JP2000039407A - X-ray foreign object inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a foreign object being mixed into an object to be inspected that moves speedily by allowing X rays passing through the object to be inspected to reach a fluorescent plate and capturing the obtained transmission X-ray image with an image pick-up camera. SOLUTION: An object 2 to be inspected being placed on a belt conveyor 3 is successively carried and passes an inspection position part being provided at an X-ray generation source 1. The X-ray generation source 1 detects the timing of the passage of the inspection position of the object 2 to be inspected and applies X rays to the object 2 to be inspected. Application X rays successively pass through the object 2 to be inspected and the belt conveyor 3 and reach a fluorescent plate 4. In this case, when a foreign object is mixed into the object 2 to be inspected, transmission X rays have different amount of attenuation from the case when there are no foreign objects, and a foreign object is recognized in an X-ray perspective image appearing on the fluorescent plate 4. An X-ray transmission image appearing on the fluorescent plate 4 is reflected by a mirror 5 and is captured by an image pick-up camera 7. An image- processing device 8 where a video signal from the image pick-up camera 7 is inputted processes a signal, performs an operation for detecting the foreign object, and judges the presence or absence of the mixture of the foreign object.

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 automatically detecting foreign matter mixed in various products, for example, foods, medicines and the like by using X-rays.
More specifically, the present invention relates to an X-ray foreign matter inspection apparatus capable of detecting foreign matter with high accuracy while an object to be inspected is being conveyed at a high speed by a belt conveyor or the like.

[0002]

2. Description of the Related Art Products produced in the food and pharmaceutical industries are eaten and consumed or administered to the human body, and consequently, foreign substances are not allowed to enter the products. For this reason, conventionally, an inspection apparatus for detecting whether or not a foreign substance is mixed in a product in a nondestructive manner is installed in a production line of this type of product. Conventional inspection apparatuses mainly include an electromagnetic inspection method and an X-ray inspection method.

The electromagnetic inspection method detects electromagnetic changes due to foreign substances present in an inspection object.
It has the feature that the entire inspection apparatus can be configured at low cost, and is widely used not only in large-scale production lines but also in small- and medium-scale production lines. On the other hand, the inspection device using the X-ray detection method
An X-ray from an X-ray source is applied to an inspection object, the amount of X-ray transmitted therethrough is detected by an X-ray image sensor, and image processing is performed to detect foreign matter. Here, as the X-ray image sensor, a combination of a fluorescence intensifier and a television camera, an X-ray television camera, an X-ray line sensor, or the like is used.

[0004]

However, the electromagnetic inspection method has good detection accuracy when ferromagnetic metal foreign matter is mixed, but the foreign matter is a non-magnetic metal,
If it is a non-metal, there is a problem that the contamination cannot be detected or it cannot be detected with high accuracy. In addition, if the food contains a large amount of salt and water, as in seasoning foods, the food itself is converted into a conductor by electric field conduction. There were drawbacks. In addition, when an X-ray detection type inspection apparatus uses a fluorescent intensifier or an X-ray television camera, the exposure time of the camera or sensor must be long in order to obtain a clear image. When the inspection object is conveyed at high speed by a conveyor or the like,
There is a problem that foreign matter cannot be detected with high accuracy. Further, since the entire apparatus becomes expensive including the case of using an X-ray line sensor, it has not been adopted in a general production line.

[0005] Therefore, the problem to be solved by the present invention is:
An object of the present invention is to provide an inexpensive X-ray foreign substance inspection apparatus that employs an X-ray detection method and can accurately detect a foreign substance mixed in an inspection object that moves at a high speed.

[0006]

In order to achieve the above object, according to the present invention, an X-ray source for irradiating an inspection object with X-rays, and the inspection object is transported to a position where the X-rays are irradiated. Transporting means, a fluorescent plate which receives X-rays transmitted through the inspection object and converts a fluoroscopic image into a visible image, an imaging camera which captures the visible image obtained on the fluorescent plate and converts it into an electric signal, and this imaging camera Is an X-ray foreign matter inspection device including an image processing device that receives an electric signal from the device and performs image processing for foreign matter detection. In addition, a rotatable reflecting means for reflecting the visible image obtained on the fluorescent screen and giving it to the imaging camera, and a driving means for rotating the reflecting means in synchronization with the movement of the inspection object are provided. It is an X-ray foreign matter inspection device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing an example of an X-ray foreign matter inspection apparatus according to the present invention. In the figure, reference numeral 1 denotes an X-ray generation source, for example, a Coolidge tube or the like can be used so that irradiation of X-rays can be electrically controlled. An inspection object 2 is placed on a belt conveyor 3 and is continuously conveyed. In the middle of the belt conveyor 3, an X-ray source 1
Is installed, and X-rays can be irradiated to the inspection object 2 conveyed. Reference numeral 4 denotes a fluorescent plate, and the belt conveyor 3
Is installed so as to face the X-ray generation source 1 with the X-ray interposed therebetween, and converts an X-ray image transmitted through the inspection object 2 into a visible image.

[0008] Reference numeral 5 denotes a rotatable mirror (reflecting means) for reflecting a visible image appearing on the fluorescent screen 4. Here, an axis orthogonal to the conveying direction of the belt conveyor 3 is used as a rotation axis. The mirror 5 is configured to rotate about the rotation axis in synchronization with the moving speed of the inspection object 2, that is, the transport speed of the belt conveyor 3 by driving means such as a motor 6.

Reference numeral 7 denotes an imaging camera using a CCD, for example.
A visible image appearing on the fluorescent screen 4 is formed in a camera via a mirror 5 and converted into a video signal. A video signal from the imaging camera 7 is sent to an image processing device 8 where the signal is processed to detect and calculate a foreign substance in the inspection object 2. In this detection calculation, for example, a visible image of the fluorescent screen 4 obtained in a state where the inspection object 2 has no foreign matter is stored in a memory in advance, and the visible image at this time and the inspection object to be inspected are sequentially conveyed. The presence or absence of a foreign substance can be detected by comparing each of the visible images obtained in the state as described above.

Next, the operation of the above-configured device will be described. The inspection object 2 is placed on the belt conveyor 2 and transported one after another, and passes through the inspection position where the X-ray source 1 is installed. The X-ray source 1 detects the timing at which the inspection object 2 passes through a predetermined inspection position by, for example, an optical sensor (not shown), and irradiates the inspection object 2 with X-rays. The X-rays applied to the inspection object 2 pass through the inspection object 2 and the belt conveyor 3 respectively, and
To reach. Here, when a foreign substance is mixed in the inspection object 2, the amount of attenuation of the X-ray passing therethrough is different from that when no foreign substance is present, and the presence of the foreign substance is recognized in the X-ray fluoroscopic image appearing on the fluorescent screen 4. Can be

The X-ray fluoroscopic image appearing on the fluorescent screen 4 is reflected by the mirror 5 and captured by the imaging camera 7. The video signal from the imaging camera is sent to the image processing device 8, where the signal is processed and a foreign matter detection calculation is performed to determine whether or not foreign matter is mixed. In the above description, the X-ray irradiation time is short and the fluorescent screen 4 has a long after-image time, and the mirror 5 is used to capture the X-ray fluoroscopic image appearing on the fluorescent screen 5 in a stationary state. It is assumed that the light beam is incident on. The present invention can be realized in the use as described above, but it is also possible to obtain a clearer image by rotating the mirror 5 in synchronization with the movement of the inspection object 2.

FIG. 2 is a diagram for explaining a mirror driving method in a case where the mirror 5 is rotated in synchronization with the movement of the inspection object 2 to obtain a clear image. After the inspection object 2 conveyed in the direction of arrow B by the belt conveyor 3 reaches the inspection position,
After the elapse of the minute time Δt, the position 2
The position slightly moves to the position indicated by -2. Here, mirror 5
A line segment connecting the rotation center to the position 2-1 and the position 2-2
Is defined as C, and during this time, X-rays are continuously emitted from the X-ray source 1 to the inspection object 2. Further, here, the fluorescent plate 4 having a short after-image time is used, and the X-ray fluoroscopic image appearing on the fluorescent plate moves as the inspection object 4 moves.

The mirror 5 moves with the arrow A as the object 2 moves.
The rotation angle D of the mirror 5, which changes during the elapse of a minute time Δt, is set in the following relationship with respect to the angle C formed by each line segment. D = C / 2 (1)

Assuming that the conveying speed of the belt conveyor 3 is constant, the time change of the angle C becomes a constant value. Therefore,
By rotating the mirror 5 at a constant angular velocity while satisfying the relationship of the expression (1), an X-ray fluoroscopic image of the inspection object 2 appearing on the fluorescent screen 4 and moving during the angle C can be obtained at a constant light receiving surface of the imaging camera 7. Can always be formed at the position.

As a result, the exposure time for the imaging camera 7 can be lengthened, and a clear image with a high contrast can be obtained. Therefore, according to this embodiment, even if the transport speed of the inspection object is increased, it is possible to detect the foreign matter mixed in the inspection object with high accuracy.

In each of the above embodiments, a belt conveyor is used as a means for transporting the inspection object, but other transport means may be used. Further, a configuration may be added in which the intensity of X-rays emitted from the X-ray generation unit 1 is automatically changed depending on the type and size of the inspection object.

[0017]

FIG. 3 is a block diagram showing a second embodiment of the present invention. 5 in the configuration diagram of the embodiment shown in FIG.
This is an example in which the mirror is replaced by 7 imaging cameras. The inspection object 2 in the X-ray fluoroscopic image appearing on the fluorescent screen moves from the position indicated by 2-1 to the position indicated by 2-2 in the direction of arrow B after the elapse of the minute time Δt in FIG. Here, the light receiving axis of the imaging camera 7 is moved within the time Δt by an angle C formed by a line segment connecting the position 2-1 from the rotation center passing through the light receiving surface of the imaging camera and a line segment connecting the position 2-2. By rotating in accordance with the movement, an X-ray fluoroscopic image can always be formed at a fixed position on the light receiving surface of the imaging camera 7. As a result, a bright image with clear contrast can be obtained even when the transport speed of the inspection object is increased.

[0018]

As described above in detail, according to the present invention, the X-rays that have passed through the object to be inspected reach the fluorescent plate, where a transmitted X-ray image is obtained. Since the line image is captured by the imaging camera, foreign matter can be detected with a simple configuration. Further, by forming the transmitted X-ray image obtained on the fluorescent screen on the imaging camera via the reflecting means which rotates in synchronization with the movement of the inspection object, the exposure time in the imaging camera can be lengthened. Even if a fluorescent plate having a small amount of emitted light is used, a clearer image can be obtained, and a foreign substance mixed into an inspection object moving at high speed can be detected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram for explaining a driving method when a mirror that is a reflection unit is driven.

FIG. 3 is a configuration diagram of a second embodiment of the present invention.

FIG. 4 is a diagram for explaining a method of driving an imaging camera according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray generation source 2 Inspection object 3 Belt conveyor 4 Fluorescent plate 5 Reflecting means 6 Motor 7 Imaging camera 8 Image processing device 9 Motor control device

Claims (3)

[Claims] An X-ray source for irradiating an X-ray to an object to be inspected, conveying means for irradiating the object to be irradiated with the X-ray, and conveying the X-ray transmitted through the object to be inspected, a fluoroscopic image Plate for converting the image into a visible image, an image pickup camera for picking up the visible image obtained on the fluorescent plate and converting the image into an electric signal, and an image processing device for receiving the electric signal from the image pickup camera and performing image processing for foreign matter detection X-ray foreign substance inspection device. 2. A system according to claim 1, further comprising: rotatable reflecting means for reflecting the visible image obtained on the fluorescent screen to the imaging camera, and driving means for rotating the reflecting means in synchronization with the movement of the inspection object. 2. The X-ray foreign matter inspection apparatus according to claim 1, wherein: 3. An imaging camera having a light-receiving axis rotatable or movable, provided with driving means for performing a tracking movement in synchronization with the movement of the inspection object in the visible image obtained on the fluorescent screen. X-ray foreign matter inspection device.