Patent Publication Number: US-2022212470-A1

Title: Liquid ejecting head and recording apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2021-001309, filed Jan. 7, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     Embodiments of the present disclosure relate to a liquid ejecting head and a recording apparatus. 
     2. Related Art 
     Some liquid ejecting heads according to related art are configured to eject liquid contained inside pressure compartments from nozzles by causing piezoelectric elements to vibrate a diaphragm disposed over the pressure compartments as disclosed in, for example, JP-A-2014-188717, JP-A-2007-062036, and JP-A-2009-269315. The liquid ejecting head includes a sealing plate that seals the piezoelectric elements. The sealing plate has an opening. Lead electrodes connected from the piezoelectric elements extend in one direction and are electrically coupled to a flexible wiring board inside the opening. Drive signals for driving the piezoelectric elements are communicated to the piezoelectric elements via the flexible wiring board and the lead electrodes. 
     In the process of connecting the flexible wiring board to the lead electrodes, a tool for mounting is inserted into the opening of the sealing plate. The tool applies heat to an adhesive inside the opening so that the adhesive will cure. The flexible wiring board becomes mounted to the lead electrodes due to the curing of the adhesive. The following problem might occur in related art: the tool might collide with a wall surface of the opening in the process of inserting the tool into the opening, and, if such a collision occurs, it is difficult to mount the flexible wiring board onto the lead electrodes with high precision. 
     SUMMARY 
     A liquid ejecting head according to a certain aspect of the present disclosure includes a pressure compartment forming substrate, a piezoelectric actuator, a sealing plate, and a flexible wiring board. A pressure compartment is formed in the pressure compartment forming substrate. The piezoelectric actuator is disposed over the pressure compartment. The sealing plate has an opening going from a first surface, which is farther from the pressure compartment, to a second surface, which is closer to the pressure compartment. The sealing plate is configured to cover the piezoelectric actuator located in a first direction with respect to the opening. The flexible wiring board is inserted in the opening and is electrically coupled to the piezoelectric actuator. A first opening width of the opening at the first surface in the first direction is greater than a second opening width of the opening at the second surface in the first direction. 
     A recording apparatus according to a certain aspect of the present disclosure includes the above liquid ejecting head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram that illustrates, partially by blocks, an example of the configuration of a liquid ejecting apparatus according to a first embodiment. 
         FIG. 2  is a cross-sectional view of a liquid ejecting head taken along an X-Z plane. 
         FIG. 3  is a cross-sectional view of a sealing plate, piezoelectric actuators, and a pressure compartment forming substrate of the liquid ejecting head. 
         FIG. 4  is a perspective view of the sealing plate of the liquid ejecting head. 
         FIG. 5  is a plan view of the sealing plate of the liquid ejecting head. 
         FIG. 6  is an enlarged cross-sectional view of an opening of the sealing plate. 
         FIG. 7  is an enlarged cross-sectional view of an opening of a sealing plate of a liquid ejecting head according to a second embodiment. 
         FIG. 8  is a cross-sectional view of a sealing plate of a liquid ejecting head according to a first modification example. 
         FIG. 9  is a cross-sectional view of a sealing plate of a liquid ejecting head according to a second modification example. 
         FIG. 10  is a cross-sectional view of a sealing plate of a liquid ejecting head according to a third modification example. 
         FIG. 11  is a cross-sectional view of a sealing plate of a liquid ejecting head according to a fourth modification example. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     With reference to the accompanying drawings, an exemplary embodiment of the present disclosure will now be explained. In the drawings, the dimensions and scales of components may be made different from those in actual implementation. Since the embodiment described below shows some preferred examples of the present disclosure, they contain various technically-preferred limitations. However, the scope of the present disclosure shall not be construed to be limited to the examples described below unless and except where any intention of restriction is mentioned explicitly. 
     In the description below, three directions that are orthogonal to one another will be referred to as X-axis direction, Y-axis direction, and Z-axis direction. The X-axis direction includes X1 direction and X2 direction, which are the opposite of each other. The X-axis direction is an example of a first direction. The Y-axis direction includes Y1 direction and Y2 direction, which are the opposite of each other. The Y-axis direction is an example of a second direction. The Z-axis direction includes Z1 direction and Z2 direction, which are the opposite of each other. The Z1 direction is the direction going down. The Z2 direction is the direction going up. In this specification, the terms “upper” and “lower” will be used. The terms “upper” and “lower” as used herein correspond to the ordinary meaning of “upper” and “lower” in a normal state of use, in which nozzles are directed vertically downward, of a liquid ejecting apparatus  1 . 
     The X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to one another. In an ordinary configuration, the Z-axis direction is along the vertical direction. However, the Z-axis direction is not necessarily along the vertical direction. 
       FIG. 1  is a schematic diagram that illustrates an example of the configuration of a liquid ejecting apparatus  1  according to a first embodiment. The liquid ejecting apparatus  1  is an ink-jet-type printing apparatus that ejects droplets of ink, which is an example of “liquid”, onto a medium P. The liquid ejecting apparatus  1  according to the present embodiment is a head-scan-type printing apparatus also called as a serial-type printer that reciprocates a plurality of nozzles, from which ink is ejected, in the direction of the width of the medium P. The medium P is, typically, printing paper such as plain paper, coated paper, glossy paper, etc. The medium P is not limited to printing paper. The medium P may be a print target made of any material such as, for example, a resin film or a cloth. The liquid ejecting apparatus  1  is an example of a recording apparatus. 
     As illustrated in  FIG. 1 , the liquid ejecting apparatus  1  includes a liquid container  2  that contains ink. Some specific examples of the liquid container  2  are: a cartridge that can be detachably attached to the liquid ejecting apparatus  1 , a bag-type ink pack made of a flexible film material, an ink tank which can be refilled with ink, etc. Any type of ink may be contained in the liquid container  2 . The liquid container  2  is an example of a liquid containing unit. 
     In an ordinary configuration, the liquid container  2  includes a first liquid container and a second liquid container, though not illustrated. The liquid container  2  may be a single liquid container instead. The first liquid container contains first ink. The second liquid container contains second ink, the type of which is different from the type of the first ink. For example, the color of the first ink and the color of the second ink are different from each other. The first ink and the second ink may be the same type of ink. 
     The liquid ejecting apparatus  1  includes a control unit  3 , a medium transportation mechanism  4 , a carriage  5 , a carriage transportation mechanism  6 , and a plurality of liquid ejecting heads  10 . The control unit  3  controls the operation of each component of the liquid ejecting apparatus  1 . The control unit  3  includes a processing circuit, for example, a CPU (central processing unit) or an FPGA (field programmable gate array), and a storage circuit such as a semiconductor memory. Various kinds of program and data are stored in the storage circuit. The processing circuit realizes various kinds of control by running the program and using the data. 
     The medium transportation mechanism  4  is controlled by the control unit  3  and transports the medium P in a transportation direction DM. The transportation direction DM is, for example, the Y1 direction. The transportation direction DM is not limited to the Y1 direction. The transportation direction DM may be the Y2 direction or any other direction. The medium transportation mechanism  4  includes a transportation roller that is elongated in the X-axis direction and a motor that causes the transportation roller to rotate. The configuration of the medium transportation mechanism  4  is not limited to the illustrated example in which the transportation roller is used. For example, a drum that transports the medium P in a state in which the medium P is attracted to the circumferential surface of the drum due to an electrostatic force, etc., or an endless belt, may be used instead. 
     The plurality of liquid ejecting heads  10  is mounted on the carriage  5 . The carriage transportation mechanism  6  is controlled by the control unit  3  and reciprocates the carriage  5  in the X-axis direction. The carriage transportation mechanism  6  includes, for example, an endless belt tensioned around and between plural rollers distanced from each other in the X-axis direction. 
     Ink flows from the liquid container  2  through an ink flow passage and is then supplied to the liquid ejecting head  10 . The liquid ejecting head  10  is controlled by the control unit  3  and ejects ink from each of the plurality of nozzles toward the medium P. 
     Next, with reference to  FIG. 2 , ink flow passages  11  formed inside the liquid ejecting head  10  will now be explained.  FIG. 2  is a cross-sectional view of the liquid ejecting head  10  taken along an X-Z plane. The X-Z plane is a plane that is along the X-axis direction and the Z-axis direction. In  FIG. 2 , the direction in which ink flows inside the liquid ejecting head  10  is indicated by arrows. Flow passages  11  through which ink flows are formed inside the liquid ejecting head  10 . The flow passage  11  leads from a supply inlet  12  to a nozzle N. The flow passages  11  are line-symmetric with respect to a center line O extending in the Z-axis direction. 
     The flow passage  11  includes the supply inlet  12 , a common reservoir  13 , a common reservoir  14 , a relay flow passage  15 , a relay flow passage  16 , a pressure compartment  17 , a communication flow passage  18 , and the nozzle N. The supply inlet  12  is provided on both sides in the X-axis direction of the liquid ejecting head  10 . The supply inlet  12  is in communication with the common reservoir  13  in the Z-axis direction. The common reservoir  13  is in communication with the common reservoir  14  in the Z-axis direction. The common reservoirs  13  and  14  are formed in different members respectively. The common reservoir  13 ,  14  extends in the Y-axis direction. The common reservoir  13 ,  14  is a common space that is in communication with the plurality of pressure compartments  17 . The plural pressure compartments  17  are arranged next to one another in the Y-axis direction. 
     A plurality of relay flow passages  15 ,  16  is connected to the common reservoir  14 . The plurality of relay flow passages  15 ,  16  is provided such that they correspond to the plurality of pressure compartments  17  respectively. The plural relay flow passages  15  are arranged next to one another in the Y-axis direction. The relay flow passage  15  extends from the outside toward the inside in the X-axis direction. The relay flow passage  16  is connected to the downstream end of the relay flow passage  15 . The relay flow passage  16  extends in the Z2 direction from the relay flow passage  15  and is in communication with the pressure compartment  17 . 
     Each of the plurality of pressure compartments  17  extends inward in the X-axis direction. The communication flow passage  18  is connected to the downstream end of the pressure compartment  17  and extends in the Z1 direction. The plurality of communication flow passages  18  is connected to the plurality of pressure compartments  17  respectively. The plurality of communication flow passages  18  is connected to the plurality of nozzles N respectively. 
     The communication flow passage  18  is located downstream of the pressure compartment  17 . The communication flow passage  18  is located at an inner side in the X-axis direction in comparison with the relay flow passage  16 . The communication flow passage  18  provides communication between the pressure compartment  17  and the nozzle N. The communication flow passage  18  extends in the Z-axis direction. 
     Next, the flow of ink inside the liquid ejecting head  10  will now be explained. Ink flows into the liquid ejecting head  10  through the supply inlet  12 . The ink having passed through the supply inlet  12  flows into the common reservoir  13  and next into the common reservoir  14 . The flow path of the ink from the common reservoir  14  branches into the plurality of relay flow passages  15 . The ink in the relay flow passage  15  flows through the relay flow passage  16  into the pressure compartment  17 . The pressure of the ink in the pressure compartment  17  is raised by a piezoelectric actuator  31 , which will be described later. Due to the rise in pressure, the ink in the pressure compartment  17  flows through the communication flow passage  18  to be ejected from the nozzle N. 
     Next, the structure of the liquid ejecting head  10  will now be explained. The liquid ejecting head  10  includes a nozzle plate  21 , a bottom plate  22 , a flow passage forming substrate  23 , a pressure compartment forming substrate  24 , a diaphragm  25 , and the piezoelectric actuators  31 . The liquid ejecting head  10  further includes a sealing plate  40  for sealing the piezoelectric actuators  31 , a COF  60  coupled to the piezoelectric actuators  31  electrically, and a cover  70  enclosing the sealing plate  40 . COF is an acronym for Chip On Film. 
     The supply inlet  12  and the common reservoir  13  are formed in the cover  70 . A cavity for accommodating the pressure compartment forming substrate  24 , the diaphragm  25 , the piezoelectric actuators  31 , and the sealing plate  40  is formed in the cover  70 . The cover  70  encloses the sealing plate  40  from the Z2-directional side. The common reservoir  13  is located on both sides outside the sealing plate  40  in the X-axis direction. The cover  70  has an opening  75  at a position corresponding to the opening  50  of the sealing plate  40 . 
     The nozzle plate  21  has the plurality of nozzles N. The nozzle N is a through hole going in a plate-thickness direction. The plate-thickness direction of the nozzle plate  21  is along the Z axis. The nozzles N constitute each nozzle row, that is, a row of nozzles arranged linearly in the Y-axis direction. Plural nozzle rows distanced from each other in the X-axis direction are formed in the nozzle plate  21 . The nozzle plate  21  is bonded to the bottom surface of the flow passage forming substrate  23  and covers the communication flow passages  18  from below. The nozzles N are located at respective positions corresponding to the communication flow passages  18 . 
     The bottom plate  22  is disposed outside the nozzle plate  21  in the X-axis direction. The bottom plate  22  is bonded to the bottom surface of the flow passage forming substrate  23  and covers the common reservoir  14  and the relay flow passages  15 ,  16  from below. 
     The common reservoir  14 , the relay flow passages  15 ,  16 , and the communication flow passages  18  are formed in the flow passage forming substrate  23 . The common reservoir  14 , the relay flow passages  16 , and the communication flow passages  18  are openings going through the flow passage forming substrate  23  in the plate-thickness direction. The plate-thickness direction of the flow passage forming substrate  23  is along the Z axis. The relay flow passage  15  is a groove formed in the bottom surface of the flow passage forming substrate  23 . 
     The pressure compartments  17  are formed in the pressure compartment forming substrate  24 . The pressure compartments  17  are openings going through the pressure compartment forming substrate  24  in the plate-thickness direction. The length of the pressure compartment forming substrate  24  in the X-axis direction is less than the length of the flow passage forming substrate  23  in the X-axis direction. The pressure compartment forming substrate  24  is bonded to the top surface of the flow passage forming substrate  23 . 
       FIG. 3  is a cross-sectional view of the sealing plate  40 , the piezoelectric actuators  31 , and the pressure compartment forming substrate  24  of the liquid ejecting head  10 . As illustrated in  FIG. 3 , the diaphragm  25  is disposed on the top surface of the pressure compartment forming substrate  24 . The plate-thickness direction of the diaphragm  25  is along the Z axis. The diaphragm  25  covers the openings of the pressure compartment forming substrate  24 . The portion, of the diaphragm  25 , covering the openings of the pressure compartment forming substrate  24  constitutes the ceiling of the pressure compartments  17 . The diaphragm  25  is formed of a plurality of insulation layers. The diaphragm  25  includes a first insulation layer made of silicon dioxide (SiO 2 ) and a second insulation layer made of zirconium dioxide (ZrO 2 ). The first insulation layer is formed on the pressure compartment forming substrate  24 . The second insulation layer is formed on the first insulation layer. The diaphragm  25  is driven by the piezoelectric actuator  31  and vibrates in the Z-axis direction. 
     The plurality of piezoelectric actuators  31  is disposed on the diaphragm  25 . The plurality of piezoelectric actuators  31  is provided such that they correspond to the plurality of pressure compartments  17  respectively. The piezoelectric actuator  31  includes a lower electrode  32 , a piezoelectric layer  33 , and an upper electrode  34 . The lower electrode  32 , the piezoelectric layer  33 , and the upper electrode  34  are stacked in this order on the diaphragm  25 . The lower electrode  32  is an individual electrode(s). The upper electrode  34  is a common electrode. The common electrode may be the lower electrode. The individual electrode may be the upper electrode. 
     The lower electrodes  32  are arranged at predetermined intervals in the Y-axis direction. Each of the plurality of lower electrodes  32  is located at a position overlapping with the corresponding one of the plurality of pressure compartments  17  as viewed in the Z-axis direction. The lower electrode  32  has a predetermined length in the X-axis direction, and extends inward toward the center line O from the position over the pressure compartment  17 . 
     The lower electrode  32  includes, for example, an electrode layer containing a conductive material having a low resistance such as platinum (Pt) or iridium (Ir), etc., and a ground layer containing titanium (Ti). The electrode layer may be made of oxide such as, for example, strontium ruthenate (SrRuO 3 ), lanthanum nickelate (LaNiO 3 ), etc. 
     The piezoelectric layer  33  is formed on the lower electrode  32 . The piezoelectric layer  33  is disposed in such a way as to cover the plurality of lower electrodes  32 . The piezoelectric layer  33  is a band-shaped dielectric film extending in the Y-axis direction. 
     The upper electrode  34  is formed on the piezoelectric layer  33 . The upper electrode  34  extends in the Y-axis direction in such a way as to cover the plurality of lower electrodes  32 , with the piezoelectric layer  33  sandwiched therebetween. The upper electrode  34  includes, for example, an electrode layer containing a conductive material having a low resistance such as Pt or Ir, etc., and a ground layer containing Ti. The electrode layer may be made of oxide such as, for example, SrRuO 3 , LaNiO 3 , etc. 
     The portion, of the piezoelectric layer  33 , sandwiched between the lower electrode  32  and the upper electrode  34  serves as a drive region. The drive region overlaps with the pressure compartment  17  as viewed in the Z-axis direction. A non-drive region is formed around the drive region as viewed in the Z-axis direction. The lower electrode  32  and the upper electrode  34  do not overlap with each other at the non-drive region. 
     The liquid ejecting head  10  includes a plurality of lead electrodes  35  coupled to the plurality of lower electrodes  32  electrically. Each of the plurality of lead electrodes  35  is coupled to the corresponding one of the plurality of lower electrodes  32 . The lead electrode  35  extends in the X-axis direction and is wired to reach the inside of the opening  50  of the sealing plate  40 . The lead electrode  35  is electrically coupled to the COF  60  inside the opening  50 . 
     The lead electrode  35  is made of a conductive material having a lower resistance than that of the lower electrode  32 . For example, the lead electrode  35  is a conductive pattern having a layered structure obtained by forming a conductive film made of gold (Au) on the surface of a conductive film made of nichrome (NiCr). 
     The sealing plate  40  is disposed in such a way as to cover the plurality of piezoelectric actuators  31  from the Z2-directional side.  FIG. 4  is a perspective view of the sealing plate  40 .  FIG. 5  is a plan view of the sealing plate  40 . The sealing plate  40  has a rectangular shape as viewed in the Z-axis direction. The sealing plate  40  protects the plurality of piezoelectric actuators  31  and enhances the mechanical strength of the pressure compartment forming substrate  24  and the diaphragm  25 . 
     The sealing plate  40  includes a first surface  41  and a second surface  42 . The first surface  41  and the second surface  42  are at a distance from each other in the Z-axis direction. The first surface  41  is the surface oriented in the Z2 direction. The second surface  42  is the surface oriented in the Z1 direction. The second surface  42  is in contact with the diaphragm  25  as illustrated in  FIG. 3 . The second surface  42  is fixed to the diaphragm  25  by using, for example, an adhesive. 
     The sealing plate  40  has a recessed portion  43  for housing the piezoelectric actuators  31 . The recessed portion  43  is located on both sides with respect to the opening  50  in the X-axis direction. The recessed portion  43  is recessed from the second surface  42 . The recessed portion  43  extends in the Y-axis direction in such a way as to house the plurality of piezoelectric actuators  31  arranged next to one another in the Y-axis direction. 
     The opening  50  goes through the sealing plate  40  in the Z-axis direction. The opening  50  is continuous from the first surface  41  to the second surface  42 . The opening  50  is surrounded and defined by inner wall surfaces  51  to  54 . The inner wall surfaces  51  and  52  are at a distance from each other in the X-axis direction. The inner wall surfaces  53  and  54  are at a distance from each other in the Y-axis direction. 
     The inner wall surfaces  51  and  52  are inclined with respect to the Z-axis direction. The inner wall surfaces  51  and  52  extend in the Y-axis direction. The width W 1  of the opening  50  at the first surface  41  is greater than the width W 2  of the opening  50  at the second surface  42 . The opening width W 1 , W 2  is the length of the opening  50  in the X-axis direction. The length L of the opening  50  at the first surface  41  is equal to the length L of the opening  50  at the second surface  42 . The area size S 1  of the opening  50  at the first surface  41  is larger than the area size S 1  of the opening  50  at the second surface  42 . 
       FIG. 6  is an enlarged cross-sectional view of the opening  50  of the sealing plate  40 . As illustrated in  FIG. 6 , the angle of inclination θ 1  of the inner wall surface  51  with respect to the X-axis direction is an acute angle. For example, the angle of inclination θ 1  of the inner wall surface  51  is 54.7°. The angle of inclination θ 2  of the inner wall surface  52  with respect to the X-axis direction is the same as the angle of inclination θ 1  of the inner wall surface  51  with respect to the X-axis direction. The inner wall surfaces  51  and  52  are line-symmetric with respect to the center line O. 
     The sealing plate  40  is made of a monocrystalline silicon substrate having preferential orientation of ( 100 ) at its surface perpendicular to the Z-axis direction. The monocrystalline silicon substrate is a preferential orientation substrate in which 50% or more of crystal in relation to a whole of crystal is oriented to the first surface  41 . The monocrystalline silicon substrate may be a preferential orientation substrate in which 80% or more of crystal in relation to a whole of crystal is oriented to the first surface  41 . The monocrystalline silicon substrate may be a preferential orientation substrate in which 90% or more of crystal in relation to a whole of crystal is oriented to the first surface  41 . The inner wall surfaces  51  and  52  each having a slope of 54.7° are formed by wet-etching a monocrystalline silicon substrate using a strongly basic aqueous solution such as a potassium hydroxide solution (KOH), etc. By forming a SiO 2  film, it is possible to stop the etching of the silicon substrate by the strongly basic aqueous solution. If the sealing plate  40  is made of a monocrystalline silicon substrate, it is possible to form the inclined surface easily by wet etching. 
     The COF  60  is inserted in the opening  50  and is electrically coupled to the piezoelectric actuator  31  via the lead electrode  35 . The COF  60  includes a flexible wiring board  61  and a driver IC  62 . The flexible wiring board  61  is a wiring board that has flexibility. The flexible wiring board  61  is, for example, an FPC (Flexible Printed Circuit). The flexible wiring board  61  may be, for example, an FFC (Flexible Flat Cable). 
     The flexible wiring board  61  has a plurality of layers. The flexible wiring board  61  may include, for example, a polyimide base material, a copper foil, a gold plating layer, an insulating layer, an adhesive layer, or a solder resist. 
     The flexible wiring board  61  includes a connection portion  63 , a part (a portion)  64 , and another part (another portion)  65 . The connection portion  63  is disposed at the bottom of the opening  50  and is electrically coupled to the lead electrodes  35 . The bottom of the opening  50  is the face that is closer to the second surface  42  of the sealing plate  40  in the Z-axis direction than the opposite face is. The plate-thickness direction of the connection portion  63  is along the Z axis. The connection portion  63  has a predetermined width in the X-axis direction and extends in the Y-axis direction. The connection portion  63  is disposed in such a way as to cover the plurality of lead electrodes  35  from the Z2-directional side. 
     The part  64  of the flexible wiring board  61  is bent from the connection portion  63 . As viewed in the Y1 direction, the part  64  of the flexible wiring board  61  extends obliquely upward from the connection portion  63 . The rising angle θ 3  of the part  64  with respect to the connection portion  63  is an obtuse angle. The part  64  extends in an X2-and-Z2 direction. There is a predetermined clearance between the part  64  and the inner wall surface  52 . The part  64  is located inside the opening  50 . 
     The part  65  of the flexible wiring board  61  is bent from the connection portion  63 . As viewed in the Y1 direction, the part  65  of the flexible wiring board  61  extends obliquely upward from the connection portion  63 . The rising angle θ 4  of the part  65  with respect to the connection portion  63  is an obtuse angle. The part  65  extends toward the opposite side away from the part  64  in the X-axis direction. The part  65  extends in an X1-and-Z2 direction. There is a predetermined clearance between the part  65  and the inner wall surface  51 . The part  65  extends up to the outside of the opening  50 . The part  65  is electrically coupled to a wiring board that is not illustrated. The flexible wiring board  61  is electrically coupled to a wiring board, a relay board, and a connector. 
     The driver IC  62  is mounted on the flexible wiring board  61 . More specifically, the driver IC  62  is mounted on, of the flexible wiring board  61 , the surface oriented toward the inner wall surface  51 . There is a predetermined clearance between the driver IC  62  and the inner wall surface  51 . 
     The driver IC  62  is electrically coupled to the control unit  3  via the flexible wiring board  61 . The driver IC  62  receives a command signal outputted from the control unit  3 . In response to the command signal, the driver IC  62  supplies a drive signal to each piezoelectric actuator  31  to cause the diaphragm  25  to vibrate. 
     The COF  60  is bonded to the diaphragm  25  by an adhesive  81  disposed inside the opening  50 . The adhesive  81  is an example of a first adhesive. The part  64  is bonded to the inner wall surface  52  by the adhesive  81 . The part  65  and the driver IC  62  are bonded to the inner wall surface  51 . The connection portion  63  is bonded to the diaphragm  25  by the adhesive  81 . The adhesive  81  is disposed on the area of the diaphragm  25  between the lead electrodes  35  arranged adjacent to one another in the Y-axis direction. The connection portion  63  is bonded to the diaphragm  25 , with the adhesive  81  applied therebetween. 
     The adhesive  81  is a non-conductive adhesive that does not contain a conductor such as, for example, conductive particles. For example, the adhesive  81  may be a non-conductive adhesive paste (NCP: Non-Conductive Paste) or a non-conductive adhesive film (NCF: Non-Conductive Film). The adhesive  81  may be an anisotropic conductive adhesive in which a plurality of conductive particles is dispersed. The anisotropic conductive adhesive is, for example, an anisotropic conductive film (ACF: Anisotropic Conductive Film) or an anisotropic conductive paste (ACP: Anisotropic Conductive Paste). If the adhesive  81  is a non-conductive adhesive, high-density mounting will be easier as compared with a case where an ACF or an ACP is used. 
     The adhesive  81  is sealed by an adhesive  82  disposed inside the opening  50 . The adhesive  82  is an example of a second adhesive. The COF  60  is bonded indirectly to the pressure compartment forming substrate  24 , with the diaphragm  25  interposed therebetween, in the Z-axis direction. The connection portion  63  disposed inside the opening  50  is sealed by the adhesive  82 . The adhesive  82  may be a potting agent or a sealant. 
     Next, with reference to  FIG. 6 , a method of mounting the COF  60  in the liquid ejecting head  10  will now be explained. Prior to the mounting of the COF  60 , the plurality of piezoelectric actuators  31  is formed by producing, on the pressure compartment forming substrate  24 , a layered structure made up of the diaphragm  25 , the lower electrode  32 , the piezoelectric layer  33 , and the upper electrode  34 , and the lead electrodes  35 . After the plurality of piezoelectric actuators  31  is formed, the sealing plate  40  is mounted over the plurality of piezoelectric actuators  31  by bonding. 
     The sealing plate  40  has the opening  50 . The plurality of lead electrodes  35  is exposed to the inside of the opening  50 . The part  64  of the flexible wiring board  61  is bent from the connection portion  63  at an obtuse angle. The part  65  of the flexible wiring board  61  is also bent from the connection portion  63  at an obtuse angle. Prior to the mounting of the COF  60 , the driver IC  62  is mounted on the part  65  of the flexible wiring board  61 . 
     The adhesive  81  is disposed on the diaphragm  25  and the lead electrodes  35  inside the opening  50 . The COF  60  is inserted into the opening  50  in the Z1 direction. The connection portion  63  is disposed on the diaphragm  25  and the lead electrodes  35  at the bottom of the opening  50 . 
     When the connection portion  63  that is being inserted approaches the second surface  42 , the connection portion  63  comes into contact with the adhesive  81 , and a part of the adhesive  81  is forced to go outward in the X-axis direction. A part of the adhesive  81  moves in the X2 direction into the gap between the part  64  of the flexible wiring board  61  and the inner wall surface  52 . Another part of the adhesive  81  moves in the X1 direction into the gap between the part  65  of the flexible wiring board  61  and the inner wall surface  51  and the gap between the driver IC  62  and the inner wall surface  51 . Still another part of the adhesive  81  stays on the diaphragm  25  and contributes to the bonding of the connection portion  63  and the diaphragm  25  to each other. 
     A tool  91  is inserted into the opening  50  in the Z1 direction. In  FIG. 6 , the tool  91  is shown by broken-line illustration. The tool  91  is a mounting tool. The tool  91  pushes the connection portion  63  in the Z1 direction and applies heat thereto. Therefore, the adhesive  81  is heated to cure, the connection portion  63  becomes bonded to the diaphragm  25 , and the wiring of the COF  60  becomes electrically coupled to the lead electrodes  35 . 
     Next, the tool  91  is taken out of the opening  50 , and then the opening  50  is filled with the adhesive  82 , thereby sealing the connection portion  63  and the lead electrodes  35 . The COF  60  is mounted onto the lead electrodes  35  in this way. 
     In the liquid ejecting head  10  described above, the inner wall surfaces  51  and  52  of the opening  50  are sloped, and the opening width W 1  at the first surface  41  is greater than the opening width W 2  at the second surface  42 . The opening  50  is widest at the first surface  41  and becomes narrower from the first surface  41  toward the second surface  42 , at which it is narrowest. This structure reduces the risk of contact of the tool  91  with the inner wall surface  51 ,  52  when the tool  91  is inserted into the opening  50 . Similarly, this structure reduces the risk of contact of the flexible wiring board  61  and the driver IC  62  with the inner wall surface  51 ,  52  when the COF  60  is inserted into the opening  50 . With the liquid ejecting head  10  described above, the electric coupling of the COF  60  becomes easier. 
     In the liquid ejecting head  10 , as described above, the width W 1  of the opening  50  is greater than the width W 2  of the opening  50 . Therefore, unlike related art, there is no need to bend the part  65  from the connection portion  63  at a right angle. Namely, in the COF  60 , the part  65  is bent from the connection portion  63  at an obtuse angle. Because of this structure, the flexible wiring board  61  is bent at an angle that is gentler than that of related art. Consequently, the risk of occurrence of wire breakage and migration at the bent portion of the flexible wiring board  61  decreases. 
     For example, if the angle of the bent portion of the flexible wiring board  61  is a right angle, the possibility of occurrence of wire breakage and migration will be higher as compared with a structure in which the angle of the bent portion is an obtuse angle as in θ 3 . In this respect, in the liquid ejecting head  10 , since the angle of the bent portion can be made gentler, it is possible to reduce the risk of exposure of wiring Cu caused by cracking of Au plating that covers wires. Since the structure of the liquid ejecting head  10  makes it possible to reduce the risk of occurrence of wire breakage and migration at the bent portion of the flexible wiring board  61 , the reliability of the liquid ejecting head  10  improves. 
     In the liquid ejecting head  10 , the inner wall surfaces  51  and  52  of the opening  50  are sloped, the part  64  is formed on one side with respect to the connection portion  63 , and the part  65  is formed on the opposite side with respect to the connection portion  63 . Because of this structure, even if the adhesive  81  disposed on the Z1-directional side with respect to the connection portion  63  moves to both sides in the X-axis direction, the presence of the parts  64  and  65  prevents the adhesive  81  from entering an inner space on the Z2-directional side with respect to the connection portion  63 . In the liquid ejecting head  10 , it is possible to prevent the adhesive  81  from climbing up into the inner space on the Z2-directional side with respect to the connection portion  63 . Therefore, the adhesive  81  will not get on the tool  91  when the COF  60  is mounted using the tool  91 . 
     Moreover, in the liquid ejecting head  10 , since the bent portion of the flexible wiring board  61  is covered by the adhesive  81 , it is possible to protect the bent portion by the adhesive  81 . For example, of the flexible wiring board  61 , the portion that is not covered by a solder resist may be covered by the adhesive  81 . As described here, it is possible to protect the flexible wiring board  61  by the adhesive  81  that is present inside the opening  50 . Therefore, it is possible to enhance the reliability of electric coupling in the liquid ejecting head  10 . 
     In the liquid ejecting head  10 , since the inner wall surfaces  51  and  52  of the opening  50  are sloped, it is easier to dispose the adhesive  81  near the Z1-side end of the inner wall surface  51  and the Z1-side end of the inner wall surface  52 . For example, as compared with a structure in which the inner wall surfaces of the opening are perpendicular to the X-axis direction, it is easier to dispose the adhesive  81  without a clearance. Therefore, in the liquid ejecting head  10 , the adhesive  81  can be disposed appropriately without being applied excessively. 
     In the liquid ejecting head  10 , the flexible wiring board  61  and the pressure compartment forming substrate  24  are bonded by means of the adhesive  81 . Since the flexible wiring board  61  is electrically bonded by using the adhesive  81 , the reliability of electric coupling improves. 
     In the liquid ejecting head  10 , the adhesive  81 , the connection portion  63 , and the lead electrodes  35  are sealed by the adhesive  82  disposed inside the opening  50 . Since it is possible to protect the adhesive  81 , the connection portion  63 , and the lead electrodes  35  by the adhesive  82 , the reliability of electric coupling in the liquid ejecting head  10  improves. Moreover, since the connection portion  63  and the lead electrodes  35  are protected from moisture, etc. by the adhesive  82 , the life of the connection portion  63  and the lead electrodes  35  becomes longer. 
     In the liquid ejecting head  10 , since it is possible to prevent the adhesive  81  from entering the inner space on the Z2-directional side with respect to the connection portion  63 , even if the adhesive  81  is disposed more roughly as compared with related art, it is possible to mount the COF  60  onto the lead electrodes  35  without impairing the reliability. 
     In the liquid ejecting head  10 , the opening width W 2  at the second surface  42  may be made less than that of related art by adjusting the slope of the inner wall surfaces  51  and  52  of the opening  50 . By this means, it is possible to prevent the contact of the COF  60  with the inner wall surface  51 ,  52  while reducing the opening width W 2 . 
     Moreover, a reduction in the opening width W 2  makes it possible to arrange the rows of the pressure compartments  17  closer to each other in the X-axis direction. The rows of the nozzles N may be arranged closer to each other in the X-axis direction. This makes it possible for the liquid ejecting apparatus  1  to perform high-density printing. 
     Next, with reference to  FIG. 7 , a liquid ejecting head  10 B according to a second embodiment will now be explained.  FIG. 7  is an enlarged cross-sectional view of the opening  50  of the sealing plate  40  of the liquid ejecting head  10 B according to the second embodiment. The liquid ejecting head  10 B according to the second embodiment is different from the liquid ejecting head  10  according to the first embodiment in that, firstly, a plurality of convex portions  85  is formed under the connection portion  63 , and, secondly, the lead electrodes  35  are formed between the connection portion  63  and the plurality of convex portions  85 . In the description of the second embodiment below, the same explanation as that of the first embodiment will not be given. 
     The plurality of convex portions  85  is, for example, formed of the piezoelectric layer. The plurality of convex portions  85  is formed at the same time as the forming of the piezoelectric layer  33  of the piezoelectric actuators  31 . A plurality of concave portions is formed by partially removing the piezoelectric layer by etching the piezoelectric layer. The plurality of convex portions  85  is the piezoelectric layer remaining between the concave portions. These convex portions  85  and concave portions constitute a convex-and-concave shape pattern. A part of the lead electrodes  35  is formed on the convex portions  85 . A part of the lead electrodes  35  may exist between the convex portions  85  in the X-axis direction. 
     The convex portion  85  projects in the Z2 direction with respect to the lower electrode  32 . Each of the plurality of convex portions  85  extends in the Y-axis direction. As viewed in the Z-axis direction, the convex portions  85  are arranged at positions where they overlap with the opening  50 . The plurality of convex portions  85  may be formed in such a way as to project from the pressure compartment forming substrate  24 . The convex-and-concave shape pattern may be provided under the wiring of the pressure compartment forming substrate  24 . 
     The plurality of convex portions  85  may project beyond the second surface  42  of the sealing plate  40  in the Z2 direction. In this case, the connection portion  63  is disposed at a position more distant from the second surface  42  in the Z2 direction. Therefore, it is possible to adjust the gap between the COF  60  and the inner wall surface  51 ,  52 . For example, it is possible to make the gap between the COF  60  and the inner wall surface  51 ,  52  wider. 
     The liquid ejecting head  10 B according to the second embodiment having this structure produces the same operational effects as those of the liquid ejecting head  10  according to the first embodiment. In the liquid ejecting head  10 B, since the plurality of convex portions  85  is provided, it is possible to bond the connection portion  63  and the lead electrodes  35  to each other well. If there is a convex-and-concave shape pattern including the convex portions  85 , stress will concentrate in a desirable way when the connection portion  63  and the lead electrodes  35  are bonded together. Therefore, the reliability of electric coupling improves. 
     If the concave portions are formed under the wiring of the connection portion  63 , a larger amount of the adhesive  81  will be used as compared with a structure in which the concave portions do not exist. In the liquid ejecting head  10 B, since the inner wall surfaces  51  and  52  of the opening  50  are sloped, even if a larger amount of the adhesive  81  is used, it is possible to prevent the vertical climbing of the adhesive  81  and thus possible to electrically couple the connection portion  63  well. Even if a larger amount of the adhesive  81  is used, the risk of adhesion of the adhesive  81  to the tool  91  for mounting decreases. 
     Moreover, in the liquid ejecting head  10 B, it is possible to guide the adhesive  81  by the convex-and-concave shape pattern including the convex portions  85  when the COF  60  is mounted. The guiding makes it easier to dispose the adhesive  81  appropriately. Therefore, it is possible to bond the connection portion  63  to the diaphragm  25  securely. Consequently, it is possible to enhance the reliability of the liquid ejecting head  10 B. 
     Next, with reference to  FIG. 8 , a liquid ejecting head  10 C according to a first modification example will now be explained.  FIG. 8  is a cross-sectional view of the sealing plate  40  of the liquid ejecting head  10 C according to the first modification example. The liquid ejecting head  10 C according to the first modification example is different from the liquid ejecting head  10  according to the first embodiment in that, firstly, the liquid ejecting head  10 C includes, instead of the part  64 , a part  64 B that is longer than the part  64 , and, secondly, a driver IC  66  is mounted on the part  64 B. In the description of the first modification example below, the same explanation as that of the first embodiment will not be given. 
     The liquid ejecting head  10 C includes a COF  60 B. The COF  60 B includes a flexible wiring board  61 B, the driver IC  62 , and the driver IC  66 . The flexible wiring board  61 B includes the connection portion  63 , a part  64 B, and the part  65 . The liquid ejecting head  10 C includes the driver IC  62  mounted on the part  65  and the driver IC  66  mounted on the part  64 B. The part  65  is an example of a first portion. The part  64 B is an example of a second portion. The driver IC  62  is an example of a first integrated circuit. The driver IC  66  is an example of a second integrated circuit. 
     The driver IC  66  is disposed on, of the part  64 B, the surface that is closer to the inner wall surface  52 . The liquid ejecting head  10 C having this structure also produces the same operational effects as those of the liquid ejecting head  10 . In the liquid ejecting head  10 C, since the part  64 B extends up to the outside of the opening  50 , it is possible to prevent the adhesive  81  from entering the inner space on the Z2-directional side with respect to the connection portion  63 . Therefore, the adhesive  81  will not get on the tool  91  when the COF  60 B is mounted using the tool  91 . 
     Next, with reference to  FIG. 9 , a liquid ejecting head  10 D according to a second modification example will now be explained.  FIG. 9  is a cross-sectional view of the sealing plate  40  of the liquid ejecting head  10 D according to the second modification example. The liquid ejecting head  10 D according to the second modification example is different from the liquid ejecting head  10 C according to the first modification example in that the part  64 B and the driver IC  66  are disposed further up to the outside of the opening  50 . 
     The liquid ejecting head  10 D according to the second modification example having this structure also produces the same operational effects as those of the foregoing liquid ejecting head  10 ,  10 C. Moreover, since the driver IC  62  is disposed on one side with respect to the connection portion  63  in the X-axis direction and since the driver IC  66  is disposed on the opposite side with respect thereto, it is possible to support the flexible wiring board  61 B over the diaphragm  25  in a well-balanced manner. 
     Next, with reference to  FIG. 10 , a liquid ejecting head  10 E according to a third modification example will now be explained.  FIG. 10  is a cross-sectional view of a sealing plate  40 B of the liquid ejecting head  10 E according to the third modification example. The liquid ejecting head  10 E is different from the liquid ejecting head  10  according to the first embodiment in that its opening  50 B has a cross-sectional shape different from that of the opening  50 . In the description of the third modification example below, the same explanation as that of the first embodiment will not be given. 
     The liquid ejecting head  10 E includes the sealing plate  40 B in which the opening  50 B is formed. The opening  50 B has inner wall surfaces  51  and  55  that are at a distance from each other in the X-axis direction. The inner wall surface  51  is sloped. The inner wall surface  55  is along the Z axis. More specifically, the inner wall surface  51 , which is closer to the part  65 , is an inclined surface, and the inner wall surface  55 , which is closer to the part  64  that is shorter than the part  65 , extends in the X-axis direction. The liquid ejecting head  10 E according to the third modification example having this structure also produces the same operational effects as those of the liquid ejecting head  10  according to the first embodiment. 
     Next, with reference to  FIG. 11 , a liquid ejecting head  10 F according to a fourth modification example will now be explained.  FIG. 11  is a cross-sectional view of a sealing plate  40 C of the liquid ejecting head  10 F according to the fourth modification example. The liquid ejecting head  10 F is different from the liquid ejecting head  10  according to the first embodiment in that its opening  50 C has a cross-sectional shape different from that of the opening  50 . 
     The liquid ejecting head  10 F includes the sealing plate  40 C in which the opening  50 C is formed. The opening  50 C has inner wall surfaces  51 B and  52 B, which are inclined with respect to the X-axis direction, inner wall surfaces  56  and  58 , which are along the X axis, and inner wall surfaces  57  and  59 , which are along the Z axis. The inner wall surface  51 B is sloped, likewise the inner wall surface  51  according to the first embodiment. The inner wall surface  51 B extends obliquely up to a position that is approximately the half of the thickness of the sealing plate  40 C in the Z-axis direction. The inner wall surface  56  extends in the X1 direction from the Z1-side end of the inner wall surface  51 B. The inner wall surface  57  extends in the Z2 direction from the X1-side end of the inner wall surface  56 . 
     The inner wall surface  52 B is sloped, likewise the inner wall surface  52  according to the first embodiment. The inner wall surface  52 B extends obliquely up to a position that is approximately the half of the thickness of the sealing plate  40 C in the Z-axis direction. The inner wall surface  58  extends in the X2 direction from the Z1-side end of the inner wall surface  52 B. The inner wall surface  59  extends in the Z2 direction from the X2-side end of the inner wall surface  58 . 
     Among the inner wall surfaces surrounding and defining the opening  50 C, the inner wall surfaces  56  and  58  are step surfaces. As described here, the sealing plate  40 C may have a stepped inner-wall-surface structure. The liquid ejecting head  10 F according to the fourth modification example having this structure also produces the same operational effects as those of the liquid ejecting head  10  according to the first embodiment. 
     The foregoing embodiment merely discloses typical examples of the present disclosure. The scope of the present disclosure is not limited to the foregoing embodiment. Various modifications and additions, etc. can be made within a range not departing from the gist of the present disclosure. 
     In the foregoing embodiment, the liquid ejecting apparatus  1  that is a so-called serial-type device configured to reciprocate the carriage  5  on which the liquid ejecting head  10  is mounted has been described to show some examples. However, the present disclosure may be applied to a so-called line-type liquid ejecting apparatus in which the plural nozzles N are arranged throughout the entire width of the medium P. 
     In the foregoing embodiment, the common reservoir  13  is formed in the cover  70 . However, a part of the ink flow passages  11  such as the common reservoir  13  may be formed in the sealing plate  40 . 
     The liquid ejecting apparatus  1  disclosed as examples in the foregoing embodiment can be applied to not only print-only machines but also various kinds of equipment such as facsimiles and copiers, etc. The scope of application of a liquid ejecting apparatus according to the present disclosure is not limited to printing. For example, a liquid ejecting apparatus that ejects a colorant solution can be used as an apparatus for manufacturing a color filter of a display device such as a liquid crystal display panel. A liquid ejecting apparatus that ejects a solution of a conductive material can be used as a manufacturing apparatus for forming wiring lines and electrodes of a wiring substrate. A liquid ejecting apparatus that ejects a solution of a living organic material can be used as a manufacturing apparatus for, for example, production of biochips. 
     The actuator  31  disclosed as examples in each embodiment may be used for devices such as, for example, an ultrasonic wave transmitter, an ultrasonic motor, a piezoelectric transformer, a piezoelectric speaker, a piezoelectric pump, a pressure-electricity converter, and the like.