Online real-time monitoring and testing system and method for color difference of color film

Abstract

The invention discloses an on-line real-time monitoring and testing system and method for color difference of a colored film. The method comprises the following steps: acquiring a film image by adopting an optical detection module; the reflection calibration module compensates transmissivity fluctuation of the thin film through a reflection plate located below the thin film, and provides a calibration reference by means of a standard material and a calibration plate with the same height; the motion synchronization module realizes synchronization of high-precision camera acquisition and film motion so as to eliminate motion blur, and adjusts the light source intensity of the optical detection module based on the real-time light transmittance feedback of the film; and the data processing module dynamically updates a conversion matrix from RGB to LAB by using the data of the calibration plate so as to compensate system temperature excursion, obtain an E threshold value and generate a color difference distribution thermodynamic diagram. According to the invention, the problem of inaccurate chromatic aberration measurement caused by factors such as film light transmittance fluctuation, system temperature excursion and motion blur in the prior art is solved, real-time and accurate monitoring and rapid analysis of the film chromatic aberration in the production process are realized, and the method is suitable for film color quality control in a high-speed continuous production scene.

Description

Technical Field

[0001] This invention relates to a real-time monitoring and testing system and method for color difference of online colored films, specifically to a system for real-time monitoring and testing of color difference of colored films in high-speed continuous production scenarios, and the method used in conjunction with it, belonging to the field of optical inspection and industrial automation technology. Background Technology

[0002] In the production of colored films, color consistency is a core indicator for measuring product quality, directly affecting product quality and market competitiveness. Therefore, accurate monitoring of color differences during the production process is crucial. However, existing quality control technologies have significant shortcomings, mainly in the following two aspects: 1. Offline detection lag: Current production processes mainly rely on manual sampling for color monitoring. Samples are usually taken from the beginning and end of the film roll and then sent to the laboratory for measurement using offline equipment such as X-Rite. This method has significant drawbacks: First, the cycle from sampling and testing to obtaining results is too long, making it impossible to capture color fluctuations in production in real time, resulting in difficulty in timely detection and correction of color deviation problems; second, manual sampling and testing processes are prone to introducing contamination or scratches, which may damage the samples, causing the measurement results to deviate from the actual situation and affecting the accurate assessment of the color quality of the entire roll of film. 2. Lack of online dynamic calibration: Existing online testing equipment is unable to synchronously calibrate the performance drift of core components (such as the detection light source and imaging camera) under conditions of high-speed continuous operation of the film (e.g., 10-50 meters / minute). Due to the lack of an effective dynamic calibration mechanism, the measurement errors accumulated by the system over time cannot be automatically compensated, resulting in a gradual decline in the reliability and stability of the detection data, making it difficult to meet the long-term requirements of high-precision color control.

[0003] To overcome the low efficiency and unstable accuracy of manual color difference detection for thin films, Chinese patent CN119354894A proposes an automated detection system. This system integrates hardware and algorithms, employing a support vector machine to construct a classification module. It performs high-dimensional spatial analysis on extracted color features to achieve high-precision and adaptive color difference determination, and can visually locate problem areas. However, in actual production line applications, this system still faces the problem of reference color failure. Affected by factors such as stray light and light source attenuation in the environment, the lack of real-time correction of the reference color will lead to inaccurate RGB data, severely impacting the overall accuracy of color detection. Furthermore, the absence of a background calibration plate in the system further increases testing errors. Summary of the Invention

[0004] The purpose of this invention is to provide an online real-time monitoring and testing system and method for color difference of colored films. By integrating multiple modules such as optical detection, reflection calibration, motion synchronization and data processing, it solves the problem of inaccurate color difference measurement caused by factors such as film transmittance fluctuation, system temperature drift and motion blur in the prior art. It realizes real-time, accurate monitoring and rapid analysis of film color difference in the production process, and is suitable for film color quality control in high-speed continuous production scenarios.

[0005] This invention is achieved through the following technical solution: a real-time monitoring and testing system for color difference in online color films, comprising: Optical inspection module: Illuminates the thin film at a 5° incident angle and acquires images of the thin film using a high-precision camera; Reflection calibration module: It compensates for the transmittance fluctuations of the thin film by using a reflector located below the thin film, and provides a calibration reference by using standard materials and calibration plates of the same height; Motion synchronization module: Enables synchronization between high-precision camera acquisition and thin film motion to eliminate motion blur, and adjusts the light source intensity of the optical detection module based on the real-time transmittance feedback of the thin film. Data processing module: Dynamically updates the conversion matrix from RGB color space to LAB color space using calibration board data to compensate for system temperature drift, and simultaneously calculates the color difference ΔE threshold in multiple modes. Based on the threshold and the color data of the acquired image, it generates and outputs a color difference distribution heatmap.

[0006] The reflector is located 1-5 mm below the film, its width covers the width of the film, and its installation height is consistent with that of the calibration plate.

[0007] The reflector and calibration plate have a matte ceramic finish and a reflectivity of not less than 98%.

[0008] The reflection calibration module also includes a self-cleaning and dustproof device for dustproofing the standard materials and calibration plate.

[0009] The motion synchronization module synchronously triggers the exposure of the high-precision camera by receiving encoder signals from the thin film roller.

[0010] The motion synchronization module integrates an adaptive dimming unit, which adjusts the light source intensity of the optical detection module based on the real-time transmittance feedback signal of the thin film.

[0011] The data processing module also integrates an anomaly alarm unit. When the system detects that the ΔE value of three consecutive frames of images exceeds the threshold, it triggers an audible and visual alarm and automatically records the spatial coordinates of the defect location.

[0012] A method for real-time monitoring and testing of color difference in online color films, using the aforementioned real-time monitoring and testing system, performs the following operations: S1. Online calibration process: During each frame image acquisition, the linear RGB values ​​of the calibration board are extracted synchronously. The standard values ​​of the calibration whiteboard obtained from offline laboratory testing are compared and corrected with the values ​​acquired on-site to ensure the consistency between production line testing and offline equipment testing results. S2. Thin film color analysis process: S21. Color Correction: Based on the values ​​calibrated in step S1, the RGB values ​​of the thin film in real-time testing are corrected and calculated. S22. Color Space Conversion: Convert the corrected linear RGB values ​​into one or more color parameters from L*, a*, b*, x, y, YI and △E according to the CIE1931 or CIE1976 standard color space coordinate formula; S3. Online verification process: The standard film of the production line is placed on the placement stage above the calibration plate for material calibration to further reduce the system reference error and verify the abnormality of the test results; S4. Result Display and Anomaly Handling: The ΔE value calculated in step S22 is visualized in the form of a heat map, and an alarm is triggered for positions where the color parameter exceeds the set threshold.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention utilizes 5° incident angle illumination and combines it with a high reflectivity (≥98%) matte ceramic reflector design to effectively suppress specular reflection interference (≤5%), providing a pure and stable optical environment for color acquisition.

[0014] (2) The present invention can realize dynamic calibration compensation, and uses the reflector and calibration plate to compensate for the thin film transmittance fluctuation and system temperature drift in real time, ensuring the accuracy of the measurement reference and the reliability of the collected data under long-term operation.

[0015] (3) The present invention can realize high-speed online real-time detection, and use encoder signals to trigger high-precision camera exposure, so that image acquisition and high-speed movement of thin film (supporting 50m / min) are precisely synchronized, which can eliminate motion blur and ensure image clarity.

[0016] (4) The present invention can achieve rapid real-time feedback. During the operation of the system, it overcomes the lag of traditional offline detection, can capture color fluctuations in production in real time, and avoids sample contamination. It can provide test results faster and more accurately.

[0017] (5) The present invention can automatically adjust the light source intensity according to the real-time transmittance of the thin film through an integrated adaptive dimming unit, so as to adapt to different production materials and working conditions.

[0018] (6) The present invention utilizes a data processing module to automatically calculate color difference, generate distribution heat map, and trigger audible and visual alarms and record defect location (positioning accuracy ±1mm) when continuous abnormalities are detected, thus realizing rapid discovery and accurate positioning of problems.

[0019] (7) The method of the present invention can effectively ensure the consistency and reliability of the measurement results. Through the online calibration process, the test results of the production line can be correlated and corrected with the offline laboratory standards, ensuring the consistency of data under different test environments. Furthermore, the entire thin film color acquisition and analysis process is online and non-contact, avoiding sample contamination or damage that may be introduced during manual sampling and testing, thereby ensuring the authenticity of the measurement results and accurately reflecting the product quality. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the system layout described in this invention (front view and side view).

[0021] Figure 2 This is a schematic diagram of the system structure described in this invention.

[0022] Figure 3 This is a schematic diagram of the system flow described in this invention.

[0023] Figure 4 This is a thermogram showing the color difference distribution of the orange reflective film in Example 1.

[0024] Figure 5 This is a thermogram showing the color difference distribution of the red reflective film in Example 2.

[0025] Among them, 1—thin film, 2—high-precision camera, 3—reflector, 4—standard material, 5—calibration plate, 6—light source (5° incident angle), 7—placement stage. Detailed Implementation

[0026] The invention's objective, technical solution, and beneficial effects will be further explained in detail below.

[0027] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the claimed invention. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] This invention aims to construct a high-precision, high-speed, and highly automated online color difference detection system and method. The system integrates four major modules: optical detection, reflection calibration, motion synchronization, and data processing. Through coordinated hardware and software design and systematic multi-module collaboration, it successfully applies high-precision laboratory color difference detection capabilities to high-speed continuous production lines. This enables real-time, accurate, stable, and automated monitoring of color differences in colored films throughout the entire process, effectively improving product quality and production efficiency. It provides timely, accurate, and reliable data support for color quality control of colored films in high-speed continuous production scenarios and is applicable to various functional films such as colored reflective film base films, optical films, and photovoltaic films.

[0029] In terms of high-precision detection, this invention utilizes the collaborative operation of a built-in reflector 3 and an external calibration plate 5 to synchronously compensate for error sources of two different dimensions: changes in the thin film's own characteristics and drift in the performance of the detection system. This multi-calibration mechanism ensures the long-term stable operation of the system. In terms of high-speed detection, this invention combines high-speed synchronous imaging with real-time feedback-based adjustment of the light source 6 to simultaneously solve two major dynamic challenges: motion blur and image exposure consistency. This ensures that stable and clear detection images can be obtained even in high-speed, variable-condition production environments. In terms of automated detection, the data processing module of this invention updates the RGB to LAB color space conversion matrix in real time based on the data from the calibration plate 5 in each frame of the image. This actively tracks and compensates for the system's slow temperature drift, ensuring the continuous accuracy of the color calculation model and achieving fully unmanned intelligent judgment throughout the entire process.

[0030] The following is a further summary of the technical solution of the present invention: This invention relates to an online real-time monitoring and testing system for color difference in color thin films, integrating four main modules: optical detection, reflection calibration, motion synchronization, and data processing. (See also...) Figure 1 and Figure 2 As shown: The optical inspection module includes a light source 6 and a high-precision camera 2. The light source 6 illuminates the thin film 1 with illumination light at a 5° incident angle, and the high-precision camera 2 acquires images of the surface of the thin film 1. The light source 6 can be a D65 linear light source with a color temperature of 6504K, symmetrically arranged on both sides along the transmission direction of the thin film 1, and suppresses specular reflection by having an incident angle of 5° with the normal of the thin film 1. The high-precision camera 2 can be an RGB 12-bit linear array camera, mounted perpendicular to the surface of the thin film 1, and supports 10-bit RAW output.

[0031] The reflection calibration module includes a reflector 3 positioned below the film 1, a standard material 4 at the same height as the film 1, and a calibration plate 5 at the same height as the reflector 3. Specifically, the reflector 3 is positioned 1-5 mm below the film 1, its width covering the width of the film 1, and its surface is a matte ceramic color (reflectivity ≥98%), used to compensate for transmittance fluctuations in the film 1. The standard material 4 and the calibration plate 5 are both located on one side of the production line. The standard material 4 is stored on a designated platform. The system pre-stores the LAB color space reference values ​​for the calibration plate 5 (e.g., L*=93.8, a*=-0.1, b*=2.66, test values ​​not included in the reflection data). The standard material 4 and the calibration plate 5 share a calibration benchmark. Additionally, a self-cleaning dustproof device is provided for this reflection calibration module to prevent dust from entering the standard material 4 and the calibration plate 5. This device can be set to automatically clean and prevent dust every 10 seconds as needed.

[0032] The motion synchronization module is used to synchronize image acquisition by the high-precision camera 2 with the movement of the thin film 1, thereby eliminating motion blur and dynamically adjusting the light source intensity of the optical detection module based on the real-time transmittance of the thin film 1. Specifically, an encoder can be installed on the thin film roller. The motion synchronization module receives the encoder signal from the thin film roller to synchronously trigger the exposure of the high-precision camera 2, ensuring that the image is free of motion blur (displacement error <0.1mm). Since the transmittance of the thin film varies under the same light source for different materials, the light source intensity needs to be adjusted in real time (0-100% PWM adjustment) to avoid overexposure or underexposure. Therefore, the adaptive dimming unit integrated in the motion synchronization module is used to adjust the light source intensity of the optical detection module based on the real-time transmittance feedback signal of the thin film 1.

[0033] The data processing module dynamically updates the conversion matrix from RGB color space to LAB color space based on the image data from the calibration board 5 to compensate for system temperature drift, and calculates the color difference E threshold in multiple modes. Based on the threshold and the color data of the acquired image, it generates and outputs a color difference distribution heatmap. This is achieved through an integrated real-time calibration engine and a multi-mode color difference calculation module. The real-time calibration engine can dynamically update the conversion matrix from RGB color space to LAB color space based on data from the external calibration board 5, compensating for temperature drift (accuracy ±0.1ΔE / ℃). The multi-mode color difference calculation module supports CIE1931 (XYZ), CIE1976 (LAB), CIEDE2000 standards, etc., and can configure the ΔE threshold (default ΔE ≤ 1.0). It can also generate and output a color difference distribution heatmap based on the threshold and the color data of the acquired image.

[0034] The data processing module also integrates an anomaly alarm unit. When the system detects that the ΔE value of three consecutive frames of images exceeds the threshold, it triggers an audible and visual alarm and automatically records the spatial coordinates of the defect location.

[0035] This invention also relates to a method for real-time monitoring and testing of color difference in online color films based on the above system, see [link to relevant documentation]. Figure 3 As shown, the specific operation is as follows: S1. Online calibration process: During each frame image acquisition, the linear RGB value of calibration board 5 is extracted synchronously. The standard value of the calibration white board obtained from offline laboratory testing is compared and corrected with the value acquired on site to ensure the consistency between production line testing and offline equipment testing results. S2. Thin film color analysis process: S21. Color Correction: Based on the values ​​calibrated in step S1, the RGB values ​​of the film 1 are corrected and calculated in real time. S22. Color Space Conversion: Convert the corrected linear RGB values ​​into one or more color parameters from L*, a*, b*, x, y, YI and △E according to the CIE1931 or CIE1976 standard color space coordinate formula; Where L* represents the parameter for black and white, with positive for black and negative for white; a* represents the parameter for red and green, with positive for red and green for white; b* represents the parameter for yellow and blue, with positive for yellow and negative for blue; x and y are the normalized ratios of tristimulus values, used to represent hue and protection; YI is the yellow index.

[0036] S3. Online verification process: The standard film of the production line is placed on the placement stage above the calibration plate 5 for material calibration, so as to further reduce the system reference error and verify the abnormality of the test results; S4. Result Display and Anomaly Handling: The ΔE value calculated in step S22 is visualized in the form of a heat map, and an alarm is triggered for positions where the color parameter exceeds the set threshold.

[0037] The specific implementation of the present invention will be described below with reference to the embodiments. Of course, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Example 1: The real-time monitoring and testing system described in this invention is added to the existing orange reflective film production line. The system uses a customer-sealed confirmation sample as standard material 4 and is calibrated using the LAB color space reference values ​​(L*=93.8, a*=-0.1, b*=2.66) of its calibration plate 5. When the production line operates at a speed of 20 meters per minute, the system performs real-time color detection on the orange reflective film and obtains a color difference distribution heatmap. See details... Figure 4 As shown.

[0039] Example 2: The real-time monitoring and testing system described in this invention is added to the existing red reflective film production line. The system uses a customer-sealed confirmation sample as standard material 4 and is calibrated using the LAB color space reference values ​​(L*=93.8, a*=-0.1, b*=2.66) of its calibration plate 5. When the production line operates at a speed of 20 meters per minute, the system performs real-time color detection on the red reflective film and obtains a color difference distribution heatmap. See details... Figure 5 As shown.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A real-time monitoring and testing system for color difference of online color films, characterized in that: include: Optical detection module: Illuminates the thin film (1) at an incident angle of 5° and acquires images of the thin film by a high-precision camera (2); Reflection calibration module: The reflector plate (3) located below the thin film (1) compensates for the transmittance fluctuation of the thin film (1) and provides a calibration reference with the help of a standard material (4) of the same height and a calibration plate (5); Motion synchronization module: realizes the synchronization of high-precision camera (2) acquisition and film (1) motion to eliminate motion blur, and adjusts the light source intensity of optical detection module based on real-time transmittance feedback of film (1); Data processing module: dynamically updates the conversion matrix from RGB color space to LAB color space using calibration board (5) data to compensate for system temperature drift, and synchronously calculates the color difference ΔE threshold in multiple modes. Based on the threshold and the color data of the acquired image, it generates and outputs a color difference distribution heat map.

2. The real-time monitoring and testing system according to claim 1, characterized in that: The reflector (3) is located 1-5 mm below the film (1), its width covers the width of the film (1), and its installation height is consistent with that of the calibration plate (5).

3. The real-time monitoring and testing system according to claim 1, characterized in that: The reflector (3) and the calibration plate (5) have a matte ceramic finish and a reflectivity of not less than 98%.

4. The real-time monitoring and testing system according to claim 1, characterized in that: The reflection calibration module also includes a self-cleaning and dustproof device for dustproofing the standard material (4) and calibration plate (5).

5. The real-time monitoring and testing system according to claim 1, characterized in that: The motion synchronization module synchronously triggers the exposure of the high-precision camera (2) by receiving the encoder signal from the thin film roller.

6. The real-time monitoring and testing system according to claim 1, characterized in that: The motion synchronization module integrates an adaptive dimming unit, which is used to adjust the light source intensity of the optical detection module according to the real-time transmittance feedback signal of the thin film (1).

7. The real-time monitoring and testing system according to claim 1, characterized in that: The data processing module also integrates an anomaly alarm unit. When the system detects that the ΔE value of three consecutive frames of images exceeds the threshold, it triggers an audible and visual alarm and automatically records the spatial coordinates of the defect location.

8. A method for real-time monitoring and testing of color difference in online color films, characterized in that: Using the real-time monitoring and testing system according to any one of claims 1 to 7, perform the following operations: S1. Online calibration process: During each frame image acquisition, the linear RGB value of the calibration board (5) is extracted synchronously. The standard value of the calibration white board obtained from the offline laboratory test is compared and corrected with the value acquired on site to ensure the consistency between the production line test and the offline equipment test results. S2. Thin film color analysis process: S21. Color correction: Based on the values ​​calibrated in step S1, the RGB values ​​of the film (1) in real-time test are corrected and calculated. S22. Color Space Conversion: Convert the corrected linear RGB values ​​into one or more color parameters from L*, a*, b*, x, y, YI and △E according to the CIE1931 or CIE1976 standard color space coordinate formula; S3. Online verification process: Place the standard film of the production line on the placement platform above the calibration plate (5) for material calibration, so as to further reduce the system reference error and verify the abnormality of the test results; S4. Result Display and Anomaly Handling: The ΔE value calculated in step S22 is visualized in the form of a heat map, and an alarm is triggered for positions where the color parameter exceeds the set threshold.

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