Patent Publication Number: US-11034152-B2

Title: Liquid discharge head, head module, head device, liquid discharge device, and liquid discharge apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2019-049226, filed on Mar. 16, 2019, in the Japan Patent Office, the entire disclosures of which is hereby incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Aspects of the present disclosure relate to a liquid discharge head, a head module, a head device, a liquid discharge device, and a liquid discharge apparatus. 
     Related Art 
     A liquid discharge head includes a plurality of nozzles from which a liquid is discharged. The plurality of nozzles is arrayed in a two-dimensional matrix. The liquid is supplied to a pressure chamber from a supply-main channel through a supply-branch channel. The liquid is collected from the pressure chamber to a collection-main channel through a collection-branch channel. The liquid discharge head includes one or more bypass channels that connect the collection-branch channel and the supply-branch channel or the collection-branch channel and the supply-main channel. 
     SUMMARY 
     In an aspect of this disclosure, a liquid discharge head is provided that includes a plurality of nozzles configured to discharge a liquid, the plurality of nozzles arrayed in a two-dimensional matrix forming a plurality of nozzle groups, a plurality of pressure chambers communicating with the plurality of nozzles, respectively, a plurality of supply ports communicating with the plurality of pressure chambers, respectively, a plurality of common-supply branch channels communicating with two or more of the plurality of pressure chambers through the plurality of supply ports, respectively, a plurality of collection ports communicating with the plurality of pressure chambers, respectively, a plurality of common-collection branch channels communicating with two or more of the plurality of pressure chambers through the plurality of collection ports, respectively, a plurality of bypass supply ports, each of which is adjacent to one of the plurality of supply ports at each longitudinal end of one of the plurality of common-supply branch channels in one of the plurality of the nozzle groups, a plurality of bypass collection ports each of which is adjacent to one of the plurality of collection ports at each longitudinal end of one of the plurality of common-collection branch channels in the one of the plurality of nozzle groups, and a plurality of bypass channels connecting the plurality of bypass supply ports and the plurality of bypass collection ports, respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The aforementioned and other aspects, features, and advantages of the present disclosure will be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is an outer perspective view of a liquid discharge head according to a first embodiment of the present disclosure; 
         FIG. 2  is an exploded perspective view of the liquid discharge head in the first embodiment; 
         FIG. 3  is a schematic cross-sectional perspective view of the liquid discharge head in the first embodiment; 
         FIG. 4  is an exploded perspective view of the liquid discharge head without a frame in the first embodiment; 
         FIG. 5  is a cross-sectional perspective view of channels in the liquid discharge head in the first embodiment; 
         FIG. 6  is an enlarged cross-sectional perspective view of the channels in the first embodiment; 
         FIG. 7  is a plan view of the channels of the liquid discharge head in the first embodiment; 
         FIG. 8  is an enlarged plan view of a portion of the liquid discharge head in the first embodiment of  FIG. 7 ; 
         FIG. 9  is an enlarged plan view of a portion of the liquid discharge head in the first embodiment of  FIG. 7 ; 
         FIG. 10  is an enlarged plan view of a portion of the liquid discharge head in the first embodiment of  FIG. 7 ; 
         FIG. 11  is an enlarged plan view of a portion of the liquid discharge head in the first embodiment of  FIG. 7 ; 
         FIG. 12  is an enlarged plan view of a portion of one nozzle group to illustrate configuration of a bypass channel in the first embodiment; 
         FIG. 13  is a schematic perspective view of a channel plate in which the bypass channel is formed; 
         FIG. 14  is a plan view of channels of the liquid discharge head according to a second embodiment of the present disclosure; 
         FIG. 15  is an enlarged perspective view of a portion of the liquid discharge head in the second embodiment; 
         FIG. 16  is an enlarged plan view of a portion of the liquid discharge head in the second embodiment; 
         FIG. 17  is an exploded perspective view of a head module according to an embodiment of the present disclosure; 
         FIG. 18  is an exploded perspective view of the head module viewed from a nozzle surface side of the head module of  FIG. 17 ; 
         FIG. 19  is a schematic side view of a liquid discharge apparatus according to an embodiment of the present disclosure; 
         FIG. 20  is a plan view of an example of a head unit of the liquid discharge apparatus of  FIG. 19 ; 
         FIG. 21  is a circuit diagram illustrating an example of a liquid circulation device according to an embodiment of the present disclosure; 
         FIG. 22  is a plan view of a portion of a printer as a liquid discharge apparatus according to an embodiment of the present disclosure; 
         FIG. 23  is a schematic side view of a main portion of the liquid discharge apparatus of  FIG. 22 ; 
         FIG. 24  is a plan view of a portion of another example of a liquid discharge device; and 
         FIG. 25  is a front view of the liquid discharge device according to still another embodiment of the present disclosure. 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have the same function, operate in a similar manner, and achieve similar results. 
     Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
     Embodiments of the present disclosure are described below with reference to the attached drawings. A liquid discharge head according to a first embodiment of the present disclosure is described with reference to  FIGS. 1 to 8 . 
       FIG. 1  is an outer perspective view of a liquid discharge head according to the present embodiment. 
       FIG. 2  is an exploded perspective view of the liquid discharge head. 
       FIG. 3  is a cross-sectional perspective view of the liquid discharge head. 
       FIG. 4  is an exploded perspective view of the liquid discharge head excluding a frame. 
       FIG. 5  is a cross-sectional perspective view of channels of the liquid discharge head. 
       FIG. 6  is an enlarged cross-sectional perspective view of the channels of the liquid discharge head. 
       FIG. 7  is a plan view of the channels of the liquid discharge head. 
     Hereinafter, the “liquid discharge head  1 ” is simply referred to as the “head  1 .” The head  1  includes a nozzle plate  10 , an individual-channel member  20  (channel plate), a diaphragm member  30 , a common-channel member  50 , a damper member  60 , a frame  80 , and a flexible wiring  101  (substrate) mounting a drive circuit  102  . 
     The nozzle plate  10  includes a plurality of nozzles  11  to discharge a liquid. As illustrated in  FIG. 7 , the plurality of nozzles  11  are arranged two-dimensionally in a matrix and are arranged side by side in three directions of a first direction F, a second direction S, and a third direction T. 
     The individual-channel member  20  includes a plurality of pressure chambers  21  (individual chambers) respectively communicating with the plurality of nozzles  11 , a plurality of individual-supply channels  22  respectively communicating with the plurality of pressure chambers  21 , and a plurality of individual-collection channels  23  respectively communicating with the plurality of pressure chambers  21 . A combination of one pressure chamber  21 , one individual-supply channel  22  communicating with one pressure chamber  21 , and one individual-collection channel  23  communicating with one pressure chamber  21  is collectively referred to as an individual chamber  25 . 
     The diaphragm member  30  forms a diaphragm  31  serving as a deformable wall of the pressure chamber  21 , and the piezoelectric element  40  is formed on the diaphragm  31  to form a single body. Further, the diaphragm member  30  includes a supply opening  32  communicating with the individual-supply channel  22  and a collection opening  33  communicating with the individual-collection channel  23 . The piezoelectric element  40  is a pressure generator to deform the diaphragm  31  to pressurize the liquid in the pressure chamber  21 . 
     Note that the individual-channel member  20  and the diaphragm member  30  are not limited to be separate members. For example, an identical member such as a Silicon on Insulator (SOI) substrate may be used to form the individual-channel member  20  and the diaphragm member  30  in a single body. That is, an SOI substrate formed by sequentially forming a silicon oxide film, a silicon layer, and a silicon oxide film on a silicon substrate is used. The silicon substrate on which the SOI substrate is formed is used to form the individual-channel member  20 , and the silicon oxide film, the silicon layer, and the silicon oxide film are used to form diaphragm  31 . In the above-described configuration, the layer structure of the silicon oxide film, the silicon layer, and the silicon oxide film in the SOI substrate forms the diaphragm member  30 . As described above, the diaphragm member  30  includes a member made of the material that is film-formed on a surface of the individual-channel member  20 . 
     The common-channel member  50  includes a plurality of common-supply branch channels  52  that communicate with two or more individual-supply channels  22  and a plurality of common-collection branch channels  53  that communicate with two or more individual-collection channels  23  as illustrated in  FIG. 5 . The plurality of common-supply branch channels  52  and the plurality of common-collection branch channels  53  are arranged alternately adjacent to each other in the second direction S of the nozzles  11 . 
     As illustrated in  FIGS. 5 and 6 , the common-channel member  50  includes a through hole serving as a supply port  54  that connects the supply opening  32  of the individual-supply channel  22  and the common-supply branch channel  52 , and a through hole serving as a collection port  55  that connects the collection opening  33  of the individual-collection channel  23  and the common-collection branch channel  53 . 
     The common-channel member  50  includes one or more common-supply main channels  56  (see  FIGS. 3 and 4 ) that communicate with the plurality of common-supply branch channels  52 , and one or more common-collection main channels  57  (see  FIGS. 3 and 4 ) that communicate with the plurality of common-collection branch channels  53 . Further, the common-supply main channel  56  communicates with a supply port  81  in the frame  80 . Further, the common-collection main channel  57  communicates with a collection port  82  in the frame  80 . 
     As illustrated in  FIGS. 5 and 6 , the damper member  60  includes a supply-side damper  62  that faces (opposes) the supply port  54  of the common-supply branch channel  52  and a collection-side damper  63  that faces (opposes) the collection port  55  of the common-collection branch channel  53 . 
     The head  1  includes a plurality of collection-side dampers  63 . The plurality of collection-side dampers  63  forms part of walls of the plurality of common-collection branch channels  53 , respectively. 
     Thus, an identical damper member  60  forms the plurality of supply-side dampers  62  and the plurality of collection-side dampers  63 , and each of the plurality of common-supply branch channels  52  and the plurality of common-collection branch channels  53  is formed of the identical damper member  60  that seals grooves formed on an identical common-channel member  50 . 
     The plurality of collection-side dampers  63  faces the plurality of the collection ports  55 , respectively. 
     As illustrated in  FIGS. 5 and 6 , the supply-side damper  62  and the collection-side damper  63  of the damper member  60  seal grooves in the common-channel member  50  to form the common-supply branch channel  52  and the common-collection branch channel  53 . 
     The grooves are alternately arranged in the common-channel member  50  in a longitudinal direction of the common-supply main channel  56 . Both of the common-supply branch channel  52  and the common-collection branch channel  53  are formed in the same common-channel member  50 . As a material of the damper member  60 , it is preferable to use a metal thin film or an inorganic thin film resistant to an organic solvent. A thickness of the supply-side damper  62  and the collection-side damper  63  of the damper member  60  is preferably 10 μm or less. 
     Next, a configuration of a channel arrangement according to the present embodiment is described below with reference to  FIGS. 8 to 11 .  FIGS. 8 to 11  are enlarged schematic plan views of a main part of the channel arrangement of  FIG. 7 . In  FIGS. 8 to 11 , branch channels such as the common-supply branch channels  52  and the common-collection branch channels  53  are indicated by imaginary lines. 
     As illustrated in  FIG. 8 , the plurality of nozzles  11  are arranged two-dimensionally in a matrix and are arranged side by side in three directions of a first direction F, a second direction S and a third direction T. As illustrated in  FIG. 7 , a group of the nozzles  11  arranged two-dimensionally in a matrix is defined as a nozzle group NG (NG 1  and NG 2 ). The common-supply branch channel  52  and the common-collection branch channel  53  are arranged in common across the two nozzle groups NG 1  and NG 2  (see  FIG. 7 ). 
     In one nozzle group NG (NG  1  or NG  2 , for example), the first direction F is a nozzle array direction along which the nozzles  11  are arranged (arrayed). The second direction S is a direction in which nozzle arrays are aligned at a predetermined inclination angle θ 1  with the nozzle array direction the nozzles  11  (first direction F). Thus, the second direction S intersects the first direction F at an angle θ 1 . The common-supply branch channel  52  and the common-collection branch channel  53  extend in the first direction F (nozzle array direction). Therefore, a longitudinal direction of the common-supply branch channel  52  and the common-collection branch channel  53  is along the first direction F (nozzle array direction). 
     In one nozzle group NG (NG  1  or NG  2 , for example), the second direction S is a direction (nozzle array direction) in which most adjacent nozzles  11  are arranged (arrayed) and is a direction intersecting the first direction F at an angle θ 1  in the first direction F. The common-supply branch channel  52  and the common-collection branch channel  53  are alternately arranged in the second direction S. 
     In one nozzle group NG (NG  1  or NG  2 , for example), the third direction T is a direction intersecting the first direction F and the second direction S. In the present disclosure, the individual chambers  25  configured by the individual-supply channel  22 , the pressure chambers  21 , and the individual-collection channels  23  is arranged along the third direction T. 
     The individual chamber  25  (see  FIG. 7 ) configured by the individual-supply channel  22 , the pressure chamber  21 , and the individual-collection channel  25  has a shape of twice rotational symmetrical with an axis of the nozzle  11  (central axis in a direction of liquid discharge from the nozzle  11 ). 
     Thus, the head  1  in an example illustrated in  FIG. 8  can be arranged such that the individual chamber  25  is arranged reversal to a first nozzle  11 A and a nozzle  11 E adjacent in a direction (third direction T) parallel to a direction of liquid flow in the individual chamber  25  as in a relation between the individual chamber  25  communicating with the first nozzle  11 A and the individual chamber  25  communicating with the nozzle  11 E, for example. 
     The first supply port  54 A communicating with the individual chamber  25  of the first nozzle  11 A and the supply port  54 E communicating with the individual chamber  25  of the nozzle  11 E are arranged in the identical common-supply branch channel  52 . Further, a direction of arrangement of the individual chamber  25  communicating with the first supply port  54 A can be arranged opposite (reversal) to a direction of arrangement of the individual chamber  25  communicating with the supply port  54 E. 
     Thus, a package density of the individual chambers  25  (nozzles  11 ) can be increased without being restricted by an arrangement of the common-supply branch channel  52 , and the head  1  thus can be downsized. 
     Further, in the example illustrated in  FIG. 8 , the first nozzle  11 A connected to the first supply port  54 A and the nozzle  11 E connected to the supply port  54 E communicate with different common-collection branch channels  53  through collection ports  55 A and  55 E, respectively. Thus, two nozzles  11  communicating with two supply ports  54  arranged nearest to each other (closest to each other) and arranged in the identical common-supply branch channel  52  communicate with different common-collection branch channels  53  via two collection ports  55 , respectively. 
     The individual chambers  25  are translationally symmetrical (not reversely arranged) in the first direction F along which the liquid flows in the common-supply branch channel  52  and the common-collection branch channel  53 . 
     As illustrated in  FIG. 9 , an interval P 3  between the nozzles  11  adjacent in the third direction T can be set in an arbitrary direction. However, the interval P 3  can be set wider than an interval P 1  between the nozzles  11  adjacent in the first direction F and an interval P 2  between the nozzles  11  adjacent in the second direction T. 
     The third direction T is set such that the interval P 3  between the nozzles  11  adjacent in the third direction T has a distance equal to or more than twice the interval P 2  between the nozzles  11  adjacent in the second direction S. Further, an interval P 0  between the common-supply branch channel  52  and the common-collection branch channel  53  is set to be twice or more of the interval P 2  of the nozzles  11  adjacent in the second direction S. 
     The interval P 0  corresponds to a center distance between a width of channels in a direction along which the common-supply branch channel  52  and the common-collection branch channel  53  are alternately arranged (second direction S). 
     Further, a width W 1  of the common-supply branch channel  52  is made wider (twice or more) of the interval P 2  between the nozzles  11  adjacent in the second direction S. Similarly, a width W 2  of the common-collection branch channel  53  is also made wider (twice or more) than the interval P 2  between the nozzles  11  adjacent in the second direction S. 
     A relation between a distance “a” and a distance “b” is described below with reference to  FIG. 10 . The distance “a” is between the supply ports  54  of two most adjacent nozzles  11  among the nozzles  11  communicating with the identical common-supply branch channel  52 . The distance “b” is between the supply port  54  to a supply-side damper  62  (see  FIG. 6 ). 
     Here, a first nozzle  11 A and a second nozzle  11 B in  FIG. 10  are respectively selected as a combination of the most adjacent nozzles  11  among two adjacent nozzles  11 . In  FIG. 8 , the nozzles  11  arranged in the second direction S are combinations of the most adjacent nozzles  11  in the same nozzle array (the nozzles  11  arrayed in the second direction S). 
     The supply port  54  communicating with the first nozzle  11 A is referred to as a “first supply port  54 A”, and the supply port  54  communicating with the second nozzle  11 B is referred to as a “second supply port  54 B”. The first supply port  54 A communicating with the first nozzle  11 A and the second supply port  54 B communicating with the second nozzle  11 B are arranged in the identical common-supply branch channel  52 . 
     The distance “a” between the first supply port  54 A and the second supply port  54 B is greater than the distance “b” (see  FIG. 6 ) between the supply port  54  (the first supply port  54 A or the second supply port  54 B) and the supply-side damper  62 . Thus, the head  1  has a configuration that satisfies a relation of a&gt;b. 
     The plurality of supply ports  54  further includes a third supply port  54 B 1 , and the third supply port  54 B 1  is arranged in the identical one of the plurality of common-supply branch channels  52  with the first supply port  54 A and the second supply port  54 B. The third supply port  54 B 1  and one of the first supply port  54 A and the second supply port  54 B (first supply port  54 A in  FIG. 10 ) are spaced apart by a distance “a 1 ” shorter than the distance “a” between the first supply port  54 A and the second supply port  54 B. 
     Further, in the head  1  according to an embodiment of the present disclosure, the first nozzle  11 A is the most adjacent nozzle to a second nozzle  11 B 1  in the second direction S. The second nozzle  11 B 1  is arranged opposite to the second nozzle  11 B via the first nozzle  11 A in the second direction S. Therefore, a distance “a 1 ” between the first supply port  54 A communicating with the first nozzle  11 A and a third supply port  54 B 1  communicating with the second nozzle  11 B 1  is also greater than the distance “b” from the supply port  54  to the supply-side damper  62 . Thus, the head  1  has a configuration that satisfies a relation of a 1 &gt;b. 
     Thus, the head  1  includes a plurality of supply-side dampers  62 , and the plurality of supply-side dampers  62  forms a part of a wall of the plurality of common-supply branch channels  52 , respectively. 
     The plurality of nozzles  11  includes a first nozzle  11 A and a second nozzle  11 B disposed closest to the first nozzle  11 A (see  FIG. 10 ). 
     The plurality of supply ports  54  includes a first supply port  54 A communicating with the first nozzle  11 A and a second supply port  54 B communicating with the second nozzle  11 B. 
     The first supply port  54 A and the second supply port  54 B are in an identical one of the plurality of common-supply branch channels  52 , and the first supply port  54 A and the second supply port  54 B are spaced apart by a distance greater than a distance between one of the first supply port  54 A and the second supply port  54 B and one of the plurality of supply-side dampers  62  facing the one of the first supply port  54 A and the second supply port  54 B. 
     Similarly, in the head  1  according to an embodiment of the present disclosure, the second nozzle  11 B is the most adjacent nozzle to a first nozzle  11 A 1  in the second direction S. The first nozzle  11 A 1  is arranged opposite to the first nozzle  11 A via the second nozzle B in the second direction S. Thus, the distance “a 1 ” between the first supply port  54 A 1  communicating with the first nozzle  11 A 1  and the second supply port  54 B communicating with the second nozzle  11 B is also greater than the distance “b” from the supply port  54  to the supply-side damper  62 . Thus, the head  1  has a configuration that satisfies the relation of a 1 &gt;b. 
     In the above-described case, the first supply port  54 A and the second supply port  54 B are not the most adjacent supply port  54 . However, the first nozzle  11 A and the second nozzle  11 B are the most adjacent nozzles belonging to the same nozzle array (the nozzles  11  belong to the same nozzle array arrayed in the second direciton S). 
     The supply port  54 E communicating with the nozzle  11 E is the most adjacent to the first supply port  54 A communicating with the first nozzle  11 A as described above. The nozzle  11 E is arranged in a different nozzle array from the first nozzle  11 A and the second nozzle  11 B. 
     In the head  1  with such a configuration, when the liquid in the pressure chamber  21  is pressurized and liquid is discharged from the nozzle  11 , a pressure wave propagates from the individual-supply channel  22  to the common-supply branch channel  52  through the first supply port  54 A. 
     The distance “b” from the supply port  54  to the supply-side damper  62  is short. Thus, the pressure wave coming out from the first supply port  54 A spreads in a spherical shape, reaches to the supply-side damper  62 , and is absorbed by the supply-side damper  62  before the pressure wave propagates and reaches to the second supply port  54 B. Thus, the pressure wave reaching the second supply port  54 B decreases. 
     Thus, the head  1  can reduce an interference (mutual interference) of pressure to other nozzles  11  through the common-supply branch channel  52  and thus can reduce the crosstalk. 
     On the other hand, the supply port  54 E of the nozzle  11 E is the most adjacent supply port  54  to the first supply port  54 A. The pressure wave generated by the discharge operation of the liquid from the first nozzle  11 A propagates through the supply port  54 E and reaches to the pressure chamber  21  of the nozzle  11 E. However, the nozzle  11 E is arranged in a different array with the first nozzle  11 A and is not driven simultaneously with the first nozzle  11 A. Thus, the influence of crosstalk is reduced. 
     Arranging a structure of the channels as illustrated in  FIG. 7  ( FIGS. 8 to 11 ) can increase the density of nozzles  11  and reduce the crosstalk. 
     That is, in general, it is preferable to arrange the supply ports  54  such that a distance between all the supply ports  54  to be larger than the distance “b” between the supply port  54  and the supply-side damper  62  so that the crosstalk between adjacent nozzles  11  can be reduced. 
     However, increasing a distance between the supply ports  54  reduces the density of arrangement of the nozzles  11  and thus resulting in an increase in a size of the head  1 . 
     Thus, adopting the above-described arrangement of the channels (nozzles  11 ) can increase a package density of the individual chambers  25  and reduce the size of the head  1 . 
     The distance “b” from the supply port  54  to the supply-side damper  62  is preferably as short as possible. Thus, the distance “b” is set to be the optimum size in consideration of a cross-sectional area of the common-supply branch channel  52 . In the above-described case, the common-supply branch channel  52  needs to secure a flow rate of the liquid for a number of the nozzles  11  connected to the common-supply branch channel  52  to distribute the liquid to each supply ports  54  connected to the same common-supply branch channel  52 . 
     The distance b from the supply port  54  to the supply-side damper  62  corresponds to a channel height of the common-supply branch channel  52 . Shortening the distance b between the supply port  54  and the supply-side damper  62  reduces the channel height of the common-supply branch channel  52 . Further, shortening the distance “b” reduces a cross-sectional area of the common-supply branch channel  52  and increases a fluid resistance of the common-supply branch channel  52 . 
     When the fluid resistance of the common-supply branch channel  52  is large, a fluctuation of a pressure loss in the common-supply branch channel  52  increases with a fluctuation of a flow rate at each nozzle  11  by the liquid discharge. The pressure loss depends on a product of a fluid resistance and a flow rate. When the fluctuation of the pressure loss increases, the pressure at each nozzles  11  fluctuates according to the flow rate at each nozzle  11 . Thus, discharge characteristics of the liquid vary at each nozzle  11 . 
     Thus, the head  1  in the present embodiment has a channel arrangement in which the width W 1  of one common-supply branch channel  52  is made twice or more of the interval P 2  of the nozzles  11  in the second direction S. Thus, the head  1  increases the cross-sectional area and reduces the fluid resistance of the common-supply branch channel  52 . 
     Thus, the head  1  according to the present embodiment can reduce a fluid resistance and reduce the crosstalk at the same time. 
     Further, widening the width W 1  of the common-supply branch channel  52  increases the width of the supply-side damper  62  and also increases a compliance of the supply-side damper  62 . Therefore, it is preferable to sufficiently reduce the channel height of the common-supply branch channel  52  and increase the width of the common-supply branch channel  52  within an allowable range of the fluid resistance of the common-supply branch channel  52  so that the variation in discharge characteristics and crosstalk can be reduced. 
     Next, as illustrated in  FIGS. 8 and 11 , the head  1  according to the present embodiment has a configuration of a channel arrangement in which the individual-collection channel  23  is arranged opposite to the individual-supply channel  22  via the pressure chamber  21 . Further, the individual-collection channel  23  is connected to the common-collection branch channel  53  via the collection port  55 , and the plurality of common-collection branch channels  53  communicate with the common-collection main channel  57  as illustrated in  FIG. 4 . 
     Thus, the head  1  according to the present embodiment configures a head including a circulation-type individual chamber (pressure chamber). Thus, a liquid with high drying property or a liquid with high sedimentation property can be used to the head  1 . 
     As described above, the common-supply branch channel  52  and the common-collection branch channel  53  are alternately arranged. The head  1  includes a collection-side damper  63  that faces the collection port  55  on a wall of the common-collection branch channel  53  (see  FIG. 6 ). 
     The pressure wave generated in the pressure chamber  21  at the time of liquid discharge interferes not only with nozzles  11  at a supply side but also with other nozzles  11  via the common-collection branch channel  53 . Thus, similar to the common-supply branch channel  52 , variations in the discharge characteristics due to the crosstalk may occur via the common-collection branch channel  53 . 
     Thus, the collection-side damper  63  on the wall of the common-collection branch channel  53  can reduce crosstalk transmitted via the common-collection branch channel  53 . 
     Similar to the channels at the supply side, a third nozzle  11 C and a fourth nozzle  11 D are respectively selected as a combination of the most adjacent nozzles  11  of the collection side among the two adjacent nozzles  11 . In  FIG. 11 , the nozzles  11  arranged in the second direction S are combinations of the most adjacent nozzles  11  in the same nozzle array (the nozzles  11  arrayed in the second direction S). 
     The collection port  55  communicating with the third nozzle  11 C is referred to as a “first collection port  55 C,” and the collection port  55  communicating with the fourth nozzle  11 D is referred to as a “second collection port  55 D.” The first collection port  55 C communicating with the third nozzle  11 C and the second collection port  55 D communicating with the fourth nozzle  11 D are arranged in the identical common-collection branch channel  53 . 
     A distance “c” between the first collection port  55 C and the second collection port  55 D is greater than a distance “d” (=b, see  FIG. 6 ) between the collection port  55  (the first collection port  55 C and the second collection port  55 D) and the collection-side damper  63 . Thus, the head  1  has a configuration that satisfies a relation of c&gt;d. 
     Thus, the first collection port  55 C and the second collection port  55 D are spaced apart by a distance greater than a distance between one of the first collection port  55 C and the second collection port  55 D and one of the plurality of collection-side dampers  63  facing the one of the first collection port  55 C and the second collection port  55 D. 
     For example, the plurality of collection ports  55  further includes a third collection port  55 D 1 , and the third collection port  55 D 1  is arranged in the identical one of the plurality of common-collection branch channels  52  with the first collection port  55 C and the second collection port  55 D. The third collection port  55 D 1  and one of the first collection port  55 C and the second collection port  55 D (first collection port  55 C in  FIG. 11 ) are spaced apart by a distance “c 1 ” shorter than the distance “c” between the first collection port  55 C and the second collection port  55 D. The nozzle  11 C communicating with the collection port  55 C is arranged in a different array from the nozzle  11 D 1  communicating with the third collection port  55 D 1 . 
     Further, in the present embodiment, the third nozzle  11 C is the most adjacent nozzle to a fourth nozzle  11 D 1  in the second direction S. The fourth nozzle  11 D 1  is arranged opposite to the fourth nozzle  11 D via the third nozzle  11 C in the second direction S. Thus, the distance “c 1 ” between the first collection port  55 C communicating with the third nozzle  11 C and the third collection port  55 D 1  communicating with the fourth nozzle  11 D 1  is also greater than the distance d (see  FIG. 6 ) between the collection port  55  and the collection-side damper  63 . Thus, the head  1  has a configuration that satisfies a relation of c 1 &gt;d. 
     Further, in the present embodiment, the fourth nozzle  11 D is the most adjacent nozzle to a third nozzle  11 C 1  in the second direction S. The third nozzle  11 C 1  is arranged opposite to the third nozzle  11 C via the fourth nozzle  11 D in the second direction S. Thus, the distance “c 1 ” between the first collection port  55 C 1  communicating with the third nozzle  11 C 1  and a second collection port  55 D communicating with the fourth nozzle  11 D is also greater than the distance “d” (see  FIG. 6 ) between the collection port  55  and the collection-side damper  63 . Thus, the head  1  has a configuration that satisfies a relation of c 1 &gt;d. 
     The first collection port  55 C and the second collection port  55 D are not the most adjacent collection port  55 . However, the third nozzle  11 C and the fourth nozzle  11 D are the most adjacent nozzles belonging to the same nozzle array. 
     In the head  1  with such a configuration, when the liquid in the pressure chamber  21  is pressurized and discharged from the nozzle  11 , a pressure wave propagates from the individual-collection channel  23  to the common-collection branch channel  53  through the first collection port  55 C. The pressure wave coming out of the first collection port  55 C arrives at the collection-side damper  63  and is absorbed and attenuated before propagating to the second collection port  55 D. 
     Thus, the head  1  can reduce an interference (mutual interference) of pressure to other nozzles  11  through the common-collection branch channel  53  and thus can reduce the crosstalk. 
     Further, in the present embodiment, the common-supply branch channel  52  and the common-collection branch channel  53  are alternately arranged in the common channel member  50 . 
     Thus, the head  1  can form the supply-side damper  62  of the common-supply branch channel  52  and the collection-side damper  63  of the common-collection branch channel  53  with one damper member  60 . Thus, it is possible to reduce the size of the head  1 . 
     Further, as illustrated in  FIG. 9 , an interval P 0  between the common-supply branch channel  52  and the common-collection branch channel  53  is set to be twice or more of the interval P 2  between the nozzles  11  adjacent in the second direction S. Similar to a width W 1  of the common-supply branch channel  52 , a width W 2  of the common-collection branch channel  53  is also made wider (twice or more) of the interval P 2  between the nozzles  11  in the second direction S. 
     Thus, also in the common-collection branch channel  53 , the head  1  according to the present embodiment can increase a compliance of the collection-side damper  63  while reducing the fluid resistance and sufficiently shorten a distance between the collection-side damper  63  and the collection port  55 . 
     Therefore, the head  1  can reduce the crosstalk due to propagation of the pressure wave. Thus, the head  1  can adopt to various types of liquids in the circulation-type head and improve the reliability of the head  1 . 
     Thus, the head  1  having the arrangement of the channels as described in  FIGS. 7 to 11  can reduce the fluid resistance of each of the common-supply branch channel  52  and the common-collection branch channel  53 . Further, the head  1  can increase the compliance of the damper disposed in the common-supply branch channel  52  and the common-collection branch channel  53 . Thus, the head  1  can reduce a fluid resistance and reduce the crosstalk at the same time to stably discharge the liquid. 
     Next, a configuration of a bypass channel in the present embodiment is described with reference to  FIGS. 12 and 13 .  FIG. 12  is an enlarged plan view of a part of one nozzle group.  FIG. 13  is a schematic perspective view of a channel plate in which the bypass channel is formed. 
     The head  1  in  FIGS. 12 and 13  includes bypass supply ports  71  respectively adjacent to supply ports  54 F arranged at both longitudinal ends of the common-supply branch channels  52  in the first direction F among the plurality of supply ports  54  communicating with the nozzles  11  in one nozzle group NG. For example, the bypass supply port  71  is provided to each end of the common-supply branch channel  52  in the first direction F, that is, each of a left end and a right end of the common-supply branch channel  52  in the first direction F in  FIG. 12 . 
     Further, the head  1  includes bypass collection ports  72  respectively adjacent to collection ports  55 F arranged at both longitudinal ends of the common-collection branch channels  53  in a first direction F among the plurality of collection ports  55  communicating with the nozzles  11  in the one nozzle group NG. 
     Further, the head  1  includes a plurality of bypass channels  73  connecting the plurality of bypass supply ports  71  and the plurality of bypass collection ports  72 , respectively. Thus, each of a plurality of bypass channels  73  connects the bypass supply port  71  and the bypass collection port  72 . The bypass channel  73  is provided in an individual-channel member  20  (channel plate) in which pressure chambers  21  are formed as illustrated in  FIG. 13 . Thus, the bypass channel  73  communicates the common-supply branch channel  52  and the common-collection branch channel  53  at each longitudinal end of the common-supply branch channel  52  and the common-collection branch channel  53  (first direction F). 
     A distance (interval) R between the bypass supply port  71  and the supply port  54 F adjacent to the bypass supply port  71  is substantially the same as a distance (interval) Q between the adjacent supply ports  54 . Similarly, a distance (interval) between the bypass collection port  72  and the collection port  55 F adjacent to the bypass collection port  72  is substantially the same as a distance (interval) between the adjacent collection ports  55 . The distance (interval) Q between the adjacent supply ports  54  is a distance (interval) between the most adjacent supply ports  54 . 
     In the head  1  according to the present embodiment, the supply ports  54 F and  54 G and the collection ports  55 F and  55 G are isolated without an adjacent supply port  54  and an adjacent collection port  55  compared to the supply ports  54  and the collection ports  55  near a center of the common-supply branch channel  52  and the common-collection branch channel  53  in the first direction F. The supply ports  54 F and  54 G and the collection ports  55 F and  55 G are arranged at both ends of the common-supply branch channel  52  and the common-collection branch channel  53  in the first direction F. Here, the first direction F is parallel to a longitudinal direction of the common-supply branch channel  52  and the common-collection branch channel  53  (hereinafter, simply referred to as the “longitudinal direction”). 
     Thus, when the pressure generated in the pressure chamber  21  propagates to the common-supply branch channel  52  and the common-collection branch channel  53  during a liquid discharge operation, a pressure difference is generated between an end region and a center region of the common-supply branch channel  52  and the common-collection branch channel  53  in the longitudinal direction (first direction F), thus causing variations in discharge characteristics of the head  1 . 
     In particular, when the liquid flows through the common-supply branch channel  52  and the common-collection branch channel  53  in the head  1  of flow-through type, the pressure in the common-supply branch channel  52  and the common-collection branch channel  53  changes in the longitudinal direction (first direction F) due to the pressure loss of the branch channels. Thus, the pressure difference between the end region and the center region increases. 
     Thus, in one nozzle group NG, the bypass supply port  71  is arranged adjacent to the supply port  54 F at each longitudinal end (in the first direction F) of the common-supply branch channel  52  and the common-collection branch channel  53 . Further, in one nozzle group NG, the bypass collection port  72  is arranged adjacent to the collection port  55 F at each longitudinal end (in the first direction F) of the common-supply branch channel  52  and the common-collection branch channel  53 . Thus, the head  1  includes the bypass channel  73  that connects the bypass supply port  71  and the bypass collection port  72  to connect the common-supply branch channel  52  and the common-collection branch channel  53  at each longitudinal end in the first direction F. 
     Thus, the head  1  can reduce the pressure difference between the common-supply branch channel  52  and the common-collection branch channel  53  at each longitudinal end and reduce the variation in the discharge characteristics in one nozzle group NG. 
     In  FIG. 12 , the bypass channel  73  is disposed adjacent to the pressure chamber  21  at each longitudinal end of the common-supply branch channel  52  and the common-collection branch channel  53 . Thus, the head  1  including the bypass channel  73  can reduce the size of the head  1  as compared with the head  1  including a dummy pressure chamber and prevent an increase in a length of the branch channel such as the common-supply branch channel  52  and the common-collection branch channel  53 . 
     A fluid resistance of a flow-through path from the supply port  54  to the collection port  55  via the pressure chamber  21  is made substantially the same as a fluid resistance of a flow-through path from the bypass supply port  71  to the bypass collection port  72  via the bypass channel  73 . Specifically, the bypass channel  73  is shorter than a flow-through path including the pressure chamber  21 , the individual-supply channel  22 , and the individual-collection channel  23 . Further, the bypass channel  73  has a width narrower than a width of the pressure chamber  21 . Thus, the head  1  can further reduce the variation in the pressure difference. 
     The distance (interval) R between the bypass supply port  71  and the supply port  54  adjacent to the bypass supply port  71  is substantially the same as the distance (interval) Q between the adjacent supply ports  54 . Thus, the head  1  can further reduce the variation in the pressure difference. 
     Next, the head  1  according to a second embodiment of the present disclosure is described with reference to  FIGS. 14 to 16 .  FIG. 14  is a schematic plan view of the head  1  according to the second embodiment.  FIG. 15  is an enlarged perspective view of a portion of the head  1 .  FIG. 16  is an enlarged plan view of a portion of the head  1 . 
     The head  1  according to the second embodiment includes a bypass channel  73  at each longitudinal end (in the first direction F) of the common-supply branch channel  52  and the common-collection branch channel  53  in one nozzle group NG. The bypass channel  73  is a groove formed on a partition wall  59  between the common-supply branch channel  52  and the common-collection branch channel  53  adjacent to each other to connect the common-supply branch channel  52  and the common-collection branch channel  53 . 
     An opening of the groove that forms the bypass channel  73  at the common-supply branch channel  52  side becomes the bypass supply port  71  adjacent to the supply port  54 F arranged at each longitudinal end of the common-supply branch channel  52  in the first direction F. Another opening of the groove that forms the bypass channel  73  at the common-collection branch channel  53  side becomes the bypass collection port  72  adjacent to the collection port  55 F arranged at each longitudinal end of the common-collection branch channel  53  in the first direction F. 
     As described above, the head  1  includes the bypass channel  73  in a partition wall  59  between the common-supply branch channel  52  and the common-collection branch channel  53 . Thus, the head  1  has a simpler configuration, a smaller size, and a higher density. 
       FIGS. 17 and 18  illustrate an example of a head module according to an embodiment of the present disclosure.  FIG. 17  is an exploded perspective view of the head module  100 .  FIG. 18  is an exploded perspective view of the head module  100  viewed from a nozzle surface side of the head module  100 . 
     The head module  100  includes a plurality of heads  1  to discharge a liquid, a base  103  that holds the plurality of heads  1 , and a cover  113  serving as a nozzle cover of the plurality of heads  1 . 
     Thus, the head module  100  includes a plurality of heads  1  arrayed in one direction. 
     Further, the head module  100  includes a heat radiator  104 , a manifold  105  forming a channel to supply liquid to the plurality of heads  1 , a printed circuit board  106  (PCB) connected to a flexible wiring  101 , and a module case  107 . 
       FIGS. 19 and 20  illustrate an example of a liquid discharge apparatus according to an embodiment of the present disclosure.  FIG. 19  is a side view of a liquid discharge apparatus according to an embodiment of the present disclosure.  FIG. 20  is a plan view of a head unit of the liquid discharge apparatus of  FIG. 19  according to the present embodiment. 
     A printer  500  serving as the liquid discharge apparatus includes a feeder  501  to feed a continuous medium  510 , such as a rolled sheet, a guide conveyor  503  to guide and convey the continuous medium  510 , fed from the feeder  501 , to a printing unit  505 , the printing unit  505  to discharge a liquid onto the continuous medium  510  to form an image on the continuous medium  510 , a dryer  507  to dry the continuous medium  510 , and an ejector  509  to eject the continuous medium  510 . 
     The continuous medium  510  is fed from a winding roller  511  of the feeder  501 , guided and conveyed with rollers of the feeder  501 , the guide conveyor  503 , the dryer  507 , and the ejector  509 , and wound around a take-up roller  591  of the ejector  509 . 
     In the printing unit  505 , the continuous medium  510  is conveyed opposite the head unit  550  on a conveyance guide  559 . The head unit  550  discharges a liquid from the nozzles  11  of the head modules  100 A and  100 B to form an image on the continuous medium  510 . 
     Here, in the head unit  550 , two head modules  100 A and  100 B according to the present disclosure are provided in the common base member  552 . 
     The head module  100 A includes head arrays  1 A 1 ,  1 B 1 ,  1 A 2 , and  1 B 2 . Each of the head arrays  1 A 1 ,  1 B 1 ,  1 A 2 , and  1 B 2  includes a plurality of heads  1  arranged in a direction perpendicular to a conveyance direction of the continuous medium  510 . The direction perpendicular to the conveyance direction of the continuous medium  510  is also referred to as a “head array direction” indicated by arrow “HAD” in  FIG. 23 . The head module  100 B includes head arrays  1 C 1 ,  1 D 1 ,  1 C 2 , and  1 D 2 . 
     Each of the head arrays  1 C 1 ,  1 D 1 ,  1 C 2 , and  1 D 2  includes a plurality of heads  1  arranged in the head array direction HAD. The head  1  in each of the head arrays  1 A 1  and  1 A 2  of the head module  100 A discharges liquid of the same color. Similarly, the head arrays  1 B 1  and  1 B 2  of the head module  100 A are grouped as one set that discharge liquid of the same color. The head arrays  1 C 1  and  1 C 2  of the head module  100 B are grouped as one set that discharge liquid of the same color. The head arrays  1 D 1  and  1 D 2  are grouped as one set to discharge liquid of the same color. 
       FIG. 21  illustrates an example of a liquid circulation device  600  employed in the printer  500  according to the present embodiment.  FIG. 21  is a circuit diagram illustrating a structure of the liquid circulation device  600 . Although only one head  1  is illustrated in  FIG. 21 , in the structure including a plurality of heads  1  as illustrated in  FIG. 20 , supply channels and collection channels are respectively coupled via manifolds or the like to the supply sides and collection sides of the plurality of heads  1 . 
     The liquid circulation device  600  includes a supply tank  601 , a collection tank  602 , a main tank  603 , a first liquid-feed pump  604 , a second liquid-feed pump  605 , a compressor  611 , a regulator  612 , a vacuum pump  621 , a regulator  622 , and a supply-side pressure sensor  631 , and a collection-side pressure sensor  632 , for example. 
     The compressor  611  and the vacuum pump  621  together generate a difference of pressure between a pressure in the supply tank  601  and a pressure in the collection tank  602 . 
     The supply-side pressure sensor  631  is connected between the supply tank  601  and the head  1  and connected to the supply channels connected to the supply port  81  of the head  1 . The collection-side pressure sensor  632  is connected between the head  1  and the collection tank  602  and is connected to the collection channels connected to the collection port  82  of the head  1 . 
     One end of the collection tanks  602  is connected to the supply tank  601  via the first liquid-feed pump  604 , and another end of the collection tanks  602  is connected to the main tank  603  via the second liquid-feed pump  605 . 
     Accordingly, the liquid flows from the supply tank  601  into the head  1  via the supply port  81  and exits the head  1  from the collection port  82  into the collection tank  602 . Further, the first liquid-feed pump  604  feeds the liquid from the collection tank  602  to the supply tank  601 . Thus, the liquid circulation channel is constructed. 
     Here, a compressor  611  is connected to the supply tank  601  and is controlled so that a predetermined positive pressure is detected by the supply-side pressure sensor  631 . Conversely, a vacuum pump  621  is connected to the collection tank  602  and is controlled so that a predetermined negative pressure is detected by the collection-side pressure sensor  632 . 
     Such a configuration allows the menisci of ink in the nozzle  11  of the head  1  to be maintained at a constant negative pressure while circulating liquid through an interior of the head  1 . 
     When liquids are discharged from the nozzles  11  of the head  1 , the amount of liquid in each of the supply tank  601  and the collection tank  602  decreases. Therefore, the liquid is replenished from the main tank  603  to the collection tank  602  using the second liquid-feed pump  605  as appropriate. 
     The timing of supply of liquid from the main tank  603  to the collection tank  602  can be controlled in accordance with a result of detection by a liquid level sensor in the collection tank  602 . For example, the liquid is supplied to the collection tank  602  from the main tank  603  when the liquid level in the collection tank  602  becomes lower than a predetermined height. 
     Next, another example of a printer  500  serving as a liquid discharge apparatus according to the present embodiment is described with reference to  FIGS. 22 and 23 .  FIG. 22  is a plan view of a portion of the printer  500 .  FIG. 23  is a side view of a portion of the printer  500  of  FIG. 22 . 
     The printer  500  is a serial type apparatus, and the carriage  403  is reciprocally moved in a main scanning direction by the main scan moving unit  493 . The main scanning direction is indicated by arrow “MSD” in  FIG. 22 . The main scan moving unit  493  includes a guide  401 , a main scanning motor  405 , and a timing belt  408 . The guide  401  is bridged between a left-side plate  491 A and a right-side plate  491 B to movably hold the carriage  403 . The main scanning motor  405  reciprocally moves the carriage  403  in the main scanning direction MSD via the timing belt  408  bridged between a driving pulley  406  and a driven pulley  407 . 
     The carriage  403  mounts a liquid discharge device  440 . The head  1  according to the present embodiment and a head tank  441  forms the liquid discharge device  440  as a single unit. The head tank  441  store the liquid to be supplied to the head  1 . 
     The head  1  of the liquid discharge device  440  discharges liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K). The head  1  includes a nozzle array including a plurality of nozzles  11  arrayed in a sub-scanning direction indicated by arrow “SSD” perpendicular to the main scanning direction MSD. The head  1  is mounted to the carriage  403  so that liquids are discharged downward. 
     The head  1  is connected to the liquid circulation device  600  described above, and a liquid of a required color is circulated and supplied. 
     The printer  500  includes a conveyor  495  to convey a sheet  410 . The conveyor  495  includes a conveyance belt  412  as a conveyor and a sub-scanning motor  416  to drive the conveyance belt  412 . 
     The conveyance belt  412  attracts the sheet  410  and conveys the sheet  410  at a position facing the head  1 . The conveyance belt  412  is an endless belt and is stretched between a conveyance roller  413  and a tension roller  414 . Attraction of the sheet  410  to the conveyance belt  412  may be applied by electrostatic adsorption, air suction, or the like. 
     The conveyance belt  412  cyclically rotates in the sub-scanning direction SSD as the conveyance roller  413  is rotationally driven by the sub-scanning motor  416  via the timing belt  417  and the timing pulley  418 . 
     At one side in the main scanning direction MSD of the carriage  403 , a maintenance unit  420  to maintain the head  1  in good condition is disposed on a lateral side of the conveyance belt  412 . 
     The maintenance unit  420  includes, for example, a cap  421  to cap the nozzle surface of the head  1  and a wiper  422  to wipe the nozzle surface of the head  1 . 
     The main scan moving unit  493 , the maintenance unit  420 , and the conveyor  495  are mounted to a housing  491  that includes a left-side plate  491 A, a right-side plate  491 B, and a rear-side plate  491 C. 
     In the printer  500  thus configured, the sheet  410  is conveyed on and attracted to the conveyance belt  412  and is conveyed in the sub-scanning direction SSD by the cyclic rotation of the conveyance belt  412 . 
     The head  1  is driven in response to image signals while the carriage  403  moves in the main scanning direction MSD, to discharge liquid to the sheet  410  stopped, thus forming an image on the sheet  410 . 
     Next, the liquid discharge device  440  according to another embodiment of the present embodiment is described with reference to  FIG. 24 .  FIG. 24  is a plan view of a portion of another example of the liquid discharge device  440 . 
     The liquid discharge device  440  includes the housing  491 , the main scan moving unit  493 , the carriage  403 , and the head  1  among components of the printer  500  (liquid discharge apparatus) illustrated in  FIG. 22 . The housing  491  includes the left-side plate  491 A, the right-side plate  491 B, and the rear-side plate  491 C. 
     Note that, in the liquid discharge device  440 , the maintenance unit  420  described above may be mounted on, for example, the right-side plate  491 B. 
     Next, still another example of the liquid discharge device  440  according to the present embodiment is described with reference to  FIG. 25 .  FIG. 25  is a front view of still another example of the liquid discharge device  440 . 
     The liquid discharge device  440  includes the head  1 , to which a channel part  444  is attached, and a tube  456  connected to the channel component  444 . 
     Further, the channel part  444  is disposed inside a cover  442 . Instead of the channel part  444 , the liquid discharge device  440  may include the head tank  441 . A connector  443  electrically connected with the head  1  is provided on an upper part of the channel part  444 . 
     In the present embodiment, discharged liquid is not limited to a particular liquid as long as the liquid has a viscosity or surface tension to be discharged from a head (liquid discharge head). 
     However, preferably, the viscosity of the liquid is not greater than 30 mPa·s under ordinary temperature and ordinary pressure or by heating or cooling. 
     Examples of the liquid include a solution, a suspension, or an emulsion that contains, for example, a solvent, such as water or an organic solvent, a colorant, such as dye or pigment, a functional material, such as a polymerizable compound, a resin, or a surfactant, a biocompatible material, such as DNA, amino acid, protein, or calcium, or an edible material, such as a natural colorant. 
     Such a solution, a suspension, or an emulsion can be used for, e.g., inkjet ink, surface treatment solution, a liquid for forming components of electronic element or light-emitting element or a resist pattern of electronic circuit, or a material solution for three-dimensional fabrication. 
     Examples of an energy source to generate energy to discharge liquid include a piezoelectric actuator (a laminated piezoelectric element or a thin-film piezoelectric element), a thermal actuator that employs a thermoelectric conversion element, such as a heating resistor, and an electrostatic actuator including a diaphragm and opposed electrodes. 
     The “liquid discharge device” is an assembly of parts relating to liquid discharge. The term “liquid discharge device” represents a structure including the head and a functional part(s) or mechanism combined to the head to form a single unit. For example, the “liquid discharge device” includes a combination of the head with at least one of a head tank, a carriage, a supply unit, a maintenance unit, a main scan moving unit, and a liquid circulation apparatus. 
     Here, examples of the “single unit” include a combination in which the head and a functional part(s) or unit(s) are secured to each other through, e.g., fastening, bonding, or engaging, and a combination in which one of the head and a functional part(s) or unit(s) is movably held by another. The head may be detachably attached to the functional part(s) or unit(s) s each other. 
     For example, the head and the head tank may form the liquid discharge device as a single unit. Alternatively, the head and the head tank coupled (connected) with a tube or the like may form the liquid discharge device as a single unit. A unit including a filter may be added at a position between the head tank and the head of the liquid discharge device. 
     In another example, the head and the carriage may form the liquid discharge device as a single unit. 
     In still another example, the liquid discharge device includes the head movably held by a guide that forms part of a main scan moving unit, so that the head and the main scan moving unit form a single unit. The liquid discharge device may include the head, the carriage, and the main scan moving unit that form a single unit. 
     In still another example, a cap that forms part of a maintenance unit may be secured to the carriage mounting the head so that the head, the carriage, and the maintenance unit form a single unit to form the liquid discharge device. 
     Further, in another example, the liquid discharge device includes tubes connected to the head to which the head tank or the channel member is attached so that the head and a supply unit form a single unit. Liquid is supplied from a liquid reservoir source to the head via the tube. 
     The main scan moving unit may be a guide only. The supply unit may be a tube(s) only or a loading unit only. 
     In another example, the “liquid discharge device” may be a single unit in which the head and other functional parts are combined with each other. The “liquid discharge device” includes a head module including the above-described head, and a head device in which the above-described functional components and mechanisms are combined to form a single unit. 
     The term “liquid discharge apparatus” used herein also represents an apparatus including the head, the liquid discharge device, the head module, and the head device to discharge liquid by driving the head. The liquid discharge apparatus may be, for example, an apparatus capable of discharging liquid to a material to which liquid can adhere or an apparatus to discharge liquid toward gas or into liquid. 
     The “liquid discharge apparatus” may include devices to feed, convey, and eject the material on which liquid can adhere. The liquid discharge apparatus may further include a pretreatment apparatus to coat a treatment liquid onto the material, and a post-treatment apparatus to coat a treatment liquid onto the material, onto which the liquid has been discharged. 
     The “liquid discharge apparatus” may be, for example, an image forming apparatus to form an image on a sheet by discharging ink, or a three-dimensional fabrication apparatus to discharge a fabrication liquid to a powder layer in which powder material is formed in layers to form a three-dimensional fabrication object. 
     The liquid discharge apparatus is not limited to an apparatus to discharge liquid to visualize meaningful images, such as letters or figures. For example, the liquid discharge apparatus may be an apparatus to form arbitrary images, such as arbitrary patterns, or fabricate three-dimensional images. 
     The above-described term “material on which liquid can be adhered” represents a material on which liquid is at least temporarily adhered, a material on which liquid is adhered and fixed, or a material into which liquid is adhered to permeate. Examples of the “material on which liquid can be adhered” include recording media, such as paper sheet, recording paper, recording sheet of paper, film, and cloth, electronic component, such as electronic substrate and piezoelectric element, and media, such as powder layer, organ model, and testing cell. The “material on which liquid can be adhered” includes any material on which liquid is adhered, unless particularly limited. 
     Examples of the “material on which liquid can be adhered” include any materials on which liquid can be adhered even temporarily, such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramic. 
     The “liquid discharge apparatus” may be an apparatus to relatively move the head and a material on which liquid can be adhered. However, the liquid discharge apparatus is not limited to such an apparatus. For example, the liquid discharge apparatus may be a serial head apparatus that moves the head or a line head apparatus that does not move the head. 
     Examples of the “liquid discharge apparatus” further include a treatment liquid coating apparatus to discharge a treatment liquid to a sheet to coat the treatment liquid on the surface of the sheet to reform the sheet surface, and an injection granulation apparatus in which a composition liquid including raw materials dispersed in a solution is injected through nozzles to granulate fine particles of the raw materials. 
     The terms “image formation,” “recording,” “printing,” “image printing,” and “fabricating” used herein may be used synonymously with each other. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it is obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims.