JP4715009B2 - How to recognize workpiece reference marks - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a workpiece reference mark recognition method, and more particularly to a workpiece reference mark recognition method in a mounting apparatus that mounts a component at a predetermined position on a workpiece by holding means.
[0002]
[Prior art]
The electronic circuit is formed on a circuit board made of an insulating material. In other words, the copper foil bonded on the circuit board is etched to form a predetermined wiring pattern, and a component is mounted thereon, and the electrode of the component is soldered to the connection land of the wiring pattern, whereby the electronic component is Connected to each other to form a predetermined electronic circuit.
[0003]
An electronic component mounting apparatus is used for mounting components on such a circuit board. The mounting apparatus includes a mount head, and a component is taken out from the parts cassette by a suction nozzle attached to the tip of the mount head, and is mounted on the circuit board by a combination of movements in the X-axis direction, the Y-axis direction, and the Z-axis direction. Is mounted at a predetermined position.
[0004]
Here, in order to correctly mount electronic components at a predetermined position on the circuit board, a work recognition camera is attached to the mount head, and the reference mark on the circuit board is image-recognized by this work recognition camera. Based on this, the position of the circuit board is corrected. In accordance with such position correction, the mounting of the component by the mount head is corrected, and the electronic component is correctly mounted at a predetermined position on the circuit board.
[0005]
Japanese Patent Application Laid-Open No. 2000-236199 discloses that a predetermined position on which a part of a mounting target is to be mounted is recognized on the mounting target in order to accurately recognize the image in a short time under an appropriate imaging condition and mount the part with a high probability. In order to control the operation of the component handling means based on the position information obtained by recognizing the predetermined position of the image, and to transfer and mount the component at the predetermined position, the appropriateness of the actual imaging information at the time of image recognition is determined. In response to the fact that the imaging conditions are set to a predetermined appropriateness and the characteristics of the imaging means and the imaging target vary from time to time, the position by image recognition under the imaging conditions set with this predetermined appropriateness A component mounting method is disclosed in which components are mounted based on information.
[0006]
[Problems to be solved by the invention]
As described above, in the conventional mounting apparatus, the board recognition camera for imaging the fiducial mark constituting the reference mark of the circuit board should have the fiducial mark when the circuit board is accurately positioned. Move to position. This is because the camera is moved to a position where the fiducial mark will come to the center of the field of view of the board recognition camera, the image is taken, the mark is recognized, and the amount of deviation from the center of the image is detected. This means calculating the amount of deviation.
[0007]
At this time, depending on the surface state of the fiducial mark on the circuit board, sufficient contrast cannot be obtained between the circuit board and the fiducial mark, and image processing fails. When the contrast between the fiducial mark and the circuit board cannot be obtained, the plating applied to the fiducial mark causes specular reflection, and the reflected light from the fiducial mark is sent to the substrate recognition camera. Occurs when not returning.
[0008]
When such image recognition failure occurs, an error occurs, and the mounting apparatus causes an error stop. Therefore, in this case, the operator goes in front of the mounting machine, picks up the circuit board, wipes the surface of the fiducial mark, and increases the reflectance. Alternatively, the circuit board is aligned by manual operation, and then the automatic operation state is restored and the circuit components are mounted. Such a method leads to a decrease in the operation rate, and the productivity decreases. Further, when the circuit board is positioned by manual operation by the operator, the mounting accuracy is deteriorated, and the electronic circuit is liable to be defective.
[0009]
The present invention has been made in view of such problems, and provides a workpiece reference mark recognition method that increases the success rate of image recognition of a workpiece reference mark such as a fiducial mark on a circuit board. The purpose is to do.
[0010]
[Means for Solving the Problems]
A main invention of the present application is a method for recognizing a workpiece reference mark in a mounting apparatus that holds a component by a holding unit and mounts the held component at a predetermined position on the workpiece.
In order to know the position of the workpiece, the reference mark provided on the workpiece is recognized by the workpiece recognition camera that moves together with the holding means,
Moreover, the position of the workpiece is detected by moving the workpiece recognition camera relative to the workpiece within a range where the reference mark falls within the field of view of the workpiece recognition camera and performing image recognition a plurality of times. The present invention relates to a method for recognizing a reference mark of a workpiece.
[0011]
Here, the work may be a circuit board, and a fiducial mark formed at a predetermined position on the circuit board may be recognized by a work recognition camera. In addition, it is preferable to use an image that has been successfully detected for the reference mark among the images obtained by multiple image recognitions for the position detection of the workpiece. The recognition accuracy can be improved by averaging the images of a plurality of reference marks obtained by a plurality of image recognitions.
[0012]
Another main invention of the present application is a method for recognizing a workpiece reference mark in a mounting apparatus that holds a component by a holding unit and mounts the held component at a predetermined position on the workpiece.
In order to know the position of the workpiece, the reference mark provided on the workpiece is recognized by the workpiece recognition camera that moves together with the holding means,
If image recognition fails, the workpiece recognition camera is moved relative to the workpiece to repeat image recognition, and if the reference mark is successfully recognized, the workpiece position is detected from the image. The present invention relates to a mark recognition method.
[0013]
Here, when the image recognition fails, the image is stored in the storage unit, and when the image recognition fails for a predetermined number of times, the stored image is combined and the reference mark is recognized. it can. Further, the movement position of the work recognition camera when the image recognition is successful may be stored, and the work recognition camera may be moved to that position when the reference mark of the next work is recognized.
[0014]
In a preferred embodiment of the invention included in the present application, in an electronic component mounting apparatus in which an electronic component is sucked from a parts cassette by a suction nozzle and mounted at a predetermined position on the circuit board, the circuit board is provided in advance to know the position of the circuit board. When a fiducial mark is picked up by a workpiece recognition camera that moves with the mount head and the position of this fiducial mark is recognized by image processing, the fiducial mark is within the field of view of the workpiece recognition camera. In this method, the position of the workpiece recognition camera is moved within the range to be entered, and a plurality of images are acquired and an image in which the fiducial mark position has been successfully detected is used.
[0015]
Here, the workpiece recognition camera may be moved only during a retry operation when the reference mark recognition fails. In addition, the recognition accuracy can be improved by averaging the positions of fiducial marks obtained from the plurality of acquired images. In addition, by offsetting the multiple acquired images by the amount of the position of the workpiece recognition camera and adding luminance information, the influence of uneven illumination on the circuit board can be reduced and the fiducial mark position can be easily recognized. can do. And according to the above aspects, the success rate of the image recognition of the fiducial mark on the circuit board can be remarkably improved as compared with the conventional case.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings. First, the overall configuration of a component mounting apparatus in which the reference mark recognition method for a circuit board is implemented will be described with reference to FIGS.
[0017]
As shown in FIG. 1, the component mounting apparatus includes a base 10, and a frame 11 is mounted on the base 10. A parts cassette mounting table 12 is provided on one side surface, and the parts cassette 13 is arranged and mounted on the mounting table 12. Although only a single parts cassette 13 is shown in FIG. 1, in practice, a large number of parts cassettes 13 each holding a tape holding different types of parts by a reel are arranged in a line. A transport conveyor 14 extending in the lateral direction is provided in front of the arrangement position of the parts cassette 13, and the circuit board 15 is supplied by the transport conveyor 14.
[0018]
On the other hand, an X-axis unit 17 is attached to the lower part of the frame 11, and a Y-axis unit 18 that can be moved in the X-axis direction by the X-axis unit 17 is provided. A mount head 19 is attached to be freely movable. As shown in FIG. 2, the mount head 19 is provided with a suction nozzle 20 at its tip side, and the suction nozzle 20 sucks and holds components and mounts it at a predetermined position on the circuit board 15.
[0019]
Next, the configuration of the mount head 19 will be described with reference to FIGS. The mount head 19 includes a frame 23, and a ball nut 24 is rotatably supported on the frame 23. The ball nut 24 is screwed with a ball screw 25 arranged vertically. Moreover, a pulley 26 is attached to the ball nut 24. A pulley 30 is attached to the output shaft 29 of the motor 28 on the frame 23. A timing belt 31 is stretched between the pulley 26 of the ball nut 24 and the pulley 30 of the output shaft 29 of the motor 28.
[0020]
The ball screw 25 having the suction nozzle 20 at the tip is further engaged with a spline nut 34. The spline nut 34 is located on the lower side of the ball nut 24 and further includes a pulley 35 on the outer periphery thereof. On the other hand, a pulley 37 is fixed to the output shaft of the motor 36 shown in FIG. A timing belt 38 is stretched between the pulley 35 of the spline nut 34 and the pulley 37 of the motor 36.
[0021]
A work recognition camera 42 is supported on the frame 23 via a bracket 41. The workpiece recognition camera 42 is for recognizing the circuit board 15 (see FIG. 1) sent by the conveyor 14 from above.
[0022]
A bracket 45 is fixed to the frame 23, and a linear guide 46 is attached to the front end side of the bracket 45 so as to extend in the lateral direction. A ball screw 47 is also supported by the bracket 45 in parallel with the linear guide 46. An arm 48 is fixed to a ball nut 49 that is screwed into the ball screw 47. A mirror 50 is attached to the tip side of the arm 48. A pulley 52 is fixed to the ball screw 47. A pulley 56 is fixed to the output shaft 55 of the motor 54 arranged in the horizontal direction. A timing belt 57 is stretched between the pulley 52 of the ball nut 49 and the pulley 56 of the motor 54. Further, a mirror 61 is supported on the side of the bracket 45 via another bracket 60, and a component recognition camera 62 is attached to the upper portion of the mirror 61. The component recognition camera 62 is for performing image recognition by reflecting the image of the lower surface of the component sucked by the suction nozzle 20 by the mirrors 50 and 61.
[0023]
The workpiece recognition camera 42 and the component recognition camera 62 are connected to a controller 63 as shown in FIG. The controller 63 includes a computer that performs image processing performed by the cameras 42 and 62 and performs calculations. The controller 63 controls the X-axis unit 17, the Y-axis unit 18, the motors 28, 36 and 54, and the transport conveyor 14.
[0024]
As described above, the electronic component mounting apparatus according to the present embodiment includes a parts cassette 13 that supplies electronic components wound in a tape as shown in FIG. 1, a conveyor 14 that conveys the circuit board 15, and an electronic component. Is mounted from the parts cassette 13 and mounted at a predetermined position on the circuit board 15, and the X-axis unit 17 and the Y-axis unit 18 for moving the mount head 19 to the predetermined position on the circuit board 15. It consists of and.
[0025]
2 and 3, the mount head 19 includes a suction nozzle 20 for sucking electronic components, a ball screw 25 with splines for moving and rotating the suction nozzle 20 in the vertical direction, and a spline. A motor 28 for rotating the ball nut 24 of the ball screw 25 with a timing via a timing belt 31; a motor 36 for rotating the spline nut 34 of the ball screw 25 with a spline via a timing belt 38; A first mirror 50, a second mirror 61, and a component recognition camera 62 for detecting the position of the electronic component adsorbed by the linear guide 46 for retracting the mirror 50 when the adsorption nozzle 20 moves up and down, The ball screw 47 is rotated via the ball screw 47 and the timing belt 57. Composed of board recognition camera 42 for detecting the position of the circuit board 15 for mounting because the motor 54, and the electronic component.
[0026]
If the ball nut 24 is rotated by the motor 28 while the spline nut 34 is stopped without driving the motor 36, the ball screw 25 moves up and down without rotating. Accordingly, the suction nozzle 20 can be moved in the Z-axis direction. On the other hand, when the spline nut 34 is rotated by the motor 36 and the ball nut 24 is rotated at the same angle by the motor 28, the ball screw 25 performs only rotational movement without moving up and down. Therefore, the operation of the θ axis of the suction nozzle 20 is thereby performed.
[0027]
Next, an outline of an electronic component mounting operation by such a mounting apparatus will be described. The circuit board 15 is transported by the transport conveyor 14 and positioned at a predetermined position. Then, this mounting apparatus moves the mount head 19 in the X-axis direction and the Y-axis direction by the X-axis unit 17 and the Y-axis unit 18, and recognizes the fiducial mark on the circuit board 15 as the workpiece provided on the mount head 19. The image is picked up by the camera 42 and its position is detected, thereby prompting the accurate position of the circuit board 15. By such an operation, it is possible to know where the workpiece recognition camera 42 is moved and where the electronic component is to be mounted.
[0028]
After that, the mount head 19 moves to the component take-out position of the parts cassette 13 for supplying the electronic components, and lowers the suction nozzle 20 to vacuum-suck the electronic components. At this time, the position of the mirror 50 is at a position retracted from the vertical movement area of the suction nozzle 20 as shown in FIGS. Then, after the suction nozzle 20 picks up the electronic component, it rises to a predetermined height by the rotation of the ball nut 24, and then the mirror 50 moves below the suction nozzle 20 as shown in FIG. Then, the image of the lower surface of the electronic component sucked by the suction nozzle 20 is reflected by the mirrors 50 and 61 and picked up by the component recognition camera 62.
[0029]
Using the information regarding the position of the electronic component imaged by the component recognition camera 62, the amount of displacement of the electronic component from the camera image reference position (usually the rotation center position of the suction nozzle 20) at the time of suction is detected. The mount head 19 moves to a predetermined position on the circuit board 15 programmed in advance to a position where the amount of positional deviation at the time of suction is corrected. Thereafter, the mirror 50 is retracted as shown in FIG. 4 and the suction nozzle 20 is lowered as shown in FIG. 5 to mount the electronic component at a predetermined position on the circuit board 15.
[0030]
As described above, the electronic component mounting apparatus according to the present embodiment includes the mount head 19, the mount head 19 has a vertical movement and a degree of freedom of rotation, and a suction nozzle 20 for sucking the electronic component, a circuit, and the like. A work recognition camera 42 for recognizing the position of the substrate 15 is provided. As described above, the mount head 19 is movable in the X-axis direction and the Y-axis direction. The mounting nozzle 19 sucks the electronic components from the parts cassette 13 by the suction nozzle 20, and corrects the suction posture to correct the predetermined position on the circuit board 15. This electronic component is mounted on.
[0031]
In order to mount the electronic component at a predetermined position on the circuit board 15 during such mounting, it is necessary to know the position of the circuit board 15 in advance. Therefore, in the electronic component mounting apparatus, before performing the above-described series of mounting operations, the workpiece recognition camera 42 is moved onto the fiducial mark 67 of the circuit board 15 as shown in FIG. The mark 67 is imaged and an operation for detecting the position of the circuit board 15 is performed. As shown in FIG. 6, the workpiece recognition unit includes a workpiece recognition camera 42 and a plurality of illumination devices 65 and 66 for illuminating the fiducial mark 67.
[0032]
The fiducial mark 67 is manufactured in the same process as the circuit board 15. That is, it is usually made of copper foil, and its surface may be soldered or gold-plated to prevent oxidation. A normal fiducial mark 67 is picked up as shown in FIG. When the workpiece recognition camera 42 is correctly moved with respect to the circuit board 15, an image of the fiducial mark 67 is generated at substantially the center of the field of view as shown in FIG. 7B.
[0033]
However, in the case of the circuit board 15 that has been plated, the surface of the fiducial mark 67 may cause specular reflection. In such a case, light from the illumination devices 65 and 66 is reflected by the workpiece recognition camera 42. May not return to the state. In this case, a sufficient contrast between the circuit board 15 and the fiducial mark 67 cannot be obtained, and image recognition may be difficult. FIG. 8 shows such a state. When the surface of the fiducial mark 67 undergoes total reflection and the reflected light deviates from the field of view of the work recognition camera 42, it is difficult to recognize the fiducial mark 67. .
[0034]
Therefore, in the present embodiment, as shown in FIG. 9 or FIG. 10, the movement position of the workpiece recognition camera 42 is set so that the camera 42 is placed on the circuit board 15 within the range where the fiducial mark 67 is within the field of view of the camera 42. On the other hand, the circuit board 15 and the fiducial mark are moved by moving in the X-axis direction or the Y-axis direction and changing the relative positional relationship between the illumination devices 65 and 66, the fiducial mark 67, and the workpiece recognition camera 42. The contrast with 67 is ensured, and this makes it possible to perform image recognition at the position of the fiducial mark 67.
[0035]
In FIG. 9, the work recognition camera 42 is offset with respect to the circuit board 15 so that the image of the fiducial mark 67 is positioned toward the end of the field of view of the work recognition camera 42. Here, the field of view of the workpiece recognition camera 42 is within a range of, for example, 4 × 5 mm. For this reason, the workpiece recognition camera 42 is moved within the range of 4 × 5 mm to retry the capture of the image of the fiducial mark 67. Can be performed.
[0036]
The amount by which the workpiece recognition camera 42 is offset may be a predetermined amount, but a random value may be set in a range in which the fiducial mark 67 does not leave the field of view of the workpiece recognition camera 42. If the image processing of the fiducial mark 67 is successful by offsetting, when the fiducial mark of the next circuit board 15 is recognized, the work recognition camera 42 is moved to a position where the same amount is offset in advance. Since the fiducial mark 67 is picked up and the image is recognized, the probability that the fiducial mark 67 is successfully recognized at once is increased.
[0037]
Further, depending on the surface state of the fiducial mark 67, as shown in FIG. 10B, the entire surface of the fiducial mark 67 may not shine brightly and may only be partially brightened. This is often the case when the plating layer 68 applied on the surface of the fiducial mark 67 is irregularly swelled as shown in FIG. 10A.
[0038]
In such a case, the plurality of image luminance data of the fiducial mark 67 captured while the workpiece recognition camera 42 is offset are added while being moved by the offset amount as shown in FIG. It is possible to create image data in which the entire spot corresponding to the char mark 67 is bright. Then, by performing the recognition process of the fiducial mark 67 on such image data, the position of the fiducial mark 67 can be recognized.
[0039]
FIG. 13 shows an example of the operation procedure of the computer that performs the image processing of the work recognition camera 42. Here, when the position of the fiducial mark 67 is successfully detected, the position of the circuit board 15 is detected based on the successful single image, and the mounting operation of the electronic component is automatically performed based on the position detection. Do.
[0040]
If the detection of the fiducial mark 67 fails despite a plurality of retries, the respective images are stored, and the stored images are added together with an offset amount as shown in FIG. Then, the position of the circuit board 15 is detected by recognizing the mark position, and electronic components are automatically mounted. If the mark position cannot be recognized despite multiple retries, an error will be stopped.
[0041]
FIG. 14 shows another procedure of image processing by a computer connected to the workpiece recognition camera 42. This procedure is a case where sufficient time may be taken for detection of the fiducial mark 67, and an operation of capturing the image of the fiducial mark 67 is always performed while offsetting. By averaging the mark positions of a plurality of images that have been successfully detected once, the recognition success rate of the fiducial mark 67 is increased and the accuracy of position detection of the fiducial mark 67 is also increased.
[0042]
Here, when the fiducial mark 67 is successfully detected, the mark recognition position is stored. When such an operation is repeated a plurality of times, it is determined whether or not the mark position has been successfully detected once or more, and if it has been successfully stored, it is stored successfully. An average value of the marks is calculated, and electronic components are automatically mounted on the circuit board 15 using such calculated detection positions. On the other hand, if the mark detection has not been successful once in a plurality of retries, the error is stopped.
[0043]
Although the invention of the present application has been described with the illustrated embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical idea of the invention included in the present application. For example, the above embodiment relates to mounting of electronic components on the circuit board 15, but the present invention can be widely applied to mounting devices for various other components.
[0044]
【The invention's effect】
The main invention of the present application is to recognize a workpiece position in a method for recognizing a workpiece reference mark in a mounting apparatus that holds a component by a holding means and mounts the held component at a predetermined position on the workpiece. The reference mark provided on the workpiece is image-recognized by a workpiece recognition camera that moves together with the holding means, and the workpiece recognition camera is positioned relative to the workpiece within a range where the reference mark falls within the field of view of the workpiece recognition camera. The position of the workpiece is detected by moving and performing image recognition a plurality of times.
[0045]
Therefore, according to such a method for recognizing a reference mark of a work, even when the surface of the reference mark causes total reflection and image recognition cannot be performed by the work recognition camera, the work recognition camera is moved to another position. As a result, image recognition is possible, which increases the success rate of image recognition of the reference mark.
[0046]
Another invention of the present application is a method for recognizing a workpiece reference mark in a mounting apparatus for holding a component by a holding means and mounting the held component at a predetermined position on the workpiece in order to know the position of the workpiece. Recognize the image of the fiducial mark provided on the work with the work recognition camera that moves with the holding means. If the image recognition fails, move the work recognition camera relative to the work and repeat the image recognition. If the recognition is successful, the position of the workpiece is detected from the image.
[0047]
Therefore, according to such a method for recognizing a reference mark for a work, when image recognition fails, the work recognition camera is moved relative to the work and the image recognition is repeated to eventually succeed in recognizing the reference mark. As a result, the position of the workpiece can be detected. Accordingly, the error stop of the mounting apparatus is reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the overall configuration of a component mounting apparatus.
FIG. 2 is a partially cutaway front view showing a mount head.
FIG. 3 is a side view of the mount head.
FIG. 4 is a side view of the mount head when the mirror is retracted.
FIG. 5 is a side view of the mount head when the suction nozzle is lowered.
FIG. 6 is a perspective view of a principal part showing position detection of a circuit board by a work recognition camera.
FIGS. 7A and 7B are a front view and a plan view when a fiducial mark is urged at the center of the field of view of the workpiece recognition camera. FIGS.
FIG. 8 is a front view and a plan view when a fiducial mark is totally reflected.
FIGS. 9A and 9B are a front view and a plan view when image recognition is performed by offsetting the position of the workpiece recognition camera.
FIG. 10 is a front view and a plan view when a plating layer is formed on the surface of a fiducial mark.
FIG. 11 is a plan view showing the operation of adding a plurality of images.
FIG. 12 is a block diagram illustrating a system configuration of a control unit.
FIG. 13 is a flowchart showing an operation of position detection using image processing by a computer.
FIG. 14 is a flowchart illustrating an operation of position detection using image processing by another computer.
[Explanation of symbols]
10 ... Base, 11 ... Frame, 12 ... Parts cassette mounting base, 13 ... Parts cassette, 14 ... Conveyor, 15 ... Circuit board, 17 ... X axis unit, 18 ... Y axis unit, 19 ... mount head, 20 ... suction nozzle, 23 ... frame, 24 ... ball nut, 25 ... ball screw, 26 ... pulley, 28 ... motor, 29 ... output shaft, 30 ... pulley, 31 ... Timing belt, 34 ... Spline nut, 35 ... Pulley, 36 ... Motor, 37 ... Pulley, 38 ... Timing belt, 41 ... Bracket, 42 ... Work recognition camera, 45 ... Bracket, 46 ... Linear guide, 47 ... Ball screw, 48 ... Arm, 49 ... Ball nut, 50 ... Mirror, 52 ... Pulley, 54 ... Motor, 55 ... Output shaft, 56 ... pulley, 57 ... timing belt, 60 ... bracket, 61 ... mirror, 62 ... parts recognition camera, 63 ... controller, 65, 66 ... lighting device, 67 ... fiducial Mark, 68 ... plating layer

Claims (2)

In a method for recognizing a workpiece reference mark in a mounting apparatus that holds a component by a holding means and mounts the held component at a predetermined position on the workpiece.
In order to know the position of the workpiece, the reference mark provided on the workpiece is recognized by the workpiece recognition camera that moves together with the holding means,
Save the image if it fails to the image recognition of the reference mark in the storage means, the repeated image recognition relatively moving the workpiece recognition camera relative to the workpiece, the storage in the case of consecutive failed a predetermined number of times It performs recognition of the reference mark combined image stored in the unit, the reference mark recognition method of the workpiece, characterized in that to detect the position of the workpiece by the image after a successful image recognition of the reference mark. In a method for recognizing a workpiece reference mark in a mounting apparatus that holds a component by a holding means and mounts the held component at a predetermined position on the workpiece.
In order to know the position of the workpiece, the reference mark provided on the workpiece is recognized by the workpiece recognition camera that moves together with the holding means,
If the image recognition of the reference mark fails, the work recognition camera is moved relative to the work to repeat image recognition, and if the image recognition of the reference mark is successful, the position of the work is detected by the image, The movement position of the work recognition camera when the image recognition of the reference mark is successful is stored, and the work recognition camera is moved to the position at the time of image recognition of the reference mark of the next work. A method for recognizing reference marks of workpieces.

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