JP2018154033A - Liquid discharge head, method for manufacturing liquid discharge head, liquid discharge unit, and apparatus for discharging liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of variation in the degree of bending of a diaphragm between electromechanical conversion elements, and to obtain good ejection performance. SOLUTION: A plurality of nozzles and a plurality of pressure chambers communicating with the nozzles are formed side by side, and a pressure chamber forming substrate in which a dummy pressure chamber is formed on an end side and a pressure chamber forming substrate are provided on one surface of the pressure chamber forming substrate. A part of the vibrating plate layer that constitutes the wall surface of the pressure chamber and the dummy pressure chamber, the electromechanical conversion element 30 provided corresponding to each pressure chamber, and the dummy electricity provided corresponding to each dummy pressure chamber. At least the most of the mechanical conversion element 34, the electrode pad 62 electrically connected to the electromechanical conversion element 30, the dummy electrode pad 63 electrically connected to the dummy electromechanical conversion element 34, and the dummy electrode pad 63. A guard ring wiring 64 formed so as to face at least a part of the dummy electrode pad 63 located at the end thereof is provided. [Selection diagram] FIG. 13

Description

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

  A liquid discharge head used in a printer, a facsimile machine, a copying apparatus, or the like has a nozzle that discharges liquid, a pressure chamber that communicates with the nozzle, and an electromechanical conversion element such as a piezoelectric element that pressurizes the liquid in the pressure chamber. Things 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.

  As an example of using the flexural vibration mode, for example, a uniform piezoelectric material layer is formed by a film forming technique over the entire surface of the diaphragm, and this piezoelectric material layer is cut into a shape corresponding to the pressure chamber by a lithography method. A device in which an electromechanical conversion element is formed so as to be independent of each pressure chamber is known.

  It is known that such an electromechanical conversion element is subjected to polarization treatment. In other words, the piezoelectric crystal included in the electromechanical conversion film forming the electromechanical conversion element has a random polarization direction. It suppresses displacement deterioration after continuous driving of the mechanical transducer.

  Further, in the liquid discharge head, in order to discharge bubbles at the time of filling the liquid and improve the liquid filling property, on the end side in the arrangement direction of the drive channel having the electromechanical conversion element for discharging the liquid, It is known to provide a dummy channel having a dummy electromechanical transducer that does not discharge droplets.

  For example, Patent Document 1 discloses a nozzle, a liquid chamber, an electromechanical conversion element, a first terminal electrode connected to a first drive electrode on the substrate side of the electromechanical conversion element, and an electromechanical conversion element. A plurality of second terminal electrodes connected to the second drive electrode on the side opposite to the substrate side are provided, and the plurality of second terminal electrodes are arranged so as to be arranged at a predetermined interval. A droplet discharge head is disclosed in which a dummy terminal electrode is provided at a position adjacent to an end of a row of terminal electrodes.

  By providing a dummy channel on the end side of the drive channel as in Patent Document 1, when performing polarization processing, the charge injection is concentrated on the dummy terminal electrode, to the individual electrode of the drive channel located at the end. Charge concentration can be suppressed.

  However, if the polarization of the dummy electromechanical transducer is advanced too much, the deflection of the diaphragm at that portion affects the degree of deflection of the diaphragm at the position of the electromechanical transducer in the drive channel on the end side. I found out. As described above, if the vibration deflection between the electromechanical transducers varies, the ejection performance of the liquid ejection head is affected.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid ejection head that can suppress the occurrence of variation in the degree of bending of the diaphragm between electromechanical transducers and obtain good ejection performance.

  In order to achieve this object, a liquid discharge head according to the present invention includes a plurality of nozzles that discharge liquid and a plurality of pressure chambers for liquid discharge that communicate with the nozzles arranged side by side in a predetermined direction. A pressure chamber forming substrate in which at least one dummy pressure chamber is disposed on the end side of the pressure chamber in a direction, and one surface of the pressure chamber forming substrate, a part of which is provided in the pressure chamber and the pressure chamber A diaphragm layer constituting a wall surface of the dummy pressure chamber, an electromechanical conversion element provided on the diaphragm layer corresponding to each pressure chamber, and provided on the diaphragm layer corresponding to each dummy pressure chamber A dummy electromechanical transducer, an electrode pad electrically connected to the electromechanical transducer, a dummy electrode pad electrically connected to the dummy electromechanical transducer, and the dummy electrode pad. The dummy electrode pads located on at least the outermost end, in which and a wiring formed so as to be opposed to at least a portion.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the variation in the bending state of the diaphragm between electromechanical conversion elements can be suppressed, and favorable discharge performance can be obtained.

It is sectional drawing which illustrates a liquid discharge head. It is sectional drawing which illustrates the manufacturing process of a liquid discharge head. It is sectional drawing which illustrates a liquid discharge head. It is a figure which illustrates the wiring etc. of a liquid discharge head. It is a figure explaining the bending of a diaphragm. It is a figure explaining the definition of the bending amount of a diaphragm. 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. FIG. 6 is a top view illustrating a liquid discharge head. FIG. 6 is a top view illustrating a liquid discharge head. FIG. 6 is a top view illustrating a liquid discharge head. FIG. 3 is a top view (1) illustrating a liquid ejection head according to the first embodiment. (A) It is sectional drawing in the dotted-line part of FIG. 13, (b) It is sectional drawing in the dashed-dotted line part of FIG. FIG. 3 is a top view (2) illustrating the liquid ejection head according to the first embodiment. FIG. 10 is a top view illustrating a liquid ejection head according to a second embodiment. FIG. 10 is a top view illustrating a liquid ejection head according to a third embodiment. FIG. 6 is a top view illustrating a liquid discharge head illustrating a state connected to a drive IC. It is principal part plane explanatory drawing of an example of the apparatus which discharges a liquid. It is principal part side explanatory drawing of an example of the apparatus which discharges a liquid. It is principal part top explanatory drawing of the other example of a liquid discharge unit. It is front explanatory drawing of the other example of a liquid discharge unit. It is a figure explaining a holding substrate.

  Hereinafter, the configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

(Liquid discharge head)
[First Embodiment]
<Configuration of liquid discharge head>
FIG. 1 is a cross-sectional view of a liquid discharge head 1 showing an embodiment of the liquid discharge head. The liquid discharge head 1 includes a substrate 10, a diaphragm 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 ejection head 1, the diaphragm 20 is formed on the substrate 10, and the lower electrode 31 of the electromechanical transducer 30 is formed on the diaphragm 20. In addition, an electromechanical conversion film 32 is formed in a predetermined region of the lower electrode 31, and an upper electrode 33 is further 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 nozzles 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. It is formed. The diaphragm 20 forms a 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 ejection head 2 includes a structure (liquid ejection head 1) including a nozzle 51 that ejects liquid, a pressure chamber 10x that communicates with the nozzle 51, and ejection drive means that boosts the liquid in the pressure chamber 10x. It is a structure in which a plurality are arranged in a predetermined direction. Here, the discharge driving means can be configured to include the diaphragm 20 constituting a part of the wall of the pressure chamber 10 x and the electromechanical conversion element 30 including the electromechanical conversion film 32.

  In the liquid discharge head 2, the portion of the structure (dummy pressure chamber, diaphragm 20, electromechanical transducer 30) that does not discharge liquid is referred to as a dummy channel 4 (dummy ch). In the head 2, the portion of the structure (pressure chamber 10x, diaphragm 20, electromechanical transducer 30) that discharges liquid is referred to as a drive channel 3 (drive ch).

  Next, the configuration of the liquid ejection head 2 including wiring and the like will be described. 4A and 4B are diagrams illustrating the wiring of the liquid ejection head 2, and FIG. 4A is a cross-sectional view and FIG. 4B is a plan view. In addition, in FIG.4 (b), illustration of the insulation protective films 40 and 70 is abbreviate | omitted.

  In the example of FIG. 4, the insulating protective film 40 is composed of two layers (insulating protective films 40a and 40b). A plurality of wirings 60 are provided on the second-layer insulating protective film 40 b, 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. 4B) 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 and 62. 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 pad 62 is an individual electrode pad, and is connected to an independent upper electrode 33 for each electromechanical transducer 30 via a wiring 60.

<Bending (curvature) of diaphragm>
By the way, in the process of manufacturing the liquid ejection head 2, when the pressure chamber 10x is manufactured, the diaphragm 20 is bent (curved) so as to protrude toward the pressure chamber 10x as shown in FIG. For this reason, the diaphragm 20 is formed in a state bent in a convex shape toward the pressure chamber 10x. Depending on the amount of deflection of the diaphragm 20, the amount of displacement of the diaphragm 20 is affected. Further, if the vibration plate 20 is bent, residual vibration is generated when ink is ejected. In order to suppress the residual vibration, it is necessary to generate a predetermined waveform. However, it is necessary to reduce the frequency of the predetermined waveform, and it is difficult to ensure the discharge performance at a high frequency.

In order to ensure high-frequency ejection performance, it is necessary to increase the rigidity of the diaphragm 20, the electromechanical conversion film 32, and the insulating protective film 40, and it is necessary to use a material having a high Young's modulus or to increase the thickness. . In the liquid discharge head 2, the diaphragm 20 is 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. be able to. It is preferable that the thickness of the diaphragm 20 is 1 μm or more and 3 μm or less. Furthermore, by setting the Young's modulus of the diaphragm 20 to 75 GPa or more and 95 GPa or less, it is possible to ensure the discharge performance at a high frequency.

  Next, the bending amount of the diaphragm 20 will be described. First, the definition of the deflection amount of the diaphragm 20 will be described with reference to FIG. In order to calculate the deflection amount of the diaphragm 20, a deflection distribution of the diaphragm 20 illustrated in FIG. 6A is acquired from the pressure chamber 10x side using a deflection meter (CCI3000, manufactured by Ametech).

  Calculation of the radius of curvature R of the diaphragm 20 based on the acquired deflection distribution will be described. As illustrated in FIG. 5, the central portion of the diaphragm 20 has a large amount of bending, and both end portions have a small amount of bending. Therefore, in the deflection distribution of the diaphragm 20 illustrated in FIG. 6A acquired using a deflection meter, the center is based on the points A and B at both ends where the deflection is minimized. A point C (center point of deflection) is obtained. Next, let X be the distance between points A and B at both ends and the center point C of deflection. Then, two points D and E at a distance of 0.8X with respect to the center point C of bending are obtained. Next, as shown in FIG. 6B, an intersection of a line connecting the points D and E and a perpendicular to the center point C is defined as a point F, and a distance between the points F and C is defined as a distance Y. This distance Y can be obtained from the difference between the height at points D and E in the deflection distribution and the height at the center point C. If the center of the curvature circle is the point O, the distance between the points O and F is calculated. it can. Therefore, the radius of curvature R can be calculated using the three-square theorem in the right triangle composed of the points O, E, and F.

  In the following description, unless otherwise specified, the curvature radius R is calculated by the above calculation method, but the calculation method of the curvature radius R of the diaphragm 20 is limited to the method shown in FIG. Instead, for example, in the deflection distribution of the diaphragm 20, the center point of the deflection (the point C) is obtained, and the point C and two points that are separated from the point C by two predetermined distances on both ends respectively. It may be calculated based on the coordinate points.

<Material of liquid discharge head>
Next, a suitable material and the like constituting the liquid discharge head 2 will be described. 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 by 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 250 μm or less, and more preferably 60 μm or more and 150 μm or less.

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. 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 10 μm, and more preferably 2 to 5 μm.

  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, SiO2) serving as a _{base, Ti, TiO 2, Ta,} Ta 2 O 5, Ta 3 it is preferable to laminate via an adhesion layer of N ₅ and the like. 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, and therefore 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.

  Further, an SRO film can be used as the 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, and more preferably 30 nm to 50 nm.

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 Pb (Zr0.53, Ti0.47) O ₃ in the chemical formula, PZT generally indicated as PZT (53/47), etc. are used. be able to.

  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.

  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 to 3 μm, and more preferably 1.5 to 2.5 μm.

  As the electromechanical conversion film 32, an ABO 3 type perovskite type crystalline film other than PZT may be used. As the ABO3 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, 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 ABO3, and correspond to composite oxides containing A = Pb, Ba, Sr B = Ti, Zr, Sn, Ni, Zn, Mg, and Nb as main components. The specific description is expressed as (Pb _1-x , Ba) (Zr, Ti) O ₃ , (Pb _1-x , Sr) (Zr, Ti) O ₃ , which is the same as Pb of the A site. This is a case where the part Ba or Sr is substituted. 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.

  As the material for the insulating protective film 40, it is necessary to select a material that prevents damage to the piezoelectric element due to the film forming and etching processes and is difficult to transmit moisture in the atmosphere. preferable.

In order to obtain high protection performance with a thin film, it is preferable to use an oxide, a nitride, or a carbonized film. However, a material having high adhesion to an electrode material, a piezoelectric material, and a diaphragm material as a base of the insulating protective film 40 is used. It is necessary to select. In addition, it is necessary to select a film forming method that does not damage the piezoelectric element. That is, a plasma CVD method in which a reactive gas is turned into plasma and deposited on a substrate, or a sputtering method in which a film is formed by causing a plasma to collide with a target material and flying away is not preferable. Examples of preferable film forming methods include vapor deposition and ALD (Atomic Layer Deposition), but ALD is preferable because of the wide choice of materials that can be used. As a preferable material of the insulating protective film 40, an oxide film used for a ceramic material such as Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , TiO ₂ is exemplified. In particular, by using the ALD method, a thin film having a very high film density can be produced and damage in the process can be suppressed.

  The insulating protective film 40 needs to be thin enough to secure the protection performance of the electromechanical transducer 30 and at the same time, as thin as possible so as not to inhibit the displacement of the diaphragm 20. A preferable film thickness of the insulating protective film 40 is in the range of 20 nm to 100 nm.

A configuration in which the insulating protective film 40 has two layers is also conceivable. In this case, in order to increase the thickness of the second insulating protective film, a configuration in which the second insulating protective film is opened in the upper electrode 33 so as not to significantly disturb the vibration displacement of the diaphragm 20 may be used. At this time, as the second insulating protective film, any oxide, nitride, carbide, or a composite compound thereof can be used, but SiO ₂ generally used in semiconductor devices can be used. Arbitrary methods can be used for the film formation, and a CVD method and a sputtering method can be exemplified, and it is preferable to use a CVD method capable of forming an isotropic film in consideration of the step coverage of the pattern forming portion such as the electrode forming portion. The film thickness of the second insulating protective film needs to be a film thickness that does not cause dielectric breakdown by the voltage applied to the lower electrode 31 and the wiring 60. That is, it is necessary to set the electric field strength applied to the insulating protective film within a range not causing dielectric breakdown. Further, considering the surface property of the base of the second insulating protective film, pinholes, etc., the film thickness is required to be 200 nm or more, and more preferably 500 nm or more.

  The function of the insulating protective film 70 is a passivation layer that functions as a protective layer of the wiring 60. As shown in FIG. 4, the upper electrode 33 and the lower electrode 31 are covered except for the positions of the electrode pads 61 and 62 (opening 70 x). This makes it possible to use inexpensive Al or an alloy material mainly composed of Al as the electrode material. As a result, the liquid discharge head 2 with low cost and high reliability can be obtained.

As the material of the insulating protective film 70, any inorganic material or organic material can be used, but it is necessary to use a material with low moisture permeability. Examples of the inorganic material include oxides, nitrides, and carbides, and examples of the organic material include polyimide, acrylic resin, and urethane resin. However, an organic material is not suitable because it requires a thick film. Therefore, it is preferable to use an inorganic material that can exhibit a wiring protection function with a thin film. In particular, it is preferable to use Si ₃ N ₄ on the Al wiring because it is a proven technology for semiconductor devices.

  The film thickness is preferably 200 nm or more, and more preferably 500 nm or more.

  Further, a structure having openings on the electromechanical transducer 30 and the diaphragm 20 around it is preferable. This is the same reason that the individual liquid chamber region of the insulating protective film 40 is thinned. As a result, the liquid ejection head 2 with high efficiency and high reliability can be obtained.

Since the electromechanical conversion element 30 is protected by the insulating protective films 40 and 70, photolithography and dry etching can be used to form the opening. The area of the electrode pads 61 and 62 is preferably 50 × 50 μm ² or more, and more preferably 100 × 300 μm ² or more.

  The material of the wiring 60 is preferably a metal electrode material made of any one of an Ag alloy, Cu, Al, Au, Pt, and Ir. As a manufacturing method, a sputtering method or a spin coating method is used, and then a desired pattern is obtained by photolithography etching or the like. The film thickness is preferably from 0.1 to 20 μm, more preferably from 0.2 to 10 μm.

  Further, the contact resistance in the contact hole portion (for example, 10 μm × 10 μm) is preferably 10Ω or less for the lower electrode 31, 1Ω or less for the upper electrode 33, and more preferably 5Ω or less for the lower electrode 31. 33 is 0.5Ω or less.

<Polarization device>
Next, the polarization processing apparatus will be described. FIG. 7 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. 8, when corona discharge is performed using a 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.

  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. 9A illustrates a PE hysteresis loop before polarization processing, and FIG. 9B illustrates a PE hysteresis loop after polarization processing.

  Specifically, first, as shown in FIG. 9, 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. In FIG. 7, 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.

<Guard ring wiring>
As described above, in the liquid ejection head 2, in order to discharge the bubbles at the time of filling the liquid and improve the liquid filling property, the drive channel 3 having the electromechanical conversion element that discharges the liquid is arranged in the arrangement direction. It is known that a dummy channel 4 having a dummy electromechanical conversion element that does not discharge droplets is disposed on the end side.

  The dummy channel 4 has a configuration similar to the layer configuration of the drive channel 3 described so far. That is, a dummy pressurizing chamber is formed in the same manner as the pressure chamber 10x, and the dummy electromechanical transducer 34 having the same configuration as the diaphragm 20 and the electromechanical transducer 30 and the insulating protective film are formed on the dummy pressurizing chamber. 40 and 70 are formed.

  FIG. 10 is a top view on the end side of the liquid discharge head 2 having the dummy channel 4 on the end side of the drive channel 3, and the end of the drive channel 3 in the arrangement direction (that is, the arrangement direction of the pressure chambers 10 x). An example in which three dummy channels 4 are provided on the side is shown. As already described with reference to FIG. 4, the upper electrode 33 of the electromechanical transducer 30 of the drive channel 3 is connected to the wiring 60 through the opening 40x of the insulating protective film 40 (not shown in FIG. 10). In the wiring 60, an electrode pad 62 is formed in the opening 70 x of the insulating protective film 70. In the example of FIG. 10, the opening 70 x of the insulating protective film 70 is formed in the arrangement direction so as to include the plurality of electrode pads 62, but may be opened only at the position of each electrode pad 62. Good.

  On the other hand, since the liquid discharge drive is not performed in the dummy channel 4, the dummy electromechanical conversion element 34 of the dummy channel 4 is pulled out of the dummy electromechanical conversion element 34 and the electrodes are connected as in the example shown in FIG. It is not the structure which provides a pad.

  As in the example shown in FIG. 10, in the configuration in which the dummy channel 4 does not have a terminal electrode (electrode pad) provided by drawing wiring from the dummy electromechanical transducer 34, the dummy channel 4 is subjected to polarization processing (corona discharge processing). In FIG. 5, no charge was injected, and it was found that the amount of deflection of the diaphragm 20 in the dummy channel 4 (FIG. 5) was very small compared to the drive channel 3. That is, since the amount of contraction of the electromechanical conversion film 32 increases as the polarization progresses due to the corona discharge treatment, the amount of bending increases. At this time, the amount of bending of the drive channel 3 at the end close to the dummy channel 4 is Under the influence of the deflection of the dummy channel 4, it becomes slightly smaller.

  In contrast, in the present embodiment, first, as shown in FIG. 11, in the dummy channel 4, the wiring 60 is drawn from the dummy electromechanical conversion element 34 to provide the electrode pad (dummy electrode pad 63).

  That is, the upper electrode 33 of the dummy electromechanical transducer 34 of the dummy channel 4 is connected to the wiring 60 through the opening 40x of the insulating protective film 40 (not shown in FIG. 11). The wiring 60 is connected to the insulating protective film 70. A dummy electrode pad 63 is formed in the opening 70x.

  In the example of FIG. 11, the opening 70x of the insulating protective film 70 is formed in the arrangement direction so as to include the plurality of electrode pads 62 and the dummy electrode pads 63, but as shown in FIG. You may open only in the position of each electrode pad 62 and the dummy electrode pad 63. FIG. The same applies to the following configuration examples.

  In this way, by performing the polarization process in the state where the wiring 60 is drawn out from the dummy electromechanical conversion element 34 of the dummy channel 4 and the dummy electrode pad 63 is provided, the charge injection is concentrated on the dummy electrode pad 63 and the end portion Charge concentration on the electrode pad 62 of the drive channel 3 on the side can be suppressed, and variations in the deflection amount and the polarizability can be suppressed.

  However, as a result of further studies by the inventors of the present application, as shown in FIGS. 11 and 12, in the configuration in which the dummy channel 4 and the dummy electrode pad 63 are provided, the polarization of the dummy electromechanical transducer 34 is advanced by the polarization process, If excessive charge concentration occurs in the dummy electrode pad 63, the bending of the vibration plate 20 at the position of the dummy channel 4 causes the vibration plate at the position of the electromechanical transducer 30 of the drive channel 3 on the end side. It turned out that it affects the degree of bending of 20.

  Therefore, in the liquid discharge head according to the present embodiment, a plurality of nozzles (nozzles 51) for discharging liquid and a plurality of pressure chambers (pressure chambers 10x) for liquid discharge communicating with the nozzles are formed side by side in a predetermined direction. A pressure chamber forming substrate (substrate 10) on which at least one dummy pressure chamber is disposed on the end side of the pressure chamber in a predetermined direction is formed, and a part of the pressure chamber forming substrate is provided on one surface of the pressure chamber forming substrate. A diaphragm layer (diaphragm layer 20) constituting wall surfaces of the pressure chamber and the dummy pressure chamber, an electromechanical transducer (electromechanical transducer 30) provided on the diaphragm layer corresponding to each pressure chamber, A dummy electromechanical transducer (dummy electromechanical transducer 34) provided on the diaphragm layer corresponding to the dummy pressure chamber, and electrode pads (electrode pads 61, 62) electrically connected to the electromechanical transducer , Dami A dummy electrode pad (dummy electrode pad 63) electrically connected to the electromechanical conversion element and at least a part of the dummy electrode pad located at the outermost end of the dummy electrode pad are opposed to at least a part thereof. And formed wiring (guard ring wiring, guard wiring) 64.

  FIG. 13 is a top view of the liquid ejection head 2 according to the first embodiment. In addition to the example shown in FIG. 11, the liquid discharge head 2 shown in FIG. 13 further has a predetermined interval with respect to the dummy electrode pad 63 of the dummy channel 4 located at the outermost end and faces at least a part thereof. Thus, a guard ring wiring 64 is provided. By providing the guard ring wiring 64, surplus charges concentrated on the dummy electrode pad 63 can be released to the guard ring wiring 64, and the charge concentration on the dummy electrode pad 63 can be avoided.

  14A is a cross-sectional view of the liquid ejection head 2 in a direction (dotted line portion in FIG. 13) orthogonal to the arrangement direction of the pressure chambers 10x at the position where the guard ring wiring 64 is formed. FIG. 14B is a cross-sectional view of the liquid ejection head 2 in the arrangement direction of the pressure chambers 10x at the position where the guard ring wiring 64 is formed (the chain line portion in FIG. 13).

  As shown in FIG. 14, the guard ring wiring 64 is formed on the insulating protective film 40 and is electrically connected to the lower electrode 31 through the contact hole H on the other end side of the end facing the dummy electrode pad 63. Yes. The other end side of the end portion of the guard ring wiring 64 facing the dummy electrode pad 63 is preferably electrically connected to the lower electrode 31 as shown in FIG. In this way, by making the guard ring wiring 64 conductive to the lower electrode 31 laminated on the relatively low resistance diaphragm layer 20, the charge injected into the guard ring wiring 64 is vibrated via the lower electrode 31. It can be moved to the plate layer 20. In addition, when the other end side of the guard ring wiring 64 can be connected to another layer which can move the electric charge injected into the guard ring wiring 64, it may be connected thereto.

  The guard ring wiring 64 is a metal electrode material made of Al, for example. The guard ring wiring 64 is preferably a metal electrode material made of any one of an Ag alloy, Cu, Al, Au, Pt, and Ir, similarly to the wiring 60. As a manufacturing method, a sputtering method or a spin coating method is used, and then a desired pattern is obtained by photolithography etching or the like. The film thickness is preferably from 0.1 to 20 μm, more preferably from 0.2 to 10 μm.

  In the example of FIG. 13, an example in which the guard ring wiring 64 is provided for the dummy electrode pad 63 of the dummy channel 4 located at the extreme end is shown. Here, as shown in FIG. 13, it is preferable to provide the guard ring wiring 64 only for the dummy electrode pad 63 of the dummy channel 4 located at the extreme end. For example, as shown in FIG. 64 may be provided continuously from the dummy channel 4 located at the end to the predetermined number of dummy electrode pads 63. Further, when the guard ring wiring 64 is provided for the electrode pads of a plurality of channels, the guard ring wiring 64 may be formed including the electrode pad 62 on the drive channel 3 side. Further, the guard ring wiring 64 includes the dummy electrode pad 63 of the dummy channel 4 located at the extreme end (left end) shown in FIG. 13 to the dummy electrode pad 63 of the dummy channel 4 located at the right end (not shown). It may be formed.

  The shape of the guard ring wiring 64 at the position facing the dummy electrode pad 63 is preferably formed in an L shape so as to face the two sides of the dummy electrode pad 63, as shown in FIG. The guard ring wiring 64 only needs to be provided at a position facing at least a part of the dummy electrode pad 63, and the range and shape thereof are not particularly limited, but the circumferential length of the dummy electrode pad 63 is 50. By providing them so as to oppose each other at a position equal to or greater than%, charge concentration on the dummy electrode pad 63 can be suitably avoided.

  The width of the guard ring wiring 64 is preferably 20 μm or more and 100 μm or less. The distance between the guard ring wiring 64 and the dummy electrode pad 63 is preferably 3 μm or more and 50 μm or less.

  As described above, in the liquid ejection head 2 according to the present embodiment, the dummy electrode pad of the wiring 60 connected to the dummy electromechanical transducer 34 of at least the dummy channel 4 in the endmost part in the arrangement direction of the drive channels 3. A guard ring wiring 64 is provided at a position facing at least a part of 63 and is electrically connected to the lower electrode 31. Thereby, surplus charges generated at the end of the dummy channel 4 due to the polarization process can be released via the guard ring wiring 64. Thereby, the polarizability variation and the deflection amount variation can be suppressed.

  Therefore, the bending of the diaphragm 20 at the dummy electromechanical transducer element 34 affects the bending state of the diaphragm 20 at the position of the electromechanical transducer 30 of the drive channel 3 on the end side. This can be avoided, and the occurrence of variation in the degree of bending of the diaphragm 20 between the electromechanical transducers 30 of the drive channel 3 that discharges the liquid can be suppressed, and good discharge performance can be obtained.

[Second Embodiment]
Hereinafter, other embodiments of the liquid discharge head according to the present invention will be described. In addition, the description about the same point as the said embodiment is abbreviate | omitted suitably.

  FIG. 16 is a top view of the liquid ejection head 2 according to the second embodiment. In addition to the configuration shown in FIG. 13, the liquid discharge head 2 shown in FIG. 16 is a device in which a short-circuit wiring 65 for conducting the dummy electrode pad 63 and the lower electrode 31 is produced after the polarization process. Thereby, in the dummy channel 4, it can be set as the electrically stable state by short-circuiting between the upper electrode 33 and the lower electrode 31. FIG.

[Third Embodiment]
FIG. 17 is a top view of the liquid ejection head 2 according to the third embodiment. As shown in FIG. 16, the liquid discharge head 2 shown in FIG. 17 covers at least a portion where the short-circuit wiring 65 is formed after the short-circuit wiring 65 that connects the dummy electrode pad 63 and the lower electrode 31 is formed. Furthermore, by producing the insulating protective film 80, it is possible to suppress the occurrence of problems such as an insulation failure of the short-circuit wiring 65. The insulating protective film 80 is a passivation layer that functions as a protective layer for the guard ring wiring 64 and the shorting wiring 65, and the material, film thickness, and the like can be configured in the same manner as the insulating protective film 70.

  After the liquid discharge head 2 shown in the first to third embodiments is configured, as shown in FIG. 18, the electrode pad 62 of the drive channel 3 is a drive IC 35 as discharge control means for controlling liquid discharge. Are electrically connected by wire bonding 36. Since the dummy channel 4 is not intended to discharge liquid, the dummy electrode pad 63 is not electrically connected to the drive IC 35.

(Device for discharging liquid)
An example of an apparatus for ejecting liquid having the liquid ejection head according to the present invention will be described with reference to FIGS. FIG. 19 is an explanatory plan view of the main part of the apparatus, and FIG.

  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 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.

  As described above, since this apparatus includes the above-described liquid discharge head, there is no liquid discharge failure due to a diaphragm drive failure, stable liquid discharge characteristics are obtained, and high-quality images are stably formed. can do.

(Liquid discharge unit)
Next, an example of a liquid discharge unit having the liquid discharge head according to the present invention will be described with reference to FIG. FIG. 21 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 movement mechanism 493, a carriage 403, and a liquid discharge portion among members constituting a liquid discharge device. The 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, another example of the liquid discharge unit having the liquid discharge head according to the present invention will be described with reference to FIG. FIG. 22 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 ejection 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 significant images such as characters and figures are 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, as a “device for discharging liquid”, a processing liquid coating apparatus for discharging a processing liquid onto a sheet in order to apply the processing liquid to the surface of the sheet for the purpose of modifying the surface of the sheet, 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 with 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 that constitutes a part of the scanning movement mechanism. Further, as shown in FIG. 21, there is a liquid discharge unit in which a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

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

  In addition, as shown in FIG. 22, 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.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

  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.

  Examples of the present invention will be described below.

[Example 1]
A 6-inch silicon wafer was prepared as the substrate 10, and a thermal oxide film (film thickness 1 μm) was produced as the diaphragm 20 on the substrate 10. 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 400 ° 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.

  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 made by Tokyo Ohka Co., Ltd. (TSMR8800) is formed by spin coating, a resist pattern is formed by ordinary photolithography, and then a pattern as shown in FIG. 4 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. 4, a contact hole H was formed by etching. Thereafter, Al was formed by sputtering, and patterned by etching to form wiring 60, and guard ring wiring 64 was produced. Si ₃ N ₄ was deposited as an insulating protective film 70 to a thickness of 500 nm by plasma CVD. Then, an opening 70x was provided in the insulating protective film 70 to expose part of the wiring 60 and the guard ring wiring 64, and the structure shown in FIG. 13 was fabricated.

  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 corona electrode 510 voltage of 9 kV, a grid electrode 520 voltage of 1.5 kV, 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.

[Example 2]
After the polarization treatment in Example 1, the liquid discharge head 2 was produced in the same manner as in Example 1 except that the short-circuit wiring 65 and the insulating protective film 80 were produced as shown in FIG.

[Comparative Example 1]
A liquid discharge head 2 was manufactured in the same manner as in Example 1 except that a structure without the guard ring wiring 64 was manufactured as shown in FIG.

[Comparative Example 2]
A liquid ejection head 2 was produced in the same manner as in Example 1 except that a structure without the dummy electrode pad 63 was produced as shown in FIG.

[Examination of Examples 1-2 and Comparative Examples 1-2]
For the liquid ejection heads 2 created in Examples 1 and 2 and Comparative Examples 1 and 2, a drive IC 35 was further produced and electrically joined to the electrode pads 61 and 62 of the drive channel 3 by wire bonding 36.

  Thereafter, the back surface of the substrate 10 was etched to form a pressure chamber 10x and a dummy pressure chamber, and 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.

  At this time, as shown in FIG. 23, in order to hold the pressure chamber 10x, the holding substrate 15 having the number of recesses 15x corresponding to the electromechanical conversion elements 30 formed on the back surface was used. Specifically, before the pressure chamber 10x is formed, the holding substrate 15 is bonded onto the substrate 10 through an adhesive layer so that each electromechanical conversion element 30 is accommodated in each recess 15x. Thereafter, the back surface of the substrate 10 was etched to form a pressure chamber 10x.

  For the electromechanical transducer 30 of each liquid ejection head 2 produced in Examples 1 and 2 and Comparative Examples 1 and 2, using a chip corresponding to the position of C3 shown in FIG. The displacement characteristics (piezoelectric constant) and the bending amount of the diaphragm were evaluated. In addition, about evaluation of the displacement characteristic, vibration evaluation was implemented from the pressure chamber 10x side. Specifically, the amount of deformation due to electric field application (150 kV / cm) was measured with a laser Doppler vibrometer and calculated from fitting by simulation. Further, the bending amount (curvature radius) of the diaphragm 20 was measured using a white light interference type surface shape measuring machine.

  Then, the polarizability variation of the diaphragm 20 in each end channel group, the difference in the radius of curvature R, and the displacement difference (Δδ / δ_ave) were obtained, and the results are summarized in Table 1. Δ is a displacement characteristic of the electromechanical conversion film 32 when evaluation is performed with an electric field strength of 150 kv / cm, Δδ is a difference in inclination of the displacement characteristic δ with respect to the arrangement direction of the electromechanical conversion film 32, and δ_ave is a displacement. This is the average value of the characteristic δ.

  As can be seen from Table 1, in Examples 1 and 2 and Comparative Example 1, the displacement difference is within the target 8% as the displacement inclination in the channel group from each end in the chip to 20ch. Comparative Example 2 had a large variation of 13.0%. Further, it was confirmed that the displacement difference can be more suitably suppressed in Examples 1 and 2 compared to Comparative Example 1 in which no guard ring is provided.

  In Table 1, in Examples 1 and 2 and Comparative Example 1, the difference in the radius of curvature R of the diaphragm 20 in the channel group from each end to 20ch is 1500 μm or less, but in Comparative Example 2 it is 2000 μm. Is bigger than.

  Next, the nozzle plate 50 provided with the nozzles 51 is bonded to the lower part of the substrate 10 of each liquid discharge head 2 (semi-finished liquid discharge head 2) manufactured in Examples 1-2 and Comparative Examples 1-2. The liquid discharge head 2 was completed and liquid discharge evaluation was performed.

  Specifically, the discharge state when an applied voltage of −10 to −30 V was applied with a simple Push waveform using ink having a viscosity adjusted to 5 cp was confirmed. As a result, it was confirmed that the liquid ejection heads 2 produced in Examples 1 and 2 and Comparative Example 1 can be ejected from any nozzle 51 and can be ejected at high frequency. On the other hand, with respect to the liquid discharge head 2 manufactured in Comparative Example 2, it was confirmed that the liquid discharge speed greatly varied in the nozzles 51 corresponding to the channel groups at the respective end portions in the head.

1, 2 Liquid discharge head 3 Drive channel 4 Dummy channel 10 Substrate 10x Pressure chamber 15 Holding substrate 15x Recess 20 Diaphragm 30 Electromechanical transducer 31 Lower electrode 32 Electromechanical transducer 33 Upper electrode 34 Dummy electromechanical transducer 35 Driving IC
36 Wire bonding 40 (40a, 40b) Insulating protective film 40x Opening 50 Nozzle plate 51 Nozzle 60 Wiring 61 Electrode pad (common electrode pad)
62 Electrode pads (individual electrode pads)
63 Dummy electrode pad 64 Guard ring wiring 65 Short-circuit wiring 70 Insulating protective film 70x Opening 80 Insulating protective film

JP 2014-177049 A

Claims (10)

A plurality of nozzles for discharging liquid;
A pressure chamber in which a plurality of liquid discharge pressure chambers communicating with the nozzle are formed side by side in a predetermined direction, and at least one dummy pressure chamber disposed on the end side of the pressure chamber in the predetermined direction is formed A forming substrate;
A diaphragm layer provided on one surface of the pressure chamber forming substrate, a part of which constitutes a wall surface of the pressure chamber and the dummy pressure chamber;
An electromechanical transducer provided on the diaphragm layer corresponding to each pressure chamber;
Dummy electromechanical transducers provided on the diaphragm layer corresponding to each dummy pressure chamber;
An electrode pad electrically connected to the electromechanical transducer;
A dummy electrode pad electrically connected to the dummy electromechanical transducer;
A wiring formed so as to face at least a part of the dummy electrode pad located at least at the end of the dummy electrode pad;
A liquid ejection head comprising: The electromechanical transducer includes a lower electrode laminated on the diaphragm layer,
The liquid ejection head according to claim 1, wherein the wiring is electrically connected to the lower electrode.   The liquid ejection head according to claim 1, wherein the wiring is formed so as to face 50% or more of the circumference of the dummy electrode pad.   4. The liquid ejection head according to claim 1, wherein an interval between the wiring and the dummy electrode pad is in a range of 3 to 50 μm. 5.   5. The liquid discharge head according to claim 1, further comprising: a short-circuit wiring that conducts between the dummy electrode pad and the common electrode of the electromechanical conversion element.   The liquid discharge head according to claim 5, further comprising an insulating protective film that covers the short-circuit wiring. A discharge control means for controlling discharge of the liquid from the nozzle;
The electrode pad is electrically joined to the discharge control means,
The liquid discharge head according to claim 1, wherein the dummy electrode pad is not electrically joined to the discharge control unit. It is a manufacturing method of the liquid discharge head according to claim 5,
The method of manufacturing a liquid discharge head, wherein the step of producing the short-circuit wiring is a step after a polarization process for the electromechanical transducer and the dummy electromechanical transducer.   A liquid discharge unit comprising the liquid discharge head according to claim 1.   An apparatus for ejecting liquid, comprising the liquid ejection head according to claim 1 or the liquid ejection unit according to claim 9.

Images