Printing apparatus and maintenance method

Abstract

To provide a technique that can suction ink adhering to a lower surface of a head and suppress ink from being suctioned from inside of a nozzle of the head.SOLUTION: A printing device comprises heads 61 that discharge ink and a maintenance unit 70 that performs maintenance of the heads 61. Lower surfaces of the heads 61 have nozzle surfaces on which a plurality of nozzles is arranged and side surfaces arranged adjacently to the nozzle surfaces. The maintenance unit 70 has a cleaning block 72 that suctions ink from the lower surfaces of the heads 61. An upper surface of the cleaning block 72 has a first region opposing to the nozzle surfaces and a second region opposing to the side surfaces. Suction force of the first region is smaller than suction force of the second region. This can suppress ink from being suctioned from the insides of the nozzles of the heads 61.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to a head maintenance technique in a printing apparatus that performs printing on a long strip-shaped printing medium by an inkjet method.

Background Art

[0002] Conventionally, there is known a printing apparatus that prints an image on a printing medium by discharging ink onto the surface of the printing medium while conveying a long strip-shaped printing medium in the longitudinal direction. The printing apparatus has a head provided with a plurality of nozzles for discharging ink.

[0003] In this type of printing apparatus, in order to eliminate clogging of the nozzles, a "purge operation" may be performed in which ink is continuously discharged from a plurality of nozzles. When the purge operation is performed, foreign matter in the ink and aggregates of the ink itself are discharged from the nozzles. As a result, clogging of the nozzles is eliminated.

[0004] A conventional printing apparatus that performs a purge operation is described in, for example, Patent Document 1.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when the purge operation is performed, ink adheres to the lower surface of the head provided with a plurality of nozzles. Therefore, after the purge operation, it is necessary to remove the ink adhering to the lower surface of the head.

[0007] One method for removing ink adhering to the underside of the print head is to suck the ink out from the underside of the head. However, if a strong suction force is applied to the nozzle, ink may be drawn out from inside the nozzle. Normally, the ink interface inside the nozzle forms a meniscus. If ink is drawn out from inside the nozzle, this meniscus will break down, which can lead to poor ink ejection.

[0008] This invention has been made in view of these circumstances, and aims to provide a technology that can suck up ink adhering to the underside of the print head and suppress the suction of ink from inside the nozzle of the print head. [Means for solving the problem]

[0009] The first invention of this application is a printing apparatus for printing on a long strip-shaped printing medium using an inkjet method, comprising an ink ejection head and a maintenance unit for maintaining the head, wherein the lower surface of the head ejects ink multiple A nozzle surface with several nozzles, Along the predetermined stretching direction The maintenance unit has a cleaning block that sucks ink from the lower surface of the head, and the upper surface of the cleaning block has a first region facing the nozzle surface and a second region facing the side surface, and the suction force of the first region is less than the suction force of the second region. The cleaning block has a plurality of suction holes on its upper surface for drawing up ink, and the plurality of suction holes are arranged in a direction intersecting the extension direction. .

[0010] The second invention of this application is a printing apparatus of the first invention, wherein the cleaning block has a plurality of suction holes on its upper surface for sucking up ink, and the density of the suction holes in the first region is smaller than the density of the suction holes in the second region.

[0011] The third invention of this application is a printing apparatus according to the second invention, wherein the suction hole is not provided in the first region.

[0012] The fourth invention of this application is a printing apparatus according to any one of the first to third inventions, wherein the side surface protrudes downward from the nozzle surface.

[0013] The fifth invention of this application is a printing apparatus according to any one of the first to third inventions, further comprising a pressurizing mechanism that continuously ejects ink from a plurality of nozzles by supplying ink to the head while pressurizing the ink.

[0014] The sixth invention of this application is, Printing is performed on long, strip-shaped printing media using an inkjet method. A printing device, The device comprises an ink ejection head and a maintenance unit for performing maintenance on the head, wherein the lower surface of the head has a nozzle surface provided with a plurality of nozzles for ejecting ink and a side surface adjacent to the nozzle surface, the maintenance unit has a cleaning block for sucking ink from the lower surface of the head, the upper surface of the cleaning block has a first region facing the nozzle surface and a second region facing the side surface, and the suction force of the first region is less than the suction force of the second region. The cleaning block further has a plurality of liquid supply holes for supplying cleaning fluid to the lower surface of the head.

[0015] The seventh invention of this application is a printing apparatus according to the sixth invention, wherein the plurality of liquid supply holes are provided in both the first region and the second region.

[0016] The eighth invention of this application is a printing apparatus according to any one of the first to third inventions, wherein the nozzle surface and the side surface extend along the width direction of the printing medium, and further comprises a moving mechanism for moving the cleaning block relative to the head in the width direction.

[0017] The ninth invention of this application is a method for maintaining a print head in a printing apparatus that prints on a long strip-shaped printing medium using an inkjet method, comprising a cleaning step of sucking ink adhering to the lower surface of the head to a cleaning block, wherein the lower surface of the head ejects ink multiple A nozzle surface with several nozzles, Along the predetermined stretching direction The upper surface of the cleaning block has a side surface adjacent to the nozzle surface, and the upper surface of the cleaning block has a first region facing the nozzle surface and a second region facing the side surface, and the suction force of the first region is less than the suction force of the second region. The cleaning block has a plurality of suction holes on its upper surface for drawing up ink, and the plurality of suction holes are arranged in a direction intersecting the extension direction. .

[0018] The tenth invention of the present application is the maintenance method of the ninth invention, which has a purge process of continuously discharging ink from the plurality of nozzles by supplying ink to the head while pressurizing the ink, and performs the cleaning process after the purge process.

[0019] The eleventh invention of the present application is In a printing apparatus that performs inkjet printing on a long, strip-shaped printing medium a maintenance method, The device has a cleaning step of sucking ink adhering to the lower surface of the head into a cleaning block, the lower surface of the head having a nozzle surface provided with a plurality of nozzles for ejecting ink and a side surface adjacent to the nozzle surface, the upper surface of the cleaning block having a first region facing the nozzle surface and a second region facing the side surface, the suction force of the first region being less than the suction force of the second region. In the cleaning process, the cleaning block sucks ink while supplying cleaning liquid to the lower surface of the head.

[0020] The twelfth invention of the present application is the maintenance method of the ninth invention or the tenth invention, wherein the nozzle surface and the side surface extend along the width direction of the printing medium, and in the cleaning process, the cleaning block sucks ink while relatively moving in the width direction with respect to the head.

Advantages of the Invention

[0021] [[ID=*18]] According to the first to eighth inventions of the present application, the ink adhering to the lower surface of the head can be sucked by the cleaning block. Also, among the upper surface of the cleaning block, the suction force of the first region facing the nozzle surface is smaller than the suction force of the second region facing the side surface. Thereby, it is possible to suppress the ink from being sucked out from the inside of the nozzles of the head.

[0022] Particularly, according to the fifth invention of the present application, after eliminating the clogging of the nozzles by the purge operation, the ink adhering to the lower surface of the head can be sucked by the cleaning block.

[0023] Particularly, according to the sixth invention of the present application, cleaning liquid can be supplied to the lower surface of the head. Thereby, the lower surface of the head can be cleaned better.

[0024] Particularly, according to the seventh invention of the present application, both the nozzle surface and the side surface of the head can be cleaned with cleaning liquid.

[0025] In particular, according to the eighth invention of this application, ink adhering to the underside of the head can be sucked up by the cleaning block while the cleaning block is moved relative to the head in the width direction.

[0026] According to the 9th to 12th inventions of this application, ink adhering to the underside of the print head can be sucked up by the cleaning block. Furthermore, the suction force of the first region on the upper surface of the cleaning block facing the nozzle surface is smaller than the suction force of the second region facing the side surface. This prevents ink from being sucked out from inside the nozzle of the print head.

[0027] In particular, according to the tenth invention of this application, after clearing nozzle blockage in the purging process, ink adhering to the underside of the head can be removed in the cleaning process.

[0028] In particular, according to the 11th invention of this application, the underside of the head can be cleaned more effectively by supplying cleaning fluid to the underside of the head.

[0029] In particular, according to the 12th invention of this application, ink adhering to the underside of the head can be sucked up by the cleaning block while the cleaning block is moved relative to the head in the width direction. [Brief explanation of the drawing]

[0030] [Figure 1] This is a diagram showing the configuration of the printing system. [Figure 2] This is a diagram showing the configuration of a printing device. [Figure 3] This is a control block diagram of a printing system. [Figure 4] This is a view of the bottom of the head unit. [Figure 5] This is a diagram showing the head unit viewed in the width direction. [Figure 6] This diagram shows the configuration of the head unit, maintenance unit, and moving mechanism. [Figure 7] This is a perspective view of the cleaning block. [Figure 8] This is a top view of the cleaning block. [Figure 9] This diagram shows the configuration of the piping system connected to the cleaning block. [Figure 10] This is a flowchart showing the maintenance procedure for the head unit. [Figure 11] This is a diagram showing the cleaning process. [Modes for carrying out the invention]

[0031] Embodiments of the present invention will be described below with reference to the drawings.

[0032] <1. Printing System Configuration> Figure 1 shows the configuration of a printing system 100 equipped with a printing apparatus 1 according to one embodiment of the present invention. This printing system 100 is a system that prints and dries on a long, strip-shaped printing medium 9 while transporting the medium 9 in the longitudinal direction. The printing medium 9 is a flexible sheet with flexibility. For example, resin films such as OPP (oriented polypropylene) or PET (polyethylene terephthalate) for flexible packaging are used for the printing medium 9. However, the printing medium 9 may also be printing paper.

[0033] As shown in Figure 1, the printing system 100 comprises a printing device 1, a drying device 2, and a control unit 3. The printing device 1 and the drying device 2 are arranged adjacent to each other.

[0034] The printing device 1 is a device that prints on the surface of a printing medium 9 using an inkjet method. Figure 2 is a diagram showing the configuration of the printing device 1. As shown in Figures 1 and 2, the printing device 1 comprises a first transport mechanism 10, a color printing unit 20, and a white printing unit 30. The first transport mechanism 10, the color printing unit 20, and the white printing unit 30 are housed inside a box-shaped housing 101.

[0035] The first transport mechanism 10 is a mechanism that transports the printing medium 9 within the housing 101 of the printing device 1 in a transport direction along its longitudinal direction. The first transport mechanism 10 has a plurality of first transport rollers 11. The printing medium 9 is unwound from an unwinding roller 12 located outside the housing 101 and transported along a transport path formed by the plurality of first transport rollers 11. Each first transport roller 11 rotates about an axis extending parallel to the width direction of the printing medium 9, thereby guiding the printing medium 9 downstream along the transport path.

[0036] The color printing unit 20 is the part that dispenses water-based color ink onto the printing medium 9 transported by the first transport mechanism 10. As shown in Figure 1, the color printing unit 20 has a plurality of head units 21. The plurality of head units 21 are arranged at intervals along the transport direction of the printing medium 9. The printing medium 9 is transported below the plurality of head units 21 with its printing surface facing upward.

[0037] In the examples shown in Figures 1 and 2, the color printing unit 20 has six head units 21. However, the number of head units 21 in the color printing unit 20 may be 1 to 5, or 7 or more.

[0038] Multiple head units 21 eject color ink toward the upper surface of the printing medium 9. In this embodiment, color ink refers to ink of a color other than white. Color ink includes, for example, cyan, magenta, yellow, and black ink. Multiple head units 21 eject ink of different colors from each other. As a result, a multicolor image is formed on the upper surface of the printing medium 9.

[0039] The white printing unit 30 is the part that dispenses water-based white ink onto the printing medium 9 transported by the first transport mechanism 10. The white printing unit 30 is located downstream of the color printing unit 20 in the transport path of the printing medium 9. As shown in Figure 1, the white printing unit 30 has one head unit 31. The printing medium 9 is transported below the head unit 31 with the printing surface facing upwards.

[0040] The head unit 31 ejects white ink toward the upper surface of the printing medium 9. White ink refers to ink that is white in color. The white ink ejected from the head unit 31 forms a white image on the upper surface of the printing medium 9.

[0041] The drying apparatus 2 is a device that fixes the ink to the printing medium 9 by drying the ink. As shown in Figure 1, the drying apparatus 2 comprises a second transport mechanism 40 and a plurality of blowing units 50. The second transport mechanism 40 and the plurality of blowing units 50 are housed inside a box-shaped drying oven 102.

[0042] The second conveying mechanism 40 is a mechanism that conveys the printing medium 9 in a conveying direction along its longitudinal direction within the drying oven 102. The second conveying mechanism 40 has a plurality of second conveying rollers 41. After being conveyed by the first conveying mechanism 10, the printing medium 9 is transferred from the first conveying mechanism 10 to the second conveying mechanism 40. The printing medium 9 is then conveyed within the drying oven 102 along a conveying path formed by the plurality of second conveying rollers 41. Each second conveying roller 41 rotates about an axis extending parallel to the width direction of the printing medium 9, thereby guiding the printing medium 9 downstream along the conveying path. After conveying, the printing medium 9 is collected by a winding roller 42 located outside the drying oven 102.

[0043] Multiple blowing units 50 are arranged within the drying oven 102 along the transport path of the printing medium 9. Each of the multiple blowing units 50 has a pair of blowing chambers 51. The printing medium 9 passes between the pair of blowing chambers 51. Each blowing chamber 51 blows warm air onto the printing medium 9. The warm air is, for example, a gas heated to 60°C or higher. This dries the ink adhering to the surface of the printing medium 9. As a result, the ink is fixed to the surface of the printing medium 9.

[0044] The control unit 3 is a unit for controlling the operation of each part of the printing system 100. Figure 3 is a control block diagram of the printing system 100. As shown in Figure 3, the control unit 3 is composed of a computer having a processor 301 such as a CPU, memory 302 such as RAM, and a storage unit 303 such as a hard disk drive. The storage unit 303 stores a computer program P for executing printing, drying, and maintenance of the head units 21 and 31.

[0045] As shown in Figure 3, the control unit 3 is electrically connected to the first transport mechanism 10, the multiple head units 21 of the color printing unit 20, the head unit 31 of the white printing unit 30, the second transport mechanism 40, and the multiple blower units 50. The control unit 3 is also electrically connected to the ink supply unit 66, pressurizing mechanism 67, liquid supply pump 753, liquid supply valve 754, negative pressure generation unit 764, suction valve 765, first lifting mechanism 77, wiping unit 73, second lifting mechanism 78, and moving mechanism 80, which will be described later.

[0046] The control unit 3 controls the operation of each of the above-mentioned parts according to the computer program P stored in the memory unit 303. This allows the printing process, drying process, and maintenance process of the head units 21 and 31 in the printing system 100 to proceed.

[0047] <2. Head Unit Configuration> Next, the detailed configuration of the head units 21 and 31 described above will be explained. The multiple head units 21 of the color printing section 20 and the head unit 31 of the white printing section 30 have the same structure. For this reason, in the following, these head units 21 and 31 will be collectively referred to as "head unit 60," and one head unit 60 will be described.

[0048] In the following explanation, the direction along the transport path of the printing medium 9 will be referred to as the "transport direction," and the direction along the shorter side of the printing medium 9 will be referred to as the "width direction." Figure 4 is a bottom view of the head unit 60. Figure 5 is a view of the head unit 60 in the width direction.

[0049] As shown in Figure 4, the head unit 60 has multiple heads 61 that eject ink of the same color. The multiple heads 61 are arranged along the width direction. Each head 61 has a box-shaped casing 62. 4 In this example, the shape of the bottom surface of the casing 62 is approximately a parallelogram. However, the shape of the bottom surface of the casing 62 may also be rectangular.

[0050] As shown in Figures 4 and 5, the lower surface of the casing 62 of each head 61 has a nozzle surface 63 and a pair of side surfaces 64. The nozzle surface 63 and the pair of side surfaces 64 are aligned in the conveying direction. The nozzle surface 63 is located between the pair of side surfaces 64. Also, the nozzle surface 63 and the pair of side surfaces 64 extend substantially parallel to each other along the width direction.

[0051] The nozzle surface 63 is provided with a plurality of nozzles 65 capable of ejecting ink. The plurality of nozzles 65 are arranged in the width direction. In the example of Figure 4, the plurality of nozzles 65 are arranged in the width direction with their positions in the transport direction offset. By arranging the plurality of nozzles 65 two-dimensionally in this way, the positions of each nozzle 65 in the width direction can be brought closer to each other. However, the plurality of nozzles 65 may also be arranged in a single line along the width direction. Each nozzle 65 has an ink ejection port that opens downwards.

[0052] The nozzle 65 ejects ink droplets according to commands from the control unit 3. For example, the ink ejection method from the nozzle 65 is a so-called piezoelectric method, in which a voltage is applied to a piezoelectric element to deform it, thereby pressurizing and ejecting the ink inside the nozzle 65. However, the ink ejection method may also be a so-called thermal method, in which the ink inside the nozzle 65 is heated and expanded by energizing a heater.

[0053] The pair of side surfaces 64 are provided on both sides of the nozzle surface 63 in the conveying direction. Each side surface 64 is adjacent to the nozzle surface 63 in the conveying direction. As shown in Figure 5, each side surface 64 protrudes downward from the nozzle surface 63. In other words, the nozzle surface 63 is located above the pair of side surfaces 64. The nozzle surface 63 and the pair of side surfaces 64 are flat surfaces that are parallel to each other.

[0054] As shown in Figure 4, the printing device 1 has an ink supply unit 66. The ink supply unit 66 is connected to each head 61 of the head unit 60 via piping. When the printing device 1 is in operation, ink circulates between the ink supply unit 66 and the head unit 60. The ink supply unit 66 also has a pressurizing mechanism 67. The pressurizing mechanism 67 is a mechanism for performing a purge operation during maintenance of the head unit 60, which will be described later. The pressurizing mechanism 67 pressurizes the ink in the ink supply unit 66, thereby forcibly supplying ink to each head 61. This causes ink to be continuously ejected from multiple nozzles 65 of each head 61.

[0055] <3. Head Unit Maintenance> Next, we will explain the maintenance of the head unit 60 described above. The printing apparatus 1 has a maintenance unit 70 and a moving mechanism 80 for each head unit 60. Figure 6 is a diagram showing the configuration of the head unit 60, the maintenance unit 70, and the moving mechanism 80.

[0056] The head unit 60 is movable between a printing position facing the printing surface of the printing medium 9 and a maintenance position located laterally away from the transport path of the printing medium 9, by a head movement mechanism (not shown). The maintenance unit 70 performs maintenance such as cleaning on the head unit 60 when it is positioned at the maintenance position.

[0057] As shown in Figure 5, the maintenance unit 70 includes a cap 71, a cleaning block 72, a wiping unit 73, and a base frame 74. The cap 71, cleaning block 72, and wiping unit 73 are arranged in the width direction. The cap 71, cleaning block 72, and wiping unit 73 are supported by the base frame 74.

[0058] The cap 71 is the part that covers the underside of multiple heads 61. The cap 71 has a bottom and side walls and an open top. The cap 71 covers the underside of multiple heads 61 of one head unit 60 all at once. When purging is performed, the cap 71 receives the ink ejected from the multiple heads 61. A drain pipe 711 is connected to the bottom of the cap 71. The ink ejected from the multiple heads 61 is discharged from the cap 71 into the drain pipe 711.

[0059] The cleaning block 72 is a unit that cleans the underside of the print head 61 to which ink has adhered. The cleaning block 72 is located between the cap 71 and the wiping unit 73 in the width direction. The cleaning block 72 has an upper surface parallel to the underside of the print head 61. Figure 7 is a perspective view of the cleaning block 72. Figure 8 is a top view of the cleaning block 72. As shown in Figures 7 and 8, the cleaning block 72 has a plurality of liquid supply holes 721 and a plurality of suction holes 722 on its upper surface.

[0060] Multiple liquid supply holes 721 are holes for supplying cleaning fluid toward the underside of the head 61. The multiple liquid supply holes 721 are arranged on the upper surface of the cleaning block 72 along the transport direction. Multiple suction holes 722 are holes for sucking ink from the underside of the head 61. The multiple suction holes 722 are arranged on the upper surface of the cleaning block 72 at a position spaced in the width direction away from the multiple liquid supply holes 721, along the transport direction.

[0061] Figure 9 shows the configuration of the piping system connected to the cleaning block 72. As shown in Figure 9, the maintenance unit 70 has a cleaning fluid supply unit 75 and a suction unit 76.

[0062] The cleaning fluid supply unit 75 includes a cleaning fluid tank 751 and a fluid supply pipe 752. The cleaning fluid tank 751 stores cleaning fluid for cleaning the underside of the head 61. For example, a solvent from which the coloring components of the ink have been removed is used as the cleaning fluid. The upstream end of the fluid supply pipe 752 is connected to the cleaning fluid tank 751. The downstream end of the fluid supply pipe 752 is connected to a plurality of fluid supply holes 721 via the internal flow path of the cleaning block 72. A fluid supply pump 753 and a fluid supply valve 754 are provided along the path of the fluid supply pipe 752.

[0063] The liquid supply pump 753 operates according to a drive signal supplied from the control unit 3. The liquid supply valve 754 opens and closes according to a command from the control unit 3. When the liquid supply valve 754 is open and the liquid supply pump 753 is operated, cleaning fluid is supplied from the cleaning fluid tank 751 to the cleaning block 72 through the liquid supply pipe 752. The cleaning fluid is then discharged from multiple liquid supply holes 721 in the cleaning block 72.

[0064] The suction unit 76 includes a first suction pipe 761, a trap tank 762, a second suction pipe 763, and a negative pressure generating unit 764. The upstream end of the first suction pipe 761 is connected to a plurality of suction holes 722 via an internal flow path in the cleaning block 72. The downstream end of the first suction pipe 761 is connected to the trap tank 762. A suction valve 765 is provided along the path of the first suction pipe 761. The upstream end of the second suction pipe 763 is connected to the trap tank 762. The downstream end of the second suction pipe 763 is connected to the negative pressure generating unit 764.

[0065] An ejector, for example, is used in the negative pressure generating unit 764. However, a pump or the like may be used instead of an ejector. The negative pressure generating unit 764 operates according to commands from the control unit 3. The suction valve 765 opens and closes according to commands from the control unit 3. When the negative pressure generating unit 764 is operated with the suction valve 765 open, the gas inside the first suction pipe 761, the trap tank 762, and the second suction pipe 763 is drawn out to the negative pressure generating unit 764, and negative pressure is generated at the suction hole 722. As a result, the ink and cleaning fluid adhering to the underside of the head 61 are drawn into the suction hole 722. The drawn-out ink and cleaning fluid pass through the first suction pipe 761 and are stored in the trap tank 762.

[0066] In this embodiment, multiple liquid supply holes 721 open diagonally upward toward the suction holes 722. However, the direction of the opening of the liquid supply holes 721 may be vertically upward. Also, in this embodiment, multiple suction holes 722 open vertically upward. However, the direction of the opening of the suction holes 722 may be diagonally upward.

[0067] Furthermore, as shown in Figure 6, the maintenance unit 70 has a first lifting mechanism 77. The first lifting mechanism 77 raises and lowers the cleaning block 72 relative to the base frame 74 of the maintenance unit 70. Specifically, the first lifting mechanism 77 raises and lowers the cleaning block 72 between a first raised position in which the cleaning block 72 approaches the lower surface of the head 61 and a first lowered position lower than the first raised position. For example, an air cylinder can be used for the first lifting mechanism 77.

[0068] Figure 8 shows the position of the head 61 during cleaning by the cleaning block 72, indicated by dashed lines (two-dot dashed lines). As shown in Figure 8, the upper surface of the cleaning block 72 has a first region A1 and a pair of second regions A2. The first region A1 is the region that faces the nozzle surface 63 of the head 61 in the vertical direction when the head 61 is being cleaned by the cleaning block 72. The second region A2 is the region that faces the side surface 64 of the head 61 in the vertical direction when the head 61 is being cleaned by the cleaning block 72.

[0069] Multiple liquid supply holes 721 are provided in the first region A1 and a pair of second regions A2. That is, the multiple liquid supply holes 721 are provided at regular intervals from one second region A2 through the first region A1 to the other second region A2. As a result, the cleaning fluid discharged from the multiple liquid supply holes 721 is supplied to the nozzle surface 63 and the pair of side surfaces 64 of the head 61. This allows the nozzle surface 63 and the pair of side surfaces 64 to be cleaned with the cleaning fluid.

[0070] On the other hand, the multiple suction holes 722 are provided only in the pair of second regions A2, out of the first region A1 and the pair of second regions A2. That is, the first region A1 does not have suction holes 722. In this way, the suction force in the first region A1 can be made smaller than the suction force in the second region A2. Therefore, the suction force acting on the nozzle surface 63 of the head 61 can be made smaller than the suction force acting on the side surface 64.

[0071] Inside the multiple nozzles 65 provided on the nozzle surface 63, the ink interface forms a meniscus. If ink is drawn out from inside the nozzles 65, this meniscus will collapse, which can cause poor ink ejection. However, as described above, if the suction force acting on the nozzle surface 63 is made smaller than the suction force acting on the side surface 64, the drawing out of ink from inside the nozzles 65 can be suppressed. Therefore, poor ink ejection from the nozzles 65 can be suppressed.

[0072] The wiping unit 73 is a unit that wipes off ink and cleaning fluid adhering to the underside of the head 61. As shown in Figure 6, the wiping unit 73 has a supply roller 731, a wiping roller 732, and a recovery roller 733. The supply roller 731 and the recovery roller 733 are spaced apart in the width direction. The wiping unit 73 conveys a strip-shaped sheet 734 from the supply roller 731 through the wiping roller 732 to the recovery roller 733. The material used for the sheet 734 is, for example, cloth or paper.

[0073] The wiping unit 73 brings a sheet 734, supported by a wiping roller 732, into contact with a pair of side surfaces 64 of the head 61. With the sheet 734 sandwiched between the wiping roller 732 and the side surfaces 64, the sheet 734 is transported from the supply roller 731 to the recovery roller 733. This allows the sheet 734 to wipe away ink and cleaning fluid adhering to the side surfaces 64.

[0074] Furthermore, as shown in Figure 6, the maintenance unit 70 has a second lifting mechanism 78. The second lifting mechanism 78 raises and lowers the wiping unit 73 relative to the base frame 74 of the maintenance unit 70. Specifically, the second lifting mechanism 78 raises and lowers the cleaning block 72 between a second raised position in which the wiping roller 732 contacts the side surface 64 of the head 61, and a second lowered position lower than the second raised position. For example, an air cylinder can be used for the second lifting mechanism 78.

[0075] The moving mechanism 80 is a mechanism for moving the maintenance unit 70 in the width direction. The moving mechanism 80 moves the maintenance unit 70 in the width direction relative to the head unit 60 which is positioned at the maintenance location. For example, a linear motion mechanism using a ball screw is used for the moving mechanism 80. However, the moving mechanism 80 may be a linear motion mechanism composed of other mechanisms such as a linear motor.

[0076] Next, the operation of maintaining the head unit 60 using the maintenance unit 70 described above will be explained. Figure 10 is a flowchart showing the maintenance procedure for the head unit 60. The following procedure is carried out by the control unit 3 controlling the operation of each part of the printing device 1 according to the computer program P.

[0077] When performing maintenance on the head unit 60, first, the head unit 60 is moved from the printing position to the maintenance position. Then, the moving mechanism 80 positions the maintenance unit 70 in the position shown in Figure 6. In the position shown in Figure 6, the cap 71 of the maintenance unit 70 is positioned below the head unit 60. Then, the head unit 60 is lowered using a head lifting mechanism (not shown). As a result, the undersides of the multiple heads 61 are covered by the cap 71.

[0078] In this state, the printing apparatus 1 performs a purging operation (step S1, purging process). That is, the pressurizing mechanism 67 pressurizes the ink and supplies ink to each head 61 of the head unit 60. As a result, ink is continuously discharged from multiple nozzles 65 of each head 61. By performing the purging operation, foreign matter in the ink and aggregates of the ink itself are discharged from the nozzles 65. As a result, clogging of the nozzles 65 is resolved. However, when the purging operation is performed, ink adheres to the nozzle surface 63 and side surface 64 of each head 61.

[0079] After performing a purging operation for a predetermined time, the pressurizing mechanism 67 terminates the pressurization of the ink. This completes the purging operation. Then, the head lifting mechanism raises the head unit 60. As a result, the head unit 60 moves upward away from the cap 71, returning to the state shown in Figure 6.

[0080] Next, the printing apparatus 1 cleans the head 61 using the cleaning block 72 and the wiping unit 73 (step S2, cleaning process). Figure 11 shows the cleaning process.

[0081] In the cleaning process, the first lifting mechanism 77 moves the cleaning block 72 from the first lowered position to the first raised position. Then, it operates the cleaning fluid supply unit 75 and the suction unit 76 to start the discharge of cleaning fluid from the multiple fluid supply holes 721 and the suction of cleaning fluid into the multiple suction holes 722. At the same time, the second lifting mechanism 78 moves the wiping unit 73 from the second lowered position to the second raised position. Then, it starts the transport of the sheet 734 from the supply roller 731 to the recovery roller 733.

[0082] In this state, the moving mechanism 80 moves the maintenance unit 70 in the width direction. The direction of movement of the maintenance unit 70 is from the wiping unit 73 toward the cap 71. As a result, the cleaning block 72 moves in the width direction along the underside of the head 61 while discharging cleaning fluid from the multiple fluid supply holes 721 and drawing it into the multiple suction holes 722.

[0083] The cleaning fluid discharged from multiple fluid supply holes 721 is supplied to the nozzle surface 63 and a pair of side surfaces 64 of each head 61. The ink and cleaning fluid adhering to the nozzle surface 63 and the pair of side surfaces 64 are then sucked into multiple suction holes 722. This cleans the nozzle surface 63 and the pair of side surfaces 64. Furthermore, the movement of the cleaning block 72 cleans the nozzle surface 63 and the pair of side surfaces 64 of all heads 61.

[0084] Furthermore, when the maintenance unit 70 is moved, wiping is performed by the wiping unit 73 following the cleaning block 72. The wiping unit 73 transports the sheet 734, supported by the wiping roller 732, from the supply roller 731 to the recovery roller 733 while bringing the sheet 734 into contact with the pair of side surfaces 64 of the head 61. As a result, any ink and cleaning fluid remaining on the side surfaces 64 is wiped away by the sheet 734. In addition, the movement of the cleaning block 72 wipes away ink and cleaning fluid from the side surfaces 64 of all heads 61.

[0085] As described above, the maintenance unit 70 removes blockages from the nozzles 65 by purging, and then removes ink adhering to the underside of the print head 61 using the cleaning block 72 and the wiping unit 73. This helps to keep the print head 61 in good condition.

[0086] In particular, this maintenance unit 70 has suction holes 722 only in the second region A2 of the upper surface of the cleaning block 72 that faces the side surface 64 of the head 61. As a result, the suction force acting on the nozzle surface 63 of the head 61 is smaller than the suction force acting on the side surface 64. In addition, due to the suction force of the multiple suction holes 722, a gas flow along the nozzle surface 63 is formed below the nozzle surface 63, rather than a gas flow directed downwards. Therefore, it is possible to suppress ink from being sucked out from inside the nozzle 65. As a result, the ink meniscus inside the nozzle 65 can be maintained well, and ink ejection problems can be suppressed.

[0087] <4. Variation> Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment.

[0088] In the above embodiment, suction holes 722 were provided only in the pair of second regions A2 of the first region A1 and the pair of second regions A2 on the upper surface of the cleaning block 72, thereby making the suction force of the first region A1 smaller than that of the second region A2. However, suction holes 722 may also be provided in the first region A1. In that case, for example, the density of suction holes 722 in the first region A1 (number of suction holes 722 per unit area) should be made smaller than the density of suction holes 722 in the second region A2.

[0089] Furthermore, the opening diameter of the suction hole 722 provided in the first region A1 may be smaller than the opening diameter of the suction hole 722 provided in the second region A2. Also, by making the height of the first region A1 lower than the height of the second region A2, the suction force acting on the nozzle surface 63 of the head 61 may be made smaller than the suction force acting on the side surface 64. In addition, separate negative pressure generating units 764 may be connected to the suction hole 722 of the first region A1 and the suction hole 722 of the second region A2, so that the negative pressure generated in the suction hole 722 of the first region A1 is weaker than the negative pressure generated in the suction hole 722 of the second region A2.

[0090] Furthermore, in the above embodiment, the upper surface of the cleaning block 72 was provided with a plurality of liquid supply holes 721 and a plurality of suction holes 722. However, the cleaning block 72 does not necessarily have to have a plurality of liquid supply holes 721.

[0091] Furthermore, in the above embodiment, in step S2, the maintenance unit 70 was moved in the width direction relative to the stationary head unit 60. However, the head unit 60 may be moved in the width direction relative to the stationary maintenance unit 70. That is, in step S2, the maintenance unit 70 may be moved relative to the head unit 60 in the width direction.

[0092] Furthermore, in the above embodiment, the head 61 was cleaned by the cleaning block 72 and the wiping unit 73 after the purging operation. However, the head 61 may be cleaned by the cleaning block 72 and the wiping unit 73 without performing the purging operation. Also, the cleaning of the head 61 by the wiping unit 73 may be omitted.

[0093] Furthermore, in the above embodiment, the head unit 60 had multiple heads 61 arranged in a single row along the width direction. However, the head unit 60 may have multiple heads 61 arranged in two or more rows. Alternatively, the head unit 60 may have multiple heads 61 arranged in a staggered pattern.

[0094] Furthermore, in the above embodiment, the printing device 1 had a color printing unit 20 and a white printing unit 30. However, the printing device 1 may have only a color printing unit 20. Also, the number of head units 60 in the printing device 1 may differ from that in the above embodiment.

[0095] Furthermore, the detailed configuration of the printing apparatus may be modified as appropriate, without departing from the spirit of the present invention. In addition, the elements that appear in the above embodiments and modifications may be combined or partially deleted as appropriate, without causing any contradictions. [Explanation of Symbols]

[0096] 1 Printing device 2 Drying equipment 3. Control Unit 9 Print media 10. First conveying mechanism 20 Color Printing Department 21 Head Unit 30 White Printing Section 31 Head Unit 40. Second conveying mechanism 50 Blower Unit 60 Head Unit 61 heads 62 Casing 63 Nozzle surface 64 Side view 65 nozzles 66 Ink supply unit 67 Pressurization mechanism 70 Maintenance Units 71 Cap 72 Cleaning Blocks 73 Wiping Unit 74 Base Frame 75 Cleaning fluid supply unit 76 Suction part 77 First Lifting Mechanism 78 Second Lifting Mechanism 80 Moving mechanism 100 Printing Systems 721 Liquid supply hole 722 Suction hole A1 1st area A2 2nd area P Computer Program

Claims

1. A printing apparatus that performs inkjet printing on a long, strip-shaped printing medium, The print head that ejects ink, A maintenance unit for performing maintenance on the head, Equipped with, The lower surface of the head is A nozzle surface provided with multiple nozzles for ejecting ink, A side surface adjacent to the nozzle surface along a predetermined stretching direction, It has, The aforementioned maintenance unit is A cleaning block that sucks ink from the lower surface of the head. It has, The upper surface of the cleaning block is A first region facing the nozzle surface, A second region facing the aforementioned side surface, It has, The suction force in the first region is smaller than the suction force in the second region. The cleaning block has a plurality of suction holes on its upper surface for sucking up ink. A printing apparatus in which the plurality of suction holes are arranged in a direction intersecting the stretching direction.

2. A printing apparatus according to claim 1, The cleaning block has a plurality of suction holes on its upper surface for sucking up ink. A printing apparatus in which the density of suction holes in the first region is less than the density of suction holes in the second region.

3. A printing apparatus according to claim 2, A printing apparatus in which the suction holes are not provided in the first region.

4. A printing apparatus according to any one of claims 1 to 3, A printing apparatus in which the side surface protrudes downward from the nozzle surface.

5. A printing apparatus according to any one of claims 1 to 3, A pressurized mechanism that supplies ink to the head under pressure, thereby continuously ejecting ink from the multiple nozzles. A printing device that is further equipped with these features.

6. A printing apparatus for printing on a long strip-shaped printing medium using an inkjet method, The print head that ejects ink, A maintenance unit for performing maintenance on the head, Equipped with, The lower surface of the head is A nozzle surface provided with multiple nozzles for ejecting ink, The side surface adjacent to the nozzle surface, It has, The aforementioned maintenance unit is A cleaning block that sucks ink from the lower surface of the head. It has, The upper surface of the cleaning block is A first region facing the nozzle surface, A second region facing the aforementioned side surface, It has, The suction force in the first region is smaller than the suction force in the second region. The aforementioned cleaning block is, Multiple liquid supply holes for supplying cleaning fluid to the lower surface of the head. A printing apparatus further comprising the following.

7. A printing apparatus according to claim 6, A printing apparatus in which the plurality of liquid supply holes are provided in both the first region and the second region.

8. A printing apparatus according to any one of claims 1 to 3, The nozzle surface and the side surface extend along the width direction of the printing medium, A moving mechanism that moves the cleaning block relative to the head in the width direction. A printing device that is further equipped with these features.

9. A method for maintaining the print head in a printing apparatus that prints on a long, strip-shaped printing medium using an inkjet method, A cleaning process in which ink adhering to the lower surface of the print head is sucked into a cleaning block. It has, The lower surface of the head is A nozzle surface provided with multiple nozzles for ejecting ink, A side surface adjacent to the nozzle surface along a predetermined stretching direction, It has, The upper surface of the cleaning block is A first region facing the nozzle surface, A second region facing the aforementioned side surface, It has, The suction force in the first region is smaller than the suction force in the second region. The cleaning block has a plurality of suction holes on its upper surface for sucking up ink. A maintenance method wherein the plurality of suction holes are arranged in a direction intersecting the extension direction.

10. A maintenance method according to claim 9, A purging process in which ink is supplied to the head under pressure, thereby continuously ejecting ink from the multiple nozzles. It has, A maintenance method comprising performing the cleaning step after the purging step.

11. A method for maintaining a print head in a printing apparatus that performs inkjet printing on a long, strip-shaped printing medium, A cleaning process in which ink adhering to the lower surface of the print head is sucked into a cleaning block. It has, The lower surface of the head is A nozzle surface provided with multiple nozzles for ejecting ink, The side surface adjacent to the nozzle surface, It has, The upper surface of the cleaning block is A first region facing the nozzle surface, A second region facing the aforementioned side surface, It has, The suction force in the first region is smaller than the suction force in the second region. A maintenance method in which, in the cleaning step, the cleaning block supplies cleaning fluid to the lower surface of the head while simultaneously sucking up ink.

12. A maintenance method according to claim 9 or claim 10, The nozzle surface and the side surface extend along the width direction of the printing medium, A maintenance method in which, in the cleaning step, the cleaning block moves relative to the head in the width direction while sucking up ink.

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