JP4816002B2 - Piezoelectric actuator manufacturing method, liquid transfer device manufacturing method, and piezoelectric actuator manufacturing apparatus - Google Patents

Description

  The present invention relates to a method for manufacturing a piezoelectric actuator for a liquid transfer device, a method for manufacturing a liquid transfer device, and a device for manufacturing a piezoelectric actuator.

  A liquid transfer device such as an inkjet head that discharges ink from nozzles includes an actuator that applies pressure to the liquid to transfer the liquid. Various actuators can be used as this actuator. Among these actuators, a piezoelectric layer made of a ferroelectric piezoelectric material such as lead zirconate titanate (PZT) is used. Piezoelectric actuators that drive a target by utilizing the deformation of are widely used. For example, a piezoelectric actuator of an ink jet head is generally disposed on both sides of a vibration plate that covers a pressure chamber in which ink is stored, a piezoelectric layer that is disposed on the opposite side of the pressure chamber of the vibration plate, and a piezoelectric layer. Two electrodes.

  Here, for example, an aerosol deposition method (AD method, for example, see Patent Document 1) in which particles of a very small piezoelectric material are sprayed onto a substrate in a state of being mixed with a carrier gas, collided at high speed, and deposited on the substrate. If a sputtering method (for example, refer to Patent Document 2), in which particles of the target are deposited on the substrate by ionizing argon or the like and colliding with the target, the piezoelectric layer is formed with a relatively uniform thickness. Can do. Alternatively, a piezoelectric layer can be formed by attaching a piezoelectric sheet obtained by firing a green sheet such as PZT to a diaphragm (see, for example, Patent Document 3).

  In this piezoelectric actuator, when a driving voltage is applied to one electrode, an electric field in the thickness direction acts on the piezoelectric layer sandwiched between the two electrodes, and this piezoelectric layer extends in the thickness direction and is parallel to the surface. Shrink in the direction. At this time, the diaphragm is also deformed along with the deformation of the piezoelectric layer, so that the volume of the pressure chamber is changed and pressure is applied to the ink in the pressure chamber.

JP 2003-142750 A Japanese Patent Laid-Open No. 10-286953 JP 2004-284109 A

  By the way, for example, when the diaphragm is made of a metal material, the thickness may be slightly different for each lot of sheet-like metal plates. In this case, the thickness of the diaphragm is different for each actuator. It will vary. As described above, if the thickness of the diaphragm varies, the thickness may not be different for each actuator by using the above-mentioned AD method, sputtering method, etc., or using the same thickness piezoelectric sheet. Even if the piezoelectric layer can be formed, characteristics such as the deformation amount of the diaphragm and the rigidity of the piezoelectric actuator are different for each actuator. If so, the droplet volume and droplet velocity of the ink ejected from the nozzles are different for each head, and the print quality varies, resulting in a decrease in yield.

  It is also conceivable to adjust the drive voltage and drive waveform conditions of the drive signal supplied to the electrodes for each head to correct the thickness variation of the diaphragm. However, these conditions are corrected for each head. This is complicated, and this correction may be difficult depending on the specifications of the drive device that applies the drive voltage to the electrodes.

  An object of the present invention is to provide a method for manufacturing a piezoelectric actuator, a method for manufacturing a liquid transfer device, and a device for manufacturing such a piezoelectric actuator capable of correcting variations in the thickness of the diaphragm by the thickness of the piezoelectric layer. Is to provide. Further, according to the present invention, when mass-producing piezoelectric actuators, even if there are variations in the thickness of the diaphragm as a part, it is possible to easily manufacture a piezoelectric actuator having a constant and desired ejection characteristics. Another object of the present invention is to provide a method for manufacturing a piezoelectric actuator.

Means for Solving the Problems and Effects of the Invention

According to the first aspect of the present invention, the diaphragm provided on one surface of the flow path unit having the pressure chamber and covering the pressure chamber, and the piezoelectric layer disposed on the opposite side of the pressure chamber of the diaphragm A method for manufacturing a piezoelectric actuator for a liquid transfer device, comprising two electrodes disposed on both sides of the piezoelectric layer and sandwiching the piezoelectric layer, wherein the thickness of the diaphragm is measured. And a piezoelectric layer for determining the thickness of the piezoelectric layer based on a deviation amount of the diaphragm thickness measured in the diaphragm thickness measuring step with respect to a preset reference thickness of the diaphragm A thickness determining step, and a piezoelectric layer forming step in which the piezoelectric layer having the thickness determined in the piezoelectric layer thickness determining step is provided on a side opposite to the pressure chamber of the diaphragm, and the piezoelectric layer thickness In the determining step, the piezoelectric layer has a predetermined reference thickness. The relationship between the amount of deviation of the diaphragm and the amount of correction of the piezoelectric layer is related to the amount of deformation of the diaphragm when a predetermined voltage is applied to one of the electrodes. The relational expression 1 and the second relational expression showing the relation between the amount of deviation of the thickness of the diaphragm and the correction amount of the piezoelectric layer relating to the rigidity of the actuator are determined so as to satisfy both , The diaphragm is made of a material having an elastic modulus equal to or greater than the material of the piezoelectric layer, and when the thickness deviation amount of the diaphragm is ΔTv and the correction amount of the piezoelectric layer is ΔTp, the diaphragm The first relational expression regarding the deformation amount is (−0.75 × ΔTv) ≦ ΔTp ≦ (−1.05 * ΔTv), and the second relational expression regarding the rigidity of the actuator is (−1 .0 × .DELTA.TV) piezoelectric activator is ≦ ΔTp ≦ (-1.3 × ΔTv) Manufacturing method of eta is provided.

  If the thickness of the vibration plate varies for each piezoelectric actuator, the amount of deformation of the vibration plate, the rigidity of the piezoelectric actuator, etc., which affect the liquid transfer amount and transfer speed of the liquid transfer device, will vary among the piezoelectric actuators. It will be different. However, according to the present invention, an appropriate thickness of the piezoelectric layer is determined based on the deviation amount of the actually measured diaphragm thickness from the reference thickness, and the piezoelectric layer having the determined thickness is determined. Since it is provided on the surface of the diaphragm opposite to the pressure chamber, when the thickness of the diaphragm deviates from the reference thickness, the deviation can be easily corrected by the thickness of the piezoelectric layer. Yield is also improved. In the present invention, in addition to the form in which two electrodes are formed separately from the diaphragm, the diaphragm is formed of a conductive material, and the form in which the diaphragm serves as one of the two electrodes is also included. .

In the method for manufacturing a piezoelectric actuator of the present invention, the diaphragm is made of a conductive material and serves as one of the two electrodes. In the piezoelectric layer forming step, the piezoelectric layer is The diaphragm may be formed in contact with a surface opposite to the pressure chamber, and the other of the two electrodes may be formed in contact with a surface of the piezoelectric layer opposite to the diaphragm. In this way, the pressure of the diaphragm can be reduced without interposing another layer (for example, an electrode layer or an insulating material layer that insulates the electrode from the diaphragm) between the piezoelectric layer and the diaphragm. Since it is formed directly on the surface opposite to the chamber, the variation in the thickness of the diaphragm can be accurately corrected by adjusting the thickness of the piezoelectric layer. Further, since the diaphragm also serves as one of the two electrodes, the process of forming the one electrode separately from the diaphragm can be omitted, and the manufacturing process can be simplified.

  In the piezoelectric actuator manufacturing method of the present invention, in the piezoelectric layer forming step, the piezoelectric layer may be formed on the diaphragm by an aerosol deposition method, a sputtering method, or a chemical vapor deposition method. By using these methods, the piezoelectric layer having the thickness determined in the piezoelectric layer thickness determining step can be easily formed. Among these, the aerosol deposition method is suitable for manufacturing. In addition to forming the piezoelectric layer on the vibration plate, a material previously formed in a sheet shape may be bonded to the vibration plate.

According to the second aspect of the present invention, a flow path unit having a pressure chamber, a diaphragm provided on one surface of the flow path unit and covering the pressure chamber, the opposite side of the vibration chamber from the pressure chamber And a piezoelectric actuator having two electrodes respectively disposed on both sides of the piezoelectric layer, and a diaphragm for measuring the thickness of the diaphragm The thickness of the piezoelectric layer is determined based on a thickness measurement step and a deviation amount of the diaphragm thickness measured in the diaphragm thickness measurement step with respect to a preset reference thickness of the diaphragm. A piezoelectric layer thickness determining step, and a piezoelectric layer forming step in which the piezoelectric layer having the thickness determined in the piezoelectric layer thickness determining step is provided on the side opposite to the pressure chamber of the diaphragm, In the layer thickness determining step, a predetermined base of the piezoelectric layer is set. The relationship between the amount of deviation of the diaphragm and the amount of correction of the piezoelectric layer is related to the amount of deformation of the diaphragm when a predetermined voltage is applied to one of the electrodes. a first relation formula showing relates rigidity of the actuator, the second relation formula showing the amount of deviation of the thickness of the diaphragm and the relationship between the correction amount of the piezoelectric layer was determined so as to satisfy both The diaphragm is made of a material having an elastic modulus equal to or higher than that of the piezoelectric layer, and when the thickness deviation amount of the diaphragm is ΔTv and the correction amount of the piezoelectric layer is ΔTp, The first relational expression regarding the deformation amount of the diaphragm is (−0.75 × ΔTv) ≦ ΔTp ≦ (−1.05 × ΔTv), and the second relational expression regarding the rigidity of the actuator is ( is -1.0 × ΔTv) ≦ ΔTp ≦ ( -1.3 × ΔTv) Method for manufacturing a body transfer apparatus is provided.

  According to the method for manufacturing the liquid transfer device, even if the thickness of the diaphragm is deviated from the reference thickness, the deviation can be corrected by the thickness of the piezoelectric layer, and the yield in the production process is improved. In addition, it is possible to suppress variations in the vibration amount of the diaphragm and the rigidity of the piezoelectric actuator among the plurality of piezoelectric actuators as much as possible. Can be equal.

According to the third aspect of the present invention, a diaphragm provided on one surface of the flow path unit having a pressure chamber and covering the pressure chamber, and a piezoelectric layer disposed on the opposite side of the pressure chamber of the diaphragm A device for manufacturing a piezoelectric actuator of a liquid transfer device having two electrodes respectively disposed on both sides of the piezoelectric layer, the thickness measuring device for measuring the thickness of the diaphragm, and the thickness A thickness determining device that determines the thickness of the piezoelectric layer based on a deviation amount of the thickness of the diaphragm measured by a measuring device with respect to a preset reference thickness of the diaphragm; and the thickness determination A piezoelectric layer forming device that forms the piezoelectric layer having a thickness determined by a device on a side opposite to the pressure chamber of the diaphragm, and the thickness determining device has a preset piezoelectric layer. A correction amount with respect to the reference thickness is applied to one of the electrodes by a predetermined power The first relational expression showing the relationship between the thickness deviation amount of the diaphragm and the correction amount of the piezoelectric layer with respect to the deformation amount of the diaphragm when the vibration is applied, and the vibration with respect to the rigidity of the actuator It is determined so as to satisfy both of the second relational expression showing the relationship between the deviation amount of the plate thickness and the correction amount of the piezoelectric layer. The first relational expression relating to the deformation amount of the diaphragm is given by assuming that the thickness deviation amount of the diaphragm is ΔTv and the correction amount of the piezoelectric layer is ΔTp. −0.75 × ΔTv) ≦ ΔTp ≦ (−1.05 × ΔTv), and the second relational expression regarding the rigidity of the actuator is (−1.0 × ΔTv) ≦ ΔTp ≦ (−1.3 A device for manufacturing a piezoelectric actuator of xΔTv) is provided.

  According to this piezoelectric actuator manufacturing apparatus, even if the thickness of the diaphragm deviates from the reference thickness, the deviation can be corrected by the thickness of the piezoelectric layer, and the yield in the manufacturing process is improved. Further, it is possible to suppress the variation in the deformation amount of the diaphragm and the rigidity of the piezoelectric actuator among the plurality of piezoelectric actuators as much as possible. The piezoelectric actuator manufacturing apparatus may further include a storage device that stores a relationship of the thickness of the piezoelectric layer with respect to a deviation amount with respect to a reference thickness of the diaphragm.

  Embodiments of the present invention will be described. This embodiment is an example in which the present invention is applied to an inkjet head that ejects ink from nozzles onto recording paper as a liquid transfer device.

  First, the ink jet printer 100 including the ink jet head 1 will be briefly described. As shown in FIG. 1, an inkjet printer 100 includes a carriage 101 that can move in the left-right direction in FIG. 1, a serial inkjet head 1 that is provided on the carriage 101 and that ejects ink onto a recording paper P, A conveyance roller 102 that conveys the recording paper P forward in FIG. 1 is provided. The inkjet head 1 moves in the left-right direction (scanning direction) integrally with the carriage 101, and is transferred from the emission port of the nozzle 20 (see FIGS. 2 to 5) formed on the lower surface to the recording paper P. On the other hand, ink is ejected. Then, the recording paper P recorded by the inkjet head 1 is discharged forward (paper feeding direction) by the transport roller 102.

  Next, the inkjet head 1 will be described in detail with reference to FIGS.

  As shown in FIGS. 2 to 5, the inkjet head 1 includes a flow path unit 2 in which an individual ink flow path 21 (see FIG. 4) including a pressure chamber 14 is formed, and an upper surface of the flow path unit 2. And a piezoelectric actuator 3 laminated on the substrate.

  First, the flow path unit 2 will be described. As shown in FIGS. 4 and 5, the flow path unit 2 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 bonded 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, the cavity plate 10 is formed with a plurality of pressure chambers 14 arranged along a plane. The plurality of pressure chambers 14 are open to a diaphragm 30 side (upper side in FIG. 4) described later. The plurality of pressure chambers 14 are arranged in two rows in the paper feeding direction (up and down direction in FIG. 2). 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. The cavity plate 10 is formed with an ink supply port 18 connected to an ink tank (not shown).

  As shown in FIGS. 3 and 4, communication holes 15 and 16 are formed at positions overlapping the both ends in the longitudinal direction of the pressure chamber 14 in plan view of the base plate 11, respectively. Further, the manifold plate 12 is formed with a manifold 17 that extends in the paper feeding direction (vertical direction in FIG. 2) and overlaps either one of the right and left ends of the pressure chamber 14 in FIG. Ink is supplied to the manifold 17 from an ink tank through an ink supply port 18. A communication hole 19 is also formed at a position overlapping the end of the pressure chamber 14 opposite to the manifold 17 in plan view. Further, the nozzle plate 13 is formed with a plurality of nozzles 20 at positions overlapping with the plurality of communication holes 19 in plan view. The nozzle 20 is formed, for example, by performing excimer laser processing on a polymer synthetic resin substrate such as polyimide.

  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. In this way, the individual ink flow path 21 extending from the manifold 17 to the nozzle 20 through the pressure chamber 14 is formed in the flow path unit 2.

  Next, the piezoelectric actuator 3 will be described. As shown in FIGS. 2 to 5, the piezoelectric actuator 3 includes a conductive vibration plate 30 disposed on the upper surface of the flow path unit 2, and an upper surface of the vibration plate 30 (surface opposite to the pressure chamber 14). And a plurality of individual electrodes 32 formed corresponding to the plurality of pressure chambers 14 on the upper surface of the piezoelectric layer 31, respectively.

  The diaphragm 30 is a plate made of a substantially rectangular metal material 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 laminated and joined to the upper surface of the cavity plate 10 so as to cover the plurality of pressure chambers 14. The diaphragm 30 also serves as a common electrode that opposes the plurality of individual electrodes 32 and applies an electric field to the piezoelectric layer 31 between the individual electrodes 32 and the diaphragm 30.

  On the upper surface of the vibration plate 30, a piezoelectric layer 31 composed mainly of lead zirconate titanate (PZT), which is a solid solution and a ferroelectric substance, is formed in direct contact with the vibration plate 30. Has been. The piezoelectric layer 31 is entirely formed on the upper surface of the diaphragm 30 across the plurality of pressure chambers 14. As will be described later, the thickness of the piezoelectric layer 31 is the vibration actually measured in the manufacturing stage of the inkjet head 1 in order to correct the variation in the thickness of the vibration plate 30 with the thickness of the piezoelectric layer 31. The thickness of the plate 30 is determined based on a deviation amount from a preset reference thickness.

  A plurality of individual electrodes 32 having an elliptical planar shape that is slightly smaller than the pressure chamber 14 are formed on the upper surface of the piezoelectric layer 31. Each of the plurality of individual electrodes 32 is formed at a position overlapping the central portion of the corresponding pressure chamber 14 in plan view. The individual electrode 32 is made of a conductive material such as gold, copper, silver, palladium, platinum, or titanium. Further, on the upper surface of the piezoelectric layer 31, a plurality of terminal portions 35 extending in the scanning direction from the end portions on the manifold 17 side of the plurality of individual electrodes 32 are also formed. As shown in FIG. 4, the plurality of terminal portions 35 are electrically connected to a driver IC 37 via a flexible wiring member (not shown) such as a flexible printed wiring board. A drive voltage is selectively supplied to the plurality of individual electrodes 32 via the unit 35.

  Next, the operation of the piezoelectric actuator 3 will be described.

  When a driving voltage is selectively applied to the plurality of individual electrodes 32 from the driver IC 37, the individual electrodes 32 on the upper side of the piezoelectric layer 31 to which the driving voltage is supplied and the lower side of the piezoelectric layer 31 held at the ground potential. The potentials of the diaphragm 30 as the common electrode are in different states, and an electric field in the vertical direction is generated in the portion of the piezoelectric layer 31 sandwiched between the individual electrode 32 and the diaphragm 30. Then, the portion of the piezoelectric layer 31 directly below the individual electrode 32 to which the drive voltage is applied contracts in the horizontal direction orthogonal to the vertical direction that is the polarization direction. At this time, the diaphragm 30 is deformed so as to protrude toward the pressure chamber 14 as the piezoelectric layer 31 contracts, so that the volume in the pressure chamber 14 decreases and pressure is applied to the ink in the pressure chamber 14. Ink droplets are ejected from the nozzle 20 communicating with the pressure chamber 14.

  Next, a method for manufacturing the inkjet head 1 will be described.

  First, holes to be the pressure chambers 14, the manifold 17, and the like are formed in the cavity plate 10, the base plate 11, and the manifold plate 12 made of a metal material by etching or the like. Moreover, the diaphragm 30 is cut out and formed into a predetermined size from a metal sheet. Then, as shown in FIG. 6A, the cavity plate 10, the base plate 11, the manifold plate 12, and the four metal plates of the vibration plate 30 are joined together.

  Next, as shown in FIG. 6B, the piezoelectric layer 31 is formed in contact with the surface of the diaphragm 30 on the side opposite to the pressure chamber 14. Here, the thickness of the diaphragm 30 may be different for each piezoelectric actuator 3 because the thickness of the metal sheet from which the diaphragm 30 is cut varies from lot to lot. In this case, the deformation amount of the vibration plate 30 and the rigidity of the piezoelectric actuator 3 vary between the plurality of piezoelectric actuators 3, and the ink droplet volume and liquid discharged from the nozzle 20 are different for each inkjet head 1. Since ink ejection characteristics such as droplet velocity or ejection timing are different, the print quality varies. Therefore, in the present embodiment, the variation in the thickness of the vibration plate 30 is corrected by the thickness of the piezoelectric layer 31 so that the ink ejection characteristics are equal among the plurality of inkjet heads 1 as follows.

  First, the thickness of the diaphragm 30 cut out from the metal sheet is measured (diaphragm thickness measuring step). Here, the thickness of the diaphragm 30 may be measured for each diaphragm 30, but the metal sheet is often the same thickness in one lot, so the metal sheet of a new lot The thickness of the diaphragm 30 may be measured every time the (rolling roll) is used. Further, the thickness of the metal sheet may be measured before the diaphragm 30 is cut from the metal sheet (that is, before the diaphragm 30 is joined to the cavity plate 10).

  Then, the thickness of the piezoelectric layer 31 is determined based on a deviation amount of the measured thickness of the diaphragm 30 with respect to a preset reference thickness of the diaphragm 30 (piezoelectric layer thickness determining step). Here, the thickness of the piezoelectric layer 31 determined in the piezoelectric layer thickness determining step differs depending on which factor is particularly focused on among the factors affecting the ink ejection characteristics.

  If the thickness of the vibration plate 30 is different, the deformation amount of the vibration plate 30 is also different, and the pressure generated in the pressure chamber 14 is different. The print quality varies depending on the head 1 and varies. Therefore, in the piezoelectric layer thickness determination step, the piezoelectric layer 31 is formed so that the deformation amount of the diaphragm 30 becomes a predetermined deformation amount when a predetermined driving voltage is applied from the driver IC 37 to the individual electrode 32. The thickness can be determined. In this case, the thickness Tv of the vibration plate 30 and the thickness Tp of the piezoelectric layer 31 and the displacement amount Dd (hereinafter referred to as the maximum displacement amount) at the position facing the central portion of the pressure chamber 14 of the vibration plate 30 in advance. The relationship with Dd) is obtained by structural analysis by finite element method (FEM), experiments, or the like. For example, as shown in FIG. 5, the length in the direction orthogonal to the longitudinal direction of the pressure chamber 14, the width Wc of the pressure chamber 14 is 250 μm, the width We of the individual electrode 32 is 140 μm, and the pressure chamber 14 is not formed. The thickness Tv (μm) of the diaphragm 30 and the piezoelectric layer 31 when structural analysis by FEM is performed with the width B of the side wall 10a being 89 μm and the drive voltage applied to the individual electrode 32 being 20V. FIG. 7 shows the change in the maximum displacement Dd (nm) with respect to the thickness Tp (μm). In this analysis, stainless steel is assumed as the material of the diaphragm 30, and lead zirconate titanate (PZT) is assumed as the material of the piezoelectric layer 31.

  Here, the numbers in the graph of FIG. 7 indicate the value of Dd. When the value of Tv on the horizontal axis and the value of Tp on the vertical axis are changed, the value of Dd becomes the intersection of Tv and Tp. It shows that it becomes the numerical value described in the position. In addition, a curve a in FIG. 7 indicates a line connecting points that are set to a preset target value Dd0 (Dd0 = 33) of Dd. From the relationship between the deviation ΔTv of the actually measured thickness Tvi of the diaphragm 30 from the preset reference thickness Tv0, Tv and Tp, and Dd as shown in FIG. The correction amount ΔTp1 of the thickness of the piezoelectric layer 31 (Dd when the thickness Tv of the diaphragm 30 is the reference thickness Tv0) so that the amount Dd becomes a predetermined target value Dd0 (Dd0 = 33 in FIG. 7). Is determined in advance from the reference thickness Tp0 of the piezoelectric layer 31 so as to be the target value Dd0. In FIG. 7, the value of Tp on the vertical axis indicates a positive displacement below Tp0. Therefore, it can be seen from the slope of the curve of the graph that the insufficient thickness of the diaphragm may be compensated by the thickness of the piezoelectric layer.

When the diaphragm is made of a material having an elastic modulus equal to or higher than that of the piezoelectric layer, the width Wc of the pressure chamber 14, the width We of the individual electrode 32, the width B of the side wall 10a, As a result of changing the thickness Tv and the thickness Tp of the piezoelectric layer 31 within a practical range and performing analysis by FEM, the correction amount ΔTp1 is independent of the values of these Wc, We, B, Tv, and Tp. Was found to satisfy the condition of the following formula (1).
(−0.75 × ΔTv) ≦ ΔTp1 ≦ (−1.05 × ΔTv) (1)
Therefore, ΔTp1 may be determined from ΔTv using this relationship. In this case, since it is not necessary to obtain the relationship as shown in FIG. 7 in advance for each combination of Wc, We, B, Tv, and Tp, the value of the correction amount ΔTp1 can be easily obtained.

  In addition, if the thickness of the vibration plate 30 varies among the plurality of piezoelectric actuators 3, the rigidity of the piezoelectric actuator 3 varies. When the rigidity of the piezoelectric actuator 3 varies as described above, the displacement amount of the piezoelectric actuator 3 changes due to the reaction force against the pressure of the ink in the pressure chamber 14, and the droplet speed and liquid of the ink ejected from the nozzle 20 are changed. The droplet volume differs from one inkjet head 1 to another, and the print quality varies. Furthermore, when the rigidity of the piezoelectric actuator 3 varies, the velocity of the pressure wave propagating in the pressure chamber 14 (that is, the propagation time of the pressure wave) also varies from one piezoelectric actuator 3 to another. In particular, a negative pressure wave is generated by returning the diaphragm 30 to its original shape and increasing the volume in the pressure chamber 14 from a state in which the diaphragm 30 is deformed so as to protrude toward the pressure chamber 14. When the pressure wave is turned positive, the diaphragm 30 is deformed so as to be convex again toward the pressure chamber 14, thereby generating a large pressure in the ink. When the propagation time of the pressure wave deviates from the design value, the diaphragm 30 is deformed so as to be convex toward the pressure chamber 14 at the timing when the pressure wave turns positive, and a large pressure is applied to the ink. become unable. Therefore, ink cannot be ejected at the correct timing, and further, the ejection quality of the liquid droplets is unstable, and the print quality is deteriorated. Therefore, in the piezoelectric layer thickness determining step, the thickness of the piezoelectric layer 31 may be determined so that the rigidity of the piezoelectric actuator 3 becomes a predetermined value.

  In this case, the thickness Tv of the diaphragm 30 and the thickness Tp of the piezoelectric layer 31 and the maximum displacement Di (pressure chamber) of the diaphragm 30 when a predetermined pressure is generated in the pressure chamber 14 in advance. 14 is obtained by structural analysis by FEM, experiments, or the like. The maximum displacement Di when the piezoelectric actuator 3 is driven corresponds to the rigidity of the piezoelectric actuator 3. And when this displacement amount Di increases, it has shown that the rigidity of the piezoelectric actuator 3 has fallen, and the propagation time of a pressure wave increases. For example, in FIG. 5, the width Wc of the pressure chamber 14 is 250 μm, the width We of the individual electrode 32 is 140 μm, the width B of the side wall 10a is 89 μm, and the pressure of the ink generated in the pressure chamber 14 is 0.1 MPa. FIG. 8 shows changes in the maximum displacement amount Di (nm) with respect to the thickness Tv (μm) of the vibration plate 30 and the thickness Tp (μm) of the piezoelectric layer 31 when the structural analysis is performed. . In this analysis, stainless steel is assumed as the material of the diaphragm 30, and lead zirconate titanate (PZT) is assumed as the material of the piezoelectric layer 31.

  The numbers in the graph of FIG. 8 indicate the value of the maximum displacement amount Di (the displacement amount toward the pressure chamber 14 is positive), and the value of Tv on the horizontal axis and the value of Tp on the vertical axis. When the value is changed, it is indicated that the value of Di becomes a numerical value described at the position of the intersection of Tv and Tp. Further, a curve b in FIG. 8 shows a line connecting points that become the target value Di0 (Di0 = −3.3) of Di. Then, from the relationship between the deviation amount ΔTv of the measured thickness Tvi of the diaphragm 30 from the preset reference thickness Tv0, Tv and Tp as shown in FIG. 8, and Di, the maximum displacement Di Is a predetermined target value Di0 (Di0 = −3.3 in FIG. 8), the correction amount ΔTp2 of the thickness of the piezoelectric layer 31 (when the thickness Tv of the diaphragm 30 is the reference thickness Tv0). A predetermined correction amount from the reference thickness Tp0 of the piezoelectric layer 31 so that Di becomes the target value Di0 is determined. In FIG. 8, the value of Tp on the vertical axis indicates a positive displacement below Tp0. Therefore, it can be seen from the slope of the curve of the graph that the insufficient thickness of the diaphragm may be compensated by the thickness of the piezoelectric layer.

Further, when the vibration plate is made of a material having an elastic modulus equal to or higher than the material of the piezoelectric layer, the width Wc of the pressure chamber 14, the width We of the individual electrode 32, the width B of the side wall portion 10a, the vibration plate 30 As a result of analyzing the thickness Tv and the thickness Tp of the piezoelectric layer 31 within the practical range and performing the analysis by FEM, the correction amount ΔTp2 regardless of the values of Wc, We, B, Tv, and Tp. Was found to satisfy the relationship of the following formula (2).
(−1.0 × ΔTv) ≦ ΔTp2 ≦ (−1.3 × ΔTv) (2)
Therefore, ΔTp2 may be determined from ΔTv using this relationship. In this case, the correction amount ΔTp2 can be easily obtained.

  Further, as an example, a case where the piezoelectric layer 31 is formed by using an aerosol deposition method (AD method) in which particles of very small piezoelectric material are sprayed onto a substrate to collide at high speed and deposited on the substrate will be described with reference to FIGS. This will be described more specifically with reference to FIG. 11 and the flowchart of FIG.

  As shown in FIGS. 9 to 11, the manufacturing apparatus 40 of the piezoelectric actuator 3 forms a piezoelectric displacement 31 on the vibration plate 30 and a laser displacement meter 41 (thickness measurement device) that measures the thickness of the vibration plate 30. A control device 43 that controls the thickness of the piezoelectric layer 31 formed by the film forming device 42 based on the thickness of the vibration plate 30 measured by the film forming device 42 (piezoelectric layer forming device) and the laser displacement meter 41. (Thickness determination device). The control device 43 includes a storage device or a storage unit (not shown). The film forming apparatus 42 includes a film forming chamber 50, an injection nozzle 51 connected to an aerosol generator (not shown), and a stage 52 that moves the diaphragm 30 in a predetermined direction in the film forming chamber 50.

  The aerosol generator generates an aerosol that is a mixture of an ultrafine piezoelectric material and a carrier gas, and injects the aerosol from the injection nozzle 51, and has a predetermined particle concentration according to a command from the control device 43. It is configured to generate an aerosol.

  Further, when the piezoelectric layer 31 is formed in a predetermined region of the diaphragm 30, the stage 52 causes the diaphragm 30 to eject the nozzle 30 so that the spray nozzle 51 that sprays aerosol is completely opposed to this region. Relative movement. The relative movement path of the stage 52 is appropriately determined by the control device 43 according to a desired film formation range, and the stage 52 moves along the determined path according to a command from the control device 43.

  And using this manufacturing apparatus 40, the piezoelectric layer 31 is formed in the diaphragm 30 as follows. First, as shown in FIG. 9, before the diaphragm 30 bonded to the cavity plate 10 is accommodated in the film forming chamber 50, the thickness Tv of the diaphragm 30 is measured by the laser displacement meter 41 (FIG. 12). S10). Then, the control device 43 calculates a deviation amount ΔTv of the measured thickness Tv of the diaphragm 30 from the reference thickness Tv0 (S11). Further, from the deviation amount ΔTv and the relationship between Tv and Tp and the maximum displacement amount Dd (see FIG. 7) or the above-described range (−0.75 × ΔTv) ≦ ΔTp1 ≦ (−1.05 × ΔTv), A correction amount ΔTp1 of the thickness of the piezoelectric layer 31 is calculated so that the deformation amount of the diaphragm 30 becomes a predetermined value (S12). Alternatively, from the deviation amount ΔTv and the relationship between Tv and Tp and the maximum displacement amount Di (see FIG. 8) or the above-described range (−1.0 × ΔTv) ≦ ΔTp2 ≦ (−1.3 × ΔTv), A correction amount ΔTp2 of the thickness of the piezoelectric layer 31 is calculated so that the rigidity of the piezoelectric actuator 3 becomes a predetermined value (S13).

  Then, the thickness Tp of the piezoelectric layer 31 is determined from the reference thickness ΔTp0 and the correction amount ΔTp1 or the correction amount ΔTp2 (S14). Further, the film forming conditions (the number of times the stage 52 moves along a predetermined path, the moving speed of the stage 52, etc.) necessary for forming the piezoelectric layer 31 having the determined thickness Tp are determined (S15). . If the number of movements of the stage 52 is increased, the piezoelectric layer 31 can be formed thicker according to the number of movements. Further, if the moving speed of the stage 52 is increased, the time during which the injection nozzle 51 faces the desired film formation range of the diaphragm 30 is shortened, so that the piezoelectric layer 31 can be made thin. Therefore, for example, the thickness of the piezoelectric layer 31 can be managed as follows. The thickness of the piezoelectric layer 31 is measured in advance while changing the number of movements and the movement speed to various values. The obtained relationship of the thickness of the piezoelectric layer 31 with respect to the number of movements and the movement speed is stored in the storage device as data. When the piezoelectric layer 31 is actually formed, the manufacturing apparatus 40 can be operated with the number of movements and the movement speed corresponding to the target thickness of the piezoelectric layer 31. It is desirable to store the data and equations (1) to (3) in the storage unit provided in the control device 43.

  Then, as shown in FIG. 10, after the diaphragm 30 is attached to the stage 52, as shown in FIG. 11, an aerosol generator is formed in the film forming chamber 50 maintained in a vacuum state by a vacuum pump (not shown). The stage 52 to which the diaphragm 30 is attached is sprayed from the spray nozzle 51 onto the diaphragm 30 while the aerosol generated in step S5 is moved by the control device 43, and the number of movements and the movement speed determined in S15. The piezoelectric layer 31 having a thickness Tp is formed on the vibration plate 30 (S16).

  In the piezoelectric layer forming process by the manufacturing apparatus 40, the piezoelectric layer 31 having a desired thickness may be formed by adjusting the aerosol particle concentration, which is another film forming condition. By increasing the particle concentration of the aerosol, the piezoelectric layer 31 can be formed thick. Also in this case, the thickness of the piezoelectric layer 31 is measured while changing the particle concentration of the aerosol by a preliminary experiment, and the relationship between the particle concentration and the thickness of the piezoelectric layer 31 is obtained in advance as data and stored in the storage unit of the control device 43. It is desirable to keep it. The thickness may be adjusted by selecting at least one of the three film formation conditions of the aerosol particle concentration, the number of movements of the stage 52 and the movement speed of the stage 52 described above, or 3 The thickness may be adjusted by combining two film forming conditions.

  In the above description, the case where the piezoelectric layer 31 is formed by using the AD method is taken as an example, but a method other than the AD method, for example, a sputtering method, a chemical vapor deposition method (CVD method), or a hydrothermal synthesis is used. It is possible to form the piezoelectric layer 31 having the determined predetermined thickness on the diaphragm 30 by using other known methods such as the method. Even in these cases, the piezoelectric layer 31 having a desired thickness can be formed by managing the sputtering time, sputtering voltage, vapor deposition time, vapor deposition temperature, and the like in relation to the thickness of the piezoelectric layer 31.

  After the piezoelectric layer 31 having a predetermined thickness is formed on the surface opposite to the pressure chamber 14 of the vibration plate 30 in this way, as shown in FIG. 6C, screen printing, sputtering, vapor deposition, or the like is performed. Thus, the plurality of individual electrodes 32 and the plurality of terminal portions 35 are simultaneously formed on the surface of the piezoelectric layer 31 opposite to the diaphragm 30. The thickness of the piezoelectric layer 31 may be measured after forming the piezoelectric layer 31 or while forming the piezoelectric layer 31. Finally, as shown in FIG. 6 (d), the nozzle plate 13 is joined to the manifold plate 12 to complete the manufacturing process of the inkjet head 1.

  When the nozzle plate 13 is a metal plate, the nozzle plate 13 is also joined simultaneously with the other four metal plates (the cavity plate 10, the base plate 11, the manifold plate 12, and the vibration plate 30). It may be.

In the above embodiment, when the diaphragm is made of a material having an elastic modulus equal to or higher than the material of the piezoelectric layer, the relationship of either formula (1) or formula (2) can be used. It can be seen that it is advantageous in manufacturing that the thickness of the piezoelectric layer satisfying 1) also satisfies the formula (2). That is, when the diaphragm is made of a material having an elastic modulus equal to or greater than that of the piezoelectric layer, the thickness of the piezoelectric layer is adjusted so as to satisfy the following formula (3). And from the viewpoint of the rigidity of the actuator.
(−1.0 × ΔTv) ≦ ΔTp1 ≦ (−1.05 × ΔTv) (3)
Focusing on equation (3) further leads to the following important results: It can be seen that the thickness of the piezoelectric layer and the thickness of the diaphragm have a complementary relationship. In other words, if the thickness of the diaphragm is thicker than the reference value by an error ΔTv, it is sufficient to subtract from the reference thickness Tp0 of the piezoelectric layer only an amount equivalent to the error ΔTv (ΔTv≈ΔTp1). Therefore, the following thickness setting method is possible. A sum design value TT0 (= Tp0 + Tv0) is obtained from the design value of the diaphragm and the design value of the piezoelectric layer. First, the thickness of the diaphragm is measured, and a deviation ΔTv from the reference value Tv0 is obtained. Since the sum design value TT0 may be maintained from the equation (3), the thickness of the piezoelectric layer is set to be (Tp0−ΔTv). According to this, since the measured value can be used as it is for the correction value of the thickness of the piezoelectric layer only by measuring the error of the thickness of the diaphragm, the thickness setting process of the piezoelectric layer becomes extremely simple.

  The relationship of the above formulas (1) to (3) is that the material of the diaphragm is made of metal, silicon or oxide thereof, and is equivalent to the elastic modulus (elastic modulus or Young's modulus) of the piezoelectric layer. This is true only when the elastic modulus is higher than that. For example, the following materials can be used for PZT, which is a piezoelectric layer material having an elastic modulus of 70 GPa (7000 Kg / mm 2). Aluminum (70 GPa), stainless steel (180 GPa), copper (130 GPa), titanium (120 GPa), nickel (210 GPa), alumina (300 GPa), silicon Si (130 to 190 GPa: depending on crystal direction). A resin such as polyimide cannot be used because it has a low elastic modulus of 7 GPa.

  According to the method for manufacturing the inkjet head 1 described above, the following effects can be obtained.

  In order to measure the thickness of the vibration plate 30 and determine an appropriate thickness of the piezoelectric layer 31 based on the amount of deviation of the measured thickness from the reference thickness, the thickness of the vibration plate 30 is the reference thickness. Even in the case of deviation, the deviation can be corrected by the thickness of the piezoelectric layer 31, and the yield in the manufacturing process is also improved.

  If the thickness of the piezoelectric layer 31 is determined so that the deformation amount of the vibration plate 30 becomes a predetermined deformation amount in the piezoelectric layer thickness determination step, the piezoelectric actuator 3 is caused by the variation in the thickness of the vibration plate 30. Variation in the deformation amount of the diaphragm 30 (that is, variation in droplet volume) can be suppressed as much as possible. Further, if the thickness of the piezoelectric layer 31 is determined so that the rigidity of the piezoelectric actuator 3 becomes a predetermined value, the rigidity variation for each piezoelectric actuator 3 caused by the thickness variation of the diaphragm 30 is suppressed as much as possible. Therefore, the volume of ink droplets ejected from the nozzles 20 for each inkjet head 1 can be made equal, and ink can be stably ejected in any inkjet head 1. Accordingly, it is possible to reduce variations in ink ejection characteristics for each inkjet head 1.

  Further, if the piezoelectric layer 31 is formed by a method of depositing particles or molecules of piezoelectric material on the vibration plate 30 such as the AD method, the thickness of the piezoelectric layer 31 can be finely adjusted. After determining the thickness Tp of the piezoelectric layer 31 in the thickness determining step, the piezoelectric layer 31 having the thickness Tp can be easily formed. Therefore, when the inkjet head 1 is mass-produced, even if there is a change in the thickness of the vibration plate 30 during the production, the production can be continued without varying the ink ejection characteristics. Such costs can be reduced.

  In the inkjet head 1 of the present embodiment, the diaphragm 30 made of a metal material and having conductivity also serves as a common electrode, and the piezoelectric layer 31 is disposed between the diaphragm 30 and another layer. (For example, a common electrode layer, an insulating material layer that insulates the electrode from the diaphragm 30, etc.) are formed in direct contact with the surface of the diaphragm 30 opposite to the pressure chamber 14. Therefore, the variation in the thickness of the diaphragm 30 can be accurately corrected only by adjusting the thickness of the piezoelectric layer 31. Further, since the diaphragm 30 also serves as a common electrode, the process of forming the common electrode separately from the diaphragm 30 can be omitted, and the manufacturing process can be simplified.

Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.
<First modification>
In the ink jet head manufacturing method of the above embodiment, the piezoelectric layer 31 is formed on the diaphragm 30 by depositing particles of piezoelectric material using the AD method or the like, but the PZT green sheet is fired. The piezoelectric layer 31 may be formed by adhering one or a plurality of obtained piezoelectric sheets to the vibration plate 30. In this case, piezoelectric sheets having a plurality of types of thicknesses are prepared in advance, and after determining the thickness of the piezoelectric layer 31 to a predetermined value based on the thickness deviation amount ΔTv of the diaphragm 30, the piezoelectric sheet is obtained. A piezoelectric sheet having an appropriate thickness may be selected and bonded to the diaphragm 30 so that the thickness of the layer 31 becomes the predetermined value.
<Second modification>
The diaphragm may be made of an insulating material (for example, a silicon material whose surface is oxidized, a ceramic material such as PZT, alumina, zirconia, or a synthetic resin material such as polyimide). However, in this case, as shown in FIG. 13, in the piezoelectric actuator 3A, on the surface of the insulating diaphragm 30A opposite to the pressure chamber 14, the individual electrode 32 is opposed to the piezoelectric layer 31 therebetween. A common electrode 34 is required to generate an electric field.
<Third modification>
In the above embodiment, the individual electrode 32 is formed on the side of the piezoelectric layer 31 opposite to the diaphragm 30. However, the individual electrode 32 is disposed on the diaphragm 30 side of the piezoelectric layer 31. A common electrode 34 may be disposed on the opposite side. However, when the diaphragm is made of a metal material, as shown in FIG. 14, in the piezoelectric actuator 3B, in order to insulate between the plurality of individual electrodes 32, the upper surface (pressure chamber 14) of the diaphragm 30 made of metal. The surface of the diaphragm 30 on which the individual electrodes 32 are arranged needs to have insulation properties, for example, by forming an insulating material layer 60 on the surface opposite to the surface. The insulating material layer 60 is made of a ceramic material such as alumina or zirconia, and can be formed by an AD method, a sputtering method, a CVD method, a sol-gel method, or the like. On the other hand, when the diaphragm is made of an insulating material such as a silicon material, a ceramic material, or a synthetic resin material, as shown in FIG. 15, in the piezoelectric actuator 3C, the individual electrode 32 is directly on the upper surface of the diaphragm 30C. The plurality of individual electrodes 32 are insulated from each other by the diaphragm 30C having insulation.
<Fourth modification>
In the above embodiment, the flow path unit having the individual ink flow path 21 therein is mainly constituted by the stacked metal plates (cavity plate 10, base plate 11 and manifold plate 12). May be formed of a material other than a metal material (for example, a silicon material).

  The above-described embodiment and its modification are examples in which the present invention is applied to an ink jet head that transports ink, but a liquid transport apparatus to which the present invention is applicable is not limited to an ink jet head. For example, a liquid transfer device that transfers a liquid such as a chemical solution or a biochemical solution inside a micro total analysis system (μTAS), a liquid transfer device that transfers a liquid such as a solvent or a chemical solution inside a microchemical system, etc. The present invention can also be applied to a liquid transfer device for transferring the liquid.

1 is a schematic perspective view of an inkjet head according to an embodiment of the present invention. 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 manufacturing process of an inkjet head, (a) is a joining process of a metal plate, (b) is a piezoelectric layer formation process, (c) is an individual electrode formation process, (d) is a joining process of a nozzle plate, respectively. Show. It is a figure which shows the relationship between the thickness Tv of a diaphragm, the thickness Tp of a piezoelectric layer, and the maximum displacement amount Dd showing the deformation amount of a diaphragm. It is a figure which shows the relationship between the thickness Tv of a diaphragm, the thickness Tp of a piezoelectric layer, and the maximum displacement amount Di showing the rigidity of a piezoelectric actuator. It is a figure which shows the process of measuring the thickness of a diaphragm in the case of forming a piezoelectric layer by AD method. It is a figure which shows the state which attached the diaphragm to the stage in the film-forming chamber. It is a figure which shows the state which has injected the piezoelectric material with respect to the diaphragm from the injection nozzle. It is a flowchart of a series of processes which correct | amend the dispersion | variation in the thickness of a diaphragm with the thickness of a piezoelectric layer. It is sectional drawing equivalent to FIG. 5 of a modification. It is sectional drawing equivalent to FIG. 5 of another modification. It is sectional drawing equivalent to FIG. 5 of another modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Flow path unit 3, 3A, 3B, 3C Piezoelectric actuator 14 Pressure chamber 20 Nozzle 30, 30A, 30C Diaphragm 31 Piezoelectric layer 32 Individual electrode 34 Common electrode 40 Manufacturing apparatus 41 Laser displacement meter 42 Film-forming apparatus 43 Control apparatus

Claims (10)

A diaphragm provided on one surface of the flow path unit having a pressure chamber, and covering the pressure chamber, a piezoelectric layer disposed on the opposite side of the pressure chamber of the diaphragm, and disposed on both sides of the piezoelectric layer. A method of manufacturing a piezoelectric actuator of a liquid transfer device having two electrodes sandwiching the piezoelectric layer,
A diaphragm thickness measuring step for measuring the thickness of the diaphragm;
Piezoelectric layer thickness determination that determines the thickness of the piezoelectric layer based on a deviation amount of the diaphragm thickness measured in the diaphragm thickness measurement step with respect to a preset reference thickness of the diaphragm. Process,
A piezoelectric layer forming step of providing the piezoelectric layer having the thickness determined in the piezoelectric layer thickness determining step on the opposite side of the pressure chamber of the diaphragm;
In the piezoelectric layer thickness determining step, the vibration amount relating to a deformation amount of the diaphragm when a predetermined voltage is applied to one of the electrodes, and a correction amount with respect to a preset reference thickness of the piezoelectric layer. A first relational expression indicating a relationship between a deviation amount of a plate thickness and the correction amount of the piezoelectric layer, and a deviation amount of the diaphragm thickness and a correction amount of the piezoelectric layer relating to the rigidity of the actuator; determining a second relation formula showing the relationship, so as to satisfy both,
The vibration plate is made of a material having an elastic modulus equal to or greater than the material of the piezoelectric layer, and when the thickness deviation amount of the vibration plate is ΔTv and the correction amount of the piezoelectric layer is ΔTp, the vibration The first relational expression regarding the deformation amount of the plate is (−0.75 × ΔTv) ≦ ΔTp ≦ (−1.05 × ΔTv), and the second relational expression regarding the rigidity of the actuator is (− 1.0 × ΔTv) ≦ ΔTp ≦ (−1.3 × ΔTv) The diaphragm is formed of a conductive material and serves as one of the two electrodes,
In the piezoelectric layer forming step, the piezoelectric layer is formed in contact with the surface of the diaphragm opposite to the pressure chamber,
Wherein the other of the two electrodes, the method for manufacturing a piezoelectric actuator according to claim 1, characterized in that is formed in contact with the surface opposite to the vibration plate of the piezoelectric layer. In the piezoelectric layer forming step, the piezoelectric layer, the aerosol deposition method, according to claim 1, characterized in that formed on the vibration plate by sputtering and one method selected from the group consisting of chemical vapor deposition or 3. A method for manufacturing a piezoelectric actuator according to 2 . Wherein the piezoelectric layer forming step, the piezoelectric layer, method for manufacturing a piezoelectric actuator according to any one of claims 1 to 3, characterized in that formed on the vibration plate by an aerosol deposition method. A flow path unit having a pressure chamber, a diaphragm provided on one surface of the flow path unit and covering the pressure chamber, a piezoelectric layer disposed on the opposite side of the pressure chamber of the vibration plate, A method of manufacturing a liquid transfer device comprising a piezoelectric actuator having two electrodes respectively disposed on both sides,
A diaphragm thickness measuring step for measuring the thickness of the diaphragm;
Piezoelectric layer thickness determination that determines the thickness of the piezoelectric layer based on a deviation amount of the diaphragm thickness measured in the diaphragm thickness measurement step with respect to a preset reference thickness of the diaphragm. Process,
A piezoelectric layer forming step of providing the piezoelectric layer having the thickness determined in the piezoelectric layer thickness determining step on the opposite side of the pressure chamber of the diaphragm;
In the piezoelectric layer thickness determining step, the vibration amount relating to a deformation amount of the diaphragm when a predetermined voltage is applied to one of the electrodes, and a correction amount with respect to a preset reference thickness of the piezoelectric layer. A first relational expression indicating a relationship between a deviation amount of a plate thickness and the correction amount of the piezoelectric layer, and a deviation amount of the diaphragm thickness and a correction amount of the piezoelectric layer relating to the rigidity of the actuator; determining a second relation formula showing the relationship, so as to satisfy both,
The vibration plate is made of a material having an elastic modulus equal to or greater than the material of the piezoelectric layer, and when the thickness deviation amount of the vibration plate is ΔTv and the correction amount of the piezoelectric layer is ΔTp, the vibration The first relational expression regarding the deformation amount of the plate is (−0.75 × ΔTv) ≦ ΔTp ≦ (−1.05 × ΔTv), and the second relational expression regarding the rigidity of the actuator is (− 1.0 × ΔTv) ≦ ΔTp ≦ (−1.3 × ΔTv) The diaphragm is formed of a conductive material and serves as one of the two electrodes,
In the piezoelectric layer forming step, the piezoelectric layer is formed in contact with the surface of the diaphragm opposite to the pressure chamber,
6. The method for manufacturing a liquid transfer device according to claim 5 , wherein the other of the two electrodes is formed in contact with a surface of the piezoelectric layer opposite to the vibration plate. In the piezoelectric layer forming step, the piezoelectric layer, the aerosol deposition method, according to claim 5, characterized in that formed by sputtering and a kind of method selected from the group consisting of chemical vapor deposition on the diaphragm or 6. A method for producing a liquid transfer device according to 6 . 8. The method of manufacturing a piezoelectric actuator according to claim 7 , wherein, in the piezoelectric layer forming step, the piezoelectric layer is formed on the diaphragm by an aerosol deposition method. A diaphragm provided on one surface of the flow path unit having a pressure chamber, and covering the pressure chamber, a piezoelectric layer disposed on the opposite side of the pressure chamber of the diaphragm, and disposed on both sides of the piezoelectric layer. An apparatus for manufacturing a piezoelectric actuator of a liquid transfer device having two electrodes,
A thickness measuring device for measuring the thickness of the diaphragm;
A thickness determining device that determines the thickness of the piezoelectric layer based on a deviation amount of the thickness of the diaphragm measured by the thickness measuring unit with respect to a preset reference thickness of the diaphragm;
A piezoelectric layer forming device that forms the piezoelectric layer having a thickness determined by the thickness determining device on a side opposite to the pressure chamber of the diaphragm;
The thickness determining device relates to a correction amount of the piezoelectric layer with respect to a preset reference thickness, and relates to a deformation amount of the diaphragm when a predetermined voltage is applied to one of the electrodes. A first relational expression indicating a relationship between the thickness deviation amount and the correction amount of the piezoelectric layer, and a relationship between the thickness deviation amount of the diaphragm and the correction amount of the piezoelectric layer regarding the rigidity of the actuator. the second relational expression, determined so as to satisfy both shown,
The vibration plate is made of a material having an elastic modulus equal to or greater than the material of the piezoelectric layer, and when the thickness deviation amount of the vibration plate is ΔTv and the correction amount of the piezoelectric layer is ΔTp, the vibration The first relational expression regarding the deformation amount of the plate is (−0.75 × ΔTv) ≦ ΔTp ≦ (−1.05 × ΔTv), and the second relational expression regarding the rigidity of the actuator is (− 1.0 × ΔTv) ≦ ΔTp ≦ (−1.3 × ΔTv) A piezoelectric actuator manufacturing apparatus, wherein: The piezoelectric actuator manufacturing apparatus according to claim 9 , further comprising a storage device that stores a relationship of a thickness of the piezoelectric layer with respect to a deviation amount with respect to a reference thickness of the diaphragm.

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