JP2009107299A - Manufacturing method of liquid discharge head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of liquid discharge head which enables it to suppress the variation of characteristic of a piezoelectric actuator for every product while relaxing the thermal stress applied to a piezoelectric layer. <P>SOLUTION: An inkjet head 10 has a flow path unit 11, an oscillating plate 2 and the piezoelectric layer 5. In the flow path unit 11, a pressure chamber 17 whose one surface is opened and a nozzle 19 communicating to the pressure chamber 17 are formed, and the oscillating plate 2 is fixed to one surface of the flow path unit so as to close the opening 17a of the pressure chamber 17. In the surface side which is the surface opposite to the flow path unit 11 of the oscillating plate 2, the piezoelectric layer 5 is provided. The inkjet head 10 having such a configuration is manufactured through a recess forming process which forms two or more recesses 8 in the part not corresponding to the pressure chamber in the rear surface opposite to the surface of the oscillating plate 2, and a piezoelectric layer forming process which forms the piezoelectric layer 5 by spurting out an aerosol of piezoelectric material to the area which includes the part corresponding to the pressure chamber 17 and the part corresponding to the recess 8 at the oscillating plate 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a droplet discharge head for discharging a liquid, such as an inkjet printer.

  A liquid discharge head such as an inkjet head is an apparatus that forms an image on a recording medium such as recording paper by discharging ink from nozzles. The ink jet head basically includes a flow path unit and a piezoelectric actuator. The flow path unit is formed with a pressure chamber opened on the upper surface and a nozzle communicating with the pressure chamber. The piezoelectric actuator includes a diaphragm laminated on the upper surface of the flow path unit and a piezoelectric layer formed on the surface of the diaphragm so as to close the opening of the pressure chamber with the back surface. When an electric field acts on the piezoelectric layer, the ink jet head deforms the piezoelectric layer to cause a pressure fluctuation in the pressure chamber, and discharges the liquid in the pressure chamber from the nozzle by the pressure fluctuation.

  In recent years, in a piezoelectric actuator, by using an aerosol deposition method (AD method) in which a carrier gas (aerosol) such as an inert gas in which fine particles of a piezoelectric material such as PZT are suspended is sprayed and deposited, from a metal such as SUS. A technique for forming a piezoelectric layer on a vibrating plate is proposed (see, for example, Patent Document 1).

Further, as a method of forming the piezoelectric layer by the AD method, Patent Document 2 discloses that the edge of the pressure chamber is located in a region that does not overlap with the pressure chamber in plan view on the upper surface of the diaphragm (surface opposite to the flow path unit 2). An ink jet head having a groove extending along the line is disclosed. By forming the groove in the diaphragm, the groove is also formed in the piezoelectric layer at a position corresponding to the groove of the diaphragm. It is disclosed that the occurrence of crosstalk is suppressed by the grooves of the piezoelectric layer.
JP 2006-54442 A JP 2006-96034 A

  By the way, the piezoelectric layer formed by the AD method is baked together with the vibration plate in a later annealing step, but according to the knowledge based on experiments by the present inventors, It has been found that a large thermal stress is generated in the piezoelectric layer, which causes cracks in the piezoelectric layer.

  That is, the piezoelectric layer formed on the diaphragm has an internal stress because it has a structure in which fine particles of the piezoelectric material are compressed, and the internal stress is once released by heating the piezoelectric layer. When it is further cooled to room temperature, the piezoelectric layer and the diaphragm contract together, and the linear expansion coefficient of the piezoelectric layer (PZT) is larger than the linear expansion coefficient of the diaphragm (metal). By being small, the piezoelectric layer has a state having an internal stress (a state having a thermal stress). And according to the knowledge based on experiments by the present inventors, it is known that the deformation characteristics of the piezoelectric layer are impaired by this thermal stress.

  Therefore, an object of the present invention is to provide a method for manufacturing a liquid discharge head that can relieve thermal stress acting on a piezoelectric layer.

  In the method for manufacturing a liquid discharge head according to the present invention, a pressure chamber and a nozzle that communicates with the pressure chamber are formed, and a flow path unit in which the pressure chamber is opened on one surface; A method for manufacturing a liquid ejection head, comprising: a diaphragm fixed to the one surface; and a piezoelectric layer formed on a surface side of the diaphragm opposite to the flow path unit. A recess forming step of forming a recess in a portion not corresponding to the pressure chamber on the back surface opposite to the front surface, and a portion corresponding to the pressure chamber and a portion corresponding to the recess on the surface side of the diaphragm A piezoelectric layer forming step of forming the piezoelectric layer by spraying an aerosol of a piezoelectric material on a region including the piezoelectric material.

  According to the present invention, the concave portion is formed on the back surface of the diaphragm, whereby the rigidity of the diaphragm is lowered and is easily deformed. Therefore, thermal deformation of the diaphragm during the annealing treatment is promoted, and it is possible to suppress the thermal deformation of the piezoelectric layer from being disturbed by the diaphragm. As a result, thermal stress generated in the piezoelectric layer can be relieved, and cracks can be prevented from occurring in the piezoelectric layer and the characteristics of the piezoelectric actuator can be prevented from being impaired.

  Further, in the present invention, since the thermal stress of the piezoelectric layer is reduced by forming a recess on the back surface of the diaphragm, a recess is formed on the surface of the diaphragm (the surface on which the piezoelectric layer is formed). You don't have to. If the piezoelectric layer is formed on the surface on the side where the concave portion is provided, there are portions where the fine particles are difficult to deposit due to the shadow of the concave portion, so the piezoelectric layer becomes thin or breaks at the portion corresponding to the concave portion, There is a risk of peeling from the location. However, according to the present invention, since the piezoelectric layer is formed on the surface opposite to the surface on which the concave portion is provided, the thermal stress can be alleviated while avoiding problems due to the fracture of the piezoelectric layer.

  In the above invention, the surface of the diaphragm is preferably formed flat. According to the present invention, since the surface of the diaphragm is formed flat, the spraying conditions of the aerosol on the surface of the diaphragm are substantially the same regardless of the part, and the surface of the diaphragm has a substantially uniform thickness. It becomes easy to form the piezoelectric layer. As a result, the piezoelectric actuator can be manufactured having a predetermined characteristic.

  In the above invention, the diaphragm includes a metal material, and is provided in a region corresponding to the recess on the surface of the diaphragm after the recess forming step and before the piezoelectric layer forming step. Preferably, the method further includes a diffusion prevention layer forming step of forming a diffusion prevention layer that prevents the metal material contained in the diaphragm from diffusing into the piezoelectric layer.

  According to the present invention, after the recess forming step and before the piezoelectric layer forming step, the metal material contained in the diaphragm is prevented from diffusing into the piezoelectric layer in the region corresponding to the recess on the surface of the diaphragm. A diffusion prevention layer is provided. By providing in this way, the diffusion preventing layer is provided on the side opposite to the surface on which the concave portion of the diaphragm is formed, so that it is formed to have a substantially uniform thickness even if formed by the AD method in the same manner as the piezoelectric layer. be able to. That is, the thickness of the diffusion preventing layer is not uneven or broken due to the concave portion. Accordingly, it is possible to manufacture a liquid discharge head that can prevent the metal material from diffusing from the region opposite to the concave portion into the piezoelectric layer.

  In the above invention, the flow path unit has a plurality of the pressure chambers that open on the one surface, communicates with the plurality of pressure chambers, and opens at a position that does not overlap the opening of the pressure chamber on the one surface. In the recess forming step, the recess is preferably formed in a portion corresponding to the common liquid chamber.

  According to the present invention, the recess is formed in the portion corresponding to the common liquid chamber. By forming the recess at such a position, the thermal stress generated in the piezoelectric layer during the annealing process can be relieved, and the capacity of the common liquid chamber can be increased by the recess. Therefore, since the common liquid chamber can supply liquid to many liquid discharge nozzles (pressure chambers) at once, the number of nozzles (pressure chambers) can be increased.

  In the above invention, it is preferable that in the recess forming step, a plurality of recesses extending in a predetermined direction and parallel to each other are formed.

  According to the present invention, by forming a plurality of recesses extending in a predetermined direction in parallel with each other, the thermal deformation of the diaphragm during the annealing process is promoted, and the aerosol of the piezoelectric material is sprayed on the surface of the diaphragm. The deformation of the region where the concave portion of the diaphragm is formed due to the impact by the aerosol is suppressed. As a result, unevenness can be prevented from occurring in the corresponding region of the concave portion on the surface of the diaphragm, and the spraying condition of the aerosol is substantially the same regardless of the portion, and a piezoelectric layer having a substantially uniform thickness is formed. Becomes easier.

  In the above invention, it is preferable that a vibration plate fixing step of fixing the vibration plate to the one surface of the flow path unit is further provided, and the piezoelectric layer forming step is performed after the vibration plate fixing step.

  According to the present invention, the flow path unit is fixed to the back surface of the vibration plate before forming the piezoelectric layer on the front surface side of the vibration plate in the piezoelectric layer forming step. Therefore, the diaphragm can receive the impact when the aerosol of the piezoelectric material is sprayed on the surface of the diaphragm together with the flow path unit, and can mitigate the impact applied to the diaphragm. Thereby, breakage and damage of the diaphragm can be suppressed.

  In the above invention, it is preferable that a vibration plate fixing step of fixing the vibration plate to the one surface of the flow path unit is further provided, and the piezoelectric layer forming step is performed before the vibration plate fixing step.

  According to the present invention, the piezoelectric layer is formed on the diaphragm before the diaphragm is fixed to one surface of the flow path unit. Therefore, if the annealing process is performed immediately after the piezoelectric layer is formed on the diaphragm, the annealing process is performed in a state where the back surface of the diaphragm is not constrained, and the thermal deformation of the diaphragm is further allowed, resulting in the piezoelectric layer. Thermal stress can be relieved more effectively.

  In the above invention, it is preferable that the piezoelectric layer forming step further includes an annealing treatment step of annealing the piezoelectric layer formed on the surface side of the diaphragm.

  ADVANTAGE OF THE INVENTION According to this invention, the droplet discharge head provided with the piezoelectric actuator with the favorable deformation | transformation characteristic which relieve | moderated the thermal stress which acts on a piezoelectric layer, avoiding the malfunction by the fracture | rupture of a piezoelectric layer can be applied.

In the following, with reference to FIGS. 1 to 14, a specific method of manufacturing a liquid discharge head according to the present invention and a plurality of embodiments of an inkjet head, which is a specific product manufactured by the manufacturing method, will be described. Each embodiment is similar in configuration to each other. Therefore, when describing each embodiment, only the configuration different from the configuration of the above-described embodiment will be described, and the same configuration as the configuration of the above-described embodiment will be denoted by the same reference numeral, and the detailed description thereof will be given. Omitted.
(First embodiment)
FIG. 1 is a plan view showing a part of the inkjet head 10 of the first embodiment. 2 is a cross-sectional view showing the inkjet head 10 taken along line II-II in FIG. The ink jet head 10 includes a flow path unit 11 that includes a plurality of pressure chambers 17 that contain ink and open on one surface, and a piezoelectric actuator 1 that is fixed on the flow path unit 11 so as to close the pressure chambers 17. I have.

  The flow path unit 11 has a flat plate shape as a whole and is formed in a rectangular shape in plan view, and includes a nozzle plate 12, a spacer plate 13, a flow path plate 14, a manifold plate 15, and a pressure chamber plate 16. Each of these plates 12 to 16 is laminated in the order shown above, and is fixed to each other with an epoxy thermosetting adhesive.

  The nozzle plate 12 is formed of a polyimide-based synthetic resin material, in which holes serving as a plurality of nozzles 19 for ejecting ink have a long side direction (hereinafter simply referred to as “X” Are aligned in a direction). By arranging the holes to be a plurality of nozzles 19 in this way, a nozzle row extending in the X direction in the flow path unit 11 is formed. The nozzle rows are arranged in a plurality of rows in the short side direction (hereinafter simply referred to as “Y direction”) of the flow path unit 11 in accordance with the type of color of ink ejected from the inkjet head 10 and the like. Each of the plurality of nozzles 19 is disposed in one-to-one correspondence with each of the plurality of pressure chambers 17. The spacer plate 13 and the flow path plate 14 are formed of, for example, stainless steel (SUS430), and include a plurality of nozzle flow paths 18 for communicating each of the plurality of nozzles 19 with the corresponding pressure chambers 17. Each hole is provided.

  The manifold plate 15 is also formed of stainless steel (SUS430), and holes serving as the plurality of nozzle flow paths 18 are provided therein. The pressure chamber plate 16 is also formed of stainless steel (SUS430), and there are provided holes serving as a plurality of pressure chambers 17 communicating with each of the plurality of nozzle channels 18. The holes serving as the pressure chambers 17 are aligned in the X direction so as to correspond to the plurality of nozzles 19 on a one-to-one basis, and a plurality of rows of the holes serving as the pressure chambers 17 are aligned in the Y direction. It has been.

  Further, manifold holes 15 a and 16 a communicating with each other are formed in the manifold plate 15 and the pressure chamber plate 16, and the two manifold holes 15 a and 16 a are closed by the flow path plate 14 and the piezoelectric actuator 1. It becomes the chamber 20 (common liquid chamber). The common ink chamber 20 is connected to an ink tank (not shown), and is connected to each pressure chamber 17 by a groove serving as a plurality of manifold channels 21 formed for each pressure chamber 17 in the pressure chamber plate 16. . The plurality of common ink chambers 20 are also formed in accordance with the type of color of ink ejected from the inkjet head 10, and the plurality of common ink chambers 20 are arranged in the Y direction.

  The flow path unit 11 configured as described above has a plurality of holes, manifold holes 16a, and a plurality of manifold flow paths 21 that serve as a plurality of pressure chambers 17 by fixing the piezoelectric actuator 1 to the surface on the pressure chamber plate 16 side. The plurality of pressure chambers 17, the common ink chamber 20, and the plurality of manifold channels 21 are configured. As a result, an ink flow path 22 is formed from the common ink chamber 20 connected to the ink tank to the nozzle 19 via the manifold flow path 21, the pressure chamber 17, and the nozzle flow path 18. Since the ink flow path 22 is fine and needs to be formed with high precision, the holes to be the ink flow path 22 are formed by etching with good workability, and the plates 12 to 16 are formed. Is made of metal so as to be eroded by etching.

  The piezoelectric actuator 1 laminated on the flow path unit 11 is formed in a rectangular shape having a slightly smaller outer dimension than the flow path unit 11, and the back surface facing the flow path unit 11 is the upper side of the pressure chamber 17 in FIG. The diaphragm 2 constituting a part of the wall surface of the first diaphragm, the diffusion prevention layer 3 formed on the surface of the diaphragm 2 opposite to the pressure chamber 17, and the diffusion prevention layer 3 on the opposite side of the diaphragm 2 A lower electrode 4 formed on the surface; a piezoelectric layer 5 laminated on a surface of the lower electrode 4 opposite to the diffusion preventing layer 3; and a surface of the piezoelectric layer 5 opposite to the lower electrode 4 The upper electrode 6 is provided. The long side direction of the piezoelectric actuator 1 is substantially coincident with the X direction, and the short side direction is substantially coincident with the Y direction.

  The diaphragm 2 is formed in a rectangular shape, and is fixed to the surface of the flow path unit 11 on the pressure chamber plate 16 side by thermocompression bonding so as to cover the entire upper surface of the flow path unit 11. By fixing the diaphragm 2 to the flow path unit 11, the holes forming the pressure chambers 17, the manifold holes 15 a and 16 a, and the holes forming the manifold flow paths 21 are closed. A common ink chamber 20 and a plurality of manifold channels 21 are formed.

  On the back surface of the diaphragm 2, a plurality of concave portions 8 (slits) are provided for each common ink chamber 20 so as to face the common ink chamber 20. That is, the plurality of recesses 8 are formed in a portion not corresponding to the pressure chamber in a plan view as viewed in the direction opposite to the stacking direction in which the piezoelectric actuator 1 is stacked on the flow path unit 11. The plurality of recesses 8 are elongated in the X direction and are arranged at short intervals in the Y direction. By arranging the plurality of recesses 8 so as to face the common ink chamber 20 in this way, the capacity of the common ink chamber 20 can be increased. Accordingly, the common ink chamber 20 can supply ink to many nozzles 19 (pressure chambers 17) at a time, and can cope with the increase in the number of nozzles 19 (pressure chambers 17).

  The diaphragm 2 is made of the same metal material as the manifold plate 15, the flow path plate 14, and the pressure chamber plate 16 constituting the flow path unit 11, for example, stainless steel (SUS430). Warpage when the plate 2 is thermocompression bonded to the flow path unit 11 can be prevented.

  The surface of the diaphragm 2 is formed flat, and the diffusion prevention layer 3 is formed over the entire surface. That is, the diffusion preventing layer 3 is formed in a region corresponding to the concave portion 8 on the surface of the diaphragm 2. The diffusion prevention layer 3 is formed by an aerosol deposition method (abbreviation: AD method) in which an aerosol containing a piezoelectric material such as alumina and zirconia is sprayed on the surface of the diaphragm 2. However, the forming method is not limited to the AD method, and may be a sol-gel method, a CVD method, a sputtering method, a vapor deposition method, an ion plating method, or the like. The diffusion prevention layer 3 has a function of preventing the metal material contained in the diaphragm 2 from diffusing into the piezoelectric layer 5.

  A lower electrode 4 is formed over the entire surface of the diffusion prevention layer 3 on the side opposite to the diaphragm 2. However, the lower electrode 4 is not limited to the one formed over the entire surface. The lower electrode 4 is used as a ground electrode by being connected to the ground of a drive circuit IC (not shown). The lower electrode 4 is formed by evaporating, for example, Au on the diffusion preventing layer 3.

  A piezoelectric layer 5 made of a ferroelectric piezoelectric ceramic material such as lead zirconate titanate (PZT) is formed on the surface of the lower electrode 4 opposite to the diffusion preventing layer 3. The lower electrode 4 is laminated with a uniform thickness on the entire opposite surface. The piezoelectric layer 5 is also formed by the AD method, and is subjected to a polarization process so as to be polarized in the thickness direction.

  Furthermore, a plurality of upper electrodes 6 and a plurality of lead portions 9 are provided on the surface of the piezoelectric layer 5 opposite to the lower electrode 4. Each of the plurality of upper electrodes 6 is provided in a region corresponding to the opening 17 a of each pressure chamber 17, and each lead portion 9 is commonly connected to each pressure chamber 17 via a manifold channel 21. In the region corresponding to the ink chamber 20, it is provided corresponding to each of the plurality of upper electrodes 6. The upper electrode 6 is connected to the drive circuit IC via the corresponding lead portion 9, and is used as the drive electrode. The plurality of upper electrodes 6 thus configured form a row extending in the X direction so as to correspond to each pressure chamber 17, and this row is arranged in the Y direction. The plurality of lead portions 9 are aligned in the X direction along the plurality of upper electrodes 6, and a plurality of concave portions 8 are disposed between the adjacent lead portions 9.

  In the inkjet head 10 configured in this manner, when a predetermined drive signal is issued from the drive circuit IC to the upper electrode 6, the potential of the upper electrode 6 becomes higher than that of the lower electrode 4, and the polarization direction of the piezoelectric layer 5 ( An electric field is applied in the thickness direction). Then, the piezoelectric layer 5 expands in the thickness direction and contracts in the surface direction. Thereby, in the piezoelectric layer 5 and the diaphragm 2 (that is, the piezoelectric actuator 1), a region corresponding to the opening 17a of the pressure chamber 17 is locally deformed so as to protrude toward the pressure chamber 17 (unimorph deformation). For this reason, the volume of the pressure chamber 17 is reduced, the pressure of the ink is increased, and the ink is ejected from the nozzle 19. Thereafter, when the upper electrode 6 is returned to the same potential as the lower electrode 4, the piezoelectric layer 5 and the diaphragm 2 return to their original shapes, and the volume of the pressure chamber 17 returns to the original volume. Suction is performed from the common ink chamber 20 in communication through the manifold channel 21. Next, a method for manufacturing the inkjet head 10 will be described.

  FIG. 3 is a flowchart showing the procedure of the method for manufacturing the inkjet head 10. FIG. 4 is a diagram illustrating a procedure of a method for manufacturing the inkjet head 10. 4A is the state in step S1 of FIG. 3, FIG. 4B is the state in step S2 of FIG. 3, FIG. 4C is the state in step S3 of FIG. 3, and FIG. FIG. 4E shows the state in step S4, FIG. 4E shows the state in step S5 in FIG. 3, and FIG. 4F shows the state in step S7 in FIG. In FIG. 4, the part surrounded by a circle is shown enlarged.

  First, as shown to Fig.4 (a), the some recessed part 8 is formed in the back surface of the diaphragm 2 by an etching (step S1, recessed part formation process). The plurality of recesses 8 may be formed simultaneously when the diaphragm 2 is cut out from the stainless steel plate. Next, the nozzle 19, the nozzle flow path 18 and the pressure chamber 17 are etched in the stainless steel plate, respectively, and the nozzle plate 12, spacer plate 13, flow path plate 14, manifold plate 15, pressure chamber plate 16 (etching parts) ). Then, by fixing these plates 12 to 16 in a stacked state, the flow path unit 11 in which the ink flow path 22 is formed is formed (flow path unit forming step).

  Next, as shown in FIG. 4B, the diaphragm 2 formed in step S1 is opposed to the surface on the pressure chamber plate 16 side of the flow path unit 11, and the rear surface of the diaphragm 2 is opposed to the surface. The diaphragm 2 is stacked in the state. At this time, the diaphragm 2 is aligned so that the plurality of concave portions 8 face the corresponding common ink chamber 20. After superposition in such a state of alignment, the pressure chambers 17 and the common ink chambers 20 are closed by the vibration plate 2 (step S2, vibration plate fixing step).

  After the diaphragm fixing step, as shown in FIG. 4C, the diffusion prevention layer 3 is formed on the surface of the diaphragm 2 by the AD method (step S3). Details of the AD method will be described later. Then, as shown in FIG. 4D, the lower electrode 4 is formed on the diffusion preventing layer 3 (step S4, lower electrode forming step). The lower electrode 4 can be formed, for example, by forming an Au thin film by vapor deposition.

  Next, as shown in FIG. 4E, the piezoelectric layer 5 is formed by the AD method (step S5, piezoelectric layer forming step). Hereinafter, the AD method will be described. FIG. 5 is a schematic view showing a film forming apparatus 30 for forming the piezoelectric layer 5 (diffusion prevention layer 3). The film forming apparatus 30 includes an aerosol generator 31 that forms an aerosol Z by dispersing material particles M in a carrier gas, and a film forming chamber 35 that causes the aerosol Z to be ejected from an ejection nozzle 37 and adhered to a substrate. ing.

  The aerosol generator 31 includes an aerosol chamber 32 that can accommodate the material particles M therein, and a vibration device 33 that is attached to the aerosol chamber 32 and vibrates the aerosol chamber 32. A gas cylinder B for introducing a carrier gas is connected to the aerosol chamber 32 via an introduction pipe 34. The distal end of the introduction tube 34 is located near the bottom surface in the aerosol chamber 32 and is buried in the material particles M. As the carrier gas, for example, an inert gas such as helium, argon, or nitrogen, air, oxygen, or the like can be used.

  The film forming chamber 35 is provided with a stage 36 for attaching a substrate on which the piezoelectric layer 5 (diffusion prevention layer 3) is attached, and an injection nozzle 37 provided below the stage 36. The injection nozzle 37 is connected to the aerosol chamber 32 via an aerosol supply pipe 38, and the aerosol Z in the aerosol chamber 32 is supplied to the injection nozzle 37 through the aerosol supply pipe 38. In addition, a vacuum pump P is connected to the film forming chamber 35 via a powder recovery device 39 so that the inside thereof can be depressurized.

  When the piezoelectric layer 5 (diffusion prevention layer 3) is formed using the film forming apparatus 30, first, the diaphragm 2 on which the lower electrode 4 is formed in step S4 is directed downward with the lower electrode 4 side facing downward. (In the case of the diffusion preventing layer 3), the diaphragm 2 is set on the stage 36 with its back surface facing downward. Next, the material particles M are introduced into the aerosol chamber 32. As the material particle M, for example, lead zirconate titanate (PZT) (in the case of the diffusion prevention layer 3, for example, alumina) can be used.

  And carrier gas is introduce | transduced from the gas cylinder B, and the material particle M is made to soar by the gas pressure. At the same time, the aerosol chamber 32 is vibrated by the vibration device 33, whereby the material particles M and the carrier gas are mixed to generate the aerosol Z. Then, by depressurizing the inside of the film forming chamber 35 with the vacuum pump P, the aerosol Z in the aerosol chamber 32 is accelerated from the injection nozzle 37 while being accelerated at a high speed by the differential pressure between the aerosol chamber 32 and the film forming chamber 35. Erupt. The material particles M contained in the ejected aerosol Z collide with the diaphragm 2 and are deposited to form the piezoelectric layer 5 (diffusion prevention layer 3).

  Subsequently, in order to obtain necessary piezoelectric characteristics, the formed piezoelectric layer 5 is annealed (step S6, firing step). At this time, since the diffusion preventing layer 3 is provided over the entire surface of the diaphragm 2 between the piezoelectric layer 5 and the diaphragm 2, a metal material such as Fe contained in the diaphragm 2 is not present in the piezoelectric layer 5. Can be prevented from spreading to.

  Then, as shown in FIG. 4F, the upper electrode 6 and a plurality of lead portions 9 connected to each upper electrode 6 are formed on the surface of the piezoelectric layer 5 opposite to the lower electrode (Step S7, upper electrode formation). Process). In order to form the upper electrode 6 and the lead portion 9, for example, a conductor film may be formed over the entire surface of the piezoelectric layer 5 and then formed into a predetermined pattern using a photolithography etching method. It may be formed directly on the upper surface of the piezoelectric layer 5 by screen printing. Finally, an electric field stronger than that in the normal ink ejection operation is applied between the upper electrode 6 and the lower electrode 4 to polarize the piezoelectric layer 5 between both electrodes in the thickness direction (polarization process). Thereby, the inkjet head 10 is completed.

  According to such a manufacturing method of the ink jet head 10, the concave portion 8 is formed on the back surface of the diaphragm 2, and the rigidity of the diaphragm 2 is lowered and easily deformed. Therefore, thermal deformation of the diaphragm 2 during the annealing treatment is promoted, and it is possible to suppress the thermal deformation of the piezoelectric layer 5 from being disturbed by the diaphragm 2. As a result, the thermal stress generated in the piezoelectric layer 5 can be relaxed, and cracks in the piezoelectric layer 5 and the characteristics of the piezoelectric actuator can be prevented from being damaged.

  Further, since the plurality of concave portions 8 are formed on the back surface of the diaphragm 2, the thermal stress of the piezoelectric layer 5 can be relaxed with the surface of the diaphragm 2 being flat on the back surface of the diaphragm 2. Further, when the piezoelectric layer is formed on the surface on which the concave portion is provided, a portion in which fine particles are difficult to deposit is generated due to the shadow of the concave portion. By thus forming the surface of the diaphragm 2 flat, the diaphragm 2 The spraying conditions of the aerosol on the surface side are substantially the same regardless of the portion, and the diffusion preventing layer 3 and the piezoelectric layer 5 having a substantially uniform thickness can be formed on the surface. As a result, it is possible to alleviate thermal stress while avoiding problems due to breakage of the diffusion preventing layer 3 and the piezoelectric layer 5.

  Further, the diffusion preventing layer 3 can be formed without any gap over the entire surface of the diaphragm 2 (the area opposite to the plurality of recesses 8) and can be formed to have a substantially uniform thickness. Thus, the inkjet head 10 that can prevent the metal material from diffusing into the piezoelectric layer 5 can be manufactured.

  Furthermore, by arranging the plurality of recesses 8 so as to face the liquid chamber, the opening end portions of the plurality of recesses 8 are not constrained, and each recess 8 is easily deformed. Therefore, the thermal expansion of the diaphragm 2 can be further promoted during the annealing process, and the thermal stress generated in the piezoelectric layer 5 can be further relaxed. Further, by forming the concave portion 8, the ink jet head 10 having a large capacity of the common ink chamber 20 can be manufactured.

  Further, by forming a plurality of recesses 8, the thermal deformation of the vibration plate 2 during the annealing process is allowed, and the vibration of the vibration plate 2 due to the impact when the aerosol of the piezoelectric material is sprayed on the surface of the vibration plate 2. The deformation of the region where the plurality of recesses 8 are formed is suppressed. As a result, unevenness can be prevented from occurring in the region corresponding to the plurality of recesses 8 on the surface of the diaphragm 2, and the aerosol spraying conditions are substantially the same regardless of the location, and the piezoelectric layer has a substantially uniform thickness. It becomes easy to form.

Further, before the diffusion preventing layer 3 and the piezoelectric layer 5 are formed on the front surface side of the vibration plate 2 in the piezoelectric layer forming step, the flow path unit 11 is fixed to the rear surface of the vibration plate 2. Therefore, the diaphragm 2 can receive an impact when the aerosol of the piezoelectric material is sprayed on the surface of the diaphragm 2 together with the flow path unit, and can mitigate the impact applied to the diaphragm 2. Thereby, breakage and damage of the diaphragm 2 can be suppressed.
(Second Embodiment)
FIG. 6 is a plan view showing a part of the inkjet head 10A of the second embodiment. FIG. 7 is a cross-sectional view showing the inkjet head 10A cut along line VII-VII in FIG. A piezoelectric actuator 1A provided in the ink jet head 10A of the second embodiment includes a diaphragm 2A, a piezoelectric layer 5, and an upper electrode 6, and is fixed to the upper surface of the flow path unit 11.

  The diaphragm 2 </ b> A is formed in a rectangular shape like the diaphragm 2 of the first embodiment, and the back surface thereof is fixed to the upper surface of the flow path unit 11. A recess 8A extending in the X direction is formed on the back surface of the diaphragm 2A so as to face the common ink chamber 20. That is, the concave portion 8 </ b> A is formed in a portion not corresponding to the pressure chamber in a plan view seen in the direction opposite to the stacking direction in which the piezoelectric actuator 1 is stacked on the flow path unit 11. Thus, the capacity of the common ink chamber 20 can be increased also by the recess 8A.

  The diaphragm 2A is electrically connected to the ground of the drive circuit IC and used as a lower electrode. The surface of the diaphragm 2A is also formed flat, the piezoelectric layer 5 is formed over the entire surface, and the upper electrode 6 and the lead portion 9 are further formed thereon. Next, a method for manufacturing the inkjet head 10 will be described.

  FIG. 8 is a flowchart showing the procedure of the method for manufacturing the inkjet head 10. FIG. 9 is a diagram illustrating a procedure of a method for manufacturing the inkjet head 10. 9A is the state in step S11 in FIG. 8, FIG. 9B is the state in step S12 in FIG. 8, FIG. 9C is the state in step S13 in FIG. 8, and FIG. It is the figure which each showed the state in step S15. In FIG. 9, the circled portion is shown in an enlarged manner.

  First, as shown in FIG. 9A, a recess 8A is formed on the back surface of the diaphragm 2 by etching (step S11, recess forming step). Next, similarly to step S2, the flow path unit 11 is formed (flow path unit formation step), and as shown in FIG. 9B, the recess 8A is formed in the common ink chamber in the diaphragm 2 formed in step S11. In a state of being aligned so as to face 20, they are stacked and fixed (step S 12, diaphragm fixing step).

  Next, as in step S5, as shown in FIG. 9C, the piezoelectric layer 5 is formed by the AD method (step S13, piezoelectric layer forming step). Subsequently, similarly to step S6, the formed piezoelectric layer 5 is annealed (step S14, firing step). Then, as in step S7, as shown in FIG. 4F, the upper electrode 6 and a plurality of lead portions 9 are formed on the upper surface of the piezoelectric layer 5 (step S15, upper electrode forming step). Finally, an electric field stronger than that in the normal ink ejection operation is applied between the upper electrode 6 and the diaphragm 2A to polarize the piezoelectric layer 5 between both electrodes in the thickness direction (polarization process). Thereby, the inkjet head 10A is completed.

By manufacturing the inkjet head 10 </ b> A by such a method, the same operational effects as when the inkjet head 10 of the first embodiment is manufactured are obtained except for the operational effects related to the diffusion prevention layer 3 and the plurality of recesses 8.
(Third embodiment)
FIG. 10 is a plan view showing a part of the inkjet head 10B of the third embodiment. FIG. 11 is a cross-sectional view showing the inkjet head 10B cut along line XI-XI in FIG. The piezoelectric actuator 1B provided in the ink jet head 10B of the third embodiment includes a diaphragm 2B, a lower electrode 4, a piezoelectric layer 5, and an upper electrode 6, and is fixed to the upper surface of the flow path unit 11.

  The diaphragm 2B is formed in a rectangular shape like the diaphragm 2 of the first embodiment, and the back surface thereof is fixed to the upper surface of the flow path unit 11. A plurality of recesses 8B are formed on the back surface of the diaphragm 2B so as to face the common ink chamber 20. That is, a plurality of recesses 8 </ b> B are formed in a portion not corresponding to the pressure chamber in a plan view seen in the direction opposite to the stacking direction in which the piezoelectric actuator 1 is stacked on the flow path unit 11. The plurality of recesses 8B extend elongated in the Y direction, and are arranged at short intervals in the X direction.

The inkjet head 10B can be manufactured by the same manufacturing method as the inkjet head 10 of the first embodiment. By manufacturing the inkjet head 10B by this manufacturing method, the manufacturing method of the inkjet head 10 of the first embodiment. Has the same effect as.
(Fourth embodiment)
FIG. 12 is a plan view showing a part of the inkjet head 10C of the fourth embodiment. FIG. 13 is a cross-sectional view showing the inkjet head 10C cut along line XIII-XIII in FIG. The inkjet head 10C according to the fourth embodiment includes a flow path unit 11C and a piezoelectric actuator 1C. The channel unit 11C has a flat plate shape as a whole and is formed in a rectangular shape in plan view, and includes a nozzle plate 12, a spacer plate 13, a manifold plate 15C, a channel plate 14C, and a pressure chamber plate 16C. Each plate 12-16C is laminated | stacked in the order shown previously, and is mutually fixed with the epoxy-type thermosetting adhesive agent.

  The manifold plate 15C is formed of, for example, stainless steel (SUS430), in which holes serving as a plurality of nozzle channels 18 are provided, and connected to an ink tank (not shown) to store a common ink chamber. A hole of 20C is provided. The common ink chamber 20C is configured by closing a hole that becomes the common ink chamber 20C by sandwiching the manifold plate 15C between the flow path plate 14C and the spacer plate 13.

  The flow path plate 14C is also formed of stainless steel (SUS430), and is provided with holes that serve as the plurality of nozzle flow paths 18, respectively. The pressure chamber plate 16 </ b> C is also formed of stainless steel (SUS430), and there are provided holes serving as a plurality of pressure chambers 17 communicating with the respective nozzles 19 through the plurality of nozzle flow paths 18. These holes serving as the pressure chambers 17 communicate with the common ink chamber 20C through holes serving as a plurality of manifold channels 21C provided in the channel plate 14C.

  By forming in this way, the common ink chamber 20C connected to the ink tank is arranged below the paper surface of FIG. 13 of each pressure chamber 17, and from the common ink chamber 20C, the manifold channel 21C, the pressure chamber 17, an ink flow path 22 </ b> C extending from the nozzle flow path 18 to the nozzle 19 is formed.

  The piezoelectric actuator 1C stacked on the flow path unit 11C includes a diaphragm 2C, a diffusion prevention layer 3, a lower electrode 4, a piezoelectric layer 5, and an upper electrode 6. The diaphragm 2C is formed in a rectangular shape, and is fixed to the upper surface of the flow path unit 11 (the surface on the pressure chamber plate 16 side). By fixing the diaphragm 2C to the flow path unit 11, the holes forming the pressure chambers 17 are closed, and a plurality of pressure chambers 17 are formed. On the back surface of the diaphragm 2C, a concave portion 8C extending in the X direction is disposed in a portion not corresponding to the pressure chamber in plan view.

  When the concave portion 8C is thus formed on the back surface of the diaphragm 2C, the concave portion 8C is disposed so as to face the pressure chamber plate 16, and the opening end portion of the concave portion 8C is fixed and restrained to the pressure chamber plate 16. The However, since the thermal expansion of the diaphragm 2C facing inward of the concave portion 8C is allowed, except for the effects related to the case where the plurality of concave portions 8 are arranged, the ink jet 10 according to the first embodiment is manufactured by the manufacturing method. Has the same effect as.

  FIG. 14 is a flowchart showing a procedure of a different manufacturing method of the inkjet head 10. In the first to fourth embodiments, the diaphragms 2, 2A, 2B, 2C are fixed to the flow path unit 11, and then the aerosol is sprayed on the surfaces of the diaphragms 2, 2A, 2B, 2C, so that the piezoelectric layer 5 is formed. Although formed, a plurality of recesses 8 are formed in the diaphragm 2 as shown in FIG. 14 (step S21), and then fixed to the flow path unit 11, that is, before the flow path unit forming step. The diffusion prevention layer 3, the lower electrode 4, and the piezoelectric layer 5 may be formed on the surface side of the diaphragm 2 and fired (steps S22 to S25). Thereafter, the flow path unit 11 is fixed to the back side of the diaphragm 2 (step S26), and the upper electrode 6 is formed (step S27). With this configuration, the vicinity of the plurality of recesses 8 is not constrained at the time of firing, so that thermal expansion of the diaphragm 2 is further promoted. Thereby, the thermal stress generated in the piezoelectric layer 5 can be relaxed more efficiently.

  Each of the above-described embodiments applies the present invention to an inkjet head that ejects ink, but it ejects liquids other than ink, such as colored liquids, and not only recording paper as a recording medium, You may apply to the liquid discharge apparatus using cloth, a resin sheet, etc., and the same effect is acquired.

  The liquid discharge head according to the present invention has an excellent effect of suppressing variation in the characteristics of the piezoelectric actuator for each product while relaxing the thermal stress acting on the piezoelectric layer. It is useful when applied to a discharging apparatus.

It is a top view which shows a part of inkjet head of 1st Embodiment. It is sectional drawing which cut | disconnects and shows an inkjet head by the II-II line | wire of FIG. It is a flowchart which shows the procedure of the manufacturing method of an inkjet head. It is the figure which showed the procedure of the manufacturing method of an inkjet head. It is the schematic which shows the film-forming apparatus for forming a piezoelectric layer (diffusion prevention layer). It is a top view which shows a part of inkjet head of 2nd Embodiment. It is sectional drawing which cut | disconnects and shows an inkjet head by the VII-VII line of FIG. It is a flowchart which shows the procedure of the manufacturing method of an inkjet head. It is the figure which showed the procedure of the manufacturing method of an inkjet head. It is a top view which shows a part of inkjet head of 3rd Embodiment. It is sectional drawing which cut | disconnects and shows an inkjet head by the XI-XI line of FIG. It is a top view which shows a part of inkjet head of 4th Embodiment. It is sectional drawing which cut | disconnects and shows an inkjet head by the XIII-XIII line | wire of FIG. It is a flowchart which shows the procedure of the manufacturing method from which an inkjet head differs.

Explanation of symbols

1, 1A, 1B, 1C Piezoelectric actuator 2, 2A, 2B, 2C Diaphragm 3 Diffusion prevention layer 5 Piezoelectric layer 8, 8A, 8B, 8C Recess 10, 10, 10A, 10B, 10C Inkjet head 11, 11C Flow path unit 17 Pressure Chamber 19 Nozzle 20, 20C Common ink chamber

Claims (8)

A pressure chamber and a nozzle communicating with the pressure chamber are formed, the flow channel unit in which the pressure chamber is opened on one surface, the diaphragm fixed to the one surface of the flow channel unit so as to close the opening, A method of manufacturing a liquid discharge head comprising: a piezoelectric layer formed on a surface side that is a surface opposite to the flow path unit of the vibration plate,
A recess forming step of forming a recess in a portion not corresponding to the pressure chamber on the back surface opposite to the front surface of the diaphragm;
A piezoelectric layer forming step of forming the piezoelectric layer by spraying an aerosol of a piezoelectric material on a region including a portion corresponding to the pressure chamber and a portion corresponding to the concave portion on the surface side of the diaphragm. A method of manufacturing a liquid discharge head.   The method of manufacturing a liquid ejection head according to claim 1, wherein the surface of the diaphragm is formed flat. The diaphragm includes a metal material,
After the recess forming step and before the piezoelectric layer forming step, the metal material contained in the diaphragm diffuses into the piezoelectric layer in a region corresponding to the recess on the surface of the diaphragm. The method of manufacturing a liquid discharge head according to claim 1, further comprising a diffusion prevention layer forming step of forming a diffusion prevention layer to prevent. The flow path unit has a plurality of the pressure chambers that open on the one surface, communicates with each of the plurality of pressure chambers, and opens at a position that does not overlap the opening of the pressure chamber on the one surface. Has a chamber,
4. The method of manufacturing a liquid ejection head according to claim 1, wherein, in the recess forming step, the recess is formed in a portion corresponding to the common liquid chamber. 5.   5. The method of manufacturing a liquid ejection head according to claim 1, wherein in the recess forming step, a plurality of recesses extending in a predetermined direction and parallel to each other are formed. A vibration plate fixing step of fixing the vibration plate to the one surface of the flow path unit;
6. The method of manufacturing a liquid discharge head according to claim 1, wherein the piezoelectric layer forming step is performed after the vibration plate fixing step. A vibration plate fixing step of fixing the vibration plate to the one surface of the flow path unit;
The method for manufacturing a liquid ejection head according to claim 1, wherein the piezoelectric layer forming step is performed before the vibration plate fixing step.   The liquid ejection according to claim 1, further comprising an annealing treatment step of annealing the piezoelectric layer formed on the surface side of the diaphragm in the piezoelectric layer forming step. Manufacturing method of the head.

Images