Precision correction method for flatness test equipment

Abstract

The invention discloses a precision correction method for flatness test equipment. The precision correction method comprises the following steps: acquiring a first coordinate of a symmetric center of a first calibration piece by using a CCD camera; controlling the light spot of the laser head to move towards the first coordinate according to a preset coordinate difference value, then enabling the laser head to move to the boundary of the first calibration piece along the X direction and the Y direction, recording the position coordinate when the distance measured by the laser head suddenly changes, calculating the central abscissa value and the central ordinate value, and obtaining the first calculation central coordinate of the first calibration piece; comparing the first calculation center coordinate with the first coordinate, calculating a difference value, and correcting the plane position deviation of the laser head according to the difference value; detecting and correcting the perpendicularity of the laser head; and controlling the light spot of the laser head to move to the first coordinate again so as to carry out plane coordinate correction again. In the embodiment of the invention, the position deviation value and the inclination angle can be calculated to correct the laser head.

Description

Technical Field

[0001] The present application relates to the technical field of precision correction of flatness testing equipment, and in particular to a precision correction method of flatness testing equipment. Background Art

[0002] In the related technology, flatness will affect the mounting of the device, and the commonly used flatness measurement method is laser triangulation. Laser triangulation is based on a laser triangulator, which generates a parallel and coherent laser beam to illuminate the object to be measured. When the laser beam is irradiated on the surface of the object, part of the light will be reflected, and these reflected lights are received by the receiving element. By calculating the angle of the reflected light and the known distance between the transmitter and the receiver in the laser triangulator, the distance between the sensor and the object can be calculated.

[0003] During measurement, the CCD lens is used to capture the center of the pad, while the laser triangulation instrument is used to measure the flatness of the pad. There is a certain distance between the centers of the CCD lens and the laser triangulation instrument. The two work as follows: After the CCD lens captures the center of the pad, the CCD lens moves (according to the coordinate difference between the CCD lens and the center of the laser triangulation instrument) to move the laser triangulation instrument to the center of the pad. During the three-dimensional movement process, the position of the laser may move, resulting in deviation from the position of the CCD lens.

[0004] In addition, the laser emitted by the laser triangulation instrument must be consistent with the angle of the table (for example, the laser is perpendicular to the table). When the angle changes during the process due to abnormal reasons (such as collision or loose fixed parts), it will affect the measured height data, resulting in inaccurate measurement. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a method for calibrating the accuracy of a flatness testing device, which can calibrate the position accuracy and angle accuracy of a laser head to ensure measurement accuracy.

[0006] According to the flatness test equipment accuracy calibration method of the embodiment of the present application, the calibration method comprises the following steps:

[0007] Acquire a first coordinate of a symmetry center of the first calibration piece using a CCD camera;

[0008] According to the preset coordinate difference, the laser head spot is controlled to move to the first coordinate, and then the laser head is moved to the boundary of the first calibration piece along the X direction and the Y direction respectively, the position coordinates when the distance measured by the laser head changes suddenly are recorded, and the central horizontal coordinate value and the central vertical coordinate value are calculated to obtain the first calculated central coordinates of the first calibration piece;

[0009] The first calculated center coordinate is compared with the first coordinate and a difference is calculated, and the plane position deviation of the laser head is corrected according to the difference;

[0010] Detect and correct the verticality of the laser head;

[0011] The light spot of the laser head is controlled to move to the first coordinate again to perform plane coordinate correction again.

[0012] Furthermore, the step of using a CCD camera to obtain the first coordinates of the center of symmetry of the first calibration piece includes: using the CCD camera to capture the outer contour of the first calibration piece, and controlling the CCD camera to move to directly above the first calibration piece. At this time, the plane coordinates of the position of the CCD camera are the plane coordinates of the first coordinates.

[0013] Furthermore, the first calibration piece is a prism, and the step of detecting and correcting the verticality of the laser head includes:

[0014] Control the laser head spot to scan the midpoints of each oblique edge of the prism, and obtain the height coordinates of the scanned position at the same time, record the plane coordinate values ​​when the height coordinate suddenly changes during the scanning process, and calculate the horizontal distance L between the two scanning points with sudden height coordinate changes on the same inclined plane. 1 ;

[0015] According to the horizontal distance L 1 And the angle between the laser spot trajectory and the inclined surface is calculated based on the theoretical midline length of the inclined surface;

[0016] Calculate the deflection angle of the laser head according to the included angle;

[0017] The verticality of the laser head is corrected according to the calculated deflection angle.

[0018] Furthermore, the side length of the top end face of the prism is d, the side length of the bottom end face of the prism is D, and the angle between the hypotenuse of the prism and the bottom end face is 45°.

[0019] Furthermore, the length of the theoretical center line of the inclined plane is (D+d) / 2, and the distance between the actual center line of the laser scanning on the inclined plane and the theoretical center line of the inclined plane is h. The deflection angle of the laser head compared to the vertical direction is α = arcsin (h * sin45 ° / c), where hour, when hour,

[0020] Furthermore, the calibration system also includes a second calibration piece and a connector, the first calibration piece and the second calibration piece are both regular 2N-gonal prisms, wherein N≥2, the height difference between the first calibration piece and the second calibration piece is H, H is greater than 0, and the height of the connector is respectively smaller than the height of the first calibration piece and the second calibration piece.

[0021] Furthermore, the step of detecting and correcting the verticality of the laser head includes:

[0022] Acquire a second coordinate of the symmetry center of the top surface of the second calibration piece using a CCD camera;

[0023] The laser head is controlled to move to the second coordinate, and it is determined whether the light spot of the laser head is at the center position to determine whether the verticality of the laser head is offset.

[0024] Furthermore, the top end surface of the second calibration piece is provided with a plurality of angle scale identification rings, and the plurality of angle scale identification rings are arranged concentrically with the center position of the top end surface of the second calibration piece.

[0025] Furthermore, the step of detecting and correcting the verticality of the laser head further includes:

[0026] Control the light spot of the laser head to move to the second coordinate, move the laser head to the boundary of the first calibration piece along the X direction and the Y direction respectively, record the position coordinates when the distance measured by the laser head changes suddenly, and then calculate the central abscissa value and the central ordinate value of the second calibration piece to obtain the second calculated central coordinates of the second calibration piece;

[0027] Calculate the distance L between the center coordinates of the second coordinate and the second calculated center coordinate 2 ;

[0028] According to the calculated distance L 2 The angle between the laser head and the vertical direction, i.e. the deflection angle, is calculated based on the height difference H, and the angle of the laser head is corrected according to the calculated deflection angle.

[0029] Furthermore, the angle between the laser head and the direction perpendicular to the table is θ = arctan (L 2 / H).

[0030] The precision calibration method of the flatness testing equipment of the embodiment of the present application has at least the following beneficial effects: by calibrating on the first calibration piece, the actual plane coordinate deviation value between the laser head and the CCD camera can be determined, and whether the laser head is tilted and the specific tilt angle can be determined, and the laser head can be calibrated according to the calculated position deviation value and tilt angle. In this way, it helps to ensure the accuracy of the laser head measurement.

[0031] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present application is further described below with reference to the accompanying drawings and embodiments, wherein:

[0033] Figure 1 This is a schematic diagram of the measurement of the laser triangulation instrument;

[0034] Figure 2 A schematic diagram of measuring a PCB with a stepped groove after an angle deviation occurs in a laser triangulation measuring instrument;

[0035] Figure 3 A schematic diagram of a process flow of a method for calibrating the accuracy of a flatness testing device according to an embodiment of the present application;

[0036] Figure 4 This is a schematic diagram of the structure of a first calibration component in an embodiment of the present application;

[0037] Figure 5 A schematic diagram of a top measurement area of ​​a first calibration piece in an embodiment of the present application;

[0038] Figure 6 A schematic diagram of the inclined surface measurement area of ​​the first calibration piece in one embodiment of the present application;

[0039] Figure 7 A schematic diagram of the positions of a theoretical center line of one side surface of a first calibration piece and an actual center line of a laser scan in an embodiment of the present application;

[0040] Figure 8 A schematic diagram of the angle between the laser light and one of the side surfaces of the first calibration component in one embodiment of the present application;

[0041] Fig. 9 This is a schematic diagram of the coordination of the first calibration piece, the second calibration piece and the connector in another embodiment of the present application;

[0042] Fig.10 A schematic diagram of a top measurement area of ​​a second calibration piece in an embodiment of the present application;

[0043] Fig.11 This is a top schematic diagram of a second calibration piece in one embodiment of the present application;

[0044] Fig.12 This is a schematic structural diagram of the first calibration component in another embodiment of the present application.

[0045] Reference numerals:

[0046] 1. Laser transmitter; 2. Receiving element; 3. Photoelectric detector; 4. Alignment target; 5. CCD lens detection path; 6. Laser detection path;

[0047] 100, first calibration piece; 110, first top end surface; 111, first coordinate; 120, inclined plane; 121, theoretical center line; 122, actual center line; 130, hypotenuse;

[0048] 200, second calibration piece; 210, second top end surface; 211, angle scale identification ring.

[0049] 300. Connector. DETAILED DESCRIPTION

[0050] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0051] In the description of the present application, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 understood as a limitation on the present application.

[0052] In the description of this application, "several" means more than one, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0053] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0054] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0055] In related technologies, flatness refers to the flatness of the circuit board surface in the vertical direction, that is, the height deviation of the circuit board surface. Flatness testing is required more frequently in PCBs, as flatness affects the placement of components. The commonly used flatness measurement method is laser triangulation.

[0056] Specifically, Figure 1 As shown, a laser triangulation meter is added next to the CCD lens of the three-dimensional device. The laser transmitter 1 of the laser triangulation meter emits a laser beam, which passes through optical elements such as lenses, optical fibers and prisms to form a parallel and coherent laser beam that irradiates the object to be measured. When the laser beam irradiates the surface of the object, part of the light will be reflected, and these reflected lights are received by the photodetector 3 through the receiving element 2. By calculating the angle of the reflected light and the known distance between the laser transmitter 1 and the receiver (photodetector 3), the distance between the sensor and the object can be calculated.

[0057] During measurement, the CCD lens is used to capture the center of the pad, while the laser triangulation meter is used to measure the flatness of the pad. There is a certain distance between the centers of the CCD lens and the laser triangulation meter. The two work as follows: After the CCD lens captures the center of the pad, the CCD lens moves (according to the coordinate difference between the CCD lens and the center of the laser triangulation meter) to move the laser triangulation meter to the center of the pad. During the movement, the position of the laser may move, resulting in deviation from the position of the CCD lens.

[0058] The laser emitted by the laser triangulation instrument must maintain a stable angle with the table surface (here the laser is perpendicular to the table surface). If the angle changes during the process due to abnormal reasons such as collision or loosening of the fixed part, it will affect the measured height data and cause inaccurate measurement.

[0059] At the same time, due to the uneven process features such as step grooves on PCB, there are height differences on the board surface. When the angles of the laser triangulation meter and the CCD lens are inconsistent, after the CCD lens is positioned on the plane according to the alignment target 4, if the laser triangulation meter needs to measure the bottom pattern of the step groove, there will be a situation where the laser detection path 6 is inconsistent with the CCD lens detection path 5, resulting in an offset between the laser measurement point and the pattern, which will result in the measurement not being the height data of the CCD lens positioning position, resulting in measurement errors, such as Figure 2 shown.

[0060] Therefore, it is necessary to calibrate the position and angle of the laser triangulation instrument.

[0061] See also Figures 3 to 8 The present application discloses a method for calibrating the accuracy of a flatness testing device, comprising the following steps:

[0062] S110: using a CCD camera to obtain a first coordinate 111 of the symmetry center of the first calibration piece 100;

[0063] S120: According to the preset coordinate difference, the light spot of the laser head is controlled to move toward the first coordinate 111, so that the laser head moves to the boundary of the first calibration member 100 along the X direction and the Y direction respectively, and the position coordinates when the distance measured by the laser head changes suddenly are recorded, and the central horizontal coordinate value and the central vertical coordinate value are calculated to obtain the first calculated central coordinate of the first calibration member 100;

[0064] S130: Compare the first calculated center coordinate with the first coordinate 111 and calculate the difference, and correct the plane position deviation of the laser head according to the difference;

[0065] S140: Detect and calibrate the verticality of the laser head;

[0066] S150: Control the light spot of the laser head to move to the first coordinate 111 again to perform plane coordinate correction again.

[0067] It is worth understanding that, in the present embodiment, the first coordinate 111 is the plane coordinate of the symmetry center of the top surface of the first calibration component 100; the first calculated center coordinate refers to the plane coordinate of the symmetry center of the top surface calculated by the measurement data of the laser head. Due to the influence of errors, in the process of controlling the light spot of the laser head to move toward the first coordinate 111, the light spot of the laser head actually reaches the position corresponding to the first calculated center coordinate.

[0068] In the embodiment of the present application, by performing calibration on the first calibration piece 100, the actual plane coordinate deviation value between the laser head and the CCD camera can be determined, and whether the laser head is tilted and the specific tilt angle can be determined, and the position deviation value and the tilt angle can be calculated to calibrate the laser head. This helps to ensure the accuracy of the laser head measurement.

[0069] Since the error includes the deviation between the preset coordinate difference of the center of the CCD camera and the laser head and the actual coordinate difference (plane error), as well as the deviation caused by the installation angle of the laser head (verticality error), correction is performed in the order of plane correction, angle correction, and plane correction again to ensure the correction quality.

[0070] It can be understood that the precision calibration method of the flatness testing equipment of the present application is applied to a calibration system, and the calibration system includes a first calibration piece 100, a CCD camera and a laser head, and the first calibration piece 100 has a symmetry center.

[0071] In some embodiments of the present application, the step of using a CCD camera to obtain the first coordinate 111 of the symmetry center of the first calibration piece 100 includes: using the CCD camera to capture the outer contour of the first calibration piece 100, and controlling the CCD camera to move to the top of the first calibration piece 100. At this time, the plane coordinates of the position of the CCD camera are the plane coordinates of the symmetry center. Wherein, the top of the first calibration piece 100 refers to the normal direction of the symmetry center of the first calibration piece 100.

[0072] In the above embodiment, when the CCD camera moves to the top of the first calibration piece 100, the plane position coordinates of the CCD camera are the same as the plane position coordinates of the symmetry center of the top surface of the first calibration piece 100. Therefore, when the CCD camera moves to the top of the first calibration piece 100, the calibration system can obtain the plane coordinates of the symmetry center of the top surface of the first calibration piece 100. It should be noted that the top surface of the first calibration piece 100 is recorded as the first top surface 110. Figure 4 and Figure 5 shown.

[0073] In some embodiments of this application, see Figures 4 to 8The first calibration piece 100 is a prism, and the step of detecting and correcting the verticality of the laser head includes: controlling the light spot of the laser head to scan the midpoints of the oblique sides 130 of the prism, and obtaining the height coordinates of the scanned position at the same time, recording the plane coordinate values ​​when the height coordinate suddenly changes during the scanning process, calculating the horizontal distance L1 of the two scanning points with sudden height coordinate changes on the same inclined surface 120, and calculating the angle between the laser spot trajectory and the inclined surface 120 according to the horizontal distance L1 and the theoretical center line length of the inclined surface 120; calculating the deflection angle of the laser head according to the angle, and correcting the verticality of the laser head according to the calculated deflection angle.

[0074] Further, see Figures 5 to 7 , the length of the top face of the prism is d, the length of the bottom face of the prism is D, and the angle between the hypotenuse 130 of the prism and the bottom face is 45°. In this embodiment, for the convenience of calculation, the angle between the hypotenuse 130 of the prism and the bottom face is selected to be 45°.

[0075] It is worth to understand that the angle between the hypotenuse 130 and the bottom end face of the prism can also be set to other angles as required. For example, in some possible implementations, the angle between the hypotenuse 130 and the bottom end face can be set to 30°, 60°, etc.

[0076] Further, see Figure 7 , the length of the theoretical center line 121 of the inclined plane is (D+d) / 2, the distance between the laser scanning position on the inclined plane 120, i.e., the actual center line 122 and the theoretical center line 121 of the inclined plane is h, The deflection angle of the laser head compared to the vertical direction is α = arcsin (h*sin45° / c),

[0077] Among them, when hour, when hour,

[0078] In this way, the deflection angle of the laser head compared to the vertical direction can be calculated, so that the operator can calibrate the laser head according to the calculated deflection angle to improve the measurement accuracy.

[0079] In a specific implementation, the specific steps of the flatness testing equipment accuracy calibration method are as follows:

[0080] A first calibration piece 100 is provided. The first calibration piece 100 is a prism. The material of the first calibration piece 100 is a material that has little dimensional change with temperature and humidity, and the first calibration piece 100 is opaque. The top and bottom cross-sections of the first calibration piece 100 are both square, the angles between the four inclined surfaces and the bottom plane are 45 degrees, and the angles between the four oblique sides 130 and the bottom side are designed to be 45 degrees.

[0081] It is worth understanding that the top of the first calibration piece 100 can be other shapes with a symmetrical center, such as a circle, an isosceles triangle, a rectangle, etc.; the side is a cone or a prism with a certain inclination angle, and the angle of the inclination remains consistent.

[0082] Specifically, the first calibration piece 100 is a prism, the top cross section of the prism is a square with a side length of d; the angle between the inclined plane of the prism and the bottom plane is 45 degrees; the angle between the hypotenuse 130 and the bottom side of the prism is 45 degrees. The bottom cross section of the prism is a square with a side length of D.

[0083] During calibration, the first calibration piece 100 is placed on the glass table of the three-dimensional device, and the three-dimensional CCD lens is moved to the top of the fixture. The CCD lens captures the two diagonal corners of the top of the first calibration piece 100, and the CCD lens moves to the center of the top square plane.

[0084] Then, switch to the laser triangulation measuring instrument, which includes a laser head (the laser triangulation measuring instrument automatically moves to the original CCD lens position according to the settings and the coordinate deviation of the CCD lens), so that the light spot of the laser triangulation measuring instrument moves to the center of the square plane.

[0085] Then let the laser triangulation instrument move along the following path, and at the same time detect the height of the measured position and match it with the coordinate value: first move along the X direction, record the coordinates of the sudden change in height during the movement of the laser triangulation instrument, and then calculate the center coordinate Xc; after resetting, let the laser triangulation instrument move along the Y direction, record the coordinates of the sudden change in height during the movement, and then calculate the center coordinate Yc to obtain the first calculated center coordinate (Xc, Yc). Then compare (Xc, Yc) with the center coordinate of the square found by the CCD lens, input the difference into the device, and correct the coordinate deviation of the laser triangulation instrument and the CCD lens.

[0086] After the coordinate deviation of the laser triangulation meter and the CCD lens is corrected, the verticality of the laser triangulation meter needs to be tested. Specifically, the laser triangulation meter is used to scan the midpoints of the four oblique edges 130 of the first calibration component 100, and the height of the measured position is detected and matched with the coordinate value at the same time. When the height suddenly changes, the corresponding coordinate value is recorded, and the distance L is calculated through the two height sudden change coordinates on the same inclined surface. 1 , the length of the theoretical center line 121 of the inclined plane is (D+d) / 2, and the distance h between the position of the laser scanning on the inclined plane and the actual center line 122 of the actual scanning is

[0087] The above formula can be used to calculate the angle between the laser and each surface, and then the deflection angle of the laser triangulation instrument can be obtained based on the calculated angle, and correction can be performed based on the angle.

[0088] Finally, after the deflection angle measured by the laser triangulation measuring instrument is corrected, the laser triangulation measuring instrument is controlled to perform another correction of the center origin of the top surface of the calibration piece.

[0089] In some embodiments of the present application, see Figures 9 to 11 , the calibration system further includes a second calibration piece 200 and a connector 300, the first calibration piece 100 and the second calibration piece 200 are both regular 2N-gonal prisms, wherein N≥2, the height difference between the first calibration piece 100 and the second calibration piece 200 is H, H is greater than 0, and the height of the connector 300 is respectively less than the height of the first calibration piece 100 and the second calibration piece 200. Specifically, in this embodiment, the height of the first calibration piece 200 is H 1 , the height of the second calibration piece 200 is H 2 , H1 is greater than H 2 , and H 1 With H 2 The difference is H.

[0090] Furthermore, the step of detecting and correcting the verticality of the laser head includes: using a CCD camera to obtain the second coordinate of the center of symmetry of the top surface of the second calibration piece 200, controlling the laser head to move to the second coordinate, and judging whether the light spot of the laser head is in the center position to determine whether the verticality of the laser head is offset.

[0091] Further, see Fig.11 The top surface of the second calibration piece 200 is provided with a plurality of angle scale identification rings 211 , and the plurality of angle scale identification rings 211 are arranged concentrically with the center position of the top surface of the second calibration piece 200 .

[0092] The top end surface of the second calibration member 200 is recorded as the second top end surface 210. Fig. 9 shown.

[0093] Furthermore, the spot of the laser head is controlled to move to the second coordinate, so that the laser head moves to the boundary of the first calibration piece 100 along the X direction and the Y direction respectively, and the position coordinates when the distance measured by the laser head changes suddenly are recorded, and then the central horizontal coordinate value and the central vertical coordinate value of the second calibration piece 200 are calculated to obtain the second calculated central coordinate of the second calibration piece 200, and the distance L between the central coordinates of the two is calculated according to the second coordinate and the second calculated central coordinate. 2 , according to the calculated distance L 2 The angle between the laser head and the vertical direction, i.e. the deflection angle, is calculated based on the height difference H, and the angle of the laser head is corrected according to the calculated deflection angle.

[0094] Furthermore, the angle between the laser head and the direction perpendicular to the table is θ = arctan (L 2 / H). In this way, the calculated included angle θ is the deflection angle of the laser head. The laser head is calibrated according to the obtained deflection angle to ensure the measurement accuracy of the laser head.

[0095] In a specific embodiment, see Figures 9 to 11 The calibration system includes two connected rectangular blocks (which may also be regular 2N-gonal prisms (N≥2)), made of a material that changes little in size with temperature and humidity and is opaque; the top of each rectangular block is a square, and there is a height difference H between the top surfaces of the two rectangular blocks, and the two rectangular blocks are connected in the middle by a connector 300, and the height of the connector 300 is lower than the top of any one of the rectangular blocks, wherein the size and shape of each rectangular block and the connector 300 are fixed.

[0096] Specifically, the first calibration piece 100 is a cuboid, the top cross section of the cuboid is a square, the side length is D, and the height is H. 1 The second calibration piece 200 is a rectangular parallelepiped, the top cross-section of the rectangular parallelepiped is a square, the side length is D, and the height is H 2 ;H 1 and H 2 The height difference is H. The connector 300 is connected between the two cuboids, and the height of the connector 300 is lower than the tops of the two cuboids.

[0097] During calibration, the first calibration piece 100, the second calibration piece 200 and the connector 300 are placed as a whole on a three-dimensional glass table, the three-dimensional CCD lens is moved to the top of the first calibration piece 100 of the fixture, the CCD lens captures the two diagonal corners of the top of the first calibration piece 100, and the CCD lens moves to the center of the square plane on the top of the first calibration piece 100.

[0098] Then switch to the laser triangulation meter (the laser triangulation meter automatically moves to the original CCD lens position according to the settings and the coordinate deviation of the CCD lens), and then control the laser triangulation meter's light spot to move to the center of the square plane at the top of the first calibration piece 100. Then let the laser triangulation meter move along the following path, and simultaneously detect the height of the measured position and match it with the coordinate value: first move along the X direction to record the coordinates where the height changes suddenly from left to right, and then calculate the center coordinate Xc; then move along the Y direction, record the coordinates where the height changes suddenly from left to right, and then calculate the center coordinate Yc. Then compare (Xc, Yc) with the center coordinates of the square at the top of the first calibration piece 100 found by the CCD lens, input the difference into the device, and correct the coordinate deviation of the laser triangulation meter and the CCD lens.

[0099] After the coordinate deviation of the laser triangulation meter and the CCD lens is corrected, the verticality of the laser triangulation meter needs to be tested. Specifically, the laser triangulation meter whose position accuracy has been calibrated at the first calibration piece 100 is moved to the center C1 of the second calibration piece 200 (the position where the CCD grabs the first calibration piece 100 can be directly moved to the top center of the second calibration piece 200), and then observe whether the laser red dot of the laser triangulation meter at the top of the second calibration piece 200 is in the center position, as well as the position and angle of the offset.

[0100] Of course, the center of the second calibration piece 200 can also be scanned in the same way as measuring the top center position coordinates of the first calibration piece 100 to obtain the center C2 of the second calibration piece 200 calculated by the laser triangulation meter, and then the distance d between C1 and C2 can be calculated using the three-dimensional coordinates. The angle between the laser and the direction perpendicular to the table surface is θ=arctan(d / H). The deflection angle of the laser triangulation meter can be obtained based on the calculated angle and corrected based on the angle.

[0101] After the deflection angle measured by the laser triangulation measuring instrument is corrected, the laser triangulation measuring instrument is controlled to perform another central origin correction of the top square of the first calibration piece 100 .

[0102] In the above embodiment, the two connected cuboids (regular 2N-gonal prisms) can also be designed as follows: Fig.12 The structure shown in the figure, wherein the top middle of the structure shown in the figure is a hollow area. During calibration, the CCD camera is controlled to grasp the center of the top, and then grasp the center of the bottom, to determine the position offset and angle offset between the laser triangulation measurement and the CCD and to perform calibration.

[0103] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for calibrating the accuracy of a flatness testing device, characterized in that: The calibration method includes the following steps: Acquire a first coordinate of a symmetry center of the first calibration piece using a CCD camera; According to the preset coordinate difference, the laser head spot is controlled to move to the first coordinate, and then the laser head is moved to the boundary of the first calibration piece along the X direction and the Y direction respectively, the position coordinates when the distance measured by the laser head changes suddenly are recorded, and the central horizontal coordinate value and the central vertical coordinate value are calculated to obtain the first calculated central coordinates of the first calibration piece; The first calculated center coordinate is compared with the first coordinate and a difference is calculated, and the plane position deviation of the laser head is corrected according to the difference; Detect and correct the verticality of the laser head; The light spot of the laser head is controlled to move to the first coordinate again to perform plane coordinate correction again.

2. The method for calibrating the flatness testing equipment according to claim 1, characterized in that: The step of using the CCD camera to obtain the first coordinates of the center of symmetry of the first calibration piece includes: using the CCD camera to capture the outer contour of the first calibration piece, and controlling the CCD camera to move to directly above the first calibration piece. At this time, the plane coordinates of the position of the CCD camera are the plane coordinates of the first coordinates.

3. The method for calibrating the flatness testing equipment according to claim 1, characterized in that: The first calibration piece is a prism, and the step of detecting and correcting the verticality of the laser head includes: Control the laser head spot to scan the midpoints of the oblique sides of the prism, and obtain the height coordinates of the scanned position at the same time, record the plane coordinate values ​​when the height coordinate suddenly changes during the scanning process, and calculate the horizontal distance L1 between the two scanning points on the same inclined plane where the height coordinate suddenly changes; The angle between the laser spot trajectory and the inclined surface is calculated according to the horizontal distance L1 and the theoretical midline length of the inclined surface; Calculate the deflection angle of the laser head according to the included angle; The verticality of the laser head is corrected according to the calculated deflection angle.

4. The method for calibrating the flatness testing equipment according to claim 3, characterized in that: The length of the top face of the prism is d, the length of the bottom face of the prism is D, and the angle between the hypotenuse of the prism and the bottom face is 45°.

5. The method for calibrating the flatness testing equipment according to claim 4, characterized in that: The length of the theoretical center line of the inclined plane is (D+d) / 2, and the distance between the actual center line of the laser scan on the inclined plane and the theoretical center line of the inclined plane is h. The deflection angle of the laser head compared to the vertical direction is α = arcsin (h*sin45° / c), Among them, when hour, when hour, 6. The method for calibrating the flatness testing equipment according to claim 1, characterized in that: The calibration system also includes a second calibration piece and a connector. The first calibration piece and the second calibration piece are both regular 2N-gonal prisms, where N≥2. The height difference between the first calibration piece and the second calibration piece is H, H is greater than 0, and the height of the connector is smaller than the height of the first calibration piece and the second calibration piece, respectively.

7. The method for calibrating the flatness testing equipment according to claim 6, characterized in that: The step of detecting and correcting the verticality of the laser head includes: Acquire a second coordinate of the symmetry center of the top surface of the second calibration piece using a CCD camera; The laser head is controlled to move to the second coordinate, and it is determined whether the light spot of the laser head is at the center position to determine whether the verticality of the laser head is offset.

8. The method for calibrating the accuracy of a flatness testing device according to claim 7, characterized in that: The top end surface of the second calibration piece is provided with a plurality of angle scale identification rings, and the plurality of angle scale identification rings are arranged concentrically with the center position of the top end surface of the second calibration piece.

9. The method for calibrating the accuracy of a flatness testing device according to claim 7, characterized in that: The step of detecting and correcting the verticality of the laser head also includes: Control the light spot of the laser head to move to the second coordinate, move the laser head to the boundary of the first calibration piece along the X direction and the Y direction respectively, record the position coordinates when the distance measured by the laser head changes suddenly, and then calculate the central abscissa value and the central ordinate value of the second calibration piece to obtain the second calculated central coordinates of the second calibration piece; Calculate the distance L2 between the center coordinates of the two according to the second coordinate and the second calculated center coordinate; The angle between the laser head and the vertical direction, that is, the deflection angle, is calculated according to the calculated distance L2 and the height difference H, and the angle of the laser head is corrected according to the calculated deflection angle.

10. The method for calibrating the accuracy of a flatness testing device according to claim 9, characterized in that: The angle between the laser head and the direction perpendicular to the table is θ=arctan(L2 / H).

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