JP2012068143A - X-ray inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray inspection device capable of performing inspection readily and with high accuracy.SOLUTION: In an X-ray inspection device 100, transmission X-rays 210 which have transmitted through an inspection target 900 are detected with a line sensor 220. A transmission image from the detected transmission X-rays 210 is created and the inspection target 900 is inspected. The line sensor 220 is a sensor which is an indirect line sensor including a scintillator and a photodiode, but is provided with no scintillator.

Description

  The present invention relates to an X-ray inspection apparatus for inspecting an article.

  Conventionally, an X-ray inspection apparatus or the like has been used for recognizing the shape of an article or detecting the presence or absence of foreign matter on an article. Research and development on these X-ray inspection apparatuses is conducted daily.

  For example, Patent Document 1 discloses an X-ray inspection apparatus that performs X-ray inspection. The X-ray inspection apparatus includes an X-ray source that irradiates X-rays from a first direction toward an inspection object including a plurality of contents overlapping in a first direction, and the X-rays from the X-ray source are each content. A position adjusting unit that adjusts the relative position between the object to be inspected and the X-ray source so as to pass through the end of the X-ray obliquely with respect to the first direction, and an X-ray receiving unit that receives X-rays from the X-ray source And a quantity inspection unit that inspects the quantity of contents contained in the inspection object based on the density value of the X-rays transmitted through the end portion obliquely with respect to the first direction and received by the X-ray light receiving unit; .

  Said X-ray inspection apparatus is an apparatus which test | inspects the quantity of the some content which overlapped. In general, when X-rays are incident on an assembly (inspected object) composed of a plurality of overlapping contents obliquely with respect to the overlapping direction of the contents, the images of these contents do not completely overlap. Appears with a slight shift in a certain direction. The X-ray inspection apparatus utilizes such a phenomenon, and the contents are arranged so that the X-rays are obliquely incident on the ends of the contents (the ends when viewed from the X-ray irradiation direction). The relative position of the assembly and the X-ray source is adjusted. Then, the quantity of the contents is determined based on the density value of the X-rays obliquely transmitted through the end portions of the contents. Thereby, the quantity inspection of a plurality of overlapping contents can be performed accurately.

JP 2010-38629 A

  However, the conventional X-ray inspection apparatus cannot perform inspection with high accuracy depending on the thickness of the article. That is, in particular, inspection of an article having a small thickness is difficult to detect because there is little deviation.

  An object of the present invention is to provide an X-ray inspection apparatus capable of performing inspection with high accuracy.

(1)
An X-ray inspection apparatus according to one aspect irradiates an article with X-rays from an X-ray source, detects transmission X-rays transmitted through the article with a line sensor, and transmits a transmission image from the detected transmission X-rays. An X-ray inspection apparatus for inspecting the article, wherein the tube voltage of the X-ray source irradiated from the X-ray source is in the range of 15 kilovolts to 50 kilovolts, and the line sensor comprises a scintillator and a photo This is a sensor from which a scintillator of an indirect line sensor composed of a diode is removed.

  In the X-ray inspection apparatus according to one aspect, transmitted X-rays transmitted through the article are detected by a line sensor. A transmission image is created from the detected transmission X-rays to inspect the article. The line sensor of the present invention is a sensor having no scintillator of an indirect line sensor composed of a scintillator and a photodiode.

  Conventionally, an indirect line sensor including a scintillator that converts X-rays into light and a photodiode that converts visible light into electric charges has been used. In the indirect line sensor, since X-rays are indirectly converted into electric charges, the X-ray image is not excellent in contrast characteristics and resolution. Therefore, when inspecting an article in a minute unit (for example, 0.1 mm unit), the inspection accuracy does not increase.

  On the other hand, according to the X-ray inspection apparatus according to the present invention, X-rays are directly converted into electric charges by a line sensor consisting only of photodiodes, so that an image based on the output of the line sensor has contrast characteristics and resolution. Is excellent. Thereby, the X-ray inspection of the article can be performed with high accuracy. For example, even when the article is a book and the inspection is performed in a minute unit with respect to the thickness so as to detect a missing page or a page fold, the book can be detected with high accuracy. Further, since the line sensor does not require a scintillator, cost reduction can be realized.

(2)
According to a second aspect of the present invention, in the X-ray inspection apparatus, the tube voltage of the X-ray source is 40 kilovolts or less.

  In this case, since the tube voltage of the X-ray source is 40 kilovolts or less, stable high-precision inspection can be performed with excellent resolution.

(3)
According to a third aspect of the present invention, in the X-ray inspection apparatus, the tube voltage of the X-ray source is 20 kilovolts or less.

  In this case, since the tube voltage of the X-ray source is 20 kilovolts or less, a more stable high-precision inspection can be performed with excellent resolution.

(4)
According to a fourth aspect of the present invention, in the X-ray inspection apparatus, the tube voltage of the X-ray source is 30 kilovolts or less, the material of the article is paper or resin, and the thickness is 12 mm or less.

In this case, the tube voltage of the X-ray source is 30 kilovolts or less, the material of the article is paper or resin, and the thickness is 12 mm or less. Specifically, the density of the article is 1.5 g / cm ³ or less. In this case, since it has a resolution of 0.08 mm, which is the thickness of a piece of paper, even if the inspection object is thin, such as paper, the X-ray inspection apparatus of the present invention can stably perform high-precision inspection. it can. Therefore, since it is possible to determine whether or not there is an abnormality in the page (paper) that is the minimum unit constituting the book, it is possible to reliably detect a missing page or a page fold.

(5)
An X-ray inspection apparatus for irradiating an article with an X-ray from an X-ray source, detecting transmitted X-rays transmitted through the article with a line sensor, and inspecting the article. The tube voltage of the X-ray source of the X-ray source irradiated from the X-ray source is 25 kilovolts or less, and the line sensor is a sensor obtained by removing the scintillator of the indirect line sensor composed of a scintillator and a photodiode. It is characterized by this.
An X-ray inspection apparatus for irradiating an article with an X-ray from an X-ray source, detecting transmitted X-rays transmitted through the article with a line sensor, and inspecting the article. The tube voltage of the X-ray source of the X-ray source irradiated from the X-ray source is 20 kilovolts or less, and the line sensor is a sensor obtained by removing the scintillator of the indirect line sensor composed of a scintillator and a photodiode. It is characterized by this.

  According to the X-ray inspection apparatus according to the present invention, inspection can be performed at low cost and with high accuracy.

1 is a schematic external view showing an example of an X-ray inspection apparatus according to the present embodiment. It is a schematic diagram which shows an example of the internal structure of the X-ray inspection apparatus which concerns on this embodiment. It is a block diagram which shows the example of the hardware constitutions of the X-ray inspection apparatus which concerns on this embodiment, and the example of a functional structure. It is a schematic diagram which shows the resolution | decomposability when articles | goods are paper using the line sensor which concerns on this Embodiment. It is a schematic diagram which shows resolution | decomposability in case an article | item is a polyacetal (POM) using the line sensor which concerns on this Embodiment.

  Hereinafter, an X-ray inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic external view showing an example of the X-ray inspection apparatus 100 according to the present embodiment, and FIG. 2 is a schematic view showing an example of the internal structure of the X-ray inspection apparatus 100 according to the present embodiment.

  As shown in FIG. 1, the X-ray inspection apparatus 100 has an X-ray inspection chamber 300 formed therein. An X-ray irradiation apparatus 200 is built in the X-ray examination room 300. A belt conveyor 800 is provided so as to penetrate the X-ray examination room 300.

  An X-ray leakage prevention curtain 500 that prevents X-ray leakage from the opening of the X-ray examination room 300 is provided. In addition, the X-ray inspection apparatus 100 is provided with a touch panel type input display unit MT for an operator to operate. The X-ray inspection apparatus 100 is driven by the operator operating the input display unit MT.

The operator places the inspection object 900 (FIG. 2) on the belt conveyor 800. In the present embodiment, the material of the inspection object 900 is paper or resin (for example, polyacetal). Specifically, an inspection object 900 having a density of 1.5 g / cm ³ or less is set as an inspection target. Further, a book (book) will be described as an example of the inspection object 900 in the present embodiment.

  The inspection object 900 placed on the belt conveyor 800 is subjected to foreign matter inspection or the like in the X-ray inspection room 300. Hereinafter, the internal structure of the X-ray examination room 300 will be described.

  As shown in FIG. 2, the X-ray examination room 300 mainly includes an X-ray irradiation apparatus 200, a line sensor 220, an X-ray leakage prevention curtain 500, and a belt conveyor 800. Details of the line sensor 220 will be described later. The X-ray leakage prevention curtain 500 includes an X-ray leakage prevention curtain device 510 on the entrance side of the X-ray examination room 300 and an X-ray leakage prevention curtain device 520 on the exit side.

  In the present embodiment, the above-described line sensor 220 is a sensor in which only the scintillator of the indirect line sensor composed of a photodiode and a scintillator including CdTe (cadmium telluride) is removed. The line sensor 220 mainly detects visible light and detects X-rays 210. The line sensor 220 converts the detected X-ray 210 directly into electric charges.

  The belt conveyor 800 is configured by winding an endless belt around a pair of rollers. A line sensor 220 that detects X-rays is provided inside the belt conveyor 800.

  In FIG. 2, the inspection object 900 is placed on the belt conveyor 800. When the belt conveyor 800 is driven, the inspection object 900 is transported along the direction of the arrow d1 (transport direction). The inspection object 900 being transported first passes through the X-ray leakage prevention curtain 510 and moves into the X-ray inspection room 300.

  Next, X-rays 210 are irradiated from the X-ray irradiation apparatus 200 to the inspection object 900 being conveyed. Then, the X-ray 210 that has passed through the inspection object 900 enters the line sensor 220.

  The line sensor 220 generates detection data based on the incident X-ray 210. Based on the detection data generated by the line sensor 220, inspection such as foreign matter inspection of the inspection object 900 is performed.

  Then, the inspection object 900 that has been subjected to the X-ray inspection is continuously conveyed by the belt conveyor 800, and thus moves outside the X-ray inspection chamber 300 after passing through the X-ray leakage prevention curtain 520. Thereafter, the inspection object 900 is conveyed to the next process.

  FIG. 3 is a block diagram illustrating an example of a hardware configuration and an example of a functional configuration of the X-ray inspection apparatus 100 according to the present embodiment.

  As shown in FIG. 3, the X-ray inspection apparatus 100 has the above-described line sensor 220, A / D converter 230, CPU (Central Processing Unit) 260, ROM (Read Only Memory) or RAM (Random) as hardware configurations. An access memory), a hard disk 280, and the input display section MT described above.

  When the CPU 260 executes various programs stored in the memory 270 or the hard disk 280, the luminance data acquisition unit 240, the summation unit 241, the output change amount calculation unit 242, the S / N ratio calculation unit 243 in FIG. The unit 244 and the display data creation unit 245 are functionally realized. Various programs can be installed from a recording medium such as a CD-ROM or DVD-ROM in which the program is recorded.

  In addition, the X-ray inspection apparatus 100 includes a display control circuit (not shown) that controls data display on the input display unit MT, and a key input circuit that captures data input by the operator via the input display unit MT (see FIG. And a communication port (not shown) that enables connection with an external device such as a printer or a network such as a LAN (local area network).

  The CPU 260, the memory 270, and the hard disk 280 are connected to each other via a bus line such as an address bus or a data bus.

  In FIG. 3, first, X-rays 210 that have passed through the inspection object 900 are incident on the line sensor 220, and the line sensor 220 generates detection data KDa that is analog data based on the X-rays 210. The detection data KDa is converted into detection data KDd which is digital data by the A / D converter 230.

  The brightness data LD1 is acquired by the brightness data acquisition unit 240 based on the detection value of the detection data KDd. The luminance data LD1 corresponds to one line of the image. Then, the summation unit 241 adds the plurality of brightness data LD1 to generate brightness data LD2 corresponding to all lines of the image.

  Based on the generated brightness data LD2, the output change amount calculation unit 242 calculates an output change amount, which will be described later. Further, an S / N ratio (signal-to-noise ratio) described later is calculated by the S / N ratio calculation unit 243 based on the luminance data LD2. Then, the inspection object 900 is inspected by the determination unit 244 based on the value of the brightness data LD2 or the output change amount. With the inspection, the determination unit 244 determines whether or not the inspection object 900 has an abnormality. Depending on the determination result of the determination unit 244, a warning sound (not shown) is emitted and a process such as a warning sound is performed. Note that the abnormality of the inspection object 900 means that, for example, there is a missing book or a fold in the page of the book. Further, the display data creation unit 245 creates display data for display on the input display unit MT.

  FIG. 4 is a schematic diagram showing the resolution when the inspection object 900 is paper using the line sensor 220 according to the present embodiment, and FIG. 5 uses the line sensor 220 according to the present embodiment. It is a schematic diagram which shows resolution | decomposability in case the to-be-inspected object 900 is polyacetal (POM). 4 and 5, the vertical axis represents resolution (mm), and the horizontal axis represents tube voltage (KV).

  As shown in FIG. 4 and FIG. 5, the resolution changes based on the resolution of one sheet of paper (0.08 mm) by changing the thickness of the paper or resin (polyacetal) from 1 mm to 20 mm in 1 mm increments. Was measured.

  P1 shown in FIG. 4 indicates a case where the inspection object 900 is 1 mm thick, P3 indicates a case where the inspection object 900 is 3 mm thick, and P5 indicates a case where the inspection object 900 is 5 mm thick. P7 indicates the case where the inspection object 900 is 7 mm thick, P9 indicates the case where the inspection object 900 is 9 mm thick, and P11 indicates the case where the inspection object 900 is 11 mm thick, P12 indicates a case where the inspection object 900 is 12 mm thick, P13 indicates a case where the inspection object 900 is 13 mm thick, P15 indicates a case where the inspection object 900 is 15 mm thick, and P17 indicates The inspection object 900 shows a case where the paper is 17 mm thick, and P19 shows a case where the inspection object 900 is a paper 19 mm thick.

  Similarly, R1 shown in FIG. 5 indicates a case where the inspection object 900 has a resin (POM) thickness of 1 mm, R3 indicates a case where the inspection object 900 has a resin (POM) thickness of 3 mm, and R5 indicates an inspection object. When the object 900 has a resin (POM) thickness of 5 mm, R7 indicates that the object to be inspected 900 has a resin (POM) thickness of 7 mm, and R9 indicates that the object to be inspected 900 has a resin (POM) thickness of 9 mm. R11 indicates the case where the inspection object 900 has a resin (POM) thickness of 11 mm, R12 indicates the case where the inspection object 900 has a resin (POM) thickness of 12 mm, and R13 indicates that the inspection object 900 is a resin (resin) POM) indicates a case of 13 mm thickness, R15 indicates a case where the inspection object 900 is a resin (POM) 15 mm thickness, R17 indicates a case where the inspection object 900 is a resin (POM) 17 mm thickness, and R19 indicates The inspection object 900 shows the case of the resin (POM) 19 mm thickness.

  As shown in FIGS. 4 and 5, it can be seen that the tube voltage of the X-ray irradiation apparatus 200 is 40 kV and there is an inflection point. Specifically, if the tube voltage is 40 kV or less, the resolution is in a substantially linear state, and if it exceeds 40 kV, the slope increases. Therefore, it was found that using the tube voltage of the X-ray irradiation apparatus 200 at 40 kV or less is preferable from the viewpoint of resolution.

  Moreover, as shown in FIGS. 4 and 5, it can be seen that the tube voltage of the X-ray irradiation apparatus 200 is 20 kV and there is an inflection point. Specifically, if the tube voltage is 20 kV or less, the resolution changes in a direction that further improves. Therefore, when using the line sensor which concerns on this invention, it turned out that it is preferable from the surface of the resolution to use the tube voltage of the X-ray irradiation apparatus 200 below 20 kV.

  Furthermore, as shown in FIGS. 4 and 5, for example, when the resolution is 0.08 mm or less, the tube voltage of the X-ray irradiation apparatus 200 is 30 kV or less, and the thickness of the inspection object 900 is The said standard is satisfy | filled when it is 12 mm or less.

  Therefore, when the tube voltage of the X-ray irradiation apparatus 200 is 30 kV or less and the thickness of the inspection object 900 is 12 mm or less, the resolution is 0.08 mm or less. And deformation of the resin can be detected.

(Effect in this embodiment)
According to the X-ray inspection apparatus 100 according to the present embodiment, since the scintillator of the indirect type line sensor is removed, the X-ray 210 is directly converted into electric charges. X-ray changes can be extracted and converted as output.

  In a conventional indirect line sensor, it is estimated that it is difficult to extract a minute change in X-rays because light conversion is performed in a scintillator. Further, the tube voltage proportional to the X-ray intensity from the X-ray irradiation apparatus 200 is about 40 kV to 60 kV, so that the case of paper or resin compared to the case of metal or the like to be detected In this case, since the change in X-rays becomes minute, detection was almost impossible.

  According to the X-ray inspection apparatus 100 according to the present embodiment, the inspection object 900 is a book, and the inspection is performed in a minute unit as in the case of detecting a book signature or a page fold. However, these can be detected with high accuracy. In addition, since the line sensor 220 does not require a scintillator, the cost can be reduced.

  Further, according to the X-ray inspection apparatus 100 according to the present invention, X-rays are directly converted into electric charges by the line sensor 220 made of only photodiodes, so that an image based on the output of the line sensor 220 has contrast characteristics and resolution. Is excellent. Thereby, the X-ray inspection of the inspection object 900 can be performed with high accuracy.

(Correspondence between each component of claims and each component of the above embodiment)
In the above embodiment, the X-ray inspection apparatus 100 corresponds to the X-ray inspection apparatus, the X-ray irradiation apparatus 200 corresponds to the X-ray source, the X-ray 210 corresponds to the transmitted X-ray, and the inspection object 900 is the article. The line sensor 220 corresponds to a line sensor.

(Modification)
In the above embodiment, the photodiode is made of CdTe (cadmium telluride). However, the present invention is not limited to this, and other materials such as Si (silicon) may be used.

  In the above embodiment, only the scintillator is removed from the line sensor. However, the present invention is not limited to this, and a resin cover may be provided instead of the scintillator. The resin cover can provide advantageous effects in terms of protection or strength.

  Furthermore, although one preferable embodiment of the present invention is as described above, the present invention is not limited thereto. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention.

DESCRIPTION OF SYMBOLS 100 X-ray inspection apparatus 200 X-ray irradiation apparatus 210 X-ray 220 Line sensor 900 Inspected object

Claims (4)

An article is irradiated with X-rays from an X-ray source, transmitted X-rays transmitted through the article are detected by a line sensor, a transmission image is created from the detected transmitted X-rays, and the article is inspected. An X-ray inspection apparatus,
The tube voltage of the X-ray source irradiated from the X-ray source is in the range of 15 kilovolts to 50 kilovolts, and the line sensor is a sensor from which the scintillator of the indirect line sensor composed of a scintillator and a photodiode is removed. X-ray inspection apparatus characterized by this.   2. The X-ray inspection apparatus according to claim 1, wherein the tube voltage of the X-ray source is 40 kilovolts or less.   The X-ray inspection apparatus according to claim 1, wherein a tube voltage of the X-ray source is 20 kilovolts or less. 3. The X-ray according to claim 1, wherein a tube voltage of the X-ray source is 30 kilovolts or less, and a material of the article is paper or resin and a thickness is 12 mm or less. Inspection device.