A method and system for adjusting the placement direction of an LED wafer

Abstract

The application provides an LED wafer placement direction adjusting method and system, the method comprising: acquiring a shooting image through a shooting device, correcting the shooting image to obtain a first image to be used; preprocessing the first image to be used to obtain a second image to be used, and acquiring a wafer contour map; acquiring a target center and a target radius of the wafer contour map, determining whether the placement direction of the wafer is correct through the target center, if the placement direction of the wafer is incorrect, acquiring an adjusting angle, and rotating a turntable based on the adjusting angle. Compared with the manual feeding mode, the application realizes full-automatic and accurate feeding, avoids the situation that the placement direction is incorrect due to human operation, improves the production efficiency, and can avoid the problem that the yield is reduced due to the incorrect placement direction.

Description

Technical Field

[0001] This invention relates to the field of LED fabrication technology, and in particular to a method and system for adjusting the placement orientation of LED wafers. Background Technology

[0002] The red vertical structure LED wafer carries several arrayed chips. The chips are square in shape. When the wafer is rotated 90° in four directions, the shape characteristics of the chips distributed on it are consistent.

[0003] During the wafer manufacturing process, a flat edge notch is usually made on the wafer. During manual loading, the wafer placement orientation is adjusted by confirming the position of the flat edge notch, thereby ensuring that the die placement orientation is correct.

[0004] However, even with flat-edge cuts on the wafers, human error can still lead to incorrect wafer loading direction during manual loading, resulting in incorrect die placement and subsequent production abnormalities. This severely impacts product yield and production efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method and system for adjusting the placement orientation of LED wafers. This method addresses the technical problem that existing wafer preparation methods, which rely on manual feeding, are prone to errors in wafer feeding orientation due to human error. These errors lead to incorrect die placement orientation, resulting in abnormal production in subsequent processes and severely impacting product yield and production efficiency.

[0006] To achieve the above objectives, in a first aspect, embodiments of this application provide a method for adjusting the placement orientation of an LED wafer, comprising the following steps:

[0007] When a wafer with a flat-edge notch is placed on a turntable, an image is captured by an imaging device, and the captured image is corrected to obtain a first image to be used.

[0008] The first image to be used is preprocessed to obtain a second image to be used, and a wafer outline map is obtained from the second image to be used.

[0009] The turntable is rotated at a preset angle, and the minimum distance between the wafer profile and the center point of the turntable is detected to obtain the acquisition distance corresponding to the preset angle. The target center and target radius of the wafer profile are determined by the preset angle and the acquisition distance.

[0010] The correct placement orientation of the wafer is determined by the target center. If the wafer is placed in the wrong orientation, the outline points of the wafer outline map are obtained. An adjustment angle is determined by the outline points and the target radius. The turntable is rotated based on the adjustment angle to make the wafer placed in the correct orientation.

[0011] Furthermore, the step of correcting the captured image to obtain a first usable image includes:

[0012] An optical center coordinate system is constructed in the captured image, and the coordinates of the optical center origin are obtained. Based on the optical center origin coordinates, the pixel coordinates of each pixel in the captured image are normalized to the optical center pixel coordinates, and the Euclidean distance between the optical center pixel coordinates and the optical center origin coordinates is obtained.

[0013] Obtain the first radial distortion coefficient, the second radial distortion coefficient, the third radial distortion coefficient, the first tangential distortion coefficient, and the second tangential distortion coefficient corresponding to the imaging device;

[0014] Radial distortion correction is performed on the captured image using the Euclidean distance, the first radial distortion coefficient, the second radial distortion coefficient, and the third radial distortion coefficient to obtain a staged image;

[0015] The stage image is tangentially distorted using the Euclidean distance, the first tangential distortion coefficient, and the second tangential distortion coefficient to obtain a first image to be used.

[0016] Furthermore, the formula for obtaining the stage image is:

[0017] ,

[0018] in, , Let x and y represent the radial correction coordinates of the i-th pixel, respectively. , , These represent the first radial distortion coefficient, the second radial distortion coefficient, and the third radial distortion coefficient, respectively. Represents Euclidean distance. , Let x and y represent the x and y coordinates of the optical center pixel coordinates of the i-th pixel, respectively.

[0019] The formula for obtaining the first image to be used is:

[0020] ,

[0021] in, , Let x and y represent the x and y coordinates of the tangential correction coordinates of the i-th pixel, respectively. , These represent the first tangential distortion coefficient and the second tangential distortion coefficient, respectively.

[0022] Furthermore, the preprocessing includes noise suppression processing and gradient amplitude enhancement processing.

[0023] Furthermore, the step of determining the target center and target radius of the wafer contour map using the preset angle and the acquisition distance includes:

[0024] The Cartesian coordinates are obtained based on the preset angle and the acquisition distance.

[0025] An error function is constructed using the Cartesian coordinates, and the sum of squares of the error function is minimized to obtain the target circle center and target radius.

[0026] Furthermore, the expression for the error function is:

[0027] ,

[0028] in, This represents the error function relative to the i-th Cartesian coordinate point. , Let x and y represent the x and y coordinates of the i-th Cartesian coordinate point, respectively. , , Both represent intermediate variables, where, , , ,in, , Let x and y represent the x-coordinate and y-coordinate of the target circle's center, respectively. Indicates the target radius.

[0029] Furthermore, the step of determining whether the wafer's placement orientation is correct through the target center includes:

[0030] Construct mutually perpendicular horizontal and vertical lines based on the target circle center;

[0031] The wafer outline is divided into a left image and a right image by the vertical line, and the left area and right area of ​​the left image and the right image are obtained respectively.

[0032] The left area is compared with the right area. If the left area is not equal to the right area, the wafer is determined to be placed in the wrong orientation.

[0033] Furthermore, after the step of comparing the left area with the right area, and determining that the wafer's orientation is incorrect if the left area is not equal to the right area, the method further includes:

[0034] If the area of ​​the left part is equal to the area of ​​the right part, the wafer outline is divided into an upper image and a lower image by the horizontal line, and the upper area and lower area of ​​the upper image and the lower image are obtained respectively.

[0035] The upper area is compared with the lower area. If the upper area is smaller than the lower area, the wafer is determined to be placed in the wrong orientation.

[0036] Furthermore, the step of determining the adjustment angle using the contour points and the target radius includes:

[0037] Obtain the line connecting the center of the target circle to each of the contour points, and compare the line with the target radius to select several lines to be used from the several lines;

[0038] From a plurality of lines to be used, the line with the shortest length is selected as the baseline;

[0039] Starting from the center of the target circle, construct a target line in a vertically downward direction, and select the angle between the baseline and the target line as the adjustment angle.

[0040] Secondly, embodiments of this application provide an LED wafer placement orientation adjustment system, applied to the LED wafer placement orientation adjustment method described in the first aspect above, the system comprising:

[0041] The acquisition module is used to acquire an image through an imaging device when a wafer with a flat edge cut is placed on a turntable, and to perform correction processing on the captured image to obtain a first image to be used.

[0042] The first verification module is used to preprocess the first image to be used to obtain a second image to be used, and to obtain a wafer outline map from the second image to be used.

[0043] The second verification module is used to rotate the turntable at a preset angle and detect the minimum distance between the wafer profile and the center point of the turntable to obtain the acquisition distance corresponding to the preset angle, and determine the target center and target radius of the wafer profile through the preset angle and the acquisition distance.

[0044] The adjustment module is used to determine whether the wafer is placed in the correct orientation by means of the target center. If the wafer is placed in the wrong orientation, the module obtains the outline points of the wafer outline map, determines the adjustment angle by means of the outline points and the target radius, and rotates the turntable based on the adjustment angle to make the wafer placed in the correct orientation.

[0045] Thirdly, embodiments of this application provide a computer, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the LED wafer placement orientation adjustment method as described in the first aspect above.

[0046] Fourthly, embodiments of this application provide a storage medium storing a computer program thereon, which, when executed by a processor, implements the LED wafer placement orientation adjustment method as described in the first aspect above.

[0047] Compared with the prior art, the beneficial effects of the present invention are as follows: by correcting the captured image, image distortion caused by lens distortion is avoided, ensuring the consistency between the placement direction represented by the subsequent wafer outline map and the actual wafer placement direction; by dividing the wafer outline map into left-right and up-down directions using the structural features of a wafer including a flat-edge notch, the correctness of the placement direction can be quickly and automatically determined, and the adjustment angle can be automatically obtained by the relationship between the current position of the flat-edge notch and the position of the flat-edge notch when the wafer is correctly placed, thus completing the alignment work. Compared with manual loading, this invention achieves fully automated and accurate loading, avoids placement direction errors caused by human operation, improves production efficiency, and avoids the problem of yield reduction caused by incorrect placement direction. Attached Figure Description

[0048] Figure 1 This is a flowchart of the LED wafer placement orientation adjustment method in the first embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the structure when the LED wafer placement orientation is correct in the LED wafer placement orientation adjustment method of the first embodiment of the present invention;

[0050] Figure 3 This is a structural block diagram of the LED wafer placement orientation adjustment system in the second embodiment of the present invention;

[0051] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0052] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0053] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected" to another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0054] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0055] Please see Figure 1 and Figure 2 The LED wafer placement orientation adjustment method provided in the first embodiment of the present invention includes the following steps:

[0056] S10: When a wafer with a flat edge cut is placed on a turntable, an image is captured by an imaging device, and the captured image is corrected to obtain a first image to be used.

[0057] In this embodiment, the imaging device is an industrial camera, and step S10 includes:

[0058] S110: Construct an optical center coordinate system in the captured image and obtain the optical center origin coordinates. Based on the optical center origin coordinates, normalize the pixel coordinates of each pixel in the captured image to optical center pixel coordinates, and obtain the Euclidean distance between the optical center pixel coordinates and the optical center origin coordinates.

[0059] The coordinates of the optical center origin are the coordinates of the geometric center point of the imaging plane. In this embodiment, the coordinates of the optical center origin are (0,0), and the formula for obtaining the optical center pixel coordinates is:

[0060] ,

[0061] in, , Let x and y represent the x and y coordinates of the optical center pixel coordinates of the i-th pixel, respectively. , Let x and y represent the x and y coordinates of the i-th pixel, respectively. , Let x and y represent the x and y coordinates of the origin of the optical center, respectively. , These represent the pixel quantization in the x and y directions, respectively. By normalizing the pixel coordinates to the optical center pixel coordinates, the influence of hardware installation errors can be eliminated, ensuring the accurate acquisition of subsequent wafer contour maps.

[0062] The formula for obtaining the Euclidean distance is:

[0063] ,

[0064] in, This indicates Euclidean distance.

[0065] S120: Obtain the first radial distortion coefficient, the second radial distortion coefficient, the third radial distortion coefficient, the first tangential distortion coefficient, and the second tangential distortion coefficient corresponding to the imaging device;

[0066] It should be noted that the first radial distortion coefficient, the second radial distortion coefficient, the third radial distortion coefficient, the first tangential distortion coefficient, and the second tangential distortion coefficient can all be obtained by camera calibration fitting of an industrial camera. Specifically, the industrial camera is used to capture images of the chessboard from multiple angles, and the coordinates of the captured corner points are extracted. Based on the physical dimensions of the chessboard, standard corner point coordinates without distortion are defined. A fitting equation is constructed based on the captured corner point coordinates and the standard corner point coordinates. After iterative optimization using the least squares method, the first radial distortion coefficient, the second radial distortion coefficient, the third radial distortion coefficient, the first tangential distortion coefficient, and the second tangential distortion coefficient can be obtained.

[0067] S130: Radial distortion correction is performed on the captured image using the Euclidean distance, the first radial distortion coefficient, the second radial distortion coefficient, and the third radial distortion coefficient to obtain a stage image;

[0068] The formula for obtaining the stage image is:

[0069] ,

[0070] in, , Let x and y represent the radial correction coordinates of the i-th pixel, respectively. , , These represent the first radial distortion coefficient, the second radial distortion coefficient, and the third radial distortion coefficient, respectively. Represents Euclidean distance. , Let x and y represent the x and y coordinates of the optical center pixel coordinates of the i-th pixel, respectively.

[0071] S140: Perform tangential distortion correction on the stage image using the Euclidean distance, the first tangential distortion coefficient, and the second tangential distortion coefficient to obtain a first candidate image;

[0072] The formula for obtaining the first image to be used is:

[0073] ,

[0074] in, , Let x and y represent the x and y coordinates of the tangential correction coordinates of the i-th pixel, respectively. , These represent the first tangential distortion coefficient and the second tangential distortion coefficient, respectively.

[0075] S20: Preprocess the first image to be used to obtain a second image to be used, and obtain a wafer outline map from the second image to be used;

[0076] The preprocessing includes noise suppression and gradient magnitude enhancement. In this embodiment, noise suppression is performed using an adaptive bilateral filter. The noise suppression and gradient magnitude enhancement improve the contrast between the contour and the background, ensuring the accuracy of the extracted wafer contour image. Furthermore, the wafer contour image is obtained using the Canny edge detection algorithm. These noise suppression, gradient magnitude enhancement, and edge detection algorithms are commonly used in image processing and will not be elaborated upon here.

[0077] S30: Rotate the turntable at a preset angle and detect the minimum distance between the wafer profile and the center point of the turntable to obtain the acquisition distance corresponding to the preset angle. Determine the target center and target radius of the wafer profile through the preset angle and the acquisition distance.

[0078] In this embodiment, an optical sensor is positioned at the center point of the turntable. The optical sensor's position is fixed and does not change with the turntable's rotation. When the turntable rotates, a region of the wafer enters the sensor's acquisition range. After acquiring several edge distances, the smallest edge distance is selected as the acquisition distance. Each preset angle corresponds to a specific acquisition distance. It should be noted that after acquiring the acquisition distances, a distance threshold is constructed based on these distances. The acquisition distances are compared with the distance threshold to eliminate those exceeding the threshold range. This method avoids fitting errors caused by noise and edge points corresponding to flat edges, ensuring accurate acquisition of the target center and radius. In this embodiment, the distance threshold can be determined using the IQR method.

[0079] S30 includes:

[0080] S310: Obtain Cartesian coordinates based on the preset angle and the acquisition distance;

[0081] The product of the cosine value of the preset angle and the acquisition distance is the x-coordinate of the Cartesian coordinate point, and the product of the sinine value of the preset angle and the acquisition distance is the y-coordinate of the Cartesian coordinate point. It can be understood that several preset angles and acquisition distances constitute several Cartesian coordinate points.

[0082] S320: Construct an error function using the Cartesian coordinate points, and minimize the sum of squares of the error function to obtain the target circle center and target radius;

[0083] The expression for the error function is:

[0084] ,

[0085] in, This represents the error function relative to the i-th Cartesian coordinate point. , Let x and y represent the x and y coordinates of the i-th Cartesian coordinate point, respectively. , , Both represent intermediate variables, where, , , ,in, , Let x and y represent the x-coordinate and y-coordinate of the target circle's center, respectively. Indicates the target radius;

[0086] The expression for minimization optimization is:

[0087] ,

[0088] in, This indicates minimizing the search for the optimal solution. This represents the total number of Cartesian coordinate points. The specific process essentially involves solving a system of linear equations. By taking the partial derivatives separately and setting them to zero, we can obtain information about... , , The system of linear equations is then solved using matrix operations or algebraic operations. , , This allows for the automatic determination of the wafer's center point and its radius, without the need for pre-setting calibration dimensions, thus accommodating orientation adjustments for wafers of different sizes.

[0089] S40: Determine whether the placement direction of the wafer is correct by using the target center. If the placement direction of the wafer is incorrect, obtain the outline points of the wafer outline map, determine the adjustment angle by using the outline points and the target radius, and rotate the turntable based on the adjustment angle to make the placement direction of the wafer correct.

[0090] S40 includes:

[0091] S410: Construct mutually perpendicular horizontal and vertical lines based on the target circle center;

[0092] S420: Divide the wafer outline into a left image and a right image using the vertical line, and obtain the left area and right area of ​​the left image and the right image respectively;

[0093] S430: Compare the left area with the right area. If the left area is not equal to the right area, determine that the wafer is placed in the wrong orientation.

[0094] When the wafer is correctly oriented, the horizontal cut is directly below and parallel to the horizontal line. Based on this characteristic, after the wafer outline is divided along the vertical line, the left image must be symmetrical to the right image. Therefore, when the area of ​​the left part is not equal to the area of ​​the right part, there must be an incorrect orientation. Even when the area of ​​the left part is equal to the area of ​​the right part, there is still a situation where the horizontal cut is directly above and parallel to the horizontal line. In this case, the wafer orientation is still incorrect. To identify this situation, step S40 further includes:

[0095] S440: If the area of ​​the left part is equal to the area of ​​the right part, the wafer outline is divided into an upper image and a lower image by the horizontal line, and the upper area and lower area of ​​the upper image and the lower image are obtained respectively.

[0096] S450: Compare the upper area with the lower area. If the upper area is smaller than the lower area, determine that the wafer is placed in the wrong orientation.

[0097] S460: Obtain the line connecting the center of the target circle to each of the contour points, and compare the line with the target radius to select a number of lines to be used from the number of lines;

[0098] By comparing the connecting line with the target radius, the arc contour points of the wafer can be quickly screened out, simplifying subsequent comparisons and improving adjustment efficiency.

[0099] S470: Select the line with the shortest length from among the plurality of lines to be used as the baseline;

[0100] S480: Starting from the center of the target circle, construct a target line in a vertically downward direction, and select the angle between the baseline and the target line as the adjustment angle.

[0101] Since the vertical line covers the entire wafer outline, if the angle is directly determined by adjusting the reference line and the vertical line, there are two included angles. In order to clarify the adjustment direction, the target line is reconstructed, thereby completing the adjustment of the overall placement direction.

[0102] By correcting the captured images, image distortion caused by lens distortion is avoided, ensuring the consistency between the placement orientation represented by the subsequent wafer outline map and the actual wafer placement orientation. Using the structural features of a wafer including a flat-edge notch, the wafer outline map is divided into left-right and up-down directions to quickly and automatically determine the correctness of the placement orientation. Furthermore, by comparing the current position of the flat-edge notch with the position when the wafer is correctly placed, the adjustment angle is automatically obtained to complete the alignment process. Compared to manual loading, this method achieves fully automated and accurate loading, avoiding placement orientation errors caused by human operation, improving production efficiency, and preventing yield reduction due to incorrect placement orientation.

[0103] Please see Figure 3The second embodiment of the present invention provides an LED wafer placement orientation adjustment system, which is applied to the LED wafer placement orientation adjustment method described in the above embodiments, and will not be repeated hereafter. As used below, the terms "module," "unit," "subunit," etc., can refer to a combination of software and / or hardware that performs a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0104] The system includes:

[0105] The acquisition module 10 is used to acquire an image through an imaging device when a wafer with a flat edge notch is placed on a turntable, and to perform correction processing on the image to obtain a first image to be used.

[0106] The acquisition module 10 includes:

[0107] The first unit is used to construct an optical center coordinate system in the captured image and obtain the optical center origin coordinates. Based on the optical center origin coordinates, the pixel coordinates of each pixel in the captured image are normalized to the optical center pixel coordinates, and the Euclidean distance between the optical center pixel coordinates and the optical center origin coordinates is obtained.

[0108] The second unit is used to acquire the first radial distortion coefficient, the second radial distortion coefficient, the third radial distortion coefficient, the first tangential distortion coefficient, and the second tangential distortion coefficient corresponding to the shooting device;

[0109] The third unit is used to perform radial distortion correction on the captured image using the Euclidean distance, the first radial distortion coefficient, the second radial distortion coefficient, and the third radial distortion coefficient to obtain a stage image;

[0110] The fourth unit is used to perform tangential distortion correction on the stage image using the Euclidean distance, the first tangential distortion coefficient, and the second tangential distortion coefficient to obtain a first image to be used.

[0111] The first verification module 20 is used to preprocess the first candidate image to obtain a second candidate image, and to obtain a wafer outline map from the second candidate image.

[0112] The second verification module 30 is used to rotate the turntable at a preset angle and detect the minimum distance between the wafer profile and the center point of the turntable to obtain the acquisition distance corresponding to the preset angle, and determine the target center and target radius of the wafer profile through the preset angle and the acquisition distance.

[0113] The second verification module 30 includes:

[0114] The fifth unit is used to obtain Cartesian coordinate points based on the preset angle and the acquisition distance;

[0115] The sixth unit is used to construct an error function using the Cartesian coordinate points, and to minimize the sum of squares of the error function to obtain the target circle center and target radius.

[0116] The adjustment module 40 is used to determine whether the placement direction of the wafer is correct through the target center. If the placement direction of the wafer is incorrect, the module obtains the outline points of the wafer outline map, determines the adjustment angle through the outline points and the target radius, and rotates the turntable based on the adjustment angle to make the placement direction of the wafer correct.

[0117] The adjustment module 40 includes:

[0118] The seventh unit is used to construct mutually perpendicular horizontal and vertical lines based on the center of the target circle;

[0119] The eighth unit is used to divide the wafer outline into a left image and a right image by the vertical line, and to obtain the left area and right area of ​​the left image and the right image respectively.

[0120] The ninth unit is used to compare the left area with the right area. If the left area is not equal to the right area, it is determined that the wafer is placed in the wrong orientation.

[0121] The tenth unit is used to divide the final wafer outline into an upper image and a lower image by the horizontal line if the left area is equal to the right area, and to obtain the upper area and lower area of ​​the upper image and the lower image respectively.

[0122] The eleventh unit is used to compare the upper area with the lower area. If the upper area is smaller than the lower area, it is determined that the wafer is placed in the wrong orientation.

[0123] The twelfth unit is used to obtain the line connecting the center of the target circle and each of the contour points, and compare the line with the target radius to select a number of lines to be used from the number of lines.

[0124] The thirteenth unit is used to select the shortest line from a plurality of lines to be used as the baseline.

[0125] The fourteenth unit is used to construct a target line in a vertically downward direction, starting from the center of the target circle, and to select the angle between the baseline and the target line as the adjustment angle.

[0126] The present invention also provides a computer, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the LED wafer placement orientation adjustment method as described in the above technical solutions.

[0127] The present invention also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the LED wafer placement orientation adjustment method as described in the above technical solution.

[0128] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0129] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for adjusting the placement orientation of an LED wafer, characterized in that, The method comprises the following steps: When the wafer provided with the flat edge cut is placed on the turntable, a shooting image is obtained by a shooting device, and a correction process is performed on the shooting image to obtain a first standby image; A pre-processing is performed on the first standby image to obtain a second standby image, and a wafer contour map is obtained from the second standby image; The turntable is rotated at a preset angle, and the minimum distance between the wafer contour map and the center point of the turntable is detected to obtain a collection distance corresponding to the preset angle, and a target center and a target radius of the wafer contour map are determined by the preset angle and the collection distance; Whether the placement direction of the wafer is correct is determined by the target center, and if the placement direction of the wafer is incorrect, a contour point of the wafer contour map is obtained, an adjustment angle is determined by the contour point and the target radius, the turntable is rotated based on the adjustment angle, so that the placement direction of the wafer is correct; The step of determining whether the placement direction of the wafer is correct by the target center comprises: A horizontal line and a vertical line perpendicular to each other are constructed based on the target center; The wafer contour map is divided into a left image and a right image by the vertical line, and the left area and the right area of the left image and the right image are obtained respectively; The left area and the right area are compared, and if the left area is not equal to the right area, it is determined that the placement direction of the wafer is incorrect; If the left area is equal to the right area, the wafer contour map is divided into an upper image and a lower image by the horizontal line, and the upper area and the lower area of the upper image and the lower image are obtained respectively; The upper area and the lower area are compared, and if the upper area is less than the lower area, it is determined that the placement direction of the wafer is incorrect.

2. The LED wafer placement direction adjustment method according to claim 1, wherein The step of performing correction processing on the shooting image to obtain a first standby image comprises: A principal point coordinate system is constructed in the shooting image, and a principal point origin coordinate is obtained, the pixel coordinates of each pixel point in the shooting image are normalized to principal point pixel coordinates based on the principal point origin coordinate, and the Euclidean distance between the principal point pixel coordinates and the principal point origin coordinate is obtained; A first radial distortion coefficient, a second radial distortion coefficient, a third radial distortion coefficient, a first tangential distortion coefficient and a second tangential distortion coefficient corresponding to the shooting device are obtained; The shooting image is corrected in radial distortion by the Euclidean distance, the first radial distortion coefficient, the second radial distortion coefficient and the third radial distortion coefficient to obtain a stage image; The stage image is corrected in tangential distortion by the Euclidean distance, the first tangential distortion coefficient and the second tangential distortion coefficient to obtain a first standby image.

3. The LED wafer placement direction adjustment method according to claim 2, wherein The formula for obtaining the stage image is: ， in, , Let x and y represent the radial correction coordinates of the i-th pixel, respectively. , , These represent the first radial distortion coefficient, the second radial distortion coefficient, and the third radial distortion coefficient, respectively. Represents Euclidean distance. , Let x and y represent the x and y coordinates of the optical center pixel coordinates of the i-th pixel, respectively. The formula for obtaining the first standby image is: ， wherein, , respectively represent the horizontal coordinate and the vertical coordinate of the tangential correction coordinate of the i-th pixel point, , respectively represent the first tangential distortion coefficient and the second tangential distortion coefficient.

4. The LED wafer placement direction adjustment method according to claim 1, wherein The pre-processing comprises noise suppression processing and gradient amplitude enhancement processing.

5. The LED wafer placement direction adjustment method according to claim 1, wherein The step of determining the target center and the target radius of the wafer contour map by the preset angle and the collection distance comprises: acquire a Cartesian coordinate point based on the preset angle and the acquisition distance; construct an error function based on the Cartesian coordinate point, and minimize and optimize a sum of squares of the error function to acquire a target circle center and a target radius.

6. The LED wafer placement direction adjustment method according to claim 5, wherein An expression of the error function is: ， wherein denotes the error function for the i-th Cartesian coordinate point, , denote the horizontal and vertical coordinate of the i-th Cartesian coordinate point, respectively, , , all denote intermediate variables, wherein , , wherein , denote the horizontal and vertical coordinate of the target circle center, respectively, denotes the target radius.

7. The LED wafer placement direction adjustment method of claim 1, wherein The step of determining the adjustment angle based on the contour points and the target radius comprises: acquire a line between the target circle center and each contour point, and compare the line with the target radius to select a plurality of standby lines from the lines; select a standby line with the smallest length as a reference line from the standby lines; select an angle between the reference line and a target line as the adjustment angle, where the target line is constructed in a vertical downward direction from the target circle center.

8. An LED wafer placement direction adjustment system applied to the LED wafer placement direction adjustment method according to any one of claims 1 to 7, characterized in that, The system comprises: An acquisition module is configured to acquire a photographed image by a photographing device when a wafer with a flat edge cut is placed on a turntable, correct the photographed image, and acquire a first standby image. A first verification module is configured to preprocess the first standby image to acquire a second standby image, and acquire a wafer contour from the second standby image. A second verification module is configured to rotate the turntable at a preset angle, detect a minimum distance between the wafer contour and a center point of the turntable, acquire an acquisition distance corresponding to the preset angle, and determine a target circle center and a target radius of the wafer contour based on the preset angle and the acquisition distance. An adjustment module is configured to determine whether a placement direction of the wafer is correct based on the target circle center, acquire contour points of the wafer contour if the placement direction of the wafer is incorrect, determine an adjustment angle based on the contour points and the target radius, and rotate the turntable based on the adjustment angle to make the placement direction of the wafer correct.

Images