Printing apparatus

Abstract

To provide a printing device configured so that a head gap can be suppressed from varying.SOLUTION: A printing device is provided with: a conveying unit 2, installed on a conveyance surface, which conveys a three-dimensional printing medium P having a side surface erected in a direction perpendicular to the conveyance surface; a head unit 10 that discharges liquid droplets to the side surface of the printing medium P conveyed by the conveying unit 2; and an adsorbing and supporting part 5 that adsorbs the printing medium P conveyed by the conveying unit 2 to the head unit 10 side and conveys the printing medium while supporting the printing medium P so that a distance between the printing medium and the head unit 10 is kept constant.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a printing device that prints on a three-dimensional printing medium. [Background technology]

[0002] 2. Description of the Related Art Conventionally, inkjet printing devices have been proposed that perform printing by ejecting ink onto a print medium.

[0003] Inkjet printing devices that eject ink from above in a vertical direction onto a printing medium that is positioned so that the printing surface is horizontal, as well as inkjet printing devices that print by ejecting ink from a direction perpendicular to the printing surface onto a printing medium that is positioned so that the printing surface is not horizontal, have been proposed.

[0004] For example, a device has been proposed in which cardboard boxes are transported horizontally by a belt conveyor and printing is performed on the sides of the transported cardboard boxes by an inkjet head. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-217788 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when printing on the side of a cardboard box as described above, there is a problem in that it is difficult to stabilize the distance between the printing surface of the cardboard box and the inkjet head, the so-called head gap, if the bottom surface of the cardboard box is uneven or depending on the position where it is placed on the belt conveyor.

[0007] Patent Document 1 proposes a method for stably placing a cardboard box on a belt conveyor by lifting one side of the cardboard box.

[0008] However, although the method described in Patent Document 1 can suppress wobbling of the cardboard box, the head gap may fluctuate depending on the position where the cardboard box is placed on the belt conveyor.

[0009] As described above, when the head gap fluctuates, the ink landing position on the printing surface shifts, causing line misalignment and color unevenness, thereby degrading the quality of the printed image.

[0010] SUMMARY OF THE INVENTION An object of the present invention is to provide a printing apparatus that can suppress fluctuations in the head gap. [Means for solving the problem]

[0011] The printing device of the present invention comprises a transport unit that is installed on a transport surface and transports a three-dimensional printing medium having sides that stand perpendicular to the transport surface, a head unit that ejects droplets onto the sides of the printing medium transported by the transport unit, and an adsorption support unit that adsorbs the printing medium transported by the transport unit to the head unit side and transports it while supporting it so that the distance between the printing medium and the head unit is constant. [Effects of the Invention]

[0012] According to the printing device of the present invention, the three-dimensional printing medium transported by the transport unit is adsorbed to the head unit side, and is equipped with an adsorption support unit that supports and transports the printing medium while maintaining a constant distance between the printing medium and the head unit, thereby suppressing fluctuations in the head gap. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an external perspective view showing a basic configuration of an inkjet printing apparatus using an embodiment of the printing apparatus of the present invention; [Figure 2] Diagram showing the detailed configuration of the line head [Figure 3] FIG. 10 shows the configuration of the suction support unit [Figure 4]FIG. 1 is a block diagram showing the configuration of a control system of an inkjet printing apparatus using an embodiment of the printing apparatus of the present invention. [Figure 5] A diagram showing the configuration of the suction support unit using a roller conveyor. [Figure 6] FIG. 10 shows the configuration of a suction support unit using a skewed roller conveyor. [Figure 7] FIG. 1 shows the configuration of an auxiliary suction unit. [Figure 8] FIG. 10 is a diagram showing the configuration of an adsorption support unit having a charging unit; [Figure 9] 10A and 10B are diagrams showing the configuration of another embodiment of the suction support unit; DETAILED DESCRIPTION OF THE INVENTION

[0014] An inkjet printing apparatus using one embodiment of the printing apparatus of the present invention will be described in detail below with reference to the drawings. The inkjet printing apparatus of this embodiment is characterized by an adsorption support unit for a print medium, but first, the basic configuration of the inkjet printing apparatus of this embodiment excluding the adsorption support unit will be described. FIG. 1 is an external perspective view showing the basic configuration of the inkjet printing apparatus 1. In the description of the embodiment below, the up / down, left / right, front / rear directions indicated by arrows in FIG. 1 are the up / down, left / right, front / rear directions of the inkjet printing apparatus 1. Furthermore, the up / down direction of the inkjet printing apparatus 1 is the vertical direction.

[0015] As shown in FIG. 1, the inkjet printing device 1 includes a head unit 10 and a transport unit 2.

[0016] The transport unit 2 transports the print medium P in the direction of the arrow shown in Fig. 1. The print medium P may be, for example, a three-dimensional print medium (such as a box such as a cardboard box) with a printing surface Ps that stands upright in the vertical direction, as shown in Fig. 1. However, the print medium P is not limited to a box, and may be any object with a printing surface that stands upright in the vertical direction, such as a cylindrical can. In this embodiment, the transport unit 2 corresponds to the transport section of the present invention.

[0017] The transport unit 2 includes a support table 3 and a transport belt unit 4. The support table 3 is a table that supports the transport belt unit 4.

[0018] The conveyor belt unit 4 includes two platen rollers and a conveyor belt that extend in a direction perpendicular to the conveyance direction of the printing medium P. The two platen rollers are arranged parallel to and spaced apart in the conveyance direction of the printing medium P. A circular conveyor belt is stretched between the two parallel platen rollers. The platen rollers rotate under the control of the control unit 60, which will be described later, and the conveyor belt moves, thereby conveying the printing medium P.

[0019] Furthermore, an adsorption support section 5 is provided on the head unit 10 side of the conveyor belt section 4, but is not shown in Fig. 1. The adsorption support section 5 will be described in detail later.

[0020] The head unit 10 performs printing by ejecting ink onto the printing surface Ps of the print medium P transported by the transport unit 2.

[0021] 1, the head unit 10 has four line heads 11, 12, 13, and 14. The four line heads 11 to 14 are provided to extend in the vertical direction and are arranged parallel to the transport direction of the printing medium P. In this embodiment, each of the line heads 11 to 14 corresponds to a head portion of the present invention.

[0022] The four line heads 11 to 14 eject ink of C (cyan), M (magenta), Y (yellow), and K (black), respectively.

[0023] 2 is a diagram showing the detailed configuration of the line heads 11 to 14. Here, the configuration of the line head 11 out of the four line heads 11 to 14 will be described, but the remaining line heads 12 to 14 have the same configuration.

[0024] The line head 11 includes six inkjet heads 11a, 11b, 11c, 11d, 11e, and 11f.

[0025] Each of the inkjet heads 11a to 11f has a plurality of nozzles that eject ink, and the nozzles are arranged in a vertical direction. Note that the nozzle arrangement direction refers to the direction in which the nozzle row is longest, for example, when the nozzles are arranged two-dimensionally.

[0026] The line head 11 also has a first head row consisting of three inkjet heads 11a, 11c, and 11e, and a second head row consisting of three inkjet heads 11b, 11d, and 11f. The first head row and the second head row are arranged adjacent to each other at different positions in the transport direction of the printing medium P.

[0027] The three inkjet heads 11a, 11c, and 11e of the first head row are arranged at a predetermined interval in the vertical direction, and the three inkjet heads 11b, 11d, and 11f of the second head row are arranged at a predetermined interval in the vertical direction.

[0028] As shown in FIG. 2, the inkjet heads 11a, 11c, and 11e of the first head row and the inkjet heads 11b, 11d, and 11f of the second head row are arranged in a staggered manner so as to be at different positions in the vertical direction.

[0029] For example, when printing a straight line extending in the vertical direction using the line head 11, the straight line is printed by ejecting ink from the first head row and the second head row at different timings.

[0030] Next, a description will be given of the suction support section 5. Fig. 3A is a diagram of the suction support section 5 as seen from above, and Fig. 3B is a diagram of the suction support section 5 as seen from the right side.

[0031] The suction support section 5 suctions the printing medium P transported by the transport unit 2 to the head unit 10 side and supports the printing medium P so that the distance between the printing medium P and the head unit 10 is constant. Specifically, the suction support section 5 includes belt transport rollers 50 and 51, suction belts 52 and 53, and suction mechanisms 54 and 55.

[0032] The belt conveying roller 50 and the belt conveying roller 51 are provided on the upstream side and the downstream side of the head unit 10 in the conveying direction.

[0033] 3B, the belt transport roller 50 has a roller shaft 50a that is set upright in the vertical direction and two transport rollers 50b and 50c. The transport rollers 50b and 50c are provided above and below the roller shaft 50a, and are arranged with a gap between them that is wider than at least the vertical width of the ink ejection range from the head unit 10. The transport rollers 50b and 50c are also arranged with a gap narrower than the expected vertical width of the printing medium P.

[0034] The belt conveying roller 51 has a roller shaft 51a that is set upright in the vertical direction and two conveying rollers 51b and 51c. The conveying rollers 51b and 51c are provided above and below the roller shaft 51a, and are arranged at the same interval as the conveying rollers 50b and 50c of the belt conveying roller 50.

[0035] An adsorption belt 52 is stretched between the upper conveyance roller 50b of the belt conveyance roller 50 and the upper conveyance roller 51b of the belt conveyance roller 51. The adsorption belt 52 is a circular belt with a large number of suction holes 52a formed therein. As shown in FIG. 3A, a suction mechanism 54 is provided inside the adsorption belt 52, and the suction action of the suction mechanism 54 generates negative pressure in the suction holes 52a of the adsorption belt 52, thereby adsorbing the printing medium P. The suction mechanism 54 is composed of, for example, a suction fan.

[0036] Furthermore, an adsorption belt 53 is stretched between the lower conveyance roller 50c of the belt conveyance roller 50 and the lower conveyance roller 51c of the belt conveyance roller 51. The adsorption belt 53 is a circular belt with a large number of suction holes 53a formed therein. As shown in FIG. 3A, a suction mechanism 55 is provided inside the adsorption belt 53, and the suction action of the suction mechanism 55 generates negative pressure in the suction holes 53a, thereby adsorbing the printing medium P. The suction mechanism 55 is composed of, for example, a suction fan.

[0037] As shown in FIG. 3B, the head unit 10 is disposed between the roller shaft 50a of the belt conveying roller 50 and the roller shaft 51a of the belt conveying roller 51 in the conveying direction, and between the suction belt 52 and the suction belt 53 in the vertical direction.

[0038] 3B, a pulley 51d and a belt 51e are provided at the lower end of the roller shaft 51a of the belt conveying roller 51. When a drive motor 51f connected to the belt 51e rotates, the belt conveying roller 51 rotates via the pulley 51d, and the belt conveying roller 50 rotates via the suction belts 52 and 53. When the belt conveying rollers 50 and 51 rotate, the suction belts 52 and 53 rotate and move between the belt conveying roller 50 and the belt conveying roller 51.

[0039] 3A, a guide member 56 is provided at a position facing the belt transport roller 50 in a direction perpendicular to the transport direction. The guide member 56 is a member that guides the printing medium P transported by the transport unit 2 toward the suction support section 5. The guide member 56 is formed, for example, from a flexible and elastic resin or metal, and guides the printing medium P toward the suction support section 5 without damaging it. The printing medium P guided by the guide member 56 is adsorbed to the suction support section 5, and then transported downstream by the suction support section 5 and the transport unit 2.

[0040] As shown in FIG. 3A, a peeling mechanism 57 is provided downstream of the suction support unit 5. The peeling mechanism 57 is a mechanism that peels the printing medium P, which has been adsorbed to the suction belts 52, 53, from the suction belts 52, 53. The peeling mechanism 57 has a guide member that contacts the printed surface Ps of the printing medium P that has been printed and guides the printing medium P in a direction away from the suction belts 52, 53 as the printing medium P is transported along the peeling mechanism 57. Note that the peeling mechanism 57 is not shown in FIG. 3B. In this way, by providing the peeling mechanism 57, the transportation of the printing medium P can be made smoother.

[0041] 4 is a block diagram showing the overall configuration of the inkjet printing apparatus of this embodiment. The control unit 60 includes a CPU (Central Processing Unit) and storage media such as semiconductor memory and a hard disk, and controls the entire inkjet printing apparatus 1. The control unit 60 executes a control program stored in advance in a storage medium such as semiconductor memory or a hard disk, and operates electrical circuits to control the operation of each part of the inkjet printing apparatus.

[0042] Next, the conveyance process and printing process of the print medium P performed by the inkjet printing apparatus 1 of this embodiment will be described.

[0043] First, the print medium P to be printed is placed upstream of the conveyor belt unit 4. Then, the print medium P placed on the conveyor belt unit 4 is conveyed by the conveyor belt unit 4 and is guided toward the suction support unit 5 while in contact with the guide member 56.

[0044] When the printing surface Ps (side surface) of the printing medium P comes into contact with the suction support unit 5, the suction mechanisms 54, 55 of the suction support unit 5 perform suction to cause the printing surface Ps of the printing medium P to be adsorbed to the suction belts 52, 53. As the printing medium P is adsorbed to the suction belts 52, 53, it is supported so that the distance D (head gap) between the printing medium P and the head unit 10 is constant, as shown in FIG. 3A.

[0045] Then, with the printing medium P being adsorbed and supported by the suction belts 52 and 53, the conveyance of the printing medium P by the conveyor belt unit 4 and the suction belts 52 and 53 continues, and the printing medium P is conveyed to the head unit 10. The conveyance speeds of the conveyor belt unit 4 and the suction belts 52 and 53 of the suction support unit 5 are set to the same speed.

[0046] Subsequently, as the printing medium P passes through the head unit 10, ink is ejected at predetermined timing from the line heads 11 to 14 of the head unit 10 toward the printing surface Ps of the printing medium P, and printing is performed on the printing surface Ps.

[0047] After the printing process by the head unit 10 is completed, the printing medium P that has been printed is transported downstream, and the printing surface Ps of the printing medium P abuts against the peeling mechanism 57, causing the printing medium P to detach from the suction belts 52, 53.

[0048] The inkjet printing device 1 of this embodiment is equipped with an adsorption support section 5 that adsorbs the three-dimensional print medium P transported by the transport unit 2 to the head unit 10 side and transports the print medium P while supporting it so that the distance D between the print medium P and the head unit is constant, thereby suppressing fluctuations in the head gap. Furthermore, because the print medium P is transported by adsorption support section 5, the effects of speed variations in the transport unit 2 can be suppressed.

[0049] In the inkjet printing device 1 of the above embodiment, the guide member 56 guides the print medium P toward the suction support unit 5 as described above, but at this time, it is preferable that there is little resistance to movement of the print medium P in a direction perpendicular to the transport direction. Therefore, as shown in Figure 5, a roller conveyor 6 may be used as the transport unit 2.

[0050] Furthermore, as shown in FIG. 6, the transport unit 2 may be a skewed roller conveyor 7 that transports the print medium P in the transport direction while guiding the print medium P toward the head unit 10 side.

[0051] By using a roller conveyor 6 or a skewed roller conveyor 7 as the transport unit 2, even a heavy printing medium P can be moved smoothly toward the head unit 10 and can be more reliably adsorbed to the adsorption support section 5.

[0052] Furthermore, in order to more reliably deliver and adsorb the printing medium P to the adsorption support section 5, an auxiliary adsorption section 8 that adsorbs the printing medium P transported by the transport unit 2 toward the head unit 10 may be provided upstream of the adsorption support section 5 in the transport direction. The auxiliary adsorption section 8 will be described in detail below. Fig. 7A is a view of the auxiliary adsorption section 8 from above, and Fig. 7B is a view of the auxiliary adsorption section 8 shown in Fig. 7A from the right side.

[0053] The auxiliary suction unit 8 includes belt conveying rollers 80 and 81, a suction belt 82, and a suction mechanism 83.

[0054] The belt conveying roller 80 and the belt conveying roller 81 are provided on the upstream side and the downstream side of the suction mechanism 83 in the conveying direction.

[0055] As shown in Fig. 7B, the belt conveying roller 80 has a roller shaft 80a that is set upright in the vertical direction and two conveying rollers 80b and 80c. The conveying rollers 80b and 80c are provided above and below the roller shaft 80a. As shown in Fig. 7B, the conveying rollers 80b and 80c are arranged at a distance narrower than the distance between the conveying rollers 50b and 50c of the suction support unit 5.

[0056] 7B, the belt conveying roller 81 has a roller shaft 81a that is set upright in the vertical direction and two conveying rollers 81b and 81c. The conveying rollers 81b and 81c are provided above and below the roller shaft 81a, and are arranged at the same interval as the conveying rollers 80b and 80c of the belt conveying roller 80.

[0057] An adsorption belt 82 is stretched between the conveyance rollers 80b and 80c of the belt conveyance roller 80 and the conveyance rollers 81b and 81c of the belt conveyance roller 81. The adsorption belt 82 is a circular belt with a large number of suction holes 82a formed therein. As shown in FIG. 7A, a suction mechanism 83 is provided inside the adsorption belt 82, and the suction action of the suction mechanism 83 generates negative pressure in the suction holes 82a, which adsorbs the printing medium P. The suction mechanism 83 is composed of, for example, a suction fan.

[0058] As shown in FIG. 7B, a pulley 81d is provided at the lower end of the roller shaft 81a of the belt conveying roller 81, and a pulley 50d is provided at the lower end of the roller shaft 50a of the belt conveying roller 50, and a circular belt 81e is stretched between the pulleys 81d and 50d.

[0059] The rotation of the drive motor 51f rotates the belt conveying roller 51, which rotates the belt conveying roller 50 via the suction belts 52 and 53, and the rotation of the belt conveying roller 50 rotates the belt conveying roller 81. The rotation of the belt conveying roller 81 causes the suction belt 82 to rotate and move between the belt conveying roller 80 and the belt conveying roller 81.

[0060] The print medium P placed on the transport unit 2 is transported by the transport unit 2 and is guided toward the auxiliary suction portion 8 while in contact with the guide member 56.

[0061] When the printing surface Ps (side surface) of the printing medium P comes into contact with the auxiliary suction section 8, the suction mechanism 83 of the auxiliary suction section 8 performs a suction operation, causing the printing surface Ps of the printing medium P to be adsorbed to the suction belt 82.

[0062] Then, with the printing medium P adsorbed to the suction belt 82, the transport of the printing medium P by the transport unit 2 and the suction belt 82 continues, and when a downstream portion of the printing medium P reaches the suction support section 5, suction by the suction support section 5 also begins. The transport speeds of the auxiliary suction section 8 and the suction support section 5 are set to the same speed. The suction surface of the suction belt 82 and the suction surfaces of the suction belts 52 and 53 are set to be on the same vertical plane in a direction perpendicular to the transport direction.

[0063] Then, after the printing medium P has been adsorbed and transported by both the auxiliary adsorption unit 8 and the adsorption support unit 5 for a predetermined time, the printing medium P is handed over from the auxiliary adsorption unit 8 to the adsorption support unit 5. The printing medium P is then transported by the adsorption support unit 5, and thereafter the process is the same as in the inkjet printing device 1 of the above embodiment.

[0064] By providing the auxiliary suction portion 8 as described above, the print medium P can be more reliably sucked onto the suction support portion 5 even when the print medium P is heavy and difficult to suck.

[0065] Furthermore, when the auxiliary suction section 8 is provided as described above, it is preferable that the suction force of the auxiliary suction section 8 be stronger than that of the suction support section 5. This allows the printing medium P to be more reliably attracted to the auxiliary suction section 8.

[0066] In the inkjet printing device 1 of the above embodiment, the suction mechanisms 54, 55 generate negative pressure in the suction holes 52a, 53a of the suction belts 52, 53 to adsorb the printing medium P, but the mechanism for adsorbing the printing medium P is not limited to this, and the printing medium P may also be adsorbed using static electricity, for example.

[0067] 8 is a diagram showing the schematic configuration of an inkjet printing device 9 that adsorbs a print medium P using static electricity. The inkjet printing device 9 includes adsorption belts 70 and 71, similar to the inkjet printing device 1 of the above embodiment, but the adsorption belts 70 and 71 do not have suction holes. Instead, a charging unit 73 is provided so as to contact the adsorption belts 70 and 71.

[0068] The charging unit 73 generates static electricity and uses the generated static electricity to charge the suction belts 70 and 71. As the charging unit 73, a known charging device can be used.

[0069] The inkjet printing device 9 has other configurations similar to those of the above-described inkjet printing device 1. When the adsorption belts 70 and 71 are charged by the charging unit 73 to adsorb the printing medium P, the peeling mechanism 57 may be a charge removal mechanism such as an ionizer.

[0070] Furthermore, in the inkjet printing device 1 of the above embodiment, the suction belts 52, 53 are arranged above and below the head unit 10 in the suction support section 5, but this is not limited to this, and other arrangements are also possible as long as they ensure the ink ejection range from the head unit 10 is secured.

[0071] For example, when printing all the way to the bottom edge of the print medium P, the lower suction belt 53 may not be provided, and the print medium P may be adsorbed and transported by the upper suction belt 52. Also, as shown in Fig. 9, suction belts 58 and 59 may be provided in front of and behind the head unit 10.

[0072] The adsorption belt 58 has a plurality of suction holes 58a formed therein, and is moved by the rotation of conveyor rollers 58b and 58c connected to the roller shaft 50a. A suction mechanism (not shown) is provided inside the adsorption belt 58, and this suction mechanism generates negative pressure in the suction holes 58a.

[0073] The suction belt 59 has a plurality of suction holes 59a formed therein, and is moved by the rotation of conveyance rollers 59b and 59c connected to the roller shaft 51a. A suction mechanism (not shown) is provided inside the suction belt 59, and this suction mechanism generates negative pressure in the suction holes 59a. The rest of the configuration is the same as that of the suction support unit 5 of the inkjet printing apparatus 1 of the above embodiment. The suction belts 58 and 59 may be charged by a charging unit rather than being provided with a suction mechanism.

[0074] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiments. For example, all of the components shown in the embodiments can be appropriately combined. Naturally, various modifications and applications are possible without departing from the spirit of the invention.

[0075] The present invention further discloses the following supplementary notes. (Addendum)

[0076] In the printing device of the present invention, a peeling mechanism for peeling the print medium from the suction support section can be provided downstream of the suction support section in the transport direction.

[0077] In the printing device of the present invention, an auxiliary suction section can be provided upstream of the suction support section in the transport direction to suck the print medium transported by the transport section toward the head section while transporting it.

[0078] In the printing device of the present invention, the auxiliary suction portion can have a stronger suction force than the suction support portion.

[0079] In the printing device of the present invention, the transport unit can guide the print medium toward the head unit while transporting the print medium in the transport direction. [Explanation of symbols]

[0080] 1. Inkjet printing device 2 Transport unit 3 Support stand 4 Conveyor belt section 5 Suction support part 6 Roller conveyor 7 Skewed Roller Conveyor 8 Auxiliary suction part 9. Inkjet printing device 10 Head Unit 10~14 line head 11a~11f inkjet head 50,51 Belt conveying roller 50a roller shaft 50b, 50c Conveyor rollers 50d pulley 51 Belt conveyor roller 51a Roller shaft 51b, 51c Conveyor rollers 51d pulley 51e Belt 51f drive motor 52,53 Suction belt 52a,53a Suction hole 54,55 Suction mechanism 56 Guide member 57 Peeling mechanism 58,59 Suction belt 58a,59a Suction hole 58b, 58c Conveyor rollers 59b, 59c Conveyor roller 60 Control Unit 70,71 Suction belt 73 Charging section 80,81 Belt conveying roller 80a roller shaft 80b, 80c Conveyor rollers 81 Belt conveyor roller 81a Roller shaft 81b, 81c Conveyor rollers 81d Pulley 81e Belt 82 Suction Belt 82a Suction Hole 83 Attraction agencies D Distance P Print media Ps Printed Surface

Claims

1. a conveying unit that is installed on a conveying surface and conveys a three-dimensional print medium having a side surface that stands upright in a direction perpendicular to the conveying surface; a head unit that ejects droplets onto a side surface of the print medium transported by the transport unit; a suction support unit that suctions the print medium conveyed by the conveyance unit to the head unit side and conveys the print medium while supporting it so that the distance between the print medium and the head unit is constant, A printing device in which a peeling mechanism that peels the print medium from the suction support section is provided downstream of the suction support section in the transport direction.

2. A conveying unit that is installed on a conveying surface and conveys a three-dimensional print medium having a side surface that is erected in a direction perpendicular to the conveying surface; a head unit that ejects droplets onto a side surface of the print medium transported by the transport unit; a suction support unit that suctions the print medium conveyed by the conveyance unit to the head unit side and conveys the print medium while supporting it so that the distance between the print medium and the head unit is constant, The printing device includes an auxiliary suction section located upstream of the suction support section in the transport direction, which suctions the print medium transported by the transport section toward the head section while transporting the print medium.

3. 3. The printing apparatus according to claim 2, wherein the auxiliary suction portion has a stronger suction force than the suction support portion.

4. 4. The printing device according to claim 1, wherein the transport unit transports the print medium in a transport direction while guiding the print medium toward the head unit.

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