Maintenance device and inkjet recording apparatus

Abstract

To stabilize supply of humidified air to a nozzle surface.SOLUTION: A maintenance device includes: a cap 72 mounted on a nozzle surface of an ink jet head; an air supply port provided in the cap 72; and a suppression member 74 provided at least between the air supply port and the nozzle surface, having a first gap between the air supply port and the suppression member, and having a second gap between the nozzle surface and the suppression member, where the suppression member 74 includes one or more through-hole 74H provided at a place not facing the air supply port of the suppression member 74 and penetrating from the air supply port side to the nozzle surface side, and a recessed portion 74A provided on an upper surface of the suppression member 74 and recessed from an edge portion 74HE of the through-hole 74H.SELECTED DRAWING: Figure 21

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, during periods when printing is not being executed, moisture may evaporate from the ink within the nozzles, causing the viscosity to increase and potentially resulting in ejection failures and clogging. Therefore, conventionally, techniques for suppressing the evaporation of moisture from the ink within the nozzles have been studied. For example, Patent Documents 1 to 4 describe devices that supply humidified air into a cap that covers the ejection surface (nozzle surface) of the head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configurations described in Patent Documents 1 to 4, since the humidified air directly hits the nozzle surface, condensation may occur on the nozzle surface, and ink may be pulled by the condensation and exit from the nozzles. Further, although the humidified air is supplied from an air supply port provided in the cap, as the distance from the air supply port increases, it becomes more difficult for the humidified air to reach the nozzle surface, and the humidifying effect decreases. Therefore, there is a problem that the ejection performance becomes non-uniform and the density of the image deviates from the image data.

[0005] In view of the above circumstances, an object of the present invention is to stabilize the supply of humidified air to the nozzle surface.

Means for Solving the Problems

[0006] To solve the above problems, a maintenance device according to the present invention includes a cap attached to the nozzle surface of an inkjet head, an air supply port provided in the cap, and at least provided between the air supply port and the nozzle surface, having a first gap with the air supply port and a second gap with the nozzle surface, and a suppressing member, and the suppressing member is provided at a location not facing the air supply port of the suppressing member, and includes one or more through holes penetrating from the air supply port side to the nozzle surface side, and a recess provided on the upper surface of the suppressing member and recessed more than the edge of the through hole.

[0007] The cap includes an exhaust port, the through holes are provided at a plurality of locations along the direction from the air supply port side to the exhaust port side, and the recess may be formed in a groove shape along the direction from the air supply port side to the exhaust port side.

[0008] A plurality of rows of the through holes are arranged along the direction from the air supply port side to the exhaust port side, and the recess may be arranged between the rows of the through holes.

[0009] Two of the recesses may be arranged between two rows of the through holes.

[0010] The maintenance device may include a storage portion for storing the liquid flowing along the recess.

[0011] The storage portion may be provided on the upper surface of the suppressing member and may be formed deeper than the recess.

[0012] At least one end of the recess penetrates the end surface of the suppressing member, and the storage portion may be provided at the bottom of the cap.

[0013] The inkjet recording apparatus according to the present invention includes the inkjet head and the maintenance device.

Advantages of the Invention

[0014] According to the present invention, the supply of humidified air to the nozzle surface can be stabilized.

Brief Description of the Drawings

[0015]

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Embodiments for Carrying Out the Invention

[0016] [First Embodiment] Hereinafter, the inkjet recording apparatus 1 according to the first embodiment of the present invention will be described with reference to the drawings.

[0017] 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 wipe 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 paper surface in FIG. 2, and the left and right directions are described based on the direction when the inkjet recording apparatus 1 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate up, down, left, right, front, and rear, respectively.

[0018] 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.

[0019] The inkjet recording apparatus 1 (see Fig. 2) includes a rectangular parallelepiped main body housing 3. In the central part inside the main body housing 3, a conveying unit 7 for sucking and conveying a sheet in the Y direction is provided. Above the conveying unit 7, an image forming unit 6 for discharging ink to form an image is provided. On the right side surface of the main body housing 3, a paper feed port 8 for introducing a sheet from a paper feeding device 110 is provided. On the left side surface of the main body housing 3, a discharge port 9 for discharging the sheet on which an image is formed to a drying device 120 is provided. Inside the main body housing 3, a conveyance path 10 is provided from the paper feed port 8 through the gap between the conveying unit 7 and the image forming unit 6 to the discharge port 9. A registration roller 18 is provided on the upstream side in the conveying direction Y of the conveying unit 7.

[0020] The conveying unit 7 includes an endless conveying belt 21 and a suction unit 24. The conveying 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 conveying belt 21. By the suction unit 24 sucking air through the ventilation holes of the conveying belt 21 and the ventilation holes of the suction unit 24, the sheet is adsorbed to the conveying 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 conveying belt 21 rotates in the counterclockwise direction, and the sheet adsorbed to the conveying belt 21 is conveyed in the Y direction.

[0021] 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. An ink container 20 filled with black, cyan, magenta, and yellow inks is connected to each head unit 11, respectively.

[0022] 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 large 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 a 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, or the like is used. A drive circuit 12D for driving the pressurizing element 14Z is connected to the pressurizing element 14Z.

[0023] 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 performs various processes by reading and executing a control program stored in the storage unit. Note that the control unit 2 may be realized by an integrated circuit that does not use software.

[0024] 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 causes the display panel to display a screen representing an operation menu, status, etc. of the inkjet recording apparatus 1, and controls each part of the inkjet recording apparatus 1 according to operations detected by the touch panel and the keypad.

[0025] 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 or the like, the paper feeding device 110 feeds a sheet into the conveyance path 10 through the paper feed port 8, and the registration roller 18 whose rotation has been stopped corrects the skew of the sheet. When the registration roller 18 feeds 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.

[0026] [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 thereof will be described.

[0027] 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.

[0028] 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.

[0029] [Cap Unit] The cap unit 31 (see FIGS. 3 and 5) includes the same number of caps 72 as the inkjet head 12 provided in the head unit 11 (in this embodiment, three). The three caps 72 are arranged in a staggered pattern, similar to the inkjet head 12. The three caps 72 are attached to the upper surface of the plate-shaped frame 71 via the pedestal portion 71M (see FIGS. 8 to 11). Two caps 72 are arranged in the front and rear on the right side of the center of the frame 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.

[0030] [Wiper unit] The wiper 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 provided in the head unit 11. The plurality of recesses 81U are arranged in a staggered pattern, similar to 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) for sliding the cleaning member 82 along the nozzle surface 14F. The waste liquid tray 81 is placed on the plurality of caps 72. In other words, the wiper unit 32 is placed on the cap unit 31. A cleaning liquid supply device 13 (see FIG. 6) for supplying cleaning liquid to the nozzle surface 14F is provided in the head unit 11.

[0031] [Head lifting device] The head lifting device 11L (see FIG. 4) is provided before and after 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 the image forming position and the 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 wiper unit 32 when the cap unit 31 and the wiper unit 32 are slid using the cap slide device 34 described later. The retracted position is the upper limit position of the lifting range of the head unit 11.

[0032] [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 between the home position and the 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.

[0033] [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 the contact position where the waste liquid tray 81 contacts the cap 72 (see FIG. 7(B)) and the separation position where the waste liquid tray 81 is separated from the cap 72 by a predetermined distance (see FIG. 7(E)).

[0034] 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 in 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 in the cap 72.

[0035] The maintenance device 30 according to the present 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 recovery unit 94 side, and the air supply port 72NA is provided on the supply unit 92 side.

[0036] 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 second cap 722 side, and the exhaust port 72EA of the second cap 722 is provided on the first cap 721 side.

[0037] [Cap] The cap 72 (see FIGS. 8 to 10) is formed in a box shape that opens upward. The cap 72 includes a generally rectangular bottom portion 72B with its 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. An air supply port 72NA and an 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.

[0038] The three caps 72 are arranged in a staggered pattern. 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, the exhaust port 72EA is provided on the front side, and the air supply port 72NA is provided on the rear side. In the second cap 722, the exhaust port 72EA is provided on the rear side, and the air supply port 72NA is provided on the front side. Note that in the second cap 722, the exhaust port 72EA may be provided on the front side, and the air supply port 72NA may be provided on the rear side.

[0039] [Supply section, recovery section] Below the frame body 71 (see FIGS. 8, 11 to 13), the same number (three in this embodiment) of supply sections 92 as the caps 72 and one recovery section 94 are provided. The supply section 92 has a tank 92T. The recovery section 94 has a tank 94T. The supply section 92 and the recovery section 94 are supported by the frame body 91. Each supply section 92 is arranged below the air supply port 72NA of each cap 72. The recovery section 94 has a shape that overlaps all the exhaust ports 72EA in a plan view and is arranged below all the exhaust ports 72EA.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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).

[0044] 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 humidifying medium WM (see FIG. 14) is stored in the tank 93T. The humidifying medium WM is, for example, water, but any liquid containing water may be used. The pump 93P supplies the humidifying medium WM from the tank 93T to the sub-tank 93.

[0045] 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.

[0046] 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 wiper 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, and specifically, when a period during which no image forming job is executed continues for a predetermined period.

[0047] 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 wiper unit 32 is placed on the cap unit 31, the wiper 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)).

[0048] Next, the control unit 2 forces the ejection of a predetermined amount of ink from the inkjet head 12 (purging process), supplies the cleaning liquid to the nozzle surface 14F, and slides the cleaning member 82 along the nozzle surface 14F (wiper 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.

[0049] 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 wiper unit 32 to the home position (see Fig. 7(B)).

[0050] Next, the control unit 2 operates the wiper lifting device 35 to raise the wiper 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 wiper unit 32 is separated from the cap unit 31, the wiper unit 32 remains in the home position, and only the cap unit 31 slides to the maintenance position.

[0051] 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)). Thus, the cap 72 is attached to the nozzle surface 14F.

[0052] 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.

[0053] An air pump 95 (see FIG. 12) recovers air A with a reduced water vapor pressure from the recovery section 94 via a recovery flow path 95E, and supplies all of the recovered air A to all of the supply sections 92 via a supply flow path 95N. The end of the supply flow path 95N on the supply section 92 side is disposed below the liquid level of the humidifying medium WM (see FIG. 14). Therefore, in the supply section 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 section 92 is heated by the first heating section 92H, water vapor is likely to be generated. Therefore, the space above the liquid level of the supply section 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 recover and supply air A.

[0054] On the other hand, in the recovery section 94, since air A is sucked by the air pump 95, a negative pressure is generated. 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 section 92H, convection occurs in the cap 72, and the high-temperature humidified air WA is supplied to the nozzle surface 14F. Thus, the humidified air WA contacts the ink in the nozzle 14N, and an increase in the viscosity of the ink is suppressed.

[0055] 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) for measuring 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) 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.

[0056] 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 becomes 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 having a higher humidity than inside the nozzle 14N of the inkjet head 12 is supplied.

[0057] 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 becomes 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.

[0058] 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.

[0059] Incidentally, since the humidified air WA flowing into the cap 72 through the air supply pipe 72N rises toward the nozzle surface 14F, the humidified air WA directly hits the nozzle surface 14F. In such a case, condensation may occur on the nozzle surface 14F, and ink may be pulled by the condensation and come out of the nozzle 14N. The dropped ink may accumulate in the cap 72, obstruct the flow of the humidified air WA, or clog the air supply pipe 72N.

[0060] Therefore, the maintenance device 30 according to the present embodiment includes a suppression member 73. Fig. 15 is a cross-sectional view showing the cap unit 31 provided with the suppression member 73. Fig. 16 is a plan view showing the cap 72 provided with the suppression member 73. Note that Fig. 15 is a cross-sectional view taken along the II-II section of Fig. 16.

[0061] The maintenance device 30 according to the present embodiment includes a cap 72 attached to the nozzle surface 14F of the inkjet head 12, an air supply port 72NA provided in the cap 72, and a suppression member 73 provided at least between the air supply port 72NA and the nozzle surface 14F, having a first gap G1 between the air supply port 72NA and a second gap G2 between the nozzle surface 14F. Specifically, it is as follows.

[0062] The suppression member 73 is provided above the air supply port 72NA. The suppression member 73 is a plate-shaped member with the vertical direction as the thickness direction and is formed of resin. The suppression member 73 is supported by a support column 72P provided at the bottom 72B of the cap 72. The dimensions of the suppression member 73 in the front-rear direction and the left-right direction are larger than those of the air supply port 72NA. The suppression member 73 is provided so as to cover at least the entire air supply port 72NA in plan view. A first gap G1 is provided between the air supply port 72NA and the lower surface of the suppression member 73. A second gap G2 is provided between the nozzle surface 14F and the upper surface of the suppression member 73.

[0063] A part WA1 (see FIG. 15) of the humidified air flowing into the cap 72 from the air supply port 72NA flows forward from the first gap G1 and is sucked into the exhaust port 72EA. Another part WA2 of the humidified air circulates from the first gap G1 through the rear of the suppression member 73 into the second gap G2, flows forward from the second gap G2, and is sucked into the exhaust port 72EA. Another part WA3 (see FIG. 16) of the humidified air flows forward from the left and right spaces of the suppression member 73 and is sucked into the exhaust port 72EA. That is, since the humidified air WA flows along the lower surface and the upper surface of the suppression member 73 above the air supply port 72NA, the humidified air WA does not directly hit the nozzle surface 14F above the air supply port 72NA. As a result, the occurrence of dew condensation on the nozzle surface 14F is suppressed, and it is possible to prevent the ink from being pulled by the dew condensation and coming out of the nozzles 14N.

[0064] The reason why the suppression member 73 is formed of resin is as follows. There is a possibility that dew condensation may occur on the suppression member 73 because the suppression member 73 takes heat from the humidified air WA. In particular, in the present embodiment, since the first heating unit 92H is provided in the supply unit 92 to increase the amount of water vapor in the humidified air WA, dew condensation is likely to occur. When dew condensation occurs, the water vapor pressure of the humidified air WA decreases, so that the humidifying effect on the ink in the nozzles 14N decreases. To suppress dew condensation, it is desirable to form the suppression member 73 of a material with a low thermal conductivity. Generally, since resin has a lower thermal conductivity than metal, it is suitable as the material of the suppression member 73.

[0065] 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, an air supply port 72NA provided in the cap 72, and at least provided between the air supply port 72NA and the nozzle surface 14F, having a first gap G1 between the air supply port 72NA, and a suppression member 73 having a second gap G2 between the nozzle surface 14F. According to the present embodiment, it is possible to prevent the humidified air WA from directly hitting the nozzle surface 14F.

[0066] Further, according to the maintenance device 30 according to the present embodiment, the suppression member 73 is formed of resin. According to the present embodiment, condensation of the humidified air WA can be suppressed.

[0067] Further, according to the inkjet recording apparatus 1 according to the present embodiment, an inkjet head 12 and a maintenance device 30 are provided. According to the present embodiment, an increase in the viscosity of the ink in the nozzles 14N of 12 can be suppressed.

[0068] [Second Embodiment] FIG. 17 is a cross-sectional view showing a cap unit 31 including a suppression member 74 according to the second embodiment. FIG. 18 is a plan view showing a cap 72 including the suppression member 74 according to the second embodiment.

[0069] The suppression member 74 is provided along the direction from the air supply port 72NA side to the exhaust port 72EA side (in the present embodiment, the front-rear direction). Specifically, the suppression member 74 is a rectangular plate-like member having the front-rear direction as the longitudinal direction. The suppression member 74 is supported by a support column 72P provided at the bottom 72B of the cap 72. The rear end portion of the suppression member 74 is disposed above the air supply port 72NA. The front end portion of the suppression member 74 is located behind the exhaust port 72EA. A first gap G1 is provided between the air supply port 72NA and the lower surface of the suppression member 74. A second gap G2 is provided between the nozzle surface 14F and the upper surface of the suppression member 74.

[0070] The suppression member 74 includes a through hole 74H that penetrates from the air supply port 72NA side to the nozzle surface 14F side at a position not facing the air supply port 72NA. The through holes 74H are provided at a plurality of positions (three positions in this embodiment) along the front-rear direction.

[0071] A part WA1 of the humidified air (see FIG. 15) that has flowed into the cap 72 from the air supply port 72NA flows forward through the first gap G1 and is sucked into the exhaust port 72EA. Another part WA2 of the humidified air circulates from the first gap G1 through the rear of the suppression member 74 into the second gap G2, flows forward through the second gap G2, and is sucked into the exhaust port 72EA. Another part WA3 of the humidified air (see FIG. 16) flows forward through the left and right spaces of the suppression member 73 and is sucked into the exhaust port 72EA. That is, since the humidified air WA flows along the lower surface and the upper surface of the suppression member 74 over a wider range compared to the first embodiment, the humidified air WA can be supplied to the nozzle surface 14F over a wider range compared to the first embodiment.

[0072] Also, a part WA4 of the humidified air flowing through the first gap G1 to the exhaust port 72EA flows from the first gap G1 to the second gap G2 through the through hole 74H, so that it is possible to compensate for the insufficient supply of the humidified air WA by the suppression member 74. Further, since the humidified air WA is supplied to the nozzle surface 14F away from the air supply port 72NA through the through hole 74H, the uniformity of humidification with respect to the nozzle surface 14F is improved.

[0073] According to the maintenance device 30 according to the present embodiment described above, the cap 72 includes the exhaust port 72EA, and the suppression member 74 is provided along the direction from the air supply port 72NA side to the exhaust port 72EA side. According to the present embodiment, the humidified air WA can be supplied to the nozzle surface 14F over a wide range along the direction from the air supply port 72NA side to the exhaust port 72EA side.

[0074] Further, according to the maintenance device 30 according to the present embodiment, the suppression member 74 includes a through hole 74H that penetrates from the air supply port 72NA side to the nozzle surface 14F side at a position not facing the air supply port 72NA. According to the present embodiment, it is possible to compensate for the insufficient supply of the humidified air WA by the suppression member 74.

[0075] Further, according to the maintenance device 30 according to the present embodiment, the cap 72 includes an exhaust port 72EA, and the through holes 74H are provided at a plurality of locations along the direction from the air supply port 72NA side to the exhaust port 72EA side. According to the present embodiment, it is possible to improve the uniformity of humidification with respect to the nozzle surface 14F.

[0076] [Third Embodiment] In the second embodiment (see FIG. 17), since the end portion of the suppression member 74 on the exhaust port 72EA side is located behind the exhaust port 72EA, there is a problem that it is difficult to supply the humidified air WA to the region R in front of the end portion of the suppression member 74 on the exhaust port 72EA side on the nozzle surface 14F.

[0077] FIG. 19 is a cross-sectional view showing a cap unit 31 including a suppression member 74 according to the third embodiment. FIG. 20 is a plan view showing a cap 72 including a suppression member 74 according to the third embodiment.

[0078] In the present embodiment, the end portion of the suppression member 74 on the exhaust port 72EA side faces the exhaust port 72EA. According to the present embodiment, since the humidified air WA flowing forward through the second gap G2 wraps around from the front of the suppression member 74 into the first gap G1 and is sucked into the exhaust port 72EA, it is possible to supply the humidified air WA to the nozzle surface 14F on the exhaust port 72EA side as well. Therefore, according to the present embodiment, it is possible to improve the uniformity of humidification with respect to the nozzle surface 14F.

[0079] [Fourth Embodiment] Ink may fall onto the upper surface of the suppression member 74. For example, when a purge process is performed due to a malfunction with the cap 72 attached to the nozzle surface 14F, or when ink remains on the nozzle surface 14F after a wiping process because of an error in the vertical positioning of the wipe unit 32. In the second and third embodiments, if the dropped ink flows into the through-hole 74H, there is a risk that the through-hole 74H will become clogged and it will be difficult for the humidified air WA to pass through. Therefore, in this embodiment, a recess 74A that is recessed more than the edge 74HE of the through-hole 74H is provided on the upper surface of the suppression member 74.

[0080] FIG. 21 is a perspective view showing the cap 72 provided with the suppression member 74. FIG. 22 is a plan view showing the suppression member 74. FIG. 23 is a cross-sectional view showing the V-V cross-section of FIG. 22. FIG. 24 is a cross-sectional view showing the VI-VI cross-section of FIG. 22.

[0081] The through-holes 74H (see FIGS. 21 and 22) are provided at a plurality of locations (in this embodiment, four locations) along the direction from the air supply port 72NA side to the exhaust port 72EA side (in this embodiment, the front-rear direction). Also, a plurality of rows (in this embodiment, two rows) of through-holes 74H are arranged along the front-rear direction.

[0082] The recess 74A (see FIGS. 21 and 22) is formed in a groove shape along the front-rear direction. Also, the recess 74A is arranged between the rows of the through-holes 74H. In this embodiment, two recesses 74A are arranged between the two rows of through-holes 74H.

[0083] The portion of the upper surface of the suppression member 74 excluding the through-holes 74H, the recess 74A, and the storage portion 74B is substantially horizontal, and this portion is referred to as the horizontal portion 74C. The edge 74HE of the through-hole 74H (see FIGS. 21 to 23) is a part of the horizontal portion 74C. The recess 74A is recessed more than the edge 74HE of the through-hole 74H.

[0084] The suppressing member 74 includes a storage portion 74B that stores the liquid flowing along the recess 74A. The storage portion 74B is provided on the upper surface of the suppressing member 74 and is formed deeper than the recess 74A. The storage portion 74B is generally circular when viewed from above. The storage portion 74B is continuous with the two recesses 74A. As an example, in the present embodiment, the storage portion 74B is continuous with the front end portions of the two recesses 74A.

[0085] Next, the behavior of the ink that has fallen from the nozzle surface 14F onto the suppressing member 74 will be described. As shown in FIG. 21 and the like, since the horizontal portion 74C occupies most of the upper surface, most of the ink falls onto the horizontal portion 74C, and the rest of the ink directly falls into the through-hole 74H, the recess 74A, and the storage portion 74B.

[0086] The ink that has fallen onto the horizontal portion 74C is shaken by the vibration and air flow inside the inkjet recording apparatus 1, so the ink near the through-hole 74H, the recess 74A, and the storage portion 74B flows into the through-hole 74H, the recess 74A, and the storage portion 74B, respectively. When the ink flows into the recess 74A, the surface tension further draws the ink from the horizontal portion 74C into the recess 74A. The ink that has flowed into the through-hole 74H falls onto the cap 72, but the ink that has fallen into the recess 74A and the storage portion 74B stays in the recess 74A and the storage portion 74B, respectively. Since the storage portion 74B is deeper than the recess 74A, the ink staying in the recess 74A gradually flows down into the storage portion 74B. Thus, since a part of the ink that has fallen onto the upper surface of the suppressing member 74 flows into the recess 74A and the storage portion 74B, the inflow of ink into the through-hole 74H is reduced, and the through-hole 74H is less likely to be clogged. Therefore, the supply of the humidifying air WA to the nozzle surface 14F can be stabilized.

[0087] 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, an air supply port 72NA provided in the cap 72, and at least provided between the air supply port 72NA and the nozzle surface 14F, having a first gap G1 between the air supply port 72NA and a suppression member 74 having a second gap G2 between the nozzle surface 14F. The suppression member 74 is provided at a location that does not face the air supply port 72NA of the suppression member 74, and includes one or more through holes 74H penetrating from the air supply port 72NA side to the nozzle surface 14F side, and a recess 74A provided on the upper surface of the suppression member 74 and recessed from the edge 74HE of the through hole 74H. According to this configuration, a part of the ink that has fallen on the upper surface of the suppression member 74 flows into the recess 74A, so that the inflow of ink into the through hole 74H is reduced, and the through hole 74H is less likely to be clogged. Therefore, the supply of humidified air WA to the nozzle surface 14F can be stabilized.

[0088] Also, according to the maintenance device 30 according to the present embodiment, the cap 72 includes an exhaust port 72EA, the through holes 74H are provided at a plurality of locations along the direction from the air supply port 72NA side to the exhaust port 72EA side, and the recess 74A is formed in a groove shape along the direction from the air supply port 72NA side to the exhaust port 72EA side. According to this configuration, the supply of humidified air WA can be made uniform in the direction from the air supply port 72NA side to the exhaust port 72EA side. Also, even if the number of through holes 74H is increased, the ink is likely to flow into the recess 74A.

[0089] Also, according to the maintenance device 30 according to the present embodiment, a plurality of rows of through holes 74H are arranged along the direction from the air supply port 72NA side to the exhaust port 72EA side, and the recess 74A is arranged between the rows of the through holes 74H. According to this configuration, the supply of humidified air WA can be made uniform in a direction intersecting the direction from the air supply port 72NA side to the exhaust port 72EA side. Also, even if the number of rows of through holes 74H is increased, the ink is likely to flow into the recess 74A.

[0090] Further, according to the maintenance device 30 according to the present embodiment, two recesses 74A are arranged between two rows of through holes 74H. According to this configuration, by arranging the two rows of through holes 74H apart from each other, it becomes difficult for ink to drop near the through holes 74H. Further, the ink that has dropped between the two rows of through holes 74H easily flows into the recesses 74A.

[0091] Further, according to the maintenance device 30 according to the present embodiment, a storage portion 74B for storing the liquid that has flowed along the recess 74A is provided. According to this configuration, it becomes difficult for the ink to overflow from the recess 74A.

[0092] Further, according to the maintenance device 30 according to the present embodiment, the storage portion 74B is provided on the upper surface of the suppression member 74 and is formed deeper than the recess 74A. According to this configuration, the discharge of ink from the recess 74A to the storage portion 74B is promoted, so it becomes difficult for the ink to overflow from the recess 74A.

[0093] [Modification Example of the Fourth Embodiment] The fourth embodiment may be modified as follows.

[0094] [First Modification Example] FIG. 25 is a perspective view showing a cap 72 provided with a suppression member 74. In this modification example, at least one end portion (the front end portion in FIG. 25) of the recess 74A penetrates the end surface 74D of the suppression member 74, and the storage portion 74E is provided at the bottom portion 72B of the cap 72. The storage portion 74E is provided below the front end portion of the recess 74A and is formed in a box shape that opens upward. The ink staying in the recess 74A flows down from the front end portion of the recess 74A into the storage portion 74E. According to this configuration, the discharge of ink from the recess 74A to the storage portion 74E is promoted, so it becomes difficult for the ink to overflow from the recess 74A. Further, since there are few irregularities on the upper surface of the suppression member 74, the disturbance of the air flow of the humidified air WA can be suppressed.

[0095] [Second Modification Example] FIG. 26 is a perspective view showing a cap 72 provided with a suppression member 74. In this modified example, a recess 74A is formed in a portion of the upper surface of the suppression member 74 excluding the edge portion 74F of the upper surface and the edge portion 74HE of the through hole 74H. According to this configuration, most of the ink that has fallen onto the suppression member 74 falls into the recess 74A, so that the inflow of ink into the through hole 74H is reduced, and the through hole 74H is less likely to be clogged. Therefore, the supply of humidified air WA to the nozzle surface 14F can be stabilized.

[0096] [Third Modified Example] FIG. 27 is a cross-sectional view showing the suppression member 74. In this modified example, the upper surface of the suppression member 74 is inclined such that the recess 74A side is lower in a direction (in this embodiment, the left-right direction) intersecting the direction from the air supply port 72NA side to the exhaust port 72EA side (in this embodiment, the front-rear direction). According to this configuration, the ink that has fallen onto the upper surface of the suppression member 74 is likely to flow into the recess 74A.

[0097] [Fourth Modified Example] In addition to the above configuration, the bottom of the recess 74A may be inclined in the longitudinal direction of the recess 74A (hereinafter, not shown). For example, in the fourth embodiment, the bottom of the recess 74A may be inclined such that the storage portion 74B side is lower. Also, in the first modified example, the bottom of the recess 74A may be inclined such that the storage portion 74E side is lower. Further, in the second modified example, a storage portion 74E similar to that in the first modified example is provided, a notch is provided in the edge portion 74F above the storage portion 74E, and the bottom of the recess 74A may be inclined such that the storage portion 74E side is lower. According to these configurations, the discharge of ink from the recess 74A to the storage portions 74B and 74E is promoted, so that it is less likely for the ink to overflow from the recess 74A.

Explanation of Reference Numerals

[0098] 1 Inkjet recording apparatus 12 Inkjet head 14F Nozzle surface 30 Maintenance device 72 Cap 72B Bottom 72EA Exhaust port 72NA Air intake port 74 Suppression member 74A Recess 74B Reservoir 74D End face 74H Through hole 74HE Edge G1 First gap G2 Second gap

Claims

1. A cap attached to the nozzle surface of an inkjet head, An air supply port provided in the cap, A suppression member provided at least between the air supply port and the nozzle surface, having a first gap with the air supply port and a second gap with the nozzle surface, and comprising: The suppression member, One or more through-holes provided at a location of the suppression member that does not face the air supply port and penetrating from the air supply port side to the nozzle surface side, A recess provided on the upper surface of the suppression member and recessed from the edge of the through-hole, characterized in that it is a maintenance device.

2. The cap includes an exhaust port, The through-holes are provided at a plurality of locations along the direction from the air supply port side to the exhaust port side, The recess is formed in a groove shape along the direction from the air supply port side to the exhaust port side, characterized in that it is the maintenance device according to Claim 1.

3. A plurality of rows of the through-holes are arranged along the direction from the air supply port side to the exhaust port side, The recess is arranged between the rows of the through-holes, characterized in that it is the maintenance device according to Claim 2.

4. Two of the recesses are arranged between two rows of the through-holes, characterized in that it is the maintenance device according to Claim 3.

5. A storage portion for storing the liquid flowing along the recess, characterized in that it is the maintenance device according to any one of Claims 2 to 4.

6. The storage portion is provided on the upper surface of the suppression member and is formed deeper than the recess, characterized in that it is the maintenance device according to Claim 5.

7. At least one end of the recess penetrates the end surface of the suppression member, The storage portion is provided at the bottom of the cap, characterized in that it is the maintenance device according to Claim 5.

8. The inkjet head, An inkjet recording apparatus, characterized in that it includes the maintenance device according to Claim 1.

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