JP2921449B2 - Golf ball appearance inspection method and appearance inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to detecting a two-dimensional image of a golf ball by photographing the golf ball with a camera, and detecting an appearance defect such as a scratch, partial deformation or dirt on the golf ball surface from the two-dimensional image. The present invention relates to a golf ball appearance inspection method and an appearance inspection apparatus.

[0002]

2. Description of the Related Art When a golf ball is manufactured, defects such as scratches and partial deformation may occur on the surface of the golf ball, and such defects are small. However, the design of the dimples formed on the ball surface may be confused, which may affect flying performance and the like. In addition, various stains may occur on the surface of the golf ball. In this case, although the performance of the golf ball is not affected, the commercial value is greatly reduced. For this reason, usually, before shipping the manufactured golf ball, an appearance inspection for removing the golf ball having such a defect is performed.

[0003] Conventionally, it has been desired to automate the appearance inspection for detecting defects such as scratches and partial deformation of the golf ball surface and dirt using an inspection device. It is difficult to automate the appearance inspection of a ball, and at present the inspection is performed by a visual inspection by an operator.

Conventionally, as an automatic appearance inspection method instead of a visual inspection, a surface of an object to be inspected is illuminated, the surface is photographed by an optical device such as a camera, and an image processing device or the like is used from the obtained image. In general, a method of determining the quality of a product is generally performed in the appearance inspection of various products. in this case,
When inspecting for dirt and scratches on a flat surface or curved surface without patterns, etc., these defective portions will appear clearly due to the change in color of the defective portion and the difference in reflected light due to the scratch if only illumination is applied. These defective portions can be easily determined by the processing, and when the inspection target has a pattern or a regularly provided hole or concave portion on a plane,
By storing the pattern in advance and erasing the common part by superimposing it on the obtained image, only the defective part remains without being erased, so that the presence or absence of a defect can be determined. It is.

However, in the case of a golf ball,
Since a large number of circular dimples (concave portions) are provided on the spherical surface, it is difficult to reliably detect a defect by the above-described method of storing an image in advance and overlapping the obtained image. That is, when photographing the surface of a ball on which a large number of circular dimples are formed on a spherical surface, the dimples on the ball surface appear as a large number of ellipses whose ratio between the major axis and the minor axis is irregular,
An image in which these ellipses are lined up is obtained, but unlike a flat plate, the balls have a degree of freedom of rotation, so even if only one dimple is used, the circle becomes an ellipse only when the ball is shifted by a small angle. Therefore, it is extremely difficult to completely match the dimple pattern stored in advance with the obtained image.

[0006] For this reason, as described above, the visual inspection of golf balls is currently performed by an operator, but the visual inspection imposes a great burden on the operator. At the same time, it is very difficult to determine a slight deformation or a scratch on the surface of a golf ball having many dimples, and such a scratch or deformation tends to be overlooked even in a visual inspection.

The present invention has been made in view of the above circumstances, and a golf ball is photographed with an optical device such as a camera, and a defective portion such as a scratch or dirt on the surface of the golf ball is surely detected from the obtained image by image processing. An object of the present invention is to provide a golf ball appearance inspection method capable of detecting the golf ball and automating the golf ball appearance inspection, and an appearance inspection apparatus for performing the inspection method.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a two-dimensional image by photographing the surface of a golf ball with a camera, and from the two-dimensional image, scratches or parts generated on the surface of the golf ball. In a method of inspecting the appearance of a golf ball for detecting an appearance defect such as mechanical deformation or dirt, two predetermined ranges on a golf ball surface which are point-symmetric with respect to each other with respect to a center point of the golf ball are photographed by a camera. By obtaining two two-dimensional images, superimposing the obtained two two-dimensional images on each other, and taking the difference between the data of the two two-dimensional images,
A method of inspecting the appearance of a golf ball, characterized by erasing a common part between both two-dimensional images and detecting the defective part appearing as a non-common part between the two two-dimensional images.

In the appearance inspection method of the present invention, image processing is performed by utilizing the symmetry of a dimple array formed on the surface of a golf ball, and a defective portion generated on the surface of the golf ball is detected. That is, the golf ball is provided with dimples so as to form a plurality of symmetry planes on the surface of the golf ball so that the same trajectory is obtained even if the golf ball is hit at any position. A golf ball surface is equally divided into surfaces corresponding to polyhedrons such as regular tetrahedron, regular octahedron, regular hexahedron, regular icosahedron, and dimples are similarly arranged on each divided surface. In this case, in any of the division methods, the dimple arrangements at two points which are point-symmetrical to each other with the center point of the ball interposed therebetween are symmetrical arrangements inverted from each other. In the present invention, the dimple arrangements are symmetrical to each other. Photographing two points on the golf ball surface to obtain two two-dimensional images,
By superimposing the two obtained two-dimensional images on each other and taking the difference between them, the common part is erased and a defective part appearing as a non-common part is detected.

That is, as shown in FIG. 1, a golf ball always has two portions A and B which are point-symmetrical with respect to the center point o of the ball, and these two portions A and B are photographed respectively. Then, as shown in FIG. 2, symmetrical images A and B, which are inverted from each other, are obtained. Then, both images A and B
By mirror-inverting one of them and superimposing them on each other and taking the difference, the common part of the two is erased and only the non-common part remains. As a result, only a defective portion that appears as a non-common portion between the two remains in the image, and by detecting this, the defective portion can be easily detected.

The images A and B can be obtained by shooting a ball while rotating it at a constant speed using a line sensor camera, and converting the obtained image into a two-dimensional image. A two-dimensional image may be directly obtained using a camera. In this case, by rotating the ball using a single fixed camera, two points that are point-symmetric to each other can be photographed.
Two cameras located at point symmetric positions may be photographed using two cameras. When two images at point symmetric positions are obtained using two area sensor cameras, two images obtained are obtained. Is not inverted, and there is no need to perform mirror inversion processing on the image.

As described above, the appearance inspection method of the present invention is configured to perform image processing using two images obtained from a golf ball to be inspected and detect a defective portion. That is, unlike the method in which an absolute sample is created in advance and the obtained image is superimposed, images of the golf ball surface are obtained at two points that are point-symmetric with respect to the center point of the golf ball. In this way, two images that completely overlap each other can be reliably obtained for each ball, and by processing the two images, the normal portion can be reliably erased and only the defective portion can be reliably detected. It is. In this case, both images are inspection images that also serve as reference images. Therefore, two surfaces of the golf ball G located on opposite sides can be inspected at the same time, which is excellent in inspection efficiency. .

According to the present invention, as a preferred appearance inspection apparatus for carrying out this appearance inspection method, there is provided a ball rotating means for holding a golf ball and rotating around a straight line passing through the center point of the golf ball. A fixed line sensor camera for photographing the surface of the golf ball, image conversion means for obtaining a two-dimensional image from image data captured by the line sensor camera, and two two-dimensional images with one mirror-reversed Image processing means for erasing the common portion of the two-dimensional images by superimposing the two on each other and taking the difference between the data of the two-dimensional images, and rotating the golf ball at a constant speed by the ball rotating means. While letting
The predetermined area of the golf ball surface is photographed by the line sensor camera, and the image data captured by the line sensor camera is converted by the image conversion means to obtain a first two-dimensional image.な が ら While the golf ball is being rotated at a constant speed from the rotated state as well, an image of the above-mentioned predetermined range and a point-symmetrical area across the center point of the golf ball is photographed by the line sensor camera, and the second By detecting a two-dimensional image and erasing a common part of the first and second two-dimensional images obtained by the image processing means, a defective appearance portion of a golf ball surface appearing as a non-common part of both two-dimensional images is detected. A golf ball appearance inspection device is provided.

That is, while the golf ball is rotated at a constant speed by the ball rotating means, the ball surface is photographed by the line sensor camera, and the image data is converted by the image converting means to obtain a two-dimensional image of the ball surface. At the same time, the golf ball is rotated by 180 ° about the diameter line by the ball rotating means, and the ball surface is similarly photographed to obtain a two-dimensional image, whereby the golf ball is point-symmetric with respect to the center point of the ball. The two two-dimensional images at the positions are obtained, the two two-dimensional images are superimposed by the image processing means in a state where one of them is mirror-inverted, and the difference between the data is used to eliminate the common part and to remove the common part. This is for detecting a defective portion that appears as a portion, and according to the above-described appearance inspection method of the present invention, the appearance of the golf ball surface such as scratches and dirt is not improved. It is intended to detect.

In this case, by automatically controlling the operations of the ball rotating means, the line sensor camera, the image converting means, and the image processing means using a computer or the like, the appearance inspection of the golf ball can be completely automated. Things.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific examples. According to the golf ball appearance inspection method of the present invention, as described above, two images on the golf ball surface which are point-symmetric with respect to each other with respect to the center point of the ball are taken by the camera, and the two images obtained are obtained. Are superimposed on each other in a state where one of them is inverted, the common parts are erased from each other, and a defective part that appears as a non-common part is detected. Specifically, for example, the method is performed by the apparatus shown in FIG. Can be done.

That is, FIG. 3 shows an example of an inspection apparatus for implementing the appearance inspection method of the present invention. In the figure, reference numerals 1 and 1 denote a pair of rotatable ball holding bodies, and one of the holding bodies 1 is The servo motor (stepping motor) 2 is driven and rotated, and the rotation speed and the rotation angle of the servo motor 2 are controlled by a pulse signal from a servo motor driver 3. The holding members 1 and 1, the servo motor 2 and the servo motor driver 3 constitute a ball rotating means.

In the figure, reference numeral 4 denotes a fixed line sensor camera, which linearly photographs the surface of the golf ball G held between the two ball holding bodies 1 and 1 and firstly captures the photographed data. Original two-dimensional conversion device (image conversion means) 5
And the image data obtained by the conversion device 5 is converted into two-dimensional image data. Further, in the figure, reference numeral 6 denotes an image processing device capable of storing the two-dimensional image data from the conversion device 5 in a memory, inverting the image data, and performing data calculation by superimposing two image data. In addition, an image obtained from the two-dimensional image data input to the image processing device 6 and an image obtained as a result of the above calculation are displayed on the monitor 7. Note that reference numeral 8 in the figure denotes an illumination device that illuminates a shooting location of the golf ball G.

When performing a visual inspection of a golf ball using the visual inspection apparatus according to the visual inspection method of the present invention,
First, a golf ball G to be inspected is held between the two ball holding bodies 1 and 1. In this case, the golf ball G is held so that the rotation axes of the holding members 1 and 1 pass through the center of the golf ball G, and by rotating the holding members 1 and 1, the golf ball G draws a straight line passing through the center point thereof. Set to rotate around the axis.

In this state, the inspection is started by operating the golf ball G while illuminating the golf ball G with the illumination device 8.
When the inspection is started, a pulse signal is transmitted from the servo motor driver 3 to the servo motor 2, and the servo motor 2 rotates at a constant speed and a predetermined angle in accordance with the pulse signal.
The golf ball G rotates at a constant speed by a predetermined angle. At this time, the predetermined range 9a of the surface of the golf ball G is linearly photographed by the line sensor camera 4 while rotating, and the image data is converted into two-dimensional image data by the one-dimensional two-dimensional converter 5 to perform image processing. Input to the device 6. At this time, the servo motor driver 3 transmits the pulse signal to the servo motor 2 and, at the same time, transmits an image capture signal to the image processing device 6, and the two-dimensional image data input to the image processing device 6 by the signal. Is stored in the memory, and the image is displayed on the monitor 7.

Next, a ball reversal signal is transmitted from the servo motor driver 3 to the servo motor 2, and the servo motor 2 rotates to rotate the golf ball G from the inspection start state to a state rotated by 180 °. Then, from this state, the second pulse signal is transmitted from the servo motor driver 2 to the servo motor 2 and the image capture signal is transmitted to the image processing device 6, and the second pulse signal is transmitted across the center point of the ball G in the same manner as described above. (4) The two-dimensional image data of the displaced predetermined range 9b is taken into the image processing device 6, and the image is displayed on the monitor 7.

In this case, the image of the photographing range 9a obtained by the first capture is as shown in FIG. 4A, and the image of the photographing range 9 obtained by the second capture is obtained.
The image b is an image obtained by inverting the image (a) obtained by the first capture, as shown in FIG. 4B. In addition,
The circled portions in FIGS. 4A and 4B are defective portions.

Next, the two images (a) and (b) are superimposed on each other in a state where one of the images (a) and (b) is mirror-inverted by the image processing device 6, and a difference between them is taken. Deletes the common part of both images (a) and (b). Thereby, as shown in FIG. 4C, only defective portions (circled portions in FIGS. 4A and 4B) appearing as non-common portions of (a) and (b) of both images. Remain on the processed image (c), thereby determining the presence or absence of a defect.
The processed image is displayed on the monitor 7.

Then, such an operation is performed by using the golf ball G
Is performed on the entire surface of the golf ball to perform a visual inspection of the golf ball. The final judgment of good or bad may be made by the operator checking the monitor, or the defective part remaining in the processed image may be automatically detected as data and the good or bad judgment may be made completely automatically. .

As described above, according to the golf ball appearance inspection method and appearance inspection apparatus of the present invention, two images which are symmetrical and inverted from each other are taken from the golf ball itself by utilizing the symmetry of the golf ball. It is configured to perform image processing using one image and detect a defective portion, so unlike the method of creating an absolute sample in advance and superimposing this on the obtained image, the golf ball is rotated by 180 degrees. By rotating and obtaining two images, it is possible to reliably obtain two images that completely overlap each other for each individual ball, and it is possible to surely erase a normal portion and reliably detect only a defective portion. Things. Further, in this case, both images are inspection images which also serve as reference images, so that two surfaces of the golf ball located on opposite sides can be inspected at the same time, which is excellent in inspection efficiency.

The appearance inspection method of the present invention is not limited to the above embodiment, and may be variously modified without departing from the gist of the present invention. For example, in the above embodiment, an image is captured using a line sensor camera, and using a line sensor camera in this manner enables shooting of a large area by shooting while rotating a golf ball. In addition, it is preferable in that it is hardly affected by illumination and the like, but it is also possible to directly capture a two-dimensional image using a normal area sensor camera. In the above embodiment, the golf ball is 1
The second image was captured by rotating the camera by 80 °.
It is also possible to simultaneously capture two images. In this case, when two area sensor cameras are used, it is not necessary to mirror-invert one of the two captured images. Furthermore, in the above embodiment, after capturing one image, the ball is rotated by 180 ° to capture the second image. However, while the golf ball is intermittently rotated, four or more images are captured continuously. Automatically inspecting the entire surface of the ball by automatically selecting an image at a symmetrical position from among the images captured by a signal from the servo motor driver 3 and performing image processing. Is also possible.

The appearance inspection apparatus of the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, an image capture signal is transmitted from the servo motor driver 5 to the image processing apparatus 7 so that an image within a predetermined range is transmitted. Although the capturing is performed, it is also possible to separately provide a rotation angle measuring device for measuring the rotation angle of the golf ball G and control the capturing range of the image by the angle measuring device. Further, the ball rotating means and its control system may be appropriately changed without departing from the spirit of the present invention.

[0028]

As described above, according to the appearance inspection method and appearance inspection apparatus of the present invention, defects such as scratches and dirt generated on the surface of a golf ball can be surely processed by a method of performing image processing by photographing the ball surface. Thus, it is possible to achieve automation of the visual inspection of the golf ball.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating the principle of a visual inspection method according to the present invention.

FIG. 2 is an explanatory diagram illustrating the principle of the appearance inspection method of the present invention.

FIG. 3 is a schematic view showing an appearance inspection apparatus according to one embodiment of the present invention.

FIGS. 4A and 4B are explanatory diagrams illustrating image processing in the appearance inspection method according to one embodiment of the present invention, wherein FIG. 4A is a first two-dimensional image, FIG. 4B is a second two-dimensional image, and FIG. ) Is an image after image processing.

[Explanation of symbols]

 Reference Signs List 1 ball holding body 2 servo motor 3 servo motor driver 4 line sensor camera 5 one-dimensional two-dimensional converter 6 image processing device 7 monitor 8 lighting device 9a first shooting location 9b second shooting location G golf ball o center point

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-111551 (JP, A) JP-A-63-180841 (JP, A) JP-A-2-213709 (JP, A) JP-A-1 143334 (JP, A) JP-A-59-79844 (JP, A) JP-A-6-160049 (JP, A) JP-A-6-300534 (JP, A) JP-A-4-29043 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G01N 21/84 -21/90 G01B 11/30

Claims (3)

(57) [Claims] 1. An appearance of a golf ball in which a two-dimensional image is obtained by photographing the surface of a golf ball with a camera, and an appearance defect such as a scratch, partial deformation or dirt on the surface of the golf ball is detected from the two-dimensional image. In the inspection method, two predetermined areas on the golf ball surface which are point-symmetric with respect to each other with respect to the center point of the golf ball are respectively photographed by a camera to obtain two two-dimensional images, and the obtained two two-dimensional images are obtained. By superimposing on each other and taking the difference between the data of the two-dimensional images, thereby eliminating the common part of the two-dimensional images and detecting the defective part appearing as a non-common part of the two-dimensional images. Golf ball appearance inspection method. 2. A fixed line sensor camera for photographing a predetermined area on the surface of the golf ball while rotating the golf ball at a constant speed about a straight line passing through the center point of the golf ball. A first two-dimensional image is obtained from the image data captured by the camera, and then the golf ball is rotated at a constant speed from a state where the golf ball is rotated by 180 °. An area that is point-symmetrical with respect to the point is photographed by the line sensor camera, and a second two-dimensional image is obtained from image data captured by the line sensor camera.
The golf ball appearance inspection method according to claim 1, wherein the two first two-dimensional images are superimposed on each other in a state where one of the obtained first and second two-dimensional images is mirror-inverted. 3. A ball rotating means for holding a golf ball and rotating around a straight line passing through a center point of the golf ball, a fixed line sensor camera for photographing the surface of the golf ball, and the line sensor Image conversion means for obtaining a two-dimensional image from the image data captured by the camera; and superimposing the two two-dimensional images on each other in a state where one of the two-dimensional images is mirror-inverted, and calculating the difference between the data of the two two-dimensional images. Image processing means for erasing a common portion of the three-dimensional image, while rotating the golf ball at a constant speed by the ball rotating means, photographing a predetermined range of the golf ball surface with the line sensor camera, The image data captured by the line sensor camera is converted by the image conversion means to obtain a first two-dimensional image. While the golf ball is rotated at a constant speed from the state where the golf ball is rotated by 0 °, a range that is point-symmetric with respect to the predetermined range and the center point of the golf ball is photographed by the line sensor camera. By removing the common part of the first and second two-dimensional images obtained by the image processing means, a defective appearance portion of the golf ball surface appearing as a non-common part of the two-dimensional images is obtained. A golf ball appearance inspection device for detecting.