Patent Publication Number: US-11046075-B2

Title: Liquid ejecting head and liquid ejecting apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-034129, filed Feb. 27, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a liquid ejecting head and a liquid ejecting apparatus. 
     2. Related Art 
     In the related art, an ink jet recording apparatus including a liquid ejecting head is known (for example, JP-A-2012-143948). In this ink jet recording apparatus, the liquid ejecting head includes a plurality of communication passages having pressure generation chambers, a common liquid chamber and a circulation flow channel as a common liquid chamber, which communicate in common with the plurality of communication passages, and a circulation communication passage through which corresponding one of the communication passages and the circulation flow channel communicate with each other for each communication passage. 
     In the liquid ejecting head according to the related art, when a coupling port between the circulation communication passage and the circulation flow channel is changed to face a direction intersecting the nozzle plate, bubbles heading from the circulation communication passage to the circulation flow channel tend to move in the intersecting direction by a buoyant force. Thus, the bubbles may be caught at the coupling portion between the circulation communication passage and the circulation flow channel. When the bubbles are caught at the coupling portion, the bubbles may stay in the coupling portion. 
     SUMMARY 
     According to an aspect of the present disclosure, a liquid ejecting head is provided. This liquid ejecting head includes: a nozzle plate provided with a nozzle for ejecting a liquid; a flow channel forming substrate which is stacked on the nozzle plate and has a plurality of individual flow channels each including a pressure chamber communicating with the nozzle and arranged in an arrangement direction that is one of in-plane directions of the nozzle plate, a first common liquid chamber coupled to the plurality of individual flow channels, and a second common liquid chamber coupled to the plurality of individual flow channels and coupled to the first common liquid chamber via the plurality of individual flow channels; and a pressure generating element that causes a pressure change in the liquid in the pressure chamber, in which in a vertical direction perpendicular to an in-plane direction of the nozzle plate, when a side of the flow channel forming substrate with respect to the nozzle plate is set as one side and a side of the nozzle plate with respect to the flow channel forming substrate is set as another side, each of the plurality of individual flow channels has an outlet flow channel coupled to the second common liquid chamber and extending in the in-plane direction and a coupling flow channel having a coupling port coupled to the outlet flow channel, the coupling flow channel extends from the one side to the other side toward the coupling port, the outlet flow channel has an outlet portion through which the liquid flows into the second common liquid chamber and which faces the in-plane direction, the second common liquid chamber has an introduction flow channel which is coupled to the outlet portion and through which the liquid flows along the in-plane direction, and the flow channel forming substrate has a partition wall which is disposed between two of the outlet flow channels adjacent to each other and which partitions the outlet flow channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram schematically illustrating a configuration of a liquid ejecting apparatus according to an embodiment of the present disclosure. 
         FIG. 2  is a schematic sectional view of a liquid ejecting head in an XY plane. 
         FIG. 3  is a schematic sectional view of the liquid ejecting head, which is taken along line III-III of  FIG. 2 . 
         FIG. 4  is an enlarged view of a region indicated by a one-dot chain line in  FIG. 3 . 
         FIG. 5  is a partial schematic view, which is taken along line V-V of  FIG. 3 . 
         FIG. 6  is a schematic sectional view of a liquid ejecting head according to a second embodiment. 
         FIG. 7  is a schematic sectional view of a liquid ejecting head according to a third embodiment. 
         FIG. 8  is a diagram illustrating an example of an individual flow channel in another first embodiment. 
         FIG. 9  is a schematic view illustrating an example of a liquid ejecting head according to another second embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     A. First Embodiment 
       FIG. 1  is a diagram schematically illustrating a configuration of a liquid ejecting apparatus  100  according to an embodiment of the present disclosure. The liquid ejecting apparatus  100  is an ink jet printing apparatus that ejects an ink, which is an example of a liquid, onto a medium  12 . The medium  12  is a printing target made of any material such as a resin film and a cloth in addition to a printing paper sheet, and the liquid ejecting apparatus  100  performs printing on such various types of media  12 . In an X direction, a Y direction, and a Z direction perpendicular to each other, in each of the drawings, a main scanning direction that is a movement direction of a liquid ejecting head  26 , which will be described below, is set as the X direction, a sub scanning direction that is a medium feeding direction perpendicular to the main scanning direction is set as the Y direction, and an ink ejecting direction is set as the Z direction. Further, when a direction is specified, a positive direction is set as “+” and a negative direction is set as “−”. In this case, both positive and negative signs are used to indicate the direction. The liquid ejecting head  26  may not move in the X direction or the liquid ejecting head  26  may move relative to the medium  12  in the Y direction. 
     The liquid ejecting apparatus  100  includes a liquid storage container  14 , a transport mechanism  22  that sends out the medium  12 , a control unit  20 , a head movement mechanism  24 , and the liquid ejecting head  26 . The liquid storage container  14  stores a liquid supplied to the liquid ejecting head  26 . A bag-like ink pack formed of a flexible film, an ink tank that can be refilled with the ink or the like can be used as the liquid storage container  14 . The control unit  20  includes a processing circuit such as a central processing unit (CPU) and a storage circuit such as a semiconductor memory, and comprehensively controls the transport mechanism  22 , the head movement mechanism  24 , the liquid ejecting head  26 , and the like. The transport mechanism  22  is operated under a control of the control unit  20 , and sends out the medium  12  in the +Y direction. 
     The head movement mechanism  24  includes a transport belt  23  wound in the X direction over a printing range of the medium  12  and a carriage  25  in which the liquid ejecting head  26  is accommodated and which is fixed to the transport belt  23 . The head movement mechanism  24  is operated under the control of the control unit  20 , and causes the carriage  25  to reciprocate in the X direction that is the main scanning direction of the liquid ejecting head  26 . When the carriage  25  reciprocates, the carriage  25  is guided by a guide rail that is not illustrated. The liquid ejecting head  26  has a plurality of nozzles  126  arranged in the Y direction that is the sub scanning direction. A head configuration in which a plurality of the liquid ejecting heads  26  are mounted on the carriage  25  or a head configuration in which the liquid storage container  14  together with the liquid ejecting head  26  is mounted on the carriage  25  may be employed. 
       FIG. 2  is a schematic sectional view of the liquid ejecting head  26  in an XY plane. The liquid ejecting head  26  includes a flow channel formation substrate in which a plurality of individual flow channels  36 , one first common liquid chamber  32 , and one second common liquid chamber  34  are formed. The first common liquid chamber  32  and the second common liquid chamber  34  are coupled to communicate with each other via the plurality of individual flow channels  36 . 
     The liquid storage container  14  and the liquid ejecting head  26  are coupled to each other via a supply flow channel  142  and a recovery flow channel  144  in a state in which the liquid can circulate. The supply flow channel  142  is coupled to a supply port  322  formed in the first common liquid chamber  32  of the liquid ejecting head  26 . The recovery flow channel  144  is coupled to a discharge port  342  formed in the second common liquid chamber  34  of the liquid ejecting head  26 . The recovery flow channel  144  is provided with a pump  146 . The pump  146  sends out the liquid from the liquid ejecting head  26  side to the liquid storage container  14  side, and causes the liquid to circulate between the liquid ejecting head  26  and the liquid storage container  14 . The supply flow channel  142  may be provided with a pump. Further, the number of each of the first common liquid chamber  32  and the second common liquid chamber  34  is not limited to one. For example, the number of at least one of the first common liquid chamber  32  and the second common liquid chamber  34  may be two or more. 
     The liquid in the liquid ejecting head  26  circulates through the following path. The liquid supplied from the liquid storage container  14  via the supply flow channel  142  first flows into the first common liquid chamber  32 . The liquid that has flowed into the first common liquid chamber  32  flows into each of the plurality of individual flow channels  36  coupled to the first common liquid chamber  32 . The liquid that has flowed into the plurality of individual flow channels  36  flows into the second common liquid chamber  34  that is commonly coupled to the plurality of individual flow channels  36 . The liquid in the second common liquid chamber  34  is recovered into the liquid storage container  14  via the recovery flow channel  144 . The liquid recovered in the liquid storage container  14  is supplied to the liquid ejecting head  26  via the supply flow channel  142  again. 
       FIG. 3  is a schematic sectional view of the liquid ejecting head  26 , which is taken along line III-III of  FIG. 2 . As described above, the liquid ejecting head  26  includes, as a flow channel structure, the first common liquid chamber  32 , the second common liquid chamber  34 , and the individual flow channels  36 . In  FIG. 3 , although only one individual flow channel  36  is illustrated, the plurality of individual flow channels  36  are arranged in the Y direction that is a depth direction of the figure. Further, the first common liquid chamber  32  and the second common liquid chamber  34  are commonly coupled to the plurality of individual flow channels  36 . Therefore, the depth of the first common liquid chamber  32  and the second common liquid chamber  34 , that is the dimension in the Y direction in  FIG. 3 , is larger than the depth of each individual flow channel  36 . 
     The first common liquid chamber  32  has a larger dimension in the Z direction, which is a direction perpendicular to a nozzle surface  61 , than that of the individual flow channel  36 . The nozzle surface  61  is a wall surface, at which the nozzles  126  are formed, among the outer wall surfaces of the liquid ejecting head  26 . The first common liquid chamber  32  has an inlet portion  324  through which the liquid flows from the first common liquid chamber  32  into the individual flow channel  36 . The inlet portion  324  is provided at a position facing the bottom surface of the first common liquid chamber  32 . A plurality of the inlet portions  324  are provided in the Y direction as an arrangement direction. Each of the plurality of inlet portions  324  has an opening facing the −Z direction. In the present embodiment, the supply port  322  coupled to the supply flow channel  142  illustrated in  FIG. 2  is formed at the top surface of the first common liquid chamber  32 , which is not illustrated. Further, the individual flow channel  36  may have a larger dimension in the Z direction than that of the first common liquid chamber  32 . 
     Each of the plurality of individual flow channels  36  has a pressure chamber  364 , a first flow channel  362 , a second flow channel  365 , a third flow channel  366 , a coupling flow channel  367 , and an outlet flow channel  369 . The plurality of individual flow channels  36  communicate with the nozzles  126  having openings for ejecting the liquid in a flow channel downstream of the pressure chamber  364 . The pressure chamber  364  has a space for applying a pressure to the liquid in the individual flow channel  36 . A part of the liquid to which the pressure is applied is ejected from the nozzle  126 . Further, a part of the liquid that has not been ejected from the nozzle  126  may move to the first common liquid chamber  32  and the second common liquid chamber  34  coupled by the individual flow channel  36 . At this time, vibration generated in the pressure chamber  364  when the pressure is applied propagates, as residual vibration, to the first common liquid chamber  32  and the second common liquid chamber  34  at the inflow of the liquid. Accordingly, residual vibration generated in the individual flow channel  36  by itself is reduced. 
     The first flow channel  362  is a flow channel that couples the inlet portion  324  provided in the first common liquid chamber  32  and the pressure chamber  364 , and a flow channel extending from the inlet portion  324  toward the pressure chamber  364  in the +Z direction. The second flow channel  365  is a flow channel from the pressure chamber  364  to the nozzle  126 , and has a flow channel extending from the pressure chamber  364  in the −Z direction and a flow channel extending from a downstream end of the flow channel extending from the pressure chamber  364  in the −Z direction toward the nozzle  126  in the −X direction. The third flow channel  366  is a flow channel from the nozzle  126  to the coupling flow channel  367 . The third flow channel  366  has a flow channel extending from the nozzle  126  in the −X direction, a flow channel extending in the +Z direction from a downstream end of the flow channel extending in the −X direction, and a flow channel extending from a downstream end of the flow channel extending in the +Z direction toward the coupling flow channel  367  in the −X direction. 
     The coupling flow channel  367  is a flow channel extending from a downstream end of the third flow channel  366  toward the outlet flow channel  369  in the −Z direction. The coupling flow channel  367  has a coupling port  368  which is coupled to the outlet flow channel  369  and through which the liquid in the coupling flow channel  367  flows into the outlet flow channel  369 . An opening of the coupling port  368  faces the −Z direction which is a direction perpendicular to the in-plane direction of a nozzle plate  60 . 
     The outlet flow channel  369  is a flow channel coupled to the second common liquid chamber  34  and extending from the coupling port  368  toward the second common liquid chamber  34  in the −X direction. The outlet flow channel  369  has an outlet portion  344  through which the liquid in the outlet flow channel  369  flows into the second common liquid chamber  34 . 
     The outlet portion  344  is formed at one (side surface  438 ) of the side surfaces of the second common liquid chamber  34  on a side where the first common liquid chamber  32  is provided. A plurality of the outlet portions  344  are provided in the Y direction. Opening of the outlet portion  344  is a direction along the in-plane direction of the nozzle surface  61 , and faces the −X direction perpendicular to the Y direction that is an arrangement direction of the individual flow channels  36 . 
     Similar to the first common liquid chamber  32 , the second common liquid chamber  34  has a larger dimension in the Z direction, which is a direction perpendicular to the nozzle surface  61 , than that of the individual flow channel  36 . In the present embodiment, the discharge port  342  coupled to the recovery flow channel  144  illustrated in  FIG. 2  is formed at the top surface of the second common liquid chamber  34 , which is not illustrated. Further, the individual flow channel  36  may have a larger dimension in the Z direction than that of the second common liquid chamber  34 . 
     Hereinafter, a member constituting the liquid ejecting head  26  will be described. The liquid ejecting head  26  includes, as a member forming a flow channel structure, a flow channel forming substrate  40 , the nozzle plate  60 , a first film  62 , and a second film  64 . The flow channel forming substrate  40  is formed by a first communication plate  42 , a second communication plate  44 , a pressure chamber forming substrate  46 , a sealing member  47 , and a case  52 . Each of the first communication plate  42 , the second communication plate  44 , the pressure chamber forming substrate  46 , the sealing member  47 , and the nozzle plate  60  is formed of a silicon single crystal plate. On the other hand, the case  52  is formed of a resin molded product such as plastic. In the liquid ejecting head  26 , the nozzle plate  60 , the first communication plate  42 , the second communication plate  44 , and the case  52  are stacked in the order thereof from the −Z direction to the +Z direction. Further, the nozzle plate  60 , the first communication plate  42 , the second communication plate  44 , and the pressure chamber forming substrate  46  are stacked in the order thereof from the −Z direction to the +Z direction. That is, a direction from the nozzle plate  60  toward the flow channel forming substrate  40  is the +Z direction, and a direction from the flow channel forming substrate  40  toward the nozzle plate  60  is the −Z direction. The first communication plate  42  and the second communication plate  44  are plate-like members extending in the XY plane, respectively. The flow channel forming substrate  40  and the nozzle plate  60  may be formed of a material other than a silicon single crystal plate or a resin, for example, any of various materials such as metal and glass. 
     The flow channel forming substrate  40  forms the first common liquid chamber  32 , the second common liquid chamber  34 , and the plurality of individual flow channels  36 . In detail, a first opening portion  432  formed by the first communication plate  42 , the second communication plate  44 , and the case  52  in the flow channel forming substrate  40  forms the first common liquid chamber  32 . In detail, a second opening portion  434  formed by the first communication plate  42 , the second communication plate  44 , and the case  52  in the flow channel forming substrate  40  forms the second common liquid chamber  34 . Each of the first opening portion  432  and the second opening portion  434  is open in the −Z direction. The first opening portion  432  and the second opening portion  434  are formed side by side in the X direction with a region forming the individual flow channel  36  in between. The individual flow channel  36  is formed by the first communication plate  42 , the second communication plate  44 , the pressure chamber forming substrate  46 , and the sealing member  47  in the flow channel forming substrate  40 . The first communication plate  42  in the flow channel forming substrate  40  has a partition wall  428  that partitions a plurality of the outlet flow channels  369 . The pressure chamber  364  in the individual flow channel  36  is formed by the pressure chamber forming substrate  46 . 
     The first film  62  is attached to the flow channel forming substrate  40  from the −Z direction side to cover the first opening portion  432  that forms the first common liquid chamber  32 . The first film  62  defines an internal space of the first common liquid chamber  32  together with the first opening portion  432 . The first film  62  is a film member formed of a flexible resin. The first film  62  may be formed of a material other than resin, for example, any of various materials such as thin film metal. 
     The second film  64  is attached to the flow channel forming substrate  40  from the −Z direction side to cover the second opening portion  434  that forms the second common liquid chamber  34 . The second film  64  defines an internal space of the second common liquid chamber  34  together with the second opening portion  434 . Similar to the first film  62 , the second film  64  is a film member formed of a flexible resin. The second film  64  may be formed of a material other than resin, for example, any of various materials such as thin film metal. 
     The bottom surface of the first common liquid chamber  32  is defined by the first film  62 . Further, the bottom surface of the second common liquid chamber  34  is defined by the second film  64 . The compliance of the first common liquid chamber  32  and the second common liquid chamber  34  are improved by the flexibility of the first film  62  and the second film  64 . Therefore, the occurrence of crosstalk in which the pressure fluctuation generated in one pressure chamber  364  is propagated to another pressure chamber  364  via the first common liquid chamber  32  or the second common liquid chamber  34  is suppressed. 
     The first film  62  and the second film  64  are fixed by being bonded to the flow channel forming substrate  40  using an adhesive. The first film  62  is bonded to the −Z side end surface of the first communication plate  42  located at an outer edge of the first opening portion  432 . Further, the second film  64  is bonded to the −Z side end surface of the first communication plate  42  located at an outer edge of the second opening portion  434 . In the present embodiment, the second film  64  is not bonded to the partition wall  428  in the outlet flow channel  369 . 
     When viewed from the Z direction, the nozzle plate  60  is affixed to the flow channel forming substrate  40  from the −Z direction side at a position that overlaps a region of the flow channel forming substrate  40  where the individual flow channels  36  are formed. The nozzle plate  60  has nozzle openings that form the nozzles  126 . The nozzle plate  60  defines the nozzle surface  61  of the liquid ejecting head  26 . In the present embodiment, the nozzle surface  61  extends along a direction perpendicular to the Z direction, that is, the XY plane. The nozzle plate  60  may be formed of a material other than the silicon single crystal plate, for example, any of various materials such as metal and resin. For example, the nozzle plate  60  may be formed of a flexible resin. 
     A pressure generating element  70  for causing a pressure change in the liquid in the pressure chamber  364  is disposed on the +Z direction side of the pressure chamber forming substrate  46  while being covered with a protective substrate  48 . In the present embodiment, a piezoelectric element is used as the pressure generating element  70 . The pressure generating element  70  is electrically coupled to an electrode  72  disposed at a position overlapping the individual flow channel  36  in the Z direction. In the present embodiment, the liquid ejecting apparatus  100  is a piezo ink jet printer in which a piezoelectric element is employed as a pressure generating element. However, the present disclosure is not limited thereto. For example, the liquid ejecting apparatus  100  may be a thermal ink jet printer that includes, instead of the piezoelectric element, the pressure generating element that changes the pressure in the pressure chamber  364  by heating the liquid in the pressure chamber  364 . 
     The flow channel forming substrate  40  has a first through-hole  412  and a second through-hole  414  in addition to openings of the first opening portion  432  and the second opening portion  434 . The first through-hole  412  is an opening that forms the first flow channel  362  that is a flow channel of the individual flow channel  36  between the first common liquid chamber  32  and the pressure chamber  364 . The second through-hole  414  is an opening that forms a part of the third flow channel  366  that is a flow channel of the individual flow channel  36  between the second common liquid chamber  34  and the pressure chamber  364 . In detail, the second through-hole  414  forms a flow channel extending in the Z direction among the third flow channel  366 . 
     The cross-sectional area of the first through-hole  412  is smaller than the cross-sectional area of the second through-hole  414 . Therefore, the liquid is less likely to flow in the first flow channel  362  formed by the first through-hole  412  than in the third flow channel  366  formed by the second through-hole  414 . Accordingly, the pressure fluctuation in the pressure chamber  364  is efficiently propagated to the nozzle  126  coupled to the individual flow channel  36  between the pressure chamber  364  and the third flow channel  366 . Therefore, the liquid can be efficiently ejected from the nozzle  126 . Although the cross-sectional area of the first through-hole  412  is smaller than the cross-sectional area of the second through-hole  414 , the present disclosure is not limited thereto. The cross-sectional area of the first through-hole  412  may be equal to or larger than the cross-sectional area of the second through-hole  414 . Further, the second through-hole  414  may form a flow channel of the coupling flow channel  367 , which extends in the −Z direction. 
     In the individual flow channel  36 , the flow channel resistance of a flow channel between the first common liquid chamber  32  and the nozzle  126  is the same as the flow channel resistance of a flow channel between the second common liquid chamber  34  and the nozzle  126 . In detail, the flow channel between the first common liquid chamber  32  and the nozzle  126  is a series of flow channels including the first flow channel  362 , the pressure chamber  364 , and the second flow channel  365 . In detail, the flow channel between the second common liquid chamber  34  and the nozzle  126  is a series of flow channels including the third flow channel  366 , the coupling flow channel  367 , and the outlet flow channel  369 . In this case, the pressure difference between the first common liquid chamber  32  and the second common liquid chamber  34  can be reduced. Accordingly, adjustment of a meniscus position of the nozzle  126  is facilitated. A case where the flow channel resistances are the same includes not only a case where the flow channel resistances are exactly the same but also a case where the flow channel resistances can be regarded as the same in design. In detail, the difference is preferably within 50%, and is more preferably within 10%. 
     Hereinafter, distribution channel of bubbles in the liquid ejecting head  26  will be described. For example, when the liquid ejecting head  26  is initially filled with the liquid, when the bubbles existing in the liquid storage container  14  flows inward, or when bubbles flow inward from the nozzle  126 , the bubbles may flow into the liquid ejecting head  26 . The liquid that has flowed into the first common liquid chamber  32  flows into the individual flow channel  36 . Since the individual flow channel  36  is suctioned by the pump illustrated in  FIG. 2 , and thus the pressure of the individual flow channel  36  is smaller than the pressure of the first common liquid chamber  32 , the bubbles easily flow into the individual flow channel  36 . Therefore, staying of the bubbles in the first common liquid chamber  32  near the inlet portion  324  is suppressed. Accordingly, inhibition of inflow of the liquid from the first common liquid chamber  32  to the individual flow channel  36  by the bubbles is suppressed. 
     The bubbles that have flowed into the individual flow channel  36  from the first common liquid chamber  32  flow into the second common liquid chamber  34 . The individual flow channel  36  has a smaller flow-channel cross-sectional area than that of the first common liquid chamber  32  and the second common liquid chamber  34 . Therefore, since a flow rate of the liquid is high in the individual flow channel  36 , particularly, in a section from the inlet portion  324  to the coupling port  368 , the bubbles move smoothly. The bubbles that have flowed into the second common liquid chamber  34  pass through an introduction flow channel  341  to move to the recovery flow channel  144  illustrated in  FIG. 2 . The introduction flow channel  341  is a flow channel which is coupled to the outlet portion  344  of the second common liquid chamber  34  and through which the liquid flows in the −X direction. The bubbles that have moved to the recovery flow channel  144  flow out to the liquid storage container  14 . The liquid ejecting head  26  may not cause the bubbles that have flowed into the liquid ejecting head  26  to flow out to the liquid storage container  14 . For example, the liquid ejecting head  26  may include a configuration for removing the bubbles, for example, a filter that catches the bubbles and a deaeration mechanism for deaeration in the flow channel such as the first common liquid chamber  32 . Thus, the bubbles may be removed from the liquid ejecting head  26  without flowing into the liquid storage container  14 . 
       FIG. 4  is an enlarged view of a region indicated by a one-dot chain line IV in  FIG. 3 . When the bubbles flow into the outlet flow channel  369  from the coupling port  368  through the coupling flow channel  367 , the movement direction of the bubbles is the −Z direction that is an opening direction of the coupling port  368 . A buoyant force in the +Z direction and a force in the −X direction received from the liquid flowing through the outlet flow channel  369  are applied to the bubbles that have flowed into the outlet flow channel  369  from the coupling port  368 . Accordingly, as indicated by the arrow, the movement direction of the bubbles in the outlet flow channel  369  is changed from the −Z direction that is the opening direction of the coupling port  368  to the −X direction that is a flow direction of the liquid. 
       FIG. 5  is a partial schematic view, which is taken along line V-V of  FIG. 3 . The partition walls  428  are provided with every part between the two adjacent coupling ports  368 . Accordingly, the outlet flow channel  369  is provided at each coupling port  368 , and one outlet flow channel  369  is provided at one coupling port  368 . Therefore, an interval between the two adjacent partition walls  428  in the Y direction is smaller than the width of the second common liquid chamber  34  in the Y direction. Therefore, the flow rate of the liquid in the outlet flow channel  369  is larger than the flow rate of the liquid in the second common liquid chamber  34 . Further, each of the plurality of partition walls  428  extends from the coupling port  368  toward the second common liquid chamber  34  in the −X direction. 
     The bubbles flow from the +Z direction to the −Z direction through the coupling flow channel  367 , and then flow from the +X direction to the −X direction through the outlet flow channel  369 . That is, in the outlet flow channel  369 , the movement direction of the bubbles flowing from the coupling flow channel  367  to the second common liquid chamber  34  is changed from the flow in the Z direction to the flow in the X direction. In the outlet flow channel  369 , since the flow-channel cross-sectional area is reduced by the partition wall  428 , the flow rate is large. Therefore, a force applied to the bubbles in the −X direction in the outlet flow channel  369  illustrated in  FIG. 4  is large. Accordingly, the above-described movement direction of the bubbles is smoothly changed. Accordingly, changing of the movement direction of the bubbles that have flowed into the outlet flow channel  369  can suppress staying of the bubbles near the coupling port  368 . 
     Further, as illustrated in  FIG. 5 , the flow channel direction of the outlet flow channel  369  and the opening direction of the outlet portion  344  defined by the outlet flow channel  369  coincide with the communication direction of the liquid in the introduction flow channel  341  of the second common liquid chamber  34 . Therefore, the bubbles moved from the outlet portion  344  to the second common liquid chamber  34  move in the −X direction together with the liquid without greatly changing the movement direction. Therefore, the movement of the bubbles flowing into the second common liquid chamber  34  from the outlet portion  344  is smooth. 
     According to the above-described first embodiment, a difference between a direction in which the liquid flows in the second common liquid chamber  34  and a direction of the outlet portion  344  can be reduced. Further, as the partition wall  428  that partitions the outlet flow channel  369  is provided, the flow-channel cross-sectional area of the outlet flow channel  369  is smaller than that when the partition wall  428  is not provided. Accordingly, the flow rate of the liquid in the outlet flow channel  369  increases. Therefore, when the bubbles together with the liquid flow between the individual flow channel  36  and the second common liquid chamber  34 , the bubbles that have flowed into the outlet flow channel  369  from the coupling port  368  move smoothly. Therefore, occurrence of catching of the bubbles in the coupling port  368  can be suppressed. Accordingly, ejection failure of the nozzle  126  due to obstruction of the flow of the liquid in the individual flow channel  36  due to the bubbles caught in the coupling port  368  is suppressed. 
     B. Second Embodiment 
       FIG. 6  is a schematic sectional view of a liquid ejecting head  226  according to a second embodiment. The liquid ejecting head  226  according to the second embodiment is different from the liquid ejecting head  26  according to the first embodiment in terms of a structure of a partition wall  628  that forms the outlet flow channel  369 . Hereinafter, the same configurations as those according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. 
     A plurality of the partition walls  628  and the second film  64  are separated from each other. In detail, in the Z direction, a gap is formed between the second film  64  and a bottom surface  629  on the −Z side among the wall surfaces of the partition wall  628 . Accordingly, when the flow channel forming substrate  40  and the second film  64  are bonded to each other using an adhesive, flow of the adhesive to the partition wall  628  side is suppressed. Therefore, bonding between the partition wall  628  and the second film  64  is suppressed. Accordingly, a reduction in a movable range of the second film  64  by bonding the partition wall  628  and the second film  64  is suppressed. Therefore, a reduction in the compliance of the second common liquid chamber  34  is suppressed. Therefore, the occurrence of crosstalk in which the pressure fluctuation generated in one pressure chamber  364  is propagated to the other pressure chamber  364  via the second common liquid chamber  34  is further suppressed. 
     C. Third Embodiment 
       FIG. 7  is a schematic sectional view of a liquid ejecting head  526  according to a third embodiment. The liquid ejecting head  526  according to the third embodiment is different from the liquid ejecting head  26  according to the first embodiment and the liquid ejecting head  226  according to the second embodiment in terms of a structure of a partition wall  728  that forms the outlet flow channel  369 . Hereinafter, the same configurations as those according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. 
     Similar to the second embodiment, in the liquid ejecting head  526 , a plurality of the partition walls  728  and the second film  64  are separated from each other. Accordingly, bonding between the partition wall  728  and the second film  64  is suppressed. Therefore, a reduction in the movable range of the second film  64  by bonding the partition wall  728  and the second film  64  is suppressed. Therefore, a reduction in the compliance of the second common liquid chamber  34  is suppressed. 
     The partition wall  728  has a rounded shape at a corner portion  730  where a bottom surface  729  on the −Z direction side and a surface that forms the outlet portion  344  and defines a side surface  438  of the second common liquid chamber  34 . Accordingly, sharpening of the corner portion  730  can be suppressed. Here, the second film  64  may be bent in a bending direction dm illustrated in  FIG. 7 . When the second film  64  is bent in the bending direction dm, the corner portion  730  of the partition wall  728  comes into contact with the second film  64 . In the partition wall  728 , the corner portion  730  is not sharpened. Thus, even when the corner portion  730  and the second film  64  are in contact with each other, damage of the second film  64  due to contact with the partition wall  728  can be suppressed. The shape of the corner portion  730  is not limited to the rounded shape, and may have a non-pointed shape having a tapered shape. 
     D. Other Embodiment 
     D1. First Other Embodiment 
     In the above embodiment, the outlet flow channel  369  is provided in each coupling port  368 . However, the present disclosure is not limited thereto. For example, one outlet flow channel  369  may be provided for a plurality of the coupling ports  368 . In this case, all the plurality of partition walls  428 ,  528 , and  728  may not be provided between the two adjacent coupling ports  368 . When one outlet flow channel  369  is provided for the plurality of coupling ports  368 , one individual flow channel  36  includes a plurality of flow channels coupled to one outlet flow channel  369 , specifically, a series of flow channels from the first flow channel  362  to the coupling flow channel  367 . Further, the partition walls  428 ,  528 , and  728  do not have to be plural, and may be only one. Even in this case, the flow-channel cross-sectional area of the outlet flow channel  369  can be smaller than that when the partition walls  428 ,  528 , and  728  are not provided. 
       FIG. 8  is a diagram illustrating an example of an individual flow channel  36 A according to another first embodiment. The individual flow channel  36 A has one outlet flow channel  369  and two coupling ports  368  coupled to the one outlet flow channel  369 . In this case, the individual flow channel  36 A includes two flow channels coupled through the two coupling ports  368  and extending from the first flow channel  362  to the coupling flow channel  367 . That is, the individual flow channel  36 A has two pressure chambers  364 . The two pressure chambers  364  communicate with different nozzles  126 , respectively. 
     D2. Second Other Embodiment 
       FIG. 9  is a schematic view illustrating an example of a liquid ejecting head  26 B according to another second embodiment. The flow channel structure of the individual flow channels  36  and  36 A is not limited to that according to the above embodiments. For example, as illustrated in  FIG. 9 , in the individual flow channel  36 B, the pressure chamber  364  may be provided downstream of the nozzle  126 . In this case, it is preferable that the cross-sectional area of a first through-hole  412 B that forms a first flow channel  362 B is smaller than the cross-sectional area of a third through-hole  415  that forms the coupling flow channel  367 . In this case, the liquid can be less likely to flow in the first flow channel  362 B formed by the first through-hole  412 B than in the coupling flow channel  367  formed by the third through-hole  415 . Accordingly, the pressure fluctuation in the pressure chamber  364  is efficiently propagated to the nozzle  126  coupled to the individual flow channel  36 B between the pressure chamber  364  and the first flow channel  362 . Therefore, the liquid can be efficiently ejected from the nozzle  126 . 
     D3. Third Other Embodiment 
     In the above embodiment, the flow channel resistance of a flow channel of the individual flow channel  36  between the first common liquid chamber  32  and the nozzle  126  is the same as the flow channel resistance of a flow channel of the individual flow channel  36  between the second common liquid chamber  34  and the nozzle  126 . However, the present disclosure is not limited thereto. For example, the flow channel resistance of the flow channel between the first common liquid chamber  32  and the nozzle  126  may be smaller or larger than the flow channel resistance of the flow channel between the second common liquid chamber  34  and the nozzle  126 . 
     D4. Fourth Other Embodiment 
     In the above embodiment, the coupling flow channel  367  extends to be perpendicular to the nozzle surface  61 . However, the present disclosure is not limited thereto. For example, the coupling flow channel  367  may extend in a direction other than a vertical direction that intersects the nozzle surface  61 . 
     D5. Fifth Other Embodiment 
     In the above embodiment. an opening of the outlet portion  344  faces the −X direction that is a direction perpendicular to the Y direction that is the arrangement direction of the individual flow channels  36  among the nozzle surface  61 . However, the present disclosure is not limited thereto. The opening of the outlet portion  344  may extend in a direction other than the vertical direction intersecting the Y direction that is the arrangement direction of the individual flow channels  36  among the nozzle surface  61 . 
     D6. Sixth Other Embodiment 
     In the above embodiment, the first common liquid chamber  32  does not have a wall provided between the first common liquid chamber  32  and the plurality of inlet portions  324 . However, the present disclosure is not limited thereto. For example, the first common liquid chamber  32  may have an inlet wall provided between the first common liquid chamber  32  and the plurality of inlet portions  324 . In this case, it is preferable that the dimension of the inlet wall c the first common liquid chamber  32  and the plurality of inlet portions  324  in the Z direction that is a direction perpendicular to the nozzle surface  61  is smaller than the dimension of the partition walls  428 ,  528 , and  728  in the Z direction. In this case, the bubbles are easy to block the inlet portions  324 , and the bubbles blocking the inlet portions  324  smoothly flow into the inlet portions  324  due to drag. In the above embodiment, the dimension of the wall provided between the first common liquid chamber  32  and the plurality of inlet portions  324  in the Z direction is zero. Therefore, the dimension of the wall provided between the first common liquid chamber  32  and the plurality of inlet portions  324  in the Z direction that is perpendicular to the nozzle surface  61  is smaller than the dimension of the partition walls  428 ,  528 , and  728  in the Z direction. Even when the dimension of the inlet wall in the Z direction is smaller than the dimension of the partition walls  428 ,  528 , and  728  in the Z direction, if the cross-sectional area of the through-hole  412  of the first flow channel  362  is smaller than the cross-sectional area of the second through-hole  414  of the coupling flow channel  367 , the flow channel resistance of the flow channel between the first common liquid chamber  32  and the nozzle  126  and the flow channel resistance of the flow channel between the second common liquid chamber  34  and the nozzle  126  may be the same. 
     D7. Seventh Other Embodiment 
     In the above embodiment, the second film  64  is used as a member defining the bottom surface of the second common liquid chamber  34 . However, the present disclosure is not limited thereto. For example, the member defining the bottom surface of the second common liquid chamber  34  may be a member that does not have flexibility. In this case, the compliance of the second common liquid chamber  34  may be improved by a property other than the flexibility of the bottom surface of the second common liquid chamber  34 . For example, the compliance may be improved by an opening provided in the second common liquid chamber  34 , specifically, for example, the size and the position of the discharge port  342 . Further, a flexible member may be used at a position other than the bottom surface of the second common liquid chamber  34 . 
     The first to seventh other embodiments have the same effect as the first to third embodiments in that the first to seventh other embodiments have the same configuration as the first to third embodiments. 
     D8. Eighth Other Embodiment 
     The present disclosure is not limited to an ink jet printer and an ink tank for supplying an ink to the ink jet printer, and can be applied to a predetermined liquid ejecting apparatus that ejects various liquids including the ink and a liquid tank that stores the liquids. For example, the present disclosure can be applied to the following various liquid ejecting apparatuses and the following liquid storage containers thereof.
     (1) An image recording apparatus such as a facsimile machine,   (2) A color material ejecting apparatus used for manufacturing a color filter for an image display device such as a liquid crystal display,   (3) An electrode material ejecting apparatus used for forming an electrode of an organic electro luminescence (EL) display, a surface light emission display (a field emission display, FED), and the like,   (4) A liquid ejecting apparatus that ejects a liquid containing a bio-organic material used for manufacturing a biochip,   (5) A sample ejecting apparatus as a precision pipette,   (6) A lubricating oil ejecting apparatus,   (7) A resin liquid ejecting apparatus,   (8) A liquid ejecting apparatus that ejects a lubricating oil to a precision machine such as a timepiece and a camera using a pinpoint,   (9) A liquid ejecting apparatus that ejects a transparent resin liquid such as an ultraviolet curable resin liquid onto a substrate in order to form a micro hemispherical lens (optical lens) used for an optical communication element or the like,   (10) A liquid ejecting apparatus that ejects an acidic or alkaline etching solution for etching a substrate or the like, and   (11) A liquid ejecting apparatus including a liquid ejecting head that ejects the small amount of other predetermined liquid droplets.   

     The “liquid droplets” refer to a state of the liquid ejected from the liquid ejecting apparatus, which includes a particle shape, a tear shape, and a shape obtained by pulling a tail in a thread shape. Further, the “liquid” herein may be any material that can be ejected by the liquid ejecting apparatus. For example, the “liquid” may be a material in a state in which a substance is in a liquid phase, and also includes a liquid material such as a material in a liquid state having high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals (metallic melts). Further, the “liquid” includes not only a liquid as one state of a substance but also a liquid in which particles of a functional material made of a solid such as a pigment or metal particles are dissolved, dispersed, or mixed in a solvent. Further, representative examples of the liquid include the ink, the liquid crystal, and the like as described in the above embodiment. Here, the ink includes various liquid compositions such as general water-based ink, oil-based ink, and gel ink. 
     The present disclosure is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the summary of the present disclosure can be appropriately replaced or combined in order to solve some or the entirety of the above-described problems or achieve some or the entirety of the above-described effects. Further, when the technical features are not described as essential in the present specification, the technical features can be deleted as appropriate. 
     (1) According to an aspect of the present disclosure, a liquid ejecting head is provided. This liquid ejecting head includes: a nozzle plate provided with a nozzle for ejecting a liquid; a flow channel forming substrate which is stacked on the nozzle plate and has a plurality of individual flow channels each including a pressure chamber communicating with the nozzle and arranged in an arrangement direction that is one of in-plane directions of the nozzle plate, a first common liquid chamber coupled to the plurality of individual flow channels, and a second common liquid chamber coupled to the plurality of individual flow channels and coupled to the first common liquid chamber via the plurality of individual flow channels; and a pressure generating element that causes a pressure change in the liquid in the pressure chamber, in which in a vertical direction perpendicular to an in-plane direction of the nozzle plate, when a side of the flow channel forming substrate with respect to the nozzle plate is set as one side and a side of the nozzle plate with respect to the flow channel forming substrate is set as another side, each of the plurality of individual flow channels has an outlet flow channel coupled to the second common liquid chamber and extending in the in-plane direction and a coupling flow channel having a coupling port coupled to the outlet flow channel, the coupling flow channel extends from the one side to the other side toward the coupling port, the outlet flow channel has an outlet portion through which the liquid flows into the second common liquid chamber and which faces the in-plane direction, the second common liquid chamber has an introduction flow channel which is coupled to the outlet portion and through which the liquid flows along the in-plane direction, and the flow channel forming substrate has a partition wall which is disposed between two of the outlet flow channels adjacent to each other and which partitions the outlet flow channel. According to the liquid ejecting head of this aspect, a difference between a direction in which the liquid circulates in the second common liquid chamber and a direction of an outlet portion can be reduced. Further, as the wall that partitions the outlet flow channel is provided, the flow-channel cross-sectional area is reduced as compared to a case where the wall is not provided. Accordingly, the flow rate of the liquid in the outlet flow channel increases. Therefore, when the bubbles together with the liquid flow into the individual flow channel, movement of the bubbles flowing from the coupling port into the outlet flow channel becomes smooth. Therefore, occurrence of the bubbles caught at the coupling port can be suppressed. 
     (2) In the liquid ejecting head according to the above aspect, the second common liquid chamber may include an opening portion that is formed at the flow channel forming substrate and is open toward the other side, and a flexible member that is fixed to the flow channel forming substrate on the other side of the flow channel forming substrate and covers the opening portion. According to the liquid ejecting head of this aspect, since a member that forms the second common liquid chamber includes the flexible member, the compliance of the second common liquid chamber is high. Therefore, occurrence of crosstalk in which a pressure fluctuation occurring in one pressure chamber is propagated to the other pressure chamber via the second common liquid chamber is suppressed. 
     (3) In the liquid ejecting head according to the above aspect, the partition wall and the flexible member may be separated from each other. According to the liquid ejecting head of this aspect, when the flow channel forming substrate and the flexible member are bonded to each other using an adhesive, adhesion of the adhesive to the wall while the adhesive flows in the partition wall side can be suppressed. Therefore, adhesion between the partition wall and the flexible member can be suppressed. 
     (4) In the liquid ejecting head according to the above aspect, the partition wall may have a tapered shape or a rounded shape at a corner portion where a surface on the other side and a surface on a side of the outlet portion intersect each other. According to the liquid ejecting head of this aspect, even when the partition wall and the flexible member are in contact with each other, damage of the flexible member due to contact with the partition wall can be suppressed. 
     (5) In the liquid ejecting head according to the above aspect, the flow channel forming substrate may have a first through-hole that forms a flow channel of the individual flow channel between the first common liquid chamber and the pressure chamber, and a second through-hole that forms a flow channel of the individual flow channel between the second common liquid chamber and the pressure chamber, the nozzle may be provided between the first through-hole and the second through-hole in a flow channel direction of the individual flow channel, and a flow-channel cross-sectional area of the first through-hole may be smaller than a flow-channel cross-sectional area of the second through-hole. According to the liquid ejecting head of this aspect, the liquid can be efficiently ejected from the nozzle by the pressure fluctuation of the pressure chamber. 
     (6) In the liquid ejecting head according to the above aspect, in the individual flow channel, a flow channel resistance between the first common liquid chamber and the nozzle may be identical with a flow channel resistance between the second common liquid chamber and the nozzle. According to the liquid ejecting head of this aspect, the pressure difference between the first common liquid chamber and the second common liquid chamber can be reduced. Accordingly, adjustment of the meniscus position in the nozzle is facilitated. 
     (7) In the liquid ejecting head according to the aspect, the size of the partition wall in the vertical direction may be smaller than the size of an inlet wall in the vertical direction, the inlet wall being provided between a plurality of inlet portions coupling the plurality of individual flow channels and the first common liquid chamber. According to the liquid ejecting head of this aspect, catching of the bubbles at the inlet portion coupling the individual flow channel and the first common liquid chamber can be suppressed. 
     The present disclosure can be also be realized in various forms other than the liquid ejecting head. For example, the present disclosure can be realized in the form of a liquid ejecting apparatus including the liquid ejecting head according to the above aspect and a method of manufacturing the liquid ejecting apparatus.