Inspection device and inspection method

Abstract

An inspection device 1 inspects the fixation state of a first member 4 and a second member 6 of a to-be-inspected object 2 that includes the first member 4 and the second member 6, which are fixed to each other. The first member 4 and the second member 6 of the to-be-inspected object 2 are fixed to each other by fitting a leading end portion of the first member 4 into a groove provided in the outer peripheral surface of the second member 6, which has a cylindrical shape. The inspection device 1 comprises: an axicon mirror 16 that has an opening 26 into which the to-be-inspected object 2 is inserted and a mirror surface 28 extending outside the opening 26 and surrounding the outer peripheral surface of the to-be-inspected object 2 that has been inserted into the opening 26; and a camera 18 that captures mirror images of the groove and the leading end portion that are shown on the mirror surface 28.

Description

Inspection device and inspection method

[0001] The present disclosure relates to an inspection apparatus and an inspection method.

[0002] Patent Document 1 discloses a technique for visually inspecting the state of fixation between the can body and the can lid of a metal can. In the inspection method of Patent Document 1, an image of the fixation portion between the can body and the can lid is captured by a camera disposed on the side of the metal can, and the quality of the appearance is determined based on the obtained image.

[0003] Japanese Patent Application Publication No. 4-121648

[0004] In conventional inspection methods, in order to inspect the fixation state of the metal can over its entire circumference, it was necessary to rotate at least one of the camera and the metal can. In this case, the rotation easily causes misalignment or misalignment between the camera and the metal can, which can reduce the inspection accuracy.

[0005] The present disclosure has been made in view of the above circumstances, and one of its objectives is to provide a technique for improving the inspection accuracy when visually inspecting the fixed state of two members.

[0006] One aspect of the present disclosure is an inspection device that inspects a fixed state of a first member and a second member in a test object including the first member and the second member that are fixed to each other. The test object includes a cylindrical second member having a tip end of the first member fitted into a groove provided in the outer peripheral surface of the second member, thereby fixing the first member and the second member to each other. The inspection device includes an opening into which the test object is inserted, an axicon mirror having a mirror surface that extends outside the opening and surrounds the outer peripheral surface of the test object inserted into the opening, and a camera that captures a mirror image of the groove and the mirror image of the tip end reflected on the mirror surface.

[0007] Another aspect of the present disclosure is an inspection method for inspecting a fixed state of a first member and a second member in a test object including the first member and the second member fixed to each other. The test object includes the first member and the second member fixed to each other by fitting a tip end of the first member into a groove provided on the outer peripheral surface of the cylindrical second member. The inspection method includes inserting the test object into an opening of an axicon mirror and capturing, with a camera, mirror images of the groove and the tip end reflected on the mirror surface of the axicon mirror.

[0008] Any combination of the above components, and conversion of the expression of the present disclosure into a method, device, system, etc., are also valid aspects of the present disclosure.

[0009] According to the present disclosure, it is possible to improve the inspection accuracy when visually inspecting the fixed state of two members.

[0010] 1(A), 1(B), 1(C), 1(D), 1(E), 1(F), 1(G), and 1(H) are schematic diagrams for explaining a test object. A schematic diagram of an inspection device according to an embodiment. A diagram explaining an image captured by a camera. A schematic diagram of an inspection device according to Modification 1. A diagram explaining an image captured by a camera. A schematic diagram of an axicon mirror provided in an inspection device according to Modification 2.

[0011] The present disclosure will be described below with reference to the drawings based on preferred embodiments. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, parts, and processes shown in each drawing are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not represent any order or importance, but are intended to distinguish one configuration from another. Furthermore, some components that are not important for explaining the embodiments are omitted from each drawing.

[0012] First, prior to describing the inspection apparatus 1 according to this embodiment, a test object 2 to be inspected will be described. Figures 1(A), 1(B), 1(C), 1(D), 1(E), 1(F), 1(G), and 1(H) are schematic diagrams for explaining the test object 2. Figures 1(A), 1(C), and 1(E) are perspective views of the test object 2, and Figures 1(B), 1(D), and 1(F) to 1(H) are cross-sectional views of portions of the test object 2.

[0013] In this embodiment, a cylindrical battery will be described as an example of the test object 2. The test object 2 includes a first member 4 and a second member 6 that are fixed to each other. When the test object 2 is a cylindrical battery, the first member 4 is a can lid, and the second member 6 is a can body. Therefore, the first member 4 is a flat, bottomed cylindrical member, and the second member 6 is a bottomed cylindrical member that is longer than the first member 4. The second member 6 has an opening 8 at one end in the longitudinal direction. In addition, a groove 10 is provided on the outer circumferential surface of the second member 6. The groove 10 extends in the axial direction of the second member 6 near the opening 8. As an example, the groove 10 extends around the entire circumference of the second member 6. When the first member 4 and the second member 6 are aligned vertically, the groove 10 has a lower surface facing the first member 4 and an upper surface facing the lower surface at a predetermined distance. The upper surface is located closer to the first member 4 than the lower surface.

[0014] A wound electrode group (not shown) and an electrolyte (not shown) are accommodated inside the second member 6 through the opening 8. The electrode group is formed by stacking and winding a strip-shaped positive electrode plate, a separator, a negative electrode plate, and a separator in this order. As shown in FIGS. 1A and 1B , the first member 4 is placed over the opening 8 with its leading end 12, i.e., its open end, facing the second member 6. As an example, the leading end 12 is annular and extends around the entire circumference of the first member 4. Next, as shown in FIGS. 1C and 1D , the first member 4 is pressed against the second member 6, and the second member 6 enters the first member 4. The leading end 12 of the first member 4 is narrowed. Therefore, the diameter of the leading end 12 is smaller than the diameter of the portion of the second member 6 closer to the opening 8 than the groove 10. Therefore, when the second member 6 enters the first member 4, the tip portion 12 is pushed by the outer peripheral surface of the second member 6, elastically deforms, and opens outward.

[0015] When the first member 4 is further pressed against the second member 6, the tip 12 reaches the groove 10, as shown in FIGS. 1(E) and 1(F). When the tip 12 reaches the groove 10, the force with which the outer circumferential surface of the second member 6 presses the tip 12 disappears. As a result, the first member 4 returns to its original shape due to its own elasticity. As a result, the tip 12 fits into the groove 10, and the first member 4 and the second member 6 are fixed to each other. As a result, the opening 8 is blocked by the first member 4, sealing in the electrode body and the electrolyte.

[0016] The tip portion 12 contacts the upper surface of the groove 10. Therefore, a gap G is formed between the lower end of the tip portion 12 and the lower surface of the groove 10. As shown in FIG. 1(G), when the first member 4 and the second member 6 are properly fixed to each other, a gap G1 of a predetermined size is formed. On the other hand, as shown in FIG. 1(H), when the first member 4 and the second member 6 are not properly fixed to each other, a gap G2 of a different size from the gap G1 is formed. Therefore, if the size of the gap G can be confirmed around the entire outer periphery of the test object 2, the fixed state of the first member 4 and the second member 6 can be known.

[0017] It should be noted that the tip portion 12 does not have to be narrowed before the first member 4 is fixed to the second member 6. In this case, after the first member 4 is fitted into the second member 6 and the tip portion 12 reaches the groove 10, the tip portion 12 is bent so that the tip portion 12 fits into the groove 10. In other words, the tip portion 12 is fixed to the groove 10 by crimping.

[0018] Fig. 2 is a schematic diagram of an inspection device 1 according to an embodiment. In Fig. 2, a portion of the inspection device 1 is depicted as a functional block. At least a portion of these functional blocks is realized as a hardware configuration by elements and circuits such as a computer CPU and memory, and as a software configuration by a computer program or the like. Those skilled in the art will understand that these functional blocks can be realized in various ways by combining hardware and software.

[0019] The inspection device 1 inspects the fixed state of the first member 4 and the second member 6 of the test object 2. The fixed state can also be referred to as a caulked state. The inspection device 1 according to this embodiment includes a base 14, an axicon mirror 16, a camera 18, an illumination 20, a determination unit 22, and a measurement unit 24. In this embodiment, as an example, the base 14, the axicon mirror 16, the illumination 20, and the camera 18 are aligned in the vertical direction. However, the arrangement direction of these members is not limited to the vertical direction.

[0020] The test object 2 is placed on the pedestal 14. The axicon mirror 16 is disposed above the pedestal 14. The axicon mirror 16 is fixed to a bracket (not shown). The axicon mirror 16 is ring-shaped and has a central opening 26 and a mirror surface 28 surrounding the opening 26. The test object 2 placed on the pedestal 14 is inserted into the opening 26. The diameter of the opening 26 is generally larger than the diameter of the test object 2 so that the test object 2 can be smoothly inserted into the opening 26. The mirror surface 28 extends outward from the periphery of the opening 26. The mirror surface 28 is inclined so as to move away from the pedestal 14 as it moves away from the opening 26, and surrounds the outer peripheral surface of the test object 2 inserted into the opening 26. The inclination angle of the mirror surface 28 is, for example, 45°. The positional relationship between the test object 2 and the axicon mirror 16 is determined so that the gap G and the mirror surface 28 overlap in the horizontal direction.

[0021] A camera 18 is disposed above the axicon mirror 16. The camera 18 has sensitivity to at least the light irradiated by the illumination 20, for example, the wavelength range of visible light. The camera 18 is oriented and fixed to a bracket so that the imaging direction faces the axicon mirror 16. The camera 18, as an example, has a telecentric lens 30.

[0022] The illuminator 20 is disposed between the axicon mirror 16 and the camera 18. The illuminator 20 is, for example, a known flat dome illuminator and includes a light source 32 and a window 34. The light source 32 is frame-shaped and includes a light source such as an LED. The window 34 is made of a light-transmitting resin and is fitted into the frame of the light source 32. The light source 32 emits light toward the window 34. The window 34 can emit the light emitted from the light source 32 toward at least one of the test object 2 and the axicon mirror 16. This allows the light to be irradiated onto the test object 2 directly or via the mirror surface 28. The light reflected by the test object 2 is reflected upward by the mirror surface 28, passes through the window 34, and enters the camera 18. Therefore, the camera 18 can capture the mirror image reflected on the mirror surface 28 through the illuminator 20.

[0023] 3 is a diagram illustrating an image IMG captured by the camera 18. The image IMG captured by the camera 18 includes a mirror image 10m of the lower surface of the groove 10 and a mirror image 12m of the lower end of the tip 12 reflected on the mirror surface 28. The mirror image 10m of the groove 10 and the mirror image 12m of the tip 12 form a ring-shaped mirror image M corresponding to the gap G. The inner peripheral edge of the mirror image M is the mirror image 10m of the lower surface of the groove 10, and the outer peripheral edge of the mirror image M is the mirror image 12m of the lower end of the tip 12.

[0024] As shown in FIG. 2 , the camera 18 sends the image IMG to the determination unit 22. The determination unit 22 determines the fixation state of the first member 4 and the second member 6 based on the shapes of the mirror image 10m of the groove 10 and the mirror image 12m of the tip portion 12 in the image IMG—in other words, based on the shape of the mirror image M. For example, the determination unit 22 pre-stores, as reference information, information about the mirror image M formed when the first member 4 and the second member 6 are properly fixed to each other. The determination unit 22 then calculates the degree of dissociation of the mirror image M in the acquired image IMG relative to the reference information. If the calculated degree of dissociation is equal to or less than a predetermined threshold, the determination unit 22 determines that the fixation state of the first member 4 and the second member 6 is normal. If the degree of dissociation exceeds the threshold, the determination unit 22 determines that the fixation state is abnormal. The threshold can be set as appropriate by a designer based on experiments, simulations, or the like.

[0025] For example, the determination unit 22 stores, as the reference information, the value of the thickness of the mirror image M obtained in a normal fixed state, i.e., the value of the distance between the mirror image 10m of the groove 10 and the mirror image 12m of the tip 12. The determination unit 22 compares the thickness of the mirror image M in the image IMG with the reference information. If the mirror image M has a portion where the difference in thickness exceeds a threshold, the determination unit 22 determines that the fixation state is abnormal. The thickness of the mirror image M may be a value based on the pixel size of the image IMG, or a value based on the actual dimension obtained by multiplying the pixel size by the optical resolution per pixel [μm] when the manufactured value of the inner diameter of the axicon mirror 16 is used as the reference. Furthermore, the reference information may be information about the shape of the mirror image M other than the thickness.

[0026] As an example, when the determination unit 22 determines that the fixation state is abnormal, it notifies the user of the inspection device 1 of the determination result by a known notification method. The notification method is not particularly limited, and known methods such as emitting a notification sound or turning on a notification light can be used. The determination unit 22 may display the determination result on a monitor (not shown). Alternatively, the image IMG itself may be presented to the user. In this case, the user can determine whether the fixation state is normal or abnormal by checking the presented image IMG. When the image IMG itself is used by the user, the determination unit 22 may be omitted.

[0027] The measurement unit 24 measures the position of the test object 2 relative to the axicon mirror 16 in the insertion direction of the test object 2 into the opening 26. As an example, the measurement unit 24 has a folding mirror 36 and a laser displacement sensor 38. The folding mirror 36 is arranged so as to overlap with the test object 2 when viewed from the arrangement direction of the test object 2 and the camera 18. The laser displacement sensor 38 is arranged so as to be shifted in a direction intersecting with the arrangement direction. The laser displacement sensor 38 is a sensor of a triangulation system or an optical confocal system, and can measure the position of the test object 2 by irradiating the test object 2 with laser light L and receiving the laser light L reflected by the test object 2.

[0028] By interposing the folding mirror 36 between the laser displacement sensor 38 and the test object 2, the laser displacement sensor 38 can be removed from the angle of view of the camera 18. This makes it possible to prevent the laser displacement sensor 38 from interfering with the inspection of the fixed state. Furthermore, by arranging the folding mirror 36 directly above the test object 2, it is possible to prevent the folding mirror 36 from overlapping with the mirror surface 28 when viewed from the camera 18. This makes it possible to prevent the folding mirror 36 from interfering with the inspection of the fixed state.

[0029] When the position of the test object 2 relative to the axicon mirror 16 changes, the position of the gap G relative to the mirror surface 28 changes. When the position of the gap G relative to the mirror surface 28 changes, the size of the mirror image M changes. When the fixation state is determined based on the shape of the mirror image M, it is easier to improve the inspection accuracy if the size of the mirror image M is constant.

[0030] Therefore, the inspection apparatus 1 of this embodiment measures the position of the test object 2 relative to the axicon mirror 16 using the measurement unit 24. The measurement unit 24 sends the measurement results to the adjustment unit 40. The adjustment unit 40, as an example, has a drive mechanism that combines known motors and the like, and can move the pedestal 14 forward and backward relative to the axicon mirror 16. The adjustment unit 40 displaces the pedestal 14 based on the measurement results of the measurement unit 24. For example, the adjustment unit 40 stores information regarding the reference position of the pedestal 14 in advance, and displaces the pedestal 14 to the reference position. This makes it possible to keep the size of the mirror image M in the image IMG constant, thereby improving the inspection accuracy in the fixed state.

[0031] The measurement unit 24 may display the measurement results on a monitor (not shown), so that the measurement results themselves are presented to the user. In this case, the user can manually adjust the position of the test object 2 while checking the presented measurement results. In this case, the adjustment unit 40 may be omitted.

[0032] As shown in Fig. 3, the axicon mirror 16 of this embodiment has a low-reflection surface 42 on the periphery of the opening 26, in other words, on the inner periphery of the axicon mirror 16. The low-reflection surface 42 has a lower optical reflectance than the outer periphery of the test object 2 and the mirror surface 28. The low-reflection surface 42 can be formed by applying a known low-reflection treatment to the inner periphery of the axicon mirror 16. Examples of low-reflection treatments include applying an ultra-low-reflection material such as carbon black, AR coating (i.e., coating with an anti-reflection film), and low-reflection treatments such as texturing.

[0033] At the inner peripheral edge of the axicon mirror 16, light emitted from the illumination 20 may be diffracted or scattered (see FIG. 6). This diffracted light or scattered light is reflected by the outer peripheral surface of the test object 2 and becomes stray light. If this stray light is reflected by the mirror surface 28 and enters the camera 18, the contour of the mirror image M may become unclear. In response to this, the provision of the low-reflection surface 42 can suppress the generation of diffracted light and scattered light, and the reflection of stray light toward the camera 18. As a result, the inspection accuracy of the fixed state can be improved.

[0034] As described above, in the inspection device 1 of this embodiment, the entire periphery of the outer surface of the test object 2 is surrounded by the axicon mirror 16, and the mirror image 10m of the groove 10 and the mirror image 12m of the tip 12 reflected on the mirror surface 28 are captured by the camera 18. This makes it possible to inspect the fixed state of the first member 4 and the second member 6 around the entire periphery of the test object 2 without rotating the camera 18 and the test object 2 relatively. This makes it possible to improve the inspection accuracy when visually inspecting the fixed state.

[0035] Furthermore, the determination unit 22 determines the fixation state, thereby further improving the inspection accuracy. Also, the time required to inspect the fixation state can be reduced. Also, the measurement unit 24 measures the height position of the test object 2 relative to the axicon mirror 16, thereby further improving the inspection accuracy. Also, the axicon mirror 16 has a low-reflection surface 42, thereby further improving the inspection accuracy.

[0036] The embodiments of the present disclosure have been described in detail above. The above-described embodiments merely illustrate specific examples of implementing the present disclosure. The content of the embodiments does not limit the technical scope of the present disclosure, and many design modifications, such as changing, adding, or deleting components, are possible within the scope of the invention defined in the claims. A new embodiment with design modifications will combine the effects of the combined embodiments and modifications. In the above-described embodiments, content that allows such design modifications is emphasized by using notations such as "in this embodiment" or "in this embodiment," but design modifications are also permitted even in content without such notation. Furthermore, any combination of components included in each embodiment is also valid as an aspect of the present disclosure. Hatching on cross sections in the drawings does not limit the material of the hatched object.

[0037] (Modification 1) In the embodiment, the height position of the test object 2 is measured by the measurement unit 24, and the size of the mirror image M is made constant by adjusting the height position. On the other hand, in this modification, the size of the mirror image M is adjusted by calculation to make it constant. Fig. 4 is a schematic diagram of the inspection device 1 according to modification 1. Fig. 5 is a diagram illustrating an image IMG captured by the camera 18.

[0038] That is, the inspection apparatus 1 of this modified example includes a correction unit 44. The correction unit 44 corrects the sizes of the mirror image 10m of the groove 10 and the mirror image 12m of the tip 12 in the image IMG, in other words, the size of the mirror image M, using the real image 2r of the test object 2 and the real image 26r of the opening 26 that appear in the image IMG as references. The real image 2r of the test object 2 is a real image of the outer periphery of the test object 2, and the real image 26r of the opening 26 is a real image of the periphery of the opening 26. Theoretically, the sizes of these real images are constant regardless of the position of the test object 2 relative to the axicon mirror 16. Therefore, by digitally correcting the sizes of the mirror images using these real images as references, it is possible to cancel out any positional deviation of the test object 2 relative to the axicon mirror 16.

[0039] The correction unit 44 sends information about the corrected mirror image to the determination unit 22. The determination unit 22 determines the fixation state of the first member 4 and the second member 6 based on the acquired information. This makes it possible to improve the accuracy of inspection of the fixation state.

[0040] 5, the image IMG includes, from the outside to the inside, a real image 16r of the outer periphery of the axicon mirror 16, a mirror image 2m of the outer periphery of the test object 2, a mirror image 12m of the tip 12, a mirror image 10m of the groove 10, a real image 26r of the inner periphery of the axicon mirror 16, i.e., the periphery of the opening 26, and a real image 2r of the outer periphery of the test object 2. The mirror image 12m of the tip 12 and the mirror image 10m of the groove 10 form a mirror image M.

[0041] As an example, the correction unit 44 measures the size of the real image 26r of the periphery of the opening 26 in the image IMG, i.e., the inner diameter of the axicon mirror 16 (step S1). It also measures the size of the real image 2r of the test object 2, i.e., the outer diameter of the test object 2 (step S2). When measuring the inner or outer diameter, the contour of the object is identified using a known edge detection method. The same applies to the dimensional measurements of each part described below. Next, the correction unit 44 divides the inner diameter of the axicon mirror 16 measured in step S1 by the manufactured value of the inner diameter of the axicon mirror 16, i.e., the actual inner diameter of the axicon mirror 16, to calculate an optical correction factor (step S3). The optical correction factor is a correction factor that takes into account the influence of optical aberrations that may occur in the axicon mirror 16 and the camera 18. The correction unit 44 also multiplies the outer diameter of the test object 2 calculated in step S2 by the optical correction factor to calculate the outer diameter of the test object 2 after optical correction (step S4).

[0042] The corrector 44 also measures the size of the mirror image 2m of the test object 2 (step S5). Then, from the outer diameter of the test object 2 after the optical correction calculated in step S4 and the size of the mirror image 2m measured in step S5, a correction value for obtaining the outer diameter of the test object 2 when the manufactured value of the inner diameter of the axicon mirror 16 is used as a reference, i.e., the true outer diameter of the test object 2, is calculated (step S6). Specifically, when the outer diameter of the test object 2 after the optical correction calculated in step S4 is S4, the size of the mirror image 2m measured in step S5 is S5, and the correction value for obtaining the true outer diameter of the test object 2 is m, if the tilt angle of the mirror surface 28 is 45°, the correction value m is calculated based on equation (1): m = (S5 / S4) / 2√2.

[0043] Next, the correction unit 44 calculates the amount of positional deviation of the test object 2 relative to the axicon mirror 16 based on the tilt angle of the mirror surface 28, from the correction value for obtaining the true outer diameter of the test object 2 calculated in step S6 and the size of the mirror image 2m of the test object 2 measured in step S5 (step S7). For example, when the tilt angle of the mirror surface 28 is 45°, a 1 mm change in the position of the test object 2 relative to the axicon mirror 16 results in a change of 2×√2 mm in the mirror image 2m of the test object 2. Specifically, when the tilt angle of the mirror surface 28 is 45°, where X is the amount of deviation, the amount of deviation X is calculated based on equation (2): X [mm] = 1 - {(S5 - S4) / (2√2 × m)}. S4, S5, and m in equation (2) are the same as in equation (1).

[0044] Thereafter, the correction unit 44 calculates the size of the mirror image 12m of the tip portion 12 and corrects the size of the mirror image 12m by an amount corresponding to the amount of deviation calculated in step S7 (step S8). Specifically, when the calculated size of the mirror image 12m is P and the corrected size of the mirror image 12m is Q, if the inclination angle of the mirror surface 28 is 45°, the corrected size Q of the mirror image 12m is calculated based on equation (3): Q = X × 2√2 × m × P. m and X in equation (3) are the same as in equation (1) or (2).

[0045] Furthermore, the size of the mirror image 10m of the groove 10 is calculated, and the size of the mirror image 10m is corrected by an amount corresponding to the amount of deviation calculated in step S7 (step S9). Specifically, when the calculated size of the mirror image 10m is R and the corrected size of the mirror image 10m is T, if the inclination angle of the mirror surface 28 is 45°, the corrected size T of the mirror image 10m is calculated based on equation (4): T = X × 2√2 × m × R. m and X in equation (4) are the same as in equation (1) or (2).

[0046] This makes it possible to obtain a mirror image M of a constant size regardless of the position of the test object 2 relative to the axicon mirror 16. Furthermore, this modification also makes it possible to eliminate temperature-dependent errors that may occur in the optical system, such as the axicon mirror 16 and the camera 18. The width of the mirror image M can be calculated by dividing the absolute value of the difference between the size of the corrected mirror image 12m and the size of the corrected mirror image 10m by 2.

[0047] When correcting the size of the mirror image in the image IMG based on the real image 2r of the test object 2 and the real image 26r of the opening 26 shown in the image IMG, it is desirable to extract the outer periphery of the test object 2 and the periphery of the opening 26 in the image IMG with high accuracy. For this reason, the inspection device 1 of this modified example is equipped with a low-reflection member 46. The low-reflection member 46 has a lower optical reflectance than the outer periphery of the test object 2 and the mirror surface 28. The low-reflection member 46 may be made of a material such as resin that has a lower optical reflectance than the test object 2 and the mirror surface 28, or may be made of any material with a low-reflection material coated on its surface.

[0048] Furthermore, the low-reflection member 46 is positioned so as to overlap the gap between the test object 2 and the opening 26 when viewed from the arrangement direction of the test object 2 and the camera 18. Therefore, a real image 46r of the low-reflection member 46 appears between the real image 2r of the test object 2 and the real image 26r of the opening 26 in the image IMG. The gradation of the pixel corresponding to the real image 46r is lower than the gradation of the pixel corresponding to the real image 2r and the real image 26r. This makes the contours of the real images 2r and 26r clear, allowing the outer diameter of the test object 2 and the inner diameter of the axicon mirror 16 to be measured with high accuracy. This improves the inspection accuracy in the fixed state. Note that mirror image correction by physical position adjustment of the test object 2 and mirror image correction by calculation may be combined.

[0049] (Modification 2) In the embodiment, a low-reflection surface 42 is provided on the periphery of the opening 26 to prevent the contour of the mirror image M from becoming unclear due to diffracted light or scattered light. On the other hand, in this modification, this problem is solved by providing a flat portion on the periphery of the opening 26. Figure 6 is a schematic diagram of the axicon mirror 16 provided in the inspection device 1 according to modification 2.

[0050] The axicon mirror 16 of this modified example has a cylindrical opening 26 and a flat surface 48 inside the opening 26. The flat surface 48 extends from the periphery or upper end of the opening 26 along the outer circumferential surface of the test object 2. As shown by the two-dot chain line in FIG. 6 , the flat surface 48 may be inclined so as to move away from the outer circumferential surface of the test object 2 as it moves away from the camera 18. Even if stray light SL is generated by diffracting or scattering light VL emitted from the illumination 20 at the inner circumferential edge of the axicon mirror 16, the flat surface 48 can prevent the stray light SL from traveling toward the camera 18. As a result, the inspection accuracy in the fixed state can be improved. The low-reflection surface 42 and the flat surface 48 may be combined.

[0051] (Other Modifications) The camera 18 may have a lens other than the telecentric lens 30. The illumination 20 may be an illumination other than a flat dome illumination, such as a dome illumination or a bar illumination.

[0052] The embodiments may be specified by the following items. [Item 1] An inspection device (1) for inspecting a fixed state of a first member (4) and a second member (6) in a test object (2) including the first member (4) and the second member (6) fixed to each other, wherein the test object (2) has a tip end (12) of the first member (4) fitted into a groove (10) provided on the outer peripheral surface of the cylindrical second member (6), thereby fixing the first member (4) and the second member (6) to each other; the inspection device (1) comprises: an axicon mirror (16) having an opening (26) into which the test object (2) is inserted, and a mirror surface (28) that extends outside the opening (26) and surrounds the outer peripheral surface of the test object (2) inserted into the opening (26); and a camera (18) that captures a mirror image (10m) of the groove (10) and a mirror image (12m) of the tip end (12) reflected on the mirror surface (28). Inspection device (1). [Item 2] The inspection device (1) according to item 1, including a determination unit (22) that determines a fixed state of the first member (4) and the second member (6) based on the shapes of a mirror image (10m) of the groove (10) and a mirror image (12m) of the tip portion (12). [Item 3] The inspection device (1) according to item 1 or 2, including a measurement unit (24) that measures the position of the test object (2) relative to the axicon mirror (16) in the insertion direction of the test object (2) into the opening (26). [Item 4] The inspection device (1) according to item 3, wherein the measurement unit (24) has a folding mirror (36) that is arranged to overlap the test object (2) when viewed from the arrangement direction of the test object (2) and the camera (18), and a laser displacement sensor (38) that is arranged offset in a direction intersecting the arrangement direction. [Item 5] The inspection device (1) according to any one of Items 1 to 4, further comprising a correction unit (44) that corrects the sizes of the mirror image (10m) of the groove (10) and the mirror image (12m) of the tip portion (12) in the image (IMG) captured by the camera (18) based on a real image (2r) of the test object (2) and a real image (26r) of the opening (26). [Item 6] The inspection device (1) according to Item 5, further comprising a low-reflection member (46) that has a lower light reflectance than the outer peripheral surface of the test object (2) and the mirror surface (28), and is arranged so as to overlap with a gap between the test object (2) and the opening (26) when viewed from the arrangement direction of the test object (2) and the camera (18).[Item 7] The inspection device (1) according to any one of Items 1 to 6, wherein the axicon mirror (16) has a flat portion (48) that extends from the periphery of the opening (26) along the outer circumferential surface of the test object (2) or that slopes away from the outer circumferential surface of the test object (2) as it moves away from the camera (18). [Item 8] The inspection device (1) according to any one of Items 1 to 7, wherein the axicon mirror (16) has a low-reflection surface (42) on the periphery of the opening (26) that has a lower optical reflectivity than the outer circumferential surface of the test object (2) and the mirror surface (28). [Item 9] An inspection method for inspecting a fixed state of a first member (4) and a second member (6) in a test object (2) including the first member (4) and the second member (6) fixed to each other, wherein the test object (2) has a tip end (12) of the first member (4) fitted into a groove (10) provided on the outer peripheral surface of the cylindrical second member (6), so that the first member (4) and the second member (6) are fixed to each other, and the inspection method includes inserting the test object (2) into an opening (26) of an axicon mirror (16), and capturing, with a camera (18), a mirror image (10m) of the groove (10) and a mirror image (12m) of the tip end (12) reflected on a mirror surface (28) of the axicon mirror (16).

[0053] The present disclosure can be used in an inspection apparatus and an inspection method.

[0054] REFERENCE SIGNS LIST 1 Inspection device, 2 Test object, 4 First member, 6 Second member, 8 Opening, 10 Groove, 12 Tip portion, 16 Axicon mirror, 18 Camera, 22 Determination unit, 24 Measurement unit, 26 Opening, 28 Mirror surface, 36 Folding mirror, 38 Laser displacement sensor, 42 Low-reflection surface, 44 Correction unit, 46 Low-reflection member, 48 Flat portion.

Claims

1. An inspection device for inspecting a fixed state of a first member and a second member in a test object including a first member and a second member which are fixed to each other, wherein the test object has a tip end of the first member fitted into a groove provided on an outer peripheral surface of the cylindrical second member, thereby fixing the first member and the second member to each other, the inspection device comprising: an axicon mirror having an opening into which the test object is inserted and a mirror surface that extends outside the opening and surrounds the outer peripheral surface of the test object inserted into the opening; and a camera that captures a mirror image of the groove and a mirror image of the tip end reflected on the mirror surface.

2. The inspection device according to claim 1, further comprising a determination unit that determines a fixed state of the first member and the second member based on the shapes of the mirror image of the groove and the mirror image of the tip portion.

3. The inspection device according to claim 1 or 2, further comprising a measurement unit that measures the position of the test object relative to the axicon mirror in the insertion direction of the test object into the opening.

4. The inspection device according to claim 3, wherein the measurement section includes a folding mirror arranged so as to overlap the test object when viewed from the arrangement direction of the test object and the camera, and a laser displacement sensor arranged offset in a direction intersecting the arrangement direction.

5. An inspection device as described in claim 1 or 2, further comprising a correction unit that corrects the sizes of the mirror image of the groove and the mirror image of the tip in the image captured by the camera based on a real image of the test object and a real image of the opening in the image.

6. The inspection device described in claim 5, further comprising a low-reflection member having a lower light reflectance than the outer peripheral surface of the test object and the mirror surface, and arranged so as to overlap with the gap between the test object and the opening when viewed from the arrangement direction of the test object and the camera.

7. An inspection device as described in claim 1 or 2, wherein the axicon mirror has a flat surface that extends from the periphery of the opening along the outer circumferential surface of the test object, or that inclines so as to move away from the outer circumferential surface of the test object as it moves away from the camera.

8. An inspection device according to claim 1 or 2, wherein the axicon mirror has a low-reflection surface on the periphery of the opening, the low-reflection surface having a lower optical reflectance than the outer peripheral surface of the test object and the mirror surface.

9. An inspection method for inspecting a fixed state of a first member and a second member in a test object including a first member and a second member which are fixed to each other, wherein the test object has a tip end of the first member fitted into a groove provided on an outer circumferential surface of the cylindrical second member, thereby fixing the first member and the second member to each other, the inspection method including: inserting the test object into an opening of an axicon mirror, and capturing, with a camera, a mirror image of the groove and a mirror image of the tip end reflected on the mirror surface of the axicon mirror.

Images