JP7231530B2 - X-ray inspection device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an X-ray inspection apparatus that irradiates X-rays onto a conveyed object to be inspected and inspects for defective seal portions of the object by using an X-ray transmission image obtained when the X-rays are irradiated.

An X-ray inspection apparatus is an apparatus that inspects raw meat, fish, processed food, medicine, etc., for example, and inspects the inspection object using X-ray transmission images when the inspection object is irradiated with X-rays. conventionally known as

As an X-ray inspection apparatus of this type, for example, an X-ray inspection apparatus disclosed in Patent Document 1 below extracts an outline from a transmission image when an object to be inspected is irradiated with X-rays, and extracts the extracted outline. Using this as a reference, the seal area of the object to be inspected is calculated based on preset seal information, and inspection for defective seals is performed using the calculated density level of the image of the seal area.

JP 2005-024549 A

By the way, an object to be inspected by this type of X-ray inspection apparatus is, for example, an object to be inspected in which two opposite sides of a package containing contents are sealed. For this type of inspection object, for example, the contents are housed in a cylindrical belt-shaped package at regular intervals, and the package parts at both ends of each content are sealed by thermocompression bonding, and then the sealed parts are cut and individually packaged. The object to be inspected is inspected for contamination by foreign matter, defective seals, and the like.

In particular, when a lightweight object is transported as an object to be inspected, or when an object to be inspected is transported at high speed to improve the yield, for example, the posture changes due to the transfer between conveyors, and the inspection device's conveyor may move. The direction of the seal side at the time changes randomly and the posture is not stable. For this reason, in the X-ray inspection apparatus of Patent Document 1 described above, for an object to be inspected that is transported in an unstable manner due to random changes in the direction of the seal side, the outline extracted from the transmission image is used as a reference to preset There is a problem that the seal area cannot be calculated and specified based on the obtained seal area information.

Therefore, the present invention has been made in view of the above-mentioned problems, and is an X-ray inspection capable of specifying and inspecting the seal area even if the inspected object is brought in with the sealing direction changed at random. The purpose is to provide a device.

In order to achieve the above object, an X-ray inspection apparatus according to claim 1 of the present invention conveys, at predetermined intervals, inspection objects W in which two opposite sides of a package containing contents are sealed. while irradiating X-rays, and using an X-ray image obtained by detecting the X-rays transmitted through the object to be inspected, the X-ray inspection apparatus 1 inspecting the presence or absence of sealing defects in the object to be inspected, ,
a sealing direction setting means 5a for setting a sealing direction indicating whether the two sealed sides are in the longitudinal direction or the lateral direction of the object to be inspected;
an outline area extracting means 12 for extracting an outline area of the object to be inspected in the X-ray image;
a seal side specifying means 13 for specifying a seal side along which the object to be inspected is sealed based on the outer shape area and the seal direction;
a seal area calculation means 14 for calculating a seal area up to a predetermined length inside the identified seal side;
and a sealing portion defect determination means 15 for determining whether or not there is a sealing defect in the sealing portion region .

The X-ray inspection apparatus according to claim 2 is the X-ray inspection apparatus according to claim 1,
The seal side identifying means 13 is characterized in that the side corresponding to the sealing direction of the contour area is identified as the seal side.

The X-ray inspection apparatus according to claim 3 is the X-ray inspection apparatus according to claim 1,
The seal side identifying means 13 is characterized in that a side of the contour area that intersects a straight line passing through the center of gravity parallel to the side corresponding to the seal direction of the circumscribed rectangle of the contour area is identified as the seal side.

The X-ray inspection apparatus according to claim 4 is the X-ray inspection apparatus according to claim 1,
The seal side identifying means 13 is characterized in that a side of the contour area that intersects an axis corresponding to the sealing direction of the circumscribed circle of the contour area is identified as the seal side.

ADVANTAGE OF THE INVENTION According to this invention, even if it carries in to the conveyer of an inspection apparatus with a random sealing direction, a seal part area|region can be reliably specified and an inspection can be performed.

1 is a block diagram showing a schematic configuration of an X-ray inspection apparatus according to the present invention; FIG. FIG. 10 is an explanatory diagram showing an example of a method of specifying a seal portion region of an inspection object having a seal in the lateral direction; 3 is a flow chart of a method for identifying the seal area of FIG. 2; FIG. 10 is an explanatory diagram showing an example of a method of identifying a seal portion region of an object to be inspected that has a seal in the longitudinal direction; 5 is a flow chart of a method for identifying the seal region of FIG. 4; FIG. 10 is an explanatory diagram showing another example of a method of specifying a seal portion region of an object to be inspected that has a seal in the longitudinal direction; 7 is a flow chart of a method for identifying the seal area of FIG. 6;

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail, referring attached drawings.

The X-ray inspection apparatus according to the present invention is incorporated in, for example, a part of a transport line, irradiates X-rays while sequentially transporting an object to be inspected at regular intervals, and detects the X-rays transmitted through the object to be inspected. The obtained X-ray image is used to inspect the presence or absence of defects in the seal portion of the object to be inspected.

In the X-ray inspection apparatus according to the present invention, an object to be inspected in which two opposing sides of a package containing contents are sealed is the object of inspection. For this type of inspection object, for example, the contents are housed in a cylindrical belt-shaped package at regular intervals, and the package parts at both ends of each content are sealed by thermocompression bonding, and then the sealed parts are cut and individually packaged. The object to be inspected is inspected for contamination by foreign matter, defective seals, and the like.

As shown in FIG. 1, the X-ray inspection apparatus 1 of this embodiment includes a carrier device 2, an X-ray generator 3, an X-ray detector 4, a setting input unit 5, a signal processing unit 6, and a display unit 7. It is roughly composed of

The conveying device 2 sequentially conveys the objects W to be inspected to be inspected on the conveying path at predetermined intervals, and is composed of, for example, a belt conveyor arranged horizontally with respect to the apparatus main body.

A belt conveyor 2 as a conveying device includes a conveying belt 2a made of a material (an element other than an element having a large atomic weight) that easily transmits X-rays. The conveying belt 2a is driven at the conveying speed preset by the setting input unit 5 by rotating the driving motor M based on the control of . As a result, the inspected object W carried in from the carry-in port is transported in the transport direction X in FIG. 1 toward the carry-out port side.

The X-ray generator 3 irradiates X-rays on the object W to be inspected which is transported on the transport path in the transport direction X from the inlet to the outlet. It has a cylindrical X-ray tube for generating X-rays by colliding with it, and an irradiation slit for irradiating the X-rays generated by the X-ray tube toward the X-ray detector 4 .

The X-ray tube has, for example, a configuration in which a cylindrical X-ray tube provided inside a metal box is immersed in insulating oil. Generate. The X-ray tube is provided so that its longitudinal direction is perpendicular to the conveying direction of the object W to be inspected (the X direction in FIG. 1), and directs the generated X-rays toward the X-ray detector 4 below. , the irradiation slit along the longitudinal direction screen-like irradiation.

The X-ray detector 4 has a plurality of elements arranged in a straight line in a direction orthogonal to the transport direction X on a plane in the transport direction X of the inspected object W being transported. More specifically, the X-ray detector 4 is configured in an array including a plurality of photodiodes arranged in a line and scintillators provided on the line-shaped photodiodes.

The X-ray detector 4 detects X-rays passing through the inspection object W and the conveyor belt 2a with a plurality of elements (photodiode and scintillator arrays), and the detected detection data is divided into the number of elements for each element. The lines are sequentially output to the signal processing unit 6 as one line, and the sequential output is repeated as the object W to be inspected is conveyed.

The setting input unit 5 is composed of, for example, keys, push buttons, switches, soft keys on the display screen of the display unit 7, etc. provided on the main body of the apparatus, and includes a sealing direction setting means 5a and a sealing width setting means 5b.

The seal direction setting means 5a sets the seal direction indicating whether the seal is in the longitudinal direction or the lateral direction of the object W to be inspected.

The seal width setting means 5b uses the seal side of the object to be inspected W as a reference and sets the length from the seal side to the inner side by a predetermined length as the seal width.

The signal processing unit 6 specifies the seal area of the object W to be inspected based on the binarized image obtained by binarizing the transmission image of X-rays passing through the object W to be inspected and the setting information from the setting input unit 5, It determines whether or not there is a seal defect in the seal area, and as shown in FIG. 15.

The storage means 11 stores the X-ray transmission data for each inspected object W from the X-ray detector 4 . X-ray transmission data is obtained by A/D converting an electric signal from the X-ray detector 4 by an A/D converter (not shown). More specifically, each time an object W to be inspected is inspected, the storage means 11 stores, for example, several hundred X-ray transmission data per line (Y direction) of the X-ray detector 4 at least. A predetermined number of lines (for example, several hundred lines) corresponding to the length of the object W to be inspected in the conveying direction (corresponding to the detection period from the front end to the rear end) is stored.

The outline area extracting means 12 extracts an entire transmission image (including the object W and the belt surface) having a density level corresponding to a grayscale value that is lighter as the amount of transmission increases from the X-ray transmission data stored in the storage means 11. image) is created, and a transmission image having a density level equal to or higher than the threshold value set in the setting input unit 5 is extracted as the outer shape area of the object W from the created whole transmission image.

The sealing side identifying means 13 identifies the sealing side along which the object W is sealed based on the contour area extracted by the contour area extracting means 12 and the sealing direction set by the sealing direction setting means 5a. do.

More specifically, if the outline area extracted by the outline area extraction means 12 is a rectangle as shown in FIG. is identified as the seal edge.

If the contour area extracted by the contour area extraction means 12 has a shape in which the opposing long sides are recessed inward as shown in FIG. A side of the contour region that intersects a straight line passing through the center of gravity parallel to the side corresponding to the sealing direction of the circumscribed rectangle is specified as a sealing side.

If the contour area extracted by the contour area extraction means 12 has a shape in which the opposing long sides are recessed inward as shown in FIG. A side of the contour area that intersects the axis corresponding to the sealing direction of the circumscribed circle of is specified as a sealing side.

The circumscribing rectangle can be obtained from the outline of the outline area as the smallest rectangular area surrounding a set of points forming this outline. That is, each point of the outline area is the starting point, and the area of the circumscribing rectangular area is sequentially calculated when the line connecting the starting point and the next point is the X axis, and the minimum rectangular area becomes the circumscribing rectangle.

Using the moment of the binary image, the direction (principal axis) in which the outline area extends is obtained, and from the coordinate system with this principal axis as the X axis, the maximum value minus the minimum value of the x and y coordinates becomes the width and height. Alternatively, the circumscribing quadrilateral of the outline area may be obtained as the circumscribing rectangle.

In image processing, the moment of the binarized image can be used to obtain the center of gravity and the inclination of the contour area.

In general, the moment represents the magnitude of the force that rotates an object, but it can also be used as a statistic of an image for feature extraction. A moment feature of a binary image is a numerical value obtained by weighting and summing pixel positions.

The image moment is generally calculated using the (p+q)th order moment M(p,q) defined by the following equation (1).

where f _ij is the pixel value, 1 for the target pixel and 0 for the background outside the target. When determining the barycentric coordinates (I, J), I=M(1,0)/M(0,0) and J=M(0,1)/M(0,0) are used. That is, the center of gravity is obtained using the 1st order moment (however, the area is the 0th order moment).

Note that the barycentric coordinates (I, J) using the first-order moment are: I = first-order moment in the i-direction/0th-order moment (sum of coordinate positions in the i-direction/area), J = first-order moment in the j-direction/ 0th order moment (sum of coordinate positions in the j direction/area).

tan θ, which indicates the direction of the principal axis, represents the direction in which the target image extends, and is calculated by the following equation (2) using the secondary moment and the synergistic moment. However, M(2,0)=secondary moment in the i-direction, M(0,2)=secondary moment in the j-direction, and M(1,1)=multiplicative moment.

The seal area calculating means 14 calculates the seal area based on the seal side specified by the seal side specifying means 13 and the seal width set by the seal width setting means 5b. That is, the seal portion area calculation means 14 uses the seal side specified by the seal side specifying means 13 as a reference, and calculates the area from the seal side to the inside by the seal width set by the seal width setting means 5b. Calculate as area.

The sealing portion defect determining means 15 determines whether or not there is a sealing defect within the sealing portion area calculated by the sealing portion area calculating means 14 . That is, for the seal area specified by the seal area calculation means 14, a threshold larger than the threshold for extracting the outline area, for example, is used as the information for judging whether the seal is defective, which is set by the setting input unit 5. Whether or not there is a density level exceeding this threshold within the seal area determines whether there is a defect in the seal.

The display unit 7 is composed of a display device such as a liquid crystal display, for example, and displays an entire image of the object W to be inspected, an X-ray transmitted image of the object W to be inspected W based on the determination result, and "OK" or "NG". The inspection results such as the quality judgment result, the total number of inspections, the number of non-defective products, the total number of NG, etc. are displayed on the display screen based on the operation of the setting input unit 5.

Next, specific examples (examples 1, 2, and 3) of a method for identifying the seal region using the X-ray inspection apparatus 1 configured as described above will be described.

[Example 1] . , and both lateral sides are sealed. FIG. 2(a) shows an X-ray image of the object W to be inspected when the long side of the object W to be inspected is carried in parallel to the transport direction X. FIG. In this X-ray image, the corner P3 of the four corners P1, P2, P3, and P4 is the origin, and the coordinates of each corner P1, P2, P3, and P4 are P1: (0, Y), P2: (X, Y ), P3: (0, 0), and P4: (X, 0).

Now, as shown in FIG. 2(b), in the X-ray image of the inspection object W which is carried in at an angle from the state shown in FIG. Among them, let A be the highest vertex, and let B, C, and D be the vertices in the counterclockwise direction. Also, the x coordinate of vertex B is 0, the y coordinate of vertex C is 0, and the coordinates of vertices A, B, C, and D are A: (x1, y1), B: (0, y2), C: ( x3, 0), D: (x4, y4).

First, as shown in FIG. 2(b), an outline area is extracted from an X-ray image of an object to be inspected which is carried in at an angle (ST1). This contour region is determined by extracting a transmission image having a density level equal to or higher than the threshold value set in the setting input unit 5 from the X-ray image (entire transmission image) of the object W to be inspected.

Next, as shown in FIG. 2(c), the side in the same direction as the transverse direction of the X-ray image of the object to be inspected W is defined as a reference straight line L1, and the two sides adjacent to this reference straight line L1 are defined as seal sides. Identify (ST2).

Then, as shown in FIG. 2(d), an area of a predetermined length (S1) inside the outline area from the specified two seal sides is calculated as the seal portion area S (ST3).

[Example 2] . Both sides in the longitudinal direction are sealed in a state in which both sides in the transverse direction are recessed inward due to the thickness of the contents. FIG. 4(a) shows an X-ray image of the object W to be inspected when the short side of the object W to be inspected is carried in parallel to the transport direction X. FIG. In this X-ray image, the corner P3 of the four corners P1, P2, P3, and P4 is the origin, and the coordinates of each corner P1, P2, P3, and P4 are P1: (0, Y), P2: (X, Y ), P3: (0, 0), and P4: (X, 0).

Now, as shown in FIG. 4(b), in the X-ray image of the inspection object W which is carried in at an angle from the state shown in FIG. Among them, let A be the highest vertex, and let B, C, and D be the vertices in the counterclockwise direction. Also, the x coordinate of vertex B is 0, the y coordinate of vertex C is 0, and the coordinates of vertices A, B, C, and D are A: (x1, y1), B: (0, y2), C: ( x3, 0), D: (x4, y4).

First, as shown in FIG. 4(b), an outline region is extracted from an X-ray image of an object to be inspected which is carried in at an angle (ST11). This contour region is determined by extracting a transmission image having a density level equal to or higher than the threshold value set in the setting input unit 5 from the X-ray image (entire transmission image) of the object W to be inspected. Then, a circumscribing rectangle of the extracted outline area is generated (ST12). This circumscribing rectangle is generated, for example, from the contour of the outline region as the smallest rectangular region surrounding a set of points forming this contour, as described above.

Next, as shown in FIG. 4(c), the center of gravity G of the generated circumscribing rectangle is calculated (ST13), and a straight line parallel to the side passing through the center of gravity G in the same direction as the longitudinal direction is defined as a reference straight line L2. A side where the straight line L2 intersects is specified as a seal side (ST14).

Then, as shown in FIG. 4(d), an area of a predetermined length (S1) inside the outline area from the identified seal side is calculated as the seal area S (ST15).

[Example 3] . The contents are accommodated, and both sides in the longitudinal direction are sealed in a state in which both sides in the width direction are recessed inward due to the thickness of the contents. FIG. 6(a) shows an X-ray image of the object W to be inspected when the short side of the object W to be inspected is carried in parallel to the transport direction X. FIG. In this X-ray image, the corner P3 of the four corners P1, P2, P3, and P4 is the origin, and the coordinates of each corner P1, P2, P3, and P4 are P1: (0, Y), P2: (X, Y ), P3: (0, 0), and P4: (X, 0).

Now, as shown in FIG. 6(b), in the X-ray image of the inspection object W which is carried in at an angle from the state shown in FIG. Among them, let A be the highest vertex, and let B, C, and D be the vertices in the counterclockwise direction. Also, the x coordinate of vertex B is 0, the y coordinate of vertex C is 0, and the coordinates of vertices A, B, C, and D are A: (x1, y1), B: (0, y2), C: ( x3, 0), D: (x4, y4).

First, as shown in FIG. 6(b), an outline area is extracted from the X-ray image of the object W to be inspected which is carried in at an angle (ST21). This contour region is determined by extracting a transmission image having a density level equal to or higher than the threshold value set in the setting input unit 5 from the X-ray image (entire transmission image) of the object W to be inspected. Then, a circumscribed circle of the extracted outline area is generated (ST22).

Next, as shown in FIG. 6C, the center of gravity G of the generated circumscribed circle (ellipse) is calculated (ST23). A side where the straight line L3 intersects is specified as a seal side (ST24).

Then, as shown in FIG. 6(d), an area of a predetermined length (S1) inside the outline area from the identified seal side is calculated as the seal area S (ST25).

As described above, according to the present embodiment, the seal direction is set to indicate whether the seal is in the longitudinal direction or the lateral direction of the object to be inspected, and the outline region of the object to be inspected in the X-ray image is extracted and extracted. The seal side along which the object to be inspected is sealed is specified based on the outer shape area and the seal direction, and the presence or absence of a seal defect is determined within the seal portion area up to a predetermined length inside the specified seal side as a reference. Even if the seal direction is randomly carried into the conveyer of the inspection device, the seal area can be reliably specified and inspected.

Further, in this embodiment, even if the package is deformed by the contents to be filled, the sealing side becomes a straight line. If the side of the contour area that intersects with the The seal side can be identified even if it is not recessed and becomes a straight line.

Although the best mode of the X-ray inspection apparatus according to the present invention has been described above, the present invention is not limited by the description and drawings according to this mode. In other words, other forms, embodiments, operation techniques, etc. made by those skilled in the art based on this form are all included in the scope of the present invention.

1 X-ray inspection device 2 Conveying device 2a Conveyor belt 3 X-ray generator 4 X-ray detector 5 Setting input unit 5a Seal direction setting means 5b Seal width setting means 6 Signal processing unit 7 Display unit 11 Storage means 12 Outline area extraction means REFERENCE SIGNS LIST 13 seal side identification means 14 seal area calculation means 15 seal defect determination means W object to be inspected S seal area S1 seal width L1, L2, L3 reference straight line G center of gravity

Claims (4)

X-rays are irradiated while conveying an inspection object (W) in which two opposite sides of a package containing contents are sealed at predetermined intervals, and the X-rays transmitted through the inspection object are detected. An X-ray inspection apparatus (1) for inspecting the presence or absence of sealing defects in the inspected object using the obtained X-ray image,
a sealing direction setting means (5a) for setting a sealing direction indicating whether the two sealed sides are in the longitudinal direction or the lateral direction of the object to be inspected;
an outline area extracting means (12) for extracting an outline area of the object to be inspected in the X-ray image;
a seal side specifying means (13) for specifying a seal side along which the object to be inspected is sealed based on the outline area and the seal direction;
a seal area calculation means (14) for calculating a seal area up to a predetermined length inside the identified seal side;
An X-ray inspection apparatus, further comprising a sealing portion defect determining means (15) for determining whether or not there is a sealing defect within the sealing portion region . 2. The X-ray inspection apparatus according to claim 1, wherein said seal side specifying means (13) specifies a side of said contour area corresponding to said sealing direction as a seal side. The seal side specifying means (13) specifies, as the seal side, a side of the outer shape area that intersects a straight line passing through the center of gravity parallel to the side corresponding to the sealing direction of the circumscribed rectangle of the outer shape area. An X-ray inspection apparatus according to claim 1. 2. The X according to claim 1, wherein the seal side specifying means (13) specifies, as the seal side, a side of the outer shape area that intersects an axis corresponding to the sealing direction of the circumscribed circle of the outer shape area. Line inspection equipment.

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