Printing device and method

Abstract

To provide a printing device and a method capable of suppressing image degradation due to satellite.SOLUTION: A printing device includes: a conveyance part 3 that conveys a printing medium while sucking the printing medium; a head part 2 that discharges ink to the printing medium conveyed by the conveyance part 3; a cooling part 4 that supplies cooling air to the head part 2; and a control part 60 that controls the cooling part 4. The cooling part 4 is configured so as to be able to supply air to the conveyance part 3.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a printing apparatus and method for printing on a print medium while sucking and transporting the print medium. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been proposed an inkjet printing apparatus that performs printing by ejecting ink from an inkjet head onto a print medium made of paper, film, or the like while transporting the print medium.

[0003] A conveying device using a conveying belt has been proposed as a conveying device for conveying a print medium in an inkjet printing device. Specifically, a suction fan is provided on the back side of the conveying surface of the conveying belt that conveys the print medium, and negative pressure is generated in a number of belt holes formed in the conveying belt by rotation of the suction fan, thereby sucking the print medium onto the conveying belt and conveying it. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-98592 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an inkjet printing device equipped with a suction / adsorption type transport device as described above, various air currents act on the ink droplets ejected from the inkjet head. In particular, the suction air that sucks the printing medium is likely to act on the ink droplets, attracting minute satellite droplets that are generated together with the ink droplets, which causes degradation of the image at the leading and trailing ends of the printing medium.

[0006] When printing the first or final page of a multi-page print job, or when printing images at a slow transport speed, the suction air has a particularly large effect on the leading and trailing edges of the print medium, making it easy for satellites to adhere to the edges of the print medium.

[0007] Furthermore, in an inkjet printing device in which multiple inkjet heads are arranged in the transport direction of the print medium, the effects also vary depending on the position of the inkjet head in the transport direction; when printing is performed by ejecting ink from an inkjet head arranged upstream in the transport direction, the effect of satellites on the leading edge of the print medium is greater, while when printing is performed by ejecting ink from an inkjet head arranged downstream in the transport direction, the effect of satellites on the trailing edge of the print medium tends to be greater.

[0008] In addition, Patent Document 1 proposes a method of changing the ink ejection speed according to the amount of margin from the leading edge of the printing medium to the area of ​​the printed image. This is a method of improving the landing accuracy of ink droplets, and is effective as a drive control according to the amount of margin.

[0009] However, it is very difficult to control the ejection speed of satellites, which can cause stains on the edges of a print medium and image degradation.

[0010] SUMMARY OF THE PRESENT DISCLOSURE In view of the above circumstances, an object of the present invention is to provide a printing apparatus and method capable of suppressing image degradation caused by satellites. [Means for solving the problem]

[0011] The printing device of the present invention comprises a transport section that transports the printing medium while suctioning it, a head section that ejects ink onto the printing medium transported by the transport section, a cooling section that supplies cooling air to the head section, and a control section that controls the cooling section, and the cooling section is configured to be able to supply air to the transport section. Effect of the Invention

[0012] According to the printing device of the present invention, the cooling unit that supplies cooling air to the head unit is used to supply air to the transport unit, so that the supply of air can block the flow of suction air, thereby restricting the movement of the satellites and suppressing image deterioration. In addition, since the cooling unit of the head unit can be used for both, it is possible to avoid increases in cost and an increase in the size of the device. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an inkjet printing apparatus using a first embodiment of the printing apparatus of the present invention; [Diagram 2] FIG. 1 shows a schematic configuration of a head unit. [Diagram 3] FIG. 1 is a diagram showing a schematic configuration of a cooling unit according to a first embodiment; [Figure 4] FIG. 13 is a diagram showing an example of a wind direction changing mechanism. [Diagram 5] FIG. 13 shows another example of the wind direction changing mechanism [Figure 6] FIG. 1 is a block diagram showing a schematic configuration of a control system of an inkjet printing apparatus according to a first embodiment. [Figure 7] A flowchart for explaining a process for determining whether or not to perform satellite suppression control. [Figure 8] Diagram to explain the effect of satellites when the paper width is small [Figure 9] A diagram for explaining the effect of satellites on the leading edge of a print medium. [Figure 10] FIG. 1 is a diagram for explaining the effect of satellites on the trailing edge of a print medium. [Figure 11] FIG. 13 is a diagram showing a schematic configuration of a cooling unit according to a second embodiment; [Figure 12] Bottom view of the line head and head holder with satellite suppression air supply holes [Figure 13] FIG. 13 is a block diagram showing a schematic configuration of a control system of an inkjet printing apparatus according to a second embodiment. [Figure 14] FIG. 13 is a diagram for explaining an example of opening and closing control of a satellite suppression air supply hole formed in a head holder; [Figure 15] FIG. 13 is a diagram for explaining an example of opening / closing control of satellite suppression air supply holes according to a paper width; [Figure 16] FIG. 13 is a diagram for explaining the flow of suction air when satellite suppression air is not supplied and the flow of suction air when satellite suppression air is supplied; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An inkjet printing apparatus using a first 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 the configuration of the cooling unit, but first, its overall configuration will be described. FIG. 1 is a schematic configuration diagram of the inkjet printing apparatus 1 of this embodiment, but the cooling unit is not shown. The up, down, left, and right directions indicated by the arrows in FIG. 1 are the up, down, left, and right directions of the inkjet printing apparatus 1 of this embodiment. Also, the front side of the paper surface of FIG. 1 is the front direction, and the back side is the rear direction. Also, in this embodiment, the direction from left to right is the transport direction of the print medium, the left side is the upstream side in the transport direction, and the right side is the downstream side in the transport direction.

[0015] As shown in FIG. 1, the inkjet printing apparatus 1 of this embodiment includes a head unit 2 and a transport unit 3.

[0016] The head unit 2 prints an image on a print medium P (for example, printing paper) transported by the transport unit 3. The head unit 2 of this embodiment includes a plurality of line heads 11-14.

[0017] The line heads 11 to 14 eject ink onto the printing medium P to print a print image. In this embodiment, the line head 11 ejects black ink, the line head 12 ejects cyan ink, the line head 13 ejects magenta ink, and the line head 14 ejects yellow ink. The four line heads 11 to 14 extend in a direction (front-rear direction) perpendicular to the transport direction (left-right direction) of the printing medium P, and are arranged in parallel above the transport unit 3 along the transport direction of the printing medium P.

[0018] Each of the line heads 11 to 14 has a plurality of inkjet heads 15. In this embodiment, each of the line heads 11 to 14 has six inkjet heads 15.

[0019] The six inkjet heads 15 in each of the line heads 11 to 14 are arranged in a staggered manner in the front-rear direction, as shown in Fig. 2. That is, in each of the line heads 11 to 14, the six inkjet heads 15 arranged in the front-rear direction are arranged with their positions shifted alternately in the left-right direction.

[0020] Each inkjet head 15 has a plurality of nozzles (not shown) that open on a discharge surface 15a, which is the lower surface facing a transport surface 21b of a transport belt 21 described later, and discharges ink from the nozzles.

[0021] The transport unit 3 transports the print medium P fed from a paper feed unit (not shown) while holding it by suction. The transport unit 3 includes a transport belt 21, a drive roller 22, driven rollers 23-25, a platen 26, and a suction unit 27.

[0022] The transport belt 21 holds and transports the print medium P by suction. The transport belt 21 is a circular belt that is stretched around a drive roller 22 and driven rollers 23 to 25. The transport belt 21 has a large number of belt holes formed therein.

[0023] The conveyor belt 21 sucks and adsorbs the print medium P onto the conveyor surface 21b by negative pressure generated in the belt holes by driving a fan 38 of the suction unit 27 described below. The conveyor surface 21b is the surface of the conveyor belt 21 on which the print medium P is placed, and is the upper surface of the horizontal part of the conveyor belt 21 between the drive roller 22 and the driven roller 23. The conveyor belt 21 rotates (moves endlessly) in the clockwise direction in Fig. 1, thereby conveying the held print medium P in a conveying direction from the left (upstream side) to the right (downstream side).

[0024] The driving roller 22 rotates and moves the conveyor belt 21. The driving roller 22 is driven to rotate by a driving motor 35 (see FIG. 4). The driven rollers 23-25 ​​support the conveyor belt 21 together with the driving roller 22. The driven rollers 23-25 ​​rotate following the conveyor belt 21. The driven roller 23 is disposed to the left of the driving roller 22 at the same height as the driving roller 22. The driven rollers 24 and 25 are disposed below the driving roller 22 and the driven roller 23, spaced apart from each other in the left-right direction, at the same height.

[0025] The platen 26 is disposed below the conveyor belt 21 (on the side opposite to the conveyor surface 21b) between the drive roller 22 and the driven roller 23, and is a plate-shaped member that slidably supports the conveyor belt 21. The platen 26 has a number of suction holes. Air is sucked in by driving the fan 38, and negative pressure is generated in the suction holes. The suction holes of the platen 26 are disposed in the same locations as the belt holes of the conveyor belt 21.

[0026] The suction unit 27 sucks air through suction holes in the platen 26 and belt holes in the transport belt 21 to adsorb the print medium P to the transport belt 21. The suction unit 27 includes a chamber 37 and a fan .

[0027] The chamber 37 forms a negative pressure chamber for generating negative pressure in the belt holes of the conveyor belt 21. The chamber 37 is provided on the rear surface side of the platen 26 between the drive roller 22 and the driven roller 23.

[0028] The fan 38 exhausts air from the chamber 37. As a result, the fan 38 sucks air through the suction holes in the platen 26 and the belt holes in the transport belt 21, generating negative pressure in the belt holes and causing the print medium P to be attracted to the transport belt 21.

[0029] Next, the cooling section of the inkjet printing apparatus 1 of this embodiment will be described. Fig. 3 is a diagram showing a schematic configuration of the cooling section 4 of this embodiment. The cooling section 4 of this embodiment is configured to be able to supply air to the transport section 3 under the control of the control section 60, which will be described later.

[0030] Specifically, the cooling section 4 of the present embodiment includes an air supply section 40 and an air discharge section 50. The air supply section 40 includes a blowing fan section 41 and an air-blowing housing section 42. The blowing fan section 41 has a fan, and generates wind by driving the fan, and supplies the wind to the air-blowing housing section 42.

[0031] 3, the air-blowing housing section 42 is provided near the front end of each of the line heads 11 to 14 of the head section 2. The air-blowing housing section 42 has a housing into which the air supplied from the blowing fan section 41 flows, and a cooling air supply hole 43 and a satellite suppression air supply hole 44 are formed on the surface of the housing on the head section 2 side.

[0032] The cooling air supply holes 43 are holes that send out the air supplied from the blowing fan unit 41 as cooling air toward the head unit 2. The cooling air supply holes 43 are formed in the surface of the housing facing the front end of each of the line heads 11-14, and are formed so that cooling air is supplied to each of the line heads 11-14.

[0033] The satellite suppression air supply holes 44 are holes for sending out the air supplied from the blowing fan unit 41 to the air blower housing unit 42 as satellite suppression air toward the transport unit 3. A plurality of satellite suppression air supply holes 44 are formed on the surface of the housing below the cooling air supply holes 43.

[0034] The satellite suppression air supply holes 44 are formed at a position below the head holder 30 on which each inkjet head 15 of each line head 11 to 14 is installed and above the transport surface 21b of the transport section 3. The head holder 30 has installation holes in which each inkjet head 15 is installed as described above, and the ejection surface 15a of each inkjet head 15 is exposed from the installation holes.

[0035] Moreover, the satellite suppression airflow supply holes 44 are formed on both sides in the transport direction of each of the line heads 11 to 14. By forming the satellite suppression airflow supply holes 44 at the positions as described above, the satellite suppression airflow is supplied above the transport unit 3 to both sides in the transport direction of each of the line heads 11 to 14.

[0036] Air discharge section 50 includes suction fan section 51 and discharge housing section 52. Suction fan section 51 has a fan, and air inside discharge housing section 52 is sucked in by driving the fan, and the sucked air is discharged to the outside of air discharge section 50.

[0037] 3, the discharge housing section 52 is provided near the rear end of each of the line heads 11-14 of the head section 2. The discharge housing section 52 has a housing that sucks in the cooling air that is supplied from the air blower housing section 42 of the air supply section 40 and flows along each of the line heads 11-14, and exhausts it toward the suction fan section 51. A cooling air suction hole 53 is formed in the surface of the housing of the discharge housing section 52 on the head section 2 side.

[0038] The cooling air suction holes 53 are formed at positions facing the cooling air supply holes 43 in the direction perpendicular to the conveying direction.

[0039] That is, in this embodiment, the cooling air supplied from the cooling air supply holes 43 passes between the line heads, is sucked by the cooling air suction holes 53, passes through the exhaust housing part 52 and the intake fan part 51, and is exhausted from the air exhaust part 50. As a result, each of the line heads 11 to 14 is cooled by the cooling air.

[0040] Although not shown in FIG. 3, as shown in FIG. 4A and FIG. 4B, a wind direction changing mechanism 45 such as a louver is provided between the cooling wind supply hole 43 and the satellite suppression wind supply hole 44 of the ventilation housing part 42. This controls whether the wind from the blowing fan part 41 is supplied to the cooling wind supply hole 43 or the satellite suppression wind supply hole 44. The wind direction changing mechanism 45 is provided, for example, for each satellite suppression wind supply hole 44, and when performing satellite suppression control, as shown in FIG. 4B, the control part 60 controls the wind direction changing mechanism 45 to supply the wind toward the satellite suppression wind supply hole 44, so that the satellite suppression wind flows toward the transport surface 21b. Note that in FIG. 4A and FIG. 4B, the wind flow direction is indicated by a dotted arrow.

[0041] 4A, when the satellite suppression control is not performed, the control unit 60 controls the airflow direction changing mechanism 45 to supply air toward the cooling air supply holes 43, so that the cooling air flows toward each of the line heads 11 to 14, thereby cooling each of the line heads 11 to 14. The control of the airflow direction changing mechanism 45 associated with the satellite suppression control will be described in detail later.

[0042] 5, a first louver 46 and a second louver 47 may be provided to direct the satellite suppression wind supplied from the satellite suppression wind supply holes 44 downward. A plurality of first louvers 46 are provided at intervals in the transport direction of the print medium P, and the satellite suppression wind that has passed between the first louvers 46 is supplied toward the second louvers 47. A plurality of second louvers 47 are provided at positions facing the spaces between the first louvers 46, and the satellite suppression wind that has passed between the first louvers 46 hits the second louvers 47, changing the wind direction downward.

[0043] 6 is a block diagram showing a schematic configuration of a control system of the inkjet printing apparatus 1 of this embodiment. The control unit 60 includes a CPU (Central Processing Unit), a semiconductor memory, a hard disk, and the like. The control unit 60 executes a program stored in advance in a storage medium such as the semiconductor memory or the hard disk, and controls the operation of each unit of the inkjet printing apparatus 1 by operating an electric circuit. In particular, the control unit 60 of this embodiment controls the driving of the blowing fan unit 41 and the suction fan unit 51, and controls the supply of the cooling air and the satellite suppression air. The control unit 60 also controls the airflow direction changing mechanism 45 as described above to control the direction in which the satellite suppression air flows.

[0044] Next, the operation of the inkjet printing apparatus 1 of this embodiment will be described.

[0045] The inkjet printing apparatus 1 of this embodiment first performs a process of determining whether or not to perform satellite suppression control. Fig. 7 is a flowchart for explaining the flow of the determination process.

[0046] As shown in FIG. 7, before printing, the control unit 60 acquires the paper width (width in a direction perpendicular to the transport direction) of the printing medium P to be printed, the transport speed of the printing medium P by the transport unit 3, and the distance between the head unit 2 and the transport unit 3 (hereinafter referred to as the head gap) (S10).

[0047] Regarding the paper width information, for example, paper width information included in the print job may be obtained, or information measured by an optical sensor not shown in the figure may be obtained, or information set and input by the user may be obtained.

[0048] In addition, the conveying speed may be measured by an optical sensor or a rotary encoder (not shown), or may be set and input by the user.

[0049] As for the head gap, information measured by an optical sensor (not shown) or information set and input by the user may be acquired.

[0050] Then, the control unit 60 judges whether the acquired paper width, transport speed, and head gap satisfy the preset conditions (S12). If at least one of the paper width, transport speed, and head gap does not satisfy the preset conditions (S12, NO), the control unit 60 performs satellite suppression control to supply satellite suppression air to the transport unit 3 (S14).

[0051] On the other hand, when the paper width, transport speed, and head gap all satisfy the preset conditions (S12, YES), the control unit 60 performs normal printing without performing satellite suppression control (S16). When performing normal printing, only cooling of the line heads 11 to 14 is performed by cooling air.

[0052] The control unit 60 determines whether the paper width is equal to or larger than a preset paper width threshold. When the paper width is smaller than the paper width threshold, as shown in FIG. 8, the belt holes near the side edges extending in the transport direction of the print medium P are opened, so that the mist is sucked in and the effect of satellites on the side edges becomes large. Therefore, when the paper width is smaller than the paper width threshold, the control unit 60 performs satellite suppression control. Note that FIG. 8 is a view of the print medium P, the transport unit 3, and the line heads 11 to 14 as viewed from above, and the arrows in FIG. 8 indicate the direction of the suction air.

[0053] In addition, the control unit 60 judges whether the conveying speed is equal to or higher than a preset speed threshold. If the conveying speed is slower than the speed threshold, the time during which the sheet is affected by the suction wind of the belt holes becomes longer, and satellites are easily washed away, causing image degradation. Therefore, if the conveying speed is slower than the speed threshold, the control unit 60 performs satellite suppression control.

[0054] In addition, the control unit 60 determines whether the head gap is equal to or smaller than a preset gap threshold. If the head gap is larger than the gap threshold, satellites are likely to be washed away and image deterioration may occur. Therefore, if the head gap is larger than the gap threshold, the control unit 60 performs satellite suppression control.

[0055] Next, a printing operation involving satellite suppression control will be described in more detail.

[0056] First, the control unit 60 starts driving the drive roller 22 and the fan 38. Drive of the drive roller 22 causes the conveyor belt 21 to rotate in the clockwise direction in FIG. 1, and moves in the conveying direction of the print medium P between the drive roller 22 and the driven roller 23. As the conveyor belt 21 rotates, the belt holes pass over the platen 26 from left to right.

[0057] On the other hand, when the fan 38 is driven to exhaust air from the chamber 37, a negative pressure is generated in the chamber 37. A negative pressure is generated in the chamber 37.

[0058] After the drive roller 22 and the fan 38 start to operate, when the printing medium P is fed from the paper feed section (not shown) to the conveying section 3, some of the belt holes of the conveying belt 21 are covered by the fed printing medium P, thereby causing the printing medium P to be adsorbed to the belt holes.

[0059] The conveyor belt 21 attracts and holds the print medium P on the conveyor surface 21b by the attraction force generated in the belt holes covered by the print medium P. The conveyor belt 21 conveys the attracted and held print medium P to the right by rotating in the clockwise direction in FIG.

[0060] Then, when the leading end (the end on the downstream side in the transport direction) of the print medium P reaches the line head 11 arranged on the most upstream side due to transport by the transport belt 21, the print process by the line head 11 starts. At this time, as shown in FIG. 9, the belt holes of the transport belt 21 are blocked by the print medium P immediately below the line head 11, but the belt holes of the transport belt 21 are open immediately below the line heads 12 to 14 arranged downstream of the line head 11. Therefore, satellites generated by ink ejection from the line head 11 flow toward the belt holes by the suction wind generated in the belt holes immediately below the line heads 12 to 14, and the influence of the satellites on the leading end of the print medium P becomes large. Note that FIG. 9 is a view of the print medium P, the transport unit 3, and the line heads 11 to 14 as viewed from above, and the arrows shown in FIG. 9 indicate the direction of the suction wind.

[0061] Therefore, the control unit 60 starts driving the blowing fan unit 41 and the suction fan unit 51 and starts supplying the satellite suppression airflow from the point in time when the leading end of the printing medium P (the end on the downstream side in the transport direction) reaches the line head 11 arranged on the most upstream side. However, at this time, if the satellite suppression airflow is supplied in the vicinity of the line head 11 that has started the printing process, this may affect the landing accuracy of the ink ejected from the line head 11.

[0062] Therefore, the control unit 60 of this embodiment does not supply the satellite suppression air to the area corresponding to the printable range of the line head 11, but supplies the satellite suppression air only to the areas corresponding to the printable ranges of the line heads 12 to 14. Specifically, for example, of the five satellite suppression air supply holes 44 shown in Fig. 3, for the satellite suppression air supplied from the second satellite suppression air supply holes 44 from the left near the end of the line head 11, the control unit 60 controls the above-mentioned air direction changing mechanism 45 so that the satellite suppression air is not supplied toward the transport surface 21b.

[0063] 3, the satellite suppression air supplied from the remaining three satellite suppression air supply holes 44 is supplied toward the transport surface 21b by controlling the above-mentioned air direction changing mechanism 45. In other words, the satellite suppression air is supplied only to the area corresponding to the printable range of the line heads 12 to 14.

[0064] Then, since the printing process by the line heads 12 to 14 starts once the printing process by the line head 11 on the leading end of the printing medium P is completed, the control unit 60 prevents satellite suppression wind from being supplied from all of the satellite suppression wind supply holes 44 toward the transport surface 21b in order to prevent a decrease in the landing accuracy of the ink ejected from these line heads 12 to 14.

[0065] Then, the control unit 60 starts the printing process by the line head 14 when the printing medium P is further transported, the printing process by the line heads 11 to 13 is completed, and the rear end of the printing medium P (the end on the upstream side in the transport direction) reaches the line head 14 arranged on the most downstream side. At this time, as shown in FIG. 10, the belt holes of the transport belt 21 are blocked by the printing medium P immediately below the line head 14, but the belt holes of the transport belt 21 are open immediately below the line heads 11 to 13 arranged on the upstream side of the line head 14. Therefore, the satellites generated by the ink ejection from the line head 14 flow toward the belt holes by the suction wind generated in the belt holes immediately below the line heads 11 to 13, and the influence of the satellites on the rear end of the printing medium P becomes large. Note that FIG. 10 is a view of the printing medium P, the transport unit 3, and the line heads 11 to 14 as viewed from above, and the arrows shown in FIG. 10 indicate the direction of the suction wind.

[0066] Therefore, the control unit 60 again supplies the satellite suppression air toward the transport surface 21b. However, at this time, if the satellite suppression air is supplied near the printable range of the line head 14 that has started the printing process, it may affect the landing accuracy of the ink ejected from the line head 14.

[0067] Therefore, the control unit 60 of this embodiment does not supply the satellite suppression air to the area corresponding to the printable range of the line head 14, but supplies the satellite suppression air only to the area corresponding to the printable range of the line heads 11 to 13. Specifically, for example, of the five satellite suppression air supply holes 44 shown in Fig. 3, for the satellite suppression air supplied to the second satellite suppression air supply holes 44 from the right near the end of the line head 14, the control unit 60 controls the above-mentioned air direction changing mechanism 45 so that the satellite suppression air is not supplied toward the transport surface 21b.

[0068] 3, the satellite suppression air supplied from the remaining three satellite suppression air supply holes 44 is supplied toward the transport surface 21b by controlling the above-mentioned air direction changing mechanism 45. In other words, the satellite suppression air is supplied only to the area corresponding to the printable range of the line heads 11 to 13.

[0069] Then, when the rear end of the print medium P passes directly below the line head 14 arranged on the most downstream side, the control unit 60 stops driving the blowing fan unit 41 and the suction fan unit 51, and stops the supply of the satellite suppression air. The printed print medium P is discharged to a paper discharge unit (not shown).

[0070] During the printing process by the line heads 11 to 14 described above, cooling air is always supplied to the line heads 11 to 14. Therefore, in this embodiment, while cooling the line heads 11 to 14, satellite suppression air can be supplied to the transport section 3 only when printing the leading and trailing ends of the printing medium P.

[0071] In addition, the above explanation describes the transport of a single sheet of printing medium P and the operation during the printing process, but when printing a print job of multiple pages, i.e., when multiple printing media P are transported sequentially by the transport unit 3 with a specified paper spacing between them, satellite suppression air may be supplied to the transport unit 3 only when the leading end of the first page of printing medium P is printed by the line head 11 and when the trailing end of the final page of printing medium P is printed by the line head 14.

[0072] Next, an inkjet printing apparatus using a second embodiment of the printing apparatus of the present invention will be described. The inkjet printing apparatus of the second embodiment differs from the inkjet printing apparatus of the first embodiment only in the configuration of the cooling unit, and therefore only the different configuration will be described here.

[0073] 11 is a diagram showing a schematic configuration of the cooling section 4 of this embodiment. Like the cooling section 4 of the first embodiment, the cooling section 4 of this embodiment is also configured to be able to supply satellite suppression air to the transport section 3 under the control of the control section 60. However, the cooling section 4 of this embodiment differs from the cooling section 4 of the first embodiment in the method of supplying the satellite suppression air.

[0074] Specifically, the cooling section 4 of this embodiment includes an air supply section 40 having a blowing fan section 41 and an air-blowing housing section 42, similarly to the first embodiment. However, the air-blowing housing section 42 of this embodiment is not provided with a satellite suppression air supply hole 44, and the air supplied from the blowing fan section 41 flows out only from the cooling air supply hole 43.

[0075] In this embodiment, as shown in Fig. 11, a plurality of satellite suppression airflow supply holes 31 are formed in the head holder 30. Fig. 12 is a bottom view of the line heads 11-14 and the head holder 30 in which the satellite suppression airflow supply holes 31 are formed.

[0076] 12, in this embodiment, the satellite suppression airflow supply holes 31 are formed on both sides in the transport direction of each of the line heads 11 to 14. A plurality of the satellite suppression airflow supply holes 31 are arranged along each of the line heads 11 to 14 in a direction perpendicular to the transport direction.

[0077] In this embodiment, a part of the cooling air supplied from the cooling air supply hole 43 of the air supply unit 40 is configured to flow out from the satellite suppression air supply hole 31. Although not shown in Fig. 12, in order to increase the amount of satellite suppression air flowing out from the satellite suppression air supply hole 31, wall parts may be formed on the left and right sides and above the head holder 30 to surround the line heads 11 to 14 with a housing, and the inside of the housing may be pressurized. This allows a part of the cooling air supplied from the cooling air supply hole 43 to flow out sufficiently from the satellite suppression air supply hole 31.

[0078] Further, the cooling section 4 of this embodiment includes an air discharge section 50 having an intake fan section 51 and an exhaust casing section 52, similarly to the first embodiment.

[0079] As described above, part of the cooling air supplied from the cooling air supply hole 43 of the air supply unit 40 flows out from the satellite suppression air supply hole 31 of the head holder 30, and the rest passes between the line heads, is sucked in by the cooling air suction hole 53, passes through the exhaust housing unit 52 and the suction fan unit 51, and is exhausted from the air exhaust unit 50. Note that in order to further increase the amount of satellite suppression air from the satellite suppression air supply hole 31, the fan of the suction fan unit 51 may be stopped when satellite suppression control is performed.

[0080] 11 and 12, an airflow adjustment mechanism 32 (see FIG. 13), such as a shutter or a diaphragm, is provided in each satellite suppression air supply hole 31 of the head holder 30. The airflow adjustment mechanism 32 is controlled by the control unit 60, and the amount of air supplied from each satellite suppression air supply hole 31 toward the transport unit 3 is adjusted.

[0081] 13 is a block diagram showing a control system of the inkjet printing apparatus 1 of the second embodiment. The other configurations except for the air volume adjustment mechanism 32 are the same as those of the first embodiment.

[0082] Next, the operation of the inkjet printing device 1 of the second embodiment will be described. Note that the process of determining whether or not to perform satellite suppression control and the operation up to the point where the leading end of the printing medium P reaches the line head 11 on the most upstream side are similar to those of the inkjet printing device 1 of the first embodiment, so the explanation will be omitted and the operation thereafter will be described.

[0083] When the leading end (the end on the downstream side in the transport direction) of the print medium P reaches the line head 11 arranged on the most upstream side due to transport by the transport belt 21, the print process by the line head 11 starts. At this time, similar to the first embodiment, the control unit 60 of this embodiment does not supply the satellite suppression air to the area corresponding to the printable range of the line head 11, but supplies the satellite suppression air only to the area corresponding to the printable range of the line heads 12 to 14. Specifically, as shown in FIG. 14A, for example, among the multiple satellite suppression air supply holes 31, the satellite suppression air supply holes 31 in the area corresponding to the printable range of the line head 11 are blocked by the above-mentioned air volume adjustment mechanism 32 so as not to supply the satellite suppression air. On the other hand, the satellite suppression air supply holes 31 corresponding to the printable range of the line heads 12 to 14 are opened to supply the satellite suppression air.

[0084] Of the multiple satellite suppression air supply holes 31 shown in FIG. 14A, the satellite suppression air supply holes 31 indicated by gray circles are closed by the air volume adjustment mechanism 32, and the satellite suppression air supply holes 31 indicated by white circles are open.

[0085] Then, since the printing process by line heads 12 to 14 begins once the printing process by line head 11 on the leading edge of printing medium P is completed, the control unit 60 stops the supply of satellite suppression air from all satellite suppression air supply holes 31 in order to prevent a decrease in the landing accuracy of ink ejected from these line heads 12 to 14.

[0086] Then, when the printing medium P is further transported, the printing process by the line heads 11-13 is completed, and the rear end (the end on the upstream side in the transport direction) of the printing medium P reaches the line head 14 arranged on the most downstream side, the control unit 60 again supplies the satellite suppression air toward the transport surface 21b. At this time, similarly to the first embodiment, the control unit 60 of this embodiment controls the air volume adjustment mechanism 32 so that, as shown in FIG. 14B, the satellite suppression air is not supplied to the area corresponding to the printable range of the line head 14, but is supplied only to the area corresponding to the printable range of the line heads 11-13.

[0087] Then, when the rear end of the print medium P passes directly below the line head 14 arranged on the most downstream side, the control unit 60 stops driving the blowing fan unit 41 and the suction fan unit 51, and stops the supply of the satellite suppression air. The printed print medium P is discharged to a paper discharge unit (not shown).

[0088] In addition, in the inkjet printing device 1 of the second embodiment described above, the control unit 60 may control the air volume adjustment mechanism 32 in accordance with the paper width of the printing medium P to suppress the effect of satellites on the side ends extending in the transport direction of the printing medium P.

[0089] Specifically, for example, when the paper width is smaller than the paper width threshold, the control unit 60 may close the satellite suppression air supply hole 31 to not supply satellite suppression air to the area corresponding to the printable range according to the paper width, as shown in FIG. 15, and may open the satellite suppression air supply hole 31 to supply satellite suppression air to the area corresponding to the outside of the printable range according to the paper width.

[0090] In addition, the opening and closing control of the satellite suppression air supply hole 31 shown in Figure 15 may be combined with the opening and closing control of the satellite suppression air supply hole 31 when performing printing processing on the leading and trailing ends of the printing medium P described in Figures 14A and 14B.

[0091] Furthermore, in the inkjet printing apparatus 1 of the first and second embodiments, the control unit 60 may control the volume of the satellite suppression airflow. Specifically, the control unit 60 may increase the volume of the satellite suppression airflow as the transport speed of the print medium P in the transport unit 3 decreases, since the effect of satellites increases as the transport speed decreases. Furthermore, the control unit 60 may increase the volume of the satellite suppression airflow as the head gap increases, since the effect of satellites increases as the head gap increases.

[0092] Furthermore, in the inkjet printing apparatus 1 of the first and second embodiments, the control unit 60 may be configured to control the volume of the satellite suppression air based on the temperature of the head unit 2. Specifically, when the temperature of the head unit 2 is low, the viscosity of the ink increases, and satellites tend to increase. Therefore, the control unit 60 may be configured to increase the volume of the satellite suppression air as the temperature of the head unit 2 is lower. Regarding the temperature of the head unit 2, for example, a temperature sensor may be provided in each of the line heads 11 to 14, and the average value or minimum value of the temperatures detected by the temperature sensors may be used.

[0093] Furthermore, in the inkjet printing device 1 of the second embodiment, the temperature of each inkjet head 15 may be detected, and the size of the opening of the satellite suppression air supply hole 31 may be controlled for each area corresponding to the printable range of each inkjet head 15 in accordance with the detected temperature of each inkjet head 15, thereby changing the volume of the satellite suppression air.

[0094] Furthermore, in the inkjet printing apparatus 1 of the first and second embodiments, the control unit 60 may be configured to control the volume of the satellite suppression airflow based on the drive voltage of the head unit 2. Specifically, when the drive voltage of the head unit 2 is high, satellites tend to increase. Therefore, the control unit 60 may be configured to increase the volume of the satellite suppression airflow as the drive voltage of the head unit 2 is higher.

[0095] Furthermore, the drive voltage of each inkjet head 15 may be adjusted individually depending on the ejection characteristics of each inkjet head 15. Therefore, in the inkjet printing device 1 of the second embodiment, the volume of the satellite suppression air may be changed for each area corresponding to the printable range of each inkjet head 15 according to the drive voltage of each inkjet head 15.

[0096] According to the inkjet printing device 1 of the first and second embodiments, the cooling unit 4 that supplies cooling air to the head unit 2 is used to supply satellite suppression air to the transport unit 3, so that the supply of this satellite suppression air can block the flow of suction air, thereby restricting the movement of satellites and suppressing image deterioration. Also, because the cooling unit 4 of the head unit 2 can be used for both purposes, it is possible to avoid increases in costs and an increase in the size of the device.

[0097] 16A is a diagram showing the flow of the suction air when the satellite suppression air is not supplied, and FIG. 16B is a diagram showing the flow of the suction air when the satellite suppression air is supplied. As shown in FIG. 16B, the flow of the suction air can be blocked by supplying the satellite suppression air.

[0098] Furthermore, in the inkjet printing device 1 of the first and second embodiments described above, when the leading edge of the printing medium P is printed by the line head 11 arranged upstream in the transport direction, a satellite suppression wind is supplied to the area corresponding to the printable range of the line heads 12 to 14 arranged downstream in the transport direction, so that image degradation due to satellites at the leading edge of the printing medium P can be appropriately suppressed without compromising the landing accuracy of the ink ejected from the line head 11.

[0099] Furthermore, in the inkjet printing device 1 of the first and second embodiments described above, when printing the rear end of the printing medium P by the line head 14 arranged downstream in the transport direction, a satellite suppression wind is supplied to the area corresponding to the printable range of the line heads 11 to 13 arranged upstream in the transport direction, so that image degradation due to satellites at the rear end of the printing medium P can be appropriately suppressed without compromising the landing accuracy of the ink ejected from the line head 14.

[0100] Furthermore, in the inkjet printing device 1 of the second embodiment described above, based on the paper width of the printing medium P, satellite suppression air is supplied to an area corresponding to the printable range of the inkjet head 15 arranged in an area outside the printable range of the inkjet head corresponding to that paper width, so that image degradation due to satellites at the side edges of the printing medium P can be appropriately suppressed without compromising the landing accuracy of the ink ejected from the line heads 11-14.

[0101] Furthermore, in the inkjet printing device 1 of the first and second embodiments described above, if the volume of the satellite suppression air is controlled according to the transport speed and head gap, the volume of the satellite suppression air can be controlled according to the effect of the satellites, and image degradation can be appropriately suppressed.

[0102] Furthermore, in the inkjet printing device 1 of the first and second embodiments described above, if the volume of the satellite suppression air is controlled based on the temperature of the head section 2, the volume of the satellite suppression air can be controlled according to the amount of satellites, and image degradation can be appropriately suppressed.

[0103] Furthermore, in the inkjet printing device 1 of the first and second embodiments described above, if the volume of the satellite suppression air is controlled based on the driving voltage supplied to the head unit 2, the volume of the satellite suppression air can be controlled according to the amount of satellites, and image degradation can be appropriately suppressed.

[0104] Furthermore, in the inkjet printing device 1 of the first and second embodiments described above, the supply of satellite suppression air is controlled based on at least one of the conditions of the paper width, transport speed, and head gap of the printing medium P, so that appropriate control of the supply of satellite suppression air can be performed according to the printing conditions.

[0105] The present invention is not limited to the above-described embodiment, and the components can be modified and embodied in the implementation stage without departing from the gist of the invention. In addition, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiment. For example, all the components shown in the embodiment can be appropriately combined. Of course, various modifications and applications are possible without departing from the spirit of the invention.

[0106] The present invention further discloses the following supplementary notes.

[0107] (Appendix 1) The printing device of the present invention comprises a transport section that transports the printing medium while suctioning it, a head section that ejects ink onto the printing medium transported by the transport section, a cooling section that supplies cooling air to the head section, and a control section that controls the cooling section, and the cooling section is configured to be able to supply air to the transport section.

[0108] (Appendix 2) In the printing device described in Supplementary Note 1, the control unit can control the timing of supplying air to the transport unit.

[0109] (Appendix 3) In the printing device according to supplementary note 1 or supplementary note 2, the control unit can control the supply of air to the transport unit for each area obtained by dividing the range printable by the head unit.

[0110] (Appendix 4) In the printing device described in Appendix 3, the head unit has a plurality of inkjet heads arranged in the transport direction, and the control unit can supply air to an area corresponding to the printable range of the inkjet head arranged downstream in the transport direction when printing on the downstream end of the print medium in the transport direction using the inkjet head arranged upstream in the transport direction.

[0111] (Appendix 5) In the printing device described in Appendix 3 or Appendix 4, the head unit has a plurality of inkjet heads arranged in the transport direction, and the control unit can supply air to an area corresponding to the printable range of the inkjet head arranged upstream in the transport direction when printing on the upstream end of the print medium in the transport direction using the inkjet head arranged downstream in the transport direction.

[0112] (Appendix 6) In the printing device described in any one of Supplementary Notes 3 to 5, the head unit has a plurality of inkjet heads arranged in a direction perpendicular to the transport direction, and the control unit can supply air to the printable range of an inkjet head that is arranged in an area other than the printable range of the inkjet head that corresponds to the width of the print medium in the direction perpendicular to the transport direction, based on that width.

[0113] (Appendix 7) In the printing device according to any one of Supplementary Note 1 to Supplementary Note 6, the control unit can control the volume of airflow to the transport unit.

[0114] (Appendix 8) In the printing device described in Supplementary Note 7, the control unit can control the volume of air blown to the transport unit based on the temperature of the head unit.

[0115] (Appendix 9) In the printing device described in Supplementary Note 7, the control unit can control the volume of air blown to the transport unit based on the drive voltage supplied to the head unit.

[0116] (Appendix 10) In a printing device described in any one of Supplementary Notes 1 to 9, the control unit can control the supply of air to the transport unit based on at least one condition of the width of the printing medium in a direction perpendicular to the transport direction, the transport speed of the transport unit, and the distance between the head unit and the transport unit.

[0117] (Appendix 11) The printing method of the present invention is a printing method in which a print medium is transported while being suctioned and ink is ejected onto the transported print medium to print, and cooling air can be supplied to the head section that ejects the ink, and the cooling air can be supplied to the transport section that transports the print medium. [Explanation of symbols]

[0118] 1 Inkjet printing device 2 Head section 3. Conveyor 4 Cooling section 11~14 Line Head 15 Inkjet head 15a Discharge surface 21 Conveyor belt 21b Conveying surface 22 Drive roller 23~25 Driven roller 26 Platen 27 Suction part 30 Head Holder 31 Satellite suppression air supply hole 32 Air volume adjustment mechanism 35 Drive motor 37 Chamber 38 Fans 40 Air supply section 41 Blowing fan section 42 Blower housing part 43 Cooling air supply hole 44 Satellite suppression air supply hole 45 Wind direction change mechanism 50 Air exhaust section 51 Intake fan section 52 Exhaust housing part 53 Cooling air suction hole 60 Control section P Print media

Claims

1. a conveying unit that conveys the print medium while suctioning the print medium; a head unit that ejects ink onto the print medium transported by the transport unit; a cooling unit that supplies cooling air to the head unit; A control unit that controls the cooling unit, The printing device, wherein the cooling unit is configured to be able to supply air to the transport unit.

2. The printing apparatus according to claim 1 , wherein the control unit controls a timing of supplying air to the transport unit.

3. The printing apparatus according to claim 1 , wherein the control unit controls the supply of air to the transport unit for each area obtained by dividing a range printable by the head unit.

4. the head unit has a plurality of inkjet heads arranged in the transport direction, 4. The printing device according to claim 3, wherein the control unit supplies air to an area corresponding to a printable range of an inkjet head arranged downstream in the transport direction when printing on the downstream end of the printing medium in the transport direction using an inkjet head arranged upstream in the transport direction.

5. the head unit has a plurality of inkjet heads arranged in the transport direction, 4. The printing device according to claim 3, wherein the control unit supplies air to an area corresponding to a printable range of an inkjet head arranged upstream in the transport direction when printing on the upstream end of the print medium in the transport direction using an inkjet head arranged downstream in the transport direction.

6. the head unit has a plurality of inkjet heads arranged in a direction perpendicular to the transport direction, The printing device according to claim 3 , wherein the control unit supplies air to the printable range of an inkjet head arranged in an area other than the printable range of an inkjet head corresponding to the width of the printing medium in a direction perpendicular to the transport direction.

7. The printing apparatus according to claim 1 , wherein the control unit controls an amount of air blown onto the transport unit.

8. The printing apparatus according to claim 7 , wherein the control unit controls the amount of air blown to the transport unit based on the temperature of the head unit.

9. The printing apparatus according to claim 7 , wherein the control unit controls the volume of air blown onto the transport unit based on a drive voltage supplied to the head unit.

10. A printing device as described in claim 1 , wherein the control unit controls the supply of air to the transport unit based on at least one condition of the width of the printing medium in a direction perpendicular to the transport direction, the transport speed of the transport unit, and the distance between the head unit and the transport unit.

11. A printing method in which a print medium is transported while being suctioned, and ink is ejected onto the transported print medium to print, comprising the steps of: A printing method in which cooling air can be supplied to a head unit that ejects the ink, and the cooling air can be supplied to a transport unit that transports the print medium.

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