Maintenance apparatus, recording apparatus, and control method

A maintenance apparatus that prevents a reduction in image quality of an image recorded by a liquid discharge head is provided. A maintenance apparatus includes an application unit configured to come into contact with a discharge surface included in a recording head and apply a cleaning liquid to the discharge surface, wherein discharge ports configured to discharge a liquid are formed on the discharge surface, a suction unit configured to suction the discharge surface, a movement unit configured to move the suction unit relative to the recording head, and a control unit configured to execute a first cleaning mode where, after the application unit applies the cleaning liquid, the suction unit suctions the discharge surface.

BACKGROUND

Field of the Disclosure

The present disclosure relates to a maintenance apparatus that maintains a recording head, a recording apparatus, and a control method.

Description of the Related Art

In a liquid discharge head, if mist or paper dust is attached to the vicinity of discharge ports that discharge a liquid, a discharge failure may occur. Thus, it is necessary to periodically clean the vicinity of the discharge ports and a discharge port surface on which the discharge ports are formed. As a cleaning method of the conventional art, forms are known in which a discharge port surface is wiped with a wiper blade, wiped with a web or a porous body, or cleaned by using a liquid in combination with these methods.

Japanese Patent Application Laid-Open No. 2010-005856 discusses a configuration in which, after a nozzle formation surface to which a cleaning liquid is applied is wiped with a blade, a suction removal unit removes the liquid having entered a gap between head units.

Japanese Patent Application Laid-Open No. 2012-171345 discusses a configuration in which a cleaning liquid collection unit is included that collects an excessive cleaning liquid from a wiping web to which a cleaning liquid is supplied. In the configuration of Japanese Patent Application Laid-Open No. 2010-005856, however, the blade may push the applied cleaning liquid into nozzles. Further, in the configuration of Japanese Patent Application Laid-Open No. 2012-171345, the cleaning liquid collection unit may excessively collect the cleaning liquid, whereby a discharge port surface may not be sufficiently cleaned.

SUMMARY

Some embodiments are directed to providing a maintenance apparatus that prevents a reduction in image quality of an image recorded by a liquid discharge head.

According to an aspect of the present disclosure, a maintenance apparatus includes an application unit configured to come into contact with a discharge surface included in a recording head and apply a cleaning liquid to the discharge surface, wherein discharge ports configured to discharge a liquid are formed on the discharge surface, a suction unit configured to suction the discharge surface, a movement unit configured to move the suction unit relative to the recording head, and a control unit configured to execute a first cleaning mode where, after the application unit applies the cleaning liquid, the suction unit suctions the discharge surface.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments will be described below with reference to the drawings. The following exemplary embodiments, however, do not limit every embodiment, and not all the combinations of the features described in the exemplary embodiments are essential to a solving means of every embodiment. The relative arrangement and the shapes of the components described in the exemplary embodiments are merely illustrative, and do not limit the scope of every embodiment to them only. In the drawings, arrows X and Y indicate horizontal directions orthogonal to each other, and an arrow Z indicates a vertical direction.

FIG.1is a front view schematically illustrating a recording system1according to a first exemplary embodiment. The recording system1is a sheet-fed inkjet printer (inkjet recording apparatus) that transfers an ink image to a recording medium P via a transfer member2, thereby producing a recorded product P′. The recording system1includes a recording apparatus1A and a conveying apparatus1B. In the first exemplary embodiment, an X-direction, a Y-direction, and a Z-direction indicate a depth direction, a width direction (entire length direction) of the recording system1, and a height direction, respectively. The recording medium P is conveyed in the Y-direction.

“Recording” includes not only a case where meaningful information such as a character or a figure is formed, but also a case where an image, a design, or a pattern is broadly formed on a recording medium, regardless of whether meaningful or meaningless, or a case where a medium is processed. It does not matter whether a recording result is visualized so that a person can visually perceive the recording result. A “recording medium” is assumed to be sheet-like paper in the present exemplary embodiment, but may be cloth or a plastic film.

Components of an ink are not particularly limited. In the present exemplary embodiment, a case is described where an aqueous pigment ink containing a color material, water, and a resin is used.

The recording apparatus1A includes a recording unit3, a transfer unit4, peripheral units5A to5D, and a supply unit6.

The recording unit3includes a plurality of recording heads30and a carriage31.FIGS.1and2are referenced.FIG.2is a perspective view of the recording unit3. The recording heads30discharge liquid inks to the transfer member2, thereby forming an ink image of a recorded image on the transfer member2.

In the present exemplary embodiment, each recording head30is a full-line recording head extending in the X-direction, and in the recording head30, nozzles (discharge ports) are arranged in a range corresponding to the width of an image recording region of a recording medium of a maximum size that can be used. The recording head30includes, in an end portion thereof, an ink discharge surface on which the nozzles are open. The ink discharge surface faces the surface of the transfer member2with a minute gap (of several millimeters) therebetween. In the present exemplary embodiment, the transfer member2is configured to cyclically move in a circular orbit, and thus, the plurality of recording heads30is radially placed.

In each nozzle, a discharge element is provided. For example, the discharge element is an element that generates pressure in the nozzle, thereby discharging an ink in the nozzle. A technique for an inkjet recording head of a known inkjet printer is applicable to the discharge element. Examples of the discharge element include an element that causes film boiling in an ink and forms air bubbles using an electrothermal conversion member, thereby discharging the ink, an element that discharges an ink using an electromechanical conversion member, and an element that discharges an ink using static electricity. In terms of recording with high density at high speed, the discharge element using the electrothermal conversion member can be used.

In the present exemplary embodiment, nine recording heads30are provided. The recording heads30discharge inks of different types from each other. The inks of different types are inks of which the color materials are different from each other, and are inks such as a yellow ink, a magenta ink, a cyan ink, and a black ink. Each of the recording heads30discharges one type of ink, but may be configured to discharge a plurality of types of ink. In a case where the plurality of recording heads30is thus provided, some of the plurality of recording heads30may discharge an ink that does not contain a color material (e.g., a clear ink).

The carriage31supports the plurality of recording heads30. An end portion on the ink discharge surface side of each of the recording heads30is fixed to the carriage31. This can maintain the gap between the ink discharge surface and the surface of the transfer member2more accurately. The carriage31is configured to be capable of being displaced by guidance of guide members RL while the recording heads30are mounted on the carriage31. In the present exemplary embodiment, the guide members RL are rail members extending in the X-direction, and the rail members are provided in a pair while being spaced apart in the Y-direction. In side portions in the X-direction of the carriage31, slide portions32are provided. The slide portions32engage with the guide members RL and slide in the X-direction along the guide members RL.

FIG.3illustrates a displacement form of the recording unit3and is a diagram schematically illustrating a right side surface of the recording system1. In the rear of the recording system1, a recovery unit12is provided. The recovery unit12is a mechanism for recovering discharge performance of each recording head30and functions as a maintenance device for maintaining the recording head30. For example, the recovery unit12is provided with a cap mechanism for capping an ink discharge surface33of the recording head30, a cleaning mechanism for cleaning the ink discharge surface33, and a suction mechanism for suctioning ink in the recording head30from the ink discharge surface33by negative pressure.

The guide members RL extend from the sides of the transfer member2to the recovery unit12. The recording unit3can be displaced by the guidance of the guide members RL between a discharge position POS1where the recording unit3is indicated by a solid line, and a cap position POS2where the recording unit3is indicated by a dashed line. The recording unit3is moved by a driving mechanism (not illustrated).

Further, the recording unit3is configured to be capable of being displaced also in the Z-direction by the guidance of a guide member (not illustrated) to a discharge position POS3, a retracted position POS4, and a cap position POS5, and is moved by a driving mechanism (not illustrated).

A position indicated by the discharge position POS1in the X-direction and the discharge position POS3in the Z-direction is a position where the recording unit3discharges inks to the transfer member2, and is a position where the ink discharge surface33of the recording head30faces the surface of the transfer member2.

The retracted position POS4is a position where the recording unit3rises from the discharge position POS3in the Z-direction, and is a position through which the recording unit3passes to move to the cap position POS2immediately above the recovery unit12. In the state where the recording unit3is moved to the retracted position POS4in the Z-direction, the movement of the recording unit3to the cap position POS2in the X-direction is completed, and then, the recording unit3moves down in the Z-direction to the cap position POS5. After the process in which the recording unit3moves to the cap positions POS2and POS5and completion of the movement of the recording unit3, the recovery unit12performs various recovery operations. The details will be described below.

With reference toFIG.1, the transfer unit4is described. The transfer unit4includes a transfer cylinder41and an impression cylinder42. Each of these cylinders is a rotating body that rotates about a rotating shaft in the X-direction, and has a cylindrical outer circumferential surface. InFIG.1, arrows illustrated in the figures of the transfer cylinder41and the impression cylinder42indicate the rotational directions of the transfer cylinder41and the impression cylinder42. The transfer cylinder41rotates clockwise, whereas the impression cylinder42rotates counterclockwise.

The transfer cylinder41is a supporting body that supports the transfer member2on the outer circumferential surface thereof. The transfer member2is continuously or intermittently provided in the circumferential direction on the outer circumferential surface of the transfer cylinder41. In a case where the transfer member2is continuously provided, the transfer member2is formed into an endless belt. In a case where the transfer member2is intermittently provided, the transfer member2is formed into belts having ends in a plurality of segments, and the segments can be placed at regular pitches in an arc shape on the outer circumferential surface of the transfer cylinder41.

By rotation of the transfer cylinder41, the transfer member2cyclically moves in a circular orbit. Based on a rotational phase of the transfer cylinder41, a position on the transfer member2can be identified as being in a formation region R1, a transfer preprocessing region (regions R2and R3), a transfer region R4, a transfer post-processing region R5, and a discharge preprocessing region R6. The transfer member2cyclically passes through these regions.

The formation region R1is a region where the recording unit3discharges inks to the transfer member2, thereby forming an ink image. The transfer preprocessing regions R2and R3are processing regions where processing is performed on the ink image before transfer. The transfer preprocessing region R2is a region where the peripheral unit5A performs processing. The transfer preprocessing region R3is a region where the peripheral unit5B performs processing. The transfer region R4is a region where the transfer unit4transfers the ink image on the transfer member2to a recording medium P. The transfer post-processing region R5is a region where post-processing is performed on the transfer member2after the transfer, and is a region where the peripheral unit5C performs processing. The discharge preprocessing region R6is a region where preprocessing is performed on the transfer member2(a reaction liquid is applied in the present exemplary embodiment) before inks are discharged, and is a region where the peripheral unit5D performs processing.

In the present exemplary embodiment, the formation region R1is a region having a certain section, and the other regions R2to R4are regions that are substantially points in the view shown inFIG.1(in other words, lines in a three-dimensional view). If these regions are likened to a clock face, in the present exemplary embodiment, the formation region R1is in a range from about 11 o'clock to 1 o'clock, the transfer preprocessing region R2is at about the 2 o'clock position, the transfer preprocessing region R3is at about the 4 o'clock position, the transfer region R4is at about the 6 o'clock position, the transfer post-processing region R5is at about the 8 o'clock position, and the discharge preprocessing region R6is at about the 10 o'clock position.

The transfer member2may be composed of a single layer, or may be a laminate of a plurality of layers. In a case where the transfer member2is composed of the plurality of layers, for example, the transfer member2may include three layers, namely a surface layer, an elastic layer, and a compression layer. The surface layer is the outermost layer having an image formation surface on which the ink image is formed. The compression layer is provided to absorb deformation and disperse a local pressure fluctuation. Thus, it is possible to maintain a transfer property even when high speed recording is performed. The elastic layer is a layer between the surface layer and the compression layer.

As a material of the surface layer, various materials, such as a resin and a ceramic, can be appropriately used. In terms of durability, a material having a high compressive elastic modulus can be used. Specifically, examples of the material include an acrylic resin, an acrylic silicone resin, a fluorine-containing resin, and a condensation product obtained by condensing a hydrolyzable organosilicon compound. To improve the wettability of the reaction liquid and the transfer property, the surface layer may be subjected to surface treatment and then used. Examples of the surface treatment include frame treatment, corona treatment, plasma treatment, polishing treatment, roughening treatment, active energy ray irradiation treatment, ozone treatment, surfactant treatment, and silane coupling treatment. A plurality of types of treatment may be combined together. Further, a surface shape may be provided on the surface layer.

Examples of a material of the compression layer include acrylonitrile butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, and silicone rubber. When such a rubber material is molded, a predetermined amount of a vulcanizing agent or a vulcanization accelerator may be blended, and a filler, such as a foaming agent, hollow fine particles, or salt, may be further blended as needed, thereby obtaining a porous rubber material. Consequently, an air bubble portion is compressed with a change in volume in response to various pressure fluctuations, and thus, deformation in a direction other than a compression direction is small. Thus, a more stable transfer property and more stable durability can be obtained. Examples of the porous rubber material include a material having a continuous pore structure where pores are continuous with each other, and a material having a closed pore structure where pores are independent of each other. Either of the structures may be used, and the structures may also be used in combination.

As a material of the elastic layer, various materials, such as a resin and a ceramic, can be appropriately used. In terms of processing characteristics, various elastomer materials and rubber materials can be used. Specifically, examples of the material include fluorosilicone rubber, phenyl silicone rubber, fluoro rubber, chloroprene rubber, urethane rubber, and nitrile rubber. Examples of the material also include ethylene propylene rubber, natural rubber, styrene rubber, isoprene rubber, butadiene rubber, a copolymer of ethylene, propylene, and butadiene, and nitrile butadiene rubber. Particularly, silicone rubber, fluorosilicone rubber, and phenyl silicone rubber have a small compression set and thus are advantageous in terms of dimensional stability and durability. The elastic moduli of these types of rubber change little due to temperature, and thus, these types of rubber are advantageous also in terms of the transfer property.

Between the surface layer and the elastic layer and between the elastic layer and the compression layer, various adhesives or double-sided tapes can also be used to fix these layers. The transfer member2may also include a reinforcement layer having a high compressive elastic modulus to prevent lateral extension when the transfer member2is attached to the transfer cylinder41and to maintain firmness. A woven fabric may be used as the reinforcement layer. The transfer member2can be produced by freely combining layers made of the above materials.

The outer circumferential surface of the impression cylinder42is brought into pressure contact with the transfer member2. On the outer circumferential surface of the impression cylinder42, at least one grip mechanism for holding a leading end of the recording medium P is provided. A plurality of grip mechanisms may be provided spaced apart from each other in the circumferential direction of the impression cylinder42. While the recording medium P is conveyed in close contact with the outer circumferential surface of the impression cylinder42, the ink image on the transfer member2is transferred to the recording medium P when the recording medium P passes through a nip portion between the impression cylinder42and the transfer member2.

The peripheral units5A to5D are placed around the transfer cylinder41. In the present exemplary embodiment, the peripheral units5A to5D are an absorption unit, a heating unit, a cleaning unit, and an application unit, respectively.

The absorption unit5A is a mechanism for absorbing liquid from an ink image on the transfer member2before transfer, and in the present exemplary embodiment in particular, is a mechanism for absorbing moisture from the ink image. By reducing the moisture in the ink image, it is possible to prevent the bleeding of an image recorded on the recording medium P. For example, the absorption unit5A includes an absorption member that comes into contact with the ink image and reduces the amount of moisture in the ink image. The absorption member may be formed on the outer circumferential surface of a roller, or may be formed into an endless sheet and cyclically run. In terms of protection of the ink image, the absorption member may move in synchronization with the transfer member2, and a moving velocity of the absorption member may be the same as a circumferential velocity of the transfer member2. The absorption member may include a porous body that comes into contact with the ink image. To prevent attachment of an ink solid content to the porous body, the average pore diameter of the porous body may be 10 μm or less.

The heating unit5B is a mechanism for heating the ink image on the transfer member2before the transfer. The ink image is heated, whereby a resin in the ink image melts, and a film of the ink image is formed. This improves the transfer property of the ink image to the recording medium P. The heating temperature can be the minimum film forming temperature (MFT) or more of the resin. The MFT can be measured by a generally known technique, such as by using an apparatus compliant with JIS K 6828-2:2003 or ISO2115:1996. In terms of the transfer property and fastness of the image, the ink image may be heated at a temperature higher by 10° C. or more than the MFT, and may further be heated at a temperature higher by 20° C. or more than the MFT. As the heating unit5B, a known heating device, such as various lamps (e.g., an infrared lamp, or a hot air fan), can be used. In terms of heating efficiency, an infrared heater can be used.

The cleaning unit5C is a mechanism for cleaning the transfer member2after the transfer. The cleaning unit5C removes ink remaining on the transfer member2and dust (e.g., paper dust) on the transfer member2. The cleaning unit5C can appropriately use a known method, such as a method for bringing a porous member into contact with the transfer member2, a method for rubbing a surface of the transfer member2with a brush, or a method for scraping a surface of the transfer member2with a blade. As the shape of a cleaning member used for the cleaning, a known shape, such as a roller shape or a web shape, can be used.

The application unit5D is a mechanism for applying a reaction liquid onto the transfer member2after the cleaning unit5C cleans the transfer member2and before the recording unit3discharges inks. The reaction liquid is a liquid that promotes coagulation of a color material. For example, the reaction liquid contains an ink viscosity increasing component. The ink viscosity increasing component may be a metal ion or a polymer coagulant, and is not particularly limited. As the ink viscosity increasing component, a substance that causes a pH change in an ink and coagulation of the color material in the ink can be used. Specifically, an organic acid can be used.

Examples of the mechanism for applying the reaction liquid include a roller, a recording head, a die coating device (a die coater), and a blade coating device (a blade coater). The reaction liquid is applied to the transfer member2before inks are discharged to the transfer member2, whereby it is possible to prevent bleeding in which adjacent inks are mixed together, and beading in which an ink having landed on the transfer member2earlier is drawn by an ink having landed on the transfer member2later.

As described above, in the present exemplary embodiment, the absorption unit5A, the heating unit5B, the cleaning unit5C, and the application unit5D are included as the peripheral units. Alternatively, a cooling function of the transfer member2may be provided to some of the units, or a cooling unit may be added. In the present exemplary embodiment, the heat of the heating unit5B may raise the temperature of the transfer member2. After the recording unit3discharges inks to the transfer member2, if the ink image exceeds the boiling point of water, which is a main solvent of the inks, the moisture absorption performance of the absorption unit5A may decrease. The transfer member2is cooled so that the discharged inks are maintained at less than the boiling point of water, whereby it is possible to maintain the moisture absorption performance.

The cooling unit may be a blower mechanism for sending air to the transfer member2or a mechanism for bringing a member (e.g., a roller) into contact with the transfer member2while the member is cooled by air cooling or water cooling. Alternatively, the cooling unit may be a mechanism for cooling the cleaning member of the cleaning unit5C. The cooling timing may be a period after transfer and before application of the reaction liquid.

The supply unit6is a mechanism for supplying inks to the recording heads30of the recording unit3. The supply unit6may be provided on the rear side of the recording system1. The supply unit6includes storage portions TK that each store an ink of different type. Each of the storage portions TK may include a main tank and a sub-tank. The storage portion TK and the corresponding recording head30communicate with each other via a flow path6a, and the storage portion TK supplies an ink to the recording head30.

The flow path6amay be a flow path for circulating an ink between the storage portion TK and the recording head30, and the supply unit6may include a pump that circulates the ink. In the middle of the flow path6aor in the storage portion TK, a deaeration mechanism for removing air bubbles in an ink may be provided. In the middle of the flow path6aor in the storage portion TK, a valve for making an adjustment between fluid pressure of an ink and atmospheric pressure may be provided. The heights in the Z-direction of the storage portion TK and the recording head30may be designed so that an ink liquid surface in the storage portion TK is at a position lower than a position of the ink discharge surface33of the recording head30.

The conveying apparatus1B is an apparatus that feeds a recording medium P to the transfer unit4and discharges, from the transfer unit4, a recorded product P′ to which an ink image is transferred. The conveying apparatus1B includes a feeding unit7, a plurality of conveying cylinders8and8a, two sprockets8b, a chain8c, and a collection unit8d. InFIG.1, an arrow inside the figure of each component of the conveying apparatus1B indicates the rotational direction of the component, and arrows outside the figures of the components indicate a conveying path of the recording medium P or the recorded product P′. The recording medium P is conveyed from the feeding unit7to the transfer unit4, and the recorded product P′ is conveyed from the transfer unit4to the collection unit8d. In the conveying direction, a feeding unit7side may be referred to as an upstream side, and a collection unit8dside may be referred to as a downstream.

The feeding unit7includes a stacking portion in which a plurality of recording media P is stacked, and also includes a feeding mechanism for feeding the recording media P one by one from the stacking portion to the most upstream conveying cylinder8. Each of the conveying cylinders8and8ais a rotating body that rotates about a rotating shaft in the X-direction, and includes a cylindrical outer circumferential surface. On the outer circumferential surface of each of the conveying cylinders8and8a, at least one grip mechanism for holding a leading end of the recording medium P (or the recorded product P′) is provided. A gripping operation and a release operation of the grip mechanism are controlled so that the recording medium P is received and delivered between the adjacent conveying cylinders.

The two conveying cylinders8aare conveying cylinders for reversing the recording medium P. In the case of one-sided recording, the conveying cylinders8aare not used to convey the recording medium P. In a case where two-sided recording is performed on the recording medium P, after an image is transferred to the front side of the recording medium P, the impression cylinder42delivers the recording medium P to the conveying cylinders8awithout delivering the recording medium P to the conveying cylinder8adjacent to and downstream of the impression cylinder42. The front and back sides of the recording medium P are reversed via the two conveying cylinders8a, and the recording medium P is delivered to the impression cylinder42again via the conveying cylinder8upstream of the impression cylinder42. Consequently, the back side of the recording medium P faces the transfer cylinder41, and an ink image is transferred to the back side.

The chain8cis wound around the two sprockets8b. One of the two sprockets8bis a driving sprocket, and the other is a driven sprocket. Rotation of the driving sprocket cyclically runs the chain8c. In the chain8c, a plurality of grip mechanisms is provided spaced apart from each other in the longitudinal direction of the chain8c. The grip mechanisms grip an end portion of the recorded product P′. The recorded product P′ is delivered from the conveying cylinder8located at the downstream end to the grip mechanisms of the chain8c. The recorded product P′ gripped by the grip mechanisms is conveyed to the collection unit8dby the running of the chain8c, and the gripping is released. Thus, the recorded product P′ is stacked in the collection unit8d.

In the conveying apparatus1B, post-processing units10A and10B are provided. The post-processing units10A and10B are placed downstream of the transfer unit4and are mechanisms for performing post-processing on a recorded product P′. The post-processing unit10A performs processing on the front side of the recorded product P′, and the post-processing unit10B performs processing on the back side of the recorded product P′. An example of the processing is coating of an image recording surface of the recorded product P′ for the purpose of protecting or glossing the image. Examples of the coating include application of a liquid, adhesion of a sheet, and lamination.

In the conveying apparatus1B, inspection units9A and9B are provided. The inspection units9A and9B are placed downstream of the transfer unit4and are mechanisms for inspecting the recorded product P′.

In the present exemplary embodiment, the inspection unit9A is an imaging apparatus that captures an image recorded on the recorded product P′. The inspection unit9A includes an image sensor, such as a charge-coupled device (CCD) sensor or a complementary metal-oxide-semiconductor (CMOS) sensor. The inspection unit9A captures the recorded image while a recording operation is continuously performed. Based on the image captured by the inspection unit9A, the inspection unit9A can confirm a change over time in color of the recorded image and determine whether recording data can be corrected. In the present exemplary embodiment, an image capturing range of the inspection unit9A is set to the outer circumferential surface of the impression cylinder42, and the inspection unit9A is placed so that the recorded image immediately after transfer can be partially captured. The inspection unit9A may inspect all recorded images, or may inspect every predetermined number of recorded images.

In the present exemplary embodiment, the inspection unit9B is also an imaging apparatus that captures an image recorded on the recorded product P′. The inspection unit9B includes an image sensor, such as a CCD sensor or a CMOS sensor. The inspection unit9B captures the recorded image in a test recording operation. The inspection unit9B captures the entire recorded image, and based on the image captured by the inspection unit9B, the inspection unit9B can make basic settings of various corrections regarding the recording data. In the present exemplary embodiment, the inspection unit9B is placed at a position where the inspection unit9B can capture the recorded product P′ conveyed by the chain8c. In a case where the inspection unit9B captures the recorded image, the running of the chain8cis temporarily stopped, and the inspection unit9B captures the entire recorded image. The inspection unit9B may be a scanner that scans the recorded product P′.

Next, control units of the recording system1are described.FIGS.4and5are block diagrams illustrating a control unit13of the recording system1. The control unit13is connected to a superordinate apparatus (e.g., digital front end (DFE)) HC2so that the control unit13can communicate with the superordinate apparatus HC2. The superordinate apparatus HC2is connected to a host apparatus HC1so that the superordinate apparatus HC2can communicate with the host apparatus HC1.

The host apparatus HC1generates recording data from which a recorded image is generated. The recording data is generated in a format of an electronic file, such as a document file or an image file. The recording data is transmitted to the superordinate apparatus HC2, and the superordinate apparatus HC2converts the received recording data into a data format (e.g., data of cyan, magenta, yellow, and black (CMYK) colors) that can be used by the control unit13. The converted recording data is transmitted from the superordinate apparatus HC2to the control unit13, and based on the recording data received by the control unit13, the control unit13starts the recording operation.

In the present exemplary embodiment, the control unit13is roughly divided into a main controller13A and an engine controller13B. The main controller13A includes a processing unit131, a storage unit132, an operation unit133, an image processing unit134, a communication interface (I/F)135, a buffer136, and a communication I/F137.

The processing unit131is a processor such as a central processing unit (CPU). The processing unit131executes a program stored in the storage unit132and controls the entire main controller13A. The storage unit132is a storage device, such as a random-access memory (RAM), a read-only memory (ROM), a hard disk, or a solid-state drive (SSD). The storage unit132stores a program to be executed by the CPU131and data and provides a work area to the CPU131. The operation unit133is an input device, such as a touch panel, a keyboard, or a mouse, and receives an instruction from a user.

For example, the image processing unit134is an electronic circuit including an image processing processor. The buffer136is a RAM, a hard disk, or an SSD, for example. The communication I/F135communicates with the superordinate apparatus HC2. The communication I/F137communicates with the engine controller13B. InFIG.4, a dashed arrow indicates an example of a processing procedure of recording data. The recording data received from the superordinate apparatus HC2via the communication I/F135is accumulated in the buffer136. The image processing unit134reads the recording data from the buffer136, performs predetermined image processing on the read recording data, and stores the recording data in the buffer136again. The recording data subjected to the image processing and stored in the buffer136is transmitted from the communication I/F137to the engine controller13B.

As illustrated inFIG.5, the engine controller13B includes control units14and15A to15E. The engine controller13B acquires detection results of a sensor group and actuator group16included in the recording system1and controls driving of the sensor group and actuator group16. Each of the control units14and15A to15E includes a processor such as a CPU, a storage device such as a RAM or a ROM, and an interface with an external device. Divisions of the control units are merely examples, and part of control may be executed by a plurality of subdivided control units. Conversely, a configuration may be employed in which a plurality of control units is integrated together and the control contents of the plurality of control units are performed by a single control unit.

The engine control unit14controls the entire engine controller13B. The recording control unit15A converts recording data received from the main controller13A into a data format suitable for driving the recording heads30, such as raster data. The recording control unit15A controls discharge of each recording head30.

The transfer control unit15B controls the absorption unit5A, the heating unit5B, the cleaning unit5C, and the application unit5D.

The reliability control unit15C controls the supply unit6and the recovery unit12, and controls the driving mechanism for moving the recording unit3between the discharge position POS1and the recovery position (cap position) POS2.

The conveyance control unit15D controls the conveying apparatus1B. The inspection control unit15E controls the inspection unit9B and the inspection unit9A.

In the sensor group and actuator group16, the sensor group includes a sensor that detects a position and a velocity of a movable portion, a sensor that detects temperature, and an image sensor. The actuator group includes a motor, an electromagnetic solenoid, and an electromagnetic valve.

FIG.6is a diagram schematically illustrating an example of a recording operation. While the transfer cylinder41and the impression cylinder42are rotated, the following operations are cyclically performed. As illustrated in a state ST1, first, the application unit5D applies a reaction liquid L onto the transfer member2. A region on the transfer member2to which the reaction liquid L is applied moves with the rotation of the transfer cylinder41. If the region to which the reaction liquid L is applied reaches below the recording head30, then as illustrated in a state ST2, the recording head30discharges an ink to the transfer member2. Thus, an ink image IM is formed. At this time, the discharged ink is mixed with the reaction liquid L on the transfer member2, thereby accelerating the coagulation of a color material. The discharged ink is supplied from one of the storage portions TK of the supply unit6to the recording head30.

The ink image IM on the transfer member2moves with the rotation of the transfer member2. If the ink image IM reaches the absorption unit5A, then as illustrated in a state ST3, the absorption unit5A absorbs moisture from the ink image IM. If the ink image IM reaches the heating unit5B, then as illustrated in a state ST4, the heating unit5B heats the ink image IM, a resin in the ink image IM melts, and a film of the ink image IM is formed. In synchronization with such formation of the ink image IM, a recording medium P is conveyed by the conveying apparatus1B.

As illustrated in a state ST5, the ink image IM and the recording medium P reach the nip portion between the transfer member2and the impression cylinder42, and the ink image IM is transferred to the recording medium P, thereby a recorded product P′ is produced. If the recorded product P′ passes through the nip portion, an image recorded on the recorded product P′ is captured by the inspection unit9A, and the recorded image is inspected. The recorded product P′ is conveyed to the collection unit8dby the conveying apparatus1B.

If a portion on the transfer member2where the ink image IM has been formed reaches the cleaning unit5C, then as illustrated in a state ST6, the portion is cleaned by the cleaning unit5C. After the cleaning, the transfer member2completes one rotation. By a similar procedure, an ink image IM is repeatedly transferred to a recording medium P. In the above description, to facilitate understanding, the description has been given where an ink image IM is transferred to one recording medium P once in one rotation of the transfer member2. An ink image IM, however, can be successively transferred to a plurality of recording media P in one rotation of the transfer member2.

If such a recording operation is continued, it is necessary to clean the recording heads30.FIG.7illustrates an example of an operation when the recording heads30are cleaned. A state ST11illustrates the state where the recording unit3is located at the discharge position POS1. A state ST12illustrates the state where the recording unit3is displaced to the recovery position POS2. Then, as illustrated in a state ST13, the recovery unit12executes the processing of recovering the performance of the recording heads30of the recording unit3.

The recovery unit12according to the present exemplary embodiment is described in detail.FIG.8is a top perspective view of the recovery unit12. In the recovery unit12, a cleaning unit200and an equalization unit300are arranged along the X-direction. The cleaning unit200and the equalization unit300are provided for each of the recording heads30.

FIGS.9A and9Billustrate top perspective views of the cleaning unit200. The cleaning unit200includes a cleaning roller210that rotates to apply a cleaning liquid to the ink discharge surface33, a rotary motor220that rotates the cleaning roller210, and a drive train221connected to the rotary motor220. The cleaning unit200further includes a liquid application nozzle230that applies a liquid to the cleaning roller210, a squeeze roller240that squeezes the cleaning roller210, and an air cylinder241that causes the squeeze roller240to abut on the cleaning roller210.

The cleaning roller210is obtained by assembling a cylindrical porous body having a predetermined thickness to a metal core roller composed of a resin or metal material. In the present exemplary embodiment, a polyurethane material having a thickness of 10 mm is used as the porous body. The porous body, however, is not limited to this material as long as the porous body satisfies functional conditions, such as a liquid contact property with respect to an ink and a cleaning liquid, a water retention capability, and cleaning performance. At one end in the axial direction of the metal core roller, a gear221afor connecting to the drive train221is provided.

The cleaning roller210is configured to come into contact with the ink discharge surface33of the recording head30with a predetermined pressing force. In the present exemplary embodiment, the cleaning roller210is configured so that the pressing force is 0.5 to 1.0 kgf. The pressing force is appropriately set based on the cleaning conditions, the material of the cleaning roller210, and the durability of a discharge surface of a head. More specifically, the contact between the cleaning roller210and the ink discharge surface33may be fine contact or contact with a pressing force exceeding 1.0 kgf, depending on conditions. The effect of some embodiments is not impaired in either way. The contact between the cleaning roller210and the ink discharge surface33may be managed not based on the pressing force, but based on an amount of penetration into the ink discharge surface33using the elastic force of the porous body. In this case, it is desirable that the amount of penetration be 5 to 20% of the thickness of the porous body. However, even if the amount of penetration is less than 5% or exceeds 20% of the thickness of the porous body, the effect of some embodiments is not impaired.

FIGS.10A and10Bare transparent cross-sectional views of the cleaning unit200viewed from the Y-direction. The squeeze roller240is configured to squeeze out an excess of a liquid supplied to the cleaning roller210, thereby maintaining the cleaning roller210. The squeeze roller240is formed of a resin or metal material and is configured to rotate about a rotating shaft.

The squeeze roller240is not connected to the drive train221, and is driven to rotate with rotation of the cleaning roller210in an operation described below. The squeeze roller240, however, is not limited to the configuration in which the squeeze roller240is driven to rotate to obtain the effect of some embodiments. The rotating shaft is connected to the air cylinder241via a link and is configured to be capable of switching abutment and separation operations in the normal direction of the cleaning roller210.

The amount of penetration of the squeeze roller240into the cleaning roller210is 50% of the thickness of the cleaning roller210. The amount of penetration, however, can be set in a wide range from about 90% of the thickness of the cleaning member to almost 0%, which is a fine contact state. More specifically, the amount of penetration is a parameter that widely fluctuates depending on component members of the recording head30to be used, the ink composition, and the printing time. To squeeze the cleaning roller210more strongly, the amount of penetration is increased. The effect of some embodiments does not depend on the presence or absence of the squeeze roller240. For example, in a case where the cleaning member is configured to be periodically replaced, the squeeze roller240may not be included.

The liquid application nozzle230applies a cleaning liquid to the cleaning roller210by sending the liquid by a pump from a liquid supply unit, which is separately configured. In the liquid application nozzle230, six holes each having a diameter of about 0.3 mm are placed next to each other on the side surface of a cylindrical shape. The diameter of each hole is appropriately set in a range of about 0.1 to 1.5 mm based on viscosity and a supply amount of the liquid or the pressure loss in a path.

The cleaning liquid to be applied to the cleaning roller210is composed of a mixture of glycerin, an alkaline solvent, a surfactant, and water. Ratios of these components are determined based on the cleaning performance of fixed ink, the degree of sealing of a liquid tank, and the chemical resistance of the component members of the recording head30. Regarding the type of mixture, the mixture may contain only water as long as conditions are satisfied. The type of mixture is not uniquely limited.

The operation of the cleaning unit200is described. The rotary motor220is driven to rotate the cleaning roller210via the drive train221and to cause the liquid application nozzle230to abut on the cleaning roller210and to cause the squeeze roller240to abut on the cleaning roller210by the driving of the air cylinder241. These units only need to act simultaneously when the recording head30is actually cleaned, and thus, the order of operations does not matter.

The rotational direction of the cleaning roller210is set to the same direction as a relative moving direction relative to the recording head30. The rotational velocity of the cleaning roller210is set so that a difference between the rotational velocity and a relative velocity relative to the recording head30is small. This is to reduce wear of both the recording head30(ink discharge surface33) and the cleaning roller210. To remove dirt on the ink discharge surface33more strongly, however, the rotational direction can also be set to a direction opposite to the relative moving direction.

FIG.11is a top perspective view of the equalization unit300for a single color of ink. The equalization unit300includes a suction wiping unit400and a cap unit500inside. The equalization unit300functions to position these units relative to the recording head30. The equalization unit300is configured to, by a lifting and lowering mechanism (not illustrated), switch between the cap position POS5where the equalization unit300caps the recording head30, and the retracted position POS4, where the equalization unit300is retracted from the recording head30.

Inside the equalization unit300, the suction wiping unit400is configured to be slidable, and the cap unit500is configured to be lifted and lowered.FIG.12Ais a perspective view illustrating a suction wiping unit driving portion for driving the suction wiping unit400.FIG.12Bis an enlarged perspective view illustrating the vicinity of a driving motor430. As illustrated inFIGS.12A and12B, the driving portion includes a driving rail410for sliding the suction wiping unit400, a driving motor430, a drive train440, and a driving belt420for transmitting drive.

FIG.13is a perspective view illustrating a cap unit driving portion for driving the cap unit500. The driving portion includes an air cylinder510that moves the cap unit500up and down, a cam520that operates by the air cylinder510, and a cam follower530that engages with the cam520.

FIG.14is a top perspective view illustrating the detailed configuration of the suction wiping unit400. The suction wiping unit400includes a suction nozzle450that suctions an ink while wiping the ink by abutting on the ink discharge surface33, a suction nozzle holder451that holds the suction nozzle450, and a suction unit base452. The suction nozzle450is connected to a suction pump (not illustrated) in a different unit via a tube.

The suction nozzle450is composed of a rubber-like elastic body. In the present exemplary embodiment, the suction nozzle450is composed of hydrogenated nitrile butadiene rubber (HNBR) having a Shore A hardness of 50±5. The material type and the hardness of the rubber-like elastic body, however, are not limited to obtain the effect of some embodiments as long as conditions, such as a liquid contact property with respect to an ink and a cleaning liquid, adhesiveness with a discharge nozzle surface, durability, and weather resistance, are satisfied. For example, urethane rubber, silicone rubber, ethylene propylene diene monomer rubber (EPDM), or fluoro rubber may be used.

The suction nozzle450is assembled to the suction nozzle holder451. The suction nozzle holder451supports the suction nozzle450to maintain the shape of the suction nozzle450, and further functions as a negative pressure path for generating negative pressure in the suction nozzle450. However, in a case where the hardness of the material of the suction nozzle450is high, the suction nozzle holder451does not need to be configured to maintain the shape of the suction nozzle450. In the middle of a path from the suction nozzle holder451to the suction pump, a valve and a pressure sensor are appropriately provided.

The suction nozzle holder451is attached to the suction unit base452so that the suction nozzle holder451can slide up and down. A spring pressing force is applied to the suction nozzle holder451in the upward direction. This is to increase adhesiveness and the capability to follow unevenness when the suction nozzle450comes into contact with the discharge nozzle surface. The suction unit base452is linked to the driving rail410so that the suction unit base452can slide in contact with the driving rail410. The suction unit base452is also connected to the drive train440and the driving motor430via the driving belt420.

As the suction pump, a diaphragm-type dry vacuum pump is employed. This is because a high degree of vacuum and a high flow rate are required to suck out a cleaning liquid having a higher viscosity than that of an ink from ink discharge nozzles. It is desirable that the vacuum pump be used in a state where a chemical solution does not flow into the vacuum pump. Thus, a gas-liquid separation configuration is included upstream of the vacuum pump. To obtain the effect of some embodiments, however, the form of the pump is not limited. A form in which a tube pump or a liquid diaphragm pump is used can also be employed as long as various conditions, such as the viscosity of the cleaning liquid and the shape of the ink discharge nozzles, are satisfied.

On the suction unit base452, a blade460that wipes the outside of a discharge region of the ink discharge surface33is provided. More specifically, the discharge region of the ink discharge surface33is wiped and suctioned by the suction nozzle450. The blade460is placed to wipe the ink discharge surface33subsequently to wiping by the suction nozzle450in wiping of the ink discharge surface33by the suction wiping unit400. To follow unevenness of the recording head30(the ink discharge surface33), the blade460includes a plurality of blades. In the present exemplary embodiment, two first blades461that wipe a protruding portion and two second blades462that wipe a portion other than the protruding portion are provided.

FIGS.15A,15B,15C, and15Dare diagrams illustrating the detailed configuration of the cap unit500.FIG.15Ais a top view of the cap unit500.FIG.15Bis a cross-sectional view of the cap unit500as viewed from the Y-direction.FIG.15Cis an A-A cross-sectional view ofFIG.15A.FIG.15Dis a B-B cross-sectional view ofFIG.15B.

The cap unit500includes a cap550that caps the ink discharge surface33, a cap holder551that holds the cap550, and a cap holder base552. The cap unit500further includes a cap absorber553disposed inside the cap550, a cap cleaning liquid supply path554, a liquid discharge path555, and an atmosphere communication port556that causes the inside of the cap550to communicate with atmosphere.

The cap550is composed of a rubber-like elastic body. In the present exemplary embodiment, the cap550is composed of chlorinated butyl rubber having a Shore A hardness of 50±5. The cap550is incorporated into the cap holder551, and the cap absorber553is laid inside the cap550. The cap cleaning liquid supply path554and the liquid discharge path555extend in the longitudinal direction in contact with the cap absorber553. Further, at both end portions in the longitudinal direction of the cap unit500, the cap unit500includes the atmosphere communication port556that causes the inside of the cap550to communicate with atmosphere.

The cap holder551is attached to the cap holder base552so that the cap holder551can swing relative to the cap holder base552. To swing means to perform a complex operation of an up-down movement and a rotational movement about a shaft557extending in the Y-direction. Swinging of the cap holder551is restricted by the pressing force of a spring placed between the cap holder551and the cap holder base552. When the cap550comes into contact with the recording head30(the ink discharge surface33), a rib surface558of the cap550uniformly comes into close contact with the ink discharge surface33by the swinging operation of the cap holder551and the action of spring pressure. This can prevent drying of the discharge ports formed on the ink discharge surface33.

The cap holder base552is further connected to the cam follower530inside the equalization unit300. The cam follower530is configured to be movable relative to the cam520. The cam520is configured to slide by the air cylinder510. In the cam520, a groove in an oblique direction is formed, and the cam follower530moves inside the groove, thereby converting a slide operation of the air cylinder510in a lateral direction into an operation of the cap holder base552in the up-down direction.

As for the recovery unit12, as many recovery units12as the number of recording heads30are provided. In the present exemplary embodiment, nine recovery units12corresponding to the nine recording heads30are provided. The number of actuators that drive the units, however, is not necessarily equal to the number of the units. For example, in the present exemplary embodiment, one air cylinder510performs lifting and lowering operations of three cap units500. The numbers can be flexibly changed depending on a scale of the apparatus and the number of recording heads30, and is not limited thereto.

Next, a cleaning operation using the recovery unit12is described.FIG.16is a flowchart for selecting a cleaning mode after the recording operation ends. During the recording operation using each recording head30, the reliability control unit15C counts the number of times an ink is discharged from the discharge ports (hereinafter also referred to as a dot count value).

In S1601, the reliability control unit15C determines whether the dot count value counted after the previous cleaning exceeds a predetermined dirt threshold. The dirt threshold is a value indicating a state where the ink discharge surface33is likely to be dirty by ink mist. For example, the dirt threshold is set based on an experimental value.

If the dot count value exceeds the dirt threshold (YES in S1601), then in S1602, the reliability control unit15C executes a first cleaning mode. If, on the other hand, the dot count value does not exceed the dirt threshold (NO in S1601), then in S1603, the reliability control unit15C executes a second cleaning mode.

FIG.17is a flowchart illustrating the first cleaning mode. A series of cleaning operations described below is all controlled by the reliability control unit15C.

In S1701, the operation of the cleaning unit200is started, and the cleaning roller210cleans the ink discharge surface33. In S1702, if the supply unit6performs an ink circulation operation, the circulation operation is stopped. This is to prevent a cleaning liquid having entered the discharge ports by the operation for cleaning from being mixed with an ink in an ink flow path by the ink circulation operation. The circulation operation, however, does not have to be stopped if the amount of cleaning liquid entering the discharge ports is an extremely minute amount with respect to an amount of ink held in the entire ink circulation flow path and is in a range that does not affect a completed recorded product.

In S1703, moving of the carriage31is started.FIGS.19A,19B, and19Cillustrate movements of the carriage31in the first cleaning mode and are diagrams schematically illustrating the right side surface of the recording system1. In S1703, the carriage31is lifted to a cleaning position POS6, which is a position above the discharge position POS3and below the retracted position POS4in the Z-direction (FIG.19A). The cleaning position POS6is a position in the Z-direction for cleaning the ink discharge surface33by the cleaning unit200.

Then, as illustrated inFIG.19B, the carriage31moves from the discharge position POS1to the cap position POS2in the X-direction. Then, as illustrated inFIG.19C, the carriage31is lowered in the Z-direction, thereby completing the movement to the cap position POS5.

In S1704, if it is confirmed that the carriage31has moved to the cap positions POS2and POS5(YES in S1704), then in S1705, the suction wiping unit400performs suction wiping. Specifically, inside the equalization unit300, a retracting operation of the cap unit500is performed, and the suction wiping unit400moves to a wiping start position. Then, the equalization unit300positions the suction wiping unit400relative to the recording head30.

FIGS.20A,20B,20C, and20Dare schematic side views illustrating movements of the suction wiping unit400.FIG.20Aillustrates the retracting operation of the cap unit500.FIG.20Billustrates a state where the suction wiping unit400moves to the wiping start position. Then, as illustrated inFIG.20C, the equalization unit300positions the suction wiping unit400relative to the recording unit3(the recording head30).

After the suction pump starts suction, then as illustrated inFIG.20D, the suction wiping unit400moves from the wiping start position to a wiping end position. In the present exemplary embodiment, a standby position (a home position) of the suction wiping unit400is in the rear of the recording apparatus1A. Thus, the scanning direction of the suction wiping unit400is a direction from the front to the rear of the recording apparatus1A, i.e., a direction from upstream to downstream in the X-direction.

After the suction wiping ends, then in S1706, the cap unit500is lifted up, and the ink discharge surface33of the recording head30is capped with the cap550. In S1707, it is determined whether a preliminary discharge operation is necessary. If the preliminary discharge operation is necessary (YES in S1707), then in S1708, the recording head30discharges an ink to the cap550. The preliminary discharge operation is performed, for example, in a case where required conditions are satisfied for the purpose of refreshing a heater provided in the ink discharge nozzles or detecting a discharge failure. If the preliminary discharge operation is executed, a liquid discharge operation for discharging a liquid from the liquid discharge path555provided in the cap550is also performed, thereby the ink discharged into the cap550is discharged. Further, after the preliminary discharge operation ends, it is desirable to periodically supply a cap cleaning liquid from the cap cleaning liquid supply path554and clean the cap absorber553.

Next, with reference toFIG.18, the second cleaning mode is described. In the second cleaning mode, unlike the first cleaning mode, the cleaning unit200does not perform cleaning. In other words, the second cleaning mode is the mode of performing a cleaning operation weaker than that in the first cleaning mode.

In S1801, the carriage31is lifted in the Z-direction, thereby moving from the discharge position POS3to the retracted position POS4. Then, the carriage31moves from the discharge position POS1to the cap position POS2in the X-direction. Further, the carriage31is lowered to the cap position POS5in the Z-direction (seeFIG.3). In S1802, if it is confirmed that the carriage31has moved to the cap positions POS2and POS5(YES in S1802), then in S1803, the suction wiping unit400performs suction wiping. This operation is similar to that in the first cleaning mode. Then, in51804to S1806, operations similar to those in S1706to S1708in the first cleaning mode are performed.

As described above, in the present exemplary embodiment, the cleaning unit200applies a cleaning liquid to the ink discharge surface33, and then, the suction wiping unit400suctions the cleaning liquid. Consequently, even if the cleaning liquid is pushed into the discharge ports, the cleaning liquid can be discharged to the outside by suction wiping. Thus, it is possible to prevent a reduction in image quality due to mixing of the cleaning liquid with an ink discharged from the recording head30. The present exemplary embodiment is effective particularly because it is possible to prevent the cleaning liquid from being mixed in a circulation flow path in a form in which inks are circulated between the storage portions TK and the recording heads30.

Further, whether to apply the cleaning liquid in the cleaning operation for cleaning the recording head30is switched based on the dot count value. More specifically, the recording apparatus1A according to the present exemplary embodiment can execute the first cleaning mode where the cleaning liquid is applied, and the second cleaning mode where the cleaning liquid is not applied. Consequently, the cleaning liquid is not applied to the ink discharge surface33when not necessary. Thus, it is possible to prevent a reduction in image quality due to the mixing of the cleaning liquid into the discharge ports.

In the first exemplary embodiment, the form is employed in which the recording unit3includes the plurality of recording heads30. Alternatively, a form may be employed in which the recording unit3includes only one recording head30. Yet alternatively, each recording head30can employ a serial method for discharging an ink while moving in a direction intersecting the conveying direction of the recording medium P, instead of being a full-line head.

A conveying mechanism for conveying the recording medium P may be a method of nipping and conveying the recording medium P by a roller pair. In the method of conveying the recording medium P by the roller pair, a form may be employed in which a roll sheet is used as the recording medium P, and the roll sheet is cut after transfer, thereby the recorded product P′ is produced. Further, in the first exemplary embodiment, the transfer member2is provided on the outer circumferential surface of the transfer cylinder41. Alternatively, a method may be employed in which the transfer member2is formed into an endless belt that is caused to cyclically run.

In the first exemplary embodiment, the cleaning roller210is used as an application unit that applies a cleaning liquid to the ink discharge surface33, but a shape of the application unit is not limited to a roller shape. The effect of some embodiments can also be obtained by the application unit having a block shape or a web shape using a woven fabric or a non-woven fabric. In the operation of the application unit having the block shape, the application unit may be moved relative to the ink discharge surface33in the state where the application unit is in contact with the ink discharge surface33, or may perform a stamp-like operation by combining an up-down movement and a relative movement. In the operation of the application unit having the web shape using a woven fabric or a non-woven fabric, a rectangular material may be moved in a direction similar to the relative moving direction to bring a relative velocity relative to the discharge nozzle surface infinitely close to zero, similarly to the operation of the application unit having the roller shape, or the rectangular material may be moved in a direction opposite to the relative moving direction, thereby proactively scraping dirt. Alternatively, a backup member formed of an elastic body may be provided to increase adhesiveness to the ink discharge surface33.

As the form of supplying a cleaning liquid, the liquid application nozzle is employed in the first exemplary embodiment, but is not limited thereto. A form may be employed in which a cleaning liquid stored in a liquid tank is drawn up by a method suitable for each form. In the case of a roller form, a liquid may be supplied from inside via a seal bearing using a shaft having a hollow path that communicates with a cleaning member.

Regarding the form of removing an excessive cleaning liquid, the squeeze roller is employed in the present exemplary embodiment, but is not limited thereto. For example, the excessive cleaning liquid may be blown away by air blow, or may be removed by suction. The liquid may be removed by pressing a material having a strong capillary force against the liquid.

OTHER EMBODIMENTS

This application claims priority to Japanese Patent Application No. 2020-197647, which was filed on Nov. 27, 2020 and which is hereby incorporated by reference herein in its entirety.