JP2018103533A - Liquid injection head and liquid injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress breakage of piezoelectric layer constituting a piezoelectric element.SOLUTION: A liquid injection head comprises: a pressure chamber substrate formed with pressure chambers; diaphragms being formed on a surface of the pressure chamber substrate and constituting wall surfaces of the pressure chambers; and piezoelectric elements formed on surfaces of the diaphragms. Each piezoelectric element includes: a first electrode and a second electrode; and a piezoelectric layer between the first electrode and the second electrode. A boundary portion being a portion overlapping with a circumference of the second electrode out of the first electrode is positioned in a region outside the pressure chamber in a plan view. In a region overlapping with the boundary portion in the plan view out of the pressure chamber substrate, a removed portion where the pressure chamber substrate is removed is formed independently from the pressure chamber.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a technique for ejecting a liquid such as ink using a piezoelectric element.

  2. Description of the Related Art Conventionally, a liquid ejecting head that ejects liquid in a pressure chamber from a nozzle by vibrating a diaphragm that constitutes each wall surface of a plurality of pressure chambers with a piezoelectric element has been proposed. For example, Patent Document 1 discloses a piezoelectric element in which a piezoelectric layer is formed between a first electrode individually formed for each piezoelectric element and a second electrode extending over a plurality of piezoelectric elements.

Japanese Patent Application Laid-Open No. 2014-83797

  In the piezoelectric layer, stress is generated at the boundary between the region that is deformed by the piezoelectric effect corresponding to the electric field between the first electrode and the second electrode (hereinafter referred to as “active portion”) and the other inactive portion. easy. In the configuration of Patent Document 1, deformation of the piezoelectric layer due to stress in the vicinity of the boundary between the active portion and the inactive portion of the piezoelectric layer is constrained by the diaphragm, and as a result, the piezoelectric layer may be damaged. . In view of the above circumstances, a preferred aspect of the present invention aims to suppress the breakage of the piezoelectric layer constituting the piezoelectric element.

<Aspect 1>
In order to solve the above problems, a liquid jet head according to a preferred aspect (aspect 1) of the present invention includes a pressure chamber substrate in which a pressure chamber is formed, and the pressure chamber substrate formed on the surface of the pressure chamber substrate. And a piezoelectric element formed on a surface of the diaphragm, wherein the piezoelectric element includes a first electrode, a second electrode, the first electrode, and the second electrode. A boundary portion that is a portion of the first electrode that overlaps a peripheral edge of the second electrode is located in a region outside the pressure chamber in plan view, and the pressure chamber In a region of the substrate that overlaps the boundary portion in plan view, a removal portion from which the pressure chamber substrate is removed is formed independently of the pressure chamber. In the above aspect, the portion corresponding to the removal portion of the vibration plate is displaced in conjunction with the deformation of the portion near the boundary portion of the piezoelectric layer, so that the stress inside the piezoelectric layer is displaced by the vibration plate. Is alleviated by Therefore, it is possible to reduce the possibility that the piezoelectric layer is damaged due to the stress in the vicinity of the boundary portion of the piezoelectric layer.
<Aspect 2>
In a preferred example of the first aspect (the second aspect), a first pressure chamber and a second pressure chamber are formed as the pressure chambers on the pressure chamber substrate, and the first piezoelectric element corresponding to the first pressure chamber and the first pressure chamber are formed. A second piezoelectric element corresponding to two pressure chambers as the piezoelectric element, and the boundary portion of the first electrode of the first piezoelectric element includes the first pressure chamber and the second pressure chamber in plan view. The removal portion, which is located between the first pressure chamber and the second pressure chamber, is formed between the first pressure chamber and the second pressure chamber in plan view. In the above aspect, the removal portion is formed between the first pressure chamber and the second pressure chamber. Therefore, as compared with the configuration in which the removal portion is formed in a region other than between the first pressure chamber and the second pressure chamber, the liquid ejecting head in the direction intersecting the arrangement of the first pressure chamber and the second pressure chamber. There is an advantage that the size is reduced.
<Aspect 3>
In a preferred example of the aspect 2 (aspect 3), each of the first pressure chamber and the second pressure chamber includes a first portion and a second portion having a narrower width than the first portion, and the removing unit Is formed between the second part of the first pressure chamber and the second part of the second pressure chamber. In the above aspect, the removal portion is formed between the second portion of the first pressure chamber and the second portion of the second pressure chamber. Therefore, there is an advantage that it is easy to ensure the thickness of the wall portion between the first pressure chamber or the second pressure chamber and the removal portion and the area of the removal portion.
<Aspect 4>
In a preferred example (aspect 4) of any one of the aspects 1 to 3, the width of the removal portion is narrower than the width of the pressure chamber. In the above aspect, since the width of the removal portion is narrower than the width of the pressure chamber, there is an advantage that damage (for example, cracks) due to excessive deformation of the portion of the diaphragm corresponding to the removal portion can be suppressed.
<Aspect 5>
In a preferred example (Aspect 5) of Aspect 4, the width of the removal portion is not more than half of the width of the pressure chamber. In the above aspect, since the width of the removal portion is less than half of the width of the pressure chamber, the effect of suppressing breakage (for example, cracks) due to excessive deformation of the portion corresponding to the removal portion of the diaphragm is particularly remarkable. It is.
<Aspect 6>
A liquid ejecting apparatus according to a preferred aspect (aspect 6) of the present invention includes the liquid ejecting head according to each aspect exemplified above. A good example of the liquid ejecting apparatus is a printing apparatus that ejects ink, but the use of the liquid ejecting apparatus according to the present invention is not limited to printing.

1 is a configuration diagram of a liquid ejecting apparatus according to a first embodiment. FIG. 3 is an exploded perspective view of a liquid ejecting head. FIG. 3 is a cross-sectional view of the liquid jet head (a cross-sectional view taken along line III-III in FIG. 2). It is a top view of a plurality of piezoelectric elements. It is sectional drawing of the VV line in FIG. It is sectional drawing of the VI-VI line in FIG. It is a top view of a plurality of piezoelectric elements in a 2nd embodiment. It is a top view of a plurality of piezoelectric elements in a 3rd embodiment.

<First Embodiment>
FIG. 1 is a configuration diagram illustrating a liquid ejecting apparatus 100 according to the first embodiment of the invention. The liquid ejecting apparatus 100 according to the first embodiment is an ink jet printing apparatus that ejects ink, which is an example of a liquid, onto a medium (ejection target) 12. The medium 12 is typically printing paper, but a printing target of an arbitrary material such as a resin film or a fabric can be used as the medium 12. As illustrated in FIG. 1, the liquid ejecting apparatus 100 is provided with a liquid container 14 that stores ink. For example, a cartridge that can be attached to and detached from the liquid ejecting apparatus 100, a bag-shaped ink pack formed of a flexible film, or an ink tank that can be refilled with ink is used as the liquid container 14.

  As illustrated in FIG. 1, the liquid ejecting apparatus 100 includes a control unit 20, a transport mechanism 22, a moving mechanism 24, and a liquid ejecting head 26. The control unit 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and comprehensively controls each element of the liquid ejecting apparatus 100. The transport mechanism 22 transports the medium 12 in the Y direction under the control of the control unit 20.

  The moving mechanism 24 reciprocates the liquid jet head 26 in the X direction under the control of the control unit 20. The X direction is a direction that intersects (typically orthogonal) the Y direction in which the medium 12 is conveyed. The moving mechanism 24 of the first embodiment includes a substantially box-shaped transport body 242 (carriage) that houses the liquid ejecting head 26 and a transport belt 244 to which the transport body 242 is fixed. A configuration in which a plurality of liquid ejecting heads 26 are mounted on the transport body 242 or a configuration in which the liquid container 14 is mounted on the transport body 242 together with the liquid ejecting head 26 may be employed.

  The liquid ejecting head 26 ejects ink supplied from the liquid container 14 to the medium 12 from a plurality of nozzles (ejection holes) under the control of the control unit 20. In parallel with the transport of the medium 12 by the transport mechanism 22 and the reciprocating reciprocation of the transport body 242, each liquid ejecting head 26 ejects ink onto the medium 12, thereby forming a desired image on the surface of the medium 12. . A direction perpendicular to the XY plane (for example, a plane parallel to the surface of the medium 12) is hereinafter referred to as a Z direction. The ink ejection direction (typically the vertical direction) by each liquid ejection head 26 corresponds to the Z direction.

  2 is an exploded perspective view of the liquid jet head 26, and FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2 (a cross section parallel to the XZ plane). As illustrated in FIGS. 2 and 3, the liquid ejecting head 26 includes a substantially rectangular channel substrate 32 that is long in the Y direction. On the negative surface of the flow path substrate 32 in the Z direction, a pressure chamber substrate 34, a diaphragm 36, a plurality of piezoelectric elements 38, a casing portion 42, and a sealing body 44 are installed. On the other hand, a nozzle plate 46 and a vibration absorber 48 are installed on the positive side surface in the Z direction of the flow path substrate 32. Each element of the liquid jet head 26 is generally a plate-like member that is long in the Y direction, similarly to the flow path substrate 32, and is bonded to each other using, for example, an adhesive.

  As illustrated in FIG. 2, the nozzle plate 46 is a plate-like member on which a plurality of nozzles N arranged in the Y direction are formed. Each nozzle N is a through hole through which ink passes. The flow path substrate 32, the pressure chamber substrate 34, and the nozzle plate 46 are formed, for example, by processing a silicon (Si) single crystal substrate by a semiconductor manufacturing technique such as etching. However, the material and manufacturing method of each element of the liquid jet head 26 are arbitrary.

  The flow path substrate 32 is a plate-like member for forming an ink flow path. As illustrated in FIGS. 2 and 3, the channel substrate 32 is formed with an opening 322, a supply channel 324, and a communication channel 326. The opening 322 is a through hole formed in a long shape along the Y direction in a plan view (that is, viewed from the Z direction) so as to be continuous over the plurality of nozzles N. On the other hand, the supply flow path 324 and the communication flow path 326 are through holes formed individually for each nozzle N. In addition, as illustrated in FIG. 3, a relay flow path 328 that extends across a plurality of supply flow paths 324 is formed on the surface of the flow path substrate 32 on the positive side in the Z direction. The relay channel 328 is a channel that connects the opening 322 and the plurality of supply channels 324.

  The housing portion 42 is a structure manufactured by, for example, injection molding of a resin material, and is fixed to the negative surface of the flow path substrate 32 in the Z direction. As illustrated in FIG. 3, the housing portion 42 is formed with a housing portion 422 and an introduction port 424. The accommodating portion 422 is a concave portion having an outer shape corresponding to the opening portion 322 of the flow path substrate 32, and the introduction port 424 is a through hole communicating with the accommodating portion 422. As understood from FIG. 3, a space in which the opening 322 of the flow path substrate 32 and the accommodating portion 422 of the housing portion 42 communicate with each other functions as a liquid storage chamber (reservoir) SR. Ink supplied from the liquid container 14 and passing through the inlet 424 is stored in the liquid storage chamber SR.

  The vibration absorber 48 is an element for absorbing pressure fluctuations in the liquid storage chamber SR, and includes, for example, a flexible sheet member (compliance substrate) that can be elastically deformed. Specifically, the Z direction of the flow path substrate 32 is configured such that the opening 322 of the flow path substrate 32, the relay flow path 328, and the plurality of supply flow paths 324 are closed to form the bottom surface of the liquid storage chamber SR. A vibration absorber 48 is installed on the surface of the positive side.

  As illustrated in FIGS. 2 and 3, the pressure chamber substrate 34 is a plate-like member in which a plurality of pressure chambers SC corresponding to different nozzles N are formed. The plurality of pressure chambers SC are arranged along the Y direction. Each pressure chamber SC (cavity) is a long opening along the X direction in plan view. The end of the pressure chamber SC on the negative side in the X direction overlaps with one supply channel 324 of the flow path substrate 32 in a plan view, and the end of the pressure chamber SC on the positive side in the Y direction in the plan view. It overlaps with one communication channel 326 of 32.

A diaphragm 36 is installed on the surface of the pressure chamber substrate 34 opposite to the flow path substrate 32. The diaphragm 36 is a plate-like member that can vibrate elastically. For example, the vibration plate 36 can be formed by laminating an elastic film formed of an elastic material such as silicon oxide (SiO ₂ ) and an insulating film formed of an insulating material such as zirconium oxide (ZrO ₂ ).

  As understood from FIG. 3, the flow path substrate 32 and the vibration plate 36 face each other with an interval inside each pressure chamber SC. The pressure chamber SC is a space that is located between the flow path substrate 32 and the vibration plate 36 and applies pressure to the ink filled in the pressure chamber SC. The ink stored in the liquid storage chamber SR is branched from the relay flow channel 328 to each supply flow channel 324 and supplied and filled in the plurality of pressure chambers SC in parallel. As understood from the above description, the diaphragm 36 constitutes the wall surface (specifically, the upper surface) of the pressure chamber SC.

  As illustrated in FIGS. 2 and 3, a plurality of piezoelectric elements 38 corresponding to different nozzles N (or pressure chambers SC) are installed on the surface of the diaphragm 36 on the side opposite to the pressure chambers SC. . Each piezoelectric element 38 is a passive element that is deformed by supplying a drive signal. The plurality of piezoelectric elements 38 are arranged in the Y direction so as to correspond to the plurality of pressure chambers SC. When the vibration plate 36 vibrates in conjunction with the deformation of the piezoelectric element 38, the pressure in the pressure chamber SC fluctuates, so that the ink filled in the pressure chamber SC is ejected through the communication channel 326 and the nozzle N. Is done.

  2 and 3 is a structure that protects the plurality of piezoelectric elements 38 and reinforces the mechanical strength of the pressure chamber substrate 34 and the diaphragm 36. For example, the sealing body 44 is bonded to the surface of the diaphragm 36. It is fixed with an agent. A plurality of piezoelectric elements 38 are accommodated inside a concave portion formed on the surface of the sealing body 44 facing the diaphragm 36.

  As illustrated in FIG. 3, for example, a wiring substrate 50 is bonded to the surface of the vibration plate 36 (or the surface of the pressure chamber substrate 34). The wiring board 50 is a mounting component on which a plurality of wirings (not shown) for electrically connecting the control unit 20 or the power supply circuit (not shown) and the liquid jet head 26 are formed. For example, a flexible wiring board 50 such as FPC (Flexible Printed Circuit) or FFC (Flexible Flat Cable) is preferably employed.

  A specific structure of the plurality of piezoelectric elements 38 will be described in detail below. 4 is a plan view of the plurality of piezoelectric elements 38, and FIG. 5 is a cross-sectional view taken along line VV in FIG. 4 and 5, the sealing body 44 is omitted for convenience.

  As illustrated in FIGS. 4 and 5, a plurality of first electrodes 60, piezoelectric layers 70, and second electrodes 80 are formed on the surface of the diaphragm 36. The first electrode 60 is an individual electrode formed individually for each pressure chamber SC (or for each piezoelectric element 38), and the second electrode 80 is continuous over a plurality of pressure chambers SC (or a plurality of piezoelectric elements 38). It is a common electrode. The drive signal generated by the control unit 20 is individually supplied to each of the plurality of first electrodes 60, and a predetermined voltage (for example, a reference voltage serving as a reference for the voltage of the drive signal) is supplied to the second electrode 80. In addition, although the material of each 1st electrode 60 and the 2nd electrode 80 is arbitrary, the low resistance conductive material which contains platinum (Pt) etc. is suitable, for example. For forming the first electrode 60 and the second electrode 80, a known film forming technique such as sputtering and a processing technique such as photolithography and etching are preferably used.

  As illustrated in FIG. 4, each of the plurality of first electrodes 60 in the first embodiment includes an electrode part 62 and a wiring part 64. The electrode part 62 is a belt-like electrode extending linearly along the X direction. The electrode parts 62 for each pressure chamber SC are arranged in the Y direction at intervals from each other so as to correspond to the arrangement of the plurality of pressure chambers SC. The electrode part 62 of the first embodiment is formed inside the pressure chamber SC in plan view. That is, the peripheral edge of the electrode portion 62 is located inside the inner peripheral edge of the pressure chamber SC in plan view.

  The wiring part 64 of each first electrode 60 is a wiring for electrically connecting the electrode part 62 of the first electrode 60 to each wiring of the wiring board 50. The wiring part 64 of the first embodiment is configured to include a lead part 642 and a conduction part 644. The lead portion 642 is continuous with the end portion on the positive side in the X direction of the electrode portion 62, and the conduction portion 644 is continuous with the lead portion 642. Specifically, the lead-out portion 642 of the first embodiment is formed in a shape that protrudes to the positive side in the Y direction in plan view from the peripheral edge (that is, the long side) extending along the X direction in the electrode portion 62. The

  As understood from FIG. 4, the lead-out portion 642 is formed so as to straddle the long side L along the X direction in the inner periphery of the pressure chamber SC in plan view. That is, the lead-out part 642 continues from the inside to the outside of the pressure chamber SC across the long side L of the pressure chamber SC in plan view. As understood from the above description, the wiring part 64 for electrically connecting the electrode part 62 to the wiring board 50 in the first embodiment is a short side extending in the Y direction among the inner peripheral edges of the pressure chamber SC. (That is, it does not straddle the end of the pressure chamber SC).

  As illustrated in FIG. 4, the conduction portion 644 extends from the end portion of the lead-out portion 642 located outside the pressure chamber SC to the positive side in the X direction (the side opposite to the electrode portion 62). The conducting portion 644 of the first embodiment is located outside the pressure chamber SC (specifically, between a pair of pressure chambers SC adjacent to each other in the Y direction) in plan view.

  As illustrated in FIGS. 4 and 5, the piezoelectric layer 70 is formed on the surface of the diaphragm 36 on which the plurality of first electrodes 60 are formed. The material or manufacturing method of the piezoelectric layer 70 is arbitrary. For example, the piezoelectric layer 70 can be formed by forming a piezoelectric material such as lead zirconate titanate by a known film formation technique such as sputtering. It is. The piezoelectric layer 70 of the first embodiment extends along the Y direction so as to be continuous over the plurality of pressure chambers SC in plan view, and covers the electrode portions 62 of the plurality of first electrodes 60. Specifically, the piezoelectric layer 70 is formed in a strip shape having a lateral width that exceeds the entire length of the pressure chamber SC in the X direction. That is, the plurality of pressure chambers SC are included in a region where the piezoelectric layer 70 is formed in a plan view.

  As illustrated in FIG. 4, a notch 72 (slit) that is long in the Y direction is formed in the gap between the pair of electrode portions 62 adjacent to each other in plan view in the piezoelectric layer 70. . Each notch 72 is a through-hole or a bottomed hole formed in the piezoelectric layer 70, and is a portion with reduced rigidity as compared with other portions. In addition, a configuration in which the cutout portion 72 is omitted (a configuration in which the piezoelectric layer 70 is continuous in a band shape over the plurality of piezoelectric elements 38) and a configuration in which the piezoelectric layers 70 are separately formed for each piezoelectric element 38 are provided. Can be employed.

  As illustrated in FIGS. 4 and 5, the second electrode 80 is formed on the surface of the piezoelectric layer 70. As described above, the second electrode 80 extends along the Y direction so as to be continuous over the plurality of pressure chambers SC in plan view, and overlaps the electrode portions 62 of the plurality of first electrodes 60 in plan view. As illustrated in FIG. 5, the piezoelectric layer 70 is sandwiched between the first electrode 60 (electrode part 62) and the second electrode 80. A region where the first electrode 60 and the second electrode 80 overlap in a plan view with the piezoelectric layer 70 interposed therebetween functions as the piezoelectric element 38. That is, a plurality of piezoelectric elements 38 formed by stacking the first electrode 60 (lower electrode), the piezoelectric layer 70, and the second electrode 80 (upper electrode) are spaced apart from each other in the Y direction. Arranged on the surface of Each piezoelectric element is caused by the action of an electric field corresponding to the voltage difference between the drive signal supplied from the control unit 20 to the first electrode 60 via the wiring portion 64 and the reference voltage supplied from the control unit 20 to the second electrode 80. The piezoelectric layer 70 of the element 38 is displaced. As the pressure in the pressure chamber SC fluctuates due to the vibration of the vibration plate 36 in conjunction with the displacement of the piezoelectric layer 70, the ink filled in the pressure chamber SC passes through the communication channel 326 and is ejected from the nozzle N to the outside. Is done. Since notches 72 are formed in the gaps between the piezoelectric elements 38 adjacent to each other in the X direction in the piezoelectric layer 70, propagation of vibrations among the plurality of piezoelectric elements 38 is suppressed.

  The second electrode 80 of the first embodiment extends in a band shape along the Y direction with a narrower width than the piezoelectric layer 70 and is included in a region where the piezoelectric layer 70 is formed in a plan view. Specifically, in the range from the negative edge Ea1 in the X direction to the positive edge Ea2 in the piezoelectric layer 70, the negative edge Eb1 in the X direction and the positive edge in the second electrode 80. Eb2 is located.

  As understood from FIG. 4, the wiring portion 64 of the first electrode 60 is formed so as to straddle the peripheral edge Eb2 of the second electrode 80 in a plan view. That is, the wiring part 64 extends in the X direction across the peripheral edge Eb2 from the inside to the outside of the region where the second electrode 80 is formed. Therefore, the first electrode 60 of the first embodiment includes a portion (hereinafter referred to as “boundary portion”) 66 that overlaps the peripheral edge Eb2 of the second electrode 80. Specifically, a part of the conducting part 644 in the wiring part 64 of the first electrode 60 (a part overlapping the peripheral edge Eb2 of the second electrode 80 in plan view) corresponds to the boundary part 66. The boundary 66 of each first electrode 60 is located outside each pressure chamber SC in plan view. Specifically, each boundary portion 66 is located in a gap between a pair of pressure chambers SC (illustrated as a first pressure chamber and a second pressure chamber) adjacent to each other in the Y direction. That is, the boundary portion 66 is formed between the first pressure chamber and the second pressure chamber in the Y direction.

  6 is a cross-sectional view taken along line VI-VI in FIG. As illustrated in FIGS. 4 and 6, the pressure chamber substrate 34 of the first embodiment is formed with a plurality of removal portions 342 corresponding to different piezoelectric elements 38 in addition to the plurality of pressure chambers SC described above. The Each of the plurality of removal portions 342 is a space that penetrates the pressure chamber substrate 34 (that is, an opening formed by partial removal of the pressure chamber substrate 34). The flow path substrate 32 and the vibration plate 36 face each other with an interval inside each removal portion 342.

  As illustrated in FIGS. 4 and 6, the removal portion 342 is formed in a region of the pressure chamber substrate 34 that overlaps the boundary portion 66 of each first electrode 60 in plan view. That is, the boundary part 66 is located inside the removal part 342 in plan view. That is, the removal unit 342 is formed between the first pressure chamber and the second pressure chamber in the Y direction. The removing unit 342 of the first embodiment is a space independent of the pressure chamber SC. That is, the removal unit 342 and the pressure chamber SC do not communicate with each other. Accordingly, ink is not supplied to the removing unit 342. As illustrated in FIG. 6, the surplus of the adhesive 344 used for joining the flow path substrate 32 and the pressure chamber substrate 34 flows into the removal portion 342.

  As can be understood from FIG. 4, the length (the dimension in the X direction) of the removal portion 342 is larger than the width Wa. Further, the width Wa (dimension in the Y direction) of the removing portion 342 is narrower than the width Wb of the pressure chamber SC. Specifically, the width Wa of the removing unit 342 is less than or equal to half the width Wb of the pressure chamber SC. For example, the width Wb of the pressure chamber SC is about 70 μm, and the width Wa of the removal portion 342 is 35 μm or less.

  The range of the first electrode 60 on the electrode portion 62 side when viewed from the boundary portion 66 (the portion on the negative side in the X direction when viewed from the peripheral edge Eb2) is opposed to the second electrode 80 with the piezoelectric layer 70 interposed therebetween. The piezoelectric layer 70 can be deformed according to the potential difference between the first electrode 60 and the second electrode 80. On the other hand, since the second electrode 80 does not exist in the first electrode 60 in the range opposite to the electrode portion 62 when viewed from the boundary portion 66 (the portion on the positive side in the X direction when viewed from the peripheral edge Eb2), The piezoelectric layer 70 is not deformed. That is, the boundary portion 66 corresponds to a boundary between a deformable portion (active portion) and a non-deformable portion (inactive portion) of the piezoelectric layer 70. There is a tendency that significant stress tends to occur at the boundary between the active part and the inactive part.

  In a configuration in which the removal portion 342 is not formed (hereinafter referred to as “proportional”), the piezoelectric layer 70 tends to be displaced in a state where it is restrained by the vibration plate 36. Therefore, significant stress is generated in the vicinity of the boundary portion 66 in the piezoelectric layer 70, and as a result, the piezoelectric layer 70 may be damaged. In contrast to the comparative example, in the first embodiment, the removal portion 342 is formed in a region of the pressure chamber substrate 34 that overlaps the boundary portion 66. Therefore, when a portion of the piezoelectric layer 70 near the boundary portion 66 is deformed, a portion of the diaphragm 36 inside the removing portion 342 is displaced. That is, the stress inside the piezoelectric layer 70 is relaxed (specifically, absorbed or dispersed) by the displacement of the diaphragm 36. Therefore, according to the first embodiment, there is an advantage that the possibility that the piezoelectric layer 70 is damaged due to the stress in the vicinity of the boundary portion 66 in the piezoelectric layer 70 is reduced.

  In the first embodiment, the width Wa of the removing portion 342 is narrower than the width Wb of the pressure chamber SC. Therefore, excessive deformation of the portion corresponding to the removing portion 342 in the vibration plate 36 (and consequently breakage such as cracks in the vibration plate 36) is suppressed. Particularly in the first embodiment, since the width Wa of the removing portion 342 is less than or equal to half of the width Wb of the pressure chamber, the effect that the excessive deformation of the diaphragm 36 can be suppressed is particularly remarkable.

Second Embodiment
A second embodiment of the present invention will be described. In addition, about the element which an effect | action or function is similar to 1st Embodiment in each structure illustrated below, the code | symbol used by description of 1st Embodiment is diverted, and each detailed description is abbreviate | omitted suitably.

  FIG. 7 is a plan view of the plurality of piezoelectric elements 38 in the second embodiment, and corresponds to FIG. 4 in the first embodiment. As illustrated in FIG. 7, in the second embodiment, each of the plurality of pressure chambers SC includes a first portion P1 and a second portion P2. The second portion P2 is a portion of the pressure chamber SC that is located on the positive side in the X direction when viewed from the first portion P1, and has a smaller width (dimension in the Y direction) than the first portion P1. Therefore, between a pair of pressure chambers SC adjacent to each other in the Y direction (exemplification of the first pressure chamber and the second pressure chamber), the interval between the second portions P2 is wider than the interval between the first portions P1.

  As illustrated in FIG. 7, the boundary 66 that overlaps the peripheral edge Eb <b> 2 of the second electrode 80 in the first electrode 60 is located between the second portions P <b> 2 in the pressure chambers SC adjacent to each other in the Y direction. Similar to the first embodiment, the removal portion 342 is formed in a region of the pressure chamber substrate 34 that overlaps the boundary portion 66 in plan view. Therefore, as can be understood from FIG. 7, the removal portion 342 is formed between the second portions P <b> 2 in the pressure chambers SC adjacent to each other in the Y direction in the pressure chamber substrate 34. The shape and dimensions of the removal unit 342 are the same as those in the first embodiment. For example, the width Wa (dimension in the Y direction) of the removing portion 342 is narrower than the width Wb of the pressure chamber SC. Specifically, the width Wa of the removing unit 342 is less than or equal to half the width Wb of the pressure chamber SC.

  In the second embodiment, the same effect as in the first embodiment is realized. In the second embodiment, the removal portion 342 is formed between the second portions P2 of the pressure chambers SC. Therefore, as compared with the first embodiment in which the width of the pressure chamber SC is constant over the entire length, the wall thickness between each pressure chamber SC and the removal portion 342 and the area of the removal portion 342 can be easily secured. Is

<Third Embodiment>
FIG. 8 is a plan view of a plurality of piezoelectric elements 38 in the third embodiment, and corresponds to FIG. 4 in the first embodiment. As illustrated in FIG. 8, the wiring portion 64 of the first electrode 60 in the third embodiment extends linearly from the electrode portion 62 of the first electrode 60 to the positive side in the X direction. Therefore, the boundary 66 that overlaps the peripheral edge Eb2 of the second electrode 80 in the first electrode 60 is located on the positive side in the X direction when viewed from each pressure chamber SC. A removal portion 342 is formed in a region of the pressure chamber substrate 34 that overlaps the boundary portion 66 in plan view. Specifically, as will be understood from FIG. 8, the removal portion 342 is formed on the positive side in the X direction when viewed from each pressure chamber SC in the pressure chamber substrate 34. That is, in the first embodiment and the second embodiment, the removal portion 342 and the boundary portion 66 are located between the pressure chambers SC adjacent to each other in the Y direction, whereas in the third embodiment, each pressure chamber. SC, the removal unit 342, and the boundary unit 66 are arranged in the X direction. Note that the shape and dimensions of the removal unit 342 are the same as those in the first embodiment. For example, the width Wa (dimension in the Y direction) of the removing portion 342 is narrower than the width Wb of the pressure chamber SC. Specifically, the width Wa of the removing unit 342 is less than or equal to half the width Wb of the pressure chamber SC.

  In the third embodiment, the same effect as in the first embodiment is realized. In the first and second embodiments, the removal portion 342 is formed between the pressure chambers SC, whereas in the third embodiment, the removal portion 342 needs to be formed between the pressure chambers SC. Absent. Therefore, according to the third embodiment, the interval between the pressure chambers SC in the Y direction can be reduced as compared with the first embodiment and the second embodiment (as a result, a plurality of pressure chambers SC can be arranged with high density). There is an advantage. On the other hand, in the first embodiment and the second embodiment, since the removal portion 342 is formed between the pressure chambers, the size of the liquid ejecting head 26 in the X direction is reduced compared to the third embodiment. There are advantages.

  By the way, the region in the vicinity of the long side L of the pressure chamber SC in the diaphragm 36 is more easily deformed than the region in the vicinity of the short side of the pressure chamber SC. In the first embodiment and the second embodiment, the wiring part 64 (leading part 642) of the first electrode 60 is formed so as to straddle the long side L of the pressure chamber SC in plan view. Therefore, compared with the configuration of the third embodiment in which the first electrode 60 is formed so as to straddle the short side of the pressure chamber SC, the stress generated in the region corresponding to the lead portion 642 in the piezoelectric layer 70 is relieved. As a result, there is an advantage that damage to the piezoelectric layer 70 can be suppressed.

<Modification>
Each form illustrated above can be variously modified. Specific modes of modifications that can be applied to the above-described embodiments are exemplified below. Note that two or more aspects arbitrarily selected from the following examples can be appropriately combined as long as they do not contradict each other.

(1) The planar shapes of the pressure chamber SC and the piezoelectric element 38 are not limited to the illustrations (rectangular shapes) of the above-described embodiments. For example, in a configuration in which a single crystal substrate of silicon (Si) is used as the pressure chamber substrate 34, the crystal plane is actually reflected in the planar shape of the pressure chamber SC.

(2) In each of the above-described embodiments, the serial type liquid ejecting apparatus 100 that reciprocates the transport body 242 on which the liquid ejecting head 26 is mounted is exemplified. The present invention can also be applied to an injection device.

(3) The liquid ejecting apparatus 100 exemplified in the above-described embodiments can be employed in various apparatuses such as a facsimile apparatus and a copying machine, in addition to apparatuses dedicated to printing. However, the use of the liquid ejecting apparatus of the present invention is not limited to printing. For example, a liquid ejecting apparatus that ejects a solution of a coloring material is used as a manufacturing apparatus that forms a color filter of a liquid crystal display device. Further, a liquid ejecting apparatus that ejects a solution of a conductive material is used as a manufacturing apparatus that forms wiring and electrodes of a wiring board.

DESCRIPTION OF SYMBOLS 100 ... Liquid ejecting apparatus, 12 ... Medium, 14 ... Liquid container, 20 ... Control unit, 22 ... Conveyance mechanism, 24 ... Moving mechanism, 26 ... Liquid ejecting head, 32 ... Flow path substrate, 34 ... Pressure chamber substrate, 342... Removal portion, 36... Vibration plate, 38... Piezoelectric element, 42 .. casing portion, 44... Sealing body, 46. DESCRIPTION OF SYMBOLS ... Wiring board, 60 ... 1st electrode, 62 ... Electrode part, 64 ... Wiring part, 642 ... Lead-out part, 644 ... Conducting part, 66 ... Boundary part, 70 ... Piezoelectric layer, 72 ... Notch part, 80 ... Second Electrode, SC ... pressure chamber, SR ... liquid storage chamber.

Claims (6)

A pressure chamber substrate on which the pressure chamber is formed;
A diaphragm that is formed on a surface of the pressure chamber substrate and constitutes a wall surface of the pressure chamber;
A piezoelectric element formed on the surface of the diaphragm,
The piezoelectric element is
A first electrode and a second electrode;
A piezoelectric layer between the first electrode and the second electrode;
A boundary portion that is a portion of the first electrode that overlaps with a peripheral edge of the second electrode is located in a region outside the pressure chamber in a plan view, and overlaps the boundary portion in a plan view of the pressure chamber substrate. In the region, a removal portion from which the pressure chamber substrate is removed is formed independently of the pressure chamber. Liquid ejecting head. In the pressure chamber substrate, a first pressure chamber and a second pressure chamber are formed as the pressure chamber,
A first piezoelectric element corresponding to the first pressure chamber and a second piezoelectric element corresponding to the second pressure chamber as the piezoelectric element;
The boundary portion of the first electrode of the first piezoelectric element is located between the first pressure chamber and the second pressure chamber in a plan view, and the boundary portion of the pressure chamber substrate is a plan view. The liquid ejecting head according to claim 1, wherein the overlapping removing portion is formed between the first pressure chamber and the second pressure chamber in a plan view. Each of the first pressure chamber and the second pressure chamber includes a first portion and a second portion that is narrower than the first portion,
The liquid ejecting head according to claim 2, wherein the removing unit is formed between the second portion of the first pressure chamber and the second portion of the second pressure chamber. The liquid ejecting head according to claim 1, wherein a width of the removing unit is narrower than a width of the pressure chamber. The liquid ejecting head according to claim 4, wherein a width of the removal unit is equal to or less than half of a width of the pressure chamber. A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

Images