Maintenance device and inkjet recording device

Abstract

To suppress temperature drop of humidified air.SOLUTION: A maintenance device includes a cap 72 mounted on a nozzle surface 14F of an inkjet head 12, a supply part 92 which communicates with the cap 72, and supplies humidified air WA generated using a humidification medium WM to the cap 72, and a first heating part 92H for heating the supply part 92, wherein the supply part 92 is provided below the cap 72. The cap 72 includes an air supply pipe 72N communicating with the supply part 92. The air supply pipe 72N is formed of a resin.SELECTED DRAWING: Figure 14

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 Art

[0002] In an inkjet recording apparatus using aqueous ink, there is a risk that moisture evaporates from the ink in the nozzles while printing is not being executed, increasing the viscosity and causing ejection failure and clogging. Therefore, conventionally, techniques for suppressing the evaporation of moisture from the ink in the nozzles have been studied. For example, Patent Document 1 describes a device for supplying humidified air into a cap that covers the ejection surface (nozzle surface) of the head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration disclosed in Patent Document 1, in order to enhance the humidifying effect, a heater for heating the tank that generates the humidified air is provided. However, since the distance from the tank to the cap is long, there is a risk that the temperature of the humidified air decreases before it reaches the cap. Also, since the tank is provided at a location remote from the cap, the size of the device increases.

[0005] An object of the present invention is to suppress a decrease in the temperature of humidified air in consideration of the above circumstances.

Means for Solving the Problems

[0006] To solve the above problems, the maintenance device according to the present invention includes a cap attached to the nozzle surface of an inkjet head, a supply unit that communicates with the cap and supplies humidified air generated using a humidifying medium to the cap, and a first heating unit that heats the supply unit. The supply unit is provided below the cap.

[0007] The cap may include an air supply pipe that communicates with the supply unit.

[0008] The air supply pipe may be formed of resin.

[0009] The maintenance device includes a plate-shaped frame that supports the cap. The supply unit includes a tank that stores the humidifying medium. The tank has an opening that opens upward, and the frame may block the opening.

[0010] Further, the inkjet recording apparatus according to the present invention includes a plurality of the inkjet heads and any one of the maintenance devices.

Advantages of the Invention

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

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Mode for Carrying Out the Invention

[0013] Hereinafter, an inkjet recording apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings.

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

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

[0016] The inkjet recording apparatus 1 (see FIG. 2) includes a rectangular parallelepiped main body housing 3. A conveyance unit 7 that adsorbs the sheet and conveys it in the Y direction is provided at the center inside the main body housing 3. An image forming unit 6 that discharges ink to form an image is provided above the conveyance unit 7. A paper feed port 8 for introducing the sheet from the paper feeding device 110 is provided on the right side surface of the main body housing 3. A discharge port 9 for discharging the sheet on which the image is formed to the drying device 120 is provided on the left side surface of the main body housing 3. A conveyance path 10 that reaches the discharge port 9 from the paper feed port 8 through the gap between the conveyance unit 7 and the image forming unit 6 is provided inside the main body housing 3. A registration roller 18 is provided upstream in the conveyance direction Y from the conveyance unit 7.

[0017] The conveying unit 7 includes an endless conveyor belt 21 and a suction unit 24. The conveyor belt 21 has a number of ventilation holes (not shown) and is wound around a driving roller 25 and a driven roller 22. The upper surface of the suction unit 24 has a number of ventilation holes (not shown) and is in contact with the inner surface of the conveyor belt 21. By the suction unit 24 sucking air through the ventilation holes of the conveyor belt 21 and the ventilation holes of the suction unit 24, the sheet is adsorbed to the conveyor belt 21. The driving roller 25 is driven in the counterclockwise direction by a driving unit (not shown) including a motor and a reduction gear, so that the conveyor belt 21 rotates in the counterclockwise direction, and the sheet adsorbed to the conveyor belt 21 is conveyed in the Y direction.

[0018] The image forming unit 6 includes a plurality (four in this embodiment) of head units 11. The head unit 11 (see FIGS. 3 and 4) includes one or more (three in this embodiment) inkjet heads 12. Ink containers 20 filled with black, cyan, magenta, and yellow inks are respectively connected to each head unit 11.

[0019] The inkjet head 12 (see FIG. 6) includes a rectangular parallelepiped housing 12H having a longitudinal direction in 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 a discharge port 14A provided on the nozzle surface 14F which is the lower surface of the nozzle plate 14. The diaphragm 14V also serves as a part of the inner wall of the branch flow path 14B. A pressurizing element 14Z is provided on the diaphragm 14V. As the pressurizing element 14Z, a piezoelectric element, an electrostatic actuator, a heater, etc. are used. A drive circuit 12D for driving the pressurizing element 14Z is connected to the pressurizing element 14Z.

[0020] The control unit 2 (see Fig. 2) includes an arithmetic unit and a storage unit (not shown). The arithmetic 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 arithmetic unit reads and executes the control program stored in the storage unit to perform various processes. Note that the control unit 2 may be realized by an integrated circuit that does not use software.

[0021] A display operation unit 19 is provided at 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 causes the display panel to display a screen representing the operation menu, status, etc. of the inkjet recording apparatus 1, and controls each part of the inkjet recording apparatus 1 according to the operations detected by the touch panel and the keypad.

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

[0023] [Maintenance Device] 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, hereinafter, one head unit 11 and one maintenance device 30 provided to the right of it will be described.

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

[0025] The maintenance device 30 (see FIG. 3) is provided on the side (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) includes the same number of caps 72 (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. The three caps 72 are attached to the upper surface of the plate-shaped frame body 71 via a pedestal portion 71M (see FIGS. 8 to 11). Two caps 72 are arranged in the front and rear directions on the right side of the center of the frame body 71 in the left-right direction, and one cap 72 is arranged on the left side. One cap 72 on the left side is arranged at the middle position in the front-rear direction between the two caps 72 on the right side.

[0027] [Wipe Unit] The wipe unit 32 (see FIGS. 3 and 4) includes a waste liquid tray 81 and a cleaning member 82. The waste liquid tray 81 includes the same number of recesses 81U as the inkjet head 12 included in the head unit 11. The plurality of recesses 81U are arranged staggeredly in the same manner as the inkjet head 12. The cleaning member 82 is provided in each of the recesses 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 wipe unit 32 is placed on the cap unit 31. A cleaning liquid supply device 13 (see FIG. 6) for supplying a cleaning liquid to the nozzle surface 14F is provided in the head unit 11.

[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 raises and lowers the head unit 11 between an image forming position and a retracted position. The image forming position (see FIG. 7(A)) is a position where the distance between the conveyance path 10 (the upper surface of the conveyance belt 21) where 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 retracted position (see FIG. 7(B)) is a position where the head unit 11 does not interfere with the wipe unit 32 when the cap unit 31 and the wipe unit 32 are slid using a cap slide device 34 described later. The retracted 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 before and after the frame 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] [Wiper lifting device] The wiper lifting device 35 (see FIG. 4) is provided before and after the waste liquid tray 81 of the wiper unit 32. The wiper lifting device 35 is composed of, for example, a ball screw, a belt drive device, etc. The wiper lifting device 35 raises and lowers the wiper unit 32 between a contact position (see FIG. 7(B)) where the waste liquid tray 81 contacts the cap 72 and a separation position (see FIG. 7(E)) where the waste liquid tray 81 is separated from the cap 72 by a predetermined distance.

[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 the I-I cross-section of FIG. 9. FIG. 11 is an exploded view showing the cap unit 31. FIG. 12 is a diagram showing the flow of air A and 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 humidified air WA inside the cap 72. FIG. 15 is an exploded view showing a portion above the frame 71 of the cap unit 31.

[0032] The maintenance device 30 according to this embodiment includes a plurality of caps 72 attached to the nozzle surface 14F of the inkjet head 12, an air supply port 72NA and an exhaust port 72EA provided in each of the plurality of caps 72, one recovery unit 94 that recovers air A from the exhaust ports 72EA of all the caps 72, and a plurality of supply units 92 provided for each cap 72 that supply humidified air WA obtained by humidifying the air A recovered by the recovery unit 94 to the air supply port 72NA. The plurality of supply units 92 are arranged around one recovery unit 94. In each of the plurality of caps 72, the exhaust port 72EA is provided on the side of the recovery unit 94, and the air supply port 72NA is provided on the side of the supply unit 92.

[0033] The plurality of 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 (for example, the front-rear direction). The third cap 723 is arranged at an intermediate position 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. The exhaust port 72EA of the first cap 721 is provided on the side of the second cap 722, and the exhaust port 72EA of the second cap 722 is provided on the side of the first cap 721.

[0034] [Cap] The cap 72 (see FIGS. 8 to 10) is formed in a box shape that opens upward. The cap 72 includes a substantially rectangular bottom portion 72B having a longitudinal direction in the front-rear direction, and side wall portions 72W that stand upright upward from the edges of the bottom portion 72B. The side wall portions 72W are formed of a flexible material such as rubber. The air supply port 72NA and the exhaust port 72EA are provided in the bottom portion 72B. In the caps 72 on the right rear side and the left side, the air supply port 72NA is provided on the rear side, and the exhaust port 72EA is provided on the front side. In the cap 72 on the right front side, the air supply port 72NA is provided on the front side, and the exhaust port 72EA is provided on the rear side.

[0035] The three caps 72 are arranged staggeredly. The first cap 721 is arranged at 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 supply 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 supply 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 supply port 72NA may be provided on the rear side.

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

[0037] In other words, the three supply units 92 are arranged around one recovery unit 94. In each of the three caps 72, the exhaust port 72EA is provided on the side of the recovery unit 94, and the air supply port 72NA is provided on the side of the supply unit 92. Also, in other words, all the exhaust ports 72EA overlap the recovery unit 94 in the vertical direction, and in each of the plurality of caps 72, the air supply port 72NA overlaps the supply unit 92 in the vertical direction.

[0038] The tank 92T has an opening 92A that opens upward (see FIG. 11). The tank 94T has an opening 94A that opens upward. The tank 92T and the tank 94T are joined to the lower surface of the frame body 71. That is, the opening 92A and the opening 94A are blocked by the frame body 71. In other words, the frame body 71 also serves as the ceiling of the tank 92T and the tank 94T.

[0039] An air supply pipe 72N (see FIG. 10) that connects the cap 72 and 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 and the recovery unit 94 is connected to the exhaust port 72EA of each cap 72. That is, three caps 72 communicate with the recovery unit 94.

[0040] The frame body 71 has an air supply port 71NA below the air supply port 72NA and an exhaust port 71EA below the exhaust port 72EA. The air supply pipe 72N penetrates the air supply port 71NA. The exhaust pipe 72E penetrates the exhaust port 71EA.

[0041] The air pump 95 is connected to the recovery unit 94 by a recovery flow path 95E (see FIGS. 8, 9, and 11) and is connected to all the supply units 92 by a supply flow path 95N. The air pump 95 recovers the air A with a reduced water vapor pressure from the recovery unit 94 via the recovery flow path 95E, and supplies the recovered air A to all the supply units 92 via the supply flow path 95N (see FIG. 12).

[0042] All the supply units 92 are connected to the sub-tank 93 via a communication pipe 92C (see FIGS. 10, 11, and 12). A tank 93T and a pump 93P are connected to the sub-tank 93. A humidification medium WM (see FIG. 14) is stored in the tank 93T. The humidification medium WM is, for example, water, but any liquid containing water may be used. The pump 93P supplies the humidification medium WM from the tank 93T to the sub-tank 93.

[0043] The sub-tank 93 is provided with a sensor 93S (see FIGS. 8, 9, 11, and 12) for detecting the amount of the humidifying medium WM in the sub-tank 93. The sensor 93S detects, for example, the height of the liquid level in the sub-tank 93. The supply unit 92 is provided with a first heating unit 92H (see FIG. 10) for heating the supply unit 92. The cap 72 is provided with a second heating unit 72H for heating the cap 72. The supply unit 92 is provided with a sensor 92S for measuring the temperature inside the supply unit 92. The cap 72 is provided with a sensor 72S for measuring the temperature inside the cap 72. The recovery unit 94 is provided with a sensor 94S for measuring at least one of the temperature and humidity inside the recovery unit 94.

[0044] 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. That is, the waste liquid tray 81 is in contact with the cap 72. The control unit 2 executes the following processes at a predetermined timing. The predetermined timing is, for example, the timing when an increase in the viscosity of the ink in the nozzle 14N is expected, specifically, when a period during which no image forming job is executed continues for a predetermined period.

[0045] 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 until the nozzle surface 14F contacts the cleaning member 82 (see FIG. 7(D)).

[0046] Next, the control unit 2 forcibly discharges a predetermined amount of ink from the inkjet head 12 (purge process), supplies a cleaning liquid to the nozzle surface 14F, and slides the cleaning member 82 along the nozzle surface 14F (wipe process). Then, the ink remaining on the nozzle surface 14F is diluted with the cleaning liquid, and the waste liquid containing the ink and the cleaning liquid is scraped off by the cleaning member 82 and drops into the waste liquid tray 81.

[0047] 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 slide device 34 to slide the cap unit 31 and the wipe unit 32 to the home position (see FIG. 7(B)).

[0048] 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 at the home position, and only the cap unit 31 slides to the maintenance position.

[0049] Next, the control unit 2 operates the head lifting device 11L to lower the head unit 11 until 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.

[0050] Next, the control unit 2 humidifies the inside of the cap 72. The control unit 2 monitors the measured value by the sensor 93S and maintains the height of the liquid level in the sub-tank 93 within a predetermined range. Specifically, when the measured value of the liquid level falls below the predetermined range, a predetermined amount of the humidifying medium WM is supplied from the tank 93T to the sub-tank 93 using the pump 93P. Since the sub-tank 93 communicates with the supply unit 92 through the communication pipe 92C, the height of the liquid level of the humidifying medium WM is uniform in the sub-tank 93 and all the supply units 92.

[0051] An air pump 95 (see FIG. 12) collects air A with a reduced water vapor pressure from the collection unit 94 via a recovery flow path 95E, and supplies all of the collected air A to all the supply units 92 via a supply flow path 95N. The end of the supply flow path 95N on the supply unit 92 side is disposed below the liquid level 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 until the bubbles B float to the liquid surface. Further, since the humidifying medium WM in the supply unit 92 is heated by the first heating unit 92H, water vapor is likely to be generated. Therefore, the space above the liquid level 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. Note that the air pump 95 may continuously or intermittently collect and supply the air A.

[0052] On the other hand, in the collection unit 94, a negative pressure is generated because the air A is sucked by the air pump 95. Therefore, in the cap 72, an air flow of the humidified air WA from the air supply port 72NA toward the exhaust port 72EA is generated. Further, since the humidified air WA supplied to the cap 72 is heated by the first heating unit 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 contacts the ink in the nozzle 14N, and an increase in the viscosity of the ink is suppressed.

[0053] In addition to the above control, the control unit 2 controls the temperature of each part. 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 the ink in the nozzle 14N). Also, 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 recovery unit 94 is provided with a sensor 94S that measures at least one of the temperature and humidity inside the recovery unit 94.

[0054] The control unit 2 monitors the measured value 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 inside the nozzle 14N of the inkjet head 12. In that case, the humidifying effect on the ink inside the nozzle 14N cannot be obtained. On the other hand, in the present embodiment, humidified air WA with a higher humidity than inside the nozzle 14N of the inkjet head 12 is supplied.

[0055] Also, the control unit 2 monitors the measured 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 decreases inside the cap 72. When the temperature of the humidified air WA drops below the dew point, condensation occurs and the humidity inside the cap 72 decreases, and the humidifying effect cannot be obtained. On the other hand, in the present embodiment, since the temperature of the humidified air WA does not decrease inside the cap 72, there is no possibility that the humidity inside the cap 72 decreases due to condensation.

[0056] When executing an image forming job, 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 wiper lifting device 35 to lower the wiper 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.

[0057] According to the maintenance device 30 according to the present embodiment described above, a cap 72 attached to the nozzle surface 14F of the inkjet head 12, a supply unit 92 that communicates with the cap 72 and supplies humidified air WA generated using a humidifying medium WM to the cap 72, and a first heating unit 92H that heats the supply unit 92 are provided. The supply unit 92 is provided below the cap 72. According to this configuration, since the first heating unit 92H heats the supply unit 92, the water vapor pressure of the humidified air WA can be increased compared to the case at normal temperature. However, if the temperature of the humidified air WA decreases before the humidified air WA reaches the cap 72 from the supply unit 92, the water vapor pressure of the humidified air WA decreases and the humidifying effect on the nozzle surface 14F deteriorates. In the present embodiment, since the supply unit 92 is provided below the cap 72, the distance between the supply unit 92 and the cap 72 can be shortened compared to the case where the supply unit 92 is provided at a position other than below the cap 72. Therefore, according to the present embodiment, a decrease in the temperature of the humidified air WA can be suppressed.

[0058] Further, according to the maintenance device 30 according to the present embodiment, the cap 72 includes an air supply pipe 72N that communicates with the supply unit 92. According to this configuration, since the air supply pipe 72N can be shortened, a decrease in the temperature of the humidified air WA can be suppressed.

[0059] Further, according to the maintenance device 30 according to the present embodiment, the air supply pipe 72N is formed of resin. According to this configuration, since heat hardly escapes from the air supply pipe 72N, a decrease in the temperature of the humidified air WA can be suppressed.

[0060] Further, according to the maintenance device 30 according to the present embodiment, it includes a plate-shaped frame body 71 that supports the cap 72, the supply unit 92 includes a tank 92T that stores the humidification medium WM, the tank 92T includes an opening 92A that opens upward, and the frame body 71 closes the opening 92A. According to this configuration, since the frame body 71 also serves as the ceiling of the tank 92T, the vertical size of the cap unit 31 can be suppressed. Also, the number of parts can be suppressed.

[0061] Further, according to the inkjet recording apparatus 1 according to the present embodiment, it includes a plurality of inkjet heads 12 and a maintenance device 30. According to this configuration, an increase in the viscosity of the ink in the nozzle 14N can be suppressed.

[0062] The above embodiment may be modified as follows.

[0063] FIG. 16 is a cross-sectional view showing a cap unit 31 according to a modification. In the above embodiment, an example in which the cap 72 is attached to the upper surface of the frame body 71 via the pedestal portion 73 is shown, but the cap 72 may be attached to the upper surface of the frame body 71 without passing through the pedestal portion 73. According to this configuration, the vertical size of the cap unit 31 can be suppressed.

[0064] Also, since the air supply port 72NA and the air supply port 71NA are directly connected, the air supply pipe 72N is unnecessary. Also, since the exhaust port 72EA and the exhaust port 71EA are directly connected, the exhaust pipe 72E is unnecessary. That is, since the pedestal portion 73, the air supply pipe 72N, and the exhaust pipe 72E are unnecessary, the number of parts can be suppressed.

[0065] Also, the bottom portion 72B of the cap 72 may be omitted, and the side wall portion 72W may be directly attached to the frame body 71. According to this configuration, the vertical size of the cap unit 31 can be further suppressed. Also, the number of parts can be further suppressed.

Explanation of Reference Numerals

[0066] 1 Inkjet recording device 12 Inkjet head 14F Nozzle surface 30 Maintenance device 71 Frame 72 Cap 72N Air supply pipe 92 Supply unit 92A Opening 92H First heating unit 92T Tank WA Humidified air WM Humidifying medium

Claims

1. A cap attached to the nozzle surface of an inkjet head, a supply unit that communicates with the cap and supplies humidified air generated using a humidifying medium to the cap, and a first heating unit that heats the supply unit, wherein the supply unit is provided below the cap. A maintenance device characterized by this.

2. The maintenance device according to claim 1, wherein the cap includes an air supply pipe that communicates with the supply unit.

3. The maintenance device according to claim 2, wherein the air supply pipe is formed of resin.

4. It includes a plate-shaped frame that supports the cap, the supply unit includes a tank that stores the humidifying medium, the tank includes an opening that opens upward, and the frame closes the opening. The maintenance device according to any one of claims 1 to 3, characterized by this.

5. A plurality of the inkjet heads, and the maintenance device according to claim 1. An inkjet recording device characterized by this.

Images