A defect image detection method for a film pasting product

Abstract

The present application relates to a kind of defect image detection methods for film product, comprising the following steps: S1 provides the film product to be detected, film product includes substrate and transparent release film attached on the surface of substrate, transparent release film is made of plastic film and release layer, and plastic film surface layer is coated with fluorescent agent;S2 adopts visible light to irradiate film product, and first photo is obtained by photographing film product;S3 is identified by resolving first photo, and all appearance defects on the surface of film product are identified;S4 adopts ultraviolet light to irradiate film product, to excite the surface of transparent release film to generate fluorescence, and second photo is obtained by photographing film product second time by fluorescence imaging;S5 is identified by comparing and analyzing second photo with first photo, to judge whether the appearance defect identified is film bottom defect or film surface defect.It is not only accurate, efficient to judge that appearance defect belongs to film surface defect or film bottom defect, and film product will not be damaged, and it is beneficial to guarantee the quality of film product.

Description

Technical Field

[0001] This invention relates to the field of detection technology, and more specifically to a method for detecting defect images in laminated products. Background Technology

[0002] In the manufacturing process of flat products such as touch screens and monitors, a protective film is usually attached to the surface of the product to protect it from scratches, contamination or mechanical damage. The protective film is usually made of transparent plastic film of PE, PP, PVC or PET. Flat products with protective films are generally called film products.

[0003] For screen protectors, both the surface of the tablet itself and the surface of the protective film may have appearance defects (such as damage or dirt), which can be referred to as bottom film defects and surface film defects, respectively. Surface film defects are damage, dirt, or scratches located on the surface of the protective film, usually caused by external factors during transportation or processing. These surface defects have a high probability of occurrence, but since they do not affect the functionality of the product itself, they generally do not require treatment. Bottom film defects are foreign objects, scratches, or damage located on the surface of the tablet itself (i.e., below the film layer). These bottom film defects have a lower probability of occurrence, but they directly affect product quality and require timely treatment. To ensure product quality, bottom film defects in screen protectors need to be detected and addressed during the manufacturing process of tablet products such as touch screens and displays.

[0004] Modern manufacturing widely employs industrial robots and machine vision technology to detect surface defects in laminated products. Currently, many manufacturers of flat panel products such as touchscreens or displays also hope to use electron lenses to image the surface of their products and combine this with machine vision methods to detect defects on the underside of the laminated film. However, since protective films are generally transparent plastic films, defects on the underside and surface of the film are often mixed together in the images acquired by electron lenses, making it difficult for conventional machine vision to distinguish them. Therefore, it is difficult to accurately and efficiently detect defects on the underside of laminated products using machine vision methods. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a defect image detection method for laminated products. This method can detect surface defects on laminated products, accurately and efficiently determining whether the defect is a surface or substrate defect, without damaging the laminated product, thus ensuring its quality. The technical solution adopted is as follows:

[0006] A method for detecting defects in laminated products, characterized by comprising the following steps:

[0007] S1. Provide the film to be tested. The film includes 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 coated on the plastic film. 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.

[0008] S2. Irradiate the transparent release film on the adhesive with visible light and take a first photograph of the surface of the adhesive to obtain a first photograph;

[0009] S3. By distinguishing the first photograph, all appearance defects existing on the surface of the film are identified;

[0010] S4. Irradiate the film with ultraviolet light to excite the surface of the transparent release film to produce fluorescence, and take a second picture of the surface of the film to obtain a second picture of fluorescence imaging;

[0011] S5. By comparing and analyzing the second photograph with the first photograph, it is determined whether the appearance defect identified in step S3 is a film bottom defect or a film surface defect.

[0012] Specifically, the substrate can be a flat structure or device with a film-adhesive surface, such as a glass substrate, glass lens, plastic lens, display screen, touch screen, or display module; the plastic film is generally a transparent plastic film made of polymer materials such as polyester (PET), polypropylene (PP), or polyethylene (PE); the release layer is generally made of silicone resin, fluorocarbon compound, or non-silicone release agent; when the plastic film is made of polymer materials such as PET, PC, or PVC, the fluorescent agent can be from the OB series, such as OB (CAS: 7128-64-5) or OB-1 (CAS: 1533-45-5), which disperses well in the plastic film and ensures the transparency of the plastic film. In addition, the fluorescent agent can also be from the FP-127 (CAS: 40470-68-6), KCB (CAS: 5089-22-5), KSN (CAS: 5242-49-9), etc.

[0013] In the aforementioned defect image detection method, in step S2, the laminated product is irradiated with visible light and a first image is taken. Since visible light can pass through the transparent release film, the first image obtained contains images of surface defects on the laminated product, including defects on the film bottom and surface. In step S3, the first image can be analyzed using image recognition, machine vision, AI, and other technologies to identify surface defects on the laminated product, and all surface defects and their locations can be pre-marked. In step S4, the laminated product is irradiated with ultraviolet light and a second image is taken. Since the plastic film in the transparent release film absorbs ultraviolet light, the image will be obscured. When the absorption rate is high, ultraviolet light mainly acts on the surface of the plastic film, and the fluorescent components on the surface of the plastic film are excited by ultraviolet light to emit visible fluorescence of a specific frequency. This allows the second photograph to contain an image formed by the fluorescence emitted from the surface of the plastic film. The second photograph can only observe the surface defects of the film, and will not make it difficult to observe the bottom defects. Therefore, in step S5, by comparing and analyzing the first and second photographs, it is possible to distinguish whether the appearance defects of the film identified in step S3 are bottom defects or surface defects. This is not only accurate and efficient, but also does not damage the film, which helps to ensure the quality of the film.

[0014] As a preferred embodiment of the present invention, the thickness of the plastic film is 25-300 μm.

[0015] As a preferred embodiment of the present invention, the ultraviolet absorbance of the plastic film is ≥1.3. This allows the ultraviolet light to primarily act on the surface of the plastic film in step S2, thereby better revealing defects on the surface of the plastic film.

[0016] As a preferred embodiment of the present invention, the visible light transmittance of the plastic film is ≥70%. This allows for the clear imaging of defects on the bottom of the film-coated product in step S2.

[0017] As a preferred embodiment of the present invention, the fluorescence quantum yield of the plastic film surface is ≥0.7. This ensures that in step S2, ultraviolet light can excite sufficiently bright fluorescence on the surface of the plastic film, thereby better revealing defects on the release film surface.

[0018] As a preferred embodiment of the present invention, the amount of fluorescent agent added is 0.0001%-0.05%. This ensures that the plastic film has a sufficiently high fluorescence quantum yield and ultraviolet absorbance.

[0019] As a preferred embodiment of the present invention, in step S5, if the image of a certain appearance defect is observed to be weakened or disappears in the second photograph, it is determined that the appearance defect belongs to the bottom layer defect; if the image of a certain appearance defect is observed to be neither weakened nor even enhanced in the second photograph, it is determined that the appearance defect belongs to the surface layer defect.

[0020] In a preferred embodiment of the present invention, in step S4, a camera is used to take a second photograph of the surface of the film, and the camera lens of the camera is equipped with a filter. Typically, the filtering wavelength of the filter is matched with the fluorescence emission wavelength of the plastic film, especially when a fluorescent agent is added to the plastic film. 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 non-fluorescent wavelengths of light emitted from the surface of the plastic film, ensuring that the second photograph only contains images formed by fluorescence emitted from the surface of the plastic film. This filters out images formed by defects on the film bottom, making the images of film surface defects in the second photograph clearer.

[0021] As a further preferred embodiment of the present invention, in steps S2 and S4, the same camera is used to take the first and second photos respectively, and the filter is detachably mounted on the camera lens. When taking the first photo in step S2, the filter can be removed from the camera lens; while when taking the second photo in step S4, the filter can be mounted on the camera lens. Therefore, by using the same camera to take the first and second photos, the position and shape of the appearance defects of the ornament can be ensured to be consistent in both the first and second photos, making it easier to judge through the comparison of image intensity.

[0022] As a further preferred embodiment of the present invention, in steps S2-S4, a defect detection device is used to complete the first and second images of the surface of the film-coated product. The defect detection device includes a frame, a film-coated product conveying mechanism, the camera, a visible light source, and an ultraviolet light source. The film-coated product conveying mechanism, the camera, the visible light source, and the ultraviolet light source are all mounted on the frame. The film-coated 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-coated product conveying mechanism. The camera lens is set downward and faces the film-coated product conveying mechanism. The visible light source and the ultraviolet light source are located on the front and rear sides of the camera, respectively. In use, the film can be placed flat on the conveyor section of the film conveyor mechanism, and the film is conveyed by the film conveyor mechanism so that it passes under the camera lens from front to back (at this time, the camera lens does not have a filter). During this process, the visible light source is activated, and the visible light emitted by the visible light source shines on the film. At the same time, the camera takes a first picture of the surface of the film to obtain the first photo. Subsequently, after installing a filter on the camera lens, the film is conveyed in the reverse direction by the film conveyor mechanism so that it passes under the camera lens from back to front. During this process, the ultraviolet light source is activated, and the ultraviolet light emitted by the ultraviolet light source shines on the film. At the same time, the camera takes a second picture of the surface of the film to obtain the second photo. This allows the same camera to be used for steps S2 and S4, which can reduce costs.

[0023] As a further preferred embodiment of the present invention, the film-coated product conveying mechanism includes multiple conveying rollers arranged from front to back and rotating in the same direction. Specifically, the multiple conveying rollers can rotate synchronously in the forward or reverse direction under the drive of a driving mechanism (the driving mechanism may be composed of a drive motor and multiple transmission belt mechanisms), causing the film-coated products on them to move back and forth below the camera lens.

[0024] To accommodate the movement of the applied film, as a further preferred embodiment of the present invention, the camera is a line scan camera.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] This defect image detection method for laminated products can detect surface defects on laminated products. It can accurately and efficiently determine whether the defect belongs to the surface or the bottom of the film, without damaging the laminated product, which helps to ensure the quality of the laminated product. Attached Figure Description

[0027] Figure 1 This is an image of the first photograph obtained in step S2 of the defect image detection method provided in the preferred embodiment of the present invention.

[0028] Figure 2This is an image of the second photograph obtained in step S4 of the defect image detection method provided in the preferred embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of the appearance defect detection device provided in a preferred embodiment of the present invention. Detailed Implementation

[0030] like Figure 1 , Figure 2 As shown, this defect image detection method for laminated products includes the following steps:

[0031] S1. Provide a film product 10 to be tested. The film product 10 includes a substrate 11 and a transparent release film 12 attached to the surface of the substrate 11. The transparent release film 12 is composed of a plastic film 121 and a release layer 122 coated on the plastic film 121. The surface of the plastic film 121 is coated with a fluorescent agent.

[0032] S2. Irradiate the transparent release film 12 on the film 10 with visible light and take a first picture of the surface of the film 10 to obtain the first picture 20.

[0033] S3. By distinguishing the first photograph 20, all appearance defects existing on the surface of the film product 10 are identified;

[0034] S4. Use ultraviolet light to irradiate the film 10 to excite the surface of the transparent release film 12 to generate fluorescence 120, and take a second picture of the surface of the film 10 to obtain a second picture 30 formed by fluorescence 120.

[0035] S5. By comparing and analyzing the second photograph 30 with the first photograph 20, it is determined whether the appearance defect identified in step S3 is the bottom defect 130 or the surface defect 140.

[0036] In this embodiment, the substrate 11 is a flat structure or device with a surface that can be coated with a film, such as a glass substrate, glass lens, plastic lens, display screen, touch screen, or display module; the plastic film 121 is a transparent plastic film made of polymer materials such as polyester (PET), polypropylene (PP), or polyethylene (PE); the release layer 122 is made of silicone resin, fluorocarbon compound, or non-silicone release agent; when the plastic film 121 is made of polymer materials such as PET, PC, or PVC, the fluorescent agent can be from the OB series, such as OB (CAS: 7128-64-5) or OB-1 (CAS: 1533-45-5), which disperses well in the plastic film 121 and can ensure the transparency of the plastic film 121. In addition, the fluorescent agent can also be from the FP-127 (CAS: 40470-68-6), KCB (CAS: 5089-22-5), KSN (CAS: 5242-49-9), etc.

[0037] In this embodiment, the thickness of the plastic film 121 is 25–300 μm.

[0038] In this embodiment, the ultraviolet absorbance of the plastic film 121 is 1.3. This allows the ultraviolet light to primarily act on the surface of the plastic film 121 in step S2, thereby better revealing defects on the surface of the plastic film 121.

[0039] In this embodiment, the visible light transmittance of the plastic film 121 is 70%. This allows the film bottom defect 130 of the film-coated product 10 to be clearly photographed in step S2.

[0040] In this embodiment, the fluorescence quantum yield on the surface of the plastic film 121 is 0.7. This allows ultraviolet light to excite sufficiently bright fluorescence 120 on the surface of the plastic film 121 in step S2, thereby better revealing defects on the release film surface.

[0041] In this embodiment, the amount of fluorescent agent added is 0.0001%-0.05%, which ensures that the plastic film 121 has a sufficiently high fluorescence quantum yield and ultraviolet absorbance.

[0042] In this embodiment, in step S5, if the image of a certain appearance defect is observed to be weakened or disappears on the second photograph 30, it is determined that the appearance defect belongs to the film bottom defect 130; if the image of a certain appearance defect is observed to be neither weakened nor even enhanced on the second photograph 30, it is determined that the appearance defect belongs to the film surface defect 140.

[0043] refer to Figure 3The defect detection device 50 provided in this embodiment can complete the first and second images of the surface of the film-coated product 10 in steps S2-S4. The defect detection device 50 includes a frame (not shown in the figure), a film-coated product conveying mechanism 51, a line scan camera 52, a visible light source 53, and an ultraviolet light source 54. The film-coated product conveying mechanism 51, the line scan camera 52, the visible light source 53, and the ultraviolet light source 54 are all mounted on the frame. The film-coated product conveying mechanism 51 includes multiple conveying rollers 510 arranged from front to back and rotating in the same direction. The line scan camera 52, the visible light source 53, and the ultraviolet light source 54 are all located above the film-coated product conveying mechanism 51. The camera of the line scan camera 52 is set downward and faces each conveying roller 510. A filter 55 is detachably installed on the camera of the line scan camera 52. The visible light source 53 and the ultraviolet light source 54 are located on the front and rear sides of the line scan camera 52, respectively. Typically, the filtering wavelength of filter 55 is matched with the emission wavelength of fluorescence 120 of plastic film 121, especially when a fluorescent agent is added to plastic film 121. For example, when the fluorescent agent is OB, the filtering wavelength of filter 55 is selected as 430–440 nm.

[0044] In use, the film-coated product 10 can be placed flat on each of the conveying rollers 510 of the film-coated product conveying mechanism 51. The film-coated product 10 is conveyed by each of the conveying rollers 510 of the film-coated product conveying mechanism 51, so that it passes from front to back under the camera of the line scan camera 52 (at this time, the camera of the line scan camera 52 is not fitted with a filter 55). During this process, the visible light source 53 is activated, and the visible light emitted by the visible light source 53 illuminates the film-coated product 10. At the same time, the line scan camera 52 takes the first picture of the surface of the film-coated product 10, obtaining the first picture 20. Subsequently, after installing the filter 55 on the camera of the line scan camera 52, the film-coated product conveying mechanism 51... The film-coated product 10 is transported in reverse, passing under the camera of the line scan camera 52 from back to front. During this process, the ultraviolet light source 54 is activated, and the external light emitted by the ultraviolet light source 54 illuminates the film-coated product 10. At the same time, the line scan camera 52 takes a second picture of the surface of the film-coated product 10 to obtain a second picture 30. (The filter 55 is used to filter out the non-fluorescent wavelength 120 light emitted by the surface of the plastic film 121, which can ensure that the second picture 30 only contains the image formed by the fluorescence 120 emitted by the surface of the plastic film 121. Thus, it can filter out the image formed by the film bottom defect 130, making the image of the film surface defect 140 in the second picture 30 clearer.)

[0045] Furthermore, it should be noted that the names of the various parts of the specific embodiments described in this specification may differ. All equivalent or simple variations made based on the structure, features, and principles of this invention are included within the scope of protection of this invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the structure of this invention or exceed the scope defined by the claims, all of which should fall within the scope of protection of this invention.

Claims

1. A method for defect image detection in laminated products, characterized in that: It comprises the following steps: S1, providing a film product to be detected, 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, the surface of the plastic film being coated with a fluorescent agent or the fluorescent agent being distributed on the surface of the plastic film; S2, irradiating the transparent release film on the film product with visible light, and taking a first photo of 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 distinguishing the first photo; S4, irradiating the film product with ultraviolet light to excite the surface of the transparent release film to generate fluorescence, and taking a second photo of the surface of the film product, to obtain a second photo imaged by fluorescence; In steps S2-S4, the first and second photos of the surface of the film product are taken by a defect detection device; the defect detection device comprises a rack, a film product conveying mechanism, a 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, a filter is detachably installed on the camera head of the camera, the visible light source and the ultraviolet light source are respectively arranged on the front and back sides of the camera; S5, comparing and analyzing the second photo with the first photo to determine whether the appearance defects identified in step S3 are film bottom defects or film surface defects: when the image of an appearance defect is observed to be weakened or disappeared on the second photo, it is determined that the appearance defect belongs to a film bottom defect; when the image of an appearance defect is observed to be not weakened or even enhanced on the second photo, it is determined that the appearance defect belongs to a film surface defect. 2.The defect image detection method for a film attached product according to claim 1, characterized in that: The ultraviolet absorbance of the plastic film is ≥1.

3. 3.The method for detecting defect images of a product with a film according to claim 1, characterized in that: The visible light transmittance of the plastic film is ≥70%. 4.The method for detecting defect images of a product with a film according to claim 1, characterized in that: The fluorescence quantum yield of the surface of the plastic film is ≥0.

7. 5.The method for detecting defect images of a product with a film according to claim 1, characterized in that: The addition amount of the fluorescent agent is 0.0001%-0.05%. 6.The method for detecting defect images of a product with a film according to claim 1, wherein: The film product conveying mechanism comprises a plurality of conveying rollers arranged from front to back and rotating in the same direction. 7.The method for detecting defect images of a product with a film according to claim 1, wherein: The camera adopts a line array camera.

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