Inkjet recording device and nozzle surface cleaning method

Abstract

To provide an inkjet recording device and a nozzle face cleaning method that are able to appropriately wipe off residual ink adhering to a nozzle face while restricting increases in the size and cost of the device.SOLUTION: An inkjet recording device 1 includes: an inkjet head 241 that ejects ink from a nozzle surface 241a; a head cleaning unit 44 that performs a nozzle surface cleaning operation for wiping the nozzle surface 241a with a cleaning surface of a wiping member 441a wetted with ink supplied from the inkjet head 241; and a control unit 50. The head cleaning unit 44 sets a different area of the wiping member 441a as a cleaning surface each time the nozzle surface cleaning operation is performed.SELECTED DRAWING: Figure 9B

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus and a nozzle surface cleaning method. [Background technology]

[0002] Inkjet recording devices are known that record images by ejecting ink from a nozzle surface and causing it to land at desired positions on a recording medium. When ink adheres to the nozzle surface of an inkjet recording device, the ink may thicken and solidify, blocking part of the nozzles, potentially resulting in ejection problems. Therefore, it is common to remove the adhered ink by wiping the nozzle surface with a wiping member such as a cloth.

[0003] In particular, for example, Patent Document 1 proposes a configuration in which a cloth is pressed against the nozzle surface and moves back and forth to reduce areas of the nozzle surface that are not wiped. Also, for example, Patent Document 2 proposes a configuration in which a cleaning liquid is applied to reduce areas of the nozzle surface that are not wiped. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-192967 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-334964 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the invention of Patent Document 1 uses a dry cloth as the wiping member. Therefore, if the residual ink dries and thickens, the wiping member may not be able to wipe away all of the residual ink, leaving some ink unwiped. In addition, the dry cloth has an uneven surface, making it easy for some ink to be left unwiped.

[0006] The invention of Patent Document 2 applies a cleaning liquid, which can solve the above-mentioned problems of Patent Document 1. However, a dedicated device for applying the cleaning liquid is required, which increases the size and cost of the inkjet recording device.

[0007] The present invention has been made in consideration of these circumstances, and its purpose is to provide an inkjet recording device and a nozzle surface cleaning method that can properly wipe off residual ink adhering to the nozzle surface while suppressing increases in the size and cost of the device. [Means for solving the problem]

[0008] The invention described in claim 1 is an inkjet recording apparatus, an inkjet head that ejects ink from nozzles provided on a nozzle surface; a head cleaning unit that performs a nozzle surface cleaning operation by rubbing and wiping the nozzle surface with a cleaning surface of a wiping member; a control unit that supplies ink from the inkjet head to the cleaning surface of the wiping member, The head cleaning unit performs the nozzle surface cleaning operation with the cleaning surface of the wiping member wetted with the ink, and a different area of ​​the wiping member becomes the cleaning surface each time the nozzle surface cleaning operation is performed.

[0009] The invention described in claim 2 is the inkjet recording apparatus described in claim 1, The maximum amount of ink that the wiping member can hold is α [g / m 2 ], the take-up amount of the wiping member during the nozzle surface cleaning operation is β [m], the width of the inkjet head is γ [m], and the amount of ink supplied from the inkjet head is δ [g], then α, β, γ, and δ satisfy the relationship of the following formula (1): Equation (1) α×β×γ>δ

[0010] The invention described in claim 3 is the inkjet recording apparatus described in claim 1, The control unit supplies ink to the wiping member by causing the inkjet head to eject ink while the inkjet head is in contact with the wiping member.

[0011] The invention described in claim 4 is the inkjet recording apparatus described in claim 1, The control unit causes the inkjet head to wait for a predetermined time in a state where the inkjet head is in contact with the wiping member, thereby supplying ink to the wiping member.

[0012] The invention described in claim 5 is the inkjet recording apparatus described in claim 1, The control unit vibrates the meniscus to supply ink to the wiping member.

[0013] The invention described in claim 6 is the inkjet recording apparatus described in claim 1, The control unit supplies ink to the wiping member by sliding the inkjet head against the wiping member at a speed slower than that during wiping in the nozzle surface cleaning operation.

[0014] The invention described in claim 7 is the inkjet recording apparatus described in claim 1, The control unit supplies ink from the inkjet head to the wiping member in an amount corresponding to the elapsed time since the previous nozzle surface cleaning operation.

[0015] The invention described in claim 8 is the inkjet recording apparatus described in claim 1, The control unit controls the ink supply unit to supply an amount of ink corresponding to the period during which the inkjet head has been mounted from the inkjet head to the wiping member.

[0016] The invention described in claim 9 is the inkjet recording apparatus described in claim 1, The control unit wipes the nozzle surface with the cleaning surface of the wiping member wetted with ink, and then absorbs ink from the nozzle surface with a surface of the wiping member that is different from the cleaning surface.

[0017] The invention described in claim 10 is the inkjet recording apparatus described in claim 9, The control unit causes a surface of the wiping member other than the cleaning surface to come into contact with the nozzle surface and waits for a predetermined time, thereby absorbing ink from the nozzle surface.

[0018] The invention described in claim 11 is the inkjet recording apparatus described in claim 9, The control unit brings a surface of the wiping member, which is different from the cleaning surface, into contact with the nozzle surface and rubs it, thereby absorbing ink from the nozzle surface.

[0019] The invention described in claim 12 is an inkjet head that ejects ink from nozzles provided on a nozzle surface; a head cleaning unit that performs a nozzle surface cleaning operation of rubbing and wiping the nozzle surface with a cleaning surface of a wiping member, a supplying step of supplying ink from the inkjet head to the cleaning surface of the wiping member; a cleaning step of performing a nozzle surface cleaning operation while wetting the cleaning surface of the wiping member with the ink; and a cleaning surface changing step of changing a different area of ​​the wiping member to the cleaning surface each time the nozzle surface cleaning operation is performed.

[0020] The invention described in claim 13 is the nozzle surface cleaning method described in claim 12, A contacting step is provided before the supplying step, in which the cleaning surface is brought into contact with the nozzle surface.

[0021] The invention described in claim 14 is the nozzle surface cleaning method described in claim 12 or 13, After the cleaning step, a liquid absorbing step is provided in which ink on the nozzle surface is absorbed by a surface of the wiping member different from the cleaning surface. [Effects of the Invention]

[0022] According to the present invention, residual ink adhering to the nozzle surface can be properly wiped away while suppressing increases in the size and cost of the device. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a side view showing a schematic configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing main operating elements of an inkjet recording apparatus according to an embodiment of the present invention; [Figure 3] FIG. 2 is a bottom view showing the configuration of the head unit. [Figure 4] FIG. 10 is a diagram showing a carriage that moves in the width direction. [Figure 5] 10A and 10B are diagrams illustrating a movable range of the carriage in the width direction. [Figure 6A] FIG. 10 is a cross-sectional view of a cleaning portion during purge maintenance. [Figure 6B] FIG. 10 is a cross-sectional view of the cleaning unit during a scraping operation. [Figure 7] FIG. 2 is a schematic diagram illustrating the configuration of a head cleaning unit. [Figure 8] 10 is a flowchart of a nozzle surface cleaning operation. [Figure 9A] 10A and 10B are schematic diagrams illustrating a step of supplying ink to a wiping member. [Figure 9B] 10A to 10C are schematic diagrams illustrating a step of wiping the nozzle surface with a wiping member. [Figure 9C] 10 is a schematic diagram of the step of forming a new cleaning surface with a take-up roller. FIG. [Figure 9D] 10A and 10B are schematic diagrams illustrating a step of absorbing ink from the nozzle surface by a wiping member. [Figure 10] FIG. 2 is a cross-sectional schematic diagram of a split yarn. [Figure 11A] 10 is a graph showing the relationship between the time elapsed since the previous nozzle surface cleaning operation and the increase in viscosity of ink on the nozzle surface. [Figure 11B]10 is a graph showing the relationship between the period during which an inkjet head is mounted and the water repellency of the nozzle surface of the inkjet head. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, components having the same functions and configurations are designated by the same reference numerals, and their description will be omitted.

[0025] [Overall configuration of inkjet recording device] Fig. 1 is a diagram showing a schematic configuration of an inkjet recording apparatus 1 according to an embodiment of the present invention. Fig. 2 is a functional block diagram of the inkjet recording apparatus 1. The inkjet recording apparatus 1 includes a paper feed unit 10, an image forming unit 20, a paper discharge unit 30, a cleaning unit 40, and a control unit 50. The various units of the inkjet recording apparatus 1 are connected to each other via a bus 65.

[0026] Under the control of the control unit 50, the inkjet recording device 1 transports the recording medium M stored in the paper feed unit 10 to the image forming unit 20. The inkjet recording device 1 records an image on the recording medium M in the image forming unit 20, and transports the recording medium M with the image recorded thereon to the paper discharge unit 30.

[0027] The recording medium M is not limited to paper such as plain paper or coated paper, but may be any of various media such as fabric or sheet-like resin on whose surface the ink can be fixed.

[0028] In the following description, the X direction, Y direction, and Z direction are the directions shown in Fig. 1. In addition, in the following description, the X direction, Y direction, and Z direction are also referred to as the width direction, conveyance direction, and height direction, respectively.

[0029] (Paper feed section) The paper feed unit 10 has a paper feed tray 11 and a medium supply unit 12. The paper feed tray 11 stores recording media M. The medium supply unit 12 transports and supplies the recording media M from the paper feed tray 11 to the image forming unit 20. The medium supply unit 12 is equipped with a belt. The belt is ring-shaped and is supported on the inside by two rollers. The medium supply unit 12 rotates the rollers with the recording media M placed on the belt. Through this control, the medium supply unit 12 transports the recording media M from the paper feed tray 11 to the image forming unit 20.

[0030] (Image forming section) The image forming section 20 includes a transport drum 21, a delivery unit 22, a heating section 23, a head unit 24, a fixing section 25, a delivery section 26, and the like.

[0031] {Conveyor drum} The transport drum 21 has claws 211 and suction sections 212 (see FIG. 4) for holding the recording medium M on the transport surface 21a. The recording medium M is held on the transport surface 21a by having its edges pressed down by the claws 211 and being drawn to the transport surface 21a by the suction sections 212.

[0032] The transport drum 21 has a rotation shaft extending in the width direction, which is connected to a transport drum motor (not shown). The transport drum 21 rotates by an angle proportional to the rotation amount of the transport drum motor while holding the recording medium M on the transport surface 21a, which is the cylindrical outer peripheral surface. Through this control, the transport drum 21 transports the recording medium M in the transport direction.

[0033] {Delivery unit} The transfer unit 22 is provided at a position between the medium supply unit 12 and the transport drum 21. The transfer unit 22 transfers the recording medium M transported by the medium supply unit 12 to the transport drum 21. Specifically, the transfer unit 22 holds and picks up one end of the recording medium M transported from the medium supply unit 12 with a swing arm unit 221, and transfers it to the transport drum 21 via the transfer drum 222.

[0034] {Heating part} The heating section 23 is provided between the position where the delivery drum 222 is disposed and the position where the head unit 24 is disposed. The heating section 23 heats the recording medium M conveyed by the conveyance drum 21 so that the temperature falls within a predetermined temperature range. The heating section 23 includes, for example, an infrared heater. The heating section 23 energizes the infrared heater based on a control signal supplied from the control section 50 to generate heat.

[0035] {Head Unit} The head unit 24 includes a plurality of inkjet heads 241 (see FIG. 3), a head drive unit 242, and a carriage 24a. The head unit 24 supplies a drive signal to the inkjet heads 241 via the head drive unit 242 at appropriate timing according to the rotation of the transport drum 21 that holds the recording medium M. Upon receiving the drive signal, the inkjet head 241 ejects ink onto the recording medium M from a nozzle surface 241a (see FIG. 3), which is an ink ejection surface facing the transport surface 21a, to record an image. The head unit 24 is disposed such that the nozzle surface 241a and the transport surface 21a are spaced a predetermined distance apart. In this embodiment, four head units 24, corresponding respectively to yellow (Y), magenta (M), cyan (C), and black (K), are arranged at predetermined intervals from the upstream side in the transport direction in the order of Y, M, C, and K.

[0036] Inkjet head 3 is a bottom view of the entire head unit 24 as seen from the side facing the transport surface 21a of the transport drum 21. The head unit 24 of this embodiment is equipped with 16 inkjet heads 241. Each inkjet head 241 has a nozzle row made up of nozzles N arranged in the width direction on its lower surface, the nozzle surface 241a. The nozzle surface 241a of the inkjet head 241 is also coated with a water-repellent film, which is an organic film made of, for example, a fluorine-based resin.

[0037] The arrangement direction of the nozzles N in each inkjet head 241 is not limited to the width direction, but may be a direction intersecting the transport direction at an angle other than a right angle. Furthermore, the number of inkjet heads 241 provided in the head unit 24 is not limited to 16. The number of inkjet heads 241 may be changed as appropriate depending on the recording width of the image, etc.

[0038] <Head module> The 16 inkjet heads 241 are combined in pairs to form eight head modules 241M. The nozzle rows of each head module 241M are adjusted in the width direction so that the nozzle positions in the width direction do not overlap.

[0039] Each head module 241M fits into an opening provided in a support plate at the bottom of the carriage 24a. Each head module 241M is supported by the support plate with the nozzle surface 241a of the inkjet head 241 exposed from the bottom surface of the support plate. The eight head modules 241M are arranged in a staggered pattern to form a line head so that the range in which ink can be ejected from the nozzles N is continuously connected in the width direction.

[0040] The widthwise arrangement range of the nozzles N included in the head unit 24 covers the widthwise width of the image recording area of ​​the recording medium M transported by the transport drum 21. The head unit 24 is used in a fixed position when recording an image. The head unit 24 records an image by a single pass method by sequentially ejecting ink at predetermined intervals to different positions in the transport direction as the recording medium M is transported.

[0041] The head unit 24 may record an image by a multi-pass method in which the nozzles N are arranged in a widthwise range that is shorter than the width of the image recording area and ink is ejected sequentially while moving in the widthwise direction.

[0042] The ink ejection mechanism for ejecting ink from each nozzle N is not particularly limited, but a piezo-type mechanism using a piezoelectric element can be used. Known piezo-type ink ejection mechanisms include shear mode and vent mode. A shear mode ink ejection mechanism ejects ink by varying the pressure of the ink in the pressure chamber by generating a shear mode type displacement in the piezoelectric element on the wall of the pressure chamber that communicates with the nozzle N. A vent mode ink ejection mechanism ejects ink by varying the pressure of the ink in the pressure chamber by deforming a piezoelectric element that is fixed to a diaphragm that forms the wall of the pressure chamber.

[0043] The ink used to record images by the head unit 24 has the property of changing phase between a gel state and a sol state depending on the temperature. A gel state is a form of solid, and a sol state is a form of liquid. An example of such an ink composition is one in which a few percent of a gelling agent is added to a composition primarily composed of a polymerizable compound and a photopolymerization initiator. When gel-state ink is heated and the temperature is increased, the viscosity begins to decrease significantly once the ink's inherent sol-state temperature (e.g., around 70°C) is exceeded, and the ink changes phase to a sol-state. On the other hand, when the temperature of sol-state ink is decreased, the viscosity begins to increase significantly once the ink's inherent gel-state temperature (e.g., around 50°C) is reached, and the ink changes phase to a gel-state.

[0044] The head unit 24 has an ink heating section (not shown) that heats the ink before it is supplied to the inkjet head 241 and the ink that has been supplied to the inkjet head 241. The inkjet head 241 ejects the ink that has been heated by the ink heating section and turned into a sol from the nozzles N. The ink that has been ejected from the nozzles N and landed on the recording medium M is cooled and quickly changes phase to a gel state.

[0045] The ink used in this embodiment has the property of being hardened by irradiation with ultraviolet light. That is, the ink used in this embodiment is cooled and gelled on the recording medium M, and then fixed on the recording medium M by being hardened by irradiation with ultraviolet light.

[0046] <carriage> The carriage 24a carries a plurality of inkjet heads 241. The carriages 24a are provided so as to be able to move individually in the width direction. FIG. 4 is a diagram showing the carriage 24a moving in the width direction. FIG. 5 is a diagram showing the range of movement of the carriage 24a in the width direction. The carriage 24a is moved in the width direction between the image recording position and the purge maintenance position by a carriage movement unit 62 (see FIG. 2), which will be described later, as shown in FIGS. 4 and 5.

[0047] The image recording position is the position where the nozzle surface 241a faces the transport surface 21a. The image recording position is also the position of the carriage 24a when ink is ejected onto the recording medium M on the transport surface 21a to record an image. After the carriage 24a is raised from the image recording position, it can be moved in the +X direction to move the carriage 24a to the purge maintenance position.

[0048] The purge maintenance position is the position of the carriage 24a when performing purge maintenance to discharge ink from the nozzles N of the inkjet head 241. In purge maintenance, similar to when recording an image, ink is continuously discharged from each nozzle N by varying the ink pressure in the pressure chambers communicating with the nozzles N. This allows air bubbles and foreign matter mixed in the ink inside the inkjet head 241 to be discharged to the outside along with the ink.

[0049] The method of purge maintenance is not limited to this. For example, a method of forcibly discharging ink from the nozzles N by increasing the ink supply pressure to the inkjet head 241 (pressure purge) may be used.

[0050] <Head drive unit> The head driving unit 242 supplies a driving signal that deforms the piezoelectric element in accordance with the image data at an appropriate timing to the inkjet head 241. By this control, the head driving unit 242 causes the nozzle N of the inkjet head 241 to eject an amount of ink that corresponds to the pixel value of the image data.

[0051] {Fixing part} Returning to FIG. 1, the fixing unit 25 cures and fixes the ink ejected onto the recording medium M. The fixing unit 25 has an ultraviolet ray irradiation unit arranged across the width direction of the transport drum 21. The fixing unit 25 irradiates ultraviolet rays from the ultraviolet ray irradiation unit onto the recording medium M placed on the transport drum 21 to fix the ink. The ultraviolet ray irradiation unit of the fixing unit 25 is arranged opposite the transport surface between the position where the head unit 24 is arranged and the position where the delivery drum 261 of the delivery unit 26 is arranged in the transport direction.

[0052] {Delivery Department} The delivery unit 26 includes a transfer drum 261 and a belt loop 262. The transfer drum 261 is cylindrical and transfers the recording medium M from the transport drum 21 to the belt loop 262. The belt loop 262 is a circular belt supported by two rollers on the inside. The delivery unit 26 transports the recording medium M, which has been transferred from the transport drum 21 onto the belt loop 262 by the transfer drum 261, via the belt loop 262 and sends it to the paper discharge unit 30.

[0053] (Paper ejection section) The paper discharge unit 30 includes a paper discharge tray 31. The paper discharge unit 30 is plate-shaped, and the recording medium M sent out from the image forming unit 20 by the delivery unit 26 is placed on the paper discharge unit 30.

[0054] (Cleaning section) When the carriage 24a is moved to the purge maintenance position, a cleaning unit 40 is disposed below the carriage 24a in the height direction. The cleaning unit 40 includes an ink receiving unit 41, a scraping member 42, an ink storage unit 43, a head cleaning unit 44, and the like.

[0055] {Ink receiving part} 6A is a cross-sectional view of a portion of cleaning unit 40 during purge maintenance. Ink receiving unit 41 includes ink tub 411 having an inclined surface inclined relative to the horizontal plane. Ink tub 411 receives ink discharged from nozzle N on the inclined surface. The material of ink tub 411 can be, for example, aluminum, but is not limited to this.

[0056] In this embodiment, a case where one ink tub 411 is provided in common for the four carriages 24a is illustrated, but this is not limiting. That is, a configuration in which one ink tub 411 is provided separately for each carriage 24a may also be used.

[0057] An outlet 411a into which ink flowing down the inclined surface flows is provided at the bottom of ink tub 411. Ink that drops (lands) on the inclined surface flows downward along the inclined surface due to gravity and flows into outlet 411a.

[0058] {Scraping member} A scraping member 42 is attached to the upper end of the side wall on the -X direction side of the ink tub 411. A total of four scraping members 42 are provided, one for each carriage 24a. However, this is not limiting, and a configuration in which one common scraping member 42 is provided for all four carriages 24a may also be used.

[0059] The scraping member 42 is a blade-shaped member having a length equal to or greater than the width of the nozzle surface 241a in the transport direction. The material of the scraping member 42 is not particularly limited, but may be, for example, various resins or metals. The scraping member 42 scrapes off and removes ink that is discharged from the nozzles N during purge maintenance and adheres to the nozzle surface 241a.

[0060] 6B is a diagram showing a cross section of the cleaning unit 40 during the ink scraping operation by the scraping member 42. The upper tip of the scraping member 42 in the height direction is positioned so that it does not come into contact with the nozzle surface 241a but does come into contact with ink adhering to the nozzle surface 241a when the carriage 24a moves in the −X direction from the purge maintenance position.

[0061] 6B, when the nozzle surface 241a moves in the −X direction together with the carriage 24a, the tip of the scraping member 42 approaches the nozzle surface 241a. Then, the ink adhering to the nozzle surface 241a flows from the tip of the scraping member 42 to the side surface of the scraping member 42, and the ink is scraped and removed from the nozzle surface 241a. In other words, the scraping member 42 scrapes the ink off the nozzle surface 241a without coming into contact with the nozzle surface 241a.

[0062] A tray 421 is attached to the lower end of the scraping member 42. The tray 421 adjusts the drip position of the scraped ink. That is, the tray 421 allows the scraped ink scraped by the scraping member 42 to drip to a predetermined drip position and flow into the discharge port 411a.

[0063] {Ink storage section} As shown in FIGS. 6A and 6B, outlet 411a of ink tub 411 is connected to ink storage unit 43. Ink storage unit 43 stores the ink that has been received by ink tub 411 and flowed into outlet 411a. An ink amount detection unit 431 is provided at the bottom of ink storage unit 43. Ink amount detection unit 431 detects the amount of ink stored in ink storage unit 43 and sends the detected amount to control unit 50. Ink amount detection unit 431 is, for example, a load cell that detects the weight of the stored ink. Ink amount detection unit 431 is not limited to a load cell, and may be, for example, a liquid level sensor that detects the height of the ink liquid surface.

[0064] (Head cleaning section) 7 shows the head cleaning section 44. The head cleaning section 44 includes a wiping unit 441. The wiping unit 441 includes a wiping member 441a, a backup member 441b, an unwinding roller 441c, a winding roller 441d, and support rollers 441e and 441f.

[0065] The wiping member 441a wipes the nozzle surface 241a. The wiping member 441a is a long member wound on a roll. The wiping member 441a is, for example, a fabric such as a woven or nonwoven fabric. More specifically, the wiping member 441a is a loosely woven fabric. The wiping member 441a is approximately 0.3 mm thick, and the density of weft and warp threads is approximately 50 to 120 threads per inch. The wiping member 441a is unwound from the unwinding roller 441c and stretched between support rollers 441e and 441f, forming a cleaning surface of the nozzle surface 241a at a predetermined position. After wiping the nozzle surface 241a, the cleaning surface with ink attached thereto is taken up by the take-up roller 441d.

[0066] A backup member 441b is disposed on the rear surface of the cleaning surface. The backup member 441b is provided to resist the pressing force from the nozzle surface 241a to the wiping member 441a. As shown in Fig. 7, the backup member 441b includes a pressing spring 441b1, a pressing member 441b2, and a PET sheet 441b3.

[0067] The pressing spring 441b1 applies a predetermined biasing force to the pressing member 441b2 in a substantially uniform manner. The pressing member 441b2 has a lower portion made of sheet metal and an upper portion made of sponge. By using a sponge for the upper portion of the pressing member 441b2, the wiping member 441a can be gently pressed against the nozzle surface 241a. Furthermore, by using a sheet metal for the lower portion of the pressing member 441b2, a predetermined strength can be imparted to the pressing member 441b2. The PET sheet 441b3 is a thin sheet made of PET (Polyethylene Terephthalate). The PET sheet 441b3 is provided so as to cover at least the entire upper surface of the pressing member 441b2. The provision of the PET sheet 441b3 prevents ink from adhering to and hardening on the sponge on the upper portion of the pressing member 441b2, which is not ink-resistant.

[0068] A detailed description of the method for cleaning the nozzle surface 241a by the head cleaning unit 44 will be given later.

[0069] (Control unit) 2, the control unit 50 is a processor that controls the overall operation of the inkjet recording apparatus 1. The control unit 50 includes a CPU (Central Processing Unit) 51, a RAM (Random Access Memory) 52, a ROM (Read Only Memory) 53, a storage unit 54, and the like.

[0070] {CPU} The CPU 51 reads out various control programs and setting data stored in the ROM 53, stores them in the RAM 52, and executes the programs to perform various arithmetic processing.

[0071] {RAM} The RAM 52 provides a working memory space for the CPU 51 and stores temporary data. The RAM 52 may include a non-volatile memory.

[0072] {ROM} The ROM 53 stores various control programs and setting data executed by the CPU 51. Note that the ROM 53 may be replaced by a rewritable nonvolatile memory such as a flash memory.

[0073] {Storage section} The storage unit 54 stores print jobs input from an external device via the communication unit 64 and image data of images to be recorded related to the print jobs. For example, an HDD (Hard Disk Drive) is used as the storage unit 54. Alternatively, a DRAM (Dynamic Random Access Memory) or the like may be used in combination with the storage unit 54.

[0074] <Transport drive unit> The transport drive unit 61 supplies a drive signal to the transport drum motor of the transport drum 21 based on a control signal supplied from the control unit 50. Under this control, the transport drive unit 61 rotates the transport drum 21 at a predetermined speed and timing. In addition, the transport drive unit 61 supplies a drive signal to motors for operating the medium supply unit 12, the delivery unit 22, and the delivery unit 26 based on the control signal supplied from the control unit 50. Under this control, the transport drive unit 61 supplies the recording medium M to the transport drum 21 and discharges it from the transport drum 21.

[0075] <Carriage moving part> The carriage moving unit 62 outputs drive signals to the motors and brakes of the moving mechanism that moves the carriage 24a up and down in the height direction or moves it in the width direction under the control of the control unit 50. Through this control, the carriage moving unit 62 moves the carriage 24a between the above-mentioned recording position and the purge maintenance position.

[0076] {Operation display section} The operation display unit 63 displays the status of the inkjet recording apparatus 1, an operation menu, etc. in response to a control signal from the control unit 50. The operation display unit 63 also accepts user operations and outputs them to the control unit 50. The operation display unit 63 includes, for example, a liquid crystal display unit in which a touch sensor as an operation accepting means is provided superimposed on a display screen as a display means.

[0077] {Communications Department} The communication unit 64 is a communication interface that controls communication operations with external devices. The communication interface may include one or more devices compatible with various communication protocols, such as a LAN board or LAN card. The communication unit 64 acquires image data to be recorded from the external device under the control of the control unit 50. The communication unit 64 also transmits status information and the like to the external device.

[0078] {bus} The bus 65 is a path that electrically connects the above components and allows signals to be exchanged between them.

[0079] [Nozzle surface cleaning operation by the head cleaning unit] The nozzle surface cleaning operation by the head cleaning unit 44 as described above will be described with reference to Figure 8 and Figures 9A to 9E. In the present invention, after purge maintenance in the nozzle bucket 411 and scraping of ink from the nozzle surface 241a by the scraping member 42, the nozzle surface cleaning operation by the head cleaning unit 44 is carried out.

[0080] The control unit 50 controls the carriage movement unit 62 to move the inkjet head 241 to a nozzle surface cleaning position where the nozzle surface 241a faces the wiping member 441a. Then, the control unit 50 controls the carriage movement unit 62 to move the nozzle surface 241a downward in the height direction until it comes into contact with the wiping member 441a (step S101). Note that the contact portion of the wiping member 441a with the nozzle surface 241a in step S101 is the cleaning surface.

[0081] When the nozzle surface 241a and the wiping member 441a come into contact with each other, the control unit 50 supplies ink to the cleaning surface of the wiping member 441a (step S102), as shown in Fig. 9A. By bringing the nozzle surface 241a and the cleaning surface into contact with each other in step S101 and then supplying ink in step S102, it is possible to prevent ink mist from being generated when the ink is supplied.

[0082] In step S102, the control unit 50 can supply ink to the wiping member 441a by, for example, driving the head driving unit 242 to eject ink from all the nozzles N. However, the method of supplying ink to the wiping member 441a is not limited to this control.

[0083] For example, the control unit 50 causes the head drive unit 242 to supply a drive signal to the inkjet head 241 that vibrates the ink interface (meniscus), thereby bringing the ink into contact with the wiping member 441a as shown in FIG. 9A. Alternatively, the control unit 50 may wait a predetermined time while the nozzle surface 241a and the wiping member 441a are in contact with each other, thereby drawing ink from the nozzles N by the capillary force of the wiping member 441a. Alternatively, the control unit 50 may drive the carriage movement unit 62 to rub the inkjet head 241 in the width direction at a speed slower than that of step S103, which will be described later, thereby bringing the nozzles N into reliable contact with the wiping member 441a and drawing the ink. However, ejecting ink from the nozzles N, as described above, is preferable as a method of supplying ink to the wiping member 441a. This control minimizes the time required for the nozzle surface cleaning operation, thereby improving image recording productivity.

[0084] Furthermore, the amount of ink applied to the wiping member 441a in step S102 may be an amount that leaves no ink adhering to the backup member 441b (PET sheet 441b3 in this embodiment) after a series of nozzle surface cleaning operations.

[0085] In other words, even if ink penetrates the wiping member 441a and adheres to the backup member 441b, it is sufficient that the amount is such that it can be wiped away by the wiping member 441a that is pulled out in step S105, which will be described later. Therefore, the maximum amount of ink that the wiping member 441a can hold is α [g / m 2 ], the take-up amount of the wiping member 441a is β [m], the width of the inkjet head 241 in the width direction is γ [m], and the amount of ink applied is δ [g], then α, β, γ, and δ should satisfy the following inequality (1). Formula (1)…α×β×γ>δ

[0086] This is because if the backup member 441b is soiled with ink, the ink may transfer to other cleaning surfaces of the wiping member 441a, causing color mixing when cleaning inkjet heads 241 of other colors. Also, if the backup member 441b does not include the PET sheet 441b3 and the sponge of the pressing member 441b2 is configured to directly contact the wiping member 441a, ink will harden if it adheres to the backup member 441b, i.e., the sponge. As a result, the ink will no longer be able to softly contact the wiping member 441a.

[0087] After applying ink to the wiping member 441a, the control unit 50 drives the carriage movement unit 62 to move the inkjet head 241 back and forth, thereby scrubbing the nozzle surface 241a, as shown in FIG. 9B (step S103).

[0088] In this embodiment, the wiping member 441a, which is a loose cloth as described above, is wet with ink, and ink penetrates between the fibers. As a result, the nozzle surface 241a can be wiped with the wiping member 441a, which is smoother than a dry cloth. Furthermore, because ink fills the spaces between the fibers, the wiping member 441a becomes more flexible, increasing the contact area with the nozzle surface 241a.

[0089] Furthermore, by wiping the inkjet head 241 by reciprocating, it is possible to prevent the water-repellent film on the nozzle surface 241a from becoming uneven.

[0090] After the nozzle surface 241a has been scraped, the control unit 50 separates the nozzle surface 241a and the wiping member 441a by driving the carriage moving unit 62 (step S104). Then, as shown in FIG. 9C, the control unit 50 drives the unwinding roller 441c and the winding roller 441d to wind up the wiping member 441a (step S105).

[0091] The control unit 50 drives the carriage movement unit 62 to move the inkjet head 241 downward in the height direction, bringing the nozzle surface 241a into contact with a surface other than the cleaning surface used up to step S104 (step S106). The control unit 50 rubs the nozzle surface 241a and the wiping member 441a back and forth for about 2 mm while they are in contact. By this control, the control unit 50 causes the surface of the wiping member 441a other than the cleaning surface to absorb the ink remaining on the nozzle surface 241a, as shown in FIG. 9D (step S107). By not only bringing the nozzle surface 241a and the wiping member 441a into contact with each other but also rubbing them, all of the ink on the nozzle surface 241a can be absorbed, even if the wiping member 441a is a cloth with creases and roughness.

[0092] After the liquid has been absorbed onto the nozzle surface 241a, the control unit 50 drives the carriage movement unit 62 to move the inkjet head 241 upward in the height direction (step S108). Also, the control unit 50 drives the unwinding roller 441c and the winding roller 441d to wind up the wiping member 441a and form a new cleaning surface (step S109), thereby completing the nozzle surface cleaning operation.

[0093] [Effects of the embodiment] As described above, the inkjet recording apparatus 1 according to this embodiment includes an inkjet head 241 that ejects ink from nozzles N provided on a nozzle surface 241a. The inkjet recording apparatus 1 also includes a head cleaning unit 44 that performs a nozzle surface cleaning operation in which the cleaning surface of a wiping member 441a scrapes and wipes the nozzle surface 241a. The inkjet recording apparatus 1 also includes a control unit 50 that supplies ink from the inkjet head 241 to the cleaning surface of the wiping member 441a. The head cleaning unit 44 performs the nozzle surface cleaning operation while wetting the cleaning surface of the wiping member 441a with ink, cleaning a different area of ​​the wiping member 441a each time. This configuration allows residual ink adhering to the nozzle surface 241a to be properly wiped away. Furthermore, because the residual ink is wiped away using ink rather than cleaning liquid, there is no need to provide a separate device for applying cleaning liquid, which helps prevent the inkjet recording apparatus 1 from becoming larger and more expensive. Furthermore, since different areas of the wiping member 441a are used as the cleaning surface, the nozzle surface 241a can be scraped and wiped with the uncontaminated wiping member 441a in each nozzle surface cleaning operation.

[0094] [Other configurations] Furthermore, in the above description, the wiping member 441a is described as being made of cloth. However, if the wiping member 441a is made of woven fabric, the yarn constituting the woven fabric is preferably a split yarn having a cross section as shown in FIG. 10. As shown in FIG. 10, the split yarn is composed of two fibers, S1 and S2, combined together. Nylon fiber is used as the fiber S1, and polyester fiber is used as the fiber S2. In this manner, the split yarn is composed of fibers S1 and S2 of two different materials and is subjected to an opening process. As a result, the split yarn is made of split fibers, which are thinner and have an irregular shape. In this manner, the split yarn has a fine fiber structure, which can improve the liquid absorption of the wiping member 441a. Furthermore, the split yarn is made of irregularly shaped fibers, which can improve the ink scraping performance during rubbing.

[0095] Furthermore, in the above description, the nozzle surface cleaning operation is performed after purge maintenance and ink scraping, but this is not limited to this. That is, the inkjet recording apparatus 1 may be provided with multiple cleaning modes, and for example, it may perform only the nozzle surface cleaning operation without performing purge maintenance and ink scraping.

[0096] Also, in step S102, the amount of ink supplied to the wiping member 441a needs to satisfy inequality (1) as described above, but it goes without saying that the amount needs to be sufficient to wipe away the thickened ink adhering to the nozzle surface 241a.

[0097] Therefore, the adhesion state of the thickened ink on the nozzle surface 241a may be predicted, and the amount of ink supplied to the wiping member 441a may be adjusted based on the prediction result. Specifically, as shown in FIG. 11A, the viscosity of the thickened ink on the nozzle surface 241a increases as the elapsed time (left-standing time) since the image formation process after the previous nozzle surface cleaning operation increases. This is because the longer the left-standing time of the thickened ink, the more drying and adhesion of discharge products progresses. Therefore, the amount of ink supplied to the wiping member 441a may be increased depending on the time elapsed since the previous nozzle surface cleaning operation.

[0098] Alternatively, the ease of wiping off thickened ink from the nozzle surface 241a may be predicted, and the amount of ink supplied to the wiping member 441a may be adjusted based on the prediction result. Specifically, as shown in FIG. 11B, as the period during which the inkjet head 241 is installed increases, the water repellency of the ink on the nozzle surface 241a decreases, making it more difficult to wipe off thickened ink. This is because, as the period during which the inkjet head 241 is installed increases, the number of nozzle surface cleaning operations increases, resulting in the removal of the water-repellent film. Therefore, the amount of ink supplied to the wiping member 441a may be increased depending on the period during which the inkjet head 241 is installed.

[0099] In the above description, the control unit 50 drives the carriage movement unit 62 to bring the nozzle surface 241a into contact with and separate from the wiping member 441a, but this is not limiting. That is, the wiping member 441a may be configured to be movable up and down in the height direction, so that the wiping member 441a comes into contact with and separates from the nozzle surface 241a.

[0100] Furthermore, in the above description, the inkjet recording apparatus 1 is equipped with the head cleaning unit 44, but this is not limiting, and the head cleaning unit 44 may be a separate device from the inkjet recording apparatus 1.

[0101] Furthermore, in the above description, an example has been disclosed in which the ROM 43 is used as a computer-readable medium for the program according to the present invention, but the present invention is not limited to this example. As other computer-readable media, non-volatile memories such as flash memories and portable recording media such as CD-ROMs can be applied. Furthermore, a carrier wave is also applied to the present invention as a medium for providing data of the program according to the present invention via a communication line.

[0102] In addition, the specific details of the inkjet recording device 1 and head cleaning unit 44 shown in the above embodiment, such as the configuration, structure, arrangement, control content and procedure, can be changed as appropriate within the scope of the present invention. [Explanation of symbols]

[0103] 1. Inkjet recording device 241 Inkjet head 241a nozzle surface 44 Head cleaning unit 441 Wipe Unit 441a Wiping material 50 control section

Claims

1. an inkjet head that ejects ink from nozzles provided on a nozzle surface; a head cleaning unit that performs a nozzle surface cleaning operation by rubbing and wiping the nozzle surface with a cleaning surface of a wiping member; a control unit that supplies ink from the inkjet head to the cleaning surface of the wiping member, The head cleaning unit performs the nozzle surface cleaning operation while wetting the cleaning surface of the wiping member with the ink, and a different area of ​​the wiping member becomes the cleaning surface each time the nozzle surface cleaning operation is performed.

2. The maximum amount of ink that the wiping member can hold is α [g / m ２ ], the take-up amount of the wiping member in the nozzle surface cleaning operation is β [m], the width of the inkjet head is γ [m], and the amount of ink supplied from the inkjet head is δ [g], then α, β, γ, and δ satisfy the relationship of the following formula (1): Formula (1) α×β×γ>δ

3. The inkjet recording apparatus according to claim 1 , wherein the control unit supplies ink to the wiping member by causing the inkjet head to eject ink while the inkjet head is in contact with the wiping member.

4. The inkjet recording apparatus according to claim 1 , wherein the control unit supplies ink to the wiping member by waiting for a predetermined time period while the inkjet head is in contact with the wiping member.

5. The inkjet recording apparatus according to claim 1 , wherein the control unit supplies ink to the wiping member by vibrating a meniscus.

6. The inkjet recording apparatus according to claim 1 , wherein the control unit supplies ink to the wiping member by sliding the inkjet head against the wiping member at a speed slower than that during wiping in the nozzle surface cleaning operation.

7. The inkjet recording apparatus according to claim 1 , wherein the control unit controls the ink supply unit to supply ink from the inkjet head to the wiping member in an amount corresponding to the elapsed time since the previous nozzle surface cleaning operation.

8. The inkjet recording apparatus according to claim 1 , wherein the control unit controls the ink supply unit to supply ink from the inkjet head to the wiping member in an amount corresponding to the period during which the inkjet head has been mounted.

9. 9. An inkjet recording device according to claim 1, wherein the control unit wipes the nozzle surface with the cleaning surface of the wiping member wetted with ink, and then absorbs the ink from the nozzle surface with a surface of the wiping member other than the cleaning surface.

10. The inkjet recording apparatus according to claim 9 , wherein the control unit absorbs ink from the nozzle surface by bringing a surface of the wiping member other than the cleaning surface into contact with the nozzle surface and waiting for a predetermined time.

11. The inkjet recording apparatus according to claim 9 , wherein the control unit absorbs ink from the nozzle surface by bringing a surface of the wiping member other than the cleaning surface into contact with the nozzle surface and rubbing the surface.

12. an inkjet head that ejects ink from nozzles provided on a nozzle surface; a head cleaning unit that performs a nozzle surface cleaning operation of rubbing and wiping the nozzle surface with a cleaning surface of a wiping member, a supplying step of supplying ink from the inkjet head to the cleaning surface of the wiping member; a cleaning step of performing a nozzle surface cleaning operation while wetting the cleaning surface of the wiping member with the ink; a cleaning surface changing step of changing a different area of ​​the wiping member to the cleaning surface each time the nozzle surface cleaning operation is performed.

13. The nozzle face cleaning method according to claim 12 , further comprising a contacting step of bringing the cleaning surface into contact with the nozzle face before the supplying step.

14. The nozzle surface cleaning method according to claim 12 or 13, further comprising, after the cleaning step, a liquid absorbing step of absorbing ink from the nozzle surface with a surface of the wiping member different from the cleaning surface.

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