JP6081891B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus.

  Inkjet recording devices are widely used as printers, copiers, multifunction devices, and the like because they are smaller and less expensive than electrophotographic recording devices and can reduce power consumption because they do not require a fixing device. In an ink jet recording apparatus, ink droplets are ejected from a plurality of nozzles provided in a nozzle head, and an image is formed on a recording medium such as paper.

  Ink used in the ink jet recording apparatus includes, for example, an oil-based ink mainly using an organic solvent as a solvent and an aqueous ink mainly using water as a solvent. In consideration of environmental considerations, water-based inks that do not contain organic solvents that are harmful to the environment are being developed.

  When water-based ink is used, water penetrates the paper printing surface and the fibers swell, so the expansion of the printing surface is greater than the expansion of the non-printing surface, and the difference between the elongation of the printing surface and the non-printing surface is the difference. Is likely to occur. That is, a stress difference is likely to occur between the printed surface and the non-printed surface. Due to this stress difference, a curling (or cockling) phenomenon occurs in which the printing surface warps in a convex shape.

  As a measure for suppressing curling, a technique of adding a habit that bends in the direction opposite to the curling direction is known (see Patent Document 1). Patent Document 1 discloses a decurling mechanism having a hard roller and a soft roller that are pressed against each other. Curling is suppressed by causing the decurling mechanism to pass the printed paper between rollers and bending the paper in the direction opposite to the curling direction.

JP 2006-082909 A

  The decurling mechanism described in Patent Document 1 is used in an electrophotographic recording apparatus to correct a curl generated when heated by a fixing device. However, even if the decurling mechanism described in Patent Document 1 is applied to an ink jet recording apparatus, the curl correction is not sufficient, and especially when water-based ink is used, the curl cannot be sufficiently corrected. It is done.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording apparatus capable of suppressing curling occurring on a recording medium.

  In order to achieve the above object, an ink jet recording apparatus of the present invention includes a recording medium transport mechanism, a head unit, and a liquid application unit. The recording medium transport mechanism transports a recording medium. The head unit ejects ink onto the recording medium. The liquid application unit includes an application roller that applies liquid to the recording medium conveyance mechanism.

  According to the ink jet recording apparatus of the present invention, curling that occurs in a recording medium can be suppressed.

Schematic diagram showing a schematic configuration of the inkjet recording apparatus 1 of the present embodiment. It is a mimetic diagram showing grant roller 410A of other embodiments. It is a schematic diagram which shows the provision roller 410B of further embodiment. It is a schematic diagram which shows schematic structure of other embodiment of the inkjet recording device 1 by this invention. It is a schematic diagram which shows schematic structure of further embodiment of the inkjet recording device 1 by this invention. (A) shows a state where the first transport unit 320A is at the image forming position, and (b) shows a state where the first transport unit 320A is at the cleaning position.

  Hereinafter, an embodiment of an ink jet recording apparatus according to the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a schematic diagram showing a schematic configuration of an ink jet recording apparatus 1 of the present embodiment. As shown in FIG. 1, the inkjet recording apparatus 1 includes an apparatus housing 100, a paper feeding unit 200, an image forming unit 300, a liquid applying unit 400, a carry-in transport unit 500, a discharge transport unit 600, and a reverse transport unit 700. .

  The paper feed unit 200 includes a paper feed cassette 201, a manual feed tray 202, and a paper feed roller 203. The paper feed cassette 201 is detachably attached to the apparatus casing 100 and is installed below the apparatus casing 100. In the paper feed cassette 201, paper P as a plurality of recording media is stored in a stacked state. The manual feed tray 202 is installed on one side outside the apparatus housing 100. Paper P to be fed one by one is placed on the manual feed tray 202. The paper feed roller 203 is installed above one end side of the paper feed cassette 201 and the manual feed tray 202. The paper feed roller 203 transports the paper P in the paper feed cassette 201 or the paper P placed on the manual feed tray 202 to the carry-in transport unit 500.

  The carry-in conveyance unit 500 is installed on one side of the image forming unit 300. The carry-in conveyance unit 500 includes a plurality of conveyance roller pairs 501 that form a carry-in path 503 for the paper P. The paper P conveyed from the paper feed cassette 201 or the manual feed tray 202 is conveyed to the image forming unit 300 along the carry-in path 503 by the conveyance roller pair 501. In the present embodiment, the carry-in conveyance unit 500 includes a registration roller pair 502 that functions as the conveyance roller pair 501. The registration roller pair 502 is provided on the exit side of the carry-in path 503. The registration roller pair 502 temporarily waits for the paper P and then transports the paper P to the image forming unit 300 in accordance with the printing timing.

  The image forming unit 300 forms an image on the paper P. A method in which the image forming unit 300 forms an image on the paper P is an ink jet recording method. The image forming unit 300 is installed above the paper feeding unit 200. The image forming unit 300 includes a head unit 310 and a recording medium transport mechanism 320.

  The head unit 310 forms an image by ejecting ink onto the paper P conveyed by the recording medium conveyance mechanism 320. The image is formed on the first surface of the first surface (surface P1 shown in FIG. 1) and the second surface (surface P2 shown in FIG. 1) of the paper P. The first surface is a surface facing the head portion 310 when the paper P is transported by the recording medium transport mechanism 320. The second surface is a surface that contacts the recording medium conveyance mechanism 320 when the paper P is conveyed by the recording medium conveyance mechanism 320. In the present embodiment, the image forming unit 300 includes four head units 310Y, 310M, 310C, and 310K arranged in parallel from the upstream side to the downstream side in the paper transport direction.

  Each of the head portions 310Y, 310M, 310C, and 310K includes a plurality of nozzles (not shown) arranged in the width direction (Y direction) of the recording medium transport mechanism 320. Ink is ejected from the plurality of nozzles onto the first surface of the paper P. The head part 310 is called a line type. For example, the line-type head unit 310 is fixed to the apparatus housing 100.

  The recording medium transport mechanism 320 includes a support roller 321, a drive roller 322, a tension roller 323, a transport belt 324, and a suction unit 325.

  The conveyor belt 324 is endless and is stretched so as to surround the support roller 321, the drive roller 322, and the tension roller 323. The transport belt 324 receives the paper P from the carry-in transport unit 500 and transports the paper P to the discharge transport unit 600. A plurality of through holes (not shown) penetrating the conveying belt 324 in the thickness direction are perforated.

  The suction unit 325 functions as suction means such as a fan or a vacuum pump. When the suction unit 325 is driven, a negative pressure is generated. The negative pressure acts on the paper P supported on one surface of the transport belt 324 through the plurality of through holes of the transport belt 324, and the paper P is sucked onto the transport belt 324.

  The drive roller 322 is installed at an interval in the paper transport direction with respect to the support roller 321. The drive roller 322 is rotationally driven by the drive unit 322a. The drive unit 322a is, for example, a motor. The driving roller 322 rotates the transport belt 324 in the first direction (arrow D1 direction) that is the transport direction of the paper P and in the second direction (arrow D2 direction) opposite to the first direction D1. The tension roller 323 is installed below the support roller 321 and the drive roller 322 and applies tension to the transport belt 324.

  The discharge conveyance unit 600 is installed on the other side of the image forming unit 300. The discharge conveyance unit 600 includes a plurality of conveyance roller pairs 601 constituting a carry-out path 603 and a discharge tray 602. The discharge tray 602 is installed on the other side outside the apparatus housing 100. The single-side printed paper P conveyed from the recording medium conveyance mechanism 320 is conveyed to the discharge tray 602 along the carry-out path 603 by the conveyance roller pair 601.

  The reverse conveyance unit 700 is a conveyance unit for performing double-sided printing. The reverse conveyance unit 700 is installed above the image forming unit 300. The reverse conveyance unit 700 includes a plurality of conveyance roller pairs 701 that constitute a reverse path 702. When duplex printing is performed, the paper P on which an image is formed on the first surface (surface P1) is conveyed to the reverse conveyance unit 700 via the discharge conveyance unit 600. The paper P transported to the reverse transport unit 700 is switched in the transport direction in the reverse path 702, and the paper P is again a recording medium with the unprinted surface (surface P2) facing the head unit 310 as the first surface. It is transported to the transport mechanism 320.

  The liquid application unit 400 applies liquid to the recording medium transport mechanism 320. Specifically, the liquid application unit 400 applies liquid to the conveyance belt 324 of the recording medium conveyance mechanism 320. For example, the liquid applied by the liquid applying unit 400 is water.

  The liquid application unit 400 includes an application roller 410 and an application amount adjustment unit 420. The application roller 410 is configured so as to be movable in the distance from the conveyance belt 324 of the recording medium conveyance mechanism 320 and is installed so as to be in pressure contact with the conveyance belt 324. The application roller 410 has, for example, a circular outer peripheral surface, and the liquid adheres to the outer peripheral surface of the application roller 410. The application roller 410 applies (applies) a liquid to the conveyance belt 324 through a contact area (nip portion) with the conveyance belt 324 while rotating. When forming an image on the paper P, the liquid applied to the transport belt 324 is transferred to the second surface of the paper P transported by the transport belt 324.

  The application amount adjustment unit 420 adjusts the amount of liquid applied by the application roller 410 to the conveyance belt 324 according to the amount of ink ejected onto the first surface of the paper P by the head unit 310 of the image forming unit 300. Specifically, when the amount of ink ejected on the first surface of the paper P is large, the application amount adjusting unit 420 increases the area of the contact area between the application roller 410 and the conveyance belt 324 so that the application roller 410 increases. Is moved toward the conveyor belt 324. By increasing the area of the contact area between the applying roller 410 and the transport belt 324, the amount of liquid applied to the transport belt 324 increases. As an example of the application amount adjustment unit 420, a microcomputer including a CPU, a ROM, and a RAM is used. The CPU executes the liquid amount adjustment according to the program stored in the ROM.

  The ink jet recording apparatus 1 of the present embodiment has been described with reference to FIG. According to the inkjet recording apparatus 1 of the present embodiment, in the case of single-sided printing, ink is applied to the first surface (surface P1) of the paper P, and liquid is applied to the second surface (surface P2) of the paper P. . The stress on the first surface where the fiber swells by absorbing ink and the stress on the second surface where the fiber swells by absorbing liquid cancels out, and the stress difference between the first surface and the second surface is small. Become. As a result, the curling phenomenon of the paper P due to the stress difference can be suppressed.

  On the other hand, in the case of duplex printing, the paper P is conveyed again to the image forming unit 300 and ink is applied to the first surface (here, the surface P2) of the paper P. Since the paper P is conveyed to the image forming unit 300 with the curl corrected, in the image forming unit 300, the paper P is attracted by the recording medium conveyance mechanism 320 and conveyed in a flat state. As a result, an image can be accurately formed on the paper P. Even in the case of double-sided printing, liquid can be applied to the second surface (here, surface P1) of the paper P in order to correct curl.

  In the present embodiment, the application roller 410 has a circular outer peripheral surface, but the present invention is not limited to this as shown in FIGS. 2 and 3.

  Drawing 2 is a mimetic diagram showing grant roller 410A of other embodiments. A protrusion 413A made of an elastic body is formed on the surface of the application roller 410A. Specifically, the application roller 410A has a core shaft 411A and a coating layer 412A. The core shaft 411A is connected to a drive unit (not shown) that rotationally drives the application roller 410A. The covering layer 412A is covered with the core shaft 411A and rotates together with the core shaft 411A. The covering layer 412A is made of rubber, for example. The coating layer 412A has a plurality of annular protrusions 413A formed along the circumferential direction of the application roller 410A. The plurality of protrusions 413A are arranged along the axial direction in which the application roller 410A rotates. The protrusion 413A has a tapered shape that tapers along the radial direction of the application roller 410A (the direction orthogonal to the direction in which the rotation axis extends).

  When the application roller 410A moves toward the conveyance belt 324 by the control of the application amount adjustment unit 420, the tip of the projection 413A made of an elastic body is pressed and deformed, so that the contact between the projection 413A and the conveyance belt 324 is achieved. The area of the area increases. As a result, the amount of liquid transferred from the applying roller 410A to the conveying belt 324 increases. On the other hand, when the application roller 410A moves in a direction away from the conveyor belt 324 under the control of the application amount adjusting unit 420, the tip of the pressed projection 413A changes to the original shape due to elasticity, and thus the projection 413A and the conveyor belt The area of the contact region with 324 is reduced. As a result, the amount of liquid transferred from the applying roller 410A to the transport belt 324 is reduced. Thus, according to the application roller 410A of the present embodiment, the amount of liquid applied to the transport belt 324 can be easily adjusted.

  Drawing 3 is a mimetic diagram showing grant roller 410B of a further embodiment. A protrusion 413B made of an elastic body is formed on the surface of the applying roller 410B. The application roller 410B has the same configuration as the application roller 410A described with reference to FIG. 2 except that the protrusion 413B is formed in a spiral shape with respect to the circumferential direction of the application roller 410B. Yes. According to the application roller 410A of the present embodiment, when the application roller 410B rotates, the liquid can be uniformly applied to the support surface of the transport belt 324 by the spiral protrusion 413B.

  In the inkjet recording apparatus 1 of the present embodiment, the application amount adjustment unit 420 is not limited to an essential configuration. For example, a predetermined amount of liquid may be applied to the conveyor belt 324 by fixing the application roller 410 at a predetermined position and making the area of the contact area between the application roller 410 and the conveyor belt 324 constant.

  FIG. 4 is a schematic diagram showing a schematic configuration of another embodiment of the inkjet recording apparatus 1 according to the present invention. Hereinafter, the ink jet recording apparatus 1 of the present embodiment will be described with reference to FIG. In the present embodiment, the ink jet recording apparatus 1 has a point that the recording medium transport mechanism 320 includes a first transport unit 320A and a second transport unit 320B, and a liquid application unit 400 further includes a tank 430 and a supply roller 440. Except for the above, the configuration is the same as that of the embodiment described with reference to FIG.

  The first conveyance unit 320 </ b> A of the recording medium conveyance mechanism 320 is installed to face the head unit 310 of the image forming unit 300. The first transport unit 320A includes a support roller 321A, a driving roller 322A, a tension roller 323A, a transport belt 324A, and a suction unit 325A. The transport belt 324A receives the paper P from the carry-in transport unit 500 and transports the paper P to the second transport unit 320B. While the paper P is conveyed by the conveyance belt 324A, the image forming unit 300 forms an image on the first surface (surface P1) of the paper P. Each component of the first transport unit 320A is the same as the component of the recording medium transport mechanism 320 described with reference to FIG.

  The second transport unit 320B of the recording medium transport mechanism 320 is installed on the downstream side in the transport direction of the paper P with respect to the first transport unit 320A. The second transport unit 320B includes a support roller 321B, a driving roller 322B, a tension roller 323B, a transport belt 324B, and a suction unit 325B. The conveyance belt 324B receives the paper P from the first conveyance unit 320A and conveys the paper P to the discharge conveyance unit 600. Each component of the second transport unit 320B is the same as the component of the recording medium transport mechanism 320 described with reference to FIG.

  In the present embodiment, the liquid application unit 400 applies a liquid to the second transport unit 320B. The application roller 410 of the liquid application unit 400 is installed so as to be in pressure contact with the conveyance belt 324B of the second conveyance unit 320B. Liquid is stored in the tank 430 of the liquid application unit 400. The supply roller 440 is installed so that a part thereof is immersed in the liquid in the tank 430. The supply roller 440 supplies the liquid in the tank 430 to the application roller 410 while rotating. The liquid supplied to the applying roller 410 is transferred to the second surface of the paper P conveyed by the conveying belt 324B after being applied to the conveying belt 324B.

  The ink jet recording apparatus 1 of the present embodiment has been described with reference to FIG. In the inkjet recording apparatus 1, the recording medium transport mechanism 320 may be pulled away from the image forming unit 300 for jamming or cleaning of the head unit 310. According to the present embodiment, the recording medium transport mechanism 320 includes a first transport unit 320A and a second transport unit 320B. Therefore, only the first transport unit 320A can be configured to be movable up and down, and the movable part of the inkjet recording apparatus 1 can be reduced.

  In the embodiment described with reference to FIG. 4, the liquid applying unit 400 applies the liquid to the second transport unit 320B. However, as shown in FIG. 5, the present invention is not limited to this.

  FIG. 5 is a schematic diagram showing a schematic configuration of a further embodiment of the ink jet recording apparatus 1 according to the present invention. Hereinafter, the ink jet recording apparatus 1 of the present embodiment will be described with reference to FIG. In the present embodiment, the inkjet recording apparatus 1 is the same as the embodiment described with reference to FIG. 4 except that the liquid is applied to the first transport unit 320A and the cleaning mechanism 800 is further provided. Since it has a structure, description of the overlapping part is omitted.

  In the present embodiment, the liquid application unit 400 applies liquid to the conveyance belt 324A of the first conveyance unit 320A. Specifically, the application roller 410 of the liquid application unit 400 is installed so as to be in pressure contact with the conveyance belt 324A of the first conveyance unit 320A. The liquid supplied to the application roller 410 is applied to the transport belt 324 and then transferred to the second surface of the paper P transported by the transport belt 324A.

  The cleaning mechanism 800 includes an elevating unit (not shown), an elevating detection unit (not shown), a cleaning member 810, and a conveyance control unit 820.

  The elevating unit moves up and down the first transport unit 320A. Specifically, the first transport unit 320A is configured to be movable between the image forming position and the cleaning position. The image forming position is a position of the first transport unit 320A when image formation is performed on the first surface of the paper P. The cleaning position is a position where the first conveying unit 320A is lowered from the image forming position and the conveying belt 324A and the cleaning member 810 are in pressure contact with each other. The elevating unit moves up and down the first conveying unit 320A so as to move between the image forming position and the cleaning position.

  The cleaning member 810 is installed below the first transport unit 320A so as to come into pressure contact with the transport belt 324A of the first transport unit 320A lowered by the elevating unit. In the present embodiment, the cleaning member is a roller. The cleaning member 810 is rotated in the same direction as the first direction D1 (see FIG. 6) (in the direction of the arrow D3 shown in FIG. 6) and the second direction D2 (see FIG. 6) by the rotation drive unit 811 (for example, a motor). It can rotate in the direction (arrow D4 direction shown in FIG. 6). Note that the cleaning member 810 is formed so as to include a material having good liquid absorption. As such a material, for example, a porous body or a nonwoven fabric can be used.

  The elevation detection unit detects the position of the elevation unit. The conveyance control unit 820 is configured by a microcomputer including a CPU, a ROM, and a RAM. The CPU executes predetermined processing in accordance with a program stored in the ROM. The conveyance control unit 820 controls the drive unit 322a of the drive roller 322A and the rotation drive unit 811 of the cleaning member 810 based on information output from the elevation detection unit.

  Next, the operation and effect of this embodiment will be described. FIG. 6 is an operation explanatory diagram of the first transport unit 320A and the cleaning mechanism 800 of the present embodiment. FIG. 6A shows a state where the first transport unit 320A is at the image forming position, and FIG. 6B shows a state where the first transport unit 320A is at the cleaning position.

  At the time of image formation, the head portions 310Y, 310M, 310C, and 310K eject ink onto the first surface of the paper P, and the ink on the paper P is dried, whereby an image is formed on the paper P. During image formation, the conveyance belt 324A is driven to rotate in the first direction D1.

  At the time of cleaning, when an instruction to start belt cleaning is given via an operation panel (not shown), the lifting unit of the cleaning mechanism 800 moves the first transport unit 320A downward. And as shown in FIG.6 (b), when the 1st conveyance part 320A reaches a belt cleaning position, it will be detected by the raising / lowering detection part, and an raising / lowering part will stop.

  As shown in FIG. 6B, the outer peripheral surface of the cleaning member 810 is pressed against the support surface of the paper P in the transport belt 324A. Then, the driving unit 322a of the driving roller 322A is driven, and the conveying belt 324A is driven to rotate in the second direction D2.

  The driving roller 322A drives the conveying belt 324A by frictional force generated between the driving roller 322A and the conveying belt 324A. Therefore, when the transport belt 324A is driven in the second direction, the transport belt 324A is in tension due to the tension applied from the drive roller 322A to the transport belt 324A on the upstream side of the drive roller 322A in the second direction D2. It becomes.

  As a result, the cleaning member 810 pressed against the conveyance belt 324A receives a large reaction force from the conveyance belt 324A, and thus the pressure contact force generated between the conveyance belt 324A and the cleaning member 810 increases. Therefore, the cleaning effect of the conveyance belt 324A can be improved.

  The ink jet recording apparatus 1 of this embodiment has been described with reference to FIGS. 5 and 6. In the present embodiment, the cleaning member 810 can contact and separate from the conveyance belt 324A, and the cleaning member 810 is pressed against the conveyance belt 324A only when the conveyance belt 324A is cleaned. Therefore, when the image is formed, the cleaning member 810 does not hinder the driving of the conveyance belt 324A, and adverse effects in the image formation can be suppressed. Further, when the image is formed, the cleaning member 810 is separated from the conveyance belt 324A, so that the cleaning member 810 can be prevented from being damaged. Therefore, the life of the cleaning member 810 can be extended.

  When the cleaning member 810 cleans the transport belt 324A, the cleaning member 810 is driven to rotate in the same direction D4 as the second direction D2. Since the portion of the cleaning member 810 that contacts the conveying belt 324A and the portion of the conveying belt 324A that contacts the cleaning member 810 move in opposite directions, the relative speed between the cleaning member 810 and the conveying belt 324A. Increases, and the frictional force between the cleaning member 810 and the conveyor belt 324A increases. As a result, the cleaning effect of the conveyance belt 324A can be further improved.

  In the present embodiment, liquid can be applied to the transport belt 324A when cleaning the transport belt 324A. When a liquid is applied to the conveyance belt 324A, the ink that has adhered to the support surface of the conveyance belt 324A and solidified becomes soft and easily removed by absorbing the liquid. As a result, the cleaning effect of the conveyance belt 324A can be further improved.

  In the present embodiment, the cleaning member 810 is pressed against the transport belt 324A of the first transport unit 320A lowered to the cleaning position, but the present invention is not limited to this. The cleaning member 810 may be installed so as to be in pressure contact with the transport belt 324A of the first transport unit 320A disposed at the image forming position.

  In each embodiment described above, the liquid applied to the recording medium transport mechanism 320 is water, but the present invention is not limited to this. The liquid may contain additives in addition to water. Additives are, for example, preservatives, antifungal agents, and surfactants. For example, the liquid may be a transparent ink that does not contain a pigment.

  In each of the above-described embodiments, the case where the present invention is applied to an ink jet recording apparatus including the line-type head unit 310 fixed to the apparatus housing 100 has been described. It is not limited to a device. For example, the present invention may be applied to an ink jet recording apparatus that includes a recording head that moves relative to the apparatus housing 100. For example, the present invention may be applied to an ink jet recording apparatus including a serial type head unit.

  The ink jet recording apparatus of the present invention is suitably used as, for example, an image forming apparatus such as a printer, a copying machine, or a multifunction machine, or an information communication device such as a FAX. According to the ink jet recording apparatus of the present invention, curling that occurs in a recording medium can be suppressed.

DESCRIPTION OF SYMBOLS 100 Apparatus housing 200 Paper feed part 201 Paper feed cassette 202 Manual feed tray 203 Paper feed roller 300 Image forming part 310 Head part 320 Recording medium conveyance mechanism 320A First conveyance part 320B Second conveyance part 400 Liquid application part 410 Application roller 420 Application Quantity adjustment unit 430 Tank 440 Supply roller 500 Carry-in transport unit 501 Transport roller pair 502 Registration roller pair 503 Transport path 600 Discharge transport unit 603 Transport path 601 Transport roller pair 602 Discharge tray 700 Reverse transport unit 702 Reverse path 701 Transport roller pair 800 Cleaning Mechanism 810 Cleaning member 811 Rotation drive unit 820 Transport control unit

Claims (11)

A recording medium conveying mechanism including a conveying belt for conveying the recording medium;
A head portion for ejecting ink onto the recording medium;
An application roller for applying liquid to the recording medium transport mechanism, and a liquid application unit having an application amount adjustment unit,
The application amount adjustment unit adjusts an area of a contact area between the application roller and the transport belt in accordance with the amount of the ink ejected from the head unit. The application roller includes a protrusion formed of an elastic body,
The given amount adjusting unit is
Moving the application roller toward the conveyor belt, pressing the tip of the protrusion, increasing the area of the contact area between the protrusion and the conveyor belt;
2. The application roller is moved in a direction away from the conveyor belt, and the tip of the protrusion is changed to an original shape by elasticity to reduce an area of a contact area between the protrusion and the conveyor belt. 2. An ink jet recording apparatus according to 1. Projections that are elastic bodies are formed along the circumferential direction on the surface of the application roller,
The inkjet recording apparatus according to claim 1, wherein the protrusion has a tapered shape that tapers along a radial direction of the application roller. A protrusion formed of an elastic body is formed in a spiral shape on the surface of the application roller,
The inkjet recording apparatus according to claim 1, wherein the protrusion has a tapered shape that tapers along a radial direction of the application roller. The recording medium transport mechanism includes a first transport unit,
The first transport unit faces the head unit,
The inkjet recording apparatus according to claim 1, wherein the application roller of the liquid application unit applies the liquid to the first transport unit. The recording medium transport mechanism includes a first transport unit and a second transport unit,
The first conveyor is opposed to the head portion, wherein the conveyor belt,
The second transport unit is disposed downstream of the first transport unit in the transport direction of the recording medium, and includes a transport belt that transports the recording medium ,
5. The inkjet recording apparatus according to claim 1, wherein the application roller of the liquid application unit applies the liquid to the conveyance belt of the second conveyance unit.   The inkjet recording according to any one of claims 1 to 6, wherein the liquid application unit further includes a tank that stores the liquid and a supply roller that supplies the liquid from the tank to the application roller. apparatus. A cleaning mechanism having a cleaning member;
The recording medium transport mechanism includes a first transport unit,
The first transport unit faces the head unit,
The first conveyor has said conveyor belt,
The ink jet recording apparatus according to claim 1, wherein the cleaning member is pressed against the transport belt of the first transport unit to clean the transport belt. The first transport unit further includes a drive unit that drives the transport belt in a first direction and a second direction that is opposite to the first direction,
The cleaning mechanism further includes a conveyance control unit that controls the driving unit,
The cleaning member is in pressure contact with the transport belt of the first transport unit on the downstream side in the first direction with respect to the drive unit;
The inkjet recording apparatus according to claim 8, wherein the conveyance control unit controls the driving unit so that the conveyance belt is driven in the second direction when the cleaning member performs cleaning of the conveyance belt. . The cleaning mechanism further includes an elevating unit that elevates and lowers the first transport unit,
10. The inkjet recording apparatus according to claim 8, wherein the cleaning member is in pressure contact with the conveyance belt of the first conveyance unit lowered by the elevating unit.   11. The ink jet recording apparatus according to claim 8, wherein the application roller applies the liquid to the transport belt when the cleaning member cleans the transport belt. 11.

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