Maintenance device and inkjet recording apparatus

Abstract

To suppress a humidifying medium from entering an air supply pipe.SOLUTION: A maintenance device includes: a cap to be attached to a nozzle surface of an inkjet head; and a supply portion which accumulates a humidifying medium therein, generates humidified air by causing air to pass through the humidifying medium, and supplies the humidified air to the cap via an air supply pipe 72N that is in communication with the cap. Therein: inside the supply portion, the air supply pipe 72N is provided along a vertical direction in a space above a fluid level of the humidifying medium and is provided with cuts 72 NS in at least an inner surface side of a pipe wall 72NW of the air supply pipe 72N.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present invention relates to a maintenance device for performing maintenance on an inkjet head, and an inkjet recording apparatus. [Background technology]

[0002] In an inkjet recording device that uses water-based ink, moisture evaporates from the ink in the nozzles while printing is not being performed, causing the viscosity to increase, which can lead to ejection failure and clogging. Therefore, techniques for suppressing the evaporation of moisture from the ink in the nozzles have been studied. For example, Patent Document 1 describes a device that supplies humidified air into a cap that covers the ejection surface (nozzle surface) of a head. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-131064 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration disclosed in Patent Document 1, air is pumped into the water (humidification medium) in a tank to generate humidified air, and the humidified air is then supplied to the cap via a tube (air supply pipe), so there is a risk that the air will raise the liquid level in the tank, causing the humidification medium to seep into the air supply pipe or cap. It is possible to prevent the humidification medium from seeping in by increasing the distance between the connection part of the air supply pipe and the liquid level, but a deeper water depth is advantageous for improving the humidification effect. To satisfy these two requirements, the size of the tank needs to be increased, which creates a problem of making the device larger.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In consideration of the above circumstances, an object of the present invention is to prevent the infiltration of a humidifying medium into an air intake pipe. [Means for solving the problem]

[0006] In order to solve the above problems, the maintenance device of the present invention comprises a cap that is attached to the nozzle face of an inkjet head, and a supply unit that stores a humidifying medium and generates humidified air by passing air through the humidifying medium, and supplies the humidified air to the cap through an air supply pipe connected to the cap, wherein inside the supply unit, the air supply pipe is arranged in a space above the liquid level of the humidifying medium along the vertical direction, and a slit is provided on at least the inner side of the pipe wall of the air supply pipe.

[0007] The cut may be provided along the vertical direction.

[0008] The cut may extend through a lower end surface of the tube wall.

[0009] The cut may extend through the tube wall from the inner surface to the outer surface.

[0010] An inkjet recording apparatus according to the present invention includes a plurality of the inkjet heads and any one of the maintenance devices described above. Effect of the Invention

[0011] According to the present invention, it is possible to suppress the intrusion of the humidifying medium into the air intake pipe. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view showing an external appearance of an image forming system according to an embodiment of the present invention; [Diagram 2] 1 is a front view showing a schematic internal configuration of an inkjet recording apparatus according to an embodiment of the present invention; [Diagram 3] FIG. 2 is a front view showing a schematic diagram of a head unit and a maintenance device according to an embodiment of the present invention. [Figure 4] FIG. 2 is a plan view illustrating a head unit and a wipe unit according to an embodiment of the present invention. [Diagram 5]FIG. 2 is a plan view showing a schematic diagram of a cap unit according to an embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing an ink-jet head according to an embodiment of the present invention. [Figure 7] 5A to 5C are front views showing the operation of the maintenance device according to the embodiment of the present invention. [Figure 8] FIG. 2 is a perspective view showing a cap unit according to an embodiment of the present invention. [Figure 9] FIG. 2 is a plan view showing a cap unit according to an embodiment of the present invention. [Figure 10] 10 is a cross-sectional view showing a cross section II of FIG. 9. [Figure 11] FIG. 2 is an exploded view showing a cap unit according to an embodiment of the present invention. [Figure 12] 11A and 11B are diagrams showing the flow of humidified air within a cap unit according to one embodiment of the present invention. [Figure 13] FIG. 2 is a plan view showing the positions of a supply section and a recovery section according to an embodiment of the present invention. [Figure 14] 5 is a cross-sectional view showing the flow of humidified air within a cap according to one embodiment of the present invention. FIG. [Figure 15] 1 is a perspective view showing an air intake pipe according to one embodiment of the present invention; [Figure 16] FIG. 2 is a perspective view showing an air intake pipe according to a first modified example of an embodiment of the present invention. [Figure 17] FIG. 11 is a perspective view showing an air intake pipe according to a second modified example of one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An inkjet recording apparatus 1 according to one embodiment of the present invention will be described below with reference to the drawings.

[0014] FIG. 1 is a perspective view showing the appearance of an image forming system 100. FIG. 2 is a front view showing the internal configuration of an inkjet recording device 1. FIG. 3 is a front view showing a head unit 11 and a maintenance device 30. FIG. 4 is a plan view showing a head unit 11 and a wipe unit 32. FIG. 5 is a plan view showing a cap unit 31. FIG. 6 is a cross-sectional view showing an inkjet head 12. FIG. 7 is a front view showing the operation of a maintenance device 30. In the following, the front side of the paper in FIG. 2 is the front side (front side) of the inkjet recording device 1, and the left and right directions are described based on the direction when the inkjet recording device 1 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr respectively indicate up, down, left, right, front, and rear.

[0015] The image forming system 100 (see FIG. 1) includes a paper feeder 110, an inkjet recording device 1, a drying device 120, and a post-processing device 130. The paper feeder 110 stores several thousand sheets and supplies the sheets to the inkjet recording device 1. The inkjet recording device 1 forms an image on the sheets using an inkjet method. The drying device 120 heats the sheets transported from the inkjet recording device 1 to dry the ink. The post-processing device 130 performs post-processing such as punching, stapling, and folding on the sheets transported from the drying device 120.

[0016] The inkjet recording device 1 (see FIG. 2) includes a rectangular parallelepiped main housing 3. A transport unit 7 that adsorbs and transports a sheet in the Y direction is provided in the center of the main housing 3. An imaging unit 6 that ejects ink to form an image is provided above the transport unit 7. A paper feed port 8 that introduces a sheet from a paper feed device 110 is provided on the right side of the main housing 3. A discharge port 9 that discharges the sheet on which an image has been formed to a drying device 120 is provided on the left side of the main housing 3. A transport path 10 is provided inside the main housing 3, which runs from the paper feed port 8 through a gap between the transport unit 7 and the imaging unit 6 to the discharge port 9. A registration roller 18 is provided upstream of the transport unit 7 in the transport direction Y.

[0017] The transport unit 7 includes an endless transport belt 21 and a suction unit 24. The transport belt 21 has many ventilation holes (not shown) and is wound around a drive roller 25 and a driven roller 22. The upper surface of the suction unit 24 has many ventilation holes (not shown) and is in contact with the inner surface of the transport belt 21. The suction unit 24 sucks air through the ventilation holes of the transport belt 21 and the ventilation holes of the suction unit 24, thereby adsorbing the sheet to the transport belt 21. The drive roller 25 is driven in the counterclockwise direction by a drive unit (not shown) including a motor and a reduction gear, so that the transport belt 21 rotates in the counterclockwise direction, and the sheet adsorbed to the transport belt 21 is transported in the Y direction.

[0018] The imaging unit 6 includes a plurality of (four in this embodiment) head units 11. Each head unit 11 (see FIGS. 3 and 4) includes one or more (three in this embodiment) inkjet heads 12. An ink container 20 filled with black, cyan, magenta, or yellow ink is connected to each head unit 11.

[0019] The inkjet head 12 (see FIG. 6) includes a rectangular parallelepiped housing 12H with the longitudinal direction being the front-rear direction, a nozzle plate 14 provided at the bottom of the housing 12H, and a socket 12S to which a pipe for supplying ink is connected. The nozzle plate 14 includes a number of nozzles 14N arranged in the front-rear direction. The nozzle 14N includes a branch flow path 14B branched from the downstream side of the socket 12S, and an ejection port 14A provided in a nozzle surface 14F, which is the lower surface of the nozzle plate 14. The vibration plate 14V also serves as a part of the inner wall of the branch flow path 14B. The vibration plate 14V is provided with a pressure element 14Z. A piezoelectric element, an electrostatic actuator, a heater, or the like is used as the pressure element 14Z. A drive circuit 12D for driving the pressure element 14Z is connected to the pressure element 14Z.

[0020] The control unit 2 (see FIG. 2) includes a calculation unit and a storage unit (not shown). The calculation unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The calculation unit performs various processes by reading and executing control programs stored in the storage unit. The control unit 2 may be realized by an integrated circuit that does not use software.

[0021] A display operation unit 19 is provided on the upper part of the main body housing 3 (see Figs. 1 and 2). The display operation unit 19 includes a display panel, a touch panel laminated on the display panel, and a keypad (not shown). The control unit 2 displays a screen showing the operation menu and status of the inkjet recording device 1 on the display panel, and controls each part of the inkjet recording device 1 in response to operations detected by the touch panel and the keypad.

[0022] The basic image forming operation of the inkjet recording device 1 is as follows. When an image forming job is input to the inkjet recording device 1 from the display operation unit 19 or an external computer, the paper feeder 110 sends out a sheet to the transport path 10 through the paper feed port 8, and the registration rollers 18, whose rotation has been stopped, correct any skew of the sheet. When the registration rollers 18 send out the sheet to the transport unit 7 at a predetermined timing, the transport unit 7 attracts the sheet to the transport belt 21 and transports it in the Y direction. Ink is ejected from the inkjet head 12 onto the sheet, and an image is formed. The sheet on which the image has been formed is discharged to the drying device 120 through the discharge port 9.

[0023] [Maintenance equipment] Next, the maintenance device 30 will be described. Since the four head units 11 have the same configuration, and the four maintenance devices 30 have the same configuration, the following describes one head unit 11 and one maintenance device 30 provided to the right of it.

[0024] The head unit 11 includes a head base 11B (see FIGS. 3 and 4) that supports the inkjet heads 12. Three inkjet heads 12 are provided in a staggered manner on the head base 11B.

[0025] The maintenance device 30 (see FIG. 3) is provided on the side (the right side in this embodiment) of the head unit 11. The maintenance device 30 includes a cap unit 31 and a wipe unit 32.

[0026] [Cap Unit] The cap unit 31 (see FIGS. 3 and 5) has caps 72 in the same number (three in this embodiment) as the inkjet heads 12 included in the head unit 11. The three caps 72 are arranged in a staggered manner similar to the inkjet heads 12, and are supported by a frame 71.

[0027] [Wipe unit] The wiping unit 32 (see FIGS. 3 and 4) includes a waste liquid tray 81 and a cleaning member 82. The waste liquid tray 81 includes recesses 81U in the same number as the inkjet heads 12 included in the head unit 11. The recesses 81U are arranged in a staggered manner, similar to the inkjet heads 12. The cleaning member 82 is provided in each recess 81U. The cleaning member 82 is, for example, a blade. The waste liquid tray 81 includes a drive unit (not shown) that slides the cleaning member 82 along the nozzle surface 14F. The waste liquid tray 81 is placed on a plurality of caps 72. In other words, the wiping unit 32 is placed on the cap unit 31. The head unit 11 includes a cleaning liquid supplying device 13 (see FIG. 6) that supplies cleaning liquid to the nozzle surface 14F.

[0028] [Head lifting device] The head lifting device 11L (see FIG. 4) is provided in front of and behind the head base 11B. The head lifting device 11L is composed of, for example, a ball screw, a belt drive device, etc. The head lifting device 11L lifts and lowers the head unit 11 between an image forming position and a retreated position. The image forming position (see FIG. 7(A)) is a position where the distance between the conveying path 10 (the upper surface of the conveying belt 21) through which the sheet is conveyed and the nozzle surface 14F is a predetermined distance suitable for image formation. The image forming position is the lower limit position of the lifting range of the head unit 11 by the head lifting device 11L. The retreated position (see FIG. 7(B)) is a position where the head unit 11 does not interfere with the wiping unit 32 when the cap unit 31 and the wiping unit 32 are slid using the cap slide device 34 described later. The retreated position is the upper limit position of the lifting range of the head unit 11.

[0029] [Cap slide device] The cap slide device 34 (see FIG. 5) is provided in front of and behind the frame body 71 of the cap unit 31. The cap slide device 34 is composed of, for example, a ball screw, a belt drive device, etc. The cap slide device 34 slides the cap unit 31 to a home position and a maintenance position. The home position (see FIG. 7(A)) is a position to the right of the head unit 11 located at the image forming position. The maintenance position (see FIG. 7(F)) is a position below the head unit 11 located at the retracted position.

[0030] [Wipe lifting device] The wipe lifting device 35 (see FIG. 4) is provided in front of and behind the waste liquid tray 81 of the wipe unit 32. The wipe lifting device 35 is formed, for example, of a ball screw, a belt drive device, etc. The wipe lifting device 35 lifts and lowers the wipe unit 32 to a contact position (see FIG. 6(B)) where the waste liquid tray 81 contacts the cap 72, and a separated position (see FIG. 6(E)) where the waste liquid tray 81 is separated a predetermined distance from the cap 72.

[0031] Next, the configuration of the cap unit 31 will be described in detail. Fig. 8 is a perspective view showing the cap unit 31. Fig. 9 is a plan view showing the cap unit 31. Fig. 10 is a cross-sectional view showing cross section II of Fig. 9. Fig. 11 is an exploded view showing the cap unit 31. Fig. 12 is a diagram showing the flow of the humidified air WA inside the cap unit 31. Fig. 13 is a plan view showing the positions of the supply unit 92 and the recovery unit 94. Fig. 14 is a cross-sectional view showing the flow of the humidified air WA inside the cap 72.

[0032] The maintenance device 30 of this embodiment comprises a plurality of caps 72 attached to the nozzle surface 14F of the inkjet head 12, an air intake port 72NA and an exhaust port 72EA provided in each of the plurality of caps 72, one collection section 94 that collects air A from the exhaust ports 72EA of all the caps 72, and a plurality of supply sections 92 provided for each cap 72 and supplying humidified air WA obtained by humidifying the air A collected by the collection section 94 to the air intake port 72NA, the plurality of supply sections 92 being arranged around the single collection section 94, and in each of the plurality of caps 72, the exhaust port 72EA is provided on the collection section 94 side and the air intake port 72NA is provided on the supply section 92 side.

[0033] The multiple caps 72 include a first cap 721, a second cap 722, and a third cap 723, the first cap 721 and the second cap 722 are arranged along a predetermined direction (e.g., the front-to-rear direction), the third cap 723 is arranged at a position intermediate between the first cap 721 and the second cap 722 in the predetermined direction, and is arranged at a position different from the first cap 721 and the second cap 722 in a direction intersecting the predetermined direction, and the exhaust port 72EA of the first cap 721 is provided on the second cap 722 side, and the exhaust port 72EA of the second cap 722 is provided on the first cap 721 side.

[0034] [cap] The cap 72 (see Figs. 8 to 10) is formed in a box shape that opens upward. The cap 72 has a roughly rectangular bottom 72B with the longitudinal direction being the front-to-rear direction, and a side wall 72W that stands upright upward from the edge of the bottom 72B. The side wall 72W is formed of a flexible material such as rubber. The bottom 72B is provided with an air intake port 72NA and an exhaust port 72EA.

[0035] The three caps 72 are arranged in a staggered manner. The first cap 721 is arranged on the right rear side of the frame body 71, the second cap 722 is arranged in front of the first cap 721, and the third cap 723 is arranged on the left side of the frame body 71. In the first cap 721 and the third cap 723, an exhaust port 72EA is provided on the front side, and an air intake port 72NA is provided on the rear side. In the second cap 722, an exhaust port 72EA is provided on the rear side, and an air intake port 72NA is provided on the front side. Note that in the second cap 722, an exhaust port 72EA may be provided on the front side, and an air intake port 72NA may be provided on the rear side.

[0036] [Supply section, recovery section] Below the frame 71 (see Figs. 8, 11 to 13), there are provided supply units 92, the same number as the caps 72 (three in this embodiment), and one recovery unit 94. Both the supply units 92 and the recovery unit 94 are tanks that store fluid. The supply units 92 and the recovery unit 94 are supported by the frame 91. Each supply unit 92 is disposed below the air supply port 72NA of each cap 72. The recovery unit 94 has a shape that overlaps with all the exhaust ports 72EA in a plan view, and is disposed below all the exhaust ports 72EA.

[0037] In other words, the three supply parts 92 are arranged around one collection part 94, and in each of the three caps 72, the exhaust port 72EA is provided on the collection part 94 side, and the intake port 72NA is provided on the supply part 92 side. In other words, all the exhaust ports 72EA overlap with the collection part 94 in the vertical direction, and in each of the multiple caps 72, the intake port 72NA overlaps with the supply part 92 in the vertical direction.

[0038] An air supply pipe 72N (see FIG. 10) that connects the cap 72 to the supply unit 92 below it is connected to the air supply port 72NA of each cap 72. An exhaust pipe 72E that connects the cap 72 to the collection unit 94 is connected to the exhaust port 72EA of each cap 72. In other words, three caps 72 are connected to the collection unit 94.

[0039] The air pump 95 is connected to the collection unit 94 by a collection flow path 95E (see FIGS. 8, 9, and 11), and is connected to all of the supply units 92 by a supply flow path 95N. The air pump 95 collects air A whose water vapor pressure has been reduced from the collection unit 94 via the collection flow path 95E, and supplies the collected air A to all of the supply units 92 via the supply flow path 95N (see FIG. 12).

[0040] All of the supply units 92 are connected to a sub-tank 93 via a communicating pipe 92C (see FIGS. 10, 11, and 12). A tank 93T and a pump 93P are connected to the sub-tank 93. The tank 93T stores the humidifying medium WM (see FIG. 14). The humidifying medium WM is, for example, water, but may be any liquid containing water. The pump 93P supplies the humidifying medium WM from the tank 93T to the sub-tank 93.

[0041] The sub-tank 93 is provided with a sensor 93S (see FIGS. 8, 9, 11, and 12) that detects the amount of humidification medium WM in the sub-tank 93. The sensor 93S detects, for example, the height of the liquid surface in the sub-tank 93. The supply unit 92 is provided with a first heating unit 92H (see FIG. 10) that heats the supply unit 92. The cap 72 is provided with a second heating unit 72H that heats the cap 72. The supply unit 92 is provided with a sensor 92S that measures the temperature inside the supply unit 92. The cap 72 is provided with a sensor 72S that measures the temperature inside the cap 72. The collection unit 94 is provided with a sensor 94S that measures at least one of the temperature and humidity inside the collection unit 94.

[0042] [Air supply pipe] Incidentally, when air A is sent to the humidifying medium WM stored in the supply unit 92, the liquid level of the humidifying medium WM may rise partially due to the air A, and the humidifying medium WM may infiltrate into the air supply pipe 72N. If the infiltrated humidifying medium WM adheres to the inner surface of the air supply pipe 72N, the flow path in the air supply pipe 72N may become narrow or blocked, preventing the supply of the humidified air WA. In addition, the adhered humidifying medium WM may be pushed by the humidified air WA and infiltrate into the cap 72. If the humidifying medium WM infiltrates into the cap 72, it becomes difficult to control the temperature and humidity inside the cap 72.

[0043] Therefore, the maintenance device 30 according to this embodiment includes a cap 72 that is attached to the nozzle surface 14F of the inkjet head 12, and a supply unit 92 that stores a humidification medium WM, generates humidified air WA by passing air A through the humidification medium WM, and supplies the humidified air WA to the cap 72 through an air supply pipe 72N that communicates with the cap 72, and inside the supply unit 92, the air supply pipe 72N is provided in the vertical direction in a space above the liquid level of the humidification medium WM, and a slit 72NS is provided at least on the inner surface side of a pipe wall 72NW of the air supply pipe 72N. Specifically, it is as follows.

[0044] FIG. 15 is a perspective view showing the air supply pipe 72N. The air supply pipe 72N has a cylindrical pipe wall 72NW with the vertical direction as the longitudinal direction. The upper end of the pipe wall 72NW is connected to the air supply port 72NA. The lower end of the pipe wall 72NW is disposed in a space above the liquid level of the humidifying medium WM stored in the supply unit 92. The pipe wall 72NW has a slit 72NS along the vertical direction in a predetermined range including the lower end of the pipe wall 72NW. The slit 72NS penetrates the lower end of the pipe wall 72NW. The slit 72NS penetrates from the inner surface to the outer surface of the pipe wall 72NW. The slits 72NS are provided at six equal intervals in the circumferential direction of the pipe wall 72NW.

[0045] Next, the basic operation of the maintenance device 30 will be described. In the initial state (see FIG. 7(A)), the head unit 11 is located at the image forming position, and the cap unit 31 is located at the home position. The wipe unit 32 is placed on the cap unit 31. In other words, the waste liquid tray 81 is in contact with the cap 72. The control unit 2 executes the process shown below at a predetermined timing. The predetermined timing is, for example, a timing when the viscosity of the ink in the nozzle 14N is expected to increase, and specifically, when a period in which an image forming job is not executed continues for a predetermined period of time.

[0046] First, the control unit 2 operates the head lifting device 11L to raise the head unit 11 to the retracted position (see FIG. 7(B)). Next, the control unit 2 operates the cap slide device 34 to slide the cap unit 31 to the maintenance position (see FIG. 7(C)). At this time, since the wipe unit 32 is placed on the cap unit 31, the wipe unit 32 also slides to the maintenance position together with the cap unit 31. Next, the control unit 2 operates the head lifting device 11L to lower the head unit 11 to a height at which the nozzle surface 14F contacts the cleaning member 82 (see FIG. 7(D)).

[0047] Next, the control unit 2 forcibly ejects a predetermined amount of ink from the inkjet head 12, and then supplies cleaning liquid to the nozzle surface 14F and slides the cleaning member 82 along the nozzle surface 14F. Then, the ink remaining on the nozzle surface 14F is diluted with the cleaning liquid, and waste liquid containing the ink and cleaning liquid is scraped off by the cleaning member 82 and falls into the waste liquid tray 81.

[0048] Next, the control unit 2 operates the head lifting device 11L to raise the head unit 11 to the retracted position (see FIG. 7(C)). Next, the control unit 2 operates the cap sliding device 34 to slide the cap unit 31 and the wipe unit 32 to the home position (see FIG. 7(B)).

[0049] Next, the control unit 2 operates the wipe lifting device 35 to raise the wipe unit 32 to the separated position (see FIG. 7(E)). Next, the control unit 2 operates the cap slide device 34 to slide the cap unit 31 to the maintenance position (see FIG. 7(F)). At this time, since the wipe unit 32 is separated from the cap unit 31, the wipe unit 32 remains in the home position, and only the cap unit 31 slides to the maintenance position.

[0050] Next, the control unit 2 operates the head lifting device 11L to lower the head unit 11 to a height where the nozzle surface 14F contacts the cap 72 (see FIG. 7(G)). In this way, the cap 72 is attached to the nozzle surface 14F.

[0051] Next, the control unit 2 humidifies the inside of the cap 72. The control unit 2 monitors the measurement value by the sensor 93S and maintains the liquid level in the subtank 93 within a predetermined range. Specifically, when the measurement value of the liquid level falls below the predetermined range, a predetermined amount of humidifying medium WM is replenished from the tank 93T to the subtank 93 using the pump 93P. Since the subtank 93 is in communication with the supply unit 92 by the communication pipe 92C, the liquid level of the humidifying medium WM is uniform in the subtank 93 and all the supply units 92.

[0052] The air pump 95 (see FIG. 12) collects air A with a reduced water vapor pressure from the collection unit 94 through the collection flow path 95E, and supplies the collected air A to all the supply units 92 through the supply flow path 95N. The end of the supply flow path 95N on the supply unit 92 side is disposed below the liquid surface of the humidifying medium WM (see FIG. 14). Therefore, in the supply unit 92, air A is blown into the humidifying medium WM, and bubbles B are generated. The water vapor pressure of the bubbles B increases before the bubbles B rise to the liquid surface. In addition, since the humidifying medium WM in the supply unit 92 is heated by the first heating unit 92H, water vapor is easily generated. Therefore, the space above the liquid surface of the supply unit 92 is filled with humidified air WA with an increased water vapor pressure, and the humidified air WA flows into the cap 72 through the air supply pipe 72N. The air pump 95 may collect and supply air A continuously or intermittently.

[0053] Meanwhile, in the recovery section 94, air A is sucked in by the air pump 95, generating a negative pressure. Therefore, an airflow of the humidified air WA is generated in the cap 72, flowing from the air supply port 72NA to the air exhaust port 72EA. In addition, since the humidified air WA supplied to the cap 72 is heated by the first heating section 92H, convection occurs in the cap 72, and the high-temperature humidified air WA is supplied to the nozzle surface 14F. In this way, the humidified air WA comes into contact with the ink in the nozzles 14N, suppressing an increase in the viscosity of the ink.

[0054] When air A is fed into the humidifying medium WM, the liquid level of the humidifying medium WM may rise partially, and the humidifying medium WM may infiltrate into the air supply pipe 72N, but in this embodiment, when the liquid level of the humidifying medium WM rises, the humidifying medium WM returns to the liquid level through the slit 72NS provided in the pipe wall 72NW, so that the infiltration of the humidifying medium WM into the air supply pipe 72N can be suppressed. As a result, the infiltration of the humidifying medium WM into the cap 72 can also be suppressed. In addition, the infiltration of the humidifying medium WM is suppressed without increasing the distance between the lower end of the air supply pipe 72N and the liquid level of the humidifying medium WM, so that the size of the supply unit 92 can be reduced.

[0055] In addition to the above controls, the control unit 2 controls the temperature of each unit. Specifically, each inkjet head 12 is provided with a sensor (not shown) that measures the temperature of the inkjet head 12 (for example, the temperature of ink in the nozzle 14N). As described above, the supply unit 92 is provided with a first heating unit 92H (see FIG. 10) that heats the supply unit 92. The cap 72 is provided with a second heating unit 72H that heats the cap 72. The supply unit 92 is provided with a sensor 92S that measures the temperature inside the supply unit 92. The cap 72 is provided with a sensor 72S that measures the temperature inside the cap 72. The collection unit 94 is provided with a sensor 94S that measures at least one of the temperature and humidity inside the collection unit 94.

[0056] The control unit 2 monitors the measurement value obtained by the sensor 92S, and controls the first heating unit 92H so that the temperature of the supply unit 92 is equal to or higher than the temperature of the inkjet head 12. If the temperature of the supply unit 92 is lower than the temperature of the inkjet head 12, the humidity of the humidified air WA supplied from the supply unit 92 may be lower than that in the nozzles 14N of the inkjet head 12, in which case the humidifying effect on the ink in the nozzles 14N cannot be obtained. In contrast, in this embodiment, humidified air WA with a higher humidity than that in the nozzles 14N of the inkjet head 12 is supplied.

[0057] Furthermore, the control unit 2 monitors the measurement value by the sensor 72S, and controls the second heating unit 72H so that the temperature of the cap 72 is equal to or higher than the temperature of the supply unit 92. If the temperature of the cap 72 is lower than the temperature of the supply unit 92, the temperature of the humidified air WA supplied from the supply unit 92 will drop inside the cap 72. If the temperature of the humidified air WA drops below the dew point, condensation will occur, reducing the humidity inside the cap 72 and making it impossible to obtain a humidifying effect. In contrast, in this embodiment, the temperature of the humidified air WA does not drop inside the cap 72, so there is no risk of the humidity inside the cap 72 dropping due to condensation.

[0058] When an image forming job is to be executed, the control unit 2 operates the head lifting device 11L to raise the head unit 11 to the retracted position (see FIG. 7(F)), operates the cap slide device 34 to slide the cap unit 31 to the home position (see FIG. 7(E)), and operates the wipe lifting device 35 to lower the wipe unit 32 to the contact position (see FIG. 7(B)). Then, the control unit 2 operates the head lifting device 11L to lower the head unit 11 to the image forming position, and executes the image forming job.

[0059] The maintenance device 30 according to the present embodiment described above includes a cap 72 attached to the nozzle surface 14F of the inkjet head 12, and a supply unit 92 that stores the humidifying medium WM, generates humidified air WA by passing air A through the humidifying medium WM, and supplies the humidified air WA to the cap 72 through an air supply pipe 72N that communicates with the cap 72. Inside the supply unit 92, the air supply pipe 72N is provided in the vertical direction in a space above the liquid level of the humidifying medium WM, and a slit 72NS is provided at least on the inner surface side of the pipe wall 72NW of the air supply pipe 72N. According to this configuration, when the liquid level of the humidifying medium WM rises above the lower end of the air supply pipe 72N, the humidifying medium WM escapes into the slit 72NS provided in the pipe wall 72NW, so that the infiltration of the humidifying medium WM into the air supply pipe 72N can be suppressed. As a result, the infiltration of the humidifying medium WM into the cap 72 can also be suppressed. Furthermore, since the intrusion of the humidifying medium WM is suppressed without increasing the distance between the lower end of the air supply pipe 72N and the liquid surface of the humidifying medium WM, the size of the supply section 92 can be reduced.

[0060] Furthermore, in the maintenance device 30 according to this embodiment, the slits 72NS are provided along the up-down direction. With this configuration, the humidifying medium WM falls along the slits 72NS, which can facilitate the discharge of the humidifying medium WM from the air supply pipe 72N.

[0061] Furthermore, in the maintenance device 30 according to this embodiment, the slit 72NS penetrates the lower end surface of the pipe wall 72NW. This configuration can promote the discharge of the humidifying medium WM from the air supply pipe 72N.

[0062] Furthermore, in the maintenance device 30 according to this embodiment, the slits 72NS penetrate from the inner surface to the outer surface of the pipe wall 72NW. With this configuration, the humidifying medium WM is discharged in the direction from the inner surface to the outer surface of the pipe wall 72NW, which can promote the discharge of the humidifying medium WM from the air supply pipe 72N. Furthermore, the supply of the humidified air WA is promoted because the humidified air WA is supplied through the slits 72NS.

[0063] Furthermore, the inkjet recording apparatus 1 according to this embodiment includes a plurality of inkjet heads 12 and a maintenance device 30. With this configuration, it is possible to suppress an increase in the viscosity of the ink inside the nozzles 14N.

[0064] The above embodiment may be modified as follows.

[0065] 16 is a perspective view showing the air supply pipe 72N according to the first modified example. In this modified example, the slit 72NS penetrates the lower end of the pipe wall 72NW, but does not penetrate from the inner surface to the outer surface of the pipe wall 72NW, and is provided only on the inner surface side of the pipe wall 72NW. Even with this modified example, when the liquid level of the humidifying medium WM rises above the lower end of the air supply pipe 72N, the humidifying medium WM escapes into the slit 72NS, so that it is possible to suppress the intrusion of the humidifying medium WM into the air supply pipe 72N.

[0066] FIG. 17 is a perspective view showing the air supply pipe 72N according to the second modification. In this modification, the slit 72NS penetrates from the inner surface to the outer surface of the pipe wall 72NW, but does not penetrate the lower end of the pipe wall 72NW. According to this modification, when the liquid level of the humidifying medium WM rises above the lower end of the air supply pipe 72N, the humidified air WA is supplied through the slit 72NS, so that the supply of the humidified air WA can be continued. In this case, the humidified air WA flows above the liquid level, so that the intrusion of the humidifying medium WM into the air supply pipe 72N can be suppressed. In addition, when the liquid level of the humidifying medium WM rises above the lowest part of the slit 72NS, the humidifying medium WM is discharged through the slit 72NS, so that the intrusion of the humidifying medium WM into the air supply pipe 72N can be suppressed.

[0067] The number and intervals of the slits 72NS may be different from those in the above embodiment. For example, the number of slits 72NS may be one, or may be two or more. Furthermore, when multiple slits 72NS are provided, the circumferential intervals of the slits 72NS do not have to be equal. Furthermore, the air supply pipe 72N may have any shape, for example, a square tube shape. [Explanation of symbols]

[0068] 1 Inkjet recording device 12 Inkjet head 14F Nozzle surface 30 Maintenance Equipment 72 Cap 72N supply pipe 72NS Break 72NW pipe wall 92 Supply section

Claims

1. A cap attached to a nozzle surface of the inkjet head; a supply unit that stores a humidifying medium, generates humidified air by passing air through the humidifying medium, and supplies the humidified air to the cap through an air supply pipe that is connected to the cap, A maintenance device characterized in that, inside the supply section, the air supply pipe is arranged in a vertical direction in a space above the liquid level of the humidifying medium, and a slit is provided on at least the inner side of the pipe wall of the air supply pipe.

2. 2. The maintenance device according to claim 1, wherein the slit is provided along the vertical direction.

3. 3. The maintenance device according to claim 2, wherein the slit penetrates a lower end surface of the pipe wall.

4. 4. The maintenance device according to claim 1, wherein the slit penetrates the pipe wall from its inner surface to its outer surface.

5. A plurality of the inkjet heads; An inkjet recording apparatus comprising: the maintenance device according to claim 1 .

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