Patent Publication Number: US-11654682-B2

Title: Liquid discharge head

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a continuation of U.S. patent application Ser. No. 16/561,364 filed Sep. 5, 2019, which is a continuation of U.S. patent application Ser. No. 15/849,766 filed Dec. 21, 2017, issued as U.S. Pat. No. 10,442,199 on Oct. 15, 2019, which is a continuation of U.S. patent application Ser. No. 15/080,852 filed Mar. 25, 2016, issued as U.S. Pat. No. 9,878,539 on Jan. 30, 2018, which claims priority from Japanese Patent Application No. 2015-074356 filed on Mar. 31, 2015, the disclosures of which are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present invention relates to a liquid discharge apparatus which discharges liquid from nozzles, and a liquid discharge apparatus unit. 
     Description of the Related Art 
     In the case of an ink-jet head described in Japanese Patent Application Laid-open No. 2014-195929, nozzle arrays, each of which is formed by aligning a plurality of nozzles in a transport direction, are arranged in four arrays in a scanning direction. Further, manifold flow passages, which extend in the transport direction, are arranged in the scanning direction between the first nozzle array and the second nozzle array as counted from the left side and between the first nozzle array and the second nozzle array as counted from the right side, respectively. 
     SUMMARY 
     In this context, as described above, the ink-jet head as described in Japanese Patent Application Laid-open No. 2014-195929 has such a structure that the manifold flow passage is arranged between the two nozzle arrays in the scanning direction. On the other hand, in the case of the ink-jet head described in Japanese Patent Application Laid-open No. 2014-195929, in order that the pressure wave, which is generated in a pressure chamber when a piezoelectric actuator is driven and which is transmitted to the manifold flow passage, is sufficiently attenuated in the manifold flow passage, it is necessary that the width (length in the scanning direction) of the manifold flow passage should be widened to some extent. When the width of the manifold flow passage is widened, the size of the ink-jet head is consequently increased in the scanning direction. 
     An object of the present teaching is to provide a liquid discharge apparatus and a liquid discharge apparatus unit which make it possible to widen the width of a manifold flow passage which is common to a plurality of nozzles, while suppressing the increase in size of the apparatus. 
     According to an aspect of the present teaching, there is provided a liquid discharge apparatus including: an individual flow passage member; and a common flow passage member which is joined to the individual flow passage member in a first direction, wherein the individual flow passage member has nozzle groups formed on a surface on a side opposite to the common flow passage member in the first direction and connecting hole groups formed on another surface on a side of the common flow passage member in the first direction, the common flow passage member has manifold flow passages formed corresponding to the connecting hole groups respectively, each of the nozzle groups includes nozzles aligned in a second direction orthogonal to the first direction, each of the connecting hole groups includes connecting holes aligned in the second direction and connected to the nozzles respectively, each of the manifold flow passages extends in the second direction and is connected to the nozzles via the connecting holes, the nozzle groups are arranged in a third direction orthogonal to both of the first direction and the second direction, the connecting hole groups are arranged in the third direction, the manifold flow passages are arranged in the third direction, and at least one spacing between the manifold flow passages is larger than a spacing between the connecting hole groups in the third direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    depicts a schematic arrangement of a printer according to a first embodiment. 
         FIG.  2    depicts a plan view illustrating an ink-jet head depicted in  FIG.  1   . 
         FIG.  3    depicts a sectional view taken along a line III-III in  FIG.  2   . 
         FIG.  4    depicts a sectional view taken along a line IV-IV in  FIG.  2   . 
         FIG.  5    depicts a plan view illustrating a head chip. 
         FIG.  6    depicts an enlarged view illustrating a part of  FIG.  5   . 
         FIG.  7 A  depicts a sectional view taken along a line VIIA-VIIA in  FIG.  6   , and 
         FIG.  7 B  depicts a sectional view taken along a line VIIB-VIIB in  FIG.  6   . 
         FIG.  8    depicts those in  FIG.  2    from which a damper film, a plate, and filters are removed. 
         FIG.  9    depicts those in  FIG.  8    from which a first common flow passage member is removed. 
         FIG.  10    depicts a drawing of a second embodiment corresponding to  FIG.  1   . 
         FIG.  11    depicts a plan view illustrating an ink-jet head according to a first modified embodiment, from which a damper film, a plate, and filters are removed. 
         FIG.  12    depicts a plan view illustrating an ink-jet head according to a second modified embodiment, from which a damper film, a plate, and filters are removed. 
         FIG.  13    depicts a sectional view illustrating an ink-jet head according to a third modified embodiment. 
         FIG.  14    depicts a sectional view illustrating an ink-jet head according to a fourth modified embodiment. 
         FIGS.  15 A and  15 B  depict sectional views illustrating an ink-jet head according to modified embodiments 5A and 5B, respectively. 
         FIG.  16    depicts a sectional view illustrating an ink-jet head according to a sixth modified embodiment. 
         FIG.  17    depicts a plan view illustrating an ink-jet head according to a seventh modified embodiment. 
         FIG.  18    depicts a sectional view illustrating an ink-jet head according to an eighth modified embodiment. 
         FIG.  19    depicts a sectional view illustrating an ink-jet head according to a ninth modified embodiment. 
         FIG.  20    depicts a sectional view illustrating an ink-jet head according to a tenth modified embodiment. 
         FIG.  21    depicts a sectional view illustrating an ink-jet head according to an eleventh modified embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
     A first embodiment of the present teaching will be explained below. 
     &lt;Overall Structure of Printer&gt; 
     As depicted in  FIG.  1   , a printer  1  according to a first embodiment comprises, for example, a carriage  2 , an ink-jet head  3 , two recording paper transport rollers  4 , and a platen  5 . The carriage  2  is supported by two guide rails  6  extending in the scanning direction, and the carriage  2  is movable in the scanning direction along with the guide rails  6 . Note that the following explanation will be made while defining the right side and the left side in the scanning direction as depicted in  FIG.  1   . 
     The ink-jet head  3  is carried on the carriage  2 , and the ink-jet head  3  discharges inks from a plurality of nozzles  15  formed on the lower surface thereof. The structure of the ink-jet head  3  will be explained in detail later on. The two recording paper transport rollers  4  are arranged on the both sides of the carriage  2  in the direction orthogonal to the scanning direction, and the two recording paper transport rollers  4  transport the recording paper P in the transport direction. The platen  5  is arranged opposingly to the ink-jet head  3  between the two recording paper transport rollers  4  in the transport direction, and the platen  5  supports, from the lower side, the recording paper P transported by the recording paper transport rollers  4 . 
     Then, the printer  1  performs the printing on the recording paper P by discharging the inks from the ink-jet head  3  which is reciprocatively moved in the scanning direction together with the carriage  2 , while transporting the recording paper P by means of the recording paper transport rollers  4 . 
     &lt;Ink-Jet Head&gt; 
     Next, the ink-jet head  3  will be explained in detail. As depicted in  FIGS.  2  and  3   , the ink-jet head  3  is provided with a head chip  11 , a support substrate  12 , and a manifold unit  13 . However, in  FIG.  3   , for example, the heights of recesses  37  and piezoelectric actuators  24  described later on are depicted to be high in order to show the drawing more comprehensively. 
     As depicted in  FIGS.  5  to  7 B , the head chip  11  is provided with a nozzle plate  21 , a pressure chamber plate  22 , a vibration film  23 , and eight piezoelectric actuators  24 . However, in  FIGS.  5  and  6   , the positions of the support substrate  12  and the recess  37  described later on are depicted by alternate long and two short dashes lines. 
     The nozzle plate  21  is composed of, for example, a synthetic resin material. The nozzle plate  21  is formed with a plurality of nozzles  15 . The plurality of nozzles  15  form nozzle arrays  31  by being aligned in the transport direction. Further, the nozzle arrays  31  are aligned in eight arrays in the scanning direction on the nozzle plate  21 . Further, the plurality of nozzles  15 , which form the odd-numbered nozzle array as counted from the right side in the scanning direction, are deviated to the downstream side in the transport direction by a length which is a half of the spacing (spacing distance or interval) between the nozzles  15  in each of the nozzle arrays  31 , with respect to the plurality of nozzles  15  which form the even-numbered nozzle array  31 . 
     Then, the black ink is discharged from the plurality of nozzles  15  which form a nozzle group  32  constructed by the first and second nozzle arrays  31  as counted from the right side in the scanning direction. The yellow ink is discharged from the plurality of nozzles  15  which form a nozzle group  32  constructed by the third and fourth nozzle arrays  31  as counted from the right side. The cyan ink is discharged from the plurality of nozzles  15  which form a nozzle group  32  constructed by the fifth and sixth nozzle arrays  31  as counted from the right side. The magenta ink is discharged from the plurality of nozzles  15  which form a nozzle group  32  constructed by the seventh and eighth nozzle arrays  31  as counted from the right side. 
     The pressure chamber plate  22  is composed of, for example, silicon (Si), and the pressure chamber plate  22  is arranged on the upper surface of the nozzle plate  21 . The pressure chamber plate  22  is formed with a plurality of pressure chambers  10 . The plurality of pressure chambers  10  are provided individually with respect to the plurality of nozzles  15 . The pressure chamber  10 , which corresponds to the nozzle  15  for forming the odd-numbered nozzle array  31  as counted from the right side in the scanning direction, is overlapped with the nozzle  15  at the right end portion. The pressure chamber  10 , which corresponds to the nozzle  15  for forming the even-numbered nozzle array  31  as counted from the right side in the scanning direction, is overlapped with the nozzle  15  at the left end portion. Then, the plurality of pressure chambers  10  are arranged as described above, and thus the plurality of pressure chambers  10  form pressure chamber arrays  33  of eight arrays corresponding to the eight arrays of the nozzle arrays  31 . 
     The vibration film  23  is composed of an insulative material such as silicon dioxide (SiO 2 ) or the like, and the vibration film  23  is arranged on the upper surface of the pressure chamber plate  22 . The vibration film  23  extends continuously while ranging over the plurality of pressure chambers  10 , and the vibration film  23  covers the plurality of pressure chambers  10 . 
     The eight piezoelectric actuators  24  are provided corresponding to the eight arrays of the pressure chamber arrays  33 . Each of the piezoelectric actuators  24  is provided with a piezoelectric layer  41 , a common electrode  42 , and a plurality of individual electrodes  43 . The piezoelectric layer  41  is composed of a piezoelectric material containing a main component of lead titanate zirconate, and the piezoelectric layer  41  extends continuously in the transport direction while ranging over the plurality of pressure chambers  10  for forming the pressure chamber array  33 . The common electrode  42  is composed of a conductive material such as a metal or the like, and the common electrode  42  is arranged over the substantially entire region of the lower surface of the piezoelectric layer  41 . The common electrode  42  is always retained at the ground electric potential. The plurality of individual electrodes  43  are provided individually with respect to the plurality of pressure chambers  10 , and the plurality of individual electrodes  43  are overlapped with the corresponding pressure chambers  10 . The plurality of individual electrodes  43  are connected to unillustrated driver IC. Any one of the ground electric potential and a predetermined driving electric potential of about 20 V is selectively applied by the driver IC to the plurality of individual electrodes  43  respectively. Further, corresponding to the arrangement of the common electrode  42  and the plurality of individual electrodes  43 , the portions, which are interposed between the common electrode  42  of the piezoelectric layer  41  and the respective individual electrodes  43 , are polarized in the thickness direction respectively. 
     &lt;Method for Driving Piezoelectric Actuator&gt; 
     An explanation will now be made about a method for driving the piezoelectric actuator  24  to discharge the inks from the nozzles  15 . In the ink-jet head  3 , all of the individual electrodes  43  are previously retained at the ground electric potential. In order to discharge the ink from the nozzle  15 , the electric potential of the corresponding individual electrode  43  is switched from the ground electric potential to the driving electric potential. Accordingly, an electric field, which is parallel to the polarization direction, is generated at the portion of the piezoelectric layer  41  interposed between the electrodes in accordance with the electric potential difference between the individual electrode  43  and the common electrode  42 . In accordance with this electric field, the concerning portion of the piezoelectric layer  41  is shrunk in the in-plane direction which is orthogonal to the polarization direction. Accordingly, the piezoelectric layer  41  and the vibration film  23  are deformed as a whole to protrude toward the side of the pressure chamber  10 , and the volume of the pressure chamber  10  is decreased. As a result, the pressure of the ink contained in the pressure chamber  10  is raised, and the ink is discharged from the nozzle  15  communicated with the pressure chamber  10 . 
     &lt;Support Substrate&gt; 
     The support substrate  12  is composed of, for example, silicon (Si), and the support substrate  12  is arranged on the upper surface of the vibration film  23 . The length in the scanning direction of the support substrate  12  is shorter than the plates  21 ,  22 . The plates  21 ,  22  protrude from the support substrate  12  on the both sides in the scanning direction. A plurality of throttle flow passages  16 , which extend in the upward-downward direction and which penetrate through the support substrate  12  and the vibration film  23 , are formed at portions of the support substrate  12  and the vibration film  23  overlapped with end portions of the plurality of pressure chambers  10  disposed on the side opposite to the nozzles  15  in the scanning direction. Accordingly, the plurality of throttle flow passages  16  form eight arrays of throttle flow passage arrays  35  corresponding to the eight arrays of the nozzle arrays  31 . Further, the first and second throttle flow passage arrays  35  as counted from the right side, the third and fourth throttle flow passage arrays  35  as counted from the right side, the fifth and sixth throttle flow passage arrays  35  as counted from the right side, and the seventh and eighth throttle flow passage arrays  35  as counted from the right side are arranged closely to one another in the scanning direction respectively to thereby form throttle flow passage groups  36   a  to  36   d . Further, recesses  37  are formed at portions of the lower surface of the support substrate  12  overlapped with the respective piezoelectric actuators  24 . The piezoelectric actuator  24  is accommodated in the recess  37 . 
     &lt;Common Flow Passage Member&gt; 
     The manifold unit  13  is joined to the upper surface of the support substrate  12 . The manifold unit  13  is provided with a first common flow passage member  51 , a second common flow passage member  52 , a damper film  53 , a plate  54 , and filters  55 . 
     The common flow passage members  51 ,  52  are composed of, for example, ceramic. As depicted in  FIGS.  3  and  8   , the first common flow passage member  51  and the second common flow passage member  52  are stacked in the upward-downward direction so that the second common flow passage member  52  is disposed on the lower side. The second common flow passage member  52  is joined to the upper surface of the support substrate  12 . The lengths in the scanning direction of the common flow passage members  51 ,  52  are longer than the support substrate  12  and the plates  21 ,  22 . The both ends in the scanning direction protrude from the support substrate  12  and the head chip  11 . The common flow passage members  51 ,  52  are formed with four manifold flow passages  61  to  64  and four connecting flow passages  66  to  69 . 
     The four manifold flow passages  61  to  64  are formed at portions of the first common flow passage member  51  except for the lower end portions. The manifold flow passages  61  to  64  extend in the transport direction respectively, and the manifold flow passages  61  to  64  are aligned in the scanning direction. The manifold flow passage  61 , which is arranged on the rightmost side, is positioned on the right side as compared with the throttle flow passage group  36   a , and the manifold flow passage  61  is not overlapped with the throttle flow passage group  36   a . The second manifold flow passage  62  as counted from the right side is overlapped with the throttle flow passage group  36   b  at the left end portion. The third manifold flow passage  63  as counted from the right side is overlapped with the throttle flow passage group  36   c  at the right end portion. The manifold flow passage  64 , which is arranged on the leftmost side, is positioned on the left side as compared with the throttle flow passage group  36   d , and the manifold flow passage  64  is not overlapped with the throttle flow passage group  36   d . Accordingly, the spacing D 1  between the manifold flow passages  61  to  64  is larger than the spacing D 2  between the throttle flow passage groups  36   a  to  36   d . Specifically, the spacing D 1  is about 1.5 to 2.5 times the spacing D 2 . For example, the spacing D 1  is about 1.5 mm, and the spacing D 2  is about 1 mm. Further, as for the manifold flow passages  61  to  64 , the widths are identical, which are W 1 . The lengths in the transport direction are identical as well. Accordingly, as for the manifold flow passages  61  to  64 , the volumes are identical as well. Further, the width W 1  of each of the manifold flow passages is larger than the spacing D 2  between the throttle flow passage groups  36   a  to  36   d.    
     The spacing between the manifold flow passages  61  to  64 , which is referred to herein, is the spacing between the mutually corresponding portions of the manifold flow passages  61  to  64  such as, for example, the spacing between the central positions in the scanning direction of the respective manifold flow passages  61  to  64  depicted in  FIG.  3   . Further, the spacing D 2  between the throttle flow passage groups  36   a  to  36   d  is the spacing between the corresponding portions of the throttle flow passage groups  36   a  to  36   d  such as, for example, the spacing between the throttle flow passage arrays disposed on the left side of the two throttle flow passage arrays  35  for constructing each of the throttle flow passage groups  36   a  to  36   d  depicted in  FIG.  3   . 
     The four connecting flow passages  66  to  69  are formed while ranging over the lower end portions of the first common flow passage member  51  and the second common flow passage member  52 . The connecting flow passages  66  to  69  extend in the transport direction respectively, and the connecting flow passages  66  to  69  are aligned in the scanning direction. Further, each of the connecting flow passages  66  to  69  has the width in the scanning direction. 
     Further, the connecting flow passage  66 , which is disposed on the rightmost side, extends so that the position thereof is lowered toward the left side in the scanning direction. Then, the connecting flow passage  66  is communicated with the left lower end portion of the manifold flow passage  61  at the right upper end portion thereof, and the connecting flow passage  66  is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   a  at the left lower end portion thereof. Further, the lower surface  66   a  of the connecting flow passage  66  is formed to have a stepped shape so that the position thereof is lowered toward the left side in the scanning direction, corresponding to the connecting flow passage  66  extending as described above. In other words, the lower surface  66   a  of the connecting flow passage  66  is formed to have the stepped shape directed toward the corresponding throttle flow passage group  36   a . Further, a plurality of protruding portions  66   b , which protrude upwardly, are formed on the lower surface  66   a  of the connecting flow passage  66  at portions overlapped with a partition wall  51   a  of the first common flow passage member  51  for partitioning the manifold flow passage  61  and the manifold flow passage  62 . The plurality of protruding portions  66   b  are aligned in the transport direction, and upper end portions thereof are joined to the lower surface of the partition wall  51   a  of the first common flow passage member  51 . Further, as depicted in  FIG.  9   , both end surfaces  66   c  of the protruding portion  66   b  in the transport direction have circular arc-shaped curved surfaces as viewed from an upper position. 
     The second connecting flow passage  67  as counted from the right side extends in the upward-downward direction. The connecting flow passage  67  is communicated with the left lower end portion of the manifold flow passage  62  at the upper end portion thereof. The connecting flow passage  67  is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   b  at the lower end portion thereof. The third connecting flow passage  68  as counted from the right side extends in the upward-downward direction. The connecting flow passage  68  is communicated with the right lower end portion of the manifold flow passage  63  at the upper end portion thereof. The connecting flow passage  68  is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   c  at the lower end portion thereof. 
     The connecting flow passage  69 , which is disposed on the leftmost side, extends so that the position thereof is lowered toward the right side in the scanning direction. Then, the connecting flow passage  69  is communicated with the right lower end portion of the manifold flow passage  64  at the left upper end portion thereof, and the connecting flow passage  69  is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   d  at the right lower end portion thereof. Further, the lower surface  69   a  of the connecting flow passage  69  is formed to have a stepped shape so that the position thereof is lowered toward the right side in the scanning direction, corresponding to the connecting flow passage  69  extending as described above. In other words, the lower surface  69   a  of the connecting flow passage  69  is formed to have the stepped shape directed toward the corresponding throttle flow passage group  36   d . Further, a plurality of protruding portions  69   b , which protrude upwardly, are formed on the lower surface  69   a  of the connecting flow passage  69  at portions overlapped with a partition wall  51   b  of the first common flow passage member  51  for partitioning the manifold flow passage  63  and the manifold flow passage  64 . The plurality of protruding portions  69   b  are aligned in the transport direction, and upper end portions thereof are joined to the lower surface of the partition wall  51   b  of the first common flow passage member  51 . Further, as depicted in  FIG.  9   , both end surfaces  69   c  of the protruding portion  69   b  in the transport direction have circular arc-shaped curved surfaces as viewed from an upper position. 
     Further, the partition wall  38   a  of the support substrate  12  described above, which partitions the second and third recesses  37  as counted from the right side, is arranged to be overlapped with the partition wall  52   a  of the second flow passage forming member  52  which mutually partitions the connecting portions of the connecting flow passage  66  and the connecting flow passage  67  with respect to the throttle flow passages  16 . Further, the partition wall  38   b  of the support substrate  12 , which partitions the fourth and fifth recesses  37  as counted from the right side, is arranged to be overlapped with the partition wall  52   b  of the second flow passage forming member  52  which mutually partitions the connecting portions of the connecting flow passage  67  and the connecting flow passage  68  with respect to the throttle flow passages  16 . Further, the partition wall  38   c  of the support substrate  12 , which partitions the sixth and seventh recesses  37  as counted from the right side, is arranged to be overlapped with the partition wall  52   c  of the second flow passage forming member  52  which mutually partitions the connecting portions of the connecting flow passage  68  and the connecting flow passage  69  with respect to the throttle flow passages  16 . 
     The damper film  53  is joined to the upper surface of the first common flow passage member  51 , and the damper film  53  extends continuously over the four manifold flow passages  61  to  64 . Accordingly, the portions of the damper film  53 , which are overlapped with the manifold flow passages  61  to  64 , serve as damper films  53   a  for forming upper wall surfaces of the manifold flow passages  61  to  64  respectively. The pressure wave is generated in the pressure chamber  10  when the piezoelectric actuator  24  is driven. The pressure wave is transmitted to the manifold flow passage  61  to  64 . In this situation, the damper film  53   a  is deformed, and thus the pressure wave can be attenuated. 
     The plate  54  is joined to the upper surface of the damper film  53 . Ink introducing ports  71 , which penetrate through the plate  54  and the damper film  53  respectively, are formed at portions of the plate  54  and the damper film  53  overlapped with the both end portions of the manifold flow passages  61  to  64  in the transport direction. The respective ink introducing ports  71  are connected to unillustrated ink cartridges, for example, via unillustrated tubes. The inks are introduced into the manifold flow passages  61  to  64  from the ink introducing ports  71 . Further, through-holes  72 , which extend in the transport direction, are formed at portions of the plate  54  overlapped with portions except for the both end portions of the manifold flow passages  61  to  64 . Accordingly, the deformation of the damper film  53   a  is not inhibited by the plate  54 . 
     The filters  55  are joined to the both end portions in the transport direction of the upper surface of the plate  54 , and the filters  55  cover the ink introducing ports  71 . Accordingly, when the inks are introduced from the ink introducing ports  71  into the manifold flow passages  61  to  64 , any bubble, foreign matter and the like contained in the inks are captured by the filters  55 . The bubble and the foreign matter are prevented from flowing into the manifold flow passages  61  to  64 . 
     According to the embodiment explained above, the manifold flow passages  61  to  64  are arranged on the upper side of the head chip  11  and the support substrate  12 , and the spacing D 1  between the manifold flow passages  61  to  64  is larger than the spacing D 2  between the throttle flow passage groups  36   a  to  36   d . Accordingly, the widths of the manifold flow passages  61  to  64  can be widened (lengths in the scanning direction can be lengthened), and the volumes of the manifold flow passages  61  to  64  can be increased, while suppressing the increase in size of the ink-jet head  3  in the scanning direction, as compared with a case in which manifold flow passages are formed in a head chip and nozzles and the manifold flow passages are arranged while being aligned in the scanning direction. As a result, the pressure wave, which is transmitted to the manifold flow passages  61  to  64 , can be efficiently attenuated. 
     Further, in the first embodiment, the upper wall surfaces of the manifold flow passages  61  to  64  are formed by the damper film  53   a . Therefore, when the pressure of the ink in the manifold flow passage  61  to  64  is fluctuated, then the damper film  53   a  is deformed, and thus it is possible to attenuate the pressure wave more reliably. 
     Further, when the spacing D 1  between the manifold flow passages  61  to  64  is not less than 1.5 times and not more than 2.5 times the spacing D 2  between the throttle flow passage groups  36   a  to  36   d  as in the first embodiment, it is possible to reliably attenuate the pressure wave in the manifold flow passages  61  to  64 , while shortening the length in the scanning direction of the ink-jet head  3  (manifold unit  13 ) as much as possible. 
     Further, in the first embodiment, the manifold flow passages  61  to  64  have the same volume. Therefore, no dispersion arises among the throttle flow passage arrays  35  in relation to the amount of the ink supplied from the throttle flow passage  16 . Accordingly, it is possible to obtain the uniform ink discharge characteristic for the ink discharged from the plurality of nozzles  15  for forming each of the nozzle arrays  31 . 
     Further, in the first embodiment, the ink introducing ports  71  are arranged at the positions overlapped with the both end portions in the transport direction of the manifold flow passages  61  to  64 . Therefore, it is possible to suppress the increase in size of the ink-jet head  3  in the scanning direction, for example, as compared with a case in which ink introducing ports are arranged on the outer side in the scanning direction as compared with the manifold flow passages  61  to  64 . Further, it is possible to reliably supply the inks to the entire regions of the manifold flow passages  61  to  64  as compared with a case in which the ink introducing ports  71  are arranged at only positions overlapped with the end portions on one side in the transport direction of the manifold flow passages  61  to  64 . 
     Further, in the first embodiment, the filters  55  for covering the ink introducing ports  71  are provided. Therefore, when the inks flow into the manifold flow passages  61  to  64  from the ink introducing ports  71 , the bubble and the foreign matter contained in the inks can be captured by the filters  55 . It is possible to prevent the bubble and the foreign matter from flowing into the ink-jet head  3 . 
     Further, in the first embodiment, the manifold flow passage  61  is positioned on the right side as compared with the throttle flow passage group  36   a , and the connecting flow passage  66  extends so that the position thereof is lowered toward the left side in the scanning direction. Accordingly, the ink easily flows from the manifold flow passage  61  into the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   a . Similarly, in the first embodiment, the manifold flow passage  64  is positioned on the left side as compared with the throttle flow passage group  36   d , and the connecting flow passage  69  extends so that the position thereof is lowered toward the right side in the scanning direction. Accordingly, the ink easily flows from the manifold flow passage  64  into the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   d.    
     Further, in the first embodiment, the portions of the common flow passage members  51 ,  52 , at which the manifold flow passage  61  is formed, protrude from the support substrate  12  to the right side in the scanning direction. Further, the portions of the common flow passage members  51 ,  52 , at which the manifold flow passage  64  is formed, protrude from the support substrate  12  to the left side in the scanning direction. Therefore, if the rigidities of the protruding portions are low, it is feared that the common flow passage members  51 ,  52  may be deformed when the common flow passage members  51 ,  52  are joined to the support substrate  12 . Further, the portions, which are included in the portions of the common flow passage members  51 ,  52  protruding from the support substrate  12  and which are separated farther from the support substrate  12 , are deformed more easily when the rigidity is low. 
     In relation thereto, in the first embodiment, the lower surface  66   a  of the connecting flow passage  66  is formed to have the stepped shape so that the position of the lower surface  66   a  of the connecting flow passage  66  is lowered toward the left side in the scanning direction. Accordingly, the portion of the second common flow passage member  52 , which protrudes to the right side from the support substrate  12 , has the thickness which is more increased at the position farther from the support substrate  12  in the scanning direction. Similarly, the lower surface  69   a  of the connecting flow passage  69  is formed to have the stepped shape so that the position of the lower surface  69   a  of the connecting flow passage  69  is lowered toward the right side in the scanning direction. Accordingly, the portion of the second common flow passage member  52 , which protrudes to the left side from the support substrate  12 , has the thickness which is more increased at the position farther from the support substrate  12  in the scanning direction. According to the facts as described above, in the first embodiment, it is possible to secure the rigidities of the portions of the common flow passage members  51 ,  52  protruding from the support substrate  12  in the scanning direction. It is possible to prevent the common flow passage members  51 ,  52  from being deformed when the common flow passage members  51 ,  52  are joined to the support substrate  12 . 
     Further, in the first embodiment, the plurality of protruding portions  66   b  are formed at the portions of the lower surface  66   a  of the connecting flow passage  66  overlapped in the upward-downward direction with the partition wall  51   a  of the first common flow passage member  51  for partitioning the manifold flow passage  61  and the manifold flow passage  62 . The upper end portions of the protruding portions  66   b  are joined to the lower surface of the partition wall  51   a  of the first common flow passage member  51 . Accordingly, it is possible to avoid such a situation that the portion to serve as the partition wall  51   a  of the first common flow passage member  51  is deformed to the lower side when the first common flow passage member  51  and the second common flow passage member  52  are joined to one another. 
     Similarly, in the first embodiment, the plurality of protruding portions  69   b  are formed at the portions of the lower surface  69   a  of the connecting flow passage  69  overlapped in the upward-downward direction with the partition wall  51   b  of the first common flow passage member  51  for partitioning the manifold flow passage  63  and the manifold flow passage  64 . The upper end portions of the protruding portions  69   b  are joined to the lower surface of the partition wall  51   b  of the first common flow passage member  51 . Accordingly, it is possible to avoid such a situation that the portion to serve as the partition wall  51   b  of the first common flow passage member  51  is deformed to the lower side when the first common flow passage member  51  and the second common flow passage member  52  are joined to one another. 
     Further, in the first embodiment, the both end surfaces  66   c ,  69   c  in the transport direction of the protruding portions  66   b ,  69   b  have the circular arc-shaped curved surfaces as viewed from the upper side. Accordingly, it is possible to provide such a structure that the bubbles hardly stay at the end surfaces  66   c ,  69   c.    
     Further, in the first embodiment, the partition walls  38   a  to  38   c , which mutually partition the recesses  37 , are arranged at the portions of the support substrate  12  overlapped with the partition walls  52   a  to  52   c  for mutually partitioning the connecting portions of the connecting flow passages  66  to  69  with respect to the throttle flow passages  16 . Accordingly, it is possible to avoid such a situation that the support substrate  12  is pushed by the partition walls  52   a  to  52   c  and the recesses  37  are consequently crushed when the common flow passage members  51 ,  52  are joined to the support substrate  12 . As a result, it is possible to avoid any damage of the piezoelectric actuator  24 . 
     Note that in the first embodiment, the pressure chamber plate  22  corresponds to the pressure chamber forming member according to the present teaching, and the support substrate  12  corresponds to the connecting hole forming member according to the present teaching. Then, the combination of the nozzle plate  21 , the pressure chamber plate  22 , the vibration film  23 , and the support substrate  12  corresponds to the individual flow passage member according to the present teaching. Further, the combination of the nozzle  15 , the pressure chamber  10 , and the throttle flow passage  16  which are communicated with each other corresponds to the individual flow passage according to the present teaching. Further, the throttle flow passage  16  corresponds to the connecting hole according to the present teaching, and the throttle flow passage group  36   a  to  36   d  corresponds to the connecting hole group according to the present teaching. Further, the manifold unit  13  corresponds to the common flow passage member according to the present teaching. Further, the combination of the manifold flow passage  61  to  64  and the connecting flow passage  66  to  69  corresponds to the common flow passage according to the present teaching. Further, the upward-downward direction corresponds to the first direction according to the present teaching, the transport direction corresponds to the second direction according to the present teaching, and the scanning direction corresponds to the third direction according to the present teaching. 
     Second Embodiment 
     Next, a preferred second embodiment of the present teaching will be explained. As depicted in  FIG.  10   , a printer  100  according to the second embodiment comprises a head unit  101  which is arranged between two recording paper transport rollers  4  in the transport direction. 
     The head unit  101  has six ink-jet heads  3  and a holding plate  103 . The ink-jet heads  3  are arranged in such a direction that the nozzle alignment direction, in which a plurality of nozzles  15  (see  FIG.  5   ) are aligned, is orthogonal to the transport direction. Further, each three of the six ink-jet heads  3  are aligned in the nozzle alignment direction to form two head arrays  104   a ,  104   b  thereby. The head array  104   a  and the head array  104   b  are aligned in the transport direction. Further, the ink-jet heads  3  for forming the head array  104   a  are deviated from the ink-jet heads  3  for forming the head array  104   b  in the nozzle alignment direction by a length which is a half of the spacing between the ink-jet heads  3  included in each of the head arrays  104   a ,  104   b.    
     The holding plate  103  is a plate-shaped member which is lengthy in the nozzle alignment direction and which extends over the entire length of the recording paper P in the nozzle alignment direction. The six ink-jet heads  3  are joined to the lower surface of the holding plate  103  so that the positional relationship as described above is provided. Thus, the six ink-jet heads  3  are held or retained by the holding plate  103 . 
     Further, the holding plate  103  has through-holes  103   a  which are formed at portions overlapped with ink introducing ports  71  of the respective ink-jet heads  3  respectively. Accordingly, the inks can be introduced via the through-holes  103   a  from the ink introducing ports  71  into the manifold flow passages  61  to  64  (see  FIG.  3   ). Further, the holding plate  103  has through-holes  103   b  which are formed at portions overlapped with portions of the respective ink-jet heads  3  except for the both end portions in the nozzle alignment direction. The through-holes  103   b  are formed in order that the deformation of the damper film  53   a  is not inhibited by the holding plate  103 . 
     Then, in the printer  100 , the printing is performed on the recording paper P by discharging the inks from the plurality of nozzles  15  of the six ink-jet heads  3  for forming the head unit  101 , while transporting the recording paper P in the transport direction by means of the recording paper transport rollers  4 . 
     In the second embodiment, the ink introducing ports  71  are arranged at the both end portions in the longitudinal direction (nozzle alignment direction) of the manifold flow passages  61  to  64  (see  FIG.  8   ). Therefore, it is possible to suppress the increase in size of the ink-jet head  3  in the transport direction. Accordingly, it is possible to suppress the increase in size of the head unit  101  in the transport direction, the head unit  101  having the two head arrays  104   a ,  104   b  which are aligned in the transport direction. 
     In this context, in the second embodiment, as depicted in  FIG.  10   , the ink introducing ports  71  of the two adjoining ink-jet heads  3  of the head array  104   b  are arranged within a range in which the ink-jet head  3  for forming the head array  104   a  is arranged in the nozzle alignment direction. Further, the ink introducing ports  71  of the two adjoining ink-jet heads  3  of the head array  104   a  are arranged within a range in which the ink-jet head  3  for forming the head array  104   b  is arranged in the nozzle alignment direction. Therefore, even when the size of the ink-jet head  3  is increased in the nozzle alignment direction on account of the provision of the ink introducing ports  71 , the increase in size of the head unit  101  in the nozzle alignment direction is not so serious. 
     Note that in the second embodiment, the head unit  101  corresponds to the liquid discharge apparatus unit according to the present teaching. Further, the ink-jet head  3  corresponds to the liquid discharge apparatus according to the present teaching. Further, the up-down direction (direction orthogonal to the paper surface of  FIG.  10   ) corresponds to the first direction according to the present teaching, the nozzle alignment direction corresponds to the second direction according to the present teaching, and the transport direction corresponds to the third direction according to the present teaching. 
     Next, modified embodiments, in which various changes are made in the first and second embodiments, will be explained. 
     In the first and second embodiments, the both end surfaces  66   c ,  69   c  in the transport direction of the protruding portions  66   b ,  69   b  are the curved surfaces. However, there is no limitation thereto. In a first modified embodiment, as depicted in  FIG.  11   , both end surfaces  166   c ,  169   c  of protruding portions  166   b ,  169   b  are flat surfaces which are parallel to the scanning direction. 
     Further, in the first and second embodiments, the protruding portions  66   b ,  69   b , which are joined to the lower surface of the first common flow passage member  51 , are formed on the lower surfaces  66   a ,  69   a  of the connecting flow passages  66 ,  69 . However, there is no limitation thereto. In a second modified embodiment, as depicted in  FIG.  12   , the protruding portions  66   b ,  69   b  (see  FIG.  9   ) are not formed on the lower surfaces  66   a ,  69   a  of the connecting flow passages  66 ,  69 . 
     Further, in the first and second embodiments, the damper film  53   a , which forms the upper wall surfaces of the respective manifold flow passages  61  to  64 , has the same thickness and the same areal size. However, there is no limitation thereto. In a third modified embodiment, as depicted in  FIG.  13   , damper films  201  for covering the manifold flow passages  61 ,  64  and a damper film  202  for covering the manifold flow passages  62 ,  63  are joined to the upper surface of the first common flow passage member  51  in place of the damper film  53  (see  FIG.  3   ). Further, the thickness T 1  of the damper film  201  is thinner than the thickness T 2  of the damper film  202 . 
     The manifold flow passages  61 ,  64  are not overlapped with the throttle flow passage groups  36   a ,  36   d , while the manifold flow passages  62 ,  63  are overlapped with the throttle flow passage groups  36   b ,  36   c . Therefore, it is difficult to transmit the pressure wave to the manifold flow passages  61 ,  64  as compared with the manifold flow passages  62 ,  63 . Therefore, it is difficult to attenuate the pressure wave which is generated in the pressure chamber  10  (see  FIG.  5   ) corresponding to the throttle flow passage group  36   a ,  36   d , as compared with the pressure wave which is generated in the pressure chamber  10  (see  FIG.  5   ) corresponding to the throttle flow passage group  36   b ,  36   c . In the third modified embodiment, as described above, the thickness T 1  of the damper film  201  is thinned as compared with the thickness T 2  of the damper film  202 . Accordingly, the thickness T 1  of the damper film  201   a  for forming the upper wall surface of the manifold flow passage  61 ,  64  is thinner than the thickness T 2  of the damper film  202   a  for forming the upper wall surface of the manifold flow passage  62 ,  63 . Accordingly, the damper film  201   a  is easily deformed as compared with the damper film  202   a . The pressure wave can be efficiently attenuated in the manifold flow passages  61 ,  64  in which it is difficult to transmit the pressure wave. 
     Note that in the third modified embodiment, the manifold flow passages  62 ,  63  correspond to the first manifold flow passage according to the present teaching, and the manifold flow passages  61 ,  64  correspond to the second manifold flow passage according to the present teaching. 
     In a fourth modified embodiment, as depicted in  FIG.  14   , the width W 2  of manifold flow passages  221 ,  224  overlapped with the throttle flow passage groups  36   a ,  36   d  is wider than the width W 1  of manifold flow passages  62 ,  63  not overlapped with the throttle flow passage groups  36   b ,  36   c.    
     In the same manner as the third modified embodiment, it is difficult to transmit the pressure wave to the manifold flow passages  221 ,  224  as compared with the manifold flow passages  62 ,  63 . In the fourth modified embodiment, as described above, the width W 2  of the manifold flow passages  221 ,  224  is larger than the width W 1  of the manifold flow passages  62 ,  63 . Accordingly, the areal size of the damper film  53   b  for forming the upper wall surface of the manifold flow passage  221 ,  224  is larger than the areal size of the damper film  53   a  for forming the upper wall surface of the manifold flow passage  62 ,  63 . Therefore, the damper film  53   b  is easily deformed as compared with the damper film  53   a . The pressure wave can be efficiently attenuated in the manifold flow passages  221 ,  224  in which it is difficult to transmit the pressure wave. 
     Note that in the fourth modified embodiment, the manifold flow passages  62 ,  63  correspond to the first manifold flow passage according to the present teaching, and the manifold flow passages  221 ,  224  correspond to the second manifold flow passages according to the present teaching. 
     Further, in the embodiment described above, all of the connecting portions of the connecting flow passages  66  to  69  with respect to the plurality of throttle flow passages  16  extend in parallel to the upward-downward direction. However, there is no limitation thereto. In a fifth modified embodiment A, as depicted in  FIG.  15 A , a connecting flow passage  231  for connecting the manifold flow passage  61  and the throttle flow passage group  36   a  has a connecting portion with respect to the plurality of throttle flow passages  16 , the connecting portion being inclined with respect to the upward-downward direction so that the position thereof is lowered toward the left side in the scanning direction, in other words, the connecting portion approaches the support substrate  12  at positions nearer to the throttle flow passage group  36   a . Further, a connecting flow passage  234  for connecting the manifold flow passage  64  and the throttle flow passage group  36   d  has a connecting portion with respect to the plurality of throttle flow passages  16 , the connecting portion being inclined with respect to the upward-downward direction so that the position thereof is lowered toward the right side in the scanning direction, in other words, the connecting portion approaches the support substrate  12  at positions nearer to the throttle flow passage group  36   d . In this case, the inks contained in the connecting flow passages  231 ,  234  more easily flow into the plurality of throttle flow passages  16 . Further, as in a fifth modified embodiment B depicted in  FIG.  15 B , each of manifold flow passages  361  to  364  may be formed so that the width in the scanning direction is continuously reduced toward the lower side. Each of the connecting flow passages  266  to  269  may be also formed so that the width in the scanning direction is continuously reduced toward the lower side. Each of the lower ends of the manifold flow passages  361  to  364  may be connected to each of upper ends of the connecting flow passages  266  to  269 . Also in the case of this structure, the inks contained in the manifold flow passages  361  to  364  and the connecting flow passages  266  to  269  more easily flow into the throttle flow passage groups  36   a  to  36   d  respectively. Further, in the same manner as the first embodiment, the pressure wave, which is transmitted to the manifold flow passages  361  to  364 , can be efficiently attenuated, while suppressing the increase in size of the ink-jet head in the scanning direction. 
     Further, in the first and second embodiments, the lower surfaces  66   a ,  69   a  of the connecting flow passages  66 ,  69  are formed to have the stepped shapes. However, there is no limitation thereto. In a sixth modified embodiment, as depicted in  FIG.  16   , a lower surface  241   a  of a connecting flow passage  241  for connecting the manifold flow passage  61  and the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   a  and a lower surface  244   a  of a connecting flow passage  244  for connecting the manifold flow passage  64  and the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   d  are flat surfaces which are parallel to the scanning direction and the transport direction. 
     Further, in the first and second embodiments, the ink introducing ports  71  are arranged at the positions overlapped with the both end portions in the transport direction of the manifold flow passages  61  to  64 . However, there is no limitation thereto. In a seventh modified embodiment, as depicted in  FIG.  17   , the ink introducing ports  71  are arranged only at positions overlapped with the end portions on the upstream side in the transport direction of the manifold flow passages  61  to  64 . On the contrary, unlike the seventh modified embodiment, it is also allowable that the ink introducing ports  71  are arranged at only positions overlapped with the end portions on the downstream side in the transport direction of the manifold flow passages  61  to  64 . 
     Further, in the first and second embodiments, it is also allowable that the ink introducing ports  71 , which are disposed on one side and which are included in the ink introducing ports  71  arranged at the positions overlapped with the both end portions in the transport direction of the manifold flow passages  61  to  64 , are used as ink outflow ports for allowing the inks to flow out from the manifold flow passages  61  to  64  to the ink cartridges, and the inks are circulated between the ink cartridges and the manifold flow passages  61  to  64 . 
     Further, in the first and second embodiments, the filter  55  is arranged to cover the ink introducing ports  71 . However, it is also allowable that the filter  55  is absent. 
     Further, in the first and second embodiments, the spacing D 1  between the manifold flow passages  61  to  64  is not less than 1.5 times and not more than 2.5 times the spacing D 2  between the throttle flow passage groups  36   a  to  36   d . However, there is no limitation thereto. The spacing D 1  may be less than 1.5 times the spacing D 2 , or the spacing D 1  may be larger than 2.5 times the spacing D 2 , provided that the spacing D 1  between the manifold flow passages  61  to  64  is larger than the spacing D 2  between the throttle flow passage groups  36   a  to  36   d.    
     Further, in the first and second embodiments, all of the spacings D 1  between the manifold flow passages  61  to  64  are the same, and the spacings D 1  are larger than the spacings D 2  between the throttle flow passage groups  36   a  to  36   d . However, there is no limitation thereto. In an eighth modified embodiment, as depicted in  FIG.  18   , a manifold flow passage  251 , which is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   a , has a width wider than that of a connecting flow passage  256  which connects the manifold flow passage  251  and the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   a . Similarly, a manifold flow passage  254 , which is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   d , has a width wider than that of a connecting flow passage  259  which connects the manifold flow passage  254  and the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   d.    
     On the other hand, a manifold flow passage  252 , which is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   b , has the same width as that of a connecting flow passage  257  which connects the manifold flow passage  252  and the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   b . Similarly, a manifold flow passage  253 , which is communicated with the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   c , has the same width as that of a connecting flow passage  258  which connects the manifold flow passage  253  and the plurality of throttle flow passages  16  for forming the throttle flow passage group  36   c.    
     Then, the spacing between the manifold flow passage  251  and the manifold flow passage  252  and the spacing between the manifold flow passage  253  and the manifold flow passage  254  are the spacing D 3  which is larger than the spacing D 2  between the throttle flow passage groups  36   a  to  36   d . On the other hand, the spacing between the manifold flow passage  252  and the manifold flow passage  253  is the same spacing D 2  as the spacing between the throttle flow passage groups  36   a  to  36   d.    
     Further, in the first and second embodiments, all of the manifold flow passages  61  to  64  have the same volume. However, it is also allowable to vary the volume between the manifold flow passages. For example, in the fourth modified embodiment described above, the width W 2  of the manifold flow passage  221 ,  224  is wider than the width W 1  of the manifold flow passage  62 ,  63 . Therefore, the volume of the manifold flow passage  221 ,  224  is larger than the volume of the manifold flow passage  62 ,  63 . Further, in the eight modified embodiment described above, the volume of the manifold flow passage  251 ,  254  is larger than the volume of the manifold flow passage  252 ,  253 . 
     Further, in the first and second embodiments, the stack of the first common flow passage member  51  and the second common flow passage member  52  is formed with the manifold flow passages  61  to  64  and the connecting flow passages  66  to  69 . However, there is no limitation thereto. In a ninth modified embodiment, as depicted in  FIG.  19   , one flow passage member  260  is formed with manifold flow passages  61  to  64  and connecting flow passages  66  to  69 . Note that in this case, for example, the flow passage member  260  is composed of a synthetic resin, and the flow passage member  260  is formed by means of the resin molding. 
     Further, in the first and second embodiments, the partition walls  38   a  to  38   c , which mutually partition the recesses  37 , are arranged at the positions different from those of the partition walls  52   a  to  52   c , of the support substrate  12 . However, there is no limitation thereto. In a tenth modified embodiment, as depicted in  FIG.  20   , one recess  261 , which is formed on the lower surface of the support substrate  12 , accommodates each of the second and third piezoelectric actuators  24  as counted from the right side in the scanning direction, the fourth and fifth piezoelectric actuators  24  as counted from the right side in the scanning direction, and the sixth and seventh piezoelectric actuators  24  as counted from the right side in the scanning direction. That is, in the tenth modified embodiment, the partition walls  38   a  to  38   c  of the first and second embodiments (see  FIG.  3   ) are absent. 
     Further, in the first and second embodiments, the ink-jet head  3  includes, for example, the four throttle flow passage groups  36   a  to  36   d  and the manifold flow passages  61  to  64  which are aligned in the scanning direction. However, there is no limitation thereto. In an eleventh modified embodiment, as depicted in  FIG.  21   , a head chip  271  is formed with ink flow passages corresponding to the central two arrays of nozzle arrays  31  included in the plurality of nozzle arrays  31  (see  FIG.  4   ) of the first and second embodiments. Further, a support substrate  272  is formed with two throttle flow passage arrays  273   a ,  273   b  formed respectively by the plurality of throttle flow passages  16  corresponding to the ink flow passages. 
     Further, the second common flow passage member  275  is formed with two manifold flow passages  276 ,  277  corresponding to the two throttle flow passage arrays  273   a ,  273   b . Further, the common flow passage members  274 ,  275  are formed with a connecting flow passage  278  which connects the manifold flow passage  276  and the plurality of throttle flow passages  16  for forming the throttle flow passage array  273   a , and a connecting flow passage  279  which connects the manifold flow passage  277  and the plurality of throttle flow passages  16  for forming the throttle flow passage array  273   b . The shapes of the manifold flow passages  276 ,  277  are the same as or equivalent to those of the manifold flow passages  62 ,  63  of the first and second embodiments. Further, the shapes of the connecting flow passages  278 ,  279  are the same as or equivalent to those of the connecting flow passages  67 ,  68  of the first and second embodiments. 
     Further, the ink-jet head may be constructed, for example, such that three or five or more nozzle groups, throttle flow passage groups, and manifold flow passages are aligned in the scanning direction. 
     Further, in the second embodiment, the two head arrays  104   a ,  104   b  are aligned in the transport direction. However, there is no limitation thereto. It is also allowable that the head arrays are aligned in three or more arrays in the transport direction. 
     In the foregoing description, the exemplary embodiments have been explained, in which the present teaching is applied to the printer which performs the printing by discharging the inks from the nozzles. However, there is no limitation thereto. The present teaching can be also applied to any liquid discharge apparatus other than the printer, for discharging any liquid other than the ink from a nozzle or nozzles.