Image acquisition device and method for screen defect detection

Abstract

The present invention relates to an image acquisition device and method for screen defect detection, comprising a host computer and an image sampling component; the host computer determines the number of sampling times according to the width of the screen to be detected, determines the sampling position of each sampling according to the number of sampling times, and generates a sampling signal; the image sampling component moves the screen to be detected according to the sampling signal, and when moving to each sampling position, uses a linear array camera module to perform image sampling of the screen to be detected according to a preset sampling frequency to obtain multiple sampled images; the host computer splices the sampled images obtained each time to obtain a screen spliced image, and saves it. The host computer of the present invention can control the movement of the screen to be detected through the image sampling component, and control the image sampling component to perform sampling and splicing at a specified sampling position through the linear array camera module, providing a more accurate and comprehensive image for subsequent analysis of screen defects, and can meet the detection requirements of screens of different sizes.

Description

Technical Field

[0001] The present invention relates to the field of image acquisition technology, and in particular to an image acquisition device and method for screen defect detection. Background Art

[0002] The in-vehicle display screen is the primary display for smart cockpit content, and its appearance and performance directly determine the user experience. During the actual production and assembly process, it is necessary to detect defective screens to avoid delivering poorly-looking products to customers.

[0003] Traditional screen defect detection methods use area array cameras. When a product arrives at the inspection station, it remains stationary. The area array camera then samples the screen surface and transmits the results to a host computer, which determines the quality of the screen. However, the current poor quality of screen image capture results inaccurate inspection results, and the inability to detect screen defects while the screen is in motion makes inspection efficiency low. Furthermore, for large screens, such as dual-panel screens and tall and wide screens, multiple area array cameras are required to image the screen's exterior to maintain the same inspection accuracy, which increases costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an image acquisition device and method for screen defect detection in response to the deficiencies of the existing technology.

[0005] The technical solution of the present invention to solve the above technical problems is as follows: an image acquisition device for screen defect detection, comprising a host computer and an image sampling component;

[0006] The host computer is used to determine the number of sampling times according to the width of the screen to be detected, determine the sampling position of each sampling according to the number of sampling times, and generate a sampling signal;

[0007] The image sampling component is used to move the screen to be detected according to the sampling signal, and when it moves to each sampling position, use the line array camera module to sample the screen to be detected according to a preset sampling frequency to obtain multiple sampled images;

[0008] The host computer is further used to splice the sampled images of each sampling respectively to obtain a screen spliced image and save it.

[0009] The beneficial effects of the present invention are as follows: the host computer can determine the sampling times and sampling positions according to the width of different screens to be detected, and control the image sampling component to move the screen to be detected through the sampling signal, and use the linear array camera module to perform image sampling and splicing at each sampling position. During the movement of the screen to be detected, the host computer can control the image sampling component to perform sampling at the specified sampling position, providing more accurate and comprehensive images for subsequent analysis of screen defects, and can meet the detection needs of screens of different sizes.

[0010] On the basis of the above technical solution, the present invention can also be improved as follows.

[0011] Furthermore, the host computer is also used to detect the spliced image when a preset time is reached. If the detection result is that there is no screen defect, continue sampling and detection. If the detection result is that there is a screen defect, control the image sampling component to stop sampling.

[0012] The beneficial effect of adopting the above further solution is: if the detection screen is a large-size screen, it is not necessary to collect all images before performing detection, which wastes time. Immediate detection after a certain period of time can not affect subsequent screen detection.

[0013] Furthermore, the image acquisition component includes a first sliding guide rail, a second sliding guide rail, a screen carrying platform, a linear array camera module, a photoelectric position sensor, a first PLC module and a second PLC module; stripes are provided on both sides of the upper surface of the screen carrying platform;

[0014] There are two first sliding guide rails, which are spaced apart and arranged in parallel. The screen carrying platform is located between the two first sliding guide rails, and both ends of the screen carrying platform are slidably connected to the first sliding guide rails on their respective sides.

[0015] The second sliding guide rail is located above the first sliding guide rail and spans between the two first sliding guide rails, and is on the same side as the screen to be inspected placed on the screen supporting platform, and both sides of the second sliding guide rail are slidably connected to the first sliding guide rails on their respective sides;

[0016] The linear array camera module is slidably connected to the second sliding guide rail, and the photoelectric position sensor is fixedly connected to the second sliding guide rail;

[0017] The first PLC module is electrically connected to the host computer, the first sliding guide rail, and the second sliding guide rail respectively, and the second PLC module is electrically connected to the linear array camera module.

[0018] Furthermore, in the image sampling component, the screen to be detected is moved according to the sampling signal. When it moves to each sampling position, the line array camera module is used to sample the screen to be detected according to a preset sampling frequency to obtain multiple sampled images, specifically:

[0019] The first PLC module is used to control the screen carrying platform to pass through each sampling position in sequence from top to bottom on the first sliding guide rail at a preset movement speed V according to the sampling signal;

[0020] The photoelectric position sensor is configured to send a shooting signal to the second PLC module when sensing the screen to be detected on the screen carrying platform;

[0021] The second PLC module is configured to activate the linear array camera module according to a shooting signal;

[0022] The line array camera module is used to perform image sampling on the screen to be inspected according to a preset sampling frequency to obtain multiple screen images at current sampling positions.

[0023] The beneficial effects of adopting the above-mentioned further scheme are: the first PLC module can control the screen to be inspected to move on the first sliding guide rail, and control the second sliding guide rail to move to each sampling position. The photoelectric position sensor and the linear array camera module sense and shoot the screen to be inspected, and can collect more accurate and comprehensive images; stripes are provided on both sides of the upper surface of the screen supporting platform, and when splicing, it can be confirmed whether the front and rear sampling locations are in the same position.

[0024] Furthermore, when obtaining multiple screen images of the current sampling position, the image sampling component is further configured to:

[0025] The photoelectric position sensor is further configured to send a stop acquisition signal to the first PLC module and the second PLC module when no screen to be detected on the screen carrying platform is sensed;

[0026] The second PLC module is further configured to shut down the linear array camera module according to the stop acquisition signal;

[0027] The first PLC module is further configured to control the second sliding guide rail to move to a next sampling position according to the stop sampling signal;

[0028] The photoelectric position sensor is further configured to send a shooting signal to the second PLC module when it senses the screen to be detected on the screen carrying platform again;

[0029] The second PLC module is used to restart the linear array camera module according to the shooting signal;

[0030] The line array camera module is used to perform image sampling on the screen to be inspected again according to a preset sampling frequency to obtain multiple screen images at the next sampling position.

[0031] The beneficial effect of adopting the above further solution is: when the acquisition of one acquisition position is completed, the host computer controls the first PLC module to move the second sliding guide rail to the next sampling position, and the second PLC module controls the linear array camera module to start again for shooting and sampling.

[0032] Furthermore, in the host computer, the number of samplings is determined according to the width of the screen to be detected, and the sampling position of each sampling is determined according to the number of samplings, specifically:

[0033] The sampling times are calculated by the sampling calculation formula, which is n=W / W L , where n is the number of sampling times, W is the width of the screen to be detected, and W L is the FOV width of the linear array camera module under the specified detection accuracy;

[0034] The sampling positions of n samples are determined on the second sliding guide rail according to the sampling number n.

[0035] The beneficial effect of adopting the above further solution is that the corresponding acquisition times and sampling positions can be determined according to the widths of different screens to be detected.

[0036] Furthermore, in the host computer, the screen images sampled each time are spliced together to obtain a spliced image, and the spliced image is saved, specifically:

[0037] If there is a screen image sampled previously, the screen image sampled this time is spliced with the screen image sampled previously to obtain a spliced image, and the spliced image is saved in a preset first memory. If there is no screen image sampled previously, the screen image sampled this time is directly saved in the first memory; at the same time,

[0038] If there is a screen image of the previous sampling, the screen image of this sampling is compared with the screen images of the previous two samplings for similarity. If the similarity value is less than the threshold S, the screen image of this sampling is spliced with the screen images of the previous n samplings to obtain a spliced image, and the spliced image is saved in the preset second memory. Otherwise, no splicing is performed.

[0039] The beneficial effect of adopting the above further solution is: saving the directly stitched images into one memory, and performing image stitching after similarity comparison on different sampled images and saving them into another memory, which can provide more comprehensive sampled images.

[0040] Furthermore, in the host computer, the screen image of the current sampling is compared with the screen images of the previous two samplings for similarity, specifically:

[0041] The linear array camera module in the image sampling component is calibrated in advance to obtain the angle α of the screen image relative to the horizontal direction and the position deviation D of the translation, and the image is obtained. The image is calculated by the similarity formula Screen images from the previous two samples and screen images Perform similarity comparison to obtain a similarity value. The similarity calculation formula is:

[0042]

[0043] Among them, S m represents the similarity value, and Cov(·) represents the correlation operator.

[0044] The beneficial effect of adopting the above further solution is that each time sampling is performed, the screen image of this sampling is compared with the screen images of the previous two samplings for similarity, and after comparison, it is determined whether to splice, which can improve the accuracy of the spliced screen.

[0045] Furthermore, a checkerboard calibration plate is placed on the screen carrying platform in advance;

[0046] In the host computer, the linear array camera module in the image sampling component is calibrated, specifically:

[0047] The screen carrying platform is controlled by the first PLC module to move downward on the first sliding guide rail at a preset movement speed V. When passing through the second sliding guide rail, the linear array camera module is controlled to take multiple shots of the checkerboard calibration plate at a preset sampling frequency to obtain multiple checkerboard calibration plate images, and the multiple checkerboard calibration plate images are spliced to obtain a spliced image I. s ;

[0048] For the stitched image I s Perform edge detection to obtain the checkerboard edge image I e ;

[0049] According to the edge straight line of the checkerboard calibration plate, the angle α of the edge straight line relative to the horizontal direction is obtained;

[0050] According to the requirement that the width of the split image is consistent with the image captured by the linear array camera module, the checkerboard edge image I e Split and obtain edge sub-image sequence {I e0 , I e1 ,…Ien};

[0051] According to the position difference formula and edge sub-image sequence {I e0 , I e1 ,…I en}Calculate the position deviation of two adjacent edge sub-images, the position deviation formula is:

[0052]

[0053] Among them, I ei+1 and I ei represents two adjacent edge sub-images, D is the position deviation between two adjacent edge sub-images, and n is the number of all edge sub-images.

[0054] The beneficial effect of adopting the above further solution is: pre-calibrating the linear array camera module to obtain the angle and position deviation that need to be adjusted, thereby improving the accuracy of the stitched image.

[0055] Another technical solution of the present invention to solve the above technical problem is as follows: an image acquisition method for screen defect detection, comprising the following steps:

[0056] Determine the number of sampling times according to the width of the screen to be detected, determine the sampling position of each sampling according to the number of sampling times, and generate a sampling signal;

[0057] The screen to be detected is moved according to the sampling signal, and when it moves to each sampling position, the screen to be detected is sampled by a line array camera module according to a preset sampling frequency to obtain a plurality of sampled images;

[0058] The sampled images of each sampling are stitched together to obtain a screen stitching image and save it.

[0059] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0061] Figure 1 A schematic diagram of a module of an image acquisition device provided by an embodiment of the present invention;

[0062] Figure 2A schematic structural diagram of an image acquisition device provided by an embodiment of the present invention;

[0063] Figure 3 A schematic diagram of a flow chart of an image acquisition method provided by an embodiment of the present invention;

[0064] Figure 4 A schematic diagram of the process flow of a defect detection algorithm provided by an embodiment of the present invention.

[0065] In the accompanying drawings, the names of the components represented by the various symbols are as follows:

[0066] 1. Host computer; 2. First sliding guide rail; 3. Second sliding guide rail; 4. Screen carrying platform; 5. Linear array camera module; 6. Photoelectric position sensor; 7. First PLC module; 8. Second PLC module; 9. Screen to be tested. DETAILED DESCRIPTION

[0067] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0068] Example 1:

[0069] like Figure 1 As shown, an image acquisition device for screen defect detection includes a host computer 1 and an image sampling component;

[0070] The host computer 1 is used to determine the number of sampling times according to the width of the screen 9 to be detected, determine the sampling position of each sampling according to the number of sampling times, and generate a sampling signal;

[0071] The image sampling component is used to move the screen to be detected 9 according to the sampling signal, and when it moves to each sampling position, use the line array camera module 4 to sample the screen to be detected 9 according to a preset sampling frequency to obtain multiple sampled images;

[0072] The host computer 1 is further configured to splice the sampled images obtained at each sampling time to obtain a screen spliced image and save the spliced image.

[0073] In the above embodiment, the host computer 1 can determine the sampling times and sampling positions according to the width of different screens to be detected 9, and control the image sampling component to move the screen to be detected 9 through the sampling signal, and use the line array camera module 4 to perform image sampling and splicing at each sampling position. During the movement of the screen to be detected 9, the host computer 1 can control the image sampling component to perform sampling at the specified sampling position, thereby providing more accurate and comprehensive images for subsequent analysis of screen defects, and can meet the detection requirements of screens of different sizes.

[0074] Specifically, the host computer 1 is further configured to detect the spliced image when a preset time is reached, and continue sampling and detecting if the detection result shows that there is no screen defect; and control the image sampling component to stop sampling if the detection result shows that there is a screen defect.

[0075] Specifically, the detection method can detect the spliced image through a defect detection algorithm. The defect detection algorithm process is as follows Figure 4 As shown in the figure. The main steps include: (a) image preprocessing; (b) image edge extraction; (c) image edge classification; (d) image edge screening; (e) contour extraction based on image edges; (f) defect recognition; (g) defect classification. Among them:

[0076] (a) Image preprocessing uses Gaussian blur;

[0077] (b) Image edge extraction uses the Sobel operator and the Canny operator to generate the corresponding edge image;

[0078] (c) When classifying image edges, the edges are divided into two categories according to edge direction and connectivity;

[0079] (d) Image edge screening mainly performs edge screening on the above two types of edges and excludes the determined non-defective edges;

[0080] (e) The stage of extracting the contour according to the image edge is mainly to extract the edge contour according to the image edge to form the candidate area of the defect;

[0081] (f) Based on the results of (d) and (e), identify whether each candidate defect area is a defect;

[0082] (g) Finally, each defect is classified into point defects, line defects, etc.

[0083] In the above embodiment, if the detection screen is a large-size screen, it is not necessary to collect all images before performing detection, which wastes time. Immediate detection after a certain period of time can avoid affecting subsequent screen detection.

[0084] like Figure 2As shown, specifically, the image acquisition component includes a first sliding guide rail 2, a second sliding guide rail 3, a screen carrying platform 4, a line array camera module 5, a photoelectric position sensor, a photoelectric sensor 6, a first PLC module 7 and a second PLC module 8; stripes are provided on both sides of the upper surface of the screen carrying platform 4;

[0085] There are two first sliding guide rails 2, which are spaced apart and arranged in parallel. The screen carrying platform 4 is located between the two first sliding guide rails 2, and both ends of the screen carrying platform 4 are slidably connected to the first sliding guide rails 2 on their respective sides.

[0086] The second sliding guide rail 3 is located above the first sliding guide rails 2 and spans between the two first sliding guide rails 2, and is on the same side as the screen to be tested 9 placed on the screen supporting platform 4. Both sides of the second sliding guide rail 3 are slidably connected to the first sliding guide rails 2 on their respective sides;

[0087] The linear array camera module 5 is slidably connected to the second sliding guide rail 3, and the photoelectric position sensor 6 is fixedly connected to the second sliding guide rail 3;

[0088] The first PLC module 7 is electrically connected to the host computer 1 , the first sliding guide rail 2 , and the second sliding guide rail 3 , respectively. The second PLC module 8 is electrically connected to the line array camera module 5 .

[0089] The linear array camera module 5 adopts a DALSA LA-GM-08K08A linear array camera; the photoelectric sensor 6 adopts an Omron E3F3 photoelectric sensor; and the first PLC module 7 and the second PLC module 8 both adopt a Siemens s7-200 PLC.

[0090] Specifically, in the image sampling component, the screen to be detected 9 is moved according to the sampling signal. When it moves to each sampling position, the line array camera module 5 is used to sample the screen to be detected 9 according to the preset sampling frequency to obtain multiple sampled images, specifically:

[0091] The first PLC module 7 is used to control the screen carrying platform 4 to pass through each sampling position in sequence from top to bottom on the first sliding guide rail 2 at a preset movement speed V according to the sampling signal;

[0092] The photoelectric position sensor 6 is used to send a shooting signal to the second PLC module 8 when sensing the screen to be detected 9 on the screen supporting platform 4;

[0093] The second PLC module 8 is used to start the linear array camera module 5 according to the shooting signal;

[0094] The line array camera module 5 is used to perform image sampling on the screen to be inspected 9 according to a preset sampling frequency to obtain multiple screen images at the current sampling position.

[0095] Specifically, the setting of the preset motion speed V can be achieved through the following principles:

[0096] (1) In order to achieve 100% coverage of the screen to be inspected, assuming that the width of the screen to be inspected 9 is W, the FOV width of the linear array camera under the specified inspection accuracy is W L , then the linear array camera module 5 needs to adjust W / W on the sliding guide rail 2 L times (rounded up here) position, thereby ensuring that 100% imaging coverage of the entire screen can be achieved after multiple position adjustments.

[0097] (2) Assuming that the screen supporting platform 4 moves at a uniform speed of V, the detection accuracy requirement of the screen surface to be detected is μ, and the sampling frequency of the linear array camera is H, in order to make the shooting frequency of the linear array camera match the movement speed of the screen, the relationship between the three can be expressed by the following formula: μH ≥ V.

[0098] In the above embodiment, the first PLC module can control the screen to be detected 9 to move on the first sliding guide rail 2, and control the second sliding guide rail 3 to move to each sampling position. The photoelectric position sensor 6 and the linear array camera module 5 sense and shoot the screen to be detected 9, and can collect more accurate and comprehensive images; stripes are provided on both sides of the upper surface of the screen supporting platform 4, and when splicing, it can be confirmed whether the front and rear sampling locations are in the same position.

[0099] Specifically, when obtaining multiple screen images of the current sampling position, the image sampling component is further used to:

[0100] The photoelectric position sensor 6 is further configured to send a stop acquisition signal to the first PLC module 7 and the second PLC module 8 when the screen to be detected 9 on the screen carrying platform 4 cannot be sensed;

[0101] The second PLC module 8 is further configured to shut down the linear array camera module 5 according to the stop acquisition signal;

[0102] The first PLC module 7 is further configured to control the second sliding guide rail 3 to move to the next sampling position according to the stop sampling signal;

[0103] The photoelectric position sensor 6 is further configured to send a shooting signal to the second PLC module 8 when it senses the screen to be detected 9 on the screen carrying platform 4 again;

[0104] The second PLC module 8 is used to restart the linear array camera module 5 according to the shooting signal;

[0105] The line array camera module 5 is used to perform image sampling on the screen to be inspected 9 again according to a preset sampling frequency to obtain multiple screen images at the next sampling position.

[0106] Preferably, when sampling images again, the second PLC module 8 controls the linear array camera module 5 to move laterally to another position on the second sliding guide rail 3, that is, different from the previous position, so as to obtain captured images at different positions on the screen.

[0107] In the above embodiment, when the acquisition of one acquisition position is completed, the host computer 1 controls the first PLC module 7 to move the second sliding guide rail 3 to the next sampling position, and the second PLC module 8 controls the linear array camera module 5 to start shooting and sampling again.

[0108] Specifically, the host computer 1 determines the number of sampling times according to the width of the screen 9 to be detected, and determines the sampling position of each sampling according to the number of sampling times, specifically:

[0109] The sampling times are calculated by the sampling calculation formula, which is n=W / W L , where n is the number of sampling times, W is the width of the screen 9 to be detected, and W L is the FOV width of the linear array camera module 5 under the specified detection accuracy;

[0110] The sampling positions of n samples are determined on the second sliding guide rail 3 according to the sampling number n.

[0111] It should be understood that the specific sampling positions are set, and when the sampling number is determined, the sampling positions can be determined. For example, if the sampling number n is 3, then sampling is performed at position 1, position 2, and position 3 of the first sliding guide rail, i.e., three sampling positions.

[0112] In the above embodiment, the corresponding acquisition times and sampling positions can be determined according to the widths of different screens 9 to be detected.

[0113] Specifically, in the host computer 1, the screen images sampled each time are spliced together to obtain a spliced image, and the spliced image is saved, specifically as follows:

[0114] If there is a screen image sampled previously, the screen image sampled this time is spliced with the screen image sampled previously to obtain a spliced image, and the spliced image is saved in a preset first memory. If there is no screen image sampled previously, the screen image sampled this time is directly saved in the first memory; at the same time,

[0115] If there is a screen image of the previous sampling, the screen image of this sampling is compared with the screen images of the previous two samplings for similarity. If the similarity value is less than the threshold S, the screen image of this sampling is spliced with the screen images of the previous n samplings to obtain a spliced image, and the spliced image is saved in the preset second memory. Otherwise, no splicing is performed.

[0116] In the above embodiment, directly stitched images are saved in one memory, and different sample images are compared for similarity before image stitching and saved in another memory, which can provide more comprehensive sample images.

[0117] Specifically, the host computer 1 compares the similarity between the screen image sampled this time and the screen images sampled two times previously, specifically:

[0118] The linear array camera module 5 in the image sampling component is calibrated in advance to obtain the angle α of the screen image relative to the horizontal direction and the position deviation D of the translation, and the image is obtained. The image is calculated by the similarity formula Screen images from the previous two samples and screen images Perform similarity comparison to obtain a similarity value. The similarity calculation formula is:

[0119]

[0120] Among them, S m represents the similarity value, and Cov(·) represents the correlation operator.

[0121] It should be understood that although the line scan camera is fixed to the second sliding rail 3, its imaging plane cannot be guaranteed to be completely parallel to the plane of the screen. Therefore, it is necessary to calibrate it to ensure the accuracy of subsequent image stitching. Specifically, before capturing an image of the screen 9 to be inspected, the line scan camera module 5 is first calibrated.

[0122] In the above embodiment, each time sampling is performed, the screen image of the current sampling is compared with the screen images of the previous two samplings for similarity, and after the comparison, it is determined whether to perform splicing, which can improve the accuracy of the spliced screen.

[0123] Specifically, a checkerboard calibration plate is placed on the screen carrying platform 4 in advance;

[0124] In the host computer 1, the linear array camera module 5 in the image sampling component is calibrated, specifically:

[0125] The screen carrying platform 4 is controlled by the first PLC module 7 to move downward on the first sliding guide rail 2 at a preset movement speed V. When passing through the second sliding guide rail 3, the linear array camera module 5 is controlled to take multiple shots of the checkerboard calibration plate at a preset sampling frequency to obtain multiple checkerboard calibration plate images, and the multiple checkerboard calibration plate images are spliced to obtain a spliced image I. s ;

[0126] For the stitched image I s Perform edge detection to obtain the checkerboard edge image I e ;

[0127] According to the edge straight line of the checkerboard calibration plate, the angle α of the edge straight line relative to the horizontal direction is obtained;

[0128] According to the requirement that the width of the split image is consistent with the image captured by the linear array camera module 5, the checkerboard edge image I e Split and obtain edge sub-image sequence {I e0 , I e1 ,…I en};

[0129] According to the position difference formula and edge sub-image sequence {I e0 , I e1 ,…I en}Calculate the position deviation of two adjacent edge sub-images, the position deviation formula is:

[0130]

[0131] Among them, I ei+1 and I ei represents two adjacent edge sub-images, D is the position deviation between two adjacent edge sub-images, and n is the number of all edge sub-images.

[0132] In the above embodiment, the line array camera module 5 is calibrated in advance to obtain the angle and position deviation that need to be adjusted, thereby improving the accuracy of the stitched image.

[0133] like Figure 3 As shown, an image acquisition method for screen defect detection includes the following steps:

[0134] S1: Determine the number of sampling times according to the width of the screen to be detected, determine the sampling position of each sampling according to the number of sampling times, and generate a sampling signal;

[0135] S2: moving the screen to be inspected according to the sampling signal, and when moving to each sampling position, using a line array camera module to sample the screen to be inspected at a preset sampling frequency to obtain multiple sampled images;

[0136] S3: stitching the sampled images of each sampling respectively to obtain a screen stitching image, and save it.

[0137] Specifically, an image acquisition method for screen defect detection has the following overall process:

[0138] H1: At the beginning, the host computer sends a command to the first PLC module to control the second sliding guide to move to the following position: Figure 2 At position 1 shown, keep the position fixed.

[0139] H2: The screen is placed on the screen carrying platform, and the first PLC module controls the screen carrying platform to start moving from top to bottom along the sliding guide rail 1. The first PLC module sets the movement speed of the carrying platform to V.

[0140] H3: When the photoelectric position sensor on the second sliding guide rail detects the arrival of the screen, the host computer triggers the linear array camera module to start image acquisition.

[0141] H4: The linear array camera module images the screen at a certain sampling frequency H according to the movement speed of the carrier platform.

[0142] H5: The host computer pre-applies for two memories, the first memory and the second memory. The first memory is used to store directly stitched images, and the second memory is used to store processed stitched images.

[0143] H6: Each time a sample is taken, it is directly spliced with the previous image and stored in the first memory. At the same time, the image sampled this time is compared with the previous two sampling images. If the similarity is less than the threshold S, it is spliced with the previous image and stored in the second memory. If it is greater than the threshold S, no splicing is performed.

[0144] H7: After imaging for a certain period of time (T), perform defect detection on the stitched images in the first and second memories. If any image in the first and second memories is detected to have a defect, there is no need to continue image sampling and detection (no more detection: if it is a large screen, it is time-consuming to detect after acquisition. If it is detected after a period of acquisition, it will not affect subsequent acquisition). If no defects are detected, continue sampling and detection.

[0145] H8: When the screen moves to completely exceed the position of the second sliding guide rail, the photoelectric position sensor cannot detect the screen. At this time, the host computer stops the linear array camera module from continuing to collect images.

[0146] H9: The host computer controls the first PLC module to control the second sliding guide to move to position 2. The PLC module 2 controls the linear array camera module to move to Figure 2 Position 2 shown.

[0147] H10: The screen carrying platform continues to move along the sliding guide rail 1. When the lower edge of the screen reaches the position of the linear scan camera module, the photoelectric position sensor detects the screen. At this time, the host computer triggers the linear scan camera module to start image acquisition.

[0148] H11: Repeat steps H4 to H7.

[0149] H12: When the screen moves to completely exceed the position of the second sliding guide rail, the photoelectric position sensor cannot detect the screen, and the host computer stops image acquisition and completes the detection.

[0150] H13: Assume that the width of the screen to be inspected is W, and the FOV width of the linear array camera under the specified inspection accuracy is W L , then the position of the linear array camera module on the second sliding rail needs to be adjusted W / W L times; in this example, assuming W / W L =2, then when the screen completely passes through position 2, there is no need to adjust the position of the line scan camera module again, and it only needs to return to position 1 to detect the next screen.

[0151] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0152] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. An image acquisition device for screen defect detection, characterized in that: Including host computer and image sampling components; The host computer is used to determine the number of sampling times according to the width of the screen to be detected, determine the sampling position of each sampling according to the number of sampling times, and generate a sampling signal; The image sampling component is used to move the screen to be detected according to the sampling signal, and when it moves to each sampling position, use the line array camera module to sample the image of the screen to be detected according to a preset sampling frequency to obtain multiple sampled images; The host computer is further used to splice the sampled images of each sampling respectively to obtain a screen spliced image and save it. Specifically, if there is a screen image of the previous sampling, the screen image of the current sampling is spliced with the screen image of the previous sampling to obtain a spliced image, and the spliced image is saved in a preset first memory. If there is no screen image of the previous sampling, the screen image of the current sampling is directly saved in the first memory; at the same time, If there is a screen image of the previous sampling, the screen image of the current sampling is compared with the screen images of the previous two samplings for similarity. If the similarity value is less than the threshold S, the screen image of the current sampling is spliced with the previous screen image to obtain a spliced image, and the spliced image is saved in the preset second memory. Otherwise, no splicing is performed.

2. The image acquisition device according to claim 1, wherein: The host computer is further configured to detect the spliced image when a preset time is reached, and continue sampling and detecting if the detection result shows that there is no screen defect; and control the image sampling component to stop sampling if the detection result shows that there is a screen defect.

3. The image acquisition device according to claim 1, wherein: The image sampling component includes a first sliding guide rail, a second sliding guide rail, a screen carrying platform, a linear array camera module, a photoelectric position sensor, a first PLC module and a second PLC module; stripes are provided on both sides of the upper surface of the screen carrying platform; There are two first sliding guide rails, which are spaced apart and arranged in parallel. The screen carrying platform is located between the two first sliding guide rails, and both ends of the screen carrying platform are slidably connected to the first sliding guide rails on their respective sides. The second sliding guide rail is located above the first sliding guide rail and spans between the two first sliding guide rails, and is on the same side as the screen to be inspected placed on the screen supporting platform, and both sides of the second sliding guide rail are slidably connected to the first sliding guide rails on their respective sides; The linear array camera module is slidably connected to the second sliding guide rail, and the photoelectric position sensor is fixedly connected to the second sliding guide rail; The first PLC module is electrically connected to the host computer, the first sliding guide rail, and the second sliding guide rail respectively, and the second PLC module is electrically connected to the linear array camera module.

4. The image acquisition device according to claim 3, characterized in that: In the image sampling component, the screen to be detected is moved according to the sampling signal. When it moves to each sampling position, the line array camera module is used to sample the screen to be detected according to a preset sampling frequency to obtain multiple sampled images, specifically: The first PLC module is used to control the screen carrying platform to pass through each sampling position in sequence from top to bottom on the first sliding guide rail at a preset movement speed V according to the sampling signal; The photoelectric position sensor is configured to send a shooting signal to the second PLC module when sensing the screen to be detected on the screen carrying platform; The second PLC module is configured to activate the linear array camera module according to a shooting signal; The line array camera module is used to perform image sampling on the screen to be inspected according to a preset sampling frequency to obtain multiple screen images at current sampling positions.

5. The image acquisition device according to claim 4, characterized in that: When obtaining multiple screen images of the current sampling position, the image sampling component is further used to: The photoelectric position sensor is further configured to send a stop acquisition signal to the first PLC module and the second PLC module when no screen to be detected on the screen carrying platform is sensed; The second PLC module is further configured to shut down the linear array camera module according to the stop acquisition signal; The first PLC module is further configured to control the second sliding guide rail to move to a next sampling position according to the stop sampling signal; The photoelectric position sensor is further configured to send a shooting signal to the second PLC module when it senses the screen to be detected on the screen carrying platform again; The second PLC module is used to restart the linear array camera module according to the shooting signal; The line array camera module is used to perform image sampling on the screen to be inspected again according to a preset sampling frequency to obtain multiple screen images at the next sampling position.

6. The image acquisition device according to claim 1, wherein: In the host computer, the number of sampling times is determined according to the width of the screen to be detected, and the sampling position of each sampling is determined according to the number of sampling times, specifically: The sampling times are calculated by the sampling calculation formula, which is n=W / W L , where n is the number of sampling times, W is the width of the screen to be detected, and W L is the FOV width of the linear array camera module under the specified detection accuracy; The sampling positions of n samples are determined on the second sliding guide rail according to the sampling number n.

7. The image acquisition device according to claim 1, characterized in that: In the host computer, the screen image of this sampling is compared with the screen images of the previous two samplings for similarity, specifically: The linear array camera module in the image sampling component is calibrated in advance to obtain the angle α of the screen image relative to the horizontal direction and the position deviation D of the translation, and the image is obtained. The image is calculated by the similarity formula Screen images from the previous two samples and screen images Perform similarity comparison to obtain a similarity value. The similarity calculation formula is: Among them, S m represents the similarity value, and Cov(·) represents the correlation operator.

8. The image acquisition device according to claim 7, characterized in that: Place the checkerboard calibration plate on the screen carrying platform in advance; In the host computer, the linear array camera module in the image sampling component is calibrated, specifically: The screen carrying platform is controlled by the first PLC module to move downward on the first sliding guide rail at a preset movement speed V. When passing through the second sliding guide rail, the linear array camera module is controlled to take multiple shots of the checkerboard calibration plate at a preset sampling frequency to obtain multiple checkerboard calibration plate images, and the multiple checkerboard calibration plate images are spliced to obtain a spliced image I. s ; For the stitched image I s Perform edge detection to obtain the checkerboard edge image I e ; According to the edge straight line of the checkerboard calibration plate, the angle α of the edge straight line relative to the horizontal direction is obtained; According to the requirement that the width of the split image is consistent with the image captured by the linear array camera module, the checkerboard edge image I e Split and obtain edge sub-image sequence {I e0 , I e1 ,…I en }; According to the position deviation formula and edge sub-image sequence {I e0 , I e1 ,…I en }Calculate the position deviation of two adjacent edge sub-images. The formula for the position deviation is: Among them, I ei+1 and I ei represents two adjacent edge sub-images, D is the position deviation between two adjacent edge sub-images, and n is the number of all edge sub-images.

9. An image acquisition method for screen defect detection, characterized in that: The steps include: Determine the number of sampling times according to the width of the screen to be detected, determine the sampling position of each sampling according to the number of sampling times, and generate a sampling signal; The screen to be detected is moved according to the sampling signal, and when it moves to each sampling position, the screen to be detected is sampled by a line array camera module according to a preset sampling frequency to obtain a plurality of sampled images; The sampled images of each sampling are respectively spliced to obtain a screen spliced image, and saved. Specifically, if there is a screen image of the previous sampling, the screen image of the current sampling is spliced with the screen image of the previous sampling to obtain a spliced image, and the spliced image is saved in a preset first memory. If there is no screen image of the previous sampling, the screen image of the current sampling is directly saved in the first memory; at the same time, If there is a screen image of the previous sampling, the screen image of the current sampling is compared with the screen images of the previous two samplings for similarity. If the similarity value is less than the threshold S, the screen image of the current sampling is spliced with the previous screen image to obtain a spliced image, and the spliced image is saved in the preset second memory. Otherwise, no splicing is performed.

Images