JP2004257884A - X-ray method and apparatus for inspecting foreign substance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray method and apparatus for inspecting foreign substances, which breaks through the limitations of the conventional methods, can inspect minute foreign substances in a material to be inspected while keeping high SN ratios, and can continuously carry out the inspection of the material to be inspected. <P>SOLUTION: In the X-ray method for inspecting foreign substances, a material to be inspected is irradiated with X-rays while conveying it by using a conveyer 11, transmitted X-rays are detected as electric signals by using an X-ray detecting means, and the signals are processed, thereby inspecting the foreign substances in the material to be inspected. In the X-ray method, an X-ray image intensifier 14 and a camera 15 using a CCD (charge coupled device) image sensor 25 of time-delay integration types which photographs an image of the X-ray image intensifier 14, are used as the X-ray detecting means, and the charge-transfer speed of the CCD image sensor 25 is controlled so as to synchronize with an X-ray transmission image moving on the imaging surface 23 of the X-ray image intensifier 14, thereby obtaining clear image signals with the high SN ratio. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an X-ray foreign substance inspection method and apparatus capable of detecting, with high accuracy, foreign substances and defects consisting of solids contained in food, industrial raw material powder or other products, for example.
[0002]
[Prior art]
The most prominent inspection means for foreign substances inside food or industrial raw material powder is, for example, an automatic foreign substance inspection apparatus by X-ray fluoroscopy as described in Patent Document 1. However, the resolution of the line sensor type automatic foreign matter inspection apparatus described in Patent Document 1 is about 0.4 mm from the limits of X-ray intensity and inspection speed, and the detection limit is 0.25 to 0.3 mmφ. It is a piece of metal.
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-74856 (FIG. 1)
[0004]
[Problems to be solved by the invention]
However, since the enforcement of the PL Act, the introduction of food foreign matter inspection devices has been actively carried out, and if foreign substances are mixed in food, social trust will be lost and companies will be hit hard. Serious efforts are also being made to detect minute foreign matter.
Furthermore, in promoting nanotechnology and new energy, which are expected in the future, foreign matter mixed in the raw material manufacturing process may be fatal to products, and it is necessary to detect and remove fine foreign matter in order to establish manufacturing technology. Have been. For this reason, there is a strong demand for inspecting finer foreign matter, but no means has been proposed so far to meet this demand due to limitations in both technology and cost.
[0005]
In particular, there are some problems in detecting finer foreign substances during movement by X-ray fluoroscopy. However, magnifying imaging using a microfocus X-ray source to make small foreign substances visible is an effective means. is there. However, because the output of this microfocus X-ray source is small, the sensitivity is insufficient with the conventional X-ray line sensor. If the image is taken by an X-ray image intensifier type camera and integrated, it can be statically inspected. However, there is a problem that inspection during transportation cannot be performed, and the utility is low industrially.
[0006]
In addition, as the size of the foreign matter becomes smaller, the SN with the noise component due to uneven distribution of the inspection object or variation of the mixture becomes a problem. The problem can be solved by reducing the thickness of the inspection object, but the efficiency of the inspection is reduced, and the method cannot be applied to packaging or bottling.
[0007]
Then, as the size of the foreign matter becomes smaller, when the inspection object is a powder mixture, the SN with the noise component due to uneven distribution or variation of the mixture is reduced, and the overdetection of a normal object is increased. Although humans can easily discriminate, conventional fixed binarization and the high-pass filter method cannot extract only foreign matter.
[0008]
The present invention has been made in view of such circumstances, and breaks through the limitations of the conventional method, and can inspect minute foreign substances in products and raw materials (hereinafter, also referred to as “inspected materials”) with a high S / N ratio. An object of the present invention is to provide an X-ray foreign matter inspection method and apparatus capable of continuously inspecting an inspection material.
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided an X-ray foreign matter inspection method according to the first aspect of the present invention, wherein an X-ray is irradiated while an inspection target material is being transported by a transport device, and the transmitted X-ray is detected as an electric signal by an X-ray detection unit. An X-ray foreign matter inspection method for processing the signal to inspect foreign matter in the material to be inspected,
The X-ray image intensifier comprises: an X-ray image intensifier; and a camera using a time delay integration type CCD imaging device for capturing an image of the X-ray image intensifier. In synchronism with the X-ray transmission image moving on the image forming plane, the charge transfer speed of the CCD image pickup device is controlled to obtain a clear image signal having a high SN ratio.
[0010]
Here, the X-ray image intensifier is a kind of electron tube for amplifying an image, and emits an electron proportional to the X-ray intensity when an X-ray transmitted through a material to be inspected hits one surface of the tube. The emitted electrons are accelerated by a high electric field, further perform energy amplification, form an image on the other surface in the tube with an electron lens, and are simultaneously converted into a fluorescent image. As a result, it is possible to achieve light amplification of about 1000 times as much as when X-rays are simply applied to the fluorescent screen.
[0011]
A camera using a time delay integration type CCD imaging device (also referred to as a “TDI camera”) is an area camera having a time delay integration function. An image formed by a lens when an object moving at a constant speed is imaged moves in the opposite direction at a constant speed determined by the imaging magnification. If charge transfer and charge storage of the CCD are performed in synchronization with this speed, the resolution will remain at one pixel, and the sensitivity will be the same as the number of CCD shift storage stages (for example, 96). In order to detect minute objects, the X-ray generator becomes a microfocus X-ray source (or nano-focus X-ray source, the same applies hereinafter), the number of X-ray quanta decreases, and quantum variation noise becomes a problem. However, by using this time delay integration type CCD image pickup device, integration is performed by the number of accumulation stages, quantum noise is reduced, and a clear image signal can be obtained. It should be noted that a time delay integration type CCD imaging device is also known in, for example, Japanese Patent Application Laid-Open No. Hei 7-111621 and Japanese Patent Application Laid-Open No. 2002-540395. For example, an Eclipse camera manufactured by DALSA and the like are used. Is known as a specific product.
[0012]
An X-ray foreign matter inspection method according to a second aspect of the present invention is the X-ray foreign matter inspection method according to the first aspect, wherein the charge transfer speed of the CCD image pickup device is the moving speed V of the transport device and the X-ray X-ray intensity. An optical magnification determined by the positional relationship between the X-ray image intensifier, the X-ray image intensifier, and the input screen of the X-ray image intensifier; It is determined from the imaging magnification β of the camera that captures the image of the output screen of the tensifier.
[0013]
In the X-ray foreign matter inspection method according to the third invention, the inspection object is irradiated with X-rays while being conveyed by the conveyance device, and the transmitted X-rays are detected as electric signals by X-ray detection means. An X-ray foreign matter inspection method for inspecting foreign matter in the material to be inspected by processing,
As the X-ray detecting means, an X-ray fluorescent plate and a camera using a time delay integration type CCD image pickup device for capturing an image of the X-ray fluorescent plate are used to obtain an X-ray transmission image moving on the X-ray fluorescent plate. Synchronously, the charge transfer speed of the CCD image sensor is controlled to obtain a clear image signal having a high SN ratio.
[0014]
An X-ray foreign matter inspection method according to a fourth invention is the X-ray foreign matter inspection method according to the third invention, wherein the charge transfer speed of the CCD image pickup device is the moving speed V of the transport device and the X-ray X-ray speed. It is determined from an optical magnification determined by the positional relationship between the X-ray fluorescent plate and the X-ray fluorescent plate, and the imaging magnification β of the camera that images the X-ray fluorescent plate.
Similarly to the X-ray foreign matter inspection method according to the second invention, in the X-ray foreign matter inspection method according to the fourth invention, a minute X-ray image signal is amplified by a time delay integration type CCD image pickup device. An electric signal of a clear image can be obtained.
[0015]
An X-ray foreign matter inspection method according to a fifth invention is the X-ray foreign matter inspection method according to the first to fourth inventions, wherein a plurality of cameras using the time delay integration type CCD imaging device are installed, and When inspecting the inspection object, the inspection object is divided into the number of cameras in the thickness direction, and the charge transfer speed of the CCD image sensor is controlled in accordance with the optical magnification of each thickness region, Equivalently, tomographic image reconstruction is performed, and even when the material to be inspected is thick, an inspection with high accuracy in the thickness direction is enabled.
[0016]
The X-ray foreign matter inspection apparatus according to the sixth invention irradiates X-rays while the inspection object is being conveyed by the conveyance device, detects the transmitted X-rays as electric signals by X-ray detection means, and converts this signal into an electric signal. In an X-ray foreign matter inspection apparatus for processing and inspecting foreign matter in the material to be inspected,
An X-ray generator that generates the X-ray;
An X-ray fluorescent plate that changes an image of the test object being conveyed by the X-ray projection into a visible image,
Having a camera using a time delay integration type CCD imaging device for capturing an image of the X-ray fluorescent plate,
The charge transfer speed of the CCD image sensor is adjusted in synchronization with an X-ray transmission image moving on the X-ray fluorescent plate to obtain a clear and high SN ratio image signal of the inspection object.
[0017]
The X-ray foreign matter inspection apparatus according to the seventh invention irradiates X-rays while the inspection object is being conveyed by the conveyance device, detects the transmitted X-rays as an electric signal by the X-ray detection means, and detects this signal. In an X-ray foreign matter inspection apparatus for processing and inspecting foreign matter in the material to be inspected,
An X-ray generator that generates the X-ray;
An X-ray image intensifier having a function of converting a weak X-ray transmission image into a bright visible light image by changing an image by the X-ray projection of the inspection target material being transported into a visible image,
Having a camera using a time delay integration type CCD imaging device for capturing an image of the X-ray image intensifier,
In synchronization with the X-ray transmission image moving on the X-ray image intensifier, the charge transfer speed of the CCD image pickup device is adjusted to obtain a clear and high S / N ratio image signal of the inspection object.
[0018]
The X-ray foreign matter inspection apparatus according to the eighth invention is the X-ray foreign matter inspection apparatus according to the sixth and seventh inventions, wherein a plurality of cameras using the time delay integration type CCD image pickup device are installed, and the thickness is reduced. When inspecting a certain inspection object, the inspection object is divided into the number of cameras in the thickness direction, and the charge transfer speed of the CCD image sensor is controlled in accordance with the optical magnification of each thickness region. In other words, tomographic image reconstruction is equivalently performed, and even when the object to be inspected is thick, an accurate inspection can be performed.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
Here, FIG. 1 is a schematic explanatory view of an X-ray foreign substance inspection apparatus according to the first embodiment of the present invention, and FIG. 2 (A) is an X-ray foreign substance inspection apparatus according to the first embodiment of the present invention ( (B) is an explanatory diagram of an X-ray foreign matter inspection apparatus according to a modification thereof, FIG. 3 is an operational explanatory diagram of a time delay integration type CCD imaging device, and FIG. 4 is a second embodiment of the present invention. 1 is a schematic explanatory diagram of an X-ray foreign matter inspection device according to an embodiment.
[0020]
As shown in FIG. 1, an X-ray foreign substance inspection apparatus 10 according to a first embodiment of the present invention includes a powder raw material (for example, food, medicine, and other industrial raw materials) A conveyed by a belt conveyor 11. A belt conveyor (an example of a transfer device) 11 for detecting the minute metal components (for example, iron and copper) and other solid foreign substances, and for transporting the raw material constituting the material to be inspected, and gradually on the belt conveyor 11 Hopper 12 for cutting raw materials, a microfocus X-ray source (an example of an X-ray generator) 13 disposed directly above a belt conveyor 11, and an X-ray image intensifier disposed immediately below the belt conveyor 11 And a camera 15 using a time delay integration type CCD image sensor 25 (see FIG. 2) for capturing an image of the X-ray image intensifier 14. The X-ray image intensifier 14 and the camera 15 constitute an X-ray detection unit.
[0021]
The belt conveyor 11 has a plurality of guide rollers 16 to 19 and a drive roller 20, and moves a rubber or plastic endless belt having a predetermined width at a predetermined speed (V).
At the bottom of the hopper 12, a fixed amount cut-out device 21 is provided, and the raw material in the hopper 12 is supplied onto the belt conveyor 11 with a constant thickness, is conveyed, and is charged into the collection container 22 from the end of the drive roller 20. In this process, X-rays are emitted from the microfocus X-ray source 13.
[0022]
The microfocus X-ray source 13 is an X-ray source having a focal radius of 10 μm or less (for example, 5 μm or less), and is a minute foreign matter in a material to be irradiated. Even so, a clear shadow can be generated. Therefore, X-rays are generated by accelerating an electron beam in a high electric field (−tens of KV to hundreds of KV) and colliding with a target metal (a refractory metal such as tungsten or molybdenum). Efficiency is said to be less than 3%, and mostly heat. In a microfocus X-ray source, the electron beam is narrowed down by an electron lens and concentrated (focused) in a region having a diameter of 10 μm or less, so that the metal of the target is thermally deteriorated (thermal fatigue, melting, evaporation, and rough skin of the target). Increased risk of causing. Therefore, the current that can be applied is limited, and the amount of X-ray that can be generated is proportionally reduced. In addition, in the case of enlarging an image with a microfocus X-ray source, the density of X-rays decreases with the square of the distance. , A more sensitive sensor, such as an X-ray image intensifier, is required.
[0023]
The X-ray image intensifier 14 is a large-sized electron tube that not only converts X-rays into visible light but also brightens weak light. The X-ray image intensifier 14 was first commercialized in 1952 by Philip, a Dutch company. For example, in JP-A-2003-004856, JP-A-2002-162471, JP-A-5-174746, JP-A-09-017361, and the like, the structure is known. Therefore, although detailed description is omitted, an X-ray transmission image by X-rays emitted from the microfocus X-ray source 13 to the material to be inspected is further amplified and output as a visible light image. . The image moves according to the moving speed (V) of the belt conveyor 11. Since the size of the image changes (generally becomes smaller) when the image passes through the X-ray image intensifier 14, the image enlargement / reduction ratio is α.
[0024]
The camera 15 using the time delay integration type CCD imaging device 25 captures an image light-amplified by the X-ray image intensifier 14. As shown in FIG. 2, an image of an output screen (that is, an image forming plane) 23 of the X-ray image intensifier 14 is formed on a time delay integration type CCD image pickup device 25 via a lens system 24. . In the CCD imaging device 25, if a foreign matter B exists in the powder raw material A which is the material to be inspected, the image on the CCD imaging device 25 also moves in accordance with the movement of the belt conveyor 11, so that the moving speed Accordingly, charge accumulation and charge transfer of the CCD image sensor 25 are performed.
[0025]
That is, for the moving speed V of the belt conveyor 11, the image formed on the input screen 26 of the X-ray image intensifier includes the microfocus X-ray source 13 and the foreign matter B (actually, Assuming that the distance to the side) is b and the distance between the microfocus X-ray source 13 and the input screen 26 is a, the magnification is b / a (optical magnification). The size of the X-ray image intensifier 14 changes depending on the image enlargement / reduction ratio α, and is further enlarged by β (imaging magnification) by the lens system 24 of the camera 15 to form an image on the CCD image sensor 25. . Therefore, the image B ′ of the foreign matter B formed on the CCD image pickup device 25 is (V · b / a · α · β) = V ₃ And at the same speed as the moving direction of the belt conveyor 11. Note that this speed V ₃ Are synchronized with the moving image (X-ray transmission image) on the output screen 23 of the X-ray image intensifier 14.
[0026]
Therefore, as shown in FIG. 3, for example, the charge of each cell 27 in the row of the CCD image sensor 25 having the cells 27 of 2048 in length and 96 in width is transferred to the speed V. ₃ When the belt conveyor 11 is moved in the same direction as the moving direction, the charges of the foreign matter image B 'are accumulated in a unit of one pixel. In this embodiment, the pixel signal is amplified 96 times. Is done. Then, the cells are charged in the vertical cell row 28 arranged in the vertical direction in the final step. Next, the signal is taken out by sending out the signal of taking out the charge of each cell in the vertical direction, and this signal is taken out of the cell arranged in the horizontal direction. Is taken out every time the electric charge is transferred to obtain an image signal (electric signal).
[0027]
Therefore, when inspecting for foreign matter using the X-ray foreign matter inspection apparatus 10 according to the first embodiment of the present invention, as shown in FIGS. A is gradually cut out on the belt conveyor 11, X-rays are emitted from the microfocus X-ray source 13 provided on the belt conveyor 11, and the projected image is displayed on the input screen 26 of the X-ray image intensifier 14. The X-ray image intensifier 14 amplifies the signal and displays it on an output screen (image display surface) 23 of the X-ray image intensifier 14, which is imaged by a camera 15 having a time delay integration type CCD image sensor 25. Then, the charge transfer speed of the CCD imaging device 25 is set to (V · b / a · α · β) = V ₃ And the same direction as the moving direction of the belt conveyor 11.
[0028]
Thus, the output signal is amplified (96 times) and output by the CCD image pickup device 25. That is, in order to detect fine foreign substances, it is necessary to extremely narrow the focus of the source of the microfocus X-ray source 13, but this significantly reduces the dose of X-rays generated from the microfocus X-ray source 13. I do. Therefore, in this embodiment, since the image output is amplified by the X-ray image intensifier 14 and further amplified by using the time delay integration type CCD imaging device 25, the weak X-ray image Accordingly, a clear image signal having a high SN ratio can be obtained.
[0029]
In this embodiment, an X-ray projection image is input to the X-ray image intensifier 14, but, for example, as shown in FIG. 2B, an X-ray fluorescent screen 29 is used instead of the X-ray image intensifier 14. , The image projected from the microfocus X-ray source 13 can be converted into an optical signal on the X-ray fluorescent plate 29 and captured by the camera 15 having the time-delay-integrated CCD image sensor 25. In this case, the image of the X-ray fluorescent plate 29 is enlarged to V · b / a, further multiplied by β by the camera 15, and formed on the time-delay-integrated CCD image pickup device 25, and the moving direction is changed. If the charge transfer speed of the CCD image pickup device 25 is β · V · b / a in the opposite direction to the movement direction of the belt conveyor 11, the charge transfer speed of the CCD image pickup device 25 is 96 times. The X-ray fluorescent plate 29 and the camera 15 constitute an X-ray detection unit, and a clear image signal (electric signal) of the foreign matter B ″ having a high SN ratio can be obtained. The moving speed of the image of the delay-integration type CCD image pickup device 25 is synchronized with the image moving through the X-ray fluorescent plate 29 (X-ray transmission image).
[0030]
Next, an X-ray foreign substance inspection apparatus 30 according to a second embodiment of the present invention shown in FIG. 4 will be described. The same components as those in FIGS. Detailed description is omitted.
As shown in FIG. 4, the X-ray foreign matter inspection apparatus 30 includes a microfocus X-ray generation source 13, a belt conveyor 32 that conveys a material to be inspected 31 (for example, a food having a thickness such as tofu or konjac) 31. An X-ray image intensifier 14 disposed directly below the microfocus X-ray source 13 and directly below the belt conveyor 32, a prism 33 for dividing the output image of the X-ray image intensifier 14 into three parts, Cameras 34 to 36 each having three time-delay-integration type CCD image sensors 25 for capturing the output images thus obtained, control devices 37 to 39, and an image processing device connected to the control devices 37 to 39 ( (Having a storage unit) 40 and a computer 41 connected thereto. A speed sensor (for example, a rotary encoder) 42 that detects the speed of the belt is provided below the belt conveyor 32, and the output is input to the control devices 37 to 39. Here, the X-ray image intensifier 14 and the cameras 34 to 36 constitute X-ray detection means.
[0031]
In the X-ray foreign matter inspection apparatus 30 according to the present embodiment, the foreign matter B1, B2 irradiated on the X-ray emitted from the microfocus X-ray source 13 and formed on the input screen 26 of the X-ray image intensifier 14 , B3 are optically amplified by the X-ray image intensifier 14 and displayed on the output screen 23 thereof. Then, the image is divided into three parts in the flow direction of the belt conveyor 32 via the prism 33 and is imaged by the cameras 34 to 36. Here, the charge transfer speeds Va to Vc of the time delay integration type CCD imaging device 25 of the cameras 34 to 36 are adjusted as follows.
[0032]
That is, although the inspection material 31 moving on the belt conveyor 32 moves at a constant speed V, it is assumed that three foreign materials B1 to B3 are located in the inspection material 31 at different positions (c, d, e) in the thickness direction. Assuming that B3 exists, the moving speeds of the images of the foreign substances B1 to B3 input to the input screen 26 of the X-ray image intensifier 14 are (V · c / a), (V · d / a), (V · e / a), which depends on the positions of the foreign substances B1 to B3. As a result, the moving speed of the image formed on the time-delay-integration type CCD imaging device 25 is also (α · β · V · c / a), (α · β · V · d / a), (α · β) V · e / a), and this image is converted to a time-delay-integrated CCD image sensor 25 using one camera as in the X-ray foreign substance inspection apparatus 10 according to the first embodiment. If one charge transfer speed is set, an image of a foreign substance in another layer will be blurred.
[0033]
Therefore, in the X-ray foreign matter inspection apparatus 30 according to the present embodiment, three (i.e., a plurality of) cameras 34 to 36 are prepared, and the transfer speeds Va to Va of the charge of the CCD imaging device 25 of the time delay integration type are prepared. As described above, for example, (α · β · V · c / a), (α · β · V · d / a), (α · β · V) By adjusting to e / a), tomographic image reconstruction is equivalently performed, and a clear image signal having a high SN ratio is obtained in accordance with each layer of the inspection target material 31. The control devices 37 to 39 input the speed of the belt conveyor 32 detected by the speed sensor 42, and charge the transfer speed of the CCD image pickup device 25 of each of the cameras 34 to 36 according to the height and thickness of the inspection target material 31. Is determined to obtain a clear image signal. The image signals obtained by the control devices 37 to 39 are once input to the image processing device 40 and then input to the computer 41, where they are combined with the actual image of the material 31 to be inspected to detect foreign matter on the screen. And the data is recorded. In this embodiment, the number of cameras is not limited to three, and the present invention is applicable even when the number of cameras is two or four or more.
[0034]
Using the X-ray foreign matter inspection apparatus according to the first aspect of the invention, when inspecting a material to be inspected such as food, medicine, powder raw material, etc., the inspection speed was 60 mpm, and the detection of iron wire debris having a diameter of 0.1 μm was detected. It has become possible. In the prior art, at 20 mpm, only a foreign substance having a size of about 200 to 300 μm or more could be detected.
[0035]
The present invention is not limited to the above-described embodiment, and includes modifications and improvements as long as the gist of the present invention is not changed. Specifically, in the X-ray foreign matter inspection device 30 according to the second embodiment, the above-described X-ray fluorescent plate 29 for changing an image by X-ray projection into a visible image is used instead of the X-ray image intensifier 14. This makes it possible to configure the device at low cost.
Further, in the X-ray foreign matter inspection apparatus 30 according to the second embodiment, a half mirror can be used instead of the prism 33. In this case, the signal light decreases, but it can be used sufficiently depending on the size of the foreign matter to be detected.
In the above-described embodiment, the number of cells of the time delay integration type CCD image pickup device 25 has been specifically limited. However, the present invention is not limited to this number. Can be selected.
[0036]
【The invention's effect】
In the X-ray foreign matter inspection method according to the first and second aspects and the X-ray foreign matter inspection method according to the fifth aspect, the projection image by the X-ray is converted into a visible light image by an X-ray image intensifier. This image is taken using a camera using a time delay integration type CCD image pickup device, and further synchronized with an X-ray transmission image moving on the image forming plane of the X-ray image intensifier to charge the CCD image pickup device. Since the transfer speed is adjusted, a clear image signal having a high SN ratio can be obtained.
As a result, the focus of the X-ray source can be further reduced, and the inspection speed can be improved. Therefore, high-speed inspection of minute foreign substances mixed in the inspection target material can be performed. became.
[0037]
In the X-ray foreign matter inspection method according to the third and fourth aspects and the X-ray foreign matter inspection method according to the fifth aspect, the X-ray foreign matter inspection method is replaced with the X-ray image intensifier according to the first and second aspects. Since the fluorescent screen is used, the sensitivity is slightly lower than that using the X-ray image intensifier, but the production cost is lower as a whole.
Compared with the conventional line sensor type foreign matter inspection apparatus, a remarkable signal output can be obtained, and an image signal with a higher SN ratio can be obtained. As a result, a faster X-ray source with a smaller focus can be obtained. Since the material to be inspected can be moved, the material to be inspected can be inspected at a higher speed.
[0038]
In the X-ray foreign matter inspection method according to the fifth aspect, a plurality of cameras using a time delay integration type CCD imaging device are installed, and when inspecting a thick inspection object, the inspection object is focused in the thickness direction. In this way, by dividing the number of cameras and controlling the charge transfer rate of the CCD image sensor in accordance with the optical magnification of each thickness region, tomographic image reconstruction is equivalently performed, and the object to be inspected is thick. Even in this case, accurate inspection was enabled.
Thus, even when the thickness of the test object is large, a clear image signal can be obtained without defocusing of the image.
[0039]
According to a sixth aspect of the present invention, there is provided an X-ray foreign matter inspection apparatus which generates an X-ray, and an X-ray which converts an image of the inspection object being conveyed by X-ray projection into a visible image. A fluorescent screen, and a camera using a time-delay-integration type CCD imaging device for capturing an image of the X-ray fluorescent plate, and synchronizing with an X-ray transmission image moving on the X-ray fluorescent plate, the charge transfer speed of the CCD imaging device Is adjusted, it is possible to obtain a clear and high S / N ratio image signal of the material to be inspected.
Thus, an X-ray source having a smaller focus can be used by the X-ray generator, and the inspection of the inspection target material can be performed at a higher speed.
[0040]
In the X-ray foreign matter inspection apparatus according to the seventh and eighth aspects, an X-ray image intensifier is used in place of the X-ray fluorescent plate according to the sixth aspect, so that a clearer SN is obtained. An image signal with a high ratio can be obtained, and as a result, smaller foreign substances can be detected at a high speed.
[0041]
In the X-ray foreign matter inspection apparatus according to claim 8, a plurality of cameras using a time delay integration type CCD image pickup device are installed, and when inspecting a thick inspection object, the inspection object is moved in the thickness direction. Since the charge transfer speed of the CCD image pickup device is controlled in accordance with the optical magnification of each thickness region by dividing according to the number of devices, tomographic image reconstruction is performed equivalently, and the inspection object is thick. Even in this case, accurate inspection was enabled.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of an X-ray foreign matter inspection apparatus according to a first embodiment of the present invention.
FIG. 2A is an explanatory view of an X-ray foreign substance inspection apparatus (and a method thereof) according to a first embodiment of the present invention, and FIG. 2B is an explanatory view of an X-ray foreign substance inspection apparatus according to a modified example thereof; It is.
FIG. 3 is a diagram illustrating the operation of a time delay integration type CCD imaging device.
FIG. 4 is a schematic explanatory view of an X-ray foreign matter inspection apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
10: X-ray foreign substance inspection apparatus, 11: belt conveyor, 12: hopper, 13: microfocus X-ray source, 14: X-ray image intensifier, 15: camera, 16 to 19: guide roller, 20: drive roller, 21: fixed-quantity cut-out device, 22: collection container, 23: output screen, 24: lens system, 25: CCD image sensor, 26: input screen, 27: cell, 28: vertical cell row, 29: X-ray fluorescent plate, 30: X-ray foreign substance inspection device, 31: inspection material, 32: belt conveyor, 33: prism, 34 to 36: camera, 37 to 39: control device, 40: image processing device, 41: computer, 42: speed sensor, A : Powder raw material, B: foreign matter, B1 to B3: foreign matter

Claims (8)

X-rays are radiated during the transport of the material to be inspected by the transport device, and the transmitted X-rays are detected as electric signals by the X-ray detecting means, and this signal is processed to inspect foreign substances in the material to be inspected. In the X-ray foreign matter inspection method,
The X-ray image intensifier comprises: an X-ray image intensifier; and a camera using a time delay integration type CCD imaging device for capturing an image of the X-ray image intensifier. An X-ray foreign matter inspection method characterized by controlling a charge transfer speed of the CCD image pickup device in synchronization with an X-ray transmission image moving on an image forming surface to obtain a clear image signal having a high SN ratio. 2. The X-ray foreign matter inspection method according to claim 1, wherein the charge transfer speed of the CCD imaging device is a moving speed V of the transport device, an X-ray X-ray generator, the inspection object, and the X-ray image. An optical magnification determined by the positional relationship of the input screen of the intensifier, an image magnification / reduction rate α of the X-ray image intensifier, and imaging of the camera for capturing an image on the output screen of the X-ray image intensifier An X-ray foreign matter inspection method characterized by being determined from a magnification β. X-rays are radiated during the transport of the material to be inspected by the transport device, and the transmitted X-rays are detected as electric signals by the X-ray detecting means, and this signal is processed to inspect foreign substances in the material to be inspected. In the X-ray foreign matter inspection method,
As the X-ray detecting means, an X-ray fluorescent plate and a camera using a time delay integration type CCD image pickup device for capturing an image of the X-ray fluorescent plate are used to obtain an X-ray transmission image moving on the X-ray fluorescent plate. An X-ray foreign substance inspection method, wherein a charge transfer rate of the CCD image sensor is controlled in synchronization to obtain a clear image signal having a high SN ratio. 4. The X-ray foreign matter inspection method according to claim 3, wherein the charge transfer speed of the CCD imaging device is a moving speed V of the transport device, an X-ray X-ray generator, the inspection object, and the X-ray fluorescent plate. And an imaging magnification β of the camera that images the X-ray fluorescent plate. In the X-ray foreign matter inspection method according to any one of claims 1 to 4, a plurality of cameras using the time delay integration type CCD imaging device are installed, and when inspecting a thick inspection object, The inspection object is divided into the number of cameras in the thickness direction, and the tomographic image is equivalently reconstructed by controlling the charge transfer speed of the CCD image sensor in accordance with the optical magnification of each thickness region. An X-ray foreign substance inspection method, wherein an inspection with high accuracy in the thickness direction is enabled even when the material to be inspected is thick. X-rays are radiated during the transport of the material to be inspected by the transport device, and the transmitted X-rays are detected as electric signals by the X-ray detecting means, and this signal is processed to inspect foreign substances in the material to be inspected. In the X-ray foreign matter inspection device,
An X-ray generator that generates the X-ray;
An X-ray fluorescent plate that changes an image of the test object being conveyed by the X-ray projection into a visible image,
Having a camera using a time delay integration type CCD imaging device for capturing an image of the X-ray fluorescent plate,
Synchronizing with an X-ray transmission image moving on the X-ray fluorescent plate, adjusting a charge transfer speed of the CCD image pickup device, and obtaining a clear and high SN ratio image signal of the inspection object. Line foreign matter inspection device. X-rays are radiated during the transport of the material to be inspected by the transport device, and the transmitted X-rays are detected as electric signals by the X-ray detecting means, and this signal is processed to inspect foreign substances in the material to be inspected. In the X-ray foreign matter inspection device,
An X-ray generator that generates the X-ray;
An X-ray image intensifier having a function of converting a weak X-ray transmission image into a bright visible light image by changing an image by the X-ray projection of the inspection target material being transported into a visible image,
Having a camera using a time delay integration type CCD imaging device for capturing an image of the X-ray image intensifier,
Synchronizing with the X-ray transmission image moving on the X-ray image intensifier, adjusting the charge transfer speed of the CCD image sensor to obtain a clear and high SN ratio image signal of the inspection object. X-ray foreign matter inspection device. 8. The X-ray foreign matter inspection apparatus according to claim 6, wherein a plurality of cameras using the time delay integration type CCD image pickup device are installed, and when inspecting a thick object to be inspected, the object is inspected. The inspection object is divided into the number of cameras in the thickness direction, and the charge transfer speed of the CCD image sensor is controlled in accordance with the optical magnification of each thickness region, thereby to perform equivalent tomographic image reconstruction. An X-ray foreign matter inspection apparatus characterized in that an accurate inspection can be performed even when the object to be inspected is thick.

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