JPH10132762A - X-ray foreign matter inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray foreign matter inspection apparatus, which can inspect a foreign matter without being influenced by the shape of an object to be inspected or the foreign matter. SOLUTION: Data of a solid shape of an object 10 to be inspected are obtained by a solid shape-measuring means 2. The amount of X rays passing the object to be inspected is obtained by an X-ray data-measuring means 4. A correlation of the solid shape data at the same level as the object to be inspected and X-ray data is operated by a correlation-operating means 41. If no foreign matter is present in the object to be inspected, the solid shape data and X-ray data have the correlation with respect to an outer shape, and, therefore, an operation result indicating the presence of the correlation is obtained from the correlation-operating means 41. If the object to be inspected includes a foreign matter, the solid shape data and X-ray data have the correlation of the outer shape, but do not have the correlation with respect to the foreign matter. As a result, the correlation-operating means 41 outputs an operation result representing the absence of the correlation. The foreign matter in the object to be inspected is inspected in this manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray foreign matter inspection apparatus for inspecting foreign matter in an inspection object by detecting transmitted X-rays.

[0002]

2. Description of the Related Art Foreign matter inspection using an X-ray inspection apparatus has been conventionally performed in various fields. X-ray foreign matter inspection device is X
This is an apparatus that irradiates an object to be measured with X-rays from a radiation source and inspects a foreign substance contained in the object to be inspected by a transmission image obtained by the X-ray transmitted through the object to be measured. As a result, it is possible to inspect foreign substances contained in foods and medicines, and to perform a process of removing an inspection object containing foreign substances.

In a conventional X-ray foreign matter inspection apparatus, an X-ray transmitted through an object to be measured is imaged by an X-ray line sensor, and X-ray data obtained by the X-ray data processing is subjected to signal processing such as threshold processing and difference processing. Foreign material inspection.

[0004]

The signal processing of the foreign matter inspection performed in the conventional X-ray foreign matter inspection apparatus has a problem that it is difficult to perform a sufficient inspection depending on the shape of the inspection object or the foreign matter. FIG. 7 is a diagram for explaining signal processing of a foreign substance inspection performed by a conventional X-ray foreign substance inspection apparatus. FIG.
(A) schematically shows the cross-sectional shape of the inspection object and foreign substances A and B contained in the inspection object. When such an object is irradiated with X-rays to detect transmitted X-rays,
X-ray data as shown in FIG. 7B is obtained. FIG.
In (b), a and b are X-ray data obtained from foreign substances A and B.

[0005] subjected to a threshold processing by the threshold L ₁ with respect to the X-ray data, foreign object detection signal is obtained as shown in FIG. 7 (c), the signal c, d are shown to be foreign matter I have. However, although signal c indicates foreign object A, signal d
Is due to the shape of the inspection object, and no foreign matter B is detected. Further, a difference value is obtained from the X-ray data (FIG. 7D), and a threshold value process is performed on the difference value to obtain a foreign object detection signal shown in FIG. 7E or FIG. 7F. can get. FIG. 7 (e) is a foreign object detection signal when the thresholds and L _2, the signal k represents the detection of the foreign matter A, foreign body B is not detected because the shape change is small. FIG. 7 (f) a foreign object detection signal when the thresholds and L _3, the signal m, although n represents one end of the foreign object A and B, not detected at the other end of the foreign body B, Further, an erroneous signal o occurs due to the shape of the inspection object.

Therefore, the present invention solves the above-mentioned problems of the conventional X-ray foreign substance inspection apparatus, and provides an X-ray foreign substance inspection apparatus capable of performing a foreign substance inspection without being affected by the shape of an inspection object or a foreign substance. The purpose is to provide.

[0007]

An X-ray foreign matter inspection apparatus according to the present invention obtains two data, that is, three-dimensional shape data of an object to be inspected and X-ray data by transmitted X-rays, and obtains a correlation between the two data. Inspection of foreign substances in the inspection object is performed. The three-dimensional shape data includes only data on the outer shape of the inspection object,
The X-ray data includes both data on the external shape of the inspection object and data on the shape of the foreign matter. When the three-dimensional shape data and the X-ray data are compared at the same position on the two-dimensional object to be inspected, there is a correlation between the two data for the external shape of the inspected object, and a correlation between the two data for the foreign matter. There is no.

[0008] The X-ray foreign matter inspection apparatus of the present invention utilizes the above relationship, and does not perform signal processing using only X-ray data.
By detecting the correlation between the X-ray data and the three-dimensional shape data, a foreign substance in the inspection object is detected, thereby performing a foreign substance inspection irrespective of the shape of the inspection object or the foreign substance.

Therefore, an X-ray foreign matter inspection apparatus according to the present invention is an X-ray foreign matter inspection apparatus for inspecting an object to be inspected using transmitted X-rays. X-ray data measuring means for measuring the transmitted X-ray dose transmitted through the inspection object and obtaining X-ray data;
At the same two-dimensional position of the inspection object, a configuration is provided that includes correlation calculation means for calculating a correlation between the three-dimensional shape data and the X-ray data, and the correlation obtained by the correlation calculation means is used. Foreign matter contained in the inspection object is detected.

According to the present invention, the three-dimensional shape data of the inspected object is obtained by the three-dimensional shape measuring means, and the transmitted X-ray dose transmitted through the inspected object is obtained by the X-ray data measuring means. Since the signal form such as the signal level differs between the transmitted X-ray dose value and the three-dimensional shape data, it is necessary to match the signal forms in order to obtain a correlation between the two data. Therefore,
In the X-ray data measuring means or the correlation calculating means, the transmitted X-ray dose is converted into a signal form corresponding to the calculation of the correlation by signal processing. Therefore, when the signal conversion is performed by the X-ray data measurement unit, the X-ray data output by the X-ray data measurement unit is the signal after the signal conversion, and when the signal conversion is performed by the correlation calculation unit, Is the X-ray data output from the X-ray data measuring means before the signal conversion.

The correlation calculating means calculates and obtains a correlation between the three-dimensional shape data and the X-ray data at the same plane position of the inspection object. When there is no foreign substance in the object to be inspected, since the three-dimensional shape data and the X-ray data have a correlation in the outer shape, a calculation result indicating that there is a correlation is obtained from the correlation calculation means. On the other hand, when a foreign substance is present in the inspection object, the three-dimensional shape data and the X-ray data have a correlation with respect to the external shape, but there is no correlation with the foreign substance. An operation result indicating that there is no data is obtained. Therefore, it can be determined from the calculation result of the correlation calculating means whether or not a foreign substance exists in the inspection object.

The correlation calculating means according to the first embodiment of the present invention calculates a sum of squares or a square root of the difference between the three-dimensional shape data and the X-ray data for each predetermined area, and calculates the calculated value and a threshold value. This makes it possible to detect a foreign substance for each predetermined area. The size of the predetermined area is a factor that determines the resolution of the foreign substance detection, and the smaller the area is, the more the correlation is obtained, the smaller the foreign substance can be detected.

In a second embodiment of the present invention, the correlation calculating means calculates the sum of the square of the difference or the square root of the pixel data of the three-dimensional shape data and the X-ray data for each predetermined number of pixels.
This is a means for obtaining the data while shifting the pixels, and comparing the calculated value with a threshold value.

A three-dimensional shape measuring means according to a third embodiment of the present invention comprises a laser irradiator and a video camera, and captures laser light radiated on an object to be inspected by a video camera to obtain three-dimensional shape data. Can be requested.

An X-ray data measuring means according to a fourth embodiment of the present invention includes an X-ray source and an X-ray line sensor arranged on both sides of an object to be inspected, and detects X-rays from the X-ray source. The X-ray line sensor detects transmitted X-rays that irradiate the inspection object and pass through the inspection object.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram for explaining the outline of an X-ray foreign matter inspection apparatus according to the present invention. In the schematic block diagram of FIG.
A three-dimensional shape measuring means 2 for measuring three-dimensional shape data of the object 10; an X-ray data measuring means 3 for measuring the transmitted X-ray dose transmitted through the object 10 to obtain X-ray data; At the same two-dimensional position of
The apparatus includes a foreign matter detection processing unit 4 including a correlation calculating unit 41 for calculating a correlation with line data. Further, the X-ray foreign matter inspection apparatus 1 is provided with an elimination unit 5 for eliminating an inspection object 10 containing foreign matter based on a foreign matter detection signal from the foreign matter detection processing unit 4, a three-dimensional shape data, an X-ray data, and a correlation signal. And the like.

The three-dimensional shape measuring means 2 includes a laser irradiator 21 for irradiating the inspection object 10 with laser light, and a video camera 22 for imaging the laser light reflected on the surface of the inspection object 10.
A shape measurement control unit 24 that controls the laser irradiator 21 and the video camera 22 and obtains an image signal by taking in an image signal from the video camera 22;
The belt 23 is provided to perform a zero movement. Shape measurement control unit 2
Reference numeral 4 denotes a position at which the inspection object 10 is moved by the belt 23 and an image signal. The shape image processing unit 25 generates shape data using the image signal and stores the shape data in the shape image storage unit 26. Note that the input movement position is at least the inspection object 1.
It is intended to obtain the relationship between the position of the inspection object 10 in the moving direction and the shape data, including the leading position of 0.

The X-ray data measuring device 3 includes an X-ray source 31 and an X-ray
The X-ray line sensor 32 is disposed opposite to the belt 33 and the X-ray imaging controller 34 controls the X-ray line sensor 32.
Is controlled to perform imaging of the inspection object 10 using transmitted X-rays. The X-ray image processing unit 35 performs image processing on the captured transmitted X-ray to generate X-ray data.

The foreign substance detection processing unit 4 includes a correlation calculating unit 41
And input the shape data from the three-dimensional shape measuring means 2, the X-ray data and the moving position of the inspection object 10 from the X-ray data measurement means 3, and input the shape data and the X-ray at the same plane position of the inspection object 10. Find the data correlation. The correlation calculation unit 41 includes an image reading unit 42, which reads shape data corresponding to the moving position of the inspection object 10 from the shape image storage unit 26, and inputs shape data at the same plane position as the X-ray data. . The elimination means 5 includes a belt 5
3 and an exclusion control unit 54 for controlling the exclusion unit 51, and according to a foreign object detection signal output from the foreign object detection processing unit 4, the corresponding inspection object 10 is excluded.

The display means 6 includes a display control unit 61 and a display device 62, and displays the external shape of the inspection object 10 by using the shape data stored in the shape image storage unit 26. The transmitted X-ray image of the inspection object 10 is displayed by using the X-ray data from the image processing unit 35, and the foreign matter of the inspection object 10 is displayed by using the correlation signal from the correlation calculating unit 41. can do.

One configuration example of the optical system of the three-dimensional shape measuring means will be described with reference to FIGS. FIG. 2 is a diagram illustrating a configuration example of the laser irradiator 21 and the video camera 22. In FIG. 2, the inspection object 10 is disposed on a belt 23 and is moved by a driving mechanism (not shown). When the inspection object 10 is irradiated with laser light from the laser irradiator 21, a beam line 27 is formed on the surface of the inspection object 10 according to the uneven shape of the inspection object 10. The video camera 22 captures the beam line 27 two-dimensionally to form an image signal. FIG. 3 is an example of an image signal. The reflection line 29 represents the outer shape of the cross-sectional shape of the inspection object 10. P1 and P2 at both ends correspond to both ends of the belt 23 in FIG. The starting point. Then, image signals are sequentially formed with the movement of the belt 23 and stored in the shape image storage unit 26 in FIG.
0 shape data can be stored in a data form of a plurality of cross-sectional shape data.

Next, the operation of the X-ray foreign matter inspection apparatus of the present invention will be described with reference to the flowchart of FIG. 4 and FIG. The inspection object 10 moving on the belt 23 is irradiated with the laser light of the laser irradiator 21, and the reflected light is reflected on the video camera 2.
2, the image data is input to the shape measurement control unit 24 (step S1). The shape image processing unit 25 obtains data in the height direction of the inspection object 10 from the image data, generates shape data of the inspection object 10 (step S2), and stores the shape data in the shape image storage unit 26. . The above-described processing is sequentially performed in accordance with the movement of the inspection object 10, so that all the shape data of the inspection object is obtained and stored in the shape image storage unit 26 (step S3).

When the inspection object 10 passes through the belt 23,
Next, the inspection object 10 is the belt 3 of the X-ray data measurement unit 3.
3 starts the movement. The X-ray line sensor 32 is
The transmitted X-ray is detected for each line as the inspection object 10 moves, and the X-ray image processing unit 35 performs image processing on the detected transmitted X-ray detection signal to generate X-ray data. The correlation calculating means 41 outputs the X-rays for one line from the X-ray image processing unit 35.
The line data is input (step S4), and the shape data at the same movement direction position as the X-ray data is read from the shape image storage unit 26. The alignment of the X-ray data and the shape data is performed, for example, by inputting a position signal of the belt 33 to detect the position of the inspection object 10 on the belt 33,
The shape data can be read from the shape image storage unit 26 by the image reading unit 42 using the position information as an address (step S5).

The correlation calculating means 41 calculates and calculates the correlation between the input X-ray data and the shape data (step S6), and compares the obtained data with a previously determined threshold to determine the presence or absence of the correlation. (Step S
7). In the determination of the correlation, if there is a correlation between the X-ray data and the shape data, since there is no foreign substance in the inspection object 10, the process returns to step S4 and the same applies to the X-ray data of the next line. Is performed. In the determination of the correlation, if there is no correlation between the X-ray data and the shape data, it is determined that there is a foreign substance in the inspection object 10 and the foreign substance is detected and displayed (Step S).
8). By performing the above processing up to the end of the inspection object 10, the inspection of the foreign matter in the inspection object 10 is completed (step S9).

Next, the correlation calculation will be described with reference to FIGS. In FIG. 5, the reflection line 29 is detected by the optical system, and the shape data a for each movement position of the inspection object is stored in the shape image storage unit. On the other hand, the X-ray line sensor 32 detects transmitted X-rays to obtain X-ray data b,
Further, X-ray data c in which a signal form is combined with the shape data a is formed. The correlation calculation processing (d) finds a correlation between the shape data a and the X-ray data c, and the calculation result is output as a foreign matter shape signal e.

FIG. 6 is a calculation example of the correlation calculation processing (d). In this calculation example, the shape data a and the X-ray data c are data values A1, A2,.
, B1, B2,... Here, as an arithmetic expression for calculating the correlation between the two data, C = Σ ((An−Bn) ² + (An + 1−Bn + 1) ² + ·
.. + (An + m−Bn + m) ² ), and the above C is calculated using m successive data.
Is calculated while changing n. When there is a correlation between the data A and the data B, the value of C approaches zero except for the noise component, and when there is no correlation, it becomes a value corresponding to the degree of decorrelation. Therefore, the correlation can be determined by comparing the value of C with a predetermined value expected to be formed by the noise component as a threshold value.

In the detection of foreign matter by the determination of the correlation using the above arithmetic expression, the resolution can be determined according to the number of m, and the smaller the m, the smaller the foreign matter can be detected.

FIG. 6 shows a case where a correlation is obtained using two consecutive data, where n is 2, in the above equation. For example, correlation data C1 uses the data A1, A2, and data B1, B2, can be expressed by the following ^{equation, C1 = (A1 -B1) 2} + (A2 -B2) 2 The correlation The data C2 can be expressed by the following equation using the data A2 and A3 and the data B2 and B3. C2 = if included the signal due to foreign matter in ^{(A2 -B2) 2 + (A3} -B3) 2 X -ray data B3,
C3 exceeds the threshold and can be output as a foreign matter detection signal e. The arithmetic processing method for obtaining the correlation is not limited to the above processing, but can be performed using another method.

[0029]

As described above, according to the X-ray foreign matter inspection apparatus of the present invention, foreign matter inspection can be performed without being affected by the shape of the inspection object or foreign matter.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically illustrating an X-ray foreign matter inspection apparatus according to the present invention.

FIG. 2 is a diagram illustrating an example of a configuration of an optical system of a three-dimensional shape measuring unit according to the present invention.

FIG. 3 is a diagram for explaining shape data by a three-dimensional shape measuring unit according to the present invention.

FIG. 4 is a flowchart for explaining the operation of the X-ray foreign substance inspection device of the present invention.

FIG. 5 is a diagram for explaining a calculation of a correlation according to the present invention.

FIG. 6 is a diagram for explaining a calculation of a correlation according to the present invention.

FIG. 7 is a diagram for explaining signal processing of a foreign substance inspection performed by a conventional X-ray foreign substance inspection apparatus.

[Explanation of Signs] 1. X-ray foreign matter inspection device, 2 .... three-dimensional shape measuring means, 3. X
Line data measurement means, 4 ... foreign matter detection processing unit, 5 ... exclusion means, 6 ... display means, 10 ... inspection object, 11 ... foreign matter, 21
... Laser irradiator, 22 ... Video camera, 23, 33, 5
3 ... belt, 24 ... shape measurement control unit, 25 ... shape image processing unit, 26 ... shape image storage unit, 27 ... beam line, 2
8: Base line, 29: Reflection line, 31: X-ray source,
32 X-ray line sensor, 34 X-ray imaging control unit, 35
.. X-ray image processing unit, 41 correlation calculation means, 42 image reading unit, 51 exclusion unit, 54 exclusion control unit, 61 display control unit, 62 display device.

Claims (1)

[Claims] 1. An X-ray foreign matter inspection apparatus for inspecting foreign matter on an object using transmitted X-rays, a three-dimensional shape measuring means for measuring three-dimensional shape data of the object, and a transmitted X-ray amount transmitted through the object. X-ray data measuring means for measuring and obtaining X-ray data, and correlation calculating means for calculating a correlation between the three-dimensional shape data and the X-ray data at the same two-dimensional position of the inspection object. An X-ray foreign matter inspection apparatus for detecting foreign matter contained in the inspection object from the correlation.