Maintenance equipment and inkjet recording device

Abstract

The purpose is to suppress pressure changes inside the cap when attaching or detaching the cap from the nozzle surface. [Solution] The maintenance device comprises a cap 72 attached to the nozzle surface 14F of the inkjet head 12, a flow path (recovery section 94, recovery flow path 95E) connected to the cap 72, an air pump 95 that sucks air A from the cap 72 through the flow path, and a supply section 92 that stores a humidifying medium WM, generates humidified air WA by passing the air A supplied from the air pump 95 through the humidifying medium WM, and supplies the humidified air WA to the cap 72, and the flow path has a vent 94H that is open to the atmosphere.

Description

Technical Field

[0001] The present invention relates to a maintenance device and an inkjet recording device.

Background Art

[0002] In an inkjet recording device using aqueous ink, during non-printing, moisture may evaporate from the ink in the nozzles, increasing the viscosity and potentially causing ejection failure or clogging. Therefore, conventionally, techniques for suppressing moisture evaporation from the ink in the nozzles have been studied. For example, Patent Documents 1 and 2 disclose devices 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

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configurations disclosed in Patent Documents 1 and 2, due to the pressure change in the cap that occurs when attaching and detaching the cap, ejection failure of the inkjet head may occur. Also, in Patent Documents 1 and 2, air is humidified by passing air through the water stored in the tank, but there is a risk of water leakage from the tank or water flowing from the tank into the cap along with the pressure change in the cap.

[0005] In view of the above circumstances, an object of the present invention is to suppress the pressure change in the cap when attaching and detaching the cap with respect to the nozzle surface.

Means for Solving the Problems

[0006] To solve the above problems, the maintenance device according to the present invention comprises a cap attached to the nozzle surface of an inkjet head, a flow path connected to the cap, an air pump that sucks air from the cap through the flow path, and a supply unit that stores a humidifying medium, generates humidified air by passing the air supplied from the air pump through the humidifying medium, and supplies the humidified air to the cap, wherein the flow path has a vent that is open to the atmosphere.

[0007] The flow path includes a recovery unit connected to the cap and a recovery flow path connected to the recovery unit and the air pump, wherein the cap is provided with an exhaust port for discharging the air to the recovery unit, the recovery unit is provided with a suction port connected to the recovery flow path, and the vent may be provided in a position that does not overlap with the shortest path from the exhaust port to the suction port.

[0008] The ventilation opening may be provided on a surface different from the surface on which the suction opening of the recovery unit is provided.

[0009] The diameter of the vent may be smaller than the diameter of the suction port.

[0010] Furthermore, the inkjet recording apparatus according to the present invention comprises a plurality of inkjet heads and the maintenance apparatus described above. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress pressure changes inside the cap when attaching or detaching the cap from the nozzle surface. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing the external appearance of an image forming system according to one embodiment of the present invention. [Figure 2] This is a schematic front view showing the internal configuration of an inkjet recording device according to one embodiment of the present invention. [Figure 3]It is a front view schematically showing a head unit and a maintenance device according to an embodiment of the present invention. [Figure 4] It is a plan view schematically showing a head unit and a wiper unit according to an embodiment of the present invention. [Figure 5] It is a plan view schematically showing a cap unit according to an embodiment of the present invention. [Figure 6] It is a cross-sectional view showing an inkjet head according to an embodiment of the present invention. [Figure 7] It is a front view showing the operation of a maintenance device according to an embodiment of the present invention. [Figure 8] It is a perspective view showing a cap unit according to an embodiment of the present invention. [Figure 9] It is a plan view showing a cap unit according to an embodiment of the present invention. [Figure 10] It is a cross-sectional view showing the I-I cross-section of FIG. 9. [Figure 11] It is an exploded view showing a cap unit according to an embodiment of the present invention. [Figure 12] It is a view showing the flow of humidified air in a cap unit according to an embodiment of the present invention. [Figure 13] It is a plan view showing the positions of a supply unit and a recovery unit according to an embodiment of the present invention. [Figure 14] It is a cross-sectional view showing the flow of humidified air in a cap according to an embodiment of the present invention. [Figure 15] [[ID=三十七]]It is a plan view showing a recovery unit according to an embodiment of the present invention. [Figure 16] It is a perspective view showing a recovery unit according to a modification of an embodiment of the present invention.

Mode for Carrying Out the Invention

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

[0014] Figure 1 is a perspective view showing the external appearance of the image forming system 100. Figure 2 is a schematic front view showing the internal configuration of the inkjet recording device 1. Figure 3 is a schematic front view showing the head unit 11 and the maintenance device 30. Figure 4 is a schematic top view showing the head unit 11 and the wipe unit 32. Figure 5 is a schematic top view showing the cap unit 31. Figure 6 is a cross-sectional view showing the inkjet head 12. Figure 7 is a front view showing the operation of the maintenance device 30. Hereafter, the front side of the paper in Figure 2 will be considered the front side of the inkjet recording device 1, and the left and right directions will be explained based on the direction in which the inkjet recording device 1 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate top, bottom, left, right, front, and back, respectively.

[0015] The image forming system 100 (see Figure 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 holds several thousand sheets and supplies them to the inkjet recording device 1. The inkjet recording device 1 forms images 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 perforation, stapling, and folding on the sheets transported from the drying device 120.

[0016] The inkjet recording device 1 (see Figure 2) comprises a rectangular parallelepiped main housing 3. A transport unit 7 is provided in the center of the main housing 3 for adsorbing and transporting a sheet in the Y direction. An image-forming unit 6 is provided above the transport unit 7 for ejecting ink to form an image. A paper feed opening 8 is provided on the right side of the main housing 3 for introducing a sheet from the paper feed device 110. An outlet 9 is provided on the left side of the main housing 3 for discharging the sheet with the formed image to the drying device 120. Inside the main housing 3, a transport path 10 is provided from the paper feed opening 8 through the gap between the transport unit 7 and the image-forming unit 6 to the outlet 9. A registration roller 18 is provided upstream of the transport unit 7 in the transport direction Y.

[0017] The conveying unit 7 comprises an endless conveying belt 21 and a suction unit 24. The conveying belt 21 has numerous ventilation holes (not shown) and is wrapped around a drive roller 25 and a driven roller 22. The upper surface of the suction unit 24 has numerous ventilation holes (not shown) and is in contact with the inner surface of the conveying belt 21. The suction unit 24 sucks air through the ventilation holes of the conveying belt 21 and the ventilation holes of the suction unit 24, thereby causing the sheet to adhere to the conveying belt 21. The drive unit (not shown), which includes a motor and a reduction gear, drives the drive roller 25 in a counterclockwise direction, causing the conveying belt 21 to rotate in a counterclockwise direction, and the sheet adhered to the conveying belt 21 is conveyed in the Y direction.

[0018] The image-forming unit 6 comprises a plurality (four in this embodiment) of head units 11. Each head unit 11 (see Figures 3 and 4) comprises one or more (three in this embodiment) inkjet heads 12. Each head unit 11 is connected to an ink container 20 filled with black, cyan, magenta, and yellow inks, respectively.

[0019] The inkjet head 12 (see Figure 6) comprises a rectangular parallelepiped housing 12H with its longitudinal direction in the front-to-back direction, a nozzle plate 14 located below the housing 12H, and a socket 12S to which the ink supply piping is connected. The nozzle plate 14 is equipped with a number of nozzles 14N arranged in the front-to-back direction. Each nozzle 14N includes a branched channel 14B branching off from the downstream side of the socket 12S, and an ejection port 14A provided on the nozzle surface 14F, which is the lower surface of the nozzle plate 14. The diaphragm 14V also serves as part of the inner wall of the branched channel 14B. A pressure element 14Z is provided on the diaphragm 14V. The pressure element 14Z can be a piezoelectric element, an electrostatic actuator, a heater, etc. A drive circuit 12D that drives the pressure element 14Z is connected to the pressure element 14Z.

[0020] The control unit 2 (see Figure 2) comprises an arithmetic unit and a memory unit (not shown). The arithmetic unit is, for example, a CPU (Central Processing Unit). The memory unit includes storage media such as ROM (Read Only Memory), RAM (Random Access Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory). The arithmetic unit performs various processes by reading and executing control programs stored in the memory unit. The control unit 2 may also be implemented by an integrated circuit without software.

[0021] A display and operation unit 19 is provided at the top of the main housing 3 (see Figures 1 and 2). The display and 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 on the display panel showing the operation menu and status of the inkjet recording device 1, and controls each part of the inkjet recording device 1 according to operations detected by the touch panel and 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 feeds a sheet into the transport path 10 through the paper feed opening 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 transport unit 7 at a predetermined timing, the transport unit 7 picks up the sheet with the transport belt 21 and transports it in the Y direction. Ink is ejected onto the sheet from the inkjet head 12, and an image is formed. The sheet with the formed image is discharged to the drying device 120 through the discharge opening 9.

[0023] [Maintenance equipment] Next, the maintenance device 30 will be described. Since the four head units 11 and the four maintenance devices 30 have the same configuration, the following description will focus on one head unit 11 and the maintenance device 30 located to its right.

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

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

[0026] [Cap Unit] The cap unit 31 (see Figures 3 and 5) has the same number of caps 72 as the inkjet heads 12 of the head unit 11 (three in this embodiment). The three caps 72 are arranged in a staggered pattern, similar to the inkjet heads 12. The three caps 72 are attached to the upper surface of a plate-shaped frame 71 via a base portion 71M (see Figures 8 to 11). Two caps 72 are positioned front to back to the right of the center of the frame 71 in the left-right direction, and one cap 72 is positioned on the left side. The left cap 72 is positioned midway between the two right caps 72 in the front-back direction.

[0027] [Wipe Unit] The wipe unit 32 (see Figures 3 and 4) comprises a waste liquid tray 81 and a cleaning member 82. The waste liquid tray 81 has the same number of recesses 81U as the inkjet heads 12 of the head unit 11. The multiple recesses 81U are arranged in a staggered pattern, similar to the inkjet heads 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 mounted on a plurality of caps 72. In other words, the wipe unit 32 is mounted on the cap unit 31. The head unit 11 is provided with a cleaning liquid supply device 13 (see Figure 6) that supplies cleaning liquid to the nozzle surface 14F.

[0028] [Head lifting device] The head lifting device 11L (see Figure 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, 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 Figure 7(A)) is a position where the distance between the conveyor path 10 (upper surface of the conveyor belt 21) on 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 of the lifting range of the head unit 11 by the head lifting device 11L. The retracted position (see Figure 7(B)) is a position where the head unit 11 does not interfere with the wipe unit 32 when the cap unit 31 and wipe unit 32 are slid using the cap slide device 34, which will be described later. The retracted position is the upper limit of the lifting range of the head unit 11.

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

[0030] [Wipe lifting device] The wipe lifting device 35 (see Figure 4) is provided in front of and behind the waste liquid tray 81 of the wipe unit 32. The wipe lifting device 35 is composed of, for example, a ball screw, a belt drive device, etc. The wipe lifting device 35 raises and lowers the wipe unit 32 between a contact position where the waste liquid tray 81 is in contact with the cap 72 (see Figure 7(B)) and a separated position where the waste liquid tray 81 is separated from the cap 72 by a predetermined distance (see Figure 7(E)).

[0031] [Unit lifting device] The head lifting device 11L, the cap sliding device 34, and the wipe lifting device 35 are all attached to the frame 36F. In other words, the head unit 11 is supported by the frame 36F via the head lifting device 11L. The cap unit 31 is supported by the frame 36F via the cap sliding device 34. The wipe unit 32 is supported by the frame 36F via the wipe lifting device 35.

[0032] Unit lifting devices 36 are provided at the front and rear of the frame 36F. The unit lifting devices 36 are supported by the main housing 3. The unit lifting devices 36 are composed of, for example, a ball screw, a belt drive, etc., and raise and lower the frame 36F. In other words, the unit lifting devices 36 raise and lower the head unit 11 and the maintenance device 30 together. The unit lifting devices 36 raise and lower the head unit 11 and the maintenance device 30 between a normal position and a retracted position. When image forming is performed by the head unit 11 or maintenance is performed by the maintenance device 30, the frame 36F is positioned in the normal position (see Figures 7(A) to (G)). If a sheet gets jammed on the conveyor belt 21, the frame 36F is positioned in the retracted position (see Figure 7(H)) to facilitate the removal of the sheet, and the gap between the conveyor belt 21 and the frame 36F is increased.

[0033] Next, the configuration of the cap unit 31 will be described in detail. Figure 8 is a perspective view showing the cap unit 31. Figure 9 is a plan view showing the cap unit 31. Figure 10 is a cross-sectional view showing section II of Figure 9. Figure 11 is an exploded view showing the cap unit 31. Figure 12 is a diagram showing the flow of air A and humidified air WA inside the cap unit 31. Figure 13 is a plan view showing the positions of the supply unit 92 and the recovery unit 94. Figure 14 is a cross-sectional view showing the flow of humidified air WA inside the cap 72.

[0034] The maintenance device 30 according to 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 on each of the plurality of caps 72, one recovery unit 94 that recovers air A from the exhaust ports 72EA of all caps 72, and a plurality of supply units 92 provided on each cap 72 that supply humidified air WA, which is the air A recovered by the recovery unit 94, to the air intake port 72NA. The plurality of supply units 92 are arranged around the one recovery unit 94, and on each of the plurality of caps 72, the exhaust port 72EA is provided on the recovery unit 94 side and the air intake port 72NA is provided on the supply unit 92 side.

[0035] The multiple caps 72 include a first cap 721, a second cap 722, and a third cap 723, wherein the first cap 721 and the second cap 722 are arranged along a predetermined direction (for example, the front-to-back direction), the third cap 723 is positioned midway between the first cap 721 and the second cap 722 in the predetermined direction, and is positioned differently 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.

[0036] [cap] The cap 72 (see Figures 8 to 10) is formed in a box shape with an opening at the top. The cap 72 has a generally rectangular bottom portion 72B with the front-to-back direction as its longitudinal direction, and a side wall portion 72W that rises upright from the edge of the bottom portion 72B. The side wall portion 72W is made of a flexible material such as rubber. The bottom portion 72B is provided with an air intake port 72NA and an exhaust port 72EA. In the right rear and left caps 72, the air intake port 72NA is provided on the rear side and the exhaust port 72EA is provided on the front side. In the right front cap 72, the air intake port 72NA is provided on the front side and the exhaust port 72EA is provided on the rear side.

[0037] The three caps 72 are arranged in a staggered pattern. The first cap 721 is located on the right rear side of the frame 71, the second cap 722 is located in front of the first cap 721, and the third cap 723 is located on the left side of the frame 71. The first cap 721 and the third cap 723 have an exhaust port 72EA on the front side and an air intake port 72NA on the rear side. The second cap 722 has an exhaust port 72EA on the rear side and an air intake port 72NA on the front side. However, the second cap 722 may also have an exhaust port 72EA on the front side and an air intake port 72NA on the rear side.

[0038] [Supply Department, Collection Department] Below the frame 71 (see Figures 8, 11 to 13), there are the same number of supply units 92 as the caps 72 (three in this embodiment) and one recovery unit 94. Each supply unit 92 has a tank 92T. Each recovery unit 94 has a tank 94T. The supply units 92 and the recovery unit 94 are supported by the frame 91. Each supply unit 92 is located below the air intake 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 located below all the exhaust ports 72EA.

[0039] In other words, the three supply units 92 are arranged around one recovery unit 94, and in each of the three caps 72, the exhaust port 72EA is provided on the recovery unit 94 side, and the air intake port 72NA is provided on the supply unit 92 side. In other words, all the exhaust ports 72EA overlap the recovery unit 94 in the vertical direction, and in each of the multiple caps 72, the air intake port 72NA overlaps the supply unit 92 in the vertical direction.

[0040] Tank 92T has an opening 92A that opens upward (see Figure 11). Tank 94T has an opening 94A that opens upward. Tanks 92T and 94T are joined to the lower surface of the frame 71. In other words, the openings 92A and 94A are closed off by the frame 71. To put it another way, the frame 71 also serves as the ceiling for tanks 92T and 94T.

[0041] An air intake pipe 72N (see Figure 10) is connected to the air intake port 72NA of each cap 72, connecting the cap 72 to the supply unit 92 below it. An exhaust pipe 72E is connected to the exhaust port 72EA of each cap 72, connecting the cap 72 to the recovery unit 94. In other words, three caps 72 are connected to the recovery unit 94.

[0042] The frame 71 has an air intake port 71NA below the air intake port 72NA and an exhaust port 71EA below the exhaust port 72EA. The air intake pipe 72N passes through the air intake port 71NA. The exhaust pipe 72E passes through the exhaust port 71EA.

[0043] The air pump 95 is connected to the recovery unit 94 by a recovery channel 95E (see Figures 8, 9, and 11) and to all supply units 92 by a supply channel 95N. The recovery channel 95E is connected to a suction port 94SA located at the bottom of the tank 94T of the recovery unit 94. The air pump 95 recovers air A with reduced water vapor pressure from the recovery unit 94 via the recovery channel 95E and supplies the recovered air A to all supply units 92 via the supply channel 95N (see Figure 12).

[0044] All supply units 92 are connected to a sub-tank 93 via a connecting pipe 92C (see Figures 10, 11, and 12). The sub-tank 93 is connected to a tank 93T and a pump 93P. The tank 93T stores a humidifying medium WM (see Figure 14). The humidifying medium WM is, for example, water, but any liquid containing water can be used. The pump 93P supplies the humidifying medium WM from tank 93T to the sub-tank 93. When the amount of humidifying medium WM in a supply unit 92 decreases, the difference in water head between the supply unit 92 and the sub-tank 93 replenishes the supply unit 92 with humidifying medium WM from the sub-tank 93, equalizing the liquid levels of the multiple supply units 92 and the sub-tank 93. By managing the amount of humidifying medium WM in the sub-tank 93, the amount of humidifying medium WM in the multiple supply units 92 can also be managed.

[0045] The sub-tank 93 is equipped with a sensor 93S (see Figures 8, 9, 11, and 12) that detects the amount of 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 equipped with a first heating unit 92H (see Figure 10) that heats the supply unit 92. The cap 72 is equipped with a second heating unit 72H that heats the cap 72. The supply unit 92 is equipped with a sensor 92S that measures the temperature inside the supply unit 92. The cap 72 is equipped with a sensor 72S that measures the temperature inside the cap 72. The recovery unit 94 is equipped with a sensor 94S that measures 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 explained. In the initial state (see Figure 7(A)), the frame 36F is in the normal position, the head unit 11 is in the image forming position, and the cap unit 31 is in 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 performs the following processing at predetermined timings. The predetermined timing is, for example, the timing at which an increase in the viscosity of the ink in the nozzle 14N is expected, specifically, when there is a predetermined period of time during which no image forming jobs are performed.

[0047] First, the control unit 2 activates the head lifting device 11L to raise the head unit 11 to the retracted position (see Figure 7(B)). Next, the control unit 2 activates the cap sliding device 34 to slide the cap unit 31 to the maintenance position (see Figure 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 activates the head lifting device 11L to lower the head unit 11 to a height where the nozzle surface 14F contacts the cleaning member 82 (see Figure 7(D)).

[0048] Next, the control unit 2 forcibly ejects a predetermined amount of ink from the inkjet head 12 (purging process), supplies cleaning fluid to the nozzle surface 14F, and slides the cleaning member 82 along the nozzle surface 14F (wiping process). As a result, the ink remaining on the nozzle surface 14F is diluted with the cleaning fluid, and the waste liquid containing the ink and cleaning fluid is scraped off by the cleaning member 82 and falls into the waste liquid tray 81.

[0049] Next, the control unit 2 activates the head lifting device 11L to raise the head unit 11 to the retracted position (see Figure 7(C)). Next, the control unit 2 activates the cap sliding device 34 to slide the cap unit 31 and the wipe unit 32 to the home position (see Figure 7(B)).

[0050] Next, the control unit 2 activates the wipe lifting device 35 to raise the wipe unit 32 to the separated position (see Figure 7(E)). Next, the control unit 2 activates the cap sliding device 34 to slide the cap unit 31 to the maintenance position (see Figure 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.

[0051] 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 Figure 7(G)). In this way, 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 values ​​measured by the sensor 93S and maintains the liquid level in the sub-tank 93 within a predetermined range. Specifically, when the measured liquid level falls below the predetermined range, the pump 93P is used to replenish a predetermined amount of humidifying medium WM from the tank 93T to the sub-tank 93. Since the sub-tank 93 is connected to the supply unit 92 by a connecting pipe 92C, the liquid level of the humidifying medium WM is uniform in the sub-tank 93 and all the supply units 92.

[0053] The air pump 95 (see Figure 12) recovers air A, whose water vapor pressure has decreased, from the recovery unit 94 via the recovery channel 95E, and supplies the recovered air A to all supply units 92 via the supply channel 95N. The end of the supply channel 95N on the supply unit 92 side is positioned below the liquid level of the humidifying medium WM (see Figure 14). Therefore, within the supply unit 92, air A is blown into the humidifying medium WM, generating bubbles B. The water vapor pressure of bubbles B increases before they float to the liquid surface. Also, 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 level in the supply unit 92 is filled with humidified air WA with 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 recover and supply air A continuously or intermittently.

[0054] Meanwhile, in the recovery section 94, air A is drawn in by the air pump 95, creating negative pressure. As a result, a flow of humidified air WA is generated inside the cap 72, moving from the air intake 72NA to the exhaust port 72EA. Furthermore, since the humidified air WA supplied to the cap 72 is heated in the first heating section 92H, convection occurs inside the cap 72, and 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 inside the nozzle 14N, suppressing the increase in ink viscosity.

[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) that measures the temperature of the inkjet head 12 (for example, the temperature of the ink in the nozzle 14N). Also, as mentioned above, the supply unit 92 is provided with a first heating unit 92H (see Figure 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.

[0056] The control unit 2 monitors the values ​​measured 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 which case the humidifying effect on the ink inside the nozzle 14N will not be obtained. In contrast, in this embodiment, humidified air WA with a higher humidity than that inside the nozzle 14N of the inkjet head 12 is supplied.

[0057] Furthermore, the control unit 2 monitors the values ​​measured 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 decrease inside the cap 72. If the temperature of the humidified air WA drops below the dew point, condensation will occur, the humidity inside the cap 72 will decrease, and the humidifying effect will not be obtained. In contrast, in this embodiment, the temperature of the humidified air WA does not decrease inside the cap 72, so there is no risk of the humidity inside the cap 72 decreasing due to condensation.

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

[0059] If a sheet becomes jammed between the conveyor belt 21 and the frame 36F during image formation, the control unit 2 activates the unit lifting device 36 to raise the frame 36F to the retracted position (see Figure 7(H)). When the user removes the sheet and instructs the display operation unit 19 to resume image formation, the control unit 2 activates the unit lifting device 36 to lower the frame 36F to its normal position (see Figure 7(A)) and resumes the image formation job.

[0060] Here, we will explain the pressure change inside the cap 72 when the cap 72 is attached to and detached from the nozzle surface 14F. When humidifying the nozzle surface 14F, after the cap 72 is attached to the nozzle surface 14F, the air pump 95 is driven, and a circulation of air A returns to the air pump 95 from the air pump 95 through the supply unit 92, cap 72, and recovery unit 94. Inside the supply unit 92, air A is blown into the humidifying medium WM, and bubbles B are generated. The water vapor pressure of bubbles B increases before they float to the liquid surface. Also, since the humidifying medium WM inside the supply unit 92 is heated in the first heating unit 92H, water vapor is easily generated. Therefore, the space above the liquid surface in the supply unit 92 is filled with humidified air WA with increased water vapor pressure, and the humidified air WA flows into the cap 72 through the air supply pipe 72N.

[0061] As a result, the air pressure inside the supply unit 92 and the cap 72 increases, pushing down the liquid level of the humidifying medium WM in the supply unit 92, and pushing the humidifying medium WM back into the sub-tank 93 through the connecting pipe 92C. Consequently, the liquid level in the sub-tank 93 rises, and the liquid level in the supply unit 92 falls. When the liquid level in the sub-tank 93 rises, there is a risk that the humidifying medium WM will overflow from the sub-tank 93. Also, when the air pressure inside the cap 72 increases, the ink with increased viscosity is pushed back into the nozzle 14N, which may lead to a dispensing failure. Furthermore, since the side wall portion 72W of the cap 72 is made of a flexible material such as rubber, the side wall portion 72W expands horizontally due to the increase in air pressure inside the cap 72.

[0062] After humidification of the nozzle surface 14F is completed, the air pump 95 is stopped. However, the air pressure inside the supply unit 92 and the cap 72 does not immediately return to atmospheric pressure. Therefore, when the cap 72 is detached from the nozzle surface 14F, the humidified air WA, whose pressure has increased, flows out all at once from the cap 72 and the supply unit 92, returning to atmospheric pressure. As a result, the liquid level in the supply unit 92 rises, and the liquid level in the sub-tank 93 falls. When the liquid level in the supply unit 92 rises, there is a risk that the humidifying medium WM may enter the cap 72 through the air supply pipe 72N and the exhaust pipe 72E.

[0063] Therefore, the maintenance device 30 according to this embodiment is equipped with a configuration that suppresses pressure changes inside the cap 72 when attaching or detaching the cap 72 to the inkjet head 12. Specifically, a vent 94H is provided at the bottom of the tank 94T of the recovery unit 94 (see Figures 11 and 12). The vent 94H penetrates the bottom of the tank 94T vertically and is open to the atmosphere. With this configuration, when the air pressure inside the cap 72 rises, some of the air A flows out into the atmosphere through the vent 94H, thus mitigating the rise in air pressure inside the cap 72 and the supply unit 92. In addition, when the air pump 95 is stopped, air A flows out through the vent 94H and the air pressure gradually decreases, so a rapid drop in air pressure inside the cap 72 and the supply unit 92 when the cap 72 is detached from the nozzle surface 14F can be suppressed.

[0064] Figure 15 is a plan view showing the recovery unit 94. The vent 94H is positioned so as not to overlap with the shortest paths R1, R2, and R3 from the exhaust port 72EA to the suction port 94SA of each cap 72. This configuration suppresses the outflow of air A from the vent 94H when humidifying the nozzle surface 14F, thereby suppressing a decrease in the suction efficiency of the air pump 95.

[0065] The above embodiment may be modified as follows.

[0066] Figure 16 is a perspective view showing a modified recovery unit 94. The vent 94H may be provided on a surface different from the surface on which the suction port 94SA of the recovery unit 94 is provided. For example, in the example of Figure 16, the suction port 94SA is provided at the bottom of the tank 94T, and the vent 94H is provided on the side wall of the tank 94T. With this configuration, the vent 94H can be separated from the suction port 94SA, so when humidifying the nozzle surface 14F, the outflow of air A from the vent 94H is suppressed, and the decrease in the suction efficiency of the air pump 95 is suppressed.

[0067] The diameter of the vent 94H may be smaller than the diameter of the suction port 94SA (see Figures 15 and 16). This configuration also suppresses the outflow of air A from the vent 94H when humidifying the nozzle surface 14F, thereby suppressing a decrease in the suction efficiency of the air pump 95.

[0068] In the above embodiment, an example was shown in which the vent 94H is provided in the recovery section 94, but the vent 94H may also be provided in the recovery flow path 95E. In other words, the vent 94H is provided in the flow path (including the recovery section 94 and the recovery flow path 95E) for drawing air A from the cap 72.

[0069] In the above embodiment, an example is shown in which the maintenance device 30 is equipped with a recovery unit 94, but the maintenance device 30 does not have to be equipped with a recovery unit 94. In this case, the recovery channel 95E is connected to the cap 72 without going through the recovery unit 94. The vent 94H is provided in the recovery channel 95E.

[0070] In the above embodiment, an example was shown in which the head unit 11 has a plurality of inkjet heads 12 and the maintenance device 30 has the same number of caps 72 as the inkjet heads 12. However, the present invention may also be applied to a configuration in which the head unit 11 has one inkjet head 12 and the maintenance device 30 has one cap 72.

[0071] The maintenance device 30 according to the embodiment described above includes a cap 72 attached to the nozzle surface 14F of the inkjet head 12, a flow path (recovery section 94, recovery flow path 95E) connected to the cap 72, an air pump 95 that sucks air A from the cap 72 through the flow path, and a supply section 92 that stores a humidifying medium WM, generates humidified air WA by passing the air A supplied from the air pump 95 through the humidifying medium WM, and supplies the humidified air WA to the cap 72. The flow path has a vent 94H that is open to the atmosphere. With this configuration, pressure changes inside the cap 72 when attaching or detaching the cap 72 from the nozzle surface 14F can be suppressed.

[0072] Furthermore, in the maintenance device 30 according to this embodiment, the flow path includes a recovery unit 94 connected to the cap 72 and a recovery flow path 95E connected to the recovery unit 94 and the air pump 95. The cap 72 is provided with an exhaust port 72EA for discharging air A to the recovery unit 94, the recovery unit 94 is provided with a suction port 94SA connected to the recovery flow path 95E, and the vent port 94H is provided in a position that does not overlap with the shortest paths R1, R2, and R3 from the exhaust port 72EA to the suction port 94SA. With this configuration, a decrease in the suction efficiency of the air pump 95 can be suppressed.

[0073] Furthermore, in the inkjet recording apparatus 1 according to this embodiment, the vent 94H is provided on a surface different from the surface on which the suction port 94SA of the recovery unit 94 is provided. This configuration makes it possible to suppress the increase in viscosity of the ink in the nozzle 14N of the inkjet head 12.

[0074] Furthermore, in the inkjet recording apparatus 1 according to this embodiment, the diameter of the vent port 94H is smaller than the diameter of the suction port 94SA. This configuration suppresses a decrease in the suction efficiency of the air pump 95. [Explanation of Symbols]

[0075] 1. Inkjet recording device 12 inkjet heads 14F Nozzle surface 30 Maintenance equipment 72 Caps 72EA Exhaust Port 92 Supply section 94 Recovery section (flow channel) 94H Vent 94SA Suction port 95 Air pump 95E Recovery channel (channel) A air Shortest path for R1, R2, and R3 WA Humidified Air WM humidifying medium

Claims

1. A cap that is attached to the nozzle surface of the inkjet head, A flow path connected to the cap, An air pump that draws air from the cap through the aforementioned flow path, The system includes a supply unit that stores a humidifying medium, generates humidified air by passing air supplied from the air pump through the humidifying medium, and supplies the humidified air to the cap, The maintenance device is characterized in that the flow path has a vent that is open to the atmosphere.

2. The aforementioned flow path is A recovery unit connected to the cap, Includes a recovery channel connected to the recovery unit and the air pump, The cap is provided with an exhaust port for discharging the air to the recovery section. The recovery unit is equipped with a suction port connected to the recovery channel, The maintenance device according to claim 1, characterized in that the ventilation opening is provided in a position that does not overlap with the shortest path from the exhaust port to the suction port.

3. The maintenance device according to claim 2, characterized in that the ventilation opening is provided on a surface different from the surface on which the suction opening of the recovery unit is provided.

4. The maintenance device according to claim 2 or 3, characterized in that the diameter of the vent is smaller than the diameter of the suction port.

5. Multiple inkjet heads, An inkjet recording apparatus comprising the maintenance device described in claim 1.

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