JP2017100413A - Discharge drive device, liquid discharge head, liquid discharge unit, and liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress variation in displacement of each electromechanical conversion element in a discharge drive device having a diaphragm on which multiple electromechanical conversion elements are arrayed.SOLUTION: In a discharge drive device which includes a diaphragm and multiple electromechanical conversion elements arrayed on the diaphragm, the electromechanical conversion elements are provided with electromechanical conversion film, and a relationship Δds×Δdp<0 is satisfied when an inclination of film thickness of the diaphragm in an array direction of the electromechanical conversion elements is Δds and an inclination of film thickness of the electromechanical conversion film in the array direction is Δdp.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an ejection driving device, a liquid ejection head, a liquid ejection unit, and an apparatus for ejecting liquid.

  Regarding a liquid discharge head used as an image recording apparatus or an image forming apparatus such as a printer, a facsimile machine, and a copying apparatus, a nozzle that discharges ink droplets, a pressure chamber that communicates with the nozzle, a piezoelectric element that pressurizes ink in the pressure chamber, and the like What has the electromechanical conversion element of this is known. Two types of liquid ejection heads have been put to practical use, one using a longitudinal vibration mode actuator and the other using a flexural vibration mode actuator.

  For example, a uniform electromechanical conversion film is formed by a film forming technique over the entire surface of the vibration plate, and the electromechanical conversion film is formed into a shape corresponding to a pressure chamber by a lithography method. It is known that an electromechanical transducer is formed so as to be separated into each pressure chamber so as to be independent of each pressure chamber (for example, see Patent Document 1).

  However, in the liquid discharge head described above, the relationship between the Young's modulus and the film thickness of the diaphragm and the electromechanical conversion film is considered for a single electromechanical conversion element, but a plurality of electromechanical conversion elements are arranged. In this case, the variation in the film thickness distribution of the electromechanical conversion film in the arrangement direction of the electromechanical conversion elements is not taken into consideration. For this reason, when a plurality of electromechanical conversion elements are arranged, variation in the displacement amount of each electromechanical conversion element cannot be suppressed, and it is difficult to obtain stable ink ejection characteristics.

  The present invention has been made in view of the above, and in a discharge driving device in which a plurality of electromechanical conversion elements are arranged on a diaphragm, it is an object to suppress variation in the displacement amount of each electromechanical conversion element. And

  The discharge driving device is a discharge driving device including a diaphragm and a plurality of electromechanical transducer elements arranged on the diaphragm, the electromechanical transducer element including an electromechanical transducer film, When the inclination of the film thickness of the diaphragm in the arrangement direction of the mechanical conversion elements is Δds and the inclination of the film thickness of the electromechanical conversion film in the arrangement direction is Δdp, Δds × Δdp <0. As a requirement.

  According to the disclosed technology, in the discharge driving device in which a plurality of electromechanical conversion elements are arranged on the diaphragm, variation in the displacement amount of each electromechanical conversion element can be suppressed.

FIG. 3 is a cross-sectional view (part 1) illustrating the liquid ejection head according to the first embodiment; 6 is a cross-sectional view illustrating a manufacturing process of the liquid ejection head according to the first embodiment; FIG. FIG. 4 is a cross-sectional view (part 2) illustrating the liquid ejection head according to the first embodiment; It is a figure explaining the displacement amount in the row | line | column of the chip | tip in a wafer. FIG. 6 is a diagram (part 1) illustrating a film thickness distribution and a displacement characteristic distribution of a diaphragm and an electromechanical conversion film. FIG. 6 is a diagram (part 2) illustrating a film thickness distribution and a displacement characteristic distribution of a diaphragm and an electromechanical conversion film; FIG. 4 is a diagram (part 3) illustrating a film thickness distribution and a displacement characteristic distribution of a diaphragm and an electromechanical conversion film; FIG. 6 is a diagram (part 4) illustrating a film thickness distribution and a displacement characteristic distribution of a diaphragm and an electromechanical conversion film; FIG. 3 is a diagram illustrating wiring of the liquid ejection head according to the first embodiment. It is a figure which illustrates schematic structure of a polarization processing apparatus. It is a figure explaining corona discharge. It is a figure illustrated about a PE hysteresis loop. It is principal part plane explanatory drawing of an example of the apparatus which discharges the liquid which concerns on 2nd Embodiment. It is principal part side explanatory drawing of an example of the apparatus which discharges the liquid which concerns on 2nd Embodiment. It is principal part plane explanatory drawing of the other example of the liquid discharge unit which concerns on 2nd Embodiment. It is front explanatory drawing of the further another example of the liquid discharge unit which concerns on 2nd Embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

<First Embodiment>
FIG. 1 is a cross-sectional view illustrating a liquid discharge head according to the first embodiment. Referring to FIG. 1, the liquid discharge head 1 includes a substrate 10, a vibration plate 20, an electromechanical conversion element 30, and an insulating protective film 40. The electromechanical conversion element 30 includes a lower electrode 31, an electromechanical conversion film 32, and an upper electrode 33.

  In the liquid discharge head 1, the vibration plate 20 is formed on the substrate 10, and the lower electrode 31 of the electromechanical transducer 30 is formed on the vibration plate 20. An electromechanical conversion film 32 is formed in a predetermined region of the lower electrode 31, and an upper electrode 33 is formed on the electromechanical conversion film 32. The insulating protective film 40 covers the electromechanical conversion element 30. The insulating protective film 40 includes an opening that selectively exposes the lower electrode 31 and the upper electrode 33, and wiring can be routed from the lower electrode 31 and the upper electrode 33 through the opening.

  A nozzle plate 50 having a nozzle 51 for ejecting ink droplets is joined to the lower portion of the substrate 10. A pressure chamber 10x (also referred to as an ink flow path, a pressurized liquid chamber, a pressurized chamber, a discharge chamber, or a liquid chamber) that communicates with the nozzle 51 by the nozzle plate 50, the substrate 10, and the vibration plate 20. Is formed. The diaphragm 20 forms part of the wall surface of the ink flow path. In other words, the pressure chamber 10 x is partitioned by the substrate 10 (which constitutes the side surface), the nozzle plate 50 (which constitutes the lower surface), and the vibration plate 20 (which constitutes the upper surface), and communicates with the nozzle 51.

  In order to manufacture the liquid discharge head 1, first, as illustrated in FIG. 2, the vibration plate 20, the lower electrode 31, the electromechanical conversion film 32, and the upper electrode 33 are sequentially stacked on the substrate 10. Thereafter, the lower electrode 31, the electromechanical conversion film 32, and the upper electrode 33 are etched into a desired shape and covered with the insulating protective film 40. Then, an opening for selectively exposing the lower electrode 31 and the upper electrode 33 is formed in the insulating protective film 40. Thereafter, the substrate 10 is etched from below to produce a pressure chamber 10x. Next, a nozzle plate 50 having nozzles 51 is bonded to the lower surface of the substrate 10 to complete the liquid ejection head 1.

  In FIG. 1, only one liquid ejection head 1 is shown, but actually, as shown in FIG. 3, a liquid ejection head 2 in which a plurality of liquid ejection heads 1 are arranged in a predetermined direction is manufactured.

  The liquid discharge head 2 includes a discharge drive device 35 in which a plurality of electromechanical conversion elements 30 are arranged on the vibration plate 20, and a nozzle 51 that discharges liquid provided corresponding to each electromechanical conversion element 30. The pressure chamber 10x communicates with the nozzle 51. In the liquid discharge head 2, a part of the wall of the pressure chamber 10 x is configured by the diaphragm 20, and the discharge driving device 35 boosts the liquid in the pressure chamber 10 x.

  Next, the displacement amount of the electromechanical transducer 30 will be described. FIG. 4 is a diagram for explaining a displacement amount in a row of chips in the wafer. 4A is a plan view of the wafer W. Chips C1 and C4 are arranged on the outer peripheral side of the wafer W, and chips C2 and C3 are arranged on the center side of the wafer W. FIG. A plurality of electromechanical conversion elements 30 are arranged in each of the chips C1 to C4. O. F. Is the Orientation Flat. FIG. 4B shows a change in the displacement amount of the electromechanical transducer 30 in the arrangement direction of the electromechanical transducer 30 (the direction from the chip C1 to the chip C4) in the chips C1 to C4.

  As shown in FIG. 4B, in the chips C1 to C4, the displacement amount tends to decrease toward the outer periphery. That is, the chips C1 and C4 on the outer peripheral side of the wafer W tend to be smaller in displacement than the chips C2 and C3 on the center side of the wafer W. The displacement characteristics themselves are also affected by the piezoelectric strain of the piezoelectric material constituting the electromechanical conversion film 32, the dimensions of the pressure chamber 10x, and the film thickness of each layer. From the center to the outer periphery of the film thickness and film quality on the wafer surface. It can be considered that the variation in FIG. 4 generates the result as shown in FIG. In particular, the high generation factor in the process is the contribution of the film thicknesses of the diaphragm 20 and the electromechanical conversion film 32 shown in FIGS.

  As described above, the piezoelectric is not a random variation among the variations at the time of ink ejection, but a specific piezoelectric having an inclination in the column or between columns of the electromechanical transducer 30 as illustrated in FIG. 4B. It is also necessary to pay attention when there is a variation in performance. This is because such a specific variation greatly affects the ink discharge amount and the discharge speed at the time of ink discharge, and can be clearly recognized as a defective quality when actually printed on paper.

  Note that when the liquid discharge head 2 is assembled, by selecting only the chip at the center of the wafer, it is possible to suppress the outflow of a defective head whose discharge performance greatly varies, but this method is not preferable. This is because when considering the non-defective product ratio of the chips on the outer periphery of the wafer, the number of the electromechanical conversion elements 30 on the outer periphery becomes defective, which causes a large cost increase when considering the total process.

  In addition, regarding the liquid discharge head 2 manufactured from the chip on the outer periphery of the wafer, for example, the ink discharge amount and the discharge speed variation at the time of ink discharge can be corrected by adjusting the voltage waveform at the time of discharge, but this method is also not preferable. . Since liquid ejection heads 2 with small variations produced from chips at the center of the wafer coexist, it is necessary to prepare a plurality of waveforms in the liquid ejection apparatus provided with a plurality of liquid ejection heads 2. This is an increase in cost.

  Thus, in order to suppress variations in the ink ejection amount, ejection speed during ink ejection, and the like, it is preferable that variations in the piezoelectric performance of the electromechanical conversion film 32 be small. However, in addition to random variations among the electromechanical transducers 30, there are specific variations in piezoelectric performance that have inclinations between and within the columns of the plurality of electromechanical transducers 30 arranged in the liquid ejection head 2. Therefore, it is necessary to suppress such specific variations in piezoelectric performance.

  For example, the O.D. of a wafer when a diaphragm is produced as a single layer on a 6-inch wafer. Anti-O. It is assumed that the film thickness distribution toward the F portion tends to be thicker where the film thickness is located on the outer peripheral chip. Based on this result, in the electromechanical conversion film to be subsequently formed, the film thickness distribution on the 6-inch wafer is expressed as O.D. Anti-O. By controlling the film formation so as to reduce the film thickness over the F portion, it is possible to suppress the displacement inclination due to the film thickness variation between the diaphragm and the electromechanical conversion film.

  5 to 8 are diagrams illustrating the film thickness distribution and the displacement characteristic distribution of the diaphragm and the electromechanical conversion film, and the film thickness distribution and the displacement characteristic distribution of the diaphragm and the electromechanical conversion film on a 6-inch wafer. Anti-O. From part F It shows over F part. Wout indicates that the chip is located on the outer periphery of the wafer.

  In FIG. 5, it can be seen that the film thicknesses of both the diaphragm and the electromechanical conversion film increase from the center to the outer periphery, and the displacement characteristics also have a variation with inclination in the outer periphery.

  As shown in FIG. 6, the film thickness of the diaphragm increases from the center to the outer periphery, while the thickness of the electromechanical conversion film decreases from the center to the outer periphery, so that the displacement inclination at the outer peripheral portion is reduced. Can be suppressed.

  Here, the film thickness of the diaphragm (the total film thickness when the diaphragm is formed of a plurality of layers) is ds, and the diaphragm in the arrangement direction of the electromechanical transducer 30 (hereinafter referred to as the arrangement direction). Ave_ds is the average film thickness, and Δds is the inclination of the film thickness of the diaphragm in the arrangement direction. Further, the film thickness of the electromechanical conversion film is dp, the average film thickness of the electromechanical conversion film in the arrangement direction is Ave_dp, and the slope of the film thickness of the electromechanical conversion film in the arrangement direction is Δdp.

  The inclination of the film thickness is an inclination (an inclination of a tangent line) at an arbitrary point on the graph when a change in the film thickness of the diaphragm or the electromechanical conversion film in the arrangement direction in the chip is graphed.

  As shown in FIG. 6, in the chip (Wout portion) located on the outer peripheral portion of the wafer, the inclination directions of Δds and Δdp are different in the Wout on both sides, but the inclination at each point in each Wout is approximately. It tends to be constant. In this case, within each Wout, Δds and Δdp are substantially constant values (inclinations in one direction) at any point on the graph.

  In order to suppress variation in the amount of displacement of the electromechanical transducer elements in the arrangement direction, it is preferable that Δds / Ave_ds be within ± 5%. Moreover, it is preferable that Δdp / Ave_dp be within ± 5%. If it is out of this range, it becomes difficult to control the variation in the thickness of the electromechanical conversion film so as to cancel the variation in the thickness of the diaphragm.

  In order to ensure the discharge performance at high frequency, it is necessary to increase the rigidity of the diaphragm, the electromechanical conversion film, and the insulating protective film, and it is necessary to increase the Young's modulus and the film thickness. For example, the Young's modulus when the diaphragm is formed from a single layer or the average of the equivalent Young's modulus when the diaphragm is formed from a plurality of layers is preferably 75 GPa or more. When the diaphragm is formed of a plurality of layers, it is preferable that the average Young's modulus of the layer having the largest Young's modulus among the plurality of layers in the arrangement direction is 150 GPa or more. Moreover, it is preferable that the Young's modulus of the electromechanical conversion film in the arrangement direction is 80 GPa or more.

In particular, the diaphragm 20 is preferably formed from a plurality of layers including a silicon oxide film (SiO ₂ ), a silicon nitride film (SiN), polysilicon (Poly-Si), and the like in consideration of stress design. The film thickness of the vibration plate 20 is preferably 1 μm or more and 3 μm or less. Thereby, the discharge performance at a high frequency can be ensured.

  In the case where the diaphragm is formed from a plurality of layers, variation in the displacement characteristics varies greatly when the film having high rigidity (average Young's modulus in the arrangement direction is 150 GPa or more) varies. . For example, in FIG. 7, in order to ensure rigidity of 75 GPa or more as a diaphragm, the film thickness of a highly rigid film that is a part of a plurality of layers constituting the diaphragm increases from the center to the outer periphery, and the electromechanical conversion The example in the case where the film thickness has the same tendency is shown. In the case of FIG. 7, it can be seen that the displacement characteristic also has a variation with an inclination at the outer peripheral portion.

  As shown in FIG. 8, the film thickness of the high-rigidity film (high-rigidity diaphragm layer) increases from the center to the outer periphery, whereas the film thickness of the electromechanical conversion film decreases from the center to the outer periphery. Thereby, the displacement inclination in an outer peripheral part can be suppressed.

  At this time, when the average film thickness in the arrangement direction is Ave_ds_max and the inclination of the film thickness in the arrangement direction is Δds_max in the layer having the largest Young's modulus among the plurality of layers, Δds_max / Ave_ds_max is ± 5%. It is preferable to be within the range. If it is out of this range, it becomes difficult to control the variation in the thickness of the electromechanical conversion film so as to cancel the variation in the thickness of the diaphragm.

  As described above, when the diaphragm (a layer having high rigidity in the case of a plurality of layers) increases in thickness from the wafer center to the outer periphery, the outer periphery from the wafer center of the electromechanical conversion film to be formed thereafter Decrease the film thickness. Thereby, it becomes possible to cancel out the film thickness distribution of the diaphragm and the electromechanical conversion film, and it is possible to suppress variation in the displacement amount of each electromechanical conversion element.

  At this time, when the relationship regarding the film thickness gradient in the arrangement direction in the chip satisfies Δds × Δdp <0 or Δds_max × Δdp <0, variation in displacement can be suppressed within ± 8%.

  Hereinafter, a suitable material and the like constituting the liquid discharge head 2 will be described in more detail. As the substrate 10, it is preferable to use a silicon single crystal substrate, and it is usually preferable to have a thickness of 100 to 600 μm. There are three types of plane orientations, (100), (110), and (111). Generally, (100) and (111) are widely used in the semiconductor industry. A single crystal substrate having a plane orientation of 100) can be used.

  Further, when the pressure chamber 10x is manufactured, the silicon single crystal substrate is processed using etching. In this case, it is preferable to use anisotropic etching as an etching method. Note that the anisotropic etching utilizes the property that the etching rate differs with respect to the plane orientation of the crystal structure.

For example, in anisotropic etching immersed in an alkaline solution such as KOH, the (111) plane has an etching rate of about 1/400 compared to the (100) plane. Accordingly, a structure having an inclination of about 54 ° can be produced in the plane orientation (100), whereas a deep groove can be dug in the plane orientation (110). Therefore, since the arrangement density can be increased while maintaining rigidity, the liquid discharge head 2 may also use a single crystal substrate having the (110) plane orientation. However, it should be noted that in this case, SiO ₂ which is a mask material is also etched.

  Further, the width (length in the short direction) of the pressure chamber 10x is preferably 50 μm or more and 70 μm or less, and more preferably 55 μm or more and 65 μm or less. If the value is larger than this value, the residual vibration becomes large and it is difficult to secure the discharge performance at high frequency. If the value is smaller than this value, the displacement amount of the electromechanical conversion element is lowered, and a sufficient discharge voltage cannot be secured.

The vibration plate 20 is deformed and displaced by the force generated by the electromechanical conversion film 32, and ejects ink droplets in the pressure chamber 10x. Therefore, it is preferable that the diaphragm 20 has a predetermined strength. Specifically, a material in which Si, SiO ₂ , Si ₃ N ₄ or the like is produced by a CVD method or the like can be given.

  In order to ensure the rigidity of the diaphragm 20, the diaphragm 20 can be composed of a plurality of laminated films including a highly rigid film. That is, in order to ensure the discharge performance at a high frequency, it is preferable that the Young's modulus of the diaphragm 20 is 75 GPa or more. However, when a high rigidity film is to be realized with only one layer, the film is peeled off when the film becomes thick. Since a problem arises, it can be adjusted with a film having a slightly low rigidity in between.

  Furthermore, it is preferable to select a material close to the linear expansion coefficient of the lower electrode 31 and the electromechanical conversion film 32 as the material of the diaphragm 20.

In particular, when using PZT as an electromechanical conversion film 32, as the material of the diaphragm 20, 5 × ¹⁰ -6 close to the linear expansion coefficient of ^{PZT 8 × 10 -6 (1 /} K) (1 / K) It is preferable to select a material having a linear expansion coefficient of about 10 × 10 ⁻⁶ (1 / K). It is more preferable to select a material having a linear expansion coefficient of about 7 × 10 ⁻⁶ (1 / K) to 9 × 10 ⁻⁶ (1 / K).

  Specific examples of the material of the diaphragm 20 include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, rhenium oxide, rhodium oxide, palladium oxide, and compounds thereof. These can be produced by a spin coater using a sputtering method or a Sol-gel method.

  The film thickness of the diaphragm 20 is preferably 1 to 3 μm, and more preferably 1.5 to 2.5 μm. If it is smaller than this range, it will be difficult to process the pressure chamber 10x, and if it is larger than this range, it will be difficult to deform and displace, and ink droplet ejection will become unstable.

  As the lower electrode 31 and the upper electrode 33, platinum having high heat resistance and low reactivity can be used as a metal material. However, platinum may not be said to have sufficient barrier properties against lead. In that case, a platinum group element such as iridium or platinum-rhodium, or an alloy film thereof can be used. .

In the case of using platinum as the lower electrode 31 and upper electrode 33, because of poor adhesion between the diaphragm 20 (in particular SiO ₂₎ serving as a _{base, Ti, TiO 2, Ta,} Ta 2 O 5, Ta It is preferable to laminate via an adhesion layer such as ₃ N ₅ . As a method for manufacturing the lower electrode 31 and the upper electrode 33, vacuum film formation such as sputtering or vacuum deposition can be used. As a film thickness of the lower electrode 31 and the upper electrode 33, 0.05-1 micrometer is preferable and 0.1-0.5 micrometer is still more preferable.

Further, in the lower electrode 31 and the upper electrode 33, an oxide electrode film made of SrRuO ₃ or LaNiO ₃ may be formed between the metal material and the electromechanical conversion film 32. It should be noted that the oxide electrode film between the lower electrode 31 and the electromechanical conversion film 32 affects the alignment control of the electromechanical conversion film 32 (for example, a PZT film) produced thereon, so that it is desired to give priority to the alignment. The material selected depends on the orientation.

In the liquid ejection head 2, when PZT is used as the electromechanical conversion film 32 and preferentially oriented to PZT (100), a seed layer such as LaNiO ₃ , TiO ₂ , PbTiO ₃ or the like is formed on the metal material as the lower electrode 31. It is preferable that the PZT film is formed after that.

  Moreover, an SRO film can be used as the oxide electrode film between the upper electrode 33 and the electromechanical conversion film 32, and the film thickness of the SRO film is preferably 20 nm to 80 nm, and more preferably 30 nm to 50 nm. If it is thinner than this film thickness range, sufficient characteristics cannot be obtained for the initial displacement and displacement deterioration characteristics. Beyond this range, the dielectric strength of PZT is very poor and leaks easily.

As the electromechanical conversion film 32, lead zirconate titanate (PZT) can be preferably used. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTiO ₃ ), and the characteristics of PZT differ depending on the ratio of PbZrO ₃ and PbTiO ₃ . For example, the ratio of PbZrO ₃ and PbTiO ₃ is 53:47, and the chemical formula indicates Pb (Zr _0.53 , Ti _0.47 ) O ₃ , PZT generally indicated as PZT (53/47), etc. Can be used.

  As a method for producing the electromechanical conversion film 32, it can be produced by a spin coater using a sputtering method or a Sol-gel method. In that case, since patterning is required, a desired pattern can be obtained by photolithography etching or the like.

  When producing PZT by the Sol-gel method, first, lead acetate, zirconium alkoxide, or titanium alkoxide compound is used as a starting material. And a PZT precursor solution is producible by dissolving in methoxyethanol which is a common solvent, and obtaining a uniform solution. Since the metal alkoxide compound is easily hydrolyzed by moisture in the atmosphere, an appropriate amount of acetylacetone, acetic acid, diethanolamine or the like as a stabilizer may be added to the PZT precursor solution.

  When a PZT film is formed on the entire surface of the lower electrode 31, it is obtained by forming a coating film by a solution coating method such as spin coating, and performing heat treatments such as solvent drying, thermal decomposition, and crystallization. Since the transformation from the coating film to the crystallized film involves volume shrinkage, it is necessary to adjust the concentration of the PZT precursor so that a film thickness of 100 nm or less can be obtained in one step in order to obtain a crack-free film. .

  The thickness of the electromechanical conversion film 32 is preferably 1 μm to 3 μm, and more preferably 1.5 μm to 2.5 μm. If it is smaller than this range, it will be difficult to process the pressure chamber 10x, and if it is larger than this range, it will be difficult to deform and displace, and ink droplet ejection will become unstable.

  Further, when the film thickness is adjusted in the wafer surface by using the spin coating method, the in-plane distribution tendency can be adjusted by changing the application start position of the dispenser or the application amount of the liquid.

  When PZT is used as the electromechanical conversion film 32 and the PZT (100) plane is preferentially oriented, the composition ratio of Zr / Ti is preferably such that the composition ratio Ti / (Zr + Ti) is 0.45 or more and 0.55 or less. 0.48 to 0.52 is more preferable.

  The crystal orientation is represented by ρ (hkl) = I (hkl) / ΣI (hkl). Here, ρ (hkl) is the degree of orientation in the (hkl) plane orientation, I (hkl) is the peak intensity of any orientation, and ΣI (hkl) is the sum of the peak intensities. The degree of orientation of the (100) orientation calculated based on the ratio of the peak intensities of each orientation when the sum of the peak intensities obtained by the θ-2θ measurement of the X-ray diffraction method is 1 is 0.75 or more. It is preferable that it is 0.85 or more. When it is less than this, sufficient piezoelectric strain cannot be obtained, and a sufficient amount of displacement of the electromechanical transducer cannot be secured.

As the electromechanical conversion film 32, an ABO ₃ type perovskite type crystalline film other than PZT may be used. As the ABO ₃ type perovskite crystalline film other than PZT, for example, a lead-free composite oxide film such as barium titanate may be used. In this case, it is possible to prepare a barium titanate precursor solution by using barium alkoxide and a titanium alkoxide compound as starting materials and dissolving them in a common solvent.

These materials are described by the general formula ABO ₃ and correspond to composite oxides containing A = Pb, Ba, Sr B = Ti, Zr, Sn, Ni, Zn, Mg, and Nb as main components. As a specific description thereof, (Pb1-x, Ba) (Zr, Ti) O ₃ , (Pb1-x, Sr) (Zr, Ti) O ₃ are represented, and this is because part of Pb at the A site is Ba. This is the case where it is replaced with Sr. Such substitution is possible with a divalent element, and the effect thereof has an effect of reducing characteristic deterioration due to evaporation of lead during heat treatment.

  Here, the configuration of the liquid discharge head including the wiring and the like will be described. 9A and 9B are diagrams illustrating the wiring of the liquid discharge head according to the first embodiment. FIG. 9A is a cross-sectional view, and FIG. 9B is a plan view. In FIG. 9B, illustration of the insulating protective films 40 and 70 is omitted.

  Referring to FIG. 9, a plurality of wirings 60 are provided on the insulating protective film 40, and an insulating protective film 70 is further provided on the wiring 60. The insulating protective film 40 includes a plurality of openings 40x, and the surface of the lower electrode 31 or the upper electrode 33 is exposed in the openings 40x. The wiring 60 fills the opening 40x and is connected to the upper electrode 33 (part of the contact hole H in FIG. 9B) and the wiring 60 fills the opening 40x and is connected to the lower electrode 31. Includes wiring.

  The insulating protective film 70 includes a plurality of openings 70x, and the surface of each wiring 60 is exposed in each opening 70x. Each wiring 60 exposed in each opening 70x becomes electrode pads 61, 62, and 63. Here, the electrode pad 61 is a common electrode pad, and is connected to the lower electrode 31 common to each electromechanical transducer 30 via the wiring 60. The electrode pads 62 and 63 are individual electrode pads, and are connected to the independent upper electrode 33 for each electromechanical transducer 30 via the wiring 60.

  Next, the polarization processing apparatus will be described. FIG. 10 is a diagram illustrating a schematic configuration of the polarization processing apparatus. The polarization processing apparatus 500 includes a corona electrode 510 and a grid electrode 520. The corona electrode 510 and the grid electrode 520 are connected to a corona electrode power source 511 and a grid electrode power source 521, respectively. A temperature adjustment function is added to the stage 530 for setting the sample, and polarization processing can be performed while applying a temperature up to about 350 ° C. The stage 530 is provided with a ground 540. If this is not added, the polarization process cannot be performed.

  For example, mesh processing is applied to the grid electrode 520, and when a high voltage is applied to the corona electrode 510, ions, charges, and the like generated by corona discharge efficiently drop onto the lower stage 530, and the electric machine It is devised to be injected into the conversion film 32. By adjusting the magnitude of the voltage applied to the corona electrode 510 and the grid electrode 520 and the distance between the sample and each electrode, it is possible to increase or decrease the corona discharge.

  As shown in FIG. 11, when corona discharge is performed using the corona wire 600, molecules 610 in the atmosphere are ionized to generate cations 620. Then, the generated positive ions 620 flow through the pad portion of the electromechanical conversion element 30, so that charges can be injected into the electromechanical conversion element 30.

In this case, it is considered that an internal potential difference is generated by the charge difference between the upper electrode and the lower electrode, and the polarization process is performed. At this time, the charge amount Q required for the polarization treatment is not particularly limited, but it is preferable that a charge amount of 1.0 × 10 ⁻⁸ C or more is accumulated in the electromechanical transducer 30. More preferably, a charge amount of 0 × 10 ⁻⁸ C or more is accumulated. When the value is less than this value, the polarization process cannot be sufficiently performed, and sufficient characteristics cannot be obtained with respect to the displacement deterioration after continuous driving as a piezoelectric actuator of PZT.

  Here, the state of the polarization process can be determined from the PE hysteresis loop of the electromechanical transducer 30. A method of determining the polarization process will be described with reference to FIG. FIG. 12A illustrates the PE hysteresis loop before the polarization process, and FIG. 12B illustrates the PE hysteresis loop after the polarization process.

  Specifically, first, as shown in FIG. 12, a hysteresis loop is measured with an electric field strength of ± 150 kv / cm. Then, when the first polarization at 0 kv / cm is Pin, and the polarization at 0 kv / cm when the voltage is returned to 0 kv / cm after applying a voltage of +150 kv / cm is Pr, the value of Pr−Pind is the polarizability. It is possible to define and determine whether the polarization state is good or bad from this polarizability.

Polarizability Pr-Pind is preferably at 10 [mu] C / cm ² or less, still more preferably 5 [mu] C / cm ² or less. When the polarizability Pr-Pind is larger than this value, sufficient characteristics cannot be obtained with respect to displacement deterioration after continuous driving as a PZT piezoelectric actuator.

  In FIG. 11, the desired polarizability Pr-Pind can be obtained by adjusting the voltage of the corona electrode 510 and the grid electrode 520, the distance between the stage 530 and the corona electrode 510 and the grid electrode 520, and the like. . However, it is preferable to generate a high electric field for the electromechanical conversion film 32 in order to obtain a desired polarizability Pr-Pind.

<Second Embodiment>
In the second embodiment, as an application example, an apparatus for ejecting liquid including the liquid ejection head 2 (see FIG. 3) is illustrated.

  First, an example of an apparatus for discharging a liquid according to the second embodiment will be described with reference to FIGS. FIG. 13 is an explanatory plan view of the main part of the apparatus, and FIG. 14 is an explanatory side view of the main part of the apparatus.

  This apparatus is a serial type apparatus, and the carriage 403 reciprocates in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 spans the left and right side plates 491A and 491B and holds the carriage 403 so as to be movable. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 spanned between the driving pulley 406 and the driven pulley 407.

  A liquid discharge unit 440 in which the liquid discharge head 2 and the head tank 441 according to the first embodiment are integrated is mounted on the carriage 403. The liquid discharge head 2 of the liquid discharge unit 440 discharges, for example, yellow (Y), cyan (C), magenta (M), and black (K) liquids. Further, the liquid ejection head 2 is mounted with a nozzle row composed of a plurality of nozzles 51 arranged in the sub-scanning direction orthogonal to the main scanning direction and the ejection direction facing downward.

  The liquid stored in the liquid cartridge 450 is supplied to the head tank 441 by the supply mechanism 494 for supplying the liquid stored outside the liquid discharge head 2 to the liquid discharge head 2.

  The supply mechanism 494 includes a cartridge holder 451 that is a filling unit for mounting the liquid cartridge 450, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. The liquid cartridge 450 is detachably attached to the cartridge holder 451. Liquid is fed from the liquid cartridge 450 to the head tank 441 by the liquid feeding unit 452 via the tube 456.

  This apparatus includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412 serving as transport means, and a sub-scanning motor 416 for driving the transport belt 412.

  The conveyance belt 412 adsorbs the sheet 410 and conveys it at a position facing the liquid ejection head 2. The transport belt 412 is an endless belt and is stretched between the transport roller 413 and the tension roller 414. The adsorption can be performed by electrostatic adsorption or air suction.

  The transport belt 412 rotates in the sub-scanning direction when the transport roller 413 is rotationally driven by the sub-scanning motor 416 via the timing belt 417 and the timing pulley 418.

  Further, on one side of the carriage 403 in the main scanning direction, a maintenance / recovery mechanism 420 that performs maintenance / recovery of the liquid ejection head 2 is disposed on the side of the transport belt 412.

  The maintenance / recovery mechanism 420 includes, for example, a cap member 421 for capping the nozzle surface (surface on which the nozzles 51 are formed) of the liquid ejection head 2, a wiper member 422 for wiping the nozzle surface, and the like.

  The main scanning movement mechanism 493, the supply mechanism 494, the maintenance / recovery mechanism 420, and the transport mechanism 495 are attached to a housing including the side plates 491A and 491B and the back plate 491C.

  In this apparatus configured as described above, the paper 410 is fed and sucked onto the transport belt 412, and the paper 410 is transported in the sub-scanning direction by the circular movement of the transport belt 412.

  Therefore, the liquid ejection head 2 is driven according to the image signal while moving the carriage 403 in the main scanning direction, thereby ejecting liquid onto the stopped paper 410 to form an image.

  Thus, since this apparatus includes the liquid ejection head according to the first embodiment, a high-quality image can be stably formed.

  Next, another example of the liquid ejection unit according to the second embodiment will be described with reference to FIG. FIG. 15 is an explanatory plan view of the main part of the unit.

  The liquid discharge unit includes a casing portion composed of side plates 491A and 491B and a back plate 491C, a main scanning moving mechanism 493, a carriage 403, and a liquid among the members constituting the liquid discharge device. The discharge head 2 is configured.

  Note that a liquid discharge unit in which at least one of the above-described maintenance and recovery mechanism 420 and the supply mechanism 494 is further attached to, for example, the side plate 491B of the liquid discharge unit may be configured.

  Next, still another example of the liquid discharge unit according to the second embodiment will be described with reference to FIG. FIG. 16 is an explanatory front view of the unit.

  This liquid discharge unit includes a liquid discharge head 2 to which a flow path component 444 is attached and a tube 456 connected to the flow path component 444.

  The flow path component 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path component 444. In addition, a connector 443 that is electrically connected to the liquid discharge head 2 is provided above the flow path component 444.

  In the present application, the “apparatus for discharging liquid” is an apparatus that includes a liquid discharge head or a liquid discharge unit and drives the liquid discharge head to discharge liquid. The apparatus for ejecting liquid includes not only an apparatus capable of ejecting liquid to an object to which liquid can adhere, but also an apparatus for ejecting liquid toward the air or liquid.

  This “apparatus for discharging liquid” may include means for feeding, transporting, and discharging a liquid to which liquid can adhere, as well as a pre-processing apparatus, a post-processing apparatus, and the like.

  For example, as a “liquid ejecting device”, an image forming device that forms an image on paper by ejecting ink, a powder is formed in layers to form a three-dimensional model (three-dimensional model) There is a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that discharges a modeling liquid onto the powder layer.

Further, the “apparatus for ejecting liquid” is not limited to an apparatus in which a significant image such as characters and figures is visualized by the ejected liquid. For example, what forms a pattern etc. which does not have a meaning in itself, and what forms a three-dimensional image are also included.
The above-mentioned “applicable liquid” means that the liquid can be attached at least temporarily and adheres and adheres, or adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording paper, film, cloth, etc., electronic parts such as electronic boards, piezoelectric elements, powder layers (powder layers), organ models, examination cells, and other media. Yes, unless specifically limited, includes everything that the liquid adheres to.

  The material of the above-mentioned “material to which liquid can adhere” is not limited as long as liquid such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics can be adhered even temporarily.

  “Liquid” also includes ink, treatment liquid, DNA sample, resist, pattern material, binder, modeling liquid, or a solution and dispersion containing amino acid, protein, calcium, and the like.

  In addition, the “device for ejecting liquid” includes a device in which the liquid ejection head and the device to which the liquid can adhere move relatively, but is not limited thereto. Specific examples include a serial type apparatus that moves the liquid discharge head, a line type apparatus that does not move the liquid discharge head, and the like.

  In addition to the “device for discharging liquid”, a processing liquid application device for discharging a processing liquid onto a sheet for applying a processing liquid to the surface of the paper for the purpose of modifying the surface of the paper, etc. There is an injection granulating apparatus or the like for granulating raw material fine particles by spraying a composition liquid dispersed in a solution through a nozzle.

  A “liquid ejection unit” is a unit in which functional parts and mechanisms are integrated with a liquid ejection head, and is an assembly of parts related to liquid ejection. For example, the “liquid discharge unit” includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

  Here, the term “integration” refers to, for example, a liquid discharge head, a functional component, and a mechanism that are fixed to each other by fastening, adhesion, engagement, etc., and one that is held movably with respect to the other. Including. Further, the liquid discharge head, the functional component, and the mechanism may be configured to be detachable from each other.

  For example, there is a liquid discharge unit in which a liquid discharge head and a head tank are integrated as in the liquid discharge unit 440 shown in FIG. In some cases, the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter may be added between the head tank and the liquid discharge head of these liquid discharge units.

  In addition, there is a liquid discharge unit in which a liquid discharge head and a carriage are integrated.

  In addition, there is a liquid discharge unit in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably on a guide member constituting a part of the scanning movement mechanism. Further, as shown in FIG. 15, there is a liquid discharge unit in which a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

  Further, as a liquid discharge unit, there is a liquid discharge head, a carriage, and a maintenance / recovery mechanism that are integrated by fixing a cap member that is a part of the maintenance / recovery mechanism to a carriage to which the liquid discharge head is attached. .

  Further, as shown in FIG. 16, there is a liquid discharge unit in which a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and the supply mechanism are integrated. .

  The main scanning movement mechanism includes a guide member alone. The supply mechanism includes a single tube and a single loading unit.

  The “liquid discharge head” is not limited to the pressure generating means to be used. For example, in addition to the piezoelectric actuator as described in the above embodiment (a multilayer piezoelectric element may be used), a thermal actuator using an electrothermal conversion element such as a heating resistor, a diaphragm and a counter electrode are included. An electrostatic actuator or the like may be used.

  Further, the terms “image formation”, “recording”, “printing”, “printing”, “printing”, “modeling”, etc. in the terms of the present application are all synonymous.

[Example 1]
A 6-inch silicon wafer is prepared as the substrate 10, and the substrate 10 is made of SiO ₂ (film thickness 600 nm), Si (film thickness 200 nm), SiO ₂ (film thickness 100 nm), SiN (film thickness 150 nm), SiO ₂ (film thickness). 1300 nm), SiN (150 nm), SiO ₂ (thickness 100 nm), Si (200 nm), SiO ₂ (thickness 600 nm) were formed in this order to produce diaphragm 20.

  At this time, the equivalent Young's modulus in the total thickness was calculated from the rigidity and film thickness of each layer. Furthermore, the thickness distribution of SiN, which has the highest rigidity in a single layer, and the thickness distribution as the total thickness were measured.

  Thereafter, a titanium film (thickness 20 nm) was formed as an adhesion layer on the vibration plate 20 with a sputtering apparatus at a film formation temperature of 350 ° C., and then thermally oxidized at 750 ° C. using RTA (rapid heat treatment). Further, a platinum film (film thickness: 160 nm) was formed on the adhesion layer with a sputtering apparatus at a film formation temperature of 300 ° C., and the lower electrode 31 was produced.

Next, a solution adjusted to Pb: Ti = 1: 1 as a PbTiO ₃ layer serving as an underlayer on the lower electrode 31 and Pb: Zr: Ti = 115: 49: 51 as an electromechanical conversion film 32 are adjusted. And a film was formed by spin coating.

  Regarding the film thickness, the film thickness distribution was adjusted from the film thickness distribution of SiN, which had the highest rigidity, and the distribution tendency as described in Table 1 described later was adjusted.

  For the synthesis of a specific precursor coating solution, lead acetate trihydrate, isopropoxide titanium and isopropoxide zirconium were used as starting materials. Crystal water of lead acetate was dissolved in methoxyethanol and then dehydrated. The lead amount is excessive with respect to the stoichiometric composition. This is to prevent crystallinity deterioration due to so-called lead loss during heat treatment.

  Isopropoxide titanium and isopropoxide zirconium were dissolved in methoxyethanol, the alcohol exchange reaction and the esterification reaction were advanced, and the PZT precursor solution was synthesized by mixing with the methoxyethanol solution in which the lead acetate was dissolved. The PZT concentration was 0.5 mol / liter. PT solutions were also prepared in the same manner as PZT, and using these solutions, a PT layer was first formed by spin coating, dried at 120 ° C., and then the PZT solution was formed by spin coating. Filmed and dried at 120 ° C. → 400 ° C. thermal decomposition.

  After thermal decomposition treatment of the third layer, crystallization heat treatment (temperature: 730 ° C.) was performed by RTA. At this time, the film thickness of PZT was 240 nm. This process was performed a total of 8 times (24 layers) to obtain a PZT film of about 2 μm as the electromechanical conversion film 32.

Next, an SrRuO ₃ film (film thickness 40 nm) was formed as an oxide electrode film constituting the upper electrode 33, and a platinum film (film thickness 125 nm) was formed as a metal film by sputtering. Thereafter, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. is formed by spin coating, a resist pattern is formed by ordinary photolithography, and then a pattern as shown in FIG. 9 is formed using an ICP etching apparatus (manufactured by Samco). Produced. Thereby, the electromechanical transducer 30 was produced on the diaphragm 20.

Next, an Al ₂ O ₃ film having a thickness of 50 nm was formed as an insulating protective film 40 on the electromechanical transducer 30 by using the ALD method. At this time, TMA (Sigma Aldrich) was used for Al as the raw material, and O ₃ generated by an ozone generator was alternately stacked for O, so that film formation proceeded.

Thereafter, as shown in FIG. 9, a contact hole H was formed by etching. Thereafter, Al was formed by sputtering and patterned by etching to form wiring 60, and Si ₃ N ₄ was formed to a thickness of 500 nm as an insulating protective film 70 by plasma CVD. Then, an opening 70 x was provided in the insulating protective film 70 to expose a part of the wiring 60 to form electrode pads 61, 62 and 63. The electrode pad 61 is a common electrode pad, the electrode pads 62 and 63 are individual electrode pads, and the distance between the individual interelectrode pads is 80 μm.

  Thereafter, polarization treatment was performed by corona charging treatment using the polarization treatment apparatus 500. For the corona charging treatment, a tungsten wire of φ50 μm is used. The polarization treatment conditions include a treatment temperature of 80 ° C., a voltage of 9 kV at the corona electrode 510, a voltage of 2.5 kV at the grid electrode 520, a treatment time of 30 s, a distance of 4 mm between the corona electrode 510 and the grid electrode 520, and between the grid electrode 520 and the stage 530. The distance was 4 mm.

  Thereafter, the back surface of the substrate 10 was etched to form a pressure chamber 10x (width 60 μm), whereby the liquid discharge head 2 was obtained. However, the nozzle plate 50 provided with the nozzles 51 is not joined to the lower part of the substrate 10, and the liquid ejection head 2 is in a semi-finished state.

[Example 2]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (film thickness 600 nm), Si (film thickness 200 nm), SiO ₂ (film thickness 95 nm), SiN (film thickness 160 nm), SiO ₂ (film thickness) are prepared on the substrate 10. The diaphragm 20 was formed by sequentially forming a film of 1200 nm), SiN (160 nm), SiO ₂ (thickness 95 nm), Si (200 nm), and SiO ₂ (thickness 600 nm). Other than that was carried out similarly to Example 1, and produced the electromechanical conversion element 30. FIG.

[Example 3]
As the substrate 10 to prepare the silicon wafer 6 inches, SiO ₂ (thickness 600 nm) on the substrate 10, Si (thickness 360nm), SiO ₂ (thickness 100nm), SiO ₂ (film thickness 1300nm), SiO ₂ (film The diaphragm 20 was fabricated by sequentially forming a film having a thickness of 100 nm, Si (360 nm), and SiO ₂ (film thickness 600 nm).

  At this time, the nozzle position of the spin coat and the coating amount are adjusted from the film thickness distribution of Si having the highest film rigidity among the films constituting the diaphragm 20, and the film thickness distribution of the electromechanical conversion film 32 is shown in Table 1. The film thickness distribution as shown in FIG. Other than that was carried out similarly to Example 1, and produced the electromechanical conversion element 30. FIG.

[Example 4]
A 6-inch silicon wafer was prepared as the substrate 10, SiO ₂ (film thickness 2900 nm) was formed on the substrate 10, and the diaphragm 20 was produced with a single layer of SiO ₂ .

At this time, the spin coat nozzle position and the coating amount were adjusted from the SiO ₂ film thickness distribution, and the film thickness distribution of the electromechanical conversion film 32 was adjusted to the film thickness distribution shown in Table 1. Other than that was carried out similarly to Example 1, and produced the electromechanical conversion element 30. FIG.

[Example 5]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (film thickness 600 nm), Si (film thickness 200 nm), SiO ₂ (film thickness 90 nm), SiN (film thickness 170 nm), SiO ₂ (film thickness) are prepared on the substrate 10. 1100 nm), SiN (170 nm), SiO ₂ (thickness 90 nm), Si (200 nm), SiO ₂ (thickness 600 nm) were formed in this order to produce diaphragm 20.

  Thereafter, the electromechanical conversion element 30 was produced in the same manner as in Example 1 except that the temperature of the crystallization heat treatment of the electromechanical conversion element 30 was set to 620 ° C.

[Comparative Example 1]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (film thickness 600 nm), Si (film thickness 200 nm), SiO ₂ (film thickness 85 nm), SiN (film thickness 180 nm), SiO ₂ (film thickness) are prepared on the substrate 10. 1000 nm), SiN (180 nm), SiO ₂ (film thickness 85 nm), Si (200 nm), SiO ₂ (film thickness 600 nm) were formed in this order to produce diaphragm 20.

  At this time, the nozzle position of the spin coat and the coating amount are adjusted from the film thickness distribution of SiN having the highest film rigidity among the films constituting the diaphragm 20, and the film thickness distribution of the electromechanical conversion film 32 is shown in Table 1. The film thickness distribution as shown in FIG. Other than that was carried out similarly to Example 1, and produced the electromechanical conversion element 30. FIG.

[Examination of Examples 1 to 5 and Comparative Example 1]
For the electromechanical transducer 30 of each liquid discharge head 2 produced in Examples 1 to 5 and Comparative Example 1, using a chip corresponding to the position C1 (outer peripheral side of the wafer W) shown in FIG. 20 and the thickness distribution of the electromechanical conversion film 32 were confirmed. Thereafter, the electromechanical transducer 30 was evaluated for electrical characteristics and displacement characteristics (piezoelectric constant).

  As for the displacement characteristics, as shown in FIG. 3, the pressure chamber 10 x was formed by performing excavation from the back surface side of the substrate 10 and evaluated. Specifically, the amount of deformation by applying an electric field (150 kV / cm) was measured with a laser Doppler vibrometer, calculated from the fitting by simulation, and the displacement distribution was also confirmed as well as the film thickness distribution. The evaluation results are shown in Table 1.

なお、表１において、最上欄は各項目の好ましい範囲を示しており、最終的には、Δδ／δ_Ａｖｅを±８％以内に収めることが目標となる。ここで、δは電気機械変換膜３２に１５０ｋｖ／ｃｍの電界強度かけて評価を行ったときの電気機械変換素子３０の変位特性（変位量）であり、Δδは前記配列方向の両端部に位置する電気機械変換素子３０の変位特性δの前記配列方向の傾き（最大値と最小値との差）、δ_Ａｖｅは変位特性δの平均値である。

In Table 1, the uppermost column indicates a preferable range of each item, and finally, Δδ / δ_Ave is set to be within ± 8%. Here, δ is a displacement characteristic (displacement amount) of the electromechanical conversion element 30 when the electromechanical conversion film 32 is evaluated by applying an electric field strength of 150 kv / cm, and Δδ is located at both ends in the arrangement direction. An inclination (difference between the maximum value and the minimum value) of the displacement characteristic δ of the electromechanical conversion element 30 in the arrangement direction, δ_Ave is an average value of the displacement characteristic δ.

  As can be seen from Table 1, in Examples 1 to 5, Δδ / δ_Ave is within the target ± 8%, but in Comparative Example 1, Δδ / δ_Ave is about ± 15%, which is the target. It greatly exceeded ± 8%. In other words, it was confirmed that Δδ / δ_Ave was within the target ± 8% by appropriately adjusting the film thickness distribution of the electromechanical conversion film with respect to the film thickness distribution of the diaphragm.

  The preferred embodiments and the like have been described in detail above, but the present invention is not limited to the above-described embodiments and the like, and various modifications can be made to the above-described embodiments and the like without departing from the scope described in the claims. Variations and substitutions can be added.

  For example, in the above embodiment, the case where the upper electrode is an individual electrode and the lower electrode is a common electrode has been described, but the present invention is not limited to this. That is, the same effect can be obtained even in a configuration in which the upper electrode is a common electrode and the lower electrode is an individual electrode.

DESCRIPTION OF SYMBOLS 1, 2 Liquid discharge head 10 Substrate 10x Pressure chamber 20 Vibrating plate 30 Electromechanical conversion element 31 Lower electrode 32 Electromechanical conversion film 33 Upper electrode 35 Discharge drive device 40, 70 Insulating protective film 40x, 70x Opening 50 Nozzle plate 51 Nozzle 60 Wiring 61, 62, 63 Electrode pad 401 Guide member 403 Carriage 405 Main scanning motor 406 Driving pulley 407 Driven pulley 408 Timing belt 410 Paper 412 Conveying belt 413 Conveying roller 414 Tension roller 416 Sub-scanning motor 417 Timing belt 418 Timing pulley 420 Maintenance Recovery mechanism 421 Cap member 422 Wiper member 440 Liquid discharge unit 441 Head tank 442 Cover 443 Connector 444 Flow path component 450 Liquid cartridge 451 Cartridge holder 452 liquid-feeding unit 456 tubes 491A, 491B plate 491C backplate 493 main scan movement mechanism 494 supplying mechanism 495 transporting mechanism

Japanese Patent No. 3725390

Claims (15)

A diaphragm,
A plurality of electromechanical transducers arranged on the diaphragm, and a discharge driving device comprising:
The electromechanical conversion element includes an electromechanical conversion film,
Δds × Δdp <0, where Δds is an inclination of the film thickness of the diaphragm in the arrangement direction of the electromechanical conversion elements and Δdp is an inclination of the film thickness of the electromechanical conversion film in the arrangement direction. A discharge driving device characterized by that. The diaphragm is formed of a plurality of layers,
2. The ejection drive according to claim 1, wherein Δds_max × Δdp <0, where Δds_max is a thickness gradient of the layer having the largest Young's modulus among the plurality of layers in the arrangement direction. apparatus.   3. The ejection driving device according to claim 1, wherein Δds / Ave_ds is within ± 5%, where Ave_ds is an average film thickness of the diaphragm in the arrangement direction. 4.   4. The ejection according to claim 1, wherein Δdp / Ave_dp is within ± 5% when an average film thickness of the electromechanical conversion film in the arrangement direction is Ave_dp. 5. Drive device. The diaphragm is formed of a plurality of layers,
5. The Δds_max / Ave_ds_max is within ± 5% when an average film thickness of the layer having the largest Young's modulus among the plurality of layers in the arrangement direction is Ave_ds_max. The discharge driving device according to any one of the above.   6. The Young's modulus when the diaphragm is formed from a single layer or the average of the equivalent Young's modulus when the diaphragm is formed from a plurality of layers is 75 GPa or more. The discharge driving device according to any one of the above. The diaphragm is formed of a plurality of layers,
7. The ejection driving device according to claim 1, wherein an average Young's modulus of a layer having the largest Young's modulus among the plurality of layers in the arrangement direction is 150 GPa or more. The diaphragm is formed from a plurality of layers including a _SiO 2, SiN, a layer made of Poly-Si,
8. The ejection driving device according to claim 1, wherein a thickness of the diaphragm is 1 μm or more and 3 μm or less.   The discharge driving apparatus according to claim 1, wherein the electromechanical conversion film has a thickness of 1 μm to 3 μm.   The discharge driving device according to any one of claims 1 to 9, wherein the electromechanical conversion film has a Young's modulus of 80 GPa or more. A discharge driving device according to any one of claims 1 to 10,
Provided corresponding to each of the electromechanical conversion elements, a nozzle for discharging liquid, and a pressurizing chamber to which the nozzle communicates,
A part of the wall of the pressurizing chamber is constituted by the diaphragm,
The liquid discharge head, wherein the discharge driving device pressurizes the liquid in the pressurizing chamber. When evaluating the displacement characteristic δ of the electromechanical conversion element by applying an electric field strength of 150 kv / cm to the electromechanical conversion film,
Δδ / δ_Ave is within ± 8%, where Δδ is the slope of the displacement direction δ of the electromechanical transducers located at both ends of the array direction and Δδ is the average value of the displacement characteristics δ. The liquid discharge head according to claim 11, wherein the liquid discharge head is provided.   A liquid discharge unit comprising the liquid discharge head according to claim 10.   A head tank for storing liquid to be supplied to the liquid discharge head, a carriage on which the liquid discharge head is mounted, a supply mechanism for supplying liquid to the liquid discharge head, a maintenance / recovery mechanism for maintaining and recovering the liquid discharge head, and the liquid The liquid discharge unit according to claim 13, wherein the liquid discharge head is integrated with at least one of a main scanning movement mechanism that moves the discharge head in the main scanning direction.   An apparatus for ejecting liquid, comprising the liquid ejection head according to claim 11 or 12, or the liquid ejection unit according to claim 13 or 14.

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