A method for detecting the color of the adhesive surface of Mini-LED beads

Abstract

This invention discloses a method for detecting the adhesive color of Mini-LED beads, comprising the following steps: S1: Under fixed ambient light conditions, acquiring a first image of the Mini-LED bead to be tested after surface magnification before reflow treatment, and a second image of the Mini-LED bead to be tested after surface magnification after reflow treatment; S2: Restoring the Mini-LED bead to be tested from the first and second images; S3: Performing color analysis on the restored first and second images to obtain the first chromaticity value of the Mini-LED bead before reflow treatment and the second chromaticity value after reflow treatment; S4: Calculating the difference between the first and second chromaticity values ​​to determine whether the surface adhesive color of the Mini-LED bead is qualified based on the difference. This method for detecting the adhesive color of Mini-LED beads can automatically identify the surface adhesive color at the Mini-LED bead level and screen Mini-LED beads from the source, thereby improving the display effect of subsequent displays.

Description

Technical Field

[0001] This invention relates to the field of Mini-LED lamp bead technology, and in particular to a method for detecting the color of the adhesive surface of Mini-LED lamp beads. Background Technology

[0002] As is well known, Mini-LEDs, with their advantages of small size, high brightness, high contrast, and fast response, have broad application prospects in the high-end display field and are a core direction for industry technology upgrades. Among them, the mainstream in the market adopts SMD surface-mount Mini-LED chips, which is a packaging form in which LED chips are directly mounted and soldered onto the surface pads of the circuit board (PCB) using surface mount technology (SMT). It does not require drilling and insertion, and has the characteristics of compact structure and adaptability to automated mass production. It can meet the requirements of high-density dot matrix arrangement, and its packaging quality directly determines the display effect and long-term reliability of the display screen.

[0003] Currently, most SMD (Surface Mount Device) Mini-LED chips are encapsulated with epoxy resin. This organic polymer material is easily activated and oxidized during the high-temperature processes of chip encapsulation and module production, producing yellowing factors that cause changes in the color of the Mini-LED chip encapsulation adhesive, resulting in inconsistencies in adhesive color between the same batch and different batches. This difference directly causes color block defects in the display screen, with visible color blocks present whether the screen is lit or black, disrupting image consistency and causing image distortion.

[0004] Research has found that most defect detection methods for Mini-LED chips on the market focus on surface defects of the adhesive after dispensing (such as excess adhesive, insufficient adhesive, bubbles, etc.). They lack a dedicated testing system for the consistency of adhesive color and yellowing characteristics of individual Mini-LED chips, making it difficult to capture subtle differences in adhesive color and failing to achieve pre-inspection and control at the incoming material inspection end. Even when manual inspection is used, it suffers from strong subjectivity, low efficiency, easy to miss detection, poor reliability and stability, and cannot meet the requirements of large-scale inspection in industrial production. Summary of the Invention

[0005] The technical problem to be solved by this invention is that it discloses a novel method for detecting the color of the adhesive surface of Mini-LED beads, in order to solve the problem that the existing technology lacks a specific means for detecting the color of the adhesive surface of Mini-LED beads, which makes it impossible to accurately and efficiently detect the color consistency and yellowing characteristics of the adhesive surface of Mini-LED beads, and thus cannot control the impact of adhesive color differences on the picture quality of Mini-LED displays from the source.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for detecting the color of the adhesive surface of a Mini-LED bead, comprising the following steps: S1: Under fixed ambient light conditions, acquire the first image of the Mini-LED bead to be tested after surface magnification before reflow treatment, and the second image of the Mini-LED bead after surface magnification after reflow treatment. S2: Restore the Mini-LED bead to be detected in the first LED bead image and the second LED bead image; S3: Perform color analysis on the restored first LED image and second LED image respectively to obtain the first chromaticity value of the Mini-LED LED before reflow and the second chromaticity value after reflow of the tested Mini-LED. S4: Calculate the difference between the first chromaticity value and the second chromaticity value, and determine whether the surface appearance adhesive color of the Mini-LED lamp bead is qualified based on the difference.

[0007] Furthermore, in the Mini-LED bead adhesive surface color detection method of the present invention, in step S1, a CCD camera is used in conjunction with a microscopic magnification device to magnify and image the surface of the Mini-LED bead to be detected and to acquire the first bead image and / or the second bead image.

[0008] Furthermore, in the Mini-LED lamp bead adhesive surface color detection method of the present invention, in step S1, under the ambient light conditions, the ambient stray light illuminance value is controlled to be less than 1Lx.

[0009] Furthermore, in the Mini-LED lamp bead adhesive surface color detection method of the present invention, in step S1, under the ambient light conditions, an auxiliary LED light source is used to illuminate the Mini-LED lamp bead to be detected.

[0010] Furthermore, in the Mini-LED bead adhesive surface color detection method described in this invention, the chromaticity value of the auxiliary LED light source is 6200-6800K, and the illuminance value is 300-330LX.

[0011] Furthermore, in the Mini-LED lamp bead adhesive surface color detection method of the present invention, in step S1, the reflow conditions for the Mini-LED lamp bead to be tested are one of the following: The furnace treatment temperature is 150℃, and the furnace treatment time is 1 hour; The furnace treatment temperature is 180℃, and the furnace treatment time is 1 hour; The furnace treatment temperature is 220℃, and the furnace treatment time is 1 hour; or, The furnace treatment temperature is 260℃, and the furnace treatment time is 5 minutes.

[0012] Furthermore, in the Mini-LED LED bead adhesive surface color detection method of the present invention, in step S2, the restoration process specifically involves: displaying the first LED bead image and the second LED bead image in full screen using a color-calibrated high-fidelity display. The image display mode of the high-fidelity display is fixed, its size is 55 inches, its resolution is ≥4K, its NTSC color gamut overlap rate is ≥90%, and its brightness is between 300-350 cd / m², in order to restore the adhesive surface color of the Mini-LED LED bead to be detected.

[0013] Furthermore, in the Mini-LED bead adhesive surface color detection method of the present invention, in step S3, a color analyzer is used to perform color analysis on the restored first bead image and the second bead image respectively, and a standard color card is used for calibration before using the color analyzer.

[0014] Furthermore, in the Mini-LED lamp bead adhesive color detection method of the present invention, in step S4, a threshold is preset, and when the difference is greater than the threshold, the surface appearance adhesive color of the Mini-LED lamp bead is determined to be unqualified; when the difference is less than the threshold, the surface appearance adhesive color of the Mini-LED lamp bead is determined to be qualified.

[0015] Furthermore, in the Mini-LED lamp bead adhesive color detection method of the present invention, steps S1-S3 are performed on multiple Mini-LED lamp beads to be tested in the same batch, with the same reflow treatment conditions, to obtain the first chromaticity value and the second chromaticity value corresponding to the multiple Mini-LED lamp beads to be tested, so as to obtain the first average chromaticity value and the second average chromaticity value of the Mini-LED lamp beads to be tested in the batch; in step S4, the difference between the first average chromaticity value and the second average chromaticity value is calculated, so as to determine whether the surface appearance adhesive color of the Mini-LED lamp beads to be tested in the batch is qualified based on the difference.

[0016] The beneficial effects of this invention are as follows: This invention designs a novel method for detecting the color of the adhesive surface of Mini-LED beads. This method optimizes the detection process for adhesive color to establish a standardized detection environment and magnifies and restores the detection images, thereby enabling color detection of the adhesive surface of individual Mini-LED beads. It achieves precise quantitative detection of the consistency of adhesive color and yellowing characteristics on the appearance of the beads, and detects subtle differences in adhesive color. This overcomes the shortcomings of traditional detection methods that rely solely on subjective judgment. The detection results are closely related to the materials and furnace treatment process. While automatically identifying the adhesive color on the appearance of the beads, a database can be established to achieve batch-to-batch adhesive color trend analysis. This facilitates operators in improving adhesive selection and furnace treatment processes to accurately control the adhesive color differences on the surface of Mini-LED beads, thereby improving product yield and production efficiency. It has good prospects for promotion and application value. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the steps of one embodiment of the Mini-LED lamp bead adhesive surface color detection method described in this invention. Detailed Implementation

[0018] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0019] As is well known, the color block phenomenon in Mini-LED displays is affected by the inconsistency of the color of the adhesive used in the LED chips. Whether the display is lit or black, there are visible color blocks, which cause image distortion and affect picture quality.

[0020] Therefore, please refer to Figure 1 As shown, this invention designs a new method for detecting the color of the adhesive surface of Mini-LED beads. This method optimizes the detection process of the adhesive color to build a standardized detection environment and magnifies and restores the detection image, thereby enabling color detection of a single Mini-LED bead adhesive surface.

[0021] In this invention, the method for detecting the color of the adhesive surface of Mini-LED beads can specifically include the following steps: S1: Under fixed ambient light conditions, acquire the first image of the Mini-LED bead to be tested after surface magnification before reflow treatment, and the second image of the Mini-LED bead after surface magnification after reflow treatment. S2: Restore the Mini-LED bead to be detected in the first LED bead image and the second LED bead image; S3: Perform color analysis on the restored first LED image and second LED image respectively to obtain the first chromaticity value of the Mini-LED LED before reflow and the second chromaticity value after reflow of the tested Mini-LED. S4: Calculate the difference between the first chromaticity value and the second chromaticity value, and determine whether the surface appearance adhesive color of the Mini-LED lamp bead is qualified based on the difference.

[0022] The Mini-LED LED bead adhesive color detection method designed based on this invention can automatically and accurately quantify the consistency of the adhesive color and yellowing characteristics of the LED beads without the need for additional operation or subjective judgment by operators. It can also detect subtle differences in adhesive color, thereby overcoming the shortcomings of traditional detection methods that can only detect the color of large areas such as display screens, and the fact that the judgment of Mini-LED LED bead adhesive color usually relies on subjective judgment. Furthermore, it can pre-screen Mini-LED LED beads, solving the problem of poor display effect in displays made with multiple Mini-LED LED beads from the source.

[0023] In practical applications, the detection results obtained by this Mini-LED lamp bead adhesive color detection method are closely related to the selected adhesive material and furnace curing process parameters. While automatically identifying the adhesive color of the lamp bead appearance, a database can be established to realize batch-to-batch adhesive color trend analysis, thereby facilitating operators to improve adhesive material selection and furnace curing process, so as to accurately control the adhesive color difference on the surface of Mini-LED lamp beads, thereby improving product yield and production efficiency.

[0024] Accordingly, in practical applications, in order to obtain better image acquisition results, in step S1 of the Mini-LED lamp bead adhesive surface color detection method designed in this invention, the image acquisition device can be adjusted. Specifically, a high-definition CCD camera can be used in conjunction with a microscopic magnification device to magnify and image the surface of the Mini-LED lamp bead to be detected and acquire the first lamp bead image and the second lamp bead image.

[0025] It is important to emphasize that ambient light directly affects the acquisition effect of the CCD camera and also directly affects the subsequent judgment of the adhesive color on the surface of the Mini-LED beads. Therefore, in order to ensure the stability and reliability of the detection results, the ambient light must be kept constant, for example, by setting it in a dark room. At the same time, under this ambient light condition, in order to avoid external stray light affecting the imaging effect of the CCD camera, the ambient stray light illuminance value under this ambient light condition can be specifically controlled to be less than 1Lx.

[0026] Furthermore, to further improve the color acquisition accuracy of the aforementioned CCD camera, an auxiliary LED light source can be further set when acquiring images of the adhesive color on the surface of the Mini-LED beads. This auxiliary LED light source can then illuminate the Mini-LED beads under the aforementioned ambient light conditions. In practical applications, the auxiliary LED light source can preferably be a high color rendering index auxiliary LED light source, with its chromaticity value specifically controlled between 6200-6800K and its illuminance value specifically controlled between 300-330LX, to ensure that the Mini-LED beads can accurately display colors after illumination.

[0027] Furthermore, in step S1 of the Mini-LED LED bead adhesive surface color detection method designed in this invention, when dealing with the detection of a large number of Mini-LED LED beads, in order to ensure that the detection results are referential and constructive, in addition to fixing the above-mentioned ambient light conditions, it is also necessary to fix the above-mentioned reflow conditions of the Mini-LED LED beads after reflow treatment. Specifically, the reflow treatment temperature can be controlled at 150°C and the reflow treatment time can be controlled at 1 hour. Of course, in some other embodiments, depending on the material of the selected adhesive, the above-mentioned reflow conditions can also be adapted to meet product requirements, and this invention does not specifically limit them; for example, in some specific embodiments, the reflow treatment temperature can be controlled at 180°C and the reflow treatment time at 1 hour; or, the reflow treatment temperature can be controlled at 220°C and the reflow treatment time at 1 hour; or, the reflow treatment temperature can be controlled at 260°C and the reflow treatment time at 5 minutes.

[0028] Based on this, after various optimization designs of the above-mentioned ambient light conditions, reflow conditions and the image acquisition hardware used, reliable image data can be effectively acquired in step S1, that is, the first image of the Mini-LED bead to be tested after surface magnification before reflow processing and the second image of the bead after surface magnification after reflow processing are acquired.

[0029] Accordingly, see further Figure 1 As shown, since the image obtained is a magnified image of the Mini-LED bead to be detected, in step S2 of the Mini-LED bead adhesive surface color detection method designed in this invention, in order to ensure the accuracy of the subsequent color analysis results, it is also necessary to restore the Mini-LED bead to be detected in the first bead image and the second bead image.

[0030] It should be noted that, in this invention, the restoration process for the first LED bead image and the second LED bead image can be specifically as follows: the first LED bead image and the second LED bead image are displayed in full screen on a color-calibrated high-fidelity display. The image display mode of the high-fidelity display is fixed, its size is 55 inches, its resolution is ≥4K, its NTSC color gamut overlap rate is ≥90%, and its brightness is set between 300-350 cd / m², so as to restore the adhesive surface color of the Mini-LED bead to be tested.

[0031] Based on this, in step S3, a color analyzer can be used to perform color analysis on the restored first LED image and second LED image respectively, and a standard color card can be used for calibration before using the color analyzer, so as to obtain the first chromaticity value of the Mini-LED LED before reflow and the second chromaticity value after reflow of the LED.

[0032] Then, in step S4 of the present invention, a threshold is preset, and the difference between the first chromaticity value and the second chromaticity value is calculated. If the difference is greater than the threshold, the surface appearance adhesive color of the Mini-LED lamp bead is determined to be unqualified; if the difference is less than the threshold, the surface appearance adhesive color of the Mini-LED lamp bead is determined to be qualified. The threshold can be adaptively adjusted according to the production quality requirements of each production line to achieve greater adaptability.

[0033] Of course, considering that in actual production processes, a large number of Mini-LED beads are often produced in a single batch, it is difficult for operators to inspect each and every one of them. Therefore, it is usually necessary to sample Mini-LED beads from the same batch to select multiple Mini-LED beads to be tested and perform steps S1-S3 of the Mini-LED bead adhesive color detection method designed in this invention. These Mini-LED beads undergo the same reflow oven treatment conditions to obtain the first and second chromaticity values ​​corresponding to the multiple Mini-LED beads to be tested, thereby obtaining the first and second average chromaticity values ​​of the batch of Mini-LED beads to be tested. In step S4, the difference between the first and second average chromaticity values ​​is calculated, and the difference is used to determine whether the surface appearance adhesive color of the batch of Mini-LED beads to be tested is qualified. Furthermore, when judging the difference between the first and second average chromaticity values, a preset threshold can be used to facilitate automated judgment by software.

[0034] The color detection method for Mini-LED LED beads designed in this invention provides accurate results and can replace manual color judgment. For ease of understanding, this invention also employs the following Embodiment 1, implemented simultaneously with manual visual inspection, to illustrate and explain the technical solution of this invention: Before practical application, subjective judgment can be made manually. This involves taking pictures with a CCD camera, controlling the ambient light, and enhancing color rendering to capture images of the first Mini-LED beads before reflow treatment and the second Mini-LED beads after reflow treatment. Then, visual inspection can be performed manually to obtain the inspection results.

[0035] Example 1: The steps S1-S4 of the Mini-LED LED bead adhesive color detection method designed in this invention are as follows: Under fixed ambient light conditions, first LED bead images (after surface magnification before reflow treatment) and second LED bead images (after surface magnification after reflow treatment) of multiple Mini-LED LED beads to be tested from the same batch are acquired; then, the Mini-LED LED beads to be tested in the first and second LED bead images are restored; and color analysis is performed on the restored first and second LED bead images to obtain the first chromaticity value of the Mini-LED LED bead to be tested before reflow treatment and the second chromaticity value after reflow treatment, and the first average chromaticity value and the second average chromaticity value of the Mini-LED LED beads to be tested in this batch are obtained. Then, the difference between the first average chromaticity value and the second average chromaticity value is calculated to determine whether the surface appearance adhesive color of the Mini-LED LED beads to be tested in this batch is qualified based on the difference.

[0036] In actual testing, whether it is the above-mentioned visual inspection experiment or the first embodiment of the present invention, an auxiliary LED light source with a chromaticity value of 6500K and an illuminance value of 300LX is used for auxiliary lighting, and the ambient stray light illuminance value is less than 1Lx under ambient light conditions; the selected color analyzer model is CA410, and the magnification of the micro-magnification device is more than 40 times; at the same time, the furnace treatment conditions used are: furnace treatment temperature of 260℃ for 5 minutes.

[0037] It should be noted that both the visual inspection experiment and the above-mentioned Example 1 are used to detect and judge the color of the adhesive surface of the Mini-LED lamp beads to be tested, which are made of two different materials of adhesive, namely Material 1 and Material 2, and to obtain the corresponding test results in order to improve the accuracy of the experimental test results.

[0038] In this embodiment, testing is performed separately for two batches, Material 1 and Material 2. Specifically, five Mini-LED beads to be tested are selected from the same batch, namely bead 1, bead 2, bead 3, bead 4, and bead 5 as shown in Table 1. Their first chromaticity value before reflow and their second chromaticity value after reflow are listed in Table 1 below: Table 1.

[0039] In Table 1 above, Min represents the smallest chromaticity value among the five Mini-LED beads to be tested in the row, Max represents the largest chromaticity value among the five Mini-LED beads to be tested in the row, and AVG represents the average chromaticity value among the five Mini-LED beads to be tested in the row, which includes the first average chromaticity value and the second average chromaticity value.

[0040] The detection results of Example 1 were compared with the detection results of the visual inspection experiment. For details of the comparison, please refer to Tables 2 and 3 below: Table 2.

[0041] Table 3

[0042] Referring to the contents disclosed in Tables 2 and 3 above, based on the comparative experiments, it can be seen that the Mini-LED lamp bead adhesive surface color detection method of the present invention can accurately detect the color of the Mini-LED lamp bead adhesive surface and determine whether yellowing or abnormality occurs. It has good stability and accurate detection results. In contrast, the visual inspection experiment, because it is conducted by operators using their naked eyes, shows that when the difference is 200K, the human eye can hardly see any difference, making it difficult to identify the difference; when the difference is around 300K, the human eye can see a slight difference; and when the difference is 500K, the human eye can see a significant difference. Its stability is poor and it is prone to detection errors.

[0043] In summary, this invention presents a novel method for detecting the adhesive surface color of Mini-LED beads. This method optimizes the adhesive color detection process, establishes a standardized testing environment, and magnifies and restores the detected images. This enables color detection of individual Mini-LED bead adhesive surfaces, achieving precise quantitative detection of adhesive color consistency and yellowing characteristics, as well as detecting subtle adhesive color differences. It overcomes the limitations of traditional methods that rely solely on subjective judgment. The detection results are closely related to the materials and furnace treatment process. While automatically identifying the adhesive color of the beads, a database can be established to analyze adhesive color trends between batches. This facilitates operators in improving adhesive selection and furnace treatment processes, precisely controlling adhesive color differences on the surface of Mini-LED beads, and improving product yield and production efficiency. This method has promising prospects and application value.

[0044] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for detecting the color of the adhesive surface of Mini-LED beads, characterized in that, Including the following steps: S1: Under fixed ambient light conditions, acquire the first image of the Mini-LED bead to be tested after surface magnification before reflow treatment, and the second image of the Mini-LED bead after surface magnification after reflow treatment. S2: Restore the Mini-LED bead to be detected in the first LED bead image and the second LED bead image; S3: Perform color analysis on the restored first LED image and second LED image respectively to obtain the first chromaticity value of the Mini-LED LED before reflow and the second chromaticity value after reflow of the tested Mini-LED. S4: Calculate the difference between the first chromaticity value and the second chromaticity value, and determine whether the surface appearance adhesive color of the Mini-LED lamp bead is qualified based on the difference.

2. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 1, characterized in that, In step S1, a CCD camera is used in conjunction with a microscopic magnification device to magnify and image the surface of the Mini-LED bead to be tested and to acquire the image of the first bead and / or the image of the second bead.

3. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 1, characterized in that, In step S1, under the ambient light conditions, the ambient stray light illuminance value is controlled to be less than 1 Lx.

4. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 3, characterized in that, In step S1, under the ambient light conditions, an auxiliary LED light source is used to illuminate the Mini-LED bead to be tested.

5. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 4, characterized in that, The auxiliary LED light source has a chromaticity value of 6200-6800K and an illuminance value of 300-330LX.

6. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 1, characterized in that, In step S1, the reflow conditions for the Mini-LED lamp beads to be tested are one of the following: The furnace treatment temperature is 150℃, and the furnace treatment time is 1 hour; The furnace treatment temperature is 180℃, and the furnace treatment time is 1 hour; The furnace treatment temperature is 220℃, and the furnace treatment time is 1 hour; or, The furnace treatment temperature is 260℃, and the furnace treatment time is 5 minutes.

7. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 1, characterized in that, In step S2, the restoration process specifically involves: displaying the first LED image and the second LED image in full screen using a color-calibrated high-fidelity display. The high-fidelity display has a fixed image display mode, a size of 55 inches, a resolution of ≥4K, an NTSC color gamut overlap rate of ≥90%, and a brightness between 300-350 cd / m², in order to restore the adhesive surface color of the Mini-LED LED to be tested.

8. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 1, characterized in that, In step S3, a color analyzer is used to perform color analysis on the restored first LED image and second LED image, and a standard color chart is used for calibration before using the color analyzer.

9. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 1, characterized in that, In step S4, a threshold is preset, and if the difference is greater than the threshold, the surface appearance adhesive color of the Mini-LED lamp bead is determined to be unqualified; if the difference is less than the threshold, the surface appearance adhesive color of the Mini-LED lamp bead is determined to be qualified.

10. The method for detecting the color of the adhesive surface of Mini-LED beads according to claim 1, characterized in that, For multiple Mini-LED lamp beads to be tested in the same batch, the above steps S1-S3 are performed respectively, and the reflow treatment conditions are the same, so as to obtain the first chromaticity value and the second chromaticity value corresponding to the multiple Mini-LED lamp beads to be tested, so as to obtain the first average chromaticity value and the second average chromaticity value of the Mini-LED lamp beads to be tested in this batch. In step S4, the difference between the first average chromaticity value and the second average chromaticity value is calculated to determine whether the surface appearance adhesive color of the Mini-LED lamp beads to be tested in this batch is qualified based on the difference.

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