JP2018032681A - Component mounting machine, and reference mark imaging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately execute imaging of a reference mark in accordance with deformation amounts of drive parts that drive a head unit in different directions.SOLUTION: A reference mark imaging method includes the steps of: executing a first imaging operation in which reference marks including two reference marks that are disposed at different positions in a first direction among N pieces of reference marks, and being less than the N pieces are imaged by an imaging part; and executing a second imaging operation in which reference marks including two reference marks that are disposed at different positions in a second direction being orthogonal to the first direction, among the N pieces of reference marks and being less than the N pieces are imaged by the imaging part. A deformation amount of a first drive part that drives a head unit in the first direction with the passage of time is greater than a deformation amount of a second drive part that drives the head unit in the second direction, with the passage of time. The first imaging operation is executed in a higher frequency than a frequency in which the second imaging operation is executed.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a reference mark fixed to a base of a component mounting machine for mounting a component by a head unit that can move above the substrate with respect to a substrate carried by a substrate transport unit supported by the base to a work position. The present invention relates to a technique for imaging an image with an imaging unit attached to a head unit.

  2. Description of the Related Art Conventionally, a component mounter in which a head unit mounts a component supplied by a component supply unit on a substrate is known. In general, such a component mounting machine drives an X-axis ball screw with an X-axis servo motor and drives a Y-axis ball screw with a Y-axis servo motor to drive the head unit in the X and Y directions. It has a mechanism. However, since each ball screw is thermally deformed with time, it may be difficult to control the position of the head unit.

  Therefore, in Patent Document 1, the position of the head unit is corrected based on the result of imaging a plurality of reference marks fixed to the base of the component mounting machine with a camera attached to the head unit. In particular, taking into account that it takes a lot of time to image all of the plurality of reference marks at once, the position of the head unit is corrected based on the result of imaging a part of the plurality of reference marks.

JP, 2014-120724, A

  As described above, the technique of imaging a part of a plurality of reference marks has an advantage that the reference marks can be efficiently imaged. However, the deformation amount of the ball screw may vary depending on each ball screw. For this reason, for example, if the captured reference mark is not appropriate for position correction in the driving direction of the ball screw having a large deformation amount, it may be difficult to accurately correct the position of the head unit. Further, when a linear motor is used instead of the ball screw, the same problem may occur due to thermal deformation of the guide and the frame.

  The present invention has been made in view of the above problems, and provides a technique that can appropriately perform imaging of a reference mark according to the deformation amount of each driving unit that drives the head unit in different directions. Objective.

  In order to achieve the above object, the component mounter according to the present invention includes a base on which N (N is an integer of 3 or more) reference marks are fixed, and a carry-in operation for carrying a board to a predetermined work position. A substrate transport unit supported by a base that performs a carry-out operation for unloading the substrate from the work position, and a head unit that mounts components on the board while moving above the substrate held at the work position by the substrate transport unit A first drive unit that drives the head unit in the first direction, a second drive unit that drives the head unit in a second direction orthogonal to the first direction, and a reference attached with the head unit. An imaging unit that captures an image of a lower reference mark while moving above the mark, and less than N reference marks including two reference marks arranged at different positions in the first direction among the N reference marks. Composed A first imaging operation is performed in which each reference mark of the first mark group is imaged by the imaging unit, the position of the head unit is corrected based on the result of the first imaging operation, and the head unit is arranged at a different position in the second direction. Based on the result of the second imaging operation, a second imaging operation for imaging each reference mark of the second mark group including less than N reference marks including two reference marks is performed by the imaging unit. A control unit for correcting the position of the first mark group, and at least one reference mark is different between the two reference marks of the first mark group and the two reference marks of the second mark group, and the first drive The deformation amount of the unit with the passage of time is larger than the deformation amount of the second drive unit with the passage of time, and the control unit executes the first imaging operation at a frequency higher than the frequency of performing the second imaging operation.

  A fiducial mark imaging method according to the present invention includes a base for a component mounter that mounts a component with a head unit that can move above the substrate with respect to the substrate carried by the substrate transport unit supported by the base to the work position. A reference mark imaging method in which N (N is an integer of 3 or more) reference marks fixed to the image are picked up by the image pickup unit while moving the image pickup unit attached to the head unit above the reference mark. In order to achieve the object, each of the fiducial marks of the first mark group composed of less than N fiducial marks including two fiducial marks arranged at different positions in the first direction among the N fiducial marks. A step of performing a first image pickup operation for picking up an image by an image pickup unit, and N reference marks including two reference marks arranged at different positions in a second direction orthogonal to the first direction among the N reference marks A second imaging operation of imaging each reference mark of the second mark group composed of full reference marks by the imaging unit, and including two reference marks of the first mark group and the second mark group Between the two reference marks, at least one reference mark is different from each other, and the amount of deformation with time of the first drive unit that drives the head unit in the first direction drives the head unit in the second direction. The first imaging operation is executed at a frequency that is greater than the amount of deformation of the second driving unit with time and that is higher than the frequency at which the second imaging operation is performed.

  In the present invention (component mounting machine and component mounting method) configured as described above, the head unit to which the imaging unit is attached is driven in the first direction by the first driving unit, and the first driving unit by the second driving unit. Driven in a second direction orthogonal to the direction. In addition, a first imaging operation in which a reference mark of a first mark group composed of less than N reference marks including two reference marks arranged at different positions in the first direction is imaged by an imaging unit; It is possible to perform a second imaging operation in which an imaging unit images a reference mark of a second mark group including less than N reference marks including two reference marks arranged at different positions in the direction. . Here, at least one reference mark is different between the two reference marks of the first mark group and the two reference marks of the second mark group. In such a configuration, in order to correct the position of the head unit corresponding to the deformation of the first driving unit, the imaging result of the first imaging operation for imaging the reference mark of the first mark group is appropriate, while the second driving is performed. In order to correct the position of the head unit corresponding to the deformation of the part, the imaging result of the second imaging operation for imaging the reference mark of the second mark group is appropriate. On the other hand, the deformation amount with the passage of time of the first drive unit is larger than the deformation amount with the passage of time of the second drive unit. Therefore, in the present invention, the first imaging operation is executed at a frequency that is higher than the frequency at which the second imaging operation is performed. In this way, it is possible to appropriately perform imaging of the reference mark according to the deformation amount of each driving unit that drives the head unit in different directions.

  At this time, the component mounter may be configured such that at least one reference mark is common between the two reference marks of the first mark group and the two reference marks of the second mark group. good. Thus, by sharing a part of the reference marks to be imaged in the first imaging operation and the second imaging operation, the number of reference marks provided on the base can be suppressed.

  In addition, the component mounter is configured such that the two reference marks of the first mark group are arranged in parallel in the first direction, and the two reference marks of the second mark group are arranged in parallel in the second direction. May be. Accordingly, the position control of the head unit can be more accurately performed based on the imaging result in the first imaging operation, and the position control of the head unit can be more accurately performed based on the imaging result in the second imaging operation.

  Further, the component mounter may be configured such that N is 3. In such a configuration, the first imaging operation in which the two reference marks arranged at different positions in the first direction are imaged by the imaging unit, and the two reference marks arranged at different positions in the second direction are imaged. The second imaging operation for imaging by the unit can be executed. Here, between the two reference marks imaged in the first imaging operation and the two reference marks imaged in the second imaging operation, one reference mark is different from each other, and one reference mark is mutually different. Common. In such a configuration, in order to correct the position of the head unit in response to the deformation of the first drive unit, the imaging result of the first imaging operation is appropriate, while in the head unit corresponding to the deformation of the second drive unit. In order to perform position correction, the imaging result of the second imaging operation is appropriate. On the other hand, the deformation amount with the passage of time of the first drive unit is larger than the deformation amount with the passage of time of the second drive unit. Therefore, the present invention executes the first imaging operation at a frequency higher than the frequency at which the second imaging operation is performed. In this way, it is possible to appropriately perform imaging of the reference mark according to the deformation amount of each driving unit that drives the head unit in different directions.

  According to the present invention, it is possible to appropriately perform imaging of the reference mark in accordance with the deformation amount of each driving unit that drives the head unit in different directions.

The partial top view which shows typically an example of the component mounting machine which concerns on this invention. The block diagram which shows an example of the electrical constitution with which the component mounting machine of FIG. 1 is provided. The figure which shows typically an example of the amount of thermal deformation accompanying the time passage of each of an X-axis and a Y-axis ball screw. The flowchart which shows an example of position control of a head unit based on a position shift recognition process and its result. The figure which shows typically the coordinate transformation used for the position correction of a head unit.

  FIG. 1 is a partial plan view schematically showing an example of a component mounter according to the present invention. In FIG. 1, XYZ orthogonal coordinates composed of a Z direction parallel to the vertical direction and an X direction and a Y direction parallel to the horizontal direction are shown. The component mounting machine 1 includes a pair of conveyors 12 and 12 provided on a base 11. Then, the component mounting machine 1 mounts the component P on the substrate B carried into the work position Bo (the position of the substrate B in FIG. 1) from the upstream side in the X direction (substrate transport direction) by the conveyor 12 to mount the component. The substrate B that has been completed is carried out from the work position to the downstream side in the X direction by the conveyor 12.

  The component mounter 1 is provided with a pair of Y-axis rails 21, 21 extending in the Y direction, a Y-axis ball screw 22 extending in the Y direction, and a Y-axis motor My that rotationally drives the Y-axis ball screw 22, and a head support member 23 is fixed to the nut of the Y-axis ball screw 22 while being supported by the pair of Y-axis rails 21 and 21 so as to be movable in the Y direction. An X-axis ball screw 24 extending in the X direction orthogonal to the Y direction and an X-axis motor Mx that rotationally drives the X-axis ball screw 24 are attached to the head support member 23, and the head unit 3 is attached to the head support member 23. It is fixed to the nut of the X-axis ball screw 24 while being supported so as to be movable in the X direction. Therefore, the Y-axis ball screw 22 is rotated by the Y-axis motor My to move the head unit 3 in the Y direction, or the X-axis ball screw 24 is rotated by the X-axis motor Mx to move the head unit 3 in the X direction. it can.

  Two component supply units 25 are arranged in the X direction on both sides of the pair of conveyors 12 and 12 in the Y direction, and a plurality of tape feeders 26 arranged in the X direction can be attached to and detached from each component supply unit 25. It is installed. And each tape feeder 26 supplies the component P to the component pick-up position provided in each front-end | tip at the conveyor 12 side.

  The head unit 3 includes a plurality (four) of mounting heads 31 arranged in the X direction. Each mounting head 31 has a long shape extending in the Z direction (vertical direction), and can suck and hold components by a nozzle that is detachably attached to the lower end thereof. That is, the mounting head 31 moves upward from the component extraction position and sucks the component P supplied to the component extraction position by the tape feeder 26. Subsequently, the mounting head 31 mounts the component P on the substrate B by moving above the substrate B at the work position Bo and releasing the suction of the component P. In this way, the mounting head 31 performs component mounting in which the component P supplied to the component extraction position by the tape feeder 26 is extracted and mounted on the board B.

  The component mounter 1 includes two component recognition cameras 5A and 5B. Among these, the component recognition camera 5A is fixed to the base 11 facing upward between two component supply units 25 arranged in the X direction on one side in the Y direction (upper side in FIG. 1). 5B is fixed to the base 11 facing upward between the two component supply sections 25 arranged in the X direction on the other side in the Y direction (the lower side in FIG. 2). Each of the component recognition cameras 5A and 5B is used to capture an image of the component P attracted by the mounting head 31 passing therethrough.

  Further, the component mounter 1 includes a board recognition camera 6 attached to the head unit 3 facing downward. The board recognition camera 6 is movable in the X direction and the Y direction along with the head unit 3. The substrate recognition camera 6 is used not only to image a fiducial mark attached to the substrate B carried into the work position Bo, but also to image three reference marks Ra, Rb, and Rc. Used. These reference marks Ra, Rb, and Rc are used for recognizing positional deviation of the head unit 3 due to thermal deformation of the XY drive mechanism of the head unit 3. That is, on the base 11, bar-like reference marks Ra, Rb, and Rc that are erected vertically are fixed. Among these, the reference mark Ra and the reference mark Rb are arranged in parallel in the X direction with a space therebetween, and the reference mark Ra and the reference mark Rc are arranged in parallel in the Y direction with a space therebetween. Then, the board recognition camera 6 moves above the reference marks Ra, Rb, and Rc, and images the lower reference marks Ra, Rb, and Rc.

  FIG. 2 is a block diagram showing an example of an electrical configuration provided in the component mounter of FIG. The component mounter 1 includes a main control unit 100 that comprehensively controls the configuration of the entire apparatus. The main control unit 100 includes an arithmetic processing unit 110, a storage unit 120, an imaging control unit 130, and a drive control unit 140. The arithmetic processing unit 110 is a computer configured with a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The storage unit 120 is configured by an HDD (Hard Disk Drive) or the like, and includes a mounting program that defines a component mounting procedure in the component mounter 1, a program that defines the procedure of the flowchart of FIG. It is remembered.

  The imaging control unit 130 controls imaging of the component recognition cameras 5A and 5B and the board recognition camera 6 (hereinafter abbreviated as “camera” as appropriate). That is, the imaging control unit 130 outputs an imaging control signal to the cameras 5A, 5B, and 6, and the cameras 5A, 5B, and 6 image the object at a timing according to the received imaging control signal. Then, the cameras 5A, 5B, and 6 output respective captured images to the imaging control unit 130.

  As described above, the component recognition cameras 5 </ b> A and 5 </ b> B are used for imaging the component P that is picked up by the mounting head 31. That is, when the component P is picked up from the tape feeder 26, the mounting head 31 passes over the component recognition camera 5A or the component recognition camera 5B before moving upward of the substrate B. Then, the component recognition camera 5A or the component recognition camera 5B outputs a captured image obtained by capturing the component P passing above to the imaging control unit 130, and the arithmetic processing unit 110 performs the component based on the captured image acquired by the imaging control unit 130. The adsorption state of P is recognized, and whether or not the component P can be mounted is determined based on the result.

  The substrate recognition camera 6 is used to image the fiducial mark on the substrate B. That is, when the board B is carried into the component mounter 1, the board recognition camera 6 outputs a captured image obtained by capturing the fiducial mark attached to the board B to the imaging control unit 130. Then, the arithmetic processing unit 110 recognizes the position of the substrate B based on the captured image acquired by the imaging control unit 130, and corrects the positional relationship between the mounting head 31 on which the component P is mounted and the substrate B based on the result.

  Furthermore, the board recognition camera 6 is used for imaging the reference marks Ra, Rb, and Rc. That is, the board recognition camera 6 outputs to the imaging control unit 130 captured images obtained by capturing the reference marks Ra, Rb, and Rc located below while moving above the reference marks Ra, Rb, and Rc. The arithmetic processing unit 110 then performs thermal deformation of the XY drive mechanism of the head unit 3 based on the captured image acquired by the imaging control unit 130, specifically, the head associated with thermal deformation of the Y-axis ball screw 22 and the X-axis ball screw 24. Recognize the position shift of the unit 3 (position shift recognition processing). The details of the positional deviation recognition process of the head unit 3 will be described later.

  The drive controller 140 moves the head unit 3 in the X direction and the Y direction by controlling the X axis motor Mx and the Y axis motor My. Specifically, the drive control unit 140 moves the substrate recognition camera 6 above the reference marks Ra, Rb, and Rc in the positional deviation recognition process. In addition, the drive control unit 140 moves the mounting head 31 mounted on the head unit 3 between the component supply unit 25 and the board B when performing component mounting. At this time, the drive control unit 140 corrects the XY position of the head unit 3 based on the recognition result in the positional deviation recognition process.

  Further, the component mounter 1 includes a display unit 150 configured by, for example, a liquid crystal display, and an input operation unit 160 configured by, for example, a mouse or a keyboard. Therefore, the operator can confirm the state of the component mounter 1 by confirming the display on the display unit 150, and can input a command to the component mounter 1 by performing an input operation on the input operation unit 160. Incidentally, the display unit 150 and the input operation unit 160 do not need to be configured separately, and may be configured integrally by, for example, a touch panel display.

  In the component mounter 1 illustrated in FIG. 1, the arithmetic processing unit 110, the imaging control unit 130, and the drive control unit 140 cooperate to execute a positional deviation recognition process for the head unit 3. In particular, this misregistration recognition process is executed in accordance with the difference in thermal deformation amount of the X-axis ball screw 24 and the Y-axis ball screw 22 over time. Here, FIG. 3 is a diagram schematically showing an example of the amount of thermal deformation with time of each of the X-axis and Y-axis ball screws. In the figure, a straight line with “X” indicates a temporal change in the amount of thermal deformation of the X-axis ball screw 24 in the X direction, and a straight line with “Y” indicates thermal deformation of the Y-axis ball screw 22 in the Y direction. The change with time is shown. As shown in the figure, the deformation amount of the X-axis ball screw 24 with the passage of time is larger than the deformation amount of the Y-axis ball screw 22 with the passage of time, and is approximately double. This tendency is confirmed in advance, for example, when the component mounter 1 is shipped. Therefore, in the present embodiment, the positional deviation recognition process of the head unit 3 is executed in response to the difference in time change of the thermal deformation between the X-axis ball screw 24 and the Y-axis ball screw 22, and based on the result, Adjust the position.

  FIG. 4 is a flowchart showing an example of the positional deviation recognition process and the position control of the head unit based on the result. This flowchart is executed under the control of the arithmetic processing unit 110. In step S101, the count value I for counting the number of times the reference marks Ra and Rb are imaged is reset to zero. In step S <b> 102, it is determined whether the conveyors 12 and 12 carry out the substrate transport operation for unloading the mounted substrate B from the work position Bo and loading the unmounted substrate B into the work position Bo. If it is determined that the substrate transfer operation is started (“YES” in step S102), it is determined in step S103 whether the count value I matches the maximum count value Imax. In this example, the maximum count value Imax is set to “2”. At this time, the count value I (= 0) does not match the maximum count value Imax, so the process proceeds to step S104.

  In step S104, the substrate recognition camera 6 moves above the reference mark Ra to image the reference mark Ra, and then moves above the reference mark Rb to image the reference mark Rb (first imaging operation). The captured images of the reference marks Ra and Rb are output from the board recognition camera 6 to the imaging control unit 130. In step S105, the arithmetic processing unit 110 performs the reference marks Ra and Rb based on the captured images in the first imaging operation. Is recognized (first coordinate recognition operation).

  Then, the count value I is incremented (step S106), and it is determined whether or not component mounting on the board B carried into the work position Bo is started in the component mounter 1 (step S107). If it is determined that component mounting is started (“YES” in step S107), the position of the head unit 3 during execution of component mounting is corrected based on the position coordinates of the reference marks Ra and Rb recognized in step S105. (Step S108). If it is determined that the component mounting is completed (“YES” in step S109), it is determined whether the board transfer operation is started by returning to step S102, and if it is determined that the board transfer operation is started (“ YES ”), it is determined whether the count value I matches the maximum count value Imax (step S103). Thus, steps S104 to S109 are repeatedly executed until the count value I matches the maximum count value Imax. As a result, the first imaging operation (step S104) and the first coordinate recognition operation (step S105) are executed twice. The

  When the count value I matches the maximum count value Imax (“YES” in step S103), the board recognition camera 6 moves above the reference mark Ra to image the reference mark Ra, and then moves above the reference mark Rc. Then, the reference mark Rc is imaged (second imaging operation). The captured images of the reference marks Ra and Rc are output from the board recognition camera 6 to the imaging control unit 130, and in step S111, the arithmetic processing unit 110 performs the reference marks Ra and Rc based on the captured images in the second imaging operation. Is recognized (second coordinate recognition operation).

  In step S112, it is determined whether or not component mounting on the board B carried into the work position Bo is started in the component mounting machine 1, and if it is determined that component mounting is started (“YES” in step S112), in step S111. Based on the recognized position coordinates of the reference marks Ra and Rc, the position of the head unit 3 during the component mounting is corrected (step S113). If it is determined that the component mounting is completed (“YES” in step S114), the process returns to step S101, the count value I is reset to zero, and then step S102 and subsequent steps are executed again.

  As described above, in the present embodiment, the first imaging operation (step S104) in which each of the two reference marks Ra and Rb arranged at different positions in the X direction is imaged by the substrate recognition camera 6, and in the Y direction. A second imaging operation (step S110) in which each of the two reference marks Ra and Rc arranged at different positions is imaged by the substrate recognition camera 6 can be executed. In such a configuration, in order to correct the position of the head unit 3 corresponding to the deformation of the X-axis ball screw 24, the imaging result in the first imaging operation is appropriate, while the head corresponding to the deformation of the Y-axis ball screw 22 is used. In order to correct the position of the unit 3, the imaging result of the second imaging operation is appropriate. In contrast, as shown in FIG. 3, the deformation amount of the X-axis ball screw 24 with the passage of time is larger than the deformation amount of the Y-axis ball screw 22 with the passage of time. Therefore, in the present embodiment, two first imaging operations are executed for each second imaging operation, and the first imaging operation is executed more frequently than the frequency at which the second imaging operation is performed. In this way, it is possible to appropriately perform imaging of the reference marks Ra, Rb, and Rc according to the deformation amounts of the ball screws 22 and 24 that drive the head unit 3 in different directions.

  In addition, one reference mark is set between the two reference marks Ra and Rb to be imaged in the first imaging operation and the two reference marks Ra and Rc to be imaged in the second imaging operation. Ra is common. In this way, by sharing a part of the reference mark Ra to be imaged in the first imaging operation and the second imaging operation, the number of reference marks Ra, Rb, Rc provided on the base can be suppressed.

  Further, the two reference marks Ra and Rb to be imaged in the first imaging operation are arranged in parallel in the X direction, and the two reference marks Ra and Rc to be imaged in the second imaging operation are Y Line up parallel to the direction. Thereby, the position control of the head unit 3 can be more accurately performed based on the imaging result in the first imaging operation, and the position control of the head unit 3 can be more accurately performed based on the imaging result in the second imaging operation.

  Thus, in the present embodiment, the component mounting machine 1 corresponds to an example of the “component mounting machine” of the present invention, the base 11 corresponds to an example of the “base” of the present invention, and the pair of conveyors 12, 12. Corresponds to an example of the “substrate transport unit” of the present invention, the head unit 3 corresponds to an example of the “head unit” of the present invention, and the X-axis ball screw 24 corresponds to an example of the “first drive unit” of the present invention. The Y-axis ball screw 22 corresponds to an example of the “second drive unit” of the present invention, the board recognition camera 6 corresponds to an example of the “imaging unit” of the present invention, and the main control unit 100 controls the “control” of the present invention. The substrate B corresponds to an example of the “substrate” of the present invention, the work position Bo corresponds to an example of the “work position” of the present invention, and the X direction corresponds to the “first direction” of the present invention. The Y direction corresponds to an example of the “second direction” of the present invention, and the three reference marks Ra, Rb Rc corresponds to an example of “N reference marks” of the present invention (that is, N = 3), and a group composed of the reference marks Ra and Rb corresponds to an example of “first mark group” of the present invention. In addition, the reference marks Ra and Rb correspond to an example of “two reference marks” of the first mark group, and a group constituted by the reference marks Ra and Rc corresponds to an example of the “second mark group” of the present invention. In addition, the reference marks Ra and Rc correspond to an example of “two reference marks” of the second mark group, step S104 corresponds to an example of the “first imaging operation” of the present invention, and step S110 corresponds to “ This corresponds to an example of “second imaging operation”.

  Subsequently, an example of specific calculation for correcting the position of the head unit 3 based on the imaging results in the first imaging operation (step S104) and the second imaging operation (step S110) will be described. FIG. 5 is a diagram schematically showing coordinate transformation used for position correction of the head unit. FIG. 5 schematically shows how coordinate conversion is performed from the theoretical coordinate system Si to the actual coordinate system Sr. At this time, the matrix K for converting from the theoretical coordinate system Si to the actual coordinate system Sr can be expressed as follows.

  Here, the coefficient α is the scaling value of the X axis (the coordinate axis in the X direction), that is, the ratio of the unit length αr of the X axis in the coordinate system Sr to the unit length αi of the X axis in the coordinate system Si (αr / αi ) And the coefficient β is a scaling value of the Y-axis (the coordinate axis in the Y direction), that is, the ratio of the unit length βr in the Y direction in the coordinate system Sr to the unit length βi of the Y axis in the coordinate system Si (βr / Βi). The angle θ is an angle between the X axis of the coordinate system Si and the X axis of the coordinate system Sr, and the angle φ is an angle between the Y axis of the coordinate system Si and the Y axis of the coordinate system Sr.

  Thereby, the conversion from the position coordinate (x, y) in the theoretical coordinate system Si to the position coordinate (X, Y) in the actual coordinate system Sr is expressed by the following equation.

  Here, (Xoff, Yoff) is an offset value accompanying translation. These formulas 1 and 2 can be expressed by the following formula 3.

  Here, the matrix L is defined as follows.

  Then, the position coordinates of the reference marks Ra, Rb, Rc in the ideal coordinate system Si are (ax, ay), (bx, by), (cx, cy), respectively, and the reference marks Ra, Rb, Rc are actually used. Assuming that the position coordinates of the coordinate system Sr are (Ax, Ay), (Bx, By), and (Cx, Cy), the following equation is established.

  On the other hand, in the first imaging operation, only the position coordinates of the reference marks Ra and Rb aligned in parallel with the X direction are acquired. Therefore, assuming that the scale and angle in the Y direction have not changed from the previous recognition result, β = 1 and φ = 0, and other correction values may be calculated. That is, each correction value may be calculated by solving the following equations 6 and 7.

  On the other hand, in the second imaging operation, only the position coordinates of the reference marks Ra and Rc arranged in the Y direction are acquired. Therefore, assuming that the scale and angle in the X direction have not changed from the previous recognition result, α = 1 and θ = 0, and other correction values may be calculated. That is, each correction value may be calculated by solving the following equations 8 and 9.

  The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the spirit of the present invention. For example, the arrangement relationship of the reference marks Ra, Rb, and Rc is not limited to the above example. For example, the reference marks Ra and Rb may be arranged inclined with respect to the X direction, and the reference marks Ra and Rc may be arranged in the Y direction. You may incline and arrange | position.

  In the above embodiment, three reference marks Ra, Rb, and Rc are provided (that is, N = 3). However, the number of reference marks is not limited to three, and may be, for example, four or more (that is, N ≧ 4).

  In addition, the reference mark is imaged in response to the start of the substrate transfer operation. However, the trigger for capturing the reference mark is not limited to this. Accordingly, for example, the reference mark may be imaged when a predetermined time elapses. Specifically, in step S102 of the flowchart of FIG. 4, instead of determining the start of the substrate transfer operation, it is determined whether a predetermined time has elapsed since the previous reference mark was imaged, and if the predetermined time has elapsed. It is good to comprise so that it may progress to step S103.

  The execution frequency of the first imaging operation is twice the execution frequency of the second imaging operation. However, the ratio of these execution frequencies may be set as appropriate according to the amount of change of the X-axis ball screw 24 over time and the amount of change of the Y-axis ball screw 22 over time, and is not limited to twice.

  Further, the case has been described where the amount of change with time of the X-axis ball screw 24 is larger than the amount of change of Y-axis ball screw 22 with time. However, the present invention is naturally applicable even when the amount of change of the Y-axis ball screw 22 over time is larger than the amount of change of the X-axis ball screw 24 over time. In this case, the Y-axis ball screw 22 corresponds to an example of the “first drive unit” of the present invention, the X-axis ball screw 24 corresponds to an example of the “second drive unit” of the present invention, and the Y direction corresponds to the present invention. The X direction corresponds to an example of the “first direction”, the X direction corresponds to an example of the “second direction” of the present invention, and the operation of imaging the reference marks Ra and Rc is an example of the “first imaging operation” of the present invention. The operation for imaging the reference marks Ra and Rb corresponds to an example of the “second imaging operation” of the present invention.

  Further, the specific XY driving mechanism for driving the head unit 3 is not limited to the one configured with the ball screw, and may be configured with, for example, a linear motor.

  DESCRIPTION OF SYMBOLS 1 ... Component mounting machine, 11 ... Base, 12 ... Conveyor (board | substrate conveyance part), 22 ... Y-axis ball screw (2nd drive part), 24 ... X-axis ball screw (1st drive part), 3 ... Head unit, 6 ... substrate recognition camera (imaging unit), 100 ... main control unit (control unit), B ... substrate, Bo ... work position, X ... X direction (first direction), Y ... Y direction (second direction), Ra, Rb, Rc ... Reference mark

Claims (5)

A base on which N reference marks (N is an integer of 3 or more) are fixed;
A substrate transport unit supported by the base, which performs a carry-in operation for carrying a substrate into a predetermined work position and a carry-out operation for carrying out the substrate from the work position;
A head unit for mounting components on the substrate while moving above the substrate held at the working position by the substrate transport unit;
A first drive unit for driving the head unit in a first direction;
A second drive unit that drives the head unit in a second direction orthogonal to the first direction;
An imaging unit that is attached to the head unit and images the lower reference mark while moving upward with respect to the reference mark along with the head unit;
Among the N reference marks, each reference mark of the first mark group including less than N reference marks including two reference marks arranged at different positions in the first direction is obtained by the imaging unit. A first imaging operation for imaging is performed, the position of the head unit is corrected based on the result of the first imaging operation, and N including two reference marks arranged at different positions in the second direction Control for correcting the position of the head unit based on the result of the second imaging operation by executing a second imaging operation for imaging each reference mark of the second mark group composed of less than reference marks by the imaging unit With
At least one reference mark is different between the two reference marks of the first mark group and the two reference marks of the second mark group,
The amount of deformation with time of the first drive unit is larger than the amount of deformation with time of the second drive unit,
The control unit is a component mounter that executes the first imaging operation at a frequency higher than the frequency of performing the second imaging operation.   2. The component mounting machine according to claim 1, wherein at least one reference mark is common between the two reference marks of the first mark group and the two reference marks of the second mark group.   The two reference marks of the first mark group are arranged in parallel with the first direction, and the two reference marks of the second mark group are arranged in parallel with the second direction. The component mounting machine described in 1.   The component mounter according to any one of claims 1 to 3, wherein N is three. N substrates (N) fixed to the base of the component mounter for mounting components by a head unit movable above the substrate with respect to the substrate carried by the substrate transport unit supported by the base to the work position. Is a reference mark imaging method in which an imaging unit attached to the head unit is imaged by the imaging unit while moving the imaging unit attached to the head unit,
Of the N reference marks, each reference mark of the first mark group including less than N reference marks including two reference marks arranged at different positions in the first direction is imaged by the imaging unit. Performing a first imaging operation,
Among the N reference marks, each reference of the second mark group including less than N reference marks including two reference marks arranged at different positions in the second direction orthogonal to the first direction. Performing a second imaging operation of imaging a mark by the imaging unit,
At least one reference mark is different between the two reference marks of the first mark group and the two reference marks of the second mark group,
The amount of deformation of the first driving unit that drives the head unit in the first direction is larger than the amount of deformation of the second driving unit that drives the head unit in the second direction.
A reference mark imaging method for executing the first imaging operation at a frequency higher than the frequency of performing the second imaging operation.

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