JP7813087B2 - Component mounting system and substrate transport control method - Google Patents

Description

This invention relates to technology for transporting substrates using multiple conveyors arranged in series.

A component mounting system is known that produces component-mounted boards by using a mounting head to mount components onto boards carried in by multiple conveyors arranged in series. In such component mounting systems, boards may be left on the conveyors before production begins or during interruptions. In such cases, the following problems can arise if a board straddles two adjacent conveyors.

In other words, a search for remaining boards can be carried out using a sensor that detects boards at the boundary between two adjacent conveyors. In this case, the board is detected by the sensor while being transported in a predetermined direction by the conveyors. However, if a board straddles two conveyors, overdetection may occur, where a sensor installed at the boundary between the two conveyors detects a board, and then a sensor installed downstream in the predetermined direction of the two conveyors detects another board.

Patent No. 6602584

In response to this issue, Patent Document 1 prevents overdetection by selectively operating odd-numbered conveyors among multiple conveyors while checking the results of sensor detection of the board, and then selectively operating even-numbered conveyors while checking the results of sensor detection of the board. However, operating odd-numbered conveyors before operating even-numbered conveyors means that it takes a long time to search for the board. As a result, there have been cases where a different technology is needed to deal with boards left straddling two adjacent conveyors.

This invention was developed in consideration of the above-mentioned issues, and aims to provide technology that can handle boards that are left straddling two adjacent conveyors.

The component mounting system of the present invention comprises N conveyors (N is an integer of 2 or greater) arranged in a predetermined arrangement direction and transporting boards in a first direction parallel to the arrangement direction and a second direction opposite to the first direction; a mounting head that mounts components onto boards supported by the conveyors; a boundary sensor that is provided corresponding to the boundary between two adjacent conveyors and detects boards at the boundary; and a control unit that operates the two conveyors in the first direction to transport boards in the first direction, and determines whether or not a retraction operation is required to retract a board straddling the two conveyors from the boundary based on the length of the board in the arrangement direction and the detection result of the board by the boundary sensor.

The substrate transport control method of the present invention includes a step of determining whether a retraction operation is required to retract a substrate from the boundary between two adjacent conveyors (N conveyors, where N is an integer greater than or equal to 2) that are arranged in a predetermined arrangement direction and transport substrates in a first direction parallel to the arrangement direction and a second direction opposite to the first direction, and a step of executing the retraction operation when it is determined that the retraction operation is required. Whether or not the retraction operation is required is determined based on the detection result of the substrate by a boundary sensor that is provided corresponding to the boundary between the two adjacent conveyors and detects the substrate at the boundary, and the length of the substrate in the arrangement direction.

In this invention (component mounting system and board transport control method) configured in this way, the need for a retraction operation to retract a board straddling two conveyors from the boundary is determined based on the length of the board in the arrangement direction and the detection results of the board by the boundary sensor. Therefore, a retraction operation can be performed depending on the determination of need, and an operation such as retracting the board from the boundary between the two conveyors can be performed. In this way, it is possible to deal with boards left straddling two adjacent conveyors.

The component mounting system may also be configured so that the control unit determines that a retraction operation is necessary when the length of the board in the arrangement direction is shorter than the length of the downstream conveyor in the first direction of the two conveyors and the boundary sensor detects the board. This makes it possible to move a board left straddling two conveyors to the downstream conveyor in the first direction of the two conveyors and retract it from the boundary between the two conveyors. In this way, it is possible to deal with boards left straddling two adjacent conveyors.

The component mounting system may also be configured so that N is 4 or greater, and the control unit divides the N conveyors into multiple sections, each having a length greater than or equal to 1x and less than 2x the length of the board in the arrangement direction, and each section includes two or more conveyors. The control unit determines that a retraction operation to retract the board from a boundary included in a section is unnecessary, while determining whether a retraction operation to retract the board from a section boundary between two adjacent sections is necessary based on the detection results of the board by a boundary sensor positioned corresponding to the section boundary. This configuration functions effectively when one board is supported per section. In other words, in such a case, even if the board straddles a boundary included in the middle of a section, there is no need to retract the board from that boundary. On the other hand, if the board straddles a section boundary between two adjacent sections, the board needs to be retracted from that section boundary. In contrast, this configuration makes it possible to accurately determine whether a retraction operation is necessary.

The component mounting system may also be configured so that, if the control unit determines that a retraction operation is necessary, it performs a search operation to search for a conveyor supporting a board from among the N conveyors after the retraction operation, whereas if it determines that a retraction operation is not necessary, it performs the search operation without performing the retraction operation. In this configuration, the retraction operation is performed depending on whether it is necessary, preventing overdetection of the board during the search operation.

The component mounting system may also be configured to further include an upstream sensor that detects boards at the upstream ends of the N conveyors in the first direction, and the control unit performs a search operation by determining the presence or absence of boards on the N conveyors based on the board detection results of the boundary sensor and upstream sensor when the N conveyors are operated in the second direction. In this configuration, the boundary sensor and upstream sensor can detect boards, allowing the search operation to be performed quickly.

The component mounting system may also be configured so that the control unit performs a search operation by detecting the edge of the board downstream in the second direction using a boundary sensor or upstream sensor. In this configuration, the edge of the board can be detected by the boundary sensor or upstream sensor, allowing the search operation to be performed quickly.

The component mounting system may also be configured to further include a positioning sensor that detects the board between both ends of the conveyor in the first direction, and the control unit performs a search operation by determining the presence or absence of the board on the N conveyors based on the board detection results of the positioning sensor when the N conveyors are operated in the second direction. In this configuration, the positioning sensor can detect the board, allowing the search operation to be performed quickly.

The component mounting system may also be configured so that the control unit performs the search operation by using a positioning sensor to detect the edge of the board downstream in the second direction. In this configuration, the positioning sensor can detect the edge of the board, allowing the search operation to be performed quickly.

The component mounting system may also be configured so that the control unit sequentially loads multiple boards using N conveyors and mounts components on the loaded boards using the mounting heads, thereby producing multiple component-mounted boards, and the control unit performs a search operation before the production of the multiple component-mounted boards begins or is interrupted. In this configuration, boards left on the conveyors can be searched for before board production begins or is interrupted.

The component mounting system may also be configured so that the control unit determines that a retraction operation to retract the board from the boundary is unnecessary if the length of the board in the alignment direction is longer than the length of the downstream conveyor in the first direction of the two conveyors. This configuration makes it possible to accurately determine whether a retraction operation is necessary.

The component mounting system may also be configured so that the distance between the two ends of the two conveyors in the arrangement direction is longer than the length of the board, the board on which components are mounted by the mounting head is supported between the two ends of the conveyors, and the control unit determines whether or not a search operation is required to search for boards remaining on the N conveyors based on the detection results of the boards by the boundary sensor. With this configuration, it is possible to accurately determine whether or not a search operation is required.

The component mounting system may also be configured to further include an upstream sensor for detecting boards upstream in the first direction for each of the two conveyors, and a downstream sensor for detecting boards downstream in the first direction for each of the two conveyors, and the control unit performs a search operation by determining the presence or absence of boards on the N conveyors based on the board detection results of the upstream and downstream sensors when the N conveyors are operated in the second direction. With this configuration, the upstream and downstream sensors can detect boards, allowing the search operation to be performed quickly.

The component mounting system may also be configured so that the control unit determines that a search operation is not necessary when the boundary sensor detects a board, and determines that a search operation is necessary when the boundary sensor does not detect a board. This configuration makes it possible to accurately determine whether a search operation is necessary.

The component mounting system may also be configured so that the two conveyors further include a downstream sensor that detects boards downstream in the first direction, the length between the two conveyors in the arrangement direction being longer than the length of the boards, the boards on which components are mounted by the mounting heads being supported between the two conveyors, and the control unit determines whether a search operation is necessary to search for boards remaining on the N conveyors based on the detection results of the downstream sensor. With this configuration, it is possible to accurately determine whether a search operation is necessary.

The component mounting system may also be configured so that the control unit determines that a search operation is not necessary when the downstream sensor detects a board, and determines that a search operation is necessary when the downstream sensor does not detect a board. This configuration makes it possible to accurately determine whether a search operation is necessary.

The component mounting system may also be configured so that the control unit sequentially loads multiple boards using N conveyors and mounts components on the loaded boards using the mounting heads, thereby producing multiple component-mounted boards, and the control unit determines whether a search operation is necessary before the start or interruption of production of the multiple component-mounted boards. In this configuration, boards left on the conveyors can be searched for before board production starts or when it is interrupted.

The component mounting system may also be configured so that the control unit performs the retraction operation by operating the two conveyors in the first direction until the boundary sensor no longer detects the board. This configuration retracts a board that is left straddling two conveyors from the boundary between the two conveyors. In this way, it is possible to deal with a board that is left straddling two adjacent conveyors.

As described above, the present invention makes it possible to handle boards that are left straddling two adjacent conveyors.

1 is a plan view schematically showing a component mounting machine that is an example of a component mounting system according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the component mounter of FIG. 1 . FIG. 4 is a diagram schematically showing a manner in which a substrate is supported by a substrate transport unit. 10 is a flowchart showing an example of handling remaining substrates. 5 is a flowchart showing an example of a first preparation executed in response to the remaining substrate of FIG. 4 . FIG. 6 is a diagram schematically illustrating the operations executed in the first preparation in FIG. 5 . 6 is a flowchart showing an example of a search operation executed in the first preparation of FIG. 5 . FIG. 8 is a diagram illustrating operations performed in the search operation of FIG. 7 . 6 is a flowchart showing an example of a positioning operation executed in the first preparation of FIG. 5 . 10A to 10C are diagrams illustrating operations performed in the positioning operation of FIG. 9 . 5 is a flowchart showing an example of a second preparation executed in response to the remaining substrate of FIG. 4 . FIG. 12 is a diagram schematically illustrating the operations executed in the second preparation of FIG. 11 . 13 is a flowchart showing an example of a search operation (section) executed in the second preparation of FIG. 12 . FIG. 14 is a diagram schematically showing the operations executed in the search operation (section) of FIG. 13 . 12 is a flowchart showing an example of a positioning operation (section) executed in the second preparation of FIG. 11 . 16A and 16B are diagrams illustrating operations performed in the positioning operation (section) of FIG. 15 . 5 is a flowchart showing an example of a third preparation executed in response to the remaining substrate in FIG. 4 . FIG. 18 is a diagram schematically illustrating the operations executed in the third preparation of FIG. 17 . 5 is a flowchart showing an example of a fourth preparation executed in response to the remaining substrate in FIG. 4 . FIG. 20 is a diagram schematically illustrating the operations executed in the fourth preparation of FIG. 19 .

Figure 1 is a plan view that schematically shows a component mounter that is an example of a component mounting system according to the present invention, and Figure 2 is a block diagram that shows the electrical configuration of the component mounter of Figure 1. Figure 1 appropriately shows the horizontal board transport direction X, the width direction Y that is a horizontal direction perpendicular to the board transport direction X, and the vertical direction Z. Furthermore, the forward direction X1 and reverse direction X2 of the board transport direction X are appropriately shown. Here, the forward direction X1 and reverse direction X2 are opposite to each other.

The mounter 1 mounts components E on board B to produce a mounted board, which is board B on which components E are mounted. As shown in FIG. 2, the mounter 1 includes a control unit 10 that controls each component of the mounter 1. The control unit 10 includes a main controller 11 that oversees the control required for component mounting, and a memory unit 12 that stores programs and data used in component mounting. The main controller 11 is a processor such as a CPU (Central Processing Unit), and the memory unit 12 is a storage device such as an SSD (Solid State Drive). The memory unit 12 stores a production program 121 that shows the procedure for mounting components E on board B, and board-related data 122 that shows data related to board B (specifically, the size of board B, etc.). The control unit 10 also includes a head controller 13 and a board transport controller 14.

The component mounter 1 in Figure 1 includes a board transport unit 2 that transports a board B in the forward direction X1 and the reverse direction X2 of the board transport direction X. This board transport unit 2 has a standby conveyor 21, a mounting conveyor 22, a mounting conveyor 23, and a standby conveyor 24 that are arranged in series in this order in the forward direction X1 of the board transport direction X. In other words, the standby conveyor 21 and the mounting conveyor 22 are adjacent to each other in the board transport direction X with a boundary R1 in between, the mounting conveyor 22 and the mounting conveyor 23 are adjacent to each other with a boundary R2 in between, and the mounting conveyor 23 and the standby conveyor 24 are adjacent to each other with a boundary R3 in between. Each of conveyors 21, 22, 23, and 24 has two belt conveyors 20 arranged in parallel, and conveys board B in the forward direction X1 by rotating belt conveyor 20 and moving the upper surface (the surface supporting board B) of belt conveyor 20 in the forward direction X1, and conveys board B in the reverse direction X2 by moving the upper surface (the surface supporting board B) of belt conveyor 20 in the reverse direction X2. Note that in this specification, the expression "a conveyor operates in the forward direction X1 (reverse direction X2)" will be used appropriately to indicate that the upper surface of belt conveyor 20 of the conveyor moves in the forward direction X1 (reverse direction X2).

The standby conveyor 21 supports a board B that has been carried in from the upstream side in the forward direction X1, allowing the board B to wait. The standby conveyor 21 also transports the board B in the forward direction X1, thereby transferring the board B to the mounting conveyor 22. The mounting conveyor 22 supports the board B received from the standby conveyor 21. In this way, components E are mounted on the board B supported by the mounting conveyor 22. The mounting conveyor 22 also transports the board B in the forward direction X1, thereby transferring the board B to the mounting conveyor 23. The mounting conveyor 23 supports the board B received from the mounting conveyor 22. In this way, components E are mounted on the board B supported by the mounting conveyor 23. The mounting conveyor 23 also transports the board B in the forward direction X1, thereby transferring the board B to the standby conveyor 24. The standby conveyor 24 supports the board B received from the mounting conveyor 23, allowing the board B to wait. In addition, the standby conveyor 24 transports the board B in the forward direction X1, thereby carrying the board B downstream in the forward direction X1. These conveyors 21, 22, 23, and 24 operate under the control of the board transport control unit 14.

The mounter 1 also includes a board detection unit Ud that uses board sensors to detect the position of the board B supported by the board transport unit 2. The board detection unit Ud includes a trailing edge sensor Su, a boundary sensor Sr1, a boundary sensor Sr2, a boundary sensor Sr3, and a leading edge sensor Sd, arranged in this order in the forward direction X1 of the board transport direction X. These sensors Su, Sr1, Sr2, Sr3, and Sd are, for example, optical sensors that output an ON signal to the board transport control unit 14 while detecting the board B and an OFF signal to the board transport control unit 14 while not detecting the board B. The trailing edge sensor Su is positioned corresponding to the upstream end of the standby conveyor 21 in the forward direction X1 and detects the presence or absence of the board B at this upstream end. The boundary sensor Sr1 is positioned corresponding to the boundary R1 between the standby conveyor 21 and the mounting conveyor 22 in the forward direction X1 and detects the presence or absence of the board B at this boundary R1. Boundary sensor Sr2 is positioned corresponding to boundary R2 between mounting conveyor 22 and mounting conveyor 23 in the forward direction X1, and detects the presence or absence of board B at boundary R2. Boundary sensor Sr3 is positioned corresponding to boundary R3 between mounting conveyor 23 and standby conveyor 24 in the forward direction X1, and detects the presence or absence of board B at boundary R3. Front end sensor Sd is positioned corresponding to the downstream end of standby conveyor 24 in the forward direction X1, and detects the presence or absence of board B at that downstream end.

Then, the board transport control unit 14 positions the board B in the board transport direction X by controlling the board transport unit 2 based on the position of the board B detected by the board detection unit Ud. In other words, the board transport unit 2 does not have a stopper that positions the board B by abutting against it (stopperless). Therefore, the board transport control unit 14 positions the board B by moving the upper surface of the belt conveyor 20 of conveyor 21, 22, 23, or 24 by a predetermined amount from the timing when the board detection unit Ud detects the board using the board sensor. The amount of movement of the belt conveyor 20 is obtained by the board transport control unit 14 from the encoder output of the motor that drives the belt conveyor 20 of conveyor 21, 22, 23, or 24.

The mounter 1 also includes two head units 3, each of which mounts a component E on a board B, and a head drive unit 4 that independently drives the two head units 3 in the board transport direction X and width direction Y. The head drive unit 4 can be configured using a known XY drive mechanism. The drive of each head unit 3 by the head drive unit 4 is controlled by the head control unit 13 based on the production program 121.

The component mounter 1 further includes two component supply units 5. The two component supply units 5 are arranged on either side of the board transport unit 2 in the width direction Y, sandwiching the board transport unit 2 therebetween. Each component supply unit 5 has multiple tape feeders 51 arranged in the board transport direction X, and each tape feeder 51 feeds out a carrier tape containing components E in the width direction Y, thereby supplying components E to a component supply position located at the tip of the board transport unit 2 in the width direction Y. Note that the feeder used by the component supply unit 5 to supply components E is not limited to a tape feeder 51, and may be, for example, a tray feeder that supplies components E placed on a tray.

The head unit 3 has multiple mounting heads 31 (six in the example shown in Figure 1) arranged in the substrate transport direction X. Each mounting head 31 has an elongated shape extending in the Z direction, and is capable of suctioning and holding components E using a nozzle detachably attached to the bottom end of the mounting head 31. The mounting head 31 then uses this nozzle to transfer components E picked up from the tape feeder 51 onto the substrate B, thereby mounting the components E on the substrate B.

As shown in FIG. 1, each of the standby conveyors 21 and 24 has a length Lcw in the board transport direction X, and each of the mounting conveyors 22 and 23 has a length Lcm in the board transport direction X. Here, the length Lcm of each of the mounting conveyors 22 and 23 is longer than the length Lcw of each of the standby conveyors 21 and 24. Furthermore, in the board transport direction X, the length between the ends of the mounting conveyor 22 and the mounting conveyor 23 is length Lcm, and the length between the ends of the mounting conveyor 23 and the standby conveyor 24 (the length between the ends of the standby conveyor 21 and the mounting conveyor 22) is length Lcmw. Here, the length between the ends of the multiple conveyors in the board transport direction X refers to the length between the most upstream end of the most upstream conveyor and the most downstream end of the most downstream conveyor among the multiple conveyors in the board transport direction X (in other words, the forward direction X1). Such a board transport unit 2 can support the board B in each of the modes shown in FIG. 3, depending on the length Lb of the board B in the board transport direction X.

Figure 3 is a schematic diagram showing how a board is supported by the board transport unit. When the length Lb of board B is length Lb1, which is less than or equal to length Lcw, board B can be supported by each of standby conveyor 21, mounting conveyor 22, mounting conveyor 23, and standby conveyor 24. Therefore, two boards B on which components E are mounted by the mounting head 3 are supported by mounting conveyor 22 and mounting conveyor 23, respectively. Furthermore, boards B waiting for mounting of components E by the mounting head 3 are supported by standby conveyor 21, and boards B on which mounting of components E by the mounting head 3 has been completed are supported by standby conveyor 24. Therefore, the maximum number of boards B that can be supported by the board transport unit 2 is four.

When the length Lb of the board B is Lb2, which is longer than the length Lcw but less than the length L cm, the board B can fit on both the mounting conveyor 22 and the mounting conveyor 23, but cannot fit on either the standby conveyor 21 or the standby conveyor 24. Therefore, as shown in the "Mounting" column, the two boards B on which components E are mounted by the mounting head 3 are supported by the mounting conveyor 22 and the mounting conveyor 23, respectively, but are not supported by either the standby conveyor 21 or the standby conveyor 24. Also, as shown in the "Standby" column, the board B after mounting components E by the mounting head 3 is supported by both the mounting conveyor 23 and the standby conveyor 24, straddling them. Similarly, the board B before mounting components E by the mounting head 3 is supported by both the standby conveyor 21 and the mounting conveyor 22, straddling them. Therefore, the maximum number of boards B that can be supported by the board transport unit 2 is two.

If the length Lb of board B is length Lb3, which is longer than length Lcm but less than length Lcmw, board B cannot fit on any of the standby conveyor 21, mounting conveyor 22, mounting conveyor 23, and standby conveyor 24. Therefore, as shown in the "Mounting" column, two boards B on which components E are mounted by the mounting head 3 are supported by straddling both mounting conveyor 22 and mounting conveyor 23. Also, as shown in the "Standby" column, board B before components E are mounted by the mounting head 3 is supported by straddling both standby conveyor 21 and mounting conveyor 22, and board B after components E are mounted by the mounting head 3 is supported by straddling both mounting conveyor 23 and standby conveyor 24. Therefore, the maximum number of boards B that can be supported by the board transport unit 2 is two.

When the length Lb of board B is length Lb4, which is longer than length Lcmw but less than or equal to length Lcm, board B cannot fit on any of the standby conveyor 21, mounting conveyor 22, mounting conveyor 23, and standby conveyor 24. Therefore, as shown in the "Mounting" column, two boards B on which components E are mounted by the mounting head 3 are supported by straddling both the mounting conveyor 22 and the mounting conveyor 23. Also, as shown in the "Standby" column, boards B after mounting components E by the mounting head 3 are supported by straddling the mounting conveyor 22, mounting conveyor 23, and standby conveyor 24. Similarly, boards B before mounting components E by the mounting head 3 are supported by straddling the standby conveyor 21, mounting conveyor 22, and mounting conveyor 23. Therefore, the board transport unit 2 can support a maximum of one board B.

In the component mounter 1 described above, the control unit 10 controls the memory unit 12 and the board transport control unit 14 based on the production program 121, thereby carrying out board production in which multiple boards B are loaded sequentially using the board transport unit 2 and components E are mounted on the loaded multiple boards B using the mounting head 3, thereby producing multiple boards with components mounted on them. During this process, there may be boards B left behind on the board transport unit 2 before board production begins or when it is interrupted. To deal with such left-behind boards B, the main control unit 11 executes the remaining board handling process shown in Figure 4.

Figure 4 is a flowchart showing an example of how to deal with remaining boards. In step S101 of Figure 4, the main control unit 11 determines whether the conditions for executing each operation to deal with remaining board B have been met. For example, conditions such as before board production begins or when board production is interrupted (i.e., before restarting after an interruption) are defined as execution conditions. Specific examples of execution conditions are not limited to these, and execution conditions may also be defined as immediately after powering on the mounter 1, when an error occurs in transporting board B by the board transport unit 2, when the cover of the mounter 1 is opened or closed, or when an operator manually operates conveyors 21, 22, 23, or 24.

When the main control unit 11 determines that the execution conditions are met ("YES" in step S101), it issues a command to the substrate transport control unit 14 to execute steps S102 to S108, and the substrate transport control unit 14 executes steps S102 to S108 in accordance with the command received from the main control unit 11. In particular, the substrate transport control unit 14 selects and executes the operation to be executed according to the length Lb of the substrate B from among first preparation (step S103), second preparation (step S105), third preparation (step S107), and fourth preparation (step S108). These preparations must be executed before the substrate transport unit 2 begins transporting the substrate B for substrate production.

In other words, in step S102, it is determined whether the length Lb of the board B is less than or equal to the length Lcw of the standby conveyors 21, 24, in other words, whether it corresponds to the length Lb1 shown in FIG. 3. If the length Lb of the board B is less than or equal to the length Lcw of the standby conveyors 21, 24 (YES in step S102), the first preparation in step S103 is executed.

Figure 5 is a flowchart showing an example of the first preparation performed in response to the remaining substrate in Figure 4, Figure 6 is a diagram showing the operations performed in the first preparation in Figure 5, Figure 7 is a flowchart showing an example of the search operation performed in the first preparation in Figure 5, Figure 8 is a diagram showing the operations performed in the search operation in Figure 7, Figure 9 is a flowchart showing an example of the positioning operation performed in the first preparation in Figure 5, and Figure 10 is a diagram showing the operations performed in the positioning operation in Figure 9.

In the first preparation step of FIG. 5, the board transport control unit 14 checks the output of each of the boundary sensors Sr1, Sr2, and Sr3 (step S201) and determines whether the outputs of all of the boundary sensors Sr1, Sr2, and Sr3 are off (step S202). If the output of at least one of the boundary sensors Sr1, Sr2, and Sr3 is on ("NO" in step S202), steps S203 to S206 are executed. In the example shown in the "S201" column of FIG. 6, board B is left straddling the mounting conveyor 22 and the mounting conveyor 23, and board B is left straddling the mounting conveyor 23 and the standby conveyor 24. Therefore, boundary sensors Sr2 and Sr3 output on, and a "NO" determination is made in step S202.

In step S203, it is determined whether the conveyors upstream and downstream of the boundary sensor Sr1, Sr2, or Sr3 that is confirmed to output an OFF signal (i.e., the two adjacent conveyors across the boundary corresponding to that sensor) are operating. In the example shown in the "S201" column of Figure 6, boundary sensor Sr1 outputs an OFF signal, so it is determined whether the standby conveyor 21 and mounting conveyor 22 upstream and downstream of that boundary sensor Sr1 are operating (step S203). If both the upstream and downstream conveyors (the standby conveyor 21 and mounting conveyor 22) are stopped ("NO" in step S204), the process proceeds to step S206. On the other hand, if at least one of the upstream and downstream conveyors (the standby conveyor 21 and mounting conveyor 22) is operating ("YES" in step S204), that at least one conveyor is stopped (step S205) and then the process proceeds to step S206.

In step S206, the board transport control unit 14 operates the conveyors upstream and downstream of the boundary sensor Sr1, Sr2, or Sr3 that is confirmed to output an ON signal in the forward direction X1. In the example shown in the "S201" column of FIG. 6, boundary sensor Sr2 outputs an ON signal, so the mounting conveyors 22 and 23 upstream and downstream of boundary sensor Sr2 operate in the forward direction X1 (step S206). Furthermore, boundary sensor Sr3 outputs an ON signal, so the mounting conveyors 23 and standby conveyors 24 upstream and downstream of boundary sensor Sr3 operate in the forward direction X1 (step S206). As a result, as shown by the arrows in the "S206" column of FIG. 6, board B overlapping boundary R2 moves in the forward direction X1, and board B overlapping boundary R3 moves in the forward direction X1.

Following step S206, the process returns to step S201. That is, the output of each of boundary sensors Sr1, Sr2, and Sr3 is checked (step S201), and it is determined whether the outputs of all boundary sensors Sr1, Sr2, and Sr3 are OFF (step S202). In the example shown in the "S201_2" column in Figure 6, board B straddles mounting conveyors 22 and 23, and boundary sensor Sr2 outputs ON, resulting in a "NO" determination in step S202. Note that as the mounting conveyor 23 and standby conveyor 24 move in the forward direction X1 starting in step S206, board B retreats from boundary R3 to the forward direction X1, causing the output of boundary sensor Sr3 to change from ON to OFF.

In step S203, it is determined whether the conveyors upstream and downstream of the boundary sensor Sr1, Sr2, or Sr3 that is confirmed to output an OFF signal (i.e., the two adjacent conveyors across the boundary corresponding to that sensor) are operating. In the example shown in the "S201_2" column of Figure 6, boundary sensors Sr1 and Sr3 output an OFF signal, so it is determined whether the standby conveyor 21 and mounting conveyor 22 upstream and downstream of that boundary sensor Sr1 are operating, and it is also determined whether the mounting conveyor 23 and standby conveyor 24 upstream and downstream of that boundary sensor Sr3 are operating (step S203). In this example, the mounting conveyor 23 and standby conveyor 24 are operating ("YES" in step S204), so the mounting conveyor 23 and standby conveyor 24 are stopped (step S205), and then the process proceeds to step S206.

In step S206, the board transport control unit 14 operates the conveyors upstream and downstream of the boundary sensor Sr1, Sr2, or Sr3 that is confirmed to output an ON signal in the forward direction X1. In the example shown in the "S201_2" column in Figure 6, boundary sensor Sr2 outputs an ON signal, so the mounting conveyors 22 and 23 upstream and downstream of boundary sensor Sr2 operate in the forward direction X1 (step S206).

Following step S206, the process returns to step S201. That is, the output of each of boundary sensors Sr1, Sr2, and Sr3 is checked (step S201), and it is determined whether the outputs of all boundary sensors Sr1, Sr2, and Sr3 are OFF (step S202). In the example shown in the "S201_3" column in Figure 6, board B has retreated from all of boundaries R1, R2, and R3 in the forward direction X1, and all boundary sensors Sr1, Sr2, and Sr3 output OFF ("YES" in step S202). Therefore, the board transport control unit 14 stops all of conveyors 21, 22, 23, and 24 (step S207).

By executing steps S203 to S206 (retraction operation) in this manner, board B that straddled the mounting conveyors 22 and 23 before the start of the first preparation retracts in the forward direction X1 from the boundary R2 between the mounting conveyors 22 and 23, and board B that straddled the mounting conveyor 23 and the standby conveyor 24 retracts in the forward direction X1 from the boundary R3 between the mounting conveyor 23 and the standby conveyor 24 (see "S201_3" in Figure 6 or the "Before search operation starts" column in Figure 8).

Once steps S201 to S207, including the retraction operation (steps S203 to S206), are completed, a search operation is performed (step S208). In the search operation shown in FIG. 7, the board transport control unit 14 operates all of the conveyors 21, 22, 23, and 24 in the reverse direction X2 (step S301). This causes the boards B supported by the board transport unit 2 (specifically, the three boards B supported by the standby conveyor 21, mounting conveyor 23, and standby conveyor 24) to move in the reverse direction X2 (arrows in the "S301" column in FIG. 8). In step S302, the board transport control unit 14 determines whether each of the conveyors 21, 22, 23, and 24 has moved a predetermined distance. This predetermined distance is set according to the length of each of the conveyors 21, 22, 23, and 24. For example, the predetermined distance set for the standby conveyors 21 and 24 can be length Lcw, and the predetermined distance set for the mounting conveyors 22 and 23 can be length Lcm.

If each of the conveyors 21, 22, 23, and 24 has not moved the predetermined distance ("NO" in step S302), the board transport control unit 14 determines whether board B has been detected on all of the conveyors 21, 22, 23, and 24 (step S303). Here, detecting board B on the standby conveyor 21 means that the rear end sensor Su located at the downstream end of the standby conveyor 21 in the reverse direction X2 detects board B. detecting board B on the mounting conveyor 22 means that the boundary sensor Sr1 corresponding to the downstream boundary R1 of the mounting conveyor 22 in the reverse direction X2 detects board B. detecting board B on the mounting conveyor 23 means that the boundary sensor Sr2 corresponding to the downstream boundary R2 of the mounting conveyor 23 in the reverse direction X2 detects board B. detecting board B on the standby conveyor 24 means that the boundary sensor Sr3 corresponding to the downstream boundary R3 of the standby conveyor 24 in the reverse direction X2 detects board B.

In the example shown in the "S301" column of Figure 8, board B has not been detected on any of conveyors 21, 22, 23, and 24 ("NO" in step S303), so the process proceeds to step S304. In step S304, the board transport control unit 14 determines whether any of sensors Su, Sr1, Sr2, and Sr3 outputs an ON signal (ON output sensor). If no ON output sensor exists ("NO" in step S304), the process returns to step S302.

On the other hand, if an ON output sensor is present (YES in step S304), the board transport control unit 14 stops the conveyor corresponding to the ON output sensor (step S305). Here, the conveyor corresponding to the trailing edge sensor Su is the standby conveyor 21, the conveyor corresponding to the boundary sensor Sr1 is the mounting conveyor 22, the conveyor corresponding to the boundary sensor Sr2 is the mounting conveyor 23, and the conveyor corresponding to the boundary sensor Sr3 is the standby conveyor 24. In other words, in step S305, board B detected by the ON output sensor is stopped. Following step S305, the process returns to step S302.

In the example of "S304" in Figure 8, the boundary sensors Sr2 and Sr3 each output an ON signal, causing the mounting conveyor 23 and standby conveyor 24 to stop. Meanwhile, the trailing edge sensor Su and boundary sensor Sr1 output an OFF signal, causing the standby conveyor 21 and mounting conveyor 22 to continue operating in the reverse direction X2.

Steps S303 to S305 are
Each of the conveyors 21, 22, 23, and 24 operates a predetermined distance ("YES" in step S302,
Board B is detected on all of conveyors 21, 22, 23, and 24 (YES in step S303).
On the other hand, if any of these conditions is met, all of the conveyors 21, 22, 23 and 24 are stopped in step S306, and the search operation in FIG. 7 is completed.

In the example shown in the "S304" column of Figure 8, each of the conveyors 21, 22, 23, and 24 has not moved the predetermined distance ("NO" in step S302). Furthermore, board B has not been detected on the standby conveyor 21 ("NO" in step S303). Therefore, steps S304 to S305 are executed in the same manner as described above. As in the example shown in the "S304_2" column of Figure 8, when the trailing edge sensor Su outputs an ON signal ("YES" in step S304), the board transport control unit 14 stops the standby conveyor 21 corresponding to the trailing edge sensor Su, thereby stopping board B detected by the trailing edge sensor Su (step S305).

In the example shown in Figure 8, since there is no board B corresponding to mounting conveyor 22, the condition of step S303 is not met. Therefore, when mounting conveyor 22 moves a predetermined distance ("YES" in step S302), conveyors 21, 22, 23, and 24 are all stopped (step S306), and the search operation of Figure 7 ends.

By executing steps S208 and S301 to S306 (search operation) in this way, the upstream end of each board B in the forward direction X1 coincides with the position (detected position) detected by one of sensors Su, Sr1, Sr2, and Sr3 ("S304_2" in Figure 8 or the "Before positioning operation starts" column in Figure 10).

As shown in FIG. 5, once the search operation in step S208 is completed, a positioning operation is performed (step S208). In the positioning operation shown in FIG. 9, the board transport control unit 14 performs positioning of the conveyors 21, 22, 23, and 24, starting with the conveyor that is downstream in the forward direction X1. Therefore, in step S401, of the conveyors 21, 22, 23, and 24, the standby conveyor 24 that is furthest downstream in the forward direction X1 is set as the target conveyor.

In step S402, the board transport control unit 14 determines whether the boundary sensor Sr3 corresponding to the standby conveyor 24, which is the target conveyor, detects board B. If the boundary sensor Sr3 does not detect board B and outputs an OFF signal (NO in step S402), the process proceeds to step S407. On the other hand, if the boundary sensor Sr3 detects board B and outputs an ON signal (YES in step S402), the process proceeds to step S403. In the example "before the positioning operation begins" in Figure 10, the search operation results in the upstream end of board B on the standby conveyor 24 in the forward direction X1 coinciding with the detection position of the boundary sensor Sr3, and the boundary sensor Sr3 detects board B (YES in step S402). Therefore, steps S403 to S406 are executed.

In step S403, the standby conveyor 24, which is the target conveyor, operates in the forward direction X1, and the board B on the standby conveyor 24 moves in the forward direction X1. In step S404, the board transport control unit 14 determines whether the output of the sensor corresponding to the standby conveyor 24, i.e., the boundary sensor Sr3, has changed. In the example of FIG. 10, as the board B moves, the edge of the board B moves away from the boundary sensor Sr3 in the forward direction X1, causing the output of the boundary sensor Sr3 to change from ON to OFF ("YES" in step S404). From the timing when the output of the boundary sensor Sr3 changes, the board transport control unit 14 operates the standby conveyor 24, which is the target conveyor, a specified distance in the forward direction X1 (step S405) and stops the standby conveyor 24 (step S406). As a result, as shown in the "S406" column in FIG. 10, the board B on the standby conveyor 24 is positioned at a position that is the specified distance away from the boundary sensor Sr3 in the forward direction X1.

In step S407, the board transport control unit 14 determines whether the target conveyor is the most upstream conveyor in the forward direction X1, i.e., the standby conveyor 21. In this example, the target conveyor is the standby conveyor 24, not the standby conveyor 21 ("NO" in step S407). Therefore, in step S408, the conveyor one level upstream, i.e., the mounting conveyor 23, is set as the target, and the process returns to step S402.

In step S402, the board transport control unit 14 determines whether the boundary sensor Sr2 corresponding to the target conveyor, the mounting conveyor 23, detects board B. In the example "before the positioning operation begins" in Figure 10, the search operation results in the detection position of boundary sensor Sr2 coinciding with the upstream end of board B in the forward direction X1 on the mounting conveyor 23, and boundary sensor Sr2 detects board B ("YES" in step S402). Therefore, steps S403 to S406 are executed.

In step S403, the target conveyor, the mounting conveyor 23, operates in the forward direction X1, causing board B on the mounting conveyor 23 to move in the forward direction X1. In step S404, the board transport control unit 14 determines whether the output of the sensor corresponding to the mounting conveyor 23, i.e., the boundary sensor Sr2, has changed. In the example of FIG. 10, as board B moves, the edge of board B moves away from boundary sensor Sr2 in the forward direction X1, causing the output of boundary sensor Sr2 to change from ON to OFF ("YES" in step S404). From the timing when the output of boundary sensor Sr2 changes, the board transport control unit 14 operates the target conveyor, the mounting conveyor 23, in the forward direction X1 by a specified distance (step S405), and stops the mounting conveyor 23 (step S406). As a result, as shown in the "S406_2" column in FIG. 10, board B on the mounting conveyor 23 is positioned at a position that is the specified distance away from boundary sensor Sr2 in the forward direction X1.

Incidentally, the board detection unit Ud can be equipped with a positioning sensor Sla that detects the board B supported by the mounting conveyor 23. In a configuration equipped with this positioning sensor Sla, the positioning sensor Sla can be used instead of the boundary sensor Sr2 as the sensor corresponding to the mounting conveyor 23. In other words, the board transport control unit 14 may operate the mounting conveyor 23 a specified distance from the timing at which it is confirmed in step S404 that the output of the positioning sensor Sla has changed from off to on.

In step S407, the board transport control unit 14 determines whether the target conveyor is the most upstream conveyor in the forward direction X1, i.e., the standby conveyor 21. In this example, the target conveyor is the standby mounting conveyor 23, not the standby conveyor 21 ("NO" in step S407). Therefore, in step S408, the conveyor one level upstream, i.e., the mounting conveyor 22, is set as the target, and the process returns to step S402.

In step S402, the board transport control unit 14 determines whether the boundary sensor Sr1 corresponding to the target conveyor, the mounting conveyor 22, detects board B. In the example of "before the start of the positioning operation" in Figure 10, the corresponding board B is not present, so the boundary sensor Sr2 does not detect board B ("NO" in step S402). Therefore, the process proceeds to step S407.

In step S407, the board transport control unit 14 determines whether the target conveyor is the most upstream conveyor in the forward direction X1, i.e., the standby conveyor 21. In this example, the target conveyor is the mounting conveyor 22, not the standby conveyor 21 ("NO" in step S407). Therefore, in step S408, the conveyor one level upstream, i.e., the standby conveyor 21, is set as the target, and the process returns to step S402.

In step S402, the board transport control unit 14 determines whether the trailing edge sensor Su corresponding to the target conveyor, the standby conveyor 21, detects board B. In the example "before the positioning operation begins" in Figure 10, the search operation results in the detection position of the trailing edge sensor Su coinciding with the upstream edge of board B on the standby conveyor 21 in the forward direction X1, and the trailing edge sensor Su detects board B ("YES" in step S402). Therefore, steps S403 to S406 are executed.

In step S403, the standby conveyor 21, which is the target conveyor, operates in the forward direction X1, and the board B on the standby conveyor 21 moves in the forward direction X1. In step S404, the board transport control unit 14 determines whether the output of the sensor corresponding to the standby conveyor 21, i.e., the trailing edge sensor Su, has changed. In the example of FIG. 10, as the board B moves, the edge of the board B moves away from the trailing edge sensor Su in the forward direction X1, causing the output of the trailing edge sensor Su to change from ON to OFF ("YES" in step S404). From the timing when the output of the trailing edge sensor Su changes, the board transport control unit 14 operates the standby conveyor 21, which is the target conveyor, in the forward direction X1 by a specified distance (step S405) and stops the standby conveyor 21 (step S406). As a result, as shown in the "S406_3" column in FIG. 10, the board B on the standby conveyor 21 is positioned at a position that is the specified distance away from the trailing edge sensor Su in the forward direction X1.

In step S407, the board transport control unit 14 determines whether the target conveyor is the most upstream conveyor in the forward direction X1, i.e., the standby conveyor 21. In this example, the target conveyor is the standby conveyor 21 ("YES" in step S407). Therefore, the positioning operation in Figure 9 ends, and the first preparation in Figure 5 ends.

Returning to Figure 4, the explanation continues. If the length Lb of board B is longer than the length Lcw ("NO" in step S102), then in step S104 it is determined whether the length Lb of board B is equal to or less than the length L cm of the mounting conveyors 22, 23, in other words, whether it corresponds to the length Lb2 shown in Figure 3. If the length Lb of board B is equal to or less than the length L cm of the mounting conveyors 22, 23 ("YES" in step S104), then the second preparation in step S105 is executed.

Figure 11 is a flowchart showing an example of the second preparation performed in response to the remaining substrate in Figure 4, Figure 12 is a diagram showing the operations performed in the second preparation in Figure 11, Figure 13 is a flowchart showing an example of the search operation (section) performed in the second preparation in Figure 12, Figure 14 is a diagram showing the operations performed in the search operation (section) in Figure 13, Figure 15 is a flowchart showing an example of the positioning operation (section) performed in the second preparation in Figure 11, and Figure 16 is a diagram showing the operations performed in the positioning operation (section) in Figure 15.

In the second preparation shown in FIG. 11, the board transport control unit 14 divides the four conveyors 21, 22, 23, and 24 of the board transport unit 2 into multiple sections A1 and A2, so that each of the multiple sections A1 and A2 includes two or more conveyors, and performs control. In this example, the four conveyors 21, 22, 23, and 24 are divided into two sections A1 and A2, with section A1 including the standby conveyor 21 and mounting conveyor 22, and section A2 including the mounting conveyor 23 and standby conveyor 24. Of the boundaries R1, R2, and R3, the board transport control unit 14 specifically treats boundary R2, which corresponds to the boundary between sections A1 and A2, as the "section boundary," and of the boundary sensors Sr1, Sr2, and Sr3 of the board detection unit Ud, the boundary sensor Sr2, which detects board B at the boundary between sections A1 and A2, as the "section boundary sensor."

The board transport control unit 14 checks the output of the section boundary sensor Sr2 (step S501) and determines whether the output of the section boundary sensor Sr2 is off (step S502). If the output of the section boundary sensor Sr2 is on (step S502: "NO"), step S503 is executed. In the example shown in the "S501" column in Figure 12, board B is left straddling the mounting conveyor 22 in section A1 and the mounting conveyor 23 in section A2. Therefore, because the section boundary sensor Sr2 outputs on, step S502 is determined to be "NO" and the process proceeds to step S503.

In step S503, the board transport control unit 14 operates the mounting conveyors 22 and 23 upstream and downstream of the section boundary sensor Sr2 that has been confirmed to output an on signal in the forward direction X1. As a result, as shown by the arrow in the "S503" column in Figure 12, the board B that overlaps the section boundary R2 moves in the forward direction X1. In addition, as the mounting conveyor 22 operates in the forward direction X1, the board B that straddles the standby conveyor 21 and the mounting conveyor 22 also moves in the forward direction X1.

Once step S503 is executed, the process returns to step S501. That is, the output of section boundary sensor Sr2 is checked (step S501), and it is determined whether the output of section boundary sensor Sr2 is off (step S502). In the example shown in the "S501_2" column in Figure 6, board B has retreated from section boundary R2, and section boundary sensor Sr2 outputs an off signal ("YES" in step S502). Therefore, the board transport control unit 14 stops all of conveyors 21, 22, 23, and 24 (step S504).

By executing step S503 (retraction operation) in this manner, board B, which was straddling the mounting conveyor 22 in section A1 and the mounting conveyor 23 in section A2 before the start of the second preparation, is retracted in the forward direction X1 from the section boundary R2 between sections A1 and A2 ("S501_2" in Figure 12 or the "Before search operation starts" column in Figure 14).

Once steps S501 to S504, including the retraction operation (step S503), are completed, a search operation is performed (step S505). In the search operation (section) shown in FIG. 13, the board transport control unit 14 operates all of the conveyors 21, 22, 23, and 24 in the reverse direction X2 (step S601). This causes board B supported by the board transport unit 2 to move in the reverse direction X2 (arrow in the "S601" column in FIG. 14). In step S602, the board transport control unit 14 determines whether the conveyors 21 and 22 in section A1 and the conveyors 23 and 24 in section A2 have each traveled a predetermined distance. This predetermined distance is set according to the respective lengths of section A1 and section A2. For example, the predetermined distance can be a length Lcmw corresponding to the respective lengths of section A1 and section A2.

If the conveyors 21 and 22 in section A1 and the conveyors 23 and 24 in section A2 have not moved the predetermined distance ("NO" in step S602), the board transport control unit 14 determines whether board B has been detected in both sections A1 and A2 (step S603). Here, detecting board B in section A1 means that at least one of the rear end sensor Su located at the downstream end of section A1 in the reverse direction X2 and the boundary sensor Sr1 included in section A1 has detected board B, and detecting board B in section A2 means that at least one of the section boundary sensor Sr2 corresponding to the section boundary R2 downstream of section A2 in the reverse direction X2 and the boundary sensor Sr3 included in section A2 has detected board B.

In the example shown in the "S601" column of Figure 14, boundary sensor Sr1 detects substrate B in section A1, but does not detect substrate B in section A2 ("NO" in step S603), so the process proceeds to step S604. In step S604, the substrate transport control unit 14 determines whether any of sensors Su, Sr1, Sr2, and Sr3 outputs an ON signal (ON output sensor). If no ON output sensor exists ("NO" in step S604), the process returns to step S602.

On the other hand, if an ON output sensor is present (YES in step S604), the board transport control unit 14 stops the conveyor in the section corresponding to the ON output sensor (step S605). Here, the section corresponding to the trailing edge sensor Su and boundary sensor Sr1 is section A1, and the conveyors in this section A1 are the standby conveyor 21 and the mounting conveyor 22. Furthermore, the section corresponding to boundary sensor Sr2 and boundary sensor Sr3 is section A2, and the conveyors in this section A2 are the mounting conveyor 23 and the standby conveyor 24. In other words, in step S605, board B detected by the ON output sensor is stopped. Following step S605, the process returns to step S602.

In the example of "S604" in Figure 14, the boundary sensor Sr1 corresponding to section A1 outputs an ON signal, so the standby conveyor 21 and mounting conveyor 22 in section A1 are stopped. On the other hand, the boundary sensors Sr2 and Sr3 corresponding to section A2 output an OFF signal, so the mounting conveyor 23 and standby conveyor 24 in section A2 continue to operate in the reverse direction X2.

Steps S603 to S605 are
The conveyors 21 and 22 in the section A1 and the conveyors 23 and 24 in the section A2 each operate for a predetermined distance ("YES" in step S602,
Substrate B is detected in both sections A1 and A2 (YES in step S603).
On the other hand, if any of these conditions is met, all of the conveyors 21, 22, 23 and 24 are stopped in step S606, and the search operation of FIG. 13 is completed.

In the example shown in the "S604" column of Figure 14, the conveyors 21 and 22 in section A1 and the conveyors 23 and 24 in section A2 have not moved the predetermined distance ("NO" in step S602). Furthermore, board B has not been detected in section A2 ("NO" in step S603). Therefore, steps S604 to S605 are executed in the same manner as described above. As shown in the example shown in the "S604_2" column of Figure 14, when the section boundary sensor Sr2 corresponding to section A2 outputs an ON signal ("YES" in step S604), the board transport control unit 14 stops the mounting conveyor 23 and standby conveyor 24 in section A2 corresponding to the section boundary sensor Sr2, thereby stopping board B detected by the section boundary sensor Sr2 (step S605).

As a result, board B is detected in both sections A1 and A2 ("YES" in step S603), and all conveyors 21, 22, 23, and 24 are stopped (step S606), completing the search operation in Figure 13.

By executing steps S505 and S601 to S606 (search operation) in this way, each board B overlaps with a position (detection position) detected by one of sensors Su, Sr1, Sr2, and Sr3 ("S604_2" in Figure 14 or the "Before positioning operation starts" column in Figure 16).

As shown in FIG. 11, once the search operation (section) of step S505 is completed, the positioning operation (section) is executed (step S506). In the positioning operation (section) shown in FIG. 15, the substrate transport control unit 14 performs positioning in sections A1 and A2, starting from the section downstream in the forward direction X1. That is, in step S701, of sections A1 and A2, section A2, which is the most downstream in the forward direction X1, is set as the target section.

In step S702, the substrate transport control unit 14 determines whether a sensor corresponding to the target section, section A2, detects substrate B. Here, detection of substrate B for the target section A2 is performed based on the outputs of the boundary sensor Sr2 corresponding to the section boundary R2 upstream of section A2 in the forward direction X1 and the positioning sensor Sla included in section A2. That is, if at least one of the boundary sensor Sr2 and the positioning sensor Sla outputs an ON signal, step S702 determines that substrate B has been detected for the target section A2, i.e., a "YES" result, and the process proceeds to step S703. On the other hand, if both the boundary sensor Sr2 and the positioning sensor Sla output an OFF signal, step S702 determines that substrate B has not been detected for the target section A2, i.e., a "NO" result, and the process proceeds to step S708. In the example shown in the "Before Search Operation Starts" column of Figure 16, both the boundary sensor Sr2 and the positioning sensor Sla output an ON signal, so step S702 determines that substrate B has not been detected for the target section A2, i.e., a "NO" result, and the process proceeds to step S708.

In step S703, the substrate transport control unit 14 determines the target position (i.e., the position to be positioned) for substrate B. This target position is determined based on the outputs of the boundary sensor Sr2 and the positioning sensor Sla corresponding to section A2. Specifically, if the positioning sensor Sla outputs an on signal, the target position is set to a position that is a specified distance away from the boundary sensor Sr2 in the forward direction X1, based on the boundary sensor Sla. On the other hand, if the positioning sensor Sla outputs an off signal, the target position is set to a position that is a specified distance away from the positioning sensor Sla in the forward direction X1, based on the positioning sensor Sla. In the example shown in the "Before search operation begins" column in Figure 16, the positioning sensor Sla outputs an on signal, so the target position is set based on the boundary sensor Sr2.

In step S704, the board transport control unit 14 operates the mounting conveyor 23 and standby conveyor 24 in the target section A2 in the forward direction X1. As a result, the board B supported by the mounting conveyor 23 moves in the forward direction X1 (arrow in the "S704" column of Figure 16). The board transport control unit 14 also monitors changes in the output of the corresponding sensor, i.e., the boundary sensor Sr2 that was used as the basis for determining the target position in step S703 (step S705). Then, from the moment the output of the boundary sensor Sr2 changes from on to off, the board transport control unit 14 operates the mounting conveyor 23 and standby conveyor 24 in the target section A2 in the forward direction X1 a specified distance (step S706) and stops the mounting conveyor 23 and standby conveyor 24 in the target section A2 (step S707). As a result, as shown in the "S707" column of Figure 16, the board B in section A2 is positioned in the forward direction X1 at a specified distance from the boundary sensor Sr2.

In step S708, the substrate transport control unit 14 determines whether the target section is the most upstream section in the forward direction X1, i.e., section A1. In this example, the target section is section A2, not section A1 ("NO" in step S708). Therefore, in step S709, the section one section upstream, i.e., section A1, is set as the target, and the process returns to step S702.

In step S702, the board transport control unit 14 determines whether the sensor corresponding to the target section, section A1, detects board B. Here, detection of board B for the target section A1 is performed based on the outputs of the boundary sensor Sr1 included in that section A1 and the positioning sensor Slb, which detects board B supported by the mounting conveyor 22 in that section A1. That is, if at least one of the boundary sensor Sr1 and the positioning sensor Slb outputs an ON signal, step S702 determines that board B has been detected for the target section A1, i.e., a "YES" result, and the process proceeds to step S703. On the other hand, if both the boundary sensor Sr1 and the positioning sensor Slb output an OFF signal, step S702 determines that board B has not been detected for the target section A1, i.e., a "NO" result, and the process proceeds to step S708. In the example shown in the "S706" column in Figure 16, since the boundary sensor Sr1 outputs an ON signal, step S702 determines that board B has not been detected for the target section A1, i.e., a "NO" result, and the process proceeds to step S708.

In step S703, the substrate transport control unit 14 determines the target position (i.e., the position to be positioned) for substrate B. This target position is determined based on the outputs of the boundary sensor Sr1 and the positioning sensor Slb corresponding to section A1. Specifically, if the positioning sensor Slb outputs an on signal, the target position is set to a position that is a specified distance away from the boundary sensor Sr1 in the forward direction X1, based on the boundary sensor Slb. On the other hand, if the positioning sensor Slb outputs an off signal, the target position is set to a position that is a specified distance away from the positioning sensor Slb in the forward direction X1, based on the positioning sensor Slb. In the example shown in the "S706" column in Figure 16, the positioning sensor Slb outputs an off signal, so the target position is set based on the positioning sensor Slb.

In step S704, the board transport control unit 14 operates the standby conveyor 21 and mounting conveyor 22 in the target section A1 in the forward direction X1. As a result, the board B supported by the standby conveyor 21 and mounting conveyor 22 moves in the forward direction X1 (the arrow in the "S704_2" column in Figure 16). The board transport control unit 14 also monitors changes in the output of the corresponding sensor, i.e., the positioning sensor Slb that was used as the basis for determining the target position in step S703 (step S705). Then, from the moment the output of the positioning sensor Slb changes from off to on, the board transport control unit 14 operates the standby conveyor 21 and mounting conveyor 22 in the target section A1 a specified distance in the forward direction X1 (step S706) and stops the standby conveyor 21 and mounting conveyor 22 in the target section A1 (step S707). As a result, as shown in the "S707_2" column in Figure 16, board B in section A1 is positioned at a specified distance in the forward direction X1 from positioning sensor Slb.

In step S708, the substrate transport control unit 14 determines whether the target section is the most upstream section in the forward direction X1, i.e., section A1. In this example, the target section is section A1 ("YES" in step S708). Therefore, the positioning operation (section) in Figure 15 ends, and the second preparation in Figure 11 ends.

Returning to Figure 4, the explanation continues. If the length Lb of substrate B is longer than the length Lcm ("NO" in step S104), it is determined in step S106 whether the length Lb of substrate B is equal to or less than the length Lcmw, in other words, whether it corresponds to the length Lb3 shown in Figure 3. If the length Lb of substrate B is equal to or less than the length Lcmw ("YES" in step S106), the third preparation in step S107 is executed.

Figure 17 is a flowchart showing an example of the third preparation performed in response to the remaining substrate in Figure 4, and Figure 18 is a diagram showing the operations performed in the third preparation in Figure 17. The third preparation differs from the first and second preparations described above in that no evacuation operation is performed to evacuate substrate B from boundaries R1, R2, or R3. This is also true for the fourth preparation described below. In other words, the substrate transport control unit 14 essentially determines that no evacuation operation is necessary when it determines in step S104 that length Lb of substrate B is longer than length L cm.

Furthermore, in this third preparation, it is determined whether or not a search operation needs to be performed. That is, if board B has length Lb3, which is the target of the third preparation, component E is mounted on board B, which is positioned at a mounting position spanning mounting conveyors 22 and 23, as shown in the "Lb3" column in Figure 3. In response to this, in step S801 of the third preparation, the board transport control unit 14 checks the output of the central boundary sensor Sr2 corresponding to boundary R2 overlapping with the mounting position; in other words, the central boundary sensor Sr2 that detects the presence or absence of board B at that mounting position.

If the output of the central boundary sensor Sr2 is off ("NO" in step S802), the board transport control unit 14 executes the search operation (section) shown in FIG. 13 (step S802). In this case, for example, as shown in the "Before Search Operation Starts" column in FIG. 18, board B is included in at least one of sections A1 and A2 (in the example of FIG. 18, board B is located in both sections A1 and A2). Furthermore, because board B's length Lb corresponds to length Lb3, the boundary sensors Sr1 and Sr3 included in sections A1 and A2 detect board B. Therefore, when conveyors 21, 22, 23, and 24 start moving in the reverse direction X2 in step S601, boundary sensors Sr1 and Sr3 immediately output an "ON" signal ("YES" in step S604), and conveyors 21, 22, 23, and 24 in sections A1 and A2 stop (step S605).

Once the search operation (section) is completed in this manner, positioning of board B is performed in step S804. Specifically, the position of board B straddling the standby conveyor 21 and mounting conveyor 22 (upstream standby position) or the position of board B straddling the mounting conveyor 23 and standby conveyor 24 (downstream standby position) shown in the "Waiting" column of "LB3" in Figure 3 is the position closest to the position of board B confirmed by the search operation, and the positioning operation (section) of Figure 15 is performed (step S804).

On the other hand, if the output of the central boundary sensor Sr2 is on (YES in step S802), the board transport control unit 14 does not perform a search operation, but instead determines whether the downstream boundary sensor Sr3, located downstream of the mounting position in the forward direction X1, is off (step S805). If the downstream boundary sensor Sr3 is off (YES in step S805), the board transport control unit 14 performs the positioning operation (section) of FIG. 15 with the mounting position as the target position (step S806). On the other hand, if the boundary sensor Sr3 is on (NO in step S805), it can be assumed that board B was left behind during transport after component E was mounted, and therefore the board transport control unit 14 performs the positioning operation (section) of FIG. 15 with the downstream standby position as the target position (step S807). This completes the third preparation in FIG. 17.

Returning to Figure 4, we continue the explanation. If the length Lb of substrate B is longer than the length Lcmw ("NO" in step S106), the length Lb of substrate B corresponds to the length Lb4 shown in Figure 3. In this case, the fourth preparation in step S108 is performed.

Figure 19 is a flowchart showing an example of the fourth preparation performed in response to the remaining substrate in Figure 4, and Figure 20 is a diagram showing the operations performed in the fourth preparation in Figure 19. The fourth preparation also differs from the first and second preparations described above in that no evacuation operation is performed to evacuate substrate B from boundaries R1, R2, or R3.

In this fourth preparation, the board transport control unit 14 determines whether the downstream boundary sensor Sr3, located downstream of the mounting position in the forward direction X1, is off (step S901). If the downstream boundary sensor Sr3 is off (step S901: "YES"), the board transport control unit 14 executes the search operation (section) of FIG. 13 (step S902). Furthermore, the board transport control unit 14 executes the positioning operation (section) of FIG. 15, with the mounting position as the target position (step S903). As a result, board B is positioned at the position shown in the "Mounting Position" column of FIG. 20. On the other hand, if the boundary sensor Sr3 is on (step S901: "NO"), it can be assumed that board B was left behind during transport after component E was mounted. Therefore, the board transport control unit 14 executes the positioning operation (section) of FIG. 15, with the downstream standby position as the target position (step S904). As a result, board B is positioned at the position shown in the "Downstream Standby Position" column of FIG. 20. This completes the fourth preparation in Figure 19.

In the embodiment described above, whether or not a retraction operation (steps S203-S206 or step S503) is required to retract a board B spanning two conveyors (conveyors 21 and 22, conveyors 22 and 23, or conveyors 23 and 24) from the boundary (boundary R1, boundary R2, or boundary R3) is required is determined based on the length Lb of the board B in the board transport direction X (arrangement direction) and the detection results of the board B by the boundary sensor Sr1, Sr2, or Sr3 (steps S102, S104, steps S201-S202, or steps S501-S502). Therefore, depending on the determination of whether or not the retraction operation is required, an operation can be performed to retract the board B from the boundary R1, R2, or R3 between the two conveyors 21 and 22, 22 and 23, or 23 and 24. In this way, it is possible to accommodate boards B that are left straddling two adjacent conveyors 21 and 22, 22 and 23, or 23 and 24.

Furthermore, if the length Lb of the board B is shorter than the length Lcm, Lcm, or Lcw in the board conveyance direction X of the downstream conveyor 22, 23, or 24 in the forward direction X1 (first direction) of the two conveyors 21 and 22, 22 and 23, or 23 and 24, and the boundary R1, R2, or R3 detects the board B, the control unit 10 (controller) determines that a retraction operation is necessary (steps S102 to S105). This allows the board B remaining across the two conveyors 21 and 22, 22 and 23, or 23 and 24 to be moved to the downstream conveyor 22, 23, or 23 and 24 in the forward direction X1, and to be retracted from the boundary R1, R2, or R3 between the two conveyors 21 and 22, 22 and 23, or 23 and 24. In this way, it is possible to accommodate boards B that are left straddling two adjacent conveyors 21 and 22, 22 and 23, or 23 and 24.

The control unit 10 also divides the four conveyors 21, 22, 23, and 24 into multiple sections A1 and A2, each having a length greater than or equal to one and less than two times the length Lb of the board B in the board transport direction X, so that each section A1 and A2 includes two or more conveyors 21, 22, 23, and 24. The control unit 10 then determines that a retraction operation to retract the board B from the boundaries R1 and R3 included in the sections A1 and A2 is unnecessary. That is, in the second preparation shown in FIG. 11, no retraction operation is performed regardless of the output of the boundary sensors Sr1 and Sr3 corresponding to the boundaries R1 and R3. Meanwhile, the control unit 10 determines whether a retraction operation to retract the board B from the section boundary R2, which is the boundary R2 sandwiched between two adjacent sections A1 and A2, is necessary based on the detection result of the board B by the boundary sensor Sr2 positioned corresponding to the section boundary R2 (steps S501-S502). This configuration functions effectively when one substrate is supported per section A1 (the case of the "Lb2" column in Figure 3). In other words, in such a case, even if substrate B straddles boundary R1 or R3 included in section A1 or A2, there is no need to retract substrate B from said boundary R1 or R3. On the other hand, if substrate B straddles section boundary R2, which is the boundary R2 sandwiched between two adjacent sections A1 and A2, substrate B must be retracted from said section boundary R2. In contrast, this configuration makes it possible to accurately determine whether a retraction operation is necessary.

Furthermore, if the control unit 10 determines that a retraction operation is necessary, it performs a search operation (steps S208, S505) to search for a conveyor supporting board B from among conveyors 21, 22, 23, and 24, after performing the retraction operation (steps S206, S503). On the other hand, if the control unit 10 determines that a retraction operation is not necessary, it performs a search operation (steps S208, S505, S803) without performing the retraction operation. With this configuration, the retraction operation (steps S206, S503) is performed depending on whether it is necessary, preventing overdetection of board B during the search operation (steps S208, S505, S803).

In addition, a trailing edge sensor Su (upstream sensor) is provided to detect board B at the upstream end of conveyors 21, 22, 23, and 24 in the forward direction X1. In response, the control unit 10 determines the presence or absence of board B on conveyors 21, 22, 23, and 24 based on the detection results of board B by boundary sensors Sr1, Sr2, and Sr3 and trailing edge sensor Su when conveyors 21, 22, 23, and 24 are operated in the reverse direction X2 (second direction), thereby performing a search operation (steps S303-S304, steps S603-S604). With this configuration, board B can be detected by boundary sensors Sr1, Sr2, and Sr3 and trailing edge sensor Su, allowing for rapid execution of the search operation (steps S208, S505, S803).

The control unit 10 also performs a search operation (steps S208, S505, S803) by detecting the downstream edge of the substrate B in the reverse direction X2 using boundary sensors Sr1, Sr2, Sr3 and trailing edge sensor Su. With this configuration, the boundary sensors Sr1, Sr2, Sr3 and trailing edge sensor Su detect the edge of the substrate B, allowing the search operation (steps S208, S505, S803) to be performed quickly.

The control unit 10 also produces multiple component-mounted boards by sequentially loading multiple boards B on conveyors 21, 22, 23, and 24 and mounting components E onto the loaded boards B using the mounting head 31. In response to this, the control unit 10 performs a search operation before the start or interruption of production of multiple component-mounted boards (step S101). With this configuration, it is possible to search for boards B left on conveyors 21, 22, 23, and 24 before the start or interruption of board production.

Furthermore, the control unit 10 determines that the retraction operation to retract the board B from the boundary R1, R2, or R3 is unnecessary if the length Lb of the board B is longer than the length in the board transport direction X of the conveyor 22, 23, or 24 downstream in the forward direction X1, out of the two conveyors 21 and 22, 22 and 23, or 23 and 24. In other words, if the determination in step S104, which determines whether the length Lb is equal to or less than the length L cm, is "NO," the retraction operation is not performed. With this configuration, it is possible to accurately determine whether the retraction operation is necessary.

Furthermore, the length Lcm between the two ends of the two mounting conveyors 22 and 23 in the board transport direction X is longer than the length Lb of the board B, and the board B on which components E are mounted by the mounting head 31 is supported between the two ends of the two mounting conveyors 22 and 23. In response to this, the control unit 10 determines whether a search operation (step S803) is required to search for boards B remaining on the conveyors 21, 22, 23, and 24, based on the detection result of the board B by the boundary sensor Sr2 (steps S801-S802). This configuration allows for accurate determination of whether a search operation (step S803) is required.

Furthermore, the two mounting conveyors 22 and 23 are provided with a boundary sensor Sr1 (upstream sensor) that detects board B upstream in the forward direction X1, and a boundary sensor Sr3 (downstream sensor) that detects board B downstream in the forward direction X1. The board transport control unit 14 determines the presence or absence of board B on the conveyors 21, 22, 23, and 24 based on the detection results of board B by the boundary sensors Sr1 and Sr3 when the conveyors 21, 22, 23, and 24 are operated in the reverse direction X2 (step S803). With this configuration, board B can be detected by the boundary sensors Sr1 and Sr3, allowing the search operation (step S803) to be performed quickly.

Furthermore, if the boundary sensor Sr2 detects board B, the control unit 10 determines that the search operation (step S803) is unnecessary, and if the boundary sensor Sr2 does not detect board B, the control unit 10 determines that the search operation (step S803) is necessary (step S802). With this configuration, it is possible to accurately determine whether the search operation (step S803) is necessary.

The two mounting conveyors 22 and 23 are also provided with a boundary sensor Sr3 (downstream sensor) that detects boards B downstream in the forward direction X1. The length Lcm between the two ends of the two mounting conveyors 22 and 23 in the board transport direction X is longer than the length Lb of the board B, and the board B on which components E are mounted by the mounting head 31 is supported between the ends of the two mounting conveyors 22 and 23. The control unit 10 then determines whether a search operation (step S902) is required to search for boards B remaining on the conveyors 21, 22, 23, and 24 based on the detection result of the board B by the boundary sensor Sr3 (step S901). This configuration allows for accurate determination of whether a search operation (step S902) is required.

Furthermore, if the boundary sensor Sr3 detects board B ("NO" in step S301), the control unit 10 determines that a search operation is unnecessary, and if the boundary sensor Sr3 does not detect board B ("YES" in step S901), the control unit 10 determines that a search operation is necessary (step S901). With this configuration, it is possible to accurately determine whether a search operation (step S902) is necessary.

The control unit 10 also produces multiple component-mounted boards by sequentially loading multiple boards B on conveyors 21, 22, 23, and 24 and mounting components E onto the loaded boards B using the mounting head 31. The control unit 10 then determines whether a search operation is required before starting or interrupting production of multiple component-mounted boards (steps S101, S802, S901). With this configuration, it is possible to search for boards B remaining on conveyors 21, 22, 23, and 24 before starting or interrupting board production.

The control unit 10 also performs a retraction operation by operating the two conveyors 21 and 22, 22 and 23, or 23 and 24 in the forward direction X1 until the boundary sensor Sr1, Sr2, or Sr3 no longer detects the board B (steps S206, S503). This configuration retracts a board B that is left straddling two conveyors 21 and 22, 22 and 23, or 23 and 24 from the boundary R1, R2, or R3 between the two conveyors 21 and 22, 22 and 23, or 23 and 24. In this way, it is possible to deal with a board B that is left straddling two adjacent conveyors 21 and 22, 22 and 23, or 23 and 24.

As explained above, in this embodiment, the component mounter 1 corresponds to an example of a "component mounting system" of the present invention, the control unit 10 corresponds to an example of a "control unit" of the present invention, the four conveyors 21, 22, 23, and 24 correspond to an example of "N conveyors" of the present invention, the mounting head 31 corresponds to an example of a "mounting head" of the present invention, the board B corresponds to an example of a "board" of the present invention, the component E corresponds to an example of a "component" of the present invention, the board transport direction X corresponds to an example of an "arrangement direction" of the present invention, the forward direction X1 corresponds to an example of a "first direction" of the present invention, the reverse direction X2 corresponds to an example of a "second direction" of the present invention, each of the boundary sensors Sr1, Sr2, and Sr3 corresponds to an example of a "boundary sensor" of the present invention, the boundary sensor Sr1 corresponds to an example of an "upstream sensor" of the present invention, the boundary sensor Sr3 corresponds to an example of a "downstream sensor" of the present invention, the rear end sensor Su corresponds to an example of an "upstream sensor" of the present invention, and the positioning sensors Sla and Slb each correspond to an example of a "positioning sensor" of the present invention.

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 invention. For example, the number N of conveyors provided in the board transport unit 2 is not limited to four, but may be two or more.

Furthermore, the number of component mounters 1 that make up the component mounting system is not limited to one. For example, a component mounting system may be configured by arranging two component mounters 1 in series.

Furthermore, the direction in which substrate B is transported during the retraction operation is not limited to the forward direction X1, but may also be the reverse direction X2. Furthermore, if the direction in which substrate B is transported during the retraction operation is changed, the direction in which substrate B is transported during the search operation and positioning operation can be changed accordingly.

The board transport unit 2 shown in Figures 10 and 16 is also equipped with a positioning sensor Slb or Sla that detects board B between both ends of the mounting conveyor 22 or 23 in the forward direction X1. Therefore, the control unit 10 may perform a search operation by determining the presence or absence of board B on the conveyors 21, 22, 23, and 24 based on the detection result of board B by positioning sensor Slb or Sla when the conveyors 21, 22, 23, and 24 are operated in the reverse direction X2. For example, in the search operation of Figure 7, if positioning sensor Slb or Sla outputs an ON signal in step S304, the mounting conveyor 22 or 23 corresponding to positioning sensor Slb or Sla can be stopped in step S305. With this configuration, board B can be detected by positioning sensors Slb and Sla, allowing the search operation to be performed quickly.

At this time, the control unit 10 can perform a search operation by detecting the downstream edge of the substrate B in the reverse direction X2 using the positioning sensors Slb and Sla. With this configuration, the positioning sensors Slb and Sla can detect the edge of the substrate B, allowing the search operation to be performed quickly.

1...Component mounting machine (component mounting system)
10...Control unit (control section)
21... Standby conveyor 22... Mounting conveyor 23... Mounting conveyor 24... Standby conveyor 31... Mounting head B... Board E... Component X... Board transport direction (arrangement direction)
X1...Forward direction (first direction)
X2...Reverse direction (second direction)
Sr1: Boundary sensor (upstream sensor)
Sr2: Boundary sensor Sr3: Boundary sensor (downstream sensor)
Su...Rear end sensor (upstream sensor)
Sla... Positioning sensor Slb... Positioning sensor

Claims (18)

N conveyors (N is an integer of 2 or more) arranged in a predetermined arrangement direction and configured to transport substrates in a first direction parallel to the arrangement direction and a second direction opposite to the first direction;
a mounting head that mounts components onto the board supported by the conveyor;
a boundary sensor provided corresponding to a boundary between two adjacent conveyors and configured to detect the substrate at the boundary;
A component mounting system comprising: a control unit that operates the two conveyors in the first direction to transport the board in the first direction, and determines whether or not an evacuation operation is necessary to move the board spanning the two conveyors away from the boundary, based on the length of the board in the arrangement direction and the detection result of the board by the boundary sensor. The component mounting system described in claim 1, wherein the control unit determines that the retraction operation is necessary when the length of the board in the arrangement direction is shorter than the length of the conveyor downstream in the first direction of the two conveyors and the boundary sensor detects the board. N is 4 or more,
The control unit divides the N conveyors into a plurality of sections, each having a length greater than or equal to 1 time but less than 2 times the length of the board in the arrangement direction, so that each section includes two or more conveyors, and determines that the evacuation operation to evacuate the board from the boundary included in the section is unnecessary, while determining whether or not the evacuation operation to evacuate the board from the section boundary, which is the boundary between two adjacent sections, is necessary based on the detection result of the board by the boundary sensor arranged corresponding to the section boundary. The component mounting system of any one of claims 1 to 3, wherein the control unit, when determining that the retraction operation is necessary, performs a search operation to search for a conveyor supporting the board from among the N conveyors after performing the retraction operation, while, when determining that the retraction operation is unnecessary, performs the search operation without performing the retraction operation. further comprising an upstream sensor for detecting the substrate at an upstream end of the N conveyors in the first direction;
The component mounting system of claim 4, wherein the control unit performs the search operation by determining whether or not the substrate is present on the N conveyors based on the detection results of the substrate from the boundary sensor and the upstream sensor when the N conveyors are operated in the second direction. The component mounting system described in claim 5, wherein the control unit performs the search operation by detecting the downstream edge of the substrate in the second direction using the boundary sensor or the upstream sensor. a positioning sensor for detecting the substrate between both ends of the conveyor in the first direction;
The component mounting system of claim 4, wherein the control unit performs the search operation by determining whether or not the substrate is present on the N conveyors based on the detection results of the substrate by the positioning sensor when the N conveyors are operated in the second direction. The component mounting system described in claim 7, wherein the control unit performs the search operation by detecting the edge of the substrate downstream in the second direction using the positioning sensor. the control unit sequentially carries in a plurality of boards using the N conveyors, and mounts the components on the carried-in plurality of boards using the mounting heads, thereby producing a plurality of component-mounted boards;
The component mounting system according to claim 4 , wherein the control unit executes the search operation before the start of or when the production of the plurality of component-mounted boards is interrupted. The component mounting system described in claim 1, wherein the control unit determines that the retraction operation to retract the board from the boundary is unnecessary when the length of the board in the arrangement direction is longer than the length of the conveyor downstream in the first direction of the two conveyors. a length between both ends of the two conveyors in the arrangement direction is longer than a length of the board, and the board on which the components are mounted by the mounting head is supported between both ends of the two conveyors;
The component mounting system according to claim 10 , wherein the control unit determines whether or not a search operation for searching for the boards left on the N conveyors is necessary based on a detection result of the boards by the boundary sensor. an upstream sensor that detects the substrate on the upstream side in the first direction with respect to the two conveyors;
a downstream sensor that detects the substrate downstream in the first direction with respect to the two conveyors,
The component mounting system of claim 11, wherein the control unit performs the search operation by determining whether or not the substrate is present on the N conveyors based on the detection results of the substrate from each of the upstream sensor and the downstream sensor when the N conveyors are operated in the second direction. The component mounting system described in claim 11, wherein the control unit determines that the search operation is unnecessary when the boundary sensor detects the board, and determines that the search operation is necessary when the boundary sensor does not detect the board. a downstream sensor for detecting the substrate downstream in the first direction with respect to the two conveyors;
a length between both ends of the two conveyors in the arrangement direction is longer than a length of the board, and the board on which the components are mounted by the mounting head is supported between both ends of the two conveyors;
The component mounting system according to claim 10 , wherein the control unit determines whether or not a search operation for searching for the boards left on the N conveyors is necessary based on a detection result of the boards by the downstream sensor. The component mounting system described in claim 14, wherein the control unit determines that the search operation is unnecessary when the downstream sensor detects the board, and determines that the search operation is necessary when the downstream sensor does not detect the board. the control unit sequentially carries in a plurality of boards using the N conveyors, and mounts the components on the carried-in plurality of boards using the mounting heads, thereby producing a plurality of component-mounted boards;
The component mounting system according to claim 11 , wherein the control unit determines whether the search operation is necessary before production of the plurality of component-mounted boards is started or when the production is interrupted. The component mounting system described in claim 1, wherein the control unit performs the retraction operation by operating the two conveyors in the first direction until the boundary sensor no longer detects the board. a step of determining whether or not a retraction operation is required to retract the substrate from a boundary between two adjacent conveyors in N conveyors (N is an integer of 2 or more) that are arranged in a predetermined arrangement direction and transport the substrate in a first direction parallel to the arrangement direction and a second direction opposite to the first direction;
and when it is determined that the evacuation operation is necessary, executing the evacuation operation;
A substrate transport control method in which the need for the retraction operation is determined based on the detection result of the substrate by a boundary sensor that is provided corresponding to the boundary between two adjacent conveyors and detects the substrate at the boundary, and the length of the substrate in the arrangement direction.