Inkjet recording apparatus

Abstract

To detect an inclination of a unit having a tank for storing a liquid with an inexpensive structure.SOLUTION: An inkjet recording apparatus 1 includes: a unit (a cap unit 31) provided with a tank 92T for storing a liquid; a unit lifting device which lifts and lowers the unit; a control unit which controls the unit lifting device; and sensors 40 which detect a rise of a liquid surface in the tank 92T. The sensors 40 are provided at two positions spaced apart in a horizontal direction. The control unit determines that the unit inclines when one of the sensors 40 detects the rise of the liquid surface.SELECTED DRAWING: Figure 15

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus. [Background technology]

[0002] Inkjet recording devices include tanks that store liquid. Examples of liquid include ink, cleaning fluid used to clean the nozzle surface, and waste liquid containing ink and cleaning fluid removed from the nozzle surface. If these tanks tilt, the interior of the inkjet recording device may become contaminated with the liquid. Therefore, technologies to prevent tank tilt have been investigated. For example, Patent Document 1 discloses an image forming device that includes a liquid storage unit that stores ink, multiple non-contact sensors that detect the ink level in a single liquid storage unit, and a control unit that detects the liquid level based on the multiple liquid level heights detected by the multiple non-contact sensors. Patent Document 2 discloses an image forming device in which at least one of the main ink tank, sub-ink tank, cleaning fluid tank, first waste ink tank, and second waste ink tank is a level detection tank. The level detection tank is configured so that the liquid level of the liquid stored in the tank can be visually confirmed from the outside, and the level detection tank is provided with a scale that allows the degree of inclination of the visible liquid level relative to a horizontal plane to be visually confirmed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-32575 [Patent Document 2] JP 2020-59200 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the configurations disclosed in Patent Documents 1 and 2 have a problem in that the cost is high because a sensor for detecting tilt is provided.

[0005] SUMMARY OF THE INVENTION In consideration of the above circumstances, an object of the present invention is to detect the tilt of a unit having a tank for storing liquid with a low-cost configuration. [Means for solving the problem]

[0006] In order to solve the above problem, the inkjet recording device of the present invention comprises a unit having a tank for storing liquid, a unit lifting device for raising and lowering the unit, a control unit for controlling the unit lifting device, and a sensor for detecting a rise in the liquid level in the tank, the sensors being provided at two locations spaced horizontally apart, and the control unit determining that the unit has tilted when either of the sensors detects a rise in the liquid level.

[0007] The unit lifting devices may be provided at two locations spaced apart in the horizontal direction, and the two sensors may be provided along a direction connecting the two unit lifting devices.

[0008] The inkjet recording device may include a plurality of tanks arranged at a distance along a direction connecting the two unit lifting devices and connected to each other by communicating pipes, and the two sensors may be provided in separate tanks.

[0009] In addition, the inkjet recording device of the present invention comprises a unit having a tank for storing liquid, a unit lifting device for raising and lowering the unit, a control unit for controlling the unit lifting device, and a sensor for detecting the height of the liquid surface using a float floating on the liquid, the sensor being located at a position horizontally spaced from the center of the tank, and the control unit determining that the unit has tilted when the change in the height of the liquid surface detected by the sensor is equal to or greater than a threshold value. [Effects of the Invention]

[0010] According to the present invention, the tilt of a unit having a container for storing liquid can be detected with a low-cost configuration. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing the appearance of an image forming system according to an embodiment of the present invention; [Figure 2] 1 is a front view schematically illustrating the internal configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 3] FIG. 1 is a front view schematically showing a head unit and a maintenance device according to an embodiment of the present invention. [Figure 4] FIG. 2 is a plan view schematically showing a head unit and a wipe unit according to an embodiment of the present invention. [Figure 5] FIG. 2 is a plan view schematically showing a cap unit according to an embodiment of the present invention. [Figure 6] 1 is a cross-sectional view showing an inkjet head according to an embodiment of the present invention. [Figure 7] 10A and 10B are front views showing the operation of the maintenance device according to the embodiment of the present invention. [Figure 8] FIG. 2 is a perspective view showing a cap unit according to an embodiment of the present invention. [Figure 9] FIG. 2 is a plan view showing a cap unit according to an embodiment of the present invention. [Figure 10] FIG. 10 is a cross-sectional view showing cross section II of FIG. 9. [Figure 11] FIG. 2 is an exploded view showing a cap unit according to an embodiment of the present invention. [Figure 12] 10A and 10B are diagrams showing the flow of humidified air within a cap unit according to one embodiment of the present invention. [Figure 13] FIG. 2 is a plan view showing the positions of a supply unit and a recovery unit according to an embodiment of the present invention. [Figure 14] 5 is a cross-sectional view showing the flow of humidified air inside a cap according to one embodiment of the present invention. FIG. [Figure 15] FIG. 2 is a perspective view showing a sensor provided in the tank. [Figure 16] 10A and 10B are diagrams illustrating the tilt of a tank during lifting and lowering by a unit lifting device according to an embodiment of the present invention. [Figure 17] 10A and 10B are diagrams illustrating the inclination of a tank during lifting and lowering by a unit lifting device according to a modified example of an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] An inkjet recording apparatus 1 according to one embodiment of the present invention will be described below with reference to the drawings.

[0013] FIG. 1 is a perspective view showing the appearance of an image forming system 100. FIG. 2 is a front view schematically showing the internal configuration of an inkjet recording apparatus 1. FIG. 3 is a front view schematically showing a head unit 11 and a maintenance device 30. FIG. 4 is a plan view schematically showing a head unit 11 and a wiping unit 32. FIG. 5 is a plan view schematically showing a cap unit 31. FIG. 6 is a cross-sectional view showing an inkjet head 12. FIG. 7 is a front view showing the operation of the maintenance device 30. In the following description, the front side of the paper in FIG. 2 is the front side (front side) of the inkjet recording apparatus 1, 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 represent up, down, left, right, front, and rear, respectively.

[0014] The image forming system 100 (see FIG. 1) includes a paper feeder 110, an inkjet recording apparatus 1, a drying apparatus 120, and a post-processing apparatus 130. The paper feeder 110 stores several thousand sheets and supplies the sheets to the inkjet recording apparatus 1. The inkjet recording apparatus 1 forms an image on the sheets using an inkjet method. The drying apparatus 120 heats the sheets conveyed from the inkjet recording apparatus 1 to dry the ink. The post-processing apparatus 130 performs post-processing such as punching, stapling, and folding on the sheets conveyed from the drying apparatus 120.

[0015] The inkjet recording device 1 (see FIG. 2) includes a rectangular parallelepiped main housing 3. A transport unit 7 that adsorbs and transports a sheet in the Y direction is provided in the center of the main housing 3. An imaging unit 6 that ejects ink to form an image is provided above the transport unit 7. A paper feed opening 8 that introduces a sheet from a paper feed device 110 is provided on the right side of the main housing 3. A discharge opening 9 that discharges the sheet on which an image has been formed to a drying device 120 is provided on the left side of the main housing 3. A transport path 10 is provided inside the main housing 3, extending from the paper feed opening 8 through the gap between the transport unit 7 and the imaging unit 6 to the discharge opening 9. A registration roller 18 is provided upstream of the transport unit 7 in the transport direction Y.

[0016] The transport unit 7 includes an endless transport belt 21 and a suction unit 24. The transport belt 21 has a number of air holes (not shown) and is wound around a drive roller 25 and a driven roller 22. The upper surface of the suction unit 24 has a number of air holes (not shown) and is in contact with the inner surface of the transport belt 21. The suction unit 24 sucks air through the air holes of the transport belt 21 and the suction unit 24, thereby adsorbing the sheet to the transport belt 21. The drive roller 25 is driven counterclockwise by a drive unit (not shown) including a motor and a reduction gear, causing the transport belt 21 to rotate counterclockwise, and the sheet adsorbed to the transport belt 21 is transported in the Y direction.

[0017] The imaging unit 6 includes a plurality of (four in this embodiment) head units 11. Each head unit 11 (see FIGS. 3 and 4) includes one or more (three in this embodiment) inkjet heads 12. Each head unit 11 is connected to an ink container 20 filled with black, cyan, magenta, or yellow ink, respectively.

[0018] The inkjet head 12 (see FIG. 6) includes a rectangular parallelepiped housing 12H with its longitudinal direction extending in the front-to-rear direction, a nozzle plate 14 provided below the housing 12H, and a socket 12S to which a pipe for supplying ink is connected. The nozzle plate 14 includes a number of nozzles 14N arranged in the front-to-rear direction. The nozzles 14N include branch flow paths 14B branching from the downstream side of the socket 12S and ejection ports 14A provided in a nozzle surface 14F, which is the lower surface of the nozzle plate 14. A vibration plate 14V also serves as part of the inner wall of the branch flow path 14B. A pressure element 14Z is provided on the vibration plate 14V. The pressure element 14Z may be a piezoelectric element, an electrostatic actuator, a heater, or the like. A drive circuit 12D that drives the pressure element 14Z is connected to the pressure element 14Z.

[0019] The control unit 2 (see FIG. 2) includes a calculation unit and a storage unit (not shown). The calculation unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The calculation unit performs various processes by reading and executing control programs stored in the storage unit. Note that the control unit 2 may be realized by an integrated circuit that does not use software.

[0020] A display operation unit 19 is provided on the top of the main body housing 3 (see FIGS. 1 and 2). The display operation unit 19 includes a display panel, a touch panel stacked on the display panel, and a keypad (not shown). The control unit 2 displays a screen showing the operation menu and status of the inkjet recording device 1 on the display panel, and controls each part of the inkjet recording device 1 in response to operations detected by the touch panel and the keypad.

[0021] The basic image formation operation of the inkjet recording apparatus 1 is as follows. When an image formation job is input to the inkjet recording apparatus 1 from the display operation unit 19, an external computer, or the like, the paper feeder 110 feeds a sheet into the conveyance path 10 through the paper feed port 8, and the registration rollers 18, whose rotation has been stopped, correct any skew of the sheet. When the registration rollers 18 feed the sheet to the conveyance unit 7 at a predetermined timing, the conveyance unit 7 attracts 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, and an image is formed. The sheet with the image formed is discharged to the drying device 120 through the discharge port 9.

[0022] [Maintenance equipment] Next, we will explain the maintenance device 30. Since the four head units 11 have the same configuration and the four maintenance devices 30 have the same configuration, the following will explain one head unit 11 and one maintenance device 30 provided to the right of it.

[0023] The head unit 11 includes a head base 11B (see FIGS. 3 and 4) that supports the inkjet heads 12. Three inkjet heads 12 are provided in a staggered arrangement on the head base 11B.

[0024] The maintenance device 30 (see FIG. 3) is provided on the side (the right side in this embodiment) of the head unit 11. The maintenance device 30 includes a cap unit 31 and a wipe unit 32.

[0025] [Cap Unit] The cap unit 31 (see FIGS. 3 and 5) has caps 72 in the same number as the inkjet heads 12 included in 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 FIGS. 8 to 11). Two caps 72 are arranged front to back on the right side of the center in the left-right direction of the frame 71, and one cap 72 is arranged on the left side. The one left cap 72 is arranged midway between the two right caps 72 in the front-to-back direction.

[0026] [Wipe unit] The wiping unit 32 (see FIGS. 3 and 4) includes a waste liquid tray 81 and a cleaning member 82. The waste liquid tray 81 includes recesses 81U, the number of which is the same as the number of inkjet heads 12 included in the head unit 11. The recesses 81U are arranged in a staggered pattern, similar to the inkjet heads 12. A cleaning member 82 is provided in each recess 81U. The cleaning member 82 is, for example, a blade. The waste liquid tray 81 includes a drive unit (not shown) that slides the cleaning member 82 along the nozzle surface 14F. The waste liquid tray 81 is placed on a plurality of caps 72. In other words, the wiping unit 32 is placed on the cap unit 31. The head unit 11 is provided with a cleaning liquid supply device 13 (see FIG. 6) that supplies cleaning liquid to the nozzle surface 14F.

[0027] [Head lifting device] The head lifting device 11L (see FIG. 4) is provided in front of and behind the head base 11B. The head lifting device 11L is configured, for example, with a ball screw, a belt drive device, or the like. The head lifting device 11L lifts and lowers the head unit 11 between an image forming position and a retracted position. The image forming position (see FIG. 7A) is a position where the distance between the conveyance path 10 (the upper surface of the conveyance belt 21) along 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 range in which the head unit 11 is lifted and lowered by the head lifting device 11L. The retracted position (see FIG. 7B) is a position where the head unit 11 does not interfere with the wiping unit 32 when the cap unit 31 and the wiping unit 32 are slid using a cap slide device 34 (described later). The retracted position is the upper limit of the range in which the head unit 11 is lifted and lowered.

[0028] [Cap slide device] The cap slide device 34 (see FIG. 5) is provided in front of and behind the frame body 71 of the cap unit 31. The cap slide device 34 is composed of, for example, a ball screw, a belt drive device, etc. The cap slide device 34 slides the cap unit 31 to a home position and a maintenance position. The home position (see FIG. 7(A)) is a position to the right of the head unit 11 located in the image forming position. The maintenance position (see FIG. 7(F)) is a position below the head unit 11 located in the retracted position.

[0029] [Wiping lifting device] The wipe lifting device 35 (see FIG. 4) is provided in front of and behind the waste liquid tray 81 of the wiping unit 32. The wipe lifting device 35 is configured, for example, with a ball screw, a belt drive device, or the like. The wipe lifting device 35 raises and lowers the wiping unit 32 between a contact position (see FIG. 7(B)) where the waste liquid tray 81 contacts the cap 72 and a separated position (see FIG. 7(E)) where the waste liquid tray 81 is separated a predetermined distance from the cap 72.

[0030] [Unit lifting device] The head lifting device 11L, the cap slide 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 slide device 34. The wipe unit 32 is supported by the frame 36F via the wipe lifting device 35.

[0031] 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 body housing 3. The unit lifting devices 36 are configured, for example, with a ball screw, a belt drive device, or the like, and raise and lower the frame 36F. That is, 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 formation is performed by the head unit 11 or maintenance is performed by the maintenance device 30, the frame 36F is positioned at the normal position (see FIGS. 7A to 7G). When a sheet is jammed on the conveyor belt 21, the frame 36F is positioned at the retracted position (see FIG. 7H) to facilitate sheet removal, and the gap between the conveyor belt 21 and the frame 36F is widened.

[0032] Next, the configuration of the cap unit 31 will be described in detail. Fig. 8 is a perspective view showing the cap unit 31. Fig. 9 is a plan view showing the cap unit 31. Fig. 10 is a cross-sectional view showing cross section II of Fig. 9. Fig. 11 is an exploded view showing the cap unit 31. Fig. 12 is a diagram showing the flow of air A and humidified air WA within 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 within the cap 72.

[0033] The maintenance device 30 of this embodiment comprises a plurality of caps 72 attached to the nozzle surface 14F of the inkjet head 12, an air intake port 72NA and an air exhaust port 72EA provided in each of the plurality of caps 72, one collection section 94 that collects air A from the exhaust ports 72EA of all the caps 72, and a plurality of supply sections 92 provided for each cap 72 that supply humidified air WA, which is air A collected by the collection section 94 and humidified, to the air intake port 72NA, the plurality of supply sections 92 being arranged around the single collection section 94, and in each of the plurality of caps 72, the exhaust port 72EA is provided on the collection section 94 side and the air intake port 72NA is provided on the supply section 92 side.

[0034] The multiple caps 72 include a first cap 721, a second cap 722, and a third cap 723, the first cap 721 and the second cap 722 being arranged along a predetermined direction (for example, the front-to-rear direction), the third cap 723 being arranged at a position intermediate between the first cap 721 and the second cap 722 in the predetermined direction, and being arranged at a position different from the first cap 721 and the second cap 722 in a direction intersecting the predetermined direction, and the exhaust port 72EA of the first cap 721 being provided on the second cap 722 side, and the exhaust port 72EA of the second cap 722 being provided on the first cap 721 side.

[0035] [cap] The cap 72 (see Figures 8 to 10) is formed in a box shape that opens upward. The cap 72 has a roughly rectangular bottom 72B with the longitudinal direction extending in the front-to-rear direction, and sidewalls 72W that extend upright from the edges of the bottom 72B. The sidewalls 72W are formed of a flexible material such as rubber. An air inlet 72NA and an exhaust outlet 72EA are provided in the bottom 72B. The right rear and left caps 72 have the air inlet 72NA on the rear side and the exhaust outlet 72EA on the front side. The right front cap 72 has the air inlet 72NA on the front side and the exhaust outlet 72EA on the rear side.

[0036] 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. 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. Note that the second cap 722 may have an exhaust port 72EA on the front side and an air intake port 72NA on the rear side.

[0037] [Supply section, collection section] Below the frame 71 (see FIGS. 8, 11 to 13), there are provided supply units 92, the same number as the caps 72 (three in this embodiment), and one recovery unit 94. The supply units 92 have tanks 92T. The recovery unit 94 has tanks 94T. The supply units 92 and the recovery unit 94 are supported by the frame 91. Each supply unit 92 is disposed below the air supply port 72NA of each cap 72. The recovery unit 94 has a shape that overlaps with all the exhaust ports 72EA in a plan view, and is disposed below all the exhaust ports 72EA.

[0038] In other words, the three supply units 92 are arranged around one collection unit 94, and in each of the three caps 72, the exhaust port 72EA is provided on the collection unit 94 side, and the intake port 72NA is provided on the supply unit 92 side. In other words, all of the exhaust ports 72EA overlap with the collection unit 94 in the vertical direction, and in each of the multiple caps 72, the intake port 72NA overlaps with the supply unit 92 in the vertical direction.

[0039] Tank 92T has an opening 92A that opens upward (see FIG. 11). Tank 94T has an opening 94A that opens upward. Tank 92T and tank 94T are joined to the lower surface of frame 71. That is, openings 92A and 94A are closed by frame 71. In other words, frame 71 also serves as the ceiling of tank 92T and tank 94T.

[0040] An air intake pipe 72N (see FIG. 10) that connects the cap 72 to the supply unit 92 below it is connected to the air intake port 72NA of each cap 72. An exhaust pipe 72E that connects the cap 72 to the collection unit 94 is connected to the exhaust port 72EA of each cap 72. In other words, three caps 72 are connected to the collection unit 94.

[0041] 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.

[0042] The air pump 95 is connected to the recovery unit 94 by a recovery passage 95E (see FIGS. 8, 9, and 11), and is connected to all of the supply units 92 by a supply passage 95N. The air pump 95 recovers air A whose water vapor pressure has decreased from the recovery unit 94 via the recovery passage 95E, and supplies the recovered air A to all of the supply units 92 via the supply passage 95N (see FIG. 12).

[0043] All of the supply units 92 are connected to a 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. The tank 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 sub-tank 93.

[0044] The sub-tank 93 is provided with a sensor 93S (see FIGS. 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 surface in the sub-tank 93. The supply unit 92 is provided with a first heating unit 92H (see FIG. 10) that heats the supply unit 92. The cap 72 is provided with a second heating unit 72H that heats the cap 72. The supply unit 92 is provided with a sensor 92S that measures the temperature inside the supply unit 92. The cap 72 is provided with a sensor 72S that measures the temperature inside the cap 72. The collection unit 94 is provided with a sensor 94S that measures at least one of the temperature and humidity inside the collection unit 94.

[0045] Next, the basic operation of the maintenance device 30 will be described. In the initial state (see FIG. 7(A)), the frame 36F is located in the normal position, the head unit 11 is located in the image forming position, and the cap unit 31 is located 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 executes the following process at a predetermined timing. The predetermined timing is, for example, a timing when an increase in the viscosity of the ink in the nozzle 14N is expected, and specifically, when a predetermined period of time has passed since an image formation job was not executed.

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

[0047] Next, the control unit 2 forcibly ejects a predetermined amount of ink from the inkjet head 12 (purging process), supplies cleaning liquid 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 liquid, and waste liquid containing the ink and cleaning liquid is scraped off by the cleaning member 82 and falls into the waste liquid tray 81.

[0048] Next, the control unit 2 activates the head lifting device 11L to raise the head unit 11 to the retracted position (see FIG. 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 FIG. 7(B)).

[0049] 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.

[0050] 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 comes into contact with the cap 72 (see FIG. 7(G)). In this way, the cap 72 is attached to the nozzle surface 14F.

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

[0052] The air pump 95 (see FIG. 12) recovers air A with reduced water vapor pressure from the recovery unit 94 via the recovery flow path 95E and supplies the recovered air A to all of the supply units 92 via the supply flow path 95N. The end of the supply flow path 95N on the supply unit 92 side is located below the liquid level of the humidifying medium WM (see FIG. 14). Therefore, in the supply unit 92, air A is blown into the humidifying medium WM, generating bubbles B. The water vapor pressure of the bubbles B increases before the bubbles B rise to the liquid surface. Furthermore, because 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.

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

[0054] In addition to the above controls, the control unit 2 controls the temperature of each unit. Specifically, each inkjet head 12 is provided with a sensor (not shown) that measures the temperature of the inkjet head 12 (for example, the temperature of ink in the nozzles 14N). As described above, the supply unit 92 is provided with a first heating unit 92H (see FIG. 10) that heats the supply unit 92. The cap 72 is provided with a second heating unit 72H that heats the cap 72. The supply unit 92 is provided with a sensor 92S that measures the temperature inside the supply unit 92. The cap 72 is provided with a sensor 72S that measures the temperature inside the cap 72. The collection unit 94 is provided with a sensor 94S that measures at least one of the temperature and humidity inside the collection unit 94.

[0055] The control unit 2 monitors the measurement value by the sensor 92S and controls the first heating unit 92H so that the temperature of the supply unit 92 is equal to or higher than the temperature of the inkjet head 12. If the temperature of the supply unit 92 is lower than the temperature of the inkjet head 12, the humidity of the humidified air WA supplied from the supply unit 92 may be lower than that inside the nozzles 14N of the inkjet head 12, in which case the humidifying effect on the ink inside the nozzles 14N cannot be obtained. In contrast, in this embodiment, humidified air WA with a higher humidity than that inside the nozzles 14N of the inkjet head 12 is supplied.

[0056] Furthermore, the control unit 2 monitors the measurement value from the sensor 72S and controls the second heating unit 72H so that the temperature of the cap 72 is equal to or higher than the temperature of the supply unit 92. If the temperature of the cap 72 is lower than the temperature of the supply unit 92, the temperature of the humidified air WA supplied from the supply unit 92 will drop inside the cap 72. If the temperature of the humidified air WA drops below the dew point, condensation will occur, reducing the humidity inside the cap 72 and preventing the humidifying effect from being obtained. In contrast, in this embodiment, the temperature of the humidified air WA does not drop inside the cap 72, so there is no risk of condensation reducing the humidity inside the cap 72.

[0057] When an image forming job is to be executed, the control unit 2 activates the head lifting device 11L to raise the head unit 11 to the retracted position (see FIG. 7(F)), activates the cap slide device 34 to slide the cap unit 31 to the home position (see FIG. 7(E)), and activates the wipe lifting device 35 to lower the wipe unit 32 to the contact position (see FIG. 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 FIG. 7(A)), and executes the image forming job.

[0058] If a sheet becomes jammed between the conveyor belt 21 and the frame 36F during image formation, the control unit 2 operates the unit lifting device 36 to raise the frame 36F to the retracted position (see FIG. 7(H)). When the user removes the sheet and instructs the display / operation unit 19 to resume image formation, the control unit 2 operates the unit lifting device 36 to lower the frame 36F to the normal position (see FIG. 7(A)), and resumes the image formation job.

[0059] When raising and lowering the frame 36F, the control unit 2 synchronizes the driving of the front and rear unit lifting devices 36 to keep the frame 36F level. However, the frame 36F may still tilt. For example, this may occur if a foreign object gets caught in one of the front or rear unit lifting devices 36, or if one of the front or rear unit lifting devices 36 malfunctions due to aging. If the frame 36F tilts, the humidified medium WM stored in the tank 92T, the waste liquid accumulated in the waste liquid tray 81 of the wiping unit 32, or the humidified medium WM condensed inside the cap 72 may leak, potentially contaminating the interior of the inkjet recording apparatus 1. Therefore, in this embodiment, a configuration is provided to detect the tilt of the frame 36F.

[0060] 15 is a perspective view showing the sensor 40 provided in the tank 92T. Of the three tanks 92T, the sensor 40 is provided in the tank 92T below the first cap 721 and the second cap 722. In other words, the two sensors 40 are provided in the front-to-rear direction, i.e., along the direction connecting the two unit lifting devices 36. As described above, the multiple tanks 92T are connected by the communicating pipes 92C, so the liquid levels of the humidifying medium WM in the multiple tanks 92T are the same.

[0061] The sensor 40 is provided near the upper edge of the side wall of the tank 92T. The sensor 40 detects a rise in the liquid level, for example, by a change in electrical resistance when the humidifying medium WM enters between two electrodes. The sensor 40 is preferably placed at the farthest point on the wall surface of the two tanks 92T from each other in the front-to-rear direction.

[0062] 16A and 16B are diagrams showing the inclination of the tank 92T during lifting by the unit lifting device 36. Of these, (A) shows a case where the tank 92T is not inclined, and neither the front nor the rear sensors 40 detects a rise in the liquid level relative to the tank 92T. In this case, the front and rear unit lifting devices 36 are operating evenly.

[0063] (B) shows a case where the rear side is tilted low, and the rear sensor 40 detects a rise in the liquid level relative to the tank 92T. In this case, if the rise continues, there is a risk of liquid leaking from the rear tank 92T, so the control unit 2 stops the front unit lifting / lowering device 36 and operates the rear unit lifting / lowering device 36 until the rear sensor 40 no longer detects a relative rise in the liquid level.

[0064] (C) shows a case where the front side is tilted low, and the front sensor 40 detects a rise in the liquid level relative to the tank 92T. In this case, if the rise continues, there is a risk of liquid leaking from the front tank 92T, so the control unit 2 stops the rear unit lifting / lowering device 36 and operates the front unit lifting / lowering device 36 until the front sensor 40 no longer detects a relative rise in the liquid level.

[0065] The inkjet recording apparatus 1 according to the present embodiment described above includes a unit (cap unit 31) having a tank 92T for storing liquid, a unit lifting device 36 for raising and lowering the unit, a control unit 2 for controlling the unit lifting device 36, and a sensor 40 for detecting a rise in the liquid level in the tank 92T. The sensors 40 are provided at two locations spaced apart horizontally, and the control unit 2 determines that the unit has tilted when either sensor 40 detects a rise in the liquid level. In general, the sensor 40 for detecting a rise in the liquid level is less expensive than a sensor for detecting the tilt of the tank 92T. Therefore, according to this embodiment, the tilt of a unit having a tank 92T for storing liquid can be detected with a low-cost configuration.

[0066] Furthermore, according to the inkjet recording apparatus 1 of this embodiment, the unit lifting devices 36 are provided at two locations spaced apart in the horizontal direction, and the two sensors 40 are provided along a direction connecting the two unit lifting devices 36. According to this embodiment, when the unit lifting devices 36 are provided at two locations spaced apart in the horizontal direction, the tilt of the unit can be detected with high accuracy.

[0067] Furthermore, the inkjet recording apparatus 1 according to this embodiment is provided with a plurality of tanks 92T that are spaced apart along the direction connecting the two unit lifting devices 36 and are connected to each other by communicating pipes 92C, and the two sensors 40 are provided in the separate tanks 92T. According to this embodiment, when a plurality of tanks 92T that are connected to each other by communicating pipes 92C are provided, the tilt of the unit can be detected with high accuracy.

[0068] The above embodiment may be modified as follows.

[0069] 17 is a diagram showing the inclination of the tank 92T during lifting by the unit lifting device 36. In this modification, instead of the two sensors 40 of the above embodiment, a single sensor 40 is provided that detects the liquid level using a float floating on the liquid. The sensor 40 is provided at a position horizontally spaced from the center of the tank 92T, and the control unit 2 determines that the unit has tilted when the change in the liquid level detected by the sensor 40 is equal to or greater than a threshold value. According to this modification, the inclination of the unit can be detected with a simple and low-cost configuration.

[0070] In the above embodiment, an example is shown in which multiple tanks 92T are connected to each other by communicating pipes 92C and two sensors 40 are provided in separate tanks 92T, but sensors 40 may also be provided in two locations horizontally spaced apart on one tank 92T. [Explanation of symbols]

[0071] 1. Inkjet recording device 31 Cap Unit (Unit) 36 Unit lifting device 40 sensors 92T Tank

Claims

1. a unit having a tank for storing a liquid; a unit lifting device that lifts and lowers the unit; a control unit for controlling the unit lifting device; a sensor for detecting a rise in the liquid level in the tank; The sensors are provided at two locations spaced apart in the horizontal direction, The inkjet recording apparatus is characterized in that the control unit determines that the unit is tilted when any of the sensors detects a rise in the liquid level.

2. The unit lifting devices are provided at two locations spaced apart in the horizontal direction, 2. The inkjet recording apparatus according to claim 1, wherein the two sensors are provided along a direction connecting the two unit lifting devices.

3. a plurality of the tanks arranged at intervals along a direction connecting the two unit lifting devices and connected to each other by communication pipes; 3. The ink jet recording apparatus according to claim 2, wherein the two sensors are provided in different tanks.

4. a unit having a tank for storing a liquid; a unit lifting device that lifts and lowers the unit; a control unit for controlling the unit lifting device; a sensor that detects the height of the liquid surface using a float that is floated on the liquid; The sensor is provided at a position spaced horizontally from the center of the tank, The inkjet recording apparatus is characterized in that the control unit determines that the unit has tilted when a change in the height of the liquid surface detected by the sensor is equal to or greater than a threshold value.

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