KR20020015081A - Automatized defect inspection system and defect inspection method - Google Patents

Abstract

PURPOSE: An automated defect test apparatus and method is provided to obtain clear images of objects by eliminating shadows caused due to the influence of reflected light and dead angle. CONSTITUTION: An automated defect test apparatus comprises a first illumination device(310) and a second illumination device(320) for radiating light onto an object(340) to be tested; a pick-up unit(330) for receiving the light radiated from the first or second illumination device to the object to be tested, and reflected from the object, and obtaining image for the object; and an image analysis unit for comparing the image of the object obtained by the pick-up unit, with a reference image. The first illumination device includes a light source, and a curved reflecting mirror(313) disposed in such a manner that the light emitted from the light source is reflected toward the direction of the object, and the pick-up unit receives the light reflected from the object to be tested.

Description

Automated defect inspection system and defect inspection method

The present invention relates to an automated defect inspection apparatus and a defect inspection method.

In the production process of all products, defect inspection process is performed to evaluate the completeness of the finished product after the manufacturing process. In this case, the defects may be referred to collectively as all the factors that hinder the characteristics of the product, there may be a defect of various sizes ranging from very small invisible to the naked eye can be seen with the naked eye.

Inspection of the appearance defect of a relatively large object is usually performed by randomly extracting a sample and inspecting the product with the naked eye, and a small object may also be inspected by a microscope or the like. However, in this case, since it is impossible to inspect all the produced products and subjective inspection by visual observation of the worker, objective product inspection is difficult.

In order to solve this problem, an inspection system that automates the inspection process is used, which is a standard that is pre-inputted through image analysis software to obtain an image of a product obtained through a CCD (charge-coupled device) camera. By comparing and analyzing the images and making scientific decisions, the objective is to automate objective inspection and quality control.

Such automated inspection equipment can be broadly classified into optical systems, image analysis systems, and machine control systems. The optical system illuminates the area to be measured and acquires the reflected image and transmits it to the image analysis system.The image analysis system converts the analog signal of the transmitted image into a digital signal and compares and analyzes it with the standard image inputted in advance. In this case, the defects are classified by grade and the result is output. The machine control system directly classifies defective products by type and grade according to the image analysis results.

Lighting apparatuses used to obtain an image of an object to be inspected in the conventional defect inspection apparatus of the prior art include a back lighting apparatus, an upper lighting apparatus, a side lighting apparatus, and the like, and their schematic structures are shown in FIGS. 1A to 1C, respectively. Is shown.

As shown in FIG. 1A, the backside illumination device 111 irradiates light toward the inspection object 140 from the opposite side of the imaging device 130 when viewed based on the inspection object 140. When the back lighting device 111 is used, uniform light is irradiated to the entire object 140 to be inspected, but since the light is irradiated to the rear surface of the object 140 to be inspected, surface defects of the object cannot be inspected. Therefore, the back lighting device 111 is mainly used for the inspection of the outline and the measurement of the center point, it is used to inspect a transparent object such as a transparent film or a lens.

Since the upper lighting device 112 as shown in FIG. 1B irradiates light to the inspection object 140 from the upper side of the inspection object, it is advantageous for surface inspection. However, in the case of the upper lighting device 112, unlike the case of the back lighting device, since the lighting device 112 is positioned between the imaging device 130 and the object to be inspected 140, the imaging device 130 is to be inspected. In order to allow imaging of the object 140, an opening 122 for the imaging device 130 is formed in the center of the lighting device 112. However, when the inspection object 140 is a coated object, a large amount of light is reflected from the inspection object 140 to reflect the reflected light through the opening 122 of the lighting device 112. Facing toward the surface, there is a limit to surface inspection. In addition, because of the opening 122, it is difficult to obtain uniform illumination of the object to be inspected 140, and part of the light emitted from the lighting device 112 is incident at an inclined angle with respect to the object to be inspected 140. The shadow phenomenon occurs. Shadowing makes it difficult to inspect defects of an object having a certain thickness or more, and this problem is more prominent, especially in an object having an opening.

To facilitate inspection of the coated object, a side lighting device 113 as shown in FIG. 1C is used. In the case of the side lighting device 113, since the light is incident at a substantially inclined angle with respect to the object 140 to be inspected, the reflected light does not enter the imaging device 130 but is directed toward the outside of the opening 123 to influence the reflected light. Can be reduced. However, the shadow phenomenon as seen in the top lighting device is more severe in the side lighting device 113. Therefore, the side lighting device 113 is difficult to use in the defect inspection equipment for inspecting an object having a thickness of a certain degree or more.

SUMMARY OF THE INVENTION The present invention has been conceived to solve such problems, and an object of the present invention is to provide an automated defect inspection apparatus and a defect inspection method capable of eliminating shadow effects due to reflected light and blind spots.

It is another object of the present invention to provide an automated defect inspection apparatus and a defect inspection method which enable defect inspection on an object to be inspected coated with a surface having a predetermined thickness or more.

1A, 1B and 1C are schematic diagrams showing a back lighting device, an upper lighting device and a side lighting device according to the prior art, respectively.

Figure 2 is a schematic diagram showing the overall structure of the automated defect inspection apparatus according to the first embodiment of the present invention.

3 shows the structure of a lighting device according to a first embodiment of the present invention.

4A and 4B show regions of the inspection object to be imaged using respective parts of the lighting apparatus of FIG. 3.

FIG. 5 illustrates another type of inspection object that may inspect a defect using an automated defect inspection apparatus according to a second exemplary embodiment of the present invention.

6 shows the structure of a lighting device according to a second embodiment of the present invention.

7 shows the structure of a lighting device according to a third embodiment of the present invention.

The automated defect inspection apparatus of the present invention for solving such a problem is irradiated to the inspection object from the first and second illumination devices, the first or second illumination device that can irradiate light to the inspection object, the inspection object Imaging means for receiving light reflected from an object to obtain an image of at least a portion of the object to be inspected, and image analysis means for comparatively analyzing an image of the object to be inspected obtained by the imaging means with a standard image .

The first illumination device may include a curved reflector having a light source and an opening arranged to reflect light from the light source in the direction of the object to be inspected and having an opening configured to receive light reflected from the object to be inspected. The second lighting device may include a light source capable of irradiating light at an inclined angle with respect to the object to be inspected.

On the other hand, the image of the inspection object obtained by the imaging means is irradiated from the first illumination device to the inspection object and receives the light reflected from the inspection object, the first image obtained by the imaging means and from the second illumination device And a second image obtained by the imaging means by receiving light reflected from the inspection object and reflected from the inspection object, wherein the image analysis means combines the first and second images obtained by the imaging means. A third image of the entire object to be inspected is formed, and the first and second images corresponding to the areas of the object to be inspected are compared or analyzed with the standard images, or the standard images are obtained as the first and second images. And a standard image, and the image analyzing means may compare and analyze the first image with the first standard image, and compare and analyze the second image with the second standard image.

The apparatus may further include a third lighting device which is disposed in a direction opposite to the image pickup means with respect to the inspection object, and which is capable of irradiating light to the inspection object.

Another automated defect inspection apparatus according to the present invention, a plurality of lighting devices capable of irradiating light to the object to be inspected, the light to be irradiated to the object to be inspected from the plurality of illumination devices reflected from the object to be inspected And imaging means capable of acquiring an image of at least a portion of the image, and image analyzing means capable of comparing and analyzing an image of the object to be inspected obtained by the imaging means with a standard image.

The defect inspection method according to the present invention comprises the steps of acquiring an image of a first area of an object to be inspected by the image pickup means by irradiating the object to be inspected using the first lighting device and receiving light reflected from the object to be inspected; 2, the image pickup means receives the light reflected from the object under inspection by using an illumination device to acquire an image of the second region of the object under examination, the image of the first region and the image of the second region And forming an image of the entire object to be inspected, and comparing and analyzing the image of the object to be examined with the standard image.

According to another aspect of the present invention, there is provided a method for inspecting defects by irradiating an object to be inspected by using a first lighting device and acquiring light reflected from the object to be examined to obtain an image of the first region of the object to be inspected; The image pickup means receives the light reflected from the object to be inspected by using the second lighting device and acquires an image of the second area of the object to be inspected. The method may include comparing and analyzing the standard image with the standard image of the second region.

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Figure 2 is a schematic diagram showing the overall configuration of the automated defect inspection apparatus according to the first embodiment of the present invention.

The automated defect inspection apparatus 200 according to the first embodiment of the present invention may be largely divided into the measurement optical system 230 and the image analysis system 240. The measuring optical system 230 includes an image capturing unit 233 including a CCD camera and lighting units 231 and 232 divided into two upper and lower parts. The measuring optical system 230 obtains an image reflected by illuminating an area to be measured and an image analyzing system ( 240). That is, the inspection object 220 is sequentially moved through the belt 210 to pass through a predetermined position under the measurement optical system 230, and at this time, the image of the inspection object 220 is captured by the measurement optical system 230. Obtained. The image analyzer 240 includes an image processing processor 241, a memory device 242, a display unit 243, and the like, which converts an analog signal of an image transmitted from the measurement optical system 230 into a digital signal and is input in advance. The result is displayed on the display unit 243 by comparing and analyzing the standard image and classifying defects by type and grade. In addition, although not shown in the drawings, the results may be used to directly classify defective products by type and grade.

3 shows an example of an illumination device used in an automated inspection device according to a first embodiment of the present invention.

The lighting device of the first embodiment of the present invention is divided into two parts, the first lighting device 310 and the second lighting device 320, as shown in FIG.

The upper first lighting device 310 is a support 317, a plurality of light emitting diodes 312 attached to the inside of the support 317, and an opening 314 attached to the top of the support 317. Is formed and consists of a curved reflector 313 which reflects light emitted from the light emitting diode 312. Light emitted from each light emitting diode 312 of the first lighting device 310 is reflected by the curved reflector 313 to irradiate the object to be inspected 340.

When the first lighting device 310 of the first embodiment of the present invention is used, the light that is directed to the inspection object 340 is not directly irradiated from the light emitting diode 312 to the inspection object 340, but the curved reflector 313 By reflecting toward the object 340 to be irradiated by (), it is possible to obtain uniform illumination despite the presence of the opening 314, the type (concave, convex) and curvature of the curved reflector 313, the light emitting diode 312 ), The angle of inclination of the light can be adjusted by appropriately adjusting parameters such as the distance between the curved reflector 313, the direction in which the light emitting diode 312 is disposed, and the distance between the curved reflector 313 and the object 340 to be inspected. In addition, even when the inspection target object 340 has a thickness of a certain degree or more, the shadow effect may be prevented from appearing, and an accurate image may be obtained even when the inspection target object 340 has a groove or an opening.

On the other hand, the lower second lighting device 320 is composed of a support 327 and a plurality of light emitting diodes 322 attached to the inner surface of the support 327. The second lighting device also has an opening 324 for allowing the imaging unit 330 to image the inspection object.

With the second lighting device 320 of the first embodiment of the present invention, the light from the light emitting diode 322 attached to the inner side of the support 327 is at an inclined angle with respect to the object 340 to be inspected. Since the incident light is reflected from the object 340 to be directed toward the outside of the opening 324 instead of entering the opening 324 toward the imaging unit 330, the surface of the object 340 is coated and irradiated. Even when a lot of light is reflected, an accurate image of the object to be inspected 340 may be obtained.

Now, a process of performing defect inspection using such an automated defect inspection apparatus will be described in detail with reference to FIGS. 3 and 4A and 4B. 4A and 4B show regions of the inspection object to be imaged using the first and second lighting devices 310 and 320 of FIG. 3, respectively.

In the automated defect inspection apparatus of the first embodiment of the present invention, the first and second illumination devices 310 and 320 constituting the illumination unit sequentially irradiate the same inspection object 340, respectively.

That is, first, the inspection object 340 is irradiated using the upper first lighting device 310 to obtain an image of a portion of the outline side of the inspection object 340. For example, in the case of a test object having an annular coated surface as shown in FIG. 4A, the image obtained by the first irradiation by the first lighting device 310 is an image of a boundary portion of the test object. . That is, as shown in FIG. 4A, the outer peripheral portion of the annular inspection object and the annular center opening are formed. Since the first lighting device 310 uses the light reflected by the curved reflector 313, the shadow effect does not appear even when the object 340 has a thickness greater than or equal to a certain level, and the groove is formed on the object 340. Even when there is an opening or the like, an accurate image can be obtained, so that an accurate image can be obtained for an area around an outline of an object to be inspected having a certain thickness.

Next, the same inspection object is irradiated using the second lighting device 320 below, and this time, the image of the remaining part is obtained except for the portion obtained by using the first lighting device 310. That is, as shown in FIG. 4B, an image of the center portion excluding the outline portion of the object to be inspected is obtained through imaging using the second lighting device 320. Since the second lighting device 320 is hardly affected by the reflected light as described above, even when the surface of the object to be inspected is coated, an accurate image of the surface of the object to be inspected can be obtained.

Now, the images obtained by two sequential imaging are sent to the image analyzer and combined into one to form the image of the whole object to be inspected.The image analyzer compares and analyzes the images with the standard images, classifies defects by type and grade. The results are displayed via the display. Alternatively, the defect inspection may be performed by comparing the images of the respective portions obtained through the respective imaging with the standard images of the corresponding portions, without combining the images obtained by the two imaging as described above.

The portion of the image obtained by using the first lighting device and the second lighting device may vary according to the shape or characteristics of the object to be inspected. That is, the same object may be imaged two or more times by using an illumination device that divides the area of the object to be inspected according to the shape and surface characteristics of the object to be inspected and obtains an optimal image for each area. It is also possible to combine two or more lighting devices.

Meanwhile, in the first embodiment of the present invention, the first lighting device including the curved reflector is installed on the upper side, and the second lighting device is provided on the inner side of the support on the lower side. The location may vary.

If necessary, three or more lighting devices may be used. For example, to inspect the object to be tiled as shown in FIG. 5, it is preferable to use an upper lighting device and two inclined lighting devices as shown in FIG. 6.

FIG. 5 illustrates another type of inspection target object capable of inspecting a defect using an automated defect inspection apparatus according to a second exemplary embodiment of the present invention, and FIG. 6 illustrates inspection of a defect of the inspection target object as shown in FIG. 5. A lighting device according to a second embodiment of the present invention is shown. Except for the lighting apparatus of the automated defect inspection apparatus according to the second embodiment of the present invention, the structure is similar to that of the automated defect inspection apparatus according to the first embodiment of the present invention.

The illumination device of FIG. 6 includes an upper illumination device 610 for inspecting the curved surface of the center portion of the inspection object 640 and two inclination illumination devices for inspecting both edge portions of the inspection object 640 ( 620, 630). The upper lighting device 610 is configured using a curved reflector and a light emitting diode similarly to the first lighting device of the first embodiment of the present invention, and the two inclined lighting devices 620 and 630 are the upper surface of the support and the inside of the support. It consists of a number of light emitting diodes provided in the. The angle and distance between the inclined illumination devices 620 and 630 and the inspection object 640 are determined according to the size or curvature of the inspection object 640.

In order to inspect the defect of the tile-shaped inspection object 640 as shown in FIG. 5, first, the inspection object 640 is irradiated using the upper lighting device 610 to inspect the tile-shaped inspection object 640. Obtain an image of a curved surface in the middle of the. Next, the inspection object 640 is irradiated using the two tilt lighting devices 620 and 630 to obtain images of both edge portions of the inspection object 640 having a tile shape.

The image thus obtained is transmitted to an image analyzer for comparison and analysis in a similar manner as in the first embodiment.

On the other hand, when the image of each area is obtained by using the upper lighting device 610 and the inclined lighting device 620 in turn, since the imaging is required twice for each object to be inspected, the inspection time is long. The disadvantage is that it takes. Therefore, if necessary, three illumination devices 610, 620, and 630 may be simultaneously irradiated with the inspection object 640, and the image of the entire inspection object 640 may be obtained and compared and analyzed by one imaging. have.

In addition, in the second embodiment of the present invention, although the reflective lighting device using the curved reflector is used as the upper lighting device, a normal lighting device that does not use the curved reflector may be used depending on the surface state of the object to be inspected. Also, depending on the shape of the object to be inspected, two or more inclination lighting devices may be used, or only the inclination lighting device may be used without using the upper lighting device.

However, when illuminating the object to be inspected with multiple lighting devices at the same time, it is preferable to arrange each lighting device so that interference between the lighting devices is minimal.

The back lighting device may be used in combination with the lighting device of the first embodiment of the present invention. Back lighting devices are typically used for close inspection of outlines. FIG. 7 illustrates a third embodiment of the present invention in which a rear lighting device is installed in the lighting device of FIG. 3.

As shown in FIG. 7, the back illumination device 750 is installed on the opposite side of the imaging unit when viewed based on the inspection object. The back lighting device 750 includes a support 757 and a plurality of light emitting diodes 752. If necessary, the back lighting device 750 may be formed in a structure including a light emitting diode and a curved reflector similarly to the first lighting device, or may be formed to have a light emitting diode on the inner side of the support similar to the second lighting device. It may be appropriately selected according to the shape or surface condition of the object to be inspected. When the back lighting device 750 is used, the inspection target area of the object to be inspected is divided into three parts, respectively, which are captured by the first lighting device 310, the second lighting device 320, and the back lighting device 750, and compared. Is analyzed.

However, the back lighting device 750 is not used separately to obtain an image of a specific portion of the object to be inspected, but is used together with the first or second lighting devices 310 and 320 in FIGS. 4A and 4B. It can also be used as an auxiliary light to obtain an image of the displayed area.

Although the present invention has been described in detail with reference to preferred embodiments, this embodiment has been presented for the purpose of understanding the present invention, and the scope of the present invention is not limited to this embodiment. It will be understood by those skilled in the art that various modifications can be made without departing from the scope of the technical idea of the present invention, and the scope of the present invention should be interpreted by the appended claims.

In the automated defect inspection apparatus according to the present invention, by using two or more lighting devices that irradiate light to the object to be inspected in different ways, an image of a different part of the object to be inspected is obtained, whereby the object to be inspected has a certain degree or more. Conventional defect inspection devices, such as having a thickness or a coated surface, provide a clear image of the objects to be inspected, which are difficult to accurately inspect defects, and thus satisfactory defect inspection can be performed even on such objects. have.

Claims (10)

First and second lighting devices capable of irradiating light to the object to be inspected, Imaging means for receiving light reflected from the first or second illumination device to the inspection object and reflected from the inspection object to obtain an image of at least a portion of the inspection object; And an image analyzing means capable of comparing and analyzing an image of the object to be inspected obtained by the imaging means with a standard image. The method of claim 1, The first lighting device, With a light source, Automated defect inspection comprising a curved reflector arranged to reflect light from the light source in the direction of the object to be inspected and having an opening formed to allow the imaging means to receive light reflected from the object to be inspected Device. The method of claim 1, The second lighting device, Automated defect inspection apparatus including a light source for irradiating light at an inclined angle with respect to the inspection object. The method of claim 1, The image of the inspection object obtained by the imaging means, A first image obtained by the imaging means by receiving light reflected from the first object from the first illumination device and reflected from the object; And a second image obtained by the imaging means by receiving light reflected from the second object to be examined by the second illumination device and reflected from the object to be inspected. The method of claim 4, wherein The image analyzing means may combine the first and second images acquired by the imaging means to form a third image of the entire object to be inspected, and compare and analyze the formed third image with a standard image. Automated defect inspection device. The method of claim 4, wherein The standard image includes first and second standard images corresponding to areas of the object to be inspected acquired as the first and second images. And the image analyzing means compares and analyzes the first image with the first standard image and compares the second image with the second standard image. The method of claim 1, And a third lighting device disposed in a direction opposite to the image pickup means with respect to the inspection object, and configured to irradiate light to the inspection object. Multiple lighting devices capable of irradiating light onto the object under inspection, Imaging means capable of receiving light reflected from the plurality of illumination devices to the inspection object and reflecting light from the inspection object to obtain an image of at least a portion of the inspection object; And an image analyzing means capable of comparing and analyzing an image of the object to be inspected obtained by the imaging means with a standard image. Irradiating an object to be inspected by using a first lighting device and receiving light reflected from the object to be examined to acquire an image of the first area of the object to be inspected; Irradiating the object to be inspected using a second lighting device to receive the light reflected from the object to be examined and obtaining the image of the second area of the object to be inspected by the imaging means; Combining the image of the first region with the image of the second region to form an image of the entire object to be inspected; And comparing and analyzing the image of the object to be examined with a standard image. Irradiating an object to be inspected by using a first lighting device and receiving light reflected from the object to be examined to acquire an image of the first area of the object to be inspected; Irradiating the object to be inspected using a second lighting device to receive the light reflected from the object to be examined and obtaining the image of the second area of the object to be inspected by the imaging means; Comparing and analyzing the image of the first region with the standard image of the first region, And comparing and analyzing the image of the second area with the standard image of the second area.