Printing device and printing method

Abstract

To provide a printing device and a printing method that can efficiently provide printing on a three-dimensional object to be printed.SOLUTION: A printing device 1 includes: a print head 200 for discharging a printing material; and a relative movement mechanism 300 for moving the print head 200 in a printing direction relatively to a three-dimensional object to be printed 10. The relative movement mechanism 300 includes a main turning mechanism 310 for turning the object to be printed 10 about a main turning center C1.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a printing apparatus and a printing method for printing on a three-dimensional printing substrate. [Background technology]

[0002] Conventionally, packaging boxes made by folding materials such as cardboard have been widely used as packaging boxes for storing various items. Some of these packaging boxes have various information such as the product name, quantity, and precautions for the contents printed on the surface along with various decorative designs. By printing such information on the surface of the packaging box, not only can information about the contents be obtained without opening the packaging box, but the contents can also be advertised and promoted while still contained in the packaging box.

[0003] Generally, printing on such packaging boxes is performed by flexographic printing on flat material before the box is made. Meanwhile, with the spread of inkjet printing devices that print by ejecting a printing material (ink) toward a substrate, a method of printing various information on the sides of a packaging box that has become three-dimensional after the box is made or the contents are placed inside has been used in recent years (see, for example, Patent Document 1). By printing in this way after the box is made or the contents are placed inside, it becomes possible to print information that is individually tailored to the placed contents or the packaging box used, such as the manufacturing date or lot number. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-16462 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as shown in Patent Document 1, conventional printing devices that print after boxes are made are stuck on the old-fashioned idea of ​​printing on the substrate while it is being transported, so there is a problem in that if you want to print on all four sides of a rectangular packaging box, for example, you need multiple print heads.

[0006] In view of the above circumstances, the present invention aims to provide a printing device and a printing method that are capable of efficiently printing on a three-dimensional printing substrate. [Means for solving the problem]

[0007] The printing device of the present invention comprises a print head that ejects printing material, and a relative movement mechanism that moves the print head relative to a three-dimensional substrate in the printing direction, and the relative movement mechanism is characterized by having a main rotation mechanism that rotates the substrate around a main rotation center.

[0008] The printing method of the present invention is characterized in that, in a printing method in which a print head that ejects printing material is moved relative to a three-dimensional printing object in a printing direction, the printing object is rotated around a main rotation center.

[0009] According to the printing device and printing method of the present invention, by rotating the printing substrate around the main rotation center, it is possible to avoid increasing the complexity and size of the printing device and to have all of the multiple surfaces of a three-dimensional printing substrate positioned around the main rotation center face one print head.In other words, even with a simple and compact configuration, it is possible to print on all of the multiple surfaces positioned around the main rotation center with one print head, making it possible to efficiently print on three-dimensional printing substrates.

[0010] In the printing apparatus of the present invention, it is preferable that the relative movement mechanism has an auxiliary rotation mechanism that rotates the print head around an auxiliary rotation center that is parallel to the main rotation center.

[0011] This allows the ejection direction of the printing material to be maintained approximately perpendicular to the surface being printed during printing, while still maintaining a simple and compact configuration, thereby improving print quality.

[0012] In the printing apparatus of the present invention, it is preferable that the relative movement mechanism has a linear movement mechanism that moves the print head relatively toward or away from the main rotation center.

[0013] If the distance between the surface to be printed and the print head (the distance the printing material is ejected) is to be kept approximately constant during printing, the print head needs to be moved relatively closer to and away from the substrate. However, by moving the print head relatively closer to and away from the main rotation center, it is possible to minimize the distance of relative movement, thereby making the printing device more compact.

[0014] Furthermore, for example, when the printing substrate is rotated at a substantially constant rotational speed (angular velocity), the relative speed between the print head and the printing substrate in the direction along the surface to be printed, i.e., the printing speed, changes depending on the rotation angle, but by moving the print head relative to the main rotation center so that it approaches or moves away from the center, it is possible to minimize the change in printing speed in this case. This makes it easier to control the printing speed to maintain a substantially constant speed, and improves print quality.

[0015] Furthermore, it is preferable that the printing device of the present invention further comprises a control unit that controls the relative movement mechanism so as to change the rotation speed of the printing substrate based on the rotation angle of the printing substrate caused by the main rotation mechanism.

[0016] This makes it possible to appropriately adjust the printing speed, which changes when the rotation speed of the substrate is kept approximately constant, thereby simplifying control of the print head and improving print quality.

[0017] Furthermore, it is preferable that the printing device of the present invention further comprises a control unit that controls the print head so as to change the ejection timing of the printing material based on the angle of rotation of the printing substrate by the main rotation mechanism.

[0018] This makes it possible to appropriately adjust the timing of printing material ejection to match the printing speed, which changes depending on the rotation angle of the substrate, thereby simplifying the control of the relative movement mechanism and improving printing quality. [Effects of the Invention]

[0019] The printing device and printing method of the present invention can provide the excellent effect of being able to efficiently print on a three-dimensional printing substrate. [Brief explanation of the drawings]

[0020] [Figure 1] 1A is a schematic plan view of a printing device according to an embodiment of the present invention, and FIG. 1B is a schematic front view of the printing device. [Figure 2] 1A is a schematic plan view showing the relative positional relationship between the packaging box and the print head during printing, and FIG. 1B is a diagram showing the geometric relationship between the main rotation center, auxiliary rotation center, print start position, and print position during printing. [Figure 3] 1A to 1C are schematic plan views showing the operation of the printing device. [Figure 4] 1A to 1C are schematic plan views showing the operation of the printing device. [Figure 5] Graph A shows the change in print distance during printing when the turntable rotation speed is kept approximately constant, and graph B shows the change in print speed during printing when the turntable rotation speed is kept approximately constant. [Figure 6] 10A to 10C are schematic plan views showing modified examples of the printing device. [Figure 7] 10A and 10B are schematic plan views showing modified examples of the printing device. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that in the following drawings, the description has been simplified by omitting some parts, etc. Fig. 1A is a schematic plan view of a printing device 1 according to one embodiment of the present invention, and Fig. 1B is a schematic front view of the printing device 1.

[0022] The printing device 1 of this embodiment is for printing on four sides of a rectangular parallelepiped packaging box 10 (i.e., a three-dimensional printing object) shown by the two-dot chain lines in Figures 1A and 1B, specifically a first long side 11, a first short side 12, a second long side 13, and a second short side 14. In this embodiment, the printing device 1 is arranged downstream of the box sealing machine on the packaging line, and is configured to print on the packaging box 10 in a state in which the contents are placed inside and sealed after box making, i.e., in a state in which a top surface 15 and a bottom surface 16 are formed.

[0023] The packaging box 10 is carried into the printer 1, for example, from the lower side in FIG. 1A by an appropriate conveying device (not shown), and is carried out to the upper side in FIG. 1B after printing is completed. The configuration of the conveying device is not particularly limited, and an existing device can be used. The conveying device may be an external device or may be provided within the printer 1.

[0024] As shown in Figures 1A and 1B, the printing device 1 is composed of a stand 100 that supports each part of the printing device 1, a print head 200 that ejects printing material, a relative movement mechanism 300 that moves the print head 200 in the printing direction relative to the packaging box 10, and a control unit 400 that controls the print head 200 and the relative movement mechanism 300.

[0025] The stand 100 configures the printing device 1 as a single unit and adjusts the height of the placement surface for the packaging box 10 to the height of the conveying surface of the packaging line. In this embodiment, by configuring the printing device 1 as a unit, it is easy to add it to an existing packaging line.

[0026] In this embodiment, the print head 200 performs printing by an inkjet method. That is, the print head 200 is configured to perform printing by intermittently ejecting droplets of a printing material (ink) from nozzles 210 toward the packaging box 10 and depositing the printing material onto the surface of the packaging box 10 to be printed, thereby forming a plurality of dots that are arranged in the printing direction. The print head 200 may perform color printing or monochrome printing.

[0027] The relative movement mechanism 300 moves the print head 200 relatively along the first long side surface 11, the second long side surface 12, the first short side surface 13, and the second short side surface 14 of the packaging box 10. The relative movement mechanism 300 is made up of a main rotation mechanism 310 that rotates the packaging box 10, an auxiliary rotation mechanism 320 that rotates the print head 200, and a linear movement mechanism 330 that moves the print head 200 back and forth linearly together with the auxiliary rotation mechanism 320.

[0028] The main rotation mechanism 310 is composed of a turntable 311 on which the packaging box 10 is placed, a drive device 312 that drives the turntable 311, and a rotation angle detector 313 that detects the rotation angle θ (see Figure 2A) of the turntable 311.

[0029] The turntable 311 is configured so that the packaging box 10 can be placed on an upper surface 311a and can rotate about a main rotation center C1 set in a substantially vertical direction. The turntable 311 is configured in a disk shape with the main rotation center C1 as its axis, and is supported by the stand 100 so as to be rotatable about the main rotation center C1. In this embodiment, the upper surface 311a is configured to generate an appropriate friction force between itself and the bottom surface 16 of the packaging box 10, thereby positioning the packaging box 10 on the turntable 311.

[0030] The driving device 312 is composed of an appropriate motor, and is fixed to the base 100 below the turntable 311, with its output shaft connected to the turntable 311. The rotation angle detector 313 is composed of an appropriate rotary encoder, and is connected to the driving device 312. Note that the rotation angle detector 313 may be connected to the turntable 311.

[0031] In this embodiment, the packaging box 10 is placed on the turntable 311 by a conveying device (not shown) so that the centers of the top surface 15 and the bottom surface 16 are substantially aligned with the main rotation center C1. As a result, the first long side surface 11, the first short side surface 12, the second long side surface 13, and the second short side surface 14 of the packaging box 10 are positioned around the main rotation center C1, and as the packaging box 10 rotates together with the turntable 311 clockwise in a plan view around the main rotation center C1, they are sequentially positioned on the side where the print head 200 is located (the right side in FIGS. 1A and 1B ).

[0032] The auxiliary rotation mechanism 320 is composed of a support structure 321 that rotatably supports the print head 200, a drive device 322 that drives and rotates the print head 200, and a rotation angle detector 323 that detects the rotation angle of the print head 200.

[0033] The support structure 321 is configured to support the print head 200 rotatably about an auxiliary rotation center C2 that is set substantially parallel to the main rotation center C1 (i.e., substantially vertically). The support structure 321 is composed of a U-shaped support member 321a and a rotation shaft 321b that is fixed to the print head 200 and rotatably supported by the support member 321a, and the axis of the rotation shaft 321b coincides with the auxiliary rotation center C2.

[0034] The driving device 322 is made up of an appropriate motor, is fixed to the upper side of the support member 321a, and has an output shaft connected to the rotation shaft 321b. The rotation angle detector 323 is made up of an appropriate rotary encoder, and is connected to the driving device 322. Note that the rotation angle detector 323 may be connected to the rotation shaft 321b.

[0035] The linear movement mechanism 330 is composed of a ball screw transmission device 331 that moves the print head 200 and the auxiliary rotation mechanism 320 back and forth in a linear manner, a drive device 332 that drives the ball screw transmission device 331, and a movement distance detector 333 that detects the movement distance of the print head 200 and the auxiliary rotation mechanism 320.

[0036] The ball screw transmission device 331 is disposed so as to linearly reciprocate the print head 200 and the auxiliary rotation mechanism 320 along a linear path R that is substantially perpendicular to the main rotation center C1 in a substantially horizontal plane. The ball screw transmission device 331 has a known structure made up of a screw shaft and a nut (not shown), and is supported by the base 100 with the screw shaft substantially parallel to the linear path R. A support member 321a of the auxiliary rotation mechanism 320 is fixed to a flat-plate-shaped moving member 331a fixed to the nut, and the auxiliary rotation center C2 is substantially perpendicular to the linear path R.

[0037] The driving device 332 is composed of an appropriate motor, is fixed to the base 100, and has an output shaft connected to the screw shaft of the ball screw transmission device 331. The moving distance detector 333 is composed of an appropriate rotary encoder, and is connected to the driving device 322. Note that the moving distance detector 333 may be connected to the screw shaft of the ball screw transmission device 331.

[0038] The linear movement mechanism 330 moves the print head 200 and auxiliary rotation mechanism 320 back and forth linearly so as to move them closer to or farther away from the packaging box 10, but in this embodiment, the linear movement mechanism 330 is arranged so as to move the print head 200 and auxiliary rotation mechanism 320 closer to or farther away from the main rotation center C1. As will be described in detail later, this arrangement makes it possible to make the printing device 1 compact, and to facilitate control for maintaining a substantially constant movement speed Vp of the printing position P during printing (i.e., printing speed) and improve printing quality.

[0039] The control unit 400 has a known configuration including a CPU, ROM, RAM, and auxiliary storage device, and controls the operation of the print head 200 and the relative movement mechanism 300 by executing a program stored in the ROM or the like. In this embodiment, the control unit 400 is provided as a dedicated computer supported by the stand 100, but the control unit 400 may also be configured as an appropriate external computer or the like.

[0040] The control unit 400 controls the print head 200 to eject the printing material intermittently at preset intervals. The control unit 400 also controls the drive devices 312 to 332 to move the print head 200 relative to the packaging box 10 in the printing direction. Specifically, the control unit 400 maintains the ejection direction of the printing material substantially perpendicular to the surface to be printed, and maintains the distance between the nozzle 210 and the printing position P where the printing material ejected from the nozzle 210 adheres (the ejection distance of the printing material) substantially constant. The control unit 400 also moves the packaging box 10 and the print head 200 relative to each other so that the printing position P moves in the printing direction at a speed corresponding to the ejection interval of the printing material.

[0041] In this embodiment, the packaging box 10 is transported into the printing device 1 with the first long side surface 11 positioned on the print head 200 side and with the first long side surface 11 positioned approximately perpendicular to the linear path R. Therefore, the centers of the top surface 15 and the bottom surface 16 are approximately aligned with the main rotation center C1, and therefore the printing start position P0, which is the initial printing position P, is located approximately in the middle of the first long side surface 11 in the horizontal direction (width direction).

[0042] FIG. 2A is a schematic plan view showing the relative positional relationship between the packaging box 10 and the print head 200 during printing, and FIG. 2B is a diagram showing the geometric relationship between the main rotation center C1, the auxiliary rotation center C2, the print start position P0, and the print position P during printing.

[0043] 2A and 2B, the distance from the main rotation center C1 to the first long side surface 11 or the second long side surface 13 is designated as L1, the distance from the main rotation center C1 to the first short side surface 12 or the second short side surface 14 is designated as L2, and the distance from the auxiliary rotation center C2 to the printing position P is designated as L3. Note that the distance L1 is 1 / 2 of the horizontal (width) dimension of the first long side surface 11 and the second long side surface 13, and the distance L2 is 1 / 2 of the horizontal (width) dimension of the first short side surface 12 and the second short side surface 14.

[0044] 2A, the control unit 400 controls the auxiliary rotation mechanism 320 to rotate the print head 200 and the linear movement mechanism 330 to linearly move the print head 200 and the auxiliary rotation mechanism 320 in synchronization with the rotation of the packaging box 10 by the main rotation mechanism 310. At this time, the ejection direction of the printing material is maintained substantially perpendicular to the first long side surface 11, and the distance L3 is maintained substantially constant, thereby maintaining the ejection distance of the printing material substantially constant.

[0045] Therefore, after printing starts, while printing is being performed on the first long side surface 11, the rotation angle of the print head 200 is the same as the rotation angle θ of the packaging box 10. During this time, the print head 200 moves in a direction away from the packaging box 10 as the rotation angle θ increases. The movement distance Dm from the initial position of the print head 200 at this time (the position when the printing position P is the printing start position P0) can be calculated from the geometric relationship shown in FIG. 2B, for example, by the following equation (1). Dm=L1 / Cosθ+L3 / Cosθ-L1-L3...(1)

[0046] Furthermore, from the geometric relationship shown in Figure 2B, after printing starts, the distance (i.e., printing distance) Dp from the printing start position P0 to the printing position P while printing on the first long side surface 11 is performed can be calculated, for example, by the following equation (2). Dp=L1Tanθ+L3Tanθ (2)

[0047] 3A-C and 4A-C are schematic plan views showing the operation of the printing device 1. As shown in FIG. 3A, the print head 200 is in a standby state with the printing position P set to the print start position P0. When a packaging box 10 is placed on the turntable 311, the control unit 400 causes the print head 200 to start discharging printing material. At the same time, the control unit 400 rotates the turntable 311 and the print head 200 in the same direction (clockwise in plan view in this embodiment) at the same rotational speed (angular velocity). The control unit 400 also moves the print head 200 and the auxiliary rotation mechanism 320 in a direction away from the packaging box 10 so that the movement distance Dm from the initial position (the position shown in FIG. 3A) corresponds to the rotation angle θ of the turntable 311.

[0048] 3B, the printing position P where the printing material is applied moves away from the printing start position P0 as the turntable 311 rotates. In other words, the position where the printing material is applied shifts horizontally, and printing is performed on the first long side surface 11.

[0049] 3C, when printing position P reaches the end of first long side surface 11 on the side of first short side surface 12, control unit 400 causes print head 200 to stop discharging printing material. At this point, printing on half of the area of ​​first long side surface 11 is completed. Note that the printing distance Dp when printing position P reaches the end of first long side surface 11 is distance L2, and therefore angle θ1 at this time can be calculated, for example, from the following equation (3). θ1=Arctan{L2 / (L1+L3)}···(3)

[0050] That is, the control unit 400 can determine that the printing position P has reached the end of the first long side surface 11 based on the rotation angle θ detected by the rotation angle detector 323.

[0051] 4A, the control unit 400 continues to rotate the turntable 311 even after causing the print head 200 to stop discharging the printing material. Then, the control unit 400 temporarily moves the print head 200 and the auxiliary rotation mechanism 320 away from the packaging box 10 to avoid contact with the packaging box 10, and rotates the print head 200 in the opposite direction (counterclockwise).

[0052] The print head 200 continues to rotate in the opposite direction until it reaches an angle at which printing begins on the first short side surface 12. After avoiding contact with the packaging box 10, the control unit 400 also moves the print head 200 and the auxiliary rotation mechanism 320 in a direction approaching the packaging box 10, so that the print head 200 is ready to print on the end of the first short side surface 12 on the first long side surface 11 side when the turntable 311 has rotated by the angle θ2, as shown in FIG.

[0053] That is, the control unit 400 controls the auxiliary rotation mechanism 320 and the linear movement mechanism 330 so that, when the turntable 311 has rotated by the angle θ2, the ejection direction of the printing material becomes approximately perpendicular to the first short side surface 12 and the distance L3 becomes a preset distance. The angle θ2 is calculated from the following equation (4). θ2=90-Arctan{L1 / (L2+L3)}···(4)

[0054] The second term on the right side of equation (4) is a replacement of L1 and L2 in equation (3), and the rotation angle from the initial position of print head 200 in the state shown in Figure 4B (the position when print position P is the print start position P0) is the negative angle (counterclockwise angle) indicated by the second term on the right side of equation (4).

[0055] 4B is reached, the control unit 400 causes the print head 200 to start discharging the printing material and rotates the print head 200 in the same direction (clockwise) at the same rotation speed as the turntable 311. The control unit 400 also moves the print head 200 and the auxiliary rotation mechanism 320 in a direction approaching the packaging box 10 so that the movement distance Dm corresponds to the rotation angle θ of the turntable 311. The movement distance Dm at this time can be calculated, for example, from the following equation (5). Dm=L2 / Cos(90-θ)+L3 / Cos(90-θ)-L1-L3...(5)

[0056] Then, when the rotation angle θ reaches 90 degrees, the packaging box 10 and the print head 200 return to the same state as the initial state (the state when the printing position P is at the printing start position P0) shown in Fig. 3A, as shown in Fig. 4C. Therefore, by repeating the same operation as described above three times from this point onwards, printing is performed over the entire horizontal range of the first long side surface 11, the first short side surface 12, the second long side surface 13, and the second short side surface 14.

[0057] FIG. 5A is a graph showing the change in printing distance Dp during printing when the rotation speed of turntable 311 is kept approximately constant, and FIG. 5B is a graph showing the change in printing speed Vp during printing when the rotation speed of turntable 311 is kept approximately constant.

[0058] 5A and 5B, θ1 is the rotation angle when printing half of the first long side surface 11 is first completed, and θ8 is the rotation angle when printing the remaining half of the first long side surface 11 is finally started. θ2 is the rotation angle when printing of the first short side surface 12 is started, and θ3 is the rotation angle when printing of the first short side surface 12 is completed. θ4 is the rotation angle when printing of the second long side surface 13 is started, and θ5 is the rotation angle when printing of the second long side surface 13 is completed. θ6 is the rotation angle when printing of the second short side surface 14 is started, and θ7 is the rotation angle when printing of the second short side surface 14 is completed.

[0059] As shown in Fig. 5A, when the rotation speed of the turntable 311 is kept substantially constant, the change in printing distance Dp during printing on each side surface 11-14 is not a straight line proportional to the rotation angle θ, but an S-shaped curve. This is because, as shown in Fig. 5B, the printing speed Vp increases the closer to both ends of each side surface 11-14 in the water direction, and this speed change becomes more pronounced the larger the horizontal dimension of each side surface 11-14.

[0060] For this reason, in this embodiment, the rotation speed of the turntable 311 is appropriately changed based on the rotation angle θ of the turntable 311 while printing on each of the side surfaces 11 to 14, thereby keeping the printing speed Vp approximately constant.

[0061] That is, the control unit 400 controls the drive device 312 of the main rotation mechanism 310 so that the rotation speed of the turntable 311 decreases as the rotation angle θ approaches angles θ1 to θ8 (as the printing position P approaches both ends of each side surface 11 to 14 in the water direction), and also controls the drive device 322 of the auxiliary rotation mechanism 320 and the drive device 332 of the linear movement mechanism 330 so as to synchronize with the change in the rotation speed of the turntable 311.

[0062] This eliminates the need to change the timing of ejecting the printing material in accordance with changes in the printing speed Vp that accompany changes in the rotation angle θ, thereby simplifying the control of the print head 200. Furthermore, while simplifying the control of the print head 200, it is possible to deposit the printing material in appropriate positions and arrange dots, thereby improving print quality.

[0063] In addition, since the printing speed Vp also changes when the drive devices 312 to 332 are started, stopped, or accelerated or decelerated when the rotation direction is changed, the control unit 400 changes the timing of ejection of the printing material when the drive devices 312 to 332 are accelerated or decelerated.

[0064] As described above, in this embodiment, by rotating the packaging box 10 around the main rotation center C1, it is possible to print on all of the first long side surface 11, the first short side surface 12, the second long side surface 13, and the second short side surface 14 without increasing the operating range of the print head 200. This allows the entire device to be configured simply and compactly, and enables printing on the packaging box 10 to be performed quickly and efficiently. Furthermore, by making the entire device compact, the installation space is reduced, making it easier to incorporate into existing packaging lines.

[0065] In this embodiment, the print quality is improved by rotating the print head 200 around the auxiliary rotation center C2 using the auxiliary rotation mechanism 320 and maintaining the direction of printing material ejection approximately perpendicular to the surface to be printed. Furthermore, in this embodiment, the print head 200 is moved toward or away from the packaging box 10 using the linear movement mechanism 330, maintaining the printing material ejection distance approximately constant, thereby also improving print quality.

[0066] Furthermore, in this embodiment, the linear movement mechanism 330 is positioned so that the linear path R is approximately perpendicular to the main rotation center C1 in an approximately horizontal plane, and the print head 200 and the auxiliary rotation mechanism 320 are positioned close to and away from the main rotation center C1, thereby making it possible to configure the printing device 1 compactly.

[0067] Specifically, if the linear movement mechanism 330 is disposed offset upward or downward in FIG. 1A from the main rotation center C1, the movement distance Dm increases due to the amount of offset of the linear path R from the main rotation center C1. For this reason, in this embodiment, the linear path R is not offset from the main rotation center C1 (i.e., is approximately perpendicular), thereby minimizing the movement distance Dm. This reduces the dimension of the printing device 1 in the left-right direction in FIG. 1A, making it possible to make the printing device 1 more compact.

[0068] Furthermore, in this embodiment, the linear movement mechanism 330 is positioned so that the linear path R is approximately perpendicular to the main rotation center C1 in an approximately horizontal plane, and the print head 200 and auxiliary rotation mechanism 320 are moved closer to or farther away from the main rotation center C1, thereby facilitating control to maintain a substantially constant printing speed Vp and improving print quality.

[0069] Specifically, if the linear motion mechanism 330 is positioned offset above or below the main rotation center C1 in FIG. 1A, the offset of the linear path R from the main rotation center C1 increases the change in the printing speed Vp during printing, as shown in FIG. 5B. For this reason, in this embodiment, the linear path R is not offset from the main rotation center C1, thereby minimizing the change in the printing speed Vp during printing. This facilitates control to maintain a substantially constant printing speed Vp, making it possible to improve print quality.

[0070] Furthermore, in this embodiment, the printing speed Vp is kept approximately constant by appropriately changing the rotation speed of the turntable 311 based on the rotation angle θ of the turntable 311, thereby simplifying the control of the print head 200 and improving the printing quality.

[0071] Note that the change in the rotation speed of the turntable 311 based on the rotation angle θ does not have to keep the printing speed Vp approximately constant. That is, for example, the rotation speed of the turntable 311 may be changed so that the printing speed Vp does not exceed the changeable range of the timing at which the printing material is ejected from the print head 200. In this case, the control unit 400 controls both the change in the rotation speed of the turntable 311 based on the rotation angle θ and the change in the timing at which the printing material is ejected based on the rotation angle θ.

[0072] Furthermore, even if the rotation speed of the turntable 311 is kept substantially constant, if the printing speed Vp does not exceed the range in which the ejection timing of the printing material in the print head 200 can be changed, it is also possible to change only the ejection timing of the printing material based on the rotation angle θ of the turntable 311. In this way, it is possible to simplify the control of the relative movement mechanism 300 and improve the print quality.

[0073] Next, a description will be given of modified examples of the printing device 1. Figures 6A to 6C and Figures 7A and 7B are schematic plan views showing modified examples of the printing device 1.

[0074] 6A shows an example of a case where the positioning mechanism 314 is provided in the printing device 1. In this way, the main rotation mechanism 310 may be equipped with a positioning mechanism that positions the packaging box 1 on the turntable 311 by, for example, contacting any part of the packaging box 10. In this case, the packaging box 10, which is the printing substrate, can be positioned more accurately, thereby further improving print quality. The type of the positioning mechanism 314 is not particularly limited, and various known types can be adopted.

[0075] 6B shows an example of a case where a distance sensor 500 that detects the distance between the print head 200 and the surface to be printed is provided in the printing device 1. In this way, for example, by providing two distance sensors 500 at positions appropriately spaced apart in the horizontal direction, it is possible to detect the distance between the print head 200 and the surface to be printed, and the attitude of the print head 200 with respect to the surface to be printed, and the control unit 400 can appropriately correct the control of the print head 200 and the relative movement mechanism 300 based on these detection results.

[0076] In this case, depending on the number and arrangement of the distance sensors 500, the control unit 400 can control the relative movement mechanism 300 based only on the detection results of the distance sensors 500, regardless of the rotation angle θ of the turntable 311. The type of the distance sensor 500 is not particularly limited, and may be, for example, an optical type as shown in Fig. 6B, or a type that detects the distance by mechanically contacting the packaging box 10.

[0077] 6C shows an example in which the printing apparatus 1 is provided with a position and orientation detection device 600 that detects the position and orientation of the packaging box 10 on the turntable 311. In this example, the position and orientation detection device 600 captures an image of the packaging box 10 on the turntable 311 from above using an imaging device, and generates position and orientation information of the packaging box 10 by performing image processing on the captured image. Then, the control unit 400 corrects the control of the relative movement mechanism 300 based on the position and orientation information acquired from the position and orientation detection device 600.

[0078] In this way, by providing the position and orientation detection device 600, it is possible to improve print quality while simplifying or eliminating the positioning of the packaging box 10. The position and orientation detection device 600 may be of another type, for example, configured with multiple distance sensors.

[0079] 7A and 7B show an example in which the edge of the surface to be printed first is set as the print start position P0. The example shown in Fig. 7A shows a case in which the linear movement mechanism 330 is positioned so that a linear path R that is substantially perpendicular to the main rotation center C1 in a substantially horizontal plane intersects obliquely with the initial attitude of the first long side surface 11, which is the surface to be printed first. This makes it possible to prevent printing on the surface to be printed first from being divided into two passes, which can further improve print quality depending on the print range and print content.

[0080] 7B shows an example in which the linear movement mechanism 330 is arranged so that the linear path R is offset from the main rotation center C1. For example, if an increase in the movement distance Dm and a change in the printing speed Vp do not pose a problem due to the size of the packaging box 10, such an arrangement may be adopted.

[0081] Additionally, although not shown, the printing device 1 may be configured so that the relative movement mechanism 300 includes an additional linear movement mechanism that moves the print head 200 linearly back and forth in a substantially vertical direction (a direction substantially parallel to the main rotation center C1). This makes it possible, for example, to make the printing direction oblique to the horizontal direction or to change the printing position on each of the side surfaces 11-14 in the vertical direction, thereby increasing the variety of printing.

[0082] The printing device 1 may also include multiple print heads 200. In this case, for example, by arranging multiple print heads 200 on the auxiliary rotation mechanism 320 in a direction substantially parallel to the main rotation center C1, it is possible to expand the printing range in that direction. Furthermore, by arranging multiple print heads 200 around the main rotation center C1 together with their respective dedicated auxiliary rotation mechanisms 320 and linear movement mechanisms 330, it is possible to shorten the time required to print one packaging box. Furthermore, the print heads 200 are not limited to inkjet type, and may be of other types.

[0083] Furthermore, the direction of the main rotation center C1 is not limited to the approximately vertical direction and may be other directions. Furthermore, the main rotation mechanism 310 may rotate the packaging box 10 by gripping the packaging box 10 from above or the side, for example. Furthermore, the configuration of the relative movement mechanism 300 is not particularly limited as long as it rotates the packaging box 10 around the main rotation center C1. For example, the linear movement mechanism 330 may move the main rotation mechanism 310 back and forth linearly, or may move the main rotation mechanism 310 back and forth linearly together with the print head 200 and the auxiliary rotation mechanism 320. Furthermore, the printing device 1 may print on a substrate other than the packaging box 10, and the shape of the substrate is not limited to a rectangular parallelepiped.

[0084] The above describes an embodiment of the present invention, but the printing device and printing method of the present invention are not limited to the above-described embodiment, and various modifications can be made within the scope that does not deviate from the gist of the present invention.

[0085] Furthermore, the actions and effects shown in the above-described embodiments are merely a list of the most preferable actions and effects resulting from the present invention, and the actions and effects of the present invention are not limited to these. [Explanation of symbols]

[0086] 1 Printing device 10 Packaging box (printed material) 200 print heads 300 Relative movement mechanism 310 Main rotation mechanism 320 Auxiliary Rotation Mechanism 330 Linear movement mechanism 400 control section C1 Main rotation center C2 Auxiliary rotation center θ Rotation angle

Claims

1. a print head that ejects printing material; a relative movement mechanism that moves the print head relative to a three-dimensional printing substrate in a printing direction, The printing device is characterized in that the relative movement mechanism has a main rotation mechanism that rotates the printing material around a main rotation center.

2. 2. The printing device according to claim 1, a rotation mechanism for rotating the print head about an auxiliary rotation center parallel to the main rotation center;

3. 3. The printing device according to claim 2, The printing apparatus is characterized in that the relative movement mechanism has a linear movement mechanism that moves the print head relatively toward and away from the main rotation center.

4. 4. The printing device according to claim 1, A printing device comprising: a control unit that controls the relative movement mechanism so as to change the rotation speed of the printing substrate based on the rotation angle of the printing substrate caused by the main rotation mechanism.

5. 4. The printing device according to claim 1, A printing device comprising: a control unit that controls the print head so as to change the ejection timing of the printing material based on the rotation angle of the printing substrate caused by the main rotation mechanism.

6. A printing method in which a print head that ejects printing material is moved relative to a three-dimensional object to be printed in a printing direction, characterized in that the object to be printed is rotated around a main rotation center.

Images