JP2011085424A - X-ray inspection method and x-ray inspection device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an highly-reliable X-ray inspection device which properly inspects the length in a predetermined direction, bering a characteristic value, of an object to be inspected, regardless of the direction or inclination of the object to be inspected. <P>SOLUTION: The extraction part 23 of the X-ray inspection device has a reference direction calculation part 231 for calculating the reference direction of the image region (inspection region) of the inspection target contained in the X-ray image sent from an image processing part 22, an inspection direction forming part 232 for forming one or a plurality of directions, which is rotated by predetermined angle from the reference direction calculated in the reference direction calculation part 231, as an inspection direction and a length calculation part 233 for extracting the length of the inspection region in the inspection direction formed in the inspection direction forming part 232 as feature quantity. Since the direction for performing inspection is determined on the basis of the reference direction in the extraction part 23, the length in each direction of the inspection target can be properly calculated regardless of the inclination of the inspection target. As a result, X-ray inspection of high reliability can be performed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an X-ray inspection apparatus that performs inspection such as defect inspection on an article to be inspected (hereinafter referred to as “inspected object”) using a feature amount obtained from an X-ray image.

  An X-ray inspection device is a device that non-destructively inspects the interior of an article by irradiating the article with X-rays, measuring the amount of X-ray transmission with an X-ray detector, and creating an X-ray image based on the X-ray detector. is there. For example, foreign matter contamination inspection for inspecting whether foreign matter is not mixed in the contents of the packaged product, number inspection for inspecting whether the content has a predetermined number, cracks in the content, etc. There is a defect inspection for inspecting whether or not a defect has occurred. These inspections are performed on various articles such as food, pharmaceuticals, and industrial parts.

  X-ray inspection apparatuses are roughly classified into two types: X-ray fluoroscopy apparatuses and X-ray CT (Computed Tomography) apparatuses. Among these, the X-ray fluoroscopic apparatus obtains an X-ray transmission image by fixing the X-ray irradiation source and the X-ray detector, whereas the X-ray CT apparatus sets the X-ray irradiation source and the X-ray detector to be inspected. The X-ray transmission amount data measured in each direction is reconstructed by Fourier transform to obtain a tomographic image of the internal structure.

  Since the X-ray fluoroscopy device has an X-ray irradiation source and an X-ray detector fixed, the amount of information is less than that of the X-ray CT device, but the inspection object can be quickly inspected. Yes. Therefore, it is frequently used for continuous inspection of articles continuously conveyed by a belt conveyor or the like. For example, Patent Document 1 describes an X-ray inspection apparatus in which an X-ray irradiator is disposed (fixed) above a conveyor and an X-ray line sensor is disposed below (fixed). In the X-ray inspection apparatus disclosed in Patent Document 1, X-rays radiated in a fan shape from an X-ray irradiator above a conveyor are detected by an X-ray line sensor below the conveyor, whereby the object that has been conveyed on the conveyor is detected. X-ray images of the inspection object can be sequentially generated. Furthermore, it is possible to continuously inspect the inspection object by extracting feature amounts such as length and width in the transport direction from the X-ray image and individually comparing each feature amount with a reference value (allowable range). it can.

JP 2006-098195 A

  In this type of continuous inspection, in general, the object to be inspected is merely placed on a conveyor and is not fixed in many cases. In such a case, the direction (posture) of the object to be inspected is different for each inspection. Therefore, if the length is calculated based on the transport direction, such as the length in the transport direction and its width (the length in the direction perpendicular to the transport direction), the value depends on the orientation of the test object even if the same object is inspected. As a result, the reliability of the inspection decreases.

  A problem to be solved by the present invention is to provide a highly reliable X-ray inspection apparatus capable of appropriately extracting a length in a predetermined direction (hereinafter referred to as “direction length”) as a feature amount. That is.

An X-ray inspection method according to the present invention made to solve the above problems is as follows:
An X-ray image is generated by irradiating the inspection object with X-rays and measuring the amount of transmission, and a predetermined feature amount is extracted from the X-ray image to determine whether the inspection object is good or bad. In the X-ray inspection method,
Calculate the reference direction of the object in the X-ray image,
One or more directions rotated by a predetermined angle from the reference direction are generated as inspection directions,
Extract the length of the inspection object in the inspection direction as a feature amount,
Compare the length with a predetermined allowable range to determine the quality of the inspection object,
It is characterized by that.

Further, an X-ray inspection apparatus according to the present invention made to solve the above problems is
An X-ray image is generated by irradiating the inspection object with X-rays and measuring the amount of transmission, and a predetermined feature amount is extracted from the X-ray image to determine whether the inspection object is good or bad. In X-ray inspection equipment,
A reference direction calculation means for calculating a reference direction of the inspection object shown in the X-ray image;
Inspection direction generation means for generating one or a plurality of directions rotated by a predetermined angle from the reference direction as an inspection direction;
A length calculating means for extracting the length of the inspection object in the inspection direction as a feature quantity;
Pass / fail judgment means for judging pass / fail of the object to be inspected by comparing the length with a predetermined allowable range;
It is characterized by having.

  The reference direction can be calculated according to various standards such as the inertia main axis, inertia sub axis, minimum ferret diameter direction, and maximum ferret diameter direction of the inspection object.

  In addition, X-ray images generated by these X-ray inspection methods or X-ray inspection apparatuses may have different vertical and horizontal expansion ratios depending on the conveyance speed and imaging settings. In such a case, it is desirable to calculate the inspection direction and the length of the inspection object in consideration of the vertical and horizontal expansion / contraction ratios.

  According to the X-ray inspection method and the X-ray inspection apparatus according to the present invention, the reference direction of the inspection object shown in the X-ray image is calculated, and the length of the direction rotated by a predetermined angle from the reference direction is characterized. Extract as a quantity. Accordingly, the direction length can be appropriately used as the feature amount regardless of the inclination of the object to be inspected, and it is possible to perform pass / fail determination with high reliability.

The block diagram which shows the structure of one Example of the X-ray inspection apparatus which concerns on this invention. The flowchart which shows the procedure of operation | movement of the X-ray inspection apparatus of a present Example. The figure which shows an example of the X-ray image produced | generated by the attachment defect inspection of the stapler. The figure which shows another example of the X-ray image produced | generated by the attachment defect inspection of the stapler. The figure which performed the binarization process to the X-ray image. The figure which showed the principal axis of inertia in each inspection area | region in an X-ray image, and the length in this inertial principal axis direction. The figure which shows an example of the X-ray image which displayed the length calculation direction and the range of the length. The block diagram which shows the structure of the modification of the X-ray inspection apparatus of a present Example.

  The calculation of the direction length in the conventional X-ray inspection method is often performed with respect to the length and width in the transport direction (the length in the direction orthogonal to the transport direction). This will be described by taking as an example the inspection of a staple (stabbler) attachment failure at the time of bookbinding shown in FIG. FIG. 3 is an X-ray image of a book with staples attached thereto, and staples stapled at two locations are inspection objects (inspected objects). Further, the inspected object 1 in the figure is a normally attached needle, and the inspected object 2 is a poorly attached needle.

  In the conventional X-ray inspection method, whether or not the inspected objects 1 and 2 are normal products and the length and width in the transport direction are included in a predetermined tolerance range that has been learned in advance by a preliminary experiment or the like. Judgment is made by whether or not. Since the inspected object 2 has the needle foot protruding outward, the length of the object 2 increases and deviates from the allowable range. Accordingly, the inspection object 2 is determined to be poorly attached.

  However, when the direction of the inspection object changes in the X-ray image, the length and width values in the transport direction vary. For example, the X-ray image shown in FIG. 4 is generated for the same object to be inspected as shown in FIG. 3. In the X-ray image of FIG. Is small and wide. As a result, each value deviates from the allowable range, and as a result, it is determined that the attachment is defective although it is normally attached.

  Therefore, in the X-ray inspection method and apparatus according to the present invention, first, a reference direction (reference direction) is calculated from the object to be inspected, and an inspection direction (inspection direction) is determined based on the reference direction. did. Thereby, the direction length of the inspection object can be appropriately calculated regardless of the inclination of the inspection object, and as a result, a highly reliable X-ray inspection can be performed. Hereinafter, an embodiment of the X-ray inspection method and apparatus of the present invention will be described.

  An embodiment of the X-ray inspection apparatus according to the present invention will be described with reference to FIGS. Here, FIG. 1 is a block diagram showing the configuration of the X-ray inspection apparatus of the present embodiment, and FIG. 2 is a flowchart showing the operation procedure of the X-ray inspection apparatus of the present embodiment.

  The X-ray inspection apparatus according to the present embodiment irradiates a normal product or an object to be inspected with X-rays and measures the amount of transmission, and the X-ray transmission based on the amount of X-ray transmission measured by the measurement unit 10. An inspection unit 20 that creates an image and extracts a predetermined feature amount, and a determination unit 30 that determines pass / fail of the inspection object based on an allowable range set in advance by user input, learning, or the like. Yes.

  The measurement unit 10 described above includes an X-ray irradiation unit 11 that emits X-rays from an X-ray source, and an X-ray detector that measures the X-ray transmission amount of a normal product or an inspection object irradiated with X-rays. And an X-ray detection unit 12 made up of, and the like. The inspection unit 20 includes an image generation unit 21 that generates X-ray images of the inspection object measured by the X-ray detection unit 12 and an X-ray image generated by the image generation unit 21. An image processing unit 22 that performs image processing on the image processing unit, and an extraction unit 23 that extracts a predetermined feature amount from the X-ray image subjected to image processing by the image processing unit 22.

  The above is a basic configuration generally common to the X-ray inspection apparatus, but the extraction unit 23 of the present embodiment further includes an image region of the inspection object included in the X-ray image sent from the image processing unit 22. A reference direction calculation unit 231 that calculates a reference direction (hereinafter referred to as “inspection area”), and one or more directions rotated by a predetermined angle from the reference direction calculated by the reference direction calculation unit 231 are inspection directions. And a length calculation unit 233 that calculates the length (direction length) of the inspection region in the inspection direction generated by the inspection direction generation unit 232.

  A plurality of inspection areas may be detected from one X-ray image. In this case, one reference direction calculated by the reference direction calculation unit 231 is obtained for each inspection region. In addition, the rotation angle from the reference direction used for the inspection direction generation unit 232 is set in advance by user input, preliminary experiments, or the like. Here, the rotation angle may be 0 °, that is, the inspection direction may coincide with the reference direction. Further, it may be 90 ° so that the inspection direction is orthogonal to the reference direction.

  The predetermined feature amount extracted by the extraction unit 23 may include known image feature amounts such as area, volume, perimeter length, and circularity in addition to the above-described direction length.

The procedure of the inspection of the X-ray inspection apparatus according to the present embodiment shown in FIG. 1 will be described with reference to the flowchart of FIG.
In the X-ray inspection apparatus of this embodiment, the inspection object is transported to a predetermined position (X-ray irradiation position) (Step S1), and the inspection object is irradiated with X-rays from the X-ray irradiation unit 11 (Step S1). S2), the amount of transmission is measured by the X-ray detector 12 (step S3). The X-ray transmission amount data measured by the X-ray detection unit 12 is sent to the image generation unit 21 in the inspection unit 20 to generate an X-ray image (step S4). However, the X-ray image generated by the image generation unit 21 includes not only the image of the object to be inspected but also the background image as shown in FIG. It is necessary to separate the image and the image of the inspection object. For the X-ray image of FIG. 2, for example, by binarization processing, it is possible to obtain a binary image in which the inspection area shown in FIG. 5 is black and the other areas appear white. The threshold for separating black and white may be set using a known automatic determination method such as a discriminant analysis method, or a value given in advance may be used. Further, an inspection area is detected by applying a labeling process to the binary image of FIG. 5 (step S5).

  Next, the extraction unit 23 extracts the length in the inspection direction of the inspection region detected by the image processing unit 22 as a feature amount. First, the reference direction calculation unit 231 calculates the reference direction for the inspection area detected by the image processing unit 22 (step S6). Here, as the reference direction, for example, any reference used in image processing such as an inertia main axis, an inertia sub axis, a minimum ferret diameter direction, and a maximum ferret diameter direction of the inspection region can be used. In this embodiment, the inertia main axis is used as the reference direction.

With respect to the reference direction calculated by the reference direction calculation unit 231, the inspection direction generation unit 232 generates a direction rotated by a predetermined angle from the reference direction as an inspection direction (step S7). Further, the length calculation unit 233 calculates the length of the inspection region in this inspection direction (step S8). In the present embodiment, the predetermined angle is set to 0 °, and the reference direction (principal axis of inertia) is used as the inspection direction to calculate the length (FIG. 6). Note that the x-ray image of FIG. 6 has the x-axis as the abscissa, the y-axis as the y-axis, the tilt angle of the reference direction from the x-axis as θ, and the predetermined angle as α. The direction length L in the inspection direction where the inclination angle is β (= θ + α) can be calculated by the following equation.
However, since α = 0 in the present embodiment, θ and β coincide with each other.

  The direction length value calculated by the length calculation unit 233 and other feature value values extracted by the extraction unit 23 are sent to the determination unit 30 and compared with a preset allowable range. If it is included in the allowable range, it is determined as a normal product, and if not included, it is determined as a defective product (defective product) (step S9).

  The above is the inspection procedure of the X-ray inspection apparatus of the present embodiment, such as the passage speed at the X-ray irradiation position of the inspection object conveyed by a conveyor or the like, the signal acquisition interval of the X-ray detector composed of a line sensor, etc. Depending on the settings of the X-ray inspection apparatus, the inspection object in the X-ray image may appear to expand and contract vertically and horizontally. In such a case, from the setting of the X-ray inspection apparatus, the calculation formula is corrected so that the vertical / horizontal expansion / contraction ratio is 1: 1, and the inspection direction and the length of the inspection object are calculated. A test similar to the method can be performed. In addition, before extracting the feature amount from the X-ray image, a step or a function unit (for example, a correction unit) for enlarging / reducing the X-ray image in each axial direction so that the vertical / horizontal expansion / contraction ratio becomes 1: 1. It may be provided.

  Moreover, the range of the inspection direction and the length of the direction may be displayed on a display unit including an output device such as a monitor so that the user can confirm that an appropriate inspection is being performed. FIG. 7 shows an example of an X-ray image displayed on the display unit. In the display example of FIG. 7, the inspection direction (coincidence with the reference direction) and the length of the direction are displayed by a line segment 3 with arrows added to both ends on the inspection region. The inclination of the line segment 3 indicates the inspection direction, and the length of the line segment 3 indicates the range of the length of the inspection region in the inspection direction. The line segment 3 may pass through any one of the center, the lower end, and the upper end of the inspection area. In addition, when there are a plurality of inspection directions and their lengths, it is possible to make it easier for the user to confirm by changing the display color of each.

  Note that the display example in FIG. 7 is merely an example, and any other display method can be used as long as the user can recognize the inspection direction and the range of the length thereof.

  FIG. 8 shows an X-ray inspection apparatus according to the above-described embodiment, in which a correction unit 40 that corrects the vertical / horizontal expansion / contraction ratio and a display unit 41 that displays the inspection direction and the range of the length in the direction are added. The block diagram of a line inspection apparatus is shown.

  In the X-ray inspection apparatus of this modification, the correction unit 40 calculates the vertical / horizontal expansion / contraction ratio of the X-ray image from the setting of the inspection apparatus so that the ratio of the expansion / contraction ratio is vertical: horizontal = 1: 1. The image can be enlarged or reduced in the vertical and horizontal directions. In addition, by providing the display unit 41, an X-ray image in which line segments and the like are displayed in the examination area is output to an output device such as a monitor so that the user can easily recognize the calculation direction and the range of the examination area length. be able to.

DESCRIPTION OF SYMBOLS 1, 2 ... Inspection object 3 ... Line segment 10 ... Measurement part 11 ... X-ray irradiation part 12 ... X-ray detection part 20 ... Inspection part 21 ... Image generation part 22 ... Image processing part 23 ... Extraction part 231 ... Reference | standard direction calculation Unit 232 ... Inspection direction generation unit 233 ... Length calculation unit 30 ... Determination unit 40 ... Correction unit 41 ... Display unit

Claims (12)

An X-ray image is generated by irradiating the inspection object with X-rays and measuring the amount of transmission, and a predetermined feature amount is extracted from the X-ray image to determine whether the inspection object is good or bad. In the X-ray inspection method,
Calculate the reference direction of the object in the X-ray image,
One or more directions rotated by a predetermined angle from the reference direction are generated as inspection directions,
Extract the length of the inspection object in the inspection direction as a feature amount,
Compare the length with a predetermined allowable range to determine the quality of the inspection object,
An X-ray inspection method characterized by the above.   The X-ray inspection method according to claim 1, wherein the reference direction is calculated by any one of an inertia main axis, an inertia auxiliary axis, a minimum ferret diameter direction, and a maximum ferret diameter direction of the inspection object.   The X-ray inspection method according to claim 1, wherein the inspection direction and length are calculated in consideration of a vertical / horizontal expansion / contraction ratio of the X-ray image.   The X-ray inspection method according to claim 1, wherein the X-ray image is an image after correction is performed so that a vertical and horizontal expansion ratio is 1: 1.   The X-ray inspection method according to claim 1, wherein the inspection direction is displayed in the X-ray image.   The X-ray inspection method according to claim 5, wherein a range of the length in the inspection direction is displayed in the X-ray image. An X-ray image is generated by irradiating the inspection object with X-rays and measuring the amount of transmission, and a predetermined feature amount is extracted from the X-ray image to determine whether the inspection object is good or bad. In X-ray inspection equipment,
A reference direction calculation means for calculating a reference direction of the inspection object shown in the X-ray image;
A length calculating means for calculating the length of the inspection object in the inspection direction, with one or a plurality of directions rotated by a predetermined angle from the reference direction as the inspection direction;
Pass / fail judgment means for judging pass / fail of the object to be inspected by comparing the length with a predetermined allowable range;
An X-ray inspection apparatus characterized by comprising:   The X-ray inspection apparatus according to claim 7, wherein the reference direction is calculated by any one of an inertia main axis, an inertia auxiliary axis, a minimum ferret diameter direction, and a maximum ferret diameter direction of the inspection object.   The X-ray inspection apparatus according to claim 7, wherein the inspection direction and length are calculated in consideration of a vertical and horizontal expansion / contraction ratio of the X-ray image.   The X-ray inspection apparatus according to claim 7, wherein the X-ray image is an image after correction is performed so that a vertical / horizontal expansion ratio is 1: 1.   The X-ray inspection apparatus according to claim 7, further comprising image display means for displaying the inspection direction in the X-ray image.   The X-ray inspection apparatus according to claim 11, wherein the image display unit displays a range of the length in the inspection direction in the X-ray image in addition to the inspection direction.