Patent Publication Number: US-9849702-B2

Title: Liquid ejecting apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting apparatus including a plurality of liquid ejecting heads that eject a liquid, particularly to an ink jet type recording apparatus including ink jet type recording heads that discharge an ink as the liquid. 
     2. Related Art 
     There is proposed an ink jet type recording head unit as an example of a liquid ejecting head unit which includes ink jet type recording heads that eject ink droplets from nozzle openings through a change in pressure by a pressure generating unit, and a head fixing substrate (unit base) on which a plurality of ink jet type recording heads adhere to a side thereof opposite to a liquid ejecting surface in which the nozzle openings are formed (for example, see JP-A-2015-174387). 
     In such an ink jet type recording head unit, the plurality of ink jet type recording heads form a long nozzle array, thereby making it possible to increase a yield ratio and to decrease manufacturing costs, compared to a case where one ink jet type recording head forms a long nozzle array. 
     In addition, the ink jet type recording head unit includes a lifting-lowering mechanism that is capable of adjusting a position of a nozzle-formed surface with respect to an apparatus main body. As a position of the nozzle-formed surface with respect to the apparatus main body, a reference position obtained when an ink jet type recording head touches the apparatus main body is determined (for example, refer to JP-A-2010-046871). 
     However, when the reference position of the nozzle-formed surface with respect to the apparatus main body is defined through the touch, the reference position is shifted due to deformation, positional shifts of components, or the like. Therefore, a problem arises in that it is not possible to position the nozzle-formed surface with respect to the apparatus main body with high accuracy. 
     When there are variations in the position of the nozzle-formed surface with respect to the apparatus main body, there are variations in a gap between an ejection target medium and the nozzle-formed surface which are held in the apparatus main body, and a problem arises in that a landing position of an ink on the ejection target medium is shifted or the like. 
     Note that such problems arise not only in the ink jet type recording apparatus, but also in a liquid ejecting apparatus that ejects a liquid other than an ink. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a liquid ejecting apparatus in which it is possible to position a nozzle-formed surface with respect to an apparatus main body with high accuracy. 
     According to an aspect of the invention, there is provided a liquid ejecting apparatus including: an apparatus main body; a plurality of liquid ejecting heads that have a nozzle-formed surface; a unit base to which the plurality of liquid ejecting heads are fixed; a lifting-lowering mechanism that is fixed to the apparatus main body and causes a position of the nozzle-formed surface to move with respect to the apparatus main body; and a non-contact sensor unit that is provided in the apparatus main body and the unit base and identifies a position of the nozzle-formed surface with respect to the apparatus main body. 
     In this configuration, the non-contact sensor unit identifies the position of the nozzle-formed surface with respect to the apparatus main body, and thereby it is possible to decrease deformation, a positional shift, or the like of a component such that it is possible to identify the position of the nozzle-formed surface with high accuracy, compared to a case where the position of the nozzle-formed surface is identified through touching therebetween. 
     It is preferable that the liquid ejecting apparatus further include a wiper that wipes the nozzle-formed surface from a first side toward a second side, in which the sensor unit is provided on the first side. In this configuration, it is possible to decrease an amount of splashes of liquids that are attached to the sensor unit when the wiper wipes the nozzle-formed surface such that it is possible to reliably position the nozzle-formed surface with high accuracy. 
     In the liquid ejecting apparatus, it is preferable that an end portion, which is wiped by the wiper, be provided with an inclined surface portion on the second side that is gradually separated from the wiper when the wiper relatively moves on the nozzle-formed surface. In this configuration, the gradual separation of the wiper from the nozzle-formed surface along the inclined surface portion makes it possible to decrease production of splashes when the wiper is separated from the nozzle-formed surface. 
     In the liquid ejecting apparatus, it is preferable that the sensor unit be provided on the unit base side from the nozzle-formed surface in a moving direction of the apparatus main body and the nozzle-formed surface. In this configuration, it is possible to decrease an amount of mists that are attached to the sensor unit after the mists are produced through ejection of liquids from the nozzle-formed surface such that it is possible to reliably position the nozzle-formed surface with high accuracy. 
     In the liquid ejecting apparatus, it is preferable that the sensor unit be disposed on an upstream side from the plurality of liquid ejecting heads in a case where the ejection target medium, on which a liquid lands, relatively moves with respect to the plurality of liquid ejecting heads from the upstream side to a downstream side. In this configuration, even when mists produced through the ejection of liquids from the nozzle-formed surface flow to the downstream side through an air current generated when the ejection target medium moves from upstream to downstream, it is possible to decrease an amount of mists that are attached to the sensor unit such that it is possible to reliably position the nozzle-formed surface with high accuracy. 
    
    
     
       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 top view illustrating a schematic configuration of a recording apparatus according to Embodiment 1. 
         FIG. 2  is a side view illustrating the schematic configuration of the recording apparatus according to Embodiment 1. 
         FIG. 3  is an exploded perspective view illustrating a part of a head unit according to Embodiment 1. 
         FIG. 4  is an underside view illustrating the head unit according to Embodiment 1. 
         FIG. 5  is a sectional view illustrating the head unit according to Embodiment 1. 
         FIG. 6  is an enlarged sectional view illustrating a main part of the head unit according to Embodiment 1. 
         FIG. 7  is a sectional view illustrating the head unit according to Embodiment 1. 
         FIG. 8  is a perspective view illustrating a unit base when viewed from a Z 1  side according to Embodiment 1. 
         FIG. 9  is a top view illustrating the unit base according to Embodiment 1. 
         FIG. 10  is an underside view illustrating the unit base according to Embodiment 1. 
         FIG. 11  is a front view illustrating the head unit and a lifting-lowering mechanism according to Embodiment 1. 
         FIG. 12  is a side view illustrating the head unit and the lifting-lowering mechanism according to Embodiment 1. 
         FIG. 13  is a front view illustrating the head unit and the lifting-lowering mechanism according to Embodiment 1. 
         FIG. 14  is a side view illustrating the head unit and the lifting-lowering mechanism according to Embodiment 1 of the invention. 
         FIG. 15  is a top view illustrating the head unit and a sensor unit according to Embodiment 1. 
         FIG. 16  is a side view illustrating the head unit and the sensor unit according to Embodiment 1. 
         FIG. 17  is a side view illustrating the head unit and the sensor unit according to Embodiment 1. 
         FIG. 18  is a front view illustrating the head unit and a wiping unit according to Embodiment 1. 
         FIG. 19  is an underside view illustrating the head unit and the wiping unit according to Embodiment 1. 
         FIG. 20  is a front view illustrating the head unit and the wiping unit according to Embodiment 1. 
         FIG. 21  is an exploded perspective view illustrating a recording head according to Embodiment 1. 
         FIG. 22  is an underside view illustrating a head unit according to another embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, the invention will be described on the basis of embodiments. 
     Embodiment 1 
       FIG. 1  is a top view illustrating a schematic configuration of an ink jet type recording apparatus as an example of a liquid ejecting apparatus according to Embodiment 1 of the invention.  FIG. 2  is a side view illustrating the ink jet type recording apparatus. 
     As illustrated in  FIGS. 1 and 2 , an ink jet type recording apparatus  1  as an example of the liquid ejecting apparatus of the embodiment is a so-called line type recording apparatus  1  that transports a recording sheet S as an ejection target medium and performs printing. 
     Here, in the embodiment, a transport direction of the recording sheet S is referred to as a first direction X, and a direction orthogonal to the first direction X in an in-plane direction of a surface of the recording sheet S, on which an ink lands, is referred to as a second direction Y. In addition, a direction orthogonal to both of the first direction X and the second direction Y, that is, a direction orthogonal to the surface of the recording sheet S on which the ink lands, is referred to as a third direction Z. Further, in the third direction Z, the recording sheet S side is referred to as Z 1 , and the ink jet type recording head unit side is referred to as Z 2 . In the embodiment, an example, in which the directions (X, Y, and Z) are orthogonal to one another, is described; however, the definitions of the directions are not necessarily limited thereto. 
     The ink jet type recording apparatus  1  includes an apparatus main body  2 , an ink jet type recording head unit  3  (hereinafter, also simply referred to as a head unit  3 ) provided to be able to be lifted and lowered with respect to the apparatus main body  2  in the third direction Z, a liquid storing unit  4  such as an ink tank in which an ink as a liquid is stored, and a first transport unit  5  and a second transport unit  6  that transport the recording sheet S. 
     The head unit  3  extends in the second direction Y. In the embodiment, the head unit  3 , which will be described below in detail, includes a plurality of ink jet type recording heads  100  (hereinafter, also simply referred to as a recording head  100 ) that discharge an ink, and a unit base  200  that holds the plurality of recording heads  100 . 
     The liquid storing unit  4  supplies an ink to the head unit  3  and is fixed to the apparatus main body  2 , in the embodiment. The ink from the liquid storing unit  4  fixed to the apparatus main body  2  is supplied to the head unit  3  via a supply tube  4   a  such as a tube. Note that an example, in which the head unit  3  includes the liquid storing unit  4 , for example, the liquid storing unit  4  is mounted above the head unit  3  on the Z 2  side, may be employed. 
     The first transport unit  5  is provided on one side of the head unit  3  in the first direction X, and thus on an X 1  side in the embodiment. Note that, in the embodiment, an upstream side from the head unit  3  in the transport direction in the first direction X is referred to as the X 1  side, and a downstream side is referred to as an X 2  side. 
     The first transport unit  5  includes a first transport roller  501  and a first driven roller  502  that is driven by following the first transport roller  501 . The first transport roller  501  is provided on a side opposite to the surface of the recording sheet S on which the ink lands, that is, on the Z 1  side, and is driven by a drive force from the first drive motor  503 . In addition, the first driven roller  502  is provided on the surface side of the recording sheet S on which the ink lands, that is, on the Z 2  side, and the recording sheet S is nipped between the first transport roller  501  and the first driven roller  502 . The first driven roller  502  presses the recording sheet S toward the first transport roller  501  with a bias member such as a spring not illustrated. 
     The second transport unit  6  includes a transport belt  601 , a second drive motor  602 , a second transport roller  603 , a second driven roller  604 , a tension roller  605 , and a pressing roller  607 . 
     The second transport roller  603  of the second transport unit  6  is driven by a drive force from the second drive motor  602 . The transport belt  601  is formed of an endless belt and loops around outer circumferences of the second transport roller  603  and the second driven roller  604 . The transport belt  601  is provided on the Z 1  side of the recording sheet S. The tension roller  605  is provided between the second transport roller  603  and the second driven roller  604 , comes into contact with an inner circumferential surface of the transport belt  601 , and applies tension to the transport belt  601  due to a bias force from a bias member  606  such as a spring. In this manner, the transport belt  601  is disposed between the second transport roller  603  and the second driven roller  604  so as to have a flat surface facing the head unit  3 . 
     The pressing rollers  607  of the second transport unit  6  are provided on the X 1  side and the X 2  side of the head unit  3 , respectively, on the Z 2  side of the recording sheet S. The recording sheet S is interposed between the two pressing rollers  607  and the transport belt  601 , and thereby a flat posture of the recording sheet S is maintained. 
     In the ink jet type recording apparatus  1 , while the first transport unit  5  and the second transport unit  6  transport the recording sheet S with respect to the head unit  3  from the X 1  side to the X 2  side in the first direction X, the ink is caused to be ejected from the recording heads  100  of the head unit  3 , the ejected ink is caused to land on a surface of the recording sheet S on the Z 2  side, and so-called printing is performed. 
     Here, the head unit  3  that is mounted in the ink jet type recording apparatus  1  is more described in detail with reference to  FIGS. 3 to 7 .  FIG. 3  is an exploded perspective view illustrating a part of the ink jet type recording head unit as an example of a liquid ejecting head unit according to Embodiment 1 of the invention.  FIG. 4  is an underside view illustrating the head unit.  FIG. 5  is a sectional view taken along line V-V in  FIG. 4 .  FIG. 6  is an enlarged view illustrating a main part in  FIG. 5 .  FIG. 7  is a sectional view taken along line VII-VII in  FIG. 4 . In addition, in the embodiment, the directions of the head unit  3  are described, based on directions obtained when the head unit is mounted in the ink jet type recording apparatus  1 , that is, the first direction X, the second direction Y, and the third direction Z. 
     As illustrated in  FIGS. 3 to 7 , the head unit  3  of the embodiment includes the plurality of recording heads  100 , the unit base  200  that holds the plurality of recording heads  100 , and a spacer  300  provided between the unit base  200  and the recording head  100 . 
     As illustrated in  FIGS. 4 and 5 , the recording head  100  includes a nozzle-formed surface  102  having nozzle openings  101  in the surface on the Z 1  side. The nozzle openings  101  are fixed such that a nozzle array is inclined with respect to the first direction X in the in-plane direction of the nozzle-formed surface  102 . In other words, an alignment direction of the nozzle openings  101  that form the nozzle array is referred to as a fourth direction Xa inclined with respect to the first direction X. In addition, a plurality of nozzle arrays are provided side by side on the nozzle-formed surface  102  in the second direction Y. 
     In addition, the recording head  100  has a substantially parallelogramic shape in the second direction Y and the fourth direction Xa, in a plan view from the nozzle-formed surface  102  side. It is needless to say that the shape of the recording head  100  is not limited to the substantially parallelogram; however, the recording head may have a rectangular shape, a trapezoidal shape, a polygonal shape, or the like, in a plan view from the nozzle-formed surface  102  side. 
     Further, the plurality of recording heads  100  are aligned in the second direction Y orthogonal to the first direction X as the transport direction of the recording sheet S, and are fixed to the unit base  200 . Note that, in the embodiment, the plurality of recording heads  100  are aligned in the second direction Y, that is, are aligned in a straight line in the second direction Y. In other words, the plurality of recording heads  100  are not disposed to be shifted from one another in the first direction X. In this manner, it is possible to decrease a width of the head unit  3  in the first direction X, and thus it is possible to decrease the head unit  3  in size. Note that, in the embodiment, the recording heads  100  are aligned in the second direction Y, and thereby the head unit  3  has an elongated length in the second direction Y, and has a short length in the first direction X. In other words, the head unit  3  has a longitudinal direction in the second direction Y and has a short direction in the first direction X. 
     The recording head  100  is configured to include a plurality of members which are stacked. Specifically, as illustrated in  FIGS. 3 and 5 , in the embodiment, the recording head  100  includes a plurality of head main bodies  110  provided with the plurality of nozzle openings  101  from which ink droplets are discharged, holding members  120  that hold the plurality of head main bodies  110 , and covers  130  as fixing plates provided on the Z 1  side of the head main bodies  110 . The head main body  110 , the holding member  120 , and the cover  130  are stacked in the third direction Z. In the embodiment, in the recording head  100 , a surface on the Z 1  side is referred to as the nozzle-formed surface  102 . 
     In addition, the holding member  120  includes a flow-path member  121 , a holder  122 , and a wiring substrate  123  held between the flow-path member  121  and the holder  122 . The wiring substrate  123  is provided to be exposed on a stack interface between the flow-path member  121  and the holder  122 . In addition, a cable  126  connected to the wiring substrate  123  is guided out through a surface of the recording head  100  on the Z 2  side. 
     The plurality of recording heads  100  are fixed to the unit base  200 . In the embodiment, six recording heads  100  are fixed to unit base  200  via the spacer  300 . 
     The spacer  300  includes a first fixing portion  301  and a second fixing portion  302  which is thicker than the first fixing portion  301  in the third direction Z. 
     The first fixing portion  301  is provided with a first insertion hole  304  that penetrates therethrough in the third direction Z. In addition, the recording head  100  is provided with a first fixing hole  103 . A first screw member  401  as a male screw is inserted into the first insertion hole  304  from the Z 2  side of the first fixing portion  301  and the first screw member  401  is screwed with the first fixing hole  103  of the recording head  100 , and thereby the spacer  300  is fixed to the surface of the recording head  100  on the Z 2  side. 
     The spacer  300  is disposed at a position which is placed within the outer shape of the recording head  100  in the second direction Y as an alignment direction of the recording heads  100 , in a plan view of the nozzle-formed surface  102 . In other words, the spacer  300  is disposed at a position which does not project from the outer shape of the recording head  100  in the second direction Y, when viewed in the third direction Z. Note that the outer shape of the recording head  100  means portions of the recording head  100  which project to the largest extent in the first direction X and the second direction Y. 
     When the recording head  100  is viewed in the third direction Z, the spacer  300  is disposed at a position which does not project from a side surface of the recording head  100  in the second direction Y, and thereby it is possible to decrease a gap between the recording heads  100  which are adjacent to each other in the second direction Y. In this manner, the head main bodies  110  of the recording heads  100 , which are adjacent to each other in the second direction Y, can be provided to approach each other, and the nozzle openings  101  provided in the head main bodies  110  of the adjacent recording heads  100  can be provided to approach each other in the second direction Y. As a result, it is possible to continuously form the heads of the head unit  3 , which are aligned at equal intervals in the second direction Y. 
     In addition, in the embodiment, the spacer  300  is disposed at a position which is placed within the outer shape of the recording head  100  on the nozzle-formed surface  102  side in a relative moving direction of the recording sheet S with respect to the head unit  3 , that is, in the first direction X as a transport direction of the recording sheet S, in a plan view of the nozzle-formed surface  102 . In this manner, it is possible to decrease the width of the head unit  3  in the first direction X, and it is possible to decrease a distance between the two pressing rollers  607  in the first direction X in the ink jet type recording apparatus  1 . Hence, it is possible to decrease a space between the two pressing rollers  607  in the first direction X, and thus it is easy to fix the posture of the recording sheet S between the two pressing rollers  607  such that it is possible to improve print quality. In addition, it is possible to decrease the head unit  3  and the ink jet type recording apparatus  1  in size. 
     The spacer  300  is detachably fixed in a state in which the second fixing portion  302  is in contact with a surface of the unit base  200  on the Z 1  side as the recording sheet S side. Specifically, the second fixing portion  302  of the spacer  300  is provided with a second fixing hole  306  that opens to the unit base  200  side. In addition, the unit base  200  is provided with a second insertion hole  202 . A second screw member  402  as a male screw is inserted into the second insertion hole from the Z 2  side of the unit base  200  and the second screw member  402  is screwed into the second fixing hole  306  of the spacer  300 , and thereby the spacer  300  is fixed in a state of being in contact with a surface of the unit base  200  on the Z 1  side. In other words, the spacer  300  is detachably fixed by being screwed with the second screw member  402  from the Z 2  side of the unit base  200 . The spacer  300  of the embodiment is released from the screwing with the second screw member  402 , and thereby it is possible to detach the spacer  300  from the unit base  200  at a desirable timing. 
     As described above, the spacer  300  fixed to the recording head  100  is detachably provided in the unit base  200 , and thereby it is possible to easily attach or detach the recording head  100  to and from the unit base  200 . In this manner, when the plurality of recording heads  100  provided in the head unit  3  malfunction, it is possible to selectively replace only the malfunctioning recording head  100 . In other words, since there is no need to replace the entire head unit  3  in response to the malfunction of one recording head  100 , it is possible to decrease costs. In addition, also during assembly of the head unit  3 , it is possible to selectively replace a recording head  100  which does not have the same ejection characteristics of ink droplets, and thus, it is possible to increase a yield ratio. 
     In addition, in the embodiment, the first screw member  401 , which fixes the recording head  100  and the spacer  300 , and the second screw member  402 , which fixes the unit base  200  and the spacer  300 , are detachably fixed by being screwed from a side opposite to the nozzle-formed surface  102  of the recording head  100 . Hence, it is possible to decrease an occurrence of a problem arising in that an ink attached to the first screw member  401  or the second screw member  402  drops down on the recording sheet S or the like at an unexpected timing. In addition, the first screw member  401  and the second screw member  402  have the same direction of screwing, and thus are screwed with good workability. 
     Note that, in the embodiment, one recording head  100  is provided with four spacers  300 . Specifically, the spacers  300  are provided on four corners of a surface of the recording head  100 , respectively, in the first direction X and the second direction Y. 
     In addition, a plurality of types of spacers  300 , which have different thicknesses, can be used and can adjust relative heights of the plurality of recording heads  100  in the third direction Z, and thereby it is possible to easily adjust to have the same heights and inclinations of the nozzle-formed surface  102  of the plurality of recording heads  100 . In particular, in the embodiment, the spacer  300  is attachable to and detachable from the recording head  100 , and thereby it is possible to easily perform replacement with the spacer  300  having a different thickness. Hence, it is possible to decrease a shift of a landing position of ink droplets which are ejected from the recording heads  100  such that it is possible to improve the print quality. 
     The unit base  200 , to which the recording heads  100  are fixed via the spacers  300 , is more described with reference to  FIGS. 8 to 10 .  FIG. 8  is a perspective view illustrating the unit base  200  when viewed from an underside of the unit base.  FIG. 9  is a top view illustrating the unit base.  FIG. 10  is an underside view illustrating the unit base. 
     As illustrated in  FIGS. 8 to 10 , the unit base  200  includes a bottom portion  210 , and a wall portion  230  provided on the Z 1  side of the bottom portion  210 . For example, it is possible to form the unit base  200  through cutting work or molding, using metal such as an aluminum alloy or a resin. 
     The bottom portion  210  has a plate shape with a plane direction including a first direction X and the second direction Y, and includes fixing portions  211  provided on both sides in the first direction X and a thick portion  212  that is provided between the fixing portions  211  and is thicker than the fixing portion  211 . The two fixing portions  211  and the thick portion  212  interposed between the two fixing portions  211  are provided to be continuous in the second direction Y. In addition, the fixing portions  211  and the thick portion  212  are integrally provided. 
     The fixing portion  211  includes a fixing surface  213  having a surface of the fixing surface on the Z 1  side, to which the recording head  100  is fixed via the spacer  300 . Note that, in the embodiment, a surface of the bottom portion  210 , which is opposite to the fixing surface  213  to which the recording head  100  is fixed, that is, a surface on the Z 2  side, is referred to as a supply surface  214 . 
     The fixing portion  211  of the bottom portion  210  is provided with the second insertion hole  202  that penetrates therethrough in the third direction Z. The second screw member  402  inserted into the second insertion hole  202  from the supply surface  214  side is screwed as described above, and thereby the spacer  300  fixed to the recording head  100  is fixed to the fixing surface  213 . Note that, as described above, one recording head  100  is provided with four spacers  300 . In other words, the recording head  100  is fixed at total of four positions of two positions in the fixing portions  211 , respectively, which are disposed to interpose the thick portion  212  in the first direction X. In other words, the recording head  100  are fixed to unit base  200  at a plurality of positions in the first direction X as a short direction of the unit base. As described above, the recording head  100  is fixed to the unit base  200  at the plurality of positions in the first direction X, and thereby it is possible to increase the stiffness of the unit base  200  in the short direction, with the recording head  100  fixed to the unit base  200 . In addition, it is preferable that the fixing surfaces  213  in the unit base  200 , to which the spacers  300  fixing both ends of the recording head  100  the first direction X as the short direction of the unit base  200  are fixed, be disposed in both end regions in a case where the bottom portion  210  is divided into four regions in the first direction X as the short direction. As described above, the fixing surfaces  213 , to which the spacers  300  are fixed, are provided in both end portions of the bottom portion  210  in the short direction, and thereby it is possible to increase the stiffness of the unit base  200  in the short direction, with the recording head  100  fixed to the unit base. 
     In addition, the thick portion  212  of the bottom portion  210  is provided with a supply hole  215  that penetrates therethrough in the third direction Z. A flow path of the recording head  100  fixed to the bottom portion  210  is exposed through the supply hole  215  in the supply surface  214  side and the exposed flow path through the supply hole  215  is connected with the supply tube  4   a  such as a tube from the supply surface  214  side (refer to  FIG. 1 ). In other words, inks are supplied to the recording head  100  from the supply surface  214  side. Note that, in the embodiment, the supply tube  4   a  is directly connected to the recording head  100  from the supply surface  214  side of the bottom portion  210 ; however, the configuration is not particularly limited thereto, and another flow-path member may be provided on the supply surface  214  side of the bottom portion  210 , the supply tube  4   a  may be connected to the other flow-path member, and the ink may be supplied to the recording head  100  from the supply tube  4   a  via the other flow-path member. In the embodiment, the supply hole  215  is provided in the thick portion  212 , and thereby it is possible to prevent a significant decrease in the stiffness of the bottom portion  210 , and thus it is possible to secure the stiffness of the bottom portion  210 . In other words, in a case where the supply hole  215  is provided in the fixing portion  211 , the stiffness of a portion of the fixing portion  211 , in which the supply hole  215  is provided, is significantly decreased because the fixing portion  211  is thinner than the thick portion  212 . 
     Since the plurality of recording heads  100  are aligned in the second direction Y and are fixed to the bottom portion  210 , the bottom portion  210  has a long length (a longitudinal direction) in the second direction Y, and the bottom portion  210  has a short length (a short direction) in the first direction X. The bottom portion  210  is provided with the thick portion  212 , and thereby it is possible to increase the stiffness of the bottom portion  210 . In particular, since the bottom portion  210  has the long length in the second direction Y, the thick portion  212  is provided in the second direction Y, and thereby it is possible to increase the stiffness in the longitudinal direction in which the stiffness is likely to be decreased. 
     The wall portion  230  includes two first wall portions  231  provided to be continuous in the second direction Y as the alignment direction of the recording heads  100 , and two second wall portions  232  that connects the two first wall portions  231  to each other. In other words, the wall portion  230  has a ring shape in which the two first wall portions  231  and the two second wall portions  232  are formed to be a continuous wall. 
     Specifically, the first wall portions  231  are formed of a plate-like member and are provided to be upright in both end portions of the bottom portion  210  in the first direction X, respectively, so as to extend from the bottom portion  210  on the Z 1  side in a direction perpendicular to the fixing surface  213 , that is, the third direction Z. In addition, the first wall portion  231  is provided to be continuous in the second direction Y as the alignment direction of the recording heads  100 . In other words, the first wall portion  231  is formed of the plate-like member and is disposed so as to have a front surface that is formed in directions including the second direction Y and the third direction Z. 
     The second wall portions  232  are provided to be upright in both end portions of the bottom portion  210  in the second direction Y, respectively, so as to extend from the bottom portion on the Z 1  side in a direction perpendicular to the fixing surface  213 , that is, the third direction Z. In addition, the second wall portion  232  is provided to be continuous in an inclined direction with respect to the first direction X, that is, in the fourth direction Xa as the alignment direction of the nozzle openings  101  of the recording heads  100  in the embodiment. In other words, the second wall portion  232  is formed of a plate-like member and is disposed so as to have a front surface that is formed in directions including the fourth direction Xa and the third direction Z. 
     In addition, end portions of the first wall portions  231  and the second wall portions  232  are connected to each other. In the embodiment, the first wall portions  231  and the second wall portions  232  are integrally provided to be a continuous wall. Hence, the wall portion  230  is formed to have a ring shape surrounding the plurality of recording heads  100  by the two first wall portions  231  and the two second wall portions  232 . 
     The ring-shaped wall portion  230  makes it possible to increase the stiffness of the unit base  200  have an increase in stiffness. In other words, the first wall portion  231  makes it possible to increase the stiffness of the unit base against the bending moment in the second direction Y, compared to a case where only the bottom portion  210  is provided as the unit base  200 . In other words, the second wall portion  232  makes it possible to increase the stiffness of the bottom portion  210  against the bending moment in the first direction X. The first wall portion  231  and the second wall portion  232  make it possible to increase the stiffness of the unit base against the torsional moment. In the embodiment, the wall portion  230  has the ring shape with the first wall portions  231  and the second wall portions  232  formed as a continuous wall, and thereby it is possible to increase the stiffness against the bending moment in the first direction X and the second direction Y, and to increase the stiffness against the torsional moment. Hence, even when a load is increased, with a cap coming into contact with the nozzle-formed surface  102  of the head unit  3 , it is possible to decrease deformation of the unit base  200 . Since it is possible to decrease the deformation of the unit base  200 , it is possible to increase the load produced when the cap comes into contact with the nozzle-formed surface  102 . Then, it is possible to increase sealing performance between the cap and the nozzle-formed surface  102  such that it is possible to reliably perform a suction operation via the cap. In addition, it is possible to increase the load produced when the cap comes into contact with the nozzle-formed surface  102 , and then it is possible to increase the sealing performance between the cap and the nozzle-formed surface such that it is possible to decrease an amount of inks evaporating from the nozzle openings  101 . Further, even when the head unit  3  holds the plurality of recording heads  100  and thus a weight of the head unit is increased, it is possible to increase the stiffness of the unit base  200  such that it is possible to decrease deformation or damage to the unit base due to the own weight. 
     In addition, in the embodiment, since the recording heads  100  are arranged in a row in the second direction Y, the unit base  200  is likely to be long in the second direction Y with a high aspect ratio. However, the wall portion  230 , which is continuous in the alignment direction of the recording heads  100  on the unit base  200 , particularly the first wall portion  231 , makes it possible to increase the stiffness of the unit base  200  in the longitudinal direction in which the unit base is likely to be deformed. 
     Further, in the embodiment, as described above, since the spacer  300  fixed to the recording head  100  is fixed to be screwed into the unit base  200  from the side opposite to the fixing surface  213  on the Z 1  side, the spacer  300  does not project on the nozzle-formed surface  102  of the recording head  100  in the second direction Y, and thus it is possible to dispose the spacer  300  within the outer shape of the recording head  100  in the second direction Y. Hence, it is possible to decrease the interval between the recording heads  100  which are aligned in the second direction Y and are adjacent to each other, and it is possible to decrease the width of the unit base  200  in the first direction X. The decrease in the width of the head unit  3  in the first direction X makes it possible to increase the stiffness of the unit base  200 . 
     In addition, since the wall portion  230  provided in the unit base  200  makes it possible to increase the stiffness of the bottom portion  210 , there is no need to increase the thickness of the bottom portion  210  and it is possible to less increase the weight of the unit base  200  such that it is possible to decrease the deformation due to the own weight and it is possible to decrease the size. Incidentally, in a case where the wall portion  230  is not provided in the unit base  200  and only the bottom portion  210  is provided, the thickness has to be increased in the third direction Z such that the stiffness of the bottom portion  210  is increased, then, the own weight is likely to be increased and the size is likely to be increased. In the embodiment, the wall portion  230  is provided in the unit base  200 , and thereby it is possible to increase the stiffness of the unit base  200  and to decrease the weight and the size. 
     The unit base  200  is provided with a cable opening  201  into which the cable  126  of the recording head  100  is inserted. In the embodiment, the cable opening  201  is provided over a boundary between the bottom portion  210  and the wall portion  230 . The cable  126  of the recording head  100 , which is fixed to the unit base  200 , is guided out to the supply surface  214  side via the cable opening  201 . 
     In addition, a third wall portion  233  that projects outward, that is, in the first direction X, is provided on an end portion of the first wall portion  231  on the Z 1  side. The third wall portion  233  is provided on the end portion of the first wall portion  231  on the Z 1  side, and thereby a step  234  is formed on the outer side of the first wall portion  231 . A relay substrate  400  is accommodated in the step  234  provided on the outer side of the first wall portion  231 . Here, the relay substrate  400  is formed of a rigid substrate and is fixed in the step  234  by using a screw or the like. A plurality of cables  126  guided out through the cable opening  201  of the unit base  200  to the supply surface  214  side are connected to the relay substrate  400 . As described above, the cables  126  of the plurality of the recording heads  100  are inserted into the cable openings  201 , which open to the supply surface  214  of the unit base  200 , and are connected to the common relay substrate  400 , ink mists are difficult to infiltrate to the nozzle-formed surface  102  side through the cable openings  201 , and it is possible to decrease an amount of inks attached to the cables  126 , the wiring substrates  123  of the recording heads  100 , or the like. 
     In addition, in the embodiment, the step  234  is provided by the third wall portion  233  on the outer side of the first wall portion  231  such that the relay substrate  400  is accommodated in the step  234 . Therefore, the relay substrate  400  is less exposed on the Z 1  side such that it is possible to decrease an amount of ink mists or the like attached to the relay substrate  400  from the nozzle-formed surface  102  side. In other words, the third wall portion  233  covers the Z 1  side of the relay substrate  400 , and thereby the inks are unlikely to be attached to the relay substrate  400 . 
     Further, it is preferable that the relay substrate  400  have a size in the third direction Z which is larger than the height of the step  234  in the third direction Z. In this manner, a portion of the cable opening  201 , which opens to the first wall portion  231 , that is, an opening in the first direction X, is blocked with the relay substrate  400 . Hence, the relay substrate  400  makes it possible to decrease an amount of the inks infiltrated through the cable openings  201 . It is needless to say that the step  234 , in which the relay substrate  400  is accommodated, is covered with a lid member or the like, and thereby it is possible to decrease the amount of the inks attached to the relay substrate  400 . However, there is a concern that the step  234  will be covered with the lid member, and thereby the head unit  3  is likely to be increased in size in the first direction X. In the embodiment, the relay substrate  400  is not covered and is exposed in the first direction X, and thereby it is possible to decrease the head unit  3  in size in the first direction X. 
     As described above, the recording heads  100  are fixed to the unit base  200  via the spacers  300 . Here, a head-side fixing surface of the recording head  100 , which is fixed to the unit base  200  via the spacers  300 , is positioned on the Z 2  side opposite to the Z 1  side on which the nozzle-formed surface  102  is provided. In this manner, it is possible to decrease the unit base  200  in size in the first direction X such that it is possible to increase the stiffness against torsion. Incidentally, in a case where the head-side fixing surface is provided on the nozzle-formed surface  102 , there is a need to provide a flange or the like having the head-side fixing surface on the nozzle-formed surface  102  side, and there is a need to provide a region in the unit base  200  to which the flange is fixed. Then, the unit base  200  is likely to be increased in size. In particular, in the embodiment, since the plurality of recording heads  100  need to be provided to approach each other in the second direction Y, the region of the unit base  200 , to which the flange is fixed, needs to be provided on both sides of the recording head  100  in the first direction X, then, the unit base  200  is likely to be increased in size in the first direction X and the stiffness thereof against the torsion is likely to be decreased. 
     In addition, in the embodiment, the recording heads  100  are fixed to the surface of the unit base  200  on the Z 1  side, thereby it is possible to decrease the unit base  200  in size and it is possible to increase the stiffness of the unit base  200 . Incidentally, in a case where the recording heads  100  are fixed on the surface of the unit base  200  on the Z 2  side, there is a need to provide, in the unit base  200 , openings for exposing the nozzle opening  101  side of the recording heads  100  on the Z 1  side and approaching the nozzle openings  101  to the recording sheet S, a region for fixing the recording head  100 , or the like, and thus the unit base is increased in size. In particular, in the embodiment, since the plurality of recording heads  100  need to be provided to approach each other in the second direction Y, the region of the unit base  200 , to which the recording heads  100  are fixed, needs to be disposed on both sides of the recording head  100  in the first direction X, then, the unit base  200  is likely to be increased in size in the first direction X and the stiffness thereof against the torsion is likely to be decreased. 
     In addition, in the embodiment, the wall portion  230  is provided on the bottom portion  210  on the Z 1  side on which the recording heads  100  are fixed, and thereby it is possible to decrease the head unit  3  in size in the third direction Z. Incidentally, the recording heads  100  may be provided on the unit base  200  on the Z 1  side and the wall portion  230  may be provided on the unit base  200  on the Z 2  side; however, the head unit  3  is increased in size in the third direction Z. 
     Further, in the embodiment, the wall portion  230  and the recording heads  100  are provided on the bottom portion  210  on the same Z 1  side, and the wall portion  230  covers principal side surfaces of the recording heads  100 . In this manner, it is possible to decrease an occurrence of a state in which the recording head  100  comes into contact with another member during work such as attaching the head unit  3  to the ink jet type recording apparatus  1 , or the like. In addition, it is possible to decrease an occurrence of a case in which the recording sheet S comes into contact with the recording head  100  due to a paper jam or the like. Hence, it is possible to decrease an occurrence of a case where another member comes into contact with the recording head  100  such that it is possible to decrease damage to the recording head  100 . 
     Note that it is preferable that the wall portion  230  be formed to have a size such that the wall portion covers interfaces of the members stacked to configure the recording head  100  in the third direction Z. In the embodiment, as illustrated in  FIG. 3  or the like, the holding member  120  that configures the recording head  100  includes the flow-path member  121 , the holder  122 , and the wiring substrate  123  held between the flow-path member  121  and the holder  122 . As illustrated in  FIG. 7 , the wiring substrate  123  is provided to be exposed on the stack interface between the flow-path member  121  and the holder  122 . Therefore, the wall portion  230  covers the interface on which the wiring substrate  123  is exposed, that is, the stack interface between the flow-path member  121  and the holder  122 , and thereby it is possible to decrease an amount of inks attached to the wiring substrate  123 . The wiring substrate  123  may be provided not to be exposed on the interface formed between the flow-path member  121  and the holder  122  which are stacked. In other words, the interface between the members, which are stacked to configure the recording head  100 , is not limited to the interface on which the wiring substrate  123  is exposed, but may be an interface on which adhesion is performed by using an adhesive or the like. The interface, on which the adhesion is performed by using the adhesive, is covered with the wall portion  230 , thereby it is possible to decrease an occurrence of erosion of the adhesive by the ink such that it is possible to less decrease the strength of the adhesion. It is needless to say that the adhesive may not be provided on the interface between the members stacked to configure the recording head  100 . The interface is covered with the wall portion  230  in any case, and thereby it is possible to decrease an amount of inks infiltrated in the recording head  100  from the interface. Incidentally, in the embodiment, the wall portion  230  is provided to have a size so as to approach the nozzle-formed surface  102 . However, since the nozzle-formed surface  102  needs to be wiped with a wiper and to have a small distance to the recording sheet S, that is, a so-called paper gap, it is preferable that the nozzle-formed surface  102  side of the recording head  100  more project to the Z 1  side than the wall portion  230 . 
     In addition, the plurality of recording heads  100  are held in the unit base  200 , and thereby it is possible to increase the yield ratio, compared to a case where a plurality of nozzle arrays are provided in the recording head  100  and multiple arrays are formed. However, the plurality of recording heads  100  are held in the unit base  200 , and thereby the weight of all of the plurality of recording heads  100  is likely to be increased; however, the wall portion  230  is provided on the unit base  200 , and thereby the stiffness of the unit base is increased such that it is possible to decrease the deformation due to the weight of the recording heads  100 . 
     Note that, since the unit base  200  of the embodiment holds the plurality of recording heads  100  which are aligned in the second direction Y, the bottom portion  210  is short in the first direction X, is long in the second direction Y, and has a substantially rectangular shape. In this respect, the second wall portion  232  of the wall portion  230  is provided in the fourth direction Xa which is inclined with respect to the first direction X. Therefore, the bottom portion  210  has a first overhang  217  and a second overhang  218  that overhang outward from both end portions in the second direction Y, respectively, more than the wall portion  230 , so as to have an eave shape. In other words, the bottom portion  210  has the first overhang  217  that more overhangs outward than the second wall portion  232  on the Y 1  side of the second direction Y, and the second overhang  218  that more overhangs outward than the second wall portion  232  on the Y 2  side of the second direction Y. 
     The first overhang  217  is provided with a first through-hole  219  that penetrates therethrough in the third direction Z as a lifting-lowering direction of the head unit  3 . A first shaft  9   a  having the axial direction thereof in the third direction Z is inserted into the first through-hole  219 . In addition, a first bearing  220  is provided in the first through-hole  219 , so as to be in contact with an outer circumferential surface of the first shaft  9   a  and to receive the load of the shaft. 
     In addition, the second overhang  218  is provided with a cylindrical projecting portion  221  that projects to the supply surface  214  side and more toward the Z 2  side. A second through-hole  222 , which penetrates through the projecting portion  221  and the second overhang  218  in the third direction Z, is provided inside the projecting portion  221 , and a second shaft  9   b  having the axial direction thereof in the third direction Z is inserted into the second through-hole  222 . In addition, a second bearing  223  and a third bearing  224  are provided in an opening of the second through-hole  222  on the Z 1  side and an opening thereof on the Z 2  side, respectively, so as to be in contact with an outer circumferential surface of the second shaft  9   b  and to receive the load of the shaft. In other words, the second bearing  223  is provided in the opening of the second through-hole  222  on the Z 2  side and the third bearing  224  is provided in the opening thereof on the Z 1  side. In addition, the second bearing  223  and the third bearing  224  are separately provided in the second through-hole  222 . In the second through-hole  222 , the load of the second shaft  9   b  is received at two positions of the two second bearing  223  and third bearing  224  provided at positions separated in the third direction Z. In other words, in the embodiment, the unit base  200  is supported by the two first and second shafts  9   a  and  9   b  provided in the apparatus main body  2 , at total three positions of the first bearing  220 , the second bearing  223 , and the third bearing  224 . 
     In the embodiment, the first bearing  220 , the second bearing  223 , and the third bearing  224  are disposed at positions which are overlapped by the recording heads  100  in the second direction Y as the alignment direction of the recording heads  100 . In this manner, it is possible to decrease the unit base  200  in size in the first direction X. In addition, since the two first and second shafts  9   a  and  9   b  can support both end portions of the unit base  200  in the second direction Y as the longitudinal direction of the unit base  200 , it is possible to decrease a tilt of the unit base  200  with respect to the third direction Z as the axial direction of the first shaft  9   a  and the second shaft  9   b . Incidentally, in order to dispose the first bearing  220 , the second bearing  223 , and the third bearing  224  at positions which are overlapped with the recording heads  100  in the first direction X, the unit base  200  needs to be provided with a space for the first through-hole  219  and the second through-hole  222 , and thus the unit base  200  is likely to be increased in size in the first direction X. In particular, since a first contact surface  225  and a second contact surface  227 , which will be described in detail below, are provided in the unit base  200  of the embodiment in the first direction X, the first contact surface  225  and the second contact surface  227  interfere with the first through-hole  219  and the second through-hole  222 . Thus, the unit base is easy to be increased in size in the first direction X. In addition, since the unit base  200  has the center of gravity at a position shifted in the first direction X with respect to the two first and second shafts  9   a  and  9   b , the unit base  200  is likely to tilt with respect to the first shaft  9   a  and the second shaft  9   b . In the embodiment, since the first through-hole  219  and the second through-hole  222  are provided in the first overhang  217  and the second overhang  218  of the bottom portion  210 , which are formed by the wall portion  230 , there is no need to provide a new space to provide the first through-hole  219  and the second through-hole  222  such that it is possible to decrease the unit base in size not only in the first direction X, but also in the second direction Y. In addition, since it is possible to dispose the center of gravity of the head unit  3  at a position between or closer to a portion between the two first and second shafts  9   a  and  9   b , the unit base  200  is unlikely to tilt with respect to the first shaft  9   a  and the second shaft  9   b.    
     In addition, the projecting portion  221 , which more projects than the bottom portion  210 , is provided, the second bearing  223  and the third bearing  224  are provided in the second through-hole  222  of the projecting portion  221 , and thereby it is possible to dispose the second bearing  223  and the third bearing  224  at positions which are separated from each other in the third direction Z. Therefore, the bottom portion  210  does not need to have any region which is thick in the third direction Z, and thus it is possible to less increase the weight of the unit base  200 . 
     Note that, in the embodiment, the positioning is performed by the three portions of the first bearing  220 , the second bearing  223 , and the third bearing  224  with respect to the two shafts of the first shaft  9   a  and the second shaft  9   b . In other words, the positioning is performed by one portion of the first bearing  220  with respect to the first shaft  9   a  and by two portions of the second bearing  223  and the third bearing  224  with respect to the second shaft  9   b , and thereby it is possible to decrease a tilt of the unit base  200  with respect to the first shaft  9   a  and the second shaft  9   b , particularly a tilt in a direction in which the unit base rotates toward the first direction X; however, the number of bearings is not limited to three as long as the first shaft  9   a  and the second shaft  9   b  as the two shafts are positioned by three or more bearings. For example, a configuration, in which total four bearings are provided with respect to the two first and second shafts  9   a  and  9   b  which are provided two bearings, respectively, may be employed. However, it is difficult to adjust a clearance, a tilt, or the like of the first shaft  9   a  and the second shaft  9   b  in the four bearings, and thus there is a concern that a bias in the clearance of the bearings with the first shaft  9   a  and the second shaft  9   b  will occur and the head unit  3  will be difficult to move in the third direction Z. In the embodiment, the three bearings of the first bearing  220 , the second bearing  223 , and the third bearing  224  are provided with respect to the two shafts of the first shaft  9   a  and the second shaft  9   b , thereby it is possible to easily adjust a clearance between the first shaft  9   a  and the first bearing  220  and clearances between the second shaft  9   b  and the second bearing  223  an the third bearing  224 , and it is possible to cause the head unit  3  to smoothly move with respect to the first shaft  9   a  and the second shaft  9   b  in the third direction Z. In addition, three or more bearings may be provided with respect to one shaft; however, similarly, it is difficult to relatively position the three or more bearings, and the head unit  3  is difficult to smoothly move with respect to the shaft. 
     Further, the first overhang  217  is provided with a first contact portion  226  having the first contact surface  225  on the Z 1  side. The first contact portion  226  has a side wall  226   b  provided to project from the first overhang  217  toward Z 2 , and a first eave portion  226   a  that projects to have an eave shape from a projecting end portion of the side wall  226   b  on the Z 2  side toward the X 1  side. A surface of the first eave portion  226   a  on the Z 1  side is the first contact surface  225 . In other words, the first contact portion  226  is provided with the first eave portion  226   a  on the end portion of the side wall  226   b  on the Z 2  side, and thereby it is possible to dispose the first contact surface  225  at a position more separated from the nozzle-formed surface  102  of the head unit  3  on the Z 2  side. 
     In addition, the first contact portion  226  is provided with a first rib  226   c  and a second rib  226   d  that reinforce the fixing to the bottom portion  210 . The first rib  226   c  and the second rib  226   d  are formed of a plate-like member connected to a surface of the side wall  226   b  on the X 2  side and to the supply surface  214  of the bottom portion  210 . The first contact portion  226  is reinforced with the first rib  226   c  and the second rib  226   d.    
     The first contact portion  226  is integrally formed with the unit base  200 . The first contact portion  226  is integrally formed with the unit base  200 , and thereby the stiffness of the first contact portion  226 , particularly, the stiffness of the first eave portion  226   a , is increased. 
     The second overhang  218  is provided with a second contact portion  228  having the second contact surface  227  on the Z 1  side. The second contact portion  228  is provided with a second eave portion  228   a  provided to be continuous from an outer circumference of the projecting portion  221  at a position separated from the supply surface  214  on the Z 2  side and to project to have an eave shape toward the X 1  side. Incidentally, the projecting portion  221  is provided to more project than the second eave portion  228   a  on the Z 2  side. A surface of the second eave portion  228   a  on the Z 1  side is the second contact surface  227 . 
     In addition, the second contact portion  228  has a reinforcement portion  228   b  provided between the second eave portion  228   a , the outer circumferential surface of the projecting portion  221 , and the supply surface  214  of the bottom portion  210 . The second eave portion  228   a  is reinforced by the reinforcement portion  228   b.    
     In addition, in the embodiment, the second contact portion  228  and the projecting portion  221  are integrally formed with the unit base  200 . The second contact portion  228  and the projecting portion  221  are integrally formed with the unit base  200 , and thereby the stiffness of the second contact portion  228  and the projecting portion  221 , particularly, the stiffness of the second eave portion  228   a , is increased. 
     A lifting-lowering mechanism is caused to come into contact with both of the first contact surface  225  of the first contact portion  226  and the second contact surface  227  of the second contact portion  228 , such that the lifting-lowering mechanism presses the first contact surface  225  and the second contact surface  227  in the third direction X, and thereby it is possible to lift and lower the head unit  3  along the first shaft  9   a  and the second shaft  9   b  in the third direction Z. 
     Here, a lifting-lowering mechanism  10  of the embodiment is further described with reference to  FIGS. 11 to 14 .  FIGS. 11 and 13  are front views of the ink jet type recording apparatus to which the lifting-lowering mechanism is applied.  FIGS. 12 and 14  are side views of the ink jet type recording apparatus to which the lifting-lowering mechanism is applied. 
     As illustrated in  FIGS. 11 to 14 , the lifting-lowering mechanism  10  includes a rotary shaft  11 , which is rotatably held in the apparatus main body  2 , two eccentric cams  12  fixed to the rotary shaft  11 , and a drive unit  13  such as a motor which drives and rotates the rotary shaft  11  around the axial direction. 
     The eccentric cams  12  are disposed on the first contact surface  225  and the second contact surface  227  on the Z 1  side, respectively, and the first contact surface  225  and the second contact surface  227  are in contact with the two eccentric cams  12  in the third direction Z due to the own weight of the head unit  3 . The rotary shaft  11  is caused to rotate by the drive unit  13  from a state illustrated in  FIGS. 11 and 12 , and thereby the two eccentric cams  12  press the first contact surface  225  and the second contact surface  227 , respectively, on the Z 2  side as illustrated in  FIGS. 13 and 14 . In this manner, it is possible to cause the head unit  3  to move to the Z 2  side. In addition, it is possible to cause the eccentric cams  12  to rotate from a position on the Z 2  side illustrated in  FIGS. 13 and 14 , and thereby it is possible to cause the head unit  3  to move to the Z 1  side illustrated in  FIGS. 11 and 12 . 
     As described above, the first contact surface  225  and the second contact surface  227  of the head unit  3 , which project to the X 1  side of the first direction X, are caused to come into contact with the eccentric cams  12  of the lifting-lowering mechanism  10 , and the head unit  3  is supported by the three portions of the first bearing  220 , the second bearing  223 , and the third bearing  224  with respect to the two first and second shafts  9   a  and  9   b  even in a case where the head unit  3  can be lifted and lowered in the third direction Z. Therefore, it is possible to decrease the tilt of the head unit  3  in the first direction X with respect to the two first and second shafts  9   a  and  9   b . In other words, the first contact surface  225  and the second contact surface  227  are provided to project to the X 1  side. Therefore, when the lifting-lowering mechanism  10  comes into contact with the head unit  3  on the X 1  side, the X 1  side of the head unit  3  becomes higher to the Z 2  direction, and the head unit is likely to have a tilt in a rotating direction to the first direction X in which the X 2  side thereof becomes lower to the Z 1  direction. In particular, in a case where only two bearings are provided to support the head unit  3  with respect to the two first and second shafts  9   a  and  9   b , the head unit has a remarkable tilt. In the embodiment, the two second and third bearings  223  and  224  are provided to the single second shaft  9   b , and thereby it is possible to decrease the head unit  3  in size in the first direction X. In addition, the two second and third bearings  223  and  224  are provided to the second shaft  9   b , and thereby it is possible to decrease the tilt to the rotating direction to the second direction Y. Hence, it is possible to position the unit base  200  in the third direction Z by using the lifting-lowering mechanism  10  with high accuracy, and the nozzle-formed surface  102  held in the unit base  200  is positioned with respect to the recording sheet S held in the apparatus main body  2 , with high accuracy. In this manner, it is possible to decrease a shift of a landing position of an ink droplet such that it is possible to improve the print quality. 
     In addition, in embodiment, the wall portion  230  is provided on the unit base  200  and thereby the unit base  200  is increased in stiffness. Hence, even in a case where the two first and second shafts  9   a  and  9   b  support both end portions of the unit base  200  in the first direction X, it is possible to decrease the deformation of the unit base  200 , particularly, the deformation in the second direction Y or the deformation in a torsional direction. 
     Further, the unit base  200  is provided with the first contact surface  225  and the second contact surface  227  with which the lifting-lowering mechanism  10  comes into contact, and thereby it is possible to position the unit base  200  in the third direction Z as the lifting-lowering direction, that is, to position the nozzle-formed surface  102  of the recording head  100  held in the unit base  200  with high accuracy. In this manner, it is possible to adjust a gap between the recording sheet S and the nozzle-formed surface  102  with high accuracy and it is possible to decrease a shift of a landing position of an ink droplet or the like such that it is possible to improve the print quality. Incidentally, in a case where the eccentric cams  12  come into contact with the unit base  200  and a roller is provided to follow the rotation of the eccentric cams  12 , variations are likely to occur in components such as a roller, and the accuracy of the positioning of the head unit  3  in the third direction Z is likely to be lowered. 
     In addition, in the embodiment, the eccentric cams  12 , which come into contact with the first contact surface  225  and the second contact surface  227 , respectively, are fixed on the same shaft, that is, on the single rotary shaft  11 . Therefore, compared to a case where the rotary shaft  11  is provided for each eccentric cam  12 , it is possible to decrease a shift of the positions of the two eccentric cams  12  in the rotating direction, and it is possible to decrease the tilt of the head unit  3 , that is, the tilt in the rotating direction in a plane including the second direction Y and the third direction Z such that it is possible to position the nozzle-formed surface  102  of the head unit  3  by the lifting-lowering mechanism  10  with high accuracy. Incidentally, in the case where the rotary shaft  11  is provided for each of the two eccentric cams  12 , there is a concern that rotating angles of the two rotary shafts  11  which are linked to each other will be different from each other due to the variations of the component such as a gear or a belt that links the different rotary shafts  11 . When the rotating angles of the two rotary shafts  11  are different from each other, there are variations in a pressing amount of the eccentric cams  12  that press the first contact surface  225  and the second contact surface  227  and then, the nozzle-formed surface  102  is likely to tilt. 
     In addition, in the embodiment, as described above, the first eave portion  226   a  having the first contact surface  225  and the second eave portion  228   a  having the second contact surface  227  are integrally provided with the unit base  200 . In this manner, it is possible to increase the stiffness of the first eave portion  226   a  and the second eave portion  228   a , and it is possible to decrease a positional shift due to the deformation or the like of the first contact surface  225  and the second contact surface  227  such that it is possible to position the unit base  200  in the third direction Z as the lifting-lowering direction with higher accuracy. 
     Further, in the embodiment, the first contact surface  225  and the second contact surface  227  are provided in the head unit  3  in the first direction X. Therefore, compared to a case where the first contact surface  225  and the second contact surface  227  are provided on both sides in the second direction Y, it is possible to decrease the head unit  3  in size in the second direction Y. Similarly, in the embodiment, since the first contact surface  225  and the second contact surface  227  are coincident in the positions and the lifting-lowering mechanism  10  is provided in the first direction X as the direction orthogonal to the alignment direction of the recording heads  100 , it is possible to decrease the ink jet type recording apparatus  1  in size in the second direction Y, compared to a case where the lifting-lowering mechanisms  10  are provided on both sides in the second direction Y. 
     In addition, in the embodiment, the first contact surface  225  and the second contact surface  227  are provided only on the X 1  side of the first direction X. Therefore, compared to a case where contact surfaces, with which the lifting-lowering mechanism  10  comes into contact, are provided on both sides of the X 1  side and the X 2  side, it is possible to decrease the head unit  3  in size in the first direction X. It is needless to say that, similarly, since the lifting-lowering mechanism  10  is also provided only on the X 1  side, it is possible to decrease the ink jet type recording apparatus  1  in size in the first direction X. 
     Even in a case where the first contact surface  225  and the second contact surface  227  are provided only on the X 1  side and the sizes in the second direction Y and the first direction X are decreased with the lifting-lowering mechanism  10  provided only one the X 1  side, the head unit  3  is supported by the three portions of the first bearing  220 , the second bearing  223 , and the third bearing  224  with respect to the two first and second shafts  9   a  and  9   b , as described above, and thereby it is possible to decrease the tilt of the head unit  3  and it is possible to position the nozzle-formed surface  102  with high accuracy such that it is possible to improve the print quality. 
     Further, in the embodiment, the first contact surface  225  and the second contact surface  227 , with which the lifting-lowering mechanism  10  comes into contact, are disposed at positions which are separated from the nozzle-formed surface  102  on the Z 2  side. In other words, the first contact surface  225  is disposed on the Z 2  side from the supply surface  214  by the side wall  226   b  and the second contact surface  227  is provided to be continuous with the outer circumferential surface of the projecting portion  221 , and thus the second contact surface is disposed on the Z 2  side from the supply surface  214 . Therefore, the lifting-lowering mechanism  10  can less occupy a space at a position which is closer to the nozzle-formed surface  102 . Hence, it is possible to dispose the pressing rollers  607  at positions which are closer to the nozzle-formed surface  102  on the X 1  side and the X 2  side of the first direction X. As a result, it is possible to decrease a space between the two pressing rollers  607  in the first direction X, and thus it is easy to fix the posture of the recording sheet S between the two pressing rollers  607  such that it is possible to improve the print quality. In addition, it is possible to dispose a suction device that suctions the ink mists, or the like, on the nozzle-formed surface  102  on the X 1  side or the like, although not specifically illustrated. Hence, it is possible to efficiently suction and to remove the mists in the vicinity of the nozzle-formed surface  102  by the suction device, and it is possible to improve the print quality. 
     In the head unit  3 , a cap comes into contact with the nozzle-formed surface  102  on the Z 1  side. At this time, when the head unit  3  comes into contact with the eccentric cam  12  due to only the own weight, there is a concern that the head unit  3  will float to the Z 2  side due to the contact with the cap. Therefore, when the cap comes into contact with the head unit, the cap comes into contact with the supply surface  214  side of the head unit  3 . It is preferable that a floating preventive unit be provided to prevent the head unit  3  from floating to the Z 2  side. 
     The apparatus main body  2  and the head unit  3  of the ink jet type recording apparatus  1  are provided with a non-contact sensor unit that identifies a reference position of the nozzle-formed surface  102  with respect to the apparatus main body  2  in the third direction Z. 
     Here, the sensor unit is described also with reference to  FIGS. 15, 16, and 17 .  FIG. 15  is a top view illustrating the head unit and the sensor unit.  FIGS. 16 and 17  are side views illustrating the head unit and the sensor unit in which a sensor operation is shown. 
     As illustrated in  FIGS. 15 to 17 , a sensor unit  280  includes a sensor main body  281  fixed to the apparatus main body  2 , a reflective portion  282  such as a mirror that is provided in the apparatus main body  2  and reflects a light beam with which the sensor main body  281  performs irradiation, and a blocking plate  250  that is provided in the unit base  200  of the head unit  3  and blocks the beam with which the sensor main body  281  performs irradiation. 
     Here, as illustrated in  FIGS. 4, 8, 9, 10, and 15 , the blocking plate  250  of the unit base  200  is provided on an end portion of the second overhang  218  of the unit base  200  on the Y 2  side. In the embodiment, the second overhang  218  is provided with a slit  251  that penetrates therethrough in the third direction Z, and thus a part of the second overhang  218  is formed of the blocking plate  250 . In other words, the blocking plate  250  of the embodiment is integrally provided with the unit base  200 . It is needless to say that the blocking plate  250  is not limited thereto, and the blocking plate  250  as a separate body may be fixed to the unit base  200 ; however, there is a concern that a positional shift will be produced when the fixing is performed using the separate blocking plate  250 , or variations in the position of the blocking plate  250  with respect to the unit base  200  due to dimensional tolerance of a member. In the embodiment, the blocking plate  250  is integrally formed as a part of the unit base  200 , and thereby it is possible to decrease the positional shift of the blocking plate  250  with respect to the unit base  200 . 
     In addition, in the inside (not illustrated) of the sensor main body  281  provided in the apparatus main body  2 , a beam projecting portion such as a beam emitting element that performs irradiation with a light beam, and a beam receiving portion such as a beam receiving element that receives a light beam, are provided. 
     In addition, the apparatus main body  2  is provided with a reflective portion  282  such as a mirror that reflects the light beam projected from the sensor main body  281 . The reflective portion  282  is disposed to have a wider space from the sensor main body  281  than the thickness of the blocking plate  250  of the head unit  3 . Note that the slit  251  is formed to have a size to the extent that the reflective portion  282  can be inserted when the blocking plate  250  is inserted between the sensor main body  281  and the reflective portion  282 . In this manner, the blocking plate  250  can move between the sensor main body  281  and the reflective portion  282 . 
     In the configuration, as illustrated in  FIG. 16 , the light beam with which the sensor main body  281  performs the irradiation is reflected from the reflective portion  282  and then is received by the sensor main body  281 . 
     In addition, as illustrated in  FIG. 17 , the blocking plate  250  moves between the sensor main body  281  and the reflective portion  282 , and thereby the blocking plate  250  blocks the light beam with which the sensor main body  281  performs the irradiation. In this manner, the light beam with which the sensor main body  281  performs the irradiation does not reach the reflective portion  282 , or no reflected light beam is received by the sensor main body  281 . No reception of the reflective light beam by the sensor main body  281  is detected, and thereby the position of the blocking plate  250  is identified. In other words, the sensor unit  280  is capable of identifying the position of the blocking plate  250  between the sensor main body  281  and the reflective portion  282 . In other words, the sensor unit  280  of the embodiment can identify the position of the unit base  200  with respect to the apparatus main body  2  in the third direction Z in a non-contact manner, that is, the position of the head unit  3  in the third direction Z, without contact between the apparatus main body  2  and the head unit  3  including the unit base  200 . 
     The sensor unit  280  provided in the apparatus main body  2  and the unit base  200  identifies a position of the nozzle-formed surface  102  with respect to the apparatus main body  2  in the third direction Z in the non-contact manner, and thereby the lifting-lowering mechanism  10  can position the nozzle-formed surface  102  in the third direction Z with the identified position of the nozzle-formed surface  102  as a reference position with high accuracy. In other words, when the lifting-lowering mechanism  10  is not able to identify the position as a reference, the lifting-lowering mechanism  10  is not capable of positioning the height of the nozzle-formed surface  102  in the third direction Z with high accuracy. In the embodiment, with the position of the blocking plate  250  identified as the reference position by the sensor unit  280 , the lifting-lowering mechanism  10  adjusts the height of the nozzle-formed surface  102  in the third direction Z, and thereby it is possible to position the nozzle-formed surface  102  with high accuracy. Incidentally, in a case where the reference position is identified with the unit base  200  touching the apparatus main body  2 , a member is likely to be deformed or to have a positional shift due to the touching, the reference position varies, and accuracy of the position of the nozzle-formed surface  102  that is positioned by the lifting-lowering mechanism  10  is degraded. Note that, the adjustment of the position of the nozzle-formed surface  102  with respect to the reference position by the lifting-lowering mechanism  10  may be performed, on the basis of a rotary encoder that detects a rotating angle of the rotary shaft  11 , a linear encoder that detects a moving distance of the head unit  3  with respect to the apparatus main body  2  in the third direction Z, which is not particularly illustrated. 
     In addition, in the embodiment, the sensor unit  280  is disposed on the Z 2  side from the nozzle-formed surface  102 . In other words, the blocking plate  250  is provided on the second overhang  218  of the bottom portion  210 , and the sensor main body  281  and the reflective portion  282  that identify the position of the blocking plate  250  is disposed on the Z 1  side from the blocking plate  250 . Therefore, the blocking plate  250 , the sensor main body  281 , and the reflective portion  282  that configure the sensor unit  280  are disposed on the Z 2  side from the nozzle-formed surface  102 . In this manner, it is possible to decrease mists that are generated from ink droplets discharged from the nozzle openings  101  of the nozzle-formed surface  102 , and are attached to the sensor unit  280 , particularly to the sensor main body  281  or the reflective portion  282  such that it is possible to decrease an occurrence of detection failure or accuracy degradation of the detection. 
     Note that the non-contact sensor unit  280  of the embodiment is a so-called retro-reflective photoelectric sensor in which the light beam with which the sensor main body  281  performs the irradiation is reflected from the reflective portion  282  and the reflected light beam is received by the sensor main body  281 . It is needless to say that a photoelectric sensor, which is used in the sensor unit  280 , is not limited to the retro-reflective type described above. For example, the sensor unit  280  may be a so-called transmission-type photoelectric sensor that is provided with a sensor main body having only the beam projecting portion and a beam receiving portion instead of the reflective portion  282  in a portion in which the reflective portion  282  is provided, and that blocks, with the blocking plate  250 , the light beam with which the sensor main body performs the irradiation without a light beam received by the beam receiving portion, thereby identifying the position of the blocking plate  250 . In addition, the sensor unit  280  may be a so-called diffuse-reflective photoelectric sensor that identifies the position of the blocking plate  250 , in which the blocking plate  250  is provided with the reflective portion, a light beam with which the beam projecting portion of the sensor main body performs irradiation, is reflected from the reflective portion of the blocking plate  250 , and the reflected light beam is received by the beam receiving portion of the sensor main body. 
     In addition, in the embodiment described above, the apparatus main body  2  is provided with the sensor main body  281  and the head unit  3  is provided with the blocking plate  250 ; however, the configuration is not limited thereto, and the head unit  3  may be provided with the sensor main body  281 . However, at the time of replacement of the head unit  3 , the sensor main body  281  has to be simultaneously replaced, and thus maintenance costs increase. In addition, a problem is likely to arise in that the replacement work is complicated when the sensor main body  281  is replaced with the head unit  3  that is replaced or variations in the detected position are likely to occur due to a positional shift or the like when the sensor main body is replaced with the head unit  3 . Hence, as in the embodiment, it is preferable that the apparatus main body  2  be provided with the sensor main body  281  and the unit base  200  be provided with the blocking plate  250 . In this manner, the sensor main body  281  does not need to be replaced at the time of the replacement of the head unit  3 , and thereby it is possible to decrease the costs and the sensor main body  281  does not need to be replaced with the replaced head unit  3 . Thus, it is possible to decrease variations in the detected position due to the positional shift when the sensor main body  281  is attached to the head unit  3 . 
     Further, as illustrated in  FIG. 15 , the sensor unit  280  of the embodiment is provided on the Y 2  side. Therefore, it is preferable that the wiper, which wipes the nozzle-formed surface  102  of the head unit  3 , wipe the nozzle-formed surface  102  from the Y 2  side toward the Y 1  side. 
     Here, the wiper that wipes the nozzle-formed surface is described with reference to  FIGS. 18 to 20 .  FIGS. 18 and 20  are front views illustrating the head unit and a wiping unit.  FIG. 19  is an underside view illustrating the head unit and the wiper. 
     As illustrated in  FIGS. 18 to 20 , a wiping unit  270  includes a wiper  271  formed of rubber or the like and a support member  272  that supports a base end portion of the wiper  271 . 
     The wiper  271  can be formed of an elastic member such as rubber or an elastomer, a porous material such as sponge, or cloth such as woven fabric, knitted fabric, or non-woven fabric. In the embodiment, the wiper  271  is formed of a plate-shaped elastic material. The wiper  271  is disposed in the fourth direction Xa. 
     The support member  272  is provided to be moveable with respect to the nozzle-formed surface  102  in the second direction Y and supports a base end portion side of the wiper such that a front end portion of the wiper  271  becomes a free end. 
     In the wiping unit  270 , the support member  272  causes the wiper  271  to move from the Y 2  side to the Y 1  side in the second direction Y, and thereby the wiper continuously wipes the nozzle-formed surfaces  102  of the plurality of recording heads  100 . In other words, in the embodiment, the wiper  271  performs wiping from the Y 2  side as a first side toward the Y 1  side as a second side. The wiper  271  does not move vertically in the third direction Z for each nozzle-formed surface  102  of the recording head  100 , but moves horizontally with respect to the plurality of nozzle-formed surfaces  102  in the second direction Y, thereby simultaneously wiping the plurality of nozzle-formed surfaces  102 . For example, this is because, in a case where the wiper is caused to move in the third direction Z for each nozzle-formed surface  102 , there is a concern that it is difficult to control the position of the wiper  271  and thus there is a region that is not wiped, and the wiping is likely to be performed in a long time. The wiper wipes the plurality of nozzle-formed surfaces  102  without moving in the third direction Z, and thereby it is possible to perform the wiping in a short time and to decrease an occurrence of defective wiping. 
     In addition, the wiper  271  wipes from the Y 2  side as the first side toward the Y 1  side as the second side, the sensor unit  280  is provided on the Y 2  side as the first side, and thereby it is possible to decrease an amount of splashes that are attached to the sensor unit  280  when the wiper  271  ends the wiping. In other words, the sensor unit  280  on the first side means that the sensor unit  280  is disposed to be closer to the upstream side than to the downstream side in a range in which the wiper  271  performs the wiping. Note that, in the embodiment, the wiper  271  moves from the Y 2  side to the Y 1  side; however, the configuration is not particularly limited thereto, and the head unit  3  may move with respect to the wiper  271  from the Y 1  side to the Y 2  side. In other words, when the sensor unit  280  is disposed on the upstream side in a relative moving direction between the head unit  3  and the wiper  271 , it is possible to decrease the amount of splashes of inks that are attached to the sensor unit  280 . 
     Further, when the wiper wipes the nozzle-formed surface  102  of the head unit  3 , there is a concern that the head unit  3  will float to the Z 2  side due to the contact with the wiper. Therefore, when the wiper wipes the nozzle-formed surface  102 , a floating preventive unit comes into contact with the supply surface  214  side of the head unit  3  and prevents the head unit  3  from floating to the Z 2  side. 
     Note that, in the embodiment, an inclined surface portion  260  having an inclined surface  261  is provided on the Y 1  side of the unit base  200 , and thus the wiper is gradually separated along the inclined surface when the wiper moves to the Y 2  side of the second direction Y. 
     Specifically, the height of the inclined surface portion  260  on the Y 1  side in the third direction Z is substantially the same as the second wall portion  232  of the wall portion  230  and the inclined surface portion has the inclined surface  261  on the Z 1  side in which the Y 2  side of the inclined surface is positioned on the Z 2  side from the end portion of the wall portion  230 . 
     The inclined surface portion  260  having the inclined surface  261  causes a front end of the wiper  271  to move to the Z 1  side and to be elastically deformed when the wiping is performed on the nozzle-formed surface  102 , and then, causes the front end to gradually move to the Z 2  side along the inclined surface  261 . Hence, when the wiper  271  moves in the second direction Y and wipes the nozzle-formed surface  102 , the wiper  271  gradually returns to a normal shape from the elastic deformation along the inclined surface  261 . Therefore, the front end is prevented from swiftly returning to a normal state from the elastic deformation when the wiper  271  is separated from the nozzle-formed surface  102 , such that it is possible to decrease an amount of splashes of inks due to the swift returning to the normal state of the wiper  271 . 
     Note that, in the embodiment, the inclined surface  261  is provided to have the same height on the Y 1  side as the wall portion  230 ; however, the inclined surface  261  is provided to have the same height on the Y 1  side as the nozzle-formed surface  102 . 
     In addition, in the embodiment, the inclined surface portion  260  separately from the unit base  200  is fixed to a surface of the second overhang  218  of the unit base  200  on the Z 1  side; however, the configuration is not particularly limited thereto, and the inclined surface portion  260  may be integrally provided with the unit base  200 . 
     In addition, in the embodiment, the sensor unit  280  is disposed on the second overhang  218  of the unit base  200  on the upstream side in the transport direction of the recording sheet S, that is, on the X 1  side in the first direction X. In particular, it is preferable that the sensor unit  280  be disposed on the X 1  side from the recording head  100 . The sensor unit  280  is provided on the X 1  side as the upstream side from the recording head  100  in the transport direction of the recording sheet S, and thereby it is possible to decrease an amount of mists that are attached to the sensor unit  280  when the mists are generated during discharge of the inks from the nozzle-formed surface  102  of the recording head  100 . In other words, an air current is generated between the nozzle-formed surface  102  of the recording head  100  and the recording sheet S, from upstream to downstream in the transport direction in response to transport of the recording sheet S, that is, from the X 1  side toward the X 2  side in the first direction X. Therefore, the sensor unit  280  is disposed on the upstream side from the recording head  100 , that is, on the X 1  side, in the transport direction of the recording sheet S, and thereby it is possible to decrease an amount of mists carried through the air current that are attached to the sensor unit  280 . Hence, the sensor unit  280  identifies the reference position of the unit base  200  with high accuracy such that it is possible to position the nozzle-formed surface  102  with respect to the recording sheet S with high accuracy. 
     Here, an example of the recording head  100 , which is fixed to the unit base  200 , is more described with reference to  FIG. 21 .  FIG. 21  is an exploded perspective view illustrating the ink jet type recording head according to Embodiment 1 of the invention. In addition, in the embodiment, the directions of the recording head  100  are described, based on directions obtained when the recording head is mounted in the ink jet type recording apparatus  1 , that is, the first direction X, the second direction Y, and the third direction Z. 
     As illustrated in  FIGS. 3, 5, 7, and 21 , the recording head  100  is configured to include a plurality of members which are stacked in the third direction Z. Specifically, the recording head  100  includes the plurality of head main bodies  110  from which ink droplets are discharged, the holding members  120  that hold the plurality of head main bodies  110 , and the covers  130  as fixing plates provided on the nozzle-formed surface side of the head main bodies  110 . 
     The head main body  110  has nozzle openings  101  on the Z 1  side in the third direction Z. A surface of the head main body  110  provided with the nozzle openings  101  on the Z 1  side configures a part of the nozzle-formed surface  102 . In addition, in the inside (not illustrated) of the head main body  110 , a flow path that communicates with the nozzle opening  101 , and a pressure generating unit that causes a change in the pressure of the ink in the flow path are provided. As the pressure generating unit, it is possible to use a pressure generating unit that changes a volume of the flow path due to deformation of a piezoelectric actuator having a piezoelectric material with an electromechanical converting function, that causes a change in the pressure in the ink in the flow path, and that discharges ink droplets from the nozzle openings  101 , a pressure generating unit in which a heating element is disposed in the flow path, and ink droplets are caused to be discharged from the nozzle openings  101  due to bubbles produced by the heating of the heating element, or a so-called electrostatic actuator that generates an electrostatic force between a vibration plate and an electrode, in which the vibration plate is deformed due to the electrostatic force, and that discharges ink droplets from the nozzle openings  101 , or the like. 
     In addition, drive wirings  111  connected to the pressure generating unit in the inside (not illustrated) are guided out from the surface of the head main body  110  on the Z 2  side. 
     The Z 2  sides of the plurality of head main bodies  110  are fixed to a surface of the holding member  120  on the Z 1  side. 
     The holding member  120  includes the flow-path member  121 , the holder  122 , and the wiring substrate  123  held between the flow-path member  121  and the holder  122 . 
     In the inside (not illustrated) of the flow-path member  121 , a flow path is provided to supply, to the head main body  110 , inks supplied from the liquid storing unit  4 . The flow path is provided to open to the front end surface of protrusions  124  which are provided on a surface of the flow-path member  121  on the Z 1  side and protrude in the third direction Z. In the embodiment, four protrusions  124  are provided on the surface of the flow-path member  121  on the Z 1  side. In other words, four separate flow paths are provided in the inside of the flow-path member  121 . Note that a filter for removing foreign substances such as dirt or bubbles contained in the inks may be provided in the flow path of the flow-path member  121 . 
     The holder  122  is fixed to a surface of the flow-path member  121  on the Z 1  side, and in the inside (not illustrated) of the holder, flow paths that communicate with the flow paths provided in the inside of the flow-path member  121  are provided. The inks supplied from the flow-path member  121  are supplied to the plurality of head main bodies  110  via the flow paths in the holder  122 . Note that each path provided in the inside of the holder  122  diverges into a plurality of paths through which the inks are supplied to the plurality of head main bodies  110 , although not specifically illustrated. 
     The flow-path member  121  and the holder  122  are stacked in the third direction Z and are fixed by using third screw members  403  (refer to  FIG. 6 ). In other words, an interface exists between the flow-path member  121  and the holder  122 . In addition, the wiring substrate  123  is held on the interface, that is, between the flow-path member  121  and the holder  122 . The wiring substrate  123  is formed of a rigid substrate which is common to the drive wirings  111  of the plurality of head main bodies  110  and to which the drive wirings are electrically connected. In addition, in the embodiment, the wiring substrate  123  is provided to be exposed on the side surface of the recording head  100 , that is, from the stack interface between the flow-path member  121  and the holder  122 . 
     In addition, cable inserting holes  125 , which penetrate through the flow-path member  121  in the third direction Z, are provided in both end portions of the flow-path member  121  in the first direction X. The cables  126  inserted into the cable inserting holes  125  from the Z 1  side of the flow-path member  121  are connected to the wiring substrate  123  held between the flow-path member  121  and the holder  122 . 
     In addition, the holder  122  includes a holding portion  127  that forms a groove-shaped space on the Z 1  side. The holding portion  127  is provided to be continuous to the surface of the holder  122  on the Z 1  side in the second direction Y, and thereby the holding portion is provided to open to both sides thereof in the second direction Y. In addition, the holder  122  is provided with the holding portion  127  substantially at the central portion in the first direction X, and leg portions  128  are formed on both sides of the holding portion  127  in the first direction X. In other words, the leg portions  128  are provided on both end portions only in the first direction X of the surface of the holder  122  on the Z 1  side and are not provided on both end portions in the second direction Y. 
     The plurality of head main bodies  110  are fixed in the holding portion  127 . In other words, the leg portions  128  are positioned on both sides in the first direction X with respect to the head main body  110 . In addition, the holder  122  and the head main body  110  have surfaces facing each other in the third direction Z and adhering to each other. In the embodiment, six head main bodies  110  adhere to the single holder  122 . It is needless to say that the number of head main bodies  110  which are fixed to the single holder  122  is not limited to the holder described above, and a single head main body  110  may be fixed to the single holder  122 , or two or more head main bodies may be fixed to the single holder. Incidentally, the plurality of head main bodies  110  are provided to the single recording head  100  and multiple nozzle arrays are formed, and thereby it is possible to increase the yield ratio, compared to a case where a plurality of nozzle arrays are provided in only one head main body  110  with respect to the single recording head  100  and multiple arrays are formed. In addition, the plurality of head main bodies  110  are provided in the single recording head  100 , thereby it is easy to increase the weight of the recording head  100 ; however, the wall portion  230  is provided on the unit base  200  and the stiffness of the unit base is increased, and thereby it is possible to decrease the deformation of the unit base  200  due to the weight of the recording heads  100 . 
     Note that the plurality of head main bodies  110  of the embodiment are fixed to have nozzle arrays which are inclined with respect to the first direction X as the transport direction of the recording sheet S, in the in-plane direction of the nozzle-formed surface  102 . In other words, the fourth direction Xa as the alignment direction of the nozzle openings  101  that form the nozzle array means a direction inclined with respect to the first direction X. In the embodiment, the recording head  100  is configured to include the plurality of head main bodies  110  which are aligned in the second direction Y, and thus it is possible to dispose the head main bodies  110  at positions at which at least some nozzle openings  101  of the head main bodies  110 , which are adjacent to each other in the second direction Y, overlap each other in the first direction X. In addition, as described above, the plurality of recording heads  100  are aligned in the second direction Y, and thus it is possible to dispose the recording heads  100  at positions at which at least some nozzle openings  101  of the recording heads  100 , which are adjacent to each other in the second direction Y, overlap each other in the first direction X. Accordingly, it is possible to form the nozzle openings  101 , which are aligned in the head unit  3  at equal intervals in the second direction Y. 
     The cover  130  covers the opening of the holding portion  127  of the holder  122  on the Z 1  side. In the embodiment, a surface of the cover  130  on the Z 1  side and a surface of the head main body  110  on the Z 1  side exposed by an exposure opening  133  are referred to as a nozzle-formed surface  102 . 
     In addition, right-angle bending portions  132  are provided on both end portions of a base portion  131  in the second direction Y, and are formed to have a size to cover an opening area of the holding portion  127  that opens to the sides in the second direction Y. The right-angle bending portions  132  adhere to side surfaces of the holder  122  in the second direction Y. In this manner, the openings of the holding portion  127  to the sides in the second direction Y are covered and sealed by the right-angle bending portion  132 . 
     As described above, in the embodiment, since the right-angle bending portions  132  are provided on the cover  130  on both sides of the holder  122  in the second direction Y, and thereby the cover  130  and the holder  122  adhere to each other, there is no need to provide leg portions for adhering to the base portion  131  of the cover  130  on both sides of the holder  122  in the second direction Y. Therefore, since there is no leg portion between the adjacent recording heads  100  when the recording heads  100  are aligned in the second direction Y, it is possible to decrease a gap between the recording heads  100  which are adjacent to each other in the second direction Y. In this manner, the head main bodies  110  of the recording heads  100 , which are adjacent to each other in the second direction Y, can be provided to approach each other, and the nozzle openings  101  provided in the head main bodies  110  of the adjacent recording heads can be provided to approach each other in the second direction Y. 
     Note that the configuration is not limited thereto, and the recording head  100  may be provided with the leg portions on both sides of the holder  122  in the second direction Y. In addition, the right-angle bending portion  132  may be provided on the entire circumference of the cover  130  without the leg portions, and the right-angle bending portion  132  may cover the entire side surfaces of the head main body  110 . 
     As described above, the plurality of, in the embodiment, six recording heads  100  are aligned in the second direction Y, that is, are aligned in a straight line and are detachably fixed to the unit base  200 . In other words, the plurality of recording heads  100  are not disposed to be shifted from one another in the first direction X. In this manner, it is possible to decrease the width of the head unit  3  in the first direction X, and thus it is possible to decrease the head unit  3  in size. It is needless to say that the recording heads  100  aligned in the second direction Y may be arranged to be shifted in the first direction X; however, when the recording heads  100  are significantly shifted in the first direction X, the width of the unit base  200  or the like in the first direction X is likely to be widened. As described above, when the head unit  3  is increased in size in the first direction X, the distance between the two pressing rollers  607  becomes long in the first direction X in the ink jet type recording apparatus  1 , and it is difficult to fix the posture of the recording sheet S. In addition, the head unit  3  and the ink jet type recording apparatus  1  are likely to be increased in size. 
     Other Embodiments 
     As described above, an embodiment of the invention is described; however the basic configuration of the invention is not limited to the embodiment described above. 
     In Embodiment 1 described above, the first contact surface  225  and the second contact surface  227  are provided on the X 1  side, as the contact surface with which the lifting-lowering mechanism  10  comes into contact; however, the position and number of the contact surfaces are not particularly limited thereto, and the contact surface may be provided on the X 2  side or the contact surfaces may be provided on both of the X 1  side and the X 2  side. In addition, the contact surface may be provided in the second direction Y. Further, instead of the contact surface with which the lifting-lowering mechanism  10  comes into contact, a roller that rotates in response to the rotation of the eccentric cam  12  may be provided in the head unit  3  and the roller may come into contact with the lifting-lowering mechanism  10 . In addition, one contact surface may be provided or three or more contact surfaces may be provided. 
     In addition, in Embodiment 1 described above, the eccentric cam  12  or the like is used as the lifting-lowering mechanism  10 ; however, the lifting-lowering mechanism that causes the head unit  3  to be lifted and lowered in the third direction Z is not particularly limited thereto. For example, a contact member that comes into contact with the first contact surface  225  and the second contact surface  227  may be caused to reciprocate in the third direction Z by hydraulic pressure or drive of a motor. 
     In addition, in Embodiment 1 described above, the wall portion  230  is provided on the unit base  200 ; however, the configuration is not particularly limited thereto, and the unit base  200  may be configured of only the bottom portion  210 . 
     In addition, in Embodiment 1 described above, the wall portion  230  of the unit base  200  is provided on the surface side on which the recording heads  100  are held, that is, on the Z 1  side; however, the configuration is not particularly limited thereto, and the wall portion  230  may be provided on the Z 2  side of the bottom portion  210 . However, as the embodiments described above, when the wall portion  230  is provided on the Z 1  side of the bottom portion  210 , it is possible to decrease the head unit  3  in size, and it is possible to protect the side surface of the recording head  100  by the wall portion  230  such that it is possible to decrease damage caused when the recording heads  100  come into contact with the recording sheet S. In addition, the side surfaces of the recording heads  100  are protected by the wall portion  230 , and thereby it is possible to decrease an amount of inks which are attached to the stack interface of the recording head  100 . Note that the wall portion  230  may be provided on both sides of the Z 1  side and the Z 2  side of the bottom portion  210 . In this manner, it is possible to increase stiffness of the head unit  3 . However, the wall portion  230  is provided on the Z 2  side of the bottom portion  210 , and thereby the head unit  3  is likely to be increased in size in the third direction Z. 
     In addition, in Embodiment 1 described above, the head unit  3  is held to the two first and second shafts  9   a  and  9   b  so as to be moveable in the third direction Z; however, the number or positions of the shafts may not be particularly limited thereto, and one shaft may be provided, or three or more shafts may be provided. However, in a case of one shaft, a guide is provided such that the head unit does not rotate around the shaft; however, the cross-sectional shape of the shaft needs to be a polygonal shape such as a quadrangular shape. In addition, in a case of three or more shafts, it is possible to decrease the tilt of the nozzle-formed surface  102  with respect to the plane including the first direction X and the second direction Y; however, there is a concern that it is difficult to position the shafts such that the clearances of the bearings with respect to the shafts are uniform, and it is not possible for the head unit to smoothly move in the third direction Z. In Embodiment 1 described above, the two first and second shafts  9   a  and  9   b  are provided, and thereby the movement in the rotating direction around the shaft is easily regulated and it is possible to easily position the two first and second shafts  9   a  and  9   b  with uniform clearances of the first bearing  220 , the second bearing  223 , and the third bearing  224  with respect to the two first and second shafts  9   a  and  9   b  such that it is possible to cause the head unit to smoothly move with respect to the first shaft  9   a  and the second shaft  9   b  in the third direction Z. 
     Note that, in the embodiment, the plurality of recording heads  100  are screwed and fixed to the unit base  200  by using the spacers  300 , the first screw member  401 , and the second screw member  402 ; however, the configuration is not particularly limited thereto. For example, the plurality of recording heads  100  may adhere to the unit base  200  with an adhesive or may be fixed by using a clip or the like. 
     In addition, in Embodiment 1 described above, the alignment direction of the plurality of recording heads  100  held in the unit base  200  is the second direction Y as the direction perpendicular to the first direction X as the transport direction of the recording sheet S; however, the configuration is not particularly limited thereto, and a head unit, in which the recording heads  100  are aligned in the longitudinal direction of the unit base  200 , may be disposed such that the plurality of recording heads  100  have an alignment direction at an angle intersecting with the first direction X as the transport direction of the recording sheet S, that is, at an angle which is smaller than 90 degrees with respect to the first direction X. At this time, it is possible to provide the nozzle array in a direction perpendicular to the longitudinal direction of the unit base  200  in the in-plane direction of the nozzle-formed surface  102 , and the entire head unit is inclined, and thereby it is possible to dispose the nozzle array in a direction inclined with respected to the first direction X as the transport direction. 
     In addition, in Embodiment 1 described above, the recording heads  100  are arranged in a straight line in the second direction Y; however, the configuration is not particularly limited thereto, and the recording heads  100  may be arranged in a zigzag pattern in the second direction Y. Here, in the arrangement of the recording heads  100  in the zigzag pattern in the second direction Y, the recording heads  100  arranged in the second direction Y are disposed to be alternately shifted in the first direction X, and two rows of the recording heads  100  arranged in the second direction Y are arranged side by side in the first direction X. However, when the recording heads  100  as in Embodiment 1 described above are arranged in the straight line in the second direction Y, it is possible to decrease the head unit  3  in size in the first direction X, compared to the case of the arrangement in the zigzag pattern. 
     Further, in Embodiment 1 described above, the fourth direction Xa as the alignment direction of the nozzle openings  101  of the head main body  110  is the direction inclined with respect to the second direction Y orthogonal to the first direction X as the transport direction; however, the fourth direction Xa as the alignment direction of the nozzle openings  101  may be the same direction as the first direction X as the transport direction, or the fourth direction Xa as the alignment direction of the nozzle openings  101  may be the same direction as the second direction Y. Further, the nozzle openings  101  are not limited to the alignment in an array shape, and the nozzle openings  101  may be disposed to have a matrix shape. Further, in Embodiment 1 described above, the holder  122  has a substantially parallelogramic shape in a plan view kin the third direction Z perpendicular to the nozzle-formed surface  102 ; however, the configuration is not particularly limited thereto, and the holder may have a rectangular shape, a trapezoidal shape, a polygonal shape, or the like. Here,  FIG. 22  illustrates an example described above.  FIG. 22  is a plan view illustrating the recording head unit as an example of the liquid ejecting head unit according to another embodiment of the invention, when viewed from the liquid ejecting surface side. 
     As illustrated in  FIG. 22 , a recording head  100 A has a trapezoidal shape in a plan view from the nozzle-formed surface  102  side. In addition, the plurality of recording heads  100 A are aligned in the second direction Y and are fixed to the unit base  200 , and the recording heads  100 A aligned in the second direction Y are alternately inverted by 180 degrees in the in-plane direction of the nozzle-formed surface  102 . 
     In the recording head  100 A, the nozzle openings  101  are arranged in a matrix shape in the nozzle-formed surface  102 . Also in this configuration, it is possible to achieve the same effects using the same configuration as Embodiment 1 described above. Note that, also in the recording head  100  of Embodiment 1 described above, the nozzle openings  101  may be arranged in the matrix shape. 
     In addition, in the embodiment described above, the eccentric cam  12  or the like is used as the lifting-lowering mechanism  10 ; however, the lifting-lowering mechanism that causes the head unit  3  to be lifted and lowered in the third direction Z is not particularly limited thereto. For example, a contact member that comes into contact with the first contact surface  225  and the second contact surface  227  may be caused to reciprocate in the third direction Z by hydraulic pressure or drive of a motor. However, as the embodiment described above, it is possible to simplify the configuration by using the eccentric cam  12  as the lifting-lowering mechanism  10 , and it is possible to decrease the costs or decrease the size. 
     Further, in the embodiment described above, as the ink jet type recording apparatus  1 , a so-called line type recording apparatus, in which the head unit  3  is fixed to the apparatus main body  2 , only the recording sheet S is transported, and thereby printing is performed, is exemplified; however, the apparatus is not particularly limited thereto, and the invention can be applied to a so-called serial type recording apparatus in which the head unit  3  is mounted on a carriage that moves in a direction intersecting with the first direction X as the transport direction of the recording sheet S, for example, in the second direction Y, and printing is performed while the head unit  3  moves in the direction intersecting with the transport direction. In addition, the configuration is not limited to the configuration in which the recording sheet S is transported with respect to the head unit  3 , and printing may be performed by a configuration in which the head unit  3  is caused to move with respect to the recording sheet S, or the recording sheet S may be relatively move with respect to the head unit  3 . 
     Note that, in the embodiments described above, an ink jet type recording apparatus is described as an example of a liquid ejecting apparatus; however, the invention is widely applied to a liquid ejecting apparatus in general, as a target, and can be also applied to a liquid ejecting apparatus including a liquid ejecting head that ejects liquids in addition to an ink. Examples of other liquid ejecting heads include various recording heads that are used in an image recording apparatus such as a printer, a color material ejecting head that is used in manufacturing a color filter of a liquid crystal display or the like, an electrode material ejecting head that is used in forming electrodes of an organic EL display, a field emission display (FED), or the like, a bioorganic material ejecting head that is used in manufacturing a biochip, and the invention can be applied to a liquid ejecting apparatus including the liquid ejecting head.