JP2001272352A - Defect inspection equipment - Google Patents

Abstract

(57) [Summary] A black defect included in a transparent granular test object is reliably detected. In an inspection unit, a lower illuminator is disposed below a transparent conveyor belt, and an ultraviolet irradiator is disposed above the transparent illuminator. The image of the inspection object S is picked up by the imaging unit 6 in the inspection unit 2 and processed by the image processing device 7. When a colored portion is detected on the inspection object S, it is determined that the inspection object S is defective. When ultraviolet light from the ultraviolet irradiator 5 is irradiated on the inspection object S, fluorescent light that is visible light is generated.
The object to be inspected is illuminated from the inside, so that the whole becomes bright without shadows even at the edges. Therefore, the image taken by the imaging device does not include a shadow and is not mistaken for a defective portion.

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 includes an ultraviolet irradiation device that irradiates the inspection object with ultraviolet light.

The defect inspection apparatus of the present invention is provided with an ultraviolet irradiator for irradiating an ultraviolet ray as an illuminating device to detect a dark defect such as black or a foreign substance, and irradiates the inspection object with the ultraviolet ray. The test object itself emits visible light (fluorescence) having a longer wavelength than ultraviolet light. Visible light emitted from the inside illuminates the entire granular test object and makes it almost uniform, so that there is no shadow at the end face as when illuminated from the bottom, and images other than real defects are taken Instead, only the defect can be reliably detected.

Since many resin materials emit fluorescence when irradiated with ultraviolet light, visible light can be generated from the inside by irradiating ultraviolet light, and this can be used as illumination for an imaging device. However, this does not prevent the defect inspection apparatus of the present invention from being provided with a visible light illuminating device that illuminates the inspection object from outside externally.

A plate for placing and inspecting the object to be inspected in the inspecting section can be also used as a 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 visible light is disposed below the belt 3, and illuminates the inspection object S on the belt through the belt 3 from below. An ultraviolet irradiator 5 for generating ultraviolet light is installed above the belt 3, and irradiates the inspection object S with ultraviolet light from above. Since the resin pellet has a property of emitting fluorescence with many materials, the inspection object S irradiated with ultraviolet light generates fluorescence that is visible light inside, and is illuminated from the inside by the light. .

In the illustrated example, both the lower illuminator 4 and the ultraviolet irradiator 5 guide light generated by a light source lamp installed in another place (not shown) by an optical fiber. Are formed in a 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. At this time, since there is a space in the center of the ring-shaped ultraviolet irradiator 5, it does not hinder imaging. 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.

[0017]

According to the defect inspection apparatus of the present invention, since the inspection object itself emits light by irradiating ultraviolet rays in addition to ordinary illumination, a shadow may be generated as in the case where illumination light is applied from the outside. No shadow is mistaken for a colored part. 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.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hopper 2 ... Inspection part 3 ... Conveyor belt 4 ... Lower illuminator 5 ... Ultraviolet irradiation device 6 ... Imaging device 7 ... Image processing device 8 ... Defective product removal device 9 ... Defective product collection box 10 ... Good product collection box S ... Cover 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 ultraviolet irradiator for irradiating the inspection object with ultraviolet rays.