Metal foil surface defect detection system and method

Abstract

The application provides a metal foil surface defect detection system and method. The metal foil surface defect detection method of the application dynamically adjusts the light source irradiation angle by monitoring the thickness change of the foil to be tested in real time, so that the lighting conditions always match the geometric characteristics of the current material surface. The shadow projection relationship of the defect edge is stable, the contrast of the microscopic deformation is enhanced, and the detection rate of small defects is significantly improved. In the embodiment, the brightness characteristic change of the defect area under the optimized illumination is utilized, and the system can distinguish the protrusions, depressions and foreign matter on the surface of the metal foil according to the brightness change of the defect area in the image data. The technical scheme of the application solves the balance problem of sensitivity, stability and efficiency in the detection of precise metal foil defects through the thickness self-adaptive dynamic lighting strategy. The application provides a detection scheme capable of online, high-speed and accurate distinction of microscopic concave-convex deformation and foreign matter on the surface of the metal foil.

Description

Technical Field

[0001] This invention belongs to the field of fine metal mask manufacturing technology, specifically relating to a system and method for detecting surface defects in metal foil. Background Technology

[0002] Currently, Organic Light Emitting Diode (OLED) display panels are a type of panel that uses OLEDs as display pixels. Compared to traditional LCD panels, OLED display panels are becoming increasingly popular in the market due to their numerous advantages, such as self-illumination, low power consumption, excellent color performance, and applicability to flexible displays.

[0003] OLED light-emitting devices are generally fabricated by vapor-depositing organic materials onto a substrate. Vapor deposition of organic materials typically requires a mask. Masks primarily serve as pattern transfer masters and are typically customized. Masks are divided into photomasks (photomasks) and metal masks (shadow masks). Photomasks are mainly used in photolithography processes, are made of high-purity quartz glass, and are used to create circuit patterns. Fine metal masks (FMMs) are a key component in OLED display manufacturing, primarily used for the precise deposition of organic materials to form pixel patterns.

[0004] Fabricating fine metal masks (FMMs) requires roll-to-roll metal foils (such as copper foil, aluminum foil, and battery electrodes). Surface defect detection is a crucial quality control step in the production of roll-to-roll metal foils. Currently, the industry widely uses automated optical inspection (AOI) systems based on line-scan cameras.

[0005] However, existing technologies have significant limitations: 1. Inability to distinguish the unevenness of surface defects: For microscopic deformations (such as indentations and bumps) or foreign objects attached to the surface (such as dust and impurities), under traditional bright-field or dark-field illumination, line scan cameras typically only capture a uniform dark spot or line lacking three-dimensional topographic information. Traditional AOI systems cannot determine from two-dimensional images whether the defect is a depression, a bulge, or a foreign object, leading to a high false positive rate and severely affecting the accuracy of mask quality grading. 2. Limited detection capability: The grayscale changes caused by microscopic deformations are weak and easily drowned out by background noise, making it difficult for traditional AOI systems to detect them reliably.

[0006] Therefore, there is an urgent need to provide a detection solution that can distinguish between microscopic unevenness and foreign matter on the surface of metal foil in an online, high-speed and accurate manner. Summary of the Invention

[0007] In view of this, this application provides a surface defect detection system and method for metal foil, which, based on the principle of active dimming, enables the detection of micro-deformation (dimples or protrusions) and foreign objects in roll-to-roll metal foil, thereby improving the accuracy of the opening pattern.

[0008] The technical solution provided in this application is as follows:

[0009] On the one hand, this application provides a method for detecting surface defects in metal foil, including:

[0010] The metal foil to be tested is transferred via a roll-to-roll transport mechanism;

[0011] The thickness data of the metal foil is measured online in real time by a film thickness testing agency. current ;

[0012] Based on the thickness data TH of the metal foil to be tested current The light emission angle of the adjustable angle light source module is dynamically calculated and controlled; the light emission angle adjustment value is Δθ, and satisfies Δθ=K×(TH). current -TH ref ); where K is the proportionality coefficient, and the value of K ranges from 0.67° / μm to 2° / μm; TH ref The reference thickness is the metal foil to be tested.

[0013] After the adjustable angle light source module adjusts the light output angle, the image acquisition module acquires image data of the illuminated metal foil surface.

[0014] Based on the brightness changes of the defect area in the image data, the raised defects, recessed defects, and foreign objects on the surface of the metal foil are distinguished.

[0015] In one embodiment, the specific steps for controlling the light emission angle of the adjustable angle light source module include:

[0016] By using a blade-shaped light-blocking module set in the optical path of the adjustable angle light source module to block part of the incident light beam, a distinct light intensity variation boundary line is formed on the surface of the metal foil.

[0017] The logic for dynamically controlling the light emission angle is as follows: when the thickness data indicates an increase in thickness, the light emission angle is increased; when the thickness data indicates a decrease in thickness, the light emission angle is decreased.

[0018] In one embodiment, the method further includes a synchronization and positioning step: acquiring the transmission position information of the metal foil in real time through a high-precision encoder, and synchronizing the acquisition frequency of the image acquisition step with the position information;

[0019] In the defect analysis step, a secondary verification is also performed by combining the shape regularity and texture characteristics of the defect. Specifically, foreign object defects are characterized by regular geometric shapes or textures that are inconsistent with the substrate background; material deformation defects are characterized by irregular shapes and textures that are consistent with the substrate background.

[0020] On the other hand, this application provides a surface defect detection system for metal foil, comprising:

[0021] A roll-to-roll transport mechanism is used to transport the metal foil to be tested;

[0022] A film thickness detection mechanism is located at the entrance or the previous station of the roll-to-roll transport mechanism, and is used to measure the thickness data TH of the metal foil online in real time. current ;

[0023] An adjustable angle light source module is installed on one side of the roll-to-roll transport mechanism to provide illumination to the surface of the metal foil. The light emission angle of the adjustable angle light source module is adjustable.

[0024] An image acquisition module is installed on one side of the roll-to-roll transport mechanism, facing the surface of the metal foil, and is used to acquire image data of the surface of the metal foil.

[0025] Based on the real-time thickness data fed back by the film thickness detection mechanism, the light emission angle of the adjustable angle light source module is dynamically calculated and controlled, so that the microscopic unevenness or foreign matter on the surface of the metal foil is converted into brightness changes in the image acquired by the image acquisition module; wherein, the light emission angle adjustment value is Δθ, and satisfies Δθ=K×(TH) current -TH ref ); where K is the proportionality coefficient, and the value of K ranges from 0.67° / μm to 2° / μm; TH ref The reference thickness is the metal foil to be tested.

[0026] In one embodiment, the metal foil surface defect detection system further includes: a blade-shaped light-blocking module, which is disposed in the optical path of the adjustable angle light source module to block part of the incident light beam, so as to form a distinct light intensity variation boundary line on the surface of the metal foil.

[0027] In one embodiment, the metal foil surface defect detection system further includes: a high-precision encoder connected to the transport roller shaft of the roll-to-roll transport mechanism, used to acquire the transport position information of the metal foil in real time; and...

[0028] The central controller is communicatively connected to the high-precision encoder, the film thickness detection mechanism, the adjustable angle light source module, and the image acquisition module, and is used to synchronously control the metal foil surface defect detection system.

[0029] In one embodiment, the adjustable angle light source module is a high-brightness LED line light source, and its light emission angle is adjustable within the range of 0° to 90° by a motor drive.

[0030] In one embodiment, the blade-shaped light-blocking module blocks a portion of the incident light beam, causing the light intensity variation boundary line to appear as a clear light-dark boundary on the surface of the metal foil.

[0031] In one embodiment, the logic for the central controller to control the light emission angle of the adjustable angle light source module is as follows:

[0032] As the thickness of the metal foil increases, the light emission angle of the adjustable angle light source module increases;

[0033] When the thickness of the metal foil decreases, the light emission angle of the adjustable angle light source module decreases.

[0034] In one embodiment, the image acquisition module includes a high-resolution line scan camera whose acquisition frequency is synchronized with the position signal of the high-precision encoder to ensure that the image data corresponds one-to-one with the transmission position of the metal foil.

[0035] In one embodiment, the system further includes an image processing module connected to the image acquisition module and the central controller, used to analyze brightness changes and defect shapes in the image data to distinguish between protruding defects, dented defects, and foreign objects.

[0036] In one embodiment, the roll-to-roll transport mechanism, the high-precision encoder, the film thickness detection mechanism, the adjustable angle light source module, the blade light-shielding module, and the image acquisition module are all integrated on a C-shaped frame to maintain a stable relative position.

[0037] This application has at least the following advantages or beneficial effects:

[0038] 1. The metal foil surface defect detection method involved in this application dynamically adjusts the illumination angle of the light source by real-time monitoring of the thickness change of the foil under test, ensuring that the illumination conditions always match the geometric characteristics of the current material surface. This maintains a stable shadow projection relationship at the defect edge, enhances the contrast of micro-deformations (1.5μm–5μm level), and significantly improves the detection rate of minute defects. In this embodiment, by optimizing the brightness characteristic changes of the defect area under illumination, the system can distinguish between protrusions, depressions, and attached foreign matter on the metal foil surface based on the brightness changes of the defect area in the image data. In this embodiment, the provided technical solution effectively solves the balance problem of sensitivity, stability, and efficiency in precision metal foil defect detection through a thickness-adaptive dynamic illumination strategy, making it particularly suitable for high-precision mask manufacturing processes required in fields such as OLED displays and semiconductors. This application provides a detection scheme capable of online, high-speed, and accurate differentiation of micro-deformations and foreign matter on the surface of metal foil.

[0039] 2. The metal foil surface defect detection system disclosed in this application provides an adaptive optical detection condition by introducing a core control relationship: dynamically calculating and controlling the light emission angle of an adjustable angle light source module based on real-time thickness data fed back from a film thickness detection mechanism. The metal foil surface defect detection system no longer uses fixed illumination but actively adjusts the illumination angle according to the real-time physical state (thickness) of the material being measured. This allows extremely slight height differences caused by microscopic deformation of the metal foil surface to be selectively amplified into significant brightness differences in the image, thus solving the problems of insensitivity to microscopic deformation and low contrast in traditional static illumination, laying the optical foundation for high-sensitivity online detection.

[0040] 3. The metal foil surface defect detection system disclosed in this application introduces an active, high-gradient light intensity boundary into the modulated illumination path by adding a blade-shaped light-shielding module. By adjusting the amount of the adjustable-angle light source module blocked by the blade-shaped light-shielding module, a distinct light intensity gradient boundary can be formed at different locations on the metal foil surface. When the microscopic deformation (protrusion or depression) of the metal foil surface crosses this optical boundary, it causes a step change in local illumination conditions (suddenly moving from a bright area to a dark area, or vice versa), thereby converting height information into a brightness abrupt change signal with extremely high contrast in the image, greatly amplifying the detectability of defects.

[0041] The specific function of the blade-shaped light-blocking module includes blocking a portion of the incident light beam, which is an optimized design parameter. By blocking part of the incident light beam, the blade-shaped light-blocking module can preset the illumination state of the metal foil surface near a sensitive critical point. In this state, subsequent minute angle adjustments based on the thickness allow raised or recessed areas to quickly cross the light-dark boundary, thereby generating maximum brightness contrast, obtaining the optimal image signal-to-noise ratio, and enabling even weak defect signals to be clearly extracted.

[0042] 4. The metal foil surface defect detection system involved in this application also includes a high-precision encoder and a central controller, which are connected to each other to achieve synchronization of spatiotemporal information and centralized coordination of the system. The high-precision encoder provides accurate position tags, so that each piece of thickness data and image data has a unique position coordinate, enabling precise location and traceability of defects. The central controller, as the brain, uniformly schedules the timing and logic of thickness measurement, light source adjustment, and image acquisition, ensuring that the entire system works collaboratively as a closed loop, avoiding data misalignment or logical conflicts caused by independent operation of each component, and guaranteeing stability and reliability under high-speed continuous detection.

[0043] The central controller's control logic is as follows: as thickness increases, the incident angle increases; as thickness decreases, the incident angle decreases, transforming the adaptive dimming principle into a concrete, executable control algorithm. Its technical effect is to achieve directional optical marking of defect types: when a local area thickens (protrudes), increasing the angle allows for more coverage of the blade's shadow, causing the defect to first darken and then brighten in the image. When a local area thins (depresses), decreasing the angle increases the amount of light received, causing the defect to first brighten and then darken in the image. This not only detects defects but also directly reveals their physical properties (protrusion or depression) through brightness change trends, providing the most crucial and direct basis for subsequent automatic classification. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A flowchart of the method for detecting surface defects in metal foil provided in this application;

[0046] Figure 2 This is a schematic diagram illustrating the angle adjustment of surface defects in a metal foil, provided as an embodiment of this application.

[0047] Figure 3This is a schematic diagram illustrating the angle adjustment of another surface defect in a metal foil, provided in another embodiment of this application.

[0048] Figure 4 This is a schematic diagram of the structure of a metal foil surface defect detection system provided in one embodiment of this application;

[0049] Figure 5 This is a schematic diagram of the structure of a metal foil surface defect detection system provided in one embodiment of this application;

[0050] Figure 6 This is a schematic diagram of the structure of a metal foil surface defect detection system provided in another embodiment of this application;

[0051] Figure 7 This is a schematic diagram of the structure of a metal foil surface defect detection system provided in another embodiment of this application;

[0052] Figure 8 A cross-sectional schematic diagram of the surface defect detection system for metal foil provided in this application;

[0053] Figure 9 For the purposes of this application Figure 8 A schematic diagram of surface defects in the metal foil shown;

[0054] Figure 10 For the purposes of this application Figure 8 A schematic diagram showing the brightness changes in image data of surface defects on a metal foil.

[0055] Figure 11 A cross-sectional schematic diagram of the surface defect detection system for metal foil provided in this application;

[0056] Figure 12 For the purposes of this application Figure 11 A schematic diagram of surface defects in the metal foil shown;

[0057] Figure 13 For the purposes of this application Figure 11 A schematic diagram showing the brightness changes in image data of surface defects on a metal foil.

[0058] Figure 14 This is a schematic diagram of surface defects on metal foil obtained using a defect detection system in the prior art;

[0059] Figure 15 This is a schematic diagram of surface defects on a metal foil detected using the metal foil surface defect detection system provided in the embodiments of this application;

[0060] Figure 16 For the purposes of this application Figure 15The diagram shows the brightness variation of image data of surface defects on a metal foil.

[0061] Illustration: Metal Foil Surface Defect Detection System 100

[0062] Roll-to-roll transport mechanism 10, film thickness detection mechanism 20, adjustable angle light source module 30, blade light-blocking module 31, image acquisition module 40, high-precision encoder 50, central controller 60, and image processing module 70. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0064] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0065] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0066] In the description of this application, it should be noted that the terms "inner," "outer," "upper," "lower," "vertical," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0067] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, features in the following embodiments can be combined with each other.

[0068] In view of the shortcomings of the prior art, the technical solution of this application is proposed. The technical solution of this application will be described in detail below.

[0069] Please see Figure 1This application provides a method for detecting surface defects of metal foil, applied in the manufacturing process of metal photomasks, to detect microscopic deformation and foreign matter adhering to the metal foil.

[0070] Methods for detecting surface defects in metal foil include:

[0071] S10, the metal foil to be tested is transported via roll-to-roll transport mechanism 10. The metal foil to be tested has a nominal thickness TH. The metal foil to be tested is Invar alloy foil or an FMM product with holes. In one embodiment, the metal foil to be tested has a nominal thickness TH = 25 micrometers. The defect height detected by the film thickness detection mechanism is approximately 1.5 μm to 5 μm.

[0072] S20, the thickness data TH of the metal foil is measured online in real time by the film thickness detection mechanism 20. current .

[0073] S30, based on the thickness data THcurrent of the metal foil to be tested, dynamically calculate and control the light emission angle of the adjustable angle light source module 30. The light emission angle adjustment value is Δθ, and satisfies Δθ=K×(TH). current -TH ref ); where K is the proportionality coefficient. The value of K ranges from 0.67° / μm to 2° / μm; TH ref TH represents the reference thickness of the metal foil to be tested. ref It can be set to the nominal thickness TH, or TH ref It can be set to a fixed thickness, such as a fixed thickness value of 20 micrometers to 40 micrometers. The initial angle of the adjustable angle light source module is θ; the illumination angle of the adjustable angle light source module is θ + Δθ. Δθ can be a positive or negative value. The initial angle θ is in the range of 25° to 45°, and preferably in the range of 30° to 40°.

[0074] In this step, the scaling factor K represents the amount of illumination angle change required to compensate for a unit thickness change. When the thickness of the metal foil under test increases by ΔTH, the displacement of its surface in the vertical direction requires an adjustment of the light source angle Δθ to maintain the projection geometry of the illumination spot on the defect edge (i.e., the shadow effect) essentially unchanged.

[0075] In one embodiment, please refer to Figure 2 The film thickness testing agency 20 detected a change in the thickness of the metal foil under test at a certain location. current -TH ref =3.5μm, the scaling factor K is 1.2° / μm. The illumination angle of the adjustable angle light source module 30 is θ + Δθ = 30° + 3.5μm × 1.2° / μm = 30° + 4.2° = 34.2°

[0076] In one embodiment, please refer to Figure 3 The film thickness testing agency 20 detected a change in the thickness of the metal foil under test at a certain location. current -TH ref =-2.5μm, and the proportionality coefficient K is 1.5° / μm.

[0077] The illumination angle of the adjustable angle light source module 30 is θ + Δθ = 30° + (-1.5μm × 2.5° / μm) = 30° - 3.75° = 26.25°

[0078] S40: After the adjustable angle light source module 30 adjusts the light output angle, the image acquisition module 40 acquires image data of the illuminated metal foil surface.

[0079] S50, the central controller 60 distinguishes between raised defects, dented defects, and foreign objects on the surface of metal foil based on the brightness changes of the defect area in the image data.

[0080] In this embodiment, by monitoring the thickness change of the foil under test in real time, the illumination angle of the light source is dynamically adjusted to ensure that the illumination conditions always match the geometric characteristics of the current material surface. This maintains a stable shadow projection relationship at the defect edge, enhances the contrast of micro-deformations (1.5μm–5μm level), and significantly improves the detection rate of minute defects. This embodiment utilizes optimized brightness characteristic changes in the defect area under illumination; the system can distinguish between protrusions, depressions, and attached foreign matter on the metal foil surface based on the brightness changes in the defect area in the image data. In this embodiment, the provided technical solution effectively solves the balance problem of sensitivity, stability, and efficiency in precision metal foil defect detection through a thickness-adaptive dynamic illumination strategy, making it particularly suitable for high-precision mask manufacturing processes required in fields such as OLED displays and semiconductors. This application provides a detection scheme capable of online, high-speed, and accurate differentiation of micro-deformations and foreign matter on the surface of metal foil.

[0081] The roll-to-roll transport mechanism 10, film thickness detection mechanism 20, adjustable angle light source module 30, image acquisition module 40, and central controller 60 used in the above steps can all be selected from the components of the metal foil surface defect detection system 100 described below. The above-described metal foil surface defect detection method protects the core process flow for achieving high-sensitivity detection: transport-thickness measurement-dynamic lighting adjustment-acquisition-analysis. By serializing the action of dynamically controlling the illumination angle according to the real-time thickness into a mandatory process step, an adaptive optical environment is forcibly created during the detection process. This ensures that whoever implements the method can transform the challenge of detecting microstructures into a relatively easy-to-handle image brightness analysis problem through this series of steps, achieving high robustness and reproducibility of the detection method.

[0082] In one embodiment, the specific steps for controlling the light emission angle of the adjustable angle light source module 30 include: blocking part of the incident light beam by using a blade-shaped light-blocking module 31 disposed in the optical path of the adjustable angle light source module 30, so as to form a distinct light intensity variation boundary line on the surface of the metal foil. The logic for dynamically controlling the light emission angle is as follows: when the thickness data indicates an increase in thickness, the light emission angle is increased; when the thickness data indicates a decrease in thickness, the light emission angle is decreased.

[0083] In this embodiment, the method introduces a step of using a blade to block light and specific control logic for increasing thickness and angle, and decreasing thickness and angle. It explicitly protects two specific operational steps: enhancing contrast by forming light and dark boundaries, and marking defect types through directional dimming, thus making the implementation scheme more complete.

[0084] In one embodiment, the method for detecting surface defects of metal foil further includes a synchronization and positioning step: acquiring the transmission position information of the metal foil in real time through a high-precision encoder 50, and synchronizing the acquisition frequency of the image acquisition step with the position information.

[0085] In the defect analysis step, secondary verification is performed by combining the regularity of the defect's shape and texture characteristics. Specifically, foreign object defects are characterized by regular geometric shapes or textures that are inconsistent with the substrate background. Material deformation defects are characterized by irregular shapes and textures that are consistent with the substrate background.

[0086] This embodiment integrates two steps: "synchronous positioning" and "secondary verification." The "synchronous positioning" step (using an encoder for synchronous acquisition) ensures the accuracy of the method implementation, firmly binding the defect analysis results to the material location. The "secondary verification" step (combining shape and texture features) adds a redundant, morphology-based judgment level after the initial classification based on brightness. This effectively corrects misjudgments that may arise from a single brightness feature (e.g., misclassifying a regularly shaped protrusion as a foreign object). Through multi-dimensional feature cross-validation, the accuracy and reliability of the final defect classification are significantly improved, demonstrating the method's intelligent level.

[0087] Please see Figure 4 This application provides a surface defect detection system 100 for metal foil. For example... Figure 5 and Figure 6 The metal foil 100a shown can be made of Invar alloy. The metal foil surface defect detection system 100 includes: a roll-to-roll transport mechanism 10, a film thickness detection mechanism 20, an adjustable angle light source module 30, and an image acquisition module 40.

[0088] The roll-to-roll transport mechanism 10 is used to transport the metal foil to be tested. The film thickness detection mechanism 20 is located at the entrance or the previous station of the roll-to-roll transport mechanism 10 and is used to measure the thickness data of the metal foil online in real time. In one embodiment, the film thickness detection mechanism 20 is a non-contact online film thickness detection mechanism 20, which realizes thickness measurement based on X-ray or laser principles.

[0089] An adjustable-angle light source module 30 is mounted on one side of the roll-to-roll transport mechanism 10 to provide illumination to the surface of the metal foil. The light emission angle of the adjustable-angle light source module 30 is adjustable. An image acquisition module 40 is mounted on one side of the roll-to-roll transport mechanism 10, facing the surface of the metal foil, to acquire image data of the metal foil surface. In one embodiment, such as... Figure 5 As shown, the adjustable angle light source module 30 and the image acquisition module 40 can be arranged on the same side of the roll-to-roll transport mechanism 10 or on the central axis of the metal foil 100a transport direction. Figure 6 As shown, the adjustable angle light source module 30 and the image acquisition module 40 can be respectively disposed on both sides of the roll-to-roll transport mechanism 10 (in the width direction of the metal foil 100a). The adjustable angle light source module 30 emits light from one side of the metal foil 100a, and the image acquisition module 40 receives light from the other side of the metal foil 100a. Figure 5 and Figure 6 The first direction is the transmission direction of the metal foil 100a.

[0090] Based on the real-time thickness data fed back by the film thickness detection mechanism 20, the light emission angle of the adjustable angle light source module 30 is dynamically calculated and controlled, so that the microscopic unevenness or foreign matter on the surface of the metal foil is converted into brightness changes in the image acquired by the image acquisition module 40. The light emission angle adjustment value is Δθ, and satisfies Δθ=K×(TH). current -TH ref ); where K is the proportionality coefficient, and the value of K ranges from 0.67° / μm to 2° / μm; TH ref The reference thickness is the metal foil to be tested.

[0091] In this embodiment, by introducing a core control relationship—dynamically calculating and controlling the light emission angle of the adjustable angle light source module based on real-time thickness data fed back by the film thickness detection mechanism—and a special calculation process for the light emission angle adjustment value, an adaptive optical detection condition is provided. The metal foil surface defect detection system 100 no longer uses fixed illumination but actively adjusts the illumination angle according to the real-time physical state (thickness) of the material being tested. This allows extremely slight height differences caused by microscopic deformation on the surface of the metal foil 100a to be selectively amplified into significant brightness differences in the image, thus solving the problems of insensitivity to microscopic deformation and low contrast in traditional static illumination, laying the optical foundation for high-sensitivity online detection.

[0092] In one embodiment, see Figure 7 , Figure 8 and Figure 11 The metal foil surface defect detection system 100 also includes a blade-shaped light-blocking module 31. The blade-shaped light-blocking module 31 is disposed in the optical path of the adjustable angle light source module 30 and is used to block part of the incident light beam to form a distinct light intensity variation boundary line on the surface of the metal foil.

[0093] In this embodiment, by adding a blade-shaped light-blocking module 31, an active, high-gradient light intensity boundary is introduced into the modulated illumination path. By adjusting the amount of light blocking by the blade-shaped light-blocking module 31 on the adjustable-angle light source module 30, a distinct light intensity gradient boundary line can be formed at different positions on the surface of the metal foil 100a. When the microscopic deformation (protrusion or depression) on the surface of the metal foil 100a crosses this optical boundary, it causes a step change in local illumination conditions (suddenly moving from a bright area to a dark area, or vice versa), thereby converting height information into a brightness abrupt change signal with extremely high contrast in the image, greatly amplifying the detectability of defects.

[0094] Please see Figure 7 In one embodiment, the metal foil surface defect detection system 100 further includes a high-precision encoder 50 and a central controller 60. Figure 7 The thinner connecting lines indicate mechanical connections or positional installation relationships. Figure 7 Thicker connecting lines indicate electrical, signal, or data connections. The high-precision encoder 50 is connected to the conveyor rollers of the roll-to-roll conveyor mechanism 10 to acquire real-time conveying position information of the metal foil. The central controller 60 is communicatively connected to the high-precision encoder 50, the film thickness detection mechanism 20, the adjustable angle light source module 30, and the image acquisition module 40 to synchronously control the metal foil surface defect detection system 100.

[0095] In this embodiment, the metal foil surface defect detection system 100 also includes a high-precision encoder 50 and a central controller 60, which are connected to each other to achieve synchronization of spatiotemporal information and centralized coordination of the system. The high-precision encoder 50 provides accurate position tags, so that each piece of thickness data and image data has a unique position coordinate, enabling precise location and traceability of defects. The central controller 60 acts as the brain, uniformly scheduling the timing and logic of thickness measurement, light source adjustment, and image acquisition, ensuring that the entire system works collaboratively as a closed loop, avoiding data misalignment or logical conflicts caused by independent operation of each component, and guaranteeing stability and reliability under high-speed continuous detection.

[0096] In one embodiment, the adjustable angle light source module 30 is a high-brightness LED line light source, and its light emission angle is adjustable in the range of 0° to 90° by a motor drive.

[0097] In this embodiment, the adjustable angle light source module 30 is specifically defined as a motor-driven high-brightness LED line light source with an adjustable light emission angle from 0° to 90°, enabling higher performance and greater adaptability. The high-brightness LED meets the illumination intensity required for high-speed line scanning. The motor drive enables rapid and precise angle adjustment over a wide range from 0° to 90°, allowing the metal foil surface defect detection system 100 to adapt to the detection needs of materials with different thicknesses and reflective properties, providing ample adjustment space to achieve optimal illumination effects.

[0098] In one embodiment, the blade-shaped light-blocking module 31 blocks part of the incident light beam, so that the light intensity variation boundary line appears as a clear light-dark boundary on the surface of the metal foil.

[0099] In this embodiment, the specific function of the blade-shaped light-blocking module 31 includes blocking a portion of the incident light beam, which is an optimized design parameter. By blocking a portion of the incident light beam, the blade-shaped light-blocking module 31 can preset the surface illumination state of the metal foil 100a near a sensitive critical point. In this state, subsequent minute angle adjustments based on the thickness allow raised or recessed areas to quickly cross the light-dark boundary, thereby generating maximum brightness contrast, obtaining the optimal image signal-to-noise ratio, and enabling even weak defect signals to be clearly extracted.

[0100] In one embodiment, the logic of the central controller 60 controlling the light emission angle of the adjustable angle light source module 30 is as follows: when the thickness of the metal foil 100a increases, the light emission angle of the adjustable angle light source module 30 is increased, that is, the incident angle illuminating the surface of the metal foil 100a under test is increased. When the thickness of the metal foil 100a decreases, the light emission angle of the adjustable angle light source module 30 is decreased, that is, the incident angle illuminating the surface of the metal foil 100a under test is decreased.

[0101] In this embodiment, the control logic of the central controller 60 is defined as follows: as thickness increases, the incident angle increases; as thickness decreases, the incident angle decreases, transforming the adaptive dimming principle into a specific, executable control algorithm. The technical effect is the realization of directional optical marking of defect types: when a local area thickens (protrudes), increasing the angle allows for greater coverage of the blade's shadow, causing the defect to first darken and then brighten in the image. When a local area thins (depresses), decreasing the angle increases the amount of light received, causing the defect to first brighten and then darken in the image. This not only detects defects but also directly reveals their physical properties (protrusion or depression) through brightness change trends, providing the most crucial and direct basis for subsequent automatic classification.

[0102] In one embodiment, the image acquisition module 40 includes a high-resolution line scan camera whose acquisition frequency is synchronized with the position signal of the high-precision encoder 50 to ensure that the image data corresponds one-to-one with the transmission position of the metal foil.

[0103] In this embodiment, the image acquisition module 40 is specifically defined as a high-resolution line scan camera whose acquisition frequency is synchronized with the position signal of the high-precision encoder 50, achieving a strict mapping between the image and the physical space. High resolution ensures excellent detail capture. Synchronization with the encoder ensures that even with fluctuations in transmission speed, each line of image precisely corresponds to a fixed length unit on the material, thereby eliminating image distortion and enabling accurate calculation of the actual size and location coordinates of defects. This is crucial for achieving quantitative and traceable online inspection.

[0104] In one embodiment, the metal foil surface defect detection system 100 further includes an image processing module 70. The image processing module 70 is connected to the image acquisition module 40 and the central controller 60, respectively, and is used to analyze the brightness changes and defect shapes in the image data to distinguish between raised defects, dented defects, and foreign objects.

[0105] In one embodiment, the image processing module 70 classifies defects based on the brightness variation trend of the defect area: when the defect area first darkens and then brightens, it is identified as a raised defect; when the defect area first brightens and then darkens, it is identified as a recessed defect; and when the brightness of the defect area does not change but exhibits a regular or irregular shape, it is identified as a foreign object defect. More specifically, foreign object defects are characterized by regular geometric shapes or textures inconsistent with the substrate background; material deformation defects are characterized by irregular shapes and textures consistent with the substrate background.

[0106] In one embodiment, the image processing module 70 further performs secondary verification by combining the shape and texture regularity of the defect, wherein the foreign object defect has a regular geometric shape or unique texture, while the material deformation defect has the same material texture but an irregular shape.

[0107] In this embodiment, the addition of an image processing module 70 enables a shift from image acquisition to intelligent decision-making. The image processing module 70 automatically analyzes directional brightness changes in image data and, combined with defect shape features, executes multi-feature fusion defect classification logic. The metal foil surface defect detection system 100 can automatically identify areas that darken first and then brighten as protrusions, areas that brighten first and then darken as depressions, and areas with no brightness change but a shape as foreign objects. This replaces the human eye in achieving rapid, objective, and consistent defect judgment and classification, greatly improving detection efficiency and automation.

[0108] In one embodiment, the roll-to-roll transport mechanism 10, the high-precision encoder 50, the film thickness detection mechanism 20, the adjustable angle light source module 30, the blade light-shielding module 31, and the image acquisition module 40 are all integrated on a C-shaped frame to maintain a stable relative position.

[0109] In this embodiment, by integrating all key components onto a C-shaped frame, the system's rigidity and stability are improved. The roll-to-roll transport mechanism 10, high-precision encoder 50, film thickness detection mechanism 20, adjustable angle light source module 30, blade-edge light-shielding module 31, and image acquisition module 40, along with the relative positions of these components and the metal foil 100a, are physically locked to form a robust metal foil surface defect detection system 100. This effectively resists environmental interference such as on-site vibration and thermal deformation, maintains long-term optical path calibration accuracy, thereby ensuring long-term consistency and reliability of detection performance, and reducing maintenance frequency and calibration difficulty.

[0110] In one specific embodiment, the metal foil surface defect detection system 100 or the metal foil surface defect detection system method provided in any of the above embodiments of this application are adopted. By integrating film thickness detection and active dimming technology, high-precision and high-efficiency online differentiation and detection of micro-deformation (concave and convex deformation) and foreign objects are achieved.

[0111] like Figure 8 The figure shown is a cross-sectional schematic diagram of a metal foil surface defect detection system according to an embodiment of this application for surface defect detection. Figure 8 The metal foil 100a under test moves along a first direction. An adjustable-angle light source module 30 provides illumination to the surface of the metal foil, and the light emission angle of the adjustable-angle light source module 30 is adjustable. A blade-shaped light-blocking module 31 is disposed in the optical path of the adjustable-angle light source module 30 to block part of the incident beam, thereby forming a distinct light intensity variation boundary line on the surface of the metal foil 100a. It can be understood that the blade-shaped light-blocking module 31 can continuously move at a specific speed during the process of the adjustable-angle light source module 30 detecting the entire surface of the metal foil 100a. An image acquisition module 40 faces the surface of the metal foil 100a (disposed on the upper surface of the metal foil 100a) and is used to acquire image data of the metal foil surface. Based on the image data acquired by the image acquisition module 40, it can be clearly determined that the surface of the metal foil 100a under test is uneven. Figure 9 The image shows a schematic diagram of surface defects in the metal foil 100a to be tested. Figure 10 The image shown is a schematic diagram of the brightness variation of the image data of the surface defects of metal foil 100a. Figure 10 The defective area first darkens and then brightens, therefore this defective area is a raised defect.

[0112] like Figure 11The figure shown is a cross-sectional schematic diagram of a metal foil surface defect detection system according to another embodiment of this application for surface defect detection. Figure 11 The metal foil 100a under test moves along a first direction. An adjustable-angle light source module 30 provides illumination to the surface of the metal foil, and the light emission angle of the adjustable-angle light source module 30 is adjustable. A blade-shaped light-blocking module 31 is disposed in the optical path of the adjustable-angle light source module 30 to block part of the incident beam, thereby forming a distinct light intensity variation boundary line on the surface of the metal foil 100a. It can be understood that the blade-shaped light-blocking module 31 can continuously move at a specific speed during the process of the adjustable-angle light source module 30 detecting the entire surface of the metal foil 100a. An image acquisition module 40 faces the surface of the metal foil 100a (disposed on the upper surface of the metal foil 100a) and is used to acquire image data of the metal foil surface. Based on the image data acquired by the image acquisition module 40, it can be clearly determined that the surface of the metal foil 100a under test is uneven. Figure 12 The image shows a schematic diagram of surface defects in the metal foil 100a to be tested. Figure 13 The image shown is a schematic diagram of the brightness variation of the image data of the surface defects of metal foil 100a. Figure 13 The defective area first brightens and then darkens, therefore this defective area is a depression defect.

[0113] Please compare and refer to the following: Figure 14 and Figure 15 , Figure 14 This is a schematic diagram of surface defects on metal foil obtained using a defect detection system in the prior art. Figure 15 This is a schematic diagram showing surface defects on a metal foil detected using the metal foil surface defect detection system provided in this application. Figure 14 and Figure 15 The metal foils tested were all from the same piece of metal foil. Figure 14 The images are taken using existing automatic optical inspection (AOI) systems based on line scan cameras (images taken from only one incident angle). Figure 14 Only one defect can be seen, but it is impossible to determine whether it is a dent, a bulge, or a foreign object. Figure 15 Image data of the surface of a metal foil obtained by the metal foil surface defect detection system 100 provided in the embodiments of this application. Figure 15 There are three obvious defects. Figure 15 The three defects are marked with different colors. Figure 15 The three defects are converted into brightness changes in the image acquired by the image acquisition module, such as... Figure 16As shown, the brightness changes of the three defect points are all initially brighter and then darker, therefore all three defect points are concave defects. In this embodiment, during the detection of the three defect points, the film thickness detection mechanism 20 first detects a thickness change at a certain coordinate point, and then the adjustable angle light source module 30 provides illumination to the surface of the metal foil. The image acquisition module 40 acquires image data of the surface of the metal foil. The central controller 60 dynamically calculates and controls the light emission angle of the adjustable angle light source module 30 based on the real-time thickness data fed back by the film thickness detection mechanism 20, so that the microscopic unevenness or foreign matter on the surface of the metal foil is converted into brightness changes in the image acquired by the image acquisition module 40. Based on the brightness changes in the image acquired by the image acquisition module 40, the defect type (protruding defect, concave defect, and foreign matter) can be quickly and accurately determined. Figure 16 The three different colored curves represent respectively Figure 15 Brightness variation curves of three different colored defect points ( Figure 16 The brightness variation curves of the three different colored defect points were obtained from three separate tests, and the final result was obtained by integrating them according to the brightness ratio. Figure 16 The brightness variation curves of the three different colored defect points can also distinguish the depth of the three dents.

[0114] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0115] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for detecting surface defects in metal foil, characterized in that, include: The metal foil to be tested is transferred via a roll-to-roll transport mechanism; The thickness data of the metal foil is measured online in real time by a film thickness testing agency. current ; Based on the thickness data TH of the metal foil to be tested current Dynamically calculate and control the light output angle of the adjustable angle light source module; The light emission angle adjustment value is Δθ, and it satisfies Δθ=K×(TH) current -TH ref ); where K is the proportionality coefficient, and the value of K ranges from 0.67° / μm to 2° / μm; TH ref The reference thickness is the metal foil to be tested. After the adjustable angle light source module adjusts the light output angle, the image acquisition module acquires image data of the illuminated metal foil surface. Based on the brightness changes of the defect area in the image data, the raised defects, recessed defects and foreign objects on the surface of the metal foil are distinguished. The specific steps for controlling the light emission angle of the adjustable angle light source module include: By using a blade-shaped light-blocking module set in the optical path of the adjustable angle light source module to block part of the incident light beam, a distinct light intensity variation boundary line is formed on the surface of the metal foil.

2. The method for detecting surface defects of metal foil according to claim 1, characterized in that, The method further includes a synchronization and positioning step: acquiring the transmission position information of the metal foil in real time through a high-precision encoder, and synchronizing the acquisition frequency of the image acquisition step with the position information; In the defect analysis step, a secondary verification is also performed by combining the shape regularity and texture characteristics of the defect. Specifically, foreign object defects are characterized by regular geometric shapes or textures that are inconsistent with the substrate background; material deformation defects are characterized by irregular shapes and textures that are consistent with the substrate background.

3. A surface defect detection system for metal foil, characterized in that, include: A roll-to-roll transport mechanism is used to transport the metal foil to be tested; A film thickness detection mechanism is located at the entrance or the previous station of the roll-to-roll transport mechanism, and is used to measure the thickness data TH of the metal foil online in real time. current ; An adjustable angle light source module is installed on one side of the roll-to-roll transport mechanism to provide illumination to the surface of the metal foil. The light emission angle of the adjustable angle light source module is adjustable. An image acquisition module is installed on one side of the roll-to-roll transport mechanism, facing the surface of the metal foil, and is used to acquire image data of the surface of the metal foil. Based on the real-time thickness data fed back by the film thickness detection mechanism, the light emission angle of the adjustable angle light source module is dynamically calculated and controlled, so that the microscopic unevenness or foreign matter on the surface of the metal foil is converted into brightness changes in the image acquired by the image acquisition module; wherein, the light emission angle adjustment value is Δθ, and satisfies Δθ=K×(TH) current -TH ref ); where K is the proportionality coefficient, and the value of K ranges from 0.67° / μm to 2° / μm; TH ref The reference thickness is the metal foil to be tested. The metal foil surface defect detection system further includes: a blade-shaped light-shielding module, which is disposed in the optical path of the adjustable angle light source module to block part of the incident light beam, so as to form a distinct light intensity variation boundary line on the surface of the metal foil.

4. The metal foil surface defect detection system according to claim 3, characterized in that, Also includes: A high-precision encoder is connected to the transmission roller shaft of the roll-to-roll transmission mechanism to acquire the transmission position information of the metal foil in real time. as well as, The central controller is communicatively connected to the high-precision encoder, the film thickness detection mechanism, the adjustable angle light source module, and the image acquisition module, and is used to synchronously control the metal foil surface defect detection system.

5. The metal foil surface defect detection system according to claim 4, characterized in that, The adjustable angle light source module is a high-brightness LED line light source, and its light emission angle is adjustable within the range of 0° to 90° by motor drive.

6. The metal foil surface defect detection system according to claim 3, characterized in that, The blade-shaped light-blocking module blocks part of the incident light beam, making the light intensity variation boundary line appear as a clear light-dark boundary on the surface of the metal foil.

7. The metal foil surface defect detection system according to claim 4, characterized in that, The logic for the central controller to control the light output angle of the adjustable angle light source module is as follows: As the thickness of the metal foil increases, the light emission angle of the adjustable angle light source module increases; When the thickness of the metal foil decreases, the light emission angle of the adjustable angle light source module decreases.

8. The metal foil surface defect detection system according to claim 4, characterized in that, The image acquisition module includes a high-resolution line scan camera, whose acquisition frequency is synchronized with the position signal of the high-precision encoder to ensure that the image data corresponds one-to-one with the transmission position of the metal foil.

9. The metal foil surface defect detection system according to claim 5, characterized in that, Also includes: An image processing module, connected to the image acquisition module and the central controller, is used to analyze the brightness changes and defect shapes in the image data to distinguish between protruding defects, dented defects, and foreign objects.

10. The metal foil surface defect detection system according to claim 4, characterized in that, The roll-to-roll transmission mechanism, the high-precision encoder, the film thickness detection mechanism, the adjustable angle light source module, the blade light-shielding module, and the image acquisition module are all integrated on a C-shaped frame to maintain a stable relative position.

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