KR20180136421A - System and method for defect detection - Google Patents

Abstract

Disclosed are a system and a method for detecting a defect. An object of the present invention is to provide the system for detecting the defect in which detection power against defects (for example, scratch defects) on an inspection target which is difficult to transmit light is improved. The system for detecting the defect according to one embodiment of the present invention is a system for detecting the defect on an inspection target having a lower light transmittance than a light reflectance, and comprises: a light source for irradiating the inspection target with light; a light blocking mask disposed between the light source and the inspection target; and an imaging instrument which receives the light reflected from the inspection target and captures an image of the inspection target.

Description

[0001] SYSTEM AND METHOD FOR DEFECT DETECTION [0002]

The present invention relates to a system and method for detecting defects in an object to be inspected.

Recently, as an image analysis technique has been developed, an optical inspection method for detecting whether or not a product is defective by capturing an image of the appearance of a product in an image-capturing device such as a camera during the manufacturing process of the product or after the manufacture is completed, . In general, in this inspection method, a light source for illuminating the product for imaging is disposed.

The optical inspection can be classified into a transmission optical system inspection and a reflection optical system inspection depending on how a light source and an image pickup apparatus are arranged based on an inspection object (for example, a polarizing film, an optical film, a display panel, a touch panel, a printed circuit board, and the like). Korean Patent Laid-Open Publication No. 2009-0113885 discloses an illumination system that can be used for inspection by a camera. Such an illumination system is suitable for inspection of a transmission optical system. However, when the inspection object has a light transmittance lower than the light reflectance, or when the inspection object is conveyed on an opaque conveyer belt without slits, it is difficult to apply the transmission optical system inspection. On the other hand, an optical system such as regular reflection, boundary reflection, or coaxial reflection can be used to detect defects on the inspection target object through which light is not transmitted, but this inspection method does not properly detect some kinds of defects (for example, scratch defects) There is a problem. Therefore, a technique for more accurately detecting such defects with a given imaging device in a reflection optical system inspection is required.

Korean Patent Publication No. 2009-0113885

An object of the present invention is to provide a defect detection system with improved detection capability for defects (for example, scratch defects) on an inspection object which are difficult to transmit light.

It is an object of the present invention to provide such a defect detection method.

1. A system for detecting defects on a test object having a light transmittance lower than a light reflectance,

A light source for irradiating the inspection object with light;

A light blocking mask disposed between the light source and the inspection object; And

And an imaging device that receives the light reflected from the inspection target and captures an image of the inspection target.

2. The system of claim 1, further comprising a condenser lens disposed between the light source and the light blocking mask.

3. The defect detection system as in 1 above, wherein said inspection object comprises an ITO layer.

4. The defect detection system according to claim 3, wherein an angle of irradiation of the light with respect to the surface of the inspection object is 30 to 60 degrees, and an imaging angle of the imaging device with respect to the surface is 30 to 60 degrees.

5. The defect detection system according to claim 1, further comprising a defect detector for detecting a defect on the inspection object from the image.

6. The defect detection system of claim 5, wherein the defect is a scratch defect.

7. The defect detection system of 1 above, wherein said light source is an LED light source.

8. A method for detecting defects on an inspection object having a light transmittance lower than a light reflectance,

Providing a light source for irradiating the inspection object with light;

Disposing a light blocking mask between the light source and the inspection object; And

And acquiring an image of the inspection object using an imaging device that receives the light reflected by the inspection object.

9. The method of claim 8, further comprising disposing a condenser lens between the light source and the light blocking mask.

10. The defect detection method according to claim 8, wherein the inspection object includes an ITO layer.

11. The defect detection method according to claim 10, wherein an angle of irradiation of the light with respect to the surface of the inspection object is 30 to 60 degrees, and an imaging angle of the imaging device with respect to the surface is 30 to 60 degrees.

12. The defect detection method according to claim 8, further comprising detecting a defect on the inspection object from the image.

13. The method of claim 12, wherein the defect is a scratch defect.

14. The method of claim 8, wherein the light source is an LED light source.

The defect detection system and method according to the present invention can maximize the performance of the reflection optical system inspection for detecting defects (for example, scratch defects) on the inspection object that are difficult to transmit light.

1 is a diagram illustrating a defect detection system according to an embodiment of the present invention.
2 is a view for explaining that light from a light source is scattered by a light blocking mask in a defect detection system according to an embodiment of the present invention.
FIG. 3 is a view for explaining a result of detecting defects of an inspection object using a defect detection system according to an embodiment of the present invention.
FIGS. 4 to 6 are diagrams for explaining a result of detecting defects in an inspection object while adjusting the width of a light blocking mask, the distance between the inspection object and the light source, and the amount of light from the light source in the defect detection system according to an embodiment of the present invention. FIG.
FIG. 7 is a view for explaining a result of detecting defects of an inspection object while adjusting a light irradiation angle and an imaging angle in a defect detection system according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, this is merely an example and the present invention is not limited thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention or custom of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

A defect detection system according to an embodiment of the present invention is a system for detecting defects on an inspection object (for example, an opaque material) having a lower light transmittance than a light reflectance, comprising: a light source for irradiating light to the inspection object; A light blocking mask disposed between the light source and the inspection object; And an imaging device for receiving the light reflected from the inspection object and capturing an image of the inspection object, wherein the imaging optical system includes a reflection optical system inspection unit for detecting defects (e.g., scratch defects) on the inspection target object, Performance can be maximized.

1 is a diagram illustrating a defect detection system according to an embodiment of the present invention. 1 is a side view of the defect detection system 100 in the width direction of the inspection object 150. As shown in FIG.

The defect detection system 100 of FIG. 1 is suitable for inspecting an inspection object 150 to detect defects on the inspection object 150. For example, in FIG. 1, the defect detection system 100 may inspect the test object 150 while moving the test object 150 (e.g., to the right using a conveying means such as an opaque conveyor belt). When the optical reflectance of the inspection object 150 is larger than the light transmittance of the inspection object 150 (for example, when the inspection object 150 is an opaque material), the inspection of the reflection optical system using the defect detection system 100 is performed It will enable more accurate defect detection than optical system inspection. For example, the inspection object 150 may be a substrate including an ITO (Indium Tin Oxide) layer.

As shown in FIG. 1, the defect detection system 100 includes a light source 110, a light blocking mask 120, and an imaging device 130. In addition, the defect detection system 100 may further include a condenser lens 140.

The light source 110 is configured to irradiate the inspection object 150 with light. Therefore, for imaging of the imaging device 130, the defect detection system 100 can illuminate the test object 150 using the light source 110. [ For example, the defect detection system 100 may further include a control unit (not shown), which may cause the light source 110 to provide light to the test object 150. In some embodiments, such a controller may be a user suitable for receiving user input for controlling the light source 110, such as adjusting the light amount of the light source 110, adjusting the light irradiation angle of the light source 110, Interface.

The light source used in the optical inspection in the related art can be used as the light source 110 without any particular limitation. For example, a halogen lamp such as an LED lamp (Light Emitting Diode Lamp), a metal halide lamp, a fluorescent lamp, an incandescent lamp, or the like can be used as the light source 110. The type of light emitted from the light source 110 is not particularly limited, and examples thereof include white light, green light, blue light, red light, infrared light, and a suitable combination thereof. Further, the light source 110 may have a longer side or a shorter side than the width of the sheet-like product, or a side having a length equal to or longer than the width of the sheet-like product. On the other hand, the time period during which light is irradiated from the light source 110 can be adjusted according to the conveyance speed of the inspection object 150.

According to some embodiments, a condenser lens 140 for collecting light emitted from the light source 110 may be used. The condenser lens 140 is disposed between the light source 110 and the light blocking mask 120. Optical characteristics such as the shape, material, and focal length of the condenser lens 140 can be appropriately selected, and are not particularly limited.

As shown in FIG. 1, the light blocking mask 120 is disposed between the light source 110 and the inspection object 150. The type and form of the light blocking mask 120 are not particularly limited as long as they are suitable for blocking a part of the light emitted from the light source 110. For example, the light blocking mask 120 may be a black slot of appropriate width.

2 is a view for explaining that light from a light source is scattered by a light blocking mask in a defect detection system according to an embodiment of the present invention.

2, the light blocking mask 120 blocks the straight light 210 incident on the light blocking mask 120 via the condenser lens 140. [ Light scattering 220 occurs on both sides of the light blocking mask 120 in the width direction. The scattered light (cross beam) 230 on both sides of the condenser lens 140 travels toward the inspection object 150. Accordingly, the arm portion 250 may be formed between the light blocking mask 120 and the inspection object 150.

As described above, visibility of defects (e.g., scratch defects) on the inspection object 150 can be improved due to light scattering. Since the incident light of the inspection object 150 is refracted due to defects on the inspection target object 150, the possibility that the light reaches the imaging device 130 can be increased by introducing the scattered light into the inspection object 150 to be.

The imaging device 130 is configured to receive light reflected by the inspection object 150 and capture an image of the inspection object 150. Therefore, the defect detection system 100 can acquire an image of the inspection object 150 using the image pickup device 130. [ For example, the control unit of the defect detection system 100 may cause the image capturing apparatus 130 to capture an image of the inspection target object 150 and acquire an image of the inspection target object 150. In some embodiments, the upper control may provide a user interface suitable for receiving user input for controlling the imaging device 130, such as adjusting the imaging time and / or the imaging angle of the imaging device 130 have.

The imaging device 130 is capable of receiving light reflected from the inspection object 150 and capturing an image of the inspection object 150, and the kind thereof is not particularly limited. For example, the imaging device 130 may include a camera (e.g., a CCD (Charge-Coupled Device) camera), a light sensor, or the like.

Furthermore, the defect detection system 100 may further include a defect detection unit 160. [ The defect detecting unit 160 detects a defect in the inspection target object 150 by analyzing the image acquired by the imaging device 130 through the imaging of the inspection target object 150. [ For example, the defect detector 160 may calculate a gray level value of the acquired image, and compare the calculated gray level value with a preset threshold value to detect defects in the inspection target object 150. [ The defect detection unit 160 may be implemented in a computing device including various hardware modules and software modules.

According to another embodiment of the present invention, there is provided a method for detecting a defect on an inspection object having a light transmittance lower than a light reflectance, the method comprising: providing a light source for irradiating light to the inspection object; Disposing a light blocking mask between the light source and the inspection object; And acquiring an image of the inspection object using an imaging device that receives the light reflected from the inspection object.

FIG. 3 is a view for explaining a result of detecting defects of an inspection object using a defect detection system according to an embodiment of the present invention.

For comparison, when a light blocking mask is disposed between the object to be inspected and the light source and a condensing lens is disposed between the light source and the light blocking mask as shown in Fig. 1, the image 320 obtained by picking up an inspection object by the imaging device, And an image 310 in which the imaging device has taken an image of the object to be inspected is shown in Fig.

A touch panel (including an ITO layer) having scratch defects was used as a test object. In addition, a green LED having an illuminance of 900,000 lux measured at a distance of 70 mm from the illuminating surface is used as a light source, and light is irradiated to the illuminating object at a distance of 70 mm from the illuminating illuminating object, Irradiation angle. The illuminance difference in the width direction in the light irradiation area of the test object was not separately measured.

As a light shielding mask, a 6 mm wide black coated heat-resistant agent (because the light was hot) was used as a slit, and a glass-type condensing lens was used as the condensing lens. The light blocking mask and the condenser lens were spaced 1 to 2 mm apart, and the condenser lens and the light source were not spaced apart.

An imaging device was installed so as to take an image of the test object at an imaging angle of 45 DEG with respect to the surface of the test object at a distance of 190 mm from the test object, and then imaging was performed.

As can be seen from the images 310 and 320 shown in FIG. 3, in the reflection optical system inspection in which the imaging device receives the light reflected by the inspection object including the ITO layer and captures the image of the inspection object, By disposing the light shielding mask, a defect caused by the scratch of the inspection target object can be detected more clearly from the image of the inspection target object.

FIGS. 4 to 6 are diagrams for explaining a result of detecting defects in an inspection object while adjusting the width of a light blocking mask, the distance between the inspection object and the light source, and the amount of light from the light source in the defect detection system according to an embodiment of the present invention FIG.

FIG. 4 shows an image of an object to be inspected when the width of the light blocking mask is changed to 18 mm, 15 mm, 12 mm, 9 mm, and 6 mm, respectively, under the same experimental conditions as described above. In Fig. 4, the result value displayed at the bottom of each image represents the total gray level value of the image. As can be seen from FIG. 4, good results were obtained when the width of the light blocking mask was 6 mm to 12 mm, especially when the width was 9 mm.

5 shows an image of a test object when the distance between the test object and the light source is changed to 30 mm, 40 mm, 50 mm, 60 mm, 70 mm and 80 mm, respectively, under the same experimental conditions as described above. 5, the result value displayed at the bottom of each image represents the total gray level value of the image. As can be seen from Fig. 5, good results were obtained when the distance between the object to be inspected and the light source was 40 to 70 mm, particularly when the width was 50 to 70 mm.

6 shows an image of a test object when the light amount of the light source is changed to 50% and 100% of the maximum allowable light amount (900,000 lux) under the same experimental conditions as described above. In Fig. 6, the result value displayed at the bottom of each image represents the total gray level value of the image. As can be seen from Fig. 6, as the light amount increased, good results were obtained.

FIG. 7 is a view for explaining a result of detecting defects of an inspection object while adjusting a light irradiation angle and an imaging angle in a defect detection system according to an embodiment of the present invention.

Referring to FIG. 7, when an angle of light irradiation with respect to the surface of the inspection object is 30 to 60, and an imaging angle of the imaging device with respect to the surface is 30 to 60, an image in which scratch defects are clearly visible is obtained Points can be confirmed.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, . Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by equivalents to the appended claims, as well as the appended claims.

100: Defect Inspection System
110: Light source
120: Light blocking mask
130:
140: condenser lens
118: Memory
150: Inspection object
210: linear light
220, 230: Scattered light
250:

Claims (7)

A system for detecting defects on an inspection object having a lower light transmittance than a light reflectance,
A light source for irradiating the inspection object with light;
A light blocking mask disposed between the light source and the inspection object; And
And an imaging device that receives the light reflected from the inspection target and captures an image of the inspection target,
The width of the light shielding mask is 6 mm to 12 mm, the distance between the inspection object and the light source is 40 mm to 70 mm,
Wherein an irradiation angle of the light with respect to the surface of the inspection object is 30 to 60 degrees and an imaging angle of the imaging device with respect to the surface is 30 to 60 degrees.
The system according to claim 1, further comprising a condenser lens disposed between the light source and the light blocking mask.
The defect detection system according to claim 1, wherein the inspection object includes an ITO layer.
The system according to claim 1, further comprising a defect detecting section for detecting a defect on the inspection target from the image.
5. The fault detection system of claim 4, wherein the defect is a scratch defect.
The fault detection system of claim 1, wherein the light source is an LED light source.
A method for detecting defects on an inspection object having a light transmittance lower than a light reflectance,
Providing a light source for irradiating the inspection object with light;
Disposing a light blocking mask between the light source and the inspection object; And
And acquiring an image of the inspection object using an imaging device that receives the light reflected from the inspection object,
The width of the light shielding mask is 6 mm to 12 mm, the distance between the inspection object and the light source is 40 mm to 70 mm,
Wherein an irradiation angle of the light to the surface of the inspection object is 30 to 60 degrees and an imaging angle of the imaging device to the surface is 30 to 60 degrees.

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