JP2012066331A - Alignment device, and alignment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform positional alignment and detection at a high level of accuracy without changing a distance between a camera and a workpiece before and after being fastened with screws even if a high-magnification camera is used.SOLUTION: An alignment device includes: a workpiece holding unit 30 for overlaying a second workpiece W2 on a first workpiece W1 for positioning; an imaging unit 40 for imaging an image of the second workpiece W2 from the other side of the first workpiece W1; a control unit 60 for processing the image of the workpiece W2 imaged by the imaging unit 40, and detecting the relative position of the workpiece W2 to the first workpiece W1; a pressure mechanism 50 for pressing the workpiece W2 with a buffer sheet S placed on the workpiece W1; an alignment control unit 61 for aligning the second workpiece W2 in cooperation with the workpiece holding unit 30 according to the relative position detected by imaging the second workpiece W2 by the imaging unit 40 after being pressed by the pressure mechanism 50 and before being fastened with screws; and an accuracy detection unit 62 for detecting the accuracy of the alignment by imaging the second workpiece W2 with the imaging unit 40 after being fastened with the screws.

Description

  Embodiments described herein relate generally to an alignment apparatus and an alignment method for positioning two workpieces with high accuracy.

  When two plate-shaped workpieces are stacked one on top of the other and assembled by screw fastening, a position detection mechanism that detects the position of the workpiece by image processing using a CCD camera installed above, and the workpiece In addition, an alignment apparatus having an actuator mechanism for moving a workpiece based on position information obtained based on a detection result of a position detection mechanism is used. After alignment by such an alignment apparatus, the two workpieces are connected by fastening with screws or the like that penetrate in the thickness direction of the workpiece. In addition, when high-accuracy alignment is required, alignment accuracy inspection is performed after screw fastening. For example, the allowable range is about plus or minus 10 μm.

  In addition, when at least one of the workpieces is a brittle material such as glass, the workpiece may be broken if it is firmly fastened. In order to prevent this, a buffer material sheet may be sandwiched between the workpieces.

  Further, the higher the accuracy of the alignment is required, the higher the magnification (about 10 to 20 times) of the CCD camera for detecting the position of the work is required. If the magnification increases, the image becomes blurred due to a slight focal length error, and the position detection accuracy by image processing decreases.

JP 2000-221374 A

  When the workpiece is fixed by screw fastening, the cushioning material sheet is crushed, and the distance between the camera and the workpiece slightly changes before and after the screw fastening. Due to this distance difference, for example, when the camera is installed so that the distance between the workpiece and the camera before screw fastening matches the focal length of the camera, alignment can be performed with high accuracy, but the image is not displayed after screw fastening. It is blurred and the accuracy of the position inspection is deteriorated.

  On the other hand, when the camera is installed so that the distance between the work after the screw fastening and the camera matches the focal length of the camera, the position inspection after the screw fastening can be performed with high accuracy, but the positioning accuracy is deteriorated.

  Therefore, even when a high-magnification camera is used, an alignment apparatus and an alignment method that can perform both alignment and position inspection with high accuracy by not changing the distance between the workpiece and the camera before and after screw fastening. The purpose is to provide.

  In the alignment apparatus used when the first workpiece and the second workpiece are screwed together with a buffer sheet interposed therebetween, a workpiece gripping unit that positions the second workpiece on the first workpiece, and the first workpiece An imaging unit that images the second workpiece from the opposite side of the first workpiece, and a relative image of the second workpiece to the first workpiece by processing an image of the second workpiece imaged by the imaging unit A detection unit for detecting a position, a pressurizing unit that pressurizes the second workpiece with the buffer sheet sandwiched between the first workpiece, the pressurizing unit, and after screw fastening A positioning control unit that images the second workpiece by the imaging unit and positions the second workpiece by the workpiece gripping unit based on the detected relative position; and after the screw fastening, by the imaging unit Above The second workpiece captured, and a precision detector which detects the positioning accuracy.

  In the alignment method used when the first workpiece and the second workpiece are screwed together with a buffer sheet interposed therebetween, the second workpiece is supplied onto the first workpiece, and the second workpiece is moved to the first workpiece. Pressurizing the buffer sheet on one workpiece side, imaging the second workpiece from the opposite side of the first workpiece, processing the image of the second workpiece, and The relative position of the second workpiece is detected, the second workpiece is overlapped on the first workpiece and positioned with high accuracy, and after screw fastening, the second workpiece is imaged to detect positioning accuracy. Do.

1 is a perspective view schematically showing an alignment apparatus according to an embodiment. Explanatory drawing which shows the alignment process by the alignment apparatus. Explanatory drawing which shows the alignment process by the alignment apparatus. Explanatory drawing which shows the alignment process by the alignment apparatus. Explanatory drawing which shows the alignment process by the alignment apparatus.

  FIG. 1 is a perspective view schematically showing an alignment apparatus 10 according to an embodiment, and FIGS. 2 to 5 are explanatory views showing an alignment process by the alignment apparatus 10. W1 is a first workpiece made of, for example, a metal plate, W2 is a second workpiece made of, for example, a glass plate (brittle material), S is a buffer sheet made of a resin material, and N is a screw.

  The alignment apparatus 10 is an apparatus for superimposing the first workpiece W1 and the second workpiece W2 with high accuracy of, for example, plus or minus 10 μm or less.

  The alignment apparatus 10 includes a support portion 20 that fixes and supports the first workpiece W1, a workpiece gripping portion 30 that grips and positions the second workpiece W2, and a second workpiece W2 above the first workpiece W1. An imaging unit (detection unit) 40 provided on the opposite side of the workpiece W1, a pressurizing mechanism 50 that presses the second workpiece W2 toward the first workpiece W1, and a positioning control unit 60 that controls these units in cooperation. It has.

  The workpiece gripper 30 includes six support members 31 that support four side surfaces of the second workpiece W2 and four actuators 32 that move the support members 31, and determines the position of the second workpiece W2.

  The imaging unit 40 includes a pair of CCD cameras 41 and an image processing unit 42. The CCD camera 41 takes an image of the alignment mark M formed on the upper surface of the second workpiece W2, and performs image processing by the image processing unit 42 to detect the relative position of the second workpiece W2 with respect to the first workpiece W1. The focal length of the CCD camera 41 is Q.

  The pressurizing mechanism 50 includes four cylinders 51 and pistons 52 projecting and retracting from the four cylinders 51, respectively, and pressurizes the four pressurization positions P of the second workpiece W2. The pressurization is controlled so that the four pressures are equalized. Further, the amount of pressurization is set in advance so that when the applied pressure is released, the amount of collapse of the buffer sheet S is equal to the amount of collapse by screw fastening (within the depth of field).

  The control unit 60 calculates the relative position with respect to the first workpiece W1 based on the position information of the second workpiece W2 obtained by the image processing unit 42, and calculates the operation amount of the positioning mechanism 30.

  The positioning control unit 60 images the second workpiece W2 by the imaging unit 40 after pressurization by the pressurization mechanism 50 and before screw fastening, and the workpiece gripping unit 30 based on the detected relative position. In addition to the positioning unit 61 that positions the second workpiece W2 by the above, an accuracy detection unit 62 that images the second workpiece W2 by the imaging unit 40 and detects the positioning accuracy after the screws are fastened.

  In the alignment apparatus 10 configured as described above, the first workpiece W1 and the second workpiece W2 are aligned as follows. That is, the first workpiece W1 is attached to the support portion 20. Next, as shown in FIG. 2, the second workpiece W2 and the buffer sheet S are supplied above the first workpiece W1. The positioning performed at this time is coarse positioning.

  Next, as shown in FIG. 3, the pressurizing mechanism 50 pressurizes the second workpiece W2 with the buffer sheet S sandwiched between the first workpiece W1 side. The amount of pressurization is the same as the amount by which the cushion sheet S is crushed by screw fastening when the applied pressure is released.

  In this state, as shown in FIG. 4, the CCD camera 41 images the alignment mark M of the second workpiece W2 from the opposite side of the first workpiece W1. At this time, the distance L1 between the CCD camera 41 and the second workpiece W2 substantially coincides with the focal length Q of the CCD camera 41, and imaging can be performed with high accuracy.

  As shown in the comparison diagram on the right side of FIG. 4, in the absence of the pressurizing mechanism 50, the distance L3 between the CCD camera 41 and the second workpiece W2 is focused by the amount δ that the buffer sheet S is not crushed. It becomes shorter than the distance Q. As described above, since the CCD camera 41 has a high magnification, even a slight difference δ falls outside the depth of field range, and the accuracy of the captured image of the CCD camera 41 is lowered.

  The image of the second workpiece W2 is processed to detect the relative position of the second workpiece W2 with respect to the first workpiece W1. Next, the positioning unit 61 calculates the movement amount of the second workpiece W2 based on the obtained relative position, and commands the workpiece gripping unit 30. In the workpiece gripping part 30, the actuator 32 is operated to position the second workpiece W2 at a predetermined position of the first workpiece W1.

  Next, screw fastening is performed by a screw fastening device or the like (not shown). Thereby, the buffer sheet S is crushed. Then, after screw fastening, the accuracy detection unit 62 images the alignment mark M by the imaging unit 40 and inspects the positioning accuracy. At this time, since the distance L2 between the CCD camera 41 and the second workpiece W2 substantially coincides with the focal length Q of the CCD camera 41, the accuracy of the captured image of the alignment mark M is high.

  As described above, according to the alignment apparatus 10, the CCD camera 41 and the second work W2 are aligned when the first work W1 and the second work W2 are aligned by the positioning control unit 61 before screw fastening. The distance L1 and the distance L2 between the CCD camera 41 and the second workpiece W2 that are used when detecting the positioning accuracy between the first workpiece W1 and the second workpiece W2 by the accuracy detection unit 62 after screw fastening Any of them can be made to coincide with the focal length Q of the CCD camera 41, so that the captured image of the alignment mark M is not blurred. For this reason, the accuracy of position detection can be improved. The distances L1 and L2 may be within the depth of field even if they do not exactly coincide with the focal length Q.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Alignment apparatus, 20 ... Support part, 30 ... Work holding part, 32 ... Actuator, 40 ... Imaging part (detection part), 41 ... CCD camera, 42 ... Image processing part, 50 ... Pressure mechanism, 60 ... Control part , 61 ... Positioning section, 62 ... Accuracy detection section, W1 ... First work, W2 ... Second work, S ... Buffer sheet, N ... Screw.

Claims (5)

In the alignment apparatus used when the first workpiece and the second workpiece are screwed with the buffer sheet interposed therebetween,
A workpiece gripper for positioning the second workpiece on the first workpiece;
An imaging unit for imaging the second workpiece from the opposite side of the first workpiece;
A detection unit that processes an image of the second workpiece imaged by the imaging unit and detects a relative position of the second workpiece with respect to the first workpiece;
A pressurizing unit that pressurizes the second workpiece with the buffer sheet sandwiched between the first workpiece and the first workpiece;
After the pressurization by the pressurization unit and before the screw fastening, the imaging unit captures an image of the second workpiece, and the second workpiece by the workpiece gripping unit is detected based on the detected relative position. A positioning control unit for positioning;
An alignment apparatus comprising: an accuracy detection unit configured to image the second workpiece by the imaging unit and detect positioning accuracy after the screws are fastened.   The pressurization amount by the pressurizing unit is such that when the applied pressure is released, a difference between an amount by which the buffer sheet is crushed and an amount by which the buffer sheet is crushed is within a depth of field range. The alignment apparatus described in 1.   The alignment apparatus according to claim 1, wherein at least one of the first work and the second work is formed of a brittle material.   The alignment apparatus according to claim 1, wherein the surface of the second workpiece is positioned at a focal position of the camera after being pressed by the pressing unit. In the alignment method used when the first workpiece and the second workpiece are screwed with the buffer sheet interposed therebetween,
Supplying the second workpiece onto the first workpiece;
Pressurizing the second workpiece with the buffer sheet sandwiched between the first workpiece and the first workpiece;
Imaging the second workpiece from the opposite side of the first workpiece;
Processing the image of the second workpiece to detect the relative position of the second workpiece with respect to the first workpiece;
Overlaying the second work on the first work and positioning with high accuracy,
An alignment method comprising: imaging the second workpiece after screw fastening and detecting positioning accuracy.

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