JP2001272351A - Defect-inspecting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect a black defect included in transparent granular tested objects to be tasted. SOLUTION: In an inspection unit 2, a lower illuminating apparatus 4 is arranged below a transparent conveyor belt 3, while a horizontal radiation apparatus 5 is arranged directly beside the conveyor belt 3. An image of a tested object S is photographed by means of an imaging device 6 in the inspection unit 2 so as to be processed by means of an image processor 7, and if a colored part is detected in the tested object S, it is determined as being a defective item. Because illuminating light from the horizontal radiation apparatus 5 illuminates the side face of the tested object S, a shadow, which may be generated in the end part of the object to be tested, when lighting is carried out only by the lower lighting apparatus 4, is not generated. Therefore, the image taken by the imaging device includes no shadow, and wrong determination of a defective part can be prevented.

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. Colored portions, such as black, are observed in the resin pellets having a defect due to a foreign substance or the like mixed therein. In order to detect and remove this colored part mechanically,
An object to be inspected is imaged using a line sensor, a CCD camera, or the like, and the obtained image is processed to detect a colored portion included in the object to be inspected. 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, the illumination light is emitted from above the camera.

[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.
At that time, the illumination light from below may be scattered around the side of the inspection object, that is, in the vicinity of the end face, depending on the inclination and the state of the surface, so that the portion may look like a shadow. Since this shadow is imaged as black as a foreign substance, it is necessary to exclude it by software processing, and further, there is a problem that it is not always possible to completely remove the shadow on the end face portion by software. In addition, even when illumination light is applied from above the object to be inspected, the illumination light does not always reach the side of the object to be inspected. Often.

[0005] The present invention has been made in view of such circumstances, and has no effect of shadows caused by illumination on black or other colored defects contained in a transparent or translucent granular test object. It is an object of the present invention to provide a defect inspection apparatus capable of detecting the defect as described above. 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. In addition, the expression “black” is used not only for black itself but also as a word representing all black and colored colors.

[0006]

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. A defect inspection apparatus that detects a defect on the surface or inside of an inspection object by performing processing on an obtained image, is provided with an illumination device that irradiates the inspection object with light from below and in a horizontal direction.

The defect inspection apparatus according to the present invention illuminates the inspection object with light from below and further irradiates light from the horizontal direction with an illumination device in order to detect a dark color defect such as black, that is, a foreign substance. I have to. Illumination light from below highlights the black defect by brightening the background of the captured image, and illumination light from the horizontal direction illuminates the edge of the inspection object so that no shadow is produced. By doing so, no shadow is produced around the object to be inspected, so that there is no possibility of detecting anything other than a defect as a defect.

In the defect inspection apparatus of the present invention, it does not preclude the provision of an auxiliary illumination device for illuminating the inspection object from above. The addition of illumination from the top makes the whole lighter, but top illumination is not essential in highlighting black defects.

The plate for placing and inspecting the object to be inspected in the inspecting section can also serve as an endless conveyor belt for conveying the object to be inspected. In this case, the conveyor belt is desirably a transparent or light-diffusing color and surface material. By placing an inspection object supplied from a hopper or the like on the conveyor belt and passing the inspection object sequentially through the inspection unit, a large number of inspections of the inspection object can be continuously inspected for defects. Further, as an imaging device, an object to be inspected on a moving conveyor can be imaged using a line sensor. Instead of the line sensor, an image pickup device may be used by using a CCD camera capable of capturing surface data.

[0010]

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
A transparent or translucent resin pellet (test object) having a medium size is photographed by an imaging device, and particles including black spots are determined to be defective. A large amount of resin pellets are inspected one after another while being conveyed to a belt conveyor, etc., and a group of pellets including defective products is eliminated,
This is a device for preventing the use as a raw material of plastic products in the next step.

In FIG. 1, granular inspection objects S supplied from a hopper 1 are scattered and placed on a conveyor belt 3 so as not to overlap with each other. Conveyor belt 3
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 the figure as the conveyor belt 3 moves. An inspection unit 2 is provided at a predetermined position in the traveling direction of the conveyor belt 3, and the inspection unit 2 inspects whether or not the inspection object S has a defect. A defective product removing device 8 is provided at the end of the inspection unit 2, and the inspection object determined to be defective in the inspection unit 2 is swept out from the conveyor by the defective product removing device 8 and is sent to the defective product collection box 9.
Will be collected. 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, the inspection object that is not determined to be defective in the inspection section 2 is a non-defective product, and is further collected in the non-defective product collection box 10 installed at the end of the conveyor belt.

The configuration of the inspection section 2 will be described. The conveyor belt 3 is a transparent or translucent material having a light diffusing property, and can transmit light. In the inspection unit 2, a lower illuminator 4 that generates illumination light is disposed below the belt 3, and illuminates the inspection object S on the belt through the belt 3 from below. Further, a horizontal illuminator 5 that generates illumination light is installed at a position at the same height right beside the belt 3, and illuminates the inspection object S from a horizontal direction. As shown in a plan view in FIG. 2, the horizontal illuminators 5 are arranged on the left and right with the conveyor belt 3 interposed therebetween, and illuminate in a direction concentrated toward a center of the inspection unit 2 as indicated by an arrow B. Irradiating light.

In the illustrated example, the lower illuminator 4 and the horizontal illuminator 5 both guide light generated by a light source lamp installed in another place (not shown) by an optical fiber. Are formed in a ring shape (or a semi-ring shape). Therefore, the illumination light is applied to the inspection object S from various directions in all directions.

Above the inspection section 2, an imaging device 6 for photographing the inspection object S from above is installed. The image of the inspection object S obtained by the imaging device 6 is subjected to image processing by an image processing device 7 mainly composed of a computer, and it is determined whether the inspection object S, which is originally a transparent or translucent material, has a colored portion. The presence or absence of a defect is determined by the determination.

The imaging device 6 can be a line sensor arranged at right angles to the traveling direction of the conveyor belt 3, and in this case, an image can be formed as a surface as the belt 3 advances. Further, the imaging device 6 may be an imaging device such as a CCD camera that can capture an image as a surface. 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 7 can use a small personal computer or the like. The image processing device 7 extracts a discolored portion included in the inspection object by well-known image processing based on an image obtained by the imaging device 6. A pass / fail decision is made. Further, the computer constituting the image processing device 7 can also function as a control device for controlling the conveyor 3, the imaging device 6, the defective product removing device 8, and other components.

FIG. 3 shows another example of the arrangement of the conveyor belt and the horizontal illuminator in the inspection section. FIG. 3A is a plan view, and FIG. 3B is an elevation view. The conveyor belt 13 is wound around a roller so as to form a mountain having a peak at the inspection section. A lower illuminator 14 is provided below the inspection section, which is the top of the mountain, and a ring-shaped horizontal illuminator 15 is provided so as to surround the top. The lower illuminator 14 illuminates the inspection object S on the belt through the belt 13 from below, and the horizontal illuminator 15 can illuminate the inspection object S in the inspection section from all around. In this configuration example, since the object to be inspected is illuminated from all around, the occurrence of shadows on the end surface of the object to be inspected can be further reduced.

[0018]

Since the defect inspection apparatus of the present invention illuminates from the side of the object to be inspected in addition to the illumination from below, no shadow is produced on the side of the object to be inspected, and the shadow is regarded as a colored portion. There is no mistake. Therefore, it is not necessary to remove the shadow by software, and it is possible to reliably detect only the colored portion included in the inspection object.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing an arrangement of a horizontal illuminator.

FIG. 3 is a diagram showing another arrangement example of the conveyor belt and the horizontal illuminator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hopper 2 ... Inspection part 3 ... Conveyor belt 4 ... Lower illuminator 5 ... Horizontal illuminator 6 ... Imaging device 7 ... Image processing device 8 ... Defective product removal device 9 ... Defective product collection box 10 ... Good product collection box 13 ... Conveyor Belt 14: Lower illuminator 15: Horizontal illuminator S: Inspection object

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. 1. A defect inspection apparatus for detecting defects according to claim 1, further comprising an illumination device for irradiating the object to be inspected with light from below and in a horizontal direction.