JP2011191307A - Correction tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correction tool which does not need an advanced device, such as a laser measuring machine, or complicated labor and corrects the X-axis and Y-axis coordinates of a component-mounting device. <P>SOLUTION: The correction tool 75 is provided for determining the movement correction values in the X-axis and Y-axis directions of the component-mounting device in which components are mounted at target locations by moving a mount head in the X-axis direction and the Y-axis direction. The tool includes a main section made of glass having a rectangular surface having sides, the sides being disposed along the X-axis and the Y-axis of the component-mounting device, respectively; and a plurality of observation points 77, 78 which are formed on the surface, recognized by a camera mounted on the mount head, respectively, and disposed aligned in a single line in the X-axis and Y-axis directions, respectively, along the sides of the main section. Other observation points are not provided in the inner regions of the plurality of observation points 77, 78 that are disposed on a single line in the surface. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a correction jig, and more particularly to a correction jig in an apparatus in which a predetermined object is moved along a coordinate axis.

  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 of the insulating material is selectively 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. As a result, the electronic components are connected to each other to form a predetermined electronic circuit.

  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, Y-axis direction, and Z-axis direction. Is mounted at a predetermined position.

  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.

  In such a component mounting apparatus, since the mount head having the suction nozzle at the tip is moved along the X axis and the Y axis, respectively, the X axis and the Y axis have high rigidity and are crazy. It is necessary to be provided in a state where there is no. If the X-axis and Y-axis are distorted, bent, or wavy, the movement of the mount head is distorted, and the electronic component cannot be mounted at the correct position.

  Therefore, conventionally, simple correction has been performed for the X axis and the Y axis by three-point measurement. However, in such correction, only the inclination of each of the X axis and the Y axis and the averaged feed error correction can be performed. In addition, to correct the running accuracy such as straightness of the X-axis and Y-axis, it is necessary to perform time-consuming measurement using an advanced device such as a laser length measuring device, especially for mass-production devices. There is a problem that productivity is inferior.

  The present invention has been made in view of such problems, and corrects the coordinate axes with high accuracy without using a sophisticated device such as a laser length measuring instrument and without requiring complicated work. An object of the present invention is to provide a correction jig that can be used.

  In order to solve the above problems, the correction jig of the present invention is an X-axis direction and a Y-axis direction of a component mounting apparatus that mounts a component at a target position by moving the mount head in the X-axis direction and the Y-axis direction. A correction jig for obtaining a correction value of the movement of the main body made of glass having a rectangular surface having sides arranged along the X-axis and the Y-axis of the component mounting apparatus, and a surface A plurality of observation points arranged in one row in the X-axis direction and the Y-axis direction along the side of the main body, each recognized by a camera mounted on the mount head, and within the surface No other observation point is provided in a region inside a plurality of observation points arranged in one row.

  In an apparatus having an X axis and a Y axis, in order to correct the running accuracy such as straightness of the X axis and the Y axis, it is necessary to perform measurement such as an advanced apparatus and a troublesome laser length measurement. In the above aspect, the correction accuracy can be easily corrected by measuring the observation point on the correction tool using the workpiece recognition camera attached to the head using the correction jig that has already been measured by an external measuring instrument. It becomes possible. In addition, even in the case of mass production of equipment, there is no need for a measuring machine and preparation for measuring the equipment, so that productivity can be improved and services after equipment shipment can be easily performed regardless of location. It becomes possible.

  The main invention related to the correction jig relates to a correction jig having a flat plane and having observation points arranged in a line along a coordinate axis on the flat plane.

  Accordingly, a correction jig having a very simple configuration is provided, and a correction jig for correcting the coordinate axes of the apparatus without performing sophisticated apparatus or lengthy measurement or the like is provided.

It is a perspective view which shows the whole structure of a component mounting apparatus. It is the front view which fractured | ruptured a part which shows a mount head. It is a side view of the mount head. It is a side view of a mount head when a mirror is retracted. It is a side view of a mount head when a suction nozzle is lowered. It is a block diagram which shows the system configuration | structure of a control part. It is a top view of a reference jig. It is a top view of the reference | standard jig | tool which has a positioning hole. It is a flowchart which shows the operation | movement of measurement of correction data. It is a flowchart which shows calculation of a correction formula. It is a top view which shows the calibration target on a camera image. It is a top view which shows the observation point on a camera image. It is a graph which shows the error of straightness. It is a graph which shows accumulation read error

The present invention will be described below with reference to the drawings. First, the overall configuration of a component mounting apparatus for mounting a component at a target position by moving the mount head in the X-axis direction and the Y-axis direction will be described with reference to FIGS.

  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.

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.

  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.

  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.

  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.

  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.

  The workpiece recognition camera 42 and the component recognition camera 62 are connected to a controller 63 via image processing circuits 65 and 66, respectively, as shown in FIG. The controller 63 includes a computer (CPU) for inputting the image information captured by the workpiece recognition camera 42 and the component recognition camera 62 and subjected to image processing by the image processing circuits 65 and 66 and performing an operation. In addition, it is connected to the storage device 67. 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.

  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.

  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. Consists workpiece recognition camera 42 for detecting the position of the circuit board 15 for mounting because the motor 54, and the electronic component.

  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 rotation operation of the suction nozzle 20, that is, the θ-axis operation is performed thereby.

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.

  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.

  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.

  In such a component mounting apparatus, the machine coordinate system composed of the X-axis unit 17 and the Y-axis unit 18 has NC coordinates that are ideal XY coordinates on the circuit board 15 depending on the processing accuracy and assembly accuracy of the components. It is a coordinate system with distortion to the system. Therefore, correction for matching such a machine coordinate system with an ideal NC coordinate system must be performed. Such correction will be described below.

  A coordinate correction reference jig 75 (correction jig) used in the XY coordinate correction is shown in FIG. The reference jig 75 is made of, for example, a stainless steel plate, and a plurality of observation points 76, 77, and 78 are formed on the reference jig plane by a method such as etching. Further, a camera calibration target 79 is provided in the vicinity of the observation point 76. When further correction accuracy is required, it is desirable to provide an observation point and a camera calibration target on the glass substrate (main body) by vapor deposition of chromium or the like.

  Although the observation points 76, 77, and 78 shown in FIG. 7 are circular, these observation points are not necessarily circular, and may be any shape as long as the center coordinates of the observation points can be recognized with the highest accuracy by image processing. The camera calibration target 79 is used to determine the scale and camera coordinate system of the workpiece recognition camera 42 described above. Here, in order to remove the error due to the spherical aberration of the lens of the workpiece recognition camera 42, it is preferable that the target shape shown in FIG.

  The observation points applied on the plane of the reference jig 75 are ideal XY coordinate systems that coincide with the NC coordinate system, and hold position coordinate data of the respective observation points 76, 77, and 78 that are measured in advance. The array of points of the camera calibration target 79 is arranged so as to coincide with the above-described NC coordinate system.

  Further, when the reference jig 75 is positioned at a specified position by a reference pin or the like on the part where the circuit board 15 is placed, it is preferable to provide positioning holes 81 and 82 in the reference jig 75 as shown in FIG. At this time, when the position of the reference pin is set as the origin of the NC coordinate, it is necessary to consider the distance between the observation point origin and the positioning hole 81 of the reference pin as an offset value in the correction value described below.

  Next, the correction data measurement method will be described with reference to the flowchart shown in FIG. The X-axis unit 17 and the Y-axis unit 18 of the component mounting apparatus shown in FIG. 1 are connected to the camera calibration target 79 on the reference jig 75 positioned at a predetermined position on the transport conveyor 14 from the origin position, that is, the machine coordinate origin. The workpiece recognition camera 42 is moved to the position. At this time, the workpiece recognition camera 42 comprising a CCD camera recognizes the calibration target 79 as shown in FIG. 11, matches the camera scale from the known target size, and matches the NC coordinate system from the array of points of the target 79. A camera coordinate system is generated, and an arbitrary position, for example, the center position of the visual field is determined as the camera coordinate origin.

  Next, the workpiece recognition camera 42 is moved to the observation point origin 76 on the reference jig 75. Here, in order to simplify the subsequent correction, the center of the observation point origin 76 is obtained by image processing, and the position of the workpiece recognition camera 42 is adjusted by the X-axis unit and the Y-axis unit so that the coordinate origin of the camera coincides. To do.

  From the position where the observation point origin 76 and the coordinate origin of the workpiece recognition camera 42 coincide, a plurality of observation points 77 arranged in the X-axis direction on the reference jig 75 are observed point positions that the reference jig 75 has as data. Based on the coordinate data, the workpiece recognition camera 42 is moved by the X-axis unit 17 and the Y-axis unit 18, and the center of each observation point is obtained by image processing as shown in FIG. In this image processing, the shift amount (Xri, Yri) (i = 0 to n) from the camera coordinate origin is stored in the storage device 67 connected to the CPU of the controller 63 shown in FIG. Similarly, this measurement is also performed on the observation point 78 in the Y-axis direction on the reference jig 75. This makes it possible to grasp the distortion of the machine coordinate system with respect to the NC coordinate system.

  Using the data obtained by the measurement as described above, a correction formula for correcting the distortion of the machine coordinate system of the component mounting apparatus is calculated using the calculation function by the CPU of the controller 63. FIG. 10 shows a flowchart for calculating the correction formula.

  First, the coordinates of the observation points 77 and 78 arranged at equal intervals on the orthogonal axis on the reference jig 75 are (Xpi, Ypi) (i = 0 to n), and the X-axis unit 17 and the Y-axis according to the above coordinates. The workpiece recognition camera 42 attached to the axis unit 18 is moved, and the observation point position deviation amount (Xri, Yri) (i = 0 to n) from the camera coordinate origin obtained by image recognition is set.

  From the measurement result (Xri, Yri) of each observation point 77 arranged on the X-axis line on the reference jig 75, the distribution of the measurement data of the Y-axis direction component (Yri) is the X-axis straightness error, that is, the X-axis. It represents the undulation defined by the deviation amount in the Y-axis direction. An approximate expression Fxs (Xpi) for correcting the undulation of the X axis and the Y axis is obtained. The distribution of the measurement data of the X-axis direction component (Xri) is a cumulative value of the feed error in the X-axis direction and represents a cumulative read error as shown in FIG. 14, and is an approximate expression for correcting by the X-axis. Fxp (Xpi) is obtained.

  Similarly, according to the measurement results (Xri, Yri) of the observation points 78 arranged on the Y axis on the reference jig 75, the distribution of the measurement data of the X axis direction component (Xri) is as shown in FIG. , That is, the undulation of the Y axis, and an approximate expression Fys (Ypi) for correction by the X axis is obtained. The distribution of the measurement data of the Y-axis direction component (Yri) represents the cumulative read error as shown in FIG. 14, and an approximate expression Fyp (Ypi) for correction by the Y-axis is obtained.

  The correction amount obtained from each of the above approximate expressions is Xhi = Fys (Ypi) + Fxp (Xpi) for the X axis and Yhi = Fxs (Xpi) + Fyp (Ypi) for the Y axis. When the target coordinates on the work target part are (Xti, Yti), the coordinates after correction of the XY axes obtained here are (Xti + Xhi, Yti + Yhi).

ここで最小二乗法の場合、パラメータＣ_ｋ（ｋ＝０〜ｍ）に関するＱ（Ｃ_０，Ｃ_１，・・・Ｃ_ｍ）の偏微分係数が同時に０になるとき最小値をとる。すなわち

次の関数を代入してＦ_ｍ（ｘ_ｉ）を展開すると、

となり、行列方程式により残差の平方和Ｑを最小にするパラメータの解（Ｃ０，Ｃ１，Ｃ２・・・Ｃｍ）を求める。

以上でｍ次多項式のパラメータＣ０，Ｃ１，Ｃ２・・・Ｃｍが求まる。 The approximate expression used here is calculated as follows. Now, the approximate expression is approximated by an m-th order polynomial, and each parameter is estimated by the least square method. An approximate function is set as F _m (x) = C ₀ x ⁰ + C ₁ x ¹ + C ₂ x ² +... + C _m x ^m . Residual _{r i} and the value _{y i} of the data corresponding to the value _F m _{(x i)} and _{x i} of the approximation function,
r _i = F _m (x _i ) −y _i (i = 0 to n) (n is the number of observation points)
It becomes. The parameters C ₀ , C ₁ , C ₂ ... C _{m at} this time are obtained so that the residual sum of squares Q is minimized.

Here, in the case of the least square method, the minimum value is taken when the partial differential coefficients of Q (C ₀ , C ₁ ,... C _m ) relating to the parameter C _k (k = _{0 to m} ) simultaneously become zero. Ie

Substituting the following function to expand F _m (x _i ),

Thus, a parameter solution (C0, C1, C2,... Cm) that minimizes the residual sum of squares Q is obtained by a matrix equation.

Thus, the parameters C0, C1, C2,.

Here, when the observation point coordinates (Xpi, Ypi) and the observation results (Xri, Yri) are applied, Fys (Ypi) becomes x _i → Ypi, y _i → Xri (from observation point 78 in FIG. 7).
Fxp (Xpi) is x _i → Xpi, y _i → Xri (from observation point 77 in FIG. 7).
Fxs (Xpi) is x _i → Xpi, y _i → Yri (from observation point 77 in FIG. 7).
Fyp (Ypi) is x _i → Ypi, y _i → Yri) (from observation point 78 in FIG. 7)
And each approximate expression is obtained. An approximate expression can be obtained similarly in the following expressions.

  Next, optimization of the m-th order polynomial will be described. The function of the above-described estimation model is a continuous function, and includes adjustable parameters, and measurement data includes measurement errors. In such a case, the log likelihood (L) varies depending on the parameter value. Therefore, the fitness is improved by adjusting the parameter value (1 to m order) so that the log likelihood (L) is maximized. If the number of parameters can be uniquely determined by experience values, the following may be omitted.

ここでＶ_０は観測ノイズの分散であって次式によって表される。

さらにＡＩＣ（Ａｋａｉｋｅ´ｓ ｉｎｆｏｒｍａｔｉｏｎ ｃｒｉｔｅｒｉｏｎ）を用い、パラメータの数を決定する。 The maximum log likelihood (L) is evaluated by the following equation.

Here, V ₀ is the variance of the observed noise and is expressed by the following equation.

Furthermore, the number of parameters is determined using AIC (Akaike's information criterion).

AIC = (− 2) × log (L) +2 (m) The model that gives the minimum AIC in the above equation is specified as the optimum model. The m-order polynomial of the number of parameters determined as described above is used as a correction formula.

相関係数ｒは

となり、相関係数が任意の有意水準より大きければ有意と判断できる。逆に小さい場合には観測点の測定ミスや装置の異常が考えられるために、再度測定を試行し、有意と判断できるｒを求めなければならない。 Next, the significance of this approximate expression is confirmed by the correlation coefficient r. First, the determination coefficient r2 is

The correlation coefficient r is

Thus, if the correlation coefficient is greater than an arbitrary significance level, it can be determined that the value is significant. On the other hand, if it is small, an observation point measurement error or an apparatus abnormality may be considered. Therefore, it is necessary to try measurement again and obtain r that can be determined to be significant.

  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 ... image processing circuit, 67 ... storage device , 75 ... Reference jig, 76 ... Observation origin, 77, 78 ... Observation point, 79 ... Camera calibration target, 81, 82 ... Positioning hole

Claims (4)

A correction jig for obtaining correction values for movement in the X-axis direction and Y-axis direction of a component mounting apparatus that mounts a component at a target position by moving a mount head in the X-axis direction and the Y-axis direction. ,
A main body made of glass having a rectangular surface having sides arranged along the X-axis and the Y-axis of the component mounting apparatus;
A plurality of observation points arranged in one row in each of the X-axis direction and the Y-axis direction along the side of the main body portion, which are formed on the surface and recognized by cameras mounted on the mount head; Including
The correction jig | tool of the component mounting apparatus in which the other observation point is not provided in the area | region inside the several observation point arrange | positioned in the said 1 line in the said surface. The correction jig according to claim 1, wherein the observation point is formed of chromium. A correction jig for obtaining correction values for movement in the X-axis direction and Y-axis direction of a component mounting apparatus that mounts a component at a target position by moving a mount head in the X-axis direction and the Y-axis direction. ,
A rectangular glass substrate having sides corresponding to the X axis and the Y axis;
A plurality of observation points formed on the glass substrate,
The plurality of observation points are composed of only one row along the side. A correction jig for a component mounting apparatus. A correction jig for obtaining correction values for movement in the X-axis direction and Y-axis direction of a component mounting apparatus that mounts a component at a target position by moving a mount head in the X-axis direction and the Y-axis direction. ,
For correction of a component mounting apparatus having a plurality of observation points arranged on a line orthogonal to each other along the X-axis and the Y-axis, and arranged in a line at equal intervals along the side of the correction jig jig.

Images