Patent Publication Number: US-8991979-B2

Title: Liquid ejecting head module and liquid ejecting apparatus

Description:
This application claims priority to Japanese Patent Application No. 2013-065815, filed Mar. 27, 2013, the entirety of which is incorporated by reference herein. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a liquid ejecting head module and a liquid ejecting apparatus having the same, more particularly to a liquid ejecting head module which is configured to include a plurality of unit heads and a drive substrate in a fixation member, and a liquid ejecting apparatus. 
     2. Related Art 
     The liquid ejecting apparatus is an apparatus which includes a liquid ejecting head and ejects various types of liquids from the liquid ejecting head. As the liquid ejecting apparatus, there are image recording apparatuses such as an ink jet printer, an ink jet plotter, and the like. However, recently considering the features of the liquid ejecting apparatus which can accurately shoot a very small amount of liquid on a predetermined position, the liquid ejecting apparatus have been applied to various types of manufacturing apparatuses, such as a display manufacturing apparatus which manufactures a color filter for a liquid crystal display and the like, an electrode forming apparatus which forms an electrode for an organic Electro Luminescence (EL) display, a Field Emission Display (FED), and the like, and a chip manufacturing apparatus which manufactures a biochip (biological and chemical element). A recording head of the image recording apparatus ejects a liquid ink, and a color material ejecting head of the display manufacturing apparatus ejects a solution of each color material of Red (R), Green (G), and Blue (B). In addition, an electrode material ejecting head of the electrode forming apparatus ejects a liquid electrode material, and a bio-organic substance ejecting head of the chip manufacturing apparatus ejects a solution made from bio-organic substance. 
     Lately, the printer is proposed where a plurality of ink jet recording heads (hereinafter, simply referred to simply as “recording head”) which are a type of the liquid ejecting head are fixed to a metal frame (fixation member) as a unit head to be modularized (unitized) (for an example, refer to JP-A-2012-111044). In this type of head module, a drive substrate handles a signal to drive the actuator (pressure generator) of each unit head, and a flow path member to which an ink to be supplied to each unit head is introduced are shared by each unit head, and thus, reducing the size of the entire module can be achieved. 
     However, recently, there has been a demand for further size reduction, and more particularly for further size reduction of a head module configured to have a unit head fixed to both side surfaces of a metal frame, respectively, the width direction of the head module needs to be more suppressed without lowering the rigidity of the metal frame. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a liquid ejecting head module which can be made small in size and a liquid ejecting apparatus including the liquid ejecting head module. 
     According to an aspect of the invention, there is provided a unit head having a nozzle surface where a nozzle for ejecting a liquid is formed, a liquid flow path communicating with the nozzle, and a pressure generator creating a change in the liquid pressure in the liquid flow path, and which ejects the liquid in the liquid flow path from the nozzle by driving the pressure generator; a fixation member in which the unit head is fixed to one fixation surface and the other fixation surface, respectively; a drive substrate which is located on a side of the fixation member opposite to the nozzle surface side of each unit head; and a wiring member which electrically connects the pressure generator of the unit head and the drive substrate, and in which the unit head has a first portion having the nozzle surface, and a second portion which is positioned on the opposite side to the nozzle surface of the first portion, has a contact portion which is fastened to the fixation member, and accommodates a portion of the wiring member, the contact portion of the second portion is formed at a position closer to a surface of an opposite side to a fixation member side than the side surface of the fixation portion on the fixation member side, the first portion is positioned further on a liquid ejecting side than the fixation member with the contact portion of the second portion fixed to the fixation member, and the wiring member whose one end portion is connected to the pressure generator is drawn through the second member, from a position close to a surface of an opposite side to the contact portion of the second member at an opposite side to the nozzle surface, and the other end portion of the wiring member is connected to the drive substrate. 
     In this configuration, the unit head has a first portion which has a nozzle surface, and a second portion which is positioned on an opposite side to the nozzle surface of the first portion, has a contact portion which is fastened to the fixation member, and accommodates a portion of the wiring member. The contact portion of the second portion is formed at the position closer to the surface of the opposite side to the fixation member side than a side surface of the first portion on the contact portion side, and the first portion is positioned further on a liquid ejecting side than the fixation member with the contact portion of the second portion fixed to the fixation member, so that the first portion is disposed closer to the fixation member side (a surface side opposite to a surface to which the unit head is fixed) than the contact portion in the fixed state. Therefore, nozzles of the unit heads fixed to the fixation surface on both sides of the fixation member come close to each other. By this configuration, without changing the thickness of the fixation member and the size of the first portion of the unit head, it is possible to suppress the size of the entire head module in the thickness direction (a contact direction of the contact portion of the unit head with the fixation surface of the fixation member). Therefore, the head module can be made smaller without reducing the rigidity of the fixation member. Then, by securing the rigidity of the fixation member, a position accuracy of each unit head fixed to the fixation member is prevented from being lowered. 
     In addition, a wiring member whose one end portion is connected to the pressure generator is drawn through the second member, from a position close to a surface of the opposite side to a contact portion of the second member to an opposite side to a nozzle surface, and the other end portion of the wiring member is connected to the drive substrate. Thus, routing the wiring member from a fixed position on the fixation member of the unit head to the drive substrate positioned at an opposite side (an opposite side to the nozzle surface) of the fixation position of the fixation member becomes easy, and the efficiency of the wiring operation is improved. In addition, it is possible to shorten the entire length of the wiring member as much as the length of the possible reduction in the folding, and this can contribute to cost reduction. 
     In addition, in the configuration, it is desirable to adopt a configuration in which the wiring member includes a first wiring member whose one end side is connected to the pressure generator, a second wiring member whose the other end side is connected to the drive substrate, and a relay substrate relaying between the second wiring member and the first wiring member, the relay substrate has a substrate terminal portion to which the other end side of the first wiring member is connected and a connection portion to which one end side of the second wiring member is connected, and is accommodated in the second portion, and at least the connection portion is disposed on a side of the relay substrate opposite to a fixation side with respect to the fixation member. 
     In this configuration, the first wiring member, the relay substrate, and the second wiring member are located so as to get close to a surface of the opposite side to the contact portion of the second portion by stages in this order. Therefore, it is possible to draw a wiring member to an opposite side to a nozzle surface from a position close to a surface of an opposite side to the contact portion of the second member without forcedly bending the wiring member from a joining position to the pressure generator. 
     Furthermore, the liquid ejecting apparatus of the invention includes a liquid ejecting head module in any of the above configurations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIGS. 1A and 1B  are schematic views each describing an internal configuration of a printer. 
         FIG. 2  is a front view of a head module. 
         FIG. 3  is a cross-sectional view of the head module in a transverse direction. 
         FIG. 4  is a cross-sectional view of a unit head. 
         FIG. 5  is a cross-sectional view of the main portion of a head main body. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, embodiments for carrying out the invention will be described referring to accompanying drawings. The embodiments to be described below are variously limited as an appropriate detailed example of the invention, but the scope of the invention is not limited to these embodiments particularly unless there is a description to the effect of limiting the invention in the following description. In addition, in the following description, as a liquid ejecting apparatus of the invention, an ink jet printer (hereinafter, referred to as “printer”) which is mounted with a head module (liquid ejecting head module)  2  to which a plurality of ink jet recording heads (hereinafter, referred to as “unit head”) which are a type of a liquid ejecting head are fixed is used as an example. 
       FIGS. 1A and 1B  are schematic views each describing the internal configuration of a printer  1 .  FIG. 1A  is a plan view and  FIG. 1B  is a side view. For example, the printer  1  includes a head module  2  which is elongated along the width direction (a direction substantially orthogonal to the transport direction of a recording sheet) of a recording sheet  6  such as a roll sheet (a type of a recording medium or a shooting object), a sheet feeding roller  4  which supplies the recording sheet  6  to a transport belt  11 , a sheet feeding motor  9  for driving the sheet feeding roller  4 , a transport mechanism  5  which transports the recording sheet  6  using the transport belt  11 , an ink cartridge  10  (a type of a liquid supply source) which stores an ink. The printer  1  according to the embodiment is a so-called line head type ink jet recording device which performs only the transport of the recording sheet  6  during a recording operation without accompanying the scanning of a head module  2  in the width direction of the recording sheet  6 . The ink cartridge  10  and a sub-tank  27  of the head module  2  to be described later are connected to each other, for example, using a supply tube  19  made from a flexible member such as a silicon resin and the like. The ink stored in the ink cartridge  10  is pressurized and transported to the head module  2  side through a supply tube  19  using a pump not illustrated. 
     The sheet feeding roller  4  is located upstream of the transport mechanism  5 , and is configured to have a pair of upper and lower rollers  4   a  and  4   b  which may be synchronously rotatable in opposite directions with the recording sheet  6  fed from a sheet feeding unit not illustrated pinched. The sheet feeding roller  4  is driven by power from the sheet feeding motor  9  and is configured to supply the recording sheet  6  to the transport mechanism  5  side. The transport mechanism  5  is configured to have a transport motor  12  which is a drive source of the transport belt  11 , a drive roller  13  to which the power is delivered from the transport motor  12 , a driven roller  14  located further upstream side than the drive roller  13 , the transport belt  11  in an endless shape stretched between the drive roller  13  and the driven roller  14 , and a pressure roller  16  which presses the recording sheet  6  against the transport belt  11  side. The pressure roller  16  is located right on the driven roller  14  with the transport belt  11  pinched and is provided to contact the transport belt  11 . 
       FIG. 2  is a front view which describes a configuration of the head module  2  in the embodiment. In addition,  FIG. 3  is a cross-sectional view of the head module  2  in a short direction. 
     The head module  2  in the embodiment is configured to have a plurality of unit heads  26 , a sub-tank  27  common to each unit head  26 , and a drive substrate  28  common to each unit head  26  mounted on, for example, a metal frame  25  such as stainless steel and the like. The frame  25  has a shape that an elongated base frame  30  in a direction intersecting (orthogonal) with the transport direction of the recording sheet  6  is combined with a fixation frame  31  protruding downward from the lower surface of the base frame  30  (the recording sheet  6  side or an ink ejection side during a recording operation) in a T-shape in a side view. Therefore, the front and the back surfaces (one side surface and the other side surface) of the fixation frame  31  are perpendicular to the upper and the lower surfaces of the base frame  30 . The front and the back surfaces of the fixation frame  31  are the fixation surfaces  32  on which the unit head  26  is mounted. Then, with the front side of the fixation surface  32  facing upstream side in the transport direction of the recording sheet  6  and the back side of the fixation surface  32  facing downstream side in the transport direction of the recording sheet  6 , a head module  2  is located in the printer  1 . 
     On the front and the back fixation surfaces  32  of the fixation frame  31 , a plurality of unit heads  26  are mounted respectively along the longitudinal direction of the frame  25 . In the embodiment, respective five unit heads  26 , in total of 10 heads, are fixed to the front and the back fixation surfaces  32  of the fixation frame  31  via screw. The unit head  26  on the front fixation surface and the unit heads  26  on the back fixation surface are disposed so as to be away from each other in the longitudinal direction of the frame. 
     The unit head  26  is configured to have a substrate case  33  (corresponding to a second portion in the invention) and a head main body  34  (corresponding to a first portion in the invention). The substrate case  33  is a hollow box-shaped member where a case flow path (not illustrated) to which an ink is introduced from the sub-tank  27  side and an accommodation space portion  35  in which a relay substrate  36  to be described later is accommodated are formed therein. On both sides of the substrate case  33 , flange portions  33   a  and  33   b  which are thinner than the substrate case  33  are provided, respectively (refer to  FIG. 2 ). On the flange portions  33   a  and  33   b , corresponding to a fastening hole provided on a head fixed portion (fixation surface  32 ) of the fixation frame  31 , an insertion hole  39  in which a fastening member such as a screw is inserted is provided. One surface of the front and the back side surfaces of the substrate case  33  functions as a fastening surface  40  (corresponding to a contact portion in the invention) which is fastened in contact with the fixation surface  32 . When the fastening surface  40  is screwed into the fixation surface  32  of the fixation frame  31 , the fastening surface  40  is configured so that a fixed position of the unit head  26  in the frame  25  is defined. A configuration can be adopted in which only the flange portions  33   a  and  33   b  are in contact with the fixation surface  32  of the fixation frame  31 , and the other portions are not in contact with the fixation surface  32  (spaced apart). In the configuration, the flange portions  33   a  and  33   b  function as a contact portion in the invention. In short, a portion in contact with the frame  25  to define a position (in particular, a position of a direction overlapping the frame  25  (the thickness direction of the frame  25 )) of the frame  25  when fixing the frame  25  is corresponding to a contact portion. Therefore, a portion (for example, a portion in contact with the frame  25  to receive an ink) in contact with the frame  25  for purposes other than performing a function of positioning is not included as the contact portion in the invention. 
     The thickness of the substrate case  33 , that is, the size W1 in a direction overlapping the fixation surface  32  of the fixation frame  31  is shorter than the size W2 of the head main body  34  in the same direction. Then, the fastening surface  40  of the substrate case  33  is formed at a position closer to a side surface  40 ′ opposite to the fixation surface  32  side of the fixation frame  31  than a side surface  34 ′ of the head main body  34  on the fixation frame  31  side. Accordingly, a portion (at least the head main body  34 ) of the unit head  26  lower than the fastening surface  40  further protrudes to the fixation frame  31  side than the fastening surface  40 . Therefore, the relay substrate  36  which is accommodated in the substrate case  33  is located at a position closer to the side surface  40 ′ opposite to the fixation surface  32  side of the fixation frame  31  than the center line C in the width direction of the head main body  34 . 
     The relay substrate  36  is a substrate which performs a relay between a first cable  37  connected to a piezoelectric element  46  of the head main body  34  and a second cable  38  from the drive substrate  28  side. The first cable  37 , the relay substrate  36 , and the second cable  38  configure a wiring member in the invention. In the relay substrate  36 , a substrate terminal portion  41  electrically connected to the other end side terminal (not illustrated) of the first cable  37 , a connector  42  (corresponding to a connection portion in the invention) connected to the second cable  38 , other circuit patterns and the like thereof are formed. In the embodiment, a substrate terminal portion and the connector  42  are provided on surfaces opposite to each other. Then, in a state that a surface where the substrate terminal portion  41  is provided is the fastening surface  40  side and a surface where the connector  42  is provided is an opposite side to the fastening surface  40 , the substrate terminal portion  41  and the connector  42  are accommodated in the accommodation space portion  35 . Therefore, the connector  42  of the relay substrate  36  is located at a position still closer to the side surface  40 ′ opposite to the fixation surface  32  side of the fixation frame  31  than the relay substrate  36 . The substrate terminal portion may be configured to be formed on the same surface side as the connector  42 . 
     On the upper surface (a surface opposite to the nozzle surface of the head main body  34 ) of the substrate case  33 , introduction portions  43  in a cylindrical shape where an ink is introduced from the sub-tank  27  side are erectly provided on both sides in a nozzle arrangement direction, respectively. The introduction portions  43  are connected to an outlet portion which is provided in the sub-tank  27  mounted on a base frame  30  and is not illustrated. An ink introduced to the introduction portions  43  is supplied to the reservoir side of the head main body  34  through a case flow path formed in the substrate case  33 . In addition, on the upper surface of the substrate case  33 , between two introduction portions  43 , a wiring opening  45  is provided through which the second cable  38  connected to the connector  42  in the accommodation space portion  35  is drawn out. The wiring opening  45 , corresponding to a position of the connector  42 , is formed at a position close to the side surface  40 ′ of the opposite side to the fastening surface  40  side. 
       FIG. 5  is a cross-sectional view of a main portion illustrating an internal configuration of the head main body  34  (head chip) in the embodiment. 
     The head main body  34  in the embodiment is schematically configured to have a nozzle plate  47 , a flow path substrate  48 , a piezoelectric element  46 , a protection substrate  49 , and the like, and is mounted onto a case  50  where these members are stacked. 
     The nozzle plate  47  (a type of a nozzle forming member) is a member in a plate shape where a plurality of nozzles  51  are opened in a row along the width direction of the recording sheet  6  at a pitch corresponding to a dot formation density in the same direction. In the embodiment, two nozzle rows (a type of nozzle group) configured to have the plurality of nozzles  51  provided side by side are arranged in a direction corresponding to a recording sheet transport direction of the nozzle plate  47 . Then, a side surface to which an ink of the nozzle plate  47  is ejected becomes a nozzle surface in the invention. 
     On the flow path substrate  48 , a plurality of pressure chambers  52  partitioned by a plurality of partition walls using an anisotropic etching process are formed corresponding to each nozzle  51 . On the outside of the row of the pressure chamber  52  on the flow path substrate  48 , a common liquid chamber  53  partitioning a portion of the common liquid chamber  53  is formed. The common liquid chamber  53  communicates with each pressure chamber  52 . The piezoelectric element  46  (a type of the pressure generator) is formed on the upper surface of an opposite side to the nozzle plate  47  side of the flow path substrate  48  through an elastic film  54 . The piezoelectric element  46  is formed by sequentially stacking a lower electrode film made of metal, a piezoelectric layer made of, for example, lead zirconate titanate or the like, and an upper electrode film made of metal (none illustrated). The piezoelectric element  46  is a so-called piezoelectric element in a flexural mode, and is formed so as to cover the top of the pressure chamber  52 . In the embodiment, two piezoelectric element rows corresponding to two nozzle rows are provided side by side in a direction orthogonal to a nozzle row in a state where the piezoelectric elements  46  are away from each other as viewed in a nozzle row direction. From each piezoelectric element  46 , an electrode terminal  55  is extended to the center region between the piezoelectric element rows, respectively. 
     On the flow path substrate  48  where the piezoelectric element  46  is formed, the protection substrate  49  having a wiring hollow portion  59  penetrated in the thickness direction is disposed. In a plan view, an electrode terminal  55  of the piezoelectric element  46  is disposed in the wiring hollow portion  59  of the protection substrate  49 . An end portion of the first cable  37  is inserted into the wiring hollow portion  59 , and an end side wiring terminal  56  formed on the one end portion is electrically connected to the electrode terminal  55  of the piezoelectric element  46 . Then, each piezoelectric element  46  is configured so as to be deformed by applying a drive voltage through the first cable  37 . In addition, on the protection substrate  49 , a relief hollow portion  60  in a size not to impede the drive of the piezoelectric element  46  is formed in a region facing the piezoelectric element  46 . 
     In a case  50 , an ink introduction path  61  for supplying an ink introduced from the sub-tank  27  side to the common liquid chamber  53  side by communicating with a case flow path (not illustrated) of the substrate case  33  is formed, and a hollow portion  62  penetrated in the width direction is provided at the center portion thereof. Then, the other end side of the first cable  37  whose one end side wiring terminal  56  is connected to the electrode terminal  55  is drawn into the accommodation space portion  35  of the substrate case  33  through the wiring hollow portion  59  and the hollow portion  62  of the case  50 , and the other side wiring terminal is electrically connected to the substrate terminal portion  41  of the relay substrate  36 . The first cable  37  and the second cable  38  are made of a flexible cable. More specifically, a conductive pattern of a copper coil and the like is formed on the surface of the base film having flexibility such as polyimide and the like, and a conductive pattern other than the wiring terminal of both sides is configured to be covered by resist. 
     The unit head  26  configured as described above introduces an ink from the sub-tank  27  into the common liquid chamber  53  side through the introduction portions  43 , a case flow path, and an ink introduction path  61 , and fills an ink flow path (a type of liquid flow path) leading to the nozzle  51  through a pressure chamber  52  from the common liquid chamber  53  with an ink. Then, a drive signal from the drive substrate  28  side is applied to the piezoelectric element  46  through a wiring member such as the first cable  37  and the like and the piezoelectric element  46  is flexurally deformed. Accordingly, there is created a change in the pressure of an ink in a corresponding pressure chamber  52 , an ink is ejected from a nozzle  51  by the change in the pressure of an ink. 
     Here, when the unit head  26  is fixed in a state where the fastening surface  40  of the substrate case  33  is positioned in contact with the fixation surface  32  of the fixation frame  31  in the frame  25 , the head main body  34  is positioned lower than the lower end surface (the end surface of a nozzle surface side of the unit head  26 ) of the fixation frame  31 . In addition, the fastening surface  40  is offset further to the side surface  40 ′ of an opposite side to the fixation frame  31  than to the side surface  34 ′ of the fastening surface  40  side of the head main body  34 , so that a portion of the head main body  34  protrudes towards further the fixation frame  31  side (an opposite surface side of the fixation frame  31 ) than the fastening surface  40 . That is, in the embodiment, the head main body  34  is disposed closer to the fixation frame  31  side than to the fastening surface  40  due to a difference between W2 and W1. Therefore, nozzles of the unit heads  26  which are fixed to the fixation surface  32  of both sides of the fixation frame  31  come close to each other. By this configuration, without changing the thickness of the fixation frame  31  in the frame  25  and the size of the head main body  34 , it is possible to suppress the size of the entire head module  2  in the thickness direction (a contact direction of the fastening surface  40  of the unit head  26  with the fixation surface  32  of the fixation frame  31 ). Therefore, it is possible to make the head module  2  small without reducing the rigidity of the frame  25 . 
     The drive substrate  28  is a substrate which receives a control signal such as a drive signal and the like sent from a control unit side of the printer  1 , which is not illustrated, and distributes the received control signal to each unit head  26  through the second cable  38 . On both sides of the drive substrate  28 , a plurality of connectors  64  corresponding to each unit head  26  are provided. The other end portion of the second cable  38  whose one end portion is connected to the connector  42  of the relay substrate  36  of the unit head  26  is connected to the connector  64 . The drive substrate  28  is supported by the support frame  29  in a standing posture with respect to the base frame  30  of the frame  25 , and is fixed to the upper surface side (an opposite side to the nozzle surface of the unit head  26 ) of the base frame  30  through the support frame  29 . The support frame  29  is a member which is formed in a substantially rectangular cylindrical shape in a side view by a thin metal plate. In the internal space of the support frame  29 , the sub-tank  27  and the like besides the drive substrate  28  are accommodated. In addition, at a position facing the connector  64  of the drive substrate  28 , an opening  65  which exposes these connectors  64  is provided. 
     In the embodiment, the relay substrate  36  is located at a position closer to the side surface  40 ′ of the opposite side to the fixation surface  32  side (fastening surface  40  side) of the fixation frame  31  than the center line C of the head main body  34  in the width direction, and the connector  42  is located at a position closer to the side surface  40 ′ than the relay substrate  36 , so that the first cable  37 , the relay substrate  36 , and the second cable  38  are located so as to get close to the side surface  40 ′ of the substrate case  33  by stages in this order. Therefore, it is possible to draw a wiring member to an opposite side to a nozzle surface through the wiring opening  45  from a position close to the side surface  40 ′ opposite to the fastening surface  40  without forcedly bending the wiring member from a joining position to the electrode terminal  55  of the piezoelectric element  46 . Then, the other end side of the second cable  38  outside from the wiring opening  45  is extended to the drive substrate  28  located on the base frame  30  in the frame  25  in a substantially straight state without being significantly largely bent. Then, in the embodiment, the other end portion of the second cable  38  is folded at a fold line with a slope of about 45 in the longitudinal direction of the cable, and the other end portion of the wiring terminal portion is electrically connected to a corresponding connector  64  of the drive substrate  28 . Thus, routing the wiring member from a fixed position of the unit head  26  to the drive substrate  28  positioned at an opposite side to the fixed position on the frame  25  becomes easy, so that the efficiency of the wiring operation is improved. In addition, it is possible to shorten the entire length of the wiring member as much as the folding can be reduced, and this can contribute to cost reduction. 
     The embodiment illustrates an example in which the first portion (head main body  34 ) and the second portion (substrate case  33 ) are configured to have a different member, but the embodiment is not limited thereto. The embodiment may be configured to include a portion corresponding to the first portion and a portion corresponding to the second portion in the same member (a member integrally formed). 
     In addition, the invention is not limited to the embodiment described above. Additionally, the embodiment illustrates the head module  2  mounted on the ink jet printer, but if a head module with this configuration is adopted, the embodiment can be applied to those ejecting a liquid other than an ink. For example, the invention can be applied to a color material ejecting head used in manufacturing a color filter for a liquid crystal display and the like, an electrode material ejecting head used in forming an electrode for an organic Electro Luminescence (EL) display, a Field Emission Display (FED), and the like, and a bio-organic material ejecting head used in manufacturing a biochip (biological and chemical element) and the like.