Maintenance apparatus and inkjet recording apparatus

Abstract

The present invention provides a maintenance device and an ink jet recording apparatus, the maintenance device including: a cover attached to a nozzle surface of an ink jet head; and a supply unit that stores a humidification medium, generates humidified air by passing air through the humidification medium, and supplies the humidified air to the cover through an air supply pipe that communicates with the cover, the air supply pipe being provided in the vertical direction in a space above the liquid level of the humidification medium inside the supply unit, and the air supply pipe being provided in the vertical direction in a space above the liquid level of the humidification medium. A notch is formed in at least the inner surface side of the pipe wall of the air supply pipe.

Description

Technical Field

[0001] The present invention relates to a maintenance device for maintaining an inkjet head and an inkjet recording device. Background Art

[0002] In an inkjet recording device using water-based ink, when printing is not performed, the ink in the nozzle evaporates and the viscosity increases, which poses a risk of poor ejection and clogging. Therefore, in the past, a technology for suppressing the evaporation of water from the ink in the nozzle has been studied. As a related technology, a device for supplying humidified air into a cap covering the ejection surface (nozzle surface) of the head has been studied.

[0003] In the structure of the above-mentioned related art, since the humidified air is generated by sending air into the water (humidifying medium) in the container, and the humidified air is supplied to the cover through the tube (air supply pipe), there is a risk that the liquid level in the container rises due to the air and the humidifying medium penetrates into the air supply pipe and the cover. Although the penetration of the humidifying medium can be prevented by increasing the distance between the connection part of the air supply pipe and the liquid level, in order to improve the humidification effect, a deeper water depth is advantageous. In order to meet these two requirements, the size of the container needs to be increased, which leads to the problem of large-scale device. Summary of the invention

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress the infiltration of the humidifying medium into the air supply pipe.

[0005] In order to solve the above-mentioned problems, the maintenance device of the present invention comprises: a cover, which is installed on the nozzle surface of the inkjet head; and a supply part, which stores a humidifying medium, generates humidified air by passing air through the humidifying medium, and supplies the humidified air to the cover through an air supply pipe connected to the cover, and inside the supply part, the air supply pipe is arranged in the up and down direction in a space above the liquid level of the humidifying medium, and a cut is provided on at least the inner surface side of the tube wall of the air supply pipe.

[0006] The cutouts may also be arranged along the up-down direction.

[0007] The cutout may also pass through the lower end surface of the tube wall.

[0008] The cutout may also penetrate from the inner surface to the outer surface of the tube wall.

[0009] Furthermore, an inkjet recording apparatus according to the present invention includes: a plurality of the inkjet heads; and any one of the maintenance devices described above.

[0010] According to the present invention, it is possible to suppress the humidifying medium from entering the air supply pipe.

[0011] This specification is presented in a simplified form, with appropriate reference to the accompanying drawings, to summarize the concepts described in the following detailed description. This specification is not intended to limit the important features and essential features of the subject matter described in the claims, nor is it intended to limit the scope of the subject matter described in the claims. In addition, the subject matter described in the claims is not limited to implementations that solve some or all of the disadvantages described in any part of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a perspective view showing the appearance of an image forming system according to one embodiment of the present invention.

[0013] Figure 2 This is a front view schematically showing the internal structure of an inkjet recording device according to one embodiment of the present invention.

[0014] Figure 3 It is a front view schematically showing a head unit and a maintenance device according to one embodiment of the present invention.

[0015] Figure 4 It is a plan view schematically showing a head unit and a wiping unit according to one embodiment of the present invention.

[0016] Figure 5 It is a plan view schematically showing a cover unit according to one embodiment of the present invention.

[0017] Figure 6 This is a cross-sectional view showing an inkjet head according to one embodiment of the present invention.

[0018] Figure 7 This is a front view showing the operation of the maintenance device according to one embodiment of the present invention.

[0019] Figure 8 It is a perspective view showing a cover unit according to one embodiment of the present invention.

[0020] Fig. 9 It is a top view showing a cover unit according to one embodiment of the present invention.

[0021] Fig.10 Yes means Fig. 9 Cross-sectional view of section II.

[0022] Fig.11 This is an exploded view showing a cover unit according to one embodiment of the present invention.

[0023] Fig.12 This is a diagram showing the flow of humidified air in the cover unit according to one embodiment of the present invention.

[0024] Fig.13It is a top view showing the positions of a supply unit and a recovery unit according to one embodiment of the present invention.

[0025] Fig.14 This is a cross-sectional view showing the flow of humidified air in the cover according to one embodiment of the present invention.

[0026] Fig.15 It is a perspective view showing an air supply pipe according to one embodiment of the present invention.

[0027] Fig.16 It is a perspective view showing an air supply pipe according to a first modified example of one embodiment of the present invention.

[0028] Fig.17 It is a perspective view showing an air supply pipe according to a second modified example of one embodiment of the present invention. DETAILED DESCRIPTION

[0029] Hereinafter, an inkjet recording device 1 according to an embodiment of the present invention will be described with reference to the drawings.

[0030] Figure 1 It is a perspective view showing the appearance of the image forming system 100 . Figure 2 It is a front view schematically showing the internal structure of the inkjet recording device 1 . Figure 3 It is a front view schematically showing the head unit 11 and the maintenance device 30 . Figure 4 It is a plan view schematically showing the head unit 11 and the wiping unit 32 . Figure 5 It is a plan view schematically showing the cover unit 31 . Figure 6 It is a cross-sectional view showing the inkjet head 12. Figure 7 30 is a front view showing the operation of the maintenance device 30. Figure 2 The front side of the paper in the figure is regarded as the front side (front side) of the inkjet recording device 1, and the left and right directions are described based on the direction when the inkjet recording device 1 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr represent up, down, left, right, front, and back, respectively.

[0031] Image forming system 100 (see Figure 1 ) includes a paper feeding device 110, an inkjet recording device 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 device 1. The inkjet recording device 1 forms an image on the sheet by inkjet method. The drying device 120 heats the sheet conveyed from the inkjet recording device 1 to dry the ink. The post-processing device 130 performs post-processing such as punching, stapling, and folding on the sheet conveyed from the drying device 120.

[0032] Inkjet recording device 1 (refer to Figure 2) is provided with a main body shell 3 in the shape of a rectangular parallelepiped. A conveying unit 7 for sucking a sheet and conveying it in the Y direction is provided in the central part of the main body shell 3. An imaging unit 6 for ejecting ink to form an image is provided above the conveying unit 7. A paper feed port 8 for introducing a sheet from a paper feed device 110 is provided on the right side of the main body shell 3. A discharge port 9 for discharging the sheet with an image formed thereon to a drying device 120 is provided on the left side of the main body shell 3. A conveying passage 10 is provided inside the main body shell 3, which extends from the paper feed port 8 through the gap between the conveying unit 7 and the imaging unit 6 to the discharge port 9. A registration roller 18 is provided on the upstream side of the conveying unit 7 in the conveying direction Y.

[0033] The conveying unit 7 includes an endless conveyor belt 21 and a suction unit 24. The conveyor belt 21 has a plurality of vents (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 plurality of vents (not shown) and is in contact with the inner surface of the conveyor belt 21. The suction unit 24 sucks air through the vents of the conveyor belt 21 and the vents of the suction unit 24, thereby adsorbing the sheet to the conveyor belt 21. The driving roller 25 is driven counterclockwise by a driving unit (not shown) including a motor and a reduction gear, so that the conveyor belt 21 rotates counterclockwise, and the sheet adsorbed to the conveyor belt 21 is conveyed in the Y direction.

[0034] The imaging unit 6 includes a plurality of (four in this embodiment) head units 11. The head unit 11 (see Figure 3 , 4 ) is provided with one or more (three in this embodiment) inkjet heads 12. Each head unit 11 is connected to an ink tank 20, and the ink tank 20 is filled with black, cyan, magenta and yellow inks, respectively.

[0035] Inkjet head 12 (see Figure 6 ) is provided with a rectangular parallelepiped housing 12H with the front-to-back direction as the long side direction, a nozzle plate 14 provided at the bottom of the housing 12H, and a socket 12S connected to a pipe for supplying ink. The nozzle plate 14 is provided with a plurality of nozzles 14N arranged in the front-to-back direction. The nozzle 14N includes a branch flow channel 14B branched from the downstream side of the socket 12S, and a discharge port 14A provided on a nozzle surface 14F as the lower surface of the nozzle plate 14. The vibration plate 14V also serves as a part of the inner wall of the branch flow channel 14B. A pressure element 14Z is provided on the vibration plate 14V. As the pressure element 14Z, a piezoelectric element, an electrostatic actuator, a heater, etc. are used. A driving circuit 12D for driving the pressure element 14Z is connected to the pressure element 14Z.

[0036] Control unit 2 (refer to Figure 2) has a computing unit and a storage unit (not shown). The computing unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as ROM (Read Only Memory), RAM (Random Access Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory). The computing unit performs various processes by reading and executing the control program stored in the storage unit. In addition, the control unit 2 can also be implemented by an integrated circuit that does not use software.

[0037] A display operation unit 19 (see Figure 1 , 2 The display operation unit 19 includes a display panel, a touch panel stacked on the display panel, and a keyboard (not shown). The control unit 2 displays a screen showing an operation menu, status, etc. of the inkjet recording device 1 on the display panel, and controls various parts of the inkjet recording device 1 according to operations detected by the touch panel and the keyboard.

[0038] 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, an external computer, etc., the paper feed device 110 feeds the sheet to the conveying path 10 through the paper feed port 8, and the registration roller 18, which has stopped rotating, corrects the skew of the sheet. When the registration roller 18 feeds the sheet to the conveying unit 7 at a predetermined timing, the conveying unit 7 adsorbs the sheet to the conveying 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 with the image formed thereon is discharged to the drying device 120 through the discharge port 9.

[0039] [Maintenance device] Next, the maintenance device 30 will be described. In addition, since the four head units 11 have the same structure and the four maintenance devices 30 have the same structure, one head unit 11 and one maintenance device 30 provided on the right thereof will be described below.

[0040] The head unit 11 includes a head base 11B (see Figure 3 , 4 ) Three inkjet heads 12 are arranged alternately on the head base 11B.

[0041] Maintenance device 30 (see Figure 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 wiping unit 32.

[0042] [Cover unit] Cover unit 31 (see Figure 3 , 5 ) includes the same number of caps 72 as the inkjet heads 12 included in the head unit 11 (three in this embodiment). The three caps 72 are arranged in a staggered manner similarly to the inkjet heads 12 and are supported by the frame 71.

[0043] [Wipe unit] Wiping unit 32 (see Figure 3 , 4 ) is provided with a waste liquid tray 81 and a cleaning member 82. The waste liquid tray 81 is provided with the same number of recesses 81U as the inkjet heads 12 provided in the head unit 11. The plurality of recesses 81U are arranged alternately in the same manner as the inkjet heads 12. The cleaning member 82 is provided in each recess 81U. The cleaning member 82 is, for example, a scraper. The waste liquid tray 81 is provided with a driving portion (not shown) for causing the cleaning member 82 to slide along the nozzle surface 14F. The waste liquid tray 81 is carried by a plurality of covers 72. In other words, the wiping unit 32 is carried by the cover unit 31. A cleaning liquid supply device 13 (refer to Figure 6 ).

[0044] [Head lifting device] Head lifting device 11L (refer to Figure 4 ) are provided in front and behind the head base 11B. The head lifting device 11L is composed of, for example, a ball screw, a belt drive device, etc. The head lifting device 11L raises and lowers the head unit 11 between the image forming position and the retreat position. Image forming position (refer to Figure 7 (A) is a position where the distance between the conveying path 10 (the upper surface of the conveying belt 21) for conveying sheets 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 retreat position (refer to Figure 7 (B)) is a position where the head unit 11 does not interfere with the wiping unit 32 when the cover unit 31 and the wiping unit 32 are slid using the cover sliding device 34 described later. The retracted position is the upper limit position of the lifting range of the head unit 11.

[0045] [Cover sliding device] Cover sliding device 34 (see Figure 5 ) are provided at the front and rear of the frame 71 of the cover unit 31. The cover slide device 34 is composed of, for example, a ball screw, a belt drive device, etc. The cover slide device 34 slides the cover unit 31 between the home position and the maintenance position. The home position (refer to Figure 7 (A)) is located to the right of the head unit 11 at the image forming position. Figure 7(F)) is a position below the head unit 11 located at the retracted position.

[0046] [Wipe lift device] Wiping lifting device 35 (refer to Figure 4 ) are provided in front and behind the waste liquid tray 81 of the wiping unit 32. The wiping lifting device 35 is composed of, for example, a ball screw, a belt drive device, etc. The wiping lifting device 35 enables the wiping unit 32 to be in a contact position (refer to Figure 7 (B)) and the separation position where the waste liquid tray 81 is separated from the cover 72 by a predetermined distance (refer to Figure 7 (E)) rises and falls.

[0047] Next, the structure of the cover unit 31 will be described in detail. Figure 8 It is a perspective view showing the cover unit 31 . Fig. 9 It is a plan view showing the cover unit 31 . Fig.10 Yes means Fig. 9 Cross-sectional view of section II. Fig.11 It is an exploded view showing the cover unit 31 . Fig.12 It is a diagram showing the flow of the humidified air WA in the cover unit 31 . Fig.13 It is a plan view showing the positions of the supply unit 92 and the recovery unit 94 . Fig.14 It is a cross-sectional view showing the flow of the humidified air WA in the cover 72 .

[0048] The maintenance device 30 of this embodiment includes: a plurality of caps 72 mounted on the nozzle surface 14F of the inkjet head 12; an air supply port 72NA and an air exhaust port 72EA provided in each of the plurality of caps 72; a 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 in each of the caps 72 to 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 with the one recovery unit 94 as the center, and 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.

[0049] The multiple covers 72 include a first cover 721, a second cover 722 and a third cover 723. The first cover 721 and the second cover 722 are arranged along a predetermined direction (for example, a front-to-back direction). The third cover 723 is arranged at an intermediate position between the first cover 721 and the second cover 722 in the predetermined direction, and is arranged at a position different from the first cover 721 and the second cover 722 in a direction intersecting the predetermined direction. The exhaust port 72EA of the first cover 721 is set on the side of the second cover 722, and the exhaust port 72EA of the second cover 722 is set on the side of the first cover 721.

[0050] [build] Cover 72 (see Figures 8 to 10 ) is formed into a box shape that opens upward. The cover 72 has a bottom 72B that is roughly rectangular with the front-to-back direction as the long side direction, and a side wall portion 72W that stands upright upward from the edge of the bottom 72B. The side wall portion 72W is formed of a flexible raw material such as rubber. An air supply port 72NA and an exhaust port 72EA are provided at the bottom 72B.

[0051] The three covers 72 are arranged alternately. The first cover 721 is arranged on the right rear side of the frame 71, the second cover 722 is arranged in front of the first cover 721, and the third cover 723 is arranged on the left side of the frame 71. In the first cover 721 and the third cover 723, an exhaust port 72EA is provided on the front side, and an air supply port 72NA is provided on the rear side. In the second cover 722, an exhaust port 72EA is provided on the rear side, and an air supply port 72NA is provided on the front side. In addition, in the second cover 722, the exhaust port 72EA can also be provided on the front side, and the air supply port 72NA can be provided on the rear side.

[0052] [Supply and Recovery Department] Below the frame 71 (see Figure 8 , 11 ~13) are provided with the same number of supply parts 92 as the cover 72 (three in the present embodiment), and a recovery part 94. The supply part 92 and the recovery part 94 are both containers for storing fluid. The supply part 92 and the recovery part 94 are supported by the frame 91. Each supply part 92 is respectively arranged below the air supply port 72NA of each cover 72. The recovery part 94 has a shape that overlaps with all the exhaust ports 72EA when viewed from above, and is arranged below all the exhaust ports 72EA.

[0053] In other words, the three supply units 92 are arranged with one recovery unit 94 as the center, and in each of the three covers 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. In addition, in other words, all the exhaust ports 72EA overlap with the recovery unit 94 in the vertical direction, and in each of the plurality of covers 72, the air supply port 72NA overlaps with the supply unit 92 in the vertical direction.

[0054] The air supply port 72NA of each cover 72 is connected to an air supply pipe 72N (see Fig.10 An exhaust pipe 72E that allows the cover 72 to communicate with the recovery unit 94 is connected to the exhaust port 72EA of each cover 72. That is, the three covers 72 are in communication with the recovery unit 94.

[0055] The air pump 95 passes through the recovery flow channel 95E (see Figure 8 , 9, 11) is connected to the recovery unit 94, and is connected to all the supply units 92 through the supply flow channel 95N. The air pump 95 recovers the air A with reduced water vapor pressure from the recovery unit 94 through the recovery flow channel 95E, and supplies the recovered air A to all the supply units 92 through the supply flow channel 95N (refer to Fig.12 ).

[0056] All supply units 92 are connected through a connecting pipe 92C (see Fig.10 , 11 , 12) is connected to the auxiliary container 93. The auxiliary container 93 is connected to a container 93T and a pump 93P. The container 93T stores a humidifying medium WM (see Fig.14 The humidifying medium WM is, for example, water, but may be any liquid containing water. The pump 93P supplies the humidifying medium WM from the tank 93T to the auxiliary tank 93.

[0057] The auxiliary tank 93 is provided with a sensor 93S (see Figure 8 , 9 , 11, 12). The sensor 93S detects, for example, the height of the liquid level in the auxiliary container 93. The supply unit 92 is provided with a first heating unit 92H (see Fig.10 ). The cover 72 is provided with a second heating unit 72H for heating the cover 72. The supply unit 92 is provided with a sensor 92S for measuring the temperature inside the supply unit 92. The cover 72 is provided with a sensor 72S for measuring the temperature inside the cover 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.

[0058] [Air supply pipe] However, if the air A is sent into the humidifying medium WM stored in the supply unit 92, the liquid level of the humidifying medium WM partially rises due to the air A, and the humidifying medium WM may penetrate into the air supply pipe 72N. If the penetrated humidifying medium WM adheres to the inner surface of the air supply pipe 72N, the flow path in the air supply pipe 72N becomes narrow or blocked, thereby hindering the supply of the humidified air WA. In addition, the adhered humidifying medium WM may be pushed by the humidified air WA and penetrate into the cover 72. If the humidifying medium WM penetrates into the cover 72, it becomes difficult to control the temperature and humidity in the cover 72.

[0059] Therefore, the maintenance device 30 of the present embodiment includes: a cap 72 mounted on the nozzle surface 14F of the inkjet head 12; and a supply unit 92 storing a humidifying medium WM, generating humidified air WA by passing air A through the humidifying medium WM, and supplying the humidified air WA to the cap 72 through an air supply pipe 72N connected to the cap 72, wherein the air supply pipe 72N is provided in the vertical direction in a space above the liquid level of the humidifying medium WM inside the supply unit 92, and a notch 72NS is provided on at least the inner surface side of a pipe wall 72NW of the air supply pipe 72N. The details are as follows.

[0060] Fig.15 72NW is a three-dimensional diagram showing the air supply pipe 72N. The air supply pipe 72N has a cylindrical pipe wall 72NW with the vertical direction as the longitudinal direction. The upper end of the pipe wall 72NW is connected to the air supply port 72NA. The lower end of the pipe wall 72NW is arranged in a space above the liquid level of the humidifying medium WM stored in the supply unit 92. In the pipe wall 72NW, a cutout 72NS along the vertical direction is provided in a predetermined range including the lower end of the pipe wall 72NW. The cutout 72NS penetrates the lower end of the pipe wall 72NW. The cutout 72NS penetrates from the inner surface of the pipe wall 72NW to the outer surface. The cutout 72NS is provided at six locations in the circumferential direction of the pipe wall 72NW at equal intervals.

[0061] Next, the basic operation of the maintenance device 30 will be described. Figure 7 In (A), the head unit 11 is located at the image forming position, and the cover unit 31 is located at the starting position. The wiping unit 32 is carried by the cover unit 31. That is, the waste liquid tray 81 is in contact with the cover 72. The control unit 2 performs the following processing at a predetermined timing. The predetermined timing is, for example, a timing when the viscosity of the ink in the nozzle 14N is expected to increase, specifically, when the period during which the image forming operation is not performed continues for a predetermined period.

[0062] First, the control unit 2 operates the head lifting device 11L to raise the head unit 11 to the retracted position (see Figure 7 Next, the control unit 2 operates the cover sliding device 34 to slide the cover unit 31 to the maintenance position (see Figure 7 (C)). At this time, since the wiper unit 32 is supported by the cover unit 31, the wiper unit 32 also slides to the maintenance position together with the cover unit 31. 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 cleaning member 82 (see Figure 7 (D)).

[0063] Next, after forcibly causing the inkjet head 12 to eject a predetermined amount of ink, the control unit 2 supplies cleaning liquid to the nozzle surface 14F and causes the cleaning member 82 to slide along the nozzle surface 14F. Thus, the ink remaining on the nozzle surface 14F is diluted by the cleaning liquid, and waste liquid containing the ink and the cleaning liquid is scraped off by the cleaning member 82 and falls into the waste liquid tray 81.

[0064] Next, the control unit 2 operates the head lifting device 11L to raise the head unit 11 to the retracted position (see Figure 7 Then, the control unit 2 operates the cover sliding device 34 to slide the cover unit 31 and the wiping unit 32 to the starting position (see Figure 7 (B)).

[0065] Next, the control unit 2 operates the wiping lifting device 35 to raise the wiping unit 32 to the separation position (see Figure 7 Next, the control unit 2 operates the cover sliding device 34 to slide the cover unit 31 to the maintenance position (see Figure 7 At this time, since the wiping unit 32 is separated from the cover unit 31, the wiping unit 32 remains at the starting position, and only the cover unit 31 slides to the maintenance position.

[0066] Next, the control unit 2 operates the head lifting device 11L to lower the head unit 11 to a height where the nozzle surface 14F contacts the cap 72 (see FIG. 14 ). Figure 7 In this way, the cap 72 is mounted on the nozzle face 14F.

[0067] Next, the control unit 2 humidifies the inside of the cover 72. The control unit 2 monitors the measured value of the sensor 93S and maintains the height of the liquid level in the auxiliary container 93 within a predetermined range. Specifically, when the measured value of the liquid level is lower than the predetermined range, the pump 93P is used to replenish the humidifying medium WM from the container 93T to the auxiliary container 93 in a predetermined amount. Since the auxiliary container 93 is connected to the supply unit 92 through the connecting pipe 92C, the height of the liquid level of the humidifying medium WM becomes the same in the auxiliary container 93 and all the supply units 92.

[0068] Air pump 95 (refer to Fig.12 ) The air A with reduced water vapor pressure is recovered from the recovery section 94 through the recovery flow passage 95E, and the recovered air A is supplied to all the supply sections 92 through the supply flow passage 95N. The end of the supply flow passage 95N on the supply section 92 side is arranged below the liquid level of the humidifying medium WM (refer to Fig.14). Therefore, in the supply section 92, air A is blown into the humidifying medium WM to generate bubbles B. During the period until the bubbles B float to the liquid surface, the water vapor pressure of the bubbles B rises. In addition, the humidifying medium WM in the supply section 92 is heated by the first heating section 92H, so it becomes easy to generate water vapor. Therefore, the humidified air WA with increased water vapor pressure fills the space above the liquid surface of the supply section 92, and the humidified air WA flows into the cover 72 through the air supply pipe 72N. In addition, the air pump 95 can recover and supply the air A continuously, or it can recover and supply the air A intermittently.

[0069] On the other hand, in the recovery section 94, the air A is sucked by the air pump 95, so that negative pressure is generated. Therefore, in the cover 72, an airflow of the humidified air WA is generated from the air supply port 72NA toward the exhaust port 72EA. In addition, since the humidified air WA supplied to the cover 72 is heated by the first heating section 92H, convection is generated in the cover 72, and the high-temperature humidified air WA is supplied to the nozzle surface 14F. In this way, the humidified air WA contacts the ink in the nozzle 14N and suppresses the increase in the viscosity of the ink.

[0070] When the air A is sent into the humidifying medium WM, the liquid level of the humidifying medium WM partially rises, and the humidifying medium WM may penetrate into the air supply pipe 72N. However, in the present embodiment, when the liquid level of the humidifying medium WM rises, the humidifying medium WM returns to the liquid level through the cutout 72NS provided in the pipe wall 72NW, thereby preventing the humidifying medium WM from penetrating into the air supply pipe 72N. As a result, it is also possible to prevent the humidifying medium WM from penetrating into the cover 72. In addition, since the penetration of the humidifying medium WM can be prevented even without increasing the distance between the lower end of the air supply pipe 72N and the liquid level of the humidifying medium WM, the size of the supply unit 92 can be reduced.

[0071] In addition to the above-mentioned control, the control unit 2 also performs temperature control 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). In addition, as described above, the supply unit 92 is provided with a first heating unit 92H (see Fig.10 ). The cover 72 is provided with a second heating unit 72H for heating the cover 72. The supply unit 92 is provided with a sensor 92S for measuring the temperature inside the supply unit 92. The cover 72 is provided with a sensor 72S for measuring the temperature inside the cover 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.

[0072] The control unit 2 monitors the measured value of the sensor 92S and controls the first heating unit 92H so that the temperature of the supply unit 92 becomes a temperature 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, there is a possibility that the humidity of the humidified air WA supplied from the supply unit 92 is lower than the humidity in the nozzle 14N of the inkjet head 12. In this case, the humidification effect of the ink in the nozzle 14N cannot be obtained. In contrast, in the present embodiment, the humidified air WA having a higher humidity than the humidity in the nozzle 14N of the inkjet head 12 is supplied.

[0073] In addition, the control unit 2 monitors the measured value of the sensor 72S and controls the second heating unit 72H so that the temperature of the cover 72 becomes a temperature higher than the temperature of the supply unit 92. If the temperature of the cover 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 in the cover 72. If the temperature of the humidified air WA decreases below the dew point, condensation occurs, the humidity in the cover 72 decreases, and the humidification effect cannot be obtained. In contrast, in the present embodiment, the temperature of the humidified air WA does not decrease in the cover 72, so there is no risk of a decrease in the humidity in the cover 72 due to condensation.

[0074] When an image forming job is to be executed, the control unit 2 operates the head lifting device 11L to raise the head unit 11 to the retracted position (see Figure 7 (F)), the cover sliding device 34 is operated to slide the cover unit 31 to the starting position (refer to Figure 7 (E)), the wiping lifting device 35 is operated to lower the wiping unit 32 to the contact position (refer to Figure 7 (B)). Then, the control unit 2 operates the head lifting device 11L to lower the head unit 11 to the image forming position to perform the image forming operation.

[0075] The maintenance device 30 of the present embodiment described above includes: a cap 72 mounted on the nozzle surface 14F of the inkjet head 12; a supply unit 92 storing the humidifying medium WM, generating the humidified air WA by passing the air A through the humidifying medium WM, and supplying the humidified air WA to the cap 72 through the air supply pipe 72N connected to the cap 72. Inside the supply unit 92, the air supply pipe 72N is provided in the vertical direction in a space above the liquid level of the humidifying medium WM, and a notch 72NS is provided on at least the inner surface side of the tube wall 72NW of the air supply pipe 72N. According to this structure, when the liquid level of the humidifying medium WM rises above the lower end of the air supply pipe 72N, the humidifying medium WM escapes into the notch 72NS provided in the tube wall 72NW, so that the humidifying medium WM can be prevented from entering the air supply pipe 72N. As a result, the humidifying medium WM can also be prevented from entering the cap 72. Furthermore, since the intrusion of the humidifying medium WM can be suppressed even without increasing the distance between the lower end of the air supply pipe 72N and the liquid surface of the humidifying medium WM, the size of the supply unit 92 can be reduced.

[0076] According to the maintenance device 30 of the present embodiment, the cutout 72NS is provided along the vertical direction. According to this structure, the humidifying medium WM falls along the cutout 72NS, so that the humidifying medium WM can be discharged from the air supply pipe 72N more quickly.

[0077] According to the maintenance device 30 of the present embodiment, the cutout 72NS penetrates the lower end surface of the tube wall 72NW. According to this structure, it is possible to promote the discharge of the humidifying medium WM from the air supply tube 72N.

[0078] In addition, according to the maintenance device 30 of the present embodiment, the cutout 72NS penetrates from the inner surface to the outer surface of the tube wall 72NW. According to this structure, the humidifying medium WM is discharged in the direction from the inner surface to the outer surface of the tube wall 72NW, so that the humidifying medium WM can be discharged from the air supply pipe 72N. In addition, the humidified air WA is supplied through the cutout 72NS, so the supply of the humidified air WA can be promoted.

[0079] Furthermore, according to the inkjet recording apparatus 1 of the present embodiment, a plurality of inkjet heads 12 and a maintenance device 30 are provided. According to this configuration, it is possible to suppress an increase in the viscosity of the ink in the nozzle 14N.

[0080] The above-mentioned embodiment may be modified as follows.

[0081] Fig.1672NS is a perspective view showing an air supply pipe 72N of a first modification. In this modification, the cutout 72NS penetrates the lower end of the pipe wall 72NW, but the cutout 72NS does not penetrate from the inner surface to the outer surface of the pipe wall 72NW, and the cutout 72NS is only provided on the inner surface side of the pipe wall 72NW. According to this modification, when the liquid level of the humidifying medium WM rises above the lower end of the air supply pipe 72N, the humidifying medium WM escapes into the cutout 72NS, so that the humidifying medium WM can be prevented from entering the air supply pipe 72N.

[0082] Fig.17 72NS is a perspective view showing an air supply pipe 72N of a second modification. In this modification, the cutout 72NS penetrates from the inner surface to the outer surface of the tube wall 72NW, but the cutout 72NS does not penetrate the lower end of the tube wall 72NW. According to this modification, when the liquid level of the humidifying medium WM rises to a level higher than the lower end of the air supply pipe 72N, the humidified air WA is supplied through the cutout 72NS, so that the humidified air WA can be continuously supplied. In this case, the humidified air WA flows above the liquid level, so that the humidifying medium WM can be suppressed from penetrating into the air supply pipe 72N. In addition, when the liquid level of the humidifying medium WM rises to a level higher than the lowest part of the cutout 72NS, the humidifying medium WM is discharged through the cutout 72NS, so that the humidifying medium WM can be suppressed from penetrating into the air supply pipe 72N.

[0083] The number and spacing of the slits 72NS may also be different from the above-mentioned embodiment. For example, the number of the slits 72NS may be one or more than two. In addition, when a plurality of slits 72NS are provided, the circumferential spacing of the slits 72NS may not be equal. In addition, the air supply pipe 72N may be of any shape, for example, a square cylinder.

[0084] The scope of the present invention is not limited to the above content, but is defined by the description of the claims, so it can be considered that the embodiments described in this specification are only illustrative, not limiting. Therefore, all changes that do not depart from the scope and limits of the claims, as well as contents that are equivalent to the scope and limits of the claims, are included in the scope of the claims.

Claims

1. A maintenance device, characterized in that: have: a cap mounted on the nozzle face of the inkjet head; and a supply unit storing a humidifying medium, generating humidified air by passing air through the humidifying medium, and supplying the humidified air to the cover through an air supply pipe connected to the cover, The air supply pipe is provided in the supply unit along the vertical direction in a space above the liquid level of the humidifying medium, and a notch is provided on at least the inner surface side of a pipe wall of the air supply pipe.

2. The maintenance device according to claim 1, characterized in that: The cutouts are arranged along the up-down direction.

3. The maintenance device according to claim 2, characterized in that: The cutout passes through the lower end surface of the tube wall.

4. The maintenance device according to any one of claims 1 to 3, characterized in that: The cutout passes through from the inner surface to the outer surface of the tube wall.

5. An inkjet recording device, characterized in that: have: The maintenance device according to claim 1; and A plurality of said inkjet heads.

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