Patent Publication Number: US-10780702-B2

Title: Liquid ejecting head unit, liquid ejecting apparatus, and maintenance method for liquid ejecting apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 15/905,900, filed Feb. 27, 2018, which claims priority to Japanese Patent Application No. 2017-034465, filed Feb. 27, 2017, the entire disclosures of which are expressly incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Technical Field 
     The invention relates to a liquid ejecting apparatus such as an ink jet printer, a liquid ejecting head unit provided in the liquid ejecting apparatus and a maintenance method for the liquid ejecting apparatus. 
     2. Related Art 
     In general, ink jet printers, which eject ink from nozzles of a liquid ejecting head onto a medium such as a paper sheet to perform printing, are widely known as one type of liquid ejecting apparatus. Among such printers are those equipped with a moisture retention cap device that moisturizes the interior of the nozzles by covering the nozzles of the liquid ejecting head with a cap portion so that ink in the nozzles does not thicken or solidify (refer to, for example, JP-A-2012-206516). 
     In a printer such as that described above, because the moisture retention cap device is disposed in a non-printing area where printing is not performed, which is next to a printing area where printing is performed, there is a problem that it is not possible to moisturize the inside of the nozzles and the periphery of the nozzles when the liquid ejecting head is positioned in the printing area. 
     The invention has been made focusing on such problems existing in the related art. 
     SUMMARY 
     An advantage of some aspects of the invention is that a liquid ejecting head unit and a liquid ejecting apparatus capable of moisturizing the inside of nozzles and the periphery of nozzles regardless of the position of the liquid ejecting head are provided. 
     Advantageous effects will be described below. 
     A liquid ejecting head unit according to an aspect of the invention includes a liquid ejecting head having a nozzle forming portion in which a nozzle that ejects a liquid to a medium is formed, a shutter that has an opening portion exposing the nozzle and that is movable between a cover position in which a recessed portion including the nozzle is covered and an exposure position in which the nozzle is exposed, and a first communication portion that communicates with an inside of the recessed portion and that is capable of supplying a fluid into the recessed portion. 
     According to this configuration, by supplying the maintenance liquid from the first communication portion into the recessed portion with the shutter moved to the cover position, the inside of the recessed portion can be humidified. Consequently, regardless of the position of the liquid ejecting head, it is possible to moisturize the inside of the nozzle and the periphery of the nozzle (inside the recessed portion). 
     It is preferable that the liquid ejecting head unit include a recessed portion forming member that is disposed between the nozzle forming portion and the shutter, that has a side wall surrounding the nozzle, and that forms the recessed portion together with a nozzle opening surface, at which the nozzle in the nozzle forming portion opens, and that the shutter move in a direction along the nozzle opening surface. 
     According to this configuration, a recessed portion can be easily formed. 
     In the liquid ejecting head unit, it is preferable that the recessed portion forming member be formed of a porous member. 
     According to this configuration, because the maintenance liquid can be held by the recessed portion forming member, the inside of the nozzle and the inside of the recessed portion can be effectively moisturized. 
     It is preferable that the liquid ejecting head unit include a second communication portion that communicates with the inside of the recessed portion and that is capable of recovering the fluid inside the recessed portion. 
     According to this configuration, fluid in the recessed portion can be recovered from the second communication portion. 
     A liquid ejecting apparatus according to another aspect of the invention includes a liquid ejecting head unit including a liquid ejecting head that ejects a liquid from a nozzle formed in a nozzle forming portion to a medium by driving an actuator and including a shutter that has an opening portion exposing the nozzle and that is movable between a cover position in which a recessed portion including the nozzle is covered and an exposure position in which the nozzle is exposed, and a maintenance liquid storage unit that is connected to a maintenance liquid supply port capable of supplying a maintenance liquid to the recessed portion and that stores the maintenance liquid. When the shutter is in the cover position, the maintenance liquid supply port and the maintenance liquid storage unit communicate with each other. 
     According to this configuration, because the inside of the recessed portion is humidified by the maintenance liquid of the maintenance liquid storage unit, it is possible to moisturize the inside of the nozzle and the periphery of the nozzle (inside the recessed portion) regardless of the position of the liquid ejecting head. 
     It is preferable that, when the shutter is in the cover position, the liquid ejecting apparatus supply the maintenance liquid from the maintenance liquid supply port into the recessed portion. 
     According to this configuration, because the inside of the recessed portion is humidified with the maintenance liquid, the inside of the nozzle and the inside of the recessed portion can be moisturized. Therefore, it is possible to suppress drying of the liquid attached to the inside of the recessed portion and to make it easy to recover the liquid. 
     It is preferable that, when the shutter is in the cover position, the liquid ejecting apparatus drive the actuator of the liquid ejecting head in a state where the maintenance liquid fills an inside of the recessed portion so as to be in contact with the nozzle. 
     According to this configuration, it is easy to discharge thickened liquid inside the nozzle. 
     It is preferable that, when the shutter is in the cover position, the liquid ejecting apparatus drive the actuator to eject the liquid from the nozzle toward an inner surface of the shutter. 
     According to this configuration, when the shutter is in the cover position, because flushing can be performed by ejecting liquid from the nozzle in order to eliminate thickening of the liquid inside the nozzle, maintenance of the liquid ejecting head by flushing can be performed even when, for example, the liquid ejecting head is at a position facing the medium. 
     It is preferable that the liquid ejecting apparatus include a recovery port capable of sucking fluid inside the recessed portion. 
     According to this configuration, for example, even when the liquid ejecting head is at a position facing the medium, it is possible to recover fluid used for maintenance of the periphery of the nozzle. 
     It is preferable that, when the shutter is in the cover position, the liquid ejecting apparatus suck and recover the fluid inside the recessed portion from the recovery port. 
     According to this configuration, because the inside of the recessed portion is sucked from the recovery port when the recessed portion is covered with the shutter, it is possible to efficiently recover fluid used for maintenance of the periphery of the nozzle. 
     It is preferable that, in the liquid ejecting apparatus, the recovery port and the inside of the recessed portion be at least partially in communication with each other via a communication path formed by the inner surface of the shutter, and when the shutter is in the exposure position, a suction operation be performed from the recovery port. 
     According to this configuration, when liquid is being ejected from the nozzle of the liquid ejecting head to the medium after flushing has been performed with the shutter moved to the cover position, it is possible to recover the liquid on the inner surface of the shutter while ejecting the liquid from the nozzle of the liquid ejecting head to the medium with the shutter moved to the exposure position. Consequently, it is possible to prevent interruption of the operation of ejecting the liquid from the nozzle of the liquid ejecting head to the medium by the recovery operation of recovering the liquid flushed on the inner surface of the shutter. 
     It is preferable that the liquid ejecting apparatus include a wiper that is disposed so as to be capable of coming into contact with at least the shutter, and, when the shutter is in the exposure position, the wiper and the shutter be moved relative to each other along an outer surface of the shutter with the wiper in contact with the shutter. 
     According to this configuration, at least liquid attached to the outer surface of the shutter can be wiped off by the wiper. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a schematic side view of a liquid ejecting apparatus according to an embodiment. 
         FIG. 2  is a schematic view illustrating a state when capping of a liquid ejecting head unit of a liquid ejecting apparatus in  FIG. 1  is performed. 
         FIG. 3  is a schematic bottom view of a liquid ejecting head unit when a shutter is in an exposure position. 
         FIG. 4  is a cross-sectional view taken along the line IV-IV in  FIG. 3 . 
         FIG. 5  is a cross-sectional view taken along the line V-V in  FIG. 3 . 
         FIG. 6  is a view illustrating a state when the shutter has moved to the cover position in  FIG. 5 . 
         FIG. 7  is a schematic cross-sectional view illustrating an operation of a liquid ejecting head unit of a modification example. 
         FIG. 8  is a schematic cross-sectional view of a liquid ejecting head unit of a modification example. 
         FIG. 9  is a schematic cross-sectional view illustrating an operation of a liquid ejecting head unit of a modification example. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, an embodiment of a liquid ejecting apparatus will be described with reference to the drawings. 
     Further, in the drawings other than  FIG. 3 , the vertical direction of the page corresponds to the vertical direction (direction of gravity), and the lower side in the vertical direction is the lower side of the page. 
     As illustrated in  FIG. 1 , a liquid ejecting apparatus  11  of this embodiment is constituted by an ink jet type printer that performs printing by ejecting ink as an example of a liquid onto a medium S such as a sheet of paper. The liquid ejecting apparatus  11  includes a liquid ejecting head unit  12  that ejects ink to the medium S, a fluid supply mechanism  13  capable of supplying a fluid such as a liquid or a gas different from ink to the liquid ejecting head unit  12 , a recovery mechanism  14  that recovers a fluid from the liquid ejecting head unit  12 , and a maintenance mechanism  15  that performs maintenance of the liquid ejecting head unit  12 . 
     Further, in the liquid ejecting apparatus  11  of this embodiment, the liquid ejecting head unit  12  prints on the medium S disposed in the printing area PA that extends in the scanning direction which is a direction orthogonal to the paper surface in  FIGS. 1 and 2  by ejecting ink while reciprocating in the scanning direction in a state where the liquid ejecting head unit  12  faces the printing area PA. 
     As illustrated in  FIGS. 1 and 4 , the liquid ejecting head unit  12  includes a liquid ejecting head  18  having a nozzle forming portion  17  in which a plurality of nozzles  16  for ejecting ink to the medium S are formed, and a recessed portion forming member  21  that, together with a nozzle opening surface  19  at which the nozzles  16  of the nozzle forming portion  17  open, forms recessed portions  20  and a shutter  22  arranged so as to cover the recessed portion forming member  21 . Therefore, the recessed portion forming member  21  is arranged between the nozzle forming portion  17  and the shutter  22 . 
     The nozzle forming portion  17  in which the plurality of the nozzles  16  are formed is disposed at the end portion of the liquid ejecting head  18  on the printing area PA side. The nozzle forming portion  17  may be integrally formed with the liquid ejecting head  18  or may be formed separately from the liquid ejecting head  18 . In the case where the nozzle forming portion  17  is formed separately from the liquid ejecting head  18 , it is preferable that the recessed portion forming member  21  be configured to function as a fixing member that fixes the nozzle forming portion  17  to the liquid ejecting head  18 . 
     Actuators  23  such as piezoelectric elements are each disposed in a corresponding one of the nozzles  16  formed in the nozzle forming portion  17  of the liquid ejecting head  18 . The liquid ejecting head  18  ejects ink from each of the nozzles  16  to the medium S by driving a corresponding one of the actuators  23 . 
       FIG. 3  illustrates, as an example, a state in which nozzle rows  24  are formed by disposing the plurality of the nozzles  16  side by side in a direction (a nozzle row direction which is a left and right direction in  FIG. 3 ) that intersects the scanning direction (vertical direction in  FIG. 3 ) on the nozzle opening surface  19  of the liquid ejecting head  18  that faces the printing area PA where the medium S is disposed. 
     In this case, a plurality of the nozzle rows  24  are formed by a plurality of the nozzles  16 , and the plurality of the nozzle rows  24  are arranged in the scanning direction so as to be parallel to each other. The plurality of the nozzles  16  may, for each of the nozzle rows  24 , for example, eject different kinds of liquids such as inks of different colors or may eject liquids of the same type such as inks of the same color. 
     As illustrated in  FIGS. 3 and 4 , the recessed portion forming member  21  has a rectangular plate shape and is liquid-tightly fixed to the nozzle opening surface  19  of the nozzle forming portion  17  with an adhesive or the like. The recessed portion forming member  21  has through holes  25  each of which extends along a corresponding one of the nozzle rows  24  at a position corresponding to the nozzle row  24 . 
     The inner peripheral surface of each of the through holes  25  constitutes a side wall  26  surrounding a corresponding one of the nozzle rows  24  (the area of the nozzle opening surface  19 , which includes the openings of the nozzles  16  forming the nozzle row  24 , inside the through hole  25 ). That is, the recessed portion forming member  21  has the side walls  26  surrounding corresponding ones of the nozzle rows  24 . The side walls  26  are also the side walls of corresponding ones of the recessed portions  20 . Therefore, the area of the nozzle opening surface  19  inside each of the side walls  26  constitutes the bottom surface of the recessed portion  20 . 
     The shutter  22  has a bottomed rectangular box shape having an opening, and an inner bottom surface  27  (inner surface) thereof is disposed so as to be slidable along an outer surface  28  of the recessed portion forming member  21 . In this case, the gap between the inner bottom surface  27  of the shutter  22  and the outer surface  28  of the recessed portion forming member  21  is set to a value (for example, 10 micrometers or less) smaller than the diameter of the nozzles  16 , and is sealed by the meniscus of the maintenance liquid. 
     As illustrated in  FIGS. 5 and 6 , the shutter  22  is moved in a direction along the nozzle opening surface  19  by a mobile mechanism (not illustrated). In this embodiment, the shutter  22  is configured to be movable in a scanning direction (left and right direction in  FIGS. 5 and 6 ) that intersects with the nozzle row direction. That is, the shutter  22  has opening portions  29  through which corresponding ones of the nozzle rows  24  are exposed, and is movable between a cover position (the position illustrated in  FIG. 6 ) in which each of the recessed portions  20  including a corresponding one of the nozzle rows  24  is covered and an exposure position (position illustrated in  FIG. 5 ) in which each of the recessed portions  20  including a corresponding one of the nozzle rows  24  is exposed. 
     Next, the configuration of the fluid supply mechanism  13  will be described in detail. 
     As illustrated in  FIGS. 1 and 4 , the fluid supply mechanism  13  includes a maintenance liquid storage unit  30  for storing a maintenance liquid, which is a liquid different from ink, and supply pipes  32  that connect the maintenance liquid storage unit  30  to maintenance liquid supply ports  31  capable of supplying the maintenance liquid to the recessed portions  20 , respectively. 
     The maintenance liquid supply ports  31  open at the nozzle opening surface  19  of the liquid ejecting head  18  and communicate with the inside of the recessed portions  20 , respectively. In this embodiment, a first communication portion capable of supplying a fluid (for example, a maintenance liquid, vapor of a maintenance liquid, or the like) into the recessed portions  20  is constituted by the maintenance liquid supply port  31 . 
     Therefore, the first communication portion is included in the liquid ejecting head unit  12 . 
     The end portion of the supply pipes  32  on the maintenance liquid storage unit  30  side is disposed inside the maintenance liquid stored in the maintenance liquid storage unit  30 . It is preferable that the maintenance liquid stored in the maintenance liquid storage unit  30  be a liquid containing a solvent component of ink ejected from the liquid ejecting head  18 . For example, in the case where the solvent component of ink is water, a liquid containing water (which may contain an additive such as a preservative) as a main component or water is stored in the maintenance liquid storage unit  30 . 
     The fluid supply mechanism  13  further includes a liquid storage unit  34  that is connected to the maintenance liquid storage unit  30  via a connection pipe  33 , a supply pump  35  that is provided in the connection pipe  33 , a valve  36  that is disposed between the supply pump  35  in the connection pipe  33  and the liquid storage unit  34  and a detection unit  37  that detects the position of the liquid surface of the maintenance liquid inside the maintenance liquid storage unit  30 . 
     In this case, when the detection unit  37  detects that the liquid surface position inside the maintenance liquid storage unit  30  is lower than a predetermined position, by driving the supply pump  35  with the valve  36  open, it is possible to replenish the maintenance liquid from the liquid storage unit  34 , which stores the maintenance liquid, to the maintenance liquid storage unit  30 . 
     Further, in the liquid ejecting apparatus  11 , a configuration may be adopted in which the fluid supply mechanism  13  does not include the liquid storage unit  34 , the connection pipe  33 , the supply pump  35 , the valve  36 , and the detection unit  37 , and the maintenance liquid is directly replenished into the maintenance liquid storage unit  30  or the maintenance liquid is replenished by replacing the maintenance liquid storage unit  30  which is in a cartridge form. 
     The supply pipes  32  are provided with an atmospheric release valve  38  for opening the inside of the supply pipes  32  to the atmosphere and an opening and closing valve  39  for opening and closing a flow path inside the supply pipes  32 . The opening and closing valve  39  is disposed at a position closer to the liquid ejecting head  18  than the atmospheric release valve  38  in the supply pipes  32 . Then, when the shutter  22  is in the cover position and when the atmospheric release valve  38  is closed and the opening and closing valve  39  is opened, the maintenance liquid supply ports  31  and the maintenance liquid storage unit  30  communicate with each other. 
     Then, a humidified gas such as air containing the vapor of the maintenance liquid inside the maintenance liquid storage unit  30  is supplied into the recessed portions  20  from the maintenance liquid supply ports  31  via the supply pipes  32 , and the inside of the recessed portions  20  is consequently humidified. On the other hand, when the atmospheric release valve  38  is opened, humidified gas such as air containing vapor of the maintenance liquid inside the maintenance liquid storage unit  30  is released from the atmospheric release valve  38  into the atmosphere. Therefore, even if the opening and closing valve  39  is not closed, almost no humidified gas is supplied into the recessed portions  20 . 
     Next, the configuration of the recovery mechanism  14  will be described in detail. 
     As illustrated in  FIGS. 1 and 4 , the recovery mechanism  14  includes a waste liquid tank  40 , recovery pipes  42  that connect recovery ports  41 , through which the fluid in the recessed portions  20  can be sucked, and the waste liquid tank  40  respectively to each other, and a recovery pump  43  provided in the recovery pipes  42 . By driving the recovery pump  43 , the recovery pump  43  sucks the fluid inside the recovery pipes  42  from the recessed portions  20  toward the waste liquid tank  40 . 
     The recovery ports  41  open at the nozzle opening surface  19  of the liquid ejecting head  18  and communicate with the inside of the recessed portions  20 , respectively. In this embodiment, a second communication portion capable of recovering the fluid (maintenance liquid, ink, air, or the like) inside the recessed portions  20  is constituted by the recovery port  41 . Therefore, the second communication portion is provided in the liquid ejecting head unit  12 . 
     As illustrated in  FIGS. 3 and 4 , the recovery ports  41  are positioned on the side of the nozzle rows  24  opposite to the maintenance liquid supply port  31 . In other words, the recovery ports  41  open at an end portion (right end portion in  FIG. 3 ) of the recessed portions  20  in the nozzle row direction (right and left direction in  FIG. 3 ) and the maintenance liquid supply ports  31  open at the other end portion (left end portion in  FIG. 3 ) of the recessed portions  20  in the nozzle row direction. 
     The recovery ports  41  and the inside of the recessed portions  20  (the area surrounded by a two-dot chain line in  FIG. 3  in the embodiment) respectively communicate with each other via first communication paths  44  formed by the inner bottom surface  27  of the shutter  22 . The maintenance liquid supply ports  31  and the inside of the recessed portions  20  (the area surrounded by the two-dot chain line in  FIG. 3  in the embodiment) respectively communicate with each other via second communication paths  45  formed by the inner bottom surface  27  of the shutter  22 . The width of the first communication paths  44  in the scanning direction (vertical direction in  FIG. 3 ) is narrower than the width of the second communication paths  45  in the scanning direction. Therefore, the capillary force of the second communication paths  45  is smaller than the capillary force of the first communication paths  44 . 
     That is, the first communication paths  44  are formed in a narrow groove shape so that unnecessary maintenance liquid and ink remaining inside the recessed portions  20  can be easily drawn into the recovery ports  41 . On the other hand, the second communication paths  45  are formed in a shape in which the width in the scanning direction is markedly wider than that of the first communication paths  44 . That is, by ensuring a large space around the maintenance liquid supply ports  31  inside the recessed portions  20 , it is easy to supply the maintenance liquid from the maintenance liquid supply ports  31  into the recessed portions  20 , respectively. Further, in order to effectively humidify the inside of the recessed portions  20 , an absorbent material that absorbs and holds the maintenance liquid may be disposed in the second communication passages  45  as necessary. 
     Next, the configuration of the maintenance mechanism  15  will be described in detail. 
     As illustrated in  FIGS. 1 and 2 , the maintenance mechanism  15  includes a wiping mechanism  46  that is disposed in a non-printing area located at a position deviated from the printing area PA in the scanning direction and that wipes the liquid ejecting head unit  12 , and a capping mechanism  47  that suppresses clogging of the nozzles  16 . 
     The capping mechanism  47  includes a cap portion  48 , which is relatively movable with respect to the liquid ejecting head unit  12 , a waste liquid storage unit  49 , a waste liquid flow path  50  that connects the cap portion  48  and the waste liquid storage unit  49  to each other, a pressure reducing mechanism  51  provided in the waste liquid flow path  50 , and an atmospheric release valve  52  attached to the cap portion  48 . The pressure reducing mechanism  51  is constituted by, for example, a tube pump. 
     As illustrated in  FIG. 2 , the cap portion  48  having a bottomed box shape with an opening moves in a direction approaching the liquid ejecting head unit  12 , and performs capping so as to form the closed space R by covering the nozzle opening surface  19  through the recessed portion forming member  21  and the shutter  22 . The cap portion  48  is not limited to a bottomed box shape with an opening as illustrated in  FIG. 2 ; for example, an annular elastic member surrounding an area to which each of the nozzles  16  opens may be disposed on the liquid ejecting head unit  12  side and a flat plate member which forms the closed space R by making contact with this elastic member may be used as the cap portion  48 . 
     When the liquid ejecting head unit  12  is capped by the cap portion  48 , the closed space R is opened to the atmosphere when the atmospheric release valve  52  is opened, whereas when the atmospheric release valve  52  is closed, the closed space R is substantially sealed. Therefore, after the liquid ejecting head unit  12  is capped with the shutter  22  in the exposure position, when the atmospheric release valve  52  and the opening and closing valve  39  are closed and the pressure reducing mechanism  51  is driven, the closed space R is depressurized and a negative pressure is generated and suction cleaning is performed such that bubbles and the like mixed inside the liquid ejecting head  18  are discharged together with the ink through each of the nozzles  16 . The ink (waste liquid) discharged from each of the nozzles  16  into the cap portion  48  by suction cleaning is recovered in the waste liquid storage unit  49  through the waste liquid flow path  50 . 
     As illustrated in  FIG. 1 , the wiping mechanism  46  includes a wiper  53  disposed so as to be capable of coming into contact with at least the shutter  22 , and a mobile body  54  that moves while holding the wiper  53 . By the wiper  53 , for example, after execution of suction cleaning, moving along the outer surface of the shutter  22  in the exposure position while in contact with the shutter  22  in accordance with the movement of the mobile body  54 , wiping is performed to wipe off ink and the like attached to the outer surface of the shutter  22  and the inside of the recessed portions  20  including the nozzle opening surface  19 . 
     Further, the wiping by the wiper  53  may be performed by moving the liquid ejecting head unit  12  in a state where the wiper  53  is stopped or by moving both the wiper  53  and the liquid ejecting head unit  12 . That is, wiping by the wiper  53  may be performed by moving the wiper  53  and the liquid ejecting head unit  12  relative to each other. 
     Next, the operation of the liquid ejecting apparatus  11  will be described. 
     During printing of the medium S, while the liquid ejecting head unit  12  with the shutter  22  in the exposure position is reciprocating in the scanning direction while facing the printing area PA, ink is ejected from each of the nozzles  16  to the medium S disposed in the printing area PA. At this time, when the atmospheric release valve  38  is closed while the shutter  22  is moved from the exposure position to the cover position and the opening and closing valve  39  is open, the maintenance liquid supply port  31  and the maintenance liquid storage unit  30  communicate with each other. 
     Then, a humidified gas such as air containing the vapor of the maintenance liquid inside the maintenance liquid storage unit  30  is supplied into the recessed portions  20  from the maintenance liquid supply ports  31  via the supply pipes  32  and the inside of the recessed portions  20  is consequently humidified. Consequently, the inside of each of the nozzles  16  and the periphery of each of the nozzles  16  are moisturized, and drying of ink inside each of the nozzles  16  and ink attached to the inside of the recessed portions  20  is suppressed. 
     Furthermore, at this time, when the recovery pump  43  is driven, the inside of the recessed portions  20  is sucked by the recovery pump  43  and depressurized. Consequently, a negative pressure is generated in the recessed portions  20 , and the maintenance liquid inside the maintenance liquid storage unit  30  is supplied from the maintenance liquid supply ports  31  into the recessed portions  20  via the supply pipes  32  by this negative pressure. Consequently, the inside of each of the nozzles  16  and the periphery of each of the nozzles  16  are effectively moisturized. In this case, it is preferable that the negative pressure generated inside the recessed portions  20  be a negative pressure lower than the meniscus resistance pressure of the meniscus seal between the shutter  22  and the recessed portion forming member  21 . 
     Further, in the case where the maintenance liquid inside the maintenance liquid storage unit  30  is supplied from the maintenance liquid supply ports  31  into the recessed portions  20 , after opening the recovery ports  41  to the atmosphere, by driving the supply pump  35  to pressurize the inside of the maintenance liquid storage unit  30  and by separately driving a feed pump provided on the supply pipes  32 , the maintenance liquid may be pressurized and supplied into the recessed portions  20  at a positive pressure lower than the meniscus resistance pressure of the meniscus seal between the shutter  22  and the recessed portion forming member  21 . 
     In this way, in the liquid ejecting apparatus  11  of this embodiment, it is possible to moisturize the inside of the nozzles  16  and the periphery of the nozzles  16  without using the maintenance mechanism  15 . That is, in the liquid ejecting apparatus  11  of this embodiment, the inside of the nozzles  16  and the periphery of the nozzles  16  can be moisturized irrespective of the position of the liquid ejecting head unit  12  (the liquid ejecting head  18 ). In other words, as described above, in the liquid ejecting apparatus  11  of this embodiment, even in the case where the liquid ejecting head unit  12  is at a position facing the printing area PA, the inside of the nozzles  16  and the periphery of the nozzles  16  can be moisturized. 
     In addition, irrespective of printing performed from each of the nozzles  16  of the liquid ejecting head unit  12 , flushing for ejecting ink for the purpose of eliminating thickening of ink in each of the nozzles  16  is performed at a position where the liquid ejecting head unit  12  faces the medium S (printing area PA) during printing. This flushing is carried out by driving each of the actuators  23  with the shutter  22  moved to the cover position and ejecting ink from each of the nozzles  16  toward the inner bottom surface  27  of the shutter  22 . 
     Thereafter, when the recovery pump  43  is driven with the shutter  22  moved to the exposure position, because the opening portions  29  of the shutter  22  are narrower than the through holes  25  of the recessed portion forming member  21  in the movement direction of the shutter  22 , the flushing ink attached to the inner bottom surface  27  of the shutter  22  is sucked from the recovery ports  41  and recovered in the waste liquid tank  40 . At this time, because the shutter  22  is in the exposure position, it is possible to perform ejection of ink to the medium S from each of the nozzles  16 . That is, the suction operation of sucking the flushing ink from the recovery ports  41  driven by the recovery pump  43  is performed without interrupting printing of the medium S. 
     In addition, regardless of the position of the liquid ejecting head unit  12 , when the atmospheric release valve  38  and the opening and closing valve  39  are opened at an appropriate timing and the recovery pump  43  is driven with the shutter  22  in the cover position, ink attached to the inside of the recessed portions  20  (the periphery of the nozzles  16  and the like) and the maintenance liquid are sucked from the recovery ports  41  together with air and recovered in the waste liquid tank  40 . In this case, in the case where the opening and closing valve  39  is closed, it is preferable that the inside of the recessed portions  20  be sucked by the recovery pump  43  so that the negative pressure generated in the recessed portions  20  becomes a negative pressure higher than the meniscus resistance pressure of the meniscus seal between the shutter  22  and the recessed portion forming member  21 . 
     According to the embodiment described above, the following effects can be obtained. 
     (1) The liquid ejecting head unit  12  includes the maintenance liquid supply ports  31  that communicate with the inside of the recessed portions  20  and that are capable of supplying a fluid into the recessed portions  20 . Consequently, by supplying the maintenance liquid from the maintenance liquid supply ports  31  into the recessed portions  20  with the shutter  22  moved to the cover position, the inside of the recessed portions  20  can be humidified. Therefore, the inside of the nozzles  16  and the periphery of the nozzles  16  (inside the recessed portions  20 ) can be moisturized regardless of the position of the liquid ejecting head  18 . 
     (2) The liquid ejecting head unit  12  includes the recessed portion forming member  21  that forms the recessed portions  20  together with the nozzle opening surface  19 . Consequently, the recessed portions  20  can be easily formed. 
     (3) The liquid ejecting head unit  12  includes the recovery ports  41  that communicate with the inside of the recessed portions  20  and that are capable of recovering the fluid inside the recessed portions  20 . Consequently, unnecessary fluid such as unnecessary ink and maintenance liquid inside the recessed portions  20  can be recovered from the recovery ports  41 . 
     (4) When the shutter  22  is in the cover position, the liquid ejecting apparatus  11  causes the maintenance liquid supply ports  31  and the maintenance liquid storage unit  30  to communicate with each other. Therefore, because the inside of the recessed portions  20  is humidified by the maintenance liquid of the maintenance liquid storage unit  30 , it is possible to moisturize the inside of the nozzles  16  and the periphery of the nozzles  16  (inside the recessed portions  20 ) regardless of the position of the liquid ejecting head  18  (the liquid ejecting head unit  12 ). 
     (5) When the shutter  22  is in the cover position, the liquid ejecting apparatus  11  supplies the maintenance liquid from the maintenance liquid supply ports  31  into the recessed portions  20 . Consequently, because the inside of the recessed portions  20  is humidified with the maintenance liquid, it is possible to moisturize the inside of the nozzles  16  and the inside of the recessed portions  20 . Therefore, it is possible to suppress the drying of ink attached to the inside of the recessed portions  20  and to make it easy to recover the ink from the recovery ports  41 . 
     (6) When the shutter  22  is in the cover position, the liquid ejecting apparatus  11  drives the actuators  23  and ejects ink from the nozzles  16  toward the inner bottom surface  27  of the shutter  22 . Therefore, when the shutter  22  is in the cover position, it is possible to perform flushing in order to eliminate thickening of ink inside the nozzles  16  by ejecting ink from the nozzles  16 . Therefore, maintenance of the liquid ejecting head  18  by flushing can be performed even in a state in which the liquid ejecting head  18  is at a position facing the medium S (printing area PA). 
     (7) The liquid ejecting apparatus  11  includes recovery ports capable of sucking the fluid inside the recessed portions  20 . Therefore, even when the liquid ejecting head  18  is at a position facing the medium S, it is possible to recover a fluid such as a maintenance liquid used for maintenance in the periphery of the nozzles  16 . 
     (8) When the shutter  22  is in the cover position, the liquid ejecting apparatus  11  sucks and recovers the fluid inside the recessed portions  20  from the recovery ports  41 . Therefore, because the inside of the recessed portions  20  is sucked from the recovery ports  41  with the recessed portions  20  covered by the shutter  22 , it is possible to efficiently recover fluid such as the maintenance liquid used for maintenance in the periphery of the nozzles  16 . 
     (9) In the liquid ejecting apparatus  11 , the recovery ports  41  and the inside of the recessed portions  20  are at least partially in communication with each other via communication paths formed by the inner bottom surface  27  of the shutter  22 , and when the shutter  22  is in the exposure position, the suction operation of sucking from the recovery ports  41  is performed. Consequently, during printing, after flushing has been performed with the shutter  22  moved to the cover position, while ejecting ink from the nozzles  16  of the liquid ejecting head  18  onto the medium S with the shutter  22  moved to the exposure position, the flushing ink attached to the inner bottom surface  27  of the shutter  22  can be recovered. Therefore, as a result of the recovery operation of recovering the flushing ink attached to the inner bottom surface  27  of the shutter  22 , it is possible to prevent the printing operation of the liquid ejecting head from being interrupted. 
     (10) The liquid ejecting apparatus  11  includes the wiper  53  disposed so as to be in contact with at least the shutter  22  and when the shutter  22  is in the exposure position and the wiper  53  is in contact with the shutter  22 , the wiper  53  and the shutter  22  move relative to each other along the outer surface of the shutter  22 . Consequently, at least the ink attached to the outer surface of the shutter  22  can be wiped by the wiper  53 . 
     Modification Examples 
     Further, the above embodiment may be modified as follows. 
     The wiper  53  may be omitted. 
     The recovery ports  41  may be omitted. 
     The opening and closing valve  39  may be omitted. 
     The shutter  22  may be formed in a flat plate shape. 
     The recessed portion forming member  21  may be omitted. In this case, the recessed portions  20  are formed, for example, by making the nozzle opening surface  19  of the nozzle forming portion  17  uneven. In this way, the number of components constituting the liquid ejecting head unit  12  can be reduced. In this case, by forming the nozzle forming portion  17  and the shutter  22  of a magnetic material (for example, SUS 430 or electromagnetic stainless steel), the shutter  22  may slidably adsorb to the nozzle opening surface  19  of the nozzle forming portion  17  by magnetic force. In the case where separate magnets are not provided in the liquid ejecting head unit  12 , at least one of the nozzle forming portion  17  and the shutter  22  may be magnetized. 
     The recessed portion forming member  21  may be constituted by a porous member. In this case, because the maintenance liquid can be held by the recessed portion forming member  21 , the inside of the nozzles  16  and the inside of the recessed portions  20  can be effectively moisturized. 
     The recessed portion forming member  21  may be formed of rubber, elastomer (silicon type, fluorine type or the like), plastic film (polyethylene, polypropylene, polyamide, polyethylene terephthalate or the like), or the like. In this way, it is possible to improve sealing properties between the recessed portion forming member  21  and both the nozzle opening surface  19  and the shutter  22 . 
     In the liquid ejecting apparatus  11 , the recessed portion forming member  21  can slide along the nozzle opening surface  19  in the scanning direction in the same way as the shutter  22 , and the shutter  22  and the recessed portion forming member  21  may be individually slid. In this case, the recessed portion forming member  21  moves between the open position (the position illustrated in  FIG. 6 ) in which the nozzles  16  are open and the closed position (the position illustrated in  FIG. 7 ) in which the nozzles  16  are closed. In this way, after the maintenance operation with the shutter  22  moved to the cover position, it is possible to wipe the nozzle opening surface  19  by using the recessed portion forming member  21  by sliding only the recessed portion forming member  21  from the open position to the closed position. Thereafter, moisturizing of the inside of the nozzles  16  and the recessed portions  20  is performed by returning the recessed portion forming member  21  to the open position and waiting, and in the case where printing is to be performed, the shutter  22  in the cover position is moved to the exposure position. Further, as a mechanism that slides the recessed portion forming member  21  along the nozzle opening surface  19  in the scanning direction, as illustrated in  FIG. 8 , a pair of winding shafts  55  disposed so as to face the liquid ejecting head  18  in the scanning direction may be used. In this case, the recessed portion forming member  21  is formed of a flexible material, and the two ends thereof in the scanning direction are respectively attached to the pair of the winding shafts  55 . Then, by winding the recessed portion forming member  21  with one of the winding shafts  55  and winding the recessed portion forming member  21  with the other one of the winding shafts  55 , the recessed portion forming member  21  slides between the open position and the closed position. In this case, the nozzle opening surface  19  may be wiped by the recessed portion forming member  21  by winding the recessed portion forming member  21  with only one of the pair of winding shafts  55 . In the case of the recessed portion forming member  21  being completely wound by one of the winding shafts  55 , the old recessed portion forming member  21  may be replaced with a new recessed portion forming member  21 . 
     When the shutter  22  is in the cover position, the liquid ejecting apparatus  11  may drive the actuators  23  of the liquid ejecting head  18  in a state where the maintenance liquid fills the inside of the recessed portions  20  so as to be in contact with the nozzles  16 . In this way, it is possible to make it easier to discharge thickened ink inside the nozzles  16 . 
     By forming the recessed portion forming member  21  and the shutter  22  of a magnetic material (for example, SUS 430, electromagnetic stainless steel or the like), the shutter  22  may be slidably adsorbed to the recessed portion forming member  21  by magnetic force. In the case where no separate magnets are provided in the liquid ejecting head unit  12 , at least one of the recessed portion forming member  21  and the shutter  22  may be magnetized. 
     The wiper  53  may be formed of an absorbent member such as a cloth wiper and the outer surface of the shutter  22  may be wiped by the absorbent member with the shutter  22  moved to the cover position. In this way, because the absorbent member comes into contact with the outer surface of the recessed portion forming member  21  via the opening portions  29  of the shutter  22 , the ink, the maintenance liquid, or the like remaining between the inner bottom surface  27  of the shutter  22  and the outer surface of the recessed portion forming member  21  can be absorbed by the absorbent member and recovered. 
     In the case where flushing of the inner bottom surface  27  of the shutter  22  is performed, it is not absolutely necessary to move the shutter  22  to the cover position. For example, as illustrated in  FIG. 9 , flushing may be performed on the inner bottom surface  27  of the shutter  22  with the shutter  22  moved so that the recessed portions  20  are about half-covered. 
     The liquid ejecting apparatus  11  may perform suction cleaning in which ink (liquid) is sucked from the nozzles  16  by generating negative pressure inside the recessed portions  20  by moving the shutter  22  to the cover position and driving the recovery pump  43  with the opening and closing valve  39  closed. 
     The liquid ejecting apparatus  11  may, without performing maintenance of the liquid ejecting head  18  using the shutter  22 , perform maintenance of the liquid ejecting head  18  using the maintenance mechanism  15 . That is, maintenance of the liquid ejecting head  18  such as suction cleaning, pressure cleaning, wiping, and flushing is performed with the shutter  22  of the liquid ejecting head unit  12  moved to the exposure position in a state where the liquid ejecting head unit  12  is waiting at a position facing the non-printing area. 
     The liquid ejecting apparatus  11  may perform maintenance (for example, suction cleaning, flushing, or the like) of the liquid ejecting head  18  using the shutter  22  in a state where the liquid ejecting head unit  12  is waiting at a position facing the non-printing area. 
     The liquid ejecting apparatus  11  may be a printer having only a printing function, or may be a facsimile, a copying apparatus, or a printer included in a multifunction machine including these apparatuses. 
     The liquid ejecting apparatus  11  may be a so-called line head type printer in which the liquid ejecting head unit  12  does not move (scan). 
     The liquid ejecting apparatus  11  may be a liquid ejecting apparatus that ejects or discharges liquid other than ink. The liquid discharged as a minute amount of liquid droplets from the liquid ejecting apparatus may have a granular shape, teardrop shape, or thread-like tail shape. The liquid may be any material that can be ejected from the liquid ejecting apparatus. For example, the liquid may be any substance which is in a liquid phase, and may be a liquid body having high or low viscosity or a fluid body such as sol, gel water, another inorganic solvent, organic solvent, solution, liquid resin, or liquid metal (metal melt). The liquid may be not only a liquid as one state of a substance but alternatively a liquid obtained by dissolving, dispersing or mixing particles of a functional material composed of a solid such as a pigment or metal particles in a solvent. Representative examples of the liquid include ink, liquid crystal, and the like as described in the above embodiment. The ink may be any of various kinds of liquid compositions such as general water-based ink, oil-based ink, gel ink, hot melt ink or the like. Specific examples of the liquid ejecting apparatus include liquid ejecting apparatuses that eject liquids containing dispersed or dissolved materials such as electrode materials or coloring materials used for manufacturing liquid crystal displays, EL (electroluminescence) displays, surface emitting displays, color filters, or the like. The liquid ejecting apparatus may be a liquid ejecting apparatus that ejects a bioorganic material used for biochip manufacturing, a liquid ejecting apparatus that is used as a precision pipette and that ejects a liquid serving as a sample, a textile printing apparatus, a micro-dispenser, or the like. The liquid ejecting apparatus may be a liquid ejecting apparatus that ejects lubricating oil onto a precision machine such as a watch or a camera in a pinpoint manner, or a liquid ejecting apparatus that ejects a transparent resin liquid such as an ultraviolet curable resin onto a substrate to form a micro-hemispherical lens (optical lens) or the like used for an optical communication element or the like. The liquid ejecting apparatus may be a liquid ejecting apparatus that ejects an etching solution such as an acid or an alkali to etch a substrate or the like. 
     In the embodiment, by making the openings of the maintenance liquid supply ports  31  at the nozzle opening surface  19  open in an area of the nozzle opening surface  19  inside the recessed portions  20 , the openings of the maintenance liquid supply ports  31  at the nozzle opening surface  19  communicate with the inside of the recessed portions  20 ; however, in the case where the openings of the maintenance liquid supply ports  31  at the nozzle opening surface  19  and the inside of the recessed portions  20  are made to communicate using the gap between the inner bottom surface  27  of the shutter  22  and the outer surface  28  of the recessed portion forming member  21 , the openings of the maintenance liquid supply ports  31  at the nozzle opening surface  19  do not have to open in an area of the nozzle opening surface  19  inside the recessed portions  20 . 
     In the embodiment, by making the openings of the recovery ports  41  at the nozzle opening surface  19  open in the area of the nozzle opening surface  19  inside the recessed portions  20 , the inside of the recessed portions  20  communicates with the openings of the recovery ports  41  at the nozzle opening surface  19 ; however, in the case where the openings of the recovery ports  41  at the nozzle opening surface  19  and the inside of the recessed portions  20  are made to communicate using the gap between the inner bottom surface  27  of the shutter  22  and the outer surface  28  of the recessed portion forming member  21 , the openings of the recovery ports  41  at the nozzle opening surface  19  do not have to open in an area of the nozzle opening surface  19  inside the recessed portions  20 . 
     In the embodiment, the inside of the recessed portions  20  and the openings of the maintenance liquid supply ports  31  at the nozzle opening surface  19  are made to communicate with each other through the second communication paths  45  (the portion of the recessed portions  20  serving as the second guide path), however, grooves may be provided in the inner bottom surface  27  of the shutter  22  and consequently the second communication paths  45  (the second guide path) that enable the openings of the maintenance liquid supply ports  31  at the nozzle opening surface  19  and the inside of the recessed portions  20  to communicate with each other may be formed. In this case, the openings of the maintenance liquid supply ports  31  at the nozzle opening surface  19  need not open in an area of the nozzle opening surface  19  inside the recessed portions  20 . 
     In the embodiment, the openings of the recovery ports  41  at the nozzle opening surface  19  and the inside of the recessed portions  20  are made to communicate with each other through the first communication paths  44  (the portion of the recessed portions  20  serving as the first guide path); however, narrow grooves may be provided in the inner bottom surface  27  of the shutter  22  and consequently the first communication paths  44  (a first guide path) that enable the inside of the recessed portions  20  to communicate with the openings of the recovery ports  41  at the nozzle opening surface  19  may be formed. In this case, the openings of the recovery ports  41  at the nozzle opening surface  19  need not open in an area of the nozzle opening surface  19  inside the recessed portions  20 .