Container mouth shape inspection apparatus

Abstract

To highly accurately determine the quality of a mouth part of a container from an optical image.SOLUTION: The device for inspecting the shape of the mouth portion of the vessel includes an image acquiring means 20A for acquiring an image of the mouth portion of the vessel, a contour extracting means 20B for extracting a contour of the mouth portion from the acquired image, an ellipse calculating means 20C for calculating parameters of an ellipse approximating the extracted contour, a mouth region detecting means 20D for detecting a region surrounded by the contour and a region surrounded by the ellipse, a deviation calculating means 20E for calculating values corresponding to deviations of the contour from the ellipse, and a determining means 20F for determining whether the shape of the mouth portion is good or bad.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an inspection device for inspecting the shape of the mouth of a container. [Background technology]

[0002] Inspection devices that optically inspect the inner diameter and shape of the mouth of containers such as glass bottles and PET bottles are known (see Patent Documents 1 and 2). These inspection devices capture planar images of the mouth using illumination light from above the mouth, and determine any abnormalities in the mouth shape from these images. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4286569 [Patent Document 2] Patent No. 7028467 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inspection methods described in Patent Documents 1 and 2 have the problem that they cannot accurately determine whether a container's neck is good or bad if the container is tilted during transport or if the neck is distorted by the gripping force of the gripper. Specifically, tilting or temporary deformation of the container can cause the contour of the neck, which should be circular, to appear elliptical, raising the risk of misjudging a non-defective container as defective, or conversely, overlooking a defective container. This has resulted in issues such as reduced production efficiency and increased quality control costs.

[0005] An object of the present invention is to determine with high accuracy whether the mouth of a container is good or bad from an optical image. [Means for solving the problem]

[0006] The first invention of the present invention is a container mouth shape inspection device characterized by comprising an image acquisition means for acquiring an image of the mouth of the container, a contour extraction means for extracting the contour of the mouth from the acquired image, an ellipse calculation means for calculating parameters of an ellipse that approximates the contour based on coordinate data of multiple points that make up the extracted contour, a mouth area detection means for detecting the area surrounded by the contour and the area surrounded by the ellipse, a deviation calculation means for calculating a value corresponding to the deviation of the contour from the ellipse based on the area surrounded by the contour and the area surrounded by the ellipse, and a judgment means for comparing the calculated value with a predetermined threshold value to judge whether the mouth shape is good or bad.

[0007] The second invention of the present invention is a container mouth shape inspection device characterized in that the ellipse calculation means calculates the parameters of the ellipse using the least squares method for the coordinate data of multiple points that constitute the extracted contour. [Effects of the Invention]

[0008] According to the present invention, the quality of a container's neck can be determined with high accuracy from an optical image. Specifically, an ellipse that approximates the contour is calculated and used as a reference for the determination, enabling accurate determination without being affected by tilting of the container during transport or temporary deformation caused by the gripper. This significantly reduces the false determinations that were a problem in conventional technology, and enables accurate distinction between actual manufacturing defects and temporary deformation. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic side view showing the configuration of a mouth shape inspection device according to an embodiment of the present invention; [Figure 2] 10 is a side view showing a state in which the central axis of a container gripped by the gripper is tilted outward from the vertical axis. FIG. [Figure 3] FIG. 10 is a block diagram showing a quality determination process executed in a control device connected to the camera. [Figure 4] FIG. 10 is a diagram illustrating the content of a pass / fail determination process. [Figure 5] 10A to 10C are diagrams schematically showing the procedures of the contour extraction process, the ellipse calculation process, the mouth region detection process, and the deviation calculation process when the image is determined to be defective. [Figure 6] 10A to 10C are diagrams schematically showing the procedures of contour extraction processing, ellipse calculation processing, mouth region detection processing, and deviation calculation processing when a product is determined to be non-defective. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic side view showing the configuration of a mouth shape inspection device according to one embodiment of the present invention.

[0011] The mouth shape inspection device 10 of this embodiment is a device that inspects the planar shape of the mouth Vm of a container V based on image information. The container V is, for example, a resin bottle (e.g., a PET bottle) with a cylindrical mouth Vm and a flange Vf at the neck. The container V is conveyed while being gripped, for example, by the neck below the flange Vf by a gripper 14 arranged along the outer periphery of a rotating body 12A of a conveying wheel 12.

[0012] The mouth shape inspection device 10 is placed at a predetermined position on the container transport path taken by the transport wheel 12, and is equipped with a surface light 16 that is positioned facing upward below the transported container V, a camera 18 that faces the surface light 16 and is positioned facing downward along a vertical line Lp above the container V, and a control device 20 that controls the photography by the camera 18 and processes the images taken by the camera 18 to determine whether the mouth shape is good or bad.

[0013] In this embodiment, the container V is transported by gripping the neck portion below the flange portion Vf with the gripper 14 of the rotating body 12A. For example, centrifugal force causes the body of the container V to swing radially outward from the rotating body 12A around the gripper 14, tilting the central axis Lc of the container V outward from the vertical axis Lp, as shown in FIG. 2 . In this state, the horizontal cross-sectional shape of the mouth Vm of the container V is deformed from a circular shape when upright to an elliptical shape. Furthermore, if the container V is soft, the gripping force of the gripper 14 may deform the horizontal cross-sectional shape of the mouth Vm of the container V into an elliptical shape. In this state, when the mouth Vm of the container V is photographed from directly above along the vertical axis Lp, the contour image of the mouth Vm appears elliptical. Therefore, the mouth shape inspection device 10 of this embodiment detects deformations, such as chipping and distortion, of the cylindrical mouth Vm based on the elliptical shape and determines whether it is good or bad.

[0014] FIG. 3 is a block diagram showing the procedure of the quality determination process executed by the control device 20 connected to the camera 18, and FIG. 4 is a diagram for explaining the content of the quality determination process.

[0015] An image of the mouth Vm of the container V photographed from directly above is sent to the control device 20, and the image data is stored in image acquisition means 20A, which is composed of an image memory or the like (image acquisition process). The image data stored in the image acquisition means 20A is processed by contour extraction means 20B using conventionally known techniques, such as grayscale conversion, smoothing, noise removal, and binarization, to extract a contour from the image of the mouth Vm photographed from directly above (contour extraction process). The contour P of the mouth Vm extracted (detected) by the contour extraction means 20B is stored as contour coordinate data consisting of a point cloud in pixel units, as shown in FIG. 4(a), for example.

[0016] Next, the ellipse calculation means 20C calculates an ellipse E fitted based on the contour P of the mouth Vm consisting of the point cloud, as shown in Fig. 4(b) (ellipse calculation process). In the ellipse calculation process, parameters such as the center coordinates, the lengths of the major and minor axes, and the rotation angle of the ellipse E approximating the point cloud are found using a method such as the least squares method.

[0017] Furthermore, in the mouth area detection means 20D, an area A surrounded by the outline P of the mouth Vm and an area B surrounded by the ellipse E are identified as point clouds in pixel units (mouth area detection process). Furthermore, in the deviation calculation means 20E, an XOR (exclusive OR) is calculated for the point clouds of area A and area B, and the area S (e.g., the number of pixels) of area D is found as a value corresponding to the deviation of the outline P from the ellipse E (deviation calculation process).

[0018] Finally, the judgment means 20F compares the calculated deviation value (area S of region D) with a preset threshold value Th to judge the quality of the mouth Vm of the container V. For example, if S>Th, the shape of the mouth Vm is judged to be defective, and if S≦Th, the shape of the mouth Vm is judged to be good (judgment process).

[0019] 5 and 6 are diagrams schematically showing the procedures for the contour extraction process, ellipse calculation process, mouth area detection process, and deviation calculation process, with Fig. 5 corresponding to a case where the product is determined to be defective by the determination means 20F, and Fig. 6 corresponding to a case where the product is determined to be non-defective. Figs. 5(a) and 6(a) show the state where contour P is detected by the contour extraction process, Figs. 5(b) and 6(b) show the state where ellipse E is calculated based on contour P by the ellipse calculation process, and Figs. 5(c) and 6(c) show the state where area D representing the deviation of contour P from ellipse E is determined based on the area surrounded by contour P and the area surrounded by ellipse E by the mouth area detection process and deviation calculation process.

[0020] As described above, according to this embodiment, the quality of the mouth shape is determined based on an ellipse, so that the quality of the mouth of the container can be determined with high accuracy from an optical image without being affected by the tilt of the container or distortion of the mouth. [Explanation of symbols]

[0021] 10 Mouth shape inspection device 18 Camera 20 Control device 20A Image Acquisition Means 20B Contour Extraction Means 20C Ellipse Calculation Method 20D Mouth area detection means 20E Deviation calculation method 20F Judgment means

Claims

1. an image acquisition means for acquiring an image of the mouth of the container; a contour extraction means for extracting a contour of the mouth from the acquired image; an ellipse calculation means for calculating parameters of an ellipse that approximates the contour based on coordinate data of a plurality of points that constitute the extracted contour; a mouth area detection means for detecting an area surrounded by the outline and an area surrounded by the ellipse; a deviation calculation means for calculating a value corresponding to a deviation of the contour from the ellipse based on an area surrounded by the contour and an area surrounded by the ellipse; a determining means for comparing the calculated value with a preset threshold value to determine whether the mouth shape is good or bad; A container mouth shape inspection device comprising:

2. 2. The container mouth shape inspection device according to claim 1, wherein the ellipse calculation means calculates the parameters of the ellipse using the least squares method for the coordinate data of the plurality of points that make up the extracted contour.

Images