Inkjet recording device

Abstract

To provide an inkjet recording device that is improved in capability of removing an adhering matter from a nozzle surface.SOLUTION: An inkjet recording device comprises: an inkjet head 12; an immersion tank 81 that stores washing liquid; a lifting device that lifts up and down the immersion tank 81 or the inkjet head 12 to immerse a nozzle surface of the inkjet head 12 into washing liquid; and a removing device 32, provided on the immersion tank 81, which removes an adhering matter from the nozzle surface. A driving device 85 that drives the removing device 32 is provided on a position that is higher than a maximum height of a liquid level of liquid that can be stored in the immersion tank 81. A washing liquid supply device supplies washing liquid so that the liquid level is in a predetermined range which is upper than the nozzle surface.SELECTED DRAWING: Figure 13

Description

Technical Field

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

Background Art

[0002] In an inkjet recording apparatus, it is conceivable that moisture evaporates from the ink in the nozzles of the inkjet head during a period when an image forming job is not being executed, and the nozzles become clogged due to an increase in the viscosity of the ink. Therefore, a purge process is performed to discharge the ink in the nozzles into a cap for the purpose of preventing clogging. However, if the ink remaining on the nozzle surface is left unattended, there are problems such as ink dropping onto the sheet or the ink sticking to the nozzle surface during the execution of an image forming job. Therefore, techniques for removing the ink remaining on the nozzle surface have been studied. For example, in Patent Document 1, a configuration has been proposed in which ink is removed from the nozzle surface by sliding a blade that contacts the nozzle surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration disclosed in Patent Document 1, the cleaning liquid bulges out from the holes of the supply member adjacent to the nozzle surface, and the blade scrapes up the cleaning liquid and then slides along the nozzle surface. Therefore, there is a problem that the amount of the cleaning liquid supplied to the nozzle surface is small and the ability to remove deposits from the nozzle surface is low.

[0005] In view of the above circumstances, an object of the present invention is to improve the ability to remove deposits from the nozzle surface.

Means for Solving the Problems

[0006] To solve the above problems, an inkjet recording apparatus according to the present invention includes an inkjet head, an immersion tank for storing a cleaning liquid, a lifting device for immersing a nozzle surface of the inkjet head in the cleaning liquid by lifting and lowering the immersion tank or the inkjet head, and a removing device provided in the immersion tank for removing deposits from the nozzle surface.

[0007] The inkjet recording apparatus may include a driving device for driving the removing device, and the driving device may be provided at a position higher than a maximum height of a liquid level that can be stored in the immersion tank.

[0008] The inkjet recording apparatus may include a cleaning liquid supply device for supplying a cleaning liquid to the immersion tank, and the cleaning liquid supply device may supply the cleaning liquid so that a liquid level is positioned within a predetermined range above the nozzle surface.

[0009] The lifting device may maintain a state in which the nozzle surface is immersed in the cleaning liquid during a period when image formation by the inkjet head is not performed.

[0010] When performing image formation by the inkjet head, the lifting device may lift and lower the immersion tank or the inkjet head to a position where the nozzle surface is not immersed in the cleaning liquid.

[0011] The removing device includes a blade that removes deposits by sliding in one direction along the nozzle surface, the driving device includes a driving source that generates a driving force, and the driving source may be provided on a side closer to a sliding start position than a sliding end position of the blade.

[0012] The immersion tank may include a heater for heating the cleaning liquid.

Advantages of the Invention

[0013] According to the present invention, the ability to remove deposits from the nozzle surface can be improved.

Brief Description of the Drawings

[0014]

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Embodiments for Carrying Out the Invention

[0015] Next, an inkjet recording apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings.

[0016] First, the overall configuration of the inkjet recording apparatus 1 will be described. FIG. 1 is a front view schematically showing the internal configuration of the inkjet recording apparatus 1. FIG. 2 is a perspective view showing the arrangement of the inkjet head 12. FIG. 3 is a cross-sectional view showing the inkjet head 12. FIG. 4 is a diagram schematically showing the configuration of the ink supply unit 60. Hereinafter, the front side (front side) of the inkjet recording apparatus 1 will be the front side of the paper in FIG. 1, and the left and right directions will be described based on the direction of viewing the inkjet recording apparatus 1 from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate up, down, left, right, front, and rear, respectively.

[0017] The inkjet recording apparatus 1 (see FIG. 1) includes a rectangular parallelepiped main body housing 3. Inside the lower part of the main body housing 3, there are provided a paper feed cassette 4 for accommodating single-sheet sheets S such as plain paper and coated paper, and a paper feed roller 5 for feeding the sheet S to the right from the paper feed cassette 4. Above the paper feed cassette 4, a transport unit 7 for adsorbing the sheet S and transporting it in the Y direction is provided. Above the transport unit 7, an image forming unit 6 for discharging ink to form an image is provided. In the upper right part of the main body housing 3, a discharge roller 8 for discharging the sheet S on which an image is formed and a discharge tray 9 on which the discharged sheet S is stacked are provided.

[0018] Inside the main body housing 3, a transport path 10 is provided that extends from the paper feed roller 5 through the gap between the transport unit 7 and the image forming unit 6 to the discharge roller 8. The transport path 10 is mainly formed by plate-like members facing each other with a gap for passing the sheet S, and transport rollers 17 for sandwiching and transporting the sheet S are provided at a plurality of locations in the transport direction Y. A registration roller 18 is provided on the upstream side in the transport direction Y from the image forming unit 6.

[0019] The conveying unit 7 includes an endless conveyor belt 21, a support plate 23, and a suction unit 24. The conveyor belt 21 has a number of ventilation holes (not shown) and is wound around a driving roller 25 and a driven roller 22. The support plate 23 has a number of ventilation holes, and its upper surface is in contact with the inner surface of the conveyor belt 21. The suction unit 24 sucks air through the ventilation holes of the support plate 23 and the conveyor belt 21 to adsorb the sheet S onto the conveyor belt 21. The driving roller 25 is driven in the counterclockwise direction by a driving unit (not shown) including a motor and a reduction gear, so that the conveyor belt 21 rotates in the counterclockwise direction, and the sheet S adsorbed on the conveyor belt 21 is conveyed in the Y direction.

[0020] The image forming unit 6 includes head units 11Y, 11Bk, 11C, and 11M (collectively referred to as the head unit 11). The head unit 11 includes one or more inkjet heads 12, for example, three inkjet heads 12 arranged staggeredly (see FIG. 2). Ink containers 20Y, 20Bk, 20C, and 20M (collectively referred to as the ink container 20) filled with yellow, black, cyan, and magenta inks are connected to the head units 11Y, 11Bk, 11C, and 11M, respectively.

[0021] The inkjet head 12 (see FIG. 3) includes a rectangular parallelepiped housing 12H having a longitudinal direction in the front-rear direction, a nozzle plate 14 provided at the bottom of the housing 12H, and a socket 12S to which a pipe for supplying ink is connected. The nozzle plate 14 includes a number of nozzles 14N arranged in the front-rear direction. The nozzle 14N includes a branch flow path 14B branched from the downstream side of the socket 12S and a discharge port 14A provided on the nozzle surface 14F which is the lower surface of the nozzle plate 14. The diaphragm 14V also serves as a part of the inner wall of the branch flow path 14B. A pressurizing element 14Z is provided on the diaphragm 14V. As the pressurizing element 14Z, a piezoelectric element, an electrostatic actuator, a heater, etc. are used. A drive circuit 12D for driving the pressurizing element 14Z is connected to the pressurizing element 14Z.

[0022] The inkjet recording apparatus 1 includes an ink supply unit 60 (see FIG. 4). In this figure, an ink supply unit 60 corresponding to one color of ink is shown. However, in the present embodiment, since four colors of ink are used, four similar ink supply units 60 are provided. The inkjet recording apparatus 1 includes a container mounting portion 61 on which an ink container 20 is mounted, a filter 62 for filtering ink, a pump 63 for sucking ink from the ink container 20 through the filter 62, and a sub-tank 64 for storing the ink sent out from the pump 63.

[0023] The liquid level in the sub-tank 64 is adjusted to be slightly lower than the nozzle surface 14F. Due to the head difference between the liquid level and the nozzle surface 14F, a negative pressure acts on the ink in the nozzle 14N, and a meniscus is formed in the nozzle 14N. After the ink is ejected from the inkjet head 12, the surface tension of the ink acts to reduce the surface area of the meniscus, and due to the negative pressure generated thereby, the reduced amount of ink is drawn from the sub-tank 64 into the inkjet head 12.

[0024] The control unit 2 (see FIG. 1) includes an arithmetic unit and a storage unit (not shown). The arithmetic unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The arithmetic unit performs various processes by reading and executing the 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.

[0025] On the upper part of the main body housing 3, a display operation unit 19 is provided (see Fig. 1). The display operation unit 19 includes a display panel, a touch panel laminated on the display panel, and a keypad (not shown). The control unit 2 causes the display panel to display a screen representing the operation menu, status, etc. of the inkjet recording apparatus 1, and controls each part of the inkjet recording apparatus 1 according to the operations detected by the touch panel and the keypad.

[0026] The basic image forming operation of the inkjet recording apparatus 1 is as follows. When an image forming job is input to the inkjet recording apparatus 1 from the display operation unit 19 or an external computer, etc., the paper feed roller 5 sends out the sheet S from the paper feed cassette 4 to the conveyance path 10, and the registration roller 18 whose rotation has been stopped corrects the skew of the sheet S. When the registration roller 18 sends out the sheet S to the conveyance unit 7 at a predetermined timing, the conveyance unit 7 sucks the sheet S onto the conveyance belt 21 and conveys it in the Y direction. The drive circuit 12D supplies a discharge signal corresponding to the image data to the pressure element 14Z in synchronization with the conveyance of the sheet S. Thus, ink is discharged from the nozzles 14N, and an image is formed on the sheet S. The discharge roller 8 discharges the sheet S on which the image has been formed to the discharge tray 9.

[0027] [Maintenance Device] Fig. 5 is a block diagram showing the electrical configuration of the maintenance device 30. Figs. 6 to 9 are perspective views showing the maintenance device 30. The maintenance device 30 includes a frame 33, a carriage 34, a removal device 32, a lifting device 35, and a slide device 36.

[0028] [Frame, Carriage] The frame 33 (see Fig. 6) is fixed to the main body housing 3 and supports the carriage 34 and the conveyance unit 7. The carriage 34 supports the removal device 32. The removal device 32 includes a blade 82.

[0029] [Lifting Device] The conveyance unit 7 is supported by the frame 33 via a lifting device 35 (see FIG. 5). The lifting device 35 is composed of, for example, a ball screw, a belt drive device, or the like. The lifting device 35 raises and lowers the conveyance unit 7 between an image forming position (see FIG. 6) when image formation is performed and a lower retracted position (see FIG. 7) below the image forming position. When moving the conveyance unit 7 to the image forming position, the conveyance unit 7 is positioned so that the distance between the conveyance belt 21 and the nozzle surface 14F becomes a distance suitable for image formation. When moving the conveyance unit 7 to the lower retracted position, a space is formed that allows the removal device 32 to be moved between the upper surface of the conveyance belt 21 and the nozzle surface 14F.

[0030] [Slide device] The carriage 34 is supported by the frame 33 via a slide device 36 (see FIG. 5). The slide device 36 is composed of, for example, a ball screw, a belt drive device, a rack and pinion, or the like. The removal device 32 is supported by the carriage 34 and slides horizontally together with the carriage 34 by the slide device 36. When the conveyance unit 7 is in the lower retracted position, the slide device 36 slides the removal device 32 between a lateral retracted position (see FIG. 7) where it does not face the image forming unit 6 and an opposing position (see FIG. 8) where it faces the image forming unit 6.

[0031] In the opposing position, the removal device 32 can be raised and lowered using the conveyance unit 7. Specifically, the conveyance unit 7 can be raised and lowered inside the carriage 34 with the removal device 32 placed on top of the conveyance unit 7. The lifting device 35 raises and lowers the removal device 32 between a separated position (see FIG. 8) where the blade 82 is separated from the nozzle surface 14F and a contact position (see FIG. 9) where the blade 82 contacts the nozzle surface 14F.

[0032] [Removal device] FIG. 10 is a perspective view showing the removing device 32. FIG. 11 is a perspective view showing the blade unit 84. FIGS. 12 and 13 are perspective views showing a cross section of the removing device 32. FIGS. 14 to 16 are cross-sectional views showing the removing device 32. The removing device 32 includes an immersion tank 81 and a blade unit 84 that slides with respect to the immersion tank 81.

[0033] [Immersion tank] The immersion tank 81 is fixed to the carriage 34 (see FIG. 6). The immersion tank 81 (see FIGS. 10 to 16) includes a rectangular bottom 81B when viewed from above and upright side wall portions 81S provided over the entire circumference at the front, rear, left, and right edges of the bottom 81B. In other words, the immersion tank 81 is open on the inkjet head 12 side. A cleaning liquid is stored in the immersion tank 81.

[0034] [Blade unit] The blade unit 84 (see FIG. 13) includes a blade 82 and a support plate 83 that supports the blade 82. The blade 82 is a flexible plate-like member formed of rubber or the like. A plurality (12 in this embodiment) of blades 82 are arranged in the same positional relationship as the inkjet head 12. The support plate 83 includes a bottom 83B, upright side wall portions 83S provided at both left and right ends of the bottom 83B, and flange portions 83F protruding leftward and rightward respectively from the upper edges of the left and right side wall portions 83S.

[0035] [Drive device] The removing device 32 is provided with a drive device 85 (see FIGS. 5, 10, and 14) that slides the blade unit 84 in the front-rear direction. The drive device 85 includes a support plate 85A, a ball screw 85B, a rail 85R, a sliding member 85S, and a drive source 85D. The support plate 85A is disposed below the left and right flange portions 83F and is fixed to the immersion tank 81 or the carriage 34. The ball screw 85B is provided on one of the left and right support plates 85A. The screw shaft 85BS is attached to the upper surface of the support plate 85A with the front-rear direction as the axial direction, and the nut 85BN is attached to the lower surface of the flange portion 83F above the screw shaft 85BS. The drive source 85D includes a motor, a reduction gear, and the like.

[0036] The rail 85R is attached to the upper surfaces of the left and right support plates 85A with the longitudinal direction being the front-rear direction, and the sliding member 85S is attached to the lower surfaces of the left and right flange portions 83F. The sliding member 85S is fitted to the rail 85R and is slidable along the rail 85R. When the screw shaft 85BS is driven by the drive source 85D, the blade unit 84 slides in the front-rear direction together with the nut 85BN. Note that the above-described drive device 85 is merely an example, and the drive device 85 may be, for example, a belt drive device, a rack and pinion, or the like.

[0037] The drive device 85 is provided at a position higher than the maximum height of the liquid level that can be stored in the immersion tank 81. For example, in the present embodiment, since the upper edge portions of the side wall portions 81S of the immersion tank 81 are formed at the same height over the entire circumference, the maximum height of the liquid level that can be stored in the immersion tank 81 is equal to the height of the upper edge portions of the side wall portions 81S. According to this configuration, the possibility of the cleaning liquid entering the drive device 85 can be reduced.

[0038] When performing a wiping process to remove deposits from the nozzle surface 14F, the blade unit 84 slides from the slide start position toward the slide end position. In the present embodiment, the slide start position is the rear end of the slidable range of the blade unit 84. The slide end position is the front end of the slidable range of the blade unit 84. FIGS. 10 to 13 and 15 show the state where the blade unit 84 is located at the slide start position. FIG. 16 shows the state where the blade unit 84 is located at the slide end position.

[0039] During the wiping process, since the blade 82 moves in the cleaning liquid, there is a possibility that droplets of the cleaning liquid are generated. The drive source 85D is provided on the side closer to the slide start position than the slide end position of the blade 82. According to this configuration, during the wiping process, since the blade 82 moves in a direction away from the drive source 85D, the possibility of the cleaning liquid entering the drive source 85D can be reduced.

[0040] Cleaning Liquid Supply Device The inkjet recording apparatus 1 includes a cleaning liquid supply device 13 that supplies a cleaning liquid to the immersion tank 81 (see FIG. 4). The cleaning liquid supply device 13 includes a cleaning liquid tank 13T that stores the cleaning liquid, and a pump 13P that sends out the cleaning liquid from the cleaning liquid tank 13T. The pump 13P is connected to the immersion tank 81. A suction pump 68 and a waste liquid tank 69 are connected to the immersion tank 81 (see FIG. 4).

[0041] The cleaning liquid supply device 13 supplies the cleaning liquid so that the liquid level is located within a predetermined range above the nozzle surface 14F. For example, a sensor 13S (see FIG. 14) for detecting the height of the liquid level of the cleaning liquid is provided in the immersion tank 81. The control unit 2 drives the pump 13P so that the height of the liquid level detected by the sensor 13S is within a predetermined range above the nozzle surface 14F. According to this configuration, the possibility of the cleaning liquid entering the drive circuit 12D provided in the inkjet head 12 can be reduced.

[0042] Next, the operation of the maintenance device 30 will be described. The following operations are executed by the control unit 2 controlling each part of the maintenance device 30.

[0043] When executing an image forming job (see FIG. 6), the removing device 32 is arranged at the side retracted position, and the conveying unit 7 is arranged at the image forming position.

[0044] The purge process and the wipe process are executed at a predetermined timing. The predetermined timing is, for example, when a predetermined time has elapsed after the image forming job is completed. When performing the purge process and the wipe process, the control unit 2 moves the conveying unit 7 to the lower retracted position by the elevating device 35 (see FIG. 7), and moves the carriage 34 to the facing position by the slide device 36 (see FIG. 8). At this time, the removing device 32 is located at the separated position. Next, the control unit 2 raises the removing device 32 to the contact position by raising the conveying unit 7 by the elevating device 35 (see FIG. 9).

[0045] The blade unit 84 is positioned at the slide start position (see Fig. 15). At the slide start position, the blade 82 is positioned behind the nozzle surface 14F.

[0046] Subsequently, the control unit 2 increases the pressure inside the nozzle 14N of the inkjet head 12 to eject ink (purge process). Next, the control unit 2 slides the blade unit 84 forward by the drive device 85 (wipe process). The blade 82 advances while being pressed against the nozzle surface 14F and flexing, scraping off the ink adhering to the nozzle surface 14F. The ink is diluted by the cleaning liquid. The blade unit 84 stops at the slide end position (see Fig. 16). At the slide end position, the blade 82 is positioned in front of the nozzle surface 14F.

[0047] After the end of the wipe process, the control unit 2 waits until an image forming job is input while keeping the removing device 32 at the contact position. During this time, since the nozzle surface 14F is immersed in the cleaning liquid, an increase in the viscosity of the ink inside the nozzle 14N is suppressed. Also, the adhesion of ink to the nozzle surface 14F and the blade 82 is prevented.

[0048] When an image forming job is input, the control unit 2 lowers the removing device 32 to the separated position by the elevating device 35 (see Fig. 8), then slides the removing device 32 to the side standby position by the slide device 36 (see Fig. 7), and then, after raising the transport unit 7 to the image forming position by the elevating device 35 (see Fig. 6), executes the image forming job.

[0049] According to the inkjet recording apparatus 1 according to the present embodiment described above, there are provided an inkjet head 12, an immersion tank 81 for storing a cleaning liquid, a lifting device 35 for immersing the nozzle surface 14F of the inkjet head 12 in the cleaning liquid by lifting and lowering the immersion tank 81 or the inkjet head 12, and a removing device 32 provided in the immersion tank 81 for removing deposits from the nozzle surface 14F. According to this configuration, since the removing device 32 removes deposits from the nozzle surface 14F with the nozzle surface 14F immersed in the cleaning liquid, the ability to remove deposits from the nozzle surface 14F can be improved.

[0050] Further, according to the inkjet recording apparatus 1 according to the present embodiment, there is provided a driving device 85 for driving the removing device 32, and the driving device 85 is provided at a position higher than the maximum height of the liquid level that can be stored in the immersion tank 81. According to this configuration, the possibility of the cleaning liquid entering the driving device 85 can be reduced.

[0051] Further, according to the inkjet recording apparatus 1 according to the present embodiment, there is provided a cleaning liquid supply device 13 for supplying the cleaning liquid to the immersion tank 81, and the cleaning liquid supply device 13 supplies the cleaning liquid so that the liquid level is positioned within a predetermined range above the nozzle surface 14F. According to this configuration, the possibility of the cleaning liquid entering the drive circuit 12D provided in the inkjet head 12 can be reduced.

[0052] Further, according to the inkjet recording apparatus 1 according to the present embodiment, the lifting device 35 maintains the state in which the nozzle surface 14F is immersed in the cleaning liquid during a period when image formation is not performed by the inkjet head 12. According to this configuration, an increase in the viscosity of the ink in the nozzle 14N during a period when image formation is not performed can be suppressed.

[0053] Further, according to the inkjet recording apparatus 1 according to the present embodiment, when image formation is performed by the inkjet head 12, the lifting device 35 raises and lowers the immersion tank 81 or the inkjet head 12 to a position where the nozzle surface 14F is not immersed in the cleaning liquid. According to this configuration, an increase in the viscosity of the ink in the nozzle 14N during a period when image formation is not performed can be suppressed.

[0054] Further, according to the inkjet recording apparatus 1 according to the present embodiment, the removing device 32 includes a blade 82 that removes deposits by sliding in one direction along the nozzle surface 14F, the driving device 85 includes a driving source 85D that generates a driving force, and the driving source 85D is provided on a side closer to the sliding start position than the sliding end position of the blade 82. According to this configuration, the possibility of the cleaning liquid entering the driving source 85D can be reduced.

[0055] The above embodiment may be modified as follows.

[0056] In addition to the configuration of the above embodiment, the immersion tank 81 may include a heater 81H (see FIG. 14) that heats the cleaning liquid. According to this configuration, the ink removing ability can be enhanced due to the softening of the fixed ink and the decrease in the viscosity of the cleaning liquid.

[0057] In the above embodiment, an example is shown in which the removing device 32 is slid in the space formed by lowering the transport unit 7, but it may be configured such that the removing device 32 is slid in the space formed by raising the image forming unit 6.

Explanation of Reference Numerals

[0058] 1 Inkjet recording apparatus 12 Inkjet head 13 Cleaning liquid supply device 14F Nozzle surface 32 Removing device 35 Lifting device 81 Immersion tank 81H Heater 85 Driving device 85D Driving source

Claims

1. An inkjet head, An immersion tank for storing a cleaning liquid, A lifting device for immersing the nozzle surface of the inkjet head in the cleaning liquid by lifting and lowering the immersion tank or the inkjet head, And a removing device provided in the immersion tank for removing deposits from the nozzle surface. The inkjet recording apparatus is characterized by comprising the above components.

2. It comprises a driving device for driving the removing device, The driving device is provided at a position higher than the maximum height of the liquid level that can be stored in the immersion tank. The inkjet recording apparatus according to claim 1 is characterized by this.

3. It comprises a cleaning liquid supply device for supplying a cleaning liquid to the immersion tank, The cleaning liquid supply device supplies the cleaning liquid so that the liquid level is located within a predetermined range above the nozzle surface. The inkjet recording apparatus according to claim 1 or 2 is characterized by this.

4. The lifting device maintains the state in which the nozzle surface is immersed in the cleaning liquid during a period when image formation is not performed by the inkjet head. The inkjet recording apparatus according to claim 1 is characterized by this.

5. When image formation is performed by the inkjet head, the lifting device lifts and lowers the immersion tank or the inkjet head to a position where the nozzle surface is not immersed in the cleaning liquid. The inkjet recording apparatus according to claim 1 is characterized by this.

6. The removing device includes a blade that removes deposits by sliding in one direction along the nozzle surface, The driving device includes a driving source that generates a driving force, The driving source is provided on a side closer to the sliding start position than the sliding end position of the blade. The inkjet recording apparatus according to claim 2 is characterized by this.

7. The inkjet recording apparatus according to claim 1, wherein the dipping tank is provided with a heater for heating a cleaning liquid.

Images