JP6638371B2 - Liquid discharge head, liquid discharge unit, device for discharging liquid - Google Patents

Description

  The present invention relates to a liquid discharge head, a liquid discharge unit, and a device that discharges liquid.

  2. Description of the Related Art For a liquid ejection head used as an image recording apparatus or an image forming apparatus such as a printer, a facsimile, a copying apparatus, etc., a nozzle for ejecting ink droplets, a pressure chamber communicating with the nozzle, and a piezoelectric element for pressurizing ink in the pressure chamber Are known. Two types of liquid ejection heads have been put into practical use, one using a longitudinal vibration mode actuator and the other using a flexural vibration mode actuator.

  An example of a liquid ejection head includes an individual liquid chamber communicating with an ejection port, a vibration plate provided corresponding to the individual liquid chamber, and a piezoelectric element that generates a pressure for ejecting the liquid. One that discharges liquid in a room from a discharge port can be given. In this liquid discharge head, in the cross-sectional shape of the individual liquid chamber, the side wall of the individual liquid chamber has a curvature such that the inclination of the side wall gradually decreases in a direction away from the diaphragm side (for example, see Patent Document 1). .

  However, in the above-described liquid discharge head, when a plurality of pressure chambers are arranged, a specific variation in the film thickness of the diaphragm in the arrangement direction of the pressure chambers is not considered. Therefore, when a plurality of pressure chambers are arranged, it is not possible to suppress the variation in the amount of displacement of the electromechanical transducer provided in each pressure chamber, and it is difficult to obtain stable ink ejection characteristics. there were.

  The present invention has been made in view of the above, and an object of the present invention is to suppress variations in the displacement of electromechanical transducers provided in each pressure chamber in a liquid ejection head in which a plurality of pressure chambers are arranged. And

The present liquid discharge head is provided with a plurality of structures each including a nozzle for discharging liquid, a pressure chamber communicating with the nozzle, and a discharge driving unit for increasing the pressure of the liquid in the pressure chamber, and each of the structures includes In the body, the discharge driving unit includes a diaphragm constituting a part of a wall of the pressure chamber, and an electromechanical transducer formed on the diaphragm, and each of the discharge driving means in the arrangement direction of the structure. When the length of the pressure chamber is L, the L has an inclination in the arrangement direction, the inclination of the thickness of the diaphragm in the arrangement direction is Δds, and the inclination of the L in the arrangement direction is Δds. Is ΔL, it is required that Δds × ΔL> 0 .

  According to the disclosed technology, in a liquid ejection head in which a plurality of pressure chambers are arranged, it is possible to suppress variations in the amount of displacement of electromechanical transducers provided in each of the pressure chambers.

FIG. 2 is a cross-sectional view (part 1) illustrating the liquid ejection head according to the first embodiment. FIG. 5 is a cross-sectional view illustrating a manufacturing process of the liquid ejection head according to the first embodiment. FIG. 3 is a cross-sectional view (part 2) illustrating the liquid ejection head according to the first embodiment. FIG. 4 is a diagram illustrating a displacement amount in a row of chips in a wafer. FIG. 3 is a diagram (part 1) illustrating distribution of a diaphragm thickness, a liquid chamber width, and a displacement characteristic of an electromechanical conversion film. FIG. 11 is a diagram (part 2) illustrating distributions of the diaphragm thickness, the liquid chamber width, and the displacement characteristics of the electromechanical conversion film. FIG. 10 is a diagram (part 3) illustrating distributions of the diaphragm thickness, the liquid chamber width, and the displacement characteristics of the electromechanical conversion film. FIG. 11 is a diagram (part 4) illustrating the distribution of the diaphragm thickness, the liquid chamber width, and the displacement characteristics of the electromechanical conversion film. FIG. 3 is a diagram illustrating wiring and the like of the liquid ejection head according to the first embodiment. It is a figure which illustrates the schematic structure of a polarization processing apparatus. It is a figure explaining corona discharge. It is a figure which illustrates about a PE hysteresis loop. It is a principal part plane explanatory view of an example of the device which discharges the liquid concerning a 2nd embodiment. It is principal part side explanatory drawing of an example of the apparatus which discharges the liquid which concerns on 2nd Embodiment. FIG. 14 is an explanatory plan view of a main part of another example of the liquid ejection unit according to the second embodiment. FIG. 13 is an explanatory front view of still another example of the liquid ejection unit according to the second 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 ejection head according to the first embodiment. Referring to FIG. 1, the liquid ejection head 1 includes a substrate 10, a vibration plate 20, an electromechanical transducer 30, and an insulating protective film 40. The electromechanical conversion element 30 has a lower electrode 31, an electromechanical conversion film 32, and an upper electrode 33.

  In the liquid ejection 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 transducer 30. The insulating protective film 40 has an opening for selectively exposing 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 nozzles 51 for ejecting ink droplets is joined to a 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, a liquid chamber, or the like) communicating with the nozzle 51 is formed by the nozzle plate 50, the substrate 10, and the vibration plate 20. Is formed. The vibration plate 20 forms a part of the wall surface of the ink flow path. In other words, the pressure chamber 10x is partitioned by the substrate 10 (constituting the side surface), the nozzle plate 50 (constituting the lower surface), and the diaphragm 20 (constituting the upper surface), and communicates with the nozzle 51.

  To manufacture the liquid discharge head 1, first, as shown in FIG. 2, a vibration plate 20, a lower electrode 31, an electromechanical conversion film 32, and an upper electrode 33 are sequentially stacked on a substrate 10. After that, the lower electrode 31, the electromechanical conversion film 32, and the upper electrode 33 are etched into a desired shape, and covered with an 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 pressure chamber 10x is formed by etching the substrate 10 from below. Next, the nozzle plate 50 having the nozzles 51 is joined to the lower surface of the substrate 10 to complete the liquid ejection head 1.

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

  The liquid ejection head 2 includes a plurality of structures each including a nozzle 51 for ejecting the liquid, a pressure chamber 10x communicating with the nozzle 51, and an ejection driving unit 35 for increasing the pressure of the liquid in the pressure chamber 10x. Structure. Here, the ejection driving unit 35 can be configured to include the vibration plate 20 forming a part of the wall of the pressure chamber 10x and the electromechanical conversion element 30 including the electromechanical conversion film 32. The ejection driving unit 35 pressurizes the liquid in the pressure chamber 10x.

  In addition, L shown in FIGS. 1 and 3 indicates the length of each pressure chamber 10x in the arrangement direction of the structures (hereinafter, referred to as the arrangement direction). The length L of each pressure chamber 10x can be appropriately adjusted as described later. For example, the length L of each pressure chamber 10x can be adjusted so as to have an inclination in the arrangement direction. The length L of the pressure chamber 10x may be referred to as a liquid chamber width.

  Next, the displacement of the electromechanical transducer 30 will be described. FIG. 4 is a diagram for explaining a displacement amount in a row of chips in a wafer. FIG. 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 central side of the wafer W. A plurality of electromechanical transducers 30 are arranged in each of the chips C1 to C4. In addition, O. F. Is Orientation Flat. FIG. 4B shows a change in the displacement of the electromechanical transducer 30 in the array direction of the electromechanical transducers 30 (the direction from the chip C1 to the chip C4) in the chips C1 to C4.

  Variations in film thickness, film quality, and the like within the wafer surface can be improved by optimizing each process condition and the like. % Variation occurs, and it is impossible to suppress the variation to almost zero.

  One of the characteristics of the electromechanical transducer 30 that affects the ink ejection amount and the ejection speed at the time of ink ejection is a displacement characteristic (displacement amount). For example, as shown in FIG. 4B, in the chips C1 to C4, there is a tendency that the displacement amount decreases toward the outer periphery. That is, the chips C1 and C4 on the outer peripheral side of the wafer W tend to have a smaller displacement than the chips C2 and C3 on the central side of the wafer W.

  The displacement characteristics themselves are affected by the piezoelectric strain of the piezoelectric material constituting the electromechanical conversion film 32, the size of the pressure chamber 10x, and the thickness of each layer, and from the center to the outer periphery of the thickness and film quality in the wafer surface. Is considered to have caused the result as shown in FIG. In particular, a factor that is high in the process is the contribution of the thickness of the diaphragm 20 and the electromechanical conversion film 32 shown in FIG.

  As described above, the variation in the ink ejection is not a random variation, but a specific piezoelectric having an inclination in a row or between rows of the electromechanical transducers 30 as illustrated in FIG. 4B. It is also necessary to pay attention to performance variations. 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 defective when printed on paper or the like.

  When the liquid ejection head 2 is assembled, by selecting only the chip located at the center of the wafer, it is possible to suppress the outflow of a defective head having a large variation in ejection performance. However, this method is not preferable. This is because, when considering the non-defective rate of the chips on the outer periphery of the wafer, the number of the electromechanical transducers 30 on the outer periphery is defective, which is a significant cost increase factor when considering the total process.

  In addition, with respect to the liquid discharge head 2 manufactured from chips on the outer periphery of the wafer, it is possible to correct the ink discharge amount and the discharge speed fluctuation at the time of ink discharge by adjusting, for example, the voltage waveform at the time of discharge. However, this method is also not preferable. . Since the liquid ejection heads 2 with small variations manufactured from the chip located at the center of the wafer are mixed, it is necessary to prepare a plurality of waveforms in a liquid ejection device having a plurality of liquid ejection heads 2. This is because it causes a cost increase.

  As described above, in order to suppress the variation in the ink ejection amount and the ejection speed at the time of ink ejection, it is preferable that the variation in the piezoelectric performance of the electromechanical conversion film 32 is small. However, in addition to the random variation between the electromechanical transducers 30, there is a specific piezoelectric performance variation such that the plurality of electromechanical transducers 30 arranged in the liquid ejection head 2 have a slope between or within rows. Therefore, it is necessary to suppress such specific variation in piezoelectric performance.

  For example, if there is a stable variation among those with a high contribution, a means for suppressing the variation in displacement by canceling the items can be considered.

  However, when there are a plurality of components that make a small contribution to the variation in the displacement amount, or when stable variations do not occur (for example, in a certain wafer processing, the film thickness distribution from the center to the outer periphery tends to become thicker or thinner). In a case where there is a tendency or a certain variation is not always present), it is preferable that the control is performed using a parameter that has a relatively later processing step and has a high contribution to the variation in displacement.

  In the present embodiment, the length L of the pressure chamber 10x as described in FIGS. 1 and 3 greatly contributes to the variation in displacement, and is provided later as a processing step. If all the variations can be grasped, it is possible to suppress the variations in the displacement amount by intentionally generating the variations when the pressure chamber 10x is manufactured.

  For example, when a single-layer diaphragm is formed on a 6-inch wafer, the O.D. From part F, anti-O. It is assumed that the film thickness distribution toward the portion F tends to be thicker at a position located at the outer peripheral chip. Based on this result, when the pressure chamber is manufactured by etching, the dimension distribution on the 6-inch wafer for the length L of the pressure chamber 10x as shown in FIGS. O. F part and anti-O. By adjusting the length L so as to extend to the F portion, it is possible to suppress the influence of the variation in displacement generated due to the variation of the diaphragm.

  5 to 8 are diagrams illustrating the distribution of the diaphragm thickness, the liquid chamber width, and the displacement characteristics of the electromechanical conversion film, and the thickness distribution of the diaphragm and the electromechanical conversion film on a 6-inch wafer. And the displacement characteristic distribution From part F to O. The portion F is shown. Note that Wout indicates that the chip is located on the outer peripheral portion of the wafer.

  In FIG. 5, when the thickness of the diaphragm increases from the center to the outer periphery, and there is almost no variation in the length L (= liquid chamber width), the displacement characteristic also has a variation with a slope at the outer periphery. You can see that.

  As shown in FIG. 6, while the thickness of the diaphragm increases from the center to the outer periphery, the dimensional variation of the liquid chamber width is increased from the center to the outer periphery, thereby suppressing the displacement inclination at the outer periphery. can do.

  Here, the thickness of the diaphragm (total thickness when the diaphragm is formed of a plurality of layers) is ds, the average thickness of the diaphragm in the arrangement direction is Ave_ds, and the diaphragm in the arrangement direction is Is Δds, and the inclination of the length L of the pressure chamber in the arrangement direction is ΔL.

  The gradient of the film thickness is defined as a graph of a change in the film thickness of the diaphragm and a dimensional change in the width of the liquid chamber (a change in the length L) in the arrangement direction in the chip. Slope (tangent slope).

  As shown in FIG. 6, in the chip (Wout portion) located on the outer peripheral portion of the wafer, the direction of the inclination of Δds is different in both Wouts, but the inclination at each point in each Wout is substantially constant. Tend to be. In this case, within each Wout, Δds is a substantially constant value (one-way gradient) at any point on the graph. The same applies to ΔL.

  In order to suppress the variation in the displacement amount of the electromechanical transducer in the arrangement direction, it is preferable that Δds / Ave_ds be within ± 5%. Further, when the average of the length L of the pressure chambers in the arrangement direction is Ave_L, it is preferable that ΔL / Ave_L be within ± 2.5%. If the thickness is outside this range, it becomes difficult to control the variation in the dimension of the liquid chamber width so as to cancel the variation in the film thickness of the diaphragm.

  In order to ensure high-frequency discharge performance, 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 increase the film thickness. For example, the Young's modulus when the diaphragm is formed from a single layer, or the average of 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 from a plurality of layers, it is preferable that the layer having the highest Young's modulus among the plurality of layers in the arrangement direction has an average Young's modulus of 150 GPa or more. Further, the Young's modulus of the electromechanical conversion film in the arrangement direction is preferably 80 GPa or more.

In particular, the diaphragm 20 is preferably formed of a plurality of layers including a silicon oxide film (SiO ₂ ), a silicon nitride film (SiN), polysilicon (Poly-Si), or the like, in consideration of stress design. Further, it is preferable that the diaphragm 20 is formed to have a thickness of 1 μm or more and 3 μm or less. This makes it possible to ensure high-frequency ejection performance.

  In the case where the diaphragm is formed of a plurality of layers, if the film itself having high rigidity (the average Young's modulus in the arrangement direction is 150 GPa or more) among the layers varies, this greatly affects the variation in displacement characteristics. . For example, FIG. 7 shows that in order to secure a rigidity of 75 GPa or more as a diaphragm, the 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 liquid chamber width increases. The example in the case where there is almost no variation is shown. In the case of FIG. 7, it can be seen that the displacement characteristic also has a variation having a slope at the outer peripheral portion.

  As shown in FIG. 8, while the thickness of the high-rigidity film (high-rigidity diaphragm layer) increases from the center to the outer periphery, the dimensional variation of the liquid chamber width is increased from the center to the outer periphery. Thus, the displacement inclination at the outer peripheral portion can be suppressed.

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

  As described above, when the thickness of the diaphragm (a layer having high rigidity in the case of a plurality of layers) increases from the center to the outer periphery of the wafer, the pressure chamber when the pressure chamber is manufactured by etching after that. The length L (liquid chamber width) is increased from the center of the wafer to the outer periphery. This makes it possible to offset the film thickness distribution of the diaphragm by the distribution of the length L of the pressure chamber, thereby suppressing the variation in the amount of displacement of each electromechanical transducer.

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

  Hereinafter, suitable materials for forming the liquid ejection head 2 will be described in more detail. As the substrate 10, a silicon single crystal substrate is preferably used, and usually preferably has a thickness of 100 to 600 μm. There are three types of plane orientations, (100), (110), and (111). In the semiconductor industry, generally, (100) and (111) are widely used. A single crystal substrate having a (100) plane orientation can be used.

  Further, when manufacturing the pressure chamber 10x, the silicon single crystal substrate is processed by using etching. In this case, it is preferable to use anisotropic etching. Note that the anisotropic etching utilizes a property that an etching rate is different from a plane orientation of a 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. Therefore, a structure having an inclination of about 54 ° can be manufactured in the plane orientation (100), while a deep groove can be dug in the plane orientation (110). Therefore, since the arrangement density can be increased while maintaining the rigidity, the liquid discharge head 2 may use a single crystal substrate having the (110) plane orientation. However, in this case, it should be noted that SiO _{2 as the} mask material is also etched.

  In the present embodiment, the length L of the pressure chamber at the outer peripheral portion of the wafer is lengthened or shortened depending on the state of the film thickness distribution of the diaphragm. The adjustment can be made by adjusting the length (arbitrarily increasing or decreasing the length of the wafer outer peripheral portion from the mask design stage).

  Ave_L, which is the average of the length L 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 becomes difficult to secure the discharge performance at a high frequency. If the value is smaller than this value, the displacement of the electromechanical transducer decreases, and it becomes impossible to secure a sufficient discharge voltage.

The vibration plate 20 is deformed and displaced by receiving 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 prepared from Si, SiO ₂ , Si ₃ N _4, or the like by a CVD method or the like can be given.

  In order to secure the rigidity of the diaphragm 20, the diaphragm 20 can be composed of a plurality of laminated films including a film having high rigidity. In other words, in order to ensure high-frequency discharge performance, it is preferable that the Young's modulus of the diaphragm 20 be 75 GPa or more. Since a problem occurs, the adjustment can be performed with a film having a slightly low rigidity interposed therebetween.

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

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 〜１０10 × 10 ⁻⁶ (1 / K). It is further 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, 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 thickness of the diaphragm 20 is preferably 1 to 3 μm, more preferably 1.5 to 2.5 μm. If it is smaller than this range, it becomes difficult to process the pressure chamber 10x, and if it is larger than this range, it becomes difficult to deform and displace, and the ejection of ink droplets becomes 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, and in that case, a platinum group element such as iridium or platinum-rhodium, or an alloy film of these can be used. .

When platinum is used for the lower electrode 31 and the upper electrode 33, Ti, TiO ₂ , Ta, Ta ₂ O ₅ , and Ta are used because of poor adhesion to the diaphragm 20 (especially, SiO ₂ ) as a base. it is preferable to laminate via an adhesive layer, such as ₃ N _5. As a method for forming the lower electrode 31 and the upper electrode 33, a vacuum film formation such as a sputtering method or a vacuum deposition can be used. The thickness of the lower electrode 31 and the upper electrode 33 is preferably 0.05 to 1 μm, more preferably 0.1 to 0.5 μm.

Furthermore, 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. Note that the oxide electrode film between the lower electrode 31 and the electromechanical conversion film 32 affects the orientation control of the electromechanical conversion film 32 (for example, a PZT film) formed thereon. The material selected depends on the orientation.

In the liquid ejection head 2, when PZT is used as the electromechanical conversion film 32 and PZT (100) is preferentially oriented, a seed layer of 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 and then a PZT film is formed.

  Further, an SRO film can be used as an oxide electrode film between the upper electrode 33 and the electromechanical conversion film 32, and the thickness of the SRO film is preferably 20 nm to 80 nm, more preferably 30 nm to 50 nm. If the thickness is smaller than this range, sufficient initial displacement and displacement deterioration characteristics cannot be obtained. If it exceeds this range, the dielectric breakdown voltage of PZT is very poor, and leakage tends to occur.

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 between PbZrO ₃ and PbTiO ₃ . For example, the ratio of PbZrO ₃ to PbTiO ₃ is 53:47, and Pb (Zr _0.53 , Ti _0.47 ) O ₃ in chemical formula, PZT generally represented as PZT (53/47), etc. Can be used.

  The electromechanical conversion film 32 can be formed 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, a lead acetate, a zirconium alkoxide, or a titanium alkoxide compound is used as a starting material. Then, a PZT precursor solution can be prepared by dissolving in methoxyethanol, which is a common solvent, to obtain a uniform solution. Since the metal alkoxide compound is easily hydrolyzed by atmospheric moisture, an appropriate amount of acetylacetone, acetic acid, diethanolamine or the like may be added as a stabilizer 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 each of heat treatments of solvent drying, thermal decomposition, and crystallization. Since the transformation from a coating film to a crystallized film involves volume shrinkage, it is necessary to adjust the concentration of the PZT precursor so as to obtain a film thickness of 100 nm or less in a single step in order to obtain a crack-free film. .

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

  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 or more and 0.52 or less.

  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 an arbitrary orientation, and ΔI (hkl) is the sum of the respective peak intensities. The degree of orientation of the (100) orientation, which is calculated based on the ratio of the peak intensity of each orientation when the sum of the peak intensities obtained in the θ-2θ measurement of the X-ray diffraction method is 1, is 0.75 or more. Is preferable, and it is more preferable that it is 0.85 or more. If it is less than this, sufficient piezoelectric strain cannot be obtained, and the displacement of the electromechanical transducer cannot be sufficiently 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 type crystalline film other than PZT, for example, a lead-free composite oxide film such as barium titanate may be used. In this case, a barium titanate precursor solution can be prepared by using a barium alkoxide or a titanium alkoxide compound as a starting material and dissolving it in a common solvent.

These materials are described by the general formula _{ABO 3, A = Pb, Ba} , Sr B = Ti, Zr, Sn, Ni, Zn, Mg, composite oxide corresponds mainly composed of Nb. As specific description _{(Pb1-x, Ba) (} Zr, Ti) O 3, (Pb1-x, Sr) (Zr, Ti) O 3, expressed as which part of Pb of the A site Ba And Sr. Such substitution is possible if it is a divalent element, and its effect is to reduce the characteristic deterioration due to evaporation of lead during heat treatment.

  Here, the configuration of the liquid ejection head including the wiring and the like will be described. FIGS. 9A and 9B are diagrams illustrating wirings and the like of the liquid ejection 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 protection film 40, and an insulating protection film 70 is further provided on the wiring 60. The insulating protective film 40 has 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 (the portion of the contact hole H in FIG. 9B), and the wiring 60 fills the opening 40x and is connected to the lower electrode 31. And wiring.

  The insulating protective film 70 has a plurality of openings 70x, and the surface of each wiring 60 is exposed in each opening 70x. The respective wires 60 exposed in the respective openings 70x become the 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 of the electromechanical transducers 30 via the wiring 60. The electrode pads 62 and 63 are individual electrode pads, and are connected to the upper electrode 33 independent for each electromechanical transducer 30 via the wiring 60.

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

  The grid electrode 520 is, for example, subjected to mesh processing, and when a high voltage is applied to the corona electrode 510, ions and charges generated by corona discharge efficiently pour down to the lower stage 530, and the electric machine It is designed to be injected into the conversion film 32. By adjusting the magnitude of the voltage applied to the corona electrode 510 or the grid electrode 520 or the distance between the sample and each electrode, the intensity of the corona discharge can be increased.

  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 cations 620 flow through the pad portions of the electromechanical transducer 30 to charge the electromechanical transducer 30.

In this case, it is considered that an internal potential difference occurs due to a 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 process 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 conversion element 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 processing cannot be performed sufficiently, and sufficient characteristics of displacement deterioration after continuous driving as a PZT piezoelectric actuator cannot be obtained.

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

  Specifically, first, as shown in FIG. 12, the hysteresis loop is measured with an electric field strength of ± 150 kv / cm. When the initial polarization at 0 kv / cm is Pind, and when the polarization at 0 kv / cm when the voltage is returned to 0 kv / cm after application of a voltage of +150 kv / cm is Pr, the value of Pr-Pind is the polarization rate. By defining the polarizability, it is possible to judge whether the polarization state is good or bad.

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

  In FIG. 11, a 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, when trying to obtain a desired polarizability Pr-Pind, it is preferable to generate a high electric field with respect to the electromechanical conversion film 32.

<Second embodiment>
In the second embodiment, as an application example, an apparatus for discharging a liquid including the liquid discharge head 2 (see FIG. 3) will be described.

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

  This device is a serial type device, 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 is bridged between the left and right side plates 491A and 491B, and movably holds the carriage 403. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via a timing belt 408 spanned between the driving pulley 406 and the driven pulley 407.

  On the carriage 403, 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. The liquid discharge head 2 of the liquid discharge unit 440 discharges, for example, liquid of each color of yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection head 2 has a nozzle row composed of a plurality of nozzles 51 arranged in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with 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, which is a filling section for mounting the liquid cartridge 450, a tube 456, a liquid sending unit 452 including a liquid sending pump, and the like. The liquid cartridge 450 is detachably mounted on the cartridge holder 451. The liquid is sent from the liquid cartridge 450 to the head tank 441 by the liquid sending unit 452 via the tube 456.

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

  The transport belt 412 attracts the paper 410 and transports it at a position facing the liquid discharge head 2. The transport belt 412 is an endless belt, and is stretched between a transport roller 413 and a tension roller 414. Suction can be performed by electrostatic suction or air suction.

  The transport belt 412 is rotated in the sub-scanning direction by rotating the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

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

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

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

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

  Therefore, by driving the liquid discharge head 2 according to the image signal while moving the carriage 403 in the main scanning direction, the liquid is discharged onto the stopped paper 410 to form an image.

  As described above, since the 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 a main part of the unit.

  The liquid discharge unit includes a housing portion including side plates 491A and 491B and a back plate 491C, a main scanning moving mechanism 493, a carriage 403, It is composed of a discharge head 2.

  It should be noted that a liquid ejection 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 ejection unit may be configured.

  Next, still another example of the liquid ejection 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 the liquid discharge head 2 to which the flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

  The flow channel component 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path component 444. A connector 443 for making an electrical connection with the liquid ejection head 2 is provided above the flow path component 444.

  In the present application, a “device that discharges liquid” is a device that includes a liquid discharge head or a liquid discharge unit and drives the liquid discharge head to discharge liquid. The device that discharges a liquid includes not only a device that can discharge a liquid to which a liquid can be attached, but also a device that discharges a liquid into the air or into the liquid.

  The “device that discharges liquid” may include means for feeding, transporting, and discharging paper to which liquid can be attached, as well as a pre-processing device and a post-processing device.

  For example, as a "device for ejecting liquid", an image forming apparatus that ejects ink to form an image on paper, and a powder is formed in layers to form a three-dimensional object (three-dimensional object) There is a three-dimensional modeling device (three-dimensional modeling device) that discharges a modeling liquid to the formed powder layer.

Further, the "device for discharging liquid" is not limited to a device in which a significant image such as a character or a figure is visualized by the discharged liquid. For example, those that form a pattern or the like that has no meaning in itself, and those that form a three-dimensional image are also included.
The above-mentioned "thing to which a liquid can be attached" means a thing to which a liquid can be attached at least temporarily, such as a thing which adheres and adheres, a thing which adheres and penetrates, and the like. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth; electronic components such as electronic substrates and piezoelectric elements; powder layers (powder layers); organ models; and media such as inspection cells. Yes, unless otherwise specified, includes everything to which a liquid adheres.

  The material to which the above-mentioned "liquid can be attached" may be paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics or any other liquid that can be attached even temporarily.

  The “liquid” also includes inks, processing liquids, DNA samples, resists, pattern materials, binders, modeling liquids, or solutions and dispersions containing amino acids, proteins, and calcium.

  In addition, the "device for discharging liquid" includes a device in which a liquid discharge head and a device to which liquid can adhere are relatively moved, but are not limited thereto. Specific examples include a serial device that moves the liquid ejection head, a line device that does not move the liquid ejection head, and the like.

  Other examples of the "device for discharging liquid" include a processing liquid coating device for discharging a processing liquid onto a sheet in order to apply the processing liquid to the surface of the paper for the purpose of modifying the surface of the paper, and a raw material. There is an injection granulation apparatus or the like that granulates fine particles of a raw material by spraying a composition liquid in which a composition is dispersed in a solution through a nozzle.

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

  Here, the term “integration” means, for example, one in which the liquid ejection head and the functional component or mechanism are fixed to each other by fastening, bonding, engagement, or the like, or one in which one is movably held with respect to the other. Including. Further, the liquid ejection head, the functional component, and the mechanism may be configured to be detachable from each other.

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

  There is a liquid discharge unit in which a liquid discharge head and a carriage are integrated.

  Further, as a liquid discharge unit, there is a liquid discharge head in which a liquid discharge head is movably held by a guide member constituting a part of a scanning moving mechanism, and the liquid discharging head and the scanning moving mechanism are integrated. As shown in FIG. 15, there is a liquid discharge unit in which a liquid discharge head, a carriage, and a main scanning moving mechanism are integrated.

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

  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 a liquid discharge head and a supply mechanism are integrated. .

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

  Further, the "liquid ejection head" is not limited to a pressure generating means to be used. For example, in addition to the piezoelectric actuator described in the above embodiment (a laminated 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 provided. An actuator using an electrostatic actuator or the like may be used.

  Further, image forming, recording, printing, printing, printing, modeling, and the like in the terms of the present application are all synonymous.

[Example 1]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (thickness: 600 nm), Si (thickness: 200 nm), SiO ₂ (thickness: 100 nm), SiN (thickness: 150 nm), SiO ₂ (thickness: The diaphragm 20 was formed by sequentially forming films of SiN (150 nm), SiN (150 nm), SiO ₂ (film thickness 100 nm), Si (200 nm), and SiO ₂ (film thickness 600 nm).

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

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

Next, a solution in which Pb: Ti = 1: 1 is adjusted as a PbTiO ₃ layer serving as a base layer on the lower electrode 31 and a solution in which Pb: Zr: Ti is adjusted to 115: 49: 51 as the electromechanical conversion film 32. Was prepared, and a film was formed by spin coating.

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

  Titanium isopropoxide and zirconium isopropoxide were dissolved in methoxyethanol, an alcohol exchange reaction and an esterification reaction were advanced, and a PZT precursor solution was synthesized by mixing with the methoxyethanol solution in which lead acetate was dissolved. This PZT concentration was 0.5 mol / liter. A solution of PT is also prepared in the same manner as PZT. Using these solutions, a PT layer is first formed by spin coating, and after film formation, dried at 120 ° C., and then the PZT solution is formed by spin coating. The film was dried at 120 ° C. and then thermally decomposed at 400 ° C.

  After the thermal decomposition treatment of the third layer, a crystallization heat treatment (at a temperature of 730 ° C.) was performed by RTA. At this time, the film thickness of PZT was 240 nm. This process was performed eight times (24 layers) in total, and a PZT film of about 2 μm was obtained 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 Ohkasha Co., Ltd. is formed by a spin coating method, a resist pattern is formed by ordinary photolithography, and a pattern as shown in FIG. 9 is formed using an ICP etching apparatus (manufactured by Samco). Produced. As a result, the electromechanical transducer 30 was formed on the diaphragm 20.

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

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

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

  Then, the pressure chamber 10x was formed by etching the back surface of the substrate 10 to obtain the liquid discharge head 2. At this time, by adjusting the length of the outer periphery of the wafer arbitrarily (the central value of the length L = 60 μm) for the mask used for forming the resist pattern, ΔL and the like were adjusted in the range shown in Table 1. However, the nozzle plate 50 having the nozzles 51 is not joined to the lower portion of the substrate 10, and the liquid discharge head 2 is in a semi-finished state.

[Example 2]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (thickness: 600 nm), Si (thickness: 200 nm), SiO ₂ (thickness: 95 nm), SiN (thickness: 160 nm), and SiO ₂ (thickness: The diaphragm 20 was manufactured by sequentially forming films of 120 nm), SiN (160 nm), SiO ₂ (95 nm in thickness), Si (200 nm), and SiO ₂ (600 nm in thickness). Other than that, the liquid ejection head 2 (semi-finished state) was produced in the same manner as in Example 1.

[Example 3]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (thickness: 600 nm), Si (thickness: 360 nm), SiO ₂ (thickness: 100 nm), SiO ₂ (thickness: 130 nm), and SiO ₂ (film) The diaphragm 20 was formed by sequentially forming a film of thickness 100 nm), Si (360 nm), and SiO ₂ (film thickness 600 nm). Other than that, the liquid ejection head 2 (semi-finished state) was produced in the same manner as in Example 1.

[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 made of a single layer of SiO ₂ . Other than that, the liquid ejection head 2 (semi-finished state) was produced in the same manner as in Example 1.

[Example 5]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (thickness: 600 nm), Si (thickness: 200 nm), SiO ₂ (thickness: 90 nm), SiN (thickness: 170 nm), and SiO ₂ (thickness: The diaphragm 20 was formed by sequentially forming films of 110 nm), SiN (170 nm), SiO ₂ (film thickness 90 nm), Si (200 nm), and SiO ₂ (film thickness 600 nm). Other than that, the liquid ejection head 2 (semi-finished state) was produced in the same manner as in Example 1.

[Comparative Example 1]
A 6-inch silicon wafer is prepared as the substrate 10, and SiO ₂ (thickness: 600 nm), Si (thickness: 200 nm), SiO ₂ (thickness: 85 nm), SiN (thickness: 180 nm), and SiO ₂ (thickness: The diaphragm 20 was manufactured by sequentially forming films of 100 nm), SiN (180 nm), SiO ₂ (85 nm in thickness), Si (200 nm), and SiO ₂ (600 nm in thickness). Other than that, the liquid ejection head 2 (semi-finished state) was produced in the same manner as in Example 1.

[Examination of Examples 1 to 5 and Comparative Example 1]
With respect to the electromechanical transducer 30 of each of the liquid ejection heads 2 manufactured in Examples 1 to 5 and Comparative Example 1, a diaphragm was used by using a chip corresponding to the position C1 (the outer peripheral side of the wafer W) shown in FIG. 20 and the length L of the pressure chamber 10x were confirmed. Thereafter, the electrical characteristics and the displacement characteristics (piezoelectric constant) of the electromechanical transducer 30 were evaluated.

  As for the displacement characteristics, as shown in FIG. 3, a pressure chamber 10x was formed by excavating from the back surface side of the substrate 10, and evaluation was performed. Specifically, the amount of deformation due to the application of an electric field (150 kV / cm) was measured with a laser Doppler vibrometer, calculated from the adjustment by simulation, and the displacement distribution as well as the film thickness distribution was confirmed. Table 1 shows the evaluation results.

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 shows a preferable range of each item, and finally, the goal is to keep Δδ / δ_Ave within ± 8%. Here, δ is a displacement characteristic (displacement amount) of the electromechanical conversion element 30 when the evaluation is performed by applying an electric field strength of 150 kv / cm to the electromechanical conversion film 32, and Δδ is a displacement characteristic of the electromechanical conversion element 30. The inclination of δ in the arrangement direction (difference between the maximum value and the minimum value) and δ_Ave are the average values of the displacement characteristics δ.

  As can be seen from Table 1, for Examples 1 to 5, Δδ / δ_Ave is within the target ± 8%, but for Comparative Example 1, Δδ / δ_Ave is about ± 15%, which is the target. It greatly exceeded ± 8%. That is, it was confirmed that Δδ / δ_Ave could be kept within the target ± 8% by appropriately adjusting the size distribution of the length L of the pressure chamber with respect to the film thickness distribution of the diaphragm.

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

  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 in a configuration in which the upper electrode is a common electrode and the lower electrode is an individual electrode.

1, 2 Liquid discharge head 10 Substrate 10x Pressure chamber 20 Vibration plate 30 Electromechanical conversion element 31 Lower electrode 32 Electromechanical conversion film 33 Upper electrode 35 Discharge driving means 40, 70 Insulation protection 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 Followed 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 Maintaining 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

JP 2008-155472 A

Claims (7)

A plurality of structures each including a nozzle for discharging a liquid, a pressure chamber communicating with the nozzle, and a discharge driving unit for increasing the pressure of the liquid in the pressure chamber, are arranged,
In each of the structures, the discharge driving unit includes a diaphragm constituting a part of a wall of the pressure chamber, and an electromechanical transducer formed on the diaphragm,
When the length of each of the pressure chambers in the arrangement direction of the structure is L, the L has an inclination in the arrangement direction ,
A liquid ejection head , wherein Δds × ΔL> 0, where Δds is the inclination of the film thickness of the diaphragm in the arrangement direction and ΔL is the inclination of L in the arrangement direction . A plurality of structures each including a nozzle for discharging a liquid, a pressure chamber communicating with the nozzle, and a discharge driving unit for increasing the pressure of the liquid in the pressure chamber, are arranged,
In each of the structures, the discharge driving unit includes a diaphragm constituting a part of a wall of the pressure chamber, and an electromechanical transducer formed on the diaphragm,
When the length of each of the pressure chambers in the arrangement direction of the structure is L, the L has an inclination in the arrangement direction ,
The diaphragm is formed from a plurality of layers,
A liquid ejection head , wherein Δds_max × ΔL is> 0, where Δds_max is a thickness gradient of a layer having the largest Young's modulus among the plurality of layers in the arrangement direction . The diaphragm is formed of a plurality of layers including a layer made of SiO ₂ , SiN, and Poly-Si,
Liquid discharge head according to claim 1 or 2, wherein the thickness of the diaphragm is 1μm or more 3μm or less. When the displacement characteristic δ of the electromechanical conversion element was evaluated by applying an electric field strength of 150 kv / cm to the electromechanical conversion film constituting the electromechanical conversion element,
2. The method according to claim 1, wherein Δδ / δ_Ave is within ± 8%, where Δδ is the inclination of the displacement characteristic δ of the electromechanical transducer in the arrangement direction and δ_Ave is the average value of the displacement characteristics δ. The liquid discharge head according to any one of claims 3 to 3 . A liquid discharge unit, characterized in that it comprises a liquid discharge head according to any one of claims 1 to 4. 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 and recovery mechanism for maintaining and recovering the liquid discharge head, and the liquid The liquid ejection unit according to claim 5 , wherein at least one of a main scanning movement mechanism for moving the ejection head in the main scanning direction and the liquid ejection head are integrated. Claims 1 to 4 any one liquid discharge head according to the, or an apparatus for discharging a liquid, characterized in that it comprises a liquid discharge unit according to claim 5 or 6.

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