Patent Abstract:
A liquid droplet ejecting head of an aspect of the invention includes: a nozzle ejecting a liquid-droplet; a liquid flow path member in which a liquid is supplied toward the nozzle; a back-pressure generating unit applying back-pressure to the liquid in a liquid-flow-path toward the nozzle; a beam member joined together with or including the liquid flow path member, deforming to become concave in a liquid-droplet ejection direction, thereafter undergoing buckling reverse deformation to become convex in the ejection direction, and applying inertia to the liquid near the nozzle in the ejection direction, to cause the liquid near the nozzle to be ejected; an opening disposed on an opposite side of the liquid flow path member in the ejection direction and communicated with the atmosphere; a suction path whose suction opening is directed toward near the nozzle; and a negative-pressure generating unit generating negative-pressure in the suction path.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2008-322133 filed Dec. 18, 2008. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid droplet ejecting head and a liquid droplet ejecting apparatus and particularly to a liquid droplet ejecting head and a liquid droplet ejecting apparatus that eject a high-viscosity liquid as a liquid droplet. 
     2. Related Art 
     Water-based inkjet printers that are known as liquid droplet ejecting apparatus and are currently commercially available use dye-based liquids and pigment-based inks with a viscosity generally around 5 cps or 10 (or slightly larger than 10) cps at most. For reasons such as preventing liquid-bleeding when the liquid lands on a medium, increasing optical color density, suppressing expansion of the medium resulting from water content reduction and drying the medium in a short amount of time, and/or increasing the degree of freedom when totally designing such a high-quality liquid, it is known that printing performance can be improved by increasing ink viscosity. 
     In the ejection of the high-viscosity liquid, it is easy for problems to occur, in comparison to a low-viscosity liquid, such as the stability of the ejected liquid falls and variations in the ejected liquid droplets per nozzle increase. Particularly in a case where, counter to excessive flow path resistance of the high-viscosity liquid, back pressure is applied in order to supply the liquid to the vicinity of the nozzle, it becomes even more difficult to maintain a uniform meniscus (problem of dripping from the nozzle may also arise), and the above-described problems are promoted. 
     SUMMARY 
     A liquid droplet ejecting head of an aspect of the present invention includes: a nozzle that ejects a liquid droplet; a liquid flow path member at which a liquid flow path that supplies a liquid toward the nozzle is formed; a back pressure generating unit that applies back pressure to the liquid in the liquid flow path toward the nozzle; a beam member joined together with the liquid flow path member or including the liquid flow path member, that deforms so as to become concave in a liquid droplet ejection direction, thereafter undergoes buckling reverse deformation so as to become convex in the liquid droplet ejection direction, and applies inertia to the liquid in the vicinity of the nozzle in the ejection direction, to cause the liquid in the vicinity of the nozzle to be ejected from the nozzle as a liquid droplet; an opening that is disposed on an opposite side of the liquid flow path member to a side in the ejection direction and is communicated with the external atmosphere; a suction path whose suction opening is directed toward the vicinity of the nozzle; and a negative pressure generating unit that generates negative pressure in the suction path. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the invention will be described in detail with reference to the following figures, wherein: 
         FIG. 1A  is a side view showing the structure of a liquid droplet ejecting head pertaining to the invention,  FIG. 1B  is a cross-sectional view showing the structure of the liquid droplet ejecting head pertaining to the invention, and  FIG. 1C  and  FIG. 1D  are perspective views showing the structure of the liquid droplet ejecting head pertaining to the invention; 
         FIG. 2  is a side view showing operations of the liquid droplet ejecting head pertaining to the invention; 
         FIG. 3  is a side view showing operations of the liquid droplet ejecting head pertaining to the invention; 
         FIG. 4  is a side view showing operations of the liquid droplet ejecting head pertaining to the invention; 
         FIG. 5A  is a perspective view showing the structure in the vicinity of a nozzle of the liquid droplet ejecting head pertaining to the invention, and  FIG. 5B  is a cross-sectional view showing the structure in the vicinity of the nozzle of the liquid droplet ejecting head pertaining to the invention; 
         FIG. 6A  and  FIG. 6B  are cross-sectional views showing the structure in the vicinity of the nozzle of a liquid droplet ejecting head pertaining to a second exemplary embodiment of the invention; 
         FIG. 7A  to  FIG. 7C  are perspective views showing a process of manufacturing the liquid droplet ejecting head pertaining to the invention; 
         FIG. 8A  is a cross-sectional view showing the structure in the vicinity of the nozzle of a liquid droplet ejecting head pertaining to a third exemplary embodiment of the invention, and  FIG. 8B  is a cross-sectional view showing the structure in the vicinity of the nozzle of a liquid droplet ejecting head pertaining to a fourth exemplary embodiment of the invention; 
         FIG. 9A  and  FIG. 9B  are perspective views showing the structure in the vicinity of the nozzle of a liquid droplet ejecting head pertaining to a fifth exemplary embodiment of the invention; 
         FIG. 10A  to  FIG. 10C  are cross-sectional views showing the relationship between the size of an opening and a meniscus in the liquid droplet ejecting head pertaining to the invention; 
         FIG. 11A  to  FIG. 11E  are cross-sectional views showing the relationship between the size of the opening and a meniscus in the liquid droplet ejecting head pertaining to the invention; and 
         FIG. 12  is charts showing the relationship between a positional relationship between the opening and the nozzle and ejection performance in the liquid droplet ejecting head pertaining to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     In  FIG. 1A  to  FIG. 1D , there is shown the basic structure of a liquid droplet ejecting head  10  pertaining to exemplary embodiments of the invention. 
     The liquid droplet ejecting head  10  shown in  FIG. 1A  and  FIG. 1B  has a structure where a hollow tubular flow path member  12  having a liquid flow (supply) path  13  and a suction path  42  (mentioned later) inside and a nozzle  16  in a substantial center in its length direction and a beam member  14  that supports the flow path member  12  are joined together in a columnar shape and where support members  18  support both ends. 
     Further, in the left side portion of the liquid droplet ejecting head  10  with respect to the nozzle  16  in  FIG. 1B  (at the side of another rotary encoder  20 B which will be mentioned later), a piezo element  30  is joined to the beam member  14 , and a signal electrode  32  is joined to the piezo element  30 , such that an actuator  36  is configured by the beam member  14 , the piezo element  30  and the signal electrode  32 . The beam member  14  also serves as a common electrode of the piezo element  30 , and the piezo element  30  is sandwiched between the beam member  14  and the signal electrode  32 . An electrode pad  33  is disposed on one end of the signal electrode  32  and is connected to an unillustrated switching IC by an unillustrated wire  34 . The piezo element  30  is driven by a signal from this switching IC such that control as to whether to cause the beam member  14  to make flexure (bend) or not to make flexure (bend) is performed. 
     The flow path member  12  is capable of flexure in a liquid droplet ejection direction (upward in  FIG. 1A  and  FIG. 1B ) and in the opposite direction and ejects, by inertia in the ejection direction as liquid droplets, a liquid L that has been supplied from a liquid pool  24  through the liquid flow path  13  to reach the nozzle  16 . 
     At this time, the liquid L, to which back pressure has been applied by a back pressure generating component  200 , is supplied to the liquid flow path  13  from the liquid pool  24  disposed in one rotary encoder  20 A, is fed from a longitudinal direction end to the vicinity of the nozzle  16 , and is ejected from the nozzle  16  as liquid droplets  2 . 
     Moreover, as shown in  FIG. 1B , on the opposite side of the ejection direction with respect to the nozzle  16 , an opening  116  is disposed in the beam member  14  and the actuator  36 , and opens to the atmosphere. Thus, the liquid L that has been fed from the liquid flow path  13  temporarily stays in a liquid pool  100  formed in the vicinity of the opening  116  disposed in the beam member  14 . 
     As shown in  FIG. 1B , a liquid suction pool  124  disposed in another rotary encoder  20 B is communicated with a suction component (a negative pressure generating component  300 ) such that negative pressure is applied to the liquid suction pool  124 . The suction path  42  is disposed in the flow path member  12  on the opposite side of the nozzle  16  with respect to the liquid flow path  13  in the longitudinal direction, and is communicated with the liquid suction pool  124 . For this reason, the suction path  42  sequentially sucks out and removes the liquid L that stays in the liquid pool  100  in the vicinity of the opening  116 . 
     In the right side portion of the liquid droplet ejecting head  10  with respect to the nozzle  16  in  FIG. 1B  (at the side of the one rotary encoder  20 A), as shown in  FIG. 1D , a flow path member  40  is disposed on one side of the beam member  14 , such as on the opposite side in the ejection direction, for example, and a blowing path  44  is formed inside the flow path member  40 . The blowing path  44  is communicated with a blowing component  400  such that air that has been pressurized is fed through the blowing path  44 . At this time, a filter may be disposed inside the blowing path  44  to filter the air, or a humidifying component may be disposed inside the blowing path  44  to humidify the air with solvent component of the liquid L. 
     The support members  18  are pressed from both sides in positions that are offset from rotation centers of the rotary encoders  20  (hereinafter, “rotary encoder  20 A and rotary encoder  20 B” will be merely recited as “rotary encoders  20 ”), or force is applied in a bend direction to the support members  18 , such that the flow path member  12  that is joined to the beam member  14  is made flexure in the ink liquid ejection direction or in the opposite direction. The support members  18  may have a rod-like structure that is long in the front-to-back direction of the page surface of  FIG. 1A , for example, or may have a ladder-like structure where plural flow path members  12  are disposed in the support members  18 . 
     Further, in the case of a liquid droplet ejecting head that jets the liquid droplets  2  collectively from the plural nozzles  16 , it is not necessary for the suction path  42  to be disposed for each nozzle  16 ; for example, one suction path  42  may be formed with respect to two nozzles  16  (liquid flow paths  13 ). It is not necessary for the liquid flow path  13  and the suction path  42  to have the same shape, and the suction path  42  may have a larger (fatter, wider, higher) cross section than that of the liquid flow path  13 . 
     &lt;Buckling Reverse Ejection&gt; 
     In  FIG. 2  and  FIG. 3 , there is shown the relationship between buckling reverse and the flexure direction of the beam member and the flow path member of the liquid droplet ejecting head pertaining to the exemplary embodiments of the invention. All of these drawings shown deformation focusing on one flow path member in a liquid droplet ejecting head with a structure where plural flow path members are disposed in a ladder-like manner in the support members. 
     In a case where the liquid droplet ejecting head  10  is controlled so as to not eject the liquid droplet  2 , first, as shown in (A) in  FIG. 2 , the rotary encoders  20  reversely rotate (rotate in the direction where they stretch the flow path member  12 ) such that the rotary encoders  20  straightly stretch the flow path member  12  which is in a state of having a convex shape in the ejection direction in an initial state. 
     Next, as shown in (B) in  FIG. 2 , when slackening stretching the flow path member  12 , the actuator  36  is not driven because a signal instructing ejection is not sent to the flow path member  12 , and the flow path member  12  remains in the state where it is made flexure so as to be convex in the ejection direction. 
     Further, when the rotary encoders  20  continue to be forwardly rotated in the ejection direction as shown in (C) and (D) in  FIG. 2 , the flexure amount increases in the state where the flow path member  12  is made flexure so as to be convex in the ejection direction, but this does not lead to ejection of the liquid droplet  2  from the nozzle  16  because deformation of the flow path member  12  in the ejection direction resulting from buckling reverse does not occur. 
     On the other hand, in a case where the liquid droplet ejecting head  10  is controlled so as to eject the liquid droplet  2 , first, as shown in (A) in  FIG. 3 , the rotary encoders  20  reversely rotate (rotate in the direction where they stretch the flow path member  12 ) such that the rotary encoders  20  straightly stretch the flow path member  12  which is in a state of having a convex shape in the ejection direction in an initial state, and place the flow path member  12  in a state where there is no flexure. 
     Next, as shown in (B) in  FIG. 3 , a signal instructing ejection is sent to the flow path member  12  from the unillustrated switching IC, the actuator  36  is driven, and the flow path member  12  is made in a flexure state so as to be concave in the ejection direction. 
     Moreover, when the rotary encoders  20  are forwardly rotated in the direction of the arrows shown in (C) in  FIG. 3 , the flexure direction of the flow path member  12  changes, from near the rotary encoders  20  (that is, from both end sides in the longitudinal direction), such that the flow path member  12  becomes convex in the ejection direction (upward in the drawing). 
     When this change approaches the center from both end sides, the flow path member  12  (or the beam member  14 ) undergoes a steep buckling reverse at a certain point and abruptly deforms convex in the liquid droplet ejection direction (upward in the drawing) as shown in  FIG. 3D . 
     Because the nozzle  16  is disposed in the substantial center of the flow path member  12  in the length direction of the flow path member  12 , the liquid L that is supplied through the inside of the flow path member  12  and reaches the nozzle  16  is ejected as the liquid droplet  2  from the nozzle  16  in accompaniment with the convex deformation of the flow path member  12  in the ejection direction resulting from this buckling reverse. 
     Moreover, after the flexure amount reaches a maximum in  FIG. 3D  and the rotary encoders  20  stop, the rotary encoders  20  reversely rotate to flatten the flow path member  12  ((A) in  FIG. 3 ) and thereby return the flow path member  12  to the initial position shown in (A) in  FIG. 3 . 
     In  FIG. 4 , there is shown another structure of the liquid droplet ejecting head pertaining to the exemplary embodiment of the invention. That is, one longitudinal direction end of a beam member  14  is fixed to a support member  18  that is held in a rotary encoder  20 B, and the other longitudinal direction end as a fixed end is held in a support member  18 B that is fixed. 
     Further, a liquid flow path  13  is disposed at the support member  18 B side in a flow path member  12  that is disposed on the beam member  14 , a liquid L is fed toward a nozzle  16  that is disposed in the vicinity of the longitudinal direction center, and the liquid L is ejected from the nozzle  16 . 
     As shown in (A) in  FIG. 4 , from an initial state where the half of the beam member  14  on the rotary encoder  20 B side is concave on the ejection side and where the half of the beam member  14  on the other end side is convex on the ejection side, the liquid L is fed through the inside of the liquid flow path  13  from the end of the beam member  14  (the flow path member  12 ) and is fed to the nozzle  16  as shown in (A) in  FIG. 4 . 
     Moreover, as shown in (B) in  FIG. 4 , when the rotary encoder  20  rotates in the ejection direction, the beam member  14  begins to deform so as to become convex in the ejection direction starting from the one end of the beam member  14  that is held by the support member  18 , and, as shown in (C) in  FIG. 4 , the portion of the beam member  14  in the vicinity of the nozzle  16  (near the center in the longitudinal direction) undergoes buckling reverse in the ejection direction, and the liquid L is ejected as the liquid droplet  2  from the nozzle  16 . 
     In  FIG. 5A  and  FIG. 5B , there are shown details of the structure in the vicinity of the nozzle of the liquid droplet ejecting head pertaining to a first exemplary embodiment of the invention. 
     The liquid L is fed, in a state where back pressure is applied, through the inside of the liquid flow path  13  formed by the flow path member  12 , so the liquid L is always supplied to the liquid pool  100  that is formed in the vicinity of the opening  16 . At this time, the liquid pool  10  temporarily holds the liquid L, which is supplied in a larger quantity than the liquid quantity that is lost by ejection, so as to not become supply-deficient, and the surplus portion of the liquid L is sucked out and discharged by the suction path  113  to which negative pressure is applied. Thus, the liquid L in the pool  100  forms a free surface, shear resistance of the liquid L that obstructs inertia ejection of the liquid droplets  2  is suppressed, and the liquid droplet ejecting head is given a configuration where, in comparison to a structure where the opposite side in the ejection direction (back side of the nozzle) is tightly closed, it is difficult to be obstructed for ejection even when the liquid L has a high viscosity. 
     As shown in  FIG. 5A  and  FIG. 5B , the flow path member  12  of the liquid droplet ejecting head  10  is equipped with the liquid flow path  13  that penetrates the inside of the flow path member  12  in its longitudinal direction and the nozzle  16  that is disposed in the flow path member  12 , and the opening  116  that is formed by perforating the beam member  14  is disposed on the back side (opposite side in the ejection direction) of the nozzle  16 . 
     The flow path member  40  is disposed on the opposite side of the beam member  14  in the ejection direction (the back side of the beam member  14 ), and the blowing path  44  is formed between the flow path member  40  and the beam member  14 . The blowing path  44  is communicated with the blowing component such that air that has been pressurized is fed through the blowing path  44  as indicated by arrow  43 . 
     A filter  48  is disposed as a filtering component inside the blowing path  44  and filters the air that is fed through the blowing path  44 . Moreover, a humidifying component  46  such as a sponge that is capable of holding a liquid is disposed inside the blowing path  44  and humidifies the air that is fed through the blowing path  44  with solvent component of the liquid L. Some of the air that has been fed as indicated by arrow  43  proceeds toward the suction path  113  as indicated by arrow  45  in the liquid pool  100  and is sucked out and removed together with the surplus liquid L as indicated by arrow  41 . 
     By configuring the liquid droplet ejecting head  10  in this manner, the liquid droplet ejecting head  10  has a configuration where, in comparison to a configuration where the liquid pool  100  merely opens to the atmosphere, there is little incorporation of dirt and foreign matter because air that has been filtered by the filter  48  is fed to the liquid pool  100  and it is difficult for the liquid L in the vicinity of the nozzle  16  to dry because air that has been humidified by solvent is fed. 
     Second Exemplary Embodiment 
     In  FIG. 6A  and  FIG. 6B , there are shown details of the structure in the vicinity of the nozzle of a liquid droplet ejecting head  11  pertaining to a second exemplary embodiment of the invention. 
     The place where an opening  116  is disposed and which had been open to the atmosphere in the first exemplary embodiment is sealed by a flexible thin film  102  of a polyimide or epoxy resin with a thickness of about 5 μm, for example, such that the liquid L in a liquid pool  100  that has been formed is prevented from contacting the outside air. 
     That is, the opening  116  is disposed in a beam member  14  on the opposite side of the nozzle  16  in the ejection direction to form the liquid pool  100 , and the opposite side of the liquid pool  100  in the ejection direction is sealed by the thin film  102 , so that when the liquid L is fed, in a state where back pressure is applied, through the inside of a liquid flow path  13  formed by a flow path member  12 , the thin film  102  expands as shown in  FIG. 6A  due to the back pressure that is applied to the liquid L. 
     The liquid L is always supplied to the liquid pool  100 , so the liquid pool  100  that the expanded thin film  102  seals temporarily holds the liquid L, which is supplied in a larger quantity than the liquid quantity that is lost by ejection, and the surplus portion of the liquid L is sucked out and removed by a suction path  113  to which negative pressure is applied. Thus, in the liquid pool  100 , a surface is formed by the flexible thin film  102 , and shear resistance of the liquid L that obstructs inertia ejection of a liquid droplet  2  is suppressed. 
     The liquid droplet ejecting head  11  has a structure where, at the time of ejection of the liquid droplet  2 , as shown in  FIG. 6B , the thin film  102  deforms in the direction of the nozzle  16  (ejection direction), so it is difficult for the liquid L inside the liquid flow path  13  to be restrained. Accordingly, at the time of ejection of the liquid droplet  2 , the liquid droplet ejecting head  11  has a configuration where, in comparison to a structure where the opposite side in the ejection direction (back side of the nozzle) is tightly closed by a rigid member, it is difficult to be obstructed for ejection even when the liquid L has a high viscosity. 
     &lt;Manufacturing Process&gt; 
     In  FIG. 7A  to  FIG. 7C , there is shown an example of a process of manufacturing the liquid droplet ejecting head pertaining to the exemplary embodiments of the invention. First, an SUS plate with a thickness of about 20 μm is etched (slit-etched) in rows with blank therebetween with a slit width of about 70 μm, and a PI (polyimide) film  14 B is heat-sealed to the ejection surface back side to form the beam member  14 . 
     As shown in  FIG. 7A , an SUS plate with a thickness of about 10 μm where a PI (polyimide) film  12 B has been heat-sealed to the ejection surface back side is slit-etched with a slit width of 70 μm as a flow path member  12 A. Next, the opening  116  is perforated by a YAG laser  50  or the like from the ejection surface back side to form a void (space) where the liquid pool  100  will be formed. 
     Next, as shown in  FIG. 7B , a PI film  12 C is heat-sealed to the ejection surface side of the flow path member  12 A. The nozzle  16  is perforated by the YAG laser  50  or the like, and the beam member  14  that has been disposed in parallel in the longitudinal direction of the support member  18  is divided. Further, at the same time, the liquid pool  24  that communicates with the slits (=the liquid flow paths  13 ) that have been disposed in the flow path member  12 A is disposed by removing the PI film  12 C. At this time, slit-etching is performed beforehand with respect to the beam member  14  and the flow path member  12 B, so just the PI film  12 C on the surface is removed by laser ablation. 
     Moreover, the piezo elements  30  on which the signal electrodes  32  have been formed beforehand are joined in a region up to half in the longitudinal direction at the ejection back surface. A supply port  25  through which the liquid is supplied from an unillustrated liquid feed pump is connected to the liquid pool  24  disposed inside the support member  18 , and the liquid droplet ejecting head  10  is formed. 
     Third Exemplary Embodiment 
     In  FIG. 8A , there is shown a cross-sectional view of the vicinity of a nozzle  16  of a liquid droplet ejecting head  110  pertaining to a third exemplary embodiment of the invention. In the liquid droplet ejecting head  110 , a flow path member  12  is disposed on a beam member  14  whose one end is held in a support member  18 , and a liquid flow path  13  is disposed in the longitudinal direction inside the flow path member  12 . 
     As shown in  FIG. 8A , the flow path member  12  of a liquid droplet ejecting head  110  is provided with the liquid flow path  13  that penetrates the inside of the flow path member  12  in its longitudinal direction and the nozzle  16  that is disposed in the flow path member  12 , and an opening  116  that is formed by perforating the beam member  14  is disposed on the back side (opposite side in the ejection direction) of the nozzle  16 . 
     A flow path member  40  is disposed on the opposite side of the beam member  14  in the ejection direction (the back side of the beam member  14 ), and a blowing path  44  is formed between the flow path member  40  and the beam member  14 . The blowing path  44  is communicated with the blowing component such that air that has been pressurized is fed through the blowing path  44  as indicated by arrow  43 . 
     A filter  48  is disposed as the filtering component inside the blowing path  44  and filters the air that is fed through the blowing path  44 . Moreover, a humidifying component  46  such as a sponge that is capable of holding a liquid is disposed inside the blowing path  44  and humidifies the air that is fed through the blowing path  44  with solvent component of the liquid L. 
     The liquid flow path  13  becomes a suction path  113  after passing the nozzle  16  and is communicated with the suction component such that negative pressure is applied thereto. Some of the air that has been fed as indicated by arrow  43  proceeds toward the suction path  113  as indicated by arrow  45 A in a liquid pool  100  and is sucked out and removed together with the surplus liquid L as indicated by arrow  41 . 
     On the other hand, some of the air does not proceed from the liquid pool  100  toward the suction path  113  but is returned back to the blowing component through an air circulation path as indicated by arrow  45 B. Moreover, the air is fed from the blowing component to the blowing path  44  and is again sent to the liquid pool  100  as indicated by arrow  43 . By configuring the liquid droplet ejecting head  110  in this manner, the liquid droplet ejecting head  110  has a configuration where, in comparison to a configuration where the liquid pool  100  merely opens to the atmosphere, there is little incorporation of dirt and foreign matter because air that has been filtered by the filter  48  is always fed. Further, drying of the liquid in the vicinity of the nozzle  16  can be suppressed. 
     Fourth Exemplary Embodiment 
     In  FIG. 8B , there is shown a cross-sectional view of the vicinity of the nozzle  16  of a liquid droplet ejecting head  111  pertaining to a fourth exemplary embodiment of the invention. In the liquid droplet ejecting head  111 , a flow path member  12  is disposed on a beam member  14  whose one end is held in a support member  18 , and a liquid flow path  13  is disposed in the longitudinal direction inside the flow path member  12 . 
     As shown in  FIG. 8B , the flow path member  12  of the liquid droplet ejecting head  111  is provided with the liquid flow path  13  that penetrates the inside of the flow path member  12  in the longitudinal direction and a nozzle  16  that is disposed in the flow path member  12 , and an opening  116  that is formed by perforating the beam member  14  is disposed on the back side (opposite side in the ejection direction) of the nozzle  16 . 
     A flow path member  40 A is disposed on the opposite side of the beam member  14  in the ejection direction (the back side of the beam member  14 ), and a blowing path  44 A is formed between the flow path member  40 A and the beam member  14 . The blowing path  44 A is communicated with the blowing component such that air that has been pressurized is fed through the blowing path  44 A as indicated by arrow  43 A. 
     A filter  48 A is disposed as the filtering component inside the blowing path  44 A and filters the air that is fed through the blowing path  44 A. Moreover, a humidifying component  46 A such as a sponge that is capable of holding a liquid is disposed inside the blowing path  44 A and humidifies the air that is fed through the blowing path  44 A with solvent component of the liquid L. 
     The liquid flow path  13  becomes the suction path  113  after passing the nozzle  16  and is communicated with the suction component such that negative pressure is applied thereto. Air that has been fed as indicated by arrow  43 A proceeds toward the suction path  113  as indicated by arrow  45  in a liquid pool  100  and is sucked out and removed together with the surplus liquid L as indicated by arrow  41 A. 
     Further, a flow path member  40 B is disposed on the ejection direction side of the beam member  14  (the front side of the beam member  14 ), and a blowing path  44 B is formed between the flow path member  40 B and the beam member  14 . The blowing path  44 B is also communicated with the blowing component such that air that has been pressurized is fed through the blowing path  44 B as indicated by arrow  43 B. 
     Moreover, a suction path  42 B is formed between the flow path member  40 B and the flow path member  12  on the downstream side of the nozzle  16  in the blowing direction, and the suction path  42 B sucks out air that has been fed thereto. This suction path  42 B is communicated with the negative pressure generating component (a suction pump or the like) such that negative pressure is applied thereto, so the suction path  42 B sucks out and removes air and the liquid L that has spilled over in the ejection direction in the vicinity of the nozzle  16 , as indicated by arrow  41 B. 
     An opening  416  that is larger than the nozzle  16  as seen from the ejection direction is disposed in the flow path member  40 B and does not obstruct the ejection of the liquid droplet  2  from the nozzle  16 . Moreover, a filter  48 B is also disposed as the filtering component inside the blowing path  44 B and filters the air that is fed through the blowing path  44 B. Moreover, a humidifying component  46 B such as a sponge that is capable of holding a liquid is also disposed inside the blowing path  44 B and humidifies the air that is fed through the blowing path  44 B with solvent component of the liquid L. 
     By configuring the liquid droplet ejecting head  111  in this manner, the liquid droplet ejecting head  111  has a configuration where, in comparison to a configuration where the liquid pool  100  merely opens to the atmosphere, there is little incorporation of dust and foreign matter because air that has been filtered by the filter  48 A is always fed, and, drying of the liquid in the vicinity of the nozzle  16  can be suppressed. Moreover, it is difficult for the liquid L to adhere in the vicinity of the nozzle  16 . 
     Fifth Exemplary Embodiment 
     In  FIG. 9A  and  FIG. 9B , there is shown a liquid droplet ejecting head  112  pertaining to a fifth exemplary embodiment of the invention. 
     The liquid droplet ejecting head  112  pertaining to the fifth exemplary embodiment of the invention has a structure where, as shown in  FIG. 9A , a hollow tubular flow path member  12  having a liquid flow path  13  inside and a nozzle  16  in a substantial center in its length direction and a beam member  14  that supports the flow path member  12  are joined together in a columnar shape and where support members  18  support both ends. Further, on the opposite side of the nozzle  16  in the ejection direction, an opening  116  is disposed and a liquid pool  100  is formed in the beam member  14 , which is the same as in each of the preceding exemplary embodiments. 
       FIG. 9B  shows a cross-section along line A-A of  FIG. 9A . As shown in  FIG. 9B , in the liquid droplet ejecting head  112 , the hollow flow path member  12  is disposed on the ejection surface side (front side) of the beam member  14 , and the liquid flow path  13  is formed inside the flow path member  12 . Further, a flow path member  40 C is disposed on the opposite side (back side) of the ejection surface, and a suction path  42 C is formed inside the flow path member  40 C. 
     The suction path  42 C is communicated with a suction component such that negative pressure is applied thereto. The suction path  42 C opens in the vicinity of the liquid pool  100  that is formed on the opposite side of the nozzle  16  in the ejection direction, and the suction path  42 C sucks out and removes the surplus liquid L. By configuring the liquid droplet ejecting head  112  in this manner, the liquid L can be supplied from both end sides of the liquid flow path  13  toward the nozzle  16 . Further, in this configuration, when the liquid L is supplied only from one end side of the liquid flow path  13  toward the nozzle  16 , the suction path  42 C can be disposed on the ejection surface side (front side) and on the opposite side of the ejection surface (back side), which is superior in terms of the dischargeability of the surplus liquid L in comparison to each of the preceding exemplary embodiments. 
     &lt;Opening Position&gt; 
     In  FIG. 10A  to  FIG. 10C  and  FIG. 11A  to  FIG. 11E , there are shown examples of the relationship between the liquid surface (meniscus) and the distance from the end of the opening to the center of the nozzle in the liquid droplet ejecting head pertaining to the exemplary embodiments of the invention. 
     In a case where the opening size of the nozzle  16  is 50 μm, when a size d 1  of the opening  116  is equal to or less than 100 μm, as shown in  FIG. 10A , the liquid film in the nozzle  16  is easily destroyed and it becomes difficult for the liquid film to form. When a size d 2  of the opening  116  is about 150 μm, as shown in  FIG. 10B , the liquid film in the nozzle  16  is thin and becomes unstable, such as occurrence of pulsation due to suction by the suction path  113 . When a size d 3  of the opening  116  is about 200 to 400 μm, as shown in  FIG. 10C , the problems that accompany suction described above do not arise. 
     In a case where the opening diameter of the nozzle  16  is 25 μm, when suction is not performed and the liquid L is capillary-supplied without back pressure being applied thereto, there are no problems in terms of ejectability only in a case where, as shown in  FIG. 11A , the size of the opening  116  is 50 μm, and when the size of the opening  116  is about 100 to 150 μm, it becomes difficult for the liquid film to be formed in the nozzle  16 , such as the liquid L moves to the opening  116  and flows out as shown in  FIG. 11B . Further, in a case where back pressure is applied to the liquid L and suction is performed by the suction path  113 , liquid spilling, moistening, and ejection variations in the nozzles  16  occur regardless of the size of the opening  116 . 
     In a case where back pressure is applied to the liquid L and suction is performed by the suction path  113 , when the size of the opening  116  is equal to or less than 100 μm, as shown in  FIG. 11C , it becomes easy for the liquid film in the nozzle  16  to be destroyed by suction from the suction path  113  and ejection variations occur. 
     When the size of the opening  116  is about 150 μm, as shown in  FIG. 11D , the liquid film in the nozzle  16  becomes thin and it becomes difficult to maintain the liquid film because the distance from the liquid flow path  13  becomes large, and ejection variations occur. The above-described examples are all results of cases where the centers of the nozzle  16  and the opening  116  coincide as seen from the ejection direction. In this cases where the centers of the nozzle  16  and the opening  116  coincide, it is difficult to obtain sizes of the opening  116  and the nozzle  16  such that proper nozzle ejection performance and the like is obtained. 
     Thus, the charts in  FIG. 12  show results where the distance (d in) from the back pressure side (supply side) end of the opening  116  to the center of the nozzle  16  and the distance (d out) from the suction side (downstream side) end of the opening  116  to the center of the nozzle  16  are varied and ejection performance is visually determined. 
     As shown in  FIG. 12 , ejection performance is excellent when the distance from the back pressure side (supply side) of the opening  116  to the center of the nozzle  16  is within 3 times the diameter of the nozzle  16 , and ejection performance is excellent when the distance from the suction side (downstream side) end of the opening  116  to the center of the nozzle  16  is in the range of 3 times to 10 times the diameter of the nozzle  16 . 
     &lt;Other&gt; 
     The present invention is not limited to the preceding exemplary embodiments. For example, in each of the preceding exemplary embodiments, there has been exemplified a configuration where the suction path  113  and the blowing path  44  are disposed for each of the nozzles  16 , but the present invention is not limited to this and may also be configured such that the suction path  113  and the blowing path  44  are disposed for each plurality (e.g., two or four) of the nozzles  16 . At this time, as long as the nozzles  16  are disposed evenly with respect to the suction path  113  and the blowing path  44 , it is easy for the liquid film to be made uniform. 
     Further, the liquid droplet ejecting head in the exemplary embodiments has been described by way of an inkjet recording head, but the liquid droplet ejecting head is not invariably limited to recording characters and images on recording paper using ink. That is, the recording medium is not limited to paper, and the liquid that is ejected is also not limited to ink. For example, it is possible to apply the present invention to all liquid droplet jetting apparatus that are used for industrial purposes, such as apparatus that eject a liquid onto polymer film or glass to create color filters for displays or apparatus that eject liquid-solder onto a substrate to form bumps for mounting parts.

Technology Classification (CPC): 1