PDLC film defect detection system, defect detection method and production process optimization method

Abstract

The present invention discloses a PDLC film defect detection system, a defect detection method, and a production process optimization method, belonging to the field of PDLC technology. The PDLC film defect detection system includes a carrier, a front-view camera group, two side-view camera groups, and a power-on device; the power-on device is used to energize the PDLC film and adjust the power-on voltage to switch the PDLC film between an atomized state, a semi-transparent state, and a transparent state; the front-view camera group and the two side-view camera groups are used to capture detection images of the PDLC film in the atomized state, the semi-transparent state, and the transparent state. By combining a power-on device that can accurately control the state of the PDLC film with a multi-angle imaging system, the present invention can image defects with different optical characteristics in their respective most easily detected states. This effectively overcomes the problem of the prior art that different types of defect detection conditions are mutually exclusive and difficult to detect simultaneously due to the scattering, interference, polarization, and other characteristics of light, and significantly reduces the missed detection rate of defects.

Description

Technical Field

[0001] The present invention belongs to the field of PDLC technology, and in particular relates to a PDLC film defect detection system, a defect detection method and a production process optimization method. Background Art

[0002] Polymer dispersed liquid crystal, also known as PDLC (polymer dispersed liquid crystal), consists of liquid crystals dispersed in micron-sized droplets within an organic solid polymer matrix. Because the optical axes of the liquid crystal molecules in the droplets are freely oriented, their refractive index does not match that of the matrix. When light passes through the matrix, it is strongly scattered by the droplets, resulting in an opaque, milky white or translucent state. Applying an electric field adjusts the optical axis orientation of the liquid crystal droplets. When the refractive indices match, the display becomes transparent. Removing the electric field returns the droplets to their original scattered light state, allowing for display.

[0003] PDLC film is produced by coating a polymer dispersed liquid crystal layer between two layers of PET-ITO film and then curing it with light. Electrodes are formed on the upper and lower conductive layers of the film. When energized, the PDLC film becomes transparent, while when de-energized, it appears foggy. Due to the scattering, interference, and polarization properties of light, different defects often have mutually exclusive properties during detection. Therefore, existing technologies often struggle to simultaneously detect all defects in PDLC films, resulting in a high rate of missed detections. This has become a pressing issue for those skilled in the art.

[0004] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or public known technology. Summary of the Invention

[0005] The present invention provides a PDLC film defect detection system, a defect detection method and a production process optimization method, which at least solve the problem that the existing technology cannot detect common defects at the same time and has a high missed detection rate.

[0006] In order to achieve the above-mentioned objectives, in a first aspect, the present invention provides a PDLC film defect detection system, comprising a carrier, a front-view camera group, two side-view camera groups and a power-on device; the carrier is used to carry the PDLC film; the front-view camera group is arranged above the carrier, and the optical axis of the front-view camera group is perpendicular to the carrier; the two side-view camera groups are also arranged above the carrier, and the two side-view camera groups are respectively arranged on both sides of the front-view camera group, and the optical axes of the side-view camera groups are at a preset angle to the carrier; the power-on device is used to energize the PDLC film and adjust the power-on voltage so that the PDLC film can switch between an atomized state, a translucent state and a transparent state; the carrier is located within the shooting range of the front-view camera group and the side-view camera group, and the front-view camera group and the two side-view camera groups are used to shoot detection images of the PDLC film in an atomized state, a translucent state and a transparent state.

[0007] Preferably, the power supply voltage range of the power supply device is 0-65V; when the power supply voltage is 0V, the PDLC film is in an atomized state; when the power supply voltage is 10-25V, the PDLC film is in a translucent state; when the power supply voltage is 65V, the PDLC film is in a transparent state.

[0008] Preferably, an illumination device is provided below the carrier, and the illumination device is used to provide a vertically upward surface light source to the carrier; the light source intensity of the illumination device is adjusted within the range of 1000-20000 lux.

[0009] Preferably, the preset angle between the optical axis of each side-view camera group and the carrier is independently adjusted within 30-90°.

[0010] Preferably, the front-view camera group includes at least two front-view cameras arranged at intervals, and each side-view camera group includes at least two side-view cameras arranged at intervals; any position on the platform is within the shooting range of at least one front-view camera and at least two different side-view cameras.

[0011] Preferably, both the front view camera and the side view camera have a pixel count of 65 million or more, and a recognition accuracy of less than 0.01 mm.

[0012] Preferably, the carrier is made of high-transmittance glass, and the flatness is controlled to be below ±0.5mm.

[0013] Preferably, the detection system also includes a transmission device, a defect marking device, two adjustment devices and a control device; the transmission device is used to input and output the PDLC film into and out of the carrier; the defect marking device is arranged on the exit side of the carrier, and the defect marking device is used to mark the defect position on the PDLC film; the two side-view camera groups are respectively arranged on the two adjustment devices, and the adjustment devices are used to adjust the preset angle between the optical axis of the side-view camera group and the carrier; the control device is electrically connected to the front-view camera group, the side-view camera group, the power-on device, the transmission device, the defect marking device, and the adjustment device, and the control device is used to receive the detection images taken by the front-view camera group and the side-view camera group and analyze them to obtain the type, quantity and position of the defects.

[0014] In a second aspect, the present invention provides a PDLC film defect detection method, which is applied to the above-mentioned PDLC film defect detection system, and the detection method includes:

[0015] Place the PDLC film on a carrier;

[0016] The PDLC film is powered by a power supply device and the power supply voltage is adjusted to switch the PDLC film between an atomized state, a semi-transparent state, and a transparent state.

[0017] A front view camera group and two side view camera groups are used to capture detection images of the PDLC film in the atomized state, translucent state, and transparent state respectively.

[0018] Preferably, the side-view camera group captures detection images of uneven liquid crystal distribution defects and specific liquid crystal orientation defects of the PDLC film in a translucent state;

[0019] The front-view camera group captures the detection image of the completely opaque defects of the PDLC film in its transparent state;

[0020] The front-view camera group captures the detection image of the completely light-transmitting defect of the PDLC film in the atomized state.

[0021] Preferably, the detection method also includes adjusting the preset angle between the optical axis of the side-view camera group and the carrier through an adjustment device; when taking the detection image of the uneven distribution defect of the liquid crystal, the preset angle between the optical axis of the two side-view camera groups and the carrier is independently adjusted to 60-90°.

[0022] Preferably, when capturing detection images of specific orientation defects of liquid crystal, the angle between the optical axes of the two side-view camera groups is adjusted to 90°.

[0023] Preferably, the detection method also includes providing a vertically upward surface light source to the carrier through an illumination device, and adjusting the light source intensity of the illumination device during shooting; when shooting the detection image of the uneven distribution defect of the liquid crystal, adjusting the light source intensity of the illumination device to 8000-15000 lux.

[0024] Preferably, when capturing the detection image of the specific orientation defect of the liquid crystal, the light source intensity of the lighting device is adjusted to 1000-8000 lux.

[0025] Preferably, when capturing detection images of completely opaque defects and completely translucent defects, the light source intensity of the lighting device is adjusted to 15,000-20,000 lux.

[0026] Preferably, when the PDLC film is in a semi-transparent state, at least two different voltage values ​​are used to capture detection images of liquid crystal uneven distribution defects and liquid crystal specific orientation defects.

[0027] Preferably, the at least two different voltage values ​​include at least one voltage value selected from each of a first voltage interval and a second voltage interval, the power-on voltage in the first voltage interval is 10-15V, and the power-on voltage in the second voltage interval is 20-25V.

[0028] Preferably, the detection method also includes using a 10-15V voltage to shoot when shooting the detection image of the uneven distribution defect of the liquid crystal, adjusting the preset angle between the optical axis of the two side-view camera groups and the carrier to 60-90°, and adjusting the light source intensity of the lighting device to 8000-15000 lux.

[0029] Preferably, when capturing detection images of specific orientation defects of liquid crystals, a voltage of 20-25V is used for capturing, the angle between the optical axes of the two side-view camera groups is adjusted to 90°, and the light source intensity of the lighting device is adjusted to 1000-8000 lux.

[0030] In a third aspect, the present invention provides a method for optimizing a PDLC film production process, comprising the following steps:

[0031] Use PDLC film defect detection system to obtain defect types;

[0032] According to the preset defect type mapping relationship library, the defect type is converted into the corresponding process abnormality item;

[0033] The PDLC film production process is optimized based on process anomalies.

[0034] The beneficial effects of the present invention are:

[0035] 1. By combining an energizing device that precisely controls the state of the PDLC film with a multi-angle imaging system, the present invention is able to image defects with different optical properties in their most easily detectable states. This effectively overcomes the existing challenges of mutually exclusive defect detection conditions and difficulty in simultaneous detection due to light scattering, interference, polarization, and other characteristics. This significantly reduces the missed defect detection rate, reaching over 95%. This invention avoids the problems of missed defects caused by individual perception differences and operator fatigue in manual inspection, as well as the problem of conventional visual inspection that only identifies severe defects but has a low detection rate for minor defects.

[0036] 2. The system integrates an adjustable light source and an adjustable-angle side-view camera array, enabling dynamic optimization based on the specific defect type and desired imaging conditions. This ensures accurate and consistent switching of the PDLC film state, creating an optimal optical background for the clear visualization of each defect. The lighting device utilizes a vertically directed surface light source. Its area, height, and illumination can be measured and dynamically adjusted based on the actual imaging uniformity, contrast, and clarity, providing uniform illumination across the entire area and effectively minimizing the impact of shadows and reflections on image quality.

[0037] 3. The present invention utilizes a front-view camera system and dual side-view camera systems, with the number and spatial arrangement of cameras designed to ensure that any position on the PDLC film on the stage is covered by at least one front-view camera and at least two side-view cameras from different directions, forming a three-dimensional imaging network that effectively eliminates blind spots in inspection. The combined use of ultra-high-resolution cameras with 65 megapixels or higher (adjustable camera height and angle) and a highly flat, high-transmittance glass stage (which significantly improves inspection accuracy and stability, while the high-transmittance glass material effectively reduces light reflection, further enhancing imaging quality) significantly enhances the ability to identify minute defects and the accuracy of imaging. Furthermore, the entire inspection is conducted in a darkroom (light shield) to isolate ambient light interference and ensure stable imaging conditions.

[0038] 4. The image processing algorithm integrated within the control device of this invention (combined with camera pixel grayscale values ​​greater than 20) efficiently analyzes multi-angle image information captured by the front-view and side-view camera groups under different conditions. By comparing these images with a pre-set database model, the algorithm accurately identifies the type, number, size, and location of defects, effectively improving image processing speed and accuracy and reducing the incidence of misjudgments (over-inspections).

[0039] 5. This invention features an NG marking assembly (defect marking device) that quickly and accurately marks the locations of identified defects after product inspection and rewinding. This design greatly facilitates subsequent repair or sorting processes, significantly improving production efficiency and repair location accuracy.

[0040] 6. This invention achieves precise adaptation of defect detection conditions through a three-dimensional dynamic synergy of voltage regulation, camera angle optimization, and light source intensity adjustment. For uneven liquid crystal distribution defects, a low voltage of 10-15V is used to excite asymmetric scattering properties, combined with a 60-90° wide-angle side-view camera and a strong light source of 8000-15000 lux to significantly amplify the radial light intensity gradient of the defect. For specific liquid crystal orientation defects, a high voltage of 20-25V is used to enhance directional characteristics, anisotropic structures are captured through a 90° orthogonal camera layout, and a weak light source of 1000-8000 lux is controlled to avoid overexposure of details. These three synergistic mechanisms overcome the limitations of single-parameter detection, significantly improving defect detection and recognition rates and effectively reducing the rate of false positives.

[0041] 7. The PDLC film production process optimization method of the present invention forms a closed-loop system of "detection-analysis-feedback-optimization". On the one hand, relying on a high defect detection rate of more than 95%, it ensures that the optimization basis covers the vast majority of process omissions; on the other hand, by quantifying the mapping relationship between defects and process parameters, it directly identifies production process problems, significantly improving the targeting and timeliness of process adjustments, and achieving continuous improvement in PDLC film yield and lean control of the production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0043] Figure 1 A schematic structural diagram of a PDLC film defect detection system provided by an embodiment of the present invention;

[0044] Figure 2 A schematic structural diagram of a PDLC film defect detection system with a light shield provided in an embodiment of the present invention;

[0045] Figure 3 The detection image of the halo point detected in Example 1 of the present invention;

[0046] Figure 4 This is a detection image of regular coating marks detected in Example 1 of the present invention.

[0047] Description of reference numerals:

[0048] 10. Carrier; 20. Front-view camera group; 30. Side-view camera group; 40. Illumination device; 50. Conveying device; 51. Feeding air shaft; 52. Feeding support platform; 53. Discharging support platform; 54. Discharging air shaft; 60. Defect marking device; 61. Linear module; 62. Telescopic part; 63. Marking part; 70. Light shield. DETAILED DESCRIPTION

[0049] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" are generally understood in conjunction with the directions shown in the drawings and actual applications.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0051] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0052] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined to form one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein. The terms "optional" and "optional" mean that a range may or may not be included (or may or may not be present).

[0053] like Figure 1As shown, the present invention provides a PDLC film defect detection system, including a carrier 10, a front view camera group 20, two side view camera groups 30 and a power supply device (not shown in the figure); the carrier 10 is used to carry the PDLC film; the front view camera group 20 is arranged above the carrier 10, and the optical axis of the front view camera group 20 is perpendicular to the carrier 10; the two side view camera groups 30 are also arranged above the carrier 10, and the two side view camera groups 30 are respectively arranged on both sides of the front view camera group 20, and the optical axes of the side view camera groups 30 are at a preset angle to the carrier 10; the power supply device is used to energize the PDLC film and adjust the power supply voltage so that the PDLC film can switch between an atomized state, a translucent state and a transparent state; the carrier 10 is located within the shooting range of the front view camera group 20 and the side view camera group 30, and the front view camera group 20 and the two side view camera groups 30 are used to capture detection images of the PDLC film in an atomized state, a translucent state and a transparent state.

[0054] By combining an energizing device that precisely controls the state of the PDLC film with a multi-angle imaging system, the present invention can image defects with different optical properties in the most easily detectable state for each. This effectively overcomes the existing problem of mutually exclusive detection conditions for different defect types, making simultaneous detection difficult due to light scattering, interference, and polarization, significantly reducing the rate of missed defects.

[0055] It should be noted that existing technologies typically only feature front-view cameras or side-view cameras, and typically only detect a specific defect. Research on simultaneous detection of two or more defects is rare. In reality, PDLC film inspection involves numerous considerations. Due to the birefringence of the liquid crystal in PDLC products, different defect detection environments vary, depending on the site environment, camera height, angle, pixel count, recognition accuracy, camera combination, software algorithms, light source (illuminance, height, type), and the type and flatness of the inspection surface. Existing technologies often only detect a subset of defects, failing to accurately and comprehensively identify all defects and, consequently, unable to tailor production processes, require targeted development of PDLC defect detection equipment. This application simultaneously detects multiple defects, primarily through the coordinated use of multi-angle camera imaging and the rational manipulation of the PDLC film's state. However, existing technologies rarely investigate modifying the PDLC film's state to aid in the detection of different defects, and further research on combining the two for coordinated detection is completely lacking.

[0056] Preferably, the power supply voltage range of the power supply device is 0-65V; when the power supply voltage is 0V, the PDLC film is in an atomized state; when the power supply voltage is 10-25V, the PDLC film is in a translucent state; when the power supply voltage is 65V, the PDLC film is in a transparent state.

[0057] It is understood that the state change of the PDLC (polymer dispersed liquid crystal) film is mainly based on the change in the orientation of the liquid crystal molecules under the action of an electric field. Without being limited by theory, the principles anticipated by the present invention are as follows:

[0058] 1. Atomized State: When the PDLC film is de-energized (i.e., at 0V), the liquid crystal molecules freely orient within the polymer matrix, resulting in a refractive index mismatch with the matrix. Light passing through is strongly scattered, resulting in an opaque, milky-white appearance known as atomized state. In this atomized state, the PDLC film appears opaque and milky-white, strongly scattering light. In this state, completely transparent defects (such as transparent spots, blocks, or lines not coated with liquid crystal) become more easily detected due to the contrast with the surrounding scattered light.

[0059] 2. Translucent State: When a voltage within a certain range (e.g., 10-25V) is applied to the PDLC film, it exhibits a mixed state where some liquid crystals are aligned and some are disordered. This causes some light to still be scattered, but the degree of scattering is reduced, resulting in a translucent state. In this translucent state, the PDLC film scatters light less, allowing some light to pass through. In this state, defects such as uneven liquid crystal distribution (e.g., irregular coating lines and halo spots) and specific liquid crystal orientation defects (e.g., regular coating marks and tube bottom marks) create a unique optical effect due to the partial orientation of the liquid crystal molecules, making them more easily captured by side-view cameras.

[0060] 3. Transparent State: When a high voltage (e.g., 65V) is applied, the liquid crystal molecules are completely controlled by the electric field, aligning parallel to the field. At this point, the refractive index of the liquid crystal matches that of the polymer matrix, and light passes through with little scattering, resulting in a transparent state. In the transparent state, the PDLC film scatters almost no light, allowing it to pass completely through. In this state, completely opaque defects (e.g., ablation spots and black spots) become easily detectable by a normal-viewing camera due to the contrast with the surrounding transparent areas.

[0061] The PDLC film switches between atomized, translucent, and transparent states, leveraging the interaction between light and the PDLC film in different states to achieve efficient and accurate detection of different types of defects. This multi-state inspection method significantly reduces the rate of missed defect detection and improves the quality control level of PDLC films.

[0062] Preferably, the power supply device can be installed on one side of the lighting device and can include a power supply unit, a voltage regulator unit, and an electrode connection unit. The power supply unit is used to provide a stable and adjustable voltage output; the voltage regulator unit is used to adjust the output voltage as needed to meet the voltage requirements of the PDLC film in different states; and the electrode connection assembly is used to safely and effectively transmit the adjusted voltage to the electrodes that contact the upper and lower conductive layers (such as PET-ITO films) of the PDLC film.

[0063] Specifically, the power-on device can be an adjustable voltage power-on interface provided on the lighting device. When the PDLC film is placed on the carrier for inspection, the PDLC film is stationary. At this time, the power-on interface is electrically connected to the electrodes on the PDLC film, thereby powering the PDLC film and adjusting the power-on voltage.

[0064] like Figure 1 As shown, an illumination device 40 is preferably provided below the carrier. This device provides a vertically directed surface light source directed upward toward the carrier. The light intensity of the illumination device 40 is adjustable within a range of 1,000 to 20,000 lux. Different types of defects on the PDLC film require different light intensities to highlight their characteristics during inspection. By adjusting the light intensity, the imaging effect of each defect can be optimized, improving detection accuracy and sensitivity.

[0065] It is understandable that the lighting device 40 may specifically be an LED surface light source, a fluorescent surface light source, or other surface light source equipment that can provide uniform and adjustable brightness, and the present invention has no particular limitation thereto.

[0066] PDLC film defect detection systems ideally operate in a dark environment. This minimizes interference from external light, ensuring the camera captures clearer and more accurate images. In a dark environment, with only the lighting fixture providing illumination, the contrast between defects and normal areas on the PDLC film is more pronounced, facilitating camera recognition and detection. By relying solely on the system's built-in lighting fixtures, lighting conditions and intensity can be more precisely controlled, further optimizing inspection results.

[0067] like Figure 2 As shown, preferably, all other devices of the detection system (such as cameras, power devices, etc.) are set in the light shield 70 to maintain a dark environment in the entire detection area.

[0068] Preferably, the angle between the optical axis of each side-view camera group and the stage is independently adjustable within a range of 30-90°. By independently adjusting the angle of each side-view camera group's optical axis, the present invention allows for optimized capture of defects of varying types and sizes. This flexibility enables the inspection system to more accurately capture the characteristics of various defects on the PDLC film, improving the comprehensiveness and accuracy of inspections.

[0069] It's no secret that the angle of the optical axes of the side-view camera array directly impacts the quality of the captured image. At different angles, light interacts with the PDLC film in different ways, resulting in varying imaging effects. By adjusting the angle, optimal imaging conditions can be selected, making defects more visible and prominent in the image, facilitating subsequent image analysis and defect identification.

[0070] Preferably, the front-view camera group includes at least two spaced-apart front-view cameras, and each side-view camera group includes at least two spaced-apart side-view cameras. Any position on the stage is within the imaging range of at least one front-view camera and at least two different side-view cameras. The present invention, through the spaced-apart arrangement of multiple cameras, ensures that any position on the PDLC film on the stage is covered by at least one front-view camera and at least two side-view cameras from different directions. This three-dimensional imaging network effectively eliminates blind spots, ensuring that defects in any location can be captured by at least one camera.

[0071] Through a large number of actual product tests, it is concluded that the current defects of PDLC films can be roughly divided into four categories: 1. Completely opaque defects, such as ablation spots, black spots, etc.; 2. Completely translucent defects, such as transparent spots, transparent blocks or transparent lines of different shapes and sizes that are not coated with liquid crystal; 3. Uneven distribution of liquid crystal defects, such as irregular coating lines, halo spots, etc.; 4. Specific orientation defects of liquid crystal, such as regular coating marks, tube bottom marks, etc.

[0072] Specifically, the principle of defect detection of the present invention will be explained below from the combination of the state of the PDLC film and the camera arrangement:

[0073] 1. Atomized state (0V) + front-view camera: Detectable defects include completely transparent defects (transparent spots, transparent blocks, and transparent lines). This is because the PDLC film appears milky white overall (with a strong scattering background) in the atomized state. Transparent defect areas lack liquid crystal scattering, resulting in localized bright spots. The front-view camera can capture up to 90% of the brightness difference. Undetectable defects include uneven liquid crystal distribution (halo spots), liquid crystal orientation defects (coating marks), and completely opaque defects (black spots). This is because uneven distribution / orientation defects are obscured by uniform, strong scattering. In the atomized state, opaque defects lack contrast with surrounding scattering areas.

[0074] 2. Atomized state (0V) + side-view camera: There are basically no detectable defects because the strong isotropic scattering in the atomized state makes it impossible for the side-view angle to capture directional optical features (the defect signal is homogenized), and weak contrast defects (such as black spots) are further attenuated under the side-view light path.

[0075] 3. Translucent state (10-25V) + normal-view camera: Detectable defects include some severe liquid crystal orientation defects (wide coating marks) because the normal-view angle can identify the overall brightness difference of large-scale directional structures. Undetectable defects include uneven liquid crystal distribution defects (halo spots), subtle orientation defects (tube bottom marks), and opaque / transparent defects. This is because the circular scattering gradient of halo spots is compressed into a uniform bright spot at a vertical viewing angle; opaque / transparent defects have reduced contrast due to the semi-transparent background.

[0076] 4. Translucent state (10-25V) + side-view camera: Detectable defects include uneven liquid crystal distribution (halo spots, irregular lines) and liquid crystal orientation defects (regular coating marks, tube bottom marks). This is because the radial scattering gradient of halo spots creates a "bright center, dark edge" halo pattern when viewed from the side. The directional structure of orientation defects (such as parallel stripes in coating marks) creates periodic shadows in the lateral light path. The translucent state provides an optimal mixed background of scattering and transmissive light. Undetectable defects include completely opaque defects (black spots) and completely transmissive defects (transparent spots). This is because opaque defects require 100% dark field contrast in the transparent state, while completely transmissive defects require a strong scattering background in the atomized state to highlight bright spots.

[0077] 5. Transparent state (65V) + front-view camera: Detectable defects include completely opaque defects (ablation spots, black spots). This is because the PDLC film has extremely high light transmittance in the transparent state, and the black spot area creates 100% dark field contrast. Undetectable defects include uneven liquid crystal distribution, liquid crystal orientation defects, and completely transparent defects. This is because uneven distribution / orientation defects lose their optical characteristics due to the complete alignment of the liquid crystal. Completely transparent defects are invisible against a transparent background (no difference from normal areas).

[0078] 6. Transparent state (65V) + side-view camera: Detectable defects include some edge black spots (requiring a specific angle to cast a shadow). This is because the side-view optical path can cast a subtle shadow on the black spots, but only on the film edge. Undetectable defects include uneven liquid crystal distribution, liquid crystal orientation defects, completely transparent defects, and central black spots. This is because the transparent state lacks scattering, making side-view cameras unable to capture optical anomalies of distribution / orientation defects. Central black spots lack contrast due to the lack of shadow enhancement.

[0079] The result is that the side-view camera group captures images of uneven liquid crystal distribution and specific liquid crystal orientation defects in the PDLC film's semi-transparent state; the front-view camera group captures images of completely opaque defects in the PDLC film's transparent state; and the front-view camera group captures images of completely translucent defects in the PDLC film's atomized state. Achieving a detection rate exceeding 95% requires multi-state switching and multi-view coordination; a single combination would have a very high miss rate.

[0080] It should be noted that although defects with different optical properties each have their own most easily detectable state, when photographing defects in different states of the PDLC film, the present invention preferably still uses a front view camera and a side view camera to shoot at the same time, because the image superposition of the front view and side view cameras can effectively help identify defects with smaller sizes and is also more helpful in determining the type of defects.

[0081] It is understood that multiple cameras of the present invention can capture the same location from different angles, providing multi-dimensional image information. This information can be cross-validated during subsequent image analysis and defect identification, thereby improving detection accuracy and reliability.

[0082] It is understandable that different defects may have different sizes and shapes. By combining multiple cameras, we can more flexibly adapt to the detection needs of various defects, ensuring that both tiny defects and large defects can be effectively detected.

[0083] Ideally, both the front-view and side-view cameras should have a pixel count of 65 million or higher, with a recognition accuracy of less than 0.01mm. High-pixel cameras capture more detail, enabling the inspection system to clearly identify minor defects such as scratches and tiny bubbles. Combined with high-precision recognition capabilities, high-pixel cameras ensure more accurate and clear images. This helps reduce false positives and missed detections, improving inspection reliability.

[0084] The carrier is preferably made of high-transmittance glass with a flatness of ±0.5mm or less. This allows more light to penetrate the carrier, reducing reflection and scattering on the carrier surface, thereby improving the clarity and contrast of camera-captured images. Keeping the carrier flat to ±0.5mm ensures that the PDLC film remains flat when placed on the carrier, preventing image distortion or blurring caused by unevenness.

[0085] like Figure 1As shown, preferably, the detection system also includes a transmission device 50, a defect marking device 60, two adjustment devices (not shown in the figure) and a control device; the transmission device 50 is used to input and output the PDLC film into and out of the carrier 10; the defect marking device 60 is arranged on the exit side of the carrier 10, and the defect marking device 60 is used to mark the defect position on the PDLC film; the two side-view camera groups 30 are respectively arranged on the two adjustment devices, and the adjustment devices are used to adjust the preset angle between the optical axis of the side-view camera group 30 and the carrier 10; the control device is electrically connected to the front-view camera group 20, the side-view camera group 30, the power-on device, the transmission device 50, the defect marking device 60, and the adjustment device, and the control device is used to receive the detection images taken by the front-view camera group 20 and the side-view camera group 30 and analyze them to obtain the type, quantity and position of the defects.

[0086] Preferably, the control device is also electrically connected to the lighting device 40 .

[0087] like Figure 1 As shown, the conveyor 50 preferably includes a feed air shaft 51, a feed support platform 52, a discharge support platform 53, and a discharge air shaft 54, which are arranged in sequence. The feed air shaft 51 is located at the starting end of the conveyor 50 and is used to secure and rewind uninspected PDLC film rolls. The air shaft design allows for easy installation and removal of PDLC film rolls by inflating or deflating the air shaft, improving operational efficiency.

[0088] During specific use, one side of the feed inflatable shaft also needs to be connected to a first power source, which can be a motor, an electric motor, etc.

[0089] The feed support platform 52 is located downstream of the feed air shaft 51 to provide a smooth transition platform for the PDLC film. This ensures that the PDLC film remains flat after being unrolled from the air shaft, avoiding wrinkles or uneven tension.

[0090] The carrier 10, located between the infeed support platform 52 and the outfeed support platform 53, is the core area for PDLC film testing. The outfeed support platform 53, located at the exit of the carrier 10, provides support for the tested PDLC film, ensuring it remains stable during transport.

[0091] The design of the discharge support platform 53 matches that of the feed support platform 52 to maintain the stability of the PDLC film during the entire transport process.

[0092] The discharge air shaft 54 ​​is located at the end of the conveyor 50 and is used to reel in the inspected PDLC film. It rotates synchronously with the feed air shaft 51 to ensure that the PDLC film can be continuously and stably fed into and out of the carrier 10.

[0093] During specific use, one side of the discharge air shaft needs to be connected to a second power source, which can be a motor, an electric motor, etc.

[0094] Specifically, the PDLC film is a roll PDLC film, one end of the PDLC film is sleeved on the feed inflatable shaft 51, and the other end is laid on the feed support platform 52, the carrier 10 and the discharge support platform 53 in sequence, and finally sleeved on the discharge inflatable shaft 54. The feed inflatable shaft 51 and the discharge inflatable shaft 54 ​​rotate synchronously, thereby inputting and outputting the PDLC film into and out of the carrier 10.

[0095] It should be noted that the above is only a preferred choice of the transmission device of the present invention. The transmission device may also include but is not limited to structures such as conveyor belts, rollers, linear modules, etc. As long as the PDLC film can be input and output from the carrier, the present invention has no special restrictions on it.

[0096] like Figure 1 As shown, preferably, the defect marking device 60 may include a linear module 61, a telescopic portion 62, and a scribing portion 63. The linear module 61 is disposed on one side of the discharge support platform, with its length direction parallel to the transport direction of the PDLC film. One end of the telescopic portion 62 is disposed on the linear module 61 and is movable along its length direction. The telescopic portion 62 is retracted in a direction perpendicular to the linear module 61. The scribing portion 63 is disposed at the other end of the telescopic portion 62.

[0097] Specifically, when the control device identifies the location of the defect, the control device controls the defect marking device 60 to mark it. The telescopic part 62 first moves to the specified position in the linear module 61, and then the telescopic part 62 is telescoped and the marking part 63 is used to mark the defect position.

[0098] It should be noted that the above is only a preferred choice of the defect marking device of the present invention. The defect marking device may also include but is not limited to structures such as a multi-axis laser beam or a multi-axis inkjet printer. As long as the defect position on the PDLC film can be marked, the present invention has no special restrictions on it.

[0099] Preferably, the adjustment device may include a support base and a multi-jointed robotic arm. The support base may be disposed on the light shield, one end of the multi-jointed robotic arm may be disposed on the support base, and the side-view camera group may be disposed on the free end of the multi-jointed robotic arm. The multi-jointed robotic arm may flexibly adjust the angle of the optical axis of the side-view camera group by controlling the rotation angle of each joint.

[0100] It should be noted that the above is only a preferred choice of the adjustment device of the present invention. The adjustment device may also include but is not limited to a slide, a swingable support rod having a base and hinged on the base, and other structures. The structure of the adjustment device only needs to be able to adjust the preset angle between the optical axis of the side-view camera group and the carrier. The present invention has no special restrictions on it.

[0101] Preferably, the control device may include an image acquisition unit, an image processing unit, and an electronic control and adjustment unit. The image acquisition unit is configured to generate an acquisition signal and acquire a detection image captured by the camera under the instruction of the acquisition signal; the image processing unit is configured to perform defect detection on the detection image acquired by the image acquisition unit to determine the type, number, and location of defects. The electronic control and adjustment unit is configured to control the operation of the front view camera group, the side view camera group, the power supply device, the lighting device, the transmission device, the defect marking device, and the adjustment device.

[0102] A processing algorithm is provided in the image processing unit. Preferably, the processing algorithm can be for dividing the detection image into several small areas in units of pixels and numbering them, and calculating the grayscale value of each small area, as well as the deviation between the grayscale value of each small area and the grayscale value of the adjacent small area. If the absolute value of the deviation of a certain area exceeds the set grayscale deviation threshold, it is determined that there is a defect in the area; the larger the absolute value of the deviation, the more serious the surface defect.

[0103] More preferably, the processing algorithm can convert the detection image into an electronic signal through a preset algorithm, and then compare it with the database model to obtain the type, quantity and location of the defects. By comparing it with the actual defect morphology in the database, the recognition accuracy is higher.

[0104] It is understandable that the present invention does not actually have specific algorithm requirements; it can employ established analysis and processing methods in the prior art. This is because the present invention essentially exposes defects that are difficult to capture with existing technology by changing the display state of the PDLC film and collaborating with a multi-angle imaging system, allowing them to be captured by a camera. Various algorithms for analyzing and processing captured defect images are already well-established in the prior art. The present invention at least addresses the issue of ensuring that defects can be captured, and there are no restrictions on the methods used to process captured defect images.

[0105] The control device may include but is not limited to hardware structures such as CPU, PLC, FPGA, etc. It only needs to be able to obtain detection images and perform defect detection, as well as control the operation of the front-view camera group, side-view camera group, power-on device, transmission device, defect marking device, and adjustment device. The specific selection can be comprehensively considered based on system requirements, cost, performance and other factors, and the present invention has no special restrictions on it.

[0106] The present invention also provides a PDLC film defect detection method, which is applied to the above-mentioned PDLC film defect detection system, and the detection method includes:

[0107] Place the PDLC film on a carrier;

[0108] The PDLC film is powered by a power supply device and the power supply voltage is adjusted to switch the PDLC film between an atomized state, a semi-transparent state, and a transparent state.

[0109] A front view camera group and two side view camera groups are used to capture detection images of the PDLC film in the atomized state, translucent state, and transparent state respectively.

[0110] Preferably, the side-view camera group captures detection images of uneven liquid crystal distribution defects and specific liquid crystal orientation defects of the PDLC film in a translucent state;

[0111] The front-view camera group captures the detection image of the completely opaque defects of the PDLC film in its transparent state;

[0112] The front-view camera group captures the detection image of the completely light-transmitting defect of the PDLC film in the atomized state.

[0113] Preferably, the inspection method further includes adjusting a preset angle between the optical axis of the side-view camera group and the stage using an adjustment device. When capturing inspection images of uneven liquid crystal distribution defects, the preset angles between the optical axis of each of the two side-view camera groups and the stage are independently adjusted to 60-90°. The scattering signal from uneven liquid crystal distribution defects is directional. Specifically, the chaotic light and dark patches of irregular coating patterns require capture at a specific inclination angle (e.g., 60-90°). The annular scattering of halo spots requires angle adjustment to identify radial light intensity gradients. Independently adjusting the camera group angles allows for adaptability to the spatial distribution characteristics of different defects.

[0114] Preferably, when capturing images of specific LC alignment defects, adjust the angle between the optical axes of the two side-view camera groups to 90°. Specific LC alignment defects, such as regular coating marks and tube bottom marks, have a fixed directional structure (e.g., banded arrangement). A 90° cross-viewing angle can fully capture alignment anomalies in different directions, completely covering the anisotropy of the defect and preventing missed defects at any angle.

[0115] Preferably, the detection method further includes providing a vertically upward surface light source to the carrier through an illumination device, and adjusting the light source intensity of the illumination device during shooting; wherein, when capturing the detection image of the uneven distribution defect of the liquid crystal, the light source intensity of the illumination device is adjusted to 8000-15000 lux. Uneven distribution defects of liquid crystal, such as irregular coating lines and halo spots, are mainly highlighted by the scattering differences formed by the translucent state of the PDLC film. Higher light intensity can enhance the scattering signal of the defective area, because uneven distribution can lead to local droplet density differences, and high brightness can amplify this scattering contrast, especially when capturing asymmetric light spots at side viewing angles.

[0116] Preferably, when capturing images of specific liquid crystal orientation defects, the light intensity of the illumination device is adjusted to 1000-8000 lux. Lower light intensity is used to capture specific liquid crystal orientation defects because specific orientation defects inherently have high contrast in the transparent state of the PDLC film (the ordered-disordered mixed state amplifies the orientation difference), and excessively strong light may mask subtle shadows or absorption features.

[0117] When capturing images of completely opaque and completely translucent defects, adjust the illumination intensity to 15,000-20,000 lux. Extreme brightness is used to enhance global contrast in opaque and completely translucent defects. Optical defects (such as black spots) cast darker shadows under bright light, highlighting the occlusion effect. For completely translucent defects (such as transparent spots), the abnormally translucent areas are overexposed to bright spots under strong background light.

[0118] Preferably, when the PDLC film is in a semi-transparent state, at least two different voltage values ​​are used to capture detection images of liquid crystal uneven distribution defects and liquid crystal specific orientation defects.

[0119] Preferably, the at least two different voltage values ​​include at least one voltage value selected from each of a first voltage interval and a second voltage interval, the power-on voltage in the first voltage interval is 10-15V, and the power-on voltage in the second voltage interval is 20-25V.

[0120] As a preferred embodiment, while the PDLC film is translucent at voltages between 10V and 25V, the voltage significantly affects detection accuracy in this translucent state. Detection results differ between 10V and 25V, and different optimal voltages are required for uneven liquid crystal distribution defects and specific liquid crystal orientation defects. Specifically, for uneven liquid crystal distribution defects (such as halo spots), the core detection principle is the asymmetric scattering they produce. At lower voltages (10-15V), the liquid crystal molecular orientation ratio is 30%-50% ordered, leaving more disordered scattering in the background area, which in turn amplifies the ring-shaped light intensity distribution caused by the halo spot due to the density gradient. For specific liquid crystal orientation defects (such as tube bottom marks), their directional optical characteristics require a sufficiently ordered background to be prominent. At higher voltages (20-25V), the liquid crystal molecular orientation ratio is 60%-80% ordered, which improves transmittance and reduces scattering, making the anomalous birefringence or absorption characteristics of the defect area more distinct from the background.

[0121] Preferably, the detection method also includes using a 10-15V voltage to shoot when shooting the detection image of the uneven distribution defect of the liquid crystal, adjusting the preset angle between the optical axis of the two side-view camera groups and the carrier to 60-90°, and adjusting the light source intensity of the lighting device to 8000-15000 lux.

[0122] Preferably, when capturing detection images of specific orientation defects of liquid crystals, the angle between the optical axes of the two side-view camera groups is adjusted to 90°, and the light source intensity of the lighting device is adjusted to 1000-8000 lux.

[0123] The present invention significantly improves the imaging contrast of two types of defects through the dynamic coordination of voltage, angle and light source intensity:

[0124] For uneven liquid crystal distribution defects (such as halo spots), a low voltage (10-15V) is used to put the PDLC film into a weakly oriented translucent state. At this time, the liquid crystal droplets retain more disordered scattering. Combined with a 60-90° high-angle side-view camera, the radial light intensity gradient of uneven liquid crystal distribution defects (such as the "bright center-dark edge" halo of halo spots) can be captured. At the same time, a strong light source of 8000-15000 lux is applied to enhance the difference in scattering signals and amplify the contrast between light and dark. The three-way synergy significantly reduces the missed detection rate of uneven liquid crystal distribution defects.

[0125] For specific liquid crystal orientation defects (such as coating marks), high voltage (20-25V) is used to enhance the orderly arrangement of liquid crystal molecules, fully cover the defect directional structure (such as periodic shadows of parallel stripes) through a 90° orthogonal side viewing angle, and control the weak light source of 1000-8000 lux to avoid loss of details due to overexposure. The three together effectively improve the recognition accuracy of specific liquid crystal orientation defects.

[0126] As is understandable, there are four common types of defects on PDLC films. The following details each type of defect and explains the specific principle by which the present invention, through combining an energizing device that can precisely control the state of the PDLC film with a multi-angle imaging system, can image defects with different optical properties in their most easily detectable states:

[0127] 1. Completely opaque defects, such as burnt spots and black spots, are primarily caused by impurities in the substrate during the production process. Burnt spots are explosive points created when the upper and lower film surfaces are electrically connected. Carbonized deposits form locally, blocking light transmission. When the PDLC film is transparent, completely opaque defects appear as black spots, creating a 100% contrast ratio with the surrounding transparent areas. Therefore, the present invention uses a front-facing camera to capture the PDLC film in its transparent state. At this point, the normal area has the highest light transmittance, while the defective area, due to its complete opacity, forms a noticeable dark spot.

[0128] 2. Completely transparent defects, such as transparent spots, transparent blocks or transparent lines of different shapes and sizes that are not coated with liquid crystal, are mainly caused by the omission or deficiency of liquid crystal material during the coating process, resulting in the lack of liquid crystal coverage in local areas of the film layer. Under normal circumstances, the PDLC film is in an atomized state when it is not powered. However, at completely transparent defects, due to the lack of scattering effect of liquid crystal, light can pass through freely, forming bright spots or bright spots. Therefore, the present invention chooses to use a front-view camera to shoot in the atomized state of the PDLC film. In the atomized state, the film layer as a whole appears milky white, and the defective area forms a bright spot due to direct light transmission. The front-view camera can capture up to 90% of the brightness difference.

[0129] 3. Uneven distribution of liquid crystal defects, such as irregular coating lines and halo spots, are usually caused by uneven distribution of liquid crystal materials or the presence of bubbles, micro-depression of the film layer, etc. during the coating process. In different areas of the PDLC film, the degree of scattering of liquid crystal may be inconsistent, resulting in uneven brightness, color differences, or scattered light spots of a specific shape on the surface of the film layer. Specifically, the irregular coating lines are caused by fluctuations in scraper pressure or local unevenness of the substrate, which causes random accumulation of liquid crystals, forming irregular thickness mutation areas. The thickness mutation causes abnormal aggregation of droplet density, resulting in local mutations in scattering intensity. The halo spots are caused by slight damage to the film surface or interference from impurities, causing liquid crystal droplets to locally aggregate into a ring distribution. The droplet density in the center area is low and the density at the edge is high, forming concentric scattering differences.

[0130] This application uses a semi-transparent state to detect uneven liquid crystal distribution defects because, in the semi-transparent state, the PDLC film exhibits a mixed state of partially aligned and partially disordered liquid crystals. This maximizes the difference in scattering characteristics between the defective and background areas. Specifically, the uniformly oriented liquid crystal droplets in the normal region have good light transmittance, while the disordered regions maintain scattering. However, the irregular coating texture in the defective region, due to the sudden change in thickness, leads to chaotic multiple scattering paths, and halo spots produce a ring-shaped scattered light intensity distribution due to the density gradient.

[0131] This application uses a side-view camera to detect uneven liquid crystal distribution defects because the refractive index gradient at the defect changes the spatial distribution of scattered light. The side-view angle can effectively capture this asymmetric scattering signal (such as the difference in radial scattering intensity at a halo point). However, a front-view camera is not very effective at detecting uneven liquid crystal distribution defects. Specifically, the irregular thickness mutations of irregular coating patterns cause scattered light to form chaotic light and dark patches in space, and a front-view camera, due to its perpendicular optical path, cannot resolve these disordered features. The annular density gradient of a halo point exhibits a "halo effect" with a bright center and dark edges under a side-view optical path. A front-view angle compresses the annular structure into a uniform bright spot, thus missing detection.

[0132] 4. Specific liquid crystal orientation defects, such as regular coating marks and tube bottom marks, are typically caused by mechanical stress during curing, which triggers the liquid crystal molecules to form a specific orientation structure. This orientation structure can lead to abnormal light scattering or absorption properties. Specifically, regular coating marks are caused by the periodic vibration of the scraper or the pressure of the roller, which causes the liquid crystal molecules to align in a parallel band-like orientation structure. Tube bottom marks are caused by uneven substrate or localized uneven mechanical stress during the curing process, which causes the liquid crystal molecules to align in a specific direction, forming a band-like or grid-like abnormal orientation structure.

[0133] This application uses the semi-transparent state to detect specific liquid crystal orientation defects because, in the semi-transparent state, the PDLC film exhibits a mixed state of partially aligned and partially disordered liquid crystal molecules. In this state, the defective region exhibits fixed directional characteristics, significantly amplifying the optical differences between the defective region and the normal background region. Specifically, the normal region exhibits random or partially aligned molecular orientations, resulting in relatively uniform light scattering. In the defective region, however, the regular coating marks exhibit periodic anomalies in birefringence due to their oriented banded arrangement, while the bottom marks on the tube exhibit directional deflections in the scattering path due to their grid-like orientation.

[0134] This application uses a side-view camera to detect specific liquid crystal orientation defects because the directional characteristics of orientation defects (such as the parallel stripes of regular coating marks or the grid structure of tube bottom marks) can cause asymmetric light distribution. Side-view angles can effectively capture scattering or absorption signals at specific angles. However, front-view cameras are less effective at detecting specific liquid crystal orientation defects. Specifically, the parallel band structure of regular coating marks presents periodic light and dark stripes when viewed from a side angle, but front-view cameras, due to their perpendicular light path, cannot detect these directional periodic characteristics. The grid orientation of tube bottom marks can create a cross-shadow effect when viewed from a side light path, but the front-view angle averages out light intensity variations, potentially missing subtle defects.

[0135] Understandably, in the atomized state (0V), the PDLC film produces strong, uniform scattering due to the free orientation of the liquid crystal molecules, resulting in an opaque, milky white background. This uniform, strong scattering completely drowns out the local density differences characteristic of LC distribution defects (such as irregular coating lines and halo spots), while also masking the directional optical properties of specific LC orientation defects (such as regular coating marks and tube bottom marks), rendering them invisible. In the transparent state (65V), on the other hand, the LC molecules are fully aligned, and the film's transmittance is uniform, eliminating scattering contrast. In this state, the droplet density gradients of LC distribution defects fail to produce discernible intensity differences. Furthermore, under a strong electric field, the LC molecules' orientation remains uniform, and the birefringence anomalies or absorption features of specific orientation defects disappear. Therefore, neither state provides effective imaging conditions for direction-sensitive or scattering-dependent defects.

[0136] The present invention also provides a method for optimizing the production process of a PDLC film, comprising the following steps:

[0137] Use PDLC film defect detection system to obtain defect types;

[0138] According to the preset defect type mapping relationship library, the defect type is converted into the corresponding process abnormality item;

[0139] The PDLC film production process is optimized based on process anomalies.

[0140] Preferably, the defect types include four categories: 1. Completely opaque defects, such as ablation points, black spots, etc.; 2. Completely translucent defects, such as transparent spots, transparent blocks or transparent lines of different shapes and sizes that are not coated with liquid crystal; 3. Uneven distribution of liquid crystal defects, such as irregular coating lines, halo spots, etc.; 4. Specific orientation defects of liquid crystal, such as regular coating marks, tube bottom marks, etc.

[0141] Preferably, the preset defect type mapping relationship library and process abnormality items include: when a liquid crystal uneven distribution defect is detected, it is determined that the coating machine scraper pressure is abnormal;

[0142] When a specific orientation defect of the liquid crystal is detected, it is determined to be uneven mechanical stress during the curing stage;

[0143] When a complete light transmission defect is detected, it is determined that the amount of liquid crystal coating is insufficient;

[0144] When a completely opaque defect is detected, it is determined to be substrate contamination or scratches during the coating process;

[0145] Preferably, adjustment instructions are fed back to the coating machine or curing equipment execution end in real time according to process abnormalities to dynamically optimize production process parameters.

[0146] The embodiments of the present invention are described in detail below, which are exemplary and only used to explain the present invention, and are not to be construed as limiting the present invention.

[0147] Example 1

[0148] The specific parameters of the equipment used in Example 1 are as follows: the size of the light shield is 500mm*500mm*500mm, the camera model of the front view camera group and the side view camera group is Sony IMX650, the model of the lighting device is LED-500, the size of the carrier is 300mm*300mm, and the model of the defect marking device is XY-100.

[0149] like Figure 1 As shown, the present invention uses the PDLC film defect detection system to detect 1,000 PDLC film samples with various defects (the size of the carrier 10 is the area of ​​one sheet). The specific detection method includes the following steps:

[0150] After the PDLC film is transferred to the carrier 10 via the transfer device 50 , the transfer device 50 is temporarily stopped.

[0151] The PDLC film is not powered on first. At this time, the PDLC film is in an atomized state. The front view camera group 20 and two side view camera groups 30 are used to photograph the PDLC film. The light source intensity of the lighting device 40 is 18000 lux.

[0152] After the first shot, the PDLC film was powered on by the power supply device and the power supply voltage was adjusted to 12V to make the PDLC film translucent. The preset angle between the optical axis of the two side-view camera groups 30 and the stage 10 was adjusted to 75°. The light source intensity of the lighting device 40 was adjusted to 15,000 lux. The PDLC film was photographed using the front-view camera group 20 and the two side-view camera groups 30.

[0153] After the second shot, the PDLC film was powered on by the power supply device and the power supply voltage was adjusted to 22V. The preset angle between the optical axes of the two side-view camera groups 30 and the stage 10 was adjusted to 45°. The light source intensity of the lighting device 40 was adjusted to 5000 lux. The PDLC film was photographed using the front-view camera group 20 and the two side-view camera groups 30.

[0154] After the third shot, the PDLC film is energized by the power supply device and the voltage is adjusted to 65V to make the PDLC film transparent. The light intensity of the lighting device 40 is adjusted to 18,000 lux. The PDLC film is photographed using the front view camera group 20 and the two side view camera groups 30.

[0155] Acquire inspection images and perform defect detection through a control device;

[0156] After the PDLC film is output from the carrier 10 by the transport device 50 , the defect position is marked by the defect marking device 60 .

[0157] The final evaluation results showed that 24 out of 1,000 defective PDLC film samples were missed, with a detection rate of 97.6%.

[0158] like Figure 3 As shown, Figure 3 The detection image of the halo point detected in Example 1 of the present invention;

[0159] like Figure 4 As shown, Figure 4 This is a detection image of regular coating marks detected in Example 1 of the present invention.

[0160] Example 2

[0161] The same detection method as in Example 1 was used, except that after the first shot, the PDLC film was powered by a power supply device and the power supply voltage was adjusted to 20V, and after the second shot, the power supply voltage was still maintained at 20V.

[0162] The final evaluation results showed that 41 of the 1,000 defective PDLC film samples were missed, with a detection rate of 95.9%.

[0163] Example 3

[0164] The same detection method as in Example 1 is used, except that after the first shooting, the preset angles between the optical axes of the two side-view camera groups 30 and the carrier 10 are adjusted to 60°, and after the second shooting, the preset angles between the optical axes of the two side-view camera groups 30 and the carrier 10 are still maintained at 60°.

[0165] The final evaluation results showed that 36 of the 1,000 defective PDLC film samples were missed, with a detection rate of 96.4%.

[0166] Example 4

[0167] The same detection method as in Example 1 was used, except that the light source intensity of the lighting device 40 was maintained at 15,000 lux throughout the entire process.

[0168] The final evaluation results showed that 32 of the 1,000 defective PDLC film samples were missed, with a detection rate of 96.8%.

[0169] Comparative Example 1

[0170] The same detection method as in Example 1 was used, except that, in each shot, the PDLC film was not energized by the energizing device, and the PDLC film was in an atomized state throughout the entire process.

[0171] The final evaluation results showed that 246 of the 1,000 defective PDLC film samples were missed, with a detection rate of 75.4%.

[0172] Comparative Example 2

[0173] The same detection method as in Example 1 was used, except that in each shot, the PDLC film was energized by a power supply device, and the power supply voltage was 65V, and the PDLC film was in a transparent state throughout the whole process.

[0174] The final evaluation results showed that 307 out of 1,000 defective PDLC film samples were missed, with a detection rate of 69.3%.

[0175] Comparative Example 3

[0176] The same detection method as in Example 1 is used, except that the front-facing camera group does not take any picture in each shooting.

[0177] The final evaluation results showed that 368 of the 1,000 defective PDLC film samples were missed, with a detection rate of 63.2%.

[0178] Comparative Example 4

[0179] The same detection method as in Example 1 is used, except that the side view camera group does not take any picture in each shot.

[0180] The final evaluation results showed that 410 of the 1,000 defective PDLC film samples were missed, with a detection rate of 59.0%.

[0181] It can be seen from the results of Examples 1-4 that the present invention can further improve detection accuracy through dynamic coordination of voltage, angle and light source intensity.

[0182] The results of the Examples and Comparative Examples demonstrate that the present invention, by combining a power-on device capable of precisely controlling the PDLC film state with a multi-angle imaging system, can image defects with different optical properties in their most easily detectable states. This effectively overcomes the existing challenges of mutually exclusive detection conditions for different defect types, resulting from light scattering, interference, polarization, and other characteristics, significantly reducing the rate of missed defect detection.

[0183] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A PDLC film defect detection system, characterized in that: include: A carrier, the carrier being used to carry the PDLC film; An orthographic camera group is disposed above the stage, and an optical axis of the orthographic camera group is perpendicular to the stage; Two side-view camera groups, the two side-view camera groups are also arranged above the platform, and the two side-view camera groups are respectively arranged on both sides of the front-view camera group, and the optical axes of the side-view camera groups form a preset angle with the platform; a power supply device for supplying power to the PDLC film and adjusting the supply voltage so as to switch the PDLC film between an atomized state, a semi-transparent state, and a transparent state; Among them, the carrier is located within the shooting range of the front view camera group and the side view camera group, and the front view camera group and the two side view camera groups are used to shoot detection images of the PDLC film in the atomized state, translucent state and transparent state.

2. The PDLC film defect detection system according to claim 1, characterized in that: The power supply voltage range of the power supply device is 0-65V; Wherein, when the power-on voltage is 0V, the PDLC film is in an atomized state; When the voltage is 10-25V, the PDLC film is in a translucent state; When the applied voltage is 65V, the PDLC film is in a transparent state.

3. The PDLC film defect detection system according to claim 1, characterized in that: An illumination device is provided below the carrier, and the illumination device is used to provide a vertically upward surface light source to the carrier; The light source intensity of the lighting device is adjusted within the range of 1000-20000 lux.

4. The PDLC film defect detection system according to claim 1, characterized in that: The preset angle between the optical axis of each side-view camera group and the carrier is independently adjusted within 30-90°.

5. The PDLC film defect detection system according to claim 1, characterized in that: The front view camera group includes at least two spaced front view cameras, and each side view camera group includes at least two spaced side view cameras; Any position on the platform is within the shooting range of at least one front-view camera and at least two different side-view cameras.

6. The PDLC film defect detection system according to claim 5, characterized in that: The front view camera and the side view camera are both selected to have a pixel count of 65 million or more, and a recognition accuracy of less than 0.01 mm.

7. The PDLC film defect detection system according to claim 1, characterized in that: The carrier is made of high-transmittance glass, and the flatness is controlled below ±0.5mm.

8. The PDLC film defect detection system according to claim 1, characterized in that: The detection system also includes: a transport device for transporting the PDLC film into and out of the carrier; a defect marking device, the defect marking device being disposed at the exit side of the carrier, the defect marking device being used to mark the defect position on the PDLC film; Two adjustment devices, the two side-view camera groups are respectively provided on the two adjustment devices, and the adjustment devices are used to adjust a preset angle between the optical axis of the side-view camera group and the platform; A control device, wherein the control device is electrically connected to the front view camera group, the side view camera group, the power supply device, the transmission device, the defect marking device, and the adjustment device. The control device is used to receive the detection images taken by the front view camera group and the side view camera group and analyze them to obtain the type, quantity and location of the defects.

9. A PDLC film defect detection method, characterized in that: The detection method is applied to the PDLC film defect detection system according to any one of claims 1 to 8, and the detection method comprises: placing the PDLC film on a carrier; applying power to the PDLC film through a power supply device and adjusting the power supply voltage to switch the PDLC film between an atomized state, a semi-transparent state, and a transparent state; A front view camera group and two side view camera groups are used to respectively capture detection images of the PDLC film in an atomized state, a translucent state, and a transparent state.

10. The PDLC film defect detection method according to claim 9, characterized in that: The side-view camera group captures detection images of uneven liquid crystal distribution defects and specific liquid crystal orientation defects of the PDLC film in a translucent state; The front-view camera group captures a detection image of the completely opaque defect of the PDLC film in a transparent state; The front-view camera group captures a detection image of a completely light-transmitting defect of the PDLC film in an atomized state.

11. The PDLC film defect detection method according to claim 10, characterized in that: The detection method further includes adjusting a preset angle between the optical axis of the side view camera group and the stage by an adjustment device; When capturing detection images of uneven distribution defects of liquid crystal, the preset angles between the optical axes of the two side-view camera groups and the stage are independently adjusted to 60-90°; and / or, When capturing detection images of specific orientation defects of liquid crystal, the angle between the optical axes of the two side-view camera groups is adjusted to 90°.

12. The PDLC film defect detection method according to claim 10, characterized in that: The detection method further includes providing a vertically upward planar light source to the carrier through an illumination device, and adjusting the light source intensity of the illumination device during shooting; When capturing a detection image of a liquid crystal uneven distribution defect, the light source intensity of the lighting device is adjusted to 8000-15000 lux; and / or, When capturing a detection image of a specific orientation defect of a liquid crystal, the light source intensity of the lighting device is adjusted to 1000-8000 lux; and / or, When capturing detection images of completely opaque defects and completely translucent defects, the light source intensity of the lighting device is adjusted to 15,000-20,000 lux.

13. The PDLC film defect detection method according to claim 10, characterized in that: When the PDLC film is in a semi-transparent state, at least two different voltage values ​​are used to capture detection images of liquid crystal uneven distribution defects and liquid crystal specific orientation defects.

14. The PDLC film defect detection method according to claim 13, wherein: The at least two different voltage values ​​include at least one voltage value selected from a first voltage interval and a second voltage interval. The power-on voltage in the first voltage interval is 10-15V, and the power-on voltage in the second voltage interval is 20-25V.

15. The PDLC film defect detection method according to claim 14, characterized in that: The detection method further comprises: When capturing an inspection image of a liquid crystal uneven distribution defect, a voltage of 10-15 V is used for capturing the image, the preset angle between the optical axes of the two side-view camera groups and the stage is adjusted to 60-90°, and the light source intensity of the lighting device is adjusted to 8000-15000 lux; and / or, When capturing detection images of specific orientation defects of liquid crystals, a voltage of 20-25V is used for capturing, the angle between the optical axes of the two side-view camera groups is adjusted to 90°, and the light source intensity of the lighting device is adjusted to 1000-8000 lux.

16. A method for optimizing a PDLC film production process, characterized in that: The following steps are involved: Obtaining the defect type using the PDLC film defect detection system according to any one of claims 1 to 8; According to the preset defect type mapping relationship library, the defect type is converted into the corresponding process abnormality item; The PDLC film production process is optimized based on process anomalies.

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