Defect detection method and defect detection system for display panel

Abstract

The invention relates to a defect detection method of a display panel, a to-be-detected display panel comprises a first surface and a second surface which are oppositely arranged, and the defect detection method comprises the following steps: shooting the first surface and the second surface by using a line scanning camera in a dark field environment to obtain a first surface image and a second surface image; shooting the to-be-tested display panel in a bright field environment by using an image capturing camera to obtain a comprehensive image, filtering information of the first surface image and information of the second surface image in the comprehensive image to obtain information inside the to-be-tested display panel, and generating an output image; and judging whether the to-be-detected display panel has defects or not according to the output image. According to the detection method, the image information contained in the first surface image and the second surface image is eliminated, so that the interference of surface foreign matters can be eliminated, and the accuracy of defect detection of the display panel is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of display panel detection, and in particular to a display panel defect detection method and a defect detection system. Background Art

[0002] In the prior art, after the display panel is manufactured, it is usually necessary to perform defect detection on the display panel, among which the optical detection method is widely used as an effective detection method for emerging industrial automation. The optical detection method is based on optical principles and uses high-speed and high-precision visual processing technology to detect defects generated during the display panel manufacturing process. However, the optical detection method in the prior art often finds it difficult to distinguish between foreign matter on the surface of the display panel and actual defects inside the display panel, and it is easy to misjudge foreign matter on the surface of the display panel as foreign matter defects inside the display panel during the detection process, thereby causing misjudgment.

[0003] Therefore, how to accurately distinguish foreign matter on the surface of the display panel from actual defects inside the display panel to avoid misjudgment of the display panel has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In order to solve the above technical problems, an object of the present invention is to provide a defect detection method and a defect detection system for a display panel.

[0005] According to one aspect of the present invention, the present invention provides a display panel defect detection method for performing defect detection on a display panel to be tested, the display panel to be tested comprising a first surface and a second surface arranged opposite to each other, the display panel defect detection method comprising:

[0006] The first surface is photographed by a line scan camera in a dark field environment to obtain a first surface image, wherein the first surface image includes first global information of the first surface; the second surface is photographed by a line scan camera in a dark field environment to obtain a second surface image, wherein the second surface image includes second global information of the second surface; the display panel to be tested is photographed by an imaging camera in a bright field environment to obtain a comprehensive image, wherein the comprehensive image includes third global information of the display panel to be tested;

[0007] filtering out the first global information of the first surface image and the second global information of the second surface image in the integrated image to obtain fourth global information of the display panel to be tested, and generating an output image; and

[0008] It is determined whether the display panel to be tested has defects according to the output image.

[0009] As an optional technical solution, judging whether the display panel to be tested has defects according to the output image includes:

[0010] The output image is compared with a preset defect feature set.

[0011] As an optional technical solution, the defect feature set includes foreign body defects.

[0012] As an optional technical solution, the line scan camera is provided with a first light source, and the illumination of the first light source is lower than a first low threshold value. In a dark field environment, the line scan camera is illuminated and photographed only by the first light source to obtain the first surface image and the second surface image.

[0013] As an optional technical solution, in a bright field environment, the imaging camera is illuminated and photographed by a second external light source to obtain the composite image, and the illumination of the second light source is much higher than the first low threshold value.

[0014] According to another aspect of the present invention, the present invention further provides a display panel defect detection system for performing defect detection on a display panel to be tested, wherein the display panel to be tested includes a first surface and a second surface arranged opposite to each other, and the display panel defect detection system includes:

[0015] A stage, which is used to carry the display panel to be tested;

[0016] A control unit, the control unit comprising a storage unit, an image processing unit and a comparison and judgment unit that are communicatively connected to each other;

[0017] a line scan camera, the line scan camera being communicatively connected to the control unit, the line scan camera being used to photograph the first surface in a dark field environment to obtain a first surface image and photograph the second surface to obtain a second surface image, and transmit the first surface image and the second surface image to the storage unit, the first surface image including first global information of the first surface, and the second surface image including second global information of the second surface; and

[0018] An imaging camera, the imaging camera is used to photograph the display panel to be tested in a bright field environment to obtain a comprehensive image, and transmit the comprehensive image to the storage unit, the comprehensive image including the third global information of the display panel to be tested;

[0019] During detection, the storage unit transmits the first surface image, the second surface image and the integrated image to the image processing unit, and the image processing unit filters out the first global information of the first surface image and the second global information of the second surface image in the integrated image to obtain the fourth global information inside the display panel to be tested, and generates an output image to the comparison and judgment unit, which judges whether the display panel to be tested has defects based on the output image.

[0020] As an optional technical solution, the comparison and judgment unit is preset with a defect feature set, and the comparison and judgment unit compares the output image with the preset defect feature set.

[0021] As an optional technical solution, the defect feature set includes foreign body defects.

[0022] As an optional technical solution, the line scan camera is provided with a first light source, and the illumination of the first light source is lower than a first low threshold value. In a dark field environment, the line scan camera is illuminated and photographed only by the first light source to obtain the first surface image and the second surface image.

[0023] As an optional technical solution, the display panel defect detection system also includes a second light source, the illumination of the second light source is much higher than the first low threshold value, and in a bright field environment, the imaging camera is illuminated and photographed by the second light source to obtain the composite image.

[0024] In summary, in the existing display panel foreign body detection technology, only a comprehensive image is often obtained through an imaging camera, and the surface image of the display panel is not obtained. The comprehensive image will include information about foreign bodies on the surface of the display panel to be tested. Due to the interference of foreign body particles on the surface, qualified products are easily misjudged as defective products. In the present invention, a first surface image and a second surface image containing only the surface information of the display panel are obtained by adding a line scan camera and working in a dark field environment (without an external light source), and then the image information contained in the first surface image and the second surface image is eliminated from the comprehensive image to eliminate the interference of surface foreign bodies, thereby greatly improving the accuracy of display panel defect detection.

[0025] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments, but is not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 FIG. 4 is a schematic diagram of a display panel defect detection system according to an embodiment of the present invention.

[0027] Figure 2 It is a schematic diagram of a first surface image, a second surface image and a comprehensive image of a display panel to be tested according to an embodiment of the present invention.

[0028] Figure 3 FIG. 4 is a schematic diagram of a display panel defect detection system according to another embodiment of the present invention.

[0029] Figure 4 It is a schematic diagram of a first surface image, a second surface image and a comprehensive image of a display panel to be tested according to another embodiment of the present invention.

[0030] Figure 5 FIG. 4 is a structural block diagram of a control unit according to an embodiment of the present invention.

[0031] Figure 6 FIG. 4 is a flow chart of a display panel defect detection method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the technical features, contents and advantages of the present invention and the effects that can be achieved easier to understand, the present invention will be described in detail as follows in conjunction with the accompanying drawings and in the form of embodiments. The drawings used therein are only for illustration and auxiliary description purposes, and may not be the actual proportions and precise configurations after the implementation of the present invention. Therefore, the proportions and configuration relationships of the attached drawings should not be interpreted or limited to the scope of rights of the present invention in actual implementation. This should be stated in advance.

[0033] See also Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 1 FIG. 4 is a schematic diagram of a display panel defect detection system according to an embodiment of the present invention. Figure 2 It is a schematic diagram of a first surface image, a second surface image and a comprehensive image of a display panel to be tested according to an embodiment of the present invention. Figure 3 FIG. 4 is a schematic diagram of a display panel defect detection system according to another embodiment of the present invention. Figure 4 It is a schematic diagram of a first surface image, a second surface image and a comprehensive image of a display panel to be tested according to another embodiment of the present invention. Figure 5 FIG. 4 is a structural block diagram of a control unit according to an embodiment of the present invention. Figure 6 FIG. 4 is a flow chart of a display panel defect detection method according to an embodiment of the present invention.

[0034] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, the defect detection method of the display panel provided by the present invention can be applied to the detection of liquid crystal display panels, organic light-emitting display panels, inorganic light-emitting display panels, etc. Now, take the liquid crystal display panel as an example for explanation. The display panel to be tested includes an array substrate, a liquid crystal molecule layer and a color filter substrate arranged in sequence, that is, the liquid crystal molecule layer is clamped between the array substrate and the color filter substrate. The display panel to be tested has relative outer surfaces, specifically including an outer surface close to the array substrate side and an outer surface close to the color filter substrate side. When optically inspecting the display panel to be tested, the outer surface close to the array substrate side can be photographed and imaged first, or the outer surface close to the color filter substrate side can be photographed and imaged first. The present invention does not limit the order of imaging.

[0035] In order to clearly explain the method for defect detection of a display panel in the present invention, it is defined that the display panel 20 to be tested includes a first surface 201 and a second surface 202 arranged opposite to each other. In this embodiment, the first surface 201 is an outer surface close to the color filter substrate, and the second surface 202 is an outer surface close to the array substrate; but not limited thereto, in another embodiment, the first surface is an outer surface close to the array substrate, and the second surface is an outer surface close to the color filter substrate.

[0036] like Figure 1 , Figure 2 and Figure 6 As shown, the display panel defect detection method includes:

[0037] Step S101: photographing the first surface 201 of the display panel 20 to be tested in a dark field environment using a line scan camera 30 to obtain a first surface image 701 , wherein the first surface image 701 includes first global information of the first surface 201 ;

[0038] Step S102: photographing the second surface 202 of the display panel 20 to be tested in a dark field environment using the line scan camera 30 to obtain a second surface image 702 , where the second surface image 702 includes second global information of the second surface 202 ;

[0039] Step S103: Using the imaging camera 40 to photograph the display panel 20 to be tested in a bright field environment to obtain a comprehensive image 703, wherein the comprehensive image 703 includes the third global information of the display panel 20 to be tested; it should be noted that the third global information includes the first global information of the first surface image 701, the second global information of the second surface image 702, and the global information inside the display panel 20, etc.; wherein the imaging camera 40 is an area array camera; in actual operation, the order of steps S101 to S103 can be interchanged, and is not limited thereto;

[0040] Step S104: filtering out the first global information of the first surface image 701 and the second global information of the second surface image 702 in the integrated image 703 to obtain fourth global information inside the display panel 20 to be tested, and generating an output image 704; and

[0041] Step S105 : judging whether the display panel 20 to be tested has defects according to the output image 704 .

[0042] It should be noted that both the first surface image 701 and the second surface image 702 are obtained by the line scan camera 30 in a dark field environment. Since the light is weak in a dark field environment, the line scan camera 30 located on the side of the first surface 201 can only capture the light reflected by the corresponding first surface 201 during the shooting process to obtain the image of the corresponding surface, while the state of the interior of the display panel 20 to be tested and the second surface 202 cannot be obtained. Similarly, the line scan camera 30 located on the side of the second surface 202 can only capture the light reflected by the corresponding second surface 202 during the shooting process to obtain the image of the corresponding surface, while the state of the interior of the display panel 20 to be tested and the first surface 201 cannot be obtained. In addition, in the present embodiment, a line scan camera 30 is respectively arranged on the upper and lower sides of the display panel 20 to be tested, and the two line scan cameras 30 can respectively capture the first surface 201 of the display panel 20 to be tested to obtain the first surface image 701 and the second surface 202 of the display panel 20 to be tested to obtain the second surface image 702. However, in other embodiments, this is not limited to the above. In another embodiment, a line scan camera 30 may first photograph the first surface 201 of the display panel 20 to be tested to obtain a first surface image 701, and then the line scan camera 30 may be moved to the bottom of the display panel 20 to be tested to photograph the second surface 202 of the display panel 20 to be tested to obtain a second surface image 702.

[0043] The following describes the workflow of the display panel defect detection method of the present invention in conjunction with a specific embodiment. In a specific detection process, for example, a first surface 201 of a display panel 20 to be tested has a first foreign particle 2011, a second surface 202 of the display panel 20 to be tested has a second foreign particle 2021, and the interior of the display panel 20 to be tested has a third foreign particle 2031. For the convenience of explanation, the foreign particles and their images are depicted in exaggerated manner in each figure. Thus, when performing the inspection, in step S101, when the first surface 201 of the display panel 20 to be tested is photographed by the line scan camera 30 in a dark field environment to obtain the first surface image 701, the first global information of the first surface 201 includes relevant information of the first foreign particle 2021 (for example, the size and position of the first foreign particle 2021); and in step S102, when the second surface 202 of the display panel 20 to be tested is photographed by the line scan camera 30 in a dark field environment to obtain the second surface image 702, the second global information of the second surface 202 includes relevant information of the second foreign particle 2021 (for example, the size and position of the second foreign particle 2021); then, in step S103, when the display panel 20 to be tested is photographed by the imaging camera 40 in a bright field environment to obtain the integrated image 703, the third global information of the integrated image 703 includes not only relevant information of the third foreign particle 2031 inside the display panel 20 to be tested , and also includes relevant information of the first foreign particles 2021 attached to the first surface 201 and relevant information of the second foreign particles 2021 attached to the second surface 202; then, in step S104, since the relevant information of the first foreign particles 2021 attached to the first surface 201 and the relevant information of the second foreign particles 2021 attached to the second surface 202 are filtered out in the comprehensive image 703, the output image 704 generated in step S104 will only include relevant information inside the display panel 20 to be tested. Since there are third foreign particles 2031 inside the display panel 20 to be tested, the output image 704 will include relevant information of the third foreign particles 2031; thus, in step S105, it will be determined that there is a defect inside the display panel 20 to be tested, and the defect is that there are foreign matter (third foreign particles 2031) inside the display panel, and then a detailed analysis can be performed in combination with size specifications to determine whether the display panel 20 to be tested is a defective product.

[0044] Please also refer to Figure 3 , Figure 4 and Figure 6In another detection process, the first surface 201 of another display panel 20' to be tested has first foreign particles 2011, the second surface 202 of the display panel 20 to be tested has second foreign particles 2021, and there are no foreign particles inside the display panel 20' to be tested. Thus, when performing the inspection, in step S101, when the first surface 201 of the display panel 20' to be tested is photographed by the line scan camera 30 in a dark field environment to obtain the first surface image 701, the first global information of the first surface 201 includes the relevant information of the first foreign particle 2021 (for example, the size and position of the first foreign particle 2021); and in step S102, when the second surface 202 of the display panel 20' to be tested is photographed by the line scan camera 30 in a dark field environment to obtain the second surface image 702, the second global information of the second surface 202 includes the relevant information of the second foreign particle 2021 (for example, the size and position of the second foreign particle 2021); then, in step S103, when the display panel 20' to be tested is photographed by the imaging camera 40 in a bright field environment to obtain the integrated image 703, the third global information of the integrated image 703 includes not only the relevant information inside the display panel 20 to be tested, but also includes the relevant information of the first foreign particle 2021 attached to the first surface 201 and the relevant information of the second foreign particle 2021 attached to the second surface 202. The output image 704 includes information related to the second foreign particles 2021 on the surface 202 of the display panel 20' to be tested, but since there are no foreign particles inside the display panel 20' to be tested, the relevant information of the third foreign particles 2031 in the aforementioned embodiment does not exist in the comprehensive image 703; then, in step S104, since the relevant information of the first foreign particles 2021 attached to the first surface 201 and the relevant information of the second foreign particles 2021 attached to the second surface 202 are filtered out in the comprehensive image 703, the output image 704 generated in step S104 will only include relevant information inside the display panel 20' to be tested. Since there are no third foreign particles 2031 described in the previous embodiment inside the display panel 20' to be tested, the output image 704 will not include relevant information about the third foreign particles 2031 in the aforementioned embodiment. In this embodiment, the output image 704 is an internal image of a qualified display panel; thus, in step S105, it will be determined that there is no foreign matter defect inside the display panel 20' to be tested, and the display panel 20' to be tested can be determined to be a qualified product.

[0045] It should be noted that in the prior art, in the detection of foreign matter in display panels, only a comprehensive image is often obtained through an imaging camera, and the first surface image 701 and the second surface image 702 mentioned above are not obtained. However, since the comprehensive image will include information about foreign matter existing on the surface of the display panel to be tested, it is usually easy to cause misjudgment due to the interference of foreign particles on the surface. For example, foreign particles attached to the first surface and foreign particles attached to the second surface are mistakenly judged as foreign particles inside the display panel, and the display panel to be tested is determined to be a defective product.

[0046] It is worth mentioning that in the above step S105, when judging whether the display panel 20, 20' to be tested has defects, the output image 704 will be compared with a preset defect feature set, which includes foreign body defects. Of course, the defect feature set may also include, for example, recessed notches and cracks inside the display panel.

[0047] In addition, the dark field environment mentioned in the present invention refers to an environment in which there is no other external light source, and only the first light source (not shown) of the line scan camera 30 is used for illumination, and the illumination of the first light source is lower than the first low threshold value, and the overall environment is relatively dim. Therefore, in the dark field environment, the first surface image 701 obtained by the line scan camera 30 only by the first light source provided by itself and photographing only includes the first surface information of the display panels 20 and 20' to be tested, and the second surface image 702 obtained by the line scan camera 30 only by the first light source provided by itself and photographing only includes the second surface information of the display panels 20 and 20' to be tested. And because only the first light source provided by the line scan camera 30 is used with weak light to ensure successful imaging, and no additional external light source is provided, equipment costs and detection costs can be saved. The bright field environment mentioned in the present invention refers to an environment in which there is an additional external second light source for illumination, and the illumination of the second light source is much higher than the first low threshold value, and the overall environment is relatively bright. Therefore, in a bright field environment, the imaging camera 40 is illuminated by the external second light source 60 and the obtained comprehensive image captured includes the first surface information, the second surface information and the internal information of the display panel 20 , 20 ′ to be tested.

[0048] Please refer to Figure 1 , Figure 2 , Figure 5 and Figure 6The present invention also provides a display panel defect detection system compatible with the above detection method. The display panel defect detection system 1000 includes a stage 10, a line scan camera 30, an imaging camera 40, and a control unit 50. The stage 10 is used to carry the display panel 20 to be tested. In this embodiment, the stage 10 can be a transparent stage 10, but is not limited thereto. In other embodiments, the stage may also be opaque, in which case the opaque stage only contacts the edge of the display panel to be tested; the control unit 50 includes a storage unit 501, an image processing unit 502, and a comparison and judgment unit 503 that are communicatively connected to each other; the line scan camera 30 is communicatively connected to the control unit 50, and the line scan camera 30 is used to photograph the first surface 201 in a dark field environment to obtain a first surface image 701 and to photograph the second surface 202 to obtain a second surface image 702, and transmit the first surface image 701 and the second surface image 702 to the storage unit 501, the first surface image 701 includes first global information of the first surface 201, and the second surface image 702 includes second global information of the second surface 202; the imaging camera 40 is used to photograph the display panel 20 to be tested in a bright field environment to obtain a comprehensive image 704, and transmit the comprehensive image 704 to the storage unit 501, and the comprehensive image 704 includes third global information of the display panel 20 to be tested. In addition, the display panel defect detection system 1000 also includes a second light source 60, the illumination of which is much higher than the aforementioned first low threshold value, so that when the imaging camera 40 photographs the display panel 20 to be tested to obtain a comprehensive image 703, the second light source 30 can provide a bright field environment for the imaging camera 40.

[0049] During the detection, the storage unit 501 transmits the received first surface image 701, second surface image 702 and integrated image 703 to the image processing unit 502. The image processing unit 502 filters out the first global information of the first surface image 701 and the second global information of the second surface image 702 in the integrated image 703 to obtain the fourth global information inside the display panel 20 to be tested, and generates an output image 704 to the comparison and judgment unit 503. The comparison and judgment unit 503 judges whether the display panel 20 to be tested has defects according to the output image 704. In one embodiment, the comparison and judgment unit 503 is preset with a defect feature set, and the comparison and judgment unit 503 compares the output image 704 with the preset defect feature set, and the defect feature set includes foreign matter defects.

[0050] In summary, in the existing display panel foreign body detection technology, only a comprehensive image is often obtained through an imaging camera, and the surface image of the display panel is not obtained. The comprehensive image will include information about foreign bodies on the surface of the display panel to be tested. Due to the interference of foreign body particles on the surface, qualified products are easily misjudged as defective products. In the present invention, a first surface image and a second surface image containing only the surface information of the display panel are obtained by adding a line scan camera and working in a dark field environment (without an external light source), and then the image information contained in the first surface image and the second surface image is eliminated from the comprehensive image to eliminate the interference of surface foreign bodies, thereby greatly improving the accuracy of display panel defect detection.

[0051] The embodiments described above are only for illustrating the technical ideas and features of the present invention, and their purpose is to enable people skilled in the art to understand the contents of the present invention and implement them accordingly. They cannot be used to limit the patent scope of the present invention. That is, all equivalent changes or modifications made according to the spirit disclosed by the present invention should still be included in the patent scope of the present invention.

Claims

1. A method for defect detection of a display panel, for performing defect detection on a display panel to be tested, wherein the display panel to be tested comprises a first surface and a second surface arranged opposite to each other, characterized in that: The defect detection method of the display panel includes: The first surface is photographed by a line scan camera in a dark field environment to obtain a first surface image, wherein the first surface image includes first global information of the first surface; the second surface is photographed by a line scan camera in a dark field environment to obtain a second surface image, wherein the second surface image includes second global information of the second surface; the display panel to be tested is photographed by an imaging camera in a bright field environment to obtain a comprehensive image, wherein the comprehensive image includes third global information of the display panel to be tested; filtering out the first global information of the first surface image and the second global information of the second surface image in the integrated image to obtain fourth global information of the display panel to be tested, and generating an output image; and It is determined whether the display panel to be tested has defects according to the output image.

2. The display panel defect detection method according to claim 1, characterized in that: Judging whether the display panel to be tested has defects according to the output image includes: The output image is compared with a preset defect feature set.

3. The display panel defect detection method according to claim 2, characterized in that: The defect feature set includes foreign body defects.

4. The display panel defect detection method according to claim 1, characterized in that: The line scan camera is provided with a first light source, the illumination of which is lower than a first low threshold value. In a dark field environment, the line scan camera is illuminated and photographed only by the first light source to obtain the first surface image and the second surface image.

5. The display panel defect detection method according to claim 4, characterized in that: In a bright field environment, the imaging camera is illuminated and photographed by a second external light source to obtain the integrated image, and the illumination of the second light source is much higher than the first low threshold value.

6. A display panel defect detection system, used for performing defect detection on a display panel to be tested, the display panel to be tested comprising a first surface and a second surface arranged opposite to each other, characterized in that: The display panel defect detection system includes: A stage, which is used to carry the display panel to be tested; A control unit, the control unit comprising a storage unit, an image processing unit and a comparison and judgment unit that are communicatively connected to each other; a line scan camera, the line scan camera being communicatively connected to the control unit, the line scan camera being used to photograph the first surface in a dark field environment to obtain a first surface image and photograph the second surface to obtain a second surface image, and transmit the first surface image and the second surface image to the storage unit, the first surface image including first global information of the first surface, and the second surface image including second global information of the second surface; and An imaging camera, the imaging camera is used to photograph the display panel to be tested in a bright field environment to obtain a comprehensive image, and transmit the comprehensive image to the storage unit, the comprehensive image including the third global information of the display panel to be tested; During detection, the storage unit transmits the first surface image, the second surface image and the integrated image to the image processing unit, and the image processing unit filters out the first global information of the first surface image and the second global information of the second surface image in the integrated image to obtain the fourth global information inside the display panel to be tested, and generates an output image to the comparison and judgment unit, which judges whether the display panel to be tested has defects based on the output image.

7. The display panel defect detection system according to claim 6, characterized in that: The comparison and judgment unit is preset with a defect feature set, and the comparison and judgment unit compares the output image with the preset defect feature set.

8. The display panel defect detection system according to claim 7, characterized in that: The defect feature set includes foreign body defects.

9. The display panel defect detection system according to claim 6, characterized in that: The line scan camera is provided with a first light source, the illumination of which is lower than a first low threshold value. In a dark field environment, the line scan camera is illuminated and photographed only by the first light source to obtain the first surface image and the second surface image.

10. The display panel defect detection system according to claim 9, characterized in that: The display panel defect detection system also includes a second light source, the illumination of the second light source is much higher than the first low threshold value, and in a bright field environment, the imaging camera is illuminated and photographed by the second light source to obtain the integrated image.

Images