Substrate ink droplet overflow detection method and device
By acquiring images outside the barrier dam on large-size substrates for grayscale projection and area division, the problem of low efficiency in detecting ink droplet overflow defects on large-size substrates is solved, and fast and accurate detection and positioning are achieved.
Patent Information
- Application Number
- CN202511117365.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-11
- Publication Date
- 2025-10-14
AI Technical Summary
On large-sized substrates, the detection efficiency of ink drop overflow defects in the prior art is low, especially in the case of multiple printing areas, where it is difficult to detect ink drop overflow defects quickly and accurately.
By acquiring images within a preset distance range outside the barrier dam and performing grayscale projection of the images, an optical camera is used to directly determine ink droplet overflow defects. If necessary, the image can be divided into multiple areas for more accurate defect location.
The efficiency and accuracy of ink drop overflow defect detection are improved. It can make a judgment in a non-printing area surrounding a printing area at one time, and can quickly locate the defect position, facilitating subsequent parameter adjustments.
Smart Images
Figure CN120778735A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of defect detection of display screens, in particular to a method for detecting ink drop overflow of a substrate and a device thereof. BACKGROUND
[0002] At present, the most common packaging method of display screens is the thin film packaging method. Physical vapor deposition (PECVD), sputtering (SUPTTER), atomic layer deposition (ALD) and other methods are mainly used to realize the production of inorganic packaging layers, and the inorganic packaging layer is mainly responsible for water and oxygen barrier. Due to the existence of stress in the inorganic packaging layer, an organic packaging layer or a similar organic packaging layer is added between the inorganic packaging layers to realize the functions of stress release and planarization. The organic packaging layer is mainly made by inkjet printing (IJP), PECVD, screen printing or flash evaporation, etc. Among them, IJP process uses ink drop material with low viscosity, and the ink drop material drops naturally.
[0003] However, in the thin film packaging structure, the coverage area of the organic layer is smaller than that of the inorganic layer, that is, the organic layer is wrapped by the inorganic layer. When the ink drop material of IJP is used to prepare the organic packaging layer, the ink drop material is prone to overflow to the outside of the barrier dam structure of the display panel, which will directly lead to unqualified packaging of the display panel. The detection efficiency of the existing ink drop overflow defect has problems, especially on a large-size substrate, which often needs to detect the ink drop overflow defect of all printing areas.
[0004] Therefore, on a large-size substrate, how to improve the detection efficiency of the ink drop overflow defect becomes a problem to be solved. SUMMARY
[0005] The present application provides a method for detecting ink drop overflow of a substrate and a device thereof, which can directly compare the obtained image gray projection value with the preset image threshold value by performing overall image gray projection on the area outside the barrier dam, to quickly judge whether the printing area has ink drop overflow defect; thereby improving the detection efficiency of the ink drop overflow defect.
[0006] The first aspect of the present application discloses a method for detecting ink drop overflow of a substrate, the substrate comprising a printing area and a non-printing area, the non-printing area comprising a barrier dam; the barrier dam surrounds the printing area to prevent ink drops printed by an inkjet printer from overflowing, and the ink drops are used to package the printing area; the barrier dam comprises a first barrier dam and a second barrier dam, and the first barrier dam is close to the printing area, and the second barrier dam surrounds the first barrier dam; wherein the method comprises:
[0007] Obtaining a to-be-detected image, the to-be-detected image being an image within a preset distance range adjacent to the second barrier dam in a direction away from the printing area;
[0008] projecting the image gray scale of the image to be detected to obtain an image gray scale projection value of the image to be detected;
[0009] If the image gray scale projection value is greater than a preset image threshold value, it is determined that the image to be detected has a droplet overflow defect.
[0010] In the above scheme, the image within the preset distance range outside the second barrier can be directly obtained by an optical camera, the image within the preset distance range is subjected to overall gray scale projection, that is, the image within the preset distance range is converted into a gray scale value, and whether there is a droplet overflow defect can be quickly determined according to the gray scale value. In a substrate, the non-printing area surrounding the printing area only needs to be determined once, which can greatly improve the droplet overflow defect detection efficiency in the printing area.
[0011] In a possible implementation, after the image to be detected is obtained, the method further includes: dividing the image to be detected into a plurality of region images in a preset direction, and numbering the plurality of region images in a preset order; one region image corresponds to one region number, and the plurality of region images include a first region image, the preset direction is a direction in which the second barrier surrounds the first barrier; performing region gray scale projection on the first region image to obtain a first region gray scale projection value; and if the first region gray scale projection value is greater than a preset region threshold value, it is determined that the first region image has a droplet overflow defect.
[0012] In the above scheme, the position of the defect can be further located on the basis that the image to be detected has a droplet overflow defect. That is, the annular image to be detected is divided into a plurality of region images; after the initial position is preset, the region images are numbered in sequence in a clockwise or counterclockwise order of the annular shape. The region gray scale projection is performed on each numbered region image to determine whether the region has a droplet overflow defect. After the position of the defect is located, it is convenient for subsequent adjustment of inkjet printing parameters.
[0013] In a possible implementation, the image to be detected is divided into a plurality of region images in a preset direction, specifically including: in the preset direction, the image to be detected is divided into a plurality of region images according to a preset droplet overflow defect size; wherein the preset droplet overflow defect size is the smallest droplet overflow defect size in a plurality of historical droplet overflow defect sizes.
[0014] The above scheme illustrates the preferred method for setting the size when dividing an image into regions along a preset direction. Selecting the minimum size among multiple historical ink droplet overflow defect sizes allows for better defect location. This not only improves defect detection efficiency through regional grayscale projection, but also enhances defect detection accuracy. In the above description, the preset ink droplet overflow defect size can be the minimum ink droplet overflow defect size, half the minimum ink droplet overflow defect size, or other values; it can be set based on actual needs.
[0015] In a possible implementation, the preset distance range is determined by the camera positioning accuracy; wherein, the preset distance range L=a*α, a is the pixel size corresponding to the camera positioning accuracy, and α is the empirical value coefficient.
[0016] The above scheme illustrates how to set the width of the area to be inspected. This area is the area where ink overflows when an ink droplet overflow defect occurs. This area is set based on the camera's positioning accuracy. α is an empirical coefficient, which allows for a certain size margin based on the camera's positioning accuracy. This can be set based on actual needs.
[0017] In a possible implementation, the preset region threshold is smaller than the preset image threshold.
[0018] In the above scheme, the preset region threshold and the preset image threshold are different. When the two are different, the preset region threshold can be lower than the preset image threshold for more accurate identification. If no ink droplet overflow defect has occurred, the grayscale value of the image to be inspected should be 0, that is, completely black. If an ink droplet overflow defect has occurred, the grayscale value in the image to be inspected will not be 0. The grayscale value is related to the ink droplet material, the amount of ink droplet overflow, the area of ink droplet overflow, and the number of ink droplet overflows. Therefore, there is no limit on the values of the above two thresholds and they can be set according to actual conditions.
[0019] In a possible implementation, the image grayscale projection is the sum of the grayscale values of pixels in each row and column in the image, and the regional grayscale projection is the sum of the grayscale values of pixels in each row and column in the regional image.
[0020] In the above scheme, the purpose is to illustrate that image grayscale projection is to sum the grayscale values of all pixels in the image, which is equivalent to enhancing the grayscale value and can more intuitively reflect whether there is an ink droplet overflow defect in the image to be inspected; the same is true for regional grayscale projection. When the method of summing the grayscale values of each pixel is adopted, because the image to be inspected has more pixels than the regional image, the above-mentioned preset regional threshold should be smaller than the preset image threshold. In addition, the preset image threshold can further distinguish the number of ink droplet overflow defects based on the change in the value; here, the distinction can be made based on the image grayscale projection value corresponding to the number of ink droplet overflow defects; the result of the distinction can be used as a reference or verification for subsequent regional images when locating the defect position.
[0021] In one possible embodiment, before acquiring the image to be detected, the offset angle calibration is performed on the image to be detected, and the calibration operation specifically includes: acquiring the image of the printing area; acquiring the angle between the direction of any column of sub-pixel pits in the image of the printing area and the camera projection direction, where the sub-pixel pit direction is any one of the R sub-pixel pit direction, the G sub-pixel pit direction, and the B sub-pixel pit direction; if the angle is not 0°, adjusting the angle to 0° to complete the angle calibration of the image to be detected.
[0022] In the above scheme, if the image to be inspected experiences an angular offset, this will affect ink droplet overflow defect detection, especially if the size of the inspection area is set. After the image to be inspected is angularly calibrated, ink droplet overflow defect detection for the image to be inspected will be more accurate. Therefore, the above scheme does not rely on complex angle offset acquisition using markers on the substrate, but directly uses the direction of a column of sub-pixel pits as a reference. After the sub-pixel pits are printed by the inkjet printer, they will appear highlighted on the image, making them easier to detect. Furthermore, the sub-pixel pits are all micron-sized, serving as a reference for the offset angle, making the offset angle acquisition more accurate.
[0023] In one possible embodiment, before acquiring the image to be detected, an image calibration operation is performed using a calibration sphere: the image calibration operation includes: acquiring a calibration sphere image, the calibration sphere image including images of the calibration sphere and a support rod for fixing the calibration sphere; identifying the contour of the calibration sphere image; marking an area in the X-axis direction of the contour; acquiring multiple difference values; the difference value is the difference between two intersection points of the marking line and the contour in the X-axis direction; selecting a baseline, and selecting a contour within a preset range on the Y-axis as the contour to be fitted; the baseline is the marking line where the maximum difference value among the multiple differences is located; performing a circle fitting operation according to the contour to be fitted to obtain the diameter of the circle; so as to subsequently obtain the actual size of the pixel points in the image to be detected and complete the image calibration operation.
[0024] The above scheme aims to illustrate how to quickly and automatically perform calibration operations. In the substrate, the width of the barrier dam is at the micron level, and a calibration ball needs to be used for precise calibration to facilitate the subsequent detection of ink droplet overflow defects. The calibration ball is often connected to the inkjet printer through a support rod. In the current calibration process, pictures of the substrate and the calibration ball are generally taken manually, and then the circular part of the calibration ball is manually intercepted, and the support rod part connected to the calibration ball is removed; then the circular part of the calibration ball is fitted with a circle, and finally the fitting diameter of the fitted circle is obtained. In the manual calibration process, it is necessary to find a calibration ball of only a few hundred microns on a large-size substrate; it is time-consuming, labor-intensive, and inefficient. The above process can automatically identify the contour of the calibration ball image, automatically select the circular part of the calibration ball, fit the diameter of the circle, and then complete the subsequent calibration operation.
[0025] In a possible embodiment, the spacing between any two adjacent lines in the area markings and the preset range are determined by the camera pixel size; wherein, the spacing between any two adjacent lines H = (b / M)*C*β, b is the camera pixel size, M is the camera magnification, C is the empirical value of the number of pixels corresponding to the diameter of the calibration sphere image, and β is the empirical value coefficient; the preset range W = 2*(b / M)*D*θ, b is the camera pixel size, M is the camera magnification, D is the number of pixels corresponding to the baseline, and θ is the empirical value coefficient.
[0026] The above scheme is intended to illustrate how to set the spacing and preset range; specific values are not limited. This setting ensures that the selected baseline length is close to the diameter of the final fitted circle. Furthermore, the circular contour of the calibration sphere is incorporated into the fitted circle as much as possible, making the final fitted diameter more accurate.
[0027] In a possible implementation, the substrate image includes multiple images to be detected, and any image to be detected corresponds to an image number.
[0028] In the above scheme, the substrate image has multiple printing areas, each corresponding to a non-printing area, and each non-printing area corresponding to an image to be inspected. The printing area, also known as the luminous area, is also the display area of the printed product. The numbering of the images to be inspected also helps locate the location of ink droplet overflow defects.
[0029] According to a second aspect of the present application, a device for detecting ink droplet overflow on a substrate is disclosed. The device is configured to detect ink droplet overflow defects after an inkjet printer has encapsulated and printed the substrate. The substrate comprises a printing area and a non-printing area, the non-printing area comprising a barrier dam. The barrier dam surrounds the printing area to prevent ink droplets printed by the inkjet printer from overflowing, and the ink droplets are used to encapsulate the printing area. The barrier dam comprises a first barrier dam and a second barrier dam, wherein the first barrier dam is close to the printing area and the second barrier dam surrounds the first barrier dam. The device comprises a processor, a memory, a user interface, and a network interface. The memory is configured to store instructions. The user interface and the network interface are both configured to communicate with other devices. The processor is configured to execute the instructions stored in the memory so that the device executes the following instructions:
[0030] Acquire an image to be detected, wherein the image to be detected includes an image formed at a preset distance adjacent to the second barrier dam in a direction away from the printing area;
[0031] Performing image grayscale projection on the image to be detected to obtain an image grayscale projection value of the image to be detected;
[0032] If the image grayscale projection value is greater than a preset image threshold, it is confirmed that the image to be detected has an ink drop overflow defect.
[0033] The beneficial effects of this application include:
[0034] An optical camera can directly capture an image within a preset distance range outside the second barrier dam. This image within the preset distance range is then projected into grayscale, converting the image within the preset distance range into a grayscale value. This grayscale value can then be used to quickly determine whether an ink droplet overflow defect exists. On a single substrate, the non-printing area surrounding a printed area only needs to be evaluated once, significantly improving the efficiency of ink droplet overflow defect detection within the printed area.
[0035] Based on the presence of an ink droplet overflow defect in the image to be inspected, the defect's location can be further located. Specifically, the annular image to be inspected is divided into multiple regional images. After the initial position is preset, the regional images are numbered in a clockwise or counterclockwise order. A grayscale projection is performed on each numbered regional image to determine whether an ink droplet overflow defect exists in that area. Once the defect location is located, subsequent adjustment of inkjet printing parameters is facilitated.
[0036] When dividing an image into regions in a preset direction, the preferred setting method for the size is as follows. Selecting the minimum size among multiple historical ink droplet overflow defect sizes can better locate the defect; this not only improves the efficiency of defect detection through regional grayscale projection, but also improves the accuracy of defect detection. In the above, the preset ink droplet overflow defect size can be the minimum ink droplet overflow defect size, half of the minimum ink droplet overflow defect size, or other values; it can be set according to actual needs;
[0037] How to set the width of the area to be inspected. The area to be inspected is the area where ink overflows when an ink droplet overflow defect occurs. This area to be inspected is set based on the positioning accuracy of the camera. α is an empirical value coefficient, which means that a certain size redundancy is considered based on the positioning accuracy of the camera. It can be set according to actual needs.
[0038] The preset area threshold and the preset image threshold are different; when the two are different, the preset area threshold can be lower than the preset image threshold for more accurate recognition. If no ink droplet overflow defect occurs, the grayscale value of the image to be tested should be 0, that is, completely black; if an ink droplet overflow defect occurs, the grayscale value of the image to be tested will not be 0. The grayscale value is related to the ink droplet material, ink droplet overflow amount, ink droplet overflow area, ink droplet overflow number, etc. Therefore, there is no limit on the values of the above two thresholds and they can be set according to actual conditions.
[0039] Image grayscale projection is to sum the grayscale values of all pixels in the image, which is equivalent to enhancing the grayscale value, and can also more intuitively reflect whether there is an ink drop overflow defect in the image to be detected; the same is true for regional grayscale projection. When the method of summing the grayscale values of each pixel is adopted, because the image to be detected has more pixels than the regional image, the above-mentioned preset regional threshold should be smaller than the preset image threshold. In addition, the preset image threshold can further distinguish the number of ink drop overflow defects according to the change of the value; here, the distinction can be made based on the image grayscale projection value corresponding to the number of ink drop overflow defects; the result of the distinction can be used as a reference or verification for subsequent regional images when locating the defect position;
[0040] If the image to be inspected is offset at an angle, it will affect the detection of ink droplet overflow defects, especially the size setting of the inspection area. After the image to be inspected is calibrated at an angle, ink droplet overflow defect detection for the image to be inspected will be more accurate. Therefore, the above solution directly uses the direction of a column of sub-pixel pits as a reference. After the sub-pixel pits are printed by the inkjet printer, they will appear highlighted on the image and are easy to detect. Moreover, the sub-pixel pits are all micron-level, which serves as a reference for the offset angle, making the offset angle detection more accurate.
[0041] Calibration is performed quickly and automatically. The width of the barrier dam on the substrate is micron-sized, requiring precise calibration using a calibration sphere to facilitate subsequent detection of ink droplet overflow defects. Manual calibration requires searching for a calibration sphere measuring only a few hundred microns on a large substrate, which is time-consuming, labor-intensive, and inefficient. The above process automatically identifies the contours of the calibration sphere image, selects the circular portion of the calibration sphere, and fits the diameter of the circle to complete subsequent calibration operations.
[0042] The spacing and preset range settings can make the selected baseline length close to the diameter of the final fitting circle; and the circular contour of the calibration sphere is allowed to participate in the fitting circle as much as possible, making the final fitting diameter more accurate;
[0043] The substrate image has multiple print areas, each corresponding to a non-print area, and each non-print area corresponds to an image to be inspected. The print area, also known as the luminous area, is also the visible area of the printed product. The images to be inspected are numbered to locate ink overflow defects. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] Figure 1 This is a flow chart of a method for detecting ink droplet overflow on a substrate disclosed in this application specification;
[0045] Figure 2 This is a schematic structural diagram of a printing area and a non-printing area in a substrate disclosed in this application specification;
[0046] Figure 3 This is a schematic diagram of the area division of an image to be detected disclosed in this application specification;
[0047] Figure 4 This is a schematic structural diagram of a column of sub-pixel pits in a printing area disclosed in this application specification;
[0048] Figure 5 A schematic diagram of a calibration process for an image based on a calibration sphere disclosed in this application specification;
[0049] Figure 6 This is a schematic structural diagram of an ink droplet overflow detection device for a substrate disclosed in this application specification.
[0050] like Figures 1-6 : a first barrier dam 100 , a second barrier dam 200 , a product cutting line 300 , a sub-pixel pit array 400 ; a first region image 301 , a second region image 302 , and a third region image 303 . DETAILED DESCRIPTION
[0051] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments.
[0052] In the description of the embodiments of this application, words such as "for example" or "for instance" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "for example" or "for instance" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "for example" or "for instance" is intended to present the relevant concepts in a concrete manner.
[0053] In the description of the embodiments of the present application, the term "multiple" means two or more. For example, multiple systems refer to two or more systems, and multiple screen terminals refer to two or more screen terminals. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.
[0054] This specification discloses a method for detecting ink droplet overflow on a substrate. The substrate comprises a printing area and a non-printing area. The non-printing area includes a barrier dam. The barrier dam surrounds the printing area to prevent ink droplets from overflowing from an inkjet printer. The ink droplets are used to encapsulate the printing area. The barrier dam includes a first barrier dam and a second barrier dam, with the first barrier dam being located near the printing area and the second barrier dam surrounding the first barrier dam.
[0055] like Figure 2 As described, the barrier dam (the first barrier dam 100 and the second barrier dam 200 are arranged around the printing area); the printing area is also the luminous area, that is, the display area of the product. The first barrier dam 100 and the edge of the printing area constitute a leveling area, which is convenient for the leveling of the ink droplets printed by the inkjet printer. The second barrier dam 200 is arranged around the first barrier dam 100, and the ink droplets printed by the package overflow the second barrier dam 200, that is, the package printing is unqualified. Therefore, this specification mainly discusses whether there are ink droplets in the area outside the second barrier dam 200, that is, the area between the second barrier dam 200 and the product edge line (that is, the product dividing line 300). If there are no ink droplets in this area, the area will be completely black when the automatic optical inspection equipment (Automatic Optical Inspection, AOI) performs inspection; if there are ink droplets overflowing in this area, the area will not be completely black, that is, the grayscale value will change.
[0056] Furthermore, on large substrates (e.g., G8.5, which measures 2200mm x 2500mm in width and height), the typical width and height dimensions for small to medium-sized tablets, mobile phone screens, or electronic watches range from tens to hundreds of millimeters. Multiple product images are displayed on large substrates, making ink spill detection on these images crucial for efficient inspection. This manual discusses improving ink spill detection efficiency from two perspectives: image selection and inspection methods.
[0057] Generally speaking, you can sample multiple display product images on a substrate and perform ink droplet overflow defect detection on a small number of display product images. By using the images to be tested in this manual, you can sample a larger number of samples, or even perform a full inspection on all the images to be tested on the substrate, significantly improving inspection efficiency.
[0058] The method includes steps S101-S03.
[0059] Step S101 : Acquire an image to be detected, where the image to be detected is an image within a preset distance range adjacent to the second barrier dam in a direction away from the printing area.
[0060] like Figure 2 As shown, the image to be inspected is located within a predetermined distance from the second barrier dam in the direction away from the printing area; that is, the area between the second barrier dam 200 and the product edge (i.e., the product dividing line 300). Inspecting this area can directly indicate whether there is an ink droplet overflow defect in the printing area.
[0061] This specification does not limit the method for obtaining the image to be inspected. The optical inspection machine has a white light interferometry (WSI) hardware device that can determine the height of the barrier dam. After locating the position of the second barrier dam through the WSI, the image to be inspected can be determined according to the above example. Alternatively, the printed area can be photographed by a camera (displayed as a bright area after encapsulation printing), and the position of the second barrier dam can be located based on the fixed distance between the edge of the printed area and the second barrier dam, and then the image to be inspected can be determined according to the above example. This specification does not explain this in detail.
[0062] It should be noted that the edge of the second barrier dam is often inclined or curved; in the above example, being adjacent to the second barrier dam includes being close to the edge of the second barrier dam, or maintaining a certain distance from the top surface of the second barrier dam.
[0063] In one example, the preset distance range is determined by the camera positioning accuracy; wherein, the preset distance range L=a*α, a is the pixel size corresponding to the camera positioning accuracy, and α is the empirical value coefficient.
[0064] This example sets the width of the inspection area corresponding to the image to be inspected. The inspection area is the area where ink overflows when an ink droplet overflow defect occurs. This area is set based on the camera's positioning accuracy. α is an empirical coefficient that takes into account a certain size margin based on the camera's positioning accuracy. This value can be set based on actual needs.
[0065] For example, if the camera's positioning accuracy is 20 μm, and the width of a pixel in the image to be detected is 2 μm, this is equivalent to a positioning accuracy of 10 pixels. The preset distance can be selected as 50 or 100 pixels.
[0066] S102 , performing image grayscale projection on the image to be detected to obtain an image grayscale projection value of the image to be detected.
[0067] S103: If the image grayscale projection value is greater than a preset image threshold, it is determined that an ink drop overflow defect exists in the image to be detected.
[0068] In the above example, an optical camera can directly capture an image within a preset distance range outside the second barrier dam. This image within the preset distance range is then projected into grayscale, converting the image within the preset distance range into a grayscale value. This grayscale value can then be used to quickly determine whether an ink overflow defect exists. On a single substrate, the non-printing area surrounding the printed area of a display product only needs to be evaluated once, significantly improving the efficiency of ink overflow defect detection within the printed area.
[0069] In the above, if the image grayscale projection value is less than or equal to the preset image threshold, it is confirmed that there is no ink droplet overflow defect in the image to be tested. When an ink droplet overflow defect exists in the image to be tested, the specific location of the ink droplet overflow defect in the image to be tested can be located by dividing the image to be tested into regions. By locating the specific location of the ink droplet overflow defect, subsequent analysis of the cause of the ink droplet overflow defect and other situations is facilitated. Of course, it is also possible to directly divide the image to be tested into regions and test the regional images; while improving the efficiency of ink droplet overflow defect detection, the specific location of the ink droplet overflow defect is also determined.
[0070] The following describes a method for dividing the image to be detected into regions.
[0071] In one example, in a preset direction, the image to be inspected is divided into multiple area images, and the multiple area images are numbered in a preset order; one area image corresponds to one area number, and the multiple area images include a first area image, and the preset direction is the direction in which the second barrier dam surrounds the first barrier dam; regional grayscale projection is performed on the first area image to obtain a first area grayscale projection value; if the first area grayscale projection value is greater than the preset area threshold, it is confirmed that there is an ink drop overflow defect in the first area image.
[0072] At this time, if the grayscale projection value of the first region is less than or equal to the preset region threshold, it is determined that there is no ink drop overflow defect in the first region image. The first region image is only used as an example. For any region image, regional grayscale projection is performed and the above ink drop overflow defect judgment is performed.
[0073] like Figure 3 As shown, the top middle of the above-mentioned area to be detected is selected as the starting position (it can also be other positions), and the area to be detected is divided in a clockwise (or counterclockwise) order. Figure 3 Three divided regional images are shown as an example: first regional image 301, second regional image 302, and third regional image 303. These regional images can be numbered in a predetermined sequence. The numbering scheme can include three fields: the first field is the row number of the display product corresponding to the image to be inspected in the substrate image; the second field is the column number of the display product corresponding to the image to be inspected in the substrate image; and the third field is a clockwise serial number. For example, the first regional image is numbered 111, the second regional image is numbered 112, and the third regional image is numbered 113.
[0074] The above description divides the image to be detected into regional images. The length of the regional image division is explained below.
[0075] In one example, the image to be detected is divided into multiple regional images in a preset direction, specifically including: in the preset direction, the image to be detected is divided into multiple regional images according to a preset ink droplet overflow defect size; wherein the preset ink droplet overflow defect size is the smallest ink droplet overflow defect size among multiple historical ink droplet overflow defect sizes.
[0076] This section aims to illustrate the preferred size setting method when dividing regional images in a preset direction. Selecting the minimum size among multiple historical ink droplet overflow defect sizes can better locate the defect; this not only improves defect detection efficiency through regional grayscale projection, but also enhances defect detection accuracy. In the above description, the preset ink droplet overflow defect size can be the minimum ink droplet overflow defect size, half the minimum ink droplet overflow defect size, or other values, without limitation; it can be set according to actual needs.
[0077] It should be noted that if Figure 3 In the second area image 302, when the area image is within the arc transition area, the defect size is divided according to the length of the arc.
[0078] In one example, the preset region threshold is smaller than the preset image threshold.
[0079] In this manual, the preset region threshold and the preset image threshold are different. When the two are different, the preset region threshold can be lower than the preset image threshold for more accurate identification. If no ink droplet overflow defect has occurred, the grayscale value of the image to be inspected should be 0, i.e., completely black. If an ink droplet overflow defect has occurred, the grayscale value of the image to be inspected will not be 0. The grayscale value is related to the ink droplet material, the amount of ink droplet overflow, the area of ink droplet overflow, and the number of ink droplet overflows. Therefore, the values of the two thresholds are not limited and can be set according to actual conditions.
[0080] In one example, the image grayscale projection is the sum of the grayscale values of pixels in each row and column in the image, and the regional grayscale projection is the sum of the grayscale values of pixels in each row and column in the regional image.
[0081] In this case, image grayscale projection sums the grayscale values of all pixels in the image, effectively enhancing the grayscale values and providing a more intuitive indication of whether the image under inspection has ink droplet overflow defects. The same applies to regional grayscale projection. When summing the grayscale values of each pixel, the preset regional threshold should be lower than the preset image threshold because the image under inspection has more pixels than the regional image.
[0082] In addition, the preset image threshold can further distinguish the number of ink droplet overflow defects based on the change in the numerical value; here, the distinction can be made based on the image grayscale projection value corresponding to the number of ink droplet overflow defects; the result of the distinction can be used as a reference or verification for subsequent regional images when locating the defect position.
[0083] It should be noted that the image grayscale projection and regional grayscale projection described in this specification can also be performed by summing the grayscale values of the image to be detected and the regional image and then taking the average value. In this case, the setting of the preset regional threshold and the preset image threshold requires separate consideration, which is different from the above-mentioned method of directly summing the grayscale values of each pixel in the image to be detected and the regional image. This specification does not explain this in detail.
[0084] In one example, before acquiring the image to be detected, the offset angle of the image to be detected is calibrated, and the calibration operation specifically includes: acquiring an image of the printing area; acquiring the angle between the direction of any column of sub-pixel pits in the image of the printing area and the camera projection direction, where the sub-pixel pit direction is any one of the R sub-pixel pit direction, the G sub-pixel pit direction, and the B sub-pixel pit direction; if the angle is not 0°, the angle is adjusted to 0° to complete the angle calibration of the image to be detected.
[0085] In this example, if the image to be detected is offset at an angle, it will affect the detection of ink droplet overflow defects, especially the size setting of the area to be detected, and the size of the regional image division; after the angle of the image to be detected is calibrated, the ink droplet overflow defect detection of the image to be detected will be more accurate.
[0086] To improve angle calibration efficiency, the above solution does not rely on complex angle offset acquisition using markers on the substrate, but directly uses the direction of a column of sub-pixel pits as a reference. After the sub-pixel pits are printed with ink droplets by an inkjet printer, they will appear highlighted on the image and are easy to acquire. Moreover, the sub-pixel pits are all at the micron level, which serves as a benchmark for the offset angle, making the acquisition of the offset angle more accurate.
[0087] like Figure 4 The image shows a row of sub-pixel pits after ink droplets are printed by an inkjet printer. If there is no angular offset between the direction of the sub-pixel pit row 400 and the camera projection direction, the included angle is 0°. The angular offset can be obtained in this way.
[0088] In the above-mentioned ink drop overflow defect detection, the pixel size in the image is particularly important. In the substrate, the width of the barrier dam is in the micron level, and it is necessary to use a calibration ball for accurate calibration to facilitate the subsequent detection of ink drop overflow defects. The calibration ball is often connected to the inkjet printer through a support rod (such as Figure 5 (As shown in Figure a), the current calibration process typically involves manually capturing images of the substrate and calibration sphere. The circular portion of the calibration sphere is then manually captured, and the supporting rod attached to the sphere is removed. A circle is then fitted to the circular portion of the calibration sphere, ultimately obtaining the fitted diameter of the fitted circle. This manual calibration process requires searching for a calibration sphere measuring only a few hundred microns on a large substrate, which is time-consuming, labor-intensive, and inefficient.
[0089] Based on this, this note discusses how to quickly and automatically perform calibration operations.
[0090] In one example, before acquiring the image to be detected, an image calibration operation is performed using a calibration sphere: the image calibration operation includes: acquiring a calibration sphere image, the calibration sphere image including images of the calibration sphere and a support rod for fixing the calibration sphere; identifying the contour of the calibration sphere image; marking an area in the X-axis direction of the contour; acquiring multiple difference values; the difference value is the difference between the two intersection points of the marking line and the contour in the X-axis direction; selecting a baseline, and selecting a contour within a preset range on the Y-axis as the contour to be fitted; the baseline is the marking line where the maximum difference value among the multiple difference values is located; performing a circle fitting operation according to the contour to be fitted to obtain the diameter of the circle; so as to subsequently obtain the actual size of the pixel points in the image to be detected and complete the image calibration operation.
[0091] like Figure 5 As shown, a shows the calibration ball captured by the camera and the support rod that fixes the calibration ball, that is, the calibration ball image; b shows a schematic diagram of the edge contour identified by the edge recognition algorithm (conventional algorithm, which is not explained in this manual); b also shows the area demarcation of the edge contour, where any line has two intersections with the contour; for example, (x1, y1) and (x1, y2) are a group, (x2, y3) and (x2, y4) are a group, and (x3, y5) and (x3, y6) are a group; take the difference between each group, that is, y2-y1, y4-y3, y6-y5; obviously, the difference between y4-y3 is the largest, and the line where the difference lies is used as the baseline. c shows that after the baseline is selected, the contour within the preset range is selected as the contour to be fitted.
[0092] In this example, after obtaining the diameter of the fitted circle, the number of pixels corresponding to that diameter can be calculated. Based on these two values, the size of the pixels in the image can be obtained. The aforementioned regional image division lengths and preset distances can also use pixel size as the basic unit for length calculation.
[0093] In one example, the spacing between any two adjacent lines in the area marking and the preset range are determined by the camera pixel size; wherein, the spacing between any two adjacent lines H = (b / M)*C*β, b is the camera pixel size, M is the camera magnification, C is the empirical value of the number of pixels corresponding to the diameter of the calibration sphere image, and β is the empirical value coefficient; the preset range W = 2*(b / M)*D*θ, b is the camera pixel size, M is the camera magnification, D is the number of pixels corresponding to the baseline, and θ is the empirical value coefficient.
[0094] In this example, there is no limit on the specific values of the spacing and preset range. The above setting method can make the selected baseline length close to the diameter of the final fitting circle; and let the circular outline of the calibration sphere participate in the fitting circle as much as possible, so that the final fitting diameter is more accurate. The camera pixel size and camera magnification are fixed parameters of the camera. b / M is the object plane pixel size. Here is a theoretical value, and the error is larger than the error after calibration with the calibration sphere. C is an empirical value and is not fixed; β and θ can be set according to actual needs. Figure 5 As shown in Figure c, a contour segment is selected above and below the baseline, which is the preset range in the above example.
[0095] In one example, the substrate image includes multiple images to be inspected, and any image to be inspected corresponds to an image number.
[0096] At this time, the numbering of the image to be inspected is also used to locate the location of the ink drop overflow defect, as in the above example, for the numbering of the regional images;
[0097] The present specification also discloses an ink drop overflow detection device for detecting ink drop overflow defects after an inkjet printer performs package printing on a substrate; the substrate includes a printing area and a non-printing area, the non-printing area includes a barrier dam, the barrier dam surrounds the printing area to prevent ink drops printed by the inkjet printer from overflowing, the barrier dam includes a first barrier dam and a second barrier dam, the first barrier dam is close to the printing area, and the second barrier dam surrounds the first barrier dam; the ink drop overflow detection device includes a processor, a memory, a user interface, and a network interface, the memory is used to store instructions, the user interface and the network interface are used to communicate with other devices, and the processor is used to execute the instructions stored in the memory to enable the ink drop overflow detection device to perform the following instructions:
[0098] obtain a to-be-detected image, the to-be-detected image includes an image formed at a preset distance adjacent to the second barrier dam in a direction away from the printing area; perform image gray projection on the to-be-detected image to obtain an image gray projection value of the to-be-detected image; and if the image gray projection value is greater than a preset image threshold value, it is determined that the to-be-detected image has an ink drop overflow defect.
[0099] In one example, after the to-be-detected image is obtained, the method further includes: dividing the to-be-detected image into a plurality of region images in a preset direction, and numbering the plurality of region images in a preset order; one region image corresponds to one region number, the plurality of region images include a first region image, and the preset direction is a direction in which the second barrier dam surrounds the first barrier dam; performing region gray projection on the first region image to obtain a first region gray projection value; and if the first region gray projection value is greater than a preset region threshold value, it is determined that the first region image has an ink drop overflow defect.
[0100] In one example, dividing the to-be-detected image into a plurality of region images in a preset direction specifically includes: dividing the to-be-detected image into a plurality of region images in a preset direction according to a preset ink drop overflow defect size; wherein the preset ink drop overflow defect size is the smallest ink drop overflow defect size in a plurality of historical ink drop overflow defect sizes.
[0101] In one example, the preset distance range is determined by camera positioning accuracy; wherein the preset distance range L=a*α, a is a pixel size corresponding to the camera positioning accuracy, and α is an empirical value coefficient.
[0102] In one example, the preset region threshold value is less than the preset image threshold value.
[0103] In one example, the image gray projection is to sum the pixel gray values of each row and each column in the image, and the region gray projection is to sum the pixel gray values of each row and each column in the region image.
[0104] In one example, before acquiring the image to be detected, the offset angle of the image to be detected is calibrated, and the calibration operation specifically includes: acquiring an image of the printing area; acquiring the angle between the direction of any column of sub-pixel pits in the image of the printing area and the camera projection direction, where the sub-pixel pit direction is any one of the R sub-pixel pit direction, the G sub-pixel pit direction, and the B sub-pixel pit direction; if the angle is not 0°, the angle is adjusted to 0° to complete the angle calibration of the image to be detected.
[0105] In one example, before acquiring the image to be detected, an image calibration operation is performed using a calibration sphere: the image calibration operation includes: acquiring a calibration sphere image, the calibration sphere image including images of the calibration sphere and a support rod for fixing the calibration sphere; identifying the contour of the calibration sphere image; marking an area in the X-axis direction of the contour; acquiring multiple difference values; the difference value is the difference between the two intersection points of the marking line and the contour in the X-axis direction; selecting a baseline, and selecting a contour within a preset range on the Y-axis as the contour to be fitted; the baseline is the marking line where the maximum difference value among the multiple difference values is located; performing a circle fitting operation according to the contour to be fitted to obtain the diameter of the circle; so as to subsequently obtain the actual size of the pixel points in the image to be detected and complete the image calibration operation.
[0106] In one example, the spacing between any two adjacent lines in the area marking and the preset range are determined by the camera pixel size; wherein, the spacing between any two adjacent lines H = (b / M)*C*β, b is the camera pixel size, M is the camera magnification, C is the empirical value of the number of pixels corresponding to the diameter of the calibration sphere image, and β is the empirical value coefficient; the preset range W = 2*(b / M)*D*θ, b is the camera pixel size, M is the camera magnification, D is the number of pixels corresponding to the baseline, and θ is the empirical value coefficient.
[0107] In one example, the substrate image includes multiple images to be inspected, and any image to be inspected corresponds to an image number.
[0108] It should be noted that the above embodiments provide devices that implement their functions using only the division of the above functional modules as examples. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device and method embodiments provided in the above embodiments are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.
[0109] The specification also discloses a computer-readable storage medium, which stores instructions. When the instructions are executed, the above method is executed.
[0110] This embodiment also discloses an electronic device, which may be the ink drop overflow detection device described above, to perform the above method. Figure 6 The electronic device may include: at least one processor 601 , at least one communication bus 602 , a display 603 , a network interface 604 , and at least one memory 605 .
[0111] The communication bus 602 is used to implement the connection and communication between these components.
[0112] The display 603 may include a display screen (Display) and a camera (Camera).
[0113] The network interface 604 may optionally include a standard wired interface or a wireless interface (such as a WI-FI interface).
[0114] The processor 601 may include one or more processing cores. The processor 601 utilizes various interfaces and circuits to connect various components within the server. It executes instructions, programs, code sets, or instruction sets stored in the memory 605, as well as accesses data stored in the memory 605, to perform various server functions and process data. Optionally, the processor 601 may be implemented using at least one hardware form selected from the group consisting of a digital signal processing (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 601 may integrate one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), and a modem. The CPU primarily processes the operating system, user interface, and application programs; the GPU is responsible for rendering and drawing the content displayed on the display; and the modem handles wireless communications. It is understood that the modem may not be integrated into the processor 601 and may be implemented as a separate chip.
[0115] Among them, the memory 605 may include a random access memory 605 (Random Access Memory, RAM), and may also include a read-only memory 605 (Read-Only Memory). Optionally, the memory 605 includes a non-transitory computer-readable storage medium. The memory 605 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 605 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data involved in the above-mentioned various method embodiments, etc. The memory 605 may also be at least one storage device located away from the aforementioned processor 601. As shown in the figure, the memory 605 as a computer storage medium may include an operating system, a network communication module, and application programs of a display module.
[0116] exist Figure 6 In the electronic device shown, the display 603 is mainly used to provide an input interface for the user and obtain data input by the user; and the processor 601 can be used to call the application stored in the memory 605. When executed by one or more processors 601, the electronic device executes one or more methods in the above embodiments.
[0117] It should be noted that for the aforementioned method embodiments, for simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required for this application.
[0118] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0119] In the several embodiments provided in this application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely schematic, such as the division of units, which is only a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some service interface, and the indirect coupling or communication connection of devices or units can be electrical or other forms.
[0120] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.
[0121] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.
[0122] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory 605. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a memory 605 and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the present application. The aforementioned memory 605 includes various media that can store program code, such as a USB flash drive, a mobile hard drive, a magnetic disk, or an optical disk.
[0123] The above are merely exemplary embodiments of the present disclosure and are not intended to limit the scope of the present disclosure. That is, any equivalent changes and modifications made in accordance with the teachings of the present disclosure are still within the scope of the present disclosure. After considering the disclosure of the specification and the truth of practice, those skilled in the art will easily think of other embodiments of the present disclosure. This application is intended to cover any variations, uses or adaptations of the present disclosure, which follow the general principles of the present disclosure and include common knowledge or customary technical means in the art that are not recorded in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.
Claims
1. A method for detecting ink drop overflow on a substrate, characterized in that: The substrate includes a printing area and a non-printing area, and the non-printing area includes a barrier dam; the barrier dam surrounds the printing area to prevent ink droplets printed by the inkjet printer from overflowing, and the ink droplets are used to encapsulate the printing area; The barrier dam includes a first barrier dam and a second barrier dam, wherein the first barrier dam is close to the printing area and the second barrier dam surrounds the first barrier dam; wherein the method includes: Acquire an image to be detected, where the image to be detected is an image within a preset distance range adjacent to the second barrier dam in a direction away from the printing area; Performing image grayscale projection on the image to be detected to obtain an image grayscale projection value of the image to be detected; If the image grayscale projection value is greater than a preset image threshold, it is confirmed that the image to be detected has an ink drop overflow defect.
2. The ink drop overflow detection method according to claim 1, characterized in that: After acquiring the image to be detected, the method further includes: In a preset direction, the image to be detected is divided into a plurality of regional images, and the plurality of regional images are numbered in a preset order; one regional image corresponds to one regional number, the plurality of regional images include a first regional image, and the preset direction is a direction in which the second barrier dam surrounds the first barrier dam; Performing regional grayscale projection on the first regional image to obtain a first regional grayscale projection value; If the grayscale projection value of the first region is greater than a preset region threshold, it is determined that an ink drop overflow defect exists in the image of the first region.
3. The ink drop overflow detection method according to claim 2, characterized in that: In a preset direction, the image to be detected is divided into multiple area images, specifically including: In a preset direction, the image to be inspected is divided into a plurality of regional images according to a preset ink drop overflow defect size; wherein, The preset ink droplet overflow defect size is the smallest ink droplet overflow defect size among multiple historical ink droplet overflow defect sizes.
4. The ink drop overflow detection method according to claim 1, wherein: The preset distance range is determined by the camera positioning accuracy; wherein, The preset distance range L=a*α, where a is the pixel size corresponding to the camera positioning accuracy, and α is the empirical value coefficient.
5. The ink drop overflow detection method according to claim 2, characterized in that: The preset area threshold is smaller than the preset image threshold.
6. The ink drop overflow detection method according to claim 2, characterized in that: The image grayscale projection is the sum of the grayscale values of the pixels in each row and column in the image, and the regional grayscale projection is the sum of the grayscale values of the pixels in each row and column in the regional image.
7. The ink drop overflow detection method according to claim 1, characterized in that: Before acquiring the image to be detected, the image to be detected is calibrated for offset angle. The calibration operation specifically includes: acquiring an image of the printing area; Obtaining an angle between a direction of a sub-pixel pit in any column in the image of the printing area and a camera projection direction, wherein the sub-pixel pit direction is any one of an R sub-pixel pit direction, a G sub-pixel pit direction, and a B sub-pixel pit direction; If the angle is not 0°, the angle is adjusted to 0° to complete the angle calibration of the image to be detected.
8. The ink drop overflow detection method according to claim 1, wherein: Before acquiring the image to be detected, an image calibration operation is performed using a calibration sphere. The image calibration operation includes: Acquire a calibration sphere image, the calibration sphere image including an image of the calibration sphere and a support rod fixing the calibration sphere; Identifying the outline of the calibration sphere image; Performing area marking in the X-axis direction of the outline; Acquire multiple difference values; the difference values are the difference values between two intersection points of the line and the contour in the X-axis direction; Select a baseline, and select a contour within a preset range on the Y axis as the contour to be fitted; the baseline is a line where the maximum difference among the plurality of differences is located; A circle fitting operation is performed according to the contour to be fitted to obtain the diameter of the circle; so as to subsequently obtain the actual size of the pixel points in the image to be detected and complete the image calibration operation.
9. The ink drop overflow detection method according to claim 8, characterized in that: The spacing between any two adjacent lines in the area markings and the preset range are determined by the camera pixel size; wherein, The spacing between any two adjacent lines is H = (b / M)*C*β, where b is the camera pixel size, M is the camera magnification, C is the empirical value of the number of pixels corresponding to the diameter of the calibration sphere image, and β is the empirical value coefficient; The preset range W=2*(b / M)*D*θ, where b is the camera pixel size, M is the camera magnification, D is the number of pixels corresponding to the baseline, and θ is the empirical value coefficient.
10. An ink droplet overflow detection device for a substrate, characterized in that: The ink drop overflow detection device is used to detect ink drop overflow defects after the inkjet printer performs packaging printing on the substrate; the substrate includes a printing area and a non-printing area, and the non-printing area includes a barrier dam; The barrier dam surrounds the printing area to prevent ink droplets printed by the inkjet printer from overflowing, and the ink droplets are used to encapsulate the printing area; The barrier dam includes a first barrier dam and a second barrier dam, wherein the first barrier dam is close to the printing area, and the second barrier dam surrounds the first barrier dam; The ink drop overflow detection device includes a processor, a memory, a user interface, and a network interface. The memory is used to store instructions. The user interface and the network interface are both used to communicate with other devices. The processor is used to execute the instructions stored in the memory, so that the ink drop overflow detection device executes the following instructions: Acquire an image to be detected, where the image to be detected is an image within a preset distance range adjacent to the second barrier dam in a direction away from the printing area; Performing image grayscale projection on the image to be detected to obtain an image grayscale projection value of the image to be detected; If the image grayscale projection value is greater than a preset image threshold, it is confirmed that the image to be detected has an ink drop overflow defect.