Patent Publication Number: US-10759196-B2

Title: Recording device

Description:
BACKGROUND 
     The invention relates to a recording device that performs recording on a medium. 
     Some known ink jet printers as one type of recording devices include a paper transport device that transports roll paper as one type of media. For example, when recording having a high printing ratio (duty) is performed on roll paper in an ink jet printer, many ink particles are discharged onto the roll paper. A so-called cockle caused by the roll paper absorbing a large amount of ink and swelling in a wave shape may be generated in the roll paper to which many ink particles are adhering. 
     A recording device including ribs provided on a platen facing a recording head is used for solving a malfunction that a cockle is generated (JP-A-2006-95976). The printer described in JP-A-2006-95976 is configured in such a way that a cockle can escape between the ribs, and a cockle generated in a medium by a suction hole provided between the ribs can be reliably sucked to the ribs and a formation surface of the ribs. 
     SUMMARY 
     Some ink jet printers include a drying unit that dries a medium on which recording is executed and is located downstream from a recording head in a transport direction of a medium. When roll paper that has absorbed a large amount of ink is dried by this drying unit, a dry wrinkle generated in the drying unit may extend upstream in the transport direction and reach the platen. In this case, there is a risk that roll paper may not be completely adhered to the platen by the suction hole due to the large dry wrinkle even with the platen described in JP-A-2006-95976. Then, there is a risk that the medium may lifts up from the platen due to the dry wrinkle reaching the platen, and the roll paper lifting up from the platen may collide with the recording head moving in a direction intersecting the transport direction of the roll paper. 
     One advantage of certain embodiments is to provide a recording device capable of reducing contact between a medium in which a dry wrinkle arises and a recording head. 
     To solve the problem above, according to one embodiment, a recording device includes a carriage including a recording head configured to discharge liquid onto a medium and being movable in an intersecting direction, the intersecting direction intersecting a transport direction, a suction platen facing the recording head and being configured to suck the medium, a transport mechanism provided upstream from the suction platen in the transport direction of the medium and configured to transport the medium downstream in the transport direction, a drying unit located downstream from the recording head in the transport direction, a medium suction mechanism configured to suck the medium fed to the drying unit, and a controller configured to control the transport mechanism. In the recording device, the controller is configured to form a curved portion by curving, between the drying unit and the suction platen in the transport direction, a part of the medium. 
     In the above embodiment, the curved portion can be formed by curving a part of the medium, between the drying unit and the suction platen in the transport direction. For example, when a dry wrinkle arising in the drying unit extends, in the medium, upstream in the transport direction, the curved portion can prevent the dry wrinkle from extending, in the medium, to the suction platen. As a result, the medium on the suction platen can be less likely to lift up from the suction platen, and contact between the medium on the suction platen and the recording head can be suppressed. 
     In a recording device according to another embodiment, when a maintenance operation of the recording head is executed while a part of the medium is located in the drying unit, the controller is configured to move the carriage in the intersecting direction for the maintenance operation, after the curved portion has been formed. And the curved portion is formed by feeding the medium by a predetermined amount by the transport mechanism while the medium is sucked by the medium suction mechanism and sucking the medium by the suction platen after the medium fed by the predetermined amount. 
     In the above embodiment, when the maintenance operation of the recording head is executed while a part of the medium is located in the drying unit, moving the carriage before the maintenance operation is executed after the curved portion has been formed. Therefore, when the curved portion is formed, that is, when the medium on the suction platen is less likely to be lifted up from the platen, the carriage moves in the intersecting direction and then the maintenance operation is executed. Thus, contact between the medium on the suction platen and the recording head during the movement operation can be more reliably suppressed. 
     A recording device according to another embodiment further includes a discharge mechanism provided downstream from the suction platen in the transport direction and configured to discharge the medium. In the recording device, the controller, after the execution of the maintenance operation, is configured to eliminate the curved portion by stopping sucking the medium by the suction platen and the medium suction mechanism, and feeding the medium downstream in the transport direction by the discharge mechanism after stopping sucking. 
     In the above embodiment, contact between the medium on the suction platen and the recording head can be suppressed by forming the curved portion. Thus, smudging the medium on the suction platen due to contact with the recording head can be suppressed. As a result, the recording operation can restart from the portion of the medium located on the suction platen only by eliminating the curved portion from the medium. Thus, a portion of the medium without execution of recording between a portion on which recording has already been executed (portion located in the drying unit) and a portion on which recording is to be newly executed can be reduced in length, so that waste paper in the medium can be reduced. 
     In a recording device according to another embodiment, the controller, after the maintenance operation, is configured to eliminate the curved portion by stopping sucking the medium the suction platen, and feeding the medium upstream in the transport direction by the transport mechanism after stopping sucking. 
     In the above embodiment, the portion of the medium in which the curved portion is formed is wound back to the suction platen, and recording can be executed by the recording head. Thus, a gap between the recorded portions of the medium in the transport direction can be reduced, and the amount of waste paper in the medium can be reduced. 
     A recording device according to another embodiment further includes a maintenance mechanism configured to perform maintenance on the recording head. In the recording device, one side of a region of movement of the carriage in the intersecting direction is a home position, and the maintenance mechanism is disposed on the other side. 
     In the above embodiment, the recording device can achieve an effect similar to that in any of the other embodiments described above. 
     In a recording device according to another embodiment, the maintenance operation is executed after the carriage have been moved from the one side to the other side in the intersecting direction. 
     In the above embodiment, at this time, the carriage moves to the other side while the curved portion is formed. Thus, contact between the recording head and the medium on the suction platen can be more reliably reduced. 
     In a recording device according to according to another embodiment, the maintenance mechanism includes a waste liquid receiving portion configured to receive liquid discharged from the recording head during the maintenance operation and a wiper configured to clean a nozzle surface of the recording head. 
     In the above embodiment, the recording device can achieve an effect similar to that in any of the other embodiments described above. 
     A recording device according to another embodiment further includes a discharge mechanism provided downstream from the suction platen in the transport direction and configured to discharge the medium. In the recording device, the curved portion is formed by adjusting at least one of a medium feeding speed of the transport mechanism and a medium feeding speed of the discharge mechanism. 
     In the above embodiment, the curved portion is formed by adjusting at least one of the medium feeding speed of the transport mechanism and the medium feeding speed of the discharge mechanism, and thus the size of the curved portion to be formed can be adjusted as appropriate. As a result, the curved portion having the appropriate size according to a kind of the medium is formed, and thus a dry wrinkle extending from the drying unit can be more reliably prevented by the curved portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a perspective view of an external appearance of a printer in the disclosure. 
         FIG. 2  is a front view of the printer in the disclosure. 
         FIG. 3  is a perspective view illustrating a home position side of a carriage in the printer. 
         FIG. 4  is a perspective view illustrating a maintenance mechanism in the printer. 
         FIG. 5  is a perspective view illustrating a state where the carriage is located above a suction platen during a maintenance operation. 
         FIG. 6  is a side cross-sectional view illustrating a medium transport path of the printer in the disclosure. 
         FIG. 7  is a side cross-sectional view illustrating a state where a medium is transported by a transport mechanism and a discharge mechanism in the medium transport path of the printer. 
         FIG. 8  is a side cross-sectional view illustrating a state where a curved portion is formed in a medium between a drying unit and the suction platen in the medium transport path of the printer. 
         FIG. 9  is a flowchart during the maintenance operation in the printer. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments will be described with reference to drawings. Note that, the same configuration has the same reference sign in each of the exemplary embodiments and is described only in the first exemplary embodiment, and description of the configuration is omitted in the following exemplary embodiment. 
       FIG. 1  is a perspective view of an external appearance of a printer.  FIG. 2  is a front view of the printer.  FIG. 3  is a perspective view illustrating a home position side of a carriage in the printer.  FIG. 4  is a perspective view illustrating a maintenance mechanism in the printer. 
       FIG. 5  is a perspective view illustrating a state where the carriage is located above a suction platen during a maintenance operation.  FIG. 6  is a side cross-sectional view illustrating a medium transport path of the printer.  FIG. 7  is a side cross-sectional view illustrating a state where a medium is transported by a transport mechanism and a discharge mechanism in the medium transport path of the printer. In this disclosure, a medium transport direction is a direction along the medium transport path. 
       FIG. 8  is a side cross-sectional view illustrating a state where a curved portion is formed in a medium between a drying unit and the suction platen in the medium transport path of the printer.  FIG. 9  is a flowchart during the maintenance operation in the printer. 
     In an X-Y-Z coordinate system illustrated in each drawing, an X direction indicates both a device width direction and a medium width direction, a Y direction indicates the medium transport direction at a recording position, at which the medium is recorded, in a recording device, and a Z direction indicates a device height direction. Note that, in each drawing, the +X direction side is one side, the −X direction side is the other side, the +Y direction side is a device front side, and the −Y direction side is a device rear side. 
     Exemplary Embodiment 
     Overview of Recording Device 
     In  FIG. 1 , an ink jet printer  10  (hereinafter a printer  10 ) is described as one example of a recording device. The ink jet printer  10  includes a main body unit  12  and a pair of leg portions  14 . The pair of leg portions  14  are provided on a lower portion of the main body unit  12  with some intervals between the pair of leg portions  14  in the X-axis direction. The leg portions  14  extend downward from the lower portion of the main body unit  12 . Rollers  16  are provided on a lower portion of each of the leg portions  14 . 
     The rollers  16  are rotatably provided on the leg portions  14 . In the exemplary embodiment, the rotation of the rollers  16  with respect to an installation surface can facilitate the movement of the ink jet printer  10 . 
     In the exemplary embodiment, the main body unit  12  is formed into a rectangular parallelepiped as one example, and a drying unit  18  is provided on the front side of the main body unit  12 . With reference to  FIGS. 2 and 6 , a main frame  20  extending in the X-axis direction is provided in an upper portion of the main body unit  12 . A carriage  22  is attached to the front side of the main frame  20 . The carriage  22  is configured to be movable back and forth in the X-axis direction along the main frame  20 . The X-axis direction intersect the transport direction. A recording head  24  ( FIGS. 2, 6 , and the like) is disposed in a lower portion of the carriage  22 . 
     Note that, in the exemplary embodiment, a movement region of the carriage  22  is a region between a state (position of the carriage provided with a reference sign  22 ) where the carriage  22  is located on a +X direction side-end portion of the main frame  20  and a state (position of the carriage provided with a reference sign  22 - 1 ) where the carriage  22  is located on a −X direction side-end portion of the main frame  20 . 
     The recording head  24  includes a plurality of nozzles (not illustrated) capable of discharging ink as “liquid” downward, as one example. Specifically, a lower surface of the recording head  24  is formed as a nozzle surface including the plurality of nozzles. 
     The +X direction side-end portion (one side) of the main body unit  12  in  FIGS. 2 and 3  is a home position of the carriage  22  as one example. A cap  26  is provided in the home position (on the +X direction side-end portion) in the main body unit  12 . The cap  26  is configured to cover the nozzle surface of the recording head  24  while the recording head  24  is located in the home position. 
     A maintenance mechanism  28  performing maintenance on the recording head  24  is provided on the −X direction side-end portion (on the other side) of the main body unit  12  in  FIGS. 2, 4, and 5 . In the exemplary embodiment, the maintenance mechanism  28  includes a flushing receiving portion  30 , a waste liquid receiving portion  32 , and a wiper  34 . The flushing receiving portion  30  faces the recording head  24  while the carriage  22  is located in a flushing position (position in  FIG. 5 ). In this state, at least a part of the recording head  24  is located above a suction platen  36 . The flushing receiving portion  30  receives the ink discharged from the recording head  24  when a flushing operation is executed during execution of a recording operation. When the recording head  24  executes the flushing operation and discharges the ink downward, the flushing receiving portion  30  is configured to absorb the discharged ink. In the exemplary embodiment, an ink absorbing body as one example is disposed in the flushing receiving portion  30 . 
     Further, the waste liquid receiving portion  32  and the wiper  34  are provided on the outside (−X-axis direction side) of the flushing receiving portion  30  in the X-axis direction. The waste liquid receiving portion  32  includes an ink absorbing body disposed inside the waste liquid receiving portion  32 , and is configured to be able to absorb the ink discharged from the recording head  24 . The wiper  34  is configured as a cloth material as one example and configured to be movable in the Y-axis direction. The wiper  34  is configured to be able to wipe the lower surface, namely, the nozzle surface of the recording head  24  while the recording head  24  is in a state (not illustrated) of being located in a position facing the waste liquid receiving portion  32 . 
     Next, with reference to  FIG. 2 or 4 , the flat suction platen  36  extending in the X-axis direction is provided between the cap  26  and the flushing receiving portion  30  in the X-axis direction. A plurality of ribs, which are not illustrated, extending in the Y-axis direction are provided at appropriate intervals in the X-axis direction on an upper surface of the suction platen  36 . A plurality of through holes (not illustrated) penetrating the suction platen  36  in the Z-axis direction are formed between the plurality of ribs. 
     A suction fan  38  ( FIG. 6 or 8 ) is disposed below the suction platen  36 . When the suction fan  38  is driven, gas above the suction platen  36  is sucked via the through holes (not illustrated) of the suction platen  36 . This forms a flow of the gas from above to below the suction platen  36  as indicated by arrows A 1  in  FIG. 8 . As a result, while a medium P (see a thick line provided with a reference sign P in  FIGS. 6 and 8 ) is located on the suction platen  36 , the medium P is sucked by the suction platen  36  and pressed against the upper surface of the suction platen  36 . 
     With Regard to Medium Transport Path 
     Next, a transport path of the medium P in the printer  10  is described with reference to  FIGS. 6 and 8 . As illustrated in  FIG. 6 , a paper feeding unit  40  is provided on the rear side (−Y-axis direction side) of the printer  10 , and a paper discharging unit  42  is provided below the drying unit  18  on the front side (+Y-axis direction side). A configuration of the paper feeding unit  40  and the paper discharging unit  42  is described in  FIG. 2  by taking the paper feeding unit  42  as an example. Note that, the paper feeding unit  40  and the paper discharging unit  42  are omitted from  FIG. 1 . The thick line provided with the reference sign P in  FIGS. 6 and 8  represents the medium P. 
     The paper discharging unit  42  includes a pair of bearing portions  42   a  and a spindle  42   b  ( FIG. 6 ). The pair of bearing portions  42   a  are configured to be movable in the X-axis direction being a direction in which the bearing portions  42   a  come in contact with or separate from each other. The spindle  42   b  is inserted in an internal circumferential portion of a paper discharge roll R 1 . Both end portions of the spindle  42   b  are supported by the pair of bearing portions  42   a . The bearing portions  42   a  are supplied with a drive force from a drive source (not illustrated) as one example and can thus wind the paper discharge roll R 1  supported by the spindle  42   b , that is, the bearing portions  42   a  are configured to be applied with a front tension. 
     Similarly, the paper feeding unit  40  also includes a pair of bearing portions  40   a  movable in the X-axis direction and a spindle  40   b  ( FIG. 6 ). The spindle  40   b  is inserted in an internal circumferential portion of a paper feed roll R 2 . Both end portions of the spindle  40   b  are supported by the pair of bearing portions  40   a . The bearing portions  40   a  are supplied with a drive force from a drive source (not illustrated) as one example and can thus feed the paper feed roll R 2  supported by the spindle  40   b  downstream in the transport direction. Herein, the bearing portions  40   a  control drawing of the medium P in such a way that a back tension is applied to the medium P drawn from the paper feed roll R 2 . 
     As illustrated in  FIG. 6 , the medium P is configured to be drawn from the paper feed roll R 2  of the paper feeding unit  40  and wound around the paper discharge roll R 1  of the paper discharging unit  42  via the suction platen  36  and the drying unit  18  in the exemplary embodiment. 
     A transport roller  44  as a “transport mechanism” is provided upstream from the suction platen  36  in the transport direction of the medium P. The transport roller  44  is configured as a driving roller driven by a drive source, which is not illustrated. The transport roller  44  is configured to be rotatable in a normal rotation direction and a reverse rotation direction as one example. In the exemplary embodiment, the normal rotation direction is a direction in which the medium P wound around the paper feed roll R 2  is drawn and transported downstream in the medium transport direction, and the reverse rotation direction is a direction in which the medium P is transported upstream from downstream in the transport direction. 
     A discharge roller  46  as a “discharge mechanism” is provided downstream from the drying unit  18 . The discharge roller  46  is configured as a driving roller driven by a drive source, which is not illustrated. 
     The drying unit  18  includes a heater (not illustrated) as a heating source. The heater (not illustrated) applies heat to the medium P located in the drying unit  18 , evaporates water of the ink absorbed by the medium P, and accelerates drying. A suction fan  48  as a “medium suction mechanism” is provided in the drying unit  18 . The suction fan  48  extends along the transport path of the medium P in the drying unit  18 , and is attached to the lower surface side of a path formation member  18   a  constituting a part of the transport path. 
     In the exemplary embodiment, a plurality of through holes (not illustrated) are formed in the path formation member  18   a , and gas above the path formation member  18   a  is sucked via the through holes (not illustrated) when the suction fan  48  is driven. This forms a flow of the gas from above to below the path formation member  18   a  as indicated by arrows A 2  in  FIG. 8 . As a result, while the medium P (see the thick line provided with the reference sign P in  FIGS. 6 and 8 ) is located on the path formation member  18   a  of the drying unit  18 , the medium P is sucked by the path formation member  18   a  and pressed against an upper surface of the path formation member  18   a.    
     Note that, a controller  45  ( FIG. 1 ) is provided in the printer  10  in the exemplary embodiment. Note that, the position in which the controller  45  is provided in the main body unit  12  in  FIG. 1  is one example, and the controller  45  may be disposed in the main body unit  12  as appropriate. The controller  45  controls operations of the carriage  22 , the recording head  24 , the transport roller  44 , and the discharge roller  46 , operations of the suction fan  38  in the suction platen  36 , and operations of the heater and the suction fan  48  of the drying unit  18 . 
     With Regard to Transport Control of Medium P 
     Transport control of the medium P in the exemplary embodiment is described. When recording is executed on the medium P as illustrated in  FIG. 7 , the transport roller  44  is rotated and driven, the medium P is drawn from the paper feed roll R 2 , and the medium P is fed toward the suction platen  36  provided in the region facing the recording head  24 . The medium P on which recording is executed by the recording head  24  passes through the drying unit  18  and is wound into the paper discharge roll R 1  by the discharge roller  46 . 
     At this time, in the drying unit  18 , the heater (not illustrated) applies heat to the medium P passing through the drying unit  18  and accelerates drying of the medium P. The medium P passing through the drying unit  18  has absorbed a large amount of ink discharged from the recording head  24  and has swollen. The medium P shrinks and a dry wrinkle is generated due to the ink being dried rapidly. When transport of the medium P continues, a portion of the medium P in which the dry wrinkle is generated is successively fed downstream in the transport direction, and thus an influence of the dry wrinkle to the recording head  24  and the suction platen  36  can be reduced while the dry wrinkle does not grow toward the suction platen  36  side. 
     For a long continuous medium P in the longitudinal direction, such as a roll paper, transport of the medium P may be temporally stopped. For example, it is when the recording operation of one job is completed in the medium P, and the maintenance operation is executed in the recording head  24  before execution of a next job. Specifically, it is when clogging of the nozzles is ascertained after a nozzle check, when a loss of ink occurring in the nozzles during the recording operation is ascertained, or when the recording operation is executed for a predetermined period. Note that, the ascertaining operation may be executed by the controller  45  or a user. When these phenomena occur, the controller  45  temporarily stops the transport of the medium P, and moves the recording head  24  (carriage  22 ) from the home position or above the suction platen  36  toward the maintenance mechanism  28  located on the −X-axis direction side with respect to the suction platen  36 . 
     At this time, when the transport of the medium P stops, heating time for a part of the medium P, specifically, a portion heated in the drying unit  18  is increased further than that when the medium P is being transported. As a result, the dry wrinkle becomes larger because drying of the medium P proceeds more than a predetermined level and shrinking of the medium P proceeds. In this way, the dry wrinkle generated in the medium P grows upstream in the medium transport direction, that is, extends upstream in the transport direction. 
     As a result, the dry wrinkle of the medium P may reach the suction platen  36  in the medium transport direction. The dry wrinkle reaching the suction platen  36  cannot be pressed against the suction platen  36  even by a suction force of the suction fan  38 , and thus the medium P undulates along the X-axis direction on the suction platen  36 . In this state, when the carriage  22  crosses the suction platen  36 , the undulating portion of the medium P comes in contact with the recording head  24 , and thus rubs against the head. 
     In the printer  10  in the exemplary embodiment, a curved portion  50  ( FIG. 8 ) being curved upward as one example is formed in the medium P between the suction platen  36  and the drying unit  18  in the medium transport direction. By forming the curved portion  50  in the medium P between the suction platen  36  and the drying unit  18 , when a dry wrinkle generated in the drying unit  18  extends upstream in the transport direction and reaches the curved portion  50 , the dry wrinkle can be prevented from extending upstream from the curved portion  50  in the transport direction. 
     A method for forming the curved portion  50  during the execution of the maintenance operation of the recording head  24  will be described with reference to  FIG. 8  as appropriate along with the flow of the flowchart in  FIG. 9 . In Step S 1  ( FIG. 9 , also see  FIG. 9  for the following steps), the controller  45  temporarily stops the transport of the medium P. Next, in Step S 2 , the suction fan  48  of the drying unit  18  is driven, and a part of the medium P located in the drying unit  18  is sucked toward the path formation member  18   a  side as indicated by the arrows A 2  ( FIG. 8 ). In this way, the medium P located in the drying unit  18  is pressed against the path formation member  18   a , and restricted from moving in the medium transport direction. 
     Next, in Step S 3 , the transport roller  44  is rotated and driven in the normal rotation direction, and the medium P is fed downstream in the transport direction by a predetermined amount, while the medium P is sucked by driving the suction fan  48 . Herein, the predetermined amount in the exemplary embodiment is a width L 1  ( FIG. 8 ) of the suction platen  36  in the medium transport direction by which the medium P is fed as one example. Herein, since the portion of the medium P located in the drying unit  18  is restricted from moving in the transport direction, when the medium P is fed fom the suction platen  36 , the curved portion  50  is formed by curving the medium P upward before the drying unit  18 , namely, between the drying unit  18  and the suction platen  36 . In the exemplary embodiment, the medium P is fed downstream in the transport direction by a predetermined amount (width L 1 ), and the curved portion  50  is formed, so that the curved portion  50  having a sufficient size for preventing a dry wrinkle from extending upstream in the transport direction can be formed. 
     In Step S 4 , the controller  45  drives the suction fan  38  of the suction platen  36 , and a portion of the medium P facing the suction platen  36  is sucked toward the suction platen  36  (arrows A 1  in  FIG. 8 ) after the Step S 3 . In this way, the portion of the medium P facing the suction platen  36  is also restricted from moving in the medium transport direction, and thus the curved portion  50  can maintain its shape. Note that, the controller  45  starts driving of the suction fan  38 , and, at the same time, stops rotation and driving of the transport roller  44  as one example. 
     Next, the carriage  22  (the recording head  24 ) is caused to move from the +X direction side toward the −X direction side and cross above the suction platen  36  as in Step S 5 . In this state, the portion of the medium P facing the suction platen  36  is prevented from growing a dry wrinkle by the curved portion  50  and is also sucked to the upper surface of the suction platen  36 , and is thus pressed against the upper surface of the suction platen  36 . In this way, when the carriage  22  crosses above the suction platen  36 , contact between the recording head  24  and the portion of the medium P facing the suction platen  36  can be suppressed. 
     As in Step S 6 , the controller  45  operates the maintenance mechanism  28  (the flushing receiving portion  30 , the waste liquid receiving portion  32 , and the wiper  34 ), and executes the maintenance operation on the recording head  24  after the Step S 5 . As in Step S 7 , after the execution of the maintenance operation, the carriage  22  (the recording head  24 ) is caused to move to the +X direction side, for example, the home position and the like. 
     The controller  45  starts to eliminate the curved portion  50  during Step S 8  and Step S 9 . As in the Step S 8 , driving of the suction fan  38  of the suction platen  36  and the suction fan  48  of the drying unit  18  is stopped. This releases the restriction of the movement in the medium transport direction of the portion of the medium P in the drying unit  18  and the portion of the medium P facing the suction platen  36  that have been restricted from moving in the transport direction. 
     In Step S 9 , the discharge roller  46  is rotated in the direction in which the medium P is fed downstream in the transport direction, and the medium P is fed downstream in the transport direction by the width L 1  ( FIG. 8 ) of the suction platen  36  in the medium transport direction. Thus, the curved portion  50  formed between the suction platen  36  and the drying unit  18  is eliminated. 
     Contact between the medium P on the suction platen  36  and the recording head  24  can be suppressed by forming the curved portion  50 . Thus, smudging of the portion of the medium P facing the suction platen  36  due to contact with the recording head  24  can be suppressed. As a result, the recording operation can restart from the portion of the medium P facing the suction platen  36  only by eliminating the curved portion  50  from the long medium P. Thus, a portion of the medium P without execution of recording between the portion on which recording has already been executed (the portion located in the drying unit  18 ) and a portion on which recording is to be newly executed can be reduced in length, so that waste paper in the medium P can be reduced. 
     In the exemplary embodiment, an influence of a dry wrinkle generated in the portion of the medium P located in the drying unit  18  on the suction platen  36  can be suppressed by forming the curved portion  50  in the medium P between the suction platen  36  and the drying unit  18 . As a result, contact between the recording head  24  crossing above the suction platen  36  and the portion of the medium P facing the suction platen  36  can be suppressed, and occurrence of rubbing by the head can be suppressed. 
     Modification of Exemplary Embodiment 
     In the exemplary embodiment, the medium P is fed by the width L 1  of the suction platen  36  in the medium transport direction as a predetermined amount in order to form the curved portion  50  of the medium P. Instead of this configuration, for example, the medium P may be fed by a half-length of the width L 1  of the suction platen  36 . The predetermined amount may be a feeding amount needed to form the curved portion  50  having the size for preventing growth of a dry wrinkle between the suction platen  36  and the drying unit  18 . Further, the predetermined amount may be set according to a kind of a medium. 
     In the exemplary embodiment, in Step S 9  in  FIG. 9 , the controller  45  controls the discharge roller  46  to feed the medium P is fed downstream in the transport direction by L 1  for eliminating the curved portion  50 . Instead of this configuration, the curved portion  50  may be eliminated by winding the medium P upstream in the transport direction by L 1  by rotating the transport roller  44  in the reverse rotation direction, after sucing by the suction platen has been stopped. With such a configuration, a distance between portions of the medium P on which recording are executed can be shortened, and a waste paper portion of the medium P can be reduced. 
     The medium P in the exemplary embodiment is roll paper as one example. Instead of this configuration, the medium P may be a cut sheet. 
     In the exemplary embodiment, the home position is provided on the +X-axis direction side, and the maintenance mechanism  28  is provided on the −X-axis direction side. Instead of this configuration, the home position may be provided on the −X-axis direction side, and the maintenance mechanism  28  may be provided on the +X-axis direction side. 
     In the exemplary embodiment, the curved portion  50  is formed in the medium P during the execution of the maintenance operation of the recording head  24 . In addition to this configuration, the curved portion  50  may also be formed during the execution of the recording operation of the recording head  24 . In this configuration, the curved portion  50  can be formed in the medium P by adjusting at least one of a feeding speed of the transport roller  44  and the discharge roller  46 . Specifically, the curved portion  50  can be formed by, for example, increasing a feeding speed of the transport roller  44  more than a feeding speed of the discharge roller  46 . Furthermore, the size of the curved portion  50  to be formed can be adjusted as appropriate by adjusting a feeding speed of the transport roller  44  and the discharge roller  46 . As a result, the curved portion  50  having the appropriate size according to a kind of the medium P is formed, and thus growth of a dry wrinkle extending from the drying unit  18  (a dry wrinkle extending upstream in the transport direction) can be more reliably prevented by the curved portion  50 . 
     In the exemplary embodiment, as one example, the curved portion  50  is formed as follows. While the suction fan  48  of the drying unit  18  is driven and the medium P located in the drying unit  18  is pressed against the path formation member  18   a , the transport roller  44  is rotated and driven in the normal rotation direction, and the medium P is fed downstream in the transport direction by a predetermined amount. Subsequently, the suction fan  38  of the suction platen  36  is driven, and a portion of the medium P facing the suction platen  36  is sucked toward the suction platen  36 . Instead of this configuration, the curved portion  50  may be formed as follows. While the medium P is sucked to the suction platen  36  to a degree that movement of the medium P in the transport direction is not completely restricted by the suction platen  36 , the suction fan  48  of the drying unit  18  is driven, and the medium P located in the drying unit  18  is pressed against the path formation member  18   a . Then, the transport roller  44  is rotated and driven in the normal rotation direction, and the medium P is fed downstream in the transport direction by a predetermined amount. 
     Further, the method for forming the curved portion  50  is applied to an ink jet printer as one example of a recording device in the exemplary embodiment, but is also applicable to other general liquid injection devices. 
     Herein, the liquid injection device is not limited to recording devices such as printers, copying machines, and facsimile machines that use an ink jet-type recording head, discharge ink from the recording head, and perform recording on a recorded medium. The liquid injection device includes a device that injects liquid for use of ink instead of the ink to an injected medium corresponding to a recorded medium from a liquid injection head corresponding to the ink jet-type recording head, and allows the liquid to adhere to the injected medium. 
     Examples of the liquid injection head include, in addition to the recording head, a color material injection head used for manufacturing a color filter of a liquid crystal display and the like, an electrode material (conductive paste) injection head used for forming an electrode of an organic EL display, a surface emitting display (FED), and the like, a biometric organic matter injection head used for manufacturing a biochip, and a sample injection head as a precision pipet. 
     Note that the invention is not intended to be limited to the aforementioned examples, and many variations are possible within the scope of the invention as described in the appended claims. It goes without saying that such variations also fall within the scope of the invention. 
     This application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2018-055765, filed Mar. 23 2018. The entire disclosure of Japanese Patent Application No. 2018-055765 is hereby incorporated herein by reference.