JPH09288071A - Foreign matter detector by x-rays - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently detect foreign matter by X-ray photographing, without matching the shape change position of an object to be inspected by the rotation or movement of an image, and being affected by the irregularity of the object to be inspected. SOLUTION: Radiation source voltage is altered while an X-ray source 1 alterable in photographing condition by the alteration of radiation source voltage, an X-ray source control device 2, an X-ray detector 4 detecting transmission quantity of X-rays transmitted through an object 12 to be inspected and an X-ray detector control device 5 are controlled by a photographing control unit 3. Two different X-ray images of the same object to be inspected are photographed under a condition capable of photographing both of the shape and foreign matter of the object to be inspected and a condition capable of photographing only the shape of the object to be inspected to be recorded by first and second image recording devices 6, 7. The relation between two X-ray images is preliminarily calculated on the basis of an object to be inspected free from foreign matter to be stored in an operation factor memory device 8 as an operation factor, and subtraction processing is performed by an operational processing apparatus 9 by using two X-ray images of the object 12 to be inspected and the previously calculated operation factor to detect foreign matter. The detection result is displayed on a display device 10 and recorded on a processing result recording apparatus 11.

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 detecting device, and a non-destructive inspection for foreign matter inspection in food such as canned food and ham, and tungsten entrainment during welding.
Alternatively, it can be applied to a nondestructive inspection of the internal structure of an electronic component or the like, in addition to the inspection of foreign matter contamination.

[0002]

2. Description of the Related Art FIG. 5 shows a block diagram of a conventional inspection apparatus.
In the figure, in the conventional inspection apparatus, the X-ray source 1 and the X-ray source 1
An X-ray source control device 19 for controlling the irradiation timing and time of the radiation source 1, an X-ray detector 4 and an X-ray detector control device 5 for controlling the X-ray detector 4, and an imaging control device 3 are further provided. The object 12 and the reference 20 on the table 13 while being controlled by
X-ray transmission images are captured for these two types of objects.
Details are as follows.

First, instead of the object 12, an object equivalent to the object having no abnormality is usually imaged as the reference 20, and the result (reference image) is recorded in the reference image storage device 21.

Next, under the same conditions as when the reference 20 was photographed,
The subject 12 is photographed and the result (inspection image) is recorded in the inspection image storage device 22.

Basically, the imaging conditions of the object 12 and the reference 20 are matched. Therefore, the same X
Using the same X-ray detector 4 as the X-ray source 1 and making the distance between the X-ray source 1 and the X-ray detector 4 and the operating conditions of the X-ray source 1 and X-ray detector 4 the same, see 20 Then, the subject 12 is imaged in order.

Next, the respective image storage devices 22 and 21
The arithmetic processing unit 9 performs arithmetic processing for subtracting the reference image from the inspection image recorded in 1., the processing result is output and displayed on the display unit 10, and is recorded and stored in the processing result recording unit 11.

Here, since the reference image basically represents the distribution of X-ray transmission in a state in which there is no abnormality, the reference image is subtracted from the inspection image in which the presence or absence of abnormality is unknown, so that X-ray transmission is performed. Anomalies can be detected by extracting ranges with different distributions.

That is, when there is an abnormality such as foreign matter mixed in the subject 12, the attenuation amount of X-rays passing through that portion increases or decreases depending on the type of foreign matter, so that X different from the case where there is no foreign matter. It appears as a change in the amount of line transmission (= luminance value of the image).

However, even in a portion where the shape of the subject is not uniform and the thickness is changed, the X-ray transmission amount is different and the brightness value of the image is changed. It cannot be discriminated whether or not the change in luminance is due to the change in shape of the subject 12.

Therefore, by photographing an object (= reference 20) similar to the object without foreign matter, etc., the object 12
The luminance change due to the shape change is previously obtained as a reference image, and the reference image is subtracted from the inspection image to extract only the abnormal portion due to the inclusion of foreign matter.

Therefore, the subject 12 and the reference 20 need to be photographed by matching the positions of the shape changes, or they must be aligned in the arithmetic processing.

The X-ray detector 4 corresponds to a detection device such as an image intensifier or a X-ray camera which uses a phosphor that emits visible light when it is hit by X-rays.

[0013]

However, in the conventional inspection apparatus for detecting a foreign substance constructed as described above, the foreign substance detection performance can be changed by selecting "reference 20" which corresponds to the subject having no abnormality. Is greatly affected by the problem.

Further, when the contents of the test object 12 are not uniform, such as the canned product, and there is a large variation in the content among the individual test objects, what kind of object should be referred to as "reference 20".
However, even if it is selected as, the brightness change occurs due to the uneven distribution of the contents of the can, and such a brightness change is extracted by the subtraction process with the reference image, and is erroneously detected as a foreign substance.

Similarly, when there is a nail or a ripple for opening a container such as a can, when photographing at reference 20,
It is necessary to align the positions of the nails and the like shown in the image when the subject 12 to be inspected is photographed. If this position shifts, the brightness change due to this position shift will be extracted by the arithmetic processing of the inspection image and the reference image, and will be erroneously detected as a foreign substance, as in the case of the uneven content.

In particular, with respect to the brightness change caused by the positional deviation of the shape change of the subject, in order to match it, a method of rotating or moving the image of the photographed image so as to match the positions of the shape change is adopted. However, it is necessary to perform complicated signal processing that is not simple subtraction processing,
There are problems such as not completely matching, and a case where the brightness change portion due to a foreign substance is matched with the case in which the brightness is changed.

[0017]

In order to solve the above-mentioned problems, the present invention controls an X-ray source and this X-ray source as an X-ray foreign matter detection device that is not affected by variations in the subject. An X-ray source control device, an X-ray detector that detects the amount of X-rays that are emitted from the X-ray source and that passes through a subject, and an X-ray detector control device that controls the X-ray detector, While controlling the X-ray source control device and the X-ray detector control device, a first imaging condition capable of imaging both the shape of the subject and the foreign matter for the same subject, and sufficient brightness for the foreign matter. However, the shape of the subject is an imaging control device that captures two X-ray images under a second imaging condition that allows imaging with a certain level of brightness, and a first image obtained under the first imaging condition. An image storage device for recording a second image obtained under the second shooting condition; A calculation coefficient storage device that stores, as calculation coefficients, the relationship between the first and second images of the object having no object, which have different imaging conditions, and the first image and the second image of the object to be inspected. And an arithmetic processing unit that performs a subtraction process using the above arithmetic coefficient to detect a foreign substance.

Further, as a means for changing the photographing condition, for example, the X-ray source controller has a circuit in which at least one of a source voltage and a source current supplied to the X-ray source is variable, and the photographing is performed. The controller controls the X-ray source controller to change at least one of the source voltage and the source current, thereby changing the imaging conditions and capturing the two X-ray images, the first image and the second image. Or a moving mechanism for changing the distance between the X-ray source and the X-ray detector, wherein the moving mechanism is controlled by the imaging control device and the X-ray source is used. By changing the distance to the X-ray detector, the X-ray images of the first image and the second image are picked up by changing the shooting conditions, or a filter for X-rays is used. , This filter in front of the X-ray source A first image and a second image by changing the imaging condition by providing a filter insertion device to and from the X-ray detector, and controlling the filter insertion device by the imaging control device to move the filter in and out. Two
It is characterized in that one X-ray image is taken.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In an X-ray foreign matter detection apparatus having such a configuration, the X-ray source and the X-ray detector are controlled by the imaging control apparatus through the X-ray source control apparatus and the X-ray detector control apparatus, respectively. An X-ray image of the subject is captured by the imaging control device, for example, by controlling the X-ray source control device to change at least one of the source voltage and the source current supplied to the X-ray source. Alternatively, the moving mechanism is controlled to change the distance between the X-ray source and the X-ray detector, or the filter insertion device is controlled to move the filter between the X-ray source and the X-ray detector. By adjusting the above, the same subject can be imaged by changing the imaging conditions into the first imaging condition and the second imaging condition. This makes it possible to obtain two types of X-ray images, the first image and the second image, in the state where the shape change and the like are present at the same place, and the alignment of the shape change and the like are unnecessary.

As the first image, X-ray imaging is performed under the first imaging condition capable of imaging both the shape of the subject and the foreign matter, and the foreign matter and the like which may be mixed into the subject and the contents of the subject. The brightness difference and the shape change due to the deviation and the like are both obtained and recorded in the image recording apparatus, for example, the first image recording apparatus.

As the second image, it is possible to capture only the shape of the subject as much as possible, but sufficient brightness cannot be obtained for foreign matter, but the shape of the subject can be imaged with a certain degree of brightness. By performing X-ray imaging with, the foreign matter or the like that may be mixed into the subject can be obtained with the lowest possible brightness, and the deviation or shape change of the contents of the subject can be obtained with the highest possible brightness change. The image is recorded in the second image recording device.

Prior to the actual inspection, the first image and the second image are photographed in advance using an object in which it is clear that no foreign matter is mixed, and the obtained first image and second image are used. ,
The calculation coefficient is calculated so that the result obtained by multiplying and subtracting the calculation coefficient from the first image and the second image becomes 0 (zero) and stored in the calculation coefficient storage device.

Next, in the actual inspection, the first image and the second image are photographed with respect to the subject whose presence / absence of foreign matter is unknown, and the first calculation and the second image obtained are subjected to the above calculation. The arithmetic processing unit performs subtraction processing using the arithmetic coefficients stored in the coefficient storage unit, and only the change in luminance due to the mixed foreign matter is extracted to determine the presence or absence of the foreign matter. If necessary, the result is output and displayed on the display device, and the result is recorded and stored in the processing result recording device.

As described above, by using the first image and the second image of the same subject obtained by changing the imaging conditions for the arithmetic processing, the variation of each subject is eliminated between the two images. The effect of can be removed, and erroneous detection is less likely to occur.

As a method for obtaining the calculation coefficient from the two X-ray images of the subject free from foreign matter, the above-mentioned "first image and second image are multiplied by the calculation coefficient and subtracted is 0 (zero)".
Since the calculation coefficient "
There are several methods depending on the way of thinking.

As one of the methods, if two images are simply referred to as an image and an image, the value of the same pixel (x, y) of these two images is “image (x, y), image (x, y). y) ”, there is a method of obtaining the coefficient (x, y) for each pixel as in the following formula (1). Alternatively, there is a method of averaging the coefficients calculated for each pixel in the entire image to obtain one coefficient as in the following formula (2).
There is a method in which the vertical and horizontal directions of an image are regarded as an array and the coefficients are also calculated as an array. In the latter method of considering image data as an array, the image array is represented as “array: A”, the image array is represented as “array: B”, and the coefficient array is represented as “array: K”. "Array: A" and "Array: B" as in the formula
The coefficient array K is obtained from the inverse matrix of

[0027]

[Equation 1] coefficient (x, y) = image (x, y) / image (x, y) (1)

[0028]

## EQU00002 ## Coefficient = [. SIGMA. {Image (x, y) / image (x, y)}] / N equation (2) where N is the number of pixels of the image.

[0029]

## EQU00003 ## Array: K = (array: A) .times. (Array: inverse matrix of B) ... Equation (3)

Further, the subtraction process between two images is expressed by the following equation (4).

[0031]

## EQU00004 ## Subtraction processing result image = image-image * calculation coefficient ... Equation (3)

Next, the X-ray foreign matter detecting apparatus according to the present invention will be described with reference to a specific embodiment shown in the drawings.

FIG. 1 shows an example of the configuration of an X-ray foreign matter detection device according to the present invention. The foreign matter detection device of this example includes an X-ray source 1 and an X-ray source control device 2 whose imaging conditions can be changed. X-ray detector 4 for detecting the amount of X-rays transmitted through the subject 12
And the X-ray detector control device 5 and controlling these,
Imaging in which two different X-ray images are captured for the same subject under the first imaging condition in which both the shape of the subject and foreign matter can be imaged and the first imaging condition in which only the shape of the subject is imaged The control device 3, the first and second image recording devices 6 and 7 for recording the two obtained X-ray images, and the relationship between these two X-ray images are previously obtained in a subject free from foreign matter. A calculation coefficient storage device 8 for storing the calculated calculation coefficient, a calculation processing device 9 for performing a subtraction process on the two X-ray images of the subject to be inspected with the calculation coefficient previously obtained, and detecting a foreign matter; And a processing result recording device 11 that records the detection result. The subject 12 is installed on the table 13.

The X-ray source 1 is controlled by an X-ray source controller 2 having a variable circuit of a source voltage and a source current for generating X-rays in addition to a control function of X-ray irradiation timing and time. The imaging conditions of the X-ray source 1 can be changed.
For example, by increasing the source voltage, the energy of the generated X-rays can be increased, and the X-rays can easily pass through the subject 12. Therefore, for example, due to the magnitude of the energy of X-rays, the first imaging condition that allows both the shape of the subject and the foreign matter to be photographed for the same subject, and sufficient luminance for the foreign matter cannot be obtained. The shape of can be set by selecting a second shooting condition that allows shooting with a certain brightness.

The X-ray detector 4 detects the amount of X-rays emitted from the X-ray source 1 and transmitted through the subject 12.
By the control of the line detector control device 5, an image in which the intensity distribution of the X-rays transmitted through the subject 12 is used as the brightness value of brightness is obtained.

The imaging controller 3 controls the X-ray source controller 2 to change the source voltage and the like to control the imaging conditions and the like of the X-ray source 1, and controls the X-ray detector 4 and the X-ray detector. By controlling the device 5, an X-ray image in which the intensity distribution of the X-rays transmitted through the subject 12 is used as the brightness value of the brightness is captured under different imaging conditions, and the first image is recorded in the first image storage device 6. However, the second image is recorded in the second image storage device 7.

Before actually carrying out the inspection, a first radiographing in which both the shape and the foreign matter of the subject described above can be photographed by the control of the photographing control device 3 by using the subject in which the foreign matter is not mixed in advance. The condition and the foreign object does not have sufficient brightness, but the shape of the subject is the second imaging condition that allows imaging with a certain brightness, and two X-ray images with different imaging conditions are taken.
The first image and the second image are stored in the first and second image storage devices 6,
Record at 7. Here, using the obtained first image and second image, in the arithmetic processing unit 9, the relationship between these two images is used as the arithmetic coefficient for the subtraction process by the method of the equations 1 to 3 described above. Obtained and recorded in the calculation coefficient storage device 8.

Next, regarding the subject 12 which is actually inspected for the presence of foreign matter, similarly, the first photographing condition capable of photographing both the shape of the subject and the foreign matter and sufficient brightness for the foreign matter are obtained. However, the shape of the subject is a second imaging condition that allows imaging with a certain level of brightness, and two X-ray images with different imaging conditions are taken under the control of the imaging control device 3, and the first image and the second image are taken. The data is recorded in the first and second image storage devices 6 and 7.
This time, using the stored first image and second image and the calculation coefficient stored in the previous calculation coefficient storage device 8, the subtraction processing of these two images is performed by the above-described equation (4). The calculation processing device 9 is used to obtain the image of the subtraction processing result.

As shown in FIG. 2, when there is a shading due to the inclusion of foreign matter or the like other than the shape change, if the subtraction process between the first image 14 and the second image 15 is performed using the above calculation coefficient,
In the calculation processing result image 16, only the inclusion of foreign matter or the like is emphasized and extracted.

When the grayscale is extracted in the subtraction processing result image 16, the arithmetic processing unit 9 determines that the foreign matter is mixed in the subject 12 and outputs the determination result to the display unit 10 to display it. The result is recorded and stored in the result recording device 11.

From these, the presence / absence of foreign matter in the subject 12 is determined, which is extremely useful as a real-time X-ray foreign matter detecting apparatus.

Next, FIG. 3 and FIG. 4 are block diagrams of different constitutional examples of the X-ray foreign matter detecting apparatus according to the present invention. The X-ray foreign matter detecting apparatus shown in FIG. , Basically, only the method of changing the shooting condition is different.

In the example of FIG. 3, the moving conditions for moving the X-ray source 1 are not changed by changing the source line voltage or the like by the X-ray source control device which is the control device of the X-ray source 1 in the example. 17, the X-ray source moving mechanism 17 is controlled by the imaging control device 3 through the X-ray source control device 19 to move the X-ray source 1 in the vertical direction in the drawing, and the X-ray source 1 and the subject 12 And the imaging conditions are changed by changing the distance from the X-ray detector 4. That is, even if the X-ray energy generated by the X-ray source 1 is constant, the fact that the X-ray transmission intensity changes when the distance between the X-ray source 1 and the subject 12 and the X-ray detector 4 changes is used. Then, the imaging conditions are changed to obtain the first and second images for the same subject. Processing of the obtained first image and second image is performed in the same manner as in the X-ray foreign matter detection apparatus shown in FIG.

In the example of FIG. 4, the filter 18 such as a thin iron plate is used.
A, this filter 18A, the object 12 and the X-ray detector 4
And a filter insertion device 18 to be inserted between the X-ray detector 4 and the subject 12 and the X-ray detector 4 by controlling the filter insertion device 18 with the imaging control device 3. Alternatively, the shooting condition is changed by changing the insertion degree. That is, even if the sensitivity of the X-ray detector 4 itself is constant, the fact that the X-ray detection sensitivity is equivalently lowered by the insertion of the filter 18A is used to change the imaging conditions and As a result, the first and second images are obtained. Processing of the obtained first image and second image is performed in the same manner as in the X-ray foreign matter detection apparatus shown in FIG.

As a modification of FIG. 3, the X-ray source moving mechanism 17 is used.
Instead of the above, a moving mechanism (not shown) for moving the X-ray detector 4 is used, and the X-ray detector moving mechanism is controlled by the imaging controller 3 through the X-ray detector controller 5 to control the X-ray detector 4.
X-ray source 1 by moving the
The imaging conditions are changed by changing the distance between the subject 12 and the X-ray detector 4. Also in this case, the X-ray source 1, the subject 12 and the X
Since the X-ray transmission intensity changes according to the change in the distance from the line detector 4, the imaging conditions can be changed.

As a modification of FIG. 4, although not shown, the filter 18A is inserted between the X-ray source 1 and the subject 12. Also in this case, the X-ray detection sensitivity is equivalently changed depending on whether the filter 18A is inserted, and the imaging condition can be changed.

In connection with the example of FIG. 4, instead of using the filter 18A, the sensitivity of the X-ray detector 4 itself can be changed, and the X-ray detector is controlled by the imaging controller 3 through the X-ray detector controller 5. The photographing condition may be changed by electrically changing the sensitivity of 4 itself.

Further, by changing the radiation source voltage or the like, the X-ray energy generated by the X-ray source 1 is changed to change the photographing conditions, the photographing condition changing means of FIG. 1, the X-ray source 1 or the X-rays. 3 for changing the imaging condition by moving the detector 4 and its modified example of the imaging condition changing means, FIG. 4 for changing the imaging condition by inserting and removing the filter 18A and its modified example of the imaging condition changing means, and X-ray detection. A configuration may be used in which any of a plurality of means for electrically changing the sensitivity of the device 4 itself to change the shooting condition is used to change the shooting condition.

[0049]

As described above, the foreign matter detecting device using X-rays according to the present invention has the following effects (1) to (3). (1) Even if there is a variation in each subject, two X-ray images of the same subject with different imaging conditions are imaged and the subtraction processing is performed, so there is an advantage that the above variation does not affect the processing result. (2) Similarly, since the light and shade of the X-ray image due to the shape change of the subject and the like basically appear at the same place in two X-ray images with different imaging conditions for the same subject, the conventional There is no need for processing or restrictions for matching the position where the shape change exists between the subject and the reference. (3) Since only the change in the brightness of the X-ray image (= the change in the X-ray transmission amount) due to the inclusion of foreign matter can be extracted, the efficiency of foreign matter detection is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first example of a foreign matter inspection apparatus using X-rays according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing subtraction processing between images according to the present invention.

FIG. 3 is a block diagram showing a configuration of a second example of the foreign matter inspection apparatus using X-rays according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a third example of the foreign matter inspection apparatus using X-rays according to the embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional foreign matter inspection device.

[Explanation of symbols]

 1 X-ray source 2 X-ray source control device (source voltage and source current variable circuit) 3 Imaging control device 4 X-ray detector 5 X-ray detector control device 6 First image storage device 7 Second image storage device 8 Arithmetic coefficient storage device 9 Arithmetic processing device 10 Display device 11 Processing result recording device 12 Subject 13 units 14 First image 15 Second image 16 Arithmetic processing result image 17 X-ray source moving mechanism 18 Filter insertion device 18A filter 19 X-ray source Control device

Claims (4)

[Claims] 1. An X-ray source, an X-ray source control device for controlling the X-ray source, and an X-ray detector for detecting the amount of X-rays emitted from the X-ray source and transmitted through a subject. While controlling the X-ray detector controller controlling the X-ray detector, the X-ray source controller and the X-ray detector controller, the shape of the subject and the foreign matter with respect to the same subject Two X-ray images can be taken under the first imaging condition in which both of the two can be imaged and the second imaging condition in which the shape of the subject can be imaged with a certain level of brightness, although sufficient brightness cannot be obtained for foreign matter. The image capturing control device that performs the image capturing, the image storage device that records the first image obtained under the first image capturing condition and the second image obtained under the second image capturing condition, and these image capturing conditions for a subject free of foreign matter in advance are different. A calculation coefficient storage device that stores the relationship between the first and second images as a calculation coefficient When foreign matter detecting device according to X-rays, characterized in that it is constituted by a processing unit for detecting a foreign object performs subtraction processing by the calculation coefficient of the first image and the second image for the subject to be examined first. 2. The X-ray source control device has a circuit in which at least one of a source voltage and a source current supplied to the X-ray source is variable, and the imaging control device includes the X-ray source control device. By controlling and changing at least one of the source voltage and the source current, the X-ray images of the first image and the second image are imaged under different imaging conditions. Item 1. An X-ray foreign matter detection device according to item 1. 3. A moving mechanism for changing the distance between the X-ray source and the X-ray detector, wherein the imaging control device controls the moving mechanism to cause the X-ray source and the X-ray detector to move. The X-ray foreign matter detection device according to claim 1, wherein the X-ray image capturing apparatus is configured to capture the two X-ray images of the first image and the second image by changing the imaging condition by changing the distance. 4. An X-ray filter, and a filter insertion device for inserting and removing the filter between the X-ray source and the X-ray detector, wherein the imaging control device controls the filter insertion device. The foreign matter detection device by X-rays according to claim 1, wherein the X-ray image capturing apparatus includes a first image and a second image, which are two X-ray images, by changing the imaging conditions by moving the filter in and out.