, but more X-ray line sensors are arranged in the transport direction of the inspection object W, and You may comprise so that the image from a X-ray line sensor may be synthesize | combined.

  As described above, the X-ray foreign object detection device according to the present invention has an effect that the positional deviation of the inspection object on the image at the time of image composition can be reduced, and the reduction of the foreign object detection capability can be prevented. The present invention is useful as an X-ray foreign object detection apparatus that employs an energy subtraction method that obtains an image in which foreign objects are emphasized by synthesizing images from X-ray line sensors.

DESCRIPTION OF SYMBOLS 1 X-ray foreign material detection apparatus 2 Conveyance part (conveyance means)
2a Belt surface 3 Detection unit 4 Housing 5 Display 6 Drive motor 7 Carry-in port 8 Carry-out port 9 X-ray generator 10 X-ray detector 11 Box 12a X-ray tube (first X-ray source)
12b X-ray tube (second X-ray source)
Reference Signs List 16 Shielding curtain 21 Transport path 21a Ceiling part 22 Inspection space 42 Storage part 44 Image composition part (image composition means)
46 Image reduction section (image reduction means)
48 determination part (determination means)
49 Setting unit 50 X-ray line sensor (first X-ray line sensor)
60 X-ray line sensor (second X-ray line sensor)
W Inspection object

Claims (4)

A transport means for transporting the inspection object on the transport path;
A first X-ray source and a second X-ray source that irradiate X-rays having different intensities to the inspection object conveyed on the conveyance path;
X-rays arranged in the direction of conveyance of the inspection object, having a resolution higher than that necessary for foreign object determination, and irradiated from the first X-ray source and the second X-ray source and transmitted through the inspection object A first X-ray line sensor and a second X-ray line sensor that respectively output image data corresponding to
Image synthesizing means for synthesizing image data from the first X-ray line sensor and the second X-ray line sensor and outputting as one image data corresponding to the inspection object;
Image reduction means for reducing the image size of the image data from the image composition means;
An X-ray foreign object detection apparatus comprising: a determination unit that determines presence / absence of a foreign substance in the inspection object based on image data output from the image reduction unit.   By shortening the scanning cycle of the first X-ray line sensor and the second X-ray line sensor, the first X-ray line sensor and the second X-ray line sensor are necessary for foreign object determination. 2. The X-ray foreign object detection device according to claim 1, wherein image data having a resolution higher than the resolution is output.   The first X-ray line sensor and the second X-ray line sensor output image data with a resolution higher than that required for foreign object determination by reducing the conveyance speed of the inspection object by the conveyance means. The X-ray foreign object detection device according to claim 1, wherein:   By reducing the size of the detection elements of the first X-ray line sensor and the second X-ray line sensor, the first X-ray line sensor and the second X-ray line sensor are used for foreign object determination. 2. The X-ray foreign object detection device according to claim 1, wherein image data having a resolution higher than a necessary resolution is output.

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