X-ray transmission inspection device

Abstract

The purpose of the present invention is to provide an X-ray transmission inspection device capable of inhibiting blurring of an X-ray transmission image by preventing warpage and bending of a sample. An X-ray transmission inspection device according to the present invention comprises a sample holder disposed between an X-ray source and an X-ray sensor. The sample holder holds a sample by attaching the sample on the surface of the sample holder through suction by reducing the pressure of the inside of the sample holder (see FIG. 1).

Description

X-ray inspection equipment

[0001] The present invention relates to an X-ray transmission inspection apparatus.

[0002] Lithium-ion secondary batteries are a type of non-aqueous electrolyte secondary battery with a higher energy density than nickel-metal hydride batteries. Lithium-ion secondary batteries are secondary batteries in which lithium ions in the electrolyte are responsible for electrical conduction and do not contain metallic lithium. Lithium-ion secondary batteries are used as batteries for notebook personal computers, mobile phones, automobiles, hybrid vehicles, electric vehicles, and other devices.

[0003] During the manufacturing process of secondary batteries, it is necessary to detect foreign matter that has become mixed into the battery. Methods using transmission X-rays are known as methods for detecting foreign matter in a sample. For example, the following methods are known:

[0004] Patent Document 1 addresses the issue of "preventing false detection of foreign matter due to changes in the distance between the sample and the X-ray detector," and describes the following technology (see abstract): "An X-ray tube 11 irradiates X-rays onto the sample element to be inspected, an X-ray detector 13 detects the transmitted X-rays when the X-rays pass through the sample, a calculation unit 17 obtains a contrast image from the transmission image of the transmitted X-rays, a sensor calculates the distance between the sample and the detector, and a mechanism for adjusting the position of the X-ray detector, and an X-ray transmission image is captured while maintaining a constant distance between the sample and the X-ray detector."

[0005] Patent Document 2 states that "the present invention relates to an image processing device for performing non-destructive inspection using an X-ray fluoroscopic image of an object to be inspected, and aims to obtain depth information from the X-ray transmission image." Under this objective, "a plurality of images are acquired from transmitted X-rays from an object to be inspected 4 using ten line sensors 61 to 66 10 The plurality of images are rearranged in a phase array memory 12 to obtain the amount of deviation, and the CPU 10 calculates the distance from the X-ray source 2 to the object (A, B) of the object 4 to be inspected, i.e., the depth of the distance between A and B, from the plurality of images of the object 4 to be inspected using the amount of deviation (see abstract).

[0006] JP 2011-191212 A JP 05-034131 A

[0007] Consider using X-ray transmission inspection to detect foreign matter mixed into battery components. In recent years, battery components (e.g., electrodes) have become thinner, making them more susceptible to warping and bending. If an X-ray image is acquired in this state, the image will be blurred, resulting in variations in the detected size of foreign matter. If the variations are large, there is a risk of missing an item. If the detection threshold for foreign matter is tightened to prevent this, it will have a significant impact on product yield and increase loss costs.

[0008] Some conventional X-ray inspection devices hold the part of the sample other than the inspection area (the area where foreign objects are detected by X-rays). While this can suppress warping and bending in the held area, it is difficult to completely eliminate warping and bending in the inspection area.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an X-ray transmission inspection device that can prevent warping or bending of a sample and suppress blurring of an X-ray transmission image.

[0010] The X-ray transmission inspection device of the present invention comprises a sample holder arranged between an X-ray source and an X-ray sensor, and the sample holder holds the sample by adsorbing the sample to the surface of the sample holder by reducing the pressure inside the sample holder.

[0011] The X-ray inspection device according to the present invention can prevent warping or bending of the sample and suppress blurring of the X-ray transmission image. Other objects, configurations, advantages, etc. of the present invention will become apparent from the following description of the embodiments.

[0012] Fig. 1 is a side view of an X-ray transmission inspection device 1 according to embodiment 1. Fig. 2 is a perspective view of a base member 112. Fig. 3 is a side view of an X-ray transmission inspection device 1 according to embodiment 2. Fig. 4 is a side view of an X-ray transmission inspection device 1 according to embodiment 3. Fig. 5 is a side view of an X-ray transmission inspection device 1 according to embodiment 4. Fig. 6 is a schematic diagram showing an example of a method in which a calculation unit 18 calculates the position and size of a foreign object.

[0013] 1 is a side view of an X-ray transmission inspection device 1 according to a first embodiment of the present invention. The X-ray transmission inspection device 1 is an apparatus that detects foreign matter on a sample 2 by an X-ray transmission image. The X-ray transmission inspection device 1 includes a sample holder 11, an X-ray source 13, and a camera 14. The sample holder 11 has a mounting portion 111 and a base member 112 (support portion).

[0014] The mounting portion 111 holds the sample 2 by placing the sample 2 thereon. The base member 112 supports the mounting portion 111. A flow path 12 is formed in the space between the mounting portion 111 and the base member 112. The X-ray source 13 irradiates the sample 2 with X-rays, for example, from below the base member 112. The base member 112 and the mounting portion 111 transmit at least a portion of the irradiated X-rays. As a result, the X-rays are irradiated onto the sample 2, and the X-rays that have transmitted through the sample 2 are detected by a camera 14 (X-ray sensor). The camera 14 creates an X-ray transmission image of the sample 2 using the transmitted X-rays.

[0015] 2 is a perspective view of the base member 112. A groove is formed on the surface of the base member 112. By placing the mounting portion 111 on this groove, a gap is formed between the mounting portion 111 and the base member 112, and this gap becomes the flow path 12. The pressure in the flow path 12 is reduced by, for example, a vacuum pump.

[0016] The mounting portion 111 is made of a breathable material. As a result, when the pressure in the flow path 12 is reduced, the sample 2 mounted on the mounting portion 111 is sucked toward the mounting portion 111. Therefore, even if the sample 2 is warped or bent, the suction force causes the sample 2 to be stretched, thereby suppressing the warping or bending.

[0017] The mounting portion 111 is a plate-shaped member having air permeability and can be formed, for example, from porous carbon. The material of the mounting portion 111 is not limited to this, and any material may be used as long as it has high X-ray transmittance suitable for creating X-ray radiographs, a stable shape, and air permeability. The base member 112 may be formed, for example, from CFRP (carbon fiber composite material), but is not limited thereto, and any material may be used as long as it has high X-ray transmittance suitable for creating X-ray radiographs, a stable shape, and is airtight. Examples of possible materials include polyimide, polyamide, ABS, POM (polyacetal), and other high-performance plastics.

[0018] The mounting portion 111 and the base member 112 can be integrally formed from a homogeneous material, or they can be formed as separate members and then bonded together to form the flow path 12. When formed from a homogeneous material, it is necessary to seal the airflow by solidifying the base member 112 with an adhesive or the like except for its upper surface. For example, when the mounting portion 111 and the base member 112 are made from porous carbon, integral molding has the advantage of allowing for more precise design of the flow path 12, as the shape is highly flexible.

[0019] A further note on the position where the flow channel 12 is formed. From the viewpoint of minimizing warping and bending of the sample 2 as much as possible, it is desirable that the action of sucking the sample 2 be exerted over as wide an area as possible of the bottom surface of the sample 2. Therefore, it is desirable that the planar area of ​​the flow channel 12 as viewed from the top surface of the sample 2 be as large as possible. On the other hand, if the width of the flow channel 12 is too wide, it becomes difficult to stably support the mounting portion 111. Therefore, it is conceivable to arrange a large number of thin flow channels 12 over as wide an area as possible of the bottom surface of the mounting portion 111. This makes it possible to stably support the mounting portion 111 while exerting the action of sucking the sample 2 over a wide area.

[0020] Summary of First Embodiment The X-ray transmission inspection device 1 according to the first embodiment adsorbs the sample 2 by reducing the pressure in the flow path 12 formed between the mounting portion 111 and the base member 112. As a result, even if the sample 2 is warped or bent, the adsorption action can suppress the warping or bending. Therefore, blurring of the X-ray transmission image can be suppressed. For example, the X-ray transmission inspection device 1 according to the first embodiment is useful when inspecting a sample 2 that is prone to warping or bending, such as battery materials that are becoming thinner.

[0021] 3 is a side view of an X-ray transmission inspection device 1 according to a second embodiment of the present invention. The X-ray transmission inspection device 1 according to the second embodiment includes a vacuum pump 15 and a pressurizing mechanism 16 in addition to the configuration described in the first embodiment. The other configurations are the same as those of the first embodiment.

[0022] The vacuum pump 15 is a device for reducing the pressure inside the flow path 12, and can also be used in the first embodiment. The pressurizing mechanism 16 is a device for pressurizing the inside of the flow path 12. When the pressurizing mechanism 16 pressurizes the inside of the flow path 12, compressed air is blown toward the sample 2 via the mounting part 111. This makes it possible to blow away foreign matter adhering to the sample 2. The piping between the vacuum pump 15 and the flow path 12 and the piping between the pressurizing mechanism 16 and the flow path 12 may be shared by switching the connection destination using an appropriate valve or the like.

[0023] The mechanism by which the pressure mechanism 16 blows away foreign matter can be the same as the mechanism by which the vacuum pump 15 sucks the sample 2 (i.e., the flow path 12 can be used in common). This is advantageous in that it is not necessary to form a new structure such as a flow path just for the function of blowing away foreign matter. Furthermore, by using the blowing function when removing the sample 2 from the X-ray inspection apparatus 1 after inspecting the sample 2, it is possible to easily remove the sample 2.

[0024] <Embodiment 3> Figure 4 is a side view of an X-ray transmission inspection apparatus 1 according to embodiment 3 of the present invention. The X-ray transmission inspection apparatus 1 according to embodiment 3 includes a reference block 17 in addition to the configuration described in embodiments 1 and 2. The reference block 17 is placed in a position where an X-ray transmission image of the reference block 17 can be captured by the X-ray source 13 and camera 14. For example, the reference block 17 can be placed in a location on the surface of the mounting section 111 where the sample 2 is not placed. The position (exact coordinates) of the reference block 17 is fixed, or at least known in advance before capturing an image of the sample 2. The size of the reference block 17 is also known in advance.

[0025] When capturing an X-ray transmission image of the sample 2, the X-ray source 13 and camera 14 also capture an X-ray transmission image of the reference block 17 (the X-ray transmission image of the sample 2 is captured so that the X-ray transmission image of the reference block 17 is included in the X-ray transmission image of the sample 2). By using the position and size of the reference block 17 as a reference, the position and size on the sample 2 can be relatively specified. This makes it possible to specify, for example, the position and size of a foreign substance on the sample 2.

[0026] The process of identifying the position and size of the foreign matter may be performed manually by a user or by calculation. When calculation is used, data describing the position and size of the reference block 17 is stored in advance in a storage device, and the position and size of the foreign matter can be identified by comparing the data with the X-ray transmission image of the sample 2 (i.e., the X-ray transmission image of the foreign matter).

[0027] The position of the reference block 17 may be measured each time the sample 2 is measured. In other words, it is sufficient to know the relative position of the foreign substance or the sample 2 with respect to the reference block 17. This is because the purpose of the inspection can be achieved if the relative position is known.

[0028] 5 is a side view of an X-ray transmission inspection device 1 according to a fourth embodiment of the present invention. The X-ray transmission inspection device 1 according to the fourth embodiment includes two pairs of an X-ray source and a camera (a first X-ray source 13a and a first camera 14a, and a second X-ray source 13b and a second camera 14b). The X-ray transmission inspection device 1 further includes a calculation unit 18. The calculation unit 18 can also be included in the third embodiment.

[0029] The first X-ray source 13a is disposed at a different position from the second X-ray source 13b. That is, the angle at which the first X-ray source 13a irradiates the sample 2 with X-rays is different from the angle at which the second X-ray source 13b irradiates the sample 2 with X-rays. Therefore, the X-ray transmission images captured by the first camera 14a and the second camera 14b are different from each other.

[0030] The first camera 14a takes an X-ray transmission image of the sample 2 and the reference block 17, as in the third embodiment. The second camera 14b also takes an X-ray transmission image of the sample 2 and the reference block 17, as in the third embodiment. The calculation unit 18 compares these X-ray transmission images to more accurately identify the position and size of any foreign matter present in the sample 2.

[0031] FIG. 6 is a schematic diagram showing an example of a method by which the calculation unit 18 calculates the position and size of a foreign particle. The first X-ray source 13a irradiates the sample 2 with X-rays, starting from the left side of the left diagram in FIG. 6 and gradually moving the irradiation position to the right. The first camera 14a captures this image, which can be seen in the upper right of FIG. 6, and includes foreign particles 61 and 62 inside the sample 2 and the reference block 17. The second X-ray source 13b irradiates the sample 2 with X-rays, starting from the right side of the left diagram in FIG. 6 and gradually moving the irradiation position to the left. The second camera 14b captures this image, which can be seen in the lower right of FIG. 6, in a similar manner.

[0032] The positional deviation of the reference piece 17 between the two images is always the same regardless of the positions and sizes of the foreign objects 61 and 62. Therefore, the positions and sizes of the foreign objects 61 and 62 can be calculated based on the relative positional deviation of the reference piece 17 between the two images.

[0033] <Regarding Modifications of the Present Invention> The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0034] In the above embodiment, the vacuum pump 15 is used to reduce the pressure in the flow path 12. However, any other decompression mechanism can be used as long as it can reduce the pressure in the flow path 12.

[0035] In the above embodiment, it has been explained that the flow path 12 is formed by the base member 112 having a groove, but the flow path 12 may also be formed by the mounting portion 111 having a similar groove, or the flow path 12 may be formed by both the base member 112 and the mounting portion 111 having grooves.

[0036] In the fourth embodiment, the first camera 14a and the second camera 14b are used to capture two X-ray transmission images, but a single camera 14 may be used. In this case, the operation of capturing X-rays from the first X-ray source 13a and the operation of capturing X-rays from the second X-ray source 13b may be performed using a single camera 14. On the other hand, if two cameras are used as described in the fourth embodiment, these two capturing operations can be performed in parallel, thereby reducing the capturing time.

[0037] In the above-described embodiments, the calculation unit 18 can be configured by hardware such as a circuit device that implements its functions, or can be configured by a calculation device such as a CPU (Central Processing Unit) that executes software that implements its functions.

[0038] 1: X-ray transmission inspection device 11: Sample holder 111: Mounting section 112: Base member 12: Flow path 13: X-ray source 14: Camera 15: Vacuum pump 16: Pressurizing mechanism 17: Reference block 18: Calculation section

Claims

1. An X-ray transmission inspection device comprising: a first X-ray source which irradiates a sample with X-rays; a first X-ray sensor which detects X-rays which have passed through the sample; and a sample holder which holds the sample, wherein the sample holder is disposed between the first X-ray source and the first X-ray sensor, and wherein the sample holder holds the sample by adsorbing the sample to a surface of the sample holder by reducing the pressure inside the sample holder.

2. The X-ray transmission inspection device according to claim 1, characterized in that the sample holder has a mounting portion on which the sample is placed, the mounting portion being made of a plate-shaped porous material that is breathable, and the sample holder is configured so that when the pressure inside the sample holder is reduced, the sample is adsorbed to the surface of the mounting portion.

3. The X-ray transmission inspection apparatus according to claim 2, further comprising a pressure reduction mechanism for reducing the pressure inside the sample holder, the sample holder having a support section for supporting the mounting section, and a flow path formed between the mounting section and the support section, and the pressure reduction mechanism reduces the pressure in the flow path.

4. The X-ray transmission inspection device according to claim 3, characterized in that the supporting portion is made of a carbon fiber composite material.

5. The X-ray transmission inspection device according to claim 3, characterized in that at least one of the support section and the placement section has a groove that forms the flow path.

6. An X-ray transmission inspection device according to claim 3, characterized in that the placement portion and the support portion are integrally constructed from a homogeneous material.

7. The X-ray transmission inspection device according to claim 1, further comprising a pressurizing mechanism for pressurizing the inside of the sample holder.

8. An X-ray transmission inspection apparatus according to claim 1, characterized in that the sample holder has a reference piece fixed to the sample holder.

9. The X-ray transmission inspection apparatus according to claim 8, further comprising: a second X-ray source which irradiates X-rays onto the sample from an angle different from that of the first X-ray source; and a calculation unit which calculates the position and size of a foreign object on the sample based on detection signals which represent the results of detecting the sample and the reference piece by the X-rays irradiated from the first X-ray source and detection signals which represent the results of detecting the sample and the reference piece by the X-rays irradiated from the second X-ray source.