JP5726628B2 - 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 bottom surface portion of a transparent bottle such as a PET bottle.

  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 Application Laid-Open No. 2003-202295), a ring-shaped light source disposed facing the bottom of a plastic bottle, and disposed between the bottom of the plastic bottle and the ring-shaped light source, Disclosed is an inspection apparatus that includes a diffuser plate having an opening in the center and a diffuse reflector that is disposed farthest from the bottom of the PET bottle and that sandwiches the ring-shaped light source with the diffuser plate. ing.

  In this apparatus, the light emitted from the ring-shaped light source passes through the diffusion plate and enters the bottom of the PET bottle, and directly enters the bottom of the PET bottle through the opening of the diffusion plate. A second optical path and a third optical path which is reflected by the diffuser plate after being reflected by the diffuser plate, pass through the opening of the diffuser plate, and enter the bottom of the PET bottle are taken. Then, by photographing with a combination of direct illumination light and transmitted illumination light, it is possible to irradiate the uneven portion, and the shade of the uneven portion disappears, and an image having the same brightness as the other portions can be obtained. For this reason, if there are dirt and foreign matter in the uneven part, this part becomes a dark image, and these dirt and foreign matter can be detected.

JP 2003-202295 A

  However, the inspection apparatus disclosed in Patent Document 1 is intended to make it easier to visually recognize defects by erasing the unevenness of the bottom surface of the PET bottle by irradiating light from multiple directions. There is a problem that it becomes difficult to align the center of the bottle when the shade of the irregularities on the bottom surface disappears. That is, the PET bottle is unevenly provided radially from the center, and it is necessary to align the rotation angle with respect to the center axis. There was a problem that the contour of the bottom disappeared by erasing the shade of the irregularities on the bottom of the PET bottle, which made positioning difficult.

  If the alignment is not performed with high accuracy, the inspection area cannot be specified. As a result, it is impossible to determine the defect with high accuracy, and it is impossible to inspect the gate trace existing at the bottom of the bottle.

  Furthermore, since the apparatus of Patent Document 1 uses an annular light source, the shadow of each radiation direction viewed from the center of the bottle can be similarly eliminated by aligning the center of the bottle with the center of the light source. When the center of the bottle and the center of the light source do not coincide with each other, shading corresponding to the position is generated in the shadow of the bottom. For this reason, the apparatus of Patent Document 1 has a problem that only a bottle having a circular cross section can be inspected.

  Therefore, the technical problem to be solved by the present invention can be applied to various types of bottles, and can accurately determine the presence or absence of defects present on the bottom surface of the bottle. And providing an appearance inspection method.

  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,
A first light source unit capable of irradiating diffused light having a first frequency toward the bottom outer surface of a transparent bottle having an opening;
A second light source unit capable of irradiating parallel light of a second frequency toward the bottom outer surface of the transparent body bottle;
An area camera that is adjacent to the opening of the transparent bottle, discriminates the light emitted from the first light source unit and the second light source unit, and images the bottom inner surface through the opening;
Based on the first image captured by the area camera and the second image generated by the light from the first light source unit and the second image generated by the light from the second light source unit, it matches the standard image stored in advance using the second image. A defect determination unit that performs rotation angle correction of the first image and the second image so as to compare the first image with the standard image, and determines whether there is a defect on the bottom surface of the transparent body bottle; A visual inspection apparatus for transparent bottles is provided.

  According to a second aspect of the present invention, in the transparent bottle according to the first aspect, the first light source part and the second light source part are constituted by a transparent light emitting panel and are provided coaxially with each other. An appearance inspection apparatus is provided.

  According to a third aspect of the present invention, the second light source unit includes a parallel light filter provided on a light emitting surface of a light emitting panel, and is provided below the first light source unit. A transparent bottle appearance inspection apparatus according to two aspects is provided.

According to a fourth aspect of the present invention,
Irradiating diffused light of the first frequency and parallel light of the second frequency toward the bottom outer surface of the transparent bottle having the opening,
An area camera that is arranged adjacent to the opening of the transparent body bottle and images the bottom inner surface through the opening, discriminates the light emitted from the first light source unit and the second light source unit, and Capturing a first image by light from the light source unit and a second image by light from the second light source unit;
By performing rotation angle correction of the first image and the second image so as to coincide with the standard image stored in advance using the second image, and comparing the first image with the standard image, Provided is a method for inspecting the appearance of a transparent bottle, characterized by determining the presence or absence of a defect.

  According to the present invention, since the bottom of the transparent bottle is irradiated with two lights of diffused light and parallel light, it is possible to obtain two images with different shadow reflections on the bottom of the bottle. That is, the first image captured by the first light source unit that is diffused light can be an image in which the shade of the unevenness is thinned because light from many directions is irradiated on the unevenness of the bottom. On the other hand, the second image taken by the second light source unit, which is parallel light, is irradiated with light from one direction with respect to the unevenness of the bottom, so that the shadow of the unevenness and the outline of the bottom are clearly reflected. It can be. Therefore, the defect inspection of the bottom surface of the transparent body bottle can be performed with high accuracy by using these two characteristic images.

  In addition, since an annular light source is not used as the light source, it is possible to clearly photograph even a transparent bottle having a bottom shape other than a circle, and it can be applied to various types of bottles.

  In the above configuration, by configuring the first and second light source units with a transparent light-emitting panel, the two light source units can be arranged in an overlapping manner so that the optical axes can be made the same and the device configuration can be made compact. In addition, the photographing conditions by the two light source units can be made the same.

  In order to make the light emitted from the second light source part parallel light, it is preferable to use a parallel light filter. The parallel light filter is, for example, a filter having a hollow honeycomb structure. Of the light emitted from the light emitting surface of the surface light source as diffused light, only the light in the direction orthogonal to the light emitting surface is allowed to pass through. The thing converted into can be illustrated.

It is a schematic diagram which shows schematic structure of the plastic bottle which is a to-be-inspected object of the external appearance inspection apparatus concerning this embodiment. It is a partial expansion perspective view which shows the structure of the bottom part of the PET bottle of FIG. 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 figure which shows the optical path irradiated from the 1st illumination device of the external appearance inspection apparatus of FIG. It is a figure which shows the example of the 1st image using the 1st illuminating device. It is a figure which shows the optical path irradiated from the 2nd illumination device 4 of the external appearance inspection apparatus of FIG. It is a figure which shows the example of the 2nd image using the 2nd illuminating device. It is a functional block diagram of the image analysis part of an appearance inspection apparatus. It is a flowchart of the defect determination process which an image analysis part performs. It is explanatory drawing of the center specific process which a center specific part performs. It is explanatory drawing of the angle adjustment process which a rotation angle adjustment part performs.

  A transparent bottle appearance inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  The transparent bottle appearance inspection apparatus 1 according to the present embodiment uses an image captured by the camera 2 to determine whether or not there is a scratch, dirt, or the like on the top surface of the bottom surface of a plastic bottle 100 as an example of a transparent bottle. And pass / fail judgment. The transparent bottle that can be inspected in the appearance inspection apparatus 1 according to the present embodiment may be configured such that the bottom surface is configured to be transparent and the other part is configured to be opaque. For example, it is possible to inspect a plastic bottle having a white opaque area near the opening.

  FIG. 1 is a schematic diagram illustrating a schematic configuration of a plastic bottle that is an object to be inspected according to the present embodiment, and FIG. 2 is a partially enlarged perspective view illustrating a configuration of a bottom portion of the plastic bottle in FIG. As shown in FIG. 1, the plastic bottle 100 has a body 101, a bottom 102, and an opening 103. A support ring portion 104 is provided below the opening 103. The support ring portion 104 is a reference surface that serves as a position reference for molding a plastic bottle, and the distance H from the support ring 104 to the top surface 103a of the opening 103 is known.

  As shown in FIG. 2, the bottom 102 of the plastic bottle has a gate mark 105 which is a trace of a plastic injection port at the time of molding the plastic bottle and a rib shape extending radially in order to reinforce the strength of the bottom of the plastic bottle. The uneven portion 106 is provided.

  Note that the PET bottle that can be inspected by the appearance inspection apparatus of the present embodiment is not limited to the one having the circular body 101 but may be a rectangle or an ellipse. However, it is necessary to have a shape that enables imaging of the bottom 102 that is the inspection site through the opening 103. As will be described later, non-defective product data as an example of standard data of the present invention is created for the contour of the PET bottle 100, and the non-defective product data is stored in the appearance inspection apparatus.

  FIG. 3 is a schematic diagram showing the configuration of the appearance inspection apparatus according to the embodiment of the present invention. In the appearance inspection apparatus 1 according to the present embodiment, two illumination devices 3 and 4 as examples of the first light source unit and the second light source unit of the present invention are provided below the PET bottle 100. The lighting devices 3 and 4 illuminate the bottom 102 of the plastic bottle 100 from below the plastic bottle 100.

  In addition, the appearance inspection apparatus 1 is provided with a camera 2 that captures an image of the PET bottle 100 that is an inspection object using light emitted from the first illumination apparatus 3 and the second illumination apparatus 4, respectively. The camera 2 captures transmitted light that has passed through the bottom 102 of the plastic bottle 100 from the opening 103 side of the plastic bottle 100.

  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.

  In the appearance inspection apparatus 1 according to the present embodiment, the clamp 7 that supports the support ring portion 104 is used for transporting and positioning the PET bottle 100. The clamp 7 is configured to be openable and closable from side to side, and a groove for receiving the support ring portion 104 is provided on the opposing surface. The clamp 7 in the opened state is arranged in the vicinity of the support ring 104 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 portion 104 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 support ring portion 104 can be used from the camera 2 to the mouth surface. The distance can be 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 surface light source that is provided below the plastic bottle 100 and is coaxial with the optical axis of the camera and emits light of a specific frequency. The dimension of the light emitting surface is configured to be larger than the bottom surface of the PET bottle 100. In the present embodiment, the first lighting device 3 is a surface light source that emits blue light of approximately 450 to 490 nm, and a transparent light emitting panel is used. The first lighting device 3 emits diffused light from the entire light emitting surface.

  The second illuminating device 4 is a surface light source that is provided in a stacked state under the first illuminating device 3 and emits light of a specific frequency coaxially with the optical axis of the first illuminating device 3. In the present embodiment, the second lighting device 4 uses a surface light source that emits red light of approximately 620 to 750 nm.

  A parallel light filter 8 is provided on the light emitting surface of the second illumination device 4. The parallel light filter 8 is, for example, a sheet-like filter including a hollow honeycomb structure, and can transmit only light emitted in a direction along the hollow direction of the honeycomb structure. The light from the illumination device 4 can be parallel light. By adopting this configuration, parallel light can be obtained with a compact configuration.

  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.

  FIG. 4 shows an optical path irradiated from the first illumination device of the appearance inspection apparatus according to the present embodiment. As shown in FIG. 4, the first lighting device 3 is a light emitting device that irradiates diffuse light having the same illuminance in all directions from a certain arbitrary light emitting surface 3 a. That is, an arbitrary point 102a on the bottom surface 102 of the PET bottle 100 irradiated by the first lighting device 3 is irradiated with light through the optical paths (L1 to L4) in all directions, and passes through the bottom surface 102 to be opened. The light is incident on a camera provided close to 103. For this reason, the shadow 106a of the concavo-convex portion 106 is thinly imaged on the bottom surface irradiated by the first illumination device 3.

  FIG. 5 shows an example of a first image using the first lighting device. FIGS. 5A and 5B each show a first image using a plastic bottle as another sample. As shown in FIG. 5, the shadow of the bottom portion 102 is imaged thinly. On the other hand, since the shading of the concavo-convex part is not clear, the boundary and outline of the concavo-convex part are not clear, and the difference in shading does not appear remarkably.

  FIG. 6 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. 6, a transparent light filter 8 is provided on the light emitting surface of the second light emitting device 4, and parallel light is emitted from an arbitrary light emitting point 4 a of the filter 8 in a direction orthogonal to the light emitting surface. Then, the PET bottle 100 is irradiated through the first lighting device 3. That is, an arbitrary point 102a on the bottom surface 102 of the plastic bottle 100 irradiated by the second illumination device 4 is irradiated only with light in a direction perpendicular to the light emitting surface as shown by the optical path L11 and passes through the bottom surface 102. Then, the light enters the camera provided close to the opening 103. For this reason, the shadow of the concavo-convex portion 106 is clearly imaged on the bottom surface irradiated by the first lighting device 3.

  FIG. 7 shows an example of a second image using the second lighting device. FIGS. 7A and 7B each show a first image using a plastic bottle as another sample. As shown in FIG. 7, the shadow of the bottom portion 102 is clearly imaged, and the difference in shading of the uneven portion appears remarkably.

  The images shown in FIGS. 5 and 7 are images of PET bottles in which cuts 51 and 52 are respectively provided in the bottom 102 using a knife or the like in advance. As is clear from comparison between FIG. 5 and FIG. 7, in the second image, the shading of the concavo-convex part and the shade difference between the flaws 51 and 52 are not remarkable, and the differentiation between the flaw and the concavo-convex shadow by the image analysis part described later is provided. May be difficult. On the other hand, in the first image shown in FIG. 5, scratches are clearly captured as compared with the uneven shadow, and it is relatively easy to differentiate between them, and it is possible to increase the accuracy of determination in image analysis.

  In addition, by holding the support ring part 104 of the transparent body bottle 100 by the clamp 7 as described above, only the opening 101 of the transparent body bottle 100 is positioned above the clamp 7. Thereby, as shown in FIG. 2, the clamp 7 can prevent the light of the second illumination device 4 from being reflected outside the transparent bottle 100 by shielding the outer peripheral region of the opening 101. 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. 8 is a functional block diagram of the image analysis unit of the appearance inspection apparatus. FIG. 9 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 angle adjusting unit 11, an inspection region specifying unit 12, and a luminance value determining unit 13, and further, a standard that is non-defective imaging data. Data 14 is provided. The image analysis unit 6 identifies the inspection area in both images using the two types of first image and second image captured by the camera 2, and determines the defect based on the amount of change in the luminance value in the inspection area. Determine presence or absence.

  The image analysis unit 6 performs image analysis processing according to the processing procedure shown in the flowchart shown in FIG. The center specifying unit 10 of the image analysis unit 6 first calculates the center of the bottom 102 (# 1). The center specifying unit 10 creates a virtual contour line 20 based on standard data 14 stored in advance. As shown in FIG. 10, the virtual contour line 20 is configured to be similar to the contour of the bottom portion 102 of the standard data 14. In FIG. 10, the virtual outline 20 smaller than the outline of the bottom 102 is used. In addition, since the virtual outline 20 is an outline of the bottom part of the PET bottle 100, it is not limited to a circle, and may be a shape such as a rectangle or an ellipse.

  Next, as shown in FIG. 10, the center specifying unit 10 specifies the outer contour circle 21 indicating the outer boundary of the bottom region 102a corresponding to the bottom 102 using the second image with reference to the luminance value of each pixel. To do. Furthermore, a plurality of virtual lines 22 extending radially from the center of the virtual contour line 20 are created, and the lengths of the virtual lines 22 divided by the virtual contour line 20 and the outer contour circle 21 are made as uniform as possible. Two images are moved, and the subject center position of the second image is specified.

  After specifying the subject center position of the second image, the angle adjustment unit 11 rotationally corrects the second image around the subject center position so that the shadow of the uneven portion 106a is included in the inspection exclusion area of the standard data. (# 2). The inspection exclusion area 23 is determined in advance based on standard data, and the peripheral area of the shaded portion of the uneven portion 106 is set. The angle adjusting unit 11 rotates the second image around the subject center position specified by the center specifying unit 10, and sets the second rotation angle so that the luminance value of the pixel existing in the examination exclusion area 23 is minimized. Image conversion is performed on the image and the first image.

  The inspection area specifying unit 12 specifies an area excluding the inspection exclusion area 23 among the areas surrounded by the outer contour circle 21 as an inspection area (# 3).

  The brightness value determination unit 13 compares the brightness values of the pixels using the first image for the inspection region specified by the inspection region specification unit 12 (# 4). Then, a portion showing a high value exceeding a predetermined threshold is determined as a defect.

  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. Since the captured image has a different shadow shooting state, in the defect determination of the bottom portion 102 of the transparent body bottle 100, the defect determination can be performed with high accuracy by properly using the two images.

  That is, the first image by the first lighting device is an image in which the shadows of the unevenness are photographed thinly, but the outline and the like are unclear. On the other hand, the second image has a sharp image of unevenness and has a large error in comparison of luminance values used for defect determination, but has a clear outline, which is suitable for specifying an inspection region of an image. It is an image. According to the present embodiment, by using these two types of images, it is possible to perform highly accurate processing in both inspection area specification and defect determination.

  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 second lighting device 4, the configuration for obtaining parallel light is not limited to the above embodiment. As an example, parallel light can be obtained by using a point light source as the second illumination device and disposing the convex lens at a position away from the point light source by the focal length of the lens.

  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, it is impossible to capture a plurality of images at the same time, but since it is possible to capture using all the pixels of the CCD, 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 8 Parallel light filter 10 Center specific part 11 Angle adjustment part 12 Inspection area specific part 13 Brightness value determination part 20 Virtual contour Line 21 Outer contour circle 23 Virtual line 24 Inspection exclusion area 100 PET bottle 101 Body 102 Opening portion 103 Chamfering portion 104 Support ring portion 105 Gate mark 106 Uneven portion

Claims (4)

A first light source unit capable of irradiating diffused light having a first frequency toward the bottom outer surface of a transparent bottle having an opening;
A second light source unit capable of irradiating parallel light of a second frequency toward the bottom outer surface of the transparent body bottle;
An area camera that is adjacent to the opening of the transparent bottle, discriminates the light emitted from the first light source unit and the second light source unit, and images the bottom inner surface through the opening;
Based on the first image captured by the area camera and the second image generated by the light from the first light source unit and the second image generated by the light from the second light source unit, it matches the standard image stored in advance using the second image. A defect determination unit that performs rotation angle correction of the first image and the second image so as to compare the first image with the standard image, and determines whether there is a defect on the bottom surface of the transparent body bottle; A visual inspection apparatus for a transparent bottle, comprising:   2. The transparent bottle appearance inspection apparatus according to claim 1, wherein the first light source unit and the second light source unit are configured by a transparent light-emitting panel and are provided coaxially with each other.   The appearance of the transparent bottle according to claim 2, wherein the second light source unit includes a parallel light filter provided on a light emitting surface of a light emitting panel, and is provided below the first light source unit. Inspection device. Irradiating diffused light of the first frequency and parallel light of the second frequency toward the bottom outer surface of the transparent bottle having the opening,
An area camera that is arranged adjacent to the opening of the transparent body bottle and images the bottom inner surface through the opening, discriminates the light emitted from the first light source unit and the second light source unit, and Capturing a first image by light from the light source unit and a second image by light from the second light source unit;
By performing rotation angle correction of the first image and the second image so as to coincide with the standard image stored in advance using the second image, and comparing the first image with the standard image, A method for inspecting the appearance of a transparent bottle, wherein the presence or absence of a defect is determined.