Marking system

Abstract

To provide a marking system that can surely suppress a laser beam outputted from a laser marking device from leaking out.SOLUTION: A marking system 1 comprises shielding door groups 4 and 5, arranged at an upstream side and at a downstream side of a conveyance path in an enclosure 3 with respect to a marking position M, which shield a laser beam L emitted from a laser marking device 2. The shielding door groups 4 and 5 have a plurality of shielding doors 10 and 20 arranged at different positions in a conveying direction of a PET bottle P that is conveyed along the conveyance path. The plurality of shielding doors 10 and 20 respectively are overlappingly arranged when viewed from the conveying direction, and are arranged to overlap with at least a portion of the PET bottle P. It is configured that at least one shielding door of the plurality of shielding doors 10 and 20 opens to enable the PET bottle P to pass therethrough and the other shielding door closes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a marking system. [Background technology]

[0002] In the beverage manufacturing process, efforts are being made to eliminate labels on PET bottles in order to reduce label resources and simplify recycling.

[0003] For example, Patent Document 1 describes a laser marking device that uses a laser beam to directly form information such as numbers, letters, and images on the surface of a PET bottle. Patent Document 1 also describes a configuration in which the laser marking device is covered with a safety cover to prevent workers around the device from being irradiated with the laser beam output by the laser marking device and suffering from burns or other harm.

[0004] Furthermore, Patent Document 1 describes a configuration in which PET bottles are transported by a transport device such as a conveyor, and a configuration in which a safety cover has an entrance / exit provided along the transport direction of the transport device. These entrances are provided with a configuration in which a number of strip-shaped members having a predetermined width, length, and plasticity hang down vertically as elements to prevent laser light from leaking to the outside. Patent Document 1 also describes a configuration in which, as another example of a laser light leakage prevention means, the entrance / exit of the safety cover is provided with a set of doors that can swing like a double door or a door that can swing in one direction. Summary of the Invention [Problem to be solved by the invention]

[0005] However, with conventional laser light leakage prevention means, when a PET bottle, as an example of a transported item, enters or exits through the entrance of the safety cover, part of the entrance opens, leaving room for improvement in terms of preventing the laser light from leaking to the outside.

[0006] An object of the present invention is to more reliably prevent the laser light output from a laser marking device from leaking to the outside. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a marking system according to one aspect of the present invention comprises a laser marking device that uses laser light to mark transported objects transported along a transport path, an enclosure that is installed to cover a marking position on the transport path where marking is performed by the laser marking device, a portion of the transport path that includes a plurality of the transported objects, and the laser marking device, and a group of shielding doors that are arranged within the enclosure on at least one of the upstream and downstream sides of the transport path relative to the marking position and that shield the laser light emitted from the laser marking device, wherein the group of shielding doors has a plurality of shielding doors that are arranged at different positions in the transport direction of the transported objects transported along the transport path, and the plurality of shielding doors are arranged so as to overlap each other when viewed from the transport direction and so as to overlap at least a portion of the transported objects, and at least one of the plurality of shielding doors is configured to open to allow the transported objects to pass, while the other shielding doors are closed. [Effects of the Invention]

[0008] This makes it possible to more reliably prevent the laser light output from the laser marking device from leaking to the outside. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a marking system according to an embodiment. [Figure 2] FIG. 10 is a diagram showing an example of a shielding door opening and closing mechanism. [Figure 3] A diagram showing the opening and closing operation of the shielding door shown in Figure 2. [Figure 4] A diagram showing the relationship between the flow of plastic bottles on the belt conveyor and the open / closed state of the shielding door [Figure 5] Diagram showing the relationship between bottle pitch and installation interval of shielding doors [Figure 6] A diagram showing the relationship between the transport speed of the PET bottles and the opening and closing speed of the shielding door. [Figure 7] FIG. 1 is a diagram illustrating an example of a hardware configuration of a control unit. [Figure 8] FIG. 10 is a diagram showing a schematic configuration of a shielding door according to a first modified example. [Figure 9] A diagram showing the first example of a light leakage prevention structure applied to a vertical sliding type shielding door. [Figure 10] A diagram showing a second example of a light leakage prevention structure applied to a vertical sliding type shielding door. [Figure 11] A diagram showing a third example of a light leakage prevention structure applied to a vertical sliding type shielding door. [Figure 12] FIG. 10 is a diagram showing a schematic configuration of a shielding door according to a second modified example. [Figure 13] FIG. 10 is a diagram showing a schematic configuration of a shielding door according to a third modified example. [Figure 14] FIG. 14 is a diagram showing a schematic configuration of an upstream shielding door group to which the shielding door shown in FIG. 13 is applied. [Figure 15] FIG. 10 is a diagram showing a schematic configuration of a shielding door according to a fourth modified example and a shielding door according to a fifth modified example. [Figure 16] FIG. 13 is a diagram showing a schematic configuration of a shielding door according to a sixth modified example. [Figure 17] FIG. 13 is a diagram showing a schematic configuration of a shielding door according to a seventh modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the accompanying drawings. To facilitate understanding of the description, the same components in the drawings will be denoted by the same reference numerals as much as possible, and duplicated descriptions will be omitted.

[0011] In the following description, the X, Y, and Z directions are perpendicular to each other. The X and Y directions are horizontal, and the Z direction is vertical. The X direction is the conveying direction of PET bottles P as an example of the conveyed object, with the negative X direction being the upstream side of the conveying direction and the positive X direction being the downstream side. The Y direction is the width direction of the belt conveyor 6, which is perpendicular to the conveying direction. For ease of explanation, the positive Z direction may also be referred to as the upper side and the negative Z direction as the lower side. Other examples of conveyed objects include preforms that are the prototypes of PET bottles P that can be laser-processed, containers made of resin (such as food), glass products, and labels attached to products.

[0012] Fig. 1 is a diagram showing a schematic configuration of a marking system 1 according to an embodiment, in which Fig. 1(A) is a plan view seen from the Z positive direction side, and Fig. 1(B) is a side view seen from the X negative direction side.

[0013] As shown in FIG. 1, the marking system 1 includes a laser marking device 2, an enclosure 3, a group of entrance-side shielding doors 4, a group of exit-side shielding doors 5, and a belt conveyor 6.

[0014] The belt conveyor 6 is an example of a conveying device that places plastic bottles P, as an example of an object to be conveyed, on a placement surface and conveys them along a conveying direction. The belt conveyor 6 rotates and drives rollers 61 (see FIG. 2(B), etc.) to move a belt 62 wound around the rollers 61 in the conveying direction. When the conveying device is the belt conveyor 6, the placement surface is the surface of the belt 62 arranged above the belt conveyor 6. The belt conveyor 6 extends along the X direction, and can move plastic bottles P placed on the belt 62 along a conveying path from the negative X direction side to the positive X direction side.

[0015] The laser marking device 2 uses a laser beam L to mark the surface of a plastic bottle P conveyed along a conveying path by a belt conveyor 6. For example, as shown in FIG. 1, the laser marking device 2 is positioned on the negative Y-axis side of the belt conveyor 6 and is installed to irradiate the laser beam L in the positive Y-axis direction. This allows the laser marking device 2 to mark the surface of the plastic bottle P1 at the marking position M, where the plastic bottle P conveyed in the X-axis direction on the belt conveyor 6 intersects with the direction of irradiation of the laser beam L in the Y-axis direction. While the laser marking device 2 marks the surface of the plastic bottle P by processing a concave-convex pattern, other processing methods may also be used. The processing may be performed by changing the properties of the base material, including, for example, melting, evaporating, crystallizing, or foaming the base material. Depending on the target, a through hole may also be used. The processing location may be the interior (inside) of the plastic bottle P.

[0016] The enclosure 3 is a light-shielding element for preventing the laser light L emitted from the laser marking device 2 from leaking to the outside. The enclosure 3 is installed to cover a portion of the placement surface of the belt conveyor 6, including the marking position M and an area where multiple PET bottles P are placed upstream and downstream of the marking position M, the laser marking device 2, the entrance-side shielding door group 4, and the exit-side shielding door group 5. In FIG. 1, the closed space formed by the enclosure 3 is illustrated by a gray area. The enclosure 3 has an entrance 31 opened at the most upstream position of the portion covering the belt conveyor 6, for introducing the PET bottles P on the belt conveyor 6 into the closed space. Meanwhile, an exit 32 opened at the most downstream position of the portion covering the belt conveyor 6, for discharging the PET bottles P on the belt conveyor 6 from the closed space.

[0017] The entrance-side shielding door group 4 is an element for preventing the laser light L from leaking to the outside from the entrance of the transport path of the enclosure 3. The entrance-side shielding door group 4 is arranged on the upstream side of the transport path within the enclosure 3 with respect to the marking position M, and blocks the laser light L emitted from the laser marking device 2.

[0018] The exit-side shielding door group 5 is an element for preventing the laser light L from leaking to the outside from the exit of the transport path of the enclosure 3. The exit-side shielding door group 5 is arranged downstream of the transport path within the enclosure 3 with respect to the marking position M, and shields the laser light L emitted from the laser marking device 2. Note that the shielding doors of the entrance-side shielding door group 4 and the exit-side shielding door group 5 are not limited to those that provide complete light blocking, but also include those that can sufficiently absorb and reduce the amount of light (brightness) to the extent that they do not affect the outside.

[0019] In particular, in this embodiment, the entrance-side shielding door group 4 has a plurality of shielding doors 10 arranged at different positions in the conveying direction (i.e., different positions in the X direction) of the PET bottles P conveyed along the conveying path. In the example of Fig. 1, the entrance-side shielding door group 4 has two sets of shielding doors as the plurality of shielding doors 10: a first shielding door 10-1 on the upstream side and a second shielding door 10-2 on the downstream side.

[0020] The first shielding door 10-1 and the second shielding door 10-2 are arranged so as to overlap each other when viewed from the conveyance direction and so as to overlap at least a portion of the PET bottle P. One of the first shielding door 10-1 and the second shielding door 10-2 is open to allow the PET bottle P to pass, while the other shielding door is closed. In the example of FIG. 1(A), the second shielding door 10-2 on the downstream side is open to allow the PET bottle P to pass, but at the same time the first shielding door 10-1 on the upstream side is closed. As a result, as shown in FIG. 1(B), the PET bottle P1 passing through the marking position M is completely shielded by the first shielding door 10-1, so that it is always kept invisible from the outside on the entrance 31 side of the enclosure 3. Therefore, as shown in Figure 1(A), both the direct light L11 irradiated from the PET bottle P1 to the upstream side in the conveying direction by the laser light L irradiated onto the PET bottle P1 at the marking position M and the reflected light L21 which travels in a direction different from the conveying direction after passing through the PET bottle P1 and is reflected by the inner wall of the enclosure 3, etc., and irradiated upstream in the conveying direction are blocked by the first shielding door 10-1 of the entrance side shielding door group 4, preventing leakage to the outside.

[0021] 1(A), when the first shielding door 10-1 opens, the second shielding door 10-2 of the entrance-side shielding door group 4 closes. In this case, the plastic bottle P1 passing through the marking position M is completely shielded by the second shielding door 10-2, so that it is always kept invisible from the outside on the entrance 31 side of the enclosure 3. Therefore, similar to the example of FIG. 1(A), both the direct light L11 and the reflected light L21 of the laser light L irradiated onto the plastic bottle P1 at the marking position M are shielded by the second shielding door 10-2 of the entrance-side shielding door group 4, preventing leakage to the outside.

[0022] The entrance-side shielding door group 4 may be configured to have three or more sets of shielding doors 10. In this case, at least one of the multiple shielding doors 10 is configured to open to allow the PET bottle P to pass through, and the remaining shielding doors are configured to close. Therefore, even in this configuration, leakage of the laser light L to the outside can be prevented. Also, there may be cases where all of the multiple shielding doors 10 are closed, and in this case, leakage of the laser light L to the outside can naturally be prevented. In short, the entrance-side shielding door group 4 is configured so that a state in which all of the multiple shielding doors 10 are open is not created.

[0023] Similarly, the exit-side shielding door group 5 has a plurality of shielding doors 20 arranged at different positions in the conveying direction (i.e., different positions in the X direction) of the PET bottles P conveyed along the conveying path. In the example of Fig. 1, the exit-side shielding door group 5 has two sets of shielding doors as the plurality of shielding doors 20: a first shielding door 20-1 on the upstream side and a second shielding door 20-2 on the downstream side.

[0024] The first shielding door 20-1 and the second shielding door 20-2 are arranged so as to overlap each other when viewed from the conveyance direction and so as to overlap at least a portion of the PET bottle P. One of the first shielding door 20-1 and the second shielding door 20-2 is open to allow the PET bottle P to pass, while the other shielding door is closed. In the example of FIG. 1(A), the first shielding door 20-1 on the upstream side is open to allow the PET bottle P to pass, while at the same time the second shielding door 20-2 on the downstream side is closed. As a result, the PET bottle P1 passing through the marking position M is completely shielded by the second shielding door 20-2, and is therefore always kept invisible from the outside on the exit 32 side of the enclosure 3. Therefore, as shown in Figure 1(A), both the direct light L12 irradiated downstream in the conveying direction from the PET bottle P1 by the laser light L irradiated onto the PET bottle P1 at the marking position M and the reflected light L22 which travels in a direction different from the conveying direction after passing through the PET bottle P1 and is reflected by the inner wall of the enclosure 3, etc., and irradiated downstream in the conveying direction are blocked by the second shielding door 20-2 of the exit side shielding door group 5, preventing leakage to the outside.

[0025] 1(A), when the second shielding door 20-2 opens, the first shielding door 20-1 of the exit-side shielding door group 5 closes. In this case, the plastic bottle P1 passing through the marking position M is completely shielded by the first shielding door 20-1, and is therefore always kept invisible from the outside on the exit 32 side of the enclosure 3. Therefore, similar to the example of FIG. 1(A), both the direct light L12 and the reflected light L22 of the laser light L irradiated onto the plastic bottle P1 at the marking position M are shielded by the first shielding door 20-1 of the exit-side shielding door group 5, preventing leakage to the outside.

[0026] The exit-side shielding door group 5 may also be configured to have three or more sets of multiple shielding doors 20. In this case, at least one of the multiple shielding doors 20 is configured to open to allow the PET bottle P to pass through, and the remaining shielding doors are configured to close. Therefore, even in this configuration, leakage of the laser light L to the outside can be prevented. In addition, there may be cases where all of the multiple shielding doors 20 are closed, and in this case, leakage of the laser light L to the outside can naturally be prevented. In short, the exit-side shielding door group 5 is configured so that a state in which all of the multiple shielding doors 20 are open is not created.

[0027] Fig. 2 is a diagram showing an example of an opening and closing mechanism for the shielding door 10. Fig. 2(A) is a plan view seen from the Z positive direction side, Fig. 2(B) is a side view seen from the Y negative direction side, and Fig. 2(C) is a side view seen from the X negative direction side. Note that Fig. 2 illustrates the configuration of the shielding door 10 of the entrance side shielding door group 4, but the opening and closing mechanism for the shielding door 20 of the exit side shielding door group 5 is similar.

[0028] The shielding door 10 is arranged to be slidable in a direction (Y direction) perpendicular to the conveying direction, and includes two sliding doors 17 and 18 arranged side by side in the sliding direction.

[0029] The arrangement direction of the doors 17 and 18 is at least a direction that intersects with the conveying direction, and it is sufficient that the PET bottles P can pass to the downstream side of the belt conveyor 6 when they move away from each other, and it may be a direction other than perpendicular to the conveying direction.

[0030] The shielding door 10 has an upstream detection unit 11, a downstream detection unit 12, a control unit 13, a motor 14, a power transmission unit 15, and a door support unit 16 as an opening and closing mechanism.

[0031] The upstream detection unit 11 is provided upstream of the shielding door 10 in the conveying direction and detects the passage of the PET bottle P. In other words, the upstream detection unit 11 can detect the movement of the PET bottle P from the upstream side in the conveying direction to the position of the shielding door 10.

[0032] On the other hand, the downstream detection unit 12 is provided downstream of the shielding door 10 in the conveying direction and detects the passage of the PET bottle P. In other words, the downstream detection unit 12 can detect the movement of the PET bottle P from the position of the shielding door 10 to the downstream side in the conveying direction.

[0033] For example, a transmission sensor can be used as the upstream detector 11 and the downstream detector 12. In this case, each detector 11, 12 is configured such that a light projector and a light receiver are disposed on both sides of the width of the belt conveyor 6 at the same position in the conveying direction, and a light beam is irradiated from the light projector to the light receiver along the width at a height position above the top surface of the belt 62. The height position of the light beam can be set arbitrarily depending on the height of the transported object. Each detector 11, 12 can detect the passage of a plastic bottle P when the plastic bottle P interrupts the light beam between the light projector and the light receiver.

[0034] The motor 14 is a drive source for opening and closing the shielding door 10. The power transmission unit 15 is a group of elements that transmits the power output from the motor 14 to the shielding door 10.

[0035] The control unit 13 controls the opening and closing operation of the shielding door 10. The control unit 13 opens and closes the shielding door using the motor 14 and the power transmission unit 15 based on detection information of the PET bottle P input from the upstream detection unit 11 and the downstream detection unit 12. When the upstream detection unit 11 detects the PET bottle P, the control unit 13 opens the shielding door 10, and when the downstream detection unit 12 detects the PET bottle P, the control unit 13 closes the shielding door 10.

[0036] When the type of shielding door 10 is a sliding door as exemplified in Fig. 2, as shown in Figs. 2(A) and (C), the conveying path is arranged so that the plastic bottle P passes through the middle part of the two doors 17, 18. In this case, the two doors 17, 18 of the shielding door 10 can open by moving in directions away from each other (in the example of Fig. 2, door 17 is on the negative Y direction side and door 18 is on the positive Y direction side), allowing the plastic bottle P to pass through.

[0037] Furthermore, after the PET bottle P has passed, the doors 17 and 18 close by moving in directions that bring them closer to each other (in the example of FIG. 2, door 17 moves toward the positive Y direction and door 18 moves toward the negative Y direction). At this time, as shown in FIG. 2(A), for example, the end of door 17 on the positive Y direction side and the end of door 18 on the negative Y direction side move to the center in the width direction of the belt conveyor 6, and the two ends overlap when viewed from the X direction. This more reliably prevents the laser beams L11 and L21 from leaking outward from the shielding door 10 across the entire width of the shielding door 10.

[0038] The power transmission unit 15 includes a drive roller 15A, a driven roller 15B, a timing belt 15C, and first connecting portions 15D and 15E. The first connecting portions 15D and 15E connect the doors 17 and 18 to the timing belt 15C. The timing belt 15C is wound around the drive roller 15A and the driven roller 15B. The drive roller 15A and the driven roller 15B are arranged parallel to each other at approximately the same height in the Z direction. Therefore, the timing belt 15C stretched between the rollers 15A and 15B has a lower flat portion 15C1 and an upper flat portion 15C2. The first connecting portions 15D and 15E are connected to the timing belt 15C at the flat portions 15C1 and 15C2, respectively.

[0039] The door support part 16 is fixed in an arch shape above the placement surface of the belt conveyor 6. The door support part 16 has a pair of pillar parts 16A, 16B erected on both sides in the width direction of the belt conveyor 6, and a beam part 16C suspended in the Y direction between the pillar parts 16A, 16B. Slide rails 16D, 16E are installed on the beam part 16C to which second connecting parts 17A, 17B provided on the doors 17, 18 are slidably connected, respectively.

[0040] In this way, each door 17, 18 of the shielding door 10 is connected to the door support part 16. The door support part 16 does not move in the conveying direction when the PET bottles P are conveyed. The doors 17, 18 are installed so as to move along slide rails 16D, 16E installed on the door support part 16. In other words, the shielding door 10 is a left-right sliding door type.

[0041] A timing belt 15C is installed above the doors 17 and 18. The timing belt 15C can be moved forward and backward in the Y direction by the motor 14. At this time, the lower flat portion 15C1 and the upper flat portion 15C2 of the timing belt 15C move in opposite directions. The left and right doors 17 and 18 are connected to the timing belt 15C at the flat portions 15C1 and 15C2 by first connecting portions 15D and 15E, respectively. Therefore, as the timing belt 15C moves forward and backward, the doors 17 and 18 move in opposite directions in the Y direction, thereby realizing the opening and closing operation of the doors 17 and 18.

[0042] Here, the left and right doors 17 and 18 are installed so that they overlap by approximately 3 to 10 mm in the width direction so that laser light L11 and L21 from inside the enclosure 3 does not leak out from the shielding door 10 to the outside when the shielding door shown in Figure 2(A) is closed.

[0043] If the shielding doors 10, 20 are configured as sliding doors, when the shielding doors 10, 20 are in an open state, each of the shielding doors 17, 18 must move along the width direction of the belt 62 of the belt conveyor 6 to a position outside the width dimension of the belt 62, as shown in Fig. 1 for example. For this reason, in the portion of the enclosure 3 where the shielding door groups 4, 5 are arranged, the space inside the enclosure 3 is wide in the horizontal direction perpendicular to the conveying direction so that the shielding doors 10, 20 can be opened and closed.

[0044] 3 is a diagram showing the opening and closing operation of the shielding door 10 shown in FIG. 2. FIG. 3(A) shows the state in which the shielding door 10 is closed (CLOSE state), and FIG. 3(B) shows the state in which the shielding door is open (OPEN state). The overview of FIGS. 3(A) and (B) is similar to FIG. 2(C), and is a side view of the shielding door 10 as viewed from the X-negative direction. Note that FIG. 3 illustrates the opening and closing operation of the shielding door 10 of the entrance-side shielding door group 4, but the opening and closing operation of the shielding door 20 of the exit-side shielding door group 5 is similar.

[0045] As described above, in the shielding door 10, the left and right doors 17 and 18 are connected to the lower flat portion 15C1 and the upper flat portion 15C2 of the timing belt 15C via the first connecting portions 15D and 15E, respectively, so that the shielding door 10 can be opened and closed in accordance with the movement direction of the timing belt 15C as the motor 14 rotates.

[0046] The motor 14 is disposed so that its drive shaft extends in the X direction, and the drive roller 15A is coupled to the drive shaft of the motor 14 so as to be coaxial with the drive shaft.

[0047] For example, as shown by arrow A in FIG. 3A, the motor 14 rotates the drive roller 15A counterclockwise when viewed from the X-negative direction. At this time, the lower flat portion 15C1 of the timing belt 15C moves toward the Y-positive direction as shown by arrow C. The upper flat portion 15C2 of the timing belt 15C moves toward the Y-negative direction as shown by arrow B. As a result, the Y-negative side door 17 moves toward the Y-positive direction as shown by arrow E in conjunction with the lower flat portion 15C1 via the first connecting portion 15D. The Y-positive side door 18 moves toward the Y-negative direction as shown by arrow D in conjunction with the upper flat portion 15C2 via the first connecting portion 15E. Then, as shown in FIG. 3A, when the Y-positive side end of the door 17 and the Y-negative side end of the door 18 overlap each other when viewed from the X-direction, the driving of the motor 14 is stopped. This closes the shielding door 10.

[0048] Meanwhile, as shown by arrow F in FIG. 3B, motor 14 rotates drive roller 15A clockwise when viewed from the X-negative direction. At this time, lower flat portion 15C1 of timing belt 15C moves toward the Y-negative direction as shown by arrow H. Furthermore, upper flat portion 15C2 of timing belt 15C moves toward the Y-positive direction as shown by arrow G. As a result, door 17 on the Y-negative side moves toward the Y-negative direction in conjunction with lower flat portion 15C1 via first connecting portion 15D as shown by arrow J. Furthermore, door 18 on the Y-positive side moves toward the Y-positive direction in conjunction with upper flat portion 15C2 via first connecting portion 15E as shown by arrow I. Then, as shown in FIG. 3B, the Y-positive end of door 17 and the Y-negative end of door 18 move apart in the Y direction to a position where a gap is formed that allows PET bottle P to pass through when viewed from the X direction. When these positions are reached, motor 14 is stopped. This causes the shielding door 10 to be in an open state.

[0049] The doors 17 and 18 are slidably connected to the slide rails 16D and 16E by the second connecting portions 17A and 17B, respectively, so that when the doors 17 and 18 receive an external force from the timing belt 15C via the first connecting portions 15D and 15E as a result of being driven by the motor 14, they can move more smoothly along the Y direction, which is the extension direction of the slide rails 16D and 16E.

[0050] The control unit 13 can control the open and closed positions of the left and right doors 17, 18 by detecting the Y-direction positions of the doors 17, 18 using, for example, a position sensor. Alternatively, the control unit 13 may control the movement amount of the doors 17, 18 by setting in advance control variables such as the operating time of the motor 14 or, if the motor 14 is a stepping motor, the number of pulses.

[0051] Fig. 4 is a diagram showing the relationship between the flow of plastic bottles P on the belt conveyor 6 and the open / closed states of the shielding doors 10-1, 10-2. Note that Fig. 4 illustrates the open / closed states of the shielding doors 10-1, 10-2 of the entrance-side shielding door group 4, but the open / closed states of the shielding doors 20-1, 20-2 of the exit-side shielding door group 5 are similar. Fig. 4 illustrates the open / closed states of the shielding doors 10-1, 10-2 according to the flow of plastic bottles P in five stages: (A), (B), (C), (D), and (E).

[0052] When the plastic bottles P are transported on the belt conveyor 6 from left to right in the drawing (i.e., in the transport direction), in order for either of the shielding doors 10-1 and 10-2 to always be in a closed state, the states of the shielding doors 10-1 and 10-2 must change as follows: (A) → (B) → (C) → (D) → (E) (E is the same as A). If this state change is maintained, the light blocking condition that prevents the laser beams L11 and L21 from leaking outside the group of shielding doors 4 is satisfied.

[0053] Here, when focusing on the state in which the shielding doors are closed, there are two patterns for the position of the plastic bottle P: (a) a state in which there is one plastic bottle P between the shielding doors 10-1 and 10-2, and (c) a state in which there are two plastic bottles P between the shielding doors 10-1 and 10-2. Therefore, if the bottle pitch BP, which is the distance between adjacent plastic bottles P flowing on the conveying path, and the distance DS between two adjacent shielding doors 10-1 and 10-2 along the conveying path are set so as to satisfy these two patterns, the light-blocking condition will be satisfied.

[0054] In general, the distance DS between the shielding doors 10 is set to satisfy two patterns: N and N+1 plastic bottles P between the two shielding doors 10-1 and 10-2. Such conditions will be described with reference to FIG. 5.

[0055] Fig. 5 is a diagram showing the relationship between the bottle pitch BP and the installation interval DS of the shielding doors 10-1, 10-2. Note that Fig. 5 illustrates the shielding doors 10-1, 10-2 of the entrance-side shielding door group 4, but the same applies to the shielding doors 20-1, 20-2 of the exit-side shielding door group 5.

[0056] Here, the diameter of the plastic bottle P is Bd, and the gap between the two shielding doors 10-1, 10-2 and the one to which the plastic bottle P is closer is Dh. Also, an example of the arrangement of the shielding doors 10-1, 10-2 that results in an installation distance DS1 when there is one plastic bottle P between the shielding doors 10-1 and 10-2 in the state of (A) in Fig. 4, i.e., when there is one plastic bottle P between the shielding doors 10-1 and 10-2, is shown by dotted lines in Fig. 5. Similarly, an example of the arrangement of the shielding doors 10-1, 10-2 that results in an installation distance DS2 when there is two plastic bottles P between the shielding doors 10-1 and 10-2 in the state of (C) in Fig. 4, i.e., when there are two plastic bottles P between the shielding doors 10-1 and 10-2, is shown by solid lines in Fig. 5.

[0057] Using the parameters shown in FIG. 5, the installation intervals DS1 and DS2 of the shielding doors 10-1 and 10-2 can be expressed by the following equations (1) and (2), respectively.

[0058] DS1 = BP × 2 - Bd - Dh (1) DS2=BP+Bd+Dh×2 (2)

[0059] Therefore, the shading condition (i.e., the condition under which one of the shielding doors 10-1 and 10-2 is always closed) is that the installation distance DS between the shielding doors 10-1 and 10-2 is greater than or equal to DS2 and less than or equal to DS1, that is, it can be expressed as the following (3) using equations (1) and (2).

[0060] BP+Bd+Dh×2 ≦ DS ≦ BP×2-Bd-Dh (3)

[0061] By setting the door distance DS based on the above formula (3), the light blocking condition is satisfied.

[0062] Fig. 6 is a diagram showing the relationship between the transport speed Bv of the plastic bottles P and the opening / closing speed Dv of the shielding door 10. Note that Fig. 6 illustrates the shielding door 10 included in the entrance-side shielding door group 4, but the same applies to the shielding door 20 of the exit-side shielding door group 5.

[0063] Here, the diameter of the PET bottle P is Bd, the gap between the PET bottle P and the shielding door 10 to which the PET bottle P is approaching is Dh (Dh>0), the time it takes for the shielding door 10 to open (i.e., the time it takes for the PET bottle P to move) is t, and the margin of clearance when the shielding door 10 opens is Dw.

[0064] Arrows a, b, and c in FIG. 6(a) represent the trajectory of the shielding door 10 relative to the plastic bottle P (that is, the movement of the door from the viewpoint of the plastic bottle P).

[0065] Trajectory a shows the state in which the shielding door 10 opens without hitting the plastic bottle P (i.e., the door opens quickly enough to prevent the oncoming plastic bottle P from hitting it). Trajectory b shows the state in which the door opens while coming into contact with the plastic bottle P. Trajectory c shows the state in which the door hits the plastic bottle P as it opens (i.e., the door hits the oncoming plastic bottle P because the opening speed of the door is too slow).

[0066] Therefore, the shielding door 10 needs to be moved faster than the locus b. In other words, the opening / closing speed Dv of the shielding door 10 needs to be set so that the locus falls on the X-direction side of the locus b shown in Figure 6(A).

[0067] 6(b) shows the state before and after the opening and closing of the shielding door 10 for the trajectory b. Using the above parameters, the movement distance of the shielding door 10 can be expressed as Dv·t, and the movement distance of the door relative to the plastic bottle P (i.e., the movement distance of the plastic bottle P) can be expressed as Bv·t.

[0068] At this time, the moving distance Dv·t of the shielding door 10 can be expressed by the following equation (4).

[0069]

number

[0070] Here, as shown in FIG. 6(b), the center of the circular shape of the PET bottle P in a planar view is defined as O. When one of the two sliding doors of the shielding door 10 (the door on the Y-positive side in the example of FIG. 6) is closed, the position of the end of the belt conveyor 6 on the central side in the width direction (Y-direction) is defined as A. The point of contact between the tangent line passing through position A and the outline of the PET bottle P and the PET bottle P is defined as M. The intersection of this tangent line and a line extending from the center O of the PET bottle P in the width direction of the belt conveyor 6 is defined as S. Note that the length of the line segment OP excluding the radius Bd / 2 of the PET bottle P corresponds to the above-mentioned margin Dw. Furthermore, the intersection of the line segment extending from the intersection point S toward the X-positive side with a line extended toward the Y-positive side along the extension direction of the door in a planar view is defined as R.

[0071] In this case, as shown in Figure 6(b), the triangle OAM is similar to the triangle ASR, so the relationship is OM:AR = AM:PRSR. This relationship can be expressed by the following equation (5) using the above parameters.

[0072]

number

[0073] From the relationship in equation (5) above, the travel distance Bv·t of the plastic bottle P can be expressed by the following equation (6).

[0074]

number

[0075] Here, the moving distance Bv·t of the plastic bottle P is preferably small, so it is assumed as in the following equation (7).

[0076]

number

[0077] The above equation (7) can be converted into the following equation (8) for the opening / closing speed Dv of the shielding door 10.

[0078]

number

[0079] Here, the line segment AM can be expressed by the following equation (9) based on the geometric relationship shown in Figure 6(b).

[0080]

number

[0081] Therefore, the condition for the opening / closing speed Dv of the shielding door 10 can be expressed by the following equation (10).

[0082]

number

[0083] Furthermore, from the above formula (4), the opening and closing time t for providing a margin Dw when opening and closing the shielding door 10 can be expressed by the following formula (11).

[0084]

number

[0085] 5 and 6, in the marking system 1 according to this embodiment, it is preferable to set each parameter value so that the installation interval DS of the multiple shielding doors 10, 20 in the shielding door groups 4, 5 satisfies the condition of the above formula (3) and the opening / closing speed Dv of the shielding doors 10, 20 satisfies the condition of the above formula (10). In this case, the control unit 13 controls the motor 14, which is the drive source for the opening / closing operation of each of the shielding doors 10, 20, so that the opening / closing speed Dv of each of the shielding doors 10, 20 satisfies the condition of the above formula (10).

[0086] Additionally, a pitch adjustment unit is preferably provided upstream of the entrance 31 of the enclosure 3 on the belt conveyor 6 to adjust the pitch of the multiple PET bottles P along the conveying direction. The pitch adjustment unit may be provided as a separate element of the marking system 1, or as a separate device from the marking system 1. The pitch adjustment unit can adjust the pitch by restricting the downstream transport of the upstream PET bottle, for example, by inserting a partition plate between adjacent PET bottles or by gripping the upstream PET bottle. By providing such a pitch adjustment unit and configuring it to allow for arbitrary pitch adjustment, the bottle pitch BP, one of the parameters included in equation (3), can be adjusted to any value, making it easier to set the installation interval DS of the multiple shielding doors 10, 20 to satisfy the condition of equation (3).

[0087] As a result, the marking system 1 according to this embodiment can more reliably realize a state in which at least one of the multiple shielding doors 10, 20 in the shielding door groups 4, 5 is open to allow the plastic bottle P to pass through, while the remaining shielding doors are closed. This can reliably prevent a situation in which all of the multiple shielding doors 10, 20 in the shielding door groups 4, 5 are open, and therefore can more reliably prevent the laser light L11, L12, L21, L22 output from the laser marking device 2 from leaking to the outside.

[0088] 7 is a diagram illustrating an example of a hardware configuration of the control unit 13. As shown in FIG. 7, the control unit 13 can be physically configured as a computer system including a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102 and a ROM (Read Only Memory) 103 as main storage devices, an input device 104 such as a keyboard and a mouse as input devices, an output device 105 such as a display, a communication module 106 as a data transmission / reception device such as a network card, an auxiliary storage device 107 such as a hard disk, etc. Each function of the control unit 13 described above is realized by loading predetermined computer software onto hardware such as the CPU 101 and RAM 102, thereby operating the communication module 106, the input device 104, and the output device 105 under the control of the CPU 101, and reading and writing data from and to the RAM 102 and the auxiliary storage device 107.

[0089] 2 and 3, a configuration is illustrated in which each of the multiple shielding doors 10, 20 in the shielding door groups 4, 5 has its own control unit 13, but a configuration in which one control unit 13 controls the opening and closing operations of the multiple shielding doors 10, 20 may also be used. Furthermore, the control unit 13 is not specialized for the opening and closing operations of the shielding doors 10, 20, and may be configured as part of a control device that controls the operations of other elements in the marking system 1, such as the laser marking device 2 and the belt conveyor 6.

[0090] Fig. 8 is a diagram showing a schematic configuration of a shielding door 10A according to a first modified example. Figs. 8(A) and (B) show the shielding door 10A in a closed state, and Figs. 8(C) and (D) show the shielding door 10A in an open state. Figs. 8(A) and (C) are side views viewed from the Y-negative direction, and Figs. 8(B) and (D) are side views viewed from the X-negative direction. Note that Fig. 8 illustrates the configuration of the shielding door 10A of the entrance-side shielding door group 4, but the configuration of the shielding door 20 of the exit-side shielding door group 5 can also be changed in a similar manner.

[0091] The shielding door 10A according to the first modification is installed so as to be movable in directions (Z direction in the example of FIG. 8) away from and toward a placement surface on the conveying path on which the plastic bottles P are placed (i.e., the surface that passes above the belt 62 of the belt conveyor 6). The shielding door 10A opens when moved in a direction away from the placement surface, and closes when moved in a direction toward the placement surface.

[0092] In the example of FIG. 8, the shielding door 10A is a single door that is arranged opposite to one another in the conveying direction, and is opened and closed by sliding this single door up and down.

[0093] The shielding door 10A has, as an opening and closing mechanism, a control unit 13, a motor 14, and a power transmission unit 15. In addition, although not shown in FIG.

[0094] The power transmission unit 15 includes a drive roller 15A, a driven roller 15B, a timing belt 15C, and a connecting unit 15D.

[0095] In the shielding door 10A of the first modification, the motor 14 is disposed so that its drive shaft extends in the Y direction, and the drive roller 15A is connected to the drive shaft of the motor 14 so as to be coaxial with the drive shaft. The drive roller 15A and the driven roller 15B are disposed parallel to each other at substantially the same position in the conveying direction (X direction). For example, the drive roller 15A is disposed above the driven roller 15B. Therefore, a timing belt 15C stretched between these rollers 15A and 15B has a pair of flat portions disposed opposite each other in the X direction and both extending in the Z direction. The connecting portion 15D is connected to the timing belt 15C at a flat portion 15C1 of the pair of flat portions on the negative X direction side. The connecting portion 15D connects the shielding door 10A to the timing belt 15C.

[0096] As shown by arrow K in FIG. 8(A), the motor 14 rotates the drive roller 15A in a clockwise direction when viewed from the Y negative side. At this time, the flat surface 15C1 of the timing belt 15C moves downward as shown by arrow L in FIGS. 8(A) and (B). As a result, the shielding door 10A moves downward as shown by arrow M in conjunction with the flat surface 15C1 via the connecting portion 15D. Then, as shown in FIGS. 8(A) and (B), when the bottom end of the shielding door 10A moves to a position directly above the placement surface, the driving of the motor 14 is stopped. As a result, the shielding door 10A is in a closed state.

[0097] Meanwhile, as shown by arrow N in FIG. 8(C), the motor 14 rotates the drive roller 15A counterclockwise when viewed from the Y negative side. At this time, the flat surface 15C1 of the timing belt 15C moves upward as shown by arrow p in FIGS. 8(C) and (D). As a result, the shielding door 10A moves upward as shown by arrow O in conjunction with the flat surface 15C1 via the connecting portion 15D. Then, as shown in FIGS. 8(C) and (D), when the bottom end of the shielding door 10A is sufficiently separated from the placement surface and moves above the height dimension of the PET bottle P, the driving of the motor 14 is stopped. This causes the shielding door 10A to enter an open state.

[0098] It is preferable that the shielding door 10A is positioned at a height that does not contact the placement surface, i.e., the upper surface of the belt 62 of the belt conveyor 6, even when it is closed. This prevents the shielding door 10A from interfering with the movement of the belt 62 in the conveying direction, allowing the PET bottles P to be conveyed smoothly even when the shielding door 10A is closed.

[0099] However, in the shielding door 10A of the first modified example, a gap is generated between the conveying surface and the bottom edge of the door, which may cause slight leakage of the laser light L. For this reason, in a door that slides up and down like the shielding door 10A of the first modified example, it is preferable to add a structure to prevent such light leakage.

[0100] Fig. 9 is a diagram showing a first example of a light leakage prevention structure applied to a vertical sliding type shielding door 10A. Fig. 9 is a side view seen from the Y negative direction side, and corresponds to Figs. 8(A) and (C).

[0101] As shown in FIG. 9, the shielding door 10A may be provided with a laser-light-impermeable light-shielding member 19 at the end of the mounting surface side. In the case of a vertically sliding shielding door 10A, the light-shielding member 19 is connected to the bottom end of the door and installed so as to extend below the bottom end. For example, a rubber sheet or a light-shielding curtain made of a material with high light-shielding and flame-retardant properties can be used as the light-shielding member 19. By providing such a light-shielding member 19, it is possible to prevent leakage of laser light L11, L21, etc. even with a vertically sliding shielding door 10A.

[0102] Furthermore, the light blocking member 19 is preferably made of an elastically deformable material. As a result, even when the lower end of the light blocking member 19 is in contact with the placement surface and completely blocks the gap, as shown in Figure 9, the light blocking member 19 elastically deforms in the conveyance direction, preventing the movement of the belt 62 of the belt conveyor 6 in the conveyance direction from being impeded. This allows for closer contact between the light blocking member 19 and the placement surface, thereby more reliably preventing light leakage.

[0103] Fig. 10 is a diagram showing a second example of a light leakage prevention structure applied to a vertical sliding type shielding door 10A. Fig. 10 is also a side view seen from the Y negative direction side, and corresponds to Figs. 8(A) and (C).

[0104] In the example of FIG. 10, a conveying device for conveying PET bottles P includes a plurality of belt conveyors. The shielding door 10A is disposed at a boundary 63 between two adjacent belt conveyors 6A and 6B among the plurality of belt conveyors. The two belt conveyors 6A and 6B are disposed so that their loading surfaces are at approximately the same height. In FIG. 10, the height position of the loading surface 64 at the boundary 63 is indicated by a dotted line. Because rollers 61 are disposed at the end of each belt conveyor 6A and 6B in the conveying direction, the boundary 63 between the two belt conveyors 6A and 6B is recessed from the loading surface.

[0105] 10, when the shielding door 10A is closed, it moves below the placement surface 64 of the two belt conveyors 6A and 6B. In other words, when the shielding door 10A is closed, as shown in FIG. 10, the lower end of the shielding door 10A enters a recess in the boundary portion 63 between the two belt conveyors 6A and 6B and reaches a position below the height position of the placement surface 64. With this configuration, the laser beams L11 and L21 are diffused several times by the lower end and boundary portion 63 of the shielding door 10A, thereby preventing light leakage. Furthermore, light leakage can be prevented without adding any additional components separate from the shielding door 10A, thereby suppressing an increase in the number of parts and costs.

[0106] Fig. 11 is a diagram showing a third example of a light leakage prevention structure applied to a vertical sliding type shielding door 10A. Fig. 11 is also a side view seen from the Y negative direction side, and corresponds to Figs. 8(A) and (C).

[0107] In the example of FIG. 11, the belt conveyor 6C has a group of rollers 68 that move the belt 62 below the placement surface 64 to create a gap with the placement surface 64 at the position in the conveyance direction where the shielding door 10A is located.

[0108] 11, the roller group 68 includes a pair of first rollers 65, 66 arranged parallel to the rollers 61 at substantially the same height as the conventional rollers 61 arranged at both ends of the belt conveyor 6C, and arranged downstream and upstream of the shielding door 10A in the conveying direction, and a second roller 67 arranged below the pair of first rollers 65, 66 and at substantially the same position as the shielding door 10A in the conveying direction. In the portion where the roller group 68 is arranged, the belt 62 of the belt conveyor 6C first moves downward from the height position of the placement surface 64 along the upstream first roller 66. Second, when the belt 62 reaches the height position of the second roller 67, the belt 62 moves along the second roller 67 and changes direction to upward. Third, when the belt 62 reaches the height position of the downstream first roller 65, the belt 62 moves along the first roller 65 and returns to the height position of the placement surface 64. With this configuration, the roller group 68 can move the belt 62 of the belt conveyor 6C below the placement surface 64, creating a downward recessed gap.

[0109] 11, when the shielding door 10A is closed, it moves so that the end on the placement surface side enters the gap formed by the roller group 68. In other words, when the shielding door 10A is closed, as shown in Fig. 11, the lower end of the shielding door 10A enters the recess in the gap of the belt 62 formed by the roller group 68 and reaches a position below the height position of the placement surface 64. With this configuration, the laser beams L11 and L21 passing near the lower end of the shielding door 10A do not pass through the shielding door 10A without being repeatedly diffused by the gap of the belt 62 formed by the roller group 68, so that light leakage can be more reliably prevented.

[0110] Fig. 12 is a diagram showing a schematic configuration of a shielding door 10B according to a second modified example. The outlines of Fig. 12(A) to (D) correspond to Fig. 8(A) to (D), respectively. Note that Fig. 12 illustrates the configuration of the shielding door 10B of the entrance-side shielding door group 4, but the configuration of the shielding door 20 of the exit-side shielding door group 5 can also be changed in the same way.

[0111] The shielding door 10B according to the second modification is disposed above the PET bottles P being conveyed along the conveying path, and includes a drive roller 15A as a rotation shaft that extends in a direction intersecting the conveying direction (the Y direction in the example of FIG. 12). The shielding door 10B is disposed opposite the conveying direction, and opens by rotating downstream in the conveying direction around the drive roller 15A as a rotation shaft, and closes by rotating from the open state toward the upstream in the conveying direction to a position facing the conveying direction.

[0112] In the example of FIG. 12, the shielding door 10B is a single door that is arranged opposite to one another in the conveying direction when closed, and a rotation shaft is provided at the top of this single door, which is rotated to open and close the door.

[0113] The shielding door 10B has, as an opening and closing mechanism, a control unit 13, a motor 14, and a power transmission unit 15. In addition, although not shown in FIG.

[0114] The power transmission unit 15 has a drive roller 15A as a rotation shaft and a connecting unit 21. In the shielding door 10B of the first modified example, the motor 14 is disposed so that the drive shaft extends in the Y direction, and the drive roller 15A is connected to the drive shaft so as to be coaxial with the drive shaft of the motor 14. The connecting unit 21 is fixedly provided around the outer periphery of the drive roller 15A and rotates integrally with the drive roller 15A.

[0115] 12(B) and (D), two connecting portions 21 are provided along the extension direction (Y direction) of the drive roller 15A. The two connecting portions 21 are arranged at positions at approximately the same distance from the center of the door width direction at the upper end of the shielding door 10B, and are connected to the main surface of the shielding door 10B on the negative X direction side. In this way, the connecting portions 21 connect the shielding door 10B to the drive roller 15A.

[0116] As shown by arrow T in Fig. 12(A), the motor 14 rotates the drive roller 15A counterclockwise when viewed from the Y negative side. As a result, the shielding door 10B rotates in the X negative direction around the drive roller 15A as a rotation axis, as shown by arrow Q, in conjunction with the drive roller 15A via the connecting portion 21. Then, as shown in Figs. 12(A) and 12(B), when the lower end of the shielding door 10B moves to a position directly above the placement surface (in the example of Fig. 12, when the shielding door 10B assumes a vertically standing position and moves to a position where the main surface to which the connecting portion 21 is connected faces the upstream side in the conveying direction), the driving of the motor 14 is stopped. As a result, the shielding door 10B is closed.

[0117] Meanwhile, as shown by arrow R in Fig. 12(C), motor 14 rotates drive roller 15A in the clockwise direction when viewed from the Y negative side. As a result, shielding door 10B rotates in the Z positive direction around drive roller 15A as the rotation axis, as shown by arrow S, in conjunction with drive roller 15A via connecting portion 21. Then, as shown in Figs. 12(C) and 12(D), when the bottom end of shielding door 10B is sufficiently separated from the placement surface and moves above the height of PET bottle P (in the example of Fig. 12, when shielding door 10B assumes a position extending horizontally and moves to a position where the main surface to which connecting portion 21 is connected faces downward), driving of motor 14 is stopped. This causes shielding door 10B to be in the open state.

[0118] Next, other modified examples of the shielding door will be described with reference to Figures 13 to 17. The shielding door shown in Figures 13 and subsequent figures is a push-open door that is rotated downstream in the conveying direction and pushed open by the plastic bottle P being conveyed along the conveying path, and then rotates upstream in the conveying direction to close after the plastic bottle P has passed. In other words, the shielding door shown in Figures 13 and subsequent figures does not have a motor 14 as a drive source, a power transmission unit 15, or a control unit 13 for controlling the opening and closing operation, as with the shielding doors 10, 10A, and 10B described with reference to Figures 1 to 12.

[0119] However, the shielding doors shown in Figs. 13 and onwards may also be provided with a drive source such as a motor 14 and may be configured to perform opening and closing operations under the control of the control unit 13.

[0120] Fig. 13 is a diagram showing a schematic configuration of a shielding door 10C according to a third modified example. The outlines of Fig. 13(A) to (C) correspond to Fig. 2(A) to (C), respectively. Fig. 14 is a diagram showing a schematic configuration of an upstream shielding door group 4 to which the shielding door 10C shown in Fig. 13 is applied. Fig. 14(A) is a plan view seen from the Z positive direction side, and Fig. 14(B) is a side view seen from the Y negative direction side.

[0121] 13 and 14 show an example of the configuration of the shielding door 10C of the entrance-side shielding door group 4, but the configuration of the shielding door 20 of the exit-side shielding door group 5 can also be changed in the same way.

[0122] The shielding door 10C according to the third modification includes two types of doors 22, 23, each of which has a rotation shaft 24, 25 provided in the vertical direction on both sides of the width direction, which is a direction perpendicular to the conveying direction and is horizontal. As shown in Figures 13(A) and (C), the two types of doors 22, 23 are arranged so that the ends on the center side in the width direction come into contact with at least a part of the PET bottle P being conveyed along the conveying path. In the upstream shielding door group 4, as shown in Figures 14(A) and (B), the two types of doors 22, 23 of the shielding door 10C are arranged alternately along the conveying direction.

[0123] 13(A) and 13(C), door support parts 28 and 29 are installed on both sides of the width direction of the belt conveyor 6, and rotation shafts 24 and 25 are installed so as to be rotatable relative to the door support parts 28 and 29. The rotation shafts 24 and 25 are each installed so as to extend in the Z direction. Doors 22 and 23 are installed on the rotation shafts 24 and 25, respectively, and are rotatable around the rotation shafts 24 and 25.

[0124] As shown in Figure 13(C), door stoppers 26 and 27 are installed on the tops of doors 22 and 23. Door stoppers 26 and 27 have their bases fixed to door support members 28 and 29, respectively, and their leading ends first extend toward the center of the width of belt conveyor 6 along the Y direction and then bend downward. Door stoppers 26 and 27 are formed so that their downwardly bent leading ends extend to a height position that allows them to come into contact with the main surfaces of doors 22 and 23 on the negative X direction side. Doors 22 and 23 are biased toward door stoppers 26 and 27, respectively, by torsion coil springs (not shown).

[0125] In the configuration of the shielding door 10C according to the third modified example, when a filled PET bottle P is transported by the belt conveyor 6, the doors 22 and 23 are pushed by the PET bottle P and rotate around the rotation axes 24 and 25 downstream in the transport direction, as shown by the arrows in Figure 13(A).

[0126] In the example of Figure 13, the door 23 on the right side in the width direction as viewed from upstream in the conveying direction is positioned closer to the door 22 on the left side in the width direction. Therefore, when a plastic bottle P is conveyed as shown in Figure 13, the door 23 is first pushed by the plastic bottle P and rotates clockwise as viewed from the positive Z direction as shown by the arrow in Figure 13(A). After that, when the plastic bottle P passes, the rotated door 23 rotates counterclockwise due to the force of a torsion coil spring (not shown) to a position where it contacts the door stopper 27. The door stopper 27 restricts the door 23 from rotating upstream in the conveying direction.

[0127] As the plastic bottle P continues to be transported downstream, the door 22 is pushed by the plastic bottle P and rotates counterclockwise when viewed from the positive Z direction, as shown by the arrow in Figure 13(A). After that, as the plastic bottle P passes, the rotated door 22 rotates clockwise due to the force of a torsion coil spring (not shown) to a position where it contacts the door stopper 26. The door 22 is restricted from rotating upstream in the transport direction by the door stopper 26.

[0128] Here, the positional relationship between the two doors 22, 23 of the shielding door 10C is such that the ends of the left and right doors 22, 23 on the center side in the width direction overlap by about 3 to 10 mm when viewed from the X direction, similar to the two doors 17, 18 of the sliding door type shielding door 10 described with reference to Fig. 2 etc. Also, in the conveying direction (X direction), the opening and closing and the left and right door spacing (i.e., the positions of each door 22, 23 along the conveying direction) are set so that the doors 22, 23 do not interfere with each other when they rotate.

[0129] Furthermore, the shielding door 10C according to the third modified example may also be configured to have a light-shielding member such as a rubber sheet with a high flame-retardant grade installed in the gap between the conveying surface and the lower end of the doors 22 and 23, similar to the light leakage prevention structure of the shielding door 10A according to the first modified example described with reference to Figure 9.

[0130] As shown in Figure 14, when the shielding door 10C of the third modified example is applied to the upstream shielding door group 4, similar to the sliding door type shielding door 10 described with reference to Figure 1, etc., the light blocking condition is such that either the shielding door 10C-1 on the upstream side in the conveying direction or the shielding door 10C-2 on the downstream side is closed.

[0131] Here, in the case of the shielding door 10C according to the third modification, the positions of the left and right doors 22 and 23 are shifted in the conveying direction, so it is sufficient to consider the left and right doors separately. For example, as shown in FIG. (1-1) When the door 23-2 of the shielding door 10C-2 is open, the door 23-1 of the shielding door 10C-1 is closed, (1-2) When the door 22-2 of the shielding door 10C-2 is closed, the door 23-1 of the shielding door 10C-1 is open. To achieve the state, or, contrary to the example in Figure 14, (2-1) When the door 23-2 of the shielding door 10C-2 is closed, the door 23-1 of the shielding door 10C-1 is open, (2-2) When the door 22-2 of the shielding door 10C-2 is open, the door 23-1 of the shielding door 10C-1 is closed. Place the doors so that the state can be realized.

[0132] 14(A), the linear light L11 does not leak because one of the shielding doors 10C-1 and 10C-2 is closed. Furthermore, the intensity of the diffusely reflected light L21 also decreases due to multiple reflections by the inner wall of the enclosure 3 in the area of ​​the upstream shielding door group 4, so even if the light leaks, there is no problem.

[0133] Fig. 15 is a diagram showing the schematic configuration of a shielding door 10D according to a fourth modified example and a shielding door 10E according to a fifth modified example. Fig. 15(A) is a plan view of a configuration in which the shielding door 10D according to the fourth modified example is applied to the entrance-side shielding door group 4, viewed from the Z positive direction. Fig. 15(B) is a plan view of a configuration in which the shielding door 10E according to the fifth modified example is applied to the entrance-side shielding door group 4, viewed from the Z positive direction.

[0134] In addition, the opening and closing structures of the doors 22, 23 of the shielding door 10D according to the fourth modified example and the shielding door 10E according to the fifth modified example are similar to the opening and closing structures of the doors 22, 23 of the shielding door 10C according to the third modified example, and therefore the same symbols are used.

[0135] 15(A), the shielding door 10D according to the fourth modification includes two double doors 22, 23 that are arranged opposite each other in the conveying direction. The conveying path is arranged so that the plastic bottle P passes through the middle of the two doors 22, 23 and pushes open the two doors 22, 23. In the shielding door 10D according to the fourth modification, the two doors 22, 23 that are arranged on both sides in the width direction are arranged at approximately the same position in the conveying direction.

[0136] As shown in Figure 15(A), when the shielding door 10D of the fourth modified example is applied to the upstream shielding door group 4, similar to the sliding door type shielding door 10 described with reference to Figure 1, etc., the light blocking condition is such that either the shielding door 10D-1 on the upstream side in the conveying direction or the shielding door 10D-2 on the downstream side is closed.

[0137] Furthermore, as shown in the upstream shielding door 10D-1 in Figure 15(A), the positional relationship between the two doors 22, 23 of the shielding door 10D-2 is set so that when viewed from the X direction in the closed state, the ends of the left and right doors 22, 23 on the central side in the width direction overlap by approximately 3 to 10 mm.

[0138] With these configurations, the shielding door 10D according to the fourth modified example can more reliably suppress leakage of the laser light L11, L21 to the outside. Furthermore, compared to the configuration of the shielding door 10C according to the third modified example, when multiple shielding doors are applied to the upstream-side shielding door group 4, the total required dimension along the conveying direction can be made smaller, so the upstream-side shielding door group 4 can be made more compact.

[0139] 15(B), the shielding door 10E according to the fifth modification includes two double doors 22, 23 that are arranged opposite each other in the conveying direction. The conveying path is arranged so that the plastic bottle P passes through the middle of the two doors 22, 23 and pushes open the two doors 22, 23. In the shielding door 10E according to the fifth modification, the two doors 22, 23 that are arranged on both sides in the width direction are arranged at approximately the same position in the conveying direction.

[0140] As shown in Figure 15(B), when the shielding door 10E of the fifth modified example is applied to the upstream shielding door group 4, similar to the sliding door type shielding door 10 described with reference to Figure 1, etc., the light blocking condition is such that either the shielding door 10E-1 on the upstream side in the conveying direction or the shielding door 10E-2 on the downstream side is closed.

[0141] 15(B), the positional relationship between the two doors 22, 23 of the shielding door 10E-2 is set so that when viewed from the X direction in the closed state, there is a gap of about several millimeters between the ends of the left and right doors 22, 23 on the central side in the width direction. This configuration makes it possible to prevent the ends of the central parts of the two doors 22, 23 from contacting or rubbing against each other when the shielding door 10E is opened or closed, thereby enabling smoother opening and closing operations.

[0142] 15(B), in the shielding door 10E according to the fifth modification, a light-shielding member 40 that is non-transparent to laser light and closes the gap in the middle is provided at the end of the middle part of at least one of the two doors 22, 23. As a result, as shown in the upstream shielding door 10E-1 in FIG. 15(B), the gap in the middle part between the left and right doors 22, 23 can be closed by the light-shielding member 40-1 in the closed state, which allows for smooth opening and closing operations and more reliably prevents the laser light L11, L21 from leaking to the outside.

[0143] Note that Figures 15(A) and (B) illustrate a configuration in which shielding doors 10D and 10E are applied to the entrance side shielding door group 4, but the configuration of the shielding door 20 of the exit side shielding door group 5 can also be changed in the same way.

[0144] Fig. 16 is a diagram showing a schematic configuration of a shielding door 10F according to a sixth modified example. Fig. 16(A) is a plan view of a configuration in which the shielding door 10F according to the sixth modified example is applied to the entrance-side shielding door group 4, as viewed from the positive Z direction. Fig. 16(B) is a perspective view showing a schematic configuration of one revolving door 41 of the shielding door 10F.

[0145] As shown in FIG. 16(A), a shielding door 10F according to the sixth modification includes a pair of revolving doors 41 and 42 arranged opposite each other in the conveying direction. Each of the revolving doors 41 and 42 includes multiple doors spaced at predetermined angles around a rotation axis. In the example shown in FIG. 16, one of the revolving doors 41, which is arranged on the negative Y-direction side of the belt conveyor 6, includes a rotation axis 45 extending in the Z direction and four doors 43A, 43B, 43C, and 43D arranged around the rotation axis 45 along the extension direction of the rotation axis 45. As shown in FIG. 16(B), the four doors 43A, 43B, 43C, and 43D are rectangular plate-like members, and one side of the rectangular shape is fixed around the rotation axis 45 along the extension direction of the rotation axis 45. The four doors 43A, 43B, 43C, and 43D are arranged so that their main surfaces face the rotation direction of the rotation axis 45. The four doors 43A, 43B, 43C, and 43D are installed at approximately 90-degree intervals around the rotation axis 45. That is, in the shielding door 10F according to the sixth modified example, the predetermined angle at which the multiple doors of each of the revolving doors 41 and 42 are arranged is approximately 90 degrees.

[0146] On the other hand, the other revolving door 42, which is disposed on the Y positive side of the belt conveyor 6, has a rotation shaft 46 extending in the Z direction and four doors 44A, 44B, 44C, and 44D disposed around the rotation shaft 46 along the extension direction of the rotation shaft 46. The four doors 44A, 44B, 44C, and 44D are rectangular plate-like members, and one side of the rectangle extends along the extension direction of the rotation shaft 46 and is fixed around the rotation shaft 46. The four doors 44A, 44B, 44C, and 44D are disposed so that their main surfaces face the rotation direction of the rotation shaft 46. The four doors 44A, 44B, 44C, and 44D are disposed approximately every 90 degrees around the rotation shaft 46.

[0147] Also, as shown in Figure 16(A), the positional relationship of the pair of revolving doors 41, 42 of the shielding door 10F is such that the rotation axes 45, 46 of each revolving door 41, 42 are installed at approximately the same position in the conveying direction, and one of the four doors can be positioned in a straight line along the Y direction on the belt conveyor 6.

[0148] As shown in FIG. 16(A), the pair of revolving doors 41, 42 rotates so that multiple doors 43, 44 move downstream in the conveyance direction, thereby opening to allow PET bottles P to pass, and then rotates a predetermined angle (approximately 90 degrees) to close. For example, when door 43A of the four doors of revolving door 41 and door 44A of the four doors of revolving door 42 are aligned in a straight line along the Y direction on belt conveyor 6, shielding door 10F is closed. Thereafter, when a PET bottle P approaches, each of revolving doors 41, 42 rotates so that doors 43A, 44A move downstream in the conveyance direction. This opens shielding door 10F, allowing PET bottles P to pass through. Furthermore, when each of revolving doors 41, 42 rotates 90 degrees, doors 43D, 44D adjacent to each of doors 43A, 44A are aligned in a straight line along the Y direction on belt conveyor 6, thereby closing shielding door 10F again.

[0149] As shown in Figure 16(A), when the shielding door 10F of the sixth modified example is applied to the upstream shielding door group 4, similar to the sliding door type shielding door 10 described with reference to Figure 1, etc., the light blocking condition is such that either the shielding door 10F-1 on the upstream side in the conveying direction or the shielding door 10F-2 on the downstream side is closed.

[0150] In the shielding door 10F of the sixth modified example, each revolving door 41, 42 can be rotated by power output from a drive source such as a motor. Furthermore, the transported plastic bottle P can be detected by a detection unit. When the detection unit detects the approach of a plastic bottle P, it drives the motor so that each revolving door 41, 42 rotates 90 degrees in accordance with the transport of the plastic bottle P. This allows the plastic bottle P to pass through the shielding door 10F. These motors and detection units correspond to the motor 14 and upstream detection unit 11 shown in FIG. 2 and other figures. Furthermore, the rotation control of the revolving doors 41, 42 using the motor and detection unit can be performed by elements similar to the control unit 13 shown in FIG. 2 and other figures.

[0151] The shielding door 10F of the sixth modified example, with the above-described configuration, can shorten the driving time of the motor and can also accommodate PET bottles P conveyed at a faster speed, thereby improving versatility.

[0152] Fig. 17 is a diagram showing a schematic configuration of a shielding door 10G according to a seventh modified example. Fig. 17 is a plan view of a configuration in which the shielding door 10G according to the seventh modified example is applied to the entrance-side shielding door group 4, viewed from the positive Z direction. The overview of Fig. 17 is similar to Fig. 16(A).

[0153] As shown in FIG. 17, a shielding door 10G according to the seventh modification includes a pair of revolving doors 51 and 52 arranged opposite each other in the conveying direction. Each of the revolving doors 51 and 52 includes multiple doors spaced at predetermined angles around a rotation axis. In the example of FIG. 17, one of the revolving doors 51, which is arranged on the negative Y side of the belt conveyor 6, has a rotation axis 55 extending in the Z direction and eight doors 53A, 53B, 53C, 53D, 53E, 53F, 53G, and 53H arranged around the rotation axis 55 along the extension direction of the rotation axis 55. Similar to the eight doors 53A, 53B, 53C, 53D, 53E, 53F, 53G, and 53H of the shielding door 10F according to the sixth modification illustrated in FIG. 16(B), each of the eight doors is a rectangular plate-like member, and one side of the rectangular shape is fixed around the rotation axis 55 along the extension direction of the rotation axis 55. Furthermore, the eight doors 53A, 53B, 53C, 53D, 53E, 53F, 53G, and 53H are installed so that their main surfaces face the rotation direction of the rotation shaft 55. The eight doors 53A, 53B, 53C, 53D, 53E, 53F, 53G, and 53H are installed approximately every 45 degrees around the rotation shaft 55. That is, in the shielding door 10G according to the seventh modification, the predetermined angle at which the multiple doors of each of the revolving doors 51 and 52 are arranged is approximately 45 degrees.

[0154] On the other hand, the other revolving door 52, which is disposed on the Y positive side of the belt conveyor 6, has a rotation shaft 56 extending in the Z direction and eight doors 54A, 54B, 54C, 54D, 54E, 54F, 54G, and 54H disposed around the rotation shaft 56 in the direction in which the rotation shaft 56 extends. The eight doors 54A, 54B, 54C, 54D, 54E, 54F, 54G, and 54H are rectangular plate-like members, and one side of the rectangle extends along the direction in which the rotation shaft 56 extends. The eight doors 54A, 54B, 54C, 54D, 54E, 54F, 54G, and 54H are disposed so that their main surfaces face the direction in which the rotation shaft 56 rotates. The eight doors 54A, 54B, 54C, 54D, 54E, 54F, 54G, and 54H are arranged at approximately 45-degree intervals around a rotation axis 56.

[0155] Also, as shown in Figure 17, the positional relationship between the pair of revolving doors 51, 52 of the shielding door 10G is such that the rotation axes 55, 56 of each revolving door 51, 52 are installed at approximately the same position in the conveying direction, and one of the eight doors can be positioned in a straight line along the Y direction on the belt conveyor 6.

[0156] As shown in FIG. 17 , the pair of revolving doors 51, 52 rotates so that multiple doors 53, 54 move downstream in the conveyance direction to open, allowing PET bottles P to pass, and then rotates a predetermined angle (approximately 45 degrees) to close. For example, when door 53A of the eight doors of revolving door 51 and door 54A of the eight doors of revolving door 42 are aligned in a straight line along the Y direction on belt conveyor 6, shielding door 10G is closed. Thereafter, when a PET bottle P approaches, each of revolving doors 51, 52 rotates so that doors 53A, 54A move downstream in the conveyance direction. This opens shielding door 10G, allowing PET bottles P to pass. Furthermore, when each of revolving doors 51, 52 rotates 45 degrees, doors 53H, 54H adjacent to doors 53A, 54A are aligned in a straight line along the Y direction on belt conveyor 6, and shielding door 10G is closed again.

[0157] As shown in Figure 17, when the shielding door 10G of the seventh modified example is applied to the upstream shielding door group 4, similar to the sliding door type shielding door 10 described with reference to Figure 1, etc., the light blocking condition is such that either the shielding door 10G-1 on the upstream side in the conveying direction or the shielding door 10G-2 on the downstream side is closed.

[0158] In the shielding door 10G of the seventh modification, each revolving door 51, 52 can be rotated by power output from a drive source such as a motor. Furthermore, the transported plastic bottle P can be detected by a detection unit. When the detection unit detects the approach of a plastic bottle P, it drives the motor so that each revolving door 51, 52 rotates 45 degrees in accordance with the transport of the plastic bottle P. This allows the plastic bottle P to pass through the shielding door 10G. These motors and detection units correspond to the motor 14 and upstream detection unit 11 shown in FIG. 2 and other figures. Furthermore, the rotation control of the revolving doors 51, 52 using the motor and detection unit can be performed by elements similar to the control unit 13 shown in FIG. 2 and other figures.

[0159] The shielding door 10G of the seventh modified example, with the above-described configuration, can shorten the driving time of the motor and can also accommodate PET bottles P conveyed at a faster speed, thereby improving versatility.

[0160] In addition, in a configuration in which the shielding door 10F according to the sixth modified example or the shielding door 10G according to the seventh modified example is applied to the upstream shielding door group 4, it is also possible to give the shielding doors 10F and 10G the function of the pitch adjustment unit described above by controlling the timing at which the revolving door is rotated by the motor as appropriate.

[0161] 16 and 17 show an example of a configuration in which the shielding doors 10F and 10G are applied to the entrance-side shielding door group 4, but the configuration of the shielding door 20 of the exit-side shielding door group 5 can also be changed in the same way.

[0162] Here, with regard to the automatic system that uses a motor to control the opening and closing of the door, such as the shielding doors 10, 10A, 10B, 10F, and 10G, sensors such as the upstream detection unit 11 are used to detect PET bottles P, which are an example of an object to be transported, and the door is opened and closed accordingly, so there is no contact between the door and the PET bottles P, and it is possible to transport the PET bottles P without misalignment or damage. It is also possible to handle light and small objects such as empty bottles.

[0163] Furthermore, the method of pushing open the door with a plastic bottle P, as in the case of shielding doors 10C, 10D, and 10E, is a simple method and therefore very low cost. However, with light items such as empty bottles or small transported objects, the door may not be able to open or close properly due to the force of the door, so an automatic method is more preferable.

[0164] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Design modifications to these specific examples made by a person skilled in the art as appropriate are also included within the scope of the present disclosure as long as they comprise the features of the present disclosure. The elements of the above-described specific examples, as well as their arrangement, conditions, shape, etc., are not limited to those exemplified and can be modified as appropriate. The elements of the above-described specific examples can be combined in various ways as appropriate, as long as no technical contradictions arise.

[0165] In the above embodiment, a configuration has been illustrated in which the entrance-side shielding door group 4 is arranged upstream of the conveyance path within the enclosure 3 with respect to the marking position M of the laser marking device 2, and the exit-side shielding door group 5 is arranged downstream of the conveyance path within the enclosure 3 with respect to the marking position M. However, a configuration in which the shielding door group is arranged at least one of the upstream and downstream sides of the conveyance path within the enclosure 3 with respect to the marking position M may also be used. In other words, the marking system 1 may be configured to include either the entrance-side shielding door group 4 or the exit-side shielding door group 5. In this case, as with the conventional method described in Patent Document 1, a configuration in which a large number of strip-shaped members having a predetermined width, a predetermined length, and plasticity hang down vertically, a set of doors that can swing like a double door, or a door that can swing single-sided can be installed at the entrance 31 or the exit 32 of the enclosure 3 that is not provided with a shielding door group.

[0166] For example, aspects of the present invention are as follows. <1> a laser marking device that marks an object conveyed along a conveyance path with a laser beam; an enclosure installed to cover a marking position where marking by the laser marking device is performed on the conveying path, a portion including a plurality of the conveyed objects, and the laser marking device; a group of shielding doors arranged on at least one of the upstream side and the downstream side of the conveying path in the enclosure with respect to the marking position, the shielding doors blocking the laser light emitted from the laser marking device; Equipped with the group of shielding doors includes a plurality of shielding doors arranged at different positions in a conveying direction of the object conveyed along the conveying path, the plurality of shielding doors are arranged so as to overlap one another when viewed from the conveying direction and so as to overlap at least a portion of the object to be conveyed, At least one of the plurality of shielding doors is configured to open to allow the transported object to pass through, and the other shielding doors are configured to close. Marking system. <2> an upstream detection unit provided on the upstream side of the shielding door in the conveying direction and configured to detect passage of the conveyed object; a downstream detection unit provided downstream of the shielding door in the conveying direction and configured to detect passage of the conveyed object; a control unit for controlling the opening and closing operation of the shielding door; Equipped with When the upstream detection unit detects the transported object, the control unit opens the shielding door, When the downstream detection unit detects the transported object, the control unit closes the shielding door. The aforementioned <1> 10. The marking system according to claim 1 . <3> The shielding door is arranged to be slidable in a direction intersecting the conveying direction and includes two sliding doors arranged side by side in the sliding direction, the conveying path is arranged so that the object passes through a middle portion between the two doors; The two doors open by moving away from each other to allow the transported object to pass, and close by moving toward each other after the transported object has passed. The aforementioned <2> 10. The marking system according to claim 1 . <4> The shielding door is installed on the conveying path so as to be movable in a direction away from and toward a placement surface on which the conveyed object is placed, and opens when moved in a direction away from the placement surface and closes when moved in a direction toward the placement surface. The aforementioned <2> 10. The marking system according to claim 1 . <5> a light-shielding member that is non-transparent to laser light and is provided at an end of the shielding door on the side of the mounting surface; The aforementioned <4> 10. The marking system according to claim 1 . <6> a plurality of conveying devices arranged along the conveying direction, each of which places the object on the placement surface and conveys the object along the conveying direction; the shielding door is disposed at a boundary between two adjacent transport devices among the plurality of transport devices, When the shielding door is closed, it moves to a position below the placement surfaces of the two conveying devices. The aforementioned <4> 10. The marking system according to claim 1 . <7> a conveying device that places the object on the placement surface and conveys it along the conveying direction, the conveying device is a belt conveyor that moves a belt wound around a roller in the conveying direction by rotating a roller, and the placement surface is a surface of the belt that is disposed above the belt conveyor, the belt conveyor has a group of rollers that move the belt below the placement surface at a position in the conveying direction where the shielding door is disposed, thereby creating a gap on the placement surface; the shielding door moves so that an end portion of the shielding door on the placement surface side enters the gap formed by the roller group when the shielding door is closed. The aforementioned <4> 10. The marking system according to claim 1 . <8> the shielding door is disposed above the object being transported along the transport path and includes a rotation shaft extending in a direction intersecting the transport direction, the shielding door is disposed opposite to the conveying direction, and opens by rotating about the rotation axis toward the downstream side in the conveying direction, and closes by rotating from the open state toward the upstream side in the conveying direction to a position opposite to the conveying direction. The aforementioned <2> 10. The marking system according to claim 1 . <9> the shielding door includes a pair of revolving doors arranged opposite to each other in the conveying direction, The revolving door includes a plurality of doors at predetermined angles around a rotation axis, the pair of revolving doors rotates so that the plurality of doors move downstream in the conveying direction to open, allowing the conveyed object to pass, and rotates by the predetermined angle to close; The aforementioned <2> 10. The marking system according to claim 1 . <10> the control unit sets the opening / closing speed of the shielding door based on the shape and conveying speed of the transported object. The aforementioned <2> ~ <9> 10. The marking system according to claim 9, <11> The opening and closing speed of the shielding door is When the diameter of the transported object is Bd, the transport speed is Bv, the distance between the shielding door and the transported object is Dh, and the opening / closing speed is Dv, the settings are made so as to satisfy the conditional expression (10) above. <10> 10. The marking system according to claim 1 . <12> The control unit sets the opening and closing time of the shielding door based on a diameter of the transported object, a margin of freedom in the opening and closing direction of the shielding door, and an opening and closing speed of the shielding door. The aforementioned <2> ~ <11> 10. The marking system according to claim 9, <13> The opening and closing time of the shielding door is When the diameter of the conveyed object is Bd, the margin is Dw, the opening / closing speed is Dv, and the opening / closing time is t, they are set so as to satisfy the conditional expression (11) above. The aforementioned <12> 10. The marking system according to claim 1 . <14> the shielding door is a push-open door that is rotated toward the downstream side of the conveying direction and pushed open by the object being conveyed along the conveying path, and that is rotated toward the upstream side of the conveying direction and closed after the object has passed through, The aforementioned <1> 10. The marking system according to claim 1 . <15> the plurality of shielding doors include two types of doors, each of which has a rotation axis provided in a vertical direction on both sides of a width direction that is a direction perpendicular to the conveying direction and is horizontal, the two types of doors are arranged such that ends on the center side in the width direction come into contact with at least a part of the object being transported along the transport path, The shielding door group has the two types of doors arranged alternately along the conveying direction. The aforementioned <14> 10. The marking system according to claim 1 . <16> the shielding door includes two double doors arranged opposite to each other in the conveying direction, The conveying path is arranged so that the object passes through the middle of the two doors and pushes open the two doors. The aforementioned <14> 10. The marking system according to claim 1 . <17> A light-blocking member that is non-transparent to laser light and closes the gap in the middle portion is provided at an end portion of at least one of the two doors on the middle portion side. The aforementioned <16> 10. The marking system according to claim 1 . <18> the shielding door group is disposed on both the upstream side and the downstream side of the transport path within the enclosure with respect to the marking position; The aforementioned <1> ~ <17> 10. The marking system according to claim 9, <19> the group of shielding doors is arranged at predetermined intervals along the conveying direction so that both of the two shielding doors are closed when there are N and N+1 pieces of the transported objects between two adjacent shielding doors among the plurality of shielding doors. The aforementioned <1> ~ <18> 10. The marking system according to claim 9, <20> a conveying device that places the object on a placement surface on the conveying path and conveys the object along the conveying direction, The aforementioned <1> ~ <19> 10. The marking system according to claim 9, [Explanation of symbols]

[0167] 1. Marking System 2 Laser marking equipment 3 Enclosure 4 Entrance side shielding doors 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G Shielding Door 17, 18 Two sliding doors 11 Upstream detection unit 12 Downstream detection section 13 Control Unit 5. Exit side shielding doors 20 Shielding Door 6, 6A, 6B Belt conveyor (transport device) 61 Laura 62 Belt 63 Boundary 64 Placement surface 68 Roller Group L laser light P PET bottle (transported item) M marking position [Prior art documents] [Patent documents]

[0168] [Patent Document 1] Japanese Patent Publication No. 2022-058203

Claims

1. a laser marking device that marks an object conveyed along a conveyance path with a laser beam; an enclosure installed to cover a marking position where marking by the laser marking device is performed on the conveying path, a portion including a plurality of the conveyed objects, and the laser marking device; a group of shielding doors arranged on at least one of the upstream side and the downstream side of the conveying path in the enclosure with respect to the marking position, the shielding doors blocking the laser light emitted from the laser marking device; Equipped with the group of shielding doors includes a plurality of shielding doors arranged at different positions in a conveying direction of the object conveyed along the conveying path, the plurality of shielding doors are arranged so as to overlap one another when viewed from the conveying direction and so as to overlap at least a portion of the object to be conveyed, At least one of the plurality of shielding doors is configured to open to allow the transported object to pass through, and the other shielding doors are configured to close. Marking system.

2. an upstream detection unit provided on the upstream side of the shielding door in the conveying direction and configured to detect passage of the conveyed object; a downstream detection unit provided downstream of the shielding door in the conveying direction and configured to detect passage of the conveyed object; a control unit for controlling the opening and closing operation of the shielding door; Equipped with When the upstream detection unit detects the transported object, the control unit opens the shielding door, When the downstream detection unit detects the transported object, the control unit closes the shielding door. The marking system of claim 1 .

3. The shielding door is arranged to be slidable in a direction intersecting the conveying direction and includes two sliding doors arranged side by side in the sliding direction, the conveying path is arranged so that the article passes through a middle portion between the two doors; the two doors open by moving in directions away from each other to allow the transported article to pass, and close by moving in directions toward each other after the transported article has passed; The marking system of claim 2 .

4. The shielding door is installed on the conveying path so as to be movable in a direction away from and toward a placement surface on which the conveyed object is placed, and opens when moved in a direction away from the placement surface and closes when moved in a direction toward the placement surface. The marking system of claim 2 .

5. a light-shielding member that is non-transparent to laser light and is provided at an end of the shielding door on the side of the mounting surface; The marking system of claim 4.

6. a plurality of conveying devices arranged along the conveying direction, each of which places the object on the placement surface and conveys the object along the conveying direction; the shielding door is disposed at a boundary between two adjacent transport devices among the plurality of transport devices, When the shielding door is closed, it moves to a position below the placement surfaces of the two conveying devices. The marking system of claim 4.

7. a conveying device that places the object on the placement surface and conveys it along the conveying direction, the conveying device is a belt conveyor that moves a belt wound around a roller in the conveying direction by rotating a roller, and the placement surface is a surface of the belt that is disposed above the belt conveyor, the belt conveyor has a group of rollers that move the belt below the placement surface at a position in the conveying direction where the shielding door is disposed, thereby creating a gap on the placement surface; the shielding door moves so that an end portion of the shielding door on the placement surface side enters the gap formed by the roller group when the shielding door is closed. The marking system of claim 4.

8. the shielding door is disposed above the object being transported along the transport path and includes a rotation shaft extending in a direction intersecting the transport direction, the shielding door is disposed opposite to the conveying direction, and opens by rotating about the rotation axis toward the downstream side in the conveying direction, and closes by rotating from the open state toward the upstream side in the conveying direction to a position opposite to the conveying direction. The marking system of claim 2 .

9. the shielding door includes a pair of revolving doors arranged opposite to each other in the conveying direction, The revolving door includes a plurality of doors at predetermined angles around a rotation axis, the pair of revolving doors rotates so that the plurality of doors move downstream in the conveying direction to open, allowing the conveyed object to pass, and rotates by the predetermined angle to close; The marking system of claim 2 .

10. the control unit sets the opening / closing speed of the shielding door based on the shape and conveying speed of the transported object. The marking system of claim 2 .

11. The opening and closing speed of the shielding door is The marking system according to claim 10, wherein the system is set to satisfy the following conditional expression, where Bd is the diameter of the transported object, Bv is the transport speed, Dh is the distance between the shielding door and the transported object, and Dv is the opening / closing speed. [Equation 1]

12. The control unit sets the opening and closing time of the shielding door based on a diameter of the transported object, a margin of freedom in the opening and closing direction of the shielding door, and an opening and closing speed of the shielding door. The marking system of claim 2 .

13. The opening and closing time of the shielding door is 13. The marking system according to claim 12, wherein the following conditional expression is satisfied, where Bd is the diameter of the transported object, Dw is the margin, Dv is the opening / closing speed, and t is the opening / closing time. [Equation 2]

14. the shielding door is a push-open door that is rotated toward the downstream side of the conveying direction and pushed open by the object being conveyed along the conveying path, and that is rotated toward the upstream side of the conveying direction and closed after the object has passed through, The marking system of claim 1 .

15. the plurality of shielding doors include two types of doors, each of which has a rotation axis provided in a vertical direction on both sides of a width direction that is a direction perpendicular to the conveying direction and is horizontal, the two types of doors are arranged such that ends on a central side in the width direction come into contact with at least a part of the object being transported along the transport path, The shielding door group has the two types of doors arranged alternately along the conveying direction.

15. The marking system of claim 14.

16. the shielding door includes two double-door doors arranged opposite to each other in the conveying direction, The conveying path is arranged so that the article passes through the middle portion of the two doors and pushes open the two doors.

15. The marking system of claim 14.

17. a light-blocking member that is non-transparent to laser light and closes the gap in the middle portion is provided at an end portion of at least one of the two doors on the middle portion side; 17. The marking system of claim 16.

18. the shielding door group is disposed on both the upstream side and the downstream side of the transport path within the enclosure with respect to the marking position; The marking system of claim 1 .

19. the group of shielding doors is arranged at predetermined intervals along the conveying direction so that both of the two shielding doors are closed when there are N and N+1 articles between two adjacent shielding doors among the plurality of shielding doors. The marking system of claim 1 .

20. a conveying device that places the object on a placement surface on the conveying path and conveys the object along the conveying direction, The marking system of claim 1 .

Images