Calibration method, imaging method, inspection method, method for producing product, imaging system, method for producing same, and inspection system

Abstract

An imaging device (320A) images a surface of a calibration sheet (500) that is moving along a curved movement path (820), and thereby moving sheet image data which represents an image of said surface is acquired. The moving sheet image data is used to perform calibration of the imaging device (320A). Said surface has a calibration pattern that differs from a pattern which is constituted as a whole by a repeating shape pattern.

Description

Calibration Method, Imaging Method, Inspection Method, Product Manufacturing Method, Imaging System and Its Manufacturing Method, and Inspection System

[0001] The present disclosure relates to a calibration method, an imaging method, an inspection method, a product manufacturing method, an imaging system and its manufacturing method, and an inspection system.

[0002] Consideration has been made regarding the calibration of an imaging device. Calibration can be performed using a calibration pattern. In Patent Document 1, a checkerboard pattern is described as a calibration pattern.

[0003] Japanese Patent Application Laid-Open No. 2005-250628 International Publication No. 2023 / 189557

[0004] The present disclosure provides a technique suitable for suppressing distortion of an image obtained by imaging an object moving along a curved movement path.

[0005] The present disclosure includes acquiring moving sheet image data representing an image of the surface by imaging the surface of a calibration sheet moving along a curved movement path with an imaging device, and performing calibration of the imaging device using the moving sheet image data. The surface has a calibration pattern different from a pattern configured with a repeating shape pattern as a whole, and provides a calibration method.

[0006] The technology according to the present disclosure is suitable for suppressing distortion of an image obtained by imaging an object moving along a curved movement path.

[0007] Configuration diagram of the inspection system before calibration in the embodiment Configuration diagram of the calibrated inspection system in the embodiment Schematic diagram of calibration Explanation diagram of the movement path and imaging device Explanation diagram of the movement path and imaging device Explanation diagram of distortion of the object in the image Flowchart for explaining calibration Explanation diagram of the calibration sheet relating to the comparison form Explanation diagram of the calibration sheet according to the embodiment Explanation diagram of the calibration sheet according to the embodiment Top view of the calibration sheet in the first to Nth positions Longitudinal cross-sectional view of a cylindrical secondary battery relating to a specific example Front view showing the positive and negative electrodes in an unfolded state Plan view showing the position where the positive electrode tab lead is arranged Flowchart showing part of the manufacturing method of a cylindrical secondary battery

[0008] Embodiments will be described in detail below with reference to the drawings. However, descriptions that are unnecessarily detailed may be omitted. For example, detailed descriptions of already well-known matters or redundant descriptions of substantially identical configurations may be omitted. The accompanying drawings and the following description are provided for the full understanding of the disclosure by those skilled in the art and are not intended to limit the subject matter described in the claims.

[0009] In this embodiment, "orthogonal" does not necessarily mean that the angle between the two directions is exactly 90°. If the angle between the two directions is between 85° and 95°, it is treated as "orthogonal". "Parallel" does not necessarily mean that the two directions are perfectly coincidental. If the angle between the two directions is between -5° and 5°, it is treated as "parallel".

[0010] In the embodiments, "mean" refers to, for example, the arithmetic mean, harmonic mean, geometric mean, trimmed mean, etc. A hypothetical line is a hypothetical line used for illustrative purposes. A rectangle is a concept that includes squares.

[0011] In this embodiment, "shape" includes the concept of "dimensions." Therefore, even if the shapes are similar, they are considered different shapes if their dimensions are different.

[0012] (Embodiment) <Inspection System 901> Figure 1 is a diagram of the inspection system 901A before calibration in the embodiment. Figure 2 is a diagram of the inspection system 901B after calibration in the embodiment. Hereinafter, when inspection system 901A and inspection system 901B are not distinguished, they will simply be referred to as inspection system 901.

[0013] The inspection system 901 includes a travel path 800. The inspection system 901A includes an inspection device 300A before calibration and a calibration sheet 500. The inspection system 901B includes a calibrated inspection device 300B. Hereafter, when inspection devices 300A and 300B are not distinguished, they will simply be referred to as inspection device 300.

[0014] The inspection device 300 includes the determination device 310. The inspection device 300A includes the imaging device 320A before calibration. The inspection device 300B includes the imaging device 320B after calibration. Hereafter, when imaging devices 320A and 320B are not distinguished, they will simply be referred to as imaging device 320. Also, below, imaging device 320B may be referred to as the calibrated imaging device 320B.

[0015] The imaging device 320 has an imaging area 400. The movement path 800 passes through the imaging area 400. The imaging device 320 captures images of a subject in the imaging area 400.

[0016] Inspection system 901A is configured with the imaging system 902A before calibration. Inspection system 901B is configured with the calibration-completed imaging system 902B. Hereafter, unless there is a distinction between imaging system 902A and imaging system 902B, they will simply be referred to as imaging system 902.

[0017] The imaging system 902 includes a travel path 800. The imaging system 902A includes an imaging device 320A before calibration and a calibration sheet 500. The imaging system 902B includes a calibrated imaging device 320B.

[0018] Figure 3 is a schematic diagram of the calibration process. The imaging device 320A becomes the imaging device 320B when it is calibrated using the calibration sheet 500. Through calibration, the imaging system 902A becomes the imaging system 902B, the inspection device 300A becomes the inspection device 300B, and the inspection system 901A becomes the inspection system 901B.

[0019] The imaging device 320 has a memory. Calibration parameters may be stored in the memory. In the calibrated imaging device 320B, the calibration parameters may be used to correct the data representing the raw image generated by the calibrated imaging device 320B through imaging into data representing an image with suppressed distortion.

[0020] Figures 4 and 5 are explanatory diagrams of the movement path 800 and the imaging device 320. Specifically, Figure 4 schematically shows the movement path 800 and the imaging device 320 when observed along the imaging direction 321 of the imaging device 320. Figure 5 schematically shows the movement path 800 and the imaging device 320 when observed along a direction perpendicular to the imaging direction 321.

[0021] As shown in Figure 4, the travel path 800 has a straight section (hereinafter referred to as the straight travel path) 810, a curved section (hereinafter referred to as the curved travel path) 820, and a straight section (hereinafter referred to as the straight travel path) 830 in that order. Specifically, the curved travel path 820 is arc-shaped.

[0022] In this embodiment, the movement paths 810 and 830 are straight when observed along the imaging direction 321. The movement path 820 is curved when observed along the imaging direction 321. Specifically, the movement path 820 is arc-shaped when observed along the imaging direction 321. In this embodiment, the curved movement path 820 is realized by a feed platen.

[0023] The imaging device 320 is positioned such that the imaging area 400 is set on the curved movement path 820. Specifically, the imaging area 400 is set on the movement path 820 and in the direction that the head 325 of the imaging device 320 is facing.

[0024] In this embodiment, the imaging device 320 is a laser imaging device. The head 325 is a laser head. A laser is emitted from the head 325 towards the subject. The subject is imaged by the laser.

[0025] Furthermore, in this embodiment, the imaging device 320 is a three-dimensional imaging device. Specifically, a laser is emitted from the head 325 towards the subject. This provides profile data of the subject in two dimensions, as well as profile data of the subject's height. Here, the height is in a direction perpendicular to the two-dimensional direction.

[0026] After calibration, multiple objects 700 move sequentially along the movement path 800 as follows: The objects 700 move along a straight movement path 810. Next, the objects 700 are transferred from movement path 810 to movement path 820 by the robot arm 851. Next, the objects 700 move along a curved movement path 820. Next, the objects 700 are transferred from movement path 820 to movement path 830 by the robot arm 852. Next, the objects 700 move along a straight movement path 830. In this embodiment, the objects 700 are workpieces.

[0027] <Calibration> Suppose we use the imaging device 320A before calibration to image an object 700 moving along a curved path 820. In this case, distortion may occur in the image obtained by imaging.

[0028] Figure 6 is an explanatory diagram of the distortion of the object 700 in the image. In the example of Figure 6, the object 700 has a grid-like jig. Figure 6(A) shows the grid-like jig of the object 700 in an image obtained by imaging the stationary object 700 with the imaging device 320A. Figure 6(B) shows the grid-like jig of the object 700 in an image obtained by imaging the object 700 as it moves along a curved movement path 820 with the imaging device 320A.

[0029] In image 6(A) of Figure 6, there is no distortion in the grid-like jig. In contrast, in image 6(B) of Figure 6, there is distortion in the grid-like jig. The distortion can be caused by a difference in the path length between the inside and outside of the curved movement path 820.

[0030] In Figure 6(B), the short double arrow 705 indicates the length of the inner portion of the grid-like jig. The long double arrow 706 indicates the length of the outer portion of the grid-like jig. In the image, distortion occurs such that the outer portion of the grid-like jig is longer than the inner portion.

[0031] In this embodiment, the imaging device 320B is obtained by performing calibration on the imaging device 320A. The above-mentioned distortion can be suppressed by calibration. The calibration will be explained below with reference to Figure 7. Figure 7 is a flowchart for explaining the calibration.

[0032] In step S101, the surface of the stationary calibration sheet 500 is imaged in the imaging area 400 by the imaging device 320A. This acquires data representing the image of the surface (hereinafter referred to as stationary sheet image data). If data that can be used as stationary sheet image data exists without this imaging, step S101 can be omitted.

[0033] In step S102, the surface of the calibration sheet 500, which is moving along the curved movement path 820, is imaged in the imaging area 400 by the imaging device 320A. As a result, data representing the image of the surface (hereinafter referred to as the moving sheet image) is acquired.

[0034] In step S103, the imaging device 320A performs calibration using the still sheet image data and the moving sheet image data. This results in the acquisition of the imaging device 320B.

[0035] The comparative form and the calibration sheet according to the embodiment will be described below with reference to Figures 8 to 10. The comparative form is a modified embodiment in which the calibration sheet is changed. Figure 8 is an explanatory diagram of the calibration sheet 550 according to the comparative form. Figures 9 and 10 are explanatory diagrams of the calibration sheet 500 according to the embodiment. Note that the calibration pattern of the calibration sheet 500 is not shown in Figure 10.

[0036] Figure 8(A) shows the surface of the calibration sheet 550 in an image acquired by imaging the surface of the stationary calibration sheet 550 with the imaging device 320A. As shown in Figure 8(A), the calibration pattern on the surface of the calibration sheet 550 in the comparative form is a pattern composed of repeating shapes throughout. Specifically, this calibration pattern is a checkerboard pattern.

[0037] Figure 8(B) shows the surface of the calibration sheet 550 in an image acquired by imaging the surface of the calibration sheet 550 as it moves along the curved movement path 820 using the imaging device 320A. As shown in Figure 8(B), distortion is observed on the surface of the calibration sheet 550 in the image. This distortion may be caused by a difference in the path length between the inside and outside of the curved movement path 820. In Figure 8(B), auxiliary lines 553 are added to indicate the distortion.

[0038] Generally, commercially available imaging devices are often designed to capture subjects moving in a straight line. When using an imaging device designed for straight-line movement to capture a subject moving along a straight path, the subject is less likely to be distorted in the image. However, when using an imaging device designed for straight-line movement to capture a subject moving along a curved path, the subject is more likely to be distorted in the image.

[0039] In the comparative configuration, the imaging device 320A uses image data representing the image in Figure 8(A) to identify the coordinates of each feature point on the surface of the calibration sheet 550 in the image. The imaging device 320A uses image data representing the image in Figure 8(B) to identify the coordinates of each feature point on the surface of the calibration sheet 550 in the image. The imaging device 320A acquires calibration parameters based on the difference between the coordinates of each feature point in the image in Figure 8(A) and the coordinates of each feature point in the image in Figure 8(B). Using the acquired calibration parameters, the imaging device 320A is calibrated to the imaging device 320B.

[0040] Feature points are distinctive areas in an image used for calibration. Feature points can be set based on known techniques in the field of imaging device calibration. For example, feature points may be the boundary between the background and the pattern. Alternatively, feature points may be edges, corners, etc. In the example of the checkerboard pattern in Figure 8, the feature points may correspond to grid points.

[0041] In the comparative configuration, a calibrated imaging device can be obtained as described above. However, in the comparative configuration, it is difficult to perform calibration that sufficiently suppresses distortion. Specifically, as described above, in the comparative configuration, the calibration pattern on the surface of the calibration sheet 550 is a pattern composed entirely of repeating shapes. The repeating shapes appear at a constant repeating pitch. Therefore, feature points appear at regular intervals. It is not possible to perform calibration that suppresses distortion with an accuracy below this interval.

[0042] Although it might seem that the problem could be solved by narrowing the repetition pitch of the comparison pattern, this is not the case in reality. This is because there are limitations based on the performance of the imaging device 320. Specifically, due to the resolution limitations of the imaging device 320, simply narrowing the repetition pitch alone would cause problems in identifying feature points and make calibration difficult.

[0043] In contrast, as shown in FIGS. 9 and 10, the calibration pattern on the surface of the calibration sheet 500 according to the embodiment is different from a pattern formed by repeating a pattern as a whole. Therefore, it is possible to avoid calibration problems caused by the repeating shape appearing at a constant repetition pitch. Specifically, in the calibration pattern on the surface of the calibration sheet 500, the intervals between feature points can be various. In calibration, among the various intervals, feature points with a narrow interval within the range possible under the resolution limitations of the imaging device 320 can be used. Therefore, high-precision calibration can be achieved within the range allowed by the resolution of the imaging device 320. Examples of patterns formed by repeating a pattern as a whole include a checkerboard pattern, a dot pattern arranged in a grid, a stripe pattern, a check pattern, and the like.

[0044] Specifically, in the embodiment, the imaging device 320A specifies the coordinates of each feature point on the surface of the calibration sheet 500 in the image represented by the still sheet image data. The imaging device 320A specifies the coordinates of each feature point on the surface of the calibration sheet 500 in the image represented by the moving sheet image data. The imaging device 320A acquires calibration parameters based on the differences between the coordinates of each feature point in the image represented by the still sheet image data and the coordinates of each feature point in the image represented by the moving sheet image data. Using the acquired calibration parameters, the imaging device 320A is calibrated to the imaging device 320B.

[0045] Hereinafter, the terms "first partial region", "second partial region", "third partial region", "fourth partial region", "fifth partial region", and "sixth partial region" are used. These terms are defined as follows: - The first partial region is a square region with a side length 200 times the imaging resolution of the imaging device 320. - The second partial region is a square region with a side length of 10 mm. - The third partial region is a square region with a side length 100 times the imaging resolution of the imaging device 320. - The fourth partial region is a square region with a side length of 5 mm. - The fifth partial region is a square region with a side length 60 times the imaging resolution of the imaging device 320. - The sixth partial region is a square region with a side length of 3 mm.

[0046] The imaging resolution of the imaging device 320 refers to the average of the vertical resolution of the imaging device 320 and the horizontal resolution of the imaging device 320. The vertical resolution of the imaging device 320 is the value obtained by dividing the vertical field size of the imaging device 320 by the number of pixels in the vertical direction of the imaging device 320. The horizontal resolution of the imaging device 320 is the value obtained by dividing the horizontal field size of the imaging device 320 by the number of pixels in the horizontal direction of the imaging device 320. The vertical direction and the horizontal direction are directions orthogonal to the imaging direction 321. The vertical direction and the horizontal direction are directions orthogonal to each other. The imaging resolution may also be referred to as pixel resolution.

[0047] For example, consider the following example: - The vertical field of view of the imaging device 320 is 40 mm. - The horizontal field of view of the imaging device 320 is 60 mm. - The number of pixels in the vertical direction of the imaging device 320 is 500 pixels. - The number of pixels in the horizontal direction of the imaging device 320 is 800 pixels.

[0048] In this example, when adopting the arithmetic mean as the average: - The vertical resolution of the imaging device 320 is 40 mm ÷ 500 pixels = 0.08 mm / pixel, - The horizontal resolution of the imaging device 320 is 60 mm ÷ 800 pixels = 0.075 mm / pixel, - The imaging resolution of the imaging device 320 is (0.08 mm / pixel + 0.075 mm / pixel) ÷ 2 = 0.0775 mm / pixel.

[0049] In Figure 9, the dashed-dot line represents the first subregion. The dashed-dot line represents the second subregion. The first subregion is denoted by reference numeral 501. The second subregion is denoted by reference numeral 502.

[0050] As shown in Figure 9, in this embodiment, the surface of the calibration sheet 500 does not have two first partial regions 501 with identical pattern shapes. This is advantageous from the viewpoint of achieving high-precision calibration within the range permitted by the resolution of the imaging device 320.

[0051] As shown in Figure 9, in this embodiment, the surface of the calibration sheet 500 does not have two second partial regions 502 with identical pattern shapes. This is advantageous from the viewpoint of achieving high-precision calibration within the range permitted by the resolution of the imaging device 320.

[0052] Specifically, in the embodiment, the surface of the calibration sheet 500 does not have two third partial regions with identical pattern shapes. The surface of the calibration sheet 500 does not have two fourth partial regions with identical pattern shapes.

[0053] More specifically, in the embodiment, the surface of the calibration sheet 500 does not have two fifth partial regions with identical pattern shapes. The surface of the calibration sheet 500 does not have two sixth partial regions with identical pattern shapes.

[0054] Here, we will explain the "two first partial regions 501" in the statement, "There are no two first partial regions 501 with identical pattern shapes on the surface of the calibration sheet 500." The concept of "two first partial regions 501" is intended to encompass both two regions that are spaced apart from each other, as shown in the upper left of Figure 9, and two regions that partially overlap, as shown in the lower left of Figure 9. The same applies to "two second partial regions 502," "two third partial regions," "two fourth partial regions," "two fifth partial regions," and "two sixth partial regions."

[0055] As shown in Figure 10, in this embodiment, on the surface of the calibration sheet 500, adjacent feature points 531, 532, and 533 are arranged in this order on the first virtual line 511. On the surface of the calibration sheet 500, adjacent feature points 534, 535, and 6th feature points 536 are arranged in this order on the second virtual line 512. The first virtual line 511 and the second virtual line 512 are orthogonal to each other. The spacing L12 between the first feature point 531 and the second feature point 532 is different from the spacing L23 between the second feature point 532 and the third feature point 533. The spacing L45 between the fourth feature point 534 and the fifth feature point 535 is different from the spacing L56 between the fifth feature point 535 and the sixth feature point 536. With this configuration, in calibration, it is easy to use feature points with narrow spacings among various spacings, within the range possible under the resolution constraints of the imaging device 320. In the example shown in Figure 10, the surface of the calibration sheet 500 is rectangular. The first virtual line 511 is parallel to one of two adjacent sides of the rectangle. The second virtual line 512 is parallel to the other of two adjacent sides of the rectangle. The first feature point 531, the second feature point 532, the third feature point 533, the fourth feature point 534, the fifth feature point 535, and the sixth feature point 536 can be identified by the imaging device 320.

[0056] As shown in Figure 9, in this embodiment, the calibration pattern on the surface of the calibration sheet 500 is a random pattern. Therefore, variations are likely to occur in the spacing between feature points in the calibration pattern. For this reason, in calibration, it is easier to use feature points that are spaced at narrow intervals, within the limits of the resolution constraints of the imaging device 320, among the various intervals. A random pattern is a pattern that does not have regularity and may have patterns with shapes that do not have regularity.

[0057] As shown in Figures 4 and 5, in this embodiment, the movement path 820 is curved along a movement plane 850 that is perpendicular to the imaging direction 321. Imaging of the surface of the calibration sheet 500 by the imaging device 320A is performed when the calibration sheet 500 is moving along the movement path 820 and the surface of the calibration sheet 500 is parallel to the movement plane 850. Moving sheet image data is acquired by such imaging. As a result, distortion originating from the curvature of the movement path 820 is likely to appear in the image represented by the moving sheet image data. This is beneficial when performing calibration in a way that suppresses distortion originating from the curvature of the movement path 820.

[0058] In the first and second examples below, the calibration sheet 500 is imaged multiple times for calibration purposes. In the following explanation, N is a natural number greater than or equal to 2. Specifically, in one example, N is between 2 and 100, and in another specific example, N is between 5 and 50.

[0059] In the first and second examples, for all natural numbers J satisfying 1 ≤ J ≤ N, a calibration sheet 500 of the Jth attitude while moving along a curved path 820 is used. Ｊ By imaging the surface of the sheet with the imaging device 320A, the Jth angle image data is obtained as moving sheet image data. This provides the first to Nth angle image data. Calibration sheet 500 for the first to Nth orientations. １ from 500 Ｎ The surfaces are arranged at different angles to each other when observed along the imaging direction 321 of the imaging device 320A. Figure 11 shows the calibration sheet 500 for the first to Nth orientations. １ from 500 Ｎ This is a top view.

[0060] In the first and second examples, for all natural numbers J satisfying 1 ≤ J ≤ N, the Jth calibration parameter is generated using the Jth angle image data and the corresponding still sheet image data. This generates the first to Nth calibration parameters. The first to Nth calibration parameters correspond to the first to Nth poses, respectively. As mentioned above, the still sheet image data may be acquired by imaging or may be existing data.

[0061] In the first example, the imaging device 320A generates a composite calibration parameter using the first to the Nth calibration parameters. The imaging device 320A then performs calibration using the composite calibration parameter. In this way, calibration of stable quality can be performed. The effect of stabilizing the calibration quality can be suitably exhibited, for example, when the calibration pattern on the surface of the calibration sheet 500 is a random pattern. The composite calibration parameter is, for example, the average of the first to the Nth calibration parameters.

[0062] In the second example, sample image data representing the image of the test sample is obtained by imaging the test sample as it moves along the curved movement path 820 using the imaging device 320A. For all natural numbers J satisfying 1 ≤ J ≤ N, the imaging device 320A generates the J-th corrected image data by correcting the sample image data using the J-th calibration parameter. This generates the first to Nth corrected image data. The first to Nth corrected image data corresponds to the first to Nth poses, respectively. The terminal displays the images represented by the first to Nth corrected image data and accepts from the user a selection of which of the first to Nth calibration parameters to use as the calibration parameter for performing calibration of the imaging device 320A. In the second example, the first to Nth corrected image data could each be the image data that would have been obtained if the test sample moving along the curved movement path 820 had been imaged by the imaging device 320 calibrated using the first to Nth calibration parameters. The user can visually confirm how well the first to Nth calibration parameters suppress distortion by viewing the images represented by the first to Nth corrected image data displayed on the terminal. While making this confirmation, the user can input which of the first to Nth calibration parameters to adopt into the terminal. The terminal may be included in the imaging device 320, or it may communicate with the imaging device 320. The terminal may display the image represented by the sample image data along with the image represented by the first to Nth corrected image data.

[0063] <Manufacturing of Imaging System 902B> As can be understood from the above explanation, calibration parameters can be acquired using moving sheet image data by the imaging device 320A. By storing the calibration parameters in the memory of the imaging device 320A, a calibrated imaging device 320B is obtained.

[0064] <Imaging, inspection, and product manufacturing using the calibrated imaging device 320B> As described above, the calibration is performed to obtain the calibrated imaging device 320B. The object 700 moving along the curved movement path 820 is imaged by the calibrated imaging device 320B.

[0065] Image data representing the object 700 is acquired by imaging the object 700 as it moves along the curved movement path 820 using the imaging device 320B. The object 700 is inspected by the inspection device 300B using the object image data. The inspection of the object 700 includes determining whether the object 700 passes or fails based on the shape of the object 700 in the image represented by the object image data using the determination device 310. Specifically, the shape is a three-dimensional shape.

[0066] The above inspection can be incorporated into the product manufacturing process. Specifically, the object 700 is manufactured and then subjected to the above inspection. The object 700 may be a finished product or a material to be processed into a product.

[0067] In one example, the product is a battery. In a specific example, the product is a cylindrical rechargeable battery. In this specific example, the cylindrical rechargeable battery may include at least one tab lead.

[0068] <Cylindrical Secondary Battery> The following describes an example of the configuration of a cylindrical secondary battery related to the above specific example. For detailed configurations that can be adopted for cylindrical secondary batteries, please refer to Patent Document 2, etc.

[0069] Figure 12 is a longitudinal cross-sectional view of a cylindrical secondary battery 10 according to a specific example. In the cylindrical secondary battery 10 shown in Figure 12, the electrode body 14 and electrolyte (not shown) are housed in an outer casing 15. The electrode body 14 has a wound structure in which a strip-shaped positive electrode 11 and a strip-shaped negative electrode 12 are wound around a separator 13. For the sake of explanation, the side with the sealing body 16 will be referred to as "upper" and the bottom side of the outer casing 15 will be referred to as "lower".

[0070] The sealing body 16 seals the opening at the upper end of the outer casing 15, thereby sealing the inside of the cylindrical secondary battery 10. Insulating plates 17 and 18 are provided above and below the electrode body 14, respectively. The positive electrode tab lead 19 extends vertically through a through hole in the insulating plate 17 and connects the filter 22, which is the bottom plate of the sealing body 16, to the positive electrode 11 contained in the electrode body 14. This connects the positive electrode 11 to the sealing body 16, and in the cylindrical secondary battery 10, the cap 26, which is the top plate of the sealing body 16 electrically connected to the filter 22, becomes the positive electrode terminal. The positive electrode tab lead 19 is, for example, an aluminum tab lead. On the other hand, the negative electrode tab lead 20 extends to the bottom side of the outer casing 15 through a through hole in the insulating plate 18 and is welded to the bottom inner surface of the outer casing 15. This connects the negative electrode 12 to the outer casing 15, and in the cylindrical secondary battery 10, the outer casing 15 becomes the negative electrode terminal. The negative electrode tab lead 20 is, for example, a nickel tab lead.

[0071] Multiple positive electrode tab leads 19 are derived from the electrode body 14. In the illustrated example, there are three positive electrode tab leads 19 derived from the electrode body 14. However, the number of positive electrode tab leads derived from the electrode body 14 may be one, two, or four or more. The positive electrode tab leads 19 derived from the electrode body 14 may be directly connected to the sealing body 16, or they may be connected to the sealing body 16 via a known current collector. Furthermore, the manner in which the negative electrode 12 and the outer casing 15 are connected is not particularly limited, and they may be connected by multiple negative electrode tab leads 20.

[0072] The outer casing 15 is a bottomed cylindrical shape. The outer casing 15 is, for example, a metal outer can. A gasket 27 is provided between the outer casing 15 and the sealing body 16 to ensure airtightness inside the cylindrical secondary battery 10. The outer casing 15 has grooves 21 that support the sealing body 16, which are formed, for example, by pressing the side surface from the outside. The grooves 21 are preferably formed in an annular shape along the circumferential direction of the outer casing 15, and their upper surface supports the sealing body 16.

[0073] The sealing body 16 has a filter 22, a lower valve body 23, an insulating member 24, an upper valve body 25, and a cap 26, which are stacked in order from the electrode body 14 side. Each component constituting the sealing body 16 has, for example, a disc shape or a ring shape, and each component except the insulating member 24 is electrically connected to one another. The lower valve body 23 and the upper valve body 25 are connected to each other at their respective centers, with the insulating member 24 interposed between their respective peripheries. If the internal pressure of the battery rises due to abnormal heat generation, for example, the lower valve body 23 may rupture, causing the upper valve body 25 to bulge towards the cap 26 and separate from the lower valve body 23, thereby interrupting the electrical connection between the two. If the internal pressure rises further, the upper valve body 25 may rupture, and gas may be discharged from the opening 26a of the cap 26.

[0074] Figure 13 is a front view showing the positive electrode 11 and negative electrode 12, which constitute the electrode body 14 of the cylindrical secondary battery 10 of Figure 12, in an unfolded state. The positive electrode 11 has a positive electrode current collector 30 and a positive electrode mixture layer 32 formed on the surface of the positive electrode current collector 30, and the negative electrode 12 has a negative electrode current collector 40 and a negative electrode mixture layer 42 formed on the surface of the negative electrode current collector 40.

[0075] As shown in Figure 13, the positive electrode 11 has multiple positive electrode current collector exposed portions 34 at its upper end along its longitudinal direction, where the positive electrode current collector 30 is exposed, and a positive electrode mixture layer 32 exists between the positive electrode current collector exposed portions 34. One of the positive electrode tab leads 19 is connected to each of the positive electrode current collector exposed portions 34. By connecting the positive electrode tab leads 19 and the positive electrode 11 in this manner, the area of ​​the positive electrode mixture layer 32 can be increased, thereby improving the output characteristics of the cylindrical secondary battery 10. On the other hand, the negative electrode 12 has a negative electrode current collector exposed portion 44 at its longitudinal winding end, where the negative electrode current collector 40 is exposed. A negative electrode tab lead 20 is connected to the negative electrode current collector exposed portion 44.

[0076] Figure 14 is a plan view showing the positions where the positive electrode tab leads 19 are arranged on the upper surface of the electrode body 14. In the example shown in Figure 14, the positive electrode tab leads 19 are arranged at equal angles, as shown in Figure 14.

[0077] Figure 15 is a flowchart showing a part of the manufacturing method for the cylindrical secondary battery 10.

[0078] In step S201, the positive electrode 11 is manufactured. The positive electrode 11 is obtained, for example, by applying a positive electrode composite slurry containing a positive electrode active material, a conductive material, and a binder to both sides of a positive electrode current collector, drying the coating, and then rolling it.

[0079] In step S202, the negative electrode 12 is manufactured. The negative electrode 12 is obtained, for example, by applying a negative electrode mixture slurry containing a negative electrode active material, a binder, a thickener, and water to both sides of a negative electrode current collector, drying the coating, and then rolling it.

[0080] In step S203, multiple positive electrode tab leads 19 are connected to the positive electrode 11. Specifically, one positive electrode tab lead 19 is connected to each of the exposed portions 34 of the positive electrode current collector.

[0081] In step S204, the negative electrode tab lead 20 is connected to the negative electrode 12. Specifically, the negative electrode tab lead 20 is connected to the exposed portion 44 of the negative electrode current collector.

[0082] In step S205, the positive electrode 11 and the negative electrode 12 are stacked via a separator 13, and the stacked material is wound. This results in an electrode body 14 with multiple positive electrode tab leads 19 extending from it.

[0083] In step S206, the wound electrode body 14 and electrolyte are housed in the outer casing 15. This results in the object 700.

[0084] In step S207, the calibrated imaging device 320B images the object 700 as it moves along the curved path 820. The imaging acquires object image data representing the object 700. The image represents the shape of the object 700. Specifically, the shape is a three-dimensional shape.

[0085] In step S208, the object 700 is inspected by the inspection device 300B using object image data. The inspection of the object 700 includes the determination of whether the object 700 passes or fails based on the shape of the object 700 in the image represented by the object image data by the determination device 310. If the object 700 is determined to pass, the process proceeds to step S209. If the object 700 is determined to fail, the process proceeds to step S210.

[0086] In this specific example, the pass / fail determination includes determining the pass / fail status of the positions of the multiple positive electrode tab leads 19 based on the shape of the object 700 in the image represented by the object image data. In this context, the positions of the multiple positive electrode tab leads 19 may be relative to the central axis of the outer casing 15. If the positions of the multiple positive electrode tab leads 19 are within the appropriate range, the object 700 will not be judged as unacceptable due to the positions of the multiple positive electrode tab leads 19. If the positions of the multiple positive electrode tab leads 19 are outside the appropriate range, the object 700 will be judged as unacceptable due to the positions of the multiple positive electrode tab leads 19.

[0087] In the context described above, the position of the positive electrode tab lead 19 is a concept that includes the orientation of the positive electrode tab lead 19. In this specific example, the object image data represents the three-dimensional shape of the object 700. Therefore, in addition to the two-dimensional profile of the positive electrode tab lead 19, the height profile of the positive electrode tab lead 19 can be recognized from the object image data. Based on these profiles, the orientation of the positive electrode tab lead 19 can be recognized.

[0088] Furthermore, in this specific example, the pass / fail determination includes determining the pass / fail status of the dimensions of the multiple positive electrode tab leads 19 based on the dimensions of the object 700 represented by the object image data. In this context, the dimensions of the multiple positive electrode tab leads 19 may be relative dimensions to the dimensions of the outer casing 15. If the dimensions of the multiple positive electrode tab leads 19 are within the appropriate range, the object 700 will not be judged as unacceptable due to the dimensions of the multiple positive electrode tab leads 19. If the dimensions of the multiple positive electrode tab leads 19 are outside the appropriate range, the object 700 will be judged as unacceptable due to the dimensions of the multiple positive electrode tab leads 19.

[0089] If the object 700 is determined to be acceptable (in the case of "acceptable" in step S208), the object 700 is processed into a cylindrical secondary battery 10 in a subsequent process (step S209). For example, the subsequent process includes connecting a plurality of positive electrode tab leads 19 to a filter 22. On the other hand, if the object 700 is determined to be unacceptable (in the case of "unacceptable" in step S208), the object 700 that has been determined to be unacceptable is removed (step S210). Specifically, the object 700 that has been determined to be unacceptable is transported by a robot arm 855 (see Figures 4 and 5) to an unshown discharge lane.

[0090] In this specific example, the fabrication of the object 700 is carried out sequentially from step S201 to step S206. The obtained object 700 is sorted based on imaging and pass / fail judgment in steps S207 and S208, and is processed into a cylindrical secondary battery 10 (step S209) or discharged (step S210).

[0091] In the example shown in the flowchart of Figure 15, the object being inspected, 700, is to be processed into a product. The cylindrical secondary battery 10 is the product.

[0092] In another example, the object being inspected, 700, is a cylindrical secondary battery 10, which is a product.

[0093] (Note) This disclosure discloses the following technologies.

[0094] (Technology 1) A calibration method comprising: acquiring moving sheet image data representing an image of the surface by imaging the surface of a calibration sheet moving along a curved path using an imaging device; and performing calibration of the imaging device using the moving sheet image data, wherein the surface has a calibration pattern different from a pattern composed of repeating shapes as a whole.

[0095] (Technical 2) The calibration method according to Technical 1, wherein, on the surface, a first feature point, a second feature point, and a third feature point are arranged in this order on a first virtual line, a fourth feature point, a fifth feature point, and a sixth feature point are arranged in this order on a second virtual line, the first virtual line and the second virtual line are orthogonal to each other, the interval between the first feature point and the second feature point is different from the interval between the second feature point and the third feature point, and the interval between the fourth feature point and the fifth feature point is different from the interval between the fifth feature point and the sixth feature point.

[0096] (Technical 3) The calibration method according to Technical 1 or 2, wherein the surface does not have two first partial regions having the same pattern shape, and the first partial region is a square region whose side length is 200 times the imaging resolution of the imaging device.

[0097] (Technical 4) The calibration method according to any one of Technical 1 to 3, wherein the surface does not have two second partial regions having the same pattern shape, and the second partial region is a square region with a side length of 10 mm.

[0098] (Technical 5) The calibration method according to any one of Technical 1 to 4, wherein the calibration pattern is a random pattern.

[0099] (Technical 6) The calibration method according to any one of Technical 1 to 5, wherein the movement path is curved along a movement plane perpendicular to the imaging direction, and the method includes acquiring moving sheet image data by imaging the surface of the calibration sheet with the imaging device while it is moving along the movement path and its surface is parallel to the movement plane.

[0100] (Technical 7) A calibration method according to any one of Technical 1 to 6, comprising: when N is a natural number of 2 or more, acquiring the Jth angle image data as moving sheet image data by imaging the surface of the calibration sheet in the Jth orientation as it moves along the movement path with the imaging device for all natural numbers J satisfying 1 ≤ J ≤ N; generating the Jth calibration parameter using the J angle image data for all natural numbers J satisfying 1 ≤ J ≤ N; generating a composite calibration parameter using the first to Nth calibration parameters; and performing the calibration of the imaging device using the composite calibration parameter, wherein the surfaces of the calibration sheet in the first to Nth orientations are arranged at different angles to each other when observed along the imaging direction of the imaging device.

[0101] (Technical 8) A calibration method according to any one of Technical 1 to 6, comprising: acquiring sample image data representing an image of a test sample by imaging the test sample as it moves along the movement path using the imaging device; acquiring the Jth angle image data as moving sheet image data by imaging the surface of the calibration sheet in the Jth orientation as it moves along the movement path using the imaging device for all natural numbers J satisfying 1 ≤ J ≤ N, where N is a natural number of 2 or more; generating the Jth calibration parameter using the J angle image data for all natural numbers J satisfying 1 ≤ J ≤ N; generating the Jth corrected image data by correcting the sample image data using the J calibration parameter for all natural numbers J satisfying 1 ≤ J ≤ N; and accepting a selection of which of the first to Nth calibration parameters to adopt as calibration parameters for performing the calibration of the imaging device while displaying the image represented by the first to Nth corrected image data, wherein the surfaces of the calibration sheet in the first to Nth orientations are arranged at different angles to each other when observed along the imaging direction of the imaging device.

[0102] (Technical 9) An imaging method comprising: obtaining a calibrated imaging device by performing a calibration method described in any one of Technical 1 to 8; and imaging an object moving along a movement path with the calibrated imaging device.

[0103] (Technical 10) An inspection method comprising: acquiring object image data representing an image of an object by imaging an object moving along a movement path using the imaging method described in Technical 9; and inspecting the object using the object image data.

[0104] (Technical 11) The inspection method according to Technical 10, wherein the inspection of the object includes determining whether the object is acceptable or unacceptable based on the shape of the object in the image represented by the image data of the object.

[0105] (Technical 12) A method for manufacturing a product, comprising inspecting an object by performing the inspection method described in Technical 10 or 11, wherein the object is the product or is to be processed into the product.

[0106] (Technical 13) A method for manufacturing an imaging system, comprising: acquiring moving sheet image data representing an image of the surface of a calibration sheet moving along a curved path by imaging the surface of the calibration sheet with an imaging device; acquiring calibration parameters using the moving sheet image data; and storing the calibration parameters in the memory of the imaging device, wherein the surface has a calibration pattern different from a pattern composed of repeating shapes as a whole.

[0107] (Technical 14) An imaging system comprising: a curved movement path; an imaging device for imaging an object moving along the movement path; and a calibration sheet for the imaging device, wherein the surface of the calibration sheet has a calibration pattern different from a pattern composed of repeating shapes.

[0108] (Technical 15) An inspection system comprising the imaging system described in Technical 14, wherein the inspection device is configured using the imaging device of the imaging system, the imaging device acquires object image data representing an image of the object by imaging the object as it moves along a movement path, and the inspection device inspects the object using the object image data.

[0109] (Technical 16) An imaging system comprising a curved movement path and a calibrated imaging device that images an object moving along the movement path, wherein the calibrated imaging device includes a memory storing calibration parameters, the calibration parameters are obtained using a calibration sheet, and the surface of the calibration sheet has a calibration pattern different from a pattern composed of repeating shapes.

[0110] (Technical 17) An inspection system comprising the imaging system described in Technical 16, wherein the inspection device is configured using a calibrated imaging device of the imaging system, the calibrated imaging device acquires object image data representing an image of an object by imaging an object moving along a movement path, and the inspection device inspects the object using the object image data.

[0111] Some features of technologies 1 to 17 may be omitted. Furthermore, features of technologies 1 to 17 may be combined in any way. For example, the following technologies 1x, 13x, 14x, and 16x can be constructed.

[0112] (Technology 1x) A calibration method comprising: acquiring moving sheet image data representing an image of the surface by imaging the surface of a calibration sheet moving along a curved path with an imaging device; and performing calibration of the imaging device using the moving sheet image data, wherein, on the surface, a first feature point, a second feature point, and a third feature point are arranged in this order on a first virtual line, adjacent to each other; a fourth feature point, a fifth feature point, and a sixth feature point are arranged in this order on a second virtual line, adjacent to each other; the first and second virtual lines are orthogonal to each other; the spacing between the first and second feature points is different from the spacing between the second and third feature points; and the spacing between the fourth and fifth feature points is different from the spacing between the fifth and sixth feature points.

[0113] (Technical 13x) A method for manufacturing an imaging system, comprising: acquiring moving sheet image data representing an image of the surface by imaging the surface of a calibration sheet moving along a curved path with an imaging device; acquiring calibration parameters using the moving sheet image data; and storing the calibration parameters in the memory of the imaging device, wherein, on the surface, a first feature point, a second feature point, and a third feature point are arranged in this order adjacent to each other on a first virtual line; on the surface, a fourth feature point, a fifth feature point, and a sixth feature point are arranged in this order adjacent to each other on a second virtual line; the first virtual line and the second virtual line are orthogonal to each other; the spacing between the first feature point and the second feature point is different from the spacing between the second feature point and the third feature point; and the spacing between the fourth feature point and the fifth feature point is different from the spacing between the fifth feature point and the sixth feature point.

[0114] (Technical 14x) An imaging system comprising: a curved movement path; an imaging device for imaging an object moving along the movement path; and a calibration sheet for the imaging device, wherein on the surface of the calibration sheet, adjacent first feature points, second feature points, and third feature points are arranged in this order on a first virtual line; on the surface, adjacent fourth feature points, fifth feature points, and sixth feature points are arranged in this order on a second virtual line; the first and second virtual lines are orthogonal to each other; the spacing between the first and second feature points is different from the spacing between the second and third feature points; and the spacing between the fourth and fifth feature points is different from the spacing between the fifth and sixth feature points.

[0115] (Technical 16x) An imaging system comprising: a curved movement path; and a calibrated imaging device for imaging an object moving along the movement path, wherein the calibrated imaging device includes a memory storing calibration parameters, the calibration parameters are obtained using a calibration sheet, and on the surface of the calibration sheet, a first feature point, a second feature point, and a third feature point are arranged in this order on a first virtual line, adjacent to each other; on the surface, a fourth feature point, a fifth feature point, and a sixth feature point are arranged in this order on a second virtual line, the first and second virtual lines are orthogonal to each other; the spacing between the first and second feature points is different from the spacing between the second and third feature points; and the spacing between the fourth and fifth feature points is different from the spacing between the fifth and sixth feature points.

[0116] According to the technology disclosed herein, distortion of images obtained by imaging an object moving along a curved path can be suppressed.

Claims

By imaging the surface of the calibration sheet as it moves along a curved path using an imaging device, moving sheet image data representing the image of the surface is obtained. This includes performing calibration of the imaging device using the moving sheet image data, The aforementioned surface has a calibration pattern different from a pattern composed of repeating shapes throughout. Calibration method. 　 On the aforementioned surface, the first feature point, the second feature point, and the third feature point, which are adjacent to each other, are arranged in this order on the first virtual line. On the aforementioned surface, the fourth, fifth, and sixth feature points, which are adjacent to each other, are arranged in this order on the second virtual line. The first virtual line and the second virtual line are orthogonal to each other. The interval between the first feature point and the second feature point is different from the interval between the second feature point and the third feature point. The interval between the fourth feature point and the fifth feature point is different from the interval between the fifth feature point and the sixth feature point. The calibration method according to claim 1. 　 The aforementioned surface does not have two first subregions with identical pattern shapes. The first sub-region is a square region whose side length is 200 times the imaging resolution of the imaging device. The calibration method according to claim 1. 　 The aforementioned surface does not have two second subregions with identical pattern shapes. The aforementioned second sub-region is a square region with a side length of 10 mm. The calibration method according to claim 1. 　 The calibration pattern is a random pattern. The calibration method according to claim 1. 　 The aforementioned movement path is curved along a movement plane perpendicular to the imaging direction. This includes acquiring moving sheet image data by imaging the surface of the calibration sheet with the imaging device while it is moving along the aforementioned movement path and the surface is parallel to the moving plane. The calibration method according to claim 1. 　 When N is a natural number greater than or equal to 2, For all natural numbers J satisfying 1 ≤ J ≤ N, the surface of the calibration sheet at the Jth orientation while moving along the aforementioned movement path is imaged by the imaging device to obtain the Jth angle image data as the moving sheet image data. For all natural numbers J satisfying 1 ≤ J ≤ N, the J-th calibration parameter is generated using the J-angle image data, Using the first to the Nth calibration parameters described above, a composite calibration parameter is generated, This includes performing the calibration of the imaging device using the composite calibration parameters, The surfaces of the calibration sheets in the first to Nth orientations are arranged at different angles to each other when observed along the imaging direction of the imaging device. The calibration method according to claim 1. 　 By capturing images of the test sample as it moves along the aforementioned movement path using the imaging device, sample image data representing the image of the test sample is obtained. When N is a natural number greater than or equal to 2, For all natural numbers J satisfying 1 ≤ J ≤ N, the surface of the calibration sheet at the Jth orientation while moving along the aforementioned movement path is imaged by the imaging device to obtain the Jth angle image data as the moving sheet image data. For all natural numbers J satisfying 1 ≤ J ≤ N, the J-th calibration parameter is generated using the J-angle image data, For all natural numbers J satisfying 1 ≤ J ≤ N, the sample image data is corrected using the J calibration parameter to generate the J-corrected image data. The system includes, while displaying the image represented by the first to nth corrected image data, accepting a selection of which of the first to nth calibration parameters to adopt as the calibration parameter for performing the calibration of the imaging device, The surfaces of the calibration sheets in the first to Nth orientations are arranged at different angles to each other when observed along the imaging direction of the imaging device. The calibration method according to claim 1. 　 A calibrated imaging device is obtained by performing the calibration method described in claim 1, This includes imaging an object moving along a movement path using the calibrated imaging device, Imaging method. 　 By imaging an object moving along a movement path using the imaging method described in claim 9, object image data representing an image of the object is obtained, This includes inspecting the object using the object image data, Testing method. 　 Inspecting the object includes determining whether the object is acceptable or unacceptable based on the shape of the object in the image represented by the object image data. The inspection method according to claim 10. 　 A method for manufacturing a product, This includes inspecting an object by performing the inspection method described in claim 10, The aforementioned object is the aforementioned product, or something that should be processed into the aforementioned product. Manufacturing method. 　 By imaging the surface of the calibration sheet as it moves along a curved path using an imaging device, moving sheet image data representing the image of the surface is obtained. The calibration parameters are obtained using the aforementioned moving sheet image data, This includes storing the calibration parameters in the memory of the imaging device, The aforementioned surface has a calibration pattern different from a pattern composed of repeating shapes throughout. A method for manufacturing an imaging system. 　 A winding travel path, An imaging device for imaging an object moving along the aforementioned movement path, The device comprises a calibration sheet for the imaging device, The surface of the calibration sheet has a calibration pattern different from a pattern composed of repeating shapes throughout. Imaging system. 　 An inspection system comprising the imaging system described in claim 14, An inspection device is configured using the imaging device of the aforementioned imaging system. The imaging device acquires object image data representing an image of an object by imaging the object as it moves along the movement path. The inspection device inspects the object using the object image data. Inspection system. 　 A winding travel path, The system includes a calibrated imaging device that images an object moving along the aforementioned movement path, The aforementioned calibrated imaging device includes a memory in which calibration parameters are stored. The aforementioned calibration parameters were obtained using a calibration sheet. The surface of the calibration sheet has a calibration pattern different from a pattern composed of repeating shapes throughout. Imaging system. 　 An inspection system comprising the imaging system described in claim 16, The inspection apparatus is configured using the calibrated imaging device of the aforementioned imaging system. The calibrated imaging device acquires object image data representing an image of an object by imaging the object as it moves along the movement path. The inspection device inspects the object using the object image data. Inspection system.

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