Patent Publication Number: US-10308022-B2

Title: Liquid jet head and liquid jet apparatus

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. § 119 to Japanese Patent Applications No. 2016-106238 filed on May 27, 2016 and No. 2016-252721 filed on Dec. 27, 2016, the entire content of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     Technical Field 
     The present invention relates to a liquid jet head and a liquid jet apparatus. 
     Related Art 
     Conventionally, there has been an ink jet printer provided with an ink jet head as an apparatus that ejects ink in the form of liquid droplets onto a recording medium such as recording paper to record images or characters on the recording medium. For example, the ink jet head includes a plurality of head modules corresponding to respective colors which are mounted on a carriage. 
     The above head module includes a head chip which ejects ink, a manifold which includes an ink flow path for supplying ink to the head chip, and a drive board which drives the head chip (e.g., JP 2015-120265 A). The head chip, the manifold, and the drive board are mounted on a base member. 
     In JP 2015-120265 A, the base member is provided with a horizontal base which extends in a scanning direction of the ink jet head and a vertical base which stands from the horizontal base. 
     The head chip and the drive board are supported, for example, on the vertical base. Accordingly, heat generated in the head chip and the drive board is dissipated through the vertical base. On the other hand, the manifold is disposed on the base member at a side opposite to the vertical base across the head chip in the scanning direction of the ink jet head. 
     SUMMARY OF THE INVENTION 
     However, in the above conventional technique, the manifold and the drive board (vertical base) are separately disposed at the opposite sides in the scanning direction with respect to the head chip. Thus, there is still room for improvement in downsizing of the ink jet head in the scanning direction. 
     The present invention has been made in view of the above circumstances, and an object thereof is to provide a liquid jet head and a liquid jet apparatus that enable downsizing in the scanning direction. 
     In order to solve the above problem, a liquid jet head according to one aspect to the present invention includes: a jet hole plate including a jet hole array, the jet hole array including a plurality of jet holes each extending in a first direction, the jet holes being arranged side by side in a second direction perpendicular to the first direction; a head chip disposed at one side in the first direction with respect to the jet hole plate and including channels communicating with the respective jet holes; a manifold disposed at one side in a third direction perpendicular to the first direction and the second direction with respect to the head chip, the manifold being configured to support the head chip by a first face facing the third direction and including a liquid flow path communicating with the channels; and a drive board supported on the first face of the manifold and electrically connected to the head chip. 
     According to this configuration, the head chip and the drive board are supported on the manifold which includes the liquid flow path. Thus, it is possible to downsize the liquid jet head in the third direction as compared to a conventional configuration in which a member which supports the head chip and the drive board is disposed at one side in the third direction with respect to the head chip and a member which includes the liquid flow path is separately disposed at the other side in the third direction with respect to the head chip. 
     Further, since the head chip and the drive board are supported on the manifold, heat generated in the head chip and the drive board is dissipated to the outside through the manifold. This makes it possible to enhance the heat dissipation performance of the head chip and the drive board. 
     Further, since the head chip and the drive board are supported on the manifold which includes the liquid flow path, liquid flowing through the liquid flow path can be heated using exhaust heat which is generated in the head chip and the drive board and transmitted to the manifold. As a result, it is possible to supply liquid having a desired temperature (viscosity) to the head chip and thereby obtain an excellent printing characteristic. 
     In the above aspect, the liquid jet head may further include a damper configured to absorb pressure fluctuations of liquid supplied to the liquid flow path, the damper being disposed at a side opposite to the jet hole plate in the first direction with respect to the manifold and connected to the liquid flow path. 
     According to the above aspect, the damper is disposed at the side opposite to the jet hole plate in the first direction with respect to the manifold. Thus, it is possible to downsize the liquid jet head in the third direction as compared to a configuration in which the damper and the manifold are disposed side by side in the third direction. 
     In the above aspect, the head chip, the manifold, and the drive board may constitute a head module, and a plurality of the head modules may be mounted side by side in the third direction on a base member. 
     According to the above aspect, even when a plurality of head modules are mounted, it is possible to provide a small liquid jet head. 
     In the above aspect, the jet hole plate may include a plurality of the jet hole arrays corresponding to the head chips of the head modules, and may be disposed on a plate placement face of the base member, the plate placement face facing the other side in the first direction. 
     According to the above aspect, since the jet hole plate which includes the jet hole arrays corresponding to the respective head modules is disposed on the plate placement face of the base member, it is possible to improve the position accuracy of the jet holes as compared to a configuration in which the jet hole plate is attached to each of the head modules. 
     In the above aspect, the liquid jet head may further include a spacer interposed between the plate placement face of the base member and a face of the jet hole plate, the face facing the plate placement face of the base member in the first direction. 
     According to the above aspect, since the spacer is interposed between the jet hole plate and the base member, it is possible to relax a stress that acts on the jet hole plate and the base member due to a difference in thermal expansion coefficient between the jet hole plate and the base member. As a result, it is possible to reduce come-off of the jet hole plate from the head chip. 
     In the above aspect, the spacer may be adhered to the base member with a soft adhesive, and the jet hole plate may be adhered to the spacer with a hard adhesive formed of a material harder than the soft adhesive. 
     According to the above aspect, it is possible to reliably relax a stress that acts on the spacer and the base member due to a difference in thermal expansion coefficient between the spacer and the base member. As a result, it is possible to reduce come-off of the jet hole plate from the head chip. 
     In the above aspect, the base member may include an attachment opening that penetrates the base member in the first direction and inserts the head module therein, and the liquid jet head may further include a biasing member configured to bias the head module and the base member in at least either the second direction or the third direction, the biasing member being interposed between the head module and the base member. 
     According to the above aspect, since the biasing member biases the head module and the base member in at least either the second direction or the third direction, it is possible to position the head module with respect to the base member with high accuracy and thereby improve assemblability. 
     In the above aspect, the manifold may include a first flow path plate and a second flow path plate that are stacked in the third direction, and the liquid flow path may be defined between the first flow path plate and the second flow path plate. 
     According to the above aspect, since the first flow path plate and the second flow path plate are stacked to form the manifold, it is possible to easily form the liquid flow path on the manifold as compared to a configuration in which the manifold is integrally formed. 
     In the above aspect, the first flow path plate may be formed of a material having a higher thermal conductivity than the second flow path plate and thicker than the second flow path plate in the third direction, and a face facing the other side in the third direction of the second flow path plate may constitute the first face that supports the head chip and the drive board. 
     According to the above aspect, since the head chip and the drive board are supported on the second flow path plate, the first flow path plate can be formed of a material having a high thermal conductivity regardless of proof stress for supporting the head chip and the drive board. In this case, since the second flow path plate is thinner than the first flow path plate, heat generated in the head chip and the drive board is easily transmitted to the first flow path plate through the second flow path plate. As a result, the heat generated in the head chip and the drive board is effectively dissipated to the outside through the manifold, which enhances the heat dissipation performance of the head chip and the drive board. 
     A liquid jet apparatus according to one aspect of the present invention includes the liquid jet head according to the above aspect. 
     According to the above aspect, it is possible to provide the liquid jet apparatus having high reliability while achieving downsizing in the third direction. 
     According to one aspect of the present invention, it is possible to provide the liquid jet head and the liquid jet apparatus having high reliability while achieving downsizing in the third direction and enhancing the heat dissipation performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic configuration diagram of an ink jet printer according to an embodiment; 
         FIG. 2  is a perspective view of the ink jet head according to the embodiment; 
         FIG. 3  is a perspective view illustrating a state in which a part of the ink jet head according to the embodiment is detached; 
         FIG. 4  is a perspective view of a first head module according to the embodiment; 
         FIG. 5  is an exploded perspective view of a head chip according to the embodiment; 
         FIG. 6  is an exploded perspective view of a manifold according to the embodiment; 
         FIG. 7  is an exploded perspective view of a base member, a nozzle plate, and a nozzle guard according to the embodiment; and 
         FIG. 8  is a partial bottom view of the ink jet head according to the embodiment viewed from a −Z direction. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinbelow, an embodiment according to the present invention will be described with reference to the drawings. In the following description, an ink jet printer (hereinbelow, merely referred to as the printer) which performs recording on a recording medium using ink (liquid) will be described as an example. Note that, in the drawings used in the following description, the scale of each member is appropriately changed so as to allow each member to have a recognizable size. 
     [Printer] 
       FIG. 1  is a schematic configuration diagram of a printer  1 . 
     As illustrated in  FIG. 1 , the printer  1  of the present embodiment is provided with a pair of conveyance mechanisms  2 ,  3 , an ink supply mechanism  4 , ink jet heads  5 A,  5 B, and a scanning mechanism  6 . In the following description, an X, Y, Z orthogonal coordinate system is used as needed. In this case, an X direction (second direction) corresponds to a conveyance direction (sub-scanning direction) of a recording medium P (e.g., paper). A Y direction (third direction) corresponds to a scanning direction (main-scanning direction) of the scanning mechanism  6 . A Z direction (first direction) indicates a height direction which is perpendicular to the X direction and the Y direction. In the following description, in the X direction, the Y direction, and the Z direction, an arrow direction in the drawings is defined as a plus (+) direction, and a direction opposite to the arrow is defined as a minus (−) direction. 
     The conveyance mechanisms  2 ,  3  convey the recording medium P in the +X direction. Specifically, the conveyance mechanism  2  is provided with a grid roller  11  which extends in the Y direction, a pinch roller  12  which extends parallel to the grid roller  11 , and a drive mechanism (not illustrated) such as a motor which axially rotates the grid roller  11 . Similarly, the conveyance mechanism  3  is provided with a grid roller  13  which extends in the Y direction, a pinch roller  14  which extends parallel to the grid roller  13 , and a drive mechanism (not illustrated) which axially rotates the grid roller  13 . 
     The ink supply mechanism  4  is provided with an ink tank  15  which stores ink therein and an ink tube  16  which connects the ink tank  15  to the ink jet heads  5 A,  5 B. 
     In the present embodiment, a plurality of ink tanks  15  are arranged side by side in the X direction. The ink tanks  15  store therein respective four colors of ink, for example, yellow ink, magenta ink, cyan ink, and black ink. 
     The ink tube  16  is, for example, a flexible hose which has flexibility. The ink tube  16  connects each of the ink tanks  15  to a corresponding one of the ink jet heads  5 A,  5 B. 
     The scanning mechanism  6  moves the ink jet heads  5 A,  5 B back and forth in the Y direction. Specifically, the scanning mechanism  6  is provided with a pair of guide rails  21 ,  22  which extend in the Y direction, a carriage  23  which is movably supported on the pair of guide rails  21 ,  22 , and a drive mechanism  24  which moves the carriage  23  in the Y direction. 
     The drive mechanism  24  is disposed between the guide rails  21 ,  22  in the X direction. The drive mechanism  24  is provided with a pair of pulleys  25 ,  26  which are disposed at an interval in the Y direction, an endless belt  27  which is wound around the pair of pulleys  25 ,  26 , and a drive motor  28  which drives the pulley  25  to rotate. 
     The carriage  23  is coupled to the endless belt  27 . The ink jet heads  5 A,  5 B are mounted on the carriage  23  side by side in the Y direction. Each of the ink jet heads  5 A,  5 B is configured to eject two colors of ink. Thus, in the printer  1  of the present embodiment, the ink jet head  5 A ejects two colors of ink different from two colors of ink ejected by the ink jet head  5 B, so that four colors of ink: yellow ink, magenta ink, cyan ink, and black ink can be ejected. 
     &lt;Ink Jet Head&gt; 
       FIG. 2  is a perspective view of the ink jet head  5 A. The ink jet heads  5 A,  5 B have the same configuration except the colors of ink supplied thereto. Thus, hereinbelow, the ink jet head  5 A will be described, and description for the ink jet head  5 B will be omitted. 
     As illustrated in  FIG. 2 , the ink jet head  5 A of the present embodiment includes head modules  30 A to  30 D, a damper  31 , a nozzle plate (jet hole plate)  32 , and a nozzle guard (jet hole guard)  33  all of which are mounted on a base member  38 . In  FIG. 2 , a cover which covers the head modules  30 A to  30 D and the damper  31  is not illustrated. 
     (Base Member) 
       FIG. 3  is a perspective view illustrating a state in which a part of the ink jet head  5 A is detached. 
     As illustrated in  FIG. 3 , the base member  38  is formed in a plate-like shape whose thickness direction corresponds to the Z direction and whose longitudinal direction corresponds to the X direction. The base member  38  includes a module holding portion  41  which holds each of the head modules  30 A to  30 D and a carriage fixing portion  42  for fixing the base member  38  to the carriage  23  (refer to  FIG. 1 ). In the present embodiment, the base member  38  is integrally formed of a metal material. 
     The module holding portion  41  is formed in a frame shape in plan view viewed from the Z direction. That is, an attachment opening  44  which penetrates the base member  38  in the Z direction is formed on a central part of the module holding portion  41  in an XY plane. The module holding portion  41  includes a pair of short side parts  45  which are located at opposite sides in the X direction and include insertion grooves  46 . In the present embodiment, insertion grooves  46  that are formed on the respective short side parts  45  and opposed to each other in the X direction are defined as one set, and a plurality of sets (e.g., four sets) of insertion grooves  46  are formed at intervals in the Y direction. 
     Each of the insertion grooves  46  is recessed in the X direction with respect to the inner peripheral face of the short side part  45  and penetrates the short side part  45  in the Z direction. That is, the insertion grooves  46  communicate with the attachment opening  44 . Each of the head modules  30 A to  30 D is insertable into a corresponding set of insertion grooves  46  which are opposed to each other in the X direction. In each set of insertion grooves  46 , a first biasing member (not illustrated) is disposed on an inner face of one of the insertion grooves  46 . The first biasing member biases a corresponding one of the head modules  30 A to  30 D to one side in the X direction toward the other insertion groove  46 . In the present embodiment, the first biasing member is formed in a flat spring shape. 
     The carriage fixing portion  42  projects on the XY plane from a +Z direction end of the module holding portion  41 . The carriage fixing portion  42  includes an attachment hole for attaching the base member  38  to the carriage  23  (refer to  FIG. 1 ). 
     (Head Module) 
     As illustrated in  FIG. 2 , each of the head modules  30 A to  30 D is capable of ejecting ink supplied from the ink tank  15  (refer to  FIG. 1 ) toward the recording medium P. The head modules  30 A to  30 D are mounted on the base member  38  at intervals in the Y direction. In the present embodiment, four head modules including the first head module  30 A, the second head module  30 B, the third head module  30 C, and the fourth head module  30 D are mounted on the base member  38 . 
     In the ink jet head  5 A of the present embodiment, each two of the four head modules  30 A to  30 D eject one color of ink. Specifically, the first head module  30 A and the second head module  30 B are configured to eject the same color of ink, and the third head module  30 C and the fourth head module  30 D are configured to eject the same color of ink. Note that the number of head modules  30 A to  30 D mounted on the base member  38  and the types of ink ejected from the head modules  30 A to  30 D can be appropriately changed. The head modules  30 A to  30 D have corresponding configurations to each other. Thus, hereinbelow, the first head module  30 A will be described as an example. 
       FIG. 4  is a perspective view of the first head module  30 A. 
     As illustrated in  FIG. 4 , the first head module  30 A is mainly provided with a head chip  51 , a manifold  52 , and a drive board  53 . 
     (Head Chip) 
       FIG. 5  is an exploded perspective view of the head chip  51 . 
     As illustrated in  FIG. 5 , the head chip  51  is an edge shoot type head chip which ejects ink from an end in an extending direction (Z direction) of an ejection channel  57  (described below). Specifically, the head chip  51  includes an actuator plate  55  and a cover plate  56  which are stacked in the Y direction. 
     The actuator plate  55  is a monopole substrate whose polarization direction is set at one direction along the thickness direction (Y direction). For example, a ceramic substrate which is made of lead zirconate titanate (PZT) is suitably used as the actuator plate  55 . The actuator plate  55  may be formed by laminating two piezoelectric substrates whose polarization directions differ from each other in the Y direction (chevron type). 
     The actuator plate  55  includes a plurality of channels  57 ,  58  which are formed on a face facing the +Y direction (hereinbelow, referred to as the “front face”) and arranged side by side at intervals in the X direction. Each of the channels  57 ,  58  is linearly formed along the Z direction. Each of the channels  57 ,  58  is open on a −Z direction end face of the actuator plate  55  and ends on a +Z direction end face of the actuator plate  55 . Each of the channels  57 ,  58  may be inclined with respect to the Z direction. 
     The channels  57 ,  58  are classified into the ejection channels  57  which are filled with ink and the non-ejection channels  58  which are not filled with ink. The ejection channels  57  and the non-ejection channels  58  are alternately arranged side by side in the X direction. The channels  57 ,  58  are partitioned by drive walls  61  of the actuator plate  55  in the X direction. Drive electrodes (not illustrated) are formed on inner faces of the channels  57 ,  58 . 
     The cover plate  56  is formed in a rectangular shape in front view viewed from the Y direction. The cover plate  56  is joined to the front face of the actuator plate  55  with the +Z direction end of the actuator plate  55  projecting therefrom. 
     The cover plate  56  includes a common ink chamber  62  which is formed on a face facing the +Y direction (hereinbelow, referred to as the “front face”) and a plurality of slits  63  which are formed on a face facing the −Y direction (hereinbelow, referred to as the “back face”). 
     The common ink chamber  62  is formed at a position corresponding to a +Z direction end of each of the ejection channels  57  in the Z direction. The common ink chamber  62  is recessed from the front face of the cover plate  56  toward the −Y direction and extends in the X direction. Ink flows into the common ink chamber  62  through the manifold  52 . 
     The slits  63  are formed in the common ink chamber  62  at positions facing the respective ejection channels  57  in the Y direction. The slits  63  allow the common ink chamber  62  and the respective ejection channels  57  to communicate with each other. On the other hand, the non-ejection channels  58  do not communicate with the common ink chamber  62 . 
     As illustrated in  FIG. 4 , a heat transfer plate  65  is attached to a face facing the −Y direction (hereinbelow, referred to as the “back face”) of the actuator plate  55 . The heat transfer plate  65  is formed of a material having a high thermal conductivity (e.g., aluminum). The heat transfer plate  65  covers the entire channels  57 ,  58  on the back face of the actuator plate  55 . The size and the position of the heat transfer plate  65  can be appropriately changed. 
     (Manifold) 
     The manifold  52  includes an ink flow path  71  (refer to  FIG. 6 ) through which ink flows toward the head chip  51 . The manifold  52  is formed in a plate-like shape whose thickness direction corresponds to the Y direction as a whole. The manifold  52  is inserted into one set of insertion grooves  46  which are opposed to each other in the X direction so as to be held in a standing state in the +Z direction on the base member  38 . As illustrated in  FIG. 4 , second biasing members  70  are disposed on opposite ends in the X direction at a −Z direction end of the manifold  52 . Each of the second biasing members  70  is interposed between the inner face of the insertion groove  46  and the manifold  52  inside the insertion groove  46  to bias the first head module  30 A in the −Y direction. In the present embodiment, the second biasing member  70  is formed in a flat spring shape. 
       FIG. 6  is an exploded perspective view of the manifold  52 . 
     As illustrated in  FIG. 6 , the manifold  52  includes a flow path member  72  and a flow path cover  73  which is stacked on the flow path member  72  in the Y direction. 
     The flow path member  72  is integrally formed of a material having a high thermal conductivity. In the present embodiment, a metal material (e.g., aluminum) is suitably used as the material of the flow path member  72 . 
     The flow path member  72  is provided with a flow path plate  75  and an inflow port  76 . 
     The flow path plate  75  is formed in a rectangular plate-like shape whose thickness direction corresponds to the Y direction. The flow path plate  75  includes the ink flow path  71  which is formed on a face facing the −Y direction. The ink flow path  71  is formed in a groove shape recessed in the +Y direction. Specifically, the ink flow path  71  includes a meandering portion  79  and a communication portion  80 . 
     The meandering portion  79  extends in the Z direction while meandering in the X direction. A +Z direction end of the meandering portion  79  communicates with the inside of the inflow port  76 . On the other hand, a −Z direction end of the meandering portion  79  communicates with the communication portion  80  at a central part in the X direction of the flow path plate  75 . A meandering direction of the meandering portion  79  can be appropriately changed to any direction that makes the meandering portion  79  longer than a straight line connecting a communicating part between the meandering portion  79  and the inflow port  76  to a communicating part between the meandering portion  79  and the communication portion  80 . For example, the meandering portion  79  may extend in the X direction while meandering in the Z direction. 
     The communication portion  80  extends in the X direction at a −Z direction end of the flow path plate  75 . The communication portion  80  has the same shape as the common ink chamber  62  in front view viewed from the Y direction. 
     In the first head module  30 A, the inflow port  76  is disposed at a −X direction end on a +Z direction end face of the flow path plate  75 . The inflow port  76  is formed in a tubular shape projecting toward the +Z direction from the flow path plate  75 . A −Z direction end of the inflow port  76  communicates with the meandering portion  79 . 
     The flow path cover  73  is formed in a rectangular plate-like shape which has the same outer shape as the flow path plate  75  in front view viewed from the Y direction and has a Y-direction thickness thinner than the flow path plate  75 . The flow path cover  73  is fixed to the face facing the −Y direction of the flow path plate  75  and blocks the ink flow path  71  from the −Y direction. A communication hole  82  which opens the communication portion  80  is formed on the flow path cover  73  at a position overlapping the communication portion  80  in the Y direction. The communication hole  82  has the same shape as the communication portion  80  in front view viewed from the Y direction. 
     In the present embodiment, the flow path cover  73  is formed of a metal material (e.g., stainless steel) that has a high thermal conductivity and higher proof stress than the flow path member  72 . In the present embodiment, the groove-shaped ink flow path  71  is formed only on the flow path member  72 . However, the present invention is not limited only to this configuration. It is only required that an ink flow path be formed on at least either the flow path member  72  or the flow path cover  73  to form the ink flow path  71  between the flow path member  72  and the flow path cover  73 . In this case, for example, grooves may be formed on both the flow path member  72  and the flow path cover  73 , and the grooves of the flow path member  72  and the flow path cover  73  may be joined to form an ink flow path. 
     In the present embodiment, the flow path member  72  and the flow path cover  73  are stacked to form the manifold  52 . However, the present invention is not limited to this configuration. The manifold  52  may be integrally formed. 
     The flow path cover  73  includes an insulating sheet  86  which is disposed on a face facing the −Y direction. The insulating sheet  86  is formed in a frame shape in front view viewed from the Y direction. The insulating sheet  86  surrounds the periphery of the communication hole  82  on the face facing the −Y direction of the flow path cover  73 . The insulating sheet  86  is fixed to the face facing the −Y direction of the flow path cover  73  with, for example, an adhesive. In the present embodiment, for example, polyimide is suitably used as the insulating sheet  86 . The material of the insulating sheet  86  can be appropriately changed to any material (e.g., a resin material or a rubber material) that has a characteristic capable of sufficiently reducing stray capacitance (e.g., a material having a low dielectric constant or a material capable of reducing a dielectric constant with a tiny space distance) or an ink resistance (elution resistance) and that is relatively soft (has a small Young&#39;s modulus). 
     As illustrated in  FIGS. 4 and 6 , the head chip  51  is fixed on the face facing the −Y direction (a first face facing a third direction) of the flow path cover  73  with the insulating sheet  86  interposed therebetween. Specifically, the head chip  51  is fixed to the insulating sheet  86  with, for example, an adhesive with the front face (the face facing the manifold  52 ) of the cover plate  56  facing the insulating sheet  86 . In this case, the common ink chamber  62  of the cover plate  56  communicates with the communication portion  80  through the communication hole  82 . Accordingly, ink flowing through the ink flow path  71  is supplied to the head chip  51 . The head chip  51  projects in the −Z direction with respect to the manifold  52  when fixed to the manifold  52 . In the example illustrated in  FIG. 4 , the length in the X direction of the head chip  51  is shorter than the length in the X direction of the manifold  52 . 
     As illustrated in  FIG. 2 , a heater  85  is disposed on a face facing the +Y direction (a second face facing the third direction) of the flow path member  72  (the flow path plate  75 ). The heater  85  heats the inside of the ink flow path  71  through the flow path member  72  to keep ink flowing through the ink flow path  71  within a predetermined temperature range (keep the ink warm). 
     As illustrated in  FIG. 4 , the drive board  53  is a flexible printed circuit board and includes a wiring pattern and various electronic components which are mounted on a base film. The drive board  53  includes a module control portion  88  which is supported on the manifold  52  and a chip connecting portion  89  which connects the module control portion  88  to the head chip  51 . In the drive board  53 , for example, a rigid board may be used as the module control portion  88  as long as at least the chip connecting portion  89  is composed of a flexible board. 
     The module control portion  88  is formed in a rectangular shape in front view viewed from the Y direction. An electronic component such as a driver IC is mounted on the module control portion  88 . The module control portion  88  is fixed to the manifold  52  with a support plate  90  interposed therebetween in a part located in the +Z direction with respect to the head chip  51  on the face facing the −Y direction of the flow path cover  73 . The support plate  90  is formed of a material (e.g., a metal material) having a high thermal conductivity. The support plate  90  may not be provided. That is, the module control portion  88  may be directly fixed to the manifold  52 . 
     As illustrated in  FIG. 2 , the drive board  53  is electrically connected to an external connection board  92  through a lead-out portion  91  which is led out from the module control portion  88  in the +Z direction. The external connection board  92  relays a control signal and drive voltage output from a main control board (not illustrated) which is mounted on the printer  1  to each of the head modules  30 A to  30 D (driver IC). The drive board  53  drives the head chip  51  on the basis of the control signal and the drive voltage relayed by the external connection board  92 . 
     As illustrated in  FIG. 4 , the chip connecting portion  89  extends in the −Z direction from the module control portion  88  with a clearance left in the Y direction with respect to the flow path cover  73 . A −Z direction end of the chip connecting portion  89  is fixed to the +Z direction end of the actuator plate  55  by, for example, pressure bonding. Accordingly, the drive board  53  and the drive electrodes of the head chip  51  are electrically connected. 
     The drive board  53  is provided with a sensor connecting portion  93  which is led out from a +X direction end of the module control portion  88 . The sensor connecting portion  93  extends up to a position that overlaps the heat transfer plate  65  when viewed from the Y direction. A temperature sensor  94  (e.g., a thermistor) which detects an ink temperature inside the ejection channels  57  is mounted on the tip of the sensor connecting portion  93 . The temperature sensor  94  is disposed on the back face of the actuator plate  55  with the heat transfer plate  65  interposed therebetween. 
     As illustrated in  FIG. 3 , the first head module  30 A is inserted in the attachment opening  44  with the manifold  52  inserted in the corresponding set of insertion grooves  46  as described above. In this case, the first head module  30 A is held on the base member  38  in such a manner that the head chip  51  faces the −Y direction and a −Z direction end face of the head chip  51  is flush with a −Z direction end face of the base member  38  (the module holding portion  41 ). 
     As illustrated in  FIGS. 2 and 3 , the second head module  30 B is inserted in a set of insertion grooves  46  that is adjacent, in the −Y direction, to the set of insertion grooves  46  in which the manifold  52  of the first head module  30 A is inserted and, in this state, inserted in the attachment opening  44 . In this case, the second head module  30 B is held on the base member  38  with the head chip  51  thereof facing the head chip  51  of the first head module  30 A in the Y direction. The inflow port  76  of the first head module  30 A and the inflow port  76  of the second head module  30 B are arranged at the same position in the X direction. 
     An array pitch of the ejection channels  57  on the head chip  51  of the second head module  30 B is shifted by a half pitch from an array pitch of the ejection channels  57  on the head chip  51  of the first head module  30 A (a staggered form). Accordingly, the head chip  51  of the first head module  30 A and the head chip  51  of the second head module  30 B eject one color of ink in corporation with each other to enable high-density recording of characters or images recorded on the recording medium P. In the first head module  30 A and the second head module  30 B, the array pitch of the ejection channels  57  of the head chip  51  can be appropriately changed. 
     As illustrated in  FIG. 2 , the third head module  30 C and the fourth head module  30 D are held on the base member  38  with their head chips  51  facing each other in the same manner as the first head module  30 A and the second head module  30 B. Each of the head modules  30 A to  30 D is fixed to the base member  38  through a stay (not illustrated) which is provided in a standing manner in the +Z direction from the base member  38 . The inflow ports  76  of the third head module  30 C and the fourth head module  30 D are located at a side opposite to the inflow ports  76  of the first head module  30 A and the second head module  30 B in the X direction (at a +X direction end of the flow path plate  75 ). 
     (Damper) 
     The damper  31  is provided corresponding to each color of ink in the +Z direction with respect to the head modules  30 A to  30 D. That is, in the present embodiment, one damper  31  is provided for two head modules (e.g., the head modules  30 A,  30 B). The dampers  31  are arranged side by side in the Y direction. The dampers  31  have the same configuration except the colors of ink supplied thereto. Thus, hereinbelow, one of the dampers  31  (the damper for the head modules  30 A,  30 B) will be described, and description for the other damper  31  will be omitted. 
     The damper  31  is attached in the +Z direction with respect to the head modules  30 A,  30 B through a stay (not illustrated) which is fixed to the base member  38 . The damper  31  includes an inlet port  100 , a pressure buffer  101 , and an outlet port  102 . The damper  31  may be separately provided from the ink jet head  5 A. 
     The inlet port  100  is formed in a tubular shape projecting in the +Z direction from the pressure buffer  101 . The ink tube  16  (refer to  FIG. 1 ) described above is connected to the inlet port  100 . Ink inside the ink tank  15  flows into the inlet port  100  through the ink tube  16 . 
     The pressure buffer  101  is formed in a box shape. The pressure buffer  101  stores a movable film inside thereof. The pressure buffer  101  is disposed between the ink tank  15  ( FIG. 1 ) and the head modules  30 A,  30 B to absorb pressure fluctuations of ink supplied to the damper  31  through the inlet port  100 . 
     The outlet port  102  is formed in a tubular shape projecting in the −X direction from the pressure buffer  101 . Ink discharged from the pressure buffer  101  flows into the outlet port  102 . 
     A filter unit  110  is connected to the outlet port  102 . The filter unit  110  stores a filter (not illustrated) therein. The filter unit  110  removes air bubbles and foreign substances contained in ink discharged from the damper  31  by the filter. The filter unit  110  includes branch portions  111 ,  112  which divide ink discharged from the damper  31  into two branches. The branch portion  111  is connected to the inflow port  76  of the first head module  30 A through a connection tube  113 . The branch portion  112  is connected to the inflow port  76  of the second head module  30 B through a connection tube  114 . The filter unit  110  is fixed to the base member  38  through a stay (not illustrated). The external connection board  92  described above is disposed between the dampers  31  which are opposed to each other in the Y direction. 
       FIG. 7  is an exploded perspective view of the base member  38 , the nozzle plate  32 , and the nozzle guard  33 . 
     As illustrated in  FIG. 7 , a spacer  120  is fixed to the −Z direction end face (plate placement face) of the module holding portion  41  in the above base member  38 . The spacer  120  is formed of polyimide or SUS. The spacer  120  is adhered to the −Z direction end face of the module holding portion  41  using a soft adhesive. A silicone adhesive (e.g., 1211 manufactured by ThreeBond Holdings Co., Ltd) is suitably used as the soft adhesive. 
     The spacer  120  covers the −Z direction end face of the module holding portion  41  from the −Z direction. The spacer  120  includes a spacer opening  121 . The spacer opening  121  is formed at a position that overlaps the head chip  51  of each of the head modules  30 A to  30 D when viewed from the Z direction and exposes the head chip  51  in the −Z direction. In the present embodiment, the spacer opening  121  collectively exposes the head chips  51  for each color (e.g., the head chips  51  of the first head modules  30 A and the second head module  30 B). The spacer opening  121  may collectively expose the head chips  51  of the respective head modules  30 A to  30 D, or may individually expose each of the head chips  51 . 
     (Nozzle Plate) 
     The nozzle plate  32  is formed of a resin material such as polyimide. A +Z direction end face (the face facing the base member  38 ) of the nozzle plate  32  is fixed to the spacer  120  and the −Z direction end faces of the head chips  51  with a hard adhesive. The hard adhesive is formed of, for example, a material that is harder in Shore hardness than the soft adhesive described above. An epoxy adhesive (e.g., 931-1T1N1 manufactured by Henkel Ablestik Japan Ltd.) is preferably used as such a material. The nozzle plate  32  may be directly adhered to the base member  38  using a soft adhesive. 
     As illustrated in  FIGS. 2 and 7 , the nozzle plate  32  collectively covers the head chips  51  of the respective head modules  30 A to  30 D from the −Z direction. The nozzle plate  32  includes a plurality of nozzle arrays (first to fourth nozzle arrays  130 A to  130 D) each of which extends in the X direction. The nozzle arrays are formed at intervals in the Y direction. 
     Each of the nozzle arrays (jet hole arrays)  130 A to  130 D is formed on the nozzle plate  32  at a position facing the head chip  51  of a corresponding one of the head modules  30 A to  30 D in the Z direction. 
       FIG. 8  is a partial bottom view of the ink jet head  5 A viewed from the −Z direction. 
     As illustrated in  FIG. 8 , the nozzle arrays  130 A to  130 D include nozzle holes (first to fourth nozzle holes  131 A to  131 D) each of which penetrates the nozzle plate  32  in the Z direction. For example, the first nozzle holes (jet holes)  131 A are formed on the nozzle plate  32  at positions facing the respective ejection channels  57  of the head chip  51  in the first head module  30 A in the Z direction. That is, the plurality of first nozzle holes  131 A are linearly formed at intervals in the X direction to constitute the first nozzle array  130 A. 
     Similarly to the first nozzle holes  131 A, the second nozzle holes  131 B, the third nozzle holes  131 C, and the fourth nozzle holes  131 D are formed on the nozzle plate  32  at positions facing the ejection channels  57  of the head chips  51  in the respective head modules  30 B to  30 D in the Z direction. 
     As illustrated in  FIG. 7 , a slit  135  which penetrates the nozzle plate  32  in the Z direction is formed in a part of the nozzle plate  32  located between the second nozzle array  130 B and the third nozzle array  130 C in the Y direction. In the present embodiment, two slits  135  are formed at an interval in the Y direction. The slits  135  extend parallel to the nozzle arrays  130 A to  130 D along the X direction. The length in the X direction of the slit  135  is longer than the nozzle arrays  130 A to  130 D. The length of the slit  135  can be appropriately changed to any length shorter than the length in the X direction of the nozzle plate  32 . The number of slits  135  is not limited to two, and can be appropriately changed. 
     The material of the nozzle plate  32  is not limited to a resin material. The nozzle plate  32  may be formed of a metal material (e.g., stainless steel), or may be a laminated structure of a resin material and a metal material. Note that the nozzle plate  32  is preferably made of a material having a thermal expansion coefficient equivalent to the spacer  120 . A liquid repellent treatment is applied to a −Z direction end face of the nozzle plate  32 . In the present embodiment, the single nozzle plate  32  collectively covers the head modules  30 A to  30 D. However, the present invention is not limited to this configuration. A plurality of nozzle plates  32  may individually cover the respective head modules  30 A to  30 D. The liquid repellent treatment may not be applied to the nozzle plate  32 . 
     (Nozzle Guard) 
     The nozzle guard  33  is formed, for example, by pressing a plate material such as stainless steel. The nozzle guard  33  covers the module holding portion  41  from the −Z direction with the nozzle plate  32  and the spacer  120  interposed therebetween. 
     The nozzle guard  33  includes an exposure hole  141  which is formed at a position facing the nozzle arrays  130 A to  130 D in the Z direction and exposes the nozzle arrays  130 A to  130 D to the outside. The exposure hole  141  penetrates the nozzle guard  33  in the Z direction and is formed in a slit-like shape extending in the X direction. In the present embodiment, two exposure holes  141  are formed at an interval in the Y direction corresponding to the nozzle arrays  130 A,  130 B ejecting the same color of ink and the nozzle arrays  130 C,  130 D ejecting the same color of ink. That is, one of the exposure holes  141  exposes the first nozzle array  130 A and the second nozzle array  130 B to the outside. The other exposure hole  141  exposes the third nozzle array  130 C and the fourth nozzle array  130 D to the outside. 
     As illustrated in  FIG. 8 , the nozzle guard  33  is fixed to the spacer  120  with, for example, an adhesive. Specifically, the nozzle guard  33  is adhered to a part of the spacer  120  that is located on the outer side with respect to the nozzle plate  32  in plan view viewed from the Z direction (hereinbelow, referred to as a “first adhesion region  150 ”). The first adhesion region  150  is set to a frame shape surrounding the entire periphery of the nozzle plate  32 . The first adhesion region  150  may be adhered to the outer peripheral edge of the nozzle plate  32  as long as it is adhered to the spacer  120  at least outside the nozzle plate  32 . 
     Further, the nozzle guard  33  is adhered to a part of the spacer  120  that is exposed through each of the slits  135  of the nozzle plate  32  (hereinbelow, referred to as a “second adhesion region  151 ”). That is, the second adhesion region  151  extends parallel to the nozzle arrays  130 A to  130 D along the X direction. Accordingly, the second adhesion region  151  partitions between nozzle arrays of different colors in the nozzle arrays  130 A to  130 D (between the second nozzle array  130 B and the third nozzle array  130 C). 
     [Printer Operation Method] 
     Next, a method for recording information on the recording medium P using the printer  1  described above will be described. 
     As illustrated in  FIG. 1 , when the printer  1  is actuated, the grid rollers  11 ,  13  of the conveyance mechanisms  2 ,  3  rotate. Accordingly, the recording medium P is conveyed in the +X direction between the grid rollers  11 ,  13  and the pinch rollers  12 ,  14 . Simultaneously, the drive motor  28  rotates the pulley  26  to cause the endless belt  27  to travel. Accordingly, the carriage  23  moves back and forth in the Y direction while being guided by the guide rails  21 ,  22 . 
     During this operation, in each of the ink jet heads  5 A,  5 B, drive voltage is applied to the drive electrodes of the head chip  51 . This produces thickness-shear deformation in the drive walls  61 , which generates pressure waves in ink filled inside the ejection channels  57 . The pressure waves increase the internal pressure of the ejection channels  57 , so that the ink is ejected through the nozzle holes  131 A to  131 D. Then, the ink lands on the recording medium P. As a result, various kinds of information are recorded on the recording medium P. 
     In the present embodiment, for example, in the first head module  30 A, the head chip  51  and the drive board  53  are supported on the manifold  52  which includes the ink flow path  71 . 
     According to this configuration, a member which supports the head chip  51  and the drive board  53  and the ink flow path  71  are integrated to the manifold  52  which is disposed at one side in the Y direction with respect to the head chip  51 . This makes it possible to downsize the first head module  30 A in the Y direction (main-scanning direction) as compared to a conventional configuration in which a member which supports a head chip and a drive board is disposed at one side in the Y direction with respect to the head chip and a member which includes an ink flow path is separately disposed at the other side in the Y direction with respect to the head chip. As a result, it is possible to downsize the ink jet head  5 A in the Y direction. 
     Heat generated in the head chip  51  and the drive board  53  is dissipated to the outside through the manifold  52 . This makes it possible to enhance the heat dissipation performance of the head chip  51  and the drive board  53 . 
     Further, since the head chip  51  and the drive board  53  are supported on the manifold  52  which includes the ink flow path  71 , ink flowing through the ink flow path  71  can be heated (kept warm) using exhaust heat which is generated in the head chip  51  and the drive board  53  and transmitted to the manifold  52 . As a result, it is possible to supply ink having a desired temperature (viscosity) to the head chip  51  and thereby obtain an excellent printing characteristic. 
     In addition, in the present embodiment, the head modules  30 A to  30 D can be downsized in the Y direction. Thus, the manifold  52  can be provided in each of the head chips  51 . As a result, it is possible to enhance the heat dissipation performance of each of the head chips  51  as compared to a configuration in which a plurality of head chips  51  are mounted on each of the head modules  30 A to  30 D in order to achieve high-density recording. 
     Further, since the head modules  30 A to  30 D can be downsized in the Y direction, it is possible to provide the small ink jet heads  5 A,  5 B. 
     In the present embodiment, the damper  31  is disposed in the +Z direction with respect to the manifold  52 . Thus, it is possible to downsize the ink jet head  5 A in the Y direction as compared to a configuration in which the damper  31  and the manifold  52  are disposed side by side in the Y direction. 
     In the present embodiment, the ink flow path  71  extends in a meandering manner. Thus, exhaust heat from the head chip  51  and the drive board  53  can be effectively transmitted to ink inside the ink flow path  71 . As a result, it possible to supply ink having a desired temperature (viscosity) to the head chip  51  and thereby obtain an excellent printing characteristic. 
     In the present embodiment, the heater  85  is disposed on the face facing the +Y direction (the face opposite to the face supporting the drive board  53 ) of the manifold  52 . 
     According to this configuration, ink flowing through the ink flow path  71  can be heated also by the heater  85  in addition to the exhaust heat from the head chip  51  and the drive board  53 . Thus, it is possible to reliably supply ink having a desired temperature to the head chip  51 . 
     In the present embodiment, the insulating sheet  86  is interposed between the head chip  51  and the manifold  52 . Thus, a stray capacitance between the head chip  51  and the manifold  52  can be reduced. As a result, it is possible to reduce electrical noises generated when the head chip  51  is driven and enhance the operation reliability of the ink jet head  5 A. 
     Further, the use of a material having ink resistance such as polyimide as the insulating sheet  86  makes it possible to reduce elution of the insulating sheet  86  caused by ink and reduce ejection failures. 
     Further, the use of a soft material such as polyimide as the insulating sheet  86  makes it possible to relax a stress that acts on the head chip  51  and the manifold  52  due to a difference in thermal expansion coefficient between the head chip  51  and the manifold  52 . As a result, for example, it is possible to reduce cracking of the head chip  51  and come-off of the head chip  51  from the manifold  52 . 
     In the present embodiment, the nozzle plate  32  which includes the nozzle arrays  130 A to  130 D corresponding to the respective head modules  30 A to  30 D is disposed on the −Z direction end face of the base member  38 . 
     This configuration makes it possible to improve the position accuracy of the nozzle holes  131 A to  131 D as compared to a configuration in which the nozzle plate  32  is attached to each of the head modules  30 A to  30 D. 
     In the present embodiment, the spacer  120  is interposed between the nozzle plate  32  and the base member  38 . Thus, it is possible to relax a stress that acts on the nozzle plate  32  and the base member  38  due to a difference in thermal expansion coefficient between the nozzle plate  32  and the base member  38 . 
     Further, in the present embodiment, the spacer  120  is adhered to the base member  38  with the soft adhesive. Thus, it is possible to reliably relax a stress that acts on the spacer  120  and the base member  38  due to a difference in thermal expansion coefficient between the spacer  120  and the base member  38 . 
     As a result, it is possible to reduce come-off of nozzle plate  32  from the head chip  51 . 
     In the present embodiment, the first adhesion region  150  between the nozzle guard  33  and the spacer  120  surrounds the periphery of the nozzle plate  32 . 
     According to this configuration, when ink adhered to the −Z direction end face of the nozzle plate  32  or the nozzle guard  33  tries to enter the inside of the ink jet head  5 A through a gap between the nozzle plate  32  and the nozzle guard  33 , it is possible to dam up the ink with the first adhesion region  150 . As a result, it is possible to prevent ink from entering the inside of the ink jet head  5 A. 
     In the present embodiment, the second adhesion region  151  between the nozzle guard  33  and the spacer  120  is disposed between the nozzle arrays  130 B,  130 C which eject different colors of ink in the nozzle arrays  130 A to  130 D. 
     According to this configuration, the different colors of ink adhered onto the −Z direction end face of the nozzle plate  32  are blocked by the second adhesion region  151 . This makes is possible to reduce leakage of a mixture of the different colors of ink to the outside of the ink jet head  5 A. 
     In the present embodiment, the first biasing member and the second biasing members  70  which bias the base member  38  and the head modules  30 A to  30 D to one side in the X direction and the Y direction are interposed between the base member  38  and the head modules  30 A to  30 D. 
     According to this configuration, the head modules  30 A to  30 D are held on the base member  38  in a state pressed to the one side in the X direction and the Y direction. Thus, it is possible to position the head modules  30 A to  30 D with respect to the base member  38  with high accuracy. As a result, it is possible to improve assemblability when the head modules  30 A to  30 D are fixed to the base member  38  through the stays thereafter. 
     In the present embodiment, the temperature sensor  94  is disposed on the back face of the actuator plate  55 . Thus, it is possible to precisely detect the ink temperature in the ejection channels  57  as compared to a case in which the temperature sensor  94  is disposed at a position away from the actuator plate  55 . 
     In particular, in the present embodiment, the heat transfer plate  65  is disposed between the temperature sensor  94  and the actuator plate  55  so as to cover the entire channels  57 ,  58 . Thus, it is possible to detect an average ink temperature in all the ejection channels  57 . 
     In the present embodiment, the flow path member  72  and the flow path cover  73  are stacked to form the manifold  52 . This makes it possible to easily form the ink flow path  71  on the manifold  52  as compared to a configuration in which the manifold  52  is integrally formed. 
     In the present embodiment, the head chip  51  and the drive board  53  are supported on the flow path cover  73 . Thus, the flow path member  72  can be formed of a material having a high thermal conductivity regardless of proof stress for supporting the head chip  51  and the drive board  53 . In this case, since the flow path cover  73  is thinner than the flow path member  72 , heat generated in the head chip  51  and the drive board  53  is easily transmitted to the flow path member  72  through the flow path cover  73 . As a result, the heat generated in the head chip  51  and the drive board  53  is effectively dissipated to the outside through the manifold  52 , which enhances the heat dissipation performance of the head chip  51  and the drive board  53 . 
     The printer  1  of the present embodiment is provided with the ink jet head  5 A described above. Thus, it is possible to provide the printer  1  having high reliability while achieving downsizing in the Y direction. 
     The technical scope of the present invention is not limited to the above embodiment, and various modifications can be added without departing from the gist of the invention. 
     For example, in the above embodiment, the ink jet printer  1  has been described as an example of the liquid jet apparatus. However, the liquid jet apparatus is not limited to a printer. For example, the liquid jet apparatus may be a fax machine or an on-demand printing machine. 
     In the above embodiment, the four head modules  30 A to  30 D are mounted on the base member  38 . However, the present invention is not limited only to this configuration. The number of head modules mounted on the base member  38  may be on or more. 
     In the above embodiment, each two of the head modules eject one color of ink. However, the present invention is not limited only to this configuration. Three or more head modules may eject one color of ink, or one head module may eject one color of ink. 
     In the above embodiment, the edge shoot type head chip has been described. However, the present invention is not limited thereto. For example, the present invention may be applied to a side shoot type head chip which ejects ink from a central part in an extending direction of an ejection channel. 
     Further, the present invention may be applied to a roof shoot type head chip in which the direction of pressure applied to ink and an ejection direction of ink droplets are equal. 
     In the above embodiment, the head chip  51  and the drive board  53  are supported on the face facing the −Y direction of the flow path cover  73 . However, the present invention is not limited only to this configuration. The head chip  51  and the drive board  53  may be supported on any face facing the Y direction in the manifold  52 . For example, when the face facing the −Y direction in the manifold  52  is included in the flow path member  72  and the flow path cover  73 , either the head chip  51  or the drive board  53  may be supported on the flow path member  72 , and the other one may be supported on the flow path cover  73 . 
     In addition to the above, an element in the above embodiment can be appropriately replaced with a known element, or the above modifications may be appropriately combined without departing from the gist of the invention.