Method for detecting material shortage mounting of flexible circuit board material belt

Abstract

The invention discloses a detection method for material-lacking mounting of a flexible circuit board material belt. The detection method comprises the following steps: S1, acquiring a first image template and a second image template of a flexible circuit board; s2, acquiring a real-time image of the material belt by utilizing an area-array camera, and identifying whether a material shortage area exists in the material belt or not according to the real-time image; if it is recognized that the material belt has the material shortage area, the coordinate position of the material shortage area is obtained; s3, sucking the to-be-mounted flexible circuit board through a suction head, collecting a real-time image of the suction head by using a flying camera, identifying whether the suction head has the flexible circuit board or not according to the real-time image, and if the suction head has the flexible circuit board, converting the coordinate position of the material shortage area into a physical coordinate of the movement of the suction head; the suction head driving mechanism pastes the flexible circuit board to the material shortage area according to the physical coordinates; and S4, carrying out position detection on the flexible circuit board in the material shortage area after surface mounting. According to the invention, the calculation accuracy of the material shortage position is ensured, and the detection efficiency of the subsidy process is improved.

Description

Technical Field

[0001] The present invention relates to the field of detection technology, and particularly relates to a detection method for the lack of components in a flexible circuit board carrier tape for mounting. Background Art

[0002] Flexible printed circuit boards (referred to as FPCs) have been widely used in fields such as consumer electronics, automotive electronics, and medical equipment due to their advantages of high flexibility, light weight, and high space utilization rate, and have become an important part of high-density assembly of electronic products. In the production and manufacturing process of FPCs, carrier tapes are usually used for transmission and packaging to achieve batch automated production. During the loading process of FPCs, due to factors such as production processes, equipment precision, and material control, some defective FPCs may be loaded into the carrier tape. These defects may include broken wires, exposed copper, stains, indentations, foreign object contamination, etc., which seriously affect the product quality and the reliability of terminal devices.

[0003] To ensure production quality, an automatic optical inspection (AOI) system is usually configured on the production line to inspect the FPCs in the carrier tape and reject defective products that do not meet the quality standards. As high-precision electronic components, FPCs have a high production cost. If a notch appears in the carrier tape due to defect rejection, it will not only affect the subsequent mounting process but also may lead to a decrease in the overall production efficiency. Therefore, after AOI inspection, it is necessary to make up for the lack of components at the rejection position to ensure the integrity and continuity of the carrier tape, thereby improving production stability.

[0004] The existing method for making up the lack of components is mainly manual, which not only has low work efficiency but also easily introduces new position errors, affecting the subsequent mounting process. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the manual method for making up the lack of components not only has low work efficiency but also easily introduces new position errors, affecting the subsequent mounting process.

[0006] For this reason, the present invention provides a detection method for the lack of components in a flexible circuit board carrier tape for mounting, which on the one hand ensures the calculation accuracy rate of the lack of components position and on the other hand improves the detection efficiency during the process of making up the lack of components.

[0007] The technical solution adopted by the present invention to solve its technical problems is as follows: A detection method for the lack of components in a flexible circuit board carrier tape for mounting, comprising the following steps: S1. Obtain a first image template and a second image template of the flexible circuit board; S2. Use an area array camera to collect a real-time image of the carrier tape, and identify whether there is a lack of components area in the carrier tape according to the real-time image; if it is identified that there is a lack of components area in the carrier tape, obtain the coordinate position of the lack of components area; S3. Use the suction head to pick up the flexible circuit board to be mounted, collect the real-time image of the suction head by using the flying shot camera, identify whether there is a flexible circuit board on the suction head according to the real-time image. If it is identified that there is a flexible circuit board on the suction head, convert the coordinate position of the missing material area into the physical coordinates of the suction head movement, and the suction head driving mechanism mounts the flexible circuit board to the missing material area according to the physical coordinates; S4. Perform position detection on the flexible circuit board in the missing material area after mounting.

[0008] Further, step S2 specifically includes: S21. Create multiple rectangular frames that can contain the flexible circuit board. The upper left vertex coordinates of the rectangular frame are , and the lower right vertex coordinates are ; S22. Adjust the center coordinates of multiple said rectangular frames to the center position of the flexible circuit board in the first row of the real-time image of the tape in turn; and after each adjustment, use the first image template to match the region of interest framed by the rectangular frame, and retain the rectangular frame with the highest matching degree as the detection frame; S23. Use the detection frame to detect the real-time image of the tape, match the region framed by the detection frame with the first image template. If the match is successful, it is determined that there is a flexible circuit board in this region. If the match fails, it is determined that there is a missing material in this region, and this region is recorded as the missing material area; S24. Perform gray-scale feature analysis on the missing material area. If the gray-scale feature Gavg ≥ gray-scale threshold Tgray, it is determined that there is a foreign object in this missing material area, and feeding and mounting are prohibited; if the gray-scale feature Gavg < gray-scale threshold Tgray, it is determined that this missing material area can be fed and mounted.

[0009] Further, the flexible circuit boards on the tape are arranged in two columns and multiple rows; In step S2, obtaining the coordinate position of the missing material area includes: S25. Feed and mount the first row. If the missing material area is in the first row and there is no flexible circuit board in both columns of the first row of the real-time image of the tape, skip feeding and mounting the first row; If the missing material area is in the first row and there is a flexible circuit board in one of the columns of the first row of the real-time image of the tape, execute the feeding and mounting strategy for the first row; The feeding and mounting strategy for the first row includes: (i) When there is material in the left column of the first row and the right column is missing: Extract the feature point coordinates of the flexible circuit board in the left column , Based on the left edge line equation of the tape , where a, b, and c represent the coefficients of the equation, calculate the coordinates of the characteristic points The coordinates of the foot of the perpendicular to the left edge line : , , Obtain the distance between the right-column flexible circuit board and the left edge line according to the definition of the tape drawing , then the key point coordinates of the flexible circuit board to be replenished in the right column of the first row are : , ; (ii) When there is material in the right column of the first row and the left column is out of stock, exchange the above left and right parameters and perform symmetric operations.

[0010] Furthermore, in step S2, to obtain the coordinate position of the out-of-stock area, it further includes: S26. Replenish materials in non-first rows, Extract the characteristic point coordinates of the flexible circuit board in the row above the out-of-stock area in the same column and the inclination angle of the tape edge line , make a perpendicular line from the characteristic point coordinates to the tape edge line , and the coordinates of the foot of the perpendicular are , obtain the angle of the perpendicular line and the distance between the flexible circuit boards in the upper and lower rows ; Calculate the temporary coordinates : : , ; According to the temporary coordinates , the distance between the flexible circuit board in the column where the out-of-stock area is located and the edge line , the perpendicular line 's inclination angle , calculate the key point coordinates of the flexible circuit board to be replenished : , .

[0011] Furthermore, the calculation process of the characteristic point coordinates of the flexible circuit board includes: Define the lower right corner of the flexible circuit board as the characteristic point, and evenly generate N scanning lines on the right edge and the lower edge of the flexible circuit board image respectively. For each scanning line, perform: (i) Gray scale gradient calculation: , = 1 pixel, Pixel gradient, indicating the pixel value of the pixel point ; (ii) On each scan line, extract the points with the maximum grayscale gradient amplitude respectively to form the right edge point set and the bottom edge point set. The extreme point extraction formula: Extreme point ; Perform weighted least squares fitting on the right edge point set and the bottom edge point set respectively, with the weight being the grayscale gradient amplitude of the corresponding pixel point, to obtain two fitting lines: The bottom edge fitting line of the flexible circuit board image : , The right edge fitting line of the flexible circuit board image : , where , respectively represent the slopes of the bottom edge fitting line and the right edge fitting line, , respectively represent the intercepts of the corresponding lines; The bottom edge fitting line and the right edge fitting line The intersection point of is the feature point, and the feature point coordinates are: , .

[0012] Further, obtaining the first image template includes: Using an area array camera to collect an image of a qualified tape, and framing the region of interest containing the flexible circuit board from the image; Using the Canny operator and the Sobel gradient operator on the region of interest to extract the edge information of the flexible circuit board, and retaining the contour features, position features, and angle features of the flexible circuit board; Using the region of interest and its features to train the template, and the template that passes the training is used as the first image template; that is, the first image template is the image template of the flexible circuit board in the qualified tape; Obtaining the second image template includes: Using a flying shot camera to collect an image after the suction head picks up the flexible circuit board, and framing the region of interest containing the flexible circuit board from the image; Using the Canny operator and the Sobel gradient operator on the region of interest to extract the edge information of the flexible circuit board, and retaining the contour features, position features, and angle features of the flexible circuit board; Using the region of interest and its features to train the template, and the template that passes the training is used as the second image template; that is, the second image template is the image template of the flexible circuit board picked up by the suction head.

[0013] Further, identifying whether there is a flexible circuit board on the suction head includes: Matching the real-time image of the suction head with the second image template, and sending the matching result to the PLC in the form of a status code; Status code 0X01: indicates that there is a flexible circuit board on the suction head; Status code 0X02: indicates that there is no flexible circuit board on the suction head or the identification fails.

[0014] Further, step S4 specifically includes: S41. Scanning the flexible circuit board after replenishment and mounting row by row with the first image template to locate the position areas of all flexible circuit boards; S42. Extracting the coordinate of the feature points of the flexible circuit board within the position area of the flexible circuit board , For the flexible circuit board in the left column, calculating the horizontal distance between the coordinate of its feature points and the coordinate of the feature points of the adjacent flexible circuit board in the right column , and the vertical distance between the coordinate of the feature points of the adjacent flexible circuit board in the upper row ; For the flexible circuit board in the right column, calculating the horizontal distance between the coordinate of its feature points and the coordinate of the feature points of the adjacent flexible circuit board in the left column , and the vertical distance between the coordinate of the feature points of the adjacent flexible circuit board in the upper row ; If or The absolute value of the difference from the standard value ≤ 0.1 mm, it is determined that the distance is qualified; If or The absolute value of the difference from the standard value ≤ 0.1 mm, it is determined that the distance is qualified; S43. When both the horizontal distance and the vertical distance of the replenished flexible circuit board are qualified, it is determined that the current flexible circuit board replenishment is qualified, otherwise, it is determined that the replenishment is unqualified.

[0015] The beneficial effects of the present invention are as follows In terms of accuracy: Through testing, the accuracy of the calculation of the missing material position by the present invention reaches 99.3%. Compared with the traditional manual replenishment method and the general automatic recognition method of image processing, a huge improvement has been achieved in terms of accuracy.

[0016] Recognition efficiency: By recording the time taken for image detection, the present invention can complete the replenishment for more than 1000 pieces per hour for material shortage, significantly improving the production efficiency. Compared with the traditional manual counting method, the present invention has achieved a substantial improvement in both the recognition speed and the accuracy of replenishment, fully demonstrating the great advantages of the detection system in high-efficiency recognition and automated production.

[0017] The present invention has improved problems such as feeding offset and dislocation that are prone to occur in manual operations, forming an industrial-grade solution integrating high-precision detection and rapid response, and significantly improving the yield stability and automation level of the FPC production line. Brief Description of the Drawings

[0018] The present invention will be further described below in conjunction with the drawings and embodiments.

[0019] Figure 1 It is a flowchart of the detection method for the shortage mounting of the flexible circuit board tape of the present invention.

[0020] Figure 2 It is a schematic diagram of the real-time image of the tape collected by the area array camera of the present invention.

[0021] Figure 3 It is a schematic diagram of the first image template of the present invention.

[0022] Figure 4 It is a schematic diagram of the second image template of the present invention.

[0023] Figure 5 It is a schematic diagram of the detection frame outlining the region of interest of the present invention.

[0024] Figure 6 It is a schematic diagram of the matching between the first image template of the present invention and the region of interest within the detection frame.

[0025] Figure 7 It is a schematic diagram of the fitting of the tape edge line and the fitting of the flexible circuit board edge line of the present invention.

[0026] Figure 8 It is a schematic diagram of the calculation of the first row replenishment coordinates of the present invention.

[0027] Figure 9 It is a schematic diagram of the calculation of the non-first row replenishment coordinates of the present invention. Detailed Description of the Invention

[0028] The present invention will now be further described in detail in conjunction with the drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner, so they only show the components related to the present invention.

[0029] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0031] As Figure 1 and Figure 2 shown, the detection method for the missing component mounting of the flexible circuit board strip in this embodiment includes the following steps: S1. Obtain the first image template and the second image template of the flexible circuit board. S2. Use an area array camera to collect the real-time image of the strip, and identify whether there is a missing component area in the strip according to the real-time image; if it is identified that there is a missing component area in the strip, obtain the coordinate position of the missing component area. S3. Use a suction head to suck the flexible circuit board to be mounted, use a flying shot camera to collect the real-time image of the suction head, and identify whether there is a flexible circuit board on the suction head according to the real-time image. If it is identified that there is a flexible circuit board on the suction head, convert the coordinate position of the missing component area into the physical coordinates of the suction head movement, and the suction head driving mechanism mounts the flexible circuit board to the missing component area according to the physical coordinates. S4. Perform position detection on the flexible circuit board in the missing component area after mounting.

[0032] This embodiment can realize the automatic replenishment and mounting of the missing component area in the strip. On the one hand, it can improve the accuracy and accuracy of the replenishment and mounting. On the other hand, it can improve the working efficiency of the quality inspection of the strip.

[0033] It should be noted that when the tape is conveyed to the inspection station, a line array camera is used to capture the image of the tape, and it is identified whether there is a material shortage area in the current real-time image. If not, the tape continues to be conveyed forward, and the line array camera continues to capture the next area of the tape; if so, the coordinate position of the material shortage area is identified based on the real-time image, and the material replenishment and mounting process is carried out. The suction head adopted in this embodiment is a double suction head carried by a motion control mechanism. The suction head is used to suck the flexible circuit board to be mounted, and the flying shot camera shoots the suction head from bottom to top to identify whether there is material on the suction head.

[0034] In this embodiment, as Figure 3 shown, the first image template is the image template of the flexible circuit board in the qualified tape; as Figure 4 shown, the second image template is the image template of the suction head sucking the flexible circuit board. For example, obtaining the first image template includes: using a line array camera to collect the image of the qualified tape, and framing the region of interest containing the flexible circuit board from the image; using the Canny operator and the Sobel gradient operator to extract the edge information of the flexible circuit board from the region of interest, and retaining the contour features, position features, and angle features of the flexible circuit board; using the region of interest and its features to train the template, and the template that passes the training is used as the first image template. Obtaining the second image template includes: using the flying shot camera to collect the image after the suction head sucks the flexible circuit board, and framing the region of interest containing the flexible circuit board from the image; using the Canny operator and the Sobel gradient operator to extract the edge information of the flexible circuit board from the region of interest, and retaining the contour features, position features, and angle features of the flexible circuit board; using the region of interest and its features to train the template, and the template that passes the training is used as the second image template. For example, during the template training process, the template can be verified. When the error of image matching using the current template for 10 consecutive times ≤ 0.5 pixels, it is determined that the template training is qualified.

[0035] That is to say, in the process of obtaining the first image template and the second image template, the feature extraction process of the region of interest is similar. The reason for preparing two image templates in this embodiment is that since the image of the flexible circuit board mounted on the tape is different from the image captured when the flexible circuit board is sucked by the suction head, the first image template is used to match the flexible circuit board in the tape image, and the second image template is used to match the flexible circuit board in the suction head image, which is beneficial to improving the accuracy of image recognition and further improving the accuracy of subsidy.

[0036] In this embodiment, the flexible circuit boards on the tape are arranged in two columns and multiple rows. That is, two flexible circuit boards are mounted in each row. In the actual application process, the real-time image of the tape collected by the area array camera generally contains four complete flexible circuit boards. In the image, the first row is recorded as the first row, and the second row is recorded as the non-first row. The missing material area may appear in the first row or the non-first row. Therefore, when calculating the coordinate position of the missing material area, it is necessary to discuss by classification.

[0037] In step S2, the process of identifying the missing material area includes: S21. Create multiple rectangular frames that can contain the flexible circuit boards. The upper left vertex coordinates of the rectangular frame are and the lower right vertex coordinates are .

[0038] It should be noted that the rectangular frame is used to frame the region of interest in the real-time image of the tape that contains a complete flexible circuit board.

[0039] S22. Sequentially adjust the center coordinates of the multiple rectangular frames to the center position of the flexible circuit board in the first row of the real-time image of the tape; and after each adjustment, use the first image template to match the region of interest framed by the rectangular frame, and retain the rectangular frame with the highest matching degree as the detection frame.

[0040] Since the region of interest framed by the rectangular frame is closely related to the subsequent detection results, therefore, the generated rectangular frames need to be screened to select an optimal rectangular frame as the detection frame. The center coordinates of the rectangular frame are , and then move the center coordinates of the rectangular frame to the center of the flexible circuit board in the first row of the image. At this time, use the first image template to perform image matching on the region of interest framed by the rectangular frame. "Matching" can be understood as performing a normalized product correlation calculation (NCC) on the gradient amplitude and direction of the flexible circuit board in the first image template and the flexible circuit board in the region of interest. The calculation formula is: , the NCC value represents the matching degree (taking values from 0 to 1), represents the gradient normalization value of the first image template, represents the gradient normalization value of the region of interest. The matching degree threshold can be set to 0.6, and select the rectangular frame that exceeds the matching degree threshold and has the highest matching degree as the detection frame.

[0041] S23. Use the detection frame to detect the real-time image of the tape (as shown in Figure 5 and Figure 6 ), match the region framed by the detection frame with the first image template. If the match is successful, it is determined that there is a flexible circuit board in this region. If the match fails, it is determined that there is a missing material in this region, and this region is recorded as the missing material region.

[0042] It should be noted that during the detection process, the detection frame dynamically offsets in the real-time image of the tape to sequentially detect the first row and non-first rows in the real-time image. The offset rule is as follows: , , , , represents the horizontal widening value, represents the vertical length of the flexible circuit, represents the vertical preset spacing. That is to say, during the detection process, the detection frame is movable. Each time it moves, it can frame an area of interest, and then use the first image template to match the area of interest. If the match is successful, it indicates that there is a flexible circuit board in this area of interest; if the match fails, it means that there is no flexible circuit board in this area of interest, and this area of interest is recorded as a missing material area.

[0043] S24. Perform gray-scale feature analysis on the missing material area. If the gray-scale feature Gavg ≥ gray-scale threshold Tgray, it is determined that there is a foreign object in this missing material area, and the replenishment and mounting are prohibited; if the gray-scale feature Gavg < gray-scale threshold Tgray, it is determined that the missing material area can be replenished and mounted.

[0044] It should be noted that after determining a certain area as a missing material area, the replenishment and mounting procedure is not immediately carried out, but this missing material area is first analyzed to see if it is suitable for replenishment. Generally speaking, the tape itself is transparent. Therefore, the image gray-scale values of the tape itself are basically the same. Through gray-scale analysis, it can be judged whether the missing material area is suitable for replenishment. First, calculate the average gray-scale value of the missing material area (i.e., Gavg). If there is a foreign object in the missing material area, it will cause the average gray-scale value to increase significantly. Therefore, by analyzing the gray-scale features of the missing material area, it can be judged whether there is foreign object interference in this missing material area. If there is foreign object interference, it is not suitable for replenishment and mounting, which will affect the mounting effect.

[0045] To perform replenishment and mounting on the missing material area, the mounting coordinate position needs to be calculated. The calculation of the coordinate position is divided into two cases: the first row and non-first rows.

[0046] Case 1: S25. Replenishment for the first row, If the missing material area is located in the first row and there is no flexible circuit board in both columns of the first row of the real-time image of the tape, then skip the replenishment for the first row. If the missing material area is located in the first row and there is a flexible circuit board in one of the columns in the first row of the real-time image of the tape, then execute the replenishment and mounting strategy for the first row.

[0047] As Figure 7 and Figure 8 shown, the replenishment and mounting strategy for the first row includes: (i) When there is material in the left column of the first row and no material in the right column: Extract the coordinate of the feature points of the flexible circuit board in the left column , based on the equation of the left edge line of the tape , where a, b, and c represent the equation coefficients, calculate the coordinate of the feature points The coordinate of the foot of the perpendicular from the point to the left edge line : , , obtain the distance between the flexible circuit board in the right column and the left edge line according to the definition of the tape drawing , then the key point coordinate of the flexible circuit board to be replenished in the first row and right column is : , .

[0048] (ii) When there is material in the first row and right column and there is no material in the left column, exchange the above left and right parameters and perform symmetric operations.

[0049] It should be noted that when there is no flexible circuit board in both columns of the first row in the real-time image of the tape, the replenishment and mounting program is not performed and it is directly skipped. When there is one flexible circuit board (either in the left column or the right column) in the two columns of the first row in the real-time image of the tape, the replenishment and mounting of the first row can be performed. In this embodiment, when there is material in the first row and left column and there is no material in the right column, the feature points of the flexible circuit board in the left column and the left edge line of the tape are used as the reference basis to calculate the key point coordinates of the flexible circuit board to be replenished in the right column. Then, why not directly calculate the key point coordinates of the replenishment based on the feature points of the flexible circuit board in the right column and the mounting spacing? This is because when the flexible circuit board is mounted, there may be a certain deviation between the mounting spacing between the left and right columns and the standard spacing. The coordinates calculated by the deviated reference points are also deviated. Coupled with the error of the mechanical components themselves, the superposition of multiple errors will lead to inaccurate coordinates of the subsidy key points. This embodiment uses the tape line, the fixed distance between the mounted product in the right column and the tape edge line and the coordinate of the feature points of the mounted product in the left column as the basis to calculate the key point coordinates of the product to be replenished in the right column, which can reduce the superposition of errors and is beneficial to improving the accuracy of the key point coordinate calculation.

[0050] Case 2: S26, non-first-row replenishment, As Figure 9 shown, extract the coordinate of the feature points of the flexible circuit board in the upper row of the same column as the material-deficient area and the inclination angle of the tape edge line , draw a perpendicular line from the coordinate of the feature points to the tape edge line, and the coordinate of the foot of the perpendicular is , obtain the inclination angle of the perpendicular line and the distance between the flexible circuit boards in the upper and lower rows ; calculate the temporary coordinate : , ; According to the temporary coordinates , the distance between the flexible circuit board in the column where the material shortage area is located and the edge line , the vertical line 's angle , calculate the key point coordinates of the flexible circuit board to be replenished : , .

[0051] It should be noted that when performing replenishment and mounting on non-first rows, the reason why the strategy for replenishment and mounting on the first row cannot be adopted is that there are already products in the row above the non-first row in the image. At this time, when performing replenishment and mounting, the vertical spacing between the product to be replenished and the product in the row above and the horizontal spacing between the products in the same row need to be considered. Therefore, it is necessary to calculate the position of the replenished and mounted product by relying on the product in the row above. However, at this time, a problem that needs to be considered is that if the product in the row above is slightly misaligned, it will cause the position of the subsidized product to deviate, and this deviation will be transmitted row by row. Therefore, in this embodiment, when performing non-first row replenishment, it cannot be calculated solely based on the position of the product in the row above. The approach adopted in this embodiment is to calculate the key point coordinates based on the feature point coordinates of the product in the row above and the features of the tape edge line. Another problem that needs to be considered here is that although the tape edge line appears to be vertical as a whole, there may sometimes be a small inclination angle. Therefore, in this embodiment, when performing non-first row replenishment, by establishing a targeted geometric reference, the influence of the offset of the product in the row above is eliminated, ensuring that the replenishment coordinates are strictly aligned with the tape direction, thereby improving the mounting accuracy and consistency.

[0052] In this embodiment, the calculation process of the feature point coordinates of the flexible circuit board includes: Define the lower right corner of the flexible circuit board as the feature point, and evenly generate N scan lines on the right edge and the lower edge of the flexible circuit board image. For each scan line, execute: (i) Gray scale gradient calculation: , = 1 pixel, pixel gradient, represents the pixel value of the pixel point ; (ii) On each scan line, respectively extract the points with the maximum gray scale gradient amplitude to form the right edge point set and the lower edge point set. The extreme point extraction formula: Extreme point ; Perform weighted least squares linear fitting on the right edge point set and the lower edge point set respectively, with the weight being the gray scale gradient amplitude of the corresponding pixel point, to obtain two fitting lines: The fitting line of the lower edge of the flexible circuit board image : , The fitting line of the right edge of the flexible circuit board image : , wherein, 、 respectively represent the slopes of the fitting line of the lower edge and the fitting line of the right edge, 、 respectively represent the intercepts of the corresponding lines; The fitting line of the lower edge and the fitting line of the right edge The intersection point is the feature point, and the coordinates of the feature point are: , .

[0053] It should be noted that the reason for selecting the lower right corner of the flexible circuit board as the feature point in this embodiment is that the flexible circuit board in this embodiment is roughly L-shaped. When performing contour fitting on the flexible circuit board, multiple feature points on the edge line of the flexible circuit board need to be collected. The more feature points are collected, the better the fitting effect. And the lower edge line and the right edge line of the flexible circuit board in this embodiment can collect more feature points, and the linear fitting will be more accurate, which is beneficial to improving the accuracy of the coordinates of the feature points of the flexible circuit board and further improving the accuracy of subsequent missing material subsidies.

[0054] After calculating the key point coordinates of the flexible circuit board that needs to be subsidized, the flexible circuit board can be sucked by the suction head and mounted at the corresponding coordinate position. The movement of the suction head is realized by a motion control mechanism (such as a manipulator). It can be understood that the calculated key point coordinates are pixel coordinates, while the suction head movement is in the world coordinate system (i.e., physical coordinates). Before mounting, coordinate conversion is required.

[0055] In this embodiment, the coordinate conversion process includes: S31. Rotation center coordinate correction Based on the pre-calibrated double suction head parameters, the rotation center of the suction head is calculated in real time through the mapping relationship between the manipulator coordinate system and the camera coordinate system. The rotation center coordinates of the positioning points of suction head 1 / suction head 2 are: the x / y translation amount of the manipulator coordinates plus the pre-stored rotation reference point coordinates.

[0056] S32. Sub-pixel level coordinate space conversion The sub-pixel coordinates of the feature points of the flexible circuit board are converted into the physical coordinates in the manipulator world coordinate system through the affine transformation matrix generated by calibration, and the conversion relationship satisfies: , , 、 represents the pixel-physical size ratio factor.

[0057] S33. Compensation for the inherent error of the motion control mechanism Overlay the pre-stored fixed compensation values in the X / Y directions on the calculated physical coordinates to eliminate mechanical errors. The compensated coordinates are: , , , 、 represents the set compensation parameters.

[0058] In this embodiment, identifying whether there is a flexible circuit board on the suction head includes: matching the real-time image of the suction head with the second image template, and sending the matching result to the PLC as a status code. Status code 0X01: indicates that there is a flexible circuit board on the suction head; Status code 0X02: indicates that there is no flexible circuit board on the suction head or the identification fails. For example, taking the double suction head as an example, {0X01, 0X01} indicates that there is material on suction head 1 and there is material on suction head 2; {0X01, 0X02} indicates that there is material on suction head 1 and there is no material on suction head 2 or the identification fails; {0X02, 0X02} indicates that there is no material on suction head 1 or the identification fails and there is no material on suction head 2 or the identification fails; {0X02, 0X01} indicates that there is no material on suction head 1 or the identification fails and there is material on suction head 2.

[0059] In this embodiment, detecting the subsidized flexible circuit board includes: S41. Use the first image template to scan the flexible circuit board row by row after the replenishment and placement to locate the position areas of all flexible circuit boards.

[0060] S42. In the position area of the flexible circuit board, extract the feature point coordinates of the flexible circuit board ; for the left-column flexible circuit board, calculate the horizontal spacing between its feature point coordinates and the feature point coordinates of the adjacent flexible circuit board in the right column , and the vertical spacing between the feature points of the adjacent flexible circuit board in the upper row ; for the right-column flexible circuit board, calculate the horizontal spacing between its feature point coordinates and the feature point coordinates of the adjacent flexible circuit board in the left column , and the vertical spacing between the feature points of the adjacent flexible circuit board in the upper row ; If or the absolute value of the difference from the standard value ≤ 0.1 mm, it is determined that the spacing is qualified; If or If the absolute value of the difference from the standard value ≤ 0.1 mm, it is determined that the spacing is qualified.

[0061] S43. When both the horizontal spacing and the vertical spacing of the subsidized flexible circuit board are qualified, it is determined that the current flexible circuit board subsidy is qualified; otherwise, it is determined that the subsidy is unqualified.

[0062] When it is determined that the subsidy is unqualified, an NG signal is sent and recorded. The recorded content includes: the type of deviation (horizontal spacing or vertical spacing) and the deviation amount (unit: mm).

[0063] By improving the calculation method of the key point coordinates in the material shortage area in this embodiment, the accuracy of the material shortage position calculation and the detection work efficiency can be significantly improved. The advantages of this method compared with the existing methods are shown in Table 1.

[0064] Table 1

[0065] In summary, the detection method for the shortage and mounting of the flexible circuit board tape of the present invention has the following advantages: In terms of accuracy: Through the test effect of the present invention in an actual factory, the accuracy of the material shortage position calculation of the present invention reaches 99.3%. Compared with the traditional manual subsidy method and the general automatic recognition method of image processing in terms of accuracy, a huge improvement has been achieved.

[0066] Recognition efficiency: By recording the time consumed for image detection, the present invention can complete more than 1000 pieces of material shortage subsidies per hour, significantly improving the production efficiency. Compared with the traditional manual counting method, the present invention has achieved a significant improvement in both the recognition speed and the subsidy accuracy, fully reflecting the great advantages of the detection system in high-efficiency recognition and automated production.

[0067] The present invention improves problems such as material replenishment deviation and misalignment that are prone to occur in manual operations, forms an industrial-level solution integrating high-precision detection and rapid response, and significantly improves the yield stability and automation level of the FPC production line.

[0068] Taking the above ideal embodiments of the present invention as an inspiration, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A detection method for the missing component mounting of a flexible circuit board tape, characterized in that, It includes the following steps: S1. Obtain the first image template and the second image template of the flexible circuit board; S2. Use an area array camera to collect the real-time image of the tape, and identify whether there is a missing material area in the tape according to the real-time image; if it is identified that there is a missing material area in the tape, obtain the coordinate position of the missing material area; S3. Suck the flexible circuit board to be mounted by a suction head, use a flying shooting camera to collect the real-time image of the suction head, and identify whether there is a flexible circuit board on the suction head according to the real-time image. If it is identified that there is a flexible circuit board on the suction head, convert the coordinate position of the missing material area into the physical coordinates of the suction head movement, and the suction head driving mechanism mounts the flexible circuit board to the missing material area according to the physical coordinates; S4. Perform position detection on the flexible circuit board in the missing material area after mounting.

2. The detection method for missing material mounting of a flexible circuit board tape according to claim 1, characterized in that Step S2 specifically includes: S21. Create multiple rectangular frames capable of containing flexible circuit boards, where the coordinates of the upper left corner vertex of the rectangular frame are , and the coordinates of the lower right corner vertex are ; S22. Sequentially adjust the center coordinates of multiple said rectangular frames to the center position of the flexible circuit board in the first row of the real-time image of the tape; and after each adjustment, use the first image template to match the region of interest framed by the rectangular frame, and retain the rectangular frame with the highest matching degree as the detection frame; S23. Use the detection frame to detect the real-time image of the tape, and match the region framed by the detection frame with the first image template. If the match is successful, it is determined that there is a flexible circuit board in this region. If the match fails, it is determined that there is a missing material in this region, and this region is recorded as the missing material area; S24. Perform gray level feature analysis on the missing material area. If the gray level feature Gavg≥gray level threshold Tgray, it is determined that there is a foreign object in this missing material area, and feeding and mounting are prohibited; if the gray level feature Gavg < gray level threshold Tgray, it is determined that this missing material area can be fed and mounted.

3. The detection method for missing material mounting of a flexible circuit board tape according to claim 2, characterized in that The flexible circuit boards on the tape are arranged in two columns and multiple rows; In step S2, obtaining the coordinate position of the missing material area includes: S25. Feeding for the first row If the missing material area is in the first row and there are no flexible circuit boards in both columns of the first row of the real-time image of the tape, skip feeding for the first row; If the missing material area is in the first row and there is a flexible circuit board in one of the two columns of the first row of the real-time image of the tape, execute the feeding and mounting strategy for the first row; The feeding and mounting strategy for the first row includes: (i) When there is material in the left column of the first row and no material in the right column: Extract the characteristic point coordinates of the flexible circuit board in the left column , Based on the left edge line equation of the tape , where a, b, and c represent the equation coefficients, calculate the coordinates of the feature points The coordinates of the foot of the perpendicular from the point to the left edge line : ， ， Obtain the distance between the flexible circuit board in the right column and the left edge line according to the definition of the strip drawing , then the key point coordinates of the flexible circuit board to be replenished in the right column of the first row are : ， ； (ii) When there is material in the right column of the first row and no material in the left column, exchange the above left and right parameters and perform symmetric operations.

4. The detection method for missing material mounting of a flexible circuit board tape according to claim 3, characterized in that In step S2, obtaining the coordinate position of the missing material area further includes: S26. Feeding for non-first rows Extract the characteristic point coordinates of the flexible circuit board in the row above the material shortage area in the same column and the inclination angle of the edge line of the tape , and use the characteristic point coordinates to draw a perpendicular line from the characteristic point coordinates to the edge line of the tape . The coordinates of the foot of the perpendicular are . Obtain the angle of the perpendicular line and the distance between the upper and lower flexible circuit boards ; ; Calculate temporary coordinates : ， ； According to the temporary coordinates and the distance between the flexible circuit board in the column where the material shortage area is located and the edge line and the inclination angle of the vertical line , calculate the key point coordinates of the flexible circuit board to be replenished with materials : ， 。 5. The detection method for missing material mounting of a flexible circuit board tape according to claim 3 or 4, characterized in that Characteristic point coordinates of a flexible circuit board The calculation process includes: Define the lower right corner of the flexible circuit board as the feature point, equally spaced generate N scanning lines on the right edge and the lower edge of the flexible circuit board image respectively, and perform for each scanning line: (i) Gray level gradient calculation: , = 1 pixel, pixel gradient, indicating the pixel point of the pixel value; (ii)On each scan line, extract the points with the maximum gray gradient amplitude respectively to form the right edge point set and the lower edge point set. Extreme point extraction formula: Extreme point ; Perform weighted least squares linear fitting on the right edge point set and the lower edge point set respectively, with the weight being the gray gradient amplitude of the corresponding pixel points, to obtain two fitted lines: Fitting line for the lower edge of the flexible circuit board image : , Fitting a straight line to the right edge of the flexible circuit board image : , Among them, , respectively represent the slopes of the lower edge fitting line and the right edge fitting line, , respectively represent the intercepts of the corresponding lines; Lower edge fitting line The intersection point with the right edge fitting line is the feature point, and the coordinates of the feature point are: ， 。 6. The method for detecting the missing component mounting of a flexible circuit board tape according to claim 1, wherein: Obtaining the first image template includes: Using an area array camera to collect an image of a qualified tape, and framing the region of interest containing the flexible circuit board from the image; Using the Canny operator and the Sobel gradient operator to extract the edge information of the flexible circuit board from the region of interest, and retaining the contour features, position features, and angle features of the flexible circuit board; Training the template using the region of interest and its features, and using the qualified template as the first image template; that is, the first image template is the image template of the flexible circuit board in the qualified tape; Obtaining the second image template includes: Using a flying shot camera to collect an image after the suction head picks up the flexible circuit board, and framing the region of interest containing the flexible circuit board from the image; Using the Canny operator and the Sobel gradient operator to extract the edge information of the flexible circuit board from the region of interest, and retaining the contour features, position features, and angle features of the flexible circuit board; Training the template using the region of interest and its features, and using the qualified template as the second image template; that is, the second image template is the image template of the flexible circuit board picked up by the suction head.

7. The method for detecting the missing component mounting of a flexible circuit board tape according to claim 1, wherein: Identifying whether there is a flexible circuit board on the suction head includes: Matching the real-time image of the suction head using the second image template, and sending the matching result to the PLC in the form of a status code; Status code 0X01: indicating that there is a flexible circuit board on the suction head; Status code 0X02: indicating that there is no flexible circuit board on the suction head or the recognition fails.

8. The method for detecting the missing component mounting of a flexible circuit board tape according to claim 1, wherein: Step S4 specifically includes: S41. Using the first image template to perform line-by-line scanning on the flexible circuit board after replenishment and mounting, and locating the position areas of all flexible circuit boards; S42. Extract the coordinate of the feature points of the flexible circuit board within the position area of the flexible circuit board , For the flexible circuit board in the left column, calculate the horizontal spacing between the coordinates of its characteristic points and the coordinates of the characteristic points of the adjacent flexible circuit board in the right column , and the vertical spacing between the characteristic points of the flexible circuit board adjacent to the previous row ; For the flexible circuit board in the right column, calculate the horizontal spacing between the coordinates of its characteristic points and the coordinates of the characteristic points of the adjacent flexible circuit board in the left column , and the vertical spacing between the characteristic points of the flexible circuit board adjacent to the previous row ; If or the absolute value of the difference from the standard value ≤ 0.1 mm, it is determined that the spacing is qualified; If or the absolute value of the difference from the standard value ≤ 0.1 mm, it is determined that the spacing is qualified; S43. When both the horizontal spacing and the vertical spacing of the replenished flexible circuit board are qualified, it is determined that the current flexible circuit board replenishment is qualified; otherwise, it is determined that the replenishment is unqualified.

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