Patent Publication Number: US-11660864-B2

Title: Liquid discharging head

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims priority from Japanese Patent Application No. 2020-111246, filed on Jun. 29, 2020, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     Field of the Invention 
     The present disclosure relates to a liquid discharging head provided with a plurality of individual channels, a first common channel and a second common channel. 
     Description of the Related Art 
     Published Japanese Translation of PCT International Publication for Patent Application No. 2011-520671 corresponding to International Publication No. WO2009/143362 discloses a liquid circulating system provided with a plurality of fluid passages (individual channels) each of which includes a fluid pumping chamber (pressure chamber) and a nozzle; and a liquid inlet passage (first common channel) and a recirculating channel (second common channel) which communicate with the plurality of fluid passages. A liquid inside the liquid inlet passage is supplied to the fluid pumping chamber of each of the plurality of fluid passages, flows from the fluid pumping chamber through a descending part; a part of the liquid flows to the nozzle, and the remaining part of the liquid flows to the recirculating channel. 
     In Published Japanese Translation of PCT International Publication for Patent Application No. 2011-520671 (see  FIG.  1 C ), the plurality of fluid passages form a fluid passage array (row). One liquid inlet passage is provided as a common liquid inlet passage with respect to two pieces of the fluid passage array (namely, the two fluid passage arrays are fluidically connected to one liquid inlet passage). The recirculating channel is provided as recirculating channels arranged, respectively, on both sides of the fluid pumping chambers of the two fluid passage arrays. 
     The temperature of the liquid inside each of the individual channels is increased in a case that an actuator provided corresponding to the pressure chamber is driven. By accumulating, in the second common channel, the liquids having a high temperature in the respective individual channels, the temperature of the liquid in the second common channel might be further higher than that of the liquid in each of the individual channels. 
     In Published Japanese Translation of PCT International Publication for Patent Application No. 2011-520671, the fluid pumping chambers (pressure chambers) of each of the two fluid passage arrays do not overlap with the recirculating channel (second common channel) which stores a high-temperature liquid, in a direction orthogonal to the sheet surface of  FIG.  1 C  (first direction). With this, any heat transmission from the second common channel to each of the pressure chambers is suppressed, which in turn makes it possible to suppress, to some extent, the increase in the temperature in the individual channel. In Japanese Patent Application Laid-open No. 2011-520671, however, the fluid pumping chambers (pressure chambers) of the two fluid passage arrays overlap with each other, in an overlap part therebetween, in an array direction (second direction) of the fluid passage arrays. In this case, the heat due to the liquids in the pressure chambers are concentrated in the overlap part, which in turn increase the temperature of the individual channel(s). 
     An object of the present disclosure is to provide a liquid discharging head capable of suppressing any increase in the temperature in the individual channel(s). 
     SUMMARY 
     According to the present disclosure, there is provided a liquid discharging head including: 
     a plurality of individual channels; 
     at least one first common channel communicating with the individual channels; and 
     at least one second common channel communicating with the individual channels, 
     wherein each of the individual channels includes:
         a pressure chamber,   a nozzle which is apart from the pressure chamber in a first direction,   a connecting channel connecting the pressure chamber and the nozzle,   a first communicating channel which has one end connected to the at least one first common channel and the other end connected to the pressure chamber, and   at least one second communicating channel which has one end connected to the connecting channel and the other end connected to the at least one second common channel;       

     the individual channels include:
         first individual channels which have first pressure chambers and which are aligned in a second direction orthogonal to the first direction to form a first individual channel array, and   second individual channels which have second pressure chambers and which are aligned in the second direction to form a second individual channel array;       

     the first individual channel array and the second individual channel array are arranged in a third direction orthogonal to the first direction and the second direction; 
     the at least one first common channel includes one first common channel communicating with both of the first individual channels and the second individual channels; and 
     the first pressure chambers and the second pressure chambers do not overlap with the at least one second common channel in the first direction, and do not overlap with each other in the second direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a plan view of a printer provided with a head according to a first embodiment of the present disclosure. 
         FIG.  2    is a plan view of the head according to the first embodiment of the present disclosure. 
         FIG.  3    is an enlarged view of an area III depicted in  FIG.  2   . 
         FIG.  4    is a cross-sectional view of the head along a line IV-IV in  FIG.  2   . 
         FIG.  5    is a plan view of a head according to a second embodiment of the present disclosure. 
         FIG.  6    is a plan view of a head according to a third embodiment of the present disclosure. 
         FIG.  7    is a plan view of a head according to a fourth embodiment of the present disclosure. 
         FIG.  8    is an enlarged view of a head according to a fifth embodiment of the present disclosure, corresponding to  FIG.  3   . 
         FIG.  9    is a plan view of a head according to a sixth embodiment of the present disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     First Embodiment 
     Firstly, an explanation will be given about the overall configuration of a printer  100  provided with a head  1  according to a first embodiment of the present disclosure, with reference to  FIG.  1   . 
     The printer  100  is provided with a head unit  1   x  including four pieces of the head  1 , a platen  3 , a conveying mechanism  4  and a controller  5 . 
     Paper sheet (paper)  9  is placed on the upper surface of the platen  3 . 
     The conveying mechanism  4  has two roller pairs  4   a  and  4   b  which are arranged, with the platen  3  being arranged or interposed therebetween in a conveying direction (a direction which is orthogonal to the vertical direction). In a case that a conveying motor (not depicted in the drawings) is driven by control of the controller  5 , the two roller pairs  4   a  and  4   b  rotate in a state that the paper  9  is held (pinched) therebetween, thereby conveying the paper  9  in the conveying direction. 
     The head unit  1   x  is elongated in a paper width direction (a direction which is orthogonal to both of the conveying direction and the vertical direction) and is of a line system in which an ink is ejected or discharged from a nozzle  21  (see  FIGS.  2  to  4   ) with respect to the paper  9  in a state that the position of the head unit  1   x  is fixed. Each of the four heads  1  is long in the paper width direction and the four heads  1  are arranged in a staggered manner in the paper width direction. 
     The controller  5  includes a ROM (Read Only Memory), a RAM (Random Access Memory) and an ASIC (Application Specific Integrated Circuit). The ASIC executes a recording processing, etc., in accordance with a program stored in the ROM. In the recording processing, the controller  5  controls a driver IC and a conveying motor (both of which are not depicted in the drawings) of each of the heads  1  based on a recording instruction (including image data) inputted from an external apparatus such as a PC, etc., and records an image on the paper  9 . 
     Next, the configuration of each of the heads  1  will be explained, with reference to  FIGS.  2  to  4   . 
     As depicted in  FIG.  4   , the head  1  has a channel member  11  and an actuator member  12 . 
     The channel member  11  is constructed of seven plates  11   a  to  11   g  which are stack on one another in the vertical direction (first direction) and which are joined to one another. A through hole forming a channel is formed in each of the plates  11   a  to  11   g.    
     The channel includes a plurality of individual channels  20 , and one supply channel  31  and two return channels  32 A and  32 B each of which communicates with the plurality of individual channels  20 . The supply channel  31  corresponds to a “first common channel” of the present disclosure, and the return channels  32 A and  32 B correspond to a “second common channel” of the present disclosure. More specifically, the common channel  31  corresponds to “one first common channel included in at least one first common channel”, the return channel  32 A corresponds to “one second common channel included in at least one second common channel”, and the return channel  32 B corresponds to “another second common channel included in the at least one second common channel”. 
     As depicted in  FIG.  2   , the supply channel  31  and the return channels  32 A and  32 B each extend in the paper width direction (second direction), and are arranged side by side in a direction parallel to the conveying direction (third direction). In the conveying direction, the supply channel  31  is arranged between the return channels  32 A and  32 B. 
     The plurality of individual channels  20  are arranged in a staggered manner in the paper width direction so as to form a first individual channel array  20 A and a second individual channel array  20 B. The first individual channel array  20 A and the second individual channel array  20 B are arranged side by side in the conveying direction. Namely, the plurality of individual channels  20  include first individual channels which are aligned in the paper width direction to form the first individual channel array  20 A, and second individual channels which are aligned in the paper width direction to form the second individual channel array 20 B. The individual channels (first individual channels)  20  constructing the first individual channel array  20 A communicate with the supply channel  31  and the return channel  32 A. The individual channels (second individual channels)  20  constructing the second individual channel array  20 B communicate with the supply channel  31  and the return channel  32 B. Namely, the supply channel  31  communicates with both of the individual channels  20  constructing the first individual channel array  20 A and the individual channels  20  constructing the second individual channel array  20 B. 
     As depicted in  FIG.  4   , each of the plurality of individual channels  20  includes: a pressure chamber  22 , a nozzle  21  which is apart from the pressure chamber  22  in the vertical direction, a connecting channel  23  connecting the pressure chamber  22  and the nozzle  21 , an inflow channel  24  communicating the pressure chamber  22  and the supply channel  31 , and an outflow channel  25  communicating the connecting channel  23  and the return channel  32 A or  32 B corresponding thereto. The inflow channel  24  corresponds to a “first communicating channel” of the present disclosure, and the outflow channel  25  corresponds to a “second communicating channel” of the present disclosure. 
     The nozzle  21  is constructed of a through hole formed in the plate  11   g , and is opened in a lower surface of the channel member  11 . 
     The pressure chamber  22  is constructed of through holes formed in the plates  11   a  and  11   b , respectively, and is opened in the upper surface of the channel member  11 . With respect to the pressure chamber  22 , the connecting channel  23  is connected to one end in the conveyance direction of the pressure chamber  22 , and the inflow channel  24  is connected to the other end in the conveyance direction of the pressure chamber  22 . 
     The connecting channel  23  is a channel having a cylindrical shape and extending downward from the pressure chamber  22 , and is constructed of through holes each of which is formed in one of the plates  11   c  to  11   f . The nozzle  21  is arranged at a location immediately below the connecting channel  23 . 
     The inflow channel  24  is constructed of through holes formed in the plates  11   c  and  11   d , respectively, and has one end  24   a  communicating with the supply channel  31  and the other end  24   b  communicating with the pressure chamber  22 . The one end  24   a  connects to the upper surface of the supply channel  31 . The other end  24   b  connects to the lower surface of the pressure chamber  22 . 
     The outflow channel  25  is constructed of a through hole formed in the plate  11   f , and has one end  25   a  communicating with the connecting channel  23  and the other end  25   b  communicating with the return channel  32 A or  32 B corresponding thereto. The one end  25   a  connects to a side surface of the connecting channel  23 . The other end  25   b  connects to a side surface of the return channel  32  ( 32 A or  32 B). 
     The supply channel  31  is constructed of through holes formed in the plates  11   e  and  11   f , respectively; and each of the return channels  32 A and  32 B is constructed of through holes each of which is formed in one of the plates  11   b  to  11   f . Each of the return channels  32 A and  32 B has a length in the vertical direction longer than that of the supply channel  31 , and overlaps with the pressure chamber  22  in the conveyance direction. The plate  11   b  has the through hole constructing the pressure chamber  22  and the through holes constructing the return channels  32 A and  32 B. 
     As depicted in  FIG.  3   , each of the inflow channel  24  and the outflow channel  25  has a width (length in the paper width direction) which is smaller than a width (length in the paper width direction) of the pressure chamber  22 , and functions as a throttle. In each of the individual channels  20 , the inflow channel  24  is arranged on one side in the conveying direction with respect to the nozzle  21 , and the outflow channel  25  is arranged on the other side in the conveying direction with respect to the nozzle  21 . The inflow channel  24  and the outflow channel  25  are parallel to each other, and each extend in the conveying direction. 
     The pressure chamber  22  has a rectangular shape which is long in the conveying direction in a plane orthogonal to the vertical direction. As depicted in  FIG.  2   , a plurality pieces of the pressure chamber  22  constructing each of the individual channel arrays  20 A and  20 B are aligned at an equal spacing distance of a pitch A in the paper width direction (width direction of the pressure chamber  22 ) therebetween. The pitch A is, for example, in a range of 50 μm to 100 μm. Here, the term “pitch” of the pressure chambers  22  indicates a center-to-center distance between the centers of two pressure chambers  22  which are adjacent in a plane orthogonal to the first direction, as seen from the first direction. The term “center of the pressure chamber  22 ” indicates, for example, the centroid of a view (plane view) in a case that the pressure chamber  22  is seen from the first direction. 
     Further, as depicted in  FIG.  2   , the pressure chambers (first pressure chambers)  22  of (belonging to) the first individual channel array  20 A and the pressure chambers (second pressure chambers) 22  of (belonging to) the second individual channel array  20 B overlap with the supply channel  31  in the vertical direction, and do not overlap with the return channels  32 A and  32 B in the vertical direction. 
     The pressure chambers  22  of the first individual channel array  20 A and the pressure chambers  22  of the second individual channel array  20 B do not overlap with one another in the paper width direction, and are apart from one another in the conveying direction (in the conveying direction, a gap (spacing distance) D 1  is provided or defined between the pressure chamber  22  of the first individual channel array  20 A and the pressure chamber  22  of the second individual channel array  20 B). The gap D 1  is, for example, in a range of 100 μm to 200 μm. 
     The pressure chambers  22  of the first individual channel array  20 A are arranged on one side in the conveying direction (left side in  FIG.  2   ) with respect to a center O in the conveying direction of the supply channel  31 ; and the pressure chambers  22  of the second individual channel array  20 B are arranged on the other side in the conveying direction (right side in  FIG.  2   ) with respect to the center O. Further, the one end  24   a  of the inflow channel  24  of the first individual channel array  20 A is positioned at an end part on the other side in the conveying direction (right end in  FIG.  2   ) of the supply channel  31 , and the one end  24   a  of the inflow channel  24  of the second individual channel array  20 B is positioned at an end part on the one side in the conveying direction (left end in  FIG.  2   ) of the supply channel  31 . 
     Each of the supply channel  31  and the return channels  32 A and  32 B communicates with a sub tank (not depicted in the drawings). The sub tank communicates with a main tank which stores the ink, and stores the ink supplied from the main tank. 
     In a case that a pump (not depicted in the drawings) is driven by control of the controller  5 , the ink inside the sub tank flows into the supply channel  31 . The ink inflowed into the supply channel  31  is supplied to each of the individual channels  20  of the first and second individual channel arrays  20 A and  20 B, while moving inside the supply channel  31  in the paper width direction. 
     As depicted in  FIG.  4   , the ink supplied from the supply channel  31  to each of the individual channels  20  flows through the inflow channel  24  and inflows into the pressure chamber  22 , and moves inside the pressure chamber  22  in a substantially horizontal manner, and flows into the connecting channel  23 . This ink moves downward while passing through the connecting channel  23 ; a part of the ink is ejected or discharged from the nozzle  21 , and a remaining part of the ink flows through the outflow channel  25  and flows out to the return channel  32 A or  32 B corresponding thereto. 
     The ink flows into the return channel  32 A from each of the individual channels  20  of the first individual channel array  20 A. The ink flows into the return channel  32 B from each of the individual channels  20  of the second individual channel array  20 B. The ink flows through the return channel  32  (return channels  32 A and  32 B), and is returned to the sub tank. 
     By circulating the ink between the sub tank and the channel member  11  in such a manner, it is possible to realize discharge (exhaust) of an air bubble and/or prevention of increase in the viscosity of the ink, in the supply channel  31 , the return channels  32 A and  32 B, and further in each of the individual channels  20 , which are formed in the channel member  11 . Further, in a case that the ink contains a component which aggregates or precipitates (a component of which aggregation or precipitation might occur; a pigment, etc.), such a component is agitated and the aggregation (precipitation) of the component is prevented. 
     The actuator member  12  includes a vibration plate  12   a , a common electrode  12   b , a plurality of piezoelectric bodies  12   c , and a plurality of individual electrodes  12   d , in this order from a lower part thereof. 
     The vibration plate  12   a  and the common electrode  12   b  are arranged on the upper surface of the channel member  11  (upper surface of the plate  11   a ), and cover all the plurality of pressure chambers  22  opened in the upper surface of the plate  11   a . On the other hand, each of the plurality of piezoelectric bodies  12   c  and each of the plurality of individual electrodes  12   d  are provided on one of the plurality of pressure chambers  22 , and overlap with one of the plurality of pressure chambers  22  in the vertical direction. 
     The common electrode  12   b  and the plurality of individual electrodes  12   d  are electrically connected to the driver IC (not depicted in the drawings). The driver IC changes the potential of each of the plurality of individual electrodes  12   d , while maintaining the potential of the common electrode  12   b  to the ground potential. Specifically, the driver IC generates a driving signal based on a control signal from the controller  5 , and applies the driving signal to each of the plurality of individual electrodes  12   d . With this, the potential of each of the plurality of individual electrodes  12   d  is changed between a predetermined driving potential and the ground potential. In this situation, a part of the vibration plate  12   a  and a part of each of the plurality of piezoelectric bodies  12   c  (the parts being actuator  12   x ) which are sandwiched between one of the plurality of individual electrodes  12   d  and one of the plurality of pressure chambers  22  are deformed so as to project toward one of the plurality of pressure chambers  22 . With this, the volume of one of the plurality of pressure chambers  22  is changed to thereby apply pressure to the ink in one of the plurality of pressure chambers  22 , and causing the ink to be ejected or discharged from the nozzle  21 . The actuator member  12  has a plurality of pieces of the actuator  12   x  each of which corresponds to one of the plurality of pressure chambers  22 . 
     As described above, according to the present embodiment, the pressure chambers (first pressure chambers)  22  in the first individual channel arrays  20 A and the pressure chambers (second pressure chambers)  22  in the second individual channel arrays  20 B do not overlap with the return channels  32 A and  32 B in the vertical direction (first direction) (see  FIG.  2   ). This suppresses any transfer of the heat to each of the plurality of pressure chambers  22  from the return channels  32 A and  32 B of which temperature might become higher than that in the plurality of individual channels  20 . Further, the pressure chambers  22  in the first individual channel array  20 A and the pressure chambers  22  in the second individual channel array  20 B do not overlap with one another in the paper width direction (second direction). With this, it is possible to avoid any concentration of the heat due to the ink inside the pressure chambers  22 . Thus, according to the present embodiment, it is possible to suppress any increase in the temperature in the plurality of individual channels  20 . 
     Note that in a case that the temperature in the plurality of individual channels  20  is increased, the viscosity of the ink in the plurality of individual channels  20  is changed, which in turn causes any variation in the viscosity of the ink among the plurality of individual channels  20 , leading to such a possibility that the discharge or ejection of the ink might be unstable. According to the present embodiment, it is possible to suppress the above-described problem and to realize a stable discharge or ejection of the ink. 
     The pressure chambers  22  in the first individual channel array  20 A and the pressure chambers  22  in the second individual channel array  20 B are apart from each other in the conveying direction (third direction) via the gap D 1  (see  FIG.  2   ). In this case, it is possible to avoid any concentration of the heat due to the ink inside the pressure chambers  22 , in a more ensured manner. Accordingly, it is possible to suppress any increase in the temperature in the individual channels  20 , in a more ensured manner. 
     The supply channel  31  is located on the upstream side of the individual channels  20  of which temperature might become high due to the driving of the actuators  12   x . Accordingly, the temperature of ink inside the supply channel  31  may be lower than the temperature of the ink inside each of the individual channels  20 . In the present embodiment, the pressure chambers  22  in the first individual channel array  20 A and the pressure chambers  22  in the second individual channel array  20 B overlap with the supply channel  31  in the vertical direction (first direction). In this case, it is possible to make the size of the head  1  to be small in the conveying direction (third direction), while suppressing any increase in the temperature of the individual channels  20 . 
     The pressure chambers  22  of the first individual channel array  20 A are arranged on one side in the conveying direction (third direction) (left side in  FIG.  2   ) with respect to the center O in the conveying direction (third direction) of the supply channel  31 ; and the pressure chambers  22  of the second individual channel array  20 B are arranged on the other side in the conveying direction (third direction) (right side in  FIG.  2   ) with respect to the center O. Further, the one end  24   a  of the inflow channel  24  of the first individual channel array  20 A is positioned at the end part on the other side in the conveying direction (third direction) (right end in  FIG.  2   ) of the supply channel  31 , and the one end  24   a  of the inflow channel  24  of the second individual channel array  20 B is positioned at the end part on the one side in the conveying direction (third direction) (left end in  FIG.  2   ) of the supply channel  31 . In this case, it is possible to make the length of the inflow channel  24  to be long. Consequently, it is possible to make the flow rate in the inflow channel  24  to be great, and to allow the air inside the supply channel  31  to flow smoothly to the individual channels  20  and to discharge or exhaust the air to the return channels  32 A and  32 B, during the circulation. 
     Each of the return channels  32 A and  32 B has the length in the vertical direction (first direction) longer than the length in the vertical direction (first direction) of the supply channel  31  (see  FIG.  4   ). In this case, by making the length in the vertical direction (first direction) of each of the return channels  32 A and  32 B to be long, and to make the volume of each of the return channels  32 A and  32 B to be great, it is possible to lower the channel resistance in each of the return channels  32 A and  32 B. Consequently, it is possible to increase a circulation amount of the ink and to efficiently release the heat inside the individual channels  20  to the return channels  32 A and  32 B. This makes it to possible to further suppress any increase in the temperature in the individual channels  20 . 
     The return channels  32 A and  32 B overlap with the pressure chambers  22  in the conveying direction (third direction) (see  FIG.  4   ). In this case, it is possible to release the heat from the pressure chambers  22  to the return channels  32 A and  32 B, thereby making it possible to further suppress any increase in the temperature in the individual channels  20 . 
     Second Embodiment 
     Next, an explanation will be given about a head  201  according to a second embodiment of the present disclosure, with reference to  FIG.  5   . 
     In the first embodiment ( FIG.  2   ), the pressure chambers  22  in the first individual channel array  20 A and the pressure chambers  22  in the second individual channel array  20 B overlap with each other in the third direction. In contrast, in the second embodiment ( FIG.  5   ), the pressure chambers  22  in the first individual channel array  20 A and the pressure chambers  22  in the second individual channel array  20 B do not overlap with each other in the third direction. In this case, it is possible to avoid any concentration of the heat due to the ink inside the pressure chambers  22 , in a more ensured manner Thus, it is possible to suppress any increase in the temperature in the individual channels  20 , in a more ensured manner. 
     Further, in the second embodiment, the pressure chambers  22  in the first individual channel array  20 A and the pressure chambers  22  in the second individual channel array  20 B are apart from each other in the second direction. Each of the second pressure chambers  22  are shifted in the second direction with respect to each of the first pressure chambers  22  (in the second direction, a gap (spacing distance) D 2  is provided or defined between each of the pressure chambers  22  in the first individual channel array  20 A and one of the pressure chambers  22  in the second individual channel array  20 B which is adjacent thereto). The gap D 2  is, for example, in a range of 50 μm to 100 μm. In this case, it is possible to avoid any concentration of the heat due to the ink inside the pressure chambers  22  in a more ensured manner. Thus, it is possible to suppress any increase in the temperature in the individual channels  20 , in a more ensured manner. 
     Third Embodiment 
     Next, an explanation will be given about a head  301  according to a third embodiment of the present disclosure, with reference to  FIG.  6   . 
     In the first embodiment ( FIG.  2   ), in each of the individual channels  20  in the first individual channel array  20 A, the one end  24   a  of the inflow channel  24  is positioned at the end part on the other side in the third direction (right end in  FIG.  2   ) of the supply channel  31 ; and in each of the individual channels  20  in the second individual channel array  20 B, the one end  24   a  of the inflow channel  24  is positioned at the end part on the one side in the third direction (left end in  FIG.  2   ) of the supply channel  31 . In contrast, in the third embodiment ( FIG.  6   ), in each of individual channels  320  in the first and second individual channel arrays  20 A and  20 B, the one end  24   a  of the inflow channel  24  is located at a central part in the third direction of the supply channel  31 . 
     The flow rate in the central part in the third direction of the supply channel  31  is great as compared with that in the end part(s) in the third direction of the supply channel  31 . According to the third embodiment, by arranging the end part  24   a  of the inflow channel  24  at this central part, it is possible to flow the air inside the supply channel  31  smoothly to the individual channels  320  and to discharge or exhaust the air to the return channels  32 A and  32 B, during the circulation. 
     Fourth Embodiment 
     Next, an explanation will be given about a head  401  according to a fourth embodiment of the present disclosure, with reference to  FIG.  7   . 
     In the first embodiment ( FIG.  2   ), the plurality of individual channels  20  construct the two individual channel arrays  20 A and  20 B. In contrast, in the fourth embodiment ( FIG.  7   ), the plurality of individual channels  20  construct three individual channel arrays  20 A to  20 C. Namely, in the fourth embodiment, the plurality of individual channels  20  include third individual channels constructing the third individual channel array  20 C, in addition to the first and second individual channel arrays  20 A and  20 B. The third individual channel array  30 C interposes, in the third direction, the second individual channel array  20 B between the first individual channel array  20 A and the third individual channel array  20 C. 
     Here, a spacing distance X in the third direction between the pressure chambers (first pressure chambers)  22  of (belonging to) the first individual channel array  20 A and the pressure chambers (second pressure chambers)  22  of the second individual channel array  20 B, and a spacing distance X in the third direction between the pressure chambers (second pressure chambers)  22  of the second individual channel array  20 B and the pressure chambers (third pressure chambers)  22  of the third individual channel array  20 C are same as each other (see  FIG.  7   ). According to this configuration, even in a case of providing the three individual channel arrays  20 A to  20 C, by arranging the pressure chambers  22  in the third direction at the equal spacing distance X therebetween, it is possible to avoid any concentration of the heat due to the ink inside the pressure chambers  22 , and to suppress any increase in the temperature in the individual channels  20 . Here, the phrase “spacing distance between the pressure chambers  22  in a predetermined direction” indicates the gap between the pressure chambers  22  in the predetermined direction, namely, the minimum distance in the predetermined direction between one pressure chamber  22  and another pressure chamber  22 . 
     Further, the pressure chambers  22  constructing the first individual channel array  20 A, the pressure chambers  22  constructing the second individual channel array  20 B and the pressure chambers  22  constructing the third individual channel array  20 C are arranged at an equal spacing distance therebetween (arranged at a same pitch) in a plane orthogonal to the first direction (see  FIG.  7   ). Specifically, the pressure chambers  22  constructing each of the first to third individual channel arrays  20 A to  20 C are aligned at an equal spacing distance of a pitch Y in the second direction therebetween; further, with respect to each (a certain second pressure chamber  22 ) of the second pressure chambers  22 , two of the first pressure chambers  22  which are closest to the certain second pressure chamber  22  are arranged at the pitch Y with respect to the certain second pressure chamber  22 ; with respect to each (the certain second pressure chamber  22 ) of the second pressure chambers  22 , two of the third pressure chambers  22  which are closest to the certain second pressure chamber  22  are arranged at the pitch Y with respect to the certain second pressure chamber  22 . In other words, a pressure chamber  22  belonging to the first individual channel array  20 A, a pressure chamber  22  belonging to the second individual channel array  20 B and a pressure chamber  22  belonging to the third individual channel array  20 C are arranged in this order at the pitch Y in a direction which is orthogonal to the first direction and which crosses the second and third directions. By arranging all the pressure chambers  22  at the equal spacing distance therebetween (by arranging all the pressure chambers  22  at the same pitch) in such a manner, it is possible to avoid any concentration of the heat, due to the ink inside the pressure chambers  22 , in a more ensured manner, and to suppress any increase in the temperature in the individual channels  20 , in a more ensured manner. 
     Furthermore, the first embodiment ( FIG.  2   ) is provided with a total of three common channels which are: the supply channel  31  communicating with the plurality of individual channels  20  constructing the first and second individual channel arrays  20 A and  20 B, the return channel  32 A communicating with the individual channels  20  constructing the first individual channel array  20 A, and the return channel  32 B communicating with the individual channels  20  constructing the second individual channel array  20 B. 
     In contrast, the fourth embodiment ( FIG.  7   ) is provided with a total of four common channels which are: a supply channel  431  communicating with the individual channels (first and second individual channels)  20  constructing the first and second individual channel arrays  20 A and  20 B, a supply channel  431 ′ communicating with the individual channels (third individual channels)  20  constructing the third individual channel array  20 C, a return channel  432  communicating with the individual channels (first individual channels)  20  constructing the first individual channel array  20 A, and a return channel  432 ′ communicating with the individual channels (second and third individual channels)  20  constructing the second and third individual channel arrays  20 B and  20 C. The supply channel  431  corresponds to the “one first common channel included in the at least one first common channel” of the present disclosure, the supply channel  431 ′ corresponds to “another first common channel included in the at least one first common channel” of the present disclosure, and the return channels  432  and  432 ′ correspond to the “second common channel” of the present disclosure. More specifically, the return channel  432  corresponds to “one second common channel included in the at least one second common channel”, and the return channel  432 ′ corresponds to “another second common channel included in the at least one second common channel”. Further, in the third direction, the supply channel  431  is arranged between the return channels  432  and  432 ′. Furthermore, in the third direction, the return channel  432 ′ is arranged between the supply channels  431  and  431 ′. A length in the third direction (width) of each of the return channels  432  and  432 ′ is shorter than a length in the third direction (width) of each of the supply channels  431  and  431 ′. 
     In particular, by making the length in the third direction of the return channel  432 ′ to be short, as compared with those of the supply channels  431  and  431 ′, it is possible to realize a configuration of arranging all the pressure chambers  22  at the equal spacing distance therebetween, in a more ensured manner. 
     Fifth Embodiment 
     Next, an explanation will be given about a head  501  according to a fifth embodiment of the present disclosure, with reference to  FIG.  8   . 
     In the first embodiment ( FIG.  2   ), each of the individual channels  20  includes one outflow channel  25 . In contrast, in the fifth embodiment ( FIG.  8   ), each of individual channels  520  includes two outflow channels  25   x  and  25   y.    
     Each of the outflow channels  25   x  and  25   y  has one end  25   a  communicating with the connecting channel  23 , and the other end  25   b  communicating with the return channel  32 A or  32 B corresponding thereto. The one end  25   a  connects to a side surface of the connecting channel  23 . The other end  25   b  connects to a side surface of the return channel  32 A or  32 B corresponding thereto. The one end  25   a  of the outflow channel  25   x  is located on one side in the second direction with respect to the nozzle  21 ; and the one end  25   a  of the outflow channel  25   y  is located on the other side in the second direction with respect to the nozzle  21 . The one ends  25   a  of the two outflow channels  25   x  and  25   y  are arranged symmetrically with respect to the nozzle  21 . Further, the outflow channels  25   x  and  25   y  are arranged within the area of the pressure chamber  22  in the second direction. Namely, the entirety of each of the outflow channels  25   x  and  25   y  overlaps with the pressure chamber  22  in the third direction, and has no part which does not overlap with the pressure chamber  22  in the third direction. The outflow channels  25   x  and  25   y  are located at positions, respectively, which are corresponding to the one end and the other end in the second direction of the pressure chamber  22 , respectively. 
     Accordingly to the fifth embodiment, it is possible to efficiently release the heat inside each of the individual channels  20  via the two outflow channels  25   x  and  25   y  to the return channel  32 A or  32 B. With this, it is possible to further suppress any increase in the temperature in the individual channels  20 . 
     Further, according to the fifth embodiment, since the two outflow channels  25   x  and  25   y  are provided with respect to each of the nozzles  21 , the ink in the vicinity of the nozzle  21  is divided (dispersed) toward the two outflow channels  25   x  and  25   y  in a case that the circulation of the ink is performed during the recording. With this, any deviation or deflection of the flow of the ink can be mitigated, thereby making it possible to suppress occurrence of such a problem that a discharging or ejecting direction of the ink from the nozzle(s)  21  is deviated from a desired direction, as compared with a case in which only one outflow channel is provided. 
     Sixth Embodiment 
     Next, an explanation will be given about a head  601  according to a sixth embodiment of the present disclosure, with reference to  FIG.  9   . 
     In the first embodiment ( FIG.  2   ), each of the pressure chambers  22  extends in the third direction. In contrast, in the sixth embodiment ( FIG.  9   ), each of the pressure chambers  22  extends in a direction orthogonal to the first direction and crossing the second and third directions (crossing direction). The plurality of pressure chambers  22  constructing each of the individual channel arrays  20 A and  20 B are aligned at an equal spacing distance of a pitch A, which is similar to that in the first embodiment, in a direction orthogonal to the direction in which the pressure chambers  22  extend (crossing direction). 
     According to the sixth embodiment, a pitch B (&gt;A) in the second direction between adjacent pressure chambers  22  can be made great as compared with the configuration wherein the pressure chambers  22  extend in the third direction (first embodiment:  FIG.  2   ). With this, it is possible to avoid any concentration of the heat due to the ink inside the pressure chambers  22  in a more ensured manner, and to suppress any increase in the temperature in the individual channels  20 , in a more ensured manner. 
     Modification 
     Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to or restricted by the above-described embodiments, and various design changes can be made within the scope of the claims. 
     In the first embodiment ( FIG.  2   ), it is allowable that the pressure chambers  22  of the first individual channel array  20 A and the pressure chambers  22  of the second individual channel array  20 B do not overlap with the supply channel  31  in the first direction. 
     In the first embodiment ( FIG.  2   ), it is allowable that the pressure chambers  22  of the first individual channel array  20 A and the pressure chambers  22  of the second individual channel array  20 B are not apart from one another in the third direction (the spacing distance D 1  may be 0 (zero)). 
     In the second embodiment ( FIG.  5   ), it is allowable that the pressure chambers  22  of the first individual channel array  20 A and the pressure chambers  22  of the second individual channel array  20 B are not apart from each other in the second direction (the spacing distance D 2  may be 0 (zero)). 
     In the fifth embodiment ( FIG.  8   ), it is allowable that each of the individual channels  20  includes three or more outflow channels. Further, it is allowable that the outflow channel has a part which is on the outside the area of the pressure chamber in the second direction. 
     In the above-described embodiments, although one pressure chamber is provided with respect to one nozzle, it is allowable that two or more pieces of the pressure chamber are provided with respect to one nozzle. Alternatively, in the above-described embodiments, although one nozzle is provided with respect to one pressure chamber, it is allowable that two or more pieces of the nozzle are provided with respect to one pressure chamber. 
     The head is not limited to being of the line system, and may be of a serial system in which the liquid is ejected or discharged from the nozzles to a discharge object while the head is moving in a scanning direction parallel to the paper width direction. 
     In the above-described embodiments, although the piezoelectric body  12   c  is provided on each of the pressure chambers  22 , the present disclosure is not limited to this. It is allowable that the piezoelectric body  12   c  is provided so as to cover all the pressure chambers  22  which are opened in the upper surface of the plate  11   a , similarly to the vibration plate  12   a  and the common electrode  12   b . Further, although the actuator is of the piezoelectric system in the above-described embodiments, the present disclosure is not limited to this; it is allowable that the actuator is of another system (for example, thermal system using a heating element, an electrostatic system using the electrostatic force, etc.). 
     The discharge object is not limited to paper (paper sheet) and may be, for example, a recording medium such as cloth (fabric), a substrate, etc. 
     The liquid discharged or ejected from the nozzles is not limited to the ink, and may be an arbitrary liquid (e.g., a treating liquid, etc., which causes a component in the ink to aggregate or precipitate). 
     The present disclosure is not limited to the printer, and is also applicable to a facsimile machine, a copying machine, a multi-functional peripheral, etc. The present disclosure is also applicable to a liquid discharging apparatus used for an application different from the recording of an image (for example, a liquid discharging apparatus which discharges or ejects a conductive liquid onto a substrate to thereby form a conductive pattern on the substrate). 
     Note that the all the above-described embodiments and modifications may be combined with each other, unless mutually exclusive with one another.