Defect image detection method for film pasting product

Abstract

The invention relates to a defect image detection method for a film product, which comprises the following steps: S1, providing a film product to be detected, the film product comprises a substrate and a transparent release film attached to the surface of the substrate, the transparent release film is composed of a plastic film and a release layer, and the surface layer of the plastic film is coated with a fluorescent agent; s2, visible light is adopted to irradiate the film pasting product, and the film pasting product is shot to obtain a first picture; s3, identifying all appearance defects on the surface of the film pasting product by distinguishing the first picture; s4, irradiating the film product by adopting ultraviolet light to excite the surface of the transparent release film to generate fluorescent light, and shooting the film product for the second time to obtain a second photo imaged by the fluorescent light; and S5, comparing and analyzing the second photo and the first photo to judge whether the identified appearance defect is a film bottom defect or a film surface defect. The method not only can accurately and efficiently judge whether the appearance defect belongs to the film surface defect or the film bottom defect, but also cannot damage the film sticking product, and is beneficial to ensuring the quality of the film sticking product.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a defect image detection method for a film-pasted product. BACKGROUND

[0002] In the manufacturing process of touch screens, displays and other flat panel products, a protective film (usually made of transparent plastic film of PE, PP, PVC or PET material) is usually attached to the surface of the product to protect the surface from scratches, contamination or mechanical damage. Such flat panel products with protective films are generally referred to as film-pasted products.

[0003] For film-pasted products, the surface of the flat panel product body and the surface of the protective film may both have appearance defects (such as damage, dirt), which can be referred to as film bottom defects and film surface defects respectively. Film surface defects are damage, dirt or scratches on the surface of the protective film, usually caused by external factors during transportation or processing. Such film surface defects have a high probability of occurrence, but do not affect the functionality of the product body and generally do not need to be treated. Film bottom defects are foreign matter, scratches or damage on the surface of the flat panel product body (i.e. below the film layer). Such film bottom defects have a low probability of occurrence, but will directly affect the product quality and need to be treated in a timely manner. In order to ensure product quality, film bottom defects of film-pasted products need to be detected and treated during the manufacturing process of touch screens, displays and other flat panel products.

[0004] Modern manufacturing industry generally uses industrial robots and machine vision technology to detect the appearance defects of film-pasted products. Currently, many manufacturers of flat panel products such as touch screens or displays also hope to use electronic lenses to image the surface of the flat panel product and combine machine vision methods to detect film bottom defects of film-pasted products. However, since the protective film is generally a transparent plastic film, the film bottom defects and film surface defects are often mixed together in the image obtained by the electronic lens, and general machine vision is difficult to distinguish them. Therefore, it is difficult to accurately and efficiently detect film bottom defects of film-pasted products using machine vision methods. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a defect image detection method for a film-pasted product, which can detect appearance defects on the surface of the film-pasted product, accurately and efficiently determine whether the appearance defects are film surface defects or film bottom defects, and will not damage the film-pasted product, thereby helping to ensure the quality of the film-pasted product. The technical solution adopted is as follows: A defect image detection method for a film-pasted product, characterized by comprising the following steps: S1, providing a to-be-detected film product, the film product comprising a substrate and a transparent release film attached to the surface of the substrate, the transparent release film being composed of a plastic film and a release layer coated on the plastic film, and a fluorescent agent being coated on the surface of the plastic film or being distributed on the surface of the plastic film; S2, irradiating the transparent release film on the film product with visible light, and performing first shooting on the surface of the film product to obtain a first photo; S3, identifying all appearance defects existing on the surface of the film product by resolving the first photo; S4, irradiating the film product with ultraviolet light to excite the transparent release film to generate fluorescence on the surface of the transparent release film, and performing second shooting on the surface of the film product to obtain a second photo imaged by the fluorescence; S5, judging whether the appearance defects identified in the step S3 are film bottom defects or film surface defects by comparing and analyzing the second photo and the first photo.

[0006] Specifically, the substrate can be a glass substrate, a glass lens, a plastic lens, a display screen, a touch screen, or a display module, etc. The surface of the substrate can be attached with a film. The plastic film is generally a transparent plastic film made of polyester (PET), polypropylene (PP), or polyethylene (PE) high molecular material. The release layer is generally made of organic silicone resin, fluorocarbon compound, or non-silicon release agent. When the plastic film is made of PET, PC, PVC, or other high molecular material, the fluorescent agent can be OB series, such as OB (CAS: 7128-64-5), OB-1 (CAS: 1533-45-5), which can be well dispersed in the plastic film and can ensure the transparency of the plastic film. In addition, the fluorescent agent can also be FP-127 (CAS: 40470-68-6), KCB (CAS: 5089-22-5), KSN (CAS: 5242-49-9), etc.

[0007] In the above defect image detection method, in the step S2, the film product is irradiated with visible light and photographed for the first time, since the visible light can penetrate the transparent release film, thus the first photo obtained can contain the images of the appearance defects of the film product including the film bottom defects and the film surface defects; in the step S3, the first photo can be distinguished by image recognition, machine vision, AI and other technologies to identify the appearance defects existing on the surface of the film product, and all the appearance defects and their positions can be marked in advance; in the step S4, the film product is irradiated with ultraviolet light and photographed for the second time, since the plastic film in the transparent release film can absorb ultraviolet light, in the case of high absorption rate, the ultraviolet light mainly acts on the surface layer of the plastic film, and the fluorescent component of the surface layer of the plastic film is excited by the ultraviolet light to emit visible fluorescence of a specific frequency, thus the second photo obtained can contain the images formed by the fluorescence emitted by the surface layer of the plastic film, and the film bottom defects of the film product can not be observed in the second photo; thus in the step S5, by comparing and analyzing the first photo and the second photo, it can be distinguished whether the appearance defects of the film product identified in the step S3 are film bottom defects or film surface defects, which is not only accurate and efficient, but also does not damage the film product, and is beneficial to ensure the quality of the film product.

[0008] As a preferred scheme of the present application, the thickness of the plastic film is 25-300 μm.

[0009] As a preferred scheme of the present application, the ultraviolet absorbance of the plastic film is ≥1.3. Thus in the step S2, the ultraviolet light mainly acts on the surface of the plastic film, thus the defects of the surface of the plastic film can be better presented.

[0010] As a preferred scheme of the present application, the visible light transmittance of the plastic film is ≥70%. Thus in the step S2, the film bottom defects of the film product can be clearly photographed.

[0011] As a preferred scheme of the present application, the fluorescence quantum yield of the surface of the plastic film is ≥0.7. Thus in the step S2, the ultraviolet light can excite the fluorescence of sufficient brightness in the surface layer of the plastic film, thus the defects of the surface of the release film can be better presented.

[0012] As a preferred scheme of the present application, the addition amount of the fluorescent agent is 0.0001%-0.05%. Thus the plastic film can have high enough fluorescence quantum yield and ultraviolet absorbance.

[0013] As a preferred scheme of the present application, in the step S5, when the image of a certain appearance defect is observed to be weakened or disappeared on the second photo, it is judged that the appearance defect belongs to the film bottom defect; when the image of a certain appearance defect is observed to be not weakened or even enhanced on the second photo, it is judged that the appearance defect belongs to the film surface defect.

[0014] As a preferred scheme of the present application, in the step S4, the surface of the decorated product is secondly photographed by using a camera, and a filter is installed on the camera head of the camera. Generally, the filtering wavelength of the filter is matched with the fluorescent emission wavelength of the plastic film, especially when the plastic film is added with fluorescent agent, for example, when the fluorescent agent is OB, the filtering wavelength of the filter is selected as 430-440 nm. The filter is used to filter out the light of non-fluorescent wavelength emitted by the surface layer of the plastic film, so that the second photo only contains the image formed by the fluorescence emitted by the surface layer of the plastic film, thereby it can filter out the image formed by the film bottom defect, so that the image of the film surface defect in the second photo is clearer.

[0015] As a further preferred scheme of the present application, in the steps S2 and S4, the same camera is used to take the first photo and the second photo, and the filter is detachably installed on the camera head of the camera. When the first photo is taken in the step S2, the filter is detached from the camera head; and when the second photo is taken in the step S4, the filter is installed on the camera head. Thus, by using the same camera to take the first photo and the second photo, it can be ensured that the position and shape of the appearance defect of the decorated product in the first photo and the second photo are consistent, and it is easier to judge by comparing the image intensity.

[0016] As a further preferred scheme of the present application, in the steps S2-S4, the first and second photographing of the surface of the film product is completed by using a defect detection device; the defect detection device comprises a rack, a film product conveying mechanism, the camera, a visible light source and an ultraviolet light source, the film product conveying mechanism, the camera, the visible light source and the ultraviolet light source are all installed on the rack, the film product conveying mechanism has a conveying section moving forward and backward, the camera, the visible light source and the ultraviolet light source are all above the conveying section of the film product conveying mechanism, the camera head of the camera is downwardly arranged and faces the film product conveying mechanism, and the visible light source and the ultraviolet light source are respectively arranged on the front and back sides of the camera. In use, the film product is placed on the conveying section of the film product conveying mechanism, the film product is conveyed by the film product conveying mechanism so as to pass below the camera head of the camera from front to back (at this time, the camera head is not provided with a filter), the visible light source is started in this process, the visible light emitted by the visible light source is irradiated on the film product, the surface of the film product is first photographed by the camera, and a first photo is obtained; then, after a filter is installed on the camera head, the film product is conveyed reversely by the film product conveying mechanism so as to pass below the camera head from back to front, the ultraviolet light source is started in this process, the external light emitted by the ultraviolet light source is irradiated on the film product, the surface of the film product is second photographed by the camera, and a second photo is obtained, so that the same camera is used for photographing in the steps S2 and S4, and the cost can be reduced.

[0017] As a still further preferred scheme of the present application, the film product conveying mechanism comprises a plurality of conveying rollers arranged from front to back and rotating in the same direction. Specifically, the plurality of conveying rollers can be synchronously rotated in a forward direction or a reverse direction under the drive of a drive mechanism (which can be composed of a drive motor and a plurality of transmission belt mechanisms), and the film product on the conveying rollers is moved back and forth below the camera head of the camera.

[0018] In order to cooperate with the movement of the film product, as a still further preferred scheme of the present application, the camera uses a line array camera.

[0019] Compared with the prior art, the present application has the following advantages: The defect image detection method for the film product can detect the appearance defects of the surface of the film product, can accurately and efficiently judge whether the appearance defects belong to film surface defects or film bottom defects, will not damage the film product, and is beneficial to guarantee the quality of the film product. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the image of the first photo obtained in the step S2 of the defect image detection method provided by the preferred embodiment of the present application.

[0021] Figure 2is the image of the second photo obtained by photographing in step S4 of the defect image detection method provided by the preferred embodiment of the present application.

[0022] Figure 3 is a structural schematic diagram of the appearance defect detection device provided by the preferred embodiment of the present application. DETAILED DESCRIPTION

[0023] As shown in Figure 1 , Figure 2 , the defect image detection method for the film product comprises the following steps: S1, providing a film product 10 to be detected, the film product 10 comprising a substrate 11 and a transparent release film 12 attached to the surface of the substrate 11, the transparent release film 12 being composed of a plastic film 121 and a release layer 122 coated on the plastic film 121, and the surface of the plastic film 121 being coated with a fluorescent agent; S2, irradiating the transparent release film 12 on the film product 10 with visible light, and performing first photographing on the surface of the film product 10 to obtain a first photo 20; S3, identifying all appearance defects existing on the surface of the film product 10 by resolving the first photo 20; S4, irradiating the film product 10 with ultraviolet light to excite the transparent release film 12 to generate fluorescence 120, and performing second photographing on the surface of the film product 10 to obtain a second photo 30 imaged by the fluorescence 120; S5, comparing and analyzing the second photo 30 with the first photo 20 to determine whether the appearance defects identified in step S3 are film bottom defects 130 or film surface defects 140.

[0024] In this embodiment, the substrate 11 is a flat plate structure or device with a surface to which a film can be attached, such as a glass substrate, a glass lens, a plastic lens, a display screen, a touch screen or a display module; the plastic film 121 is a transparent plastic film made of high molecular materials such as polyester (PET), polypropylene (PP) or polyethylene (PE); the release layer 122 is made of organic silicone resin, fluorocarbon compound or non-silicon release agent; in the case where the plastic film 121 is made of high molecular materials such as PET, PC or PVC, the fluorescent agent can be OB series, such as OB (‌CAS‌: 7128-64-5), OB-1 (‌CAS‌: 1533-45-5), which can be well dispersed in the plastic film 121 and can ensure the transparency of the plastic film 121. In addition, the fluorescent agent can also be FP-127 (CAS: 40470-68-6), KCB (‌CAS‌: 5089-22-5), KSN (‌CAS‌: 5242-49-9) and the like.

[0025] In this embodiment, the thickness of the plastic film 121 is 25-300 μm.

[0026] In the embodiment, the ultraviolet absorbance of the plastic film 121 is 1.3. Thus, in step S2, the ultraviolet light mainly acts on the surface of the plastic film 121, so that the defects on the surface of the plastic film 121 can be better presented.

[0027] In the embodiment, the visible light transmittance of the plastic film 121 is 70%. Thus, in step S2, the film bottom defects 130 of the film product 10 can be clearly captured.

[0028] In the embodiment, the fluorescence quantum yield of the surface of the plastic film 121 is 0.7. Thus, in step S2, the ultraviolet light can excite the fluorescence 120 with sufficient brightness on the surface layer of the plastic film 121, so that the defects on the surface of the release film can be better presented.

[0029] In the embodiment, the addition amount of the fluorescent agent is 0.0001%-0.05%, so that the plastic film 121 has a high enough fluorescence 120 quantum yield and ultraviolet absorbance.

[0030] In the embodiment, in step S5, when the image of an appearance defect is observed to be weakened or disappeared on the second photo 30, it is judged that the appearance defect belongs to the film bottom defect 130; when the image of an appearance defect is observed to be not weakened or even enhanced on the second photo 30, it is judged that the appearance defect belongs to the film surface defect 140.

[0031] Reference Figure 3 The defect detection device 50 provided in the embodiment can complete the first and second capturing of the surface of the film product 10 in steps S2-S4. The defect detection device 50 comprises a rack (not shown in the figure), a film product conveying mechanism 51, a linear array camera 52, a visible light source 53 and an ultraviolet light source 54, the film product conveying mechanism 51, the linear array camera 52, the visible light source 53 and the ultraviolet light source 54 are all installed on the rack, the film product conveying mechanism 51 comprises a plurality of conveying rollers 510 arranged from front to back and rotating in the same direction; the linear array camera 52, the visible light source 53 and the ultraviolet light source 54 are all above the film product conveying mechanism 51, the camera of the linear array camera 52 is arranged downward and faces each conveying roller 510, and a filter 55 is detachably installed on the camera of the linear array camera 52; the visible light source 53 and the ultraviolet light source 54 are respectively arranged on the front and back sides of the linear array camera 52. Generally, the filtering wavelength of the filter 55 matches the fluorescence 120 emission wavelength of the plastic film 121, especially when the plastic film 121 is added with a fluorescent agent, for example, when the fluorescent agent is OB, the filtering wavelength of the filter 55 is selected as 430-440 nm.

[0032] In use, the sticker product 10 can be placed on each conveying roller 510 of the sticker product conveying mechanism 51, and the sticker product 10 is conveyed from front to back under the camera of the linear array camera 52 (at this time, the camera of the linear array camera 52 is not provided with the filter 55), and in this process, the visible light source 53 is started to emit visible light on the sticker product 10, and the linear array camera 52 is used to take the first photo 20 of the surface of the sticker product 10; then, after the filter 55 is installed on the camera of the linear array camera 52, the sticker product 10 is conveyed in reverse by the sticker product conveying mechanism 51, and the sticker product 10 is conveyed from back to front under the camera of the linear array camera 52, and in this process, the ultraviolet light source 54 is started to emit ultraviolet light on the sticker product 10, and the linear array camera 52 is used to take the second photo 30 of the surface of the sticker product 10 (the filter 55 is used to filter out the non-fluorescent light 120 of the plastic film 121, so that the second photo 30 only contains the image formed by the fluorescent light 120 of the plastic film 121, and thus the image of the film bottom defect 130 can be filtered out, so that the image of the film surface defect 140 in the second photo 30 is clearer).

[0033] In addition, it should be noted that the specific embodiments described in the specification can have different names and the like, and any equivalent or simple changes made in accordance with the structure, features and principles of the patent concept of the present application are included in the protection scope of the present application. Those skilled in the art can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, as long as they do not deviate from the structure of the present application or exceed the scope defined by the present claims, and they should belong to the protection scope of the present application.

Claims

1. A method for detecting defective images of film products, characterized in that: The steps include: S1. Provide a film product to be inspected, wherein the film product comprises a substrate and a transparent release film attached to the surface of the substrate, wherein the transparent release film is composed of a plastic film and a release layer coated on the plastic film, and the surface of the plastic film is coated with a fluorescent agent or the fluorescent agent is distributed on the surface of the plastic film; S2, irradiating the transparent release film on the film-attached product with visible light, and photographing the surface of the film-attached product for the first time to obtain a first photograph; S3. Resolving the first photo to identify all appearance defects on the surface of the film-applied product; S4, irradiating the film-attached product with ultraviolet light to excite the surface of the transparent release film to generate fluorescence, and photographing the surface of the film-attached product a second time to obtain a second photograph formed by fluorescence imaging; S5. By comparing and analyzing the second photo and the first photo, it is determined whether the appearance defect identified in the step S3 is a film bottom defect or a film surface defect.

2. The method for detecting defective images of film products according to claim 1, wherein: The ultraviolet absorbance of the plastic film is ≥1.

3.

3. The defect image detection method for film products according to claim 1, characterized in that: The visible light transmittance of the plastic film is ≥70%.

4. The method for detecting defective images of film products according to claim 1, wherein: The fluorescence quantum yield on the surface of the plastic film is ≥0.

7.

5. The defect image detection method for film products according to claim 1, characterized in that: The added amount of the fluorescent agent is 0.0001%-0.05%.

6. The method for detecting defective images of film products according to claim 1, wherein: In step S5, when the image of a certain appearance defect is observed to be weakened or disappeared on the second photograph, it is determined that the appearance defect is a film bottom defect; when the image of a certain appearance defect is observed to be not weakened or even enhanced on the second photograph, it is determined that the appearance defect is a film surface defect.

7. The method for detecting defective images of film products according to claim 1, wherein: In step S4, a camera is used to take a second picture of the surface of the film-attached product, and a filter is installed on the camera head of the camera.

8. The method for detecting defective images of film products according to claim 7, wherein: In the steps S2 and S4, the first photo and the second photo are taken respectively using the same camera, and the filter is detachably mounted on the camera head of the camera.

9. The method for detecting defective images of film products according to claim 8, wherein: In the steps S2-S4, a defect detection device is used to complete the first and second shots of the surface of the film product; the defect detection device includes a frame, a film product conveying mechanism, the camera, a visible light source and an ultraviolet light source, the film product conveying mechanism, the camera, the visible light source and the ultraviolet light source are all installed on the frame, the film product conveying mechanism has a conveying section that moves back and forth, the camera, the visible light source and the ultraviolet light source are all located above the conveying section of the film product conveying mechanism, and the camera head is set downward and facing the film product conveying mechanism; the visible light source and the ultraviolet light source are respectively located on the front and back sides of the camera.

10. The method for detecting defective images of film products according to claim 9, wherein: The film-attached product conveying mechanism includes a plurality of conveying rollers arranged from front to back and rotating in the same direction; the camera is a linear array camera.

Images