JP5773741B2 - Appearance inspection apparatus and appearance inspection method for transparent body bottle - Google Patents

Description

  The present invention relates to an appearance inspection apparatus and an appearance inspection method for inspecting a defect in a top surface portion of a transparent bottle such as a PET bottle or a PET bottle preform.

  Conventionally, in order to inspect the presence or absence of defects present on an inspection object, a technique has been used in which a specific region of the inspection object is imaged and the presence or absence of scratches is determined by image processing based on the increase in the number of images captured. . This inspection method is used for a wide variety of articles, and this method is also used for visual inspection of PET bottles.

  For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-267611), in a top inspection of a PET bottle, a cylinder that projects a peripheral image of a workpiece between the workpiece and a peripheral camera that captures an image from above the workpiece. There is disclosed an inspection apparatus provided with a top surface projecting means for projecting a top surface image so that the top surface image can be imaged from the side by a top surface camera for providing a top surface image.

  This inspection apparatus projects the peripheral surface of the opening portion of the plastic bottle by the peripheral surface projecting means configured in a bowl shape, and shoots with the peripheral surface camera provided above the opening portion, and above the opening portion. An image of the top of the opening is taken by the top camera from the side with the provided top projection means. Thereby, a top surface and a surrounding surface are imaged, and the presence or absence of a defect is inspected based on the image.

JP 2002-267611 A

  However, it has been difficult for the inspection apparatus to inspect the top surface for defects with high accuracy. In general, in order to increase the accuracy of defect determination by image analysis, the top surface is imaged by setting the optical path so that the imaging optical axis is orthogonal to the aperture, and capturing the image so that the top surface is circular. That is, when imaging the top surface of a plastic bottle opening, the periphery of the opening is imaged with high definition by disposing a camera at a position that regularly reflects incident light.

  However, as shown in FIG. 9, the opening 101 of the PET bottle 100 is a portion that directly touches the mouth of the consumer, and usually reduces the uncomfortable feeling given to the consumer during drinking. Is a chamfered portion 103 formed into a curved surface. For this reason, the light irradiated onto the top surface 102 has a reflection angle that differs depending on the chamfered portion 103 and cannot reach the camera. For this reason, the chamfered portion 103 has a problem that the defect determination accuracy by image analysis is low.

  The chamfered portion 103 is a portion that directly contacts the customer's mouth, and defects such as scratches present in the chamfered portion 103 affect the evaluation of the plastic bottle. Therefore, there has been a demand for an inspection apparatus that can accurately determine the presence or absence of defects in the chamfered portion.

  Therefore, the technical problem to be solved by the present invention is to provide an inspection device and an appearance inspection method that can determine the presence or absence of defects in the opening of a plastic bottle with high accuracy.

  In order to solve the above technical problem, the present invention provides a transparent bottle appearance inspection apparatus and appearance inspection method having the following configuration.

According to the first aspect of the present invention, the transparent bottle having the opening can be irradiated with light having the first frequency from the first optical path intersecting the opening, and provided on the opening side . One light source unit;
A second light source unit capable of irradiating light having a second frequency from a second optical path intersecting the opening and in a direction opposite to the first optical path;
An area camera that is arranged so that a photographing optical axis is orthogonal to the opening, and that can detect and radiate light emitted from the first light source unit and the second light source unit;
After specifying the inspection area based on the first image by the light from the first light source unit imaged by the area camera, based on the second image by the light from the first image and the second light source unit. And a defect determining unit that determines whether or not there is a defect in the opening.

  According to a second aspect of the present invention, the second optical path passes through the wall of the transparent bottle and reaches the area camera from the top of the opening. The transparent bottle according to the first aspect The visual inspection apparatus is provided.

According to the third aspect of the present invention, the defect determination unit identifies an inner edge circle along the inner periphery of the opening using the first image, and after centering with the inner edge circle, An outer edge circle and an intermediate circle are specified from the inner edge circle and the center position, and the specified inner edge circle and the outer edge circle are determined based on luminance values of pixels existing on the circle of the second image. The transparent bottle appearance inspection apparatus according to the first aspect is characterized in that the defect determination is performed on the top based on the luminance value of the pixel existing on the circle of the first image.

According to the 4th aspect of this invention, it has further provided the light-shielding part which shields the light from the 2nd light source part which is provided under the transparent body bottle opening part, and exists in the outer peripheral area | region of the said opening part. An appearance inspection apparatus for a transparent bottle according to any one of the first to third aspects is provided.

According to the fifth aspect of the present invention, with respect to a transparent bottle having an opening, light having a first frequency is emitted from the upper part of the opening to the opening through the first optical path intersecting the opening. Irradiating from the bottom surface side of the transparent bottle with a second optical path that is opposite to the first optical path and intersects the opening,
The area camera arranged so that the photographing optical axis is orthogonal to the opening determines the light emitted from the first light source unit and the second light source unit, and the first by the light from the first light source unit. Taking an image and a second image by light from the second light source unit,
After the inspection area is specified based on the first image, a defect determination process is performed based on the first image and the second image, and a transparent bottle appearance inspection method is provided.

According to the sixth aspect of the present invention, the defect determination processing uses the first image to identify an inner edge circle along the inner periphery of the opening, and after centering with the inner edge circle, An outer edge circle is specified from the inner edge circle and the center position, and an area surrounded by the inner edge circle and the outer edge circle is used as an inspection area, and the appearance inspection method for a transparent body bottle according to the fifth aspect I will provide a.

According to the seventh aspect of the present invention, the defect determination process specifies an intermediate circle at an intermediate position between the inner edge circle and the outer edge circle, and the first image for the intermediate circle is displayed as the inner edge circle and the outer edge. For a circle, a transparent bottle appearance inspection method according to a sixth aspect is provided, in which defect determination is performed based on the luminance value of each pixel present on the circle using the second image.

  According to this invention, the 1st light source part which irradiates light directly with respect to the opening part of transparent body bottles, such as a PET bottle and a preform, and the 2nd light source part which irradiates light from the opposite side with respect to an opening part Therefore, images having different properties can be taken. That is, the first image from the first light source unit is an image with a clear top surface outline, but the chamfered portion around the top surface periphery is not clearly imaged. On the other hand, since the second image is picked up from the direction in which the area camera is directly irradiated with light, the boundary of the top surface portion, in particular, the inner boundary of the top surface portion is not clearly picked up, but both the top surface portion and the chamfered portion are captured. Can be brightly imaged. Therefore, the defect inspection of the opening of the transparent bottle can be performed with high accuracy by using these two characteristic images.

  In the above configuration, the second optical path propagates through the wall of the transparent body bottle and exits from the top surface portion to the outside of the bottle, so that the top surface portion is clearly imaged from the camera that images the transparent body bottle from the top surface direction. Can do.

  In addition, since the first image can clearly capture the contour of the top surface, the inspection area is specified using the image, and the second image can be used to clearly capture a wide area. It is preferable to make a determination. In particular, in the defect determination, the inner edge circle and the outer edge circle specified based on the first image are based on the luminance values of the pixels existing on the circle of the second image, and the first image is displayed on the intermediate circle. By performing the defect determination based on the luminance value of the pixel existing on the circle, the inspection range can be reduced and the processing speed can be increased.

  Moreover, the outer peripheral area | region of the opening part of a transparent body bottle can be light-shielded by providing a light-shielding part below a transparent body bottle opening part. For this reason, in the second image, the light of the second light source unit is prevented from being reflected outside the transparent bottle. Therefore, by shielding the outer peripheral region of the opening, the contrast of the opening can be increased, and the defect determination by the defect determination unit can be performed with high accuracy.

It is a schematic diagram which shows the structure of the external appearance inspection apparatus of the transparent body bottle concerning 1st Embodiment of this invention. It is a schematic diagram which shows the optical path irradiated from the 1st illumination device of the external appearance inspection apparatus of the transparent body bottle of FIG. It is a figure which shows the example of a 1st image. It is a schematic diagram which shows the optical path irradiated from the 2nd illumination device of the external appearance inspection apparatus of the transparent body bottle of FIG. It is a figure which shows the example of a 2nd image. It is a functional block diagram of the image analysis part of the external appearance inspection apparatus of the transparent body bottle of FIG. It is a flowchart of the defect determination process which an image analysis part performs. It is a figure which shows the process sequence example of the defect determination process which an image analysis part performs. It is a partial expansion perspective view which shows the structure of the opening part of a PET bottle.

  A transparent bottle appearance inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a transparent bottle appearance inspection apparatus according to an embodiment of the present invention.

  The transparent bottle appearance inspection apparatus 1 according to the present embodiment has scratches, dirt, etc. on the top surface of the opening of the transparent bottle 100 exemplified by a PET bottle or a preform before being blow-molded into a PET bottle. Whether or not the image is present is determined using the image captured by the camera 2. The transparent bottle that can be inspected in the appearance inspection apparatus 1 of the present embodiment is configured to be colorless and transparent or colored and transparent, for example, partially such as a plastic bottle that is crystallized in white near the opening. Anything with an opaque part cannot be inspected. In the present invention, the opening 101 includes the top surface portion 102, the chamfered portion 103, and the opening 104.

  In the appearance inspection apparatus 1 according to the present embodiment, two illumination devices 3 and 4 arranged at different places are provided as an example of the first light source unit and the second light source unit of the present invention. Further, the appearance inspection apparatus 1 is provided with a camera 2 that captures an image of the transparent body bottle 100 to be inspected using light emitted from the first illumination device 3 and the second illumination device 4, respectively. The camera 2 and each lighting device 3, 4 are connected to a control unit 5 for driving and controlling the respective devices, and an image for determining the presence or absence of a defect based on an image captured by the camera 2. An analysis unit 6 is provided. For example, a general-purpose computer can be used as the drive device 5 and the image analysis unit 6. In this embodiment, a computer in which a driver program and an image analysis program that exhibit these functions are installed is used.

  The transparent bottle 100 is a plastic bottle or a preform before being blow-molded into a plastic bottle, and a support ring portion 110 is provided below the opening 101. The support ring unit 110 is a reference surface that serves as a position reference for molding a plastic bottle, and the appearance inspection apparatus 1 according to the present embodiment supports the support ring unit 110 for transporting and positioning the transparent body bottle 100. A clamp 7 is used. The clamp 7 is configured to be openable and closable from side to side, and a groove for receiving the support ring portion 110 is provided on the opposing surface. The clamp 7 in the opened state is disposed in the vicinity of the support ring 110 from the side of the transparent body bottle 100, and then the clamp 7 is closed, so that the position of the transparent body bottle 100 in the vertical and horizontal directions with respect to the clamp 7 is kept constant. can do. Further, since the support ring part 110 is thick and strong, it can be firmly fixed when the clamp 7 is fixed, and since it is used as a bottle position reference, the distance from the camera to the mouth surface. Can be made constant.

  The camera 2 is an area camera provided at the upper part of the transparent bottle 100 to be inspected, and is arranged so that the optical axis thereof is orthogonal to the surface of the opening 104 of the transparent bottle 100. The camera 2 is equipped with a color CCD in which each pixel is provided with a filter such as an RGB filter. The camera 2 can capture an image of the transparent bottle 100 irradiated with the specific light by activating only the pixels provided with a filter that transmits light of the specific frequency.

  The first lighting device 3 is a coaxial surface light source that is provided on the transparent body bottle 100 and is coaxial with the optical axis of the camera, and emits light of a specific frequency. In the present embodiment, the first lighting device 3 is a surface light source that emits red light of approximately 620 to 750 nm, and is disposed between the camera 2 and the transparent bottle 100.

  The second illuminating device 4 is a surface light source that is provided below the transparent bottle 100 and emits light of a specific frequency coaxially with the optical axis of the camera. In the present embodiment, the second illuminating device 4 uses a surface light source that emits blue light of approximately 450 to 490 nm. The second lighting device 4 is provided at a position facing the first lighting device 3 with the transparent bottle 100 interposed therebetween.

  The lights having different frequencies emitted from the respective lighting devices 3 and 4 are discriminated by the camera 2 and images of the transparent bottle 100 irradiated with these lights are respectively taken. That is, the camera 2 can output images (first image and second image) of the two types of transparent body bottles 100 irradiated by the respective lighting devices 3 and 4.

  Since the first image and the second image are images picked up by one camera, they are images that have the same shooting position, angle of view, focal length, etc., and each pixel in the image is a transparent bottle that is a subject. 100 identical positions are imaged. For this reason, when comparing both images in the image analysis described later, it is possible to easily take a correspondence between both images by performing processing based on the coordinates of each pixel.

  In FIG. 2, the optical path irradiated from the 1st illumination device of the external appearance inspection apparatus concerning this embodiment is shown. As shown in FIG. 2, the light emitted from the first lighting device 3 provided on the upper part of the transparent bottle 100 is irradiated so as to be orthogonal to the surface of the opening 101 of the transparent bottle, and the top surface portion 102, Reflected on the surface of the chamfered portion 103 and the screw portion 105.

  Among these, the light that has passed through the optical path L <b> 1 and reached the top surface portion 102 is reflected by the surface of the top surface portion 102 and reaches the camera 2. On the other hand, the light passing through the optical path L2 and reaching the chamfered portion 103 is reflected on the surface of the chamfered portion 103 in a direction different from the optical axis direction of the camera. A part of the light irradiated to the screw part 105 passes through the optical path L3 and is reflected toward the camera 2, but most of the light is not reflected on the surface of the screw part 105 toward the camera (L4). Moreover, the light irradiated to the opening 102 reaches the bottom surface of the transparent body bottle 100 (not shown) without reaching the top surface.

  FIG. 3 shows an example of a first image using the first lighting device. As shown in FIG. 3, the top surface portion 102 is brightly photographed, and the boundary of the inner peripheral edge of the opening 101 is clearly imaged. On the other hand, the chamfered portion 103 is dark and its boundary is not clear. Further, only a part of the screw portion 105 is brightly imaged.

  Moreover, the 1st image shown in FIG. 3 image | photographs the transparent body bottle 100 which provided the notch | scratches 51 and 52 in the top | upper surface part 102 and the chamfering part 103 previously using the knife etc., respectively. As apparent from FIG. 3, the scratches 51 provided on the top surface portion 102 can be visually recognized, but the scratches 52 provided on the chamfered portion 103 can be visually recognized by the depth of the scratch reaching the top surface portion 102. However, since the image has only a very small defect, the accuracy of determination in the image analysis tends to be poor.

  FIG. 4 shows an optical path irradiated from the second illumination device 4 of the appearance inspection apparatus according to the present embodiment. As shown in FIG. 4, the light emitted from the second illumination device 4 provided at the bottom of the transparent bottle 100 is irradiated in a direction orthogonal to the opening 101 surface of the transparent bottle, and the bottom wall 106 and The camera 2 is reached through the gate trace 106a existing on the bottom surface. Further, a part of the light emitted from the second illumination device 4 reaches the side wall of the opening 101 through the side wall 107 of the transparent body bottle 100, and comes out of the bottle from the top surface portion 102 and the chamfered portion 103. The camera 2 is reached.

  The light transmitted through the bottle propagates to the outside from the top surface portion 102 and the chamfered portion 103 through the optical paths L11 and L12. The light emitted from the second illumination device 4 is diffused light and propagates through the side wall 107 while being reflected by the wall of the side wall 107 as indicated by the optical path L13.

  FIG. 5 shows an example of a second image using the second lighting device. As shown in FIG. 4, the top surface portion 102 and the chamfered portion 103 are photographed brightly, and scratches and the like attached to the chamfered portion 103 are captured clearly. On the other hand, the inside of the opening 101 is imaged through the light from the second illumination device 4, the inside of the top surface portion 102 is imaged brightly, and the boundary with the top surface portion 102 and the gate trace 106a are not clear.

  In addition, the second image shown in FIG. 5 is an image of the transparent bottle 100 in which cuts 51 and 52 are provided in the top surface portion 102 and the chamfered portion 103 that are the same as the first image, respectively. As apparent from FIG. 5, both the scratch 51 provided on the top surface portion 102 and the scratch 52 provided on the chamfered portion 103 are easily visible, and the accuracy of determination in image analysis can be increased.

  On the other hand, in the second image, the inside of the opening 101 is imaged through the light from the second illumination device 4, and the inner boundary of the top surface 102 is not clear. For this reason, in the image analysis to be described later, there is a possibility that the specific accuracy of the inspection area is lowered.

  Note that, by holding the support ring portion 110 of the transparent bottle 100 by the clamp 7 as described above, only the opening 101 of the transparent bottle 100 is positioned above the clamp 7. Thereby, as shown in FIG. 5, the clamp 7 shields the outer peripheral area of the opening 101, thereby preventing the light of the second illumination device 4 from being reflected outside the transparent body bottle 100 in the second image. can do. By shielding the outer peripheral area of the opening 101 with the clamp 7, the contrast of the top surface portion 102 and the chamfered portion 103 can be increased, and defect determination by the image analysis unit 6 described later can be performed with high accuracy. .

  Next, image analysis by the image analysis unit will be described. FIG. 6 is a functional block diagram of the image analysis unit of the appearance inspection apparatus. FIG. 7 is a flowchart of defect determination processing performed by the image analysis unit. The image analysis unit 6 as an example of the defect determination unit of the present invention includes a center specifying unit 10, an inspection region specifying unit 11, a differential processing unit 12, and a luminance value determining unit 13, and two types of second images captured by a camera. The inspection area in both images is specified using the first image and the second image, and the presence or absence of a defect is determined based on the amount of change in the luminance value in the inspection area.

  The image analysis unit 6 performs image analysis processing based on the flowchart shown in FIG. The image analysis unit 6 first calculates the center / radius (# 1). In the calculation of the center / radius, first, as shown in FIG. 8, the inner edge circle 20 is specified by referring to the luminance value of each pixel of the top surface area 102a corresponding to the top surface portion 102 using the first image. . Next, among the plurality of virtual lines 23 extending radially between the predetermined virtual circles 21 and 22, the lengths of the sections divided by the inner virtual circle 22 and the inner edge circle 20 are equal. One image (second image) is moved, and the subject center position of the first image (second image) is specified. This processing is governed by the center specifying unit 10.

  When the subject center position of the first image (second image) is specified, the outer edge circle 24 and the intermediate circle 25 are created based on the known thickness information of the opening of the transparent body bottle 100. The outer edge circle 24 is specified by creating a circle whose diameter is increased outward from the center position of the inner edge circle 20 based on the thickness of the opening. The intermediate circle 25 is specified by creating a circle specified concentrically with the inner edge circle 20 in the middle between the inner edge circle 20 and the outer edge circle 24. These processes are performed by the inspection area specifying unit 11.

  Next, the inspection area specifying unit 11 specifies an area surrounded by the inner edge circle 20 and the outer edge circle 24 as an inspection area. The inspection area includes a chamfered area 103a corresponding to the chamfered portion 103 in addition to the top surface area 102a, and the top of the transparent bottle 100 is measured by measuring the luminance of the image (second image) in the inspection area. Defects in the surface portion 102 and the chamfered portion 103 are determined.

  The differential processing unit 12 performs differential processing on the images in the circumferential direction along the circumferences of the inner edge circle 20, the outer edge circle 24, and the intermediate circle 25 created as described above, and three differential images having a circular shape. Create The differential process is a process for obtaining a difference between luminance values of pixels existing adjacent to each other along the circumference of the inner edge circle 20, the outer edge circle 24, and the intermediate circle 25. The pixel to be compared is, for example, a pixel existing at a position having a predetermined distance from the reference pixel, for example, a pixel existing at a position away from the reference pixel by a predetermined angle (for example, 5 degrees). Can do. By specifying the comparison pixels in this way, it is possible to easily find defects such as gradual scratches. The position of the pixel to be compared with the reference pixel may be appropriately determined according to the size of the image, the number of pixels, and the like.

  In the present embodiment, the differentiation process uses a first image in which the top surface portion 102 is clearly imaged for the intermediate circle 25. On the other hand, the inner edge of the top surface portion 102 and the chamfered portion 103 are created using a second image that is clearly imaged. By the differentiation process, three differential images corresponding to the inner edge circle 20, the outer edge circle 24, and the intermediate circle 25 including information on the difference values for each reference pixel are created.

  The luminance value determining unit 13 binarizes the differential image created by the differential processing unit 12 and compares pixel values. Then, a portion showing a high value exceeding a predetermined threshold is determined as a defect. The predetermined threshold value may be a different value for each image based on the inner edge circle 20, the outer edge circle 24, and the intermediate circle 25.

  According to this embodiment, an image peculiar to the light of each optical path can be captured by identifying and capturing the light that has reached the camera through different optical paths using two illumination devices. For this reason, the top surface portion 102 and the chamfered portion 103 of the transparent body bottle 100 can be clearly photographed, and defect determination can be performed with high accuracy based on the image.

  That is, the first image by the first lighting device is an image with a clear top surface outline, but the chamfered portion at the periphery of the top surface portion is not clearly imaged. On the other hand, since the second image is picked up from the direction in which the area camera is directly irradiated with light, the boundary of the top surface portion, in particular, the inner boundary of the top surface portion is not clearly picked up, but both the top surface portion and the chamfered portion are captured. As a result, the defect inspection can be performed with high accuracy.

  Also, since two types of images can be taken simultaneously with one camera, the inspection time can be shortened.

  In addition, this invention is not limited to said each embodiment, It can implement in another various aspect. For example, in the above embodiment, a camera equipped with a color CCD is used and light of each wavelength is identified by a camera driver. For example, a camera using a monochrome CCD is used and the optical axis of the camera is used. You may arrange | position the color filter apparatus comprised so that transmission wavelength could be switched above. In this case, imaging based on each wavelength is impossible at the same time. However, since all the pixels of the CCD can be used for imaging, a relatively high-definition image can be obtained.

  The present invention can be used for quality control of a plastic bottle in a plastic bottle manufacturing industry, a beverage manufacturing industry using a plastic bottle, and the like.

DESCRIPTION OF SYMBOLS 1 Appearance inspection apparatus 2 Camera 3 1st illuminating device 4 2nd illuminating device 5 Control part 6 Image analysis part 7 Clamp 10 Center specific part 11 Inspection area | region specific part 12 Differentiation processing part 13 Luminance value determination part 20 Inner edge circle 21,22 Virtual circle 23 Virtual line 24 Outer edge circle 25 Intermediate circle 100 Transparent body bottle 101 Opening portion 102 Top surface portion 103 Chamfered portion 104 Screw portion 106 Bottom wall 106a Gate mark 107 Side wall 110 Support ring portion

Claims (7)

A transparent bottle having an opening, capable of irradiating light having a first frequency from a first optical path intersecting the opening, and a first light source provided on the opening ,
A second light source unit capable of irradiating light having a second frequency from a second optical path intersecting the opening and in a direction opposite to the first optical path;
An area camera that is arranged so that a photographing optical axis is orthogonal to the opening, and that can detect and radiate light emitted from the first light source unit and the second light source unit;
After specifying the inspection area based on the first image by the light from the first light source unit imaged by the area camera, based on the second image by the light from the first image and the second light source unit. And a defect determining unit that determines whether or not there is a defect in the opening.   2. The transparent bottle appearance inspection apparatus according to claim 1, wherein the second optical path passes through the wall of the transparent bottle and reaches the area camera from the top surface of the opening. The defect determination unit identifies an inner edge circle along the inner peripheral edge of the opening using the first image, and after performing centering with the inner edge circle, the outer edge from the inner edge circle and the center position. Identify the circle and middle circle,
The specified inner edge circle and the outer edge circle are based on the luminance values of the pixels existing on the second image circle, and the intermediate circle is determined based on the luminance values of the pixels existing on the first image circle. The transparent bottle appearance inspection apparatus according to claim 1, wherein defect determination is performed. Furthermore, it has a light-shielding part which shields the light from the 2nd light source part which is provided under the transparent body bottle opening part, and exists in the outer peripheral area | region of the said opening part, The any one of Claim 1 to 3 characterized by the above-mentioned. The transparent bottle appearance inspection device according to claim 1. For a transparent bottle having an opening, light having a first frequency is passed through the opening from above the opening, and light having a second frequency is sent from the bottom of the transparent bottle to the first side. Irradiate in a second optical path that is opposite to the optical path and intersects the opening,
The area camera arranged so that the photographing optical axis is orthogonal to the opening determines the light emitted from the first light source unit and the second light source unit, and the first by the light from the first light source unit. Taking an image and a second image by light from the second light source unit,
A method for inspecting the appearance of a transparent bottle, wherein after the inspection area is specified based on the first image, defect determination processing is performed based on the first image and the second image. The defect determination process uses the first image to identify an inner edge circle along the inner peripheral edge of the opening, and after performing centering with the inner edge circle, the outer edge from the inner edge circle and the center position. 6. The transparent bottle appearance inspection method according to claim 5 , wherein a circle is specified, and an area surrounded by the inner edge circle and the outer edge circle is used as an inspection area. The defect determination process specifies an intermediate circle at an intermediate position between the inner edge circle and the outer edge circle, and uses the first image for the intermediate circle and the second image for the inner edge circle and the outer edge circle, The transparent bottle appearance inspection method according to claim 6 , wherein the defect determination is performed based on a luminance value of each pixel present on a circle.