Visual Inspection Equipment

Abstract

To improve inspection accuracy.SOLUTION: A camera 12 captures an image of a to-be-inspected object 2 placed on an inspection stage 11 from a side of the to-be-inspected object 2. A first illumination 13 irradiates a side surface of the to-be-inspected object 2 placed on the inspection stage 11 with light from above. A second illumination 14 irradiates a side surface of the to-be-inspected object 2 placed on the inspection stage 11 with light from below. Such an appearance inspection device 10 is configured to acquire a first image obtained by capturing an image of the to-be-inspected object 2 placed on the inspection stage 11 with the camera 12 while illuminating the to-be-inspected object 2 with the first illumination 13, acquire a second image obtained by capturing an image of the to-be-inspected object 2 placed on the inspection stage 11 with the camera 12 while illuminating the to-be-inspected object 2 with the second illumination 14, and determine whether the to-be-inspected object 2 whose image is captured is good or bad on the basis of the first image and the second image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a visual inspection apparatus. [Background technology]

[0002] WO2019 / 216031A1 discloses an invention relating to a defect inspection device and a defect inspection method for a ceramic body. The device disclosed here includes a table, an imaging unit, a low-angle illumination unit, a medium-angle illumination unit, and a high-angle illumination unit, a judgment image generation unit, and a defect judgment unit.

[0003] The table is a table on which the ceramic body to be inspected is placed. The imaging unit images at least a portion of the inspection surface of the ceramic body placed on the table as an imaging area from the normal direction of the inspection surface. The low-angle illumination unit, the medium-angle illumination unit, and the high-angle illumination unit each have four or more unit illuminations that each irradiate the imaging area with illumination light obliquely from different irradiation directions equiangularly spaced from each other around the imaging unit. The judgment image generation unit generates judgment image data for judging the presence or absence of defects in the imaging area based on the imaging data acquired by the imaging unit. The defect judgment unit judges the presence or absence of defects based on the judgment image data.

[0004] In the device disclosed herein, the multiple unit lights in each of the low-angle lighting unit, the medium-angle lighting unit, and the high-angle lighting unit are turned on and off in sequence. The imaging unit generates multiple pieces of low-angle lighting imaging data, multiple pieces of medium-angle lighting imaging data, and multiple pieces of high-angle lighting imaging data by imaging the imaging area each time the multiple unit lights in each of the low-angle lighting unit, the medium-angle lighting unit, and the high-angle lighting unit are turned on.

[0005] The judgment image generating section includes a maximum / minimum brightness image generating section and an excluded region specifying section. The maximum / minimum luminance image generating unit synthesizes the plurality of low-angle illumination image data, the plurality of medium-angle illumination image data, and the plurality of high-angle illumination image data such that the maximum luminance value for each pixel position becomes the luminance value for that pixel position, thereby generating low-angle maximum luminance image data, medium-angle maximum luminance image data, and high-angle maximum luminance image data, and synthesizes the plurality of low-angle illumination image data, the plurality of medium-angle illumination image data, and the plurality of high-angle illumination image data such that the minimum luminance value for each pixel position becomes the luminance value for that pixel position, thereby generating low-angle minimum luminance image data, medium-angle minimum luminance image data, and high-angle minimum luminance image data. The exclusion area identification unit identifies an exclusion target pixel area in an image represented by each of the low-angle minimum luminance image data, the medium-angle maximum luminance image data, the high-angle maximum luminance image data, the low-angle minimum luminance image data, the medium-angle minimum luminance image data, and the high-angle minimum luminance image data, based on at least one of the low-angle maximum luminance image data, the medium-angle minimum luminance image data, and the high-angle minimum luminance image data.

[0006] The pixel area to be excluded corresponds to an area included in the imaging area that is not to be inspected, and based on the low-angle minimum luminance image data, medium-angle minimum luminance image data, and high-angle minimum luminance image data that have been disabled for the pixel area to be excluded, low-angle judgment image data, medium-angle judgment image data, and high-angle judgment image data are generated as judgment image data, respectively. The defect determination unit determines the presence or absence of defects in the imaging region other than the exclusion target pixel region based on the low angle determination image data, the medium angle determination image data, and the high angle determination image data.

[0007] This ceramic body defect inspection device is said to be able to reliably detect defects that should be detected without mistakenly detecting irregularities on normal ceramic surfaces as defects, and to perform defect inspection more efficiently by excluding areas that do not need to be inspected when generating image data for judgment. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] WO2019 / 216031A1 Summary of the Invention [Problem to be solved by the invention]

[0009] However, cylindrical molded products such as gaskets and caps made of elastic bodies can have molding defects such as uneven surfaces and cracks. Here, we propose an appearance inspection device that is more suitable for finding molding defects in such molded products. [Means for solving the problem]

[0010] The appearance inspection device disclosed herein includes an inspection stage on which an object to be inspected is placed, at least one camera that photographs the object to be inspected placed on the inspection stage from the side of the object to be inspected, a first illuminator that irradiates the side surface of the object to be inspected placed on the inspection stage with light from above, a second illuminator that irradiates the side surface of the object to be inspected placed on the inspection stage with light from below, and a processing device. The processing device is configured to execute the following processes. A process of acquiring a first image by photographing an object to be inspected placed on the inspection stage with a camera while the second illumination is turned off and the first illumination is applied. A process of acquiring a second image by photographing an object to be inspected placed on an inspection stage with a camera while the first illumination is turned off and the second illumination is turned on. A process for determining whether the photographed object is good or bad based on the first image and the second image.

[0011] According to the appearance inspection device disclosed herein, defects occurring on the side peripheral surface of the object to be inspected can be extracted with high accuracy, so that a stable pass / fail judgment can be made. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic side view of a visual inspection apparatus 10. As shown in FIG. [Diagram 2]FIG. 2 is a schematic plan view of the appearance inspection apparatus 10. As shown in FIG. [Diagram 3] FIG. 3 is a side view that shows a schematic diagram of a visual inspection apparatus 10A showing another embodiment. [Figure 4] FIG. 4 is a photograph showing an example of the first image. [Diagram 5] FIG. 5 is a photograph showing an example of the second image. [Figure 6] FIG. 6 is an example of an image in which luminance values ​​have been subjected to a synthesis operation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the invention disclosed herein will be described with reference to the drawings. Note that the present invention is not limited to the following embodiment. Each drawing is drawn in a schematic manner and does not necessarily reflect the actual product. Moreover, each drawing shows only an example, and does not limit the present invention unless otherwise specified. Moreover, the same reference numerals are appropriately assigned to members and parts that perform the same function, and duplicate explanations are omitted.

[0014] Fig. 1 is a schematic side view of the appearance inspection apparatus 10. Fig. 2 is a schematic plan view of the appearance inspection apparatus 10. As shown in Figs. 1 and 2, the appearance inspection apparatus 10 includes an inspection stage 11, a plurality of cameras 12, a first illumination 13, a second illumination 14, and a processing device 15.

[0015] <Test subject 2> In this embodiment, the test object 2 is a molded product having a substantially cylindrical shape. The test object 2 is made of an elastic body such as rubber or elastomer. The test object 2 has protrusions 2a and 2b protruding in the outer diameter direction at the upper and lower parts in the axial direction, which are continuously provided in the circumferential direction. In this way, the test object 2 may have protrusions protruding in the outer diameter direction formed at predetermined positions. In addition, several faces 2c are formed along the circumferential direction on the side peripheral surface, and ridge lines 2d are provided at the boundaries between the faces 2c. Many cylindrical molded products, such as gaskets inserted into syringes as medical rubber parts and caps attached to syringe nozzles, have such protrusions and ridge lines. The test object 2 shown in FIG. 1 and FIG. 2 is an example. The shape of the test object to be inspected by the appearance inspection device 10 is not limited to the shape shown in FIG. 1 and FIG. 2. In a shape having protrusions 2a, 2b and ridges 2d like this, when light is shone on it, the parts on which the light hits become bright due to the protrusions 2a, 2b and ridges 2d, and at the same time, shadows are cast behind them, making them dark.

[0016] <Test stage 11> The inspection stage 11 is a stage on which the object under test 2 is placed. In this embodiment, since the object under test 2 is a cylindrical molded product such as a gasket or a cap, the inspection stage 11 can be, for example, a circular pedestal on which the object under test 2 is placed. In this embodiment, the inspection stage 11 uses a pedestal that is the same size as or slightly larger than the bottom surface of the object under test 2. Also, as long as the object under test 2 can be placed stably, the upper surface 11a of the inspection stage 11 may be smaller than the bottom surface of the object under test 2.

[0017] <Camera 12> The camera 12 is arranged so as to photograph the object 2 placed on the inspection stage 11 from the side of the object 2. In this embodiment, as shown in FIG. 1 and FIG. 2, the appearance inspection device 10 includes a plurality of cameras 12. The plurality of cameras 12 are arranged so as to photograph the object 2 placed on the inspection stage 11 from a plurality of directions divided in the circumferential direction. The plurality of cameras 12 (six cameras in the example shown in FIG. 2) are arranged at predetermined intervals around the object 2 placed on the inspection stage 11. Here, for example, CA-H200M manufactured by Keyence Corporation may be used as the camera 12. Furthermore, ML-M3520UR manufactured by Moritex Corporation may be used as the lens associated with the camera 12. Furthermore, an intermediate ring may be used between the lens and the light receiving part of the camera. ANB84805 manufactured by Panasonic Corporation may be used as the intermediate ring. The intermediate ring may be used when the distance between the camera and the subject cannot be sufficiently secured due to the layout of the equipment. The intermediate ring is also called the close-up ring.

[0018] <First Lighting 13, Second Lighting 14> The first illuminator 13 is an illuminator that irradiates light from above onto the position on the inspection stage 11 where the object to be inspected 2 is placed. The second illuminator 14 is an illuminator that irradiates light from below onto the position on the inspection stage 11 where the object to be inspected 2 is placed. The first illuminator 13 may be configured, for example, to irradiate illumination light or reflected light onto the side surface of the object to be inspected 2 from above. The second illuminator 14 may be configured, for example, to irradiate illumination light or reflected light onto the side surface of the object to be inspected 2 from below.

[0019] In the embodiment shown in FIG. 1, the first illumination 13 is composed of an upper ring illumination 41 (also referred to as a first ring illumination here) that irradiates light from above onto the position where the inspection object 2 is placed on the inspection stage 11. The second illumination 14 is composed of a lower ring illumination 42 (also referred to as a second ring illumination here) that irradiates light from below onto the position where the inspection object 2 is placed on the inspection stage 11. The upper ring illumination 41 and the lower ring illumination 42 are preferably configured to irradiate light at an approximately predetermined angle onto the position where the inspection object 2 is placed. By employing the ring illuminations 41 and 42 as the first illumination 13 and the second illumination 14, respectively, uniform light is irradiated in the circumferential direction onto the side surface of the inspection object 2 placed on the inspection stage 11. The first illumination 13 and the second illumination 14 are preferably connected to the processing device 15, and are preferably configured to control the timing of turning them on and off.

[0020] FIG. 3 is a side view that shows a schematic diagram of a visual inspection apparatus 10A showing another embodiment.

[0021] In the embodiment shown in FIG. 3, the second illumination 14 has a reflecting surface 51 and an illuminator 52. The reflecting surface 51 is provided around the position where the inspection object 2 on the inspection stage 11 is placed, below the inspection object 2 placed on the inspection stage 11. The illuminator 52 may be a lighting device that reflects light on the reflecting surface 51 and irradiates the inspection object 2 from below. In this case, the reflecting surface 51 and the illuminator 52 are preferably arranged so that the light of the illuminator 52 is reflected and the inspection object 2 is irradiated from below. In this way, the reflecting surface 51 is preferably arranged below the inspection object 2 placed on the inspection stage 11, and the illuminator 52 may be arranged above the inspection stage 11. When the reflecting surface 51 is used in this way, even if another object is placed below the inspection stage 11 and an illuminator cannot be placed, the inspection object 2 can be configured to be irradiated with light from below.

[0022] <Reflective surface 51> In the embodiment shown in FIG. 3, the reflection surface 51 is provided around at least the position of the inspection stage 11 where the inspection object 2 is placed. In this embodiment, the inspection stage 11 is made of a white resin having a high reflectance overall, and the upper surface of the inspection stage 11 constitutes the reflection surface 51. In this case, the inspection stage 11 provided with the reflection surface 51 can be made of, for example, a resin base. Therefore, it can be constructed relatively inexpensively. A reflector made of a plate having a high reflectance may be attached to the upper surface of the inspection stage 11. In this way, the reflection surface 51 may be constructed on the upper surface of the inspection stage 11. The reflection surface 51 is not limited to such a form. The reflection surface 51 may be provided at an appropriate angle so that the light from the illuminator 52 is reflected toward the side surface of the inspection object 2. In addition, the reflection surface 51 may be disposed at an appropriate position so that the light from the illuminator 52 is reflected toward the side surface of the inspection object 2.

[0023] <Illuminator 52> The illuminator 52 is arranged above the inspection stage 11 and is configured with a spot illuminator 61 that reflects light on the reflecting surface 51 and irradiates the inspection object 2 from below. In this case, a light-shielding masking 62 that blocks the center of the light of the spot illuminator 61 is further provided. In the embodiment shown in FIG. 3, the first ring illuminator 41 constituting the first illuminator 13 has a transparent plate 63 attached to the inside. The spot illuminator 61 is provided above the transparent plate 63. The light-shielding masking 62 is provided on the transparent plate 63. In this case, the light irradiated from the spot illuminator 61 is blocked at the center by the light-shielding masking 62. The light passes through the transparent plate 63 around the light-shielding masking 62 and is reflected by the reflecting surface 51 provided on the upper surface 11a of the inspection stage 11. The light reflected by the reflecting surface 51 illuminates the side peripheral surface of the inspection object 2 placed on the inspection stage 11 from below.

[0024] In this embodiment, a light-shielding mask 62 is disposed directly above the inspection object 2, and a spot light 61 is disposed directly above the light-shielding mask 62. The light of the spot light 61 is blocked at the center by the light-shielding mask 62, and passes through a transparent plate 63 around the light-shielding mask 62. A part of the light that passes through the transparent plate 63 is reflected by the reflecting surface 51 and irradiated onto the circumferential side surface of the inspection object 2. The circumferential side surface of the inspection object 2 is irradiated with light that is approximately uniform in the circumferential direction. The position and shape of the mask 62 may be appropriately set depending on the position, size, shape, etc. of the inspection object 2 disposed on the inspection stage 11. The transparent plate 63 may be a translucent plate as long as it transmits light.

[0025] In the embodiment shown in Fig. 3, the reflective surface 51 may be subjected to an appropriate surface treatment to suppress diffusion of light. In the embodiment shown in Fig. 3, the spot lighting 61 installed above is an LDR2-50SW2 manufactured by CCS Inc. In addition, the ring lighting 41 installed below the spot lighting 61 may be an HPR2-150SW manufactured by CCS Inc.

[0026] Although not shown in the drawings, the appearance inspection apparatus is not limited to the above-described embodiment. The configuration of the first illuminator 13 that irradiates the side surface of the inspection object 2 placed on the inspection stage 11 with light from above, and the second illuminator 14 that irradiates the side surface of the inspection object 2 placed on the inspection stage 11 with light from below are not limited to the above-described embodiment, and can be changed to various forms. For example, the illuminator 52 of the second illuminator 14 may be a panel illuminator. In this case, the panel illuminator may be arranged so that light is irradiated downward inside (inner diameter side) of the first ring illuminator 41 that constitutes the first illuminator 13. A light-shielding masking may be attached to the center of the panel illuminator as the second illuminator 14. Alternatively, the panel illuminator as the second illuminator 14 may be a ring-shaped panel illuminator. When the panel illuminator is a ring-shaped panel illuminator, the light-shielding masking may not be required. In this embodiment, light from the panel illumination as the second illumination 14 is reflected by the reflecting surface 51 of the inspection stage 11 and irradiated onto the side peripheral surface of the inspection object 2 placed on the inspection stage 11. In this case, light reflected by the reflecting surface 51 from the panel illumination is irradiated onto the side peripheral surface of the inspection object 2, and the side peripheral surface of the inspection object 2 is irradiated with light that is approximately uniform in the circumferential direction.

[0027] In this way, various examples have been given of the configurations of the first illumination 13 and the second illumination 14 of the appearance inspection device 10. The first illumination 13 may be configured to irradiate illumination light or reflected light onto the side surface of the inspection object from above. The second illumination 14 may be configured to irradiate illumination light or reflected light onto the side surface of the inspection object from below. In this respect, the present invention is not limited to the above-mentioned embodiment. Here, the first illumination 13 and the second illumination 14 may have different wavelengths of light. For example, when inspecting minute irregularities, it is preferable to use illumination with a short wavelength (blue). When illumination with a short wavelength (blue) is used, it is expected that the resolution will be high. On the other hand, when the subject base material itself has fine irregularities, illumination with a long wavelength (red) may be used to reduce the influence of the unevenness of the base material. In this way, illumination with different wavelengths of light may be used according to the characteristics of the inspection object 2. In addition, a polarized lens may be attached to at least one of the light-emitting surfaces of the first illumination 13 and the second illumination 14 and the lens tip of the camera 12. In this case, the polarizing lens is used to remove the reflected light of the illumination reflected on the inspection subject 2. For example, attaching the polarizing lens can be effective in inspecting the inspection subject 2 whose surface is covered with a film or the like and which is prone to reflecting light.

[0028] Processing device 15 The processing device 15 is a device that performs various processes of the appearance inspection device 10. The processing device 15 can be embodied by a computer that operates according to a predetermined program. Specifically, each function of the processing device 15 is processed by an arithmetic device (also called a processor, a CPU (Central Processing Unit), or an MPU (Micro-processing unit)) or a storage device (such as a memory or a hard disk) of each computer that constitutes the processing device 15. For example, each configuration of the processing device 15 can be embodied as a database that stores data embodied by a computer in a predetermined format, a data structure, a processing module that performs a predetermined arithmetic process according to a predetermined program, or a part of them. Although not shown in the figure, the processing device 15 may be one in which multiple control devices work together. For example, when the processing device 15 of the appearance inspection device 10 is connected to an external computer so as to be able to perform data communication through a LAN cable, the Internet, or the like, the processing of the processing device 15 may be performed in cooperation with such an external computer. For example, the information or a part of the information stored in the processing device 15 may be stored by an external computer, and the processing or a part of the processing performed by the processing device 15 may be performed by an external computer.

[0029] The processing device 15 is configured to perform a process 31 for acquiring a first image, a process 32 for acquiring a second image, and a judgment process 33 for judging pass / fail. In this embodiment, the processing device 15 is configured to operate the camera 12, the first lighting 13, and the second lighting 14 according to a predetermined program. The processing device 15 is electrically connected to the camera 12, the first lighting 13, and the second lighting 14 through a communication network. The communication network may be either a wired or wireless network. The first image and the second image are captured by the processing device 15 appropriately operating the first lighting 13, the second lighting 14, and the camera 12.

[0030] <Image 1> The first image is an image of the inspection object 2 placed on the inspection stage 11 photographed by the camera 12 with the second illumination 14 turned off and the first illumination 13 turned on. In the process 31 of acquiring the first image, it is preferable that the inspection object 2 placed on the inspection stage 11 is photographed by the camera 12 with the second illumination 14 turned off and the first illumination 13 turned on.

[0031] FIG. 4 is a photograph showing an example of the first image. The inspection object 2 shown in the photograph of FIG. 4 has a shape similar to that shown in FIG. 1. The inspection object 2 is a molded product having a substantially cylindrical shape. The inspection object 2 has protrusions 2a and 2b protruding in the outer diameter direction at the upper and lower parts in the axial direction, which are continuously provided in the circumferential direction. Several faces 2c are formed along the circumferential direction on the side peripheral surface, and a ridge line 2d is provided at the boundary between the faces 2c. As shown in FIG. 4, when the inspection object 2 placed on the inspection stage 11 is photographed by the camera 12 with the second illumination 14 turned off and the first illumination 13 irradiated, the light of the first illumination 13 is likely to hit the upper side of the protrusion on the side peripheral surface of the inspection object 2. In addition, a shadow due to the light of the first illumination 13 is likely to be generated on the lower side of the protrusion. In the example of the first image shown in FIG. 4, the upper side of the protrusion 2b at the lower part of the inspection object 2 is likely to be hit by the light of the first illumination 13, and has high brightness. In addition, the area below the protrusion 2a at the top of the test object 2 is prone to shadows, resulting in low brightness.

[0032] <Image 2> The second image is an image of the inspection object 2 placed on the inspection stage 11 photographed by the camera 12 with the first illumination 13 turned off and the second illumination 14 turned on. In the process 32 of acquiring the second image, it is preferable that the inspection object 2 placed on the inspection stage 11 is photographed by the camera 12 with the first illumination 13 turned off and the second illumination 14 turned on.

[0033] FIG. 5 is a photograph showing an example of the second image. The test object 2 shown in the photograph of FIG. 5 is the same as the test object 2 shown in FIG. 4. As shown in FIG. 5, when the test object 2 placed on the inspection stage 11 is photographed by the camera 12 with the first illumination 13 turned off and the second illumination 14 irradiated, the light of the second illumination 14 is likely to hit the underside of the protrusion on the side circumference of the test object 2. Also, a shadow caused by the light of the second illumination 14 is likely to be formed on the upper side of the protrusion. For this reason, in the example of the second image shown in FIG. 5, the underside of the protrusion 2b at the top of the test object 2 is likely to be hit by the light of the second illumination 14, and has high brightness. Also, the underside of the protrusion 2a at the top of the test object 2 is likely to be shadowed and has low brightness.

[0034] <Determination Process> The judgment process is a process for judging the quality of the photographed inspection object based on the first image and the second image.

[0035] For example, if there is a dent on the side surface of the test object 2, in the first image, a shadow is generated at the top of the dent, resulting in a low brightness, and the brightness of the bottom of the dent tends to be high. In addition, in the second image, a shadow is generated at the bottom of the dent, resulting in a low brightness, and the brightness of the top of the dent tends to be high. In addition, if there is a raised portion on the side surface of the test object 2, in the first image, the brightness of the top of the raised portion is high, and the brightness of the bottom of the raised portion is low. In addition, in the second image, the brightness of the bottom of the raised portion is high, and the brightness of the bottom of the raised portion is low. A dent or raised portion at a predetermined position of a molded product is normal, but if there is a dent or raised portion at a position other than the predetermined position, there is a possibility that the molding is defective. In this way, the first image and the second image are acquired, and by determining whether there is a dent or raised portion at a position other than the predetermined position, the quality of the photographed test object can be determined.

[0036] On the side peripheral surface of the inspection object 2 shown in FIG. 1, several faces 2c are formed along the circumferential direction, and ridge lines 2d are provided at the boundaries of the faces 2c. In this embodiment, as shown in FIG. 2, a plurality of cameras 12 are arranged around the inspection stage 11 at predetermined intervals so that the inspection object 2 is photographed from a plurality of directions divided in the circumferential direction of the inspection stage 11. The plurality of cameras 12 are arranged so that the side peripheral surface of the inspection object 2 placed on the inspection stage 11 can be photographed over the entire circumference as a whole. Therefore, the faces 2c and the ridge lines 2d formed on the side peripheral surface of the inspection object 2 are also captured in one of the images. In this case, if the faces 2c and the ridge lines 2d have recesses or raised portions, the faces 2c will have portions with changed brightness, and the ridge lines 2d will have portions with distorted brightness.

[0037] 1 and 2, the appearance inspection device 10 includes a plurality of cameras 12 for photographing the side of the inspection object 2 placed on the inspection stage 11, a first illuminator 13 for irradiating the side surface of the inspection object 2 with light from above, and a second illuminator 14 for irradiating the side surface of the inspection object 2 with light from below. The processing device 15 is configured to determine the quality of the inspection object 2 based on a first image taken of the inspection object 2 with the second illuminator 14 turned off and the first illuminator 13 turned on, and a second image taken of the inspection object 2 with the first illuminator 13 turned off and the second illuminator 14 turned on. In this case, the first illuminator 13 and the second illuminator 14 apply light to the side surface of the inspection object 2 from above and below, respectively. Then, a first image is obtained by applying light from above to the side peripheral surface of the inspection object 2 by the first illumination 13, and a second image is obtained by applying light from below.

[0038] This makes it possible to produce vertical shadows when uneven molding defects or scratches occur on the side circumferential surface of the inspection object 2. Shadows caused by undulations specific to the product can also be inspected by using the image of the side where light hits the undulations. In this way, the quality of the photographed side circumferential surface of the inspection object 2 can be judged based on the first image obtained by illuminating the side circumferential surface of the inspection object 2 from above with the first illumination 13, and the second image obtained by illuminating the side circumferential surface from below.

[0039] In this embodiment, as described above, the first illuminator 13 and the second illuminator 14 each irradiate the side peripheral surface of the inspection object 2 with light of uniform illuminance in the circumferential direction. Therefore, in the first image and the second image, the luminance of the light-irradiated portion and the shadow of the shaded portion are approximately the same. Therefore, the quality of the side peripheral surface of the inspection object 2 that has been photographed can be accurately determined.

[0040] In this embodiment, the multiple cameras 12 are arranged so that the inspection object 2 placed on the inspection stage 11 is photographed from multiple directions divided in the circumferential direction. Therefore, the entire circumference of the side surface of the inspection object 2 can be photographed without rotating the inspection object 2 placed on the inspection stage 11. Since the entire circumference of the side surface of the inspection object 2 can be photographed without rotating the inspection object 2 placed on the inspection stage 11, misalignment of the rotation does not occur. Therefore, stable inspection is possible, and defective parts can be identified with high accuracy. Furthermore, since multiple cameras 12 are used, the time required to photograph the entire circumference of the side surface of the inspection object 2 is short.

[0041] In addition, the first illumination 13 and the second illumination 14 illuminate the side surface of the inspection object 2 from above and below. The camera 12 captures the side surface of the inspection object 2 from the radial direction. Therefore, even if the inspection object 2 has a cylindrical shape, the variation in brightness value in the circumferential direction is suppressed to be small. The inspection area per camera 12 is wider than when light is applied from the horizontal direction of the inspection object 2. Therefore, even if multiple cameras 12 are arranged along the circumferential direction of the inspection stage 11, the number of cameras 12 required is small, and the equipment cost is suppressed to be small. For example, in this embodiment, six cameras 12 cover an area divided into six in the circumferential direction of the inspection object 2. The number of cameras 12 is not limited to six, and may be even less, such as five, four, or three.

[0042] In the judgment process, the quality of the photographed object may be judged based on a process of removing the shading gradient of the photographed object in the first image, a process of removing the shading gradient of the photographed object in the second image, and the first and second images from which the shading gradient has been removed. For example, as shown in FIG. 1, when the object 2 is a member having a substantially cylindrical shape, even if light is evenly applied in the circumferential direction, the part closer to the light tends to appear brighter, and the part farther from the light tends to appear darker. Also, when the illuminance of the light irradiated to the object 2 is uneven in the circumferential direction, uneven brightness may occur in the circumferential direction of the object 2. In such a case, a certain shading gradient tends to occur in the photographed object 2 in the circumferential direction of the object 2. For this reason, the shading can be removed by performing a process of removing the shading gradient of the photographed object in the first image and a process of removing the shading gradient of the photographed object in the second image. For example, FIG. 4 and FIG. 5 are photographs before the shading is removed. In this case, the gray gradient tends to be stronger in the height direction than in the circumferential direction, as shown in Figures 4 and 5. The process of removing the gray gradient can also remove this tendency. By performing the process of removing the gray gradient of the inspection object 2 in the first and second images, the gray gradient in the height direction and circumferential direction of the inspection object 2 is removed, and the accuracy of the pass / fail judgment of the photographed inspection object 2 can be improved.

[0043] The process of removing the shading gradient here can be realized by a process of removing shading using a real-time shading correction filter in commercially available image processing software such as XG8500 manufactured by Keyence Corporation. According to this process, the gradual change in shading (shading) on ​​the surface of the photographed inspection object 2 is removed by calculating the difference between the input image and the internally processed image created from the input image. By removing the change in shading on the surface of the photographed inspection object 2, the part with a steep change in contrast is emphasized and extracted. In addition, the contrast of the side surface of the photographed inspection object 2 may be uniformly corrected using the average value or median value of the density within the region.

[0044] The determination process may be configured to, for example, calculate the difference in luminance value between adjacent pixels or pixel groups in a first image from which the grayscale gradient has been removed and a second image from which the grayscale gradient has been removed, and determine that the area is defective if the difference is equal to or greater than a threshold value. When there are no molding defects such as scratches, the difference in luminance value between adjacent pixels or pixel groups vertically or horizontally is roughly constant. In a first image from which the grayscale gradient has been removed and a second image from which the grayscale gradient has been removed, the difference in luminance value between adjacent pixels or pixel groups vertically or horizontally is calculated, and areas where the difference is equal to or greater than a threshold value are suspected to be defective. For this reason, the process may be configured to determine that the area is defective.

[0045] In this case, the pixel group means a group of pixels in an arbitrarily determined area that is regarded as one block. In other words, instead of evaluating the difference for each pixel, a plurality of pixels in an area where a plurality of pixels are gathered may be regarded as one pixel group, and the difference may be evaluated for the pixel group. This allows the surface condition of the inspected object 2 to be evaluated in an area of ​​appropriate size that is not too small and not too subdivided. The size of the area that defines the pixel group may be set to an appropriate size for evaluating the surface condition of the inspected object 2. For example, a rectangular pixel area such as 4 (2×2), 9 (3×3), or 16 (4×4) may be set. By calculating the difference in brightness value for each pixel group of appropriate size in this way, the possibility of false detection of molding defects, scratches, etc. is reduced. The brightness value of the pixel group may also be evaluated, for example, by the average brightness value of the pixels included in the pixel group.

[0046] The processing device 15 may include a process for obtaining an image obtained by performing a synthesis operation on the luminance values ​​of the first image from which the grayscale gradient has been removed and the second image from which the grayscale gradient has been removed. In this case, the judgment process may include a process for judging whether the photographed inspection object 2 is good or bad based on the image from which the luminance values ​​have been synthesized. When there is no molding defect such as a scratch, the difference in luminance values ​​between pixels or pixel groups adjacent vertically or horizontally is approximately constant. In a normal product, the image obtained by performing a synthesis operation on the luminance values ​​of the first image from which the grayscale gradient has been removed and the second image from which the grayscale gradient has been removed will have an approximately constant pattern. In other words, the normal inherent undulations, ridges, protrusions, etc. of a molded product are obtained in a constant pattern of luminance value differences. For this reason, by obtaining an image obtained by performing a synthesis operation on the luminance values ​​of the first image from which the grayscale gradient has been removed and the second image from which the grayscale gradient has been removed, and taking the difference from a pattern of luminance value differences of a normal product prepared in advance, a portion with a certain or greater difference can be extracted as a portion suspected of being defective. When a portion suspected of being defective is extracted, it may be configured to be judged as a defective portion.

[0047] Here, the "composite operation" may employ an appropriate calculation method for evaluating the surface state of the inspection object 2 using the first image from which the grayscale gradient has been removed and the second image from which the grayscale gradient has been removed, and extracting defective parts. In other words, performing a composite operation on the luminance values ​​includes various processes for combining the luminance values ​​using a predetermined arithmetic expression. Here, the composite operation may involve, for example, simply adding up the luminance values. Furthermore, the composite operation is not limited to simply adding up the luminance values, and may involve subtraction, averaging, addition or subtraction of absolute values, etc. The method of the composite operation may be determined by performing a test in advance and determining an appropriate calculation method for extracting defective parts.

[0048] For example, FIG. 6 shows an image in which the luminance values ​​are combined. FIG. 6 shows an image obtained by the difference between the luminance values ​​of the first image shown in FIG. 4 and the second image shown in FIG. 5. In the first image shown in FIG. 4 and the second image shown in FIG. 5, there is a defective part with a gentle bulge in the blue enclosure A. Such an abnormality may appear normal depending on the material of the inspected object 2 and the way the light hits it, so it may be difficult to distinguish even with the naked eye. Even in this case, as described above, the first image illuminated from above and the second image illuminated from below are obtained, and the grayscale gradient is removed. Furthermore, according to the image in which the difference in luminance values ​​is combined, the parts with different contrasts are emphasized as shown in FIG. 6. This makes it easier to extract defective parts in computer image processing.

[0049] In the determination process, if the difference in luminance value between adjacent pixels or pixel groups in an image obtained by combining and calculating the luminance values ​​of the first image and the second image is equal to or greater than a predetermined threshold, the pixel or pixel group may be determined to be a defective part. For example, if there is a scratch on the circumferential surface of the test object 2, the difference in luminance value between adjacent pixels or pixel groups is clearly apparent. For this reason, it becomes easy to extract the scratch on the circumferential surface of the test object 2 by determining whether the difference in luminance value between adjacent pixels or pixel groups vertically or horizontally is equal to or greater than a predetermined threshold.

[0050] The processing device 15 may store in advance reference data indicating the distribution of luminance values ​​in a plurality of areas for an image obtained by combining and calculating the luminance values ​​of the first image and the second image when the inspected object 2 is normal. In this case, the determination process may be configured to extract defective portions based on the distribution of luminance values ​​in the image obtained by combining and calculating the luminance values ​​of the first image and the second image and the reference data.

[0051] 1, the processing device 15 may include a display 40. The processing device 15 may be configured to display the color of each pixel in the multiple areas in a predetermined color according to the difference between the distribution of luminance values ​​in an image obtained by synthesizing the luminance values ​​of the first image and the second image and the luminance value distribution of the reference data. In this case, the defective portion is clearly indicated to the user through the image displayed on the display 40.

[0052] Furthermore, the processing device 15 may be configured to use a machine learning model such as a neural network to determine the quality of the photographed object 2. In this case, it is preferable that the first and second images of the object 2 and data indicating the positions of defects such as scratches on the photographed object 2 that appear in the first and second images are prepared as learning data. It is preferable that a trained machine learning model is prepared so that a quality determination of the photographed object 2 is output as a result based on the first and second images of the object 2 by learning such learning data. A neural network may be used as the machine learning model.

[0053] If the result of the pass / fail judgment is defective, the defective part of the photographed test object 2 may be further specified. The defective part of the test object 2 may be specified, for example, by outputting position information, color-coding the defective part on the display, or by surrounding it with a figure such as a circle. This makes it easier for the user to understand the position of the defective part.

[0054] In this case, for example, the processing device 15 may be equipped with a machine learning model configured to learn the first image, the second image, and the position of scratches on the photographed object as learning data, and to determine the quality of the photographed object based on the first image and the second image.

[0055] In addition, the processing device 15 may be equipped with a machine learning model configured to learn the first image and the second image from which the gray scale gradient has been removed and the positions of scratches on the photographed object to be inspected as learning data, and to determine the quality of the photographed object to be inspected based on the first image and the second image from which the gray scale gradient has been removed.

[0056] The processing device 15 may include a machine learning model configured to learn the image obtained by the luminance value synthesis operation and the position of a flaw in the photographed object as learning data, and to judge the quality of the photographed object based on the image obtained by the luminance value synthesis operation. Examples of the machine learning model are not limited to those exemplified here.

[0057] As described above, the appearance inspection device 10 includes the inspection stage 11, the camera 12, the first illuminator 13, the second illuminator 14, and the processing device 15. The inspection stage 11 is a base on which the object under inspection 2 is placed. The camera 12 is an imaging device that images the object under inspection 2 placed on the inspection stage 11 from the side of the object under inspection 2. The first illuminator 13 is an illumination that irradiates the side surface of the object under inspection 2 placed on the inspection stage 11 with light from above. The first illuminator 13 is an illumination that irradiates the side surface of the object under inspection 2 placed on the inspection stage with light from below.

[0058] In the appearance inspection device 10, the following steps 31 to 33 are executed (see FIG. 1). Process 31: A process of acquiring a first image of the inspection object 2 placed on the inspection stage 11 by the camera 12 with the second illumination 14 turned off and the first illumination 13 turned on. Process 32: A process of acquiring a second image of the inspection object 2 placed on the inspection stage 11 by the camera 12 with the first illumination 13 turned off and the second illumination 14 turned on. Process 33: A process for determining whether the photographed inspection object 2 is good or bad based on the first image and the second image.

[0059] Such visual inspection device 10 can accurately extract defects that have occurred on the side surfaces of the object to be inspected 2, such as uneven defects such as dents and bulges, cracks, distortion of the tapered shape of protrusions, warping, and other defects that are excluding the inherent unevenness of normal products, thereby enabling a stable pass / fail judgment to be made.

[0060] In the process of obtaining the first and second images, the embodiment described above is provided with a plurality of cameras 12 that capture images of the inspection object 2 placed on the inspection stage 11 from a plurality of directions divided in the circumferential direction (see FIG. 1). Unless otherwise specified, in the appearance inspection device 10, the cameras 12 may be movable relative to the inspection stage 11. In this case, the camera 12 may be configured as a single unit. The inspection stage 11 may be one that rotates with the inspection stage 11. Also, the camera 12 may be configured to rotate around the inspection stage 11.

[0061] Although the invention disclosed herein has been described in various ways, the invention disclosed herein is not limited to the above-mentioned embodiments and modifications unless otherwise specified. Furthermore, the configurations of the various embodiments and modifications mentioned above can be appropriately combined as long as they are not mutually inhibiting. [Explanation of symbols]

[0062] 2. Subject 2a,2b protrusion 2d Edge 10,10A Visual inspection device 11 Inspection Stage 12 Camera 13 First Lighting 14 Second Lighting 15 Processing Equipment 31 Process to obtain the first image 32. Processing to obtain the second image 33 Judgment process 41 Upper ring light (first ring light) 42 Lower ring light (second ring light) 51 Reflective surface 52 Illumination equipment 61 Spot Lighting 62 Masking 63 Transparent plate

Claims

1. an inspection stage on which an object to be inspected is placed and on which a reflecting surface is provided at least around the periphery of the position on which the object to be inspected is placed; At least one camera that captures an image of the object to be inspected placed on the inspection stage from a side of the object to be inspected; a first illuminator which is a ring illuminator that irradiates a side peripheral surface of the inspection object placed on the inspection stage with light from above; a second illumination device that includes a spot illumination device disposed above the inspection stage and that illuminates a side peripheral surface of the inspection object placed on the inspection stage from below by reflecting light on the reflecting surface; Processing equipment and Equipped with The processing device includes: a process of acquiring a first image of an object to be inspected placed on the inspection stage by the camera in a state in which the second illumination is turned off and the first illumination is applied; a process of acquiring a second image of an object to be inspected placed on the inspection stage by the camera in a state in which the first illumination is turned off and the second illumination is applied; A determination process for determining whether the photographed object is good or bad based on the first image and the second image. A visual inspection apparatus configured to carry out the above steps.

2. An appearance inspection apparatus as described in claim 1, further comprising a light-shielding masking positioned directly above the object to be inspected placed on the inspection stage.

3. An appearance inspection device as described in claim 2, wherein a light-transmitting plate is placed directly above the object to be inspected placed on the inspection stage, the light-blocking masking is provided on the light-transmitting plate, and the second lighting consisting of the spot lighting is placed directly above the masking.

4. An appearance inspection device described in any one of claims 1 to 3, wherein the reflective surface has a surface treatment applied thereto to suppress light diffusion.

5. The determination process includes: A process of removing a gray gradient of the photographed object from the first image; A process of removing a gray gradient of the photographed object from the second image; a judgment process for judging whether the photographed object is good or bad based on the first image and the second image from which the gray scale gradient has been removed; 5. The visual inspection apparatus according to claim 1, further comprising:

6. The determination process calculates a difference in luminance between adjacent pixels or groups of pixels in a first image from which a gradient has been removed and a second image from which a gradient has been removed; If the difference is equal to or greater than the threshold, it is determined to be a defective part.

6. The visual inspection apparatus according to claim 5.

7. The processing device includes: The method includes a process of obtaining an image by performing a synthesis operation on the luminance values ​​of the first image and the second image from which the gray scale gradient has been removed, and The determination process includes: In an image obtained by synthesizing the luminance values ​​of the first image and the second image, if a difference in luminance value between adjacent pixels or pixel groups is equal to or greater than a predetermined threshold value, the pixel or pixel group is determined to be a defective portion.

7. An appearance inspection apparatus according to claim 5 or 6.

Images