Component mounting machine and mounting shaft driving method
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Filing Date
- 2024-02-20
- Publication Date
- 2025-08-28
Abstract
Description
Component mounter and mounting shaft drive method
[0001] The present invention relates to a technique for accurately controlling the amount of drive of a mounting shaft having a nozzle attached to the lower end thereof.
[0002] As shown in Patent Documents 1 to 3, there is known a component mounter that uses a nozzle attached to the lower end of a mounting shaft to pick up a component and mount it on a board. In this component mounter, the mounting shaft positions the nozzle facing the component, and then a drive unit such as a motor lowers the mounting shaft, bringing the nozzle into contact with the component and holding the component on the nozzle. Furthermore, the mounting shaft positions the component to be picked up by the nozzle facing the board, and then the drive unit lowers the mounting shaft to place the component on the board. In this way, various operations are performed by driving the mounting shaft downward. In some cases, depending on the operation, an inappropriate drive amount of the mounting shaft can result in the operation failing.
[0003] JP 2007-157848 A JP 2007-123807 A WO2022 / 158076A1
[0004] However, when the length of the mounting shaft fluctuates due to heat generated during the operation of the mounter, the height of the nozzle attached to the mounting shaft also fluctuates, which results in a change in the appropriate drive amount required to perform the operation, making it difficult to drive the mounting shaft at the appropriate drive amount.
[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to make it possible to drive a mounting shaft with an appropriate driving amount according to variations in the length of the mounting shaft.
[0006] The component mounter according to the present invention includes a board holding unit that holds a board, a component supply unit that supplies components to a component supply position, a touch sensor, a camera that captures an image of an imaging range, a mounting shaft that performs component mounting by picking up components supplied to the component supply position with a nozzle attached to the bottom end and placing them on a board, a drive unit that drives the mounting shaft in a vertical direction, a drive amount output unit that outputs a drive amount of the mounting shaft in the vertical direction by the drive unit, and a reference drive amount acquisition unit that acquires a reference drive amount that is a drive amount output by the drive amount output unit when the nozzle is lowered toward the touch sensor by the drive unit and the touch sensor detects contact of the nozzle with the touch sensor. a first image acquisition unit that acquires a first image by using a drive unit to position the nozzle within an imaging range and having the camera capture an image of the nozzle; a second image acquisition unit that acquires a second image after the first image is acquired by using the drive unit to position the nozzle within the imaging range and having the camera capture an image of the nozzle; and a drive amount calculation unit that calculates a drive amount of the mounting shaft to position the mounting shaft at a target height based on the displacement of the nozzle height indicated by the first image and the second image and a reference drive amount, and the drive unit positions the nozzle at the target height by driving the mounting shaft by the drive amount calculated by the drive amount calculation unit.
[0007] a step of lowering a nozzle attached to the lower end of the mounting shaft toward a touch sensor by a drive unit; a step of detecting contact of the nozzle with the touch sensor by the touch sensor; a step of acquiring a reference drive amount, which is a drive amount output by a drive amount output unit that outputs a drive amount of the mounting shaft in the vertical direction by the drive unit, when the touch sensor detects contact of the nozzle; a step of acquiring a first image by positioning the nozzle within an imaging range of a camera by the drive unit and having the camera capture an image of the nozzle after acquiring the first image; a step of calculating a drive amount of the mounting shaft for positioning the nozzle at a target height based on the displacement of the nozzle height indicated by the first image and the second image and the reference drive amount; and a step of positioning the nozzle at the target height by driving the mounting shaft by the calculated drive amount.
[0008] In the component mounter and mounting shaft driving method configured as described above, a touch sensor is provided, and a drive unit drives the mounting shaft to lower a nozzle attached to the lower end of the mounting shaft toward the touch sensor. When the touch sensor detects contact of the nozzle with the touch sensor, the drive unit's vertical drive amount for the mounting shaft is acquired as a reference drive amount. This acquires a reference drive amount related to the drive amount required to lower the nozzle to the touch sensor. The drive unit also positions the nozzle within the camera's imaging range and causes the camera to capture an image of the nozzle, thereby acquiring a first image. After acquiring the first image, the drive unit also positions the nozzle within the imaging range and causes the camera to capture an image of the nozzle, thereby acquiring a second image. These first and second images indicate a change in the nozzle height from the time the first image was captured to the time the second image was captured. The drive amount for the mounting shaft required to lower the nozzle to a target height is calculated based on the change in the nozzle height indicated by the first and second images and the reference drive amount. This makes it possible to drive the mounting shaft with an appropriate drive amount corresponding to variations in the length of the mounting shaft.
[0009] The component mounter may also be configured such that the board holding unit holds the board at the board holding height, the touch sensor is positioned at a height that has a predetermined positional relationship with the board holding height, the target height is the height of the upper surface of a component to be mounted on the board held at the board holding height, the drive amount calculation unit calculates a mounting drive amount, which is a drive amount of the mounting shaft for lowering the nozzle holding the component toward the target height to place the component on the board, based on the displacement of the nozzle height shown in the first image and the second image and the reference drive amount, and the drive unit drives the mounting shaft by the mounting drive amount to place the component held by the nozzle on the board. In this configuration, the touch sensor is positioned at a height that has a predetermined positional relationship with the board holding height at which the board is held. Then, when the drive unit lowers the nozzle attached to the lower end of the mounting shaft and the touch sensor detects contact of the nozzle with the touch sensor, the drive amount of the mounting shaft in the vertical direction by the drive unit is acquired as the reference drive amount. This acquires the reference drive amount related to the drive amount for lowering the nozzle to the board at the board holding height. Furthermore, a first image is acquired by positioning the nozzle within the imaging range of the camera using the drive unit and causing the camera to capture an image of the nozzle. After the first image is acquired, a second image is acquired by positioning the nozzle within the imaging range using the drive unit and causing the camera to capture an image of the nozzle. These first and second images indicate the change in nozzle height from the time the first image was captured to the time the second image was captured. Based on the change in nozzle height indicated by the first and second images and the reference drive amount, a drive amount (mounting drive amount) of the mounting shaft for lowering the nozzle to place a component on the board is calculated. This makes it possible to drive the mounting shaft with an appropriate drive amount according to the variation in the length of the mounting shaft.
[0010] The component mounter may also be configured such that the touch sensor is disposed at a height that has a predetermined positional relationship with the component supply position, the target height being the height of the upper surface of a component being supplied to the component supply position, the drive amount calculation unit calculates a suction drive amount, which is a drive amount of the mounting shaft for lowering the nozzle facing the component at the component supply position to the target height in order to pick up the component at the component supply position, based on the displacement of the nozzle height shown in the first image and the second image and the reference drive amount, and the drive unit drives the mounting shaft by the suction drive amount so that the nozzle contacts the component at the component supply position and picks up the component. In this configuration, the touch sensor is disposed at a height that has a predetermined positional relationship with the component supply position. Then, when the drive unit lowers the nozzle attached to the lower end of the mounting shaft and the touch sensor detects contact of the nozzle with the touch sensor, the drive amount of the mounting shaft in the vertical direction by the drive unit is acquired as the reference drive amount. This acquires the reference drive amount related to the drive amount for lowering the nozzle to the component supply position. The drive unit also positions the nozzle within the imaging range of the camera and causes the camera to capture the nozzle, thereby acquiring the first image. Furthermore, after the first image is acquired, the drive unit positions the nozzle within the imaging range and causes the camera to capture an image of the nozzle, thereby acquiring a second image. These first and second images indicate the change in nozzle height from the time the first image was captured to the time the second image was captured. Then, based on the change in nozzle height indicated by the first and second images and the reference drive amount, the drive amount (suction drive amount) of the mounting shaft for lowering the nozzle to pick up a component at the component supply position is calculated. This makes it possible to drive the mounting shaft with an appropriate drive amount according to the change in the length of the mounting shaft.
[0011] The mounter may also be configured such that the second image acquisition unit acquires the second image during a period in which the mounting shaft moves to remove the component from the component supply position after mounting the component on the board. In this configuration, the second image can be acquired efficiently by utilizing the period in which the mounting shaft moves to remove the component.
[0012] The mounter may also be configured so that the board holding unit carries a board carried in from outside to a predetermined board holding position, the mounting shaft starts mounting components on the board carried in the board holding position, and the reference drive amount acquisition unit acquires the reference drive amount before the mounting shaft starts mounting components. With this configuration, the mounting shaft can be driven based on an appropriate reference drive amount for component mounting that is started thereafter.
[0013] The mounter may also be configured so that the reference drive amount acquisition unit acquires the reference drive amount after the nozzle attached to the mounting shaft has been replaced and before the mounting shaft starts component mounting. With this configuration, the mounting shaft can be driven based on an appropriate reference drive amount for component mounting that is started thereafter.
[0014] The mounter may further include a storage unit that stores displacement amount relationship information indicating the relationship between the nozzle height displacement amount shown in the first image and the second image and the nozzle height displacement amount at the target height, and the drive amount calculation unit calculates the nozzle height displacement amount at the target height based on the nozzle height displacement amount shown in the first image and the second image and the displacement amount relationship information, and calculates the drive amount based on the nozzle height displacement amount at the target height and the reference drive amount. With this configuration, the reference drive amount can be appropriately calculated even when the effect of deformation of the mounting shaft is height-dependent. As a result, it is possible to drive the mounting shaft with an appropriate drive amount according to fluctuations in the length of the mounting shaft.
[0015] The component mounter may also be configured so that the imaging range is provided above the touch sensor, the drive unit raises the nozzle that has contacted the touch sensor to the imaging range so that the reference drive amount acquisition unit can acquire the reference drive amount, and the first image acquisition unit acquires the first image by having the camera capture an image of the nozzle that has risen from the touch sensor to the imaging range. With this configuration, the first image can be acquired using a mounting shaft whose length has remained almost unchanged since the reference drive amount was acquired. As a result, the mounting shaft can be driven during component mounting based on an appropriate reference drive amount.
[0016] The component mounter may also be configured so that the imaging range is provided above the touch sensor, the drive unit lowers the nozzle located within the imaging range to the touch sensor for the first image acquisition unit to capture the first image, and the reference drive amount acquisition unit acquires the reference drive amount by detecting contact of the nozzle descending from the imaging range with the touch sensor. With this configuration, the first image can be acquired using a mounting shaft whose length has remained almost unchanged since the acquisition of the reference drive amount. As a result, the mounting shaft can be driven during component mounting based on an appropriate reference drive amount.
[0017] According to the present invention, it is possible to drive the mounting shaft with an appropriate drive amount according to variations in the length of the mounting shaft.
[0018] 8 is a partial plan view schematically showing an example of a component mounter according to the present invention. FIG. 1 is a block diagram showing an example of the electrical configuration of the component mounter of FIG. 1. FIG. 2 is a diagram schematically showing an operation in component mounting performed by the component mounter. FIG. 3 is a diagram schematically illustrating a driving mode of a mounting shaft by a Z motor. FIG. 4 is a flowchart showing an example of pre-production processing performed by the component mounter. FIG. 5 is a flowchart showing an example of reference drive distance measurement performed in the pre-production processing of FIG. 5. FIG. 6 is a flowchart showing an example of nozzle height measurement performed in the pre-production processing of FIG. 5. FIG. 7 is a flowchart showing an example of board production performed by the component mounter. FIG. 8 is a flowchart showing a determination of whether measurement of the reference drive distance is required in board production of FIG. 9. FIG. 9 is a schematic diagram for explaining calculations performed in calculating the suction drive distance and the mounting drive distance. FIG. 10 is a diagram showing a graph schematically showing the correlation between the amount of displacement caused in a nozzle located within the imaging range due to thermal deformation of the mounting shaft and the amount of displacement caused in a nozzle located at the suction target height. FIG. 11 is a diagram showing the correlation between the amount of displacement caused in a nozzle located within the imaging range due to thermal deformation of the mounting shaft and the amount of displacement caused in a nozzle located at the mounting target height.
[0019] Fig. 1 is a partial plan view showing an example of a component mounter according to the present invention, Fig. 2 is a block diagram showing an example of the electrical configuration of the component mounter of Fig. 1, and Fig. 3 is a diagram showing an example of the component mounting operation performed by the component mounter. In this embodiment, the X direction, which is the horizontal direction, the Y direction, which is the horizontal direction perpendicular to the X direction, and the Z direction, which is the vertical direction are appropriately shown.
[0020] As shown in FIG. 2 , the mounter 1 includes a control unit 9 that controls the mounter 1. The control unit 9 includes a calculation processing unit 91, a memory unit 92, a drive control unit 93, an imaging control unit 94, and a sensor control unit 95. The calculation processing unit 91 is a processor such as a central processing unit (CPU) that performs calculation functions in the mounter 1, and the memory unit 92 is a storage device such as a solid-state drive (SSD) or hard disk drive (HDD). The memory unit 92 stores a reference drive distance Dt, a reference nozzle height ht, and a displacement nozzle height hd, which will be described later. The drive control unit 93 controls a drive system provided in the mounter 1 in response to commands from the calculation processing unit 91. The imaging control unit 94 controls an imaging system provided in the mounter 1 in response to commands from the calculation processing unit 91. The sensor control unit 95 acquires the output of a sensor provided in the mounter 1 and transmits the output to the calculation processing unit 91.
[0021] The component mounter 1 includes a base 11 that is substantially rectangular in plan view, and a board transport unit 2 attached to the base 11. The board transport unit 2 has a pair of conveyors 21 arranged parallel to the X direction, and transports a board B in the X direction (board transport direction) using the pair of conveyors 21. Specifically, the board transport unit 2 transports the board B from the upstream side in the X direction in response to a carry-in command from the drive control unit 93, and holds the board B at a predetermined board holding position A (the position of the board B in FIG. 1 ). Furthermore, the board transport unit 2 transports the board B, on which components E have been mounted at the board holding position A, from the board holding position A to the downstream side in the X direction in response to a carry-out command from the drive control unit 93.
[0022] The mounter 1 includes two mounting heads 3. Each mounting head 3 is an inline-type mounting head with multiple mounting shafts 31 aligned in the X direction. Each mounting shaft 31 extends in the Z direction, and a suction nozzle 32 ( FIG. 3 ) is detachably attached to the lower end of each mounting shaft 31. The mounter 1 also includes a Z motor 47 attached to the mounting head 3. The Z motor 47 is provided for each of the multiple mounting shafts 31 of the mounting head 3 and drives the corresponding mounting shaft 31 in the Z direction. In other words, the mounting head 3 can individually raise and lower each mounting shaft 31 using the Z motor 47. The Z motor 47 has a built-in Z encoder and outputs a drive distance D by which the mounting shaft 31 is driven in the Z direction to the drive control unit 93. The mounting head 3 places a component E picked up by the suction nozzle 32 on a board B, thereby mounting the component E on the board B. The specific type of the mounting head 3 is not limited to the inline type, but may be a rotary type in which a plurality of mounting shafts 31 are arranged circumferentially.
[0023] The component mounter 1 also includes an XY drive mechanism 4 that drives each of the two mounting heads 3 individually in the X and Y directions. The XY drive mechanism 4 has two X beams 41, one for each of the two mounting heads 3. Each X beam 41 extends parallel to the X direction and supports the corresponding mounting head 3 movably in the X direction. A ball screw 42 extending parallel to the X direction and an X motor 43 that rotates and drives the ball screw 42 are attached to the X beam 41. In this example, the X motor 43 is a servo motor. The mounting heads 3 are attached to the nuts of the ball screws 42 of the X beam 41. The XY drive mechanism 4 also includes a pair of Y beams 44 that extend parallel to the Y direction. Both ends of each X beam 41 are supported by a pair of Y motors 45 that allow movement in the Y direction. A Y motor 45 that drives the X beam 41 in the Y direction is attached to each Y beam 44. Each Y motor 45 is a linear motor in this example, and has a mover 451 attached to both ends of the X beam 41 and a stator 452 extending parallel to the Y direction. The X beam 41 is driven in the Y direction together with the mover 451 by the magnetic force acting between the mover 451 and the stator 452. With this XY drive mechanism 4, the mounting head 3 can be moved in the X and Y directions by the X motor 43 and Y motor 45.
[0024] Furthermore, the component mounter 1 is equipped with two component supply units 5 arranged on either side of the board transport unit 2 in the Y direction. A plurality of tape feeders 51 aligned in the X direction are detachably attached to each component supply unit 5. Each tape feeder 51 intermittently feeds out in the Y direction a tape that stores small pieces of components E (chip components) such as integrated circuits, transistors, and capacitors at predetermined intervals, thereby supplying the components E on the tape to the component supply position Ls.
[0025] The mounting head 3 then performs component mounting by removing the component E supplied to the component supply position Ls by the tape feeder 51 from the component supply position Ls and placing it on the board B held at the board holding position A. That is, the drive control unit 93 drives the mounting head 3 using the XY drive mechanism 4 to cause the suction nozzle 32 attached to the lower end of the mounting shaft 31 of the mounting head 3 to face the component E supplied to the component supply position Ls from above (step S101 in FIG. 3 ). The drive control unit 93 then causes the Z motor 47 to lower the mounting shaft 31 by a predetermined suction drive distance Ds, thereby bringing the lower end 321 of the suction nozzle 32 into contact with the upper surface of the component E (step S102), and the mounting head 3 applies negative pressure to the suction hole opened at the lower end 321 of the suction nozzle 32, thereby suctioning the component E onto the suction nozzle 32. The drive control unit 93 also uses the Z motor 47 to raise the mounting shaft 31, to which the suction nozzle 32 that picks up the component E is attached, thereby removing the component E from the component supply position Ls (step S103). Next, the drive control unit 93 uses the XY drive mechanism 4 to drive the mounting head 3, so that the component E picked up by the suction nozzle 32 on the mounting shaft 31 of the mounting head 3 faces the mounting point Lm on the board B from above (step S104). The drive control unit 93 then uses the Z motor 47 to lower the mounting shaft 31 and the suction nozzle 32 by a predetermined mounting drive distance Dp, thereby bringing the component E picked up by the suction nozzle 32 into contact with the surface of the board B (step S105). The mounting head 3 then applies atmospheric pressure or positive pressure to the suction hole of the suction nozzle 32, thereby detaching the component E from the suction nozzle 32 and placing it on the board B. In this manner, the component E is mounted on the board B.
[0026] The component mounter 1 also includes two side-view cameras 61 corresponding to the two mounting heads 3. The side-view cameras 61 are attached to the corresponding mounting heads 3 and capture images of the suction nozzles 32 attached to the mounting heads 3 and the components E picked up by the suction nozzles 32 from the X direction to acquire side-view images Is. The acquisition of these side-view images Is is performed, for example, after the components E are picked up and before the components E are mounted on the board B. That is, the acquisition can be performed during the period from when the mounting head 3 picks up the components E from the component supply position Ls with the suction nozzles 32 to when the mounting head 3 positions the components E facing the mounting point Lm (the period from steps S103 to S104). The side-view cameras 61 capture images of the components E in response to commands from the imaging control unit 94 to acquire side-view images Is and transmit the side-view images Is to the imaging control unit 94. The arithmetic processing unit 91 recognizes the height of the components E based on the side-view images Is acquired by the imaging control unit 94. The arithmetic processing unit 91 then adjusts the mounting drive distance Dp based on the recognized height.
[0027] The component mounter 1 also includes two component recognition cameras 63 corresponding to the two mounting heads 3. The component recognition cameras 63 are attached to the base 11 facing upward and capture images of the components E from below before they are removed from the component supply position Ls by the mounting head 3 and placed on the board B, thereby acquiring component recognition images. That is, the drive control unit 93 controls the drive of the mounting head 3 by the XY drive mechanism 4 so that the components E removed from the component supply position Ls in step S103 pass through the component recognition position, which is the field of view of the component recognition camera 63, before being placed on the board B. The component recognition cameras 63 then capture images of the components E that have reached the component recognition position, acquiring component recognition images, and transmit these component recognition images to the imaging control unit 94. The arithmetic processing unit 91 recognizes the positions of the components E based on the component recognition images acquired by the imaging control unit 94. The arithmetic processing unit 91 then adjusts the positions (in the X and Y directions) of the components E when placing them at the mounting points Lm, based on the recognized positions.
[0028] Furthermore, the component mounter 1 is equipped with two touch sensors 65 provided corresponding to the two mounting heads 3. The touch sensor 65 has a horizontally disposed detection surface 651, and when it detects contact of an object with the detection surface 651, it outputs a detection signal to the sensor control unit 95. The arithmetic processing unit 91 confirms that the object has contacted the detection surface 651 of the touch sensor 65 based on the detection signal acquired by the sensor control unit 95. The height of the detection surface 651 matches the height of the surface of the board B held at the board holding position A by the board transport unit 2. The difference between the height of the detection surface 651 and the height of the component supply position Ls is stored in the memory unit 92.
[0029] The component mounter 1 also includes two nozzle exchangers 7 provided corresponding to the two mounting heads 3. The nozzle exchangers 7 exchange the suction nozzles 32 attached to the lower ends of the mounting shafts 31 that access the nozzle exchangers 7.
[0030] 4 is a diagram illustrating a schematic example of a driving mode of the mounting shaft by the Z motor. Since driving is performed in the same manner for multiple mounting shafts 31, the following explanation will be given using one mounting shaft 31 as a representative. The "Home Standby" column shows a state in which the mounting shaft 31 is waiting at the home position, and the driving distance D of the mounting shaft 31 by the Z motor 47 is a distance Dh (= 0).
[0031] The "Side-view imaging" column shows a state in which the suction nozzle 32 is imaged from the X direction by the side-view camera 61, and the drive distance D of the mounting shaft 31 driven by the Z motor 47 is the imaging drive distance Di. In other words, the drive control unit 93 outputs an imaging drive command Ci to the Z motor 47 to drive the mounting shaft 31 downward in the Z direction by the imaging drive distance Di, and the Z motor 47 drives the mounting shaft 31 downward in the Z direction by the imaging drive distance Di in accordance with this imaging drive command Ci. As a result, the suction nozzle 32 (particularly the lower end 321 of the suction nozzle 32) is positioned within the imaging range R61, which is the field of view of the side-view camera 61, and the side-view camera 61 captures an image of the imaging range R61, thereby acquiring a side-view image Is of the suction nozzle 32.
[0032] The "contact detection" column shows a state in which the lower end 321 of the suction nozzle 32 comes into contact with the detection surface 651 of the touch sensor 65, causing the touch sensor 65 to detect the contact of the suction nozzle 32 with the detection surface 651, and the drive distance D of the mounting shaft 31 by the Z motor 47 is the reference drive distance Dt. Note that the detection surface 651 of the touch sensor 65 is located below the imaging range R61, and the reference drive distance Dt is longer than the imaging drive distance Di.
[0033] The "Component Placement" column shows the state in which component E, which is sucked onto lower end 321 of suction nozzle 32, is in contact with surface Bs of board B (the state in step S105), and the driving distance D of mounting shaft 31 by Z motor 47 is mounting driving distance Dp. As shown in FIG. 4 , board holding height hb, which is the height of surface Bs of board B held at board holding position A by board transport unit 2, matches the height of detection surface 651 of touch sensor 65.
[0034] The "Component Suction" column shows the state in which the lower end 321 of the suction nozzle 32 is in contact with the surface of the component E supplied to the component supply position Ls (the state in step S102), and the driving distance D of the mounting shaft 31 by the Z motor 47 is the suction driving distance Ds. As described above, the supply height correction amount hlb (=hl-hb), which is the difference between the component supply height hl, which is the height of the component supply position Ls, and the board holding height hb, which corresponds to the height of the detection surface 651 of the touch sensor 65, is stored in the memory unit 92.
[0035] Fig. 5 is a flowchart showing an example of pre-production processing executed by a component mounter, Fig. 6 is a flowchart showing an example of reference drive distance measurement executed in the pre-production processing of Fig. 5, and Fig. 7 is a flowchart showing an example of nozzle height measurement executed in the pre-production processing of Fig. 5. The flowcharts of Fig. 5, Fig. 6 and Fig. 7 are executed under the control of the calculation processing unit 91.
[0036] The pre-production processing in FIG. 5 is performed before board production ( FIG. 8 ), in which components E are mounted on board B to produce a component-mounted board. In step S201, the processing unit 91 checks whether the touch flag is on. Here, the touch flag is a flag that indicates whether measurement of the reference drive distance Dt ( FIG. 6 ) for bringing the suction nozzle 32 into contact with the touch sensor 65 has been performed. If the touch flag is off ("NO" in step S201), steps S203 to S206 are performed.
[0037] 6 is measured. This reference drive distance measurement is performed for all mounting shafts 31 provided in the mounter 1. However, since the details of the reference drive distance measurement are common to all mounting shafts 31, the process will be described representatively for one mounting shaft 31. In step S301, the arithmetic processing unit 91 controls the X motor 43 and the Y motor 45 using the drive control unit 93 to position the suction nozzle 32 attached to the lower end of the mounting shaft 31 facing the detection surface 651 of the touch sensor 65 from above with a gap therebetween. In step S302, the arithmetic processing unit 91 controls the Z motor 47 using the drive control unit 93 to lower the mounting shaft 31, thereby lowering the suction nozzle 32 attached to the mounting shaft 31 toward the detection surface 651. Then, when the lower end 321 of the suction nozzle 32 comes into contact with the detection surface 651 and the sensor control unit 95 receives a detection signal from the touch sensor 65 ("YES" in step S303), the calculation processing unit 91 controls the Z motor 47 via the drive control unit 93 to stop the Z motor 47 from lowering the mounting shaft 31 (step S304). That is, the state shown in the "contact detection" column in Fig. 4 is reached. In the following step S305, the calculation processing unit 91 acquires, via the drive control unit 93, the drive distance D output by the Z-axis encoder of the Z motor 47 as the reference drive distance Dt.
[0038] When the reference drive distance measurement in step S203 (FIG. 5) is completed in this manner, the calculation processing unit 91 turns on the touch flag (step S204), and then the nozzle height measurement is carried out (step S205).
[0039] In step S205, the nozzle height measurement shown in FIG. 7 is performed. This nozzle height measurement is performed for all mounting shafts 31 equipped in the mounter 1. However, since the nozzle height measurement is common to all mounting shafts 31, the process will be described for one mounting shaft 31. In step S401, the calculation processing unit 91 outputs an imaging drive command Ci from the drive control unit 93 to the Z motor 47, and the Z motor 47 drives the mounting shaft 31 downward in the Z direction by an imaging drive distance Di. This positions the suction nozzle 32 within the imaging range R61 (see the "Side-view imaging" section in FIG. 4). In step S402, the calculation processing unit 91 controls the imaging control unit 94 to cause the side-view camera 61 to capture an image of the imaging range R61 and acquire a side-view image Is of the suction nozzle 32. In step S403, the calculation processing unit 91 performs image processing on the side-view image Is acquired in step S402, and acquires the height of the suction nozzle 32 (particularly the lower end 321) shown in the side-view image Is as the reference nozzle height ht.
[0040] When the nozzle height measurement in step S205 (FIG. 5) is completed in this manner, the calculation processing unit 91 stores the measurement result in step S203 (reference driving distance Dt) and the measurement result in step S206 (reference nozzle height ht) in the storage unit 92 (step S206).Then, the pre-production processing is completed.
[0041] On the other hand, if it is confirmed in step S201 that the touch flag is on (if "YES"), the calculation processing unit 91 checks whether a predetermined periodic execution interval has elapsed since the previous reference driving distance measurement in step S203 (step S202). If the periodic execution interval has elapsed (if "YES" in step S202), steps S203 to S206 are executed as described above. On the other hand, if the periodic execution interval has not elapsed (if "NO" in step S202), the pre-production processing ends.
[0042] Fig. 8 is a flowchart showing an example of board production executed by a component mounter, and Fig. 9 is a flowchart showing the determination of whether or not measurement of the reference drive distance is required, which is executed in the board production of Fig. 8. The flowcharts of Fig. 8 and Fig. 9 are executed under the control of the calculation processing unit 91.
[0043] In step S501, the calculation processing unit 91 checks whether the touch flag is on. If the touch flag is off ("NO" in step S501), the calculation processing unit 91 measures the reference drive distance (step S502), turns on the touch flag (step S503), measures the nozzle height (step S504), and saves the measurement result (step S505) in the same manner as in steps S203, S204, S205, and S206 described above.
[0044] If the touch flag is on (if "YES" in step S501), steps S506 to S512 are executed. Note that steps S508 to S512 are executed for all mounting shafts 31 equipped in the component mounter 1, but since the contents of steps S506 to S512 are common to each mounting shaft 31, the following explanation will be given for one mounting shaft 31 as a representative.
[0045] In step S506, the calculation processing unit 91 calculates the suction drive distance Ds. That is, the thickness Ed (in other words, the height) of the component E to be supplied to each component supply position Ls is stored in advance in the memory unit 92. Therefore, the calculation processing unit 91 calculates the suction drive distance Ds by subtracting the thickness Ed and the supply height correction amount hlb from the reference drive distance Dt. In step S507, the calculation processing unit 91 controls the Z motor 47 via the drive control unit 93 to lower the mounting shaft 31 by the suction drive distance Ds. This brings the lower end 321 of the suction nozzle 32 into contact with the surface of the component E at the component supply position Ls. Then, in step S508, the calculation processing unit 91 causes the suction nozzle 32 to pick up the component E at the component supply position Ls.
[0046] In step S509, the calculation processing unit 91 calculates the mounting drive distance Dp. That is, as described above, when component E is removed from component supply position Ls, a side-view image Is of that component E is acquired. The calculation processing unit 91 then calculates the thickness Ed (in other words, the height) of component E from this side-view image Is, and calculates the distance obtained by subtracting the thickness Ed from the reference drive distance Dt as the mounting drive distance Dp. In step S510, the calculation processing unit 91 controls the Z motor 47 via the drive control unit 93 to lower the mounting shaft 31 by the mounting drive distance Dp. As a result, component E is placed and mounted on the front surface Bs of the board B (the "Component Placement" column in FIG. 4).
[0047] In step S511, it is determined whether or not measurement of the reference driving distance Dt is necessary (FIG. 9). That is, as shown in FIG. 9, it is confirmed whether a predetermined periodic execution interval has elapsed since the previous measurement of the reference driving distance Dt (step S601). If the periodic execution interval has elapsed (YES in step S601), a determination result indicating that measurement is necessary (YES) is returned.
[0048] On the other hand, if the regular execution interval has not elapsed ("NO" in step S601), the calculation processing unit 91 checks (step S602) whether the suction nozzle 32 attached to the mounting shaft 31 is scheduled to be replaced before the mounting shaft 31 next picks up a component E. If the suction nozzle 32 is scheduled to be replaced ("YES" in step S602), a determination result indicating that measurement is necessary (YES) is returned.
[0049] On the other hand, if replacement of suction nozzle 32 is not planned (NO in step S602), the nozzle height measurement shown in Fig. 7 is executed (step S603), whereby a side-view image Is is captured, and the nozzle height indicated by the side-view image Is is acquired as the displacement nozzle height hd.
[0050] In step S604, the calculation processing unit 91 determines whether the difference between the nozzle height obtained in the previous nozzle height measurement (step S205 or S504) (i.e., the reference nozzle height ht) and the nozzle height obtained in the current nozzle height measurement (step S603) (i.e., the displaced nozzle height hd) is equal to or greater than a threshold value. If a difference equal to or greater than the threshold value is confirmed (YES in step S604), a determination result indicating that measurement is necessary (YES) is returned.
[0051] On the other hand, if a difference less than the threshold value is confirmed ("NO" in step S604), the calculation processing unit 91 stores the displacement nozzle height hd measured in step S603 in the storage unit 92 (step S605), and returns a determination result that measurement is unnecessary (NO).
[0052] If it is determined in step S511 that measurement is necessary (YES), the calculation processing unit 91 turns off the touch flag in step S512 and then proceeds to step S513. On the other hand, if it is determined in step S511 that measurement is not necessary (NO), the calculation processing unit 91 proceeds to step S513 without executing step S512. In step S513, the calculation processing unit 91 determines whether to end board production. If it is determined that board production is to be ended (if "YES" in step S513), board production is ended, and if it is determined that board production is not to be ended (if "NO" in step S513), the process returns to step S501.
[0053] When the placement and mounting of component E on board B is completed in step S510, the drive control unit 93 moves the suction nozzle 32 from above to a position facing component supply position Ls in order to pick up component E from component supply position Ls. In contrast, the determination of whether measurement is necessary in step S511 is performed in parallel with the period in which the suction nozzle 32 moves to pick up component E from the next component supply position Ls. Therefore, the nozzle height measurement in step S603 is performed during this period.
[0054] In step S501, the calculation processing unit 91 checks whether the touch flag is on. If the measurement necessity determination in step S511 is determined to be "YES" and the touch flag is turned off in step S512, the determination in step S501 is "NO." As a result, steps S502 to S505 are executed. At this time, if it is determined in step S602 that the suction nozzle 32 is to be replaced (if "YES"), the suction nozzle 32 attached to the mounting shaft 31 is replaced by the nozzle exchanger 7, and steps S502 to S505 are executed for the replaced suction nozzle 32.
[0055] On the other hand, if the determination of whether measurement is necessary in step S511 is "NO," then the determination in step S501 is "YES." As a result, steps S506 to S510 are executed. However, in steps S506 and S509 this time, the pickup drive distance Ds and the mounting drive distance Dp are calculated using a method different from that used in steps S506 and S509 the previous time. This point will be explained using FIG. 10.
[0056] FIG. 10 is a schematic diagram illustrating the calculations performed to calculate the suction drive distance and the mounting drive distance. As shown in FIG. 10 , in step S205 or S504, a reference image Ist, which is a side-view image Is of the suction nozzle 32, is captured, and a reference nozzle height ht, which is the height of the suction nozzle 32 indicated by the reference image Ist, is obtained. In step S603, a displacement image Isd, which is a side-view image Is of the suction nozzle 32, is captured, and a displacement nozzle height hd, which is the height of the suction nozzle 32 indicated by the displacement image Isd, is obtained. As shown in FIG. 10 , a difference of a displacement amount Δ occurs between the reference nozzle height ht and the displacement nozzle height hd. This difference is primarily due to the extension of the mounting shaft 31 in the Z direction caused by heat generated by the driving of the mounting shaft 31 by the Z motor 47.
[0057] Therefore, in step S507, the calculation processing unit 91 calculates the suction drive distance Ds based on the displacement amount Δ of the height of the suction nozzle 32 indicated by the reference image Ist and the displacement image Isd and the reference drive distance Dt. For example, the suction drive distance Ds can be calculated by subtracting the displacement amount Δ, the thickness Ed of the component E, and the supply height correction amount hlb from the reference drive distance Dt. Then, the suction nozzle 32 is lowered by the suction drive distance Ds, whereby the component E is placed on the board B (step S508).
[0058] Furthermore, in step S509, the calculation processing unit 91 calculates the mounting drive distance Dp based on the displacement amount Δ of the height of the suction nozzle 32 indicated by the reference image Ist and the displacement image Isd and the reference drive distance Dt. For example, the mounting drive distance Dp can be calculated by subtracting the displacement amount Δ and the thickness Ed of the component E from the reference drive distance Dt. Then, the suction nozzle 32 is lowered by the mounting drive distance Dp, whereby the component E is placed on the board B (step S508).
[0059] In the embodiment described above, the touch sensor 65 is disposed at the same height as the board holding height hb at which the board B is held. Then, the Z motor 47 (drive unit) lowers the suction nozzle 32 attached to the lower end of the mounting shaft 31. When the touch sensor 65 detects contact of the suction nozzle 32 with the touch sensor 65 ("YES" in step S303), the drive distance D of the mounting shaft 31 in the Z direction by the Z motor 47 is acquired as a reference drive distance Dt (reference drive amount) (step S305). This acquires the reference drive distance Dt related to the drive distance D required to lower the suction nozzle 32 to the board B at the board holding height hb (in other words, the height of the touch sensor 65). Furthermore, the Z motor 47 positions the suction nozzle 32 within the imaging range R61 of the side-view camera 61 (camera), causing the side-view camera 61 to capture an image of the suction nozzle 32, thereby acquiring a reference image Ist (first image) (step S205 or S504). Furthermore, after the reference image Ist is acquired, the Z motor 47 positions the suction nozzle 32 within the imaging range R61, and the side-view camera 61 captures an image of the suction nozzle 32, thereby acquiring a displacement image Isd (second image) (step S603). The reference image Ist and the displacement image Isd indicate the displacement amount Δ of the height of the suction nozzle 32 from the time when the reference image Ist was captured to the time when the displacement image Isd was captured ( FIG. 10 ). Then, based on the displacement amount Δ of the height of the suction nozzle 32 indicated by the reference image Ist and the displacement image Isd and the reference drive distance Dt, a mounting drive distance Dp (mounting drive amount) of the mounting shaft 31 for lowering the suction nozzle 32 to place the component E on the board B is calculated (step S509). This makes it possible to drive the mounting shaft 31 at an appropriate mounting drive distance Dp according to variations in the length of the mounting shaft 31.
[0060] Furthermore, the detection surface 651 of the touch sensor 65 is positioned at a height that satisfies a predetermined positional relationship (supply height correction amount hlb) with the height of the component supply position Ls. Therefore, in step S305, a reference drive distance Dt related to the drive distance D for lowering the suction nozzle 32 to the component supply position Ls is acquired. Then, based on the height displacement amount Δ of the suction nozzle 32 indicated by the reference image Ist and the displacement image Isd, the reference drive distance Dt, and the supply height correction amount hlb, a suction drive distance Ds (suction drive amount) of the mounting shaft 31 for lowering the suction nozzle 32 to pick up the component E at the component supply position Ls is calculated (step S506). This makes it possible to drive the mounting shaft 31 at an appropriate suction drive distance Ds that corresponds to variations in the length of the mounting shaft 31.
[0061] Furthermore, the imaging control unit 94 (second image acquisition unit) acquires the displacement image Isd during the period when the mounting shaft 31 moves to remove the component E from the component supply position Ls after mounting the component E on the board B (step S603). With this configuration, the displacement image Isd can be efficiently acquired by utilizing the period when the mounting shaft 31 moves to remove the component E.
[0062] Furthermore, the board transport unit 2 (board holding unit) carries in a board B that has been carried in from outside to a predetermined board holding position A and holds it at a board holding height hb, and the mounting shaft 31 starts mounting components on the board B that has been carried in to the board holding position A. In response to this, the calculation processing unit 91 (reference drive amount acquisition unit) acquires a reference drive distance Dt before the mounting shaft 31 starts mounting components (step S203). With this configuration, the mounting shaft 31 can be driven based on an appropriate mounting drive distance Dp during subsequent component mounting (board production) (steps S509 to S510).
[0063] The calculation processing unit 91 also acquires the reference drive distance Dt after the suction nozzle 32 attached to the mounting shaft 31 has been replaced but before the mounting shaft 31 starts component mounting (step S602: YES to step S502). With this configuration, the mounting shaft 31 is driven based on the appropriate mounting drive distance Dp during subsequent component mounting. Furthermore, the measurement of the mounting drive distance Dp (step S203 or S502) is performed before the nozzle height measurement (step S205 or S504) is performed. According to this sequence, the Z motor 47 raises the suction nozzle 32 that has contacted the touch sensor 65 to the imaging range R61 to acquire the reference drive distance Dt. The imaging control unit 94 (first image acquisition unit) then causes the side-view camera 61 to capture the suction nozzle 32 that has risen from the touch sensor 65 to the imaging range R61 to acquire the reference image Ist (first image). With this configuration, the reference image Ist can be acquired using a mounting shaft 31 whose length has remained almost unchanged since the reference drive distance Dt was acquired. As a result, the mounting shaft 31 can be driven during component mounting based on an appropriate mounting drive distance Dp (steps S509 to S510).
[0064] As described above, in the embodiment described above, the board holding height hb corresponds to an example of the "board holding height" of the present invention, the board B corresponds to an example of the "board" of the present invention, the board transport unit 2 corresponds to an example of the "board holding unit" of the present invention, the touch sensor 65 corresponds to an example of the "touch sensor" of the present invention, the imaging range R61 corresponds to an example of the "imaging range" of the present invention, the side-view camera 61 corresponds to an example of the "camera" of the present invention, the component supply position Ls corresponds to an example of the "component supply position" of the present invention, the component E corresponds to an example of the "component" of the present invention, the suction nozzle 32 corresponds to an example of the "nozzle" of the present invention, the mounting shaft 31 corresponds to an example of the "mounting shaft" of the present invention, the Z direction corresponds to an example of the "vertical direction" of the present invention, the Z motor 47 corresponds to an example of the "drive unit" of the present invention, and the drive distance D corresponds to an example of the "drive amount" of the present invention. the Z motor 47 corresponds to an example of a "drive amount output unit" of the present invention, the reference drive distance Dt corresponds to an example of a "reference drive amount" of the present invention, the arithmetic processing unit 91 corresponds to an example of a "reference drive amount acquisition unit" of the present invention, the reference image Ist corresponds to an example of a "first image" of the present invention, the imaging control unit 94 corresponds to an example of a "first image acquisition unit" of the present invention, the displacement image Isd corresponds to an example of a "second image" of the present invention, the imaging control unit 94 corresponds to an example of a "second image acquisition unit" of the present invention, the suction drive distance Ds corresponds to an example of an "suction drive amount" of the present invention, the mounting drive distance Dp corresponds to an example of a "mounting drive amount" of the present invention, the arithmetic processing unit 91 corresponds to an example of a "drive amount calculation unit" of the present invention, the component mounter 1 corresponds to an example of a "component mounter" of the present invention, and the board holding position A corresponds to an example of a "board holding position" of the present invention.
[0065] The present invention is not limited to the above embodiment, and various modifications can be made to the above without departing from the spirit of the present invention. For example, the nozzle height measurement (step S205 or S504) may be performed first, followed by the measurement of the reference drive distance Dt (step S203 or S502). According to this sequence, the Z motor 47 (drive unit) lowers the suction nozzle 32 positioned in the imaging range R61 to the touch sensor 65 after the imaging control unit 94 (first image acquisition unit) acquires the reference image Ist (first image). The calculation processing unit 91 (reference drive amount acquisition unit) then acquires the reference drive distance Dt (reference drive amount) by detecting contact of the suction nozzle 32 descending from the imaging range R61 with the touch sensor 65. With this configuration, the reference image Ist can be acquired using the mounting shaft 31, whose length remains almost unchanged compared to when the reference drive distance Dt was acquired. As a result, the mounting shaft 31 can be driven during component mounting based on an appropriate mounting drive distance Dp (steps S509 to S510).
[0066] Furthermore, the specific method for calculating the mounting drive distance Dp in step S509 can be changed as appropriate. That is, the influence of thermal deformation of the mounting shaft 31 may differ between when the suction nozzle 32 is located within the imaging range R61 and when the suction nozzle 32 is located below the imaging range R61. For example, it is expected that the influence will be greater in the latter case where the drive distance D of the mounting shaft 31 is large than in the former case. Therefore, these correlations may be experimentally determined in advance and stored in the storage unit 92, and may be used to calculate the suction drive distance Ds in step S507 and the mounting drive distance Dp in step S509.
[0067] That is, in the above example, the suction drive distance Ds is calculated by using the height of the surface of the component E at the component supply position Ls as the suction target height hs ("Component Suction" in FIG. 4) at which the lower end 321 of the suction nozzle 32 is to be positioned. Furthermore, the mounting drive distance Dp is calculated by using the height of the surface of the component E placed on the board B as the mounting target height hp ("Component Placement" in FIG. 4) at which the lower end 321 of the suction nozzle 32 is to be positioned. However, due to thermal deformation of the mounting shaft 31, a discrepancy may occur between the amount of displacement of the suction nozzle 32 positioned in the imaging range R61 and the amount of displacement of the suction nozzle 32 positioned at each target height. Next, a method for dealing with such a discrepancy will be described.
[0068] 11A is a diagram schematically illustrating a graph showing the correlation between the amount of displacement caused by thermal deformation of the mounting shaft in a nozzle located within the imaging range and the amount of displacement caused by the nozzle located at the pickup target height, and FIG. 11B is a diagram schematically illustrating a graph showing the correlation between the amount of displacement caused by thermal deformation of the mounting shaft in a nozzle located within the imaging range and the amount of displacement caused by the nozzle located at the pickup target height. This correlation is experimentally measured in advance, and coefficients Fs and Fp that indicate the linear relationship between the amount of displacement Δ in the imaging range R61 and the amount of displacement Δ at the target height are stored in the memory unit 92. In other words, coefficients Fs and Fp that convert the amount of displacement Δ in the imaging range R61 into the amount of displacement Δ at the target heights hs and hp are stored. These coefficients Fs and Fp are stored for each component E having a different thickness.
[0069] Then, in step S506, the calculation processing unit 91 calculates the suction drive distance Ds based on the displacement amount Δ×Fs, which is obtained by multiplying the displacement amount Δ of the height of the suction nozzle 32 indicated by the reference image Ist and the displacement image Isd by a coefficient Fs, and the reference drive distance Dt. For example, the suction drive distance Ds can be calculated by subtracting the displacement amount Δ×Fs, the thickness Ed, and the supply height correction amount hlb from the reference drive distance Dt. Then, the suction nozzle 32 is lowered by the suction drive distance Ds, whereby the component E is picked up by the suction nozzle 32 (step S507).
[0070] In step S509, the calculation processing unit 91 calculates the mounting drive distance Dp based on the displacement amount Δ×Fp, which is obtained by multiplying the displacement amount Δ of the height of the suction nozzle 32 indicated by the reference image Ist and the displacement image Isd by a coefficient Fp, and the reference drive distance Dt. For example, the mounting drive distance Dp can be calculated by subtracting the displacement amount Δ×Fp and the thickness Ed from the reference drive distance Dt. Then, the suction nozzle 32 is lowered by the mounting drive distance Dp, whereby the component E is placed on the board B (step S510).
[0071] In this modified example, coefficients Fs and Fp (displacement amount relationship information) indicating the relationship between the displacement amount Δ of the height of the suction nozzle 32 (displacement amount on the vertical axis in FIGS. 11A and 11B ) indicated by the reference image Ist (first image) and the displacement image Isd (second image) and the displacement amount Δ of the height of the suction nozzle 32 at the target heights hs and hp (displacement amount on the horizontal axis in FIGS. 11A and 11B ) are stored in the storage unit 92. The arithmetic processing unit 91 (drive amount calculation unit) calculates the displacement amounts Δ×Fs and Δ×Fp of the height of the suction nozzle 32 at the target heights hs and hp based on the displacement amount Δ of the height of the suction nozzle 32 indicated by the reference image Ist and the displacement image Isd and the coefficients Fs and Fp, and calculates the suction drive distance Ds and the mounting drive distance Dp based on the displacement amounts Δ×Fs and Δ×Fp of the height of the suction nozzle 32 at the target heights hs and hp and the reference drive distance Dt. With this configuration, it is possible to appropriately calculate the suction drive distance Ds and the mounting drive distance Dp even if the effect of deformation of the mounting shaft 31 is height-dependent. As a result, it is possible to drive the mounting shaft 31 at an appropriate suction drive distance Ds and mounting drive distance Dp according to the variation in the length of the mounting shaft 31 (steps S506 to S507, S509 to S510).
[0072] Furthermore, the height of the detection surface 651 of the touch sensor 65 does not need to be the same as the board holding height hb, and there may be a difference between them. In this case, the mounting drive distance Dp can be calculated taking into account the difference between the height of the detection surface 651 of the touch sensor 65 and the board holding height hb (step S509).
[0073] Furthermore, the number of mounting heads 3 does not need to be two but may be one, and the number of mounting shafts 31 that the mounting head 3 has can also be changed as appropriate.
[0074] Furthermore, the reference image Ist and the displacement image Isd do not have to be captured in the horizontal direction (X direction), but may be captured in a direction tilted relative to the horizontal direction.
[0075] Furthermore, the positional relationship between the touch sensor 65 and the imaging range R61 is not limited to the example described above, and the touch sensor 65 may be disposed above the imaging range R61.
[0076] Furthermore, the correction of the drive distance D based on the displacement amount Δ indicated by the reference image Ist and the displacement image Isd does not need to be performed on both the suction drive distance Ds and the mounting drive distance Dp, but may be performed on only one of them.
[0077] REFERENCE SIGNS LIST 1...Component mounter 2...Board transport unit 31...Mounting shaft 32...Suction nozzle 47...Z motor 61...Side-view camera 65...Touch sensor 91...Calculation processing unit 94...Image capture control unit A...Board holding position B...Board D...Driving distance Dp...Mounting driving distance Ds...Suction driving distance Dt...Reference driving distance E...Component Isd...Displacement image Ist...Reference image Ls...Component supply position R61...Image capture range hb...Board holding height
Claims
a board holding unit that holds a board; a component supply unit that supplies components to a component supply position; a touch sensor; a camera that captures an image of an imaging range; a mounting shaft that performs component mounting by picking up components supplied to the component supply position with a nozzle attached to its lower end and placing the components on a board; a drive unit that drives the mounting shaft in a vertical direction; a drive amount output unit that outputs a drive amount of the mounting shaft in the vertical direction by the drive unit; a reference drive amount acquisition unit that lowers the nozzle towards the touch sensor by the drive unit and acquires a reference drive amount that is a drive amount output by the drive amount output unit when the touch sensor detects contact of the nozzle with the touch sensor; a first image acquisition unit that positions the nozzle within the imaging range by the drive unit and has the camera capture an image of the nozzle, thereby acquiring a first image; and a second image acquisition unit that, after acquiring the first image, positions the nozzle within the imaging range by the drive unit and has the camera capture an image of the nozzle, thereby acquiring a second image. a drive amount calculation unit that calculates a drive amount of the mounting shaft for positioning the mounting shaft at a target height, based on the displacement of the nozzle height indicated by the first image and the second image and the reference drive amount, wherein the drive unit positions the nozzle at the target height by driving the mounting shaft by the drive amount calculated by the drive amount calculation unit.
2. The component mounter according to claim 1, wherein the board holding unit holds the board at a board holding height, the touch sensor is positioned at a height that has a predetermined positional relationship with the board holding height, the target height is the height of an upper surface of a component to be mounted on the board held at the board holding height, the drive amount calculation unit calculates a mounting drive amount, which is the drive amount of the mounting shaft for lowering the nozzle holding a component toward the target height in order to place the component on the board, based on the displacement of the nozzle height shown in the first image and the second image and the reference drive amount, and the drive unit drives the mounting shaft by the mounting drive amount, thereby placing the component held by the nozzle on the board.
3. A component mounter as described in claim 1 or 2, wherein the touch sensor is positioned at a height that has a predetermined positional relationship with the component supply position, the target height is the height of the top surface of a component to be supplied to the component supply position, the drive amount calculation unit calculates an adsorption drive amount, which is the drive amount of the mounting shaft for lowering the nozzle facing the component at the component supply position to the target height in order to adsorb the component at the component supply position, based on the displacement in height of the nozzle shown in the first image and the second image and the reference drive amount, and the drive unit drives the mounting shaft by the adsorption drive amount, causing the nozzle to come into contact with the component at the component supply position and adsorb the component.
4. A component mounting machine as described in any one of claims 1 to 3, wherein the second image acquisition unit acquires the second image during the period when the mounting shaft moves to remove a component from the component supply position after mounting the component on the board.
5. A component mounting machine as described in any one of claims 1 to 4, wherein the board holding unit carries the board carried in from outside into a predetermined board holding position, the mounting shaft starts mounting components on the board carried in the board holding position, and the reference drive amount acquisition unit acquires the reference drive amount before the mounting shaft starts mounting components.
6. A component mounting machine as described in any one of claims 1 to 5, wherein the reference drive amount acquisition unit acquires the reference drive amount after the nozzle attached to the mounting shaft has been replaced and before the mounting shaft starts mounting components.
7. A component mounting machine as described in any one of claims 1 to 6, further comprising a memory unit that stores displacement amount relationship information that indicates the relationship between the displacement amount of the nozzle height shown in the first image and the second image and the displacement amount of the nozzle height at the target height, wherein the drive amount calculation unit calculates the displacement amount of the nozzle height at the target height based on the displacement amount of the nozzle height shown in the first image and the second image and the displacement amount relationship information, and calculates the drive amount based on the displacement amount of the nozzle height at the target height and the reference drive amount.
8. A component mounter as described in any one of claims 1 to 7, wherein the imaging range is provided above the touch sensor, the drive unit raises the nozzle that has contacted the touch sensor up to the imaging range in order for the reference drive amount acquisition unit to acquire the reference drive amount, and the first image acquisition unit causes the camera to capture an image of the nozzle that has risen from the touch sensor to the imaging range, thereby acquiring the first image.
9. A component mounter as described in any one of claims 1 to 7, wherein the imaging range is provided above the touch sensor, the drive unit lowers the nozzle located in the imaging range to the touch sensor so that the first image acquisition unit can capture the first image, and the reference drive amount acquisition unit acquires the reference drive amount by detecting contact of the nozzle that has descended from the imaging range using the touch sensor.
10. A mounting shaft drive method comprising: a step of lowering a nozzle attached to the lower end of a mounting shaft toward a touch sensor using a drive unit; a step of detecting contact of the nozzle with the touch sensor by the touch sensor; a step of obtaining a reference drive amount, which is a drive amount output by a drive amount output unit that outputs a drive amount of the mounting shaft in the vertical direction by the drive unit, when the touch sensor detects contact of the nozzle; a step of obtaining a first image by positioning the nozzle within an imaging range of a camera using the drive unit and having the camera image the nozzle; after obtaining the first image, a step of obtaining a second image by positioning the nozzle within the imaging range using the drive unit and having the camera image the nozzle; a step of calculating a drive amount of the mounting shaft for positioning the nozzle at a target height based on the displacement of the nozzle height indicated by the first image and the second image and the reference drive amount; and a step of positioning the nozzle at the target height by driving the mounting shaft by the calculated drive amount.