Patent Publication Number: US-9421777-B2

Title: Liquid ejecting apparatus

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. 2014-169945 filed on Aug. 22, 2014. The entire disclosures of Japanese Patent Application No. 2014-169945 is hereby incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to technology in which a liquid such as ink is ejected. 
     2. Related Art 
     In a configuration in which a plurality of head units which eject the liquid from nozzles are arranged, the removal of the liquid which enters gaps between the head units which are adjacent to each other becomes a problem. JP-A-2013-173264 discloses technology in which, by inserting projecting portions of an elastic material into groove portions (joins) between the head units which are adjacent to each other and moving the projecting portions, the groove portions are cleaned. JP-A-2010-005856 discloses a configuration in which an ink which is present in the gaps between the head units which are adjacent to each other is sucked from opening portions which are shaped to correspond to the gaps. 
     However, since an error may arise in the interval between the gaps of the head units which are adjacent to each other, it is difficult to sufficiently clean the gaps between the head units using the technology of JP-A-2013-173264 and JP-A-2010-005856. For example, when the gaps between the head units are wider than a planned value, the projecting portions of JP-A-2013-173264 or the opening portions of JP-A-2010-005856 do not closely adhere to the inner wall surfaces of the gaps, and, as a result, it is difficult to sufficiently perform the cleaning. Meanwhile, when the gaps between the head units are narrower than the planned value, the projecting portions of JP-A-2013-173264 or the opening portions of JP-A-2010-005856 are not inserted into the gaps, and it is nevertheless difficult to sufficiently perform the cleaning. Note that, in the above description, for convenience, focus was placed on the gaps between the head units which are adjacent to each other; however, a similar problem can occur with regard to a gap which is formed between one head unit and another element (for example, a housing which holds a plurality of head units). 
     SUMMARY 
     An advantage of some aspects of the invention is that gap is effectively cleaned even when there is an error in the interval between the gap which is formed by a head unit. 
     Aspect  1   
     According to an aspect  1  of the invention, there is provided a liquid ejecting apparatus including: a liquid ejecting head in which a plurality of head units which eject a liquid from a nozzle which is formed in an ejection surface are arranged along a first direction; and a brush which includes a plurality of bristle members for cleaning a gap which is formed by the head units. In the aspect described above, the brush which includes the plurality of bristle members is used in the cleaning of the gap. Since the number of the bristle members of the brush which enter the gap is variable according to the interval of the gap, in comparison to the configuration of JP-A-2013-173264 or JP-A-2010-005856 in which the fixed-shape member is inserted into the gap, there is a merit in that it is possible to effectively clean the gap even when there is an error in the interval of the gap which is formed by the head unit. Note that, a typical example of the gap which serves as the cleaning target of the brush is the gap between the head units which are adjacent to each other; however, it is also possible to apply the invention to the cleaning of the gap between a single arbitrary head unit and another element (for example, a member such as the housing which holds the plurality of head units). 
     Aspect  2   
     In the liquid ejecting apparatus according to a preferred example of the aspect  1  (aspect  2 ), in which the gap which is formed by the head units may extend along a second direction which intersects the first direction, and in which a dimension of a bristle sheaf of the plurality of bristle members in a third direction which orthogonally intersects the second direction be greater than an interval of the gap. In the aspect described above, since the dimension of the bristle sheaf in the third direction is greater than the interval of the gap, the previously described effect of being able to effectively clean the gap even when there is an error in the interval of the gap is especially remarkable. 
     Aspect  3   
     In the liquid ejecting apparatus according to a preferred example of the aspect  1  or  2  (aspect  3 ), in which the length of the plurality of bristle members may be selected such that a tip of each of the bristle members of the plurality of bristle members other than the bristle members which enter the gap does not reach the nozzle. In the aspect described above, the length of each of the bristle members is selected such that the tip of each of the bristle members of the plurality of bristle members which does not enter the gap does not reach the nozzle. Therefore, it is possible to prevent a situation in which the tips of the bristle members of the brush enter the inside of the nozzle and destroy the liquid meniscus. 
     Aspect  4  and Aspect  5   
     In the liquid ejecting apparatus according to a preferred example of the aspects  1  to  3  (aspect  4 ), in which a diameter of each of the bristle members may be smaller than an inner diameter of the nozzle. In the aspect described above, since the bristle member with a smaller diameter than the inner diameter of the nozzle is arranged, there is a merit in that it is possible to sufficiently secure the capillary force which absorbs and holds the liquid of the gap which is formed by the head units. Meanwhile, according to the aspect (aspect  5 ) in which the diameter of each of the bristle members is greater than the inner diameter of the nozzle, since the tips of the bristle members do not enter the inner portion of the nozzle, there is a merit in that it is possible to prevent the destruction of the meniscus of the inner portion. 
     Aspect  6   
     In the liquid ejecting apparatus according to a preferred example of the aspects  1  to  5  (aspect  6 ), in which the gap which is formed by the head units may extend along a second direction which intersects the first direction, and in which the brush may move relative to the gap along the second direction. In the aspect described above, since the brush moves relative to the gap along the direction in which the gap which is formed by the head units extends, there is a merit in that it is possible to effectively remove the liquid within the gap. 
     Aspect  7   
     According to a preferred example of the aspects  1  to  6  (aspect  7 ), there is provided a liquid ejecting apparatus further including a wiper member which wipes the ejection surface, in which after the gap is cleaned by the brush, the wiper member wipes the ejection surface. In the aspect described above, since the wiper member wipes the ejection surface after the gap is cleaned by the brush, there is a merit in that it is possible to remove the liquid, which moves from the gap to the ejection surface in the cleaning by the brush, by wiping the liquid with the wiper member. 
     Aspect  8   
     In the liquid ejecting apparatus according to a preferred example of the aspects  1  to  5  (aspect  8 ), in which the gap which is formed by the head units may extend along a second direction which intersects the first direction, and in which the brush may rotate around a rotational axis which is parallel to the ejection surface and orthogonally intersects the second direction. In the aspect described above, since the brush rotates around the rotational axis which is parallel to the ejection surface and orthogonally intersects the second direction, there is a merit in that it is possible to efficiently remove the liquid of the gap which is formed by the head units. 
     Aspect  9   
     In the liquid ejecting apparatus according to a preferred example of the aspects  1  to  5  (aspect  9 ), in which the brush may move relative to the ejection surface along a direction perpendicular to the ejection surface. In the aspect described above, since the brush moves relative to the ejection surface along the direction which is perpendicular to the ejection surface, there is a merit in that it is possible to suppress the splashing of the liquid within the gap in comparison to a configuration in which the brush is caused to move along the direction in which the gap which is formed by the head units extends. 
     Aspect  10   
     According to a preferred example of the aspect  9  (aspect  10 ), there is provided a liquid ejecting apparatus further including a cap member which seals the ejection surface, in which the brush moves relative to the ejection surface with the cap member. In the aspect described above, since the brush moves relative to the ejection surface with the cap member, in comparison to a configuration in which the brush and the cap member are caused to move independently from each other, there is a merit in that the configuration and processes for controlling the brush and the cap member are simplified. 
     Aspect  11   
     According to a preferred example of the aspects  1  to  10  (aspect  11 ), there is provided a liquid ejecting apparatus further including a removal unit which removes a liquid which adheres to the brush from the brush. In the aspect described above, since the removal unit which removes the liquid which adheres to the brush is disposed, there is a merit in that it is possible to reduce the likelihood of the liquid which adheres to the brush in the cleaning of the gap re-adhering to the gap or another location. 
     Aspect  12   
     In the liquid ejecting apparatus according to a preferred example of the aspects  1  to  11  (aspect  12 ), in which a side surface of the head unit may include a first region and a second region which is positioned on the ejection surface side in a direction perpendicular to the ejection surface from a perspective of the first region, in which the second region may have a higher hydrophobicity than the first region, and in which of the plurality of bristle members, a tip of each of the bristle members which enters the gap may reache the first region. In a configuration in which the hydrophobicity of the first region is low in comparison to the second region of the ejection surface side, there is a tendency for the liquid to be easily retained in the space which is interposed by the first regions of the head units. In the aspect described above, since the tips of the bristle members which enter the gap reach the first region, there is a merit in that it is possible to effectively remove the liquid which is retained in the space corresponding to the first region. 
    
    
     
       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 configuration diagram of a printing apparatus according to a first embodiment of the invention. 
         FIG. 2  is a plan view of a liquid ejecting head. 
         FIG. 3  is an exploded perspective diagram of a head unit. 
         FIG. 4  is a configuration diagram of a cleaning mechanism. 
         FIG. 5  is a perspective diagram of a brush. 
         FIG. 6  is an explanatory diagram of the relationship between the brush and the head unit. 
         FIG. 7  is an explanatory diagram of the relationship between the brush and the head unit. 
         FIG. 8  is a configuration diagram of a cleaning mechanism in a second embodiment. 
         FIG. 9  is a configuration diagram of a cleaning mechanism in a third embodiment. 
         FIG. 10  is an explanatory diagram of a cleaning operation in the third embodiment. 
         FIG. 11  is a configuration diagram of a brush in a fourth embodiment. 
         FIG. 12  is a configuration diagram of a liquid ejecting head in a fifth embodiment. 
         FIG. 13  is a configuration diagram of a cleaning mechanism in the fifth embodiment. 
         FIG. 14  is a configuration diagram of a printing apparatus in a modification example. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
       FIG. 1  is a configuration diagram illustrating a portion of an ink jet printing apparatus  10  according to the first embodiment of the invention. The printing apparatus  10  of the first embodiment is a liquid ejecting apparatus which ejects an ink, which is an example of the liquid, onto a medium (an ejection target)  12  such as printing paper, and is provided with a control apparatus  22 , a transport mechanism  24 , a liquid ejecting head  26 , and a cleaning mechanism  28 . A liquid container (a cartridge)  14  which stores the ink is mounted to the printing apparatus  10 . 
     The control apparatus  22  performs the overall control of each element of the printing apparatus  10 . The transport mechanism  24  transports the medium  12  along a Y direction under the control of the control apparatus  22 . The liquid ejecting head  26  ejects the ink which is supplied from the liquid container  14  onto the medium  12  under the control of the control apparatus  22 . The liquid ejecting head  26  of the first embodiment is a line head which is long in an X direction which intersects (typically, orthogonally intersects) the Y direction. A desires image is formed on the surface of the medium  12  due to the liquid ejecting head  26  ejecting the ink onto the medium  12  in parallel with the transportation of the medium  12  by the transport mechanism  24 . Note that, a direction which is perpendicular to the X-Y plane (a surface which is parallel with the surface of the medium  12 ) will be referred to as a Z direction hereinafter. The ejection direction (downward in the vertical direction) of the ink by the liquid ejecting head  26  corresponds to the Z direction. 
       FIG. 2  is a plan view of a surface of the liquid ejecting head  26  which faces the medium  12 . As exemplified in  FIG. 2 , the liquid ejecting head  26  is provided with a plurality of head units U which are lined up along the X direction.  FIG. 3  is an exploded perspective diagram of an arbitrary one of the head units U of the liquid ejecting head  26 . As exemplified in  FIGS. 2 and 3 , each of the head units U includes a support body  32 , a fixing plate  34 , and a plurality of liquid ejecting units  40 . The support body  32  is a housing which supports the plurality of liquid ejecting units  40 . 
     Each of the liquid ejecting units  40  is a head chip which ejects the ink from a plurality of nozzles (ejection holes) N which are formed in a surface (hereinafter, referred to as an “ejection surface”) S of the positive side of the Z direction. For example, the liquid ejecting unit  40  is configured to include a plurality of sets (not shown) of a pressure chamber and a piezoelectric element, where each set corresponds to a different nozzle N. The ink which fills the pressure chamber is ejected from the corresponding nozzle N due to the supply of a drive signal causing the piezoelectric element to vibrate to change the pressure inside the pressure chamber. The surface of the nozzle plate on which the plurality of nozzles N is formed corresponds to the ejection surface S. As exemplified in  FIG. 2 , the plurality of liquid ejecting units  40  is arranged along the X direction. 
     As exemplified in  FIG. 3 , the fixing plate  34  includes a plate portion  342  and edge portions  344 . The plate portion  342  is a planar plate shape which is parallel to the X-Y plane, and the edge portions  344  continue along the edges of both sides in the X direction of the plate portion  342 . The plurality of liquid ejecting units  40  are fixed to the surface of the plate portion  342 . Opening portions  346  which expose the ejection surfaces S of the liquid ejecting units  40  are formed in the plate portion  342 . Each of the edge portions  344  is a portion which is folded in the negative side of the Z direction in relation to the plate portion  342 , and, for example, is fixed to the support body  32  using an adhesive. The fixing plate  34  of the first embodiment is formed of a highly rigid material (for example, stainless steel), and the surface thereof is rendered hydrophobic by being subjected to well-known water repellent finishing. 
     As can be understood from  FIG. 2 , the plurality of nozzles N of each of the liquid ejecting units  40  is arranged along a WA direction in the X-Y plane. The WA direction is a direction within the X-Y plane which intersects the X direction and the Y direction in a non-perpendicular manner. Specifically, the WA direction is inclined at an angle from 30° to 60° in relation to the Y direction. As described above, since the plurality of nozzles N is arranged along the WA direction which is inclined in relation to the Y direction in which the medium  12  is transported, in comparison to a configuration in which the plurality of nozzles N is arranged in a straight line along the X direction, it is possible to increase the effective dot density (the resolution) in the X direction of the medium  12 . As can be understood from  FIG. 2 , the planar external shape of the plate portion  342  of the fixing plate  34  in the first embodiment is a planar rectangular shape which is demarcated by the edges which extend in the WA direction and the edges which extend in the X direction. 
     As exemplified in  FIG. 2 , gaps G are present between the head units U which are adjacent to each other in the X direction. As described earlier, since the edges which are positioned on both sides of the plate portion  342  of the fixing plate  34  in the X direction extend along the WA direction, the gaps G extend along the WA direction in plan view. There is a likelihood that the ink which is ejected from the nozzles N of each of the liquid ejecting units  40  will enter the gaps G. The ink which is retained in the gaps G may adhere to the surface of the medium  12  which passes the proximity of the fixing plate  34  of each of the head units U. In consideration of the issues described above, the printing apparatus  10  of the first embodiment is provided with a cleaning mechanism  28  for cleaning the gaps G of the head units U. 
       FIG. 4  is a plan view of the cleaning mechanism  28  as viewed from the positive side (the medium  12  side) of the Z direction. The external shape of each of the head units U is also depicted in  FIG. 4 . As exemplified in  FIG. 4 , the cleaning mechanism  28  is provided with a plurality of brushes  50 , each of which corresponds to a different one of the gaps G of the liquid ejecting head  26 . The plurality of brushes  50  is arranged along the X direction, and each of the brushes  50  is positioned on a line extending from the corresponding gap G in plan view. An arbitrary one of the brushes  50  of the cleaning mechanism  28  is used in the cleaning of the gap G which corresponds to the aforementioned brush  50 . 
       FIG. 5  is a perspective diagram of an arbitrary one of the brushes  50 . As exemplified in  FIG. 5 , the brush  50  of the first embodiment includes a base portion  52  and a bristle sheaf  54 . The base portion  52  is a planar shape, and the bristle sheaf  54  is disposed on the surface of the base portion  52  which faces the liquid ejecting head  26 . The bristle sheaf  54  is a collection of a plurality of bristle members  55  which are bound together in a state of being aligned substantially along the same direction (the Z direction). Each of the plurality of bristle members  55  which form the bristle sheaf  54  is a thin, long line-shaped object with a circular cross-section, and is formed of a material which is capable of elastic deformation. The material of the bristle members  55  is arbitrary; however, in addition to a line-shaped material which is formed of a resin material such as polypropylene, for example, being favorable used as the bristle member  55 , it is also possible to use vegetable fiber or animal hair as the bristle member  55 . 
     When the bristle strength of the bristle members  55  which form the bristle sheaf  54  is excessively low, it becomes difficult to sufficiently remove the ink inside the gaps G, and, when the bristle strength of the bristle members  55  is excessively high, it becomes difficult to cause the multiple bristle members  55  to enter the gaps G. The total length, the diameter, and the material of the bristle members  55  are selected such that the bristle strength is adjusted to fall within an appropriate range at which the problems exemplified above do not occur. Specifically, a configuration in which the bristle strength (a 7 mm bristle strength) of each bristle member  55  is a numerical value within a range of 50 N/cm 2  to 85 N/cm 2  (more favorably, within a range of 60 N/cm 2  to 75 N/cm 2 ), for example, is favorable. Note that, the bristle strength is measured using a method defined in the Japanese Industrial Standard (JIS) S3016. 
     As exemplified in  FIG. 4 , a dimension (a horizontal width) ω of the bristle sheaf  54  in the WB direction which orthogonally intersects the WA direction in the X-Y plane is greater than an interval (a dimension in the WB direction) D of the gap G between the head units U. The interval D is the distance between the side surfaces of the head units U which face each other to interpose the gap G. Note that, there may be an error in the interval D of each of the gaps G, caused by an error in the dimensions of the elements which form the head units U of the liquid ejecting head  26 . Although it is possible to adjust the positions of the head units U so as to render the intervals D of the gaps G of the head units U uniform, since the positions of the head units U are adjusted such that each of the nozzles N of each of the head units U is actually positioned at a target point (in other words, using the nozzles N as a reference), there is an issue in which an error may inescapably arise in the intervals D of the gaps G of the head units G. The dimension ω of the bristle sheaf  54  of each of the brushes  50  is selected so be greater than an anticipated maximum value of the interval D, taking errors such as those described above into account. The diameter of each of the bristle members  55  is small in comparison to the inner diameter of each of the nozzles N of the liquid ejecting unit  40 . For example, since the inner diameter of each of the nozzles N is 20 μm, a bristle member  55  with an inner diameter of less than 20 μm is used favorably in the brush  50 . 
     As illustrated by the broken line arrows in  FIG. 4 , the cleaning mechanism  28  moves in relation to the liquid ejecting head  26  under the control of the control apparatus  22 . Specifically, as exemplified in  FIG. 4 , the cleaning mechanism  28  of the first embodiment moves along the WA direction in relation to the liquid ejecting head  26  such that each of the plurality of brushes  50  moves in a straight line along the WA direction from a point PA to a point PB. The point PA and the point PB are positioned on opposite sides from each other in plan view to interpose the liquid ejecting head  26 . 
       FIGS. 6 and 7  are schematic diagrams of a state in which an arbitrary one of the brushes  50  is positioned (in a position between the point PA and the point PB) to overlap the liquid ejecting head  26  in plan view as depicted by the broken lines in  FIG. 4 .  FIG. 6  depicts the state of the brush  50  as viewed from the WA direction, and  FIG. 7  depicts the state of the brush  50  as viewed from the WB direction. 
     As exemplified in  FIG. 6 , a portion of the bristle sheaf  54  of each of the brushes  50  is positioned on the inside of the gap G between the head units U in a state of being positioned part way along the line from the point PA to the point PB. Specifically, the tip sides of the bristle members  55  of the portion of the center side of the bristle sheaf  54  in the WB direction enter the gap G. Meanwhile, the bristle members  55  of the bristle sheaf  54  which do not enter the gap G (the bristle members  55  of both end sides of the bristle sheaf  54  in the WB direction) make contact with the surface of the plate portion  342  and bend elastically. As exemplified in  FIG. 7 , the plurality of bristle members  55  of the bristle sheaf  54  which enter the gap G bend elastically such that the tip side is expanded in comparison to the baser side (the plate portion  342  side). 
     Each of the brushes  50  of the cleaning mechanism  28  proceeds in the WA direction toward the point PB from the point PA in a state in which the plurality of bristle members  55  of the bristle sheaf  54  is maintained in the shape which is exemplified above. According to the configuration described above, the ink which is retained in the gap G is absorbed and held by the inner portion of the bristle sheaf  54  due to the capillary force of the plurality of bristle members  55  of the bristle sheaf  54  of each of the brushes  50  which enters the corresponding gap G. Therefore, the ink which is retained by the gaps G of the head units U is removed by causing the brushes  50  to move in the WA direction from the point PA to the point PB. 
     The number of the bristle members  55  of the bristle sheaf  54  of each of the brushes  50  which enter the inside of the gap G changes according to the interval D of the gap G. Specifically, the greater the interval D of the gap G, the more the number of the bristle members  55  of the bristle sheaf  54  which enter the corresponding gap G increases. Therefore, according to the first embodiment, in comparison to the configurations of JP-A-2013-173264 and JP-A-2010-005856 in which a fixed-shape member (the projecting portion in JP-A-2013-173264 and the opening portion in JP-A-2010-005856) is inserted into a gap, there is a merit in that it is possible to effectively clean the gap G even when there is an error in the interval D of the gap G between the head units U. In the first embodiment, since the dimension ω of the bristle sheaf  54  in the WB direction exceeds the interval D of the gap G, the effect of being able to effectively clean the gap G even when there is an error in the interval D is especially remarkable. In particular, in the first embodiment, since the bristle members  55 , each of which has a small diameter of a degree which is less than the inner diameter of the nozzle N of the liquid ejecting unit  40 , are arranged at a high density, for example, in comparison to a configuration in which the diameter of the bristle member  55  exceeds the inner diameter of the nozzle N (a configuration in which the bristle member  55  is thick), there is a merit in that it is possible to sufficiently secure the capillary force which absorbs and holds the ink in the gap G. 
     As exemplified in  FIG. 6 , the side surface of an arbitrary one of the head units U which faces another head unit U which is adjacent thereto in the X direction includes a first region A 1  and a second region A 2 . The second region A 2  is positioned on the positive side in the Z direction (the ejection surface S side) as viewed from the first region A 1 . In the first embodiment, the surface of the support body  32  which supports the plurality of liquid ejecting units  40  corresponds to the first region A 1 , and the surface of each of the edge portions  344  of the fixing plate  34  corresponds to the second region A 2 . 
     As described earlier, since the surface of the fixing plate  34  is rendered hydrophobic, the hydrophobicity of the first region A 1  is low in comparison to the second region A 2 . Therefore, there is a tendency for the ink, which enters the gap G between two of the head units U which are adjacent to each other in the X direction, to be easily retained in the space in which the first regions A 1  of the gaps G of the head units U face each other. In consideration of the tendency described above, in the first embodiment, the total length of each of the bristle members  55  of the bristle sheaf  54  is selected such that the tip of each of the bristle members  55  of the bristle sheaf  54  of each of the brushes  50  which enters the gap G reaches the first region A 1 . Therefore, there is a merit in that it is possible to effectively remove the ink which is retained in the space of the first region A 1  in the gap G. 
     As exemplified in  FIG. 6 , in the first embodiment, the total length of the plurality of bristle members  55  is selected such that the tips of the plurality of bristle members  55  (the plurality of bristle members  55  of the bristle sheaf  54  other than the bristle members  55  which enter the gap G) of the bristle sheaf  54  of each of the brushes  50  which are positioned outside of the gap G do not reach the nozzles N of the liquid ejecting unit  40 . In a configuration in which the tips of the plurality of bristle members  55  of the bristle sheaf  54  which are positioned outside of the gap G reach the nozzles N (a configuration in which the total length of each of the bristle members  55  is sufficiently long), there is a likelihood that the tips of the bristle members  55  will make contact with the meniscus (a curved liquid surface caused by surface tension) of the ink which is formed on the inside of the nozzle N, resulting in the meniscus being broken and bubbles entering the nozzle N. In a configuration in which the diameter of the bristle member  55  is less than the inner diameter of the nozzle N, as in the first embodiment, particularly, since the tip of the bristle member  55  easily enters the inner portion of the nozzle N, there is an issue in that the destruction of the meniscus occurs easily. In consideration of the issues described above, in the first embodiment, the total length of the bristle member  55  is selected such that the tip of the bristle member  55  which is positioned outside of the gap G does not reach the nozzle N. In other words, the tip of the bristle member  55  does not make contact with the meniscus of the inner portion of the nozzle N. Therefore, regardless of the configuration in which the bristle member  55  with a smaller diameter than the inner diameter of the nozzle N in order to sufficiently secure the capillary force, it is possible to realize the remarkable effect in that it is possible to prevent the destruction of the meniscus (in addition to the entrance of bubbles caused by the destruction). 
     Second Embodiment 
     Next, description will be given of the second embodiment of the invention. In each embodiment exemplified hereinafter, the reference numerals which are used in the description of the first embodiment will be reused for elements which have the same operations and functions as those in the first embodiment, and the detailed description of such elements will be omitted as appropriate. 
       FIG. 8  is a plan view of the cleaning mechanism  28  in the second embodiment as viewed from the positive side of the Z direction. As exemplified in  FIG. 8 , in addition to the plurality of brushes  50  which are the same as those in the first embodiment, the cleaning mechanism  28  of the second embodiment is provided with a plurality of wiper members  62  corresponding to the different head units U. Each of the plurality of wiper members  62  is used to wipe the ink which adheres to the contact surface of the liquid ejecting unit  40 . As exemplified in  FIG. 8 , each of the wiper members  62  of the second embodiment is formed in a shape which is long along the WB direction so as to span the interval of the brushes  50  which are adjacent to each other in the WB direction as viewed from the WA direction. 
     The plurality of wiper members  62  moves along the WA direction with the plurality of brushes  50 . For example, the plurality of brushes  50  and the plurality of wiper members  62  are disposed on a shared member. The ink of the ejection surface S is wiped off due to each of the wiper members  62  moving along the WA direction in a state of being in contact with the ejection surface S of each of the liquid ejecting units  40 . As exemplified in  FIG. 8 , each of the wiper members  62  is positioned on the downstream side of each of the brushes  50  in the WA direction in which the cleaning mechanism  28  moves. Therefore, after the gaps G are cleaned by the brushes  50 , the wiper member  62  wipes the ejection surfaces S of the liquid ejecting units  40 . 
     The same effect as in the first embodiment is also realized in the second embodiment. In the second embodiment, since the wiper member  62  which wipes the ejection surface S is disposed in addition to the brush  50  which cleans the gap G, it is possible to effectively clean the liquid ejecting head  26 . In particular, in the second embodiment, since the wiper members  62  wipe the ejection surfaces S after the brushes  50  clean the gaps G, there is a merit in that it is possible to remove the ink which is swept out onto the ejection surfaces S from the gaps G in the cleaning of the gaps G by the brushes  50  due to wiping of the ejection surface S by the wiper member  62 . Since each of the brushes  50  moves with the wiper member  62 , in comparison to a configuration in which the brush  50  is moved independently from the wiper member  62 , there is a merit in that the configuration and processes for controlling the cleaning mechanism  28  are simplified. 
     Note that, the ink which adheres to the ejection surface S may move to the inner portion of the gap G due to use wiping performed by the wiper member  62 . However, since the ink within the gap G is absorbed and held in the bristle sheaf  54  of the brush  50  before the wiping by the wiper member  62 , it is possible to avoid a situation in which a large amount of the ink of a degree which adheres to the medium  12  is retained in the gap G even taking into account the entrance of the ink caused by the wiping by the wiper member  62 . 
     Third Embodiment 
       FIG. 9  is a plan view of the cleaning mechanism  28  in the third embodiment as viewed from the positive side of the Z direction, and  FIG. 10  is a cross sectional diagram taken across the line X-X in  FIG. 9 . As exemplified in  FIGS. 9 and 10 , the cleaning mechanism  28  of the third embodiment is provided with the plurality of brushes  50  corresponding to the gaps G of the head units U, and a plurality of cap members  64  corresponding to the head units U. The plurality of brushes  50  and the plurality of cap members  64  are arranged alternately along the X direction. Each of the brushes  50  of the third embodiment is formed to be long along the WA direction such that the bristle sheaf  54  spans the total length of the gap G. Each of the cap members  64  seals each of the nozzles N by making contact with the ejection surface S of each of the liquid ejecting units  40  of the head unit U. Note that, in  FIG. 9 , although one cap member  64  is arranged for each of the head units U, it is also possible to arrange a plurality of cap members  64  for each of the head units U. 
     As illustrated by the solid lines in  FIG. 10 , during the printing operation, the plurality of brushes  50  of the cleaning mechanism  28  and the plurality of cap members  64  are held in positions separated from the liquid ejecting head  26 . The medium  12  is transported to pass between the cleaning mechanism  28  and the liquid ejecting head  26 . Meanwhile, when the cleaning operation is started, the plurality of brushes  50  move along the Z direction with the plurality of cap members  64 , and approaches the liquid ejecting head  26 . As illustrated by the broken lines in  FIG. 10 , in a state in which each of the cap members  64  closely adheres to the ejection surface S of the liquid ejecting unit  40  and the plurality of nozzles N is sealed, the brush  50  (the portion of the tip side of the bristle sheaf  54 ) enters the gap G of each of the head units U. By generating a negative pressure in the inner portion of the cap member  64  in a state in which the plurality of nozzles N is sealed by the cap member  64 , the ink is forcefully discharged and the suction operation which cleans the nozzles N is executed. The ink which is retained in the gap G is absorbed by the inner portion of the bristle sheaf  54  due to the capillary force of the plurality of bristle members  55  which enter the gap G, and the ink is removed from the gap G. 
     The same effect as in the first embodiment is also realized in the third embodiment. In the third embodiment, since the gap G is cleaned due to the plurality of brushes  50  moving in the Z direction and the bristle sheaf  54  entering the gap G, in comparison with the first embodiment or the second embodiment in which the ink is swept out by causing the brush  50  to move along the gap G, it is possible to suppress the splashing of the ink. In the third embodiment, since it is possible to arrange the cleaning mechanism  28  so as to overlap the liquid ejecting head  26  as viewed from the Z direction, there is also a merit in that it is possible to reduce the size of the printing apparatus  10  as viewed from the Z direction. In the third embodiment, the brushes  50  move in the Z direction with the cap member  64 . Therefore, in addition to sealing the nozzles N using the cap member  64 , it is possible to execute the cleaning of the gap G using the brush  50 . As described above, since each of the brushes  50  moves with the cap member  64 , in comparison to a configuration in which the brush  50  is caused to move independently from the cap member  64 , there is a merit in that the configuration and processes for controlling the cleaning mechanism  28  are simplified. 
     Fourth Embodiment 
       FIG. 11  is a schematic diagram of the cleaning mechanism  28  in the fourth embodiment. In the cleaning mechanism  28  of the fourth embodiment, the brush  50  of  FIG. 11  is arranged corresponding to each of the gaps G. As exemplified in  FIG. 11 , the brush  50  of the fourth embodiment has a structure in which the plurality of bristle members  55  are disposed in a radial shape on the circumferential surface (the side surface) of the disc shaped base portion  52 . The base portion  52  rotates around a rotational axis of the WB direction which is parallel to the ejection surface S (the X-Y plane) of each of the liquid ejecting units  40  and orthogonally intersects the WA direction. Specifically, during the cleaning operation, the plurality of brushes  50  are caused to approach the liquid ejecting head  26  until a state is assumed in which the tips of the plurality of bristle members  55  enter the gaps G between the head units U, and the ink of the gaps G is removed by causing the brushes  50  to rotate around a rotational axis A while maintaining the state described above. 
     A removal member  70  is disposed for each of the brushes  50  on the opposite side from the liquid ejecting head  26  to interpose the brushes  50  of the cleaning mechanism  28 . Each of the removal members  70  is a means for removing the ink which is adhered to the brush  50 . Specifically, a porous absorbent material with high ink absorption properties (capillary force) in comparison to the brush  50  is favorably used as the removal member  70 . Due to a portion of the opposite side of the brush  50  from the liquid ejecting head  26  making contact with the removal member  70  in parallel with an operation in which the ink of the gap G is removed by the rotation of each of the brushes  50 , the ink which adheres to the bristle sheaf  54  moves to the removal member  70 . 
     The same effect as in the first embodiment is also realized in the fourth embodiment. In the fourth embodiment, since by causing the disc shaped brush  50  to rotate, the bristle members  55  of a different portion on the circumference of the disc sequentially enter the gap G, there is a merit in that it is possible to effectively clean the gap G in comparison to the first embodiment to the third embodiment. In the fourth embodiment, since the removal member  70  which removes the ink which adheres to the bristle members  55  of the brush  50  is disposed, there is a merit in that it is possible to reduce the likelihood of the ink which adheres to the bristle members  55  re-adhering to the gap G or another location. 
     Fifth Embodiment 
       FIG. 12  is a cross sectional diagram of the liquid ejecting head  26  according to the fifth embodiment of the invention, and  FIG. 13  is a plan view of the cleaning mechanism  28  in the fifth embodiment. As exemplified in FIG.  12 , the liquid ejecting head  26  of the fifth embodiment is provided with the same plurality of head units U (U 1  to UN) as in the first embodiment, and a housing  36  which holds the plurality of head units U in a state in which the head units U are arranged along the X direction. The housing  36  of the fifth embodiment is a structural body which is long in the X direction and is formed using die casting of a metal material or extrusion formation of a resin material, for example, and includes a side surface portion  36 A which is positioned on the end portion of the negative side of the X direction and a side surface portion  36 B which is positioned on the end portion of the positive side. The plurality of head units U is held between the side surface portion  36 A and the side surface portion  36 B. 
     The side surface portion  36 A faces the side surface of a single head unit U 1  which is positioned on the end portion of the negative side of the X direction of the plurality of head units U, and the side surface portion  36 B faces the side surface of a single head unit UN which is positioned on the end portion of the positive side of the X direction of the plurality of head units U. As exemplified in  FIGS. 12 and 13 , the gaps G which extend along the WA direction in plan view are present between the side surface portion  36 A and the head unit U 1  and between the side surface portion  36 B and the head unit UN in the same manner as the gaps G which are present between the head units U which are adjacent to each other. 
     As exemplified in  FIG. 13 , in addition to the brushes  50  for cleaning the gaps G between the head units U, the cleaning mechanism  28  of the fifth embodiment is provided with the brushes  50  for cleaning the gaps G between the housing  36  (the side surface portion  36 A and the side surface portion  36 B) and the head units U. The structure of each of the brushes  50  and the content (the movement conditions and the like) of the cleaning of the gaps G using the brushes  50  is the same as in the first embodiment. Therefore, according to the fifth embodiment, in addition to the same effect as in the first embodiment, an effect is realized in which it is possible to effectively clean the gap G even when there is a gap G between the housing  36  and the head unit U. 
     Note that, in the cleaning of the gap G between the housing  36  and the head unit U, it is possible to adopt the same overall configuration exemplified with regard to the cleaning of the gap G between the head units U in the first embodiment to the fourth embodiment. In the above description, the cleaning mechanism  28  is exemplified which is provided with both the brush  50  for cleaning the gap G between the head units U, and the brush  50  for cleaning the gap G between the housing  36  and the head unit U; however, a configuration may be adopted in which the cleaning mechanism  28  is provided with only the brush  50  for cleaning the gap G between the housing  36  and the head unit U (a configuration in which the brush  50  corresponding to the gap G between the head units U is omitted). 
     As can be understood from the exemplifications described above, the target of the cleaning carried out by the brush  50  of the cleaning mechanism  28  is comprehensively expressed as the gap G which is formed by the head unit U, and, in addition to the gap G between the head units U exemplified in the first embodiment to the fourth embodiment, the gap G between the head unit U and another element (for example, the housing  36 ) exemplified in the fifth embodiment is included. 
     Modification Example 
     The embodiments exemplified above can be subjected to various modifications. Aspects of specific modifications will be exemplified below. Two or more aspects arbitrarily selected from the following exemplifications may be used together, as appropriate, notwithstanding any contradictions therebetween. 
     (1) In the second embodiment, a configuration is exemplified in which the brush  50  is caused to move integrally with the wiper member  62 ; however, a configuration may be adopted in which the brush  50  is caused to move independently from the wiper member  62 . In the same manner, in the third embodiment, a configuration is exemplified in which the brush  50  is caused to move integrally with the cap member  64 ; however, it is possible to cause the brush  50  to move independently from the cap member  64 . 
     (2) In the fourth embodiment, the removal member  70  which removes the ink which adheres to the brush  50 ; however, it is possible to dispose the same removal member  70  in the first embodiment to the third embodiment, and the fifth embodiment. For example, as exemplified in  FIG. 14 , in the first embodiment and the second embodiment, it is possible to dispose the removal member  70  on the downstream side of the liquid ejecting head  26  in the movement path from the point PA to the point PB. 
     Note that, in the fourth embodiment, the porous absorbent material (a sponge) is exemplified as the removal member  70 ; however, the configuration and material of the removal member  70  is not limited to the aforementioned exemplification. For example, it is possible to use a member which is caused to make contact with the bristle members  55  of the brush  50  to wipe off the ink, or a member (a projecting portion) which removes the ink by elastically flicking the tip side of the bristle members  55  of the brush  50 , as the removal member  70  in each of the embodiments described earlier. 
     (3) In each of the embodiments described earlier, a configuration is exemplified in which all of the bristle members  55  which form the bristle sheaf  54  of the brush  50  have the same properties; however, it is possible to form the bristle sheaf  54  using a plurality of types of the bristle member  55  which have different properties (total length, diameter, material). In each of the embodiments described earlier, a configuration is exemplified in which the diameter of each of the bristle members  55  of the brush  50  is smaller than the inner diameter of the nozzle N; however, a configuration may be adopted in which the diameter of each of the bristle members  55  is larger than the inner diameter of the nozzle N. In a configuration in which the inner diameter of the nozzle N exceeds the diameter of the bristle member  55 , since the tip of the bristle member  55  will not enter the inner portion of the nozzle N, there is a merit in that it is possible to prevent the destruction of the meniscus of the inner portion of the nozzle N (in addition to the entrance of bubbles caused by the destruction). 
     (4) In the first embodiment and the second embodiment, a configuration is exemplified in which the brush  50  is caused to move along the WB direction in relation to the liquid ejecting head  26 ; however, a configuration may be adopted in which each of the brushes  50  of the cleaning mechanism  28  is fixed and the liquid ejecting head  26  is caused to move along the WB direction in relation to the brush  50 . In other words, the configuration in which the brush  50  is caused to move in relation to the liquid ejecting head  26  and the configuration in which the liquid ejecting head  26  is caused to move in relation to the brush  50  are included in a configuration in which the brush  50  is moved relative to the liquid ejecting head  26  (the gap G, that is, a configuration in which one of the liquid ejecting head  26  and the brush  50  is caused to move in relation to the other). The same applies to the wiper member  62  and the cap member  64 , and in addition to a configuration in which the wiper member  62  or the cap member  64  is caused to move in relation to the liquid ejecting head  26  as exemplified in each of the embodiments described earlier, it is possible to adopt a configuration in which the liquid ejecting head  26  is caused to move in relation to the wiper member  62  or the cap member  64 . 
     (5) The system used by the liquid ejecting head  26  to eject the ink is not limited to the system described earlier which uses a piezoelectric element (a piezo system). For example, the invention can also be applied to a liquid ejecting head of a system which uses a heating element to change the pressure within the pressure chamber by generating bubbles within the pressure chamber by heating the pressure chamber (a thermal system). 
     (6) In addition to a device which is specialized for printing, it is possible to adopt various types of device such as a facsimile apparatus or a copier as the printing apparatus  10  which is exemplified in each of the embodiments described above. Naturally, the purpose of the liquid ejecting apparatus of the invention is not limited to printing. For example, a liquid ejecting apparatus which ejects a color material solution is used as a manufacturing apparatus which forms a color filter of a liquid crystal display apparatus. A liquid ejecting apparatus which ejects a conductive material solution is used as a manufacturing apparatus which forms the wiring and electrodes of a wiring substrate.