CN113866171B - Circuit board dispensing detection method and device and computer readable storage medium - Google Patents
Circuit board dispensing detection method and device and computer readable storage medium Download PDFInfo
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- CN113866171B CN113866171B CN202111457033.5A CN202111457033A CN113866171B CN 113866171 B CN113866171 B CN 113866171B CN 202111457033 A CN202111457033 A CN 202111457033A CN 113866171 B CN113866171 B CN 113866171B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B5/00—Measuring arrangements characterised by the use of mechanical techniques
- G01B5/28—Measuring arrangements characterised by the use of mechanical techniques for measuring roughness or irregularity of surfaces
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T7/00—Image analysis
- G06T7/50—Depth or shape recovery
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2200/00—Indexing scheme for image data processing or generation, in general
- G06T2200/08—Indexing scheme for image data processing or generation, in general involving all processing steps from image acquisition to 3D model generation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/10—Image acquisition modality
- G06T2207/10028—Range image; Depth image; 3D point clouds
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2207/00—Indexing scheme for image analysis or image enhancement
- G06T2207/30—Subject of image; Context of image processing
- G06T2207/30108—Industrial image inspection
- G06T2207/30141—Printed circuit board [PCB]
Abstract
The invention provides a method and a device for detecting circuit board dispensing and a computer readable storage medium, wherein the method comprises the following steps: luminous powder is added in advance in glue used for dispensing the circuit board; after the glue is dispensed, acquiring an image of the circuit board by using a 2D camera in a dark light environment, and thresholding the image of the circuit board; removing the 2D camera, and arranging a thimble mechanism consisting of a plurality of thimbles which can move up and down; setting a light source and a 3D camera, and acquiring a 3D point cloud image through the 3D camera; performing three-dimensional modeling on the 3D point cloud image of the upper end surface of the thimble; creating a 2D gray scale grid map; and comparing and analyzing the 2D gray-scale grid map and the 2D gray-scale grid map of the reference surface. The method, the equipment and the computer readable storage medium solve the problem that the glue dispensing detection method in the prior art can not accurately identify the defects of more glue, less glue, glue leakage or residual glue and the like in the glue dispensing of the circuit board.
Description
Technical Field
The invention relates to the technical field of detection methods for circuit board production, in particular to a method and equipment for detecting circuit board dispensing and a computer readable storage medium.
Background
The circuit board is subjected to glue dispensing processing by using a glue dispenser and is mainly used for water resistance, dust resistance and corrosion resistance. Nowadays, many enterprises put forward higher level requirements on usability and stability of electronic products, and the dispensing processing of circuit boards has become an essential process. The long-term effective protection is well carried out on the sensitive circuit boards of some electronic equipment and some electronic components, which is an important means for ensuring the normal and stable work of the electronic equipment, the waterproof glue used for dispensing and processing the circuit boards has stable dielectric insulation, which is an effective measure for preventing environmental pollution, and simultaneously, the stress generated by impact and vibration can be counteracted within a certain temperature range and humidity range.
The Chinese invention application with the publication number of 2018-07-10, the publication number of CN108267431A and the application number of CN201611263598.9 discloses a circuit board dispensing detection device and a detection method, the detection method controls a preset light source to irradiate a circuit board through an irradiation module, an image of the circuit board is shot through a shooting unit, and the image of the circuit board shot by the shooting unit is compared and analyzed with a corresponding standard circuit board image through a comparison module; and determining whether the circuit board passes the detection or not by the determination module according to the comparison analysis result of the comparison module. However, the adoption of the detection method for dispensing detection of the circuit board has the following disadvantages: because the surface of the dispensing area of the circuit board is mostly an uneven curved surface, when the circuit board is shot by the camera shooting unit, due to diffuse reflection and the like, a large amount of noise exists in the shot circuit board image, and the detection precision is affected; and because the glue used for dispensing the circuit board has the characteristic of high transparency, when the shot image is contrasted and analyzed, the defects on the surface of the transparent adhesive film cannot be accurately identified, and the electronic components covered by the transparent adhesive film often interfere with the contrasted and analyzed image, so that the defects of excessive glue, less glue, glue leakage or residual glue and the like existing in the dispensing of the circuit board cannot be accurately identified.
Disclosure of Invention
The invention provides a method for detecting circuit board dispensing, which solves the problems that the detection precision of the dispensing detection method in the prior art is poor, and the defects of excessive glue, little glue, glue leakage or residual glue and the like in the circuit board dispensing can not be accurately identified.
The technical scheme of the invention is realized as follows:
a method for detecting the dispensing of a circuit board comprises the following steps:
step 1: before the circuit board dispensing, noctilucent powder is added in advance in glue used for the circuit board dispensing;
step 2: after dispensing, acquiring an image of the circuit board by using a 2D camera in a dark light environment, thresholding the image of the circuit board, identifying a highlight area in the thresholded image, extracting contour points of the highlight area, forming the edge of a dispensing area by all the contour points, comparing and analyzing the edge with an image of a standard dispensing circuit board, obtaining a conclusion of residual glue defects if the edge of the dispensing area does not exist on the image of the standard dispensing circuit board, and otherwise, obtaining a conclusion that the residual glue defects do not exist;
and step 3: removing the 2D camera, arranging a thimble mechanism consisting of a plurality of thimbles capable of moving up and down, moving the thimble mechanism from top to bottom to enable the lower end parts of the thimbles to be in contact with the upper surface of the circuit board glue dispensing area, and continuously moving the thimble mechanism downwards after the lower end parts of the thimbles are in contact with the upper surface of the circuit board glue dispensing area to enable the thimbles to form different height distributions according to the concave-convex fluctuation condition of the upper surface of the circuit board glue dispensing area, so that the concave-convex fluctuation condition of the upper surface of the circuit board glue dispensing area is simulated through the upper end parts of the thimbles;
and 4, step 4: arranging a light source and a 3D camera, enabling the view finding direction of a lens of the 3D camera to face the upper end part of the thimble, acquiring a 3D point cloud image through the 3D camera, carrying out detection area positioning on the acquired 3D point cloud image and cutting the acquired 3D point cloud image to obtain a 3D point cloud image of the upper end surface of the thimble;
and 5: carrying out three-dimensional modeling on the 3D point cloud image of the upper end surface of the thimble to obtain a three-dimensional image model consisting of the upper end surfaces of a plurality of thimbles, establishing a reference surface in the three-dimensional image model, wherein the normal height of the reference surface is the height of the upper surface of the thimble when the thimble is in pressure contact with a standard dispensing area of a circuit board, and respectively calculating the normal height difference between the upper end surface of the thimble obtained by modeling and the reference surface;
step 6: creating a 2D gray grid graph, wherein each grid of the 2D gray grid graph corresponds to the upper end surface of each thimble in the three-dimensional image model respectively, determining the gray value of each grid according to the normal height difference between the upper end surface of each thimble in the three-dimensional image model and a reference surface, and generating the 2D gray grid graph of the upper end surface of each thimble;
and 7: and (3) comparing and analyzing the 2D gray grid graph of the upper end surface of the thimble generated in the step (6) with the 2D gray grid graph of the reference surface to obtain a dispensing quality conclusion of the circuit board dispensing area, if the gray value of a certain grid is lower than that of the grid of the reference surface, indicating that the circuit board dispensing area corresponding to the upper end surface of the thimble has less glue or glue leakage, and if the gray value of the certain grid is higher than that of the grid of the reference surface, indicating that the circuit board dispensing area corresponding to the upper end surface of the thimble has more glue.
Further, in the step 5, three-dimensional modeling of the 3D point cloud image of the upper end surface of the tip includes the steps of: and fitting a reference plane in the 3D point cloud image of the cut upper end surface of the thimble, calculating a normal vector of the reference plane, taking the normal vector direction as a Z-axis direction, taking two mutually perpendicular directions on the reference plane as X, Y axes, establishing a 3D point cloud coordinate system, calculating coordinates of all point clouds in the 3D point cloud image of the cut upper end surface of the thimble in the 3D coordinate system, and generating a three-dimensional image of the upper end surfaces of the thimble.
Further, in the step 2, the thresholded circuit board image is vertically projected on an x/y plane, 2D features are extracted from the vertically projected image, the 2D features include an average gray value and a high brightness percentage, and a high brightness region in the thresholded image is identified according to the average gray value and the high brightness percentage.
Further, in the step 4, the cropping the acquired 3D point cloud image includes the following steps: extracting 3D features from the obtained 3D point cloud image, classifying the 3D point cloud image area of the upper end surface of the thimble and the 3D point cloud image area of the background according to the extracted 3D features, cutting the 3D point cloud image area of the background according to a classification result, and obtaining the 3D point cloud image of the upper end surface of the thimble.
Furthermore, the thimble mechanism still includes base and spring be equipped with the guiding hole on the base, be equipped with the guide pillar on the thimble, the guide pillar activity is worn to establish in the guiding hole of base, the spring suit is in the guide pillar outside, and one end of spring and the step face butt of guide pillar lower extreme and thimble combination department, another tip of spring and the lower surface butt of base.
Further, in the step 7, traversing each grid of the 2D gray scale grid pattern of the upper end surface of the thimble, comparing an image of each grid with a grid image of a corresponding position of the 2D gray scale grid pattern of the reference surface, if the gray value of the grid is lower than that of the grid of the reference surface, marking less glue or leaking glue on the grid of the 2D gray scale grid pattern of the upper end surface of the thimble, and if the gray value of the grid is higher than that of the grid of the reference surface, marking more glue on the grid of the 2D gray scale grid pattern of the upper end surface of the thimble.
Further, the number of grids marked with glue shortage or glue leakage in the 2D gray scale grid diagram of the upper end face of the thimble is counted, the area of the glue shortage or glue leakage area on the circuit board glue dispensing area is obtained by multiplying the number by the area of a single grid, and the area of the glue shortage or glue leakage area is multiplied by the normal height difference between the upper end face of the thimble corresponding to the grid marked with glue shortage or glue leakage in the three-dimensional image model and the reference surface, so that the volume of the glue shortage or glue leakage part on the circuit board glue dispensing area is obtained.
Further, the number of grids marked with multiple glue in the 2D gray scale grid diagram of the upper end face of the thimble is counted, the area of the multiple glue area on the glue dispensing area of the circuit board is obtained by multiplying the number by the area of a single grid, and the volume of the multiple glue part on the glue dispensing area of the circuit board is obtained by multiplying the area of the multiple glue area by the normal height difference between the upper end face of the thimble corresponding to the grid marked with multiple glue in the three-dimensional image model and the reference surface.
A circuit board dispensing detection device for a circuit board dispensing detection method comprises a phase taking module, a 3D point cloud image processing software algorithm module, a comparison module and a display module, wherein the phase taking module is used for controlling a 3D camera to take a phase of the upper end part of a thimble and generate a 3D point cloud image when the view finding direction of a lens of the 3D camera is aligned with the upper end part of the thimble; the 3D point cloud image processing software algorithm module is used for positioning and cutting the 3D point cloud image generated by the phase taking module, fitting a datum plane, establishing a 3D point cloud coordinate system, establishing a three-dimensional image model of the upper end surface of the thimble, and calculating the normal height difference between the upper end surface of the thimble and a reference surface obtained by each modeling; the comparison module is used for creating and generating a 2D gray-scale grid map of the upper end surface of the thimble, and comparing and analyzing the generated 2D gray-scale grid map of the upper end surface of the thimble and the 2D gray-scale grid map of the reference surface to generate a dispensing quality conclusion of a dispensing area of the circuit board; the display module is used for displaying the 2D gray scale grid diagram of the upper end face of the thimble generated by the comparison module and the dispensing quality conclusion of the dispensing area of the circuit board.
A computer-readable storage medium having computer-executable instructions stored thereon which, when executed by a processor, cause the processor to perform the steps of a circuit board dispensing detection method.
The invention adopts the technical proposal to achieve the following beneficial effects: the ejector pin of the ejector pin mechanism is in pressure contact with the upper surface of the circuit board glue dispensing area, so that the ejector pin forms different height distributions according to the concave-convex fluctuation condition of the upper surface of the circuit board glue dispensing area, the concave-convex fluctuation condition of the upper surface of the circuit board glue dispensing area is simulated through the upper end part of the ejector pin, the 3D point cloud image of the upper end surface of the ejector pin is obtained through the 3D camera and modeled, and the 2D gray grid graph is created according to the normal height difference with the reference surface, so that the concave-convex condition of the circuit board glue dispensing area is displayed in an imaging mode through the 2D gray grid graph, various interference factors generated by directly photographing the glue dispensing area are eliminated, the glue dispensing detection precision is greatly improved, and the defects of more glue, less glue, glue leakage or residual glue and the like existing in the circuit board glue dispensing can be accurately identified.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following drawings in the embodiments are described below, and it is obvious that the following drawings are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts:
FIG. 1 is a schematic view of step 1 of the present invention;
FIG. 2 is a schematic view of step 3 of the present invention;
FIG. 3 is an enlarged view of a portion of FIG. 2 at A;
FIG. 4 is a top view of the ejector pin mechanism of FIG. 2;
FIG. 5 is a schematic diagram of step 3 and step 4 of the present invention;
FIG. 6 is a schematic diagram of the upper end surface and the reference surface of the thimble in the three-dimensional image model.
In the drawings, the parts corresponding to the reference numerals are as follows: 1-circuit board, 2-2D camera, 3-dispensing area, 4-residual glue, 5-thimble mechanism, 6-thimble, 8-3D camera, 9-thimble upper end face, 10-reference face, 11-little glue, 12-base, 13-spring, 14-guide hole and 15-guide post.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
A method for detecting the dispensing of a circuit board comprises the following steps:
step 1: before the glue dispensing of the circuit board 1 is carried out, luminous powder is added in advance in glue used for the glue dispensing of the circuit board 1;
step 2: referring to fig. 1, after point gluing, under a dark light environment, obtaining an image of a circuit board 1 by using a 2D camera 2, thresholding the image of the circuit board 1, identifying a highlight area in the thresholded image, extracting contour points of the highlight area, forming the edge of a glue dispensing area 3 by all the contour points, comparing and analyzing the edge with an image of a standard glue dispensing circuit board, if the edge of a glue dispensing area does not exist on the image of the standard glue dispensing circuit board, obtaining a conclusion of a residual glue 4 defect, otherwise, obtaining a conclusion that the residual glue defect does not exist; in the step 2, the image of the circuit board 1 after thresholding is vertically projected on an x/y plane, 2D features are extracted from the image after vertical projection, the 2D features comprise an average gray value and a high brightness percentage, and a high brightness area in the image after thresholding is identified according to the average gray value and the high brightness percentage;
and step 3: referring to fig. 2 and 5, the 2D camera 2 is removed, a thimble mechanism 5 composed of a plurality of thimbles capable of moving up and down is arranged, the thimble mechanism 5 is moved from top to bottom, so that the lower end of the thimble 6 is in contact with the upper surface of the dispensing area 3 of the circuit board 1, the overall outline shape of the plurality of thimbles 6 is overlapped with the outline shape of the dispensing area 3 of the circuit board 1 in the vertical direction, after the lower end of the thimble 6 is in contact with the upper surface of the dispensing area 3 of the circuit board 1, the thimble mechanism 5 is continuously moved down, so that the thimble 6 forms different height distributions according to the concave-convex dispensing fluctuation condition of the upper surface of the dispensing area 3 of the circuit board 1, and the concave-convex condition of the upper surface of the dispensing area 3 of the circuit board 1 is simulated through the upper end of the thimble 6; referring to fig. 2 to 4, the thimble mechanism 5 further includes a base 12 and a spring 13, the base 12 is provided with a guide hole 14, the thimble 6 is provided with a guide post 15, the guide post 15 is movably inserted into the guide hole 14 of the base 12, the spring 13 is sleeved outside the guide post 15, one end of the spring 13 abuts against a step surface at a joint of a lower end of the guide post 15 and the thimble 6, and the other end of the spring 13 abuts against a lower surface of the base 12; in the step 3, the circuit board 1 is clamped and positioned by a pneumatic clamp, and the thimble mechanism 5 is lifted by a servo linear module;
and 4, step 4: arranging a light source and a 3D camera 8, enabling the view finding direction of a lens of the 3D camera 8 to face the upper end part of the thimble 6, acquiring a 3D point cloud image through the 3D camera 8, carrying out detection area positioning on the acquired 3D point cloud image and cutting the acquired 3D point cloud image to obtain a 3D point cloud image of the upper end surface 9 of the thimble; in the step 4, the step of cropping the acquired 3D point cloud image includes the steps of: extracting 3D features from the obtained 3D point cloud image, classifying the 3D point cloud image area of the upper end surface 9 of the thimble and the 3D point cloud image area of the background according to the extracted 3D features, cutting off the 3D point cloud image area of the background according to a classification result, and obtaining the 3D point cloud image of the upper end surface 9 of the thimble;
and 5: carrying out three-dimensional modeling on the 3D point cloud image of the upper end surface 9 of the thimble to obtain a three-dimensional image model consisting of a plurality of upper end surfaces 9 of the thimble, referring to FIG. 6, establishing a reference surface 10 in the three-dimensional image model, wherein the normal height of the reference surface 10 is the height of the upper surface of the thimble 6 when the thimble 6 is in pressure contact with a standard dispensing area of a circuit board, and respectively calculating the normal height difference between the upper end surface 9 of each thimble obtained by modeling and the reference surface 10; in the step 5, the three-dimensional modeling of the 3D point cloud image of the thimble upper end surface 9 includes the following steps: performing reference plane fitting in the 3D point cloud image of the cut thimble upper end surface 9, calculating a normal vector of the reference plane, taking the normal vector direction as a Z-axis direction, taking two mutually perpendicular directions on the reference plane as X, Y axes, establishing a 3D point cloud coordinate system, calculating coordinates of all point clouds in the 3D point cloud image of the cut thimble upper end surface 9 in the 3D coordinate system, and generating a plurality of three-dimensional images of the thimble upper end surface 9;
step 6: creating a 2D gray grid graph, wherein each grid of the 2D gray grid graph corresponds to the upper end surface 9 of each thimble in the three-dimensional image model respectively, determining the gray value of each grid according to the normal height difference between the upper end surface 9 of each thimble in the three-dimensional image model and the reference surface 10, and generating the 2D gray grid graph of the upper end surface 9 of each thimble;
and 7: comparing and analyzing the 2D gray scale grid graph of the thimble upper end surface 9 generated in the step 6 with the 2D gray scale grid graph of the reference surface to obtain a dispensing quality conclusion of the dispensing area 3 of the circuit board 1, if the gray value of a certain grid is lower than that of the grid of the reference surface, indicating that the dispensing area 3 of the circuit board 1 corresponding to the thimble upper end surface 9 has less glue 11 or glue leakage, and if the gray value of a certain grid is higher than that of the grid of the reference surface, indicating that the dispensing area 3 of the circuit board 1 corresponding to the thimble upper end surface 9 has more glue;
in the step 7, traversing each grid of the 2D gray scale grid pattern of the thimble upper end surface 9, comparing an image of each grid with a grid image of a corresponding position of the 2D gray scale grid pattern of the reference surface, if the gray value of the grid is lower than that of the grid of the reference surface, marking a little glue 11 or a leaking glue on the grid of the 2D gray scale grid pattern of the thimble upper end surface 9, and if the gray value of the grid is higher than that of the grid of the reference surface, marking a much glue on the grid of the 2D gray scale grid pattern of the thimble upper end surface 9. Counting the number of grids marked with less glue 11 or glue leakage in the 2D gray scale grid diagram of the upper end surface 9 of the thimble, multiplying the number by the area of a single grid to obtain the area of the area marked with less glue 11 or glue leakage on the glue dispensing area 3 of the circuit board 1, and multiplying the area of the area marked with less glue 11 or glue leakage by the normal height difference between the upper end surface 9 of the thimble corresponding to the grid marked with less glue 11 or glue leakage in the three-dimensional image model and the reference surface 10 to obtain the volume of the area marked with less glue 11 or glue leakage on the glue dispensing area 3 of the circuit board 1. Counting the number of grids marked with multiple glue in the 2D gray scale grid diagram of the upper end surface 9 of the thimble, multiplying the number by the area of a single grid to obtain the area of the multiple glue area on the glue dispensing area 3 of the circuit board 1, and multiplying the area of the multiple glue area by the normal height difference between the upper end surface 9 of the thimble corresponding to the grid marked with multiple glue in the three-dimensional image model and the reference surface 10 to obtain the volume of the multiple glue part on the glue dispensing area 3 of the circuit board 1.
The embodiment also provides a circuit board dispensing detection device for the circuit board dispensing detection method, which comprises a phase taking module, a 3D point cloud image processing software algorithm module, a comparison module and a display module, wherein the phase taking module is used for controlling the 3D camera 8 to take a phase of the upper end part of the thimble 6 and generate a 3D point cloud image when the view finding direction of the lens of the 3D camera 8 is aligned with the upper end part of the thimble 6; the 3D point cloud image processing software algorithm module is used for positioning and cutting the 3D point cloud image generated by the phase taking module, fitting a datum plane, establishing a 3D point cloud coordinate system, establishing a three-dimensional image model of the upper end surface 9 of the thimble, and calculating the normal height difference between the upper end surface 9 of the thimble and the reference surface 10 obtained by each modeling; the comparison module is used for creating and generating a 2D gray-scale grid map of the thimble upper end surface 9, and comparing and analyzing the generated 2D gray-scale grid map of the thimble upper end surface 9 with the 2D gray-scale grid map of the reference surface to generate a dispensing quality conclusion of the dispensing area 3 of the circuit board 1; the display module is used for displaying the 2D gray scale grid diagram of the thimble upper end surface 9 generated by the comparison module and the dispensing quality conclusion of the dispensing area 3 of the circuit board 1.
The present embodiment also provides a computer-readable storage medium, which stores computer-executable instructions, and when the computer-executable instructions are executed by a processor, the processor executes the steps of the circuit board dispensing detection method.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A method for detecting the dispensing of a circuit board is characterized by comprising the following steps:
step 1: before the glue dispensing of the circuit board (1), luminous powder is added in advance in glue used for the glue dispensing of the circuit board (1);
step 2: after point gluing, acquiring an image of the circuit board (1) by using a 2D camera (2) in a dark light environment, thresholding the image of the circuit board (1), identifying a high-brightness area in the thresholded image, extracting contour points of the high-brightness area, forming the edge of a glue dispensing area (3) by all the contour points, comparing and analyzing the edge with an image of a standard glue dispensing circuit board, obtaining a conclusion of a defect of residual glue (4) if the edge of the glue dispensing area which does not exist on the image of the standard glue dispensing circuit board appears, and otherwise obtaining a conclusion that the defect of the residual glue does not appear;
and step 3: removing the 2D camera (2), arranging a thimble mechanism (5) consisting of a plurality of thimbles capable of moving up and down, moving the thimble mechanism (5) from top to bottom to enable the lower end part of the thimble (6) to be in contact with the upper surface of the dispensing area (3) of the circuit board (1), and continuing to move the thimble mechanism (5) downwards after the lower end part of the thimble (6) is in contact with the upper surface of the dispensing area (3) of the circuit board (1) to enable the thimble (6) to form different height distributions according to the concave-convex fluctuation condition of the upper surface of the dispensing area (3) of the circuit board (1), so as to simulate the concave-convex fluctuation condition of the upper surface of the dispensing area (3) of the circuit board (1) through the upper end part of the thimble (6);
and 4, step 4: arranging a light source and a 3D camera (8), enabling the lens view direction of the 3D camera (8) to face the upper end part of the thimble (6), acquiring a 3D point cloud image through the 3D camera (8), carrying out detection area positioning on the acquired 3D point cloud image, and cutting to obtain the 3D point cloud image of the upper end surface (9) of the thimble;
and 5: carrying out three-dimensional modeling on the 3D point cloud image of the upper end surface (9) of the thimble to obtain a three-dimensional image model consisting of a plurality of upper end surfaces (9) of the thimble, establishing a reference surface (10) in the three-dimensional image model, wherein the normal height of the reference surface (10) is the height of the upper surface of the thimble (6) when the thimble (6) is in press contact with a standard dispensing area of a circuit board, and respectively calculating the normal height difference between the upper end surface (9) of the thimble and the reference surface (10) obtained by modeling;
step 6: creating a 2D gray grid graph, wherein each grid of the 2D gray grid graph corresponds to the upper end surface (9) of each thimble in the three-dimensional image model respectively, determining the gray value of each grid according to the normal height difference between the upper end surface (9) of each thimble and a reference surface (10) in the three-dimensional image model, and generating the 2D gray grid graph of the upper end surface (9) of each thimble;
and 7: and (3) comparing and analyzing the 2D gray grid graph of the thimble upper end surface (9) generated in the step (6) with the 2D gray grid graph of the reference surface to obtain a dispensing quality conclusion of the dispensing area (3) of the circuit board (1), if the gray value of a certain grid is lower than that of the grid of the reference surface, the condition that the dispensing area (3) of the circuit board (1) corresponding to the thimble upper end surface (9) has less glue (11) or glue leakage is described, and if the gray value of the certain grid is higher than that of the grid of the reference surface, the condition that the dispensing area (3) of the circuit board (1) corresponding to the thimble upper end surface (9) has more glue is described.
2. The circuit board dispensing detection method of claim 1, wherein in the step 5, three-dimensional modeling of the 3D point cloud image of the needle tip upper end surface (9) comprises the steps of: and fitting a reference plane in the 3D point cloud image of the cut thimble upper end surface (9), calculating a normal vector of the reference plane, taking the normal vector direction as a Z-axis direction, taking two mutually perpendicular directions on the reference plane as X, Y axes, establishing a 3D point cloud coordinate system, calculating coordinates of all point clouds in the 3D point cloud image of the cut thimble upper end surface (9) in the 3D coordinate system, and generating a plurality of three-dimensional images of the thimble upper end surface (9).
3. A circuit board dispensing detection method according to claim 1, characterized in that in step 2, the thresholded circuit board (1) image is vertically projected on an x/y plane, 2D features are extracted from the vertically projected image, the 2D features include an average gray value and a high brightness percentage, and a high brightness region in the thresholded image is identified according to the average gray value and the high brightness percentage.
4. The method for detecting the dispensing of the circuit board according to claim 1, wherein in the step 4, the step of cutting the acquired 3D point cloud image comprises the steps of: and 3D features are extracted from the obtained 3D point cloud image, the 3D point cloud image area of the upper end surface (9) of the thimble and the 3D point cloud image area of the background are classified according to the extracted 3D features, and the 3D point cloud image area of the background is cut off according to the classification result to obtain the 3D point cloud image of the upper end surface (9) of the thimble.
5. The circuit board dispensing detection method according to claim 1, wherein the ejector pin mechanism (5) further comprises a base (12) and a spring (13), a guide hole (14) is formed in the base (12), a guide post (15) is formed in the ejector pin (6), the guide post (15) is movably inserted into the guide hole (14) of the base (12), the spring (13) is sleeved outside the guide post (15), one end of the spring (13) abuts against a step surface at a joint of the lower end of the guide post (15) and the ejector pin (6), and the other end of the spring (13) abuts against a lower surface of the base (12).
6. The method for detecting the dispensing of the circuit board according to claim 1, wherein in the step 7, traversing each grid of the 2D gray grid pattern of the upper end surface (9) of the thimble, comparing the image of each grid with the grid image of the corresponding position of the 2D gray grid pattern of the reference surface, if the gray value of the grid is lower than that of the grid of the reference surface, marking the grid of the 2D gray grid pattern of the upper end surface (9) of the thimble with less glue (11) or leaking glue, and if the gray value of the grid is higher than that of the grid of the reference surface, marking the grid of the 2D gray grid pattern of the upper end surface (9) of the thimble with more glue.
7. The method for detecting the dispensing of the circuit board according to claim 6, characterized in that the number of the grids marked with less glue (11) or glue leakage in the 2D gray grid diagram of the upper end surface (9) of the ejector pin is counted, the area of the area marked with less glue (11) or glue leakage on the dispensing area (3) of the circuit board (1) is obtained by multiplying the number by the area of the area marked with less glue (11) or glue leakage by the normal height difference between the upper end surface (9) of the ejector pin corresponding to the grid marked with less glue (11) or glue leakage in the three-dimensional image model and the reference surface (10), and the volume of the area marked with less glue (11) or glue leakage on the dispensing area (3) of the circuit board (1) is obtained.
8. The method for detecting the dispensing of the circuit board according to claim 6, characterized in that the number of grids marked with multiple glue in the 2D gray grid diagram of the upper end surface (9) of the thimble is counted, the area of the multiple glue area on the dispensing area (3) of the circuit board (1) is obtained by multiplying the number by the area of a single grid, and the volume of the multiple glue part on the dispensing area (3) of the circuit board (1) is obtained by multiplying the area of the multiple glue area by the normal height difference between the upper end surface (9) of the thimble corresponding to the grid marked with multiple glue in the three-dimensional image model and the reference surface (10).
9. The circuit board dispensing detection device for the circuit board dispensing detection method according to claim 1, comprising a phase taking module, a 3D point cloud image processing software algorithm module, a comparison module and a display module, wherein the phase taking module is used for controlling the 3D camera (8) to take a phase of the upper end of the thimble (6) and generate a 3D point cloud image when the lens view finding direction of the 3D camera (8) is aligned with the upper end of the thimble (6); the 3D point cloud image processing software algorithm module is used for positioning and cutting the 3D point cloud image generated by the phase taking module, fitting a datum plane, establishing a 3D point cloud coordinate system, establishing a three-dimensional image model of the upper end surface (9) of the thimble, and calculating the normal height difference between the upper end surface (9) of the thimble and the reference surface (10) obtained by modeling; the contrast module is used for creating and generating a 2D gray-scale grid graph of the thimble upper end surface (9), and comparing and analyzing the generated 2D gray-scale grid graph of the thimble upper end surface (9) and the generated 2D gray-scale grid graph of the reference surface to generate a dispensing quality conclusion of the dispensing area (3) of the circuit board (1); the display module is used for displaying the 2D gray scale grid diagram of the thimble upper end surface (9) generated by the comparison module and the dispensing quality conclusion of the dispensing area (3) of the circuit board (1).
10. A computer-readable storage medium having computer-executable instructions stored thereon, which, when executed by a processor, cause the processor to perform the steps of the circuit board dispensing detection method according to any one of claims 1 to 8.
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