JP2005283147A - X-ray foreign matter inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray foreign matter inspection apparatus for detecting smaller foreign matters as compared with a conventional apparatus and for improving detection sensitivity regarding the size of the foreign matters even if an X-ray line sensor having the same pitch between elements is used. <P>SOLUTION: The spread direction of X rays in a fan beam shape from an X-ray generator 1 and the arrangement direction of the element of the X-ray line sensor 2 are set to an angle without orthogonally crossing a direction R orthogonally crossing the conveyance direction of a tested object W by each carrying device 3, thus obtaining X-ray see-through information equivalent to a case when the pitch of the element in the R direction is multiplied by cosθ, and improving resolution in the direction R orthogonally crossing the conveyance direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an X-ray foreign substance inspection apparatus for inspecting the presence or absence of foreign substances in, for example, foods and medicines, or clothing and night items, and more specifically, irradiates fan beam X-rays. The present invention relates to an X-ray foreign matter inspection apparatus of a type that conveys an inspection object between an X-ray generation apparatus and an X-ray line sensor corresponding to the X-ray generation apparatus.

  2. Description of the Related Art Conventionally, an X-ray foreign substance inspection apparatus having a configuration as schematically illustrated in FIG. 6 has been known as an apparatus for inspecting whether or not foreign substances are mixed in food or the like under nondestructive conditions. In this example, the X-ray generator 61 outputs X-rays focused in a fan beam downward by passing the X-rays from the X-ray source 61a through the slit 61b, and faces the X-ray generator 61. Below that, an X-ray line sensor 62 in which elements are arranged in the fan beam-shaped X-ray spreading direction is arranged. The inspection object W is transported between the X-ray generator 61 and the X-ray line sensor 62 by a transport device 63 such as a belt conveyor in a direction orthogonal to the fan beam-shaped X-ray spreading direction. X-rays are irradiated, and the X-ray transmission information is detected every moment by the X-ray line sensor 62 and sequentially taken into the image processing device 64 at predetermined minute intervals.

  Each time the X-ray transmission information sequentially taken into the image processing device 64, that is, the element output to the X-ray line sensor 62 each time, represents the intensity distribution in the spreading direction of the X-ray fan beam transmitted through the inspection object W. Thus, after the inspection object W passes between the X-ray generator 61 and the X-ray line sensor 62, the image processing apparatus 64 collects the two-dimensional X-ray transmission data of the inspection object W. .

  X-ray transmission data based on the output of each element of the X-ray line sensor 62 is subjected to offset removal, sensitivity correction between elements, LOG conversion / table correction, gradation conversion, and the like, and finally is performed in the image processing apparatus 64. It is binarized and compared with the foreign object detection level to determine whether or not foreign matter is mixed in the inspection object W. If foreign matter is mixed, it is provided downstream in the transport direction of the transport device 63. A reject signal is supplied by supplying a control signal to an exclusion device (not shown) (see, for example, Patent Document 1 or Patent Document 2).

In such an X-ray foreign substance inspection apparatus, as shown in FIG. 7A, a required area including the X-ray generator 61 and the X-ray line sensor 62 is usually covered with a protective box 65. Only the entrance 65a and the exit 65b of the inspection object W are opened. Due to such a combination of the transport direction and the X-ray aperture direction, X-rays can be transmitted via the inlet 65a and the outlet 65b of the protective box 65, as compared with the case where the X-ray is not focused as shown in FIG. There is also an advantage that leakage can be reduced.
JP-A-9-145343 JP 2001-281173 A

  By the way, in the X-ray foreign substance inspection apparatus as described above, the lower limit of the size of the detectable foreign substance greatly depends on the element pitch of the X-ray line sensor 62. For example, when the pitch of the elements is 0.43 mm, it may not be possible to detect when the size of the foreign matter projected on the X-ray line sensor 62 is smaller than 0.43 mm.

  Even if an X-ray line sensor having the same pitch between elements is used, the present invention can reliably detect a foreign material smaller than that of a conventional apparatus, and thus can improve the detection sensitivity related to the size of the foreign material. An object of the present invention is to provide an X-ray foreign substance inspection apparatus capable of performing the same.

  In order to solve the above-described problems, an X-ray foreign matter inspection apparatus according to the present invention is disposed so as to face an X-ray generator that outputs X-rays focused in a fan beam, and the X-ray generator. An X-ray line sensor in which a plurality of elements are arranged in the direction in which the X-ray spreads in order to allow X-rays from the X-ray generator to enter, and an inspection is provided between these X-ray generator and X-ray line sensor. A foreign device in the fluoroscopic object by image processing using the X-ray fluoroscopic image information of the inspection object based on the output of the X-ray line sensor and the conveying device that conveys the object in a predetermined direction intersecting the X-ray In the X-ray foreign matter inspection apparatus provided with the image processing apparatus for determining the presence or absence of X-rays, the X-ray spreading direction from the X-ray generation apparatus and the arrangement direction of the elements of the X-ray line sensor are respectively the transport directions of the transport apparatus Not orthogonal to It characterized by being set each time (claim 1).

  Here, in the present invention, it is possible to change the angles of the X-ray spreading direction from the X-ray generation device and the arrangement direction of the elements of the X-ray line sensor with respect to the transport direction of the transport device (claims). Item 2) can be preferably employed.

  According to the present invention, the fan beam-shaped X-ray spreading direction and the X-ray line sensor are arranged so that the arrangement direction of the elements is in an oblique direction that is not orthogonal to the conveyance direction of the inspection object. The resolution in the direction orthogonal to the conveyance direction of the object is improved, thereby achieving the intended purpose.

  That is, when the fan beam-shaped X-ray spreading direction and the arrangement direction of the elements of the X-ray line sensor are inclined at a predetermined angle equal to the direction perpendicular to the conveyance direction of the inspection object, the direction orthogonal to the conveyance direction The number of elements that contribute to imaging a certain dimension of the inspection object on the head increases (see FIGS. 2A and 2B), for example, the elements of the X-ray line sensor with respect to the direction orthogonal to the transport direction Is tilted by θ, the element pitch in the direction orthogonal to the transport direction is substantially reduced by cos θ times, and the resolution is improved accordingly.

  Further, as in the invention according to claim 2, if a configuration is adopted in which the inclination angle of the X-ray spread direction on the fan beam and the conveying direction of the arrangement direction of the elements of the X-ray line sensor can be arbitrarily changed, According to the dimension (width dimension) of the inspection object in the direction orthogonal to the transport direction, it is possible to set almost all elements to participate in imaging, and according to the width dimension of the inspection object. As long as the resolution can be improved.

  According to the present invention, the X-ray transmission is performed by inclining the fan beam-shaped X-ray spreading direction and the X-ray line sensor element arrangement direction at a predetermined angle with respect to the direction orthogonal to the conveyance direction of the inspection object. Since the information is collected, even if X-ray line sensors having the same pitch between elements are used, the resolution is improved as compared with the conventional X-ray foreign substance inspection apparatus of this type and finer foreign substances can be detected.

  In addition, as in the invention according to claim 2, if the angle of the X-ray spreading direction and the X-ray line sensor with respect to the conveyance direction of the inspection object is variable, By setting the angle so that almost all of the effective width contributes to imaging, X-ray transmission information can be detected with high efficiency by making the best use of the effective width, and X with the highest possible resolution. The line transmission information can be obtained, and the foreign substance detection sensitivity can be further improved. By adopting this configuration, there is an advantage that the life of the X-ray line sensor can be improved.

  That is, when the size of the inspection object is small, in this type of conventional X-ray foreign matter inspection apparatus, X-rays are always directly applied to elements in the region that hardly contributes to imaging within the effective width of the X-ray line sensor. If the angle is set so that almost all of the effective width of the X-ray line sensor contributes to imaging by adopting the configuration of the invention according to claim 2, almost all the elements are applied. X-rays that have passed through the inspection object are incident, and as a result, there are almost no elements that are always directly exposed to X-rays, so that the lifetime can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration.

  An X-ray line sensor 2 is disposed below and opposed to the X-ray generator 1, and a belt conveyor 3 is provided therebetween. The X-ray generator 1 outputs the X-rays generated from the X-ray source 1a in the form of a fan beam by passing it through the slit 1b in the same manner as the conventional one. 3, the fan beam-shaped X-ray spreading direction is inclined by θ with respect to the direction R perpendicular to the inspection object W conveyance direction. Is set to

  In addition, the X-ray line sensor 2 is also set so that the arrangement direction of the elements is inclined by the same angle θ with respect to the direction R perpendicular to the conveyance direction of the inspection object W. The output of the X-ray line sensor 2 is subjected to various processes such as offset processing and sensitivity correction in the same manner as in the past, and then taken into the image processing apparatus 4 equivalent to the conventional one. The presence or absence of is determined. Further, as in the conventional case, when it is determined that foreign matter is mixed, a drive control signal is supplied to an exclusion device (not shown) provided on the downstream side in the transport direction to exclude the article.

  The image processing apparatus 4 is connected to an operation unit 5 for giving various settings and commands, a TV monitor 6 for displaying an X-ray fluoroscopic image of the inspection object W after image processing, and the like. . The required area including the X-ray generator 1 and the X-ray line sensor 2 is accommodated in a protective box as in the conventional apparatus.

  In the embodiment of the present invention described above, the belt conveyor 3 is driven to convey the inspection object W, and the fan beam-shaped X-rays from the X-ray generator 1 are irradiated, and the transmitted X-rays are converted into X-ray lines. When detected by the sensor 2, the X-ray transmission information of the inspection object W included in the output of the X-ray spread direction and the arrangement direction of the elements of the X-ray line sensor along the direction R orthogonal to the transport direction. The resolution in the direction R is greatly improved as compared with the conventional apparatus that sets

  That is, as shown in a plan view in FIG. 2A, in the embodiment of the present invention in which the X-ray line sensor 2 and the X-ray spreading direction are inclined by θ with respect to the direction R orthogonal to the transport direction, As shown in FIG. 5B, the detection width is smaller than that in the case where the X-ray line sensor 2 and the X-ray spread direction are along the direction R, but it actually contributes to the imaging of the inspection object W. When the number of elements to be increased increases and the actual pitch between elements in the R direction is P, this is substantially equivalent to the case where a line sensor having a pitch of P cos θ is used. The resolution of the fluoroscopic image in the R direction is improved.

  Here, in the above embodiment, if the inclination angle θ with respect to the direction R orthogonal to the conveying direction of the slit 1b of the X-ray generator 1 and the X-ray line sensor 2 can be arbitrarily changed, FIG. ), (B), as shown in a schematic plan view of the main part, almost all elements of the X-ray line sensor 2 contribute to imaging of the inspection object W according to the size of the inspection object W in the R direction. By changing the angle to θ1 and θ2 so that the effective width of the X-ray line sensor 2 is maximized, the X-ray transmission information of the inspection object W can be obtained with as high a resolution as possible. Can be obtained.

  In this case, if the support plate 31 as shown in FIG. 1 is disposed along the conveyor belt 32 in the belt conveyor 3, it is necessary to form a square hole for transmitting X-rays to the support plate 31. However, this square hole also needs to be changed in accordance with the inclination angle θ of the X-ray line sensor 2. As an example of a mechanism for changing the angle of the square hole, as shown in FIG. 4 (A), a main part sectional view is shown, and in FIG. 4 (B), a main part plan view with the conveyor belt 32 removed is shown. A required portion of the plate 31 is rounded out, and a circular plate 33 having a square hole 33a is fitted into the cut-out portion, and the plate 31 is rotatably supported by a support portion 31a formed in the support plate 31. If an appropriate detent (not shown) is provided, the posture of the square hole 33a can be changed to an arbitrary angle.

  In addition, when θ is changed in accordance with the size of the inspection object W so as to make maximum use of the effective width of the X-ray line sensor 2 as described above, there is also an advantage that the life of the X-ray line sensor 2 is extended. is there. That is, when the X-ray line sensor 62 is set along the direction orthogonal to the transport direction as in the conventional apparatus shown in FIG. 5A, the element in the region indicated by N in the figure that does not contribute to the imaging of the inspection target W X-rays that do not pass through the inspection object W are always directly irradiated, and the deterioration of the elements in this region is accelerated, whereas the X-rays as in the embodiment of the present invention shown in FIG. If the arrangement angle is set so that almost all elements forming the effective width L of the line sensor 2 contribute to imaging, X-rays that have passed through the inspection object W are incident on almost all elements. As a result of removing the cause of the deterioration described above, the life of the X-ray line sensor 2 can be improved.

In the block diagram of embodiment of this invention, it is the figure which writes together and shows the schematic diagram showing a mechanical structure, and the block diagram showing an electric structure. It is explanatory drawing of the difference of effect | action of embodiment of this invention and a prior art example, (A) is a figure showing the element which contributes to the detection width and imaging of the X-ray line sensor 2 in embodiment of this invention, ( B) is a diagram showing the detection width of the X-ray line sensor 62 and elements contributing to imaging in the conventional apparatus. It is operation | movement explanatory drawing at the time of enabling change of the X-ray line sensor 2 and the angle of the X-ray spreading direction in embodiment of this invention. It is explanatory drawing of the example of the mechanism which changes the angle of the square hole 33a formed in the support plate 31 of the belt conveyor 3 required when changing (theta) arbitrarily in embodiment of this invention, (A) is. It is principal part sectional drawing, (B) is a principal part top view shown in the state which removed the conveyor belt 32. FIG. It is explanatory drawing of the difference in the method of X-ray incidence to each element of the X-ray line sensor of embodiment of this invention and a prior art example, (A) is a prior art example, (B) is implementation of this invention. It is a figure explaining each form. It is explanatory drawing of the structural example of the conventional X-ray foreign material inspection apparatus using a fan beam-shaped X-ray and an X-ray line sensor. FIG. 7 is an explanatory diagram of the effect of suppressing the leakage of X-rays by narrowing the X-rays in the apparatus of FIG. It is explanatory drawing of.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 X-ray generator 1a X-ray source 1b Slit 2 X-ray line sensor 3 Belt conveyor 31 Support plate 32 Conveyor belt 33 Disc 33a Square hole 4 Image processing device 5 Operation part 6 TV monitor W Inspection object

Claims (2)

An X-ray generator that outputs X-rays focused in a fan beam shape, and an X-ray generator that is disposed opposite to the X-ray generator and in the direction in which the X-rays spread so as to be incident on the X-rays from the X-ray generator An X-ray line sensor in which a plurality of elements are arranged, a transfer device that is provided between the X-ray generator and the X-ray line sensor, and transfers an inspection object in a predetermined direction intersecting the X-ray; In an X-ray foreign substance inspection apparatus provided with an image processing apparatus that determines the presence or absence of foreign substances in the fluoroscopic object by image processing using X-ray fluoroscopic image information of the inspection object based on the output of the X-ray line sensor,
X-rays characterized in that the X-ray spreading direction from the X-ray generation device and the arrangement direction of the elements of the X-ray line sensor are set at angles that are not orthogonal to the transport direction of the transport device, respectively. Foreign matter inspection device.   The angle with respect to the conveyance direction of the said conveying apparatus of the spreading direction of the X-ray from the said X-ray generator and the arrangement | sequence direction of the element of the said X-ray line sensor is changeable, respectively. X-ray foreign substance inspection device.

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