Patent Publication Number: US-9895884-B2

Title: Head and liquid ejecting apparatus

Description:
BACKGROUND 
     1. Technical Field 
     The present invention relates to a head and a liquid ejecting apparatus and, more particularly, to an ink jet type recording head and an ink jet type recording apparatus that ejects ink as a liquid. 
     2. Related Art 
     A piezo ink jet system is an on-demand type ink jet print system that discharges droplets of ink by deforming piezo elements through application of voltage (JIS Z8123-1:2013). 
     A permanent head (hereinafter, simply termed head) is a mechanical or electrical component of a printer main body which continually or intermittently produces liquid droplets of ink (JIS Z8123-1:2013). 
     A head for use in the piezo ink jet system includes a flow path formation substrate provided with a pressure generation chamber that communicates with a nozzle that ejects a liquid droplet, a piezo element provided on the side of one surface of the flow path formation substrate, and a drive circuit substrate joined to a piezo element side of the flow path formation substrate and provided with a drive circuit that drives the piezo element. The head ejects liquid droplets from the nozzle by causing pressure changes in the liquid within the pressure generation chamber. 
     For example, a known head includes a plurality of head bodies having rows of nozzles that discharge liquids and a flow path member for supplying the liquids to the head bodies from liquid storage units such as ink cartridges. Each head body is provided with nozzle rows in which nozzles that eject liquid droplets are aligned in a direction and which are aligned side by side in a direction that intersects that direction. 
     For example, in a head that has eight nozzle rows, the flow path member and the like are constructed so that, of the eight nozzle rows, each two nozzle rows disposed symmetrically about a center line of the eight nozzle rows, that is, a center line between the fourth and fifth rows, are supplied with the same one of four color inks; for example, the eight nozzle rows are supplied with yellow, cyan, magenta, black, black, magenta, cyan, and yellow inks in that order (see, e.g., JP-A-2013-039762). An ink jet type recording apparatus having such a head performs a recording operation while moving the head back and forth relative to a recording medium. Therefore, the order in which the color inks land on the ejection target medium remains the same between the back and forth movements. 
     In a known flow path member for supplying inks to a plurality of nozzle rows, flow paths through which the color inks supplied from ink cartridges storing the inks flow are each divided midway into branch flow paths (see, e.g., JP-A-2015-33838). This flow path member includes filters that remove undesired matters and gas bubbles from the inks supplied from the ink cartridges. The flow paths downstream of the filters are divided into branches so that each ink is supplied to corresponding two rows of the symmetrically disposed nozzle rows. In this manner, one kind of liquid or ink can be supplied to a plurality of nozzle rows. 
     However, in the flow path member provided with branched flow paths for various color inks, particularly in a construction in which the nozzle rows are symmetrically disposed separately for each color ink, the arrangement of the branch flow paths and filter chambers is complicated so that it is difficult or impossible to achieve space saving. 
     Furthermore, the head is subjected to a cleaning operation in which ink is sucked from nozzles so as to discharge gas bubbles and the like together with the ink from the flow paths downstream of a filter. In the foregoing flow path member, since the flow paths are branched downstream of the filters and are configured in accordance with the arrangement of the nozzle rows, the flow path length downstream of the filters is longer than the flow path length upstream of the filters. Therefore, in the cleaning operation, the amount of ink discharged from the flow paths downstream of the filters is large. 
     This problem is not limited to the heads that eject inks but similarly exists in heads that eject other kinds of liquids. 
     SUMMARY 
     An advantage of some aspects of the invention is that a head and a liquid ejecting apparatus that are capable of realizing high-quality ejection of liquid while making the configuration of branched flow paths as compact as possible are provided. Another advantage of some aspects of the invention is that a head and a liquid ejecting apparatus capable of reducing the amount of liquid discharged in the cleaning operation are provided. 
     In recording heads, a head capable of recording according to one aspect of the invention includes a head body that has nozzle rows in which nozzle openings that eject liquid are disposed side by side in a first direction and which are disposed side by side in a second direction that intersects the first direction, a liquid flow path that supplies the liquid from a liquid supply unit to the head body, and a flow path member that includes filters provided in the liquid flow path. The nozzle rows that discharge the same liquid are disposed at locations symmetrical about a reference line that extends in the first direction. The flow path member includes a first flow path member to which the liquid from the liquid supply unit is supplied, a second flow path member joined to the first flow path member, a filter retainer member that is joined to the second flow path member and that holds the filters, a third flow path member that is joined to the filter retainer member and that supplies the liquid to the head body. The liquid flow path includes an upstream flow path upstream of the filters and downstream flow paths that are downstream of the filters and that are formed separately for each nozzle row. The upstream flow path includes horizontal flow paths that are provided between the first flow path member and the second flow path member and that divide the liquid supplied from the liquid supply unit and buffer chambers provided on the horizontal flow paths branched so as to divide the liquid. Between the second flow path member and the filter retainer member, filter chambers are provided in regions that face the buffer chambers. The buffer chambers communicate with central portions of the filter chambers. 
     In this exemplary embodiment, an upstream portion to which the liquid supplied from the liquid supply unit flows connects to an intermediate portion of the horizontal flow path and the path is branched to two opposite sides in the horizontal flow path, equal and smooth branching can be achieved and, furthermore, the degree of freedom in laying out the branch flow paths can be improved and space saving can be facilitated. This also makes it possible to supply the liquid corresponding to the symmetrical arrangement of the nozzle rows and also to improve the ease in discharging gas bubbles during cleaning and reduce the amount of the liquid discharged for cleaning. Furthermore, even in a construction in which a plurality of liquid flow paths are each branched corresponding to the symmetrical arrangement of the nozzle rows, the pressure of the liquids supplied to the nozzle rows can be inhibited from varying among the nozzle rows. Due to this, a head capable of performing high-quality ejection of liquids can be provided. 
     In the foregoing head, each of the horizontal flow paths is a single flow path whose two end portions are provided with the buffer chambers and an intermediate portion of that flow path communicates with a flow path extending from the liquid supply unit so as to be a branching portion at which the flow path branches into two opposite horizontal directions. 
     This eliminates the stagnation of the liquid caused by the branching, so that space-saving and uniform branching can be achieved. 
     Furthermore, in the foregoing head, the branching portion may be immediately under the liquid supply unit. 
     This eliminates unnecessary flow paths and allows further space saving. 
     Furthermore, in the foregoing head, the branching portion may be provided in a straight portion of each horizontal flow path. 
     This allows smoother branching. 
     Another aspect of the invention is a liquid ejecting apparatus that includes a head as described above. 
     This aspect of the invention provides a liquid ejecting apparatus that allows the space saving of flow paths and that is capable of realizing high-quality ejection of liquids and reducing the amount of the liquids discharged during cleaning. 
    
    
     
       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 an exploded perspective view of a head body. 
         FIG. 2  is a plan view of the head body. 
         FIG. 3  is a sectional view taken on line III-III in  FIG. 2 . 
         FIG. 4  is an exploded perspective view of a head. 
         FIG. 5  is a plan view of a first flow path member. 
         FIG. 6  is a view of the reverse surface of the first flow path member. 
         FIG. 7  is a plan view of a second flow path member. 
         FIG. 8  is a view of the reverse surface of the second flow path member. 
         FIG. 9  is a plan view of a filter retainer member. 
         FIG. 10  is a view of a reverse surface of the filter retainer member. 
         FIG. 11  is a plan view of a third flow path member. 
         FIG. 12  is a view of the reverse surface of the third flow path member. 
         FIG. 13  is a bottom plan view of a head. 
         FIG. 14  is a schematic diagram illustrating an ink jet type recording apparatus. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary Embodiment 1 
     An exemplary embodiment of the invention will be described in detail below. This exemplary embodiment of the invention will be described in conjunction with an ink jet type recording head (hereinafter, simply referred to as head) that ejects ink as an example of a permanent head. 
     First, an example of a head body provided in a head according to this exemplary embodiment will be described.  FIG. 1  is an exploded perspective view of a head body.  FIG. 2  is a plan view of the head body.  FIG. 3  is a sectional view of the head body taken on line III-III in  FIG. 2 . 
     A head body  2  includes a plurality of members such as a flow path formation substrate  10 , a communication plate  15 , a nozzle plate  20 , a protective substrate  30 , a compliance substrate  45 , a case member  40 , and a wiring board  121 . 
     The flow path formation substrate  10  may be made of a metal, such as stainless steel or nickel (Ni), a ceramic material represented by zirconium oxide (ZrO 2 ) or aluminum oxide (Al 2 O 3 ), a glass ceramic material, an oxide such as magnesium oxide (MgO) or lanthanum aluminate (LaAlO 3 ), etc. In this exemplary embodiment, the flow path formation substrate  10  is made of a silicon single crystal substrate. In this flow path formation substrate  10 , pressure generation chambers  12  compartmentalized by a plurality of partition walls are disposed side by side along a direction in which a plurality of nozzle openings  21  that discharge ink are aligned. These pressure generation chambers  12  are formed by performing anisotropic etching on the flow path formation substrate  10  from the side of one surface thereof. 
     Hereinafter, a direction in which the pressure generation chambers  12  are aligned side by side (that is also the direction in which the nozzle openings  21  are aligned) will be referred to as an alignment direction of the pressure generation chambers  12  or a first direction X. Furthermore, the flow path formation substrate  10  is provided with a plurality of rows of the pressure generation chambers  12  aligned side by side in the first direction X. In this exemplary embodiment, two rows of the pressure generation chambers  12  extend in the first direction X. A direction of the plurality of rows of the pressure generation chambers  12  are aligned side by side will be hereinafter referred to as a second direction Y. Furthermore, a direction that intersects the first direction X and the second direction Y will be referred to as an ejection direction of ink droplets (liquid droplets) or a third direction Z. The third direction is a direction in which a head body and a head substrate are stacked as mentioned in the appended claims. The coordinate axes indicated in the drawings represent the first direction X, the second direction Y, and the third direction Z. The directions indicated by the arrows are also termed the positive directions and the opposite directions are also termed the negative directions. Incidentally, although, in this exemplary embodiment, the directions X, Y and Z are orthogonal to each other, the invention is not limited to a construction in which the foregoing components are arranged in directions orthogonal to each other. 
     On the one-surface side (a third direction Z side, that is, a positive Z direction side) of the flow path formation substrate  10 , the communication plate  15  and the nozzle plate  20  are stacked in the third direction Z. Specifically, the head body  2  includes the communication plate  15  provided on the one surface of the flow path formation substrate  10  and the nozzle plate  20  provided on the opposite side surface of the communication plate  15  to the flow path formation substrate  10 . 
     The communication plate  15  is provided with nozzle communication paths  16  that provide communication between the pressure generation chambers  12  and the nozzle openings  21 . The communication plate  15  has a larger area than the flow path formation substrate  10 . The nozzle plate  20  has a smaller area than the flow path formation substrate  10 . Because the communication plate  15  is provided in this manner, the nozzle openings  21  of the nozzle plate  20  and the pressure generation chambers  12  can be disposed apart from each other so that the ink in the pressure generation chambers  12  is less easily affected by the viscosity increase or thickening of the ink caused by evaporation of moisture that occurs in the ink near the nozzle openings  21 . Furthermore, the nozzle plate  20  needs only to cover the openings of the nozzle communication paths  16  that provides communication between the pressure generation chambers  12  and the nozzle openings  21 . Therefore, the area of the nozzle plate  20  can be made relatively small, so that the cost can be reduced. 
     Furthermore, the communication plate  15  is provided with first manifold portions  17  and second manifold portions  18  (constricted flow paths or orifice flow paths) which form parts of manifolds  100 . 
     The first manifold portions  17  penetrate through the communication plate  15  in its thickness direction (the stacking direction of the communication plate  15  and the flow path formation substrate  10  (third direction Z)). The second manifold portions  18  do not penetrate through the communication plate  15  in its thickness direction but each have an opening in a nozzle plate  20 -side surface of the communication plate  15 . 
     The communication plate  15  is also provided with supply communication paths  19  that each communicate with a second direction Y-side end portion of a pressure generation chamber  12 . The supply communication paths  19  are provided independently for each of the pressure generation chambers  12 . The supply communication paths  19  provide communication between the second manifold portions  18  and the pressure generation chambers  12 . 
     The communication plate  15  described above may be made of a metal, such as stainless steel or nickel (Ni), or a ceramic such as zirconium (Zr). It is preferable that the communication plate  15  be made of a material whose linear expansion coefficient is comparable or substantially equal to that of the flow path formation substrate  10 . That is, if the communication plate  15  is made of a material whose linear expansion coefficient is greatly different from that of the flow path formation substrate  10 , heating or cooling will cause warpage of the flow path formation substrate  10  and the communication plate  15 . In this exemplary embodiment, the communication plate  15  is made of the same material as the flow path formation substrate  10 , that is, made from a silicon single crystal substrate, so that thermal warpage or thermal crack, detachment, etc. can be restrained. 
     The nozzle plate  20  is provided with the nozzle openings  21  that communicate with the corresponding pressure generation chambers  12  via the nozzle communication paths  16 . The thus-formed nozzle openings  21  are aligned in the first direction X, forming nozzle rows  21   a.  In the nozzle plate  20 , two nozzle rows  21   a  of nozzle openings  21  aligned in the first direction X are disposed side by side in the second direction Y. Of the two side surfaces of the nozzle plate  20 , the surface from which ink droplets are discharged, that is, the opposite surface of the nozzle plate  20  to the pressure generation chambers  12 , will be referred to as the liquid ejection surface  20   a.    
     The nozzle plate  20  described above may be made of, for example, a metal such as stainless steel (e.g., a JIS SUS series stainless steel), an organic substance, such as polyimide resin, a silicon single crystal substrate, etc. Use of a silicon single crystal substrate to form the nozzle plate  20  will provide substantially equal linear expansion coefficients of the nozzle plate  20  and the communication plate  15 , so that the warpage caused by heating or cooling or the crack, detachment, etc., caused by heat can be restrained. 
     The opposite side surface of the flow path formation substrate  10  to the communication plate  15  is provided with vibration plates  50 . In this exemplary embodiment, each vibration plate  50  is made up of an elastic film  51  made of silicon oxide that is provided on the flow path formation substrate  10  side and an insulator film  52  made of zirconium oxide that is provided on the elastic film  51 . Liquid flow paths, such as the pressure generation chambers  12 , are formed by performing anisotropic etching on the flow path formation substrate  10  from the side of the one surface thereof (from the side of the surface to which the nozzle plate  20  is joined). Other-side surfaces of the liquid flow paths, such as the pressure generation chambers  12 , are defined by the elastic films  51 . 
     Piezoelectric actuators  130 , an example of a pressure generation unit, are provided on the vibration plates  50  of the flow path formation substrate  10 . Each piezoelectric actuator  130  has a first electrode  60 , a piezoelectric body layer  70 , and a second electrode  80 . Note that a piezoelectric actuator  130  refers to a portion that includes a first electrode  60 , a piezoelectric body layer  70 , and a second electrode  80 . Generally, one of the positive and negative electrodes of the piezoelectric actuators  130  is provided as a common electrode and the other electrode is provided separately for each of the pressure generation chambers  12  by patterning. In this exemplary embodiment, the first electrode  60  is a common electrode continuously extending for the plurality of piezoelectric actuators  130 , while the second electrodes  80  are provided independently for each piezoelectric actuator  130 , forming individual electrodes. Of course, this electrode arrangement may be reversed according to convenience for drive circuits or wiring. Although in the foregoing example, each of the vibration plates  50  is made up of an elastic film  51  and an insulator film  52 , the invention is, of course, not limited to this construction. For example, each vibration plate  50  may include only one of an elastic film  51  and an insulator film  52 . Furthermore, each vibration plate  50  may be made up of only a first electrode  60  that acts also as a vibration plate, without providing the elastic films  51  and the insulator films  52  for the vibration plates  50 . Furthermore, the piezoelectric actuators  130  may be designed to substantially function also as vibration plates. 
     The piezoelectric body layer  70  is made of a piezoelectric material that is an oxide having a polarized structure. For example, the piezoelectric body layer  70  may be made of a perovskite-type oxide represented by a general formula ABO 3 . A lead-based piezoelectric material that contains lead, a non-lead-based piezoelectric material that does not contain lead, etc., may be used. 
     Furthermore, each of the second electrodes  80 , which are the individual electrodes of the piezoelectric actuators  130 , is connected to an end portion of a lead electrode  90  made of, for example, gold (Au) or the like. Each lead electrode  90  is extracted from a vicinity of an end of a corresponding one of the second electrodes  80  which end is remote from a corresponding one of the supply communication paths  19 , and extends onto the corresponding vibration plate  50 . 
     Furthermore, the other end of each lead electrode  90  is connected to the wiring board  121  provided with a drive circuit  120  for driving the piezoelectric actuators  130 . The wiring board  121  may be made of a sheet-shaped substrate that is flexible, for example, a chip-on-film (COF) substrate or the like. 
     One surface of the wiring board  121  is provided with a second terminal  122  that electrically connects to a first terminal  311  of a head substrate  300  (described below). Incidentally, the wiring board  121  does not need to be provided with the drive circuit  120 . That is, the wiring board  121  is not limited to a COF substrate but may be a flat flexible cable (FFC) substrate, a flexible printed circuit (FPC) substrate, etc. 
     The piezoelectric actuator  130 -side surface of the flow path formation substrate  10  is joined to the protective substrate  30  that has substantially the same size as the flow path formation substrate  10 . The protective substrate  30  has holder portions  31  that provide spaces for protecting the piezoelectric actuators  130 . Each holder portion  31  has a recess shape that does not penetrate through the protective substrate  30  in its thickness direction, that is, the third direction Z, but that has an opening on the flow path formation substrate  10  side. The holder portions  31  are provided independently for each row of piezoelectric actuators  130  aligned side by side in the first direction X. 
     That is, in the protective substrate  30 , two holder portions  31  are aligned side by side in the second direction Y so as to house two rows of piezoelectric actuators  130  aligned side by side in the first direction X. Each of the holder portions  31  described above needs merely to have such a space that movements of the piezoelectric actuators  130  are not impeded. The spaces of the holder portions  31  may be tightly sealed or left unsealed. 
     The protective substrate  30  has a through hole  32  that penetrates in the thickness direction, that is, the third direction Z. The through hole  32  is provided between the two holder portions  31  aligned side by side in the second direction Y and extends in the first direction X, that is, the side-by-side alignment direction of the piezoelectric actuators  130 . That is, the through hole  32  is an opening that has longer sides in the side-by-side alignment direction of the plurality of piezoelectric actuators  130 . The other ends of the lead electrode  90  extend so as to be exposed in the through hole  32 , in which the lead electrodes  90  and the wiring board  121  are electrically connected. 
     It is preferable that the protective substrate  30  described above be made of a material that has substantially the same thermal expansion coefficient as the flow path formation substrate  10 , for example, glass, a ceramic material, etc. In this exemplary embodiment, the protective substrate  30  is formed by using the same silicon single crystal substrate as used for the flow path formation substrate  10 . Furthermore, the method for joining the flow path formation substrate  10  and the protective substrate  30  is not particularly limited. For example, in this exemplary embodiment, the flow path formation substrate  10  and the protective substrate  30  are joined by using an adhesive (not shown). 
     The case member  40 , in a plan view, has substantially the same shape as the communication plate  15  and is joined to protective substrate  30  and also to the communication plate  15 . Concretely, the case member  40  has on its protective substrate  30  side a recess portion  41  that has such a depth as to house the flow path formation substrate  10  and the protective substrate  30 . The recess portion  41  has an opening area that is larger than the surface of the protective substrate  30  which is joined to the flow path formation substrate  10 . The nozzle plate  20 -side opening surface of the recess portion  41 , with the flow path formation substrate  10  and the like housed in the recess portion  41 , is sealed by the communication plate  15 . Therefore, along an outer perimeter portion of the flow path formation substrate  10 , third manifold portions  42  are defined by the case member  40 . 
     The first manifold portions  17  and the second manifold portions  18  that are formed in the communication plate  15  and the third manifold portions  42  defined partially by the case member  40  constitute the manifolds  100 . That is, the manifolds  100  include the first manifold portions  17 , the second manifold portions  18 , and the third manifold portions  42 . The manifolds  100  are disposed at both outer sides of the two rows of pressure generation chambers  12  in the second direction Y. The two manifolds  100  provided at both outer sides of the two rows of the pressure generation chambers  12  are provided independently of each other so as not to communicate with each other in the head body  2 . Of course, the two manifolds  100  may be in communication with each other. 
     The case member  40  has introduction ports  44  that communicate with the manifolds  100 . That is, the introduction ports  44  are opening portions that are inlets through which the ink supplied to the head body  2  is introduced into the manifolds  100 . 
     Furthermore, the case member  40  has a connection opening  43  which communicates with the through hole  32  of the protective substrate  30  and through which an end portion of the wiring board  121  is inserted. An opposite end portion of the wiring board  121  extends to a side in a penetrating direction of the through hole  32  and the connection opening  43 , that is, to a side in a third direction Z opposite to the direction in which ink droplets are discharged (i.e., to a negative Z side). 
     As for the material of the case member  40 , for example, a resin, a metal, etc., may be used. Incidentally, if the case member  40  is molded from a resin material, low-cost mass production can be achieved. 
     The compliance substrate  45  is provided on a surface of the communication plate  15  in which the first manifold portions  17  and the second manifold portions  18  have openings. The compliance substrate  45 , in a plan view, has substantially the same size as the communication plate  15  and is provided with a first opening portion  45   a  that exposes the nozzle plate  20 . The compliance substrate  45 , while exposing the nozzle plate  20  through the first opening portion  45   a,  seals the liquid ejection surface  20   a -side openings of the first manifold portions  17  and the second manifold portions  18 . That is, the compliance substrate  45  partially defines the manifolds  100 . 
     The compliance substrate  45  includes a sealing film  46  and a fixture substrate  47 . The sealing film  46  is made of a flexible thin film (e.g., a thin film formed from polyphenylene sulfide (PPS) or the like and having a thickness of 20 μm or less). The fixture substrate  47  is formed from a hard material such as a metal including stainless steel (e.g., a JIS SUS series stainless steel) and the like. Portions of the fixture substrate  47  which face the manifolds  100  are removed completely in the thickness direction to form second opening portions  48 . Therefore, a one-surface-side portion of each manifold  100  forms a compliance portion  49  that is a flexible portion sealed only by the sealing film  46  that has flexibility. In this exemplary embodiment, the compliance portions  49  are provided corresponding one-to-one to the manifolds  100 . That is, in this exemplary embodiment, since the two manifolds  100  are provided, two compliance portions  49  are provided on both sides of the nozzle plate  20  in the second direction Y. 
     In the head body  2  constructed as described above, when ink is ejected, ink is taken through the introduction ports  44  to fill the flow paths extending from the manifolds  100  to the nozzle openings  21 . Then, according to signals from the drive circuit  120 , voltage is applied to piezoelectric actuators  130  that correspond to predetermined pressure generation chambers  12 , so that the piezoelectric actuators  130  undergo flexure deformation together with the adjacent vibration plates  50 . Therefore, the pressure in the pressure generation chambers  12  increases so that ink droplets are ejected from the corresponding nozzle openings  21 . 
     A head  1  that includes the foregoing head body  2  will be described in detail.  FIG. 4  is an exploded perspective view of a head.  FIG. 5  and  FIG. 6  are a plan view and a view of a reverse surface, respectively, of a first flow path member.  FIG. 7  and  FIG. 8  are a plan view and a view of a reverse surface, respectively, of a second flow path member.  FIG. 9  and  FIG. 10  are a plan view and a view of a reverse surface, respectively, of a filter retainer member.  FIG. 11  and  FIG. 12  are a plan view and a view of a reverse surface, respectively, of a third flow path member.  FIG. 13  is a bottom plan view of the head. 
     The head  1  in this exemplary embodiment ejects four color inks of cyan, magenta, yellow, and black as a plurality of kinds of inks. Of course, the number of the kinds of inks is not limited to four and the kinds of inks used are not limited to the foregoing color inks. 
     As shown in  FIGS. 4 to 10 , the head  1  includes four head bodies  2 , a head case  250  that holds the head bodies  2 , and a head substrate  300  supported on the head case  250 . 
     A flow path member  200  has liquid flow paths  500  that supplies inks (liquids) from ink supply units, such as ink cartridges, to the head bodies  2  and also has filters  245  that are provided in the liquid flow paths  500 . Concretely, the flow path member  200  includes a first flow path member  210 , a second flow path member  220 , a filter retainer member  240 , and a third flow path member  230 . 
     The first flow path member  210 , the second flow path member  220 , the filter retainer member  240 , and the third flow path member  230  are integrally formed or connected by, for example, an adhesive, welding, etc. The method for stacking and fixing these members is not particularly limited. For example, screws, clamps, or the like may be used to fix these members. 
     The first flow path member  210  is a member that form upstream flow paths  510  that are portions of the liquid flow paths  500 . Concretely, the first flow path member  210  has on its surface remote from the second flow path member  220  (i.e., its negative Z direction side surface) connection portions  211  that are connected to the liquid supply units in which the inks are held, such as ink cartridges or ink tanks. In this exemplary embodiment, the connection portions  211  are acicularly protruded. The first flow path member  210  is provided with first upstream flow paths  511  that have openings in top surfaces of the connection portions  211  and that perpendicularly penetrate through the first flow path member  210  in its thickness direction (the third direction Z). 
     Incidentally, the connection portions  211  may be connected directly to liquid holder portions, such as ink cartridges, or may also be connected to liquid holder portions, such as ink tanks, via supply pipes such as tubes. 
     The second flow path member  220  forms the upstream flow paths  510  that are portions of the liquid flow paths  500 . Concretely, the first flow path member  210 -side (negative third direction Z-side) surface of the second flow path member  220  is provided with first grooves  225  and recess portions  226  that each communicate with one of two end portions of one of the first grooves  225 . As the second flow path member  220  is joined to the first flow path member  210 , the first grooves  225  and the recess portions  226  are sealed by the first flow path member  210  to form first horizontal flow paths  531  and buffer chambers  533 , respectively. 
     Note that each of the first upstream flow paths  511  of the first flow path member  210  is formed at such a position as to connect to an intermediate portion of a corresponding one of the first horizontal flow paths  531 , so that the liquids supplied from the first upstream flow paths  511 , upon entering the first horizontal flow paths  531 , divide or branch toward their two opposite ends, and thus flow into the buffer chambers  533 . That is, connecting portions of the first upstream flow paths  511  with the first horizontal flow paths  531  are branching portions and the first horizontal flow paths  531  are branched flow paths. 
     In this exemplary embodiment, because the first upstream flow paths  511  connect to intermediate portions of the first horizontal flow paths  531  and thus the paths are each branched to two opposite sides in the first horizontal flow paths  531 , equal and smooth branching can be achieved and, furthermore, the degree of freedom in laying out the branch flow paths can be improved and space saving can be facilitated. For example, first horizontal flow paths  531  may each be formed to have a Y shape in order to have branch flow paths. In this case, however, flow may become stagnant at the branching portion and therefore it is difficult to achieve equal or uniform branching without equalizing pressure losses in the branch flow paths. Thus, the degree of freedom in laying out branch flow paths is restricted and space saving cannot be facilitated. 
     Furthermore, it is preferable that connecting regions of the first horizontal flow paths  531  to which the first upstream flow paths  511  connect be straight portions. This design achieves smooth flows downstream of the branching portions. Even in the case where, for a reason concerning layout, the first upstream flow paths  511  need to be connected to bent portions of the first horizontal flow paths  531 , it is preferable that the connecting portions of the first horizontal flow paths  531  with the first upstream flow paths  511  be linear. 
     Furthermore, the second flow path member  220  is provided with first filter chambers  221  formed on the filter retainer member  240  side (positive Z direction side). The first filter chambers  221  are recess portions formed so that the diameter thereof increases toward the filter retainer member  240  side. The second flow path member  220  is provided with second upstream flow paths  512  that interconnect the first filter chambers  221  and the buffer chambers  533 . The second upstream flow paths  512  are connected to central portions of the first filter chambers  221 . 
     Each of the recess portions  226  that form the buffer chambers  533  has a second upstream flow path  512  at a side opposite to a side that connected to a corresponding one of the first grooves  225 . Furthermore, in each recess portion  226 , two wall members  2261  that divide a flow path into three paths are provided between the second upstream flow path  512  and the connecting side to the first groove  225 . Therefore, liquid having flown into the buffer chambers  533  divides into three flow paths that are a flow path between the wall members  2261  and two flow paths on both outer sides of the wall members  2261 , and then flows from the outer flow paths into the second upstream flow paths  512 . Therefore, even if a gas bubble is trapped and grows large in the flow path between the wall members  2261  of a buffer chamber  533 , choking does not occur because liquid flows from the outer flow paths on outer sides of the wall members  2261  into the second upstream flow path  512 . 
     Furthermore, the second upstream flow paths  512  are circular in section but each have on an inner peripheral wall thereof four grooves  5121  that extend in the flowing direction (the Z direction). Even if a gas bubble in a buffer chamber  533  grows so large as to close the opening of the second upstream flow path  512 , liquid flows through the grooves  5121  and choking does not occur. 
     The first flow path member  210  and the second flow path member  220  as described above form the upstream flow paths  510  that include the first upstream flow paths  511 , the first horizontal flow paths  531 , the buffer chambers  533 , and the second upstream flow paths  512 . 
     The upstream flow paths  510  are, of the liquid flow paths  500  of the flow path member  200 , flow path portions extending from the connection portions  211  to which the liquids are supplied from the ink supply units, such as ink cartridges, to the filters  245  described below. Each upstream flow path  510  branches into two flow paths as the first upstream flow path  511  connects to the first horizontal flow path  531 , and the two branch flow paths extend to corresponding ones of the filters  245 . That is, in each liquid flow path  500 , the first horizontal flow path  531  in the upstream flow path  510  upstream of the filters  245  is divided into two flow paths. 
     The flow path member  200  in this exemplary embodiment includes four upstream flow paths  510  corresponding to the four color inks and the four upstream flow paths  510  are supplied with the four color inks. 
     The filter retainer member  240  has portions of the liquid flow paths  500  and retains the filters  245  provided in the liquid flow paths  500 . Concretely, second filter chambers  242  are formed on a second flow path member  220  side (negative third direction Z side) surface of the filter retainer member  240 . The second filter chambers  242  are each a recess portion formed so that the diameter thereof increases toward the second flow path member  220 . The filter retainer member  240  further has first downstream flow paths  241  that communicate with the second filter chambers  242  and that penetrate through the filter retainer member  240  in its thickness direction (third direction Z). 
     The second filter chambers  242  are formed so as to face the first filter chambers  221  of the second flow path member  220 . Therefore, as the second flow path member  220  and the filter retainer member  240  are joined, the first filter chambers  221  and the second filter chambers  242  together form filter chambers  260 . The filter chambers  260  are spaces that form portions of the liquid flow paths  500 . The filters  245  extend across the spaces of the filter chambers  260 . 
     The second filter chambers  242  are arranged in three rows that are disposed side by side in the first direction X and that are made up of three, two, and three chambers  242 , respectively. That is, a total of eight second filter chambers  242  are provided. This manner of arrangement achieves a space-saving layout of the first horizontal flow paths  531  and the buffer chambers  533  and also achieves a space-saving layout of the second horizontal flow paths  532  described later. 
     The filters  245  remove gas bubbles and undesired matters from the ink. Because the filters  245  are disposed as described above, the inks supplied from the upstream flow paths  510  flow into the first downstream flow paths  241  after undesired matters and gas bubbles in the inks are trapped by the filters  245 . 
     The third flow path member  230  form downstream flow paths  520  that are portions of the liquid flow paths  500 . Concretely, a filter retainer member  240  side (negative third direction Z side) surface of the third flow path member  230  is provided with second grooves  235 . As the third flow path member  230  is joined to the filter retainer member  240 , the second grooves  235  are sealed by the filter retainer member  240  to form second horizontal flow paths  532 . 
     The third flow path member  230  further has second downstream flow path  232  that communicate with the second horizontal flow paths  532  and that penetrate through the third flow path member  230  in its thickness direction (third direction Z). 
     The filter retainer member  240  and the third flow path member  230  as described above form the downstream flow paths  520  that include the first downstream flow paths  241 , the second horizontal flow paths  532 , and the second downstream flow paths  232 . 
     The downstream flow paths  520  are, of the liquid flow paths  500  of the flow path member  200 , portions extending from the filters  245  through the second downstream flow paths  232 . Each of the downstream flow paths  520  does not divide midway but is a single flow path from the filter  245  through the second downstream flow path  232 . 
     The flow path member  200  in this exemplary embodiment has eight downstream flow paths  520  as each of the four upstream flow paths  510 , corresponding to the four color inks, branches into two paths connecting to corresponding two of the downstream flow paths  520 . Details of the foregoing liquid flow paths  500  will be described later. 
     The head case  250  is a member that holds the head bodies  2 . The opposite-side (positive Z-side) surface of the head case  250  to the flow path member  200  is provided with a recess-shaped housing portion  254 . The housing portion  254  has such a size as to house four head bodies  2  disposed so that the nozzle rows  21   a  are aligned side by side in the second direction Y. 
     A flow path member  200 -side (negative Z-side) surface of the head case  250  is provided with a plurality of projected portions  251 . In this exemplary embodiment, the head case  250  is provided with eight projected portions  251 . The eight projected portions  251  are disposed so as to face the eight downstream flow paths  520  that are branched liquid flow paths  500  provided in the flow path member  200 . 
     Each projected portion  251  is provided with a first communication flow path  253  penetrating through the head case  250  in the third direction Z. A top surface of each projected portion  251  (a surface thereof that faces the flow path member  200 ) has an open of the first communication flow path  253 . A housing portion  254  side end of each first communication flow path  253  communicates with a corresponding one of the introduction ports  44  of the case member  40  for the head bodies  2 . 
     Furthermore, the head case  250  is provided with a plurality of first insertion holes  252  through which the wiring boards  121  of the head bodies  2  are inserted. Concretely, the first insertion holes  252  penetrate through the head case  250  in the third direction Z and are formed so as to communicate with the second insertion holes  302  of the head substrate  300 . In this exemplary embodiment, the head case  250  is provided with four first insertion holes  252  corresponding to the wiring boards  121  provided on the four head bodies  2 . 
     The head substrate  300  is supported on the flow path member  200 -side (negative Z-side) surface of the head case  250 . The head substrate  300  is a member to which the wiring boards  121  are connected and on which electric or electronic component parts, such as resistors or circuits that control the liquid ejecting operation of the head  1  and the like via the wiring boards  121 . 
     The flow path member  200 -side surface of the head substrate  300  is provided with terminals to which terminals of the wiring boards  121  are electrically connected. The head substrate  300  is further provided with a plurality of second insertion holes  302  through which the wiring boards  121  electrically connected to the head bodies  2  are inserted. Concretely, the second insertion holes  302  penetrate through the third direction Z so as to communicate with the first insertion holes  252  of the head case  250 . In this exemplary embodiment, the head substrate  300  is provided with four second insertion holes  302  corresponding to the four wiring boards  121  of the four head bodies  2 . 
     The head substrate  300  is further provided with through holes  301  that penetrate through the head substrate  300  in the third direction Z. The projected portions  251  of the head case  250  are inserted through the through holes  301 . In this exemplary embodiment, the head substrate  300  is provided with a total of eight through holes  301  facing the projected portions  251 . 
     Incidentally, the configuration of the through holes  301  that form the head substrate  300  is not limited to what is described above. For example, it suffices that the head substrate  300  is provided with insertion holes, cutouts, or the like so as not to interfere with connection of the projected portions  251  to the downstream flow paths  520 . 
     Each of the wiring boards  121  connected to the head bodies  2  is inserted through the connection opening  43  of a corresponding one of the head bodies  2 , a corresponding one of the first insertion holes  252  of the head case  250 , and a corresponding one of the second insertion holes  302  of the head substrate  300  and is bent to the corresponding terminals on the head substrate  300 . The terminals of the head substrate  300  are electrically connected to the terminals provided on the wiring boards  121 . The manner of this connection between the terminals is not particularly limited. The electrical connection can be achieved by, for example, soldering, welding, pressure bonding with an interposed anisotropic electroconductive adhesive (anisotropic conductive paste (ACP) or anisotropic conductive film (ACF)), an interposed non-electroconductive adhesive (non-conductive paste (NCP) or non-conductive film (NCF)), etc. 
     A seal member  270  for preventing leakage of ink is provided between the head substrate  300  and the third flow path member  230 . The seal member  270  may be made of a material (elastic material) that has liquid resistance to liquids, such as inks used in the head  1 , and that is elastically deformable, for example, rubber, elastomer, etc. 
     Concretely, the seal member  270  is provided with second communication flow paths  271  that penetrate through the seal member  270  in the third direction Z. The seal member  270  is held between the third flow path member  230  and the projected portions  251  inserted through the through holes  301  of the head substrate  300 , with the downstream flow paths  520  and the first communication flow path  253  in communication with each other via the second communication flow paths  271 . In this exemplary embodiment, eight second communication flow paths  271  are formed, corresponding to the eight downstream flow paths  520 , so that the eight downstream flow paths  520  communicate with the first communication flow paths  253  of the eight projected portions  251  of the head case  250 . 
     Thus, the liquid flow paths  500  of the flow path member  200  communicate with the introduction ports  44  of the head bodies  2 , via the first communication flow paths  253  of the head case  250  and the second communication flow paths  271  of the seal member  270 . 
     A cover head  400  is a member to which the head bodies  2  are fixed and which is fixed to the head case  250 . The cover head  400  is provided with opening portions  401  that expose the nozzle openings  21 . In this exemplary embodiment, the opening portions  401  have such a size as to expose the nozzle plates  20 , that is, have substantially the same size and shape as the first opening portions  45   a  of the compliance substrates  45 . 
     The cover head  400  is joined to the opposite side (positive Z side) of each compliance substrate  45  to the communication plates  15  and seals a space on the opposite side of the compliance portions  49  to the manifolds  100 . Because the compliance portions  49  are covered with the cover head  400  in this manner, the compliance portions  49  can be restrained from being broken if a recording medium, such as paper, contacts the compliance portions  49 . Furthermore, the cover head  400  restrains ink from adhering to the compliance portions  49 , and ink adhering to the surface of the cover head  400  can be removed by, for example, a wiper blade or the like, so that the recording medium can be restrained from being stained by ink that adheres to the cover head  400 , or the like. Although not particularly graphically shown in the drawings, the space between the cover head  400  and the compliance portions  49  is open to the atmosphere. Furthermore, the cover heads  400  may also be provided independently for each of the head bodies  2 . 
     The head  1  is formed by stacking the head case  250  on which the head bodies  2  are held, the head substrate  300 , the seal member  270 , and the flow path member  200  as described above. In the head  1  constructed as described above, when the inks are to be ejected, the inks supplied from the connection portions  211  are supplied to the head bodies  2  via the liquid flow paths  500 . Then, control signals from an external apparatus are sent to the head substrate  300 , so that, according to the control signals, the head bodies  2  eject the inks. 
     The liquid flow paths  500  of the head  1  will now be described in detail. First, as shown in  FIG. 13 , each head body  2  has two nozzle rows  21   a  and four head bodies  2  are fixed to the head case  250  and the cover head  400  so that the nozzle rows  21   a  extending in the first direction X are arranged side by side in the second direction Y. 
     In this exemplary embodiment, four color inks are used and the nozzle rows  21   a  that discharge the same color inks are disposed symmetrically about a reference line C that extends in the first direction X. Hereinafter, this arrangement of the nozzle rows  21   a  will be referred to as the symmetrical arrangement. 
     The symmetrical arrangement of the nozzle rows  21   a  refers to an arrangement in which the positional order of the kinds of the inks that are discharged from the nozzle rows  21   a  on one side (e.g., a positive Y side) of the reference line C is opposite to the positional order of the kinds of the inks that are discharged from the nozzle rows  21   a  on the other side (e.g., the negative Y side) of the reference line C. 
     The four nozzle rows  21   a  disposed on the positive Y side of the reference line C will be referred to as the nozzle group L and the four nozzle rows  21   a  disposed on the negative Y side of the reference line C will be referred to as the nozzle group R. In this exemplary embodiment, the positional order of the kinds of the inks discharged from the nozzle rows  21   a  that constitute the nozzle group L is black (K), magenta (M), cyan (C), and yellow (Y) from the negative Y side to the positive Y side. The positional order of the kinds of the inks discharged from the nozzle rows  21   a  that constitute the nozzle group R is yellow (Y), cyan (C), magenta (M), and black (K) from the negative Y side to the positive Y side. 
     As for the manner in which the nozzle rows  21   a  that discharge the same color inks are arranged symmetrically about the reference line C, it suffices that the positional order of the kinds of inks discharged from the nozzle rows  21   a  is symmetrical about the reference line C as stated above. Therefore, it is not necessary that the nozzle rows  21   a  that discharge the same color inks be disposed equidistantly from the reference line C. 
     Although in this exemplary embodiment, two nozzle rows  21   a  are provided in each head body  2 , the relation between the head bodies  2  and nozzle rows  21   a  is not limited to this arrangement. For example, all the nozzle rows  21   a  may be provided in one head body  2  or each head body  2  may be provided with one nozzle row  21   a.    
     The liquid flow paths  500  that supply the inks to the head bodies  2  that have nozzle rows  21   a  that are arranged as described above will be described in detail. 
     First, the first horizontal flow paths  531  of the upstream flow paths  510  that constitute the liquid flow paths  500  will be described. As shown in  FIGS. 5 to 8 , four first horizontal flow paths  531  (first grooves  225 ) are provided corresponding to four color inks and are each divided into two branch paths. In this exemplary embodiment, the branching portion  531   a  of each of the first horizontal flow paths  531  communicates with a corresponding one of the first upstream flow paths  511 . The buffer chambers  533  on the both end portions of the first horizontal flow paths  531  communicate with the second upstream flow paths  512 . Note that in  FIG. 5  to  FIG. 8 , Y, M, C, and K indicate yellow, magenta, cyan, and black as the colors of the inks that flow into the first horizontal flow paths  531 . 
     The first upstream flow paths  511  are disposed so as to coincide, in a plan view, with the connection portions  211  that are inlets through which the inks supplied from the liquid supply units flow in. At the locations that are immediately under the second upstream flow paths  512  and that coincide with the second flow paths  512  in a plan view, the filter chambers  260  are provided. The second upstream flow paths  512  are disposed at central portions of the filter chambers  260 . 
     The first upstream flow paths  511  and the second upstream flow paths  512  are apart from each other in the plan view in  FIG. 7 . The first upstream flow paths  511  and the second upstream flow paths  512  communicate with each other through the first horizontal flow paths  531 . Therefore, although the first upstream flow paths  511  and the second upstream flow paths  512  are apart from each other in a plan view, the inks can be supplied from the first upstream flow paths  511  to the second upstream flow paths  512 . 
     In other words, regardless of the locations, sizes, regions, etc. of the connection portions  211  and the filter chambers  260 , appropriate formation of the first horizontal flow paths  531  and the buffer chambers  533  allows the inks to be supplied from the liquid supply units connected to the connection portions  211  into the filter chambers  260 . 
     Next, the second horizontal flow paths  532  of the downstream flow paths  520  that constitute the liquid flow paths  500  will be described. As shown in  FIGS. 11 and 12 , the eight second horizontal flow paths  532  (the eight second grooves  235  of the third flow path member  230 ) are provided corresponding to the eight filter chambers  260  that communicate with the eight second upstream flow paths  512  corresponding to the eight buffer chambers  533  that communicate with the divided (branched) first horizontal flow paths  531 . In this exemplary embodiment, first end portions  532   a  of the second horizontal flow paths  532  (one end portion of each second horizontal flow path  532 ) communicate with the first downstream flow paths  241  and second end portions  532   b  of the second horizontal flow paths  532  (other end portions thereof) communicate with the second downstream flow paths  232 . Incidentally, Y, M, C, and K in  FIG. 6  indicate yellow, magenta, cyan, and black as the colors of the inks that flow into the filter chambers  260 . Similarly, Y, M, C, and K in  FIG. 11  indicate the colors of the inks that flow into the second horizontal flow paths  532 . 
     The first downstream flow paths  241  are disposed so as to coincide with the filter chambers  260  in a plan view. On the other hand, the second downstream flow paths  232  are disposed so as to coincide, in a plan view, with the introduction ports  44  of the head bodies  2  to which the inks are supplied. It is preferable that each first downstream flow path  241  be disposed as near to a central portion of a corresponding one of the filter chambers  260  as possible. In this exemplary embodiment, of the eight filter chambers  260 , seven filter chambers  260  have at the centers thereof openings of the second downstream flow paths  232  and the other one filter chamber  260  has an opening of the second downstream flow path  232  at a location slightly apart from the center thereof, for convenience in layout. 
     The first downstream flow paths  241  and the second downstream flow paths  232  are disposed apart from each other in a plan view. The first downstream flow paths  241  and the second downstream flow paths  232  communicate with each other through the second horizontal flow paths  532 . Therefore, although the first downstream flow paths  241  and the second downstream flow paths  232  are apart from each other in a plan view, inks can be supplied from the first downstream flow paths  241  to the second downstream flow paths  232 . 
     That is, regardless of the locations, sizes, ranges, or the like of the filter chambers  260  and the introduction ports  44  of the head bodies  2 , formation of the second horizontal flow paths  532  can allow inks to be supplied from the filter chambers  260  to the introduction ports  44  of the head bodies  2 . 
     Because the first horizontal flow paths  531 , which are upstream of the filters  245 , are divided (branched) flow paths, the inks can be guided in an XY plane to locations (introduction ports  44 ) that correspond to the nozzle rows  21   a.  Therefore, the second horizontal flow paths  532 , which are downstream of the filters  245 , can be made short, so that the downstream flow paths  520 , which are downstream of the filters  245  and which require strict management of gas bubbles, can be made short. 
     If gas bubbles occur in the upstream flow paths  510  upstream of the filters  245 , the gas bubbles will be trapped by the filters  245 . Therefore, in the upstream flow paths  510 , strict management of gas bubbles is relatively unnecessary. In the downstream flow paths  520  downstream of the filters  245 , on the other hand, if there occur gas bubbles, for example, passing through the filters  245  or the like, there is risk that the bubbles may be directly supplied to the head bodies  2 ; therefore, strict management of gas bubbles is needed. As a countermeasure to such gas bubbles, the head  1  performs, in order to remove gas bubbles remaining in the downstream flow paths  520 , a cleaning operation in which the inks are sucked from the head bodies  2  periodically or at an arbitrary time to discharge gas bubbles present in the downstream flow paths  520  from the nozzle openings  21  together with the inks. 
     In the head  1  according to this exemplary embodiment, because in the downstream flow paths  520  that requires strict management of gas bubbles, the second horizontal flow paths  532  are made short, it is possible to reduce the amount of time needed for the cleaning operation and reduce the amount of ink discharged for the cleaning operation. 
     Furthermore, in this exemplary embodiment, the first upstream flow paths  511 , which are vertical flow paths, communicate with intermediate portions of the first horizontal flow paths  531 , so that each first horizontal flow path  531  is divided into two opposite branch flow paths. Therefore, path dividing (branching) can be equally and smoothly accomplished. Furthermore, the degree of freedom in laying out branched flow paths can be increased and space saving can be achieved. Furthermore, although the buffer chambers  533  are provided at the ends of the first horizontal flow paths  531 , the first horizontal flow paths  531  are given certain degrees of freedom in the arrangement thereof, the degree of bend thereof, and the lengths thereof to the buffer chambers  533 . It has been confirmed that even if the branch flow paths vary in the foregoing factors, for example, even if the two opposite branch paths are different in the degree of bend or in the length to the buffer chambers  533 , uniform branching can be accomplished. In this exemplary embodiment, the first horizontal flow paths  531  for the yellow, magenta, cyan, and black inks vary in length, the degree of bend, etc. It has been confirmed that even if the degrees of bend of the first horizontal flow paths  531  and the lengths of the portions thereof that extend from the branching portions  531   a  to the buffer chambers  533  vary, a state of uniform branching is achieved. For example, although the first horizontal flow path  531  for the black ink is bent to have a U shape, this bend does not cause a particular problem. 
     Furthermore, it is preferable that connecting portions of the first horizontal flow paths  531  with the first upstream flow paths  511  be linear portions. This will smooth the flows downstream of the branching points. Even in the case where, for the sake of convenience in arrangement, a first upstream flow path  511  has to be connected to a region in a first horizontal flow path  531  in which the first horizontal flow path  531  is bent, it is preferable that at least a connecting portion of the first horizontal flow path  531  with the first upstream flow path  511  be straight. 
     Furthermore, the downstream flow paths  520  downstream of the filters  245  do not branch but simply supply the inks to the head bodies  2 . Therefore, the lengths of the downstream flow paths  520  can be made equal, so that variations in the pressure loss can be restrained and therefore the pressures of the inks supplied to the nozzle rows  21   a  can be made equal. Due to this, variations in ink pressure among the nozzle rows  21   a  can be restrained and high-quality ejection of inks can be achieved. 
     Exemplary Embodiment 2 
     The head  1  described above in conjunction with Exemplary Embodiment 1 is mounted in an ink jet type recording apparatus I.  FIG. 14  is a schematic diagram showing an ink jet type recording apparatus as an example of a liquid ejecting apparatus. 
     In an ink jet type recording apparatus I shown in  FIG. 14 , the head  1  is provided with detachably attached ink cartridges  110 , which are a liquid supply unit. A carriage  3  on which the head  1  is mounted is provided on a carriage shaft  5  attached to the apparatus main body  4 . The carriage  3  is movable along an axis direction of the carriage shaft  5 . 
     As drive force from a driving motor  6  is transmitted to the carriage  3  via a plurality of gears (not graphically shown) and a timing belt  7  so that the carriage  3  on which the head  1  is mounted moves along the carriage shaft  5 . On the other hand, the apparatus main body  4  is provided with a transport roller  8  as a transport unit, so that a recording sheet S that is a recording medium, such as paper, is transported by the transport roller  8 . Incidentally, the transport unit that transports the recording sheet S is not limited to the transport roller but may also be a belt, a drum, etc. 
     Furthermore, one side portion of the apparatus main body  4  in the moving direction of the carriage  3  is provided with a suction unit  9  that contacts the liquid ejection surface  20   a  of the head  1  and that sucks gas bubbles or undesired matters from the nozzle openings  21  together with ink. Using this suction unit  9 , a cleaning operation of sucking inks from the vicinity of the nozzle openings  21  of the head  1 , an initial filling that initially fills the head  1  with the inks, etc. are carried out. 
     Although the foregoing ink jet type recording apparatus I is an example of the liquid ejecting apparatus of the invention in which the head  1  is mounted on the carriage  3  and is thereby moved in the main scanning direction, the invention is not limited to this construction. The invention is also applicable to, for example, a so-called line type recording apparatus that includes a stationary head  1  and that only moves a recording sheet S, such as paper, in the subsidiary scanning direction to perform printing. 
     Furthermore, although in the foregoing example, the ink jet type recording apparatus I has a construction in which the ink cartridges  110 , which are a liquid supply unit, are mounted on the carriage  3 , this does not limit the invention. For example, a liquid supply unit, such as ink tanks, may be fixed to the apparatus main body  4  and the liquid supply unit and the head  1  may be interconnected via supply pipes such as tubes. Furthermore, the liquid supply unit does not necessarily need to be mounted in an ink jet type recording apparatus. 
     Other Exemplary Embodiments 
     While exemplary embodiments of the invention have been described above, a basic construction of the invention is not limited to what have described above. 
     For example, although the head  1  according to Exemplary Embodiment 1 includes the head case  250  that retains the head bodies  2  and the flow path member  200  that supplies the inks to the head bodies  2  through the head case  250  and the seal member  270 , this construction does not limit the invention. For example, a structure in which the head bodies  2  are retained on the flow path member  200  and the inks are supplied from the flow path member  200  directly to the head bodies  2  may be adopted. 
     Furthermore, although the first upstream flow paths  511 , the second upstream flow paths  512 , the first downstream flow paths  241 , and the second downstream flow paths  232 , which constitute the liquid flow paths  500 , are formed along the third direction Z orthogonal to the liquid ejection surfaces  20   a,  this manner of arrangement does not limit the invention. It suffices that these flow paths have components in the third direction Z; for example, the flow paths may be oblique to the third direction Z. 
     Although in the foregoing description, pressure generation units that cause pressure changes in the pressure generation chambers  12  are the thin film-type piezoelectric actuators  130 , this arrangement does not limit the invention. For example, it is possible to use thick film-type piezoelectric actuators formed by, for example, a method in which a green sheet is stuck, longitudinal vibration-type piezoelectric actuators that are formed by alternately stacking piezoelectric materials and electrode formation materials and that are expanded and contracted in their axis directions, etc. Furthermore, the pressure generation unit may be a pressure generation unit in which a heating element is disposed in a pressure generation chamber and the heating element is caused to produce heat that generates a gas bubble whereby a liquid droplet is discharged from a nozzle opening, a so-called electrostatic actuator in which static electricity is generated between a vibration plate and an electrode and, by electrostatic force, the vibration plate is deformed to discharge a liquid droplet from a nozzle opening. 
     Furthermore, the invention has been made broadly for liquid ejecting heads in general and is applicable to, for example, various recording heads, such as ink jet type recording heads, for use in image recording apparatuses, such as printers, color material ejecting heads for use in producing color filters for liquid crystal displays and the like, electrode material ejecting heads for use in forming electrodes for organic electroluminescent (EL) displays, field emission displays (FEDs), etc., bioorganic material ejecting heads for use in producing biochips, etc. 
     The entire disclosure of Japanese Patent Application No. 2016-065749, filed Mar. 29, 2016 is expressly incorporated by reference herein.