Mouth part inspection device and mouth part inspection method

Abstract

This mouth part inspection device 10 comprises: a rotation unit 12 that rotates a container 80 around a central axis 81 of a mouth part 82; an imaging unit 40 that images the mouth part 82 rotated by the rotation unit 12 from the inside; and a calculation unit 22 that determines the presence or absence of a defect in a threaded section 87 of the mouth part 82 on the basis of an image captured by the imaging unit 40. The calculation unit 22 sets a first inspection region having a predetermined width along the central axis 81 in the image, calculates the length of a fourth portion having a predetermined brightness or more continuous in a direction along the central axis 81 in the first inspection region, and determines that there is a defect when the calculated length of the fourth portion is longer than a preset first threshold value.

Description

Mouth inspection device and mouth inspection method

[0009] ,

[0001] The present invention relates to a mouth inspection device and a mouth inspection method for a container.

[0002] Generally, various defects such as inclusion of foreign substances such as stones and metals, bubbles, dirt adhesion, cracks (glass cracks), chips, and wrinkles may occur in glass bottles, and in order to ensure their safety and aesthetics, all glass bottles are inspected. However, due to the complex structure of the screw part of the glass bottle, it is difficult to optically inspect these defects compared to other parts.

[0003] In the glass bottle inspection process, many inspections are carried out on a handling machine that rotates the glass bottle. The handling machine has a plurality of inspection stations for inspecting while rotating the glass bottle, and each inspection station is equipped with inspection machines divided by each part and each type of defect.

[0004] The applicant of the present application proposed a screw part inspection device in Patent Document 1 that processes an image composed of a bright part and a shadow part obtained by imaging the light transmitted through the screw part of a glass bottle, detects the shadow part appearing in the bright part or the bright part appearing in the shadow part, and determines that there is a defect in the screw part.

[0005] Japanese Patent Application Laid-Open No. 2003-65967 [[ID=​​​​​​​​​​[1] One embodiment of the mouth inspection device according to the present invention is a mouth inspection device comprising: a rotating unit that rotates a container about a central axis of the mouth; an imaging unit that images the mouth rotated by the rotating unit from the inside; and a calculation unit that determines whether or not there are defects in the threaded portion of the mouth based on the image captured by the imaging unit, wherein the image includes a first portion with a predetermined brightness or higher corresponding to the vicinity of the top of the threads of the threaded portion; a second portion with a predetermined brightness or higher corresponding to the valleys between adjacent threads; and a third portion located between the first portion and between the top and the valleys, wherein the third portion is darker than the first and second portions, and the calculation unit sets a first inspection area having a predetermined width along the central axis in the image, calculates the length of a fourth portion with a predetermined brightness or higher that is continuous in the direction along the central axis in the first inspection area, and determines that there are defects if the calculated length of the fourth portion is longer than a preset first threshold.

[0010] [2] In one embodiment of the mouth inspection device, the third portion appears once on the top surface side and once on the opposite side of the top surface of the screw thread, and the calculation unit divides the first inspection area to set up a plurality of second inspection areas, calculates the length of the third portion along the central axis on the opposite side of the top surface for each second inspection area, and determines that there is a defect if the calculated length of the third portion is shorter than a second threshold set for each second inspection area.

[0011] [3] In one embodiment of the mouth inspection device, the third portion appears once on the top surface side and once on the opposite side of the top surface of the screw thread, the calculation unit sets a plurality of second inspection areas by dividing the first inspection area, calculates the length of the third portion along the central axis on the opposite side of the top surface for each second inspection area, and determines that there is a defect if the calculated length of the third portion is longer than a third threshold set for each second inspection area.

[0012] [4] In one embodiment of the mouth inspection device, the third portion appears once on the top surface side and once on the opposite side of the top surface of the screw thread, and the end of the first inspection area on the top surface side can be set to the third portion on the opposite side of the top surface of the starting part of the thread.

[0013] [5] In one embodiment of the mouth inspection device, the threaded portion has a threading start portion shaped along the central axis, the second inspection area is set up in multiple locations from the third portion on the opposite side of the top surface adjacent to the threading start portion to the opposite side of the top surface, the image includes a fifth portion that is darker than the first and second portions in the threading start portion, the calculation unit sets the third inspection area in the image to include the fifth portion, calculates the width of the third portion along the central axis in the third inspection area, and can determine that there is a defect if the third portion exceeding a predetermined width exceeds a predetermined length in the direction along the top surface.

[0014] [6] In one embodiment of the mouth inspection method according to the present invention, the calculation unit sets a fourth inspection area and a fifth inspection area in the image before and after the threading start area in a direction along the first portion, and can determine that there is a defect if the portion that is darker than the first portion exceeds a predetermined number of pixels in at least one of the fourth inspection area and the fifth inspection area.

[0015] [7] One embodiment of the mouth inspection method according to the present invention includes: an imaging step of obtaining an image by imaging the mouth of a container that rotates around the central axis of the mouth from the inside; an inspection area setting step of setting a first inspection area having a predetermined width along the central axis in the image; a length calculation step of calculating the length of a fourth portion having a predetermined brightness or higher that is continuous in the direction along the central axis in the first inspection area; and a determination step of determining that there is a defect if the calculated length of the fourth portion is longer than a preset first threshold, wherein the image includes a first portion having a predetermined brightness or higher that corresponds to the vicinity of the top of the threads of the screw portion; a second portion having a predetermined brightness or higher that corresponds to the valleys between adjacent threads; and a third portion that is located between the top and the valleys, sandwiching the first portion, wherein the third portion is a darker portion than the first portion and the second portion.

[0016] According to one embodiment of the mouth inspection device and mouth inspection method of the present invention, defects, including poor thread protrusion, which were previously difficult to detect, can be detected.

[0017] Figure 1 is a side view showing the configuration of the mouth inspection device according to this embodiment. Figure 2 is an enlarged front view of the mouth. Figure 3A is a schematic diagram showing an image and a sequence of images of the mouth. Figure 3B is an enlarged view showing a part of the first inspection area in a state where skin defects have occurred. Figure 3C is an enlarged view showing a part of the first inspection area after image processing. Figure 4 is a schematic diagram showing an image and a sequence of images of the mouth. Figure 5 is an enlarged front view of another mouth. Figure 6 (A) is a schematic diagram showing a state in which a second inspection area is set in a sequence of images of another mouth, and (B) is a schematic diagram showing a state in which a third inspection area is set in a sequence of images of another mouth. Figure 7 is a schematic diagram showing a state in which a fourth inspection area, a fifth inspection area, and a sixth inspection area are set in a sequence of images of another mouth. Figure 8 is a flowchart of the mouth inspection method according to this embodiment and modification 1. Figure 9 is a flowchart of the mouth inspection method according to modification 2.

[0018] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. The embodiments described below are not intended to unduly limit the scope of the present invention as described in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0019] One embodiment of the mouth inspection device according to this embodiment comprises a rotating unit that rotates a container around the central axis of the mouth, an imaging unit that images the mouth rotating by the rotating unit from the inside, and a calculation unit that determines whether or not there are defects in the threaded portion of the mouth based on the image captured by the imaging unit, wherein the image includes a first portion with a predetermined brightness or higher corresponding to the vicinity of the top of the threads of the threaded portion, a second portion with a predetermined brightness or higher corresponding to the valleys between adjacent threads, and a third portion located between the top and the valleys, sandwiching the first portion, wherein the third portion is darker than the first and second portions, and the calculation unit sets a first inspection area having a predetermined width along the central axis in the image, calculates the length of a fourth portion with a predetermined brightness or higher that is continuous in the direction along the central axis in the first inspection area, and determines that there are defects if the calculated length of the fourth portion is longer than a preset first threshold.

[0020] One embodiment of the mouth inspection method according to this embodiment includes an imaging step of obtaining an image by imaging the mouth of a container that rotates around the central axis of the mouth from the inside; an inspection area setting step of setting a first inspection area having a predetermined width along the central axis in the image; a length calculation step of calculating the length of a fourth portion in the first inspection area that is continuous in the direction along the central axis and has a brightness of a predetermined level or higher; and a determination step of determining that there is a defect if the calculated length of the fourth portion is longer than a preset first threshold, wherein the image includes a first portion with a brightness of a predetermined level or higher corresponding to the vicinity of the top of the thread of the screw portion; a second portion with a brightness of a predetermined level or higher corresponding to the valley between adjacent threads; and a third portion that is located between the top and the valley of the first portion, wherein the third portion is darker than the first and second portions.

[0021] 1. Mouth Inspection Device The mouth inspection device 10 will be described using Figures 1 to 7. Figure 1 is a side view showing the configuration of the mouth inspection device 10 according to this embodiment, Figure 2 is an enlarged front view of the mouth 82, Figure 3A is a schematic diagram showing images 50a, 50b and a continuous image 52a of the mouth 82, Figure 3B is an enlarged diagram showing a part of the first inspection area 55 in a state where skin defects have occurred, Figure 3C is an enlarged diagram showing a part of the first inspection area 55 after image processing, and Figure 4 is a schematic diagram showing images 50c, 50d and a continuous image 52b of the mouth 82. Figures 3A, 3B, 3C, 4, 6, and 7 show the scan direction S in the vertical direction of the figure, while the central axis 81 of the mouth 82 shown for reference is in the horizontal direction of each figure. The scan direction S is from top to bottom in each figure, but the scanning direction S may also be from bottom to top in each figure if the imaging order is reversed.

[0022] 1.1. As shown in the schematic diagram 1 of the apparatus, the mouth inspection apparatus 10 includes a rotating unit 12 that rotates the container 80 around the central axis 81 of the mouth 82, an imaging unit 40 that images the mouth 82 rotating by the rotating unit 12 from the inside, and a calculation unit 22 that determines whether or not there are defects in the threaded portion 87 of the mouth 82 based on the image captured by the imaging unit 40. The calculation unit 22 may be part of an image processing apparatus 20 which includes a storage unit 24. The mouth inspection apparatus 10 further includes a light-emitting unit 30 that irradiates the mouth 82 with light.

[0023] The rotating part 12 supports the container 80 while rotating it around a central axis 81. The container 80 is a container having a substantially cylindrical mouth 82. The material of the container 80 is not limited and may be glass or synthetic resin, for example. The central axis 81 is the central axis 81 of the substantially cylindrical mouth 82 and is also the center of rotation of the container 80 as it is rotated by the rotating part 12. Since the container 80 usually rotates in an upright position, the central axis 81 extends in the vertical direction. The rotating part 12 is a side roller that contacts the body of the container 80, but it may also be a turntable on which the container 80 is placed. The rotating part 12 may also be part of a handling machine (not shown) for transporting the container 80. The rotating part 12 rotates at a set speed directly or indirectly by an electric motor 14, and rotates the container 80. Control of the motor 14's rotation start, rotation speed, rotation end, etc., can be performed by a control device (not shown), for example, a control device that controls the entire handling machine. The rotating mechanism and conveying mechanism of the container 80 may employ other known mechanisms.

[0024] An encoder 16, which is a rotary encoder, is attached to the motor 14. The encoder 16 detects the amount of displacement caused by the rotation of the container 80 by the motor 14 and outputs a signal of the displacement amount to the image processing device 20. The encoder 16 only needs to be able to accurately measure the amount of displacement caused by the rotation of the container 80, and may be attached to a part other than the motor 14, for example, the rotating part 12.

[0025] The image processing device 20 is a device that performs calculations and controls the mouth inspection device 10, and its configuration includes a CPU for calculations and control, memory (RAM, ROM), external storage device, monitor, keyboard, mouse, and interface. The image processing device 20 is electrically connected to the encoder 16 and the imaging unit 40, and the imaging unit 40 can image the mouth 82 in accordance with the rotation speed of the container 80 based on signals from the image processing device 20.

[0026] Furthermore, the image processing device 20 includes, as a functional configuration, at least a calculation unit 22 and a storage unit 24. Some functions of the image processing device 20 may be located on a network. Display devices such as a display or known input devices may be connected to the image processing device 20. The image processing device 20 may be connected to a control device (not shown) that controls the entire container 80 transport device, and the calculation results of the calculation unit 22 may be output to the control device.

[0027] The calculation unit 22 can instruct the imaging unit 40 on the timing of imaging. The calculation unit 22 can acquire the captured images 50a, 50b, etc. (for example, Figure 3A) from the imaging unit 40. The calculation unit 22 can combine the images 50a, 50b, etc. to create a continuous image 52a (for example, Figure 3A). The calculation unit 22 can set a first inspection area 55 (Figure 3A), a second inspection area 56, 56a (Figures 4 and 6), a third inspection area 57 (Figure 6), and fourth to sixth inspection areas 58a to 58c (Figure 7) for the captured images, for example, images 50a, 50b, 50c, 50d, and the continuous images 52a, 52b, 52c, 52d, etc. The calculation unit 22 can calculate the lengths La, Lb, Lc, Ld, Le of the fourth portion 64a to 64e (Figure 3A), the lengths Lm, Ln, Lo of the third portion 63 (Figure 4), the width Wa and length Lp of the third portion 63 (Figure 6), etc., based on images such as images 50a, 50b, 50c, 50d, and sequential images 52a, 52b, 52c, 52d, etc. The calculation unit 22 can also calculate the number of pixels in the darker portion than the first portion 61 (Figure 7), etc., based on sequential image 52d, etc. Furthermore, the calculation unit 22 can compare the length La, etc., with a first threshold, etc., to determine the presence or absence of defects 90a, 90b, 90c, 90d, etc. (Figures 3A, 4, 6, 7) in images 50a, 50b, 50c, 50d, sequential images 52a, 52b, 52c, 52d, etc. Furthermore, the calculation unit 22 may perform predetermined image processing on the images 50a, 50b, etc., acquired from the imaging unit 40. Examples of known image processing include edge processing, binarization, shrinkage, and enlargement. It is preferable to perform such image processing for each image 50a, 50b in order to improve the processing speed of the calculation unit 22. The detailed functions of the calculation unit 22 will be described later.

[0028] The memory unit 24 can store the control program for the mouth inspection device 10, images 50a and 50b acquired from the imaging unit 40, continuous images 52a, etc., calculation results from the calculation unit 22, various threshold values, etc.

[0029] The light-emitting unit 30 is positioned to the side of the container 80 and irradiates light toward the side of the opening 82. The light-emitting unit 30 is, for example, a diffuse surface light source or a parallel surface light source. The illumination color of the light-emitting unit 30 is not limited, but may be changed to match the color of the container 80. For example, if the container 80 is brown, it is preferable for the light-emitting unit 30 to emit red light.

[0030] The imaging unit 40 is positioned approximately above the container 80, in a location where it can receive light emitted from the light-emitting unit 30 and transmitted through the opening 82. The opening inspection device 10 may also include a mirror 42 positioned in the light path between the imaging unit 40 and the light-emitting unit 30. The imaging unit 40 can receive light emitted from, for example, the light-emitting unit 30, transmitted through the opening 82, and reflected by the mirror 42. The imaging unit 40 is fixed to, for example, a handling machine such that its optical axis is at a downward angle θ1 with respect to the horizontal plane. The downward angle θ1 is the angle between the optical axis reflected by the mirror 42 and the horizontal plane, as in the example in Figure 1 where a mirror 42 is provided. The imaging unit 40 is positioned so that the inner circumferential surface 85b (Figure 2) of the opening 82, including the threaded portion 87, is within its field of view. The imaging unit 40 can capture a continuous image 52a (for example, Figure 3A) of the entire circumference (for example, 1.2 rotations) of the mouth 82 by rotating the container 80. The continuous image 52a captures the inner surface 85b as seen from the inside of the mouth 82, and also captures the screw portion 87 by passing through the mouth 82. The depression angle θ1 can be set to an angle in which the desired defect is reflected in the image, and can be set to, for example, about 20 to 45 degrees. In addition, by setting the depression angle θ1 to 20 to 45 degrees, it is possible to prevent the shoulder portion of the container 80 from appearing in the continuous image 52a.

[0031] The imaging unit 40 can use a known line sensor camera in which a number of sensors are arranged in a line. As the line sensor, a CCD type image sensor or a CMOS type image sensor can be used. The line sensor of the imaging unit 40 is arranged so as to be parallel to the central axis 81.

[0032] 1.2. Using the mouth and images Figures 2 to 4, we will explain an example of an object to be inspected: the mouth 82, images 50a to 50d and sequential images 52a and 52b of the mouth 82.

[0033] As shown in Figure 2, the mouth portion 82 has a threaded portion 87 that protrudes from the outer circumferential surface 85a. The threaded portion 87 may be a single continuous thread or multiple threads, as shown in Figure 2. The threaded portion 87 extends inclined from the starting thread portion 86a on the top surface 84 side toward the opposite side of the top surface 84, i.e., toward the body side. The threaded portion 87 has a top portion 88 that protrudes the most from the outer circumferential surface 85a and a valley portion 89 at the same height as the outer circumferential surface 85a. The threaded portion 87 in Figure 2 has a defect 90a called a "defect" which rarely occurs, where the desired shape is not formed. The defect appears as a dent in the threaded portion 87 because it is not accurately formed along the mold. The type of defect 90a may be any other defect as long as it can be identified by images 50a to 50d, for example, foreign matter adhering to the threaded portion 87, or chipping of the threaded portion 87.

[0034] The imaging unit 40 and mirror 42 (Figure 1), positioned at a depression angle θ1, image the inner circumferential surface 85b through the opening of the mouth portion 82. The imaging unit 40 may perform indirect imaging via the mirror 42 or direct imaging without the mirror 42, once images 50a to 50d of the inner circumferential surface 85b are obtained from the opening of the mouth portion 82. Light from the light-emitting unit 30 (Figure 1) passes through the mouth portion 82 to the inner circumferential surface 85b, and the shape of the screw portion 87 is imaged as bright and dark areas. Images 50a to 50d of the inside of the mouth portion 82 captured by the imaging unit 40 prevent the screw portion 87 on the opposite side of the mouth portion 82 from being captured.

[0035] Figures 3A and 4 are sequential images 52a and 52b of the inner surface 85b captured by the imaging unit 40. The sequential image 52a in Figure 3A is an image in which multiple images 50a, 50b... captured by the imaging unit 40 are arranged along the scan direction S in the order in which they were captured. Figure 3B is a part of the image 50a obtained in one capture, and Figure 3C is a part of the image 50a after image processing. The sequential image 52b in Figure 4 is an image in which multiple images 50c, 50d... captured by the imaging unit 40 are arranged along the scan direction S in the order in which they were captured. Above and below each figure, images 50a, 50b and images 50c, 50d from each capture by the imaging unit 40 are shown extracted from the sequential images 52a and 52b. In both sequential images 52a and 52b, images 50a, 50b and images 50c, 50d are aligned so that the top surface 84, which has been clarified by edge processing, extends in a straight line in the vertical direction.

[0036] The consecutive images 52a and 52b are captured such that the top surface 84 appears as a dark shadow extending vertically on the left side of the figure, and the threaded portion 87 appears as alternating bright and dark areas in the horizontal direction of the figure. Images 50a, 50b, 50c, 50d and / or consecutive images 52a, 52b are preferably binarized. Images 50a, 50b, 50c, 50d... include a first portion 61 with a predetermined brightness or higher corresponding to the vicinity of the top 88 of the threads of the threaded portion 87, a second portion 62 with a predetermined brightness or higher corresponding to the valleys 89 between adjacent threads, and a third portion 63 located between the first portion 61 and the top 88 and the valleys 89. The third portion 63 is a darker portion than the first portion 61 and the second portion 62. The third portion 63 appears, for example, once on the top surface 84 side and once on the opposite side of the top surface 84 of the opening 82 in each thread of a good thread 87. The third portion 63 is the part that connects the first portion 61 and the second portion 62 and corresponds to the bevel of the thread. The third portion 63 may also contain defects other than the bevel of the thread.

[0037] As shown in Figure 3A, the fourth portions 64a to 64e are portions with a brightness above a predetermined level that appear in each image 50a, 50b, etc., and are continuous in the direction along the central axis 81 in the first inspection area 55. The defect 90a in Figure 3A shows an example where it appears to completely divide one of the third portions 63 vertically. Therefore, in the portion with the defect 90a, the fourth portion 64d, which has a brightness above a predetermined level in the direction perpendicular to the scan direction S, appears longer than the other fourth portions 64a to 64c, 64e without being interrupted in the third portion 63. Also, in the portion with the defect 90a, a long fourth portion 64d is detected before and after image 50b, so the fourth portion 64d appears continuously and for a long time in the scan direction S.

[0038] In Figure 4, the defect 90b appears as a thinning of a portion of the third portion 63 along the central axis 81. Therefore, in the area with defect 90b, the dark third portion 63o appears shorter than other dark areas in the direction perpendicular to the scan direction S, as shown in image 50d. Similarly, a wavy defect called distortion, where a portion is thinned, can also be detected as defect 90b.

[0039] 1.3. Calculation Unit The calculation unit 22 acquires images 50a, 50b, 50c, 50d... from the imaging unit 40, sets a first inspection area 55 and a second inspection area 56, etc. in the images 50a, 50b, 50c, 50d..., calculates the length La to Le of the portion with a brightness above a predetermined level or the length Lm to Lo of the portion with a brightness below a predetermined level, compares the calculated length with a threshold value stored in the storage unit 24 to determine the presence or absence of defects 90a, 90b. The calculation unit 22 can also perform predetermined image processing on the images 50a, 50b, 50c, 50d... acquired from the imaging unit 40. The specific processing of the calculation unit 22 will be explained in "2. Mouth Inspection Method" to avoid redundant explanation.

[0040] Thus, the mouth inspection device 10 can detect defects 90a and 90b, including poor protrusion of the threaded portion 87, which were previously difficult to detect.

[0041] 2. Oral Inspection Method 2.1. Oral Inspection Method According to an Embodiment The oral inspection method according to this embodiment will be described using Figures 1 to 3C and Figure 8. Figure 8 is a flowchart of the oral inspection method according to this embodiment.

[0042] As shown in FIG. 8, the oral cavity inspection method according to the present embodiment includes an imaging step S10, an inspection area setting step S12, a length calculation step S14, and a determination step S16. The oral cavity inspection method may further include step S18. The oral cavity inspection method can be executed using the above-described oral cavity inspection device 10, and will be described below using the oral cavity inspection device 10, but it is also applicable to other devices.

[0043] S10: The imaging step is a step in which, for example, the imaging unit 40 images the oral cavity 82 of the container 80 rotating around the central axis 81 of the oral cavity 82 from the inside in accordance with a command from the arithmetic unit 22 to obtain images 50a, 50b,.... The arithmetic unit 22 may concatenate the images 50a, 50b,... and synthesize a continuous image 52a. Since the processing speed of the imaging step S10 may be different from the processing in S12 to S18 in the arithmetic unit 22, it may be continuously executed until the images 50a, 50b,... of the entire circumference of one oral cavity 82 are imaged without waiting for the processing after S12. In FIG. 3A, the images 50a, 50b are shown surrounded by a broken line, and the fourth portions 64a to 64e are shown by hatching.

[0044] As shown in FIG. 3B, when there is a thin shadow 92 due to poor surface finish in the image 50a imaged by the imaging unit 40, the length calculation in S14 described later may be affected by the thin shadow 92. Poor surface finish is small irregularities formed on the outer peripheral surface 85a of the oral cavity 82 due to a mold release agent or the like attached to the mold for molding the container 80. When poor surface finish occurs, it appears as a thin shadow 92 (a collection of small black pixels) in the bright portions (for example, the first portion 61 and the second portion 62) of the image 50a. Since poor surface finish is not a defect, it will be a misjudgment if it is judged as a defect. Therefore, the arithmetic unit 22 can execute predetermined image processing on each of the images 50a, 50b,... in FIG. 3A before executing S12. By executing the predetermined image processing, the thin shadow 92 is erased from each of the images 50a, 50b,..., and the influence of poor surface finish in S14 can be reduced. It is preferable that the arithmetic unit 22 executes predetermined image processing on each of the images 50a, 50b,... before synthesizing the continuous image 52a in S10.

[0045] The predetermined image processing includes, for example, binarization, shrinkage, and dilation. The calculation unit 22 first binarizes the images 50a, 50b... to clarify the thin shadows 92 as black pixels, as shown in Figure 3B. Next, the calculation unit 22 performs a process to shrink the black pixels in the images 50a, 50b... by a predetermined number of pixels. The predetermined number of pixels can be set to any number of pixels and can be set according to the state of skin defects appearing on the container 80. The predetermined number of pixels is the number of pixels that can almost completely eliminate the thin shadows 92 by the shrinkage process. The predetermined number of pixels is also set to the number of pixels that does not cause discontinuity in the third portion 63, which is continuous to the extent that it does not become a defect by the shrinkage process. Furthermore, the calculation unit 22 performs a process to dilate the black pixels in the images 50a, 50b... that have undergone the shrinkage process by the same predetermined number of pixels as the shrinkage process. The third portion 63, which has been thinned by the shrinkage process, is dilated by a predetermined number of pixels by the dilation process, and the third portion 63 returns to almost the state before the shrinkage process. As shown in Figure 3C, in the image 50a after the expansion process, there are almost no thin shadows 92. In this way, the calculation unit 22 may concatenate the images 50a, 50b, etc., which have undergone predetermined image processing, to synthesize a continuous image 52a and then execute S12.

[0046] The shrinking and expanding processes are performed in a direction perpendicular to the scan direction S of each image 50a, 50b, etc. That is, the calculation unit 22 processes a predetermined number of black pixels to shrink in a direction perpendicular to the scan direction S, and then processes a predetermined number of black pixels to expand in the same direction. Performing the shrinking and expanding processes in the scan direction S would affect the boundary between image 50a and adjacent images, so it is preferable to perform the shrinking and expanding processes in a direction perpendicular to the scan direction S.

[0047] S12: The inspection area setting step is, as shown in FIG. 3A, for example, a step in which the arithmetic unit 22 sets a first inspection area 55 having a predetermined width along the central axis 81 in the images 50a, 50b... acquired from the imaging unit 40. The first inspection area 55 has, for example, a width along the central axis 81 from the thread starting portion 86a to near the end of the thread portion 87. The thread starting portion 86a is imaged as two dark portions on both sides of the top 88, that is, on the top surface 84 side and the side opposite to the top surface 84, similar to other thread crests. The end of the first inspection area 55 on the top surface 84 side is set, for example, to the third portion 63 on the side opposite to the top surface 84 of the thread starting portion 86a. Since the distance from the top surface 84 to the thread starting portion 86a is determined based on the design conditions of the various containers 80, the width of the first inspection area 55 is stored in the storage unit 24 in advance. The arithmetic unit 22 can detect the position of the top surface 84 in the images 50a, 50b... by, for example, edge processing, and set the first inspection area 55 in the images 50a, 50b... according to the distance from the top surface 84 to the thread starting portion 86a stored in the storage unit 24.

[0048] S14: The length calculation step is, for example, a step in which the arithmetic unit 22 calculates the lengths La, Lb, Lc, Ld, Le... of the fourth portions 64a to 64e... that are continuous in the direction along the central axis 81 in the first inspection area 55 set in S12 and have a predetermined brightness or more. Each length may be calculated, for example, based on the number of pixels in the images 50a, 50b. The images 50a, 50b... include a first portion 61 having a predetermined brightness or more corresponding to the vicinity of the top 88 of the thread crest of the thread portion 87, a second portion 62 having a predetermined brightness or more corresponding to the valley portion 89 between adjacent thread crests, and a third portion 63 located at a position sandwiching the first portion 61 and being between the top 88 and the valley portion 89. In the images 50a, 50b, the third portion 63 is a darker portion than the first portion 61 and the second portion 62. The brightness criteria for distinguishing the first portion 61 to the fourth portions 64a to 64e may be set in advance and stored in the storage unit 24, and the arithmetic unit 22 may further binarize the images 50a, 50b, for example, based on these criteria to clarify the first portion 61 to the fourth portions 64a to 64e.

[0049] S16: The determination step is a step in which, for example, the calculation unit 22 determines that there is a defect 90a if the lengths La, Lb, Lc, Ld, Le... of the fourth parts 64a to 64e calculated in S14 are longer than a preset first threshold. The first threshold is preset to a value slightly larger than the maximum value of the interval between adjacent third parts 63 in the direction along the central axis 81 in a good product, and is stored in the storage unit 24. In the example of Figure 3A, in image 50b, the length Ld of the fourth part 64d passing through the defect 90a, such as a defective product, is longer than the length La of the fourth part 64a at a location without a defect, and exceeds the first threshold. The calculation unit 22 determines that there is a defect 90a in image 50b. The determination result may be output by the calculation unit 22 to the storage unit 24, for example, and stored in association with the container 80 to be inspected, and then output from the image processing device 20 to the handling machine. The handling machine can receive the determination result and discard the corresponding container 80 as a defective product. In addition, S14 may further calculate the continuous length of the fourth portion 64d in the scan direction S, and in S16 the calculation unit 22 may determine that there is a defect 90a if it is longer than a predetermined threshold.

[0050] S18: The calculation unit 22 determines whether the determination step S16 has been performed for all images 50a, 50b... (for the entire circumference) of one mouth 82. If all images have been performed, the mouth inspection method is terminated. If there are images that have not yet been processed, the unit returns to S12 and performs S12 to S16.

[0051] Thus, according to the mouth inspection method of this embodiment, it is possible to detect defects 90a, including poor protrusion of the threaded portion 87, which were previously difficult to detect.

[0052] 2.2. Mouth Inspection Method According to Modified Example 1 The mouth inspection method according to Modified Example 1 will be described using Figures 4 and 8. The imaging step S10 captures the images 50c, 50d, etc. shown in Figure 4. In addition to the "2.1. Mouth Inspection Method According to the Embodiment" described above, the mouth inspection method according to Modified Example 1 may also perform the following steps. Furthermore, in order to reduce the effect of skin imperfections, similar to the embodiment described above, the mouth inspection method according to Modified Example 1 may perform predetermined image processing on each image before combining the continuous images 52c. Note that explanations that overlap with the above description will be omitted.

[0053] S12: In addition to S12 according to the above embodiment, the inspection area setting step allows, for example, the calculation unit 22 to divide the first inspection area 55 and set a plurality of second inspection areas 56 in images 50c, 50d, etc., as shown in Figure 4. The second inspection area 56 is an area that extends along the top surface 84 to the entire circumference of the screw portion 87 with a predetermined width. The second inspection area 56 is, for example, narrower than the width of the first inspection area 55 and longer than the width along the central axis 81 of the third portion 63 that appears in the first inspection area 55. The second inspection area 56 can be set to divide the first inspection area 55 into multiple parts of the same width, for example, into four equal parts.

[0054] S14: In addition to S14 according to the above embodiment, the calculation unit 22 can calculate the lengths Lm, Ln, and Lo of the third parts 63m, 63n, and 63o along the central axis 81 on the opposite side of the top surface 84 for each second inspection area 56 set in S12. The lengths Lm, Ln, and Lo of the third parts 63m, 63n, and 63o can be calculated for each image 50c and 50d. Two third parts 63 are imaged for each screw thread, flanking the first part 61, but the calculation unit 22 calculates the lengths Lm, Ln, and Lo of the third part 63m, 63n, and 63o that is further from the top surface 84. This is because the part that becomes thinner due to a defect is the third part 63m, 63n, and 63o on the opposite side of the top surface 84.

[0055] S16: In the determination step, for example, the calculation unit 22 can determine if there is a defect 90b if the lengths Lm, Ln, Lo of the third parts 63m, 63n, and 63o calculated in S14 are shorter than a second threshold set for each second inspection area 56. The second threshold may be set to a different value for each second inspection area 56. For example, the third part 63 closer to the top surface 84 tends to be imaged with a wider width than the third part 63 further from the top surface 84. The second threshold can be set to a length slightly shorter than the length of the third part 63 measured in advance on a good sample. By setting it in this way, it is possible to detect a defect 90b in which the length of the third part 63 that is shadowed by the screw threads due to a manufacturing defect is shortened.

[0056] Furthermore, in the determination step S16, for example, the calculation unit 22 can determine if there is a defect if the lengths Lm, Ln, Lo of the third parts 63m, 63n, and 63o calculated in S14 are longer than a third threshold set for each second inspection area 56. The third threshold can be set to be slightly longer than the length of the third part 63 measured in advance on a good sample. This setting allows for the detection of foreign matter adhering to the mouth portion 82.

[0057] Thus, according to the modified example 1, by performing this method in addition to the mouth inspection method according to the above embodiment, it is possible to detect defects 90b, including poor protrusion of the threaded portion 87, which were previously difficult to detect.

[0058] 2.3. Mouth Inspection Method According to Modified Example 2 The mouth inspection method according to Modified Example 2 will be explained using Figures 5, 6, 7, and 9. Figure 9 is a flowchart of the mouth inspection method according to Modified Example 2. Here, an example in which the process in Figure 7 is performed after the process in Figure 6 will be explained, but the two processes may be performed in reverse order, simultaneously, or one may be performed with a different process. In addition to the "2.1. Mouth Inspection Method According to the Embodiment" described above, the mouth inspection method according to Modified Example 2 may further perform the following steps. Note that explanations that overlap with the above explanation will be omitted. Also, in Figures 8 and 9, the process is terminated after all images have been determined in S18, but the processes from S10 to S18 may be repeated multiple times.

[0059] As shown in Figure 5, the threaded portion 87 of the opening 82a used in Modification 2 has a threading start portion 86b shaped along the central axis 81. An opening 82a having such a threading start portion 86b is sometimes called a stopper opening. When this opening 82a is imaged in the imaging step S10, a series of images 52c and 52d are obtained, for example, as shown in Figures 6 and 7. In this example, a defect 90c exists adjacent to the threading start portion 86b. The series of images 52c and 52d include a fifth portion 65 in the threading start portion 86b that is darker than the first portion 61 and the second portion 62. The fifth portion 65 is a linear dark portion corresponding to the threading start portion 86b along the central axis 81. In Modification 1 above, if the threading start portion 86b is included in the inspection area, there is a possibility of misidentifying the fifth portion 65 as a defect, and in the above embodiment, the defect 90c is difficult to detect. Although Figures 6 and 7 use consecutive images 52c and 52d for explanation, each step may also be performed on each image before merging.

[0060] S12: In the inspection area setting step, as shown in Figure 6(A), in addition to S12 according to the above embodiment, for example, the calculation unit 22 sets a second inspection area 56a in the continuous image 52c. The second inspection area 56a is an area along the top surface 84 with a predetermined width, and in the continuous image 52c, it is an area that extends around the entire circumference of the threaded portion 87. Multiple second inspection areas 56a are set from the third portion 63 on the opposite side of the top surface 84 adjacent to the threading start portion 86b to the opposite side of the top surface 84. Figure 6(A) shows an example in which four second inspection areas 56a are set. The second inspection area 56a closest to the top surface 84 is set to include, for example, the third portion 63 that appears on the opposite side of the top surface 84 adjacent to the threading start portion 86b. Here, the third portion 63 included in the second inspection area 56a closest to the top surface 84 is the dark portion that appears on the surface transitioning from the apex 88 to the valley 89, and does not necessarily include the fifth portion 65. It is preferable to set up a separate inspection area in the first portion 61 (corresponding to the top portion 88) located near the threading start portion 86b, and to apply a different inspection method to it than to the second inspection area 56a.

[0061] In the inspection area setting step (S12) of the modified example 2, as shown in Figure 6(B), the calculation unit 22 can, for example, set the third inspection area 57 in the continuous image 52c so that the fifth portion 65 is included. The third inspection area 57 is an area with a predetermined width that extends along the top surface 84 around the entire circumference of the threaded portion 87. The third inspection area 57 has a width that includes the fifth portion 65 and the third portion 63 in the threading start portion 86b.

[0062] Figure 7 shows an example of a good product on the left, where multiple inspection areas (areas enclosed by dashed lines) are set for a continuous image 52d, and on the right side of the figure, two examples (A) and (B) are shown, where only the area around the threading start portion 86b with the defect 90d is extracted. Figure 7(A) is an example in which the calculation unit 22 accurately set the thread tip region 70 at the threading start portion 86b. Figure 7(B) is an example in which the calculation unit 22 mistakenly recognizes the defect 90d as the threading start portion 86b and sets the thread tip region 70 at the defect 90d.

[0063] In the inspection area setting step (S12) of the modified example 2, as shown in Figure 7(A), the calculation unit 22 may, for example, set the fourth inspection area 58a and the fifth inspection area 58b before and after the threading start area 86b in the continuous image 52d in the direction along the first portion 61. The threading start area 86b here is the threading start area 86b recognized by the calculation unit 22, and may include cases of misrecognition as shown in Figure 7(B). The calculation unit 22 may further set the sixth inspection area 58c in the continuous image 52d in the range adjacent to the fifth inspection area 58b in the direction along the first portion 61. The calculation unit 22 can detect the threading start area 86b in a predetermined range from the top surface 84 along the scan direction S and set the thread tip area 70 at the threading start area 86b. The calculation unit 22 arranges the fourth inspection area 58a and the fifth inspection area 58b before and after the thread tip area 70. The fourth inspection area 58a is set adjacent to the screw tip area 70 and on the extension of the first portion 61, and preferably has a width similar to that of the first portion 61. The fifth inspection area 58b is set adjacent to the screw tip area 70 and on the first portion 61. The fifth inspection area 58b and the sixth inspection area 58c can be set to match the width of the first portion 61. It is preferable that the fifth inspection area 58b and the sixth inspection area 58c do not reach the position where the mold seam line is visible.

[0064] Furthermore, steps S12 to S16 in Modified Example 1 and Modified Example 2 can be executed sequentially for each inspection area, and steps S12 to S16 for multiple inspection areas may be processed in parallel.

[0065] S14: In the length calculation process, for example, the calculation unit 22 can perform S14 according to the above embodiment, as well as S14 according to Modification 1, for the second inspection area 56a shown in Figure 6(A). The length calculation process for the second inspection area 56a is the same as S14 according to Modification 1, and can calculate the length of the third portion 63 along the central axis 81 on the opposite side of the top surface 84 for each second inspection area 56a.

[0066] Furthermore, as shown in Figure 6(B), in the length calculation step (S14) of the modified example 2, for example, the calculation unit 22 can calculate the width Wa of the third portion 63 along the central axis 81 in the third inspection area 57. The calculation unit 22 can then calculate, for example, the length Lp of the third portion 63 in the direction along the top surface 84 where the width Wa exceeds a predetermined width. The predetermined width can be determined based on a fifth portion 65 and multiple types of defect samples that occur in the third inspection area 57, which have been acquired in advance. The length Lp is the length of the third portion 63 that exceeds the predetermined width and continues along the top surface 84.

[0067] S15: In the pixel count calculation step, as shown in Figure 7, for example, the calculation unit 22 can calculate the number of pixels in the darker portion than the first portion 61 in at least one of the fourth inspection area 58a and the fifth inspection area 58b. The calculation unit 22 may further calculate the number of pixels in the darker portion than the first portion 61 in the sixth inspection area 58c. By calculating the number of pixels, it can be captured as the area value of the dark portion in that area.

[0068] S16: In the determination step, for example, the calculation unit 22 can determine that there is a defect if the length of the third portion 63 calculated in S14 is longer than the third threshold set for each second inspection area 56a, in addition to S16 according to the above embodiment, similar to S16 according to Modification 1.

[0069] Furthermore, as shown in Figure 6(B), in the determination step (S16) of the modified example 2, if it is calculated in S14 that the third portion 63 exceeding the predetermined width exceeds a predetermined length in the direction along the top surface 84, then it can be determined that there is a defect 90c. By exceeding the predetermined length, the fifth portion 65 can be excluded. In Figure 6(B), the calculation unit 22 can determine that at least a part of the defect 90c exists because the width Wa exceeds the predetermined width and the length Lp exceeds the predetermined length in the area enclosed by the dashed rectangle.

[0070] As shown in Figures 7(A) and 7(B), the determination step (S16) of the modified example 2 can determine that a defect 90d exists if, in at least one of the fourth inspection area 58a and the fifth inspection area 58b, the portion darker than the first portion 61 exceeds a predetermined number of pixels. According to the mouth inspection method of modified example 2, even if the defect 90d is easily mistaken for the threading start portion 86b of the stopper mouth, the defect 90d can be detected because the inspection area is placed before and after the threading start portion 86b (screw tip region 70) for determination. For example, as in (A), the fourth inspection area 58a and the fifth inspection area 58b are located adjacent to the threading start portion 86b, so if the calculation unit 22 can accurately recognize the threading start portion 86b, it is possible to avoid misjudging the fifth portion 65 as a defect. Also, as in (B), for example, even if the calculation unit 22 sets the screw tip region 70 to a defect 90d adjacent to the threading start portion 86b, if the fifth portion 65 is determined to be a defect, it is possible to prevent the removal of good products. Furthermore, defects located in the sixth inspection area 58c that are further from the screw tip area 70 than those in the fifth inspection area 58b can also be detected. Moreover, because the determination is based on the number of pixels, even if the fifth portion 65 extends diagonally with respect to the central axis 81, for example, it can be determined to be a defect.

[0071] The present invention is not limited to the embodiments described above, and various further modifications are possible, including configurations that are substantially identical to those described in the embodiments. Here, "identical configuration" means a configuration that has the same function, method, and result, or a configuration that has the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configuration described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as the configuration described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configuration described in the embodiments.

[0072] 10... Mouth inspection device, 12... Rotating unit, 14... Motor, 16... Encoder, 20... Image processing device, 22... Calculation unit, 24... Storage unit, 30... Light-emitting unit, 40... Imaging unit, 42... Mirror, 50a, 50b, 50c, 50d... Images, 52a, 52b, 52c, 52d... Continuous images, 55... First inspection area, 56, 56a... Second inspection area, 57... Third inspection area, 58a... Fourth inspection area, 58b... Fifth inspection area, 58c... Sixth inspection area, 61... First part, 62... Second part, 63 ,63m,63n,63o...Third part, 64a-64e...Fourth part, 65...Fifth part, 70...Thread tip region, 80...Container, 81...Central axis, 82,82a...Mouth, 84...Top surface, 85a...Outer surface, 85b...Inner surface, 86a,86b...Thread start part, 87...Threaded part, 88...Top, 89...Trough, 90a,90b,90c,90d...Defect, 92...Thin shadow, La,Lb,Lc,Ld,Le,Lm,Ln,Lo,Lp...Length, S...Scan direction, Wa...Width, θ1...Depression angle

Claims

1. A mouth inspection device comprising: a rotating unit that rotates a container around the central axis of the mouth; an imaging unit that images the mouth rotating by the rotating unit from the inside; and a calculation unit that determines whether or not there are defects in the threaded portion of the mouth based on the image captured by the imaging unit, wherein the image includes a first portion with a brightness of a predetermined level or higher corresponding to the vicinity of the top of the threads of the threaded portion; a second portion with a brightness of a predetermined level or higher corresponding to the valleys between adjacent threads; and a third portion located between the first portion and the top and the valleys, wherein the third portion is darker than the first and second portions, and the calculation unit sets a first inspection area having a predetermined width along the central axis in the image, calculates the length of a fourth portion with a brightness of a predetermined level or higher that is continuous in the direction along the central axis in the first inspection area, and determines that there are defects if the calculated length of the fourth portion is longer than a preset first threshold.

2. The mouth inspection device according to claim 1, wherein the third portion appears once on the top surface side and once on the opposite side of the top surface of the screw thread, and the calculation unit divides the first inspection area to set up a plurality of second inspection areas, calculates the length of the third portion along the central axis on the opposite side of the top surface for each second inspection area, and determines that there is a defect if the calculated length of the third portion is shorter than a second threshold set for each second inspection area.

3. The mouth inspection device according to claim 1, wherein the third portion appears once on the top surface side and once on the opposite side of the top surface of the screw thread, the calculation unit sets a plurality of second inspection areas by dividing the first inspection area, calculates the length of the third portion along the central axis on the opposite side of the top surface for each second inspection area, and determines that there is a defect if the calculated length of the third portion is longer than a third threshold set for each second inspection area.

4. A mouth inspection device according to any one of claims 1 to 3, wherein the third portion appears once on the top surface side and once on the opposite side of the top surface of the mouth in the screw thread, and the end of the first inspection area on the top surface side is set to the third portion on the opposite side of the top surface of the starting part of the thread cutting.

5. A mouth inspection device according to claim 2 or claim 3, wherein the threaded portion has a threading start portion shaped along the central axis, the second inspection area is set in multiple locations from the third portion on the opposite side of the top surface adjacent to the threading start portion to the opposite side of the top surface, the image includes a fifth portion that is darker than the first and second portions at the threading start portion, the calculation unit sets the third inspection area in the image to include the fifth portion, calculates the width of the third portion along the central axis in the third inspection area, and determines that a defect exists if the third portion exceeding a predetermined width has a predetermined length in the direction along the top surface.

6. The mouth inspection device according to claim 5, wherein the calculation unit sets a fourth inspection area and a fifth inspection area in the image before and after the threading start area in a direction along the first portion, and determines that there is a defect if the portion that is darker than the first portion exceeds a predetermined number of pixels in at least one of the fourth inspection area and the fifth inspection area.

7. A method for inspecting a container opening, comprising: an imaging step of obtaining an image by imaging the opening of a container that rotates around the central axis of the opening from the inside; an inspection area setting step of setting a first inspection area having a predetermined width along the central axis in the image; a length calculation step of calculating the length of a fourth portion having a predetermined brightness or higher that is continuous in the direction along the central axis in the first inspection area; and a determination step of determining that there is a defect if the calculated length of the fourth portion is longer than a preset first threshold, wherein the image comprises a first portion having a predetermined brightness or higher that corresponds to the vicinity of the top of the threads of the screw portion; a second portion having a predetermined brightness or higher that corresponds to the valleys between adjacent threads; and a third portion located between the top and the valleys, sandwiching the first portion, wherein the third portion is darker than the first portion and the second portion.

Images