JP2001272354A - Defect inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect both of black defects and white defects included in transparent granular tested objects. SOLUTION: In a first inspection unit 3, a light diffusing plate 4, arranged below a transparent conveyor belt 2 and a first lighting apparatus 5 radiating light beams from the upper side are arranged, and the tested object is illuminated from both of the upper and lower sides. In this process, an image of the tested object is taken by a first image pickup device 6 for detecting black defects. In a second inspection unit 7, a light-absorbing plate 8 arranged below the belt 2 and a second lighting apparatus 9 radiating light beams from the upper side are arranged. In this process, because the background of an image taken by means of a second image pickup device is darkened, a white detect can be detected. The images photographed by means of the two image pickup devices are processed by means of an image processor 11, and existence of a defect is determined if a part colored in black or white is detected in the tested object S, and subsequently, removal as a defective item is carried out by means of a defective item removing device 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a defect contained in the surface or inside of an inspection object by optically imaging a transparent or translucent granular material such as a resin pellet and performing image processing. The present invention relates to a defect inspection apparatus.

[0002]

2. Description of the Related Art Resin pellets are a raw material for various plastic products. However, if a set of resin pellets contains defective products containing colored foreign substances, the quality of the final plastic product will be reduced. Therefore, it is required to remove defective products at the stage of resin pellets. A black or white colored portion is observed in the resin pellet having a defect due to a foreign substance mixed therein. In order to mechanically detect and remove the colored portion, an image of the inspected object is taken using a line sensor, a CCD camera, or the like, and the obtained image is processed to detect a colored portion included in the inspected object. Is done. When a colored portion is detected, a group of pellets around the colored portion is discarded.

In a conventional technique for detecting a defect using an image processing technique, an image of an object to be inspected is captured as follows, for example. In the inspection unit, the object to be inspected is placed on a transparent plate, and the object is imaged from above by a line sensor or a CCD camera while irradiating the object with illumination light from below,
The obtained data was subjected to image processing to extract a black portion to determine the presence or absence of a defect. In some cases, an object to be inspected is placed on a milky white plate having light diffusing properties, and an image is similarly taken from above while illuminating light is applied from above.

[0004]

When an object to be inspected is placed on a transparent plate and illuminated with light from below, black or dark foreign substances inside and on the surface of the object are illuminated by light. , And is captured and detected as black.
However, at this time, since the illuminating light from below is scattered around the side of the test object, that is, near the end face, the part looks like a shadow and becomes black like a foreign substance. Troubles such as having to
Furthermore, there is a problem that software exclusion cannot always be completely executed. In addition, when the object to be inspected is placed on a plate having light diffusivity and the illumination light is applied from above, the black foreign matter is relatively clear because the illumination light is applied from all directions below. Can be detected.

On the other hand, it is difficult to detect white or bright foreign matter. Regardless of the method of illuminating the test object on the transparent plate from below, or the method of illuminating the test object placed on the light diffusion plate from above, the white foreign matter is the same as the background It is difficult to detect because the image is captured brightly.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a defect inspection apparatus capable of detecting both black and white defects contained in a transparent or translucent granular inspection object. Aim. It should be noted that the defect of the inspection object referred to in the present invention refers to any one including a colored foreign substance mixed therein and one having an apparent color due to other causes. Further, the expression of black or white is used as a word that represents not only black and white itself but also all black colors, that is, dark colors and white colors, that is, bright colors.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention captures an image of a transparent or translucent granular inspection object on an inspection section while irradiating the illumination object with illumination light. In a defect inspection apparatus that detects a surface or internal defect of an inspection object by performing processing on an obtained image, a transparent belt that conveys the inspection object, a light source that irradiates light from above, and a light A first inspection unit provided with a first image pickup device for disposing a light diffusion plate for reflecting light from above, a light source for irradiating light from above, and a light absorbing plate for not reflecting light below the belt, A second inspection unit provided with a second imaging device that captures an image from an object, wherein the first inspection unit detects a black defect included in the inspection object, and
The inspection unit detects a white defect included in the inspection object.

The defect inspection apparatus according to the present invention comprises a first inspection section for detecting a dark defect such as black, ie, a foreign substance, and a second inspection section for detecting a bright defect such as white, ie, a foreign substance. It has an inspection unit. The first inspection unit includes a first imaging device that captures an image from above, and irradiates the inspection object placed on the transparent belt with illumination light from above, and reflects and scatters light below the inspection object. Since the light diffuser plate is arranged, light is applied to the inspection object from all directions from above and below, so that the captured image has a bright background, so that black defects can be clearly distinguished and distinguished. it can. As the light diffusing plate, a milky white plastic plate, white paper or cloth, or a metal plate with a rough surface can be used.

The second inspection section includes a second image pickup device for picking up an image from above, a light absorbing plate that does not reflect light is disposed below the transparent belt, and illuminates with illumination light from above. Since the light from above does not bounce off the light absorbing plate, the background of the inspected object becomes dark in the captured image, and the white defect included in the inspected object is imaged so as to rise, and is clearly distinguished and distinguished. be able to. As the light absorbing plate, a metal plate or a plastic plate coated with a matte black paint, or black paper or cloth can be used.

[0010] An endless conveyor belt can be used as the transparent belt for mounting the inspection object. The inspection object supplied from a hopper or the like is placed on the conveyor belt and sequentially passed through the first inspection unit and the second inspection unit while being conveyed, thereby continuously inspecting a large number of defects of the inspection object. It can be carried out. Further, the first and second imaging devices can image an inspection object on a moving conveyor using a line sensor. Instead of the line sensor, a CCD camera capable of capturing surface data can be used.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of a defect inspection apparatus of the present invention as viewed from the side. The defect inspection device of the present invention is several mm
An image of a transparent or translucent resin pellet (test object) having a medium size is photographed by an imaging device, and particles including black or white spots are determined to be defective.
It is a device that inspects one after another while transporting a large amount of resin pellets to a belt conveyor, etc., and removes a group of pellets including defective products so that they will not be used as raw materials for plastic products in the next process .

In FIG. 1, granular inspection objects S supplied from a hopper 1 are scattered and placed on a conveyor belt 2 so as not to overlap with each other. Conveyor belt 2
Is endless, and the inspection object S
Are rotated so as to continuously move in the direction A in FIG. The inspection object S placed on the conveyor belt is carried in the direction A in FIG. A first inspection unit 3 is provided at a predetermined position in the traveling direction of the conveyor belt 2, and the first inspection unit 3 inspects whether or not the inspection object S includes a black defect. A second inspection unit 7 is provided at a predetermined position ahead of the second inspection unit 7. The second inspection unit 7 inspects whether or not the inspection object S includes a white defect. A defective product removal device 12 is provided at the end of the second inspection unit 7. The inspection object determined to be defective in the first inspection unit 3 or the second inspection unit 7 is removed from the conveyor by the defective product removal device 12. It is swept out and collected in the defective product collection box 13. At this time, since the inspection object S is as small as about several mm, a group of inspection objects including the inspection object determined to be defective is collectively removed. On the other hand, since the inspection object which is not determined to be defective in any of the inspection units is a non-defective product, it is further collected in the non-defective product collection box 14 installed at the end of the conveyor belt.

The configuration of the first inspection unit 3 will be described. The conveyor belt 2 is a transparent material and can transmit light. In the first inspection unit 3, a light diffusion plate 4 that reflects light while diffusing light is disposed below the belt 2, and a first illuminator 5 that generates illumination light is installed above the belt 2. The illumination light generated by the first illuminator 5 brightly illuminates the inspection object S from above, reaches the light diffusion plate 4 through the transparent belt 2, and is reflected in all directions so as to be diffused. The reflected light illuminates the inspection object S from below. Since the illumination light from below brightens the background of the captured image, black defects can be clearly extracted.

Above the first inspection section 3, a first imaging device 6 for photographing the inspection object S from above is installed.
The image of the inspection object S obtained by the first imaging device 6 is subjected to image processing by an image processing device 11 mainly composed of a computer, and a black coloring portion is formed on the inspection object S which is originally a transparent or translucent material. The presence or absence of a defect is determined by determining whether or not there is a defect.

As the light diffusing plate 4, a white or milky white plastic plate such as a fluororesin can be used. Alternatively, a plate to which white paper or cloth is pasted may be used. Further, a metal plate processed so as to have a rough surface may be employed. When a milky white plastic plate that transmits a certain amount of light is used as the light diffusion plate 4,
An illuminator different from the first illuminator 5 that illuminates the light diffusion plate 4 from the lower portion thereof may be used in combination.

Next, the configuration of the second inspection unit 7 will be described. In the second inspection unit 7, a light absorbing plate 8 that does not reflect light is arranged below the belt 2, and a second illuminator 9 that generates illumination light is installed above the belt 2. Second illuminator 9
Is brightly illuminating the inspection object S from above, but most of the light that reaches the light absorbing plate 8 through the transparent belt 2 is absorbed and does not return upward. Therefore, when the inspection object on the conveyor belt 2 is viewed from above, the background becomes dark, and white defects included in the inspection object S can be clearly extracted.

Above the second inspection section 7, a second imaging device 10 for photographing the inspection object S from above is installed. The image of the inspection object S obtained by the second imaging device 10 is subjected to image processing by the image processing device 11, and the inspection object S, which is originally a transparent or translucent material, has a white colored portion or turbidity. The presence or absence of a defect is determined by determining whether there is a defect.

As the light absorbing plate 8, a plate made of a plastic or metal plate with a black matte coating can be used. Alternatively, a rough black paper or a plate pasted with cloth may be used.

In the illustrated example, both the first illuminator 5 and the second illuminator 9 guide light generated by a light source lamp installed in another place (not shown) by an optical fiber. The light emitting portion is formed in a ring shape. Therefore, the illumination light is applied to the inspection object S from various directions in all directions. Since the central portion of the illuminator is open, the first imaging device 6 or the second imaging device 10 does not hinder the imaging.

The first imaging device 6 and the second imaging device 10 can be line sensors arranged at right angles to the traveling direction of the conveyor belt 2, and in this case, as the belt 2 travels, Images can be composed.
Further, these imaging devices may be imaging devices that can capture images as a surface such as a CCD camera. In this case, by capturing images at appropriate time intervals, all the inspection objects carried by the conveyor can be observed without waste.

The image processing device 11 can use a small personal computer or the like. Based on the images obtained by the first imaging device 6 and the second imaging device 10, the image processing device 11 is included in the inspection object by well-known image processing. A pass / fail judgment is made by extracting a discolored portion such as black or white. Further, the computer constituting the image processing apparatus 11 can also function as a control device for controlling the conveyor 2, the imaging devices 6 and 10, the defective product removing device 8, and other components.

[0022]

According to the defect inspection apparatus of the present invention, the first inspection section highlights black defects by illumination from above and below, and the second inspection section is illuminated from above with a light absorbing plate below. As a result, the background of the image of the inspection object becomes dark, so that white defects can be highlighted. Therefore, since both black and white defects included in the inspection object can be detected, defective products can be efficiently removed by one apparatus.

[Brief description of the drawings]

FIG. 1 is a schematic elevation view of a defect inspection apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hopper 2 ... Conveyor belt 3 ... 1st inspection part 4 ... Light diffusion plate 5 ... 1st illuminator 6 ... 1st imaging device 7 ... 2nd inspection part 8 ... Light absorption plate 9 ... 2nd illuminator 10 ... Second 2 Imaging device 11 ... Image processing device 12 ... Defective product removal device 13 ... Defective product collection box 14 ... Good product collection box S ... Inspection object

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Claims (1)

[Claims] 1. A method for processing an image obtained by imaging a transparent or translucent granular inspection object on an inspection unit while irradiating the illumination light on the inspection object, the surface or the inside of the inspection object. In a defect inspection apparatus for detecting a defect, a transparent belt for transporting an object to be inspected, a light source for irradiating light from above, and a light diffusion plate for reflecting light at the lower part of the belt are arranged, and a first for imaging from above. A first inspection unit provided with an imaging device, a second inspection unit provided with a light source for irradiating light from above and a second imaging device for arranging a light absorbing plate which does not reflect light under the belt and imaging from above; The first inspection unit detects a black defect contained in the object to be inspected;
A defect inspection apparatus characterized in that an inspection section detects a white defect included in an inspection object.