JP2010214795A - Liquid droplet jetting apparatus, and manufacturing method for liquid droplet jetting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet jetting apparatus which can prevent damages from occurring by protecting the piezoelectric layer of a piezoelectric actuator, and at the same time, prevent a short-circuiting between electrodes resulting from the adherence of a liquid to the piezoelectric layer and the migration of electrode materials from occurring as well. <P>SOLUTION: An inkjet head 1 includes: a flow channel unit 4 having an ink flow channel including a liquid droplet jetting surface 13a on which a nozzle 20 opens, and a pressure chamber 14 communicating with the nozzle 20; and the piezoelectric actuator 5 which is installed in the flow channel unit 4, and at the same time, has the piezoelectric layer 31 which is arranged to face the pressure chamber 14, and an individual electrode 32 which is installed on the piezoelectric layer 31. Then, on the liquid droplet jetting surface 13a of the flow channel unit 4, a liquid repelling film 22 having liquid-repellency is installed. In the meantime, the surface of the piezoelectric layer 31 of the piezoelectric actuator 5 is covered with a protective film 38 which is formed of the same material as the liquid repelling film 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a droplet ejecting apparatus that ejects droplets and a method for manufacturing the droplet ejecting apparatus.

  2. Description of the Related Art Conventionally, there is a liquid droplet ejecting apparatus that ejects liquid droplets that includes a piezoelectric actuator that applies an ejection pressure to a liquid. For example, Patent Document 1 discloses an ink jet head as a droplet ejecting apparatus. The ink jet head includes a flow path unit in which an ink flow path such as a nozzle and a pressure chamber communicating with the nozzle is formed; A piezoelectric actuator is provided in the flow path unit and applies pressure to the ink in the pressure chamber.

  In addition, the piezoelectric actuator disclosed in Patent Document 1 is interposed between a vibration plate joined to a flow path unit so as to cover a pressure chamber, a piezoelectric layer disposed on the vibration plate, and the vibration plate and the piezoelectric layer. A lower electrode; and an upper electrode provided in a region of the upper surface of the piezoelectric layer facing the pressure chamber. When a voltage is applied between the upper electrode and the lower electrode, and an electric field in the thickness direction acts on the piezoelectric layer between the two electrodes, the piezoelectric layer is deformed (piezoelectric strain) and vibrates to cover the pressure chamber The displacement of the plate changes the volume of the pressure chamber, and pressure is applied to the ink inside.

JP 2006-54442 A

  Incidentally, the piezoelectric material constituting the piezoelectric layer is a ceramic that is a brittle material, and in the conventional piezoelectric actuator as described in Patent Document 1, the piezoelectric layer is exposed on the surface opposite to the flow path unit. is doing. Therefore, there is a possibility that damage such as cracks may occur in the piezoelectric layer when an external impact is applied to the piezoelectric layer or when the piezoelectric actuator is operated (when the piezoelectric layer is deformed).

  In general, the liquid ejected from the nozzle floats around the piezoelectric actuator as a mist. When the floating liquid adheres to the exposed surface of the piezoelectric layer, a short circuit occurs between the electrodes provided on the piezoelectric layer, or migration of the electrode material in the piezoelectric layer is promoted by the adhered liquid. As a result, there is a possibility that a problem such as dielectric breakdown of the piezoelectric layer occurs.

  An object of the present invention is to provide a droplet ejecting apparatus capable of protecting a piezoelectric layer of a piezoelectric actuator to prevent damage and preventing short-circuiting between electrodes and migration of electrode material due to liquid adhering to the piezoelectric layer. Is to provide.

According to a first aspect of the present invention, there is provided a liquid droplet ejecting apparatus comprising: a liquid droplet ejecting surface on which a nozzle for ejecting liquid droplets opens; a flow path unit having a liquid flow path including a pressure chamber communicating with the nozzle; A piezoelectric actuator having a piezoelectric layer disposed so as to face the pressure chamber and a driving electrode provided on the piezoelectric layer,
A liquid repellent film having liquid repellency is provided on the droplet ejection surface of the flow path unit,
The surface of the piezoelectric layer of the piezoelectric actuator is covered with a protective film made of the same film material as the liquid repellent film.

  According to this configuration, since the surface of the piezoelectric layer (the surface opposite to the flow path unit) is covered with the protective film, the piezoelectric layer is used when an impact is applied to the actuator from the outside or when the actuator is operated. It is possible to prevent the occurrence of damage such as cracks. Furthermore, the protective film is formed of the same film material as the liquid repellent film provided to prevent the liquid adhering to the droplet ejection surface from staying around the nozzle opening. Such a film having high liquid repellency generally has low permeability of liquid and water vapor (excellent blocking performance). For this reason, the protective film prevents the liquid around the actuator from being separated from the piezoelectric layer, so that the liquid does not adhere to the piezoelectric layer, causing short-circuiting between electrodes and migration of electrode material within the piezoelectric layer. Can be prevented. In the present invention, “a film having liquid repellency” means a substrate (in this case, a liquid droplet ejecting surface of a flow path unit or a piezoelectric film) when the film is not formed. It is a film formed with a material having higher surface repellency compared to the surface of the layer.

  In the liquid droplet ejecting apparatus according to a second aspect, in the first aspect, the protective film is provided so as to cover almost the entire region of the surface of the piezoelectric layer facing the pressure chamber. It is characterized by.

  Since a predetermined electric field is applied to the portion of the piezoelectric layer facing the pressure chamber when a voltage is applied to the drive electrode, migration of the electrode material is particularly likely to occur. Therefore, it is preferable that almost the entire region of the surface of the piezoelectric layer facing the pressure chamber is covered with a protective film.

In the liquid droplet ejecting apparatus according to a third aspect of the present invention, in the first or second aspect, the piezoelectric actuator is drawn from the drive electrode to the surface of the piezoelectric layer, Having a terminal to be connected,
The protective film is provided with an opening for exposing the terminal drawn out to the surface of the piezoelectric layer, and a convex for connecting the terminal and the wiring member to the terminal exposed in the opening. It is characterized in that a shaped bump is provided.

  According to this configuration, when the bump is formed by attaching a conductive material having fluidity to the terminal drawn from the drive electrode to the surface of the piezoelectric layer, the liquid repellency provided around the terminal is formed. Since the conductive material does not easily flow from the position of the terminal to the periphery by the protective film having, the height of the bump can be easily set to a desired height.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the piezoelectric actuator includes a diaphragm bonded to the flow path unit so as to cover the pressure chamber. The piezoelectric layer is disposed on a surface of the diaphragm opposite to the pressure chamber, and the diaphragm is formed of a material having higher toughness than the piezoelectric layer.

  According to this configuration, even if a crack is generated in the piezoelectric layer due to an external impact on the piezoelectric actuator or the piezoelectric actuator is continuously driven, the crack propagates to the diaphragm. Transmission to the pressure chamber can be avoided. Therefore, the liquid in the pressure chamber can be prevented from adhering to the piezoelectric layer.

According to a fifth aspect of the present invention, there is provided a manufacturing method of a liquid droplet ejecting apparatus, comprising: a liquid droplet ejecting surface on which a nozzle for ejecting liquid droplets is open; A method of manufacturing a droplet ejecting apparatus including a piezoelectric actuator provided in a flow path unit and having a piezoelectric layer disposed to face the pressure chamber and a drive electrode provided in the piezoelectric layer,
A liquid repellent film forming step for forming a liquid repellent film having liquid repellency on the droplet ejection surface of the flow path unit, and a film material same as the liquid repellent film on the surface of the piezoelectric layer of the piezoelectric actuator. And a protective film forming step of forming a protective film covering the piezoelectric layer.

  Thus, by forming a protective film on the surface of the piezoelectric layer (the surface opposite to the flow path unit), damage such as cracks occurs in the piezoelectric layer when an external impact is applied or the actuator is operated. It is prevented. Furthermore, in the present invention, the protective film is formed of the same film material as the liquid repellent film provided to prevent the liquid adhering to the droplet ejection surface from staying around the nozzle opening. Here, such a highly liquid-repellent film generally has low liquid or water vapor permeability (excellent blocking performance). For this reason, the protective film prevents the liquid around the actuator from being separated from the piezoelectric layer, so that the liquid does not adhere to the piezoelectric layer, causing short-circuiting between electrodes and migration of electrode material within the piezoelectric layer. Can be prevented.

According to a sixth aspect of the present invention, there is provided the manufacturing method of the droplet ejecting device according to the fifth aspect, wherein the flow path unit is integrated with the piezoelectric actuator after the piezoelectric actuator is provided in the flow path unit. Housed in,
In the film formation chamber, the liquid repellent film and the protective film are formed by depositing the film material on the droplet ejection surface of the flow path unit and the surface of the piezoelectric layer of the piezoelectric actuator, respectively. It is characterized by performing.

  According to the present invention, since the liquid repellent film and the protective film made of the same film material can be formed at the same time in the same chamber of the film forming apparatus, the manufacturing process can be simplified.

  According to a seventh aspect of the present invention, there is provided the manufacturing method of the droplet ejecting apparatus according to the sixth aspect, wherein the liquid repellent film and the protective film are formed by sputtering or vapor deposition in the liquid repellent film forming step and the protective film forming step. Each of them is formed by any one of the CVD methods.

  As described above, when the sputtering method, the vapor deposition method, or the CVD method is employed, it is easy to form the liquid repellent film and the protective film in a uniform thickness.

  According to an eighth aspect of the present invention, there is provided the manufacturing method of the droplet ejecting apparatus according to any one of the fifth to seventh aspects, wherein in the protective film forming step, the protective film is formed on the surface of the piezoelectric layer. It is characterized in that it is formed so as to cover almost the whole area of the area opposite to.

  Migration is particularly likely to occur in the portion of the piezoelectric layer facing the pressure chamber because a predetermined electric field is applied by applying a voltage to the drive electrode. Therefore, it is preferable to cover the entire surface of the surface of the piezoelectric layer with a protective film almost in the region facing the pressure chamber.

According to a ninth aspect of the present invention, there is provided the method for manufacturing a droplet ejecting apparatus according to any one of the fifth to eighth aspects, wherein the piezoelectric actuator is drawn from the drive electrode to the surface of the piezoelectric layer. It has a terminal connected to the power supply wiring member,
In the protective film forming step, the protective film having an opening for exposing the terminal drawn to the surface of the piezoelectric layer is formed,
After a conductive material having fluidity is attached to the terminal exposed in the opening, the conductive material is cured to form a convex bump for connecting the terminal and the wiring member. It is characterized by this.

  When forming a bump by attaching a conductive material having fluidity to the terminal drawn from the drive electrode to the surface of the piezoelectric layer, a protective film having liquid repellency provided around the terminal, Since the conductive material does not easily flow from the position of the terminal to the periphery, it is easy to set the bump height to a desired height.

  According to the present invention, since the surface of the piezoelectric layer (the surface opposite to the flow path unit) is covered with the protective film, the piezoelectric layer is used when an impact is applied to the actuator from the outside or when the actuator is operated. It is possible to prevent the occurrence of damage such as cracks. Furthermore, the protective film is formed of the same film material as the liquid repellent film provided to prevent the liquid adhering to the droplet ejection surface from staying around the nozzle opening. Such a film having high liquid repellency generally has low permeability of liquid and water vapor (excellent blocking performance). For this reason, the protective film prevents the liquid around the actuator from being separated from the piezoelectric layer, so that the liquid does not adhere to the piezoelectric layer, causing short-circuiting between electrodes and migration of electrode material within the piezoelectric layer. Can be prevented.

1 is a schematic configuration diagram of a printer according to an embodiment. It is a top view of an inkjet head. FIG. 3 is a partially enlarged view of FIG. 2. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3. It is the VV sectional view taken on the line of FIG. It is a figure which shows the first half part of the manufacturing process of the inkjet head which concerns on this embodiment, (a) is a plate joining process, (b) is a piezoelectric layer formation process, (c) is an individual electrode formation process, (d) is a nozzle. Each of the plate joining steps is shown. It is a figure which shows the latter half part of the manufacturing process of the inkjet head which concerns on this embodiment, (a) shows the formation process of a liquid repellent film and a protective film, (b) shows a bump formation process, respectively. It is a figure which shows schematically the structure of the film-forming apparatus used at the formation process of a liquid repellent film and a protective film. It is sectional drawing equivalent to FIG. 4 of the inkjet head of a change form.

  Next, an embodiment of the present invention will be described. This embodiment is an example in which the present invention is applied to an ink jet printer that records desired images, characters, and the like by ejecting ink droplets from nozzles onto recording paper.

  First, a schematic configuration of the ink jet printer will be briefly described. FIG. 1 is a schematic configuration diagram of a printer according to the present embodiment. As shown in FIG. 1, an inkjet printer 100 includes a carriage 2 that can move in the left-right direction in FIG. 1, a serial type inkjet head 1 that is provided on the carriage 2 and that ejects ink onto recording paper P, A transport roller 3 for transporting the recording paper P forward in FIG. 1 is provided.

  Then, the printer 1 moves the inkjet head 1 integrally with the carriage 2 in the left-right direction (scanning direction), and from the nozzles 20 (see FIGS. 2 to 5) disposed on the lower surface thereof by the transport roller 3. Ink is ejected onto the recording paper P conveyed forward (in the paper feed direction) in the figure to record desired characters, images, and the like on the recording paper P.

  Next, the inkjet head 1 (droplet ejecting apparatus) will be described. 2 is a plan view of the inkjet head 1, FIG. 3 is a partially enlarged view of FIG. 2, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, and FIG. 5 is a sectional view taken along line VV in FIG. . As shown in FIGS. 2 to 5, the inkjet head 1 includes a nozzle 20 and a flow path unit 4 in which an ink flow path including a pressure chamber 14 communicating with the nozzle 20 is formed, and nozzles in the ink in the pressure chamber 14. And a piezoelectric actuator 5 that applies pressure to be ejected from the nozzle 20.

  First, the flow path unit 4 will be described. As shown in FIGS. 4 and 5, the flow path unit 4 includes a cavity plate 10, a base plate 11, a manifold plate 12, and a nozzle plate 13, and these four plates 10 to 13 are joined in a stacked state. Yes. Among these, the cavity plate 10, the base plate 11 and the manifold plate 12 are stainless steel plates, and ink flow paths such as a manifold 17 and a pressure chamber 14 described later can be easily etched in these three plates 10-12. It can be formed. The nozzle plate 13 is formed of, for example, a polymer synthetic resin material such as polyimide, and is bonded to the lower surface of the manifold plate 12. Or this nozzle plate 13 may be formed with metal materials, such as stainless steel, similarly to the three plates 10-12.

  As shown in FIGS. 2 to 5, among the four plates 10 to 13, the cavity plate 10 located at the uppermost position has holes through which a plurality of pressure chambers 14 arranged along a plane penetrate the plate 10. It is formed by. The plurality of pressure chambers 14 are respectively covered with a diaphragm 30 and a base plate 11 described later from above and below. Further, the plurality of pressure chambers 14 are arranged in a staggered manner along the paper feeding direction (up and down direction in FIG. 2) to form two pressure chamber rows. Furthermore, each pressure chamber 14 is formed in a substantially elliptical shape that is long in the scanning direction (left-right direction in FIG. 2) in plan view.

  As shown in FIG. 3, communication holes 15 and 16 are formed at positions where the base plate 11 overlaps both ends of the pressure chamber 14 in a plan view. The manifold plate 12 is formed with two manifolds 17 extending in the paper feeding direction so as to overlap with the communication hole 15 side portions of the pressure chambers 14 arranged in two rows in a plan view. These two manifolds 17 communicate with an ink supply port 18 formed in a vibration plate 30 described later, and ink is supplied to the manifold 17 from an ink tank (not shown) via the ink supply port 18. Furthermore, a plurality of communication holes 19 that are continuous with the plurality of communication holes 16 are also formed at positions where the manifold plate 12 overlaps the ends of the plurality of pressure chambers 14 opposite to the manifold 17 in plan view.

  Further, a plurality of nozzles 20 are formed at positions where the nozzle plate 13 respectively overlaps the plurality of communication holes 19 in plan view. As shown in FIG. 2, the plurality of nozzles 20 are arranged in a staggered manner so as to overlap with the end portions of the plurality of pressure chambers 14 arranged in two rows along the paper feed direction on the side opposite to the manifold 17. Thus, two nozzle rows are configured. The lower surface of the nozzle plate 13 is a droplet ejection surface 13a through which a plurality of nozzles 20 are opened.

  As shown in FIGS. 4 and 5, the droplet ejection surface 13 a of the nozzle plate 13 is covered with a liquid repellent film 22. The liquid repellent film 22 is made of a material having higher liquid repellency than the nozzle plate 13 made of polyimide or the like (for example, fluorine resin such as PTFE (polytetrafluoroethylene)). Therefore, even if some of the ink droplets ejected from the nozzle 20 adhere to the droplet ejecting surface 13a, the ink is less likely to stay around the nozzle 20 due to the high liquid repellency of the liquid repellent film 22. Ink adhering to the droplet ejection surface 13a is prevented from adversely affecting the droplets ejected from the nozzle 20 thereafter (occurrence of ejection bending, etc.).

  As shown in FIG. 4, the manifold 17 communicates with the pressure chamber 14 through the communication hole 15, and the pressure chamber 14 communicates with the nozzle 20 through the communication holes 16 and 19. As described above, a plurality of individual ink flow paths 21 extending from the manifold 17 to the nozzles 20 through the pressure chambers 14 are formed in the flow path unit 4.

  Next, the piezoelectric actuator 5 will be described. As shown in FIGS. 2 to 5, the piezoelectric actuator 5 is opposed to the vibration plate 30 disposed on the upper surface of the flow path unit 4 (cavity plate 10) and the plurality of pressure chambers 14 on the upper surface of the vibration plate 30. The piezoelectric layer 31 formed as described above and a plurality of individual electrodes 32 (drive electrodes) disposed on the upper surface of the piezoelectric layer 31 are provided.

  The diaphragm 30 is a substantially rectangular metal plate in plan view, and is made of, for example, an iron-based alloy such as stainless steel, a copper-based alloy, a nickel-based alloy, or a titanium-based alloy. The diaphragm 30 is joined to the upper surface of the cavity plate 10 so as to cover the plurality of pressure chambers 14. The upper surface of the diaphragm 30 having conductivity also serves as a common electrode that sandwiches the piezoelectric layer 31 between the plurality of individual electrodes 32 and generates an electric field in the thickness direction in the piezoelectric layer 31. Further, the diaphragm 30 as the common electrode is always held at the ground potential.

  On the upper surface of the vibration plate 30, a piezoelectric layer 31 made of a piezoelectric material mainly composed of lead zirconate titanate (PZT), which is a solid solution and is a ferroelectric substance, is formed of lead titanate and lead zirconate. Yes. The piezoelectric layer 31 is continuously formed so as to cover the plurality of pressure chambers 14.

  On the upper surface of the piezoelectric layer 31, a plurality of individual electrodes 32 having a substantially elliptical planar shape that is slightly smaller than the pressure chamber 14 are formed. These individual electrodes 32 are respectively arranged at positions facing the central part of the corresponding pressure chamber 14. The individual electrode 32 is made of a conductive material such as gold, copper, silver, palladium, platinum, or titanium.

  Further, the upper surface of the piezoelectric layer 31 is led out from the end of the plurality of individual electrodes 32 arranged in two rows on the side of the communication hole 15 (outside in the left-right direction in FIG. 2) to a region not facing the pressure chamber 14. A plurality of connection terminals 35 are provided. As shown in FIG. 4, the plurality of connection terminals 35 are each provided with a convex bump 39 made of a conductive material. A driver IC (not shown) for driving the piezoelectric actuator 5 is mounted above the piezoelectric layer 31, and a flexible printed circuit board (FPC) that supplies power to the individual electrodes 32 from the driver IC. ): Wiring member) is arranged, and the plurality of connection terminals 35 are connected to the terminals of the FPC 50 through convex bumps 39. That is, the plurality of individual electrodes 32 provided on the upper surface of the piezoelectric layer 31 are electrically connected to the driver IC mounted on the FPC 50 via the connection terminals 35, the bumps 39, and the wiring on the FPC 50. . When the piezoelectric actuator 5 is driven, a predetermined drive potential is applied from the driver IC to the individual electrode 32 corresponding to the desired nozzle 20 that ejects ink.

  In addition to this, in this embodiment, the entire upper surface 31 a (surface opposite to the flow path unit 4) of the piezoelectric layer 31 on which the individual electrode 32 and the connection terminal 35 are provided is covered with the protective film 38. It has been broken. The protective film 38 is formed of the same film material (for example, fluorine-based resin) as the liquid repellent film 22 that covers the droplet ejection surface 13a of the nozzle plate 13 described above. As described above, the upper surface 31a of the piezoelectric layer 31 is covered with the protective film 38, so that when the impact is applied to the piezoelectric actuator 5 from the outside or the actuator is operated, the piezoelectric layer 31 is damaged such as a crack. Is prevented from occurring.

  The protective film 38 is formed of a material having excellent liquid repellency, such as a fluorine-based resin, like the liquid repellent film 22. A film formed of such a liquid repellent material is generally used. In addition, it is known that the permeability of liquid and water vapor is low (excellent blocking performance). Therefore, ink (moisture) ejected from the nozzle 20 and present in the form of mist around the piezoelectric actuator 5 and the piezoelectric layer 31 are blocked by the protective film 38, and the ink is protected from adhering to the upper surface 31 a of the piezoelectric layer 31. Blocked by the membrane 38. Thereby, a short circuit between adjacent individual electrodes 32 (connection terminals 35) is prevented. Further, when moisture is present, a migration phenomenon in the piezoelectric layer 31 is likely to occur. That is, the ionization of the electrode material constituting the individual electrode 32 is promoted by moisture, and the electrode material may move to the cathode side (here, the metal diaphragm 30), causing dielectric breakdown of the piezoelectric layer 31. There is. However, in the present embodiment, the protective film 38 prevents moisture from adhering to the upper surface 31a of the piezoelectric layer 31, so that the dielectric breakdown due to the occurrence of the migration can also be prevented.

  As shown in FIGS. 3 and 4, in the region where the connection terminal 35 is formed on the upper surface of the piezoelectric layer 31, an opening 38 a for exposing the connection terminal 35 is formed in the protective film 38. A convex bump 39 made of a conductive material is disposed on the surface of the connection terminal 35 exposed in the opening 38a. That is, the individual electrodes 32 and the connection terminals 35 are all covered with the protective film 38 except for the region where the convex bumps 39 are formed.

  Further, the protective film 38 is provided so as to cover the entire area of the upper surface of the piezoelectric layer 31 facing the pressure chamber 14. As will be described later, the portion of the piezoelectric layer 31 facing the pressure chamber 14 is activated by applying a voltage between the individual electrode 32 and the diaphragm 30 as a common electrode, thereby applying a predetermined electric field. Migration is particularly likely to occur. Therefore, as in this embodiment, from the viewpoint of preventing migration, it is preferable that the entire area of the upper surface of the piezoelectric layer 31 facing the pressure chamber 14 is covered with the protective film 38.

  In the present embodiment, the lower surface of the piezoelectric layer 31 is covered with a metal diaphragm 30. In general, a metal material has a much higher toughness than the piezoelectric material constituting the piezoelectric layer 31. Therefore, when a shock is applied to the piezoelectric actuator 5 from the outside or the driving of the piezoelectric actuator 5 is continued for a long period of time, the piezoelectric material is piezoelectric. Even when a crack occurs in the layer 31, it can be avoided that the crack propagates to the diaphragm 30 and reaches the pressure chamber 14. Therefore, even in such a case, the metal diaphragm 30 reliably prevents ink from entering the piezoelectric layer 31 from the flow path unit 4 (pressure chamber 14) side. That is, the metal diaphragm 30 that covers the lower surface of the piezoelectric layer 31 and the protective film 38 that covers the upper surface 31a of the piezoelectric layer 31 prevent ink from entering the piezoelectric layer 31 almost completely.

  Next, the operation of the piezoelectric actuator 5 during ink ejection will be described. When a predetermined drive potential is selectively applied to the plurality of individual electrodes 32 from the driver IC, the individual electrode 32 on the upper side of the piezoelectric layer 31 to which the drive potential is applied and the piezoelectric layer 31 held at the ground potential. Since the potentials of the diaphragm 30 as the lower common electrode are different from each other, an electric field in the thickness direction is generated in the piezoelectric layer 31 sandwiched between the individual electrode 32 and the diaphragm 30. When the polarization direction of the piezoelectric layer 31 is the same as the direction of the electric field, the piezoelectric layer 31 extends in the thickness direction, which is the polarization direction, and contracts in the horizontal direction (piezoelectric lateral effect). Along with the deformation, the portion of the diaphragm 30 facing the pressure chamber 14 is bent so as to be convex toward the pressure chamber 14 side. At this time, since the volume of the pressure chamber 14 is reduced, pressure is applied to the ink inside the pressure chamber 14, and ink droplets are ejected from the nozzle 20 communicating with the pressure chamber 14.

  Next, the manufacturing method of the inkjet head 1 of this embodiment is demonstrated. 6 and 7 are diagrams showing a manufacturing process of the ink jet head 1. First, in the cavity plate 10, the base plate 11, and the manifold plate 12 among the plates constituting the flow path unit 4, holes constituting the ink flow paths such as the pressure chamber 14 and the manifold 17 are formed. Since these plates 10 to 12 are made of a metal material, the holes constituting the ink flow path can be easily formed by etching.

  Then, as shown in FIG. 6A, the four metal plates of the vibration plate 30, the cavity plate 10, the base plate 11, and the manifold plate 12 are laminated and joined. The joining method at this time is not particularly limited. For example, four metal plates are joined by metal diffusion joining by pressing the laminated plates while heating them to a predetermined temperature (for example, 1000 ° C.) or higher. can do. Alternatively, four plates can be joined using an adhesive.

  Next, as shown in FIG. 6B, the piezoelectric layer 31 is formed on the upper surface of the diaphragm 30. Here, the method for forming the piezoelectric layer 31 is not particularly limited. For example, an aerosol containing particles of a film forming material (here, a piezoelectric material) and a carrier gas is used as a film forming target substrate (here, the vibration plate 30). The aerosol deposition method (AD method) can be employed in which particles are deposited on the substrate. In addition, the piezoelectric layer 31 may be formed by a known method such as sputtering, vapor deposition, CVD, sol-gel, or hydrothermal synthesis. Furthermore, the piezoelectric layer 31 may be formed by attaching a piezoelectric sheet obtained by firing a green sheet to the diaphragm 30 with an adhesive.

  Next, as illustrated in FIG. 6C, the individual electrodes 32 and the connection terminals 35 are formed on the upper surface 31 a of the piezoelectric layer 31. Here, when the piezoelectric layer 31 is formed using the above-described film formation method such as the AD method or the sputtering method, the individual electrode 32 and the connection terminal 35 are screen-printed or sputtered on the upper surface 31a of the piezoelectric layer 31. It is formed at a time by a method, a vapor deposition method or the like. Further, when the piezoelectric layer 31 is formed by attaching the fired piezoelectric sheet to the diaphragm 30, the individual electrodes 32 and the connection terminals 35 are first formed on the green sheet before firing by screen printing or the like, The piezoelectric sheet, the individual electrode 32, and the connection terminal 35, which are obtained after firing, are bonded to the diaphragm 30. That is, the steps of FIGS. 6B and 6C are performed simultaneously.

  Next, after a plurality of nozzles 20 are formed on the synthetic resin nozzle plate 13 by laser processing or the like, the nozzle plate 13 is joined to the lower surface of the manifold plate 12 with an adhesive or the like as shown in FIG. To do. Thereby, the laminated body 60 in which the flow path unit 4 composed of the plates 10 to 13 and the piezoelectric actuator 5 having the diaphragm 30, the piezoelectric layer 31, and the individual electrode 32 are integrated is completed.

  Note that the nozzle plate 13 may be formed of a metal material such as stainless steel in the same manner as the other three plates 10 to 12 constituting the flow path unit 4, and in that case, FIG. In the plate joining step shown in FIG. 4, the plates 10 to 12 and the diaphragm 30 and the nozzle plate 13 may be joined at once by metal diffusion bonding.

  Next, as shown in FIG. 7A, the upper and lower surfaces of the laminate 60 composed of the flow path unit 4 and the piezoelectric actuator 5 obtained in FIG. 6D, that is, the lower surface (droplet) of the nozzle plate 13. A liquid repellent film 22 and a protective film 38 are formed on the ejection surface 13a) and the upper surface of the piezoelectric layer 31 with the same film material having liquid repellency such as a fluororesin (liquid repellent film forming process, protective film forming process). ).

  Here, each of the liquid repellent film 22 and the protective film 38 can be formed by applying a film material such as a fluororesin to the upper and lower surfaces of the laminate 60. Alternatively, a method of depositing a film material such as a sputtering method, a CVD method, a vapor deposition method, or an AD method may be employed. Among these, from the viewpoint of forming a film having a uniform thickness, it is preferable to form the liquid repellent film 22 and the protective film 38 by any one of a sputtering method, a vapor deposition method, and a CVD method.

  In addition, the liquid repellent film 22 and the protective film 38 may be formed in separate steps, but from the viewpoint of simplifying the manufacturing process, the liquid repellent film 22 and the protective film 38 made of the same film material are formed in one step. It is preferable to form at once. This can be easily realized by employing a film forming method such as the sputtering method, the vapor deposition method, the CVD method, or the AD method described above.

  FIG. 8 is a schematic configuration diagram of a film forming apparatus 70 for forming the liquid repellent film 22 and the protective film 38 using a vapor deposition method. As shown in FIG. 8, the film forming apparatus 70 includes a film forming chamber 71, a vacuum pump 72 for evacuating the film forming chamber 71, and a stacked body 60 that is a film forming target in the film forming chamber 71. A holding member 73 that holds the film, a shutter 74 that moves up and down so as to cover both surfaces of the laminate 60 held by the holding member 73, a crucible 75 that houses the film material 78, and the like. In the film forming chamber 71, two crucibles 75 are installed on both sides of the laminate 60, and heaters 76 for melting a film material 78 such as PTFE housed in each crucible 75 are provided. In addition, the holding member 73 is provided with a heater 77 that heats the stacked body 60 held by the holding member 73.

  First, the stacked body 60 is accommodated in the film forming chamber 71 and held by the holding member 73, and the film forming chamber 71 is evacuated by the vacuum pump 72. In addition, the two crucibles 75 are heated to about 600 to 800 ° C. by the heater 76 in a state where the shutter 74 is at the upper limit position (position indicated by a two-dot chain line in the figure) and covers both surfaces of the laminate 60. The film material 78 such as PTFE inside thereof is melted. Further, the laminate 60 is heated to about 200 to 250 ° C. by the heater 77 provided on the holding member 73. In this state, the shutter 74 is moved downward and held at the lower limit position (the position indicated by the solid line in the figure), thereby depositing the film material 78 in the two crucibles 75 on both surfaces of the laminate 60, respectively. The liquid repellent film 22 and the protective film 38 are formed simultaneously.

  Further, as shown in FIG. 7A, in the protective film forming step, an opening 38a for exposing the connection terminal 35 formed on the upper surface of the piezoelectric layer 31 is formed in the protective film 38. The opening 38a may be formed by forming the protective film 38 over the entire upper surface 31a of the piezoelectric layer 31 and then removing the protective film 38 covering the connection terminals 35 by laser processing or the like. . Alternatively, after a masking material is placed on the surface of the connection terminal 35, the protective film 38 is formed on the upper surface 31 a of the piezoelectric layer 31, and then the masking material is removed, thereby opening the opening 38 a in the region where the masking material has been placed. You may make it form.

  Thereafter, as shown in FIG. 7B, a conductive material having fluidity such as conductive paste, solder, or conductive adhesive is attached to the connection terminal 35 exposed in the opening 38a of the protective film 38. Thereafter, the conductive bumps 39 are formed by curing the conductive material. Here, when a conductive material is adhered to the connection terminal 35, the liquid-repellent protective film 38 provided around the connection terminal 35 makes it difficult for the conductive material having fluidity to flow around. . Accordingly, it is easy to set the height of the convex bump 39 to a desired height, and the variation of the bump 39 among the plurality of connection terminals 35 is reduced. Thus, if the height of the bump 39 is controlled to a predetermined height, when the FPC 50 is joined to the piezoelectric actuator 5 in a subsequent process, poor connection between the two terminals hardly occurs. Further, since the liquid repellency of the surface of the electrode material of the connection terminal 35 and the individual electrode 32 connected to the connection terminal 35 is low (high wettability), conventionally, a conductive material having fluidity for forming bumps has been used. However, by applying the present invention, such a problem can be solved by flowing into the individual electrode 32 from the surface of the substrate and inhibiting the deformation of the piezoelectric layer 31 on the pressure chamber 14.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having substantially the same configuration as those of the above embodiment are denoted by the same reference numerals and description thereof is omitted as appropriate.

1] As described in the above embodiment, it is not necessary to form the liquid repellent film 22 and the protective film 38 at the same time, and they may be formed in separate steps. In FIG. 8 of the above embodiment, the liquid repellent film 22 and the protective film 38 are simultaneously formed in one film forming chamber 71. First, only one film is formed in the film forming chamber 71. A method of forming both films in order without removing the stacked body 60 from the film forming chamber 71, such as forming the other film after changing the posture of the stacked body 60 after film formation, is adopted. May be.

2] The piezoelectric actuator 5 of the above-described embodiment has a diaphragm 30 that covers the pressure chamber 14 of the flow path unit 4, and a so-called unimorph type having a single piezoelectric layer 31 disposed on the diaphragm 30. Although it was a piezoelectric actuator, the actuator to which the present invention is applied is not limited to this. For example, like the piezoelectric actuator 5 </ b> A of the inkjet head 1 </ b> A shown in FIG. 9, a plurality of stacked piezoelectric layers 81 are provided, and an individual electrode 82 to which a driving potential is applied between the plurality of piezoelectric layers 81. And a so-called stacked actuator in which common electrodes 84 held at the ground potential are alternately arranged. The laminated piezoelectric actuator as shown in FIG. 9 mainly uses the deformation (piezoelectric longitudinal effect) in the thickness direction of each piezoelectric layer 81 itself sandwiched between the individual electrode 82 and the common electrode 84. Since the volume of the chamber 14 is changed, it is not necessary to provide a diaphragm that bends according to the deformation of the piezoelectric layer, which is necessary for the unimorph type piezoelectric actuator of the embodiment. However, if the piezoelectric layer 81 is in direct contact with the ink in the pressure chamber 14, the ink easily enters the piezoelectric layer 81, so that the ink in the pressure chamber 14 enters the piezoelectric layer 81. From the viewpoint of preventing this, it is preferable to provide an anti-permeation film 80 made of a material having low ink permeability such as a metal material as shown in FIG.

3] In the piezoelectric actuator 5 of the above embodiment, the individual electrode 32 (drive electrode) to which a predetermined drive potential is applied is disposed on the upper surface 31a of the piezoelectric layer 31 covered with the protective film 38. Is not necessarily located on the upper surface of the piezoelectric layer, and the individual electrodes 82 may be disposed between (inside) the piezoelectric layers 81 as in the actuator 5A of FIG. 9 described above. As shown in FIG. 9, when the individual electrode 82 is located inside, when connecting the FPC 50 positioned above the uppermost piezoelectric layer 81 and the individual electrode 82, for example, Make the configuration. First, a through hole 86 is formed in the piezoelectric layer 81 located above the individual electrode 82, and the inside thereof is filled with a conductive material. The conductive material in the through hole 86 is electrically connected to the individual electrode 82 located inside and the connection terminal 85 formed on the upper surface 81a of the uppermost piezoelectric layer 81, respectively. Accordingly, the connection terminal 85 connected to the FPC 50 is drawn from the individual electrode 82 to the upper surface 81a of the uppermost piezoelectric layer 81 through the conductive material in the through hole 86.

  As described above, as an embodiment of the present invention, an example in which the present invention is applied to an inkjet head that applies pressure to ink in an ink flow path and ejects the ink from a nozzle has been described. The present invention can also be applied to a liquid droplet ejecting apparatus used in various technical fields that ejects a liquid other than ink for image printing (for example, a conductive paste, a chemical liquid, or a chemical solution) from a nozzle. .

1, 1A Inkjet head 4 Flow path unit 5, 5A Piezoelectric actuator 13a Droplet ejection surface 14 Pressure chamber 20 Nozzle 22 Liquid repellent film 30 Vibration plate 31 Piezoelectric layer 32 Individual electrode 35 Connection terminal 38 Protective film 38a Opening 39 Bump 50 Flexible print Wiring board 60 Laminate 70 Film forming apparatus 71 Film forming chamber 81 Piezoelectric layer 82 Individual electrode 84 Common electrode 85 Connection terminal

Claims (9)

A flow path unit having a liquid flow path including a liquid droplet ejection surface where a nozzle for ejecting liquid droplets opens, and a pressure chamber communicating with the nozzle;
A piezoelectric actuator provided in the flow path unit and having a piezoelectric layer disposed to face the pressure chamber and a drive electrode provided in the piezoelectric layer,
A liquid repellent film having liquid repellency is provided on the droplet ejection surface of the flow path unit,
The droplet ejecting apparatus, wherein the surface of the piezoelectric layer of the piezoelectric actuator is covered with a protective film made of the same film material as the liquid repellent film.   The droplet ejecting apparatus according to claim 1, wherein the protective film is provided so as to cover substantially the entire region of the surface of the piezoelectric layer facing the pressure chamber. The piezoelectric actuator is
A terminal that is drawn from the drive electrode to the surface of the piezoelectric layer and connected to a power supply wiring member of the drive electrode;
The protective film is provided with an opening for exposing the terminal drawn to the surface of the piezoelectric layer,
The droplet ejecting apparatus according to claim 1, wherein a convex bump for connecting the terminal and the wiring member is provided on the terminal exposed in the opening. The piezoelectric actuator is
While having a diaphragm joined to the flow path unit so as to cover the pressure chamber, the piezoelectric layer is disposed on the surface of the diaphragm opposite to the pressure chamber,
The droplet ejecting apparatus according to claim 1, wherein the diaphragm is made of a material having higher toughness than the piezoelectric layer. A liquid droplet ejecting surface on which a nozzle for ejecting liquid droplets opens, a flow path unit having a liquid flow path including a pressure chamber communicating with the nozzle, and provided in the flow path unit and facing the pressure chamber. A method of manufacturing a droplet ejecting apparatus including a piezoelectric actuator having a piezoelectric layer arranged in this manner and a drive electrode provided on the piezoelectric layer,
A liquid repellent film forming step of forming a liquid repellent film having liquid repellency on the droplet ejection surface of the flow path unit;
A protective film forming step of forming a protective film covering the piezoelectric layer with the same film material as the liquid repellent film on the surface of the piezoelectric layer of the piezoelectric actuator;
A method for manufacturing a liquid droplet ejecting apparatus. After providing the piezoelectric actuator in the flow path unit, the integrated flow path unit and the piezoelectric actuator are accommodated in a film forming chamber,
In the film formation chamber, the liquid repellent film and the protective film are formed by depositing the film material on the droplet ejection surface of the flow path unit and the surface of the piezoelectric layer of the piezoelectric actuator, respectively. The method for manufacturing a droplet ejecting apparatus according to claim 5, wherein:   7. The liquid repellent film forming step and the protective film forming step, wherein the liquid repellent film and the protective film are formed by any one of a sputtering method, a vapor deposition method, and a CVD method, respectively. A method for manufacturing a droplet ejecting apparatus.   In the protective film forming step, the protective film is formed so as to cover almost the entire region of the surface of the piezoelectric layer facing the pressure chamber. A method for manufacturing the liquid droplet ejecting apparatus according to claim. The piezoelectric actuator has a terminal that is drawn from the drive electrode to the surface of the piezoelectric layer and connected to a power supply wiring member of the drive electrode,
In the protective film forming step, the protective film having an opening for exposing the terminal drawn to the surface of the piezoelectric layer is formed,
After a conductive material having fluidity is attached to the terminal exposed in the opening, the conductive material is cured to form a convex bump for connecting the terminal and the wiring member. A method for manufacturing a droplet ejecting apparatus according to claim 5.

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