JP2655210B2 - Defect inspection method for glass cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a defect of a transparent glass cylinder by using image processing.

[0002]

2. Description of the Related Art A conventional inspection method is disclosed in Japanese Patent Laid-Open No. 57-201.
As described in "Inspection Method for Bottles" of JP-A-839, illumination light is incident on the opening of a transparent bottle from both sides, and a reflection pattern from the surface of the opening is detected by a line sensor. .

[0003]

In the above prior art, the determination is made by capturing the reflected light from the surface of the opening of the bottle.
It is effective for identifying defects such as cracks generated near the surface of the opening.However, defects such as cracks generated inside the glass cylinder are not considered. There was no effective means to do so and they had to rely on visual inspection. An object of the present invention is to provide a glass tube defect inspection method for automatically detecting, using image processing, minute cracks existing inside a transparent glass tube, and deformation and chipping of a tube end. It is in.

[0004]

In order to achieve the above object, a method of inspecting a glass cylinder for defects according to the present invention is directed to a method for inspecting a defect of a glass cylinder in a direction substantially perpendicular to an axis of the glass cylinder. Irradiating the spot light so as to face the same, capturing the transmitted light transmitted through the wall of the glass cylinder with a CCD camera arranged opposite to the opening at the other end of the glass cylinder, and processing the captured image. It is characterized by.

[0005] In a binarized image obtained by binarization as image processing, an area perpendicular to the direction of the opposing spot light is defined as a defect determination area. The pass / fail is determined by determining the area of the image defect image. The area of the defect image may be obtained by counting the number of pixels that form a white image among the pixels corresponding to the defect determination area among the pixels of the CCD camera. Alternatively, the defect image may be determined by inverting the black background and the black and white of the white image in the defect determination area.

[0006]

The light radiated as the spot light on the side surface of one end of the transparent glass cylinder passes through the wall of the glass cylinder and radiates from the opening surface at the other end of the glass cylinder. When this emitted light is imaged by a CCD camera and the imaged image is binarized, the image area corresponding to the spot irradiated with the spot light becomes a white screen with high luminance, and the image area corresponding to the dark area not irradiated with the spot light is A binary image serving as a black screen is obtained. If there is a defect such as a crack, deformation, or crack in the wall portion through which the light passes, the light is refracted there, and the defect image appears as a white screen in a black screen. By rotating the glass cylinder by a certain angle, a binary image of each part is obtained, and the size of the defect is determined by obtaining the total area of the white screen appearing on the black screen, and the pass / fail of the glass cylinder is determined. The area of the defective image, that is, the area of the white screen in the black screen can be easily and quickly obtained by counting the number of white pixels in the pixels corresponding to the defective area among the pixels of the CCD camera. It is obvious that the black screen and the white screen can be reversed in the image processing.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a view showing the structure and arrangement of an apparatus for carrying out a method for inspecting defects of a glass cylinder according to one embodiment of the present invention. The subject is a transparent cylindrical glass tube as a glass cylinder. As shown in FIG. 1, illuminating devices 2a and 2b are arranged so as to face each other so as to sandwich a cylindrical glass tube 1 which is a subject, and spot lights 3a and 3b are formed by the illuminating devices 2a and 2b. One end of the tube 1 is irradiated from a direction substantially perpendicular to the axis of the cylindrical glass tube 1. The irradiated light passes through the glass tube 1 as shown by the transmitted light indicated by the arrow 4, and at this time, part of the light is refracted by a crack 5a inside the tube or a chip 5b at the end of the tube. The image is input as an image to the CCD camera 6 arranged opposite to the end.
This video is binarized and analyzed by the image processing device 10.

FIG. 2 shows a binary image obtained by binarizing an image captured by a CCD camera with an appropriate threshold value, and shows that the glass tube 1 is defect-free and good.
The side irradiated with the spot lights 3a and 3b has a large amount of light transmission, so that portions appear as white images 7a and 7b.
The other area shifted by 90 degrees from the white image is the determination area 8.

FIG. 3 shows a glass tube 1 having internal cracks 5a,
5 shows a binary image in the case where there is a defect such as a chip 5b at a pipe end. The transmitted light 4 passing through the glass tube 1 is refracted by the defect and is input to the CCD camera 6, so that a defect image 9 corresponding to the defect appears in the determination area 8. The number of pixels of the defective image 9 is counted, and the pass / fail of the glass tube is determined based on the count value. As described above, since the determination can be performed only by counting the number of pixels of the defect image, the determination process can be easily performed at high speed.

Another embodiment is shown in FIGS.

FIG. 4 shows a method of inspecting by illuminating light 3a, 3b from both ends on the bottom side of a transparent glass container 11 having a bottom. The incident light propagates through the inside of the glass container 11 as a waveguide, and the light emitted from the open end receives the defect 5 in the waveguide of the glass container 11 input to the CCD camera 6.
If there are a and 5b, the transmitted light 4 is blocked or refracted there and input to the CCD camera 6. The input light is broken by the image processing apparatus 10 to determine the presence or absence of a defect.

FIG. 5 shows a transparent glass container 12 having a round shape instead of a straight tube. Since the transmitted light 4 propagates using the thick glass portion of the container as a waveguide, defects 5
If there are a and 5b, the presence or absence of a defect can be determined in the same manner as described above. The illumination devices 2a and 2b are
As long as the light is not directly irradiated to the light, the light may be inclined as shown in FIG.

FIGS. 6 and 7 show examples of binary images in the case where the cross-sectional shape of the container is quadrangular or triangular, respectively. Can be determined.

[0015]

According to the present invention, a method for inspecting a defect of a glass cylinder is described by irradiating light to a side surface of one end of a transparent glass cylinder and transmitting the light through the wall of the glass cylinder. Light emitted from the opening surface at the other end is captured by a CCD camera, and the captured video is binarized, so that the image area corresponding to the light-irradiated portion becomes a white screen with high brightness,
In the image area corresponding to the dark area that does not hit, a binary image that becomes a black screen is obtained, and if there is a defect such as cracks, deformation, or crossing in the wall part where the light is transmitted, the light is refracted there and it is within the black screen. The defect appears as a white screen, and therefore, the defect can be easily detected by the white screen in the black screen.

This makes it possible to automate the visual inspection conventionally performed by a skilled inspector, which is effective in reducing inspection costs and preventing defective products from being sent out.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration and an arrangement of an apparatus for realizing an embodiment of the present invention.

FIG. 2 is a diagram showing a binary image of a glass cylinder having no defect.

FIG. 3 is a diagram showing a binary image of a glass cylinder having a defect.

FIG. 4 is a diagram showing a state where a glass container having a bottom is being inspected.

FIG. 5 is a diagram showing a state in which a round glass container is being inspected.

FIG. 6 is a diagram showing a binary image of a cylinder having a rectangular cross section.

FIG. 7 is a diagram showing a binary image of a cylinder having a triangular cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical glass tube 2a, 2b Illumination device 3a, 3b Spot light 4 Transmitted light 5a Crack 5b Hanging 6 CCD camera 7 White image 8 Defect judgment area 9 Defect image 10 Image processing device 11 Glass container 12 Glass container

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Osamu Shimazaki, Inventor 3-2-1 Sachimachi, Hitachi, Ibaraki Prefecture Within Hitachi Engineering Co., Ltd. (72) Sumi Ishikawa 3-2-1 Sachimachi, Hitachi, Ibaraki Prefecture Within Hitachi Engineering Co., Ltd. (72) Inventor Yasutada Shirakura 1-13-18 Shimizudai, Takatsuki-shi, Osaka (56) References JP-A-2-103453 (JP, A) JP-A-1-141341 (JP, A JP-A-60-194336 (JP, A)

Claims (4)

(57) [Claims] 1. A side face of one end of a transparent glass cylinder is irradiated with a spot light at a right angle substantially perpendicular to the axis of the glass cylinder, and transmitted light transmitted through a wall of the glass cylinder is irradiated with the spot light. A method of inspecting a defect of a glass cylinder, wherein an image is taken by a CCD camera arranged to face an opening at the other end of the glass tube, and the taken image is processed. 2. A binarized image obtained by binarization processing as image processing, a region perpendicular to the direction of the opposing spot light is defined as a defect determination region, and a region on a black background of the defect determination region is defined as a defect determination region. 2. The defect inspection method for a glass cylinder according to claim 1, wherein the appearance of the white image is regarded as a defect image, and the area of the defect image is determined to determine whether or not the defect image is acceptable. 3. The defect inspection method for a glass cylinder according to claim 2, wherein the area of the defect image is obtained by counting the number of pixels forming a white image among pixels corresponding to a defect determination area among pixels of the CCD camera. 4. The defect inspection method for a glass cylinder according to claim 2, wherein the black background of the defect determination area and the black and white of the white image are inverted.