JP6344634B2 - Droplet discharge head, droplet discharge apparatus, image forming apparatus, polarization processing method for electromechanical transducer, and method for manufacturing droplet discharge head - Google Patents

Description

  The present invention relates to a droplet discharge head that discharges a droplet, a droplet discharge device including the droplet discharge head, an image forming apparatus such as a printer, a facsimile, and a copying apparatus, a method for polarization processing an electromechanical transducer, and The present invention relates to a method for manufacturing a droplet discharge head.

  Conventionally, a nozzle that discharges liquid droplets of ink or the like, a liquid chamber (also referred to as a pressure chamber, a pressurization chamber, or a discharge chamber) that communicates with the nozzle and stores liquid, and a liquid in the liquid chamber There is known a droplet discharge head including a piezoelectric element as an electromechanical conversion element for applying pressure. In this droplet discharge head, when a predetermined voltage is applied to the piezoelectric element, it vibrates so as to deform the diaphragm that forms a part of the wall of the liquid chamber, and the liquid in the liquid chamber is deformed by the deformation of the diaphragm. Is pressurized, and droplets can be discharged from the nozzle.

  In addition, the piezoelectric crystal constituting the piezoelectric element has a random polarization direction as shown in FIG. 19A immediately after the piezoelectric element is manufactured. After that, by repeating the voltage application, the piezoelectric crystal becomes an aggregate of domains in which the directions of polarization are aligned as shown in FIG. The direction of polarization of the crystal of the piezoelectric body is preferably uniform from the beginning of use of the droplet discharge head in order to stabilize the polarization characteristics of the piezoelectric element and the properties of the droplet discharge head using the piezoelectric element. .

  Therefore, conventionally, there has been proposed a method of performing a polarization process for aligning the polarization direction of the piezoelectric element before the start of use of the droplet discharge head. For example, Patent Documents 1 and 2 disclose that a piezoelectric element that stabilizes the amount of displacement of the piezoelectric element with respect to the drive voltage by performing an aging process that applies an aging voltage to the piezoelectric element that is greater than the drive voltage during actual use. A manufacturing method is disclosed. Further, in Patent Document 3, a charge supply means for generating corona discharge is disposed so as to face the surface of the piezoelectric body through a gap, and the charge is supplied to the surface of the piezoelectric body by the corona discharge. A method is disclosed in which an electric field is generated in a piezoelectric body to perform polarization processing (polling processing).

  However, in the method of performing the aging process disclosed in Patent Documents 1 and 2 above, the aging voltage is applied by directly contacting the drive electrode constituting the piezoelectric element or the terminal electrode connected to the drive electrode. It is necessary to produce a probe card and a drive mechanism for driving the probe card, which may increase the cost.

  In the method disclosed in Patent Document 3, after the piezoelectric body is formed, the surface of the piezoelectric element is exposed before the subsequent post-process (interlayer film formation or lead wiring formation) is performed. It is necessary to perform polarization processing (polling processing). For this reason, a post-process (interlayer film formation or lead wiring formation) involving heat treatment at a high temperature (for example, a temperature exceeding 300 ° C.) is performed on the piezoelectric element that has been subjected to polarization processing (polling processing). Accordingly, the piezoelectric element is depolarized due to the influence of the thermal history or the like in the subsequent process, and the electromechanical conversion characteristic is the same as that before the polarization process (polling process) as shown in the PE hysteresis characteristic of FIG. There is a risk of returning to the state.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a droplet discharge head, a droplet discharge, and the like that can reduce variations in polarization characteristics of electromechanical transducer elements while reducing manufacturing costs. An apparatus, an image forming apparatus, an electromechanical conversion element polarization processing method, and a droplet discharge head manufacturing method are provided.

In order to achieve the above object, an invention according to claim 1 is directed to a nozzle for discharging droplets, a liquid chamber communicating with the nozzle, and an electric machine provided on a substrate so as to pressurize the liquid in the liquid chamber. A conversion element, a first terminal electrode connected to the first drive electrode on the substrate side of the electromechanical conversion element, and a second drive electrode opposite to the substrate side of the electromechanical conversion element A plurality of second terminal electrodes, the plurality of second terminal electrodes being arranged so as to be arranged at a predetermined interval, and adjacent to an end of a row of the plurality of second terminal electrodes. in position, the dummy terminal electrodes provided, the dummy terminal electrode and the bump electrode to the second terminal electrodes are formed, the terminal electrodes of the dummy, polarized dummy electromechanical transducer is connected to the plurality The electromechanical transducer elements are arranged so as to be lined up at a predetermined interval. Electromechanical transducer over the the column direction of the plurality of electro-mechanical conversion element is characterized in that are provided in different positions.

  According to the present invention, it is possible to reduce the variation in the polarization characteristics of the electromechanical transducer while reducing the manufacturing cost.

FIG. 3 is a schematic configuration diagram illustrating a configuration example of a droplet discharge unit that is a basic component of the droplet discharge head according to the embodiment of the present invention. Sectional drawing which shows an example of the layer structure of the diaphragm and piezoelectric element on a board | substrate. The more detailed sectional view of the example of composition around a piezoelectric element. The more detailed top view of the structural example of a periphery of a piezoelectric element. FIG. 3 is a plan view illustrating an example of an actuator substrate in which a plurality of droplet discharge portions of a droplet discharge head according to Embodiments 1 and 2 are formed in two rows facing each other. (B) is sectional drawing which looked at the a-a 'surface of Fig.5 (a) from the arrow direction. Explanatory drawing which shows typically the mode of the charge injection to the pad electrode for common electrodes by the discharge process, and the pad electrode for individual electrodes. (A) And (b) is an electrode arrangement | positioning figure and an equivalent circuit diagram which respectively show the principle of the polarization of the piezoelectric element by charge injection. (A) And (b) is a graph which shows the example of a measurement of the PE hysteresis loop characteristic of the piezoelectric element before polarization processing and after polarization processing, respectively. The graph which shows the θ-2theta measurement data of the X-ray measured about SRO which comprises an oxide electrode film. FIG. 9 is a plan view illustrating an example of an actuator substrate in a droplet discharge head according to a third embodiment. FIG. 9 is an enlarged plan view illustrating an example of an actuator substrate in a droplet discharge head according to a fourth embodiment. FIG. 9 is an enlarged plan view showing a configuration example around a piezoelectric element of an actuator substrate in a droplet discharge head according to Examples 5-7. FIG. 10 is an enlarged plan view illustrating a configuration example around a piezoelectric element of an actuator substrate in a droplet discharge head according to an eighth embodiment. Explanatory drawing which shows the mode of the destruction which arose in the edge part of the separate electrode of the actuator board | substrate in the droplet discharge head which concerns on a comparative example. The graph which shows the example of the typical PE hysteresis loop characteristic of a piezoelectric element. FIG. 3 is a schematic configuration diagram illustrating a configuration example of a droplet discharge head including a plurality of droplet discharge units. 1 is a side view illustrating an example of an image forming apparatus including a droplet discharge head according to an embodiment. FIG. 2 is a partial plan view of the image forming apparatus. (A) is explanatory drawing which shows the mode of the domain of the piezoelectric material before polarization processing. (B) is explanatory drawing which shows the mode of the domain of the piezoelectric material after a polarization process. The graph which shows the PE hysteresis loop characteristic of a piezoelectric element before a polarization process, after a polarization process, and after 300 degreeC thermal history, respectively.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating a configuration example of a droplet discharge unit 10 that is a basic component of a droplet discharge head according to an embodiment of the present invention.
In FIG. 1, a droplet discharge unit 10 includes a nozzle substrate 12 having a nozzle 11 for discharging a droplet of a liquid such as ink, and a liquid chamber substrate 14 formed with a liquid chamber 13 communicating with the nozzle 11 and containing a liquid. And. Further, on a liquid chamber substrate (hereinafter simply referred to as “substrate”) 14, a vibration plate 15 and a piezoelectric element as an electromechanical transducer for pressurizing the liquid in the liquid chamber 13 via the vibration plate 15. 16 is provided. The piezoelectric element 16 includes a common electrode 161 as a lower electrode as a first drive electrode on the substrate 14 side, a piezoelectric film 162 made of PZT or the like as an electromechanical conversion film, and the opposite side of the piezoelectric film 162 from the substrate 14 side. An individual electrode 163 that is an upper electrode as a second driving electrode on the side is laminated. The common electrode 161 is connected to a pad electrode for a common electrode as a first terminal electrode for external connection described later. The individual electrode 163 is connected to a pad electrode for an individual electrode as a second terminal electrode for external connection described later. In the droplet discharge unit 10 of FIG. 1, a driving voltage having a predetermined frequency and amplitude is applied between the common electrode 161 and the individual electrode 163 of the piezoelectric element 16 via the first pad electrode and the second pad electrode. The piezoelectric element 16 to which the drive voltage is applied vibrates so as to deform a vibration plate (not shown) between the substrate 14 and the piezoelectric element 16, and the liquid in the liquid chamber 13 is pressurized by the deformation of the vibration plate. Thus, the droplets can be ejected from the nozzle 11.

FIG. 2 is a cross-sectional view showing an example of the layer structure of the diaphragm and the piezoelectric element on the substrate. 3 and 4 are a more detailed cross-sectional view and plan view of the periphery of the piezoelectric element 16, respectively. In FIG. 4, the first insulating protective film 18 and the second insulating protective film 23 are not shown.
A diaphragm 15 formed by film formation is disposed between the common electrode 161 that is the lower electrode of the piezoelectric element 16 and the substrate 14. After the piezoelectric element 16 is formed so as to be in contact with the vibration plate 15, the first insulating protective film 18 is formed. Furthermore, a first wiring 20 that connects the common electrode 161 and the pad electrode 19 and a second wiring 22 that connects the individual electrode 163 and the pad electrode 21 are formed. The first insulating protective film 18 electrically insulates between the common electrode 161 and the second wiring 22. Further, between the common electrode 161 and the first wiring 20 and between the individual electrode 163 and the second wiring 22 through a contact hole 18 a which is an opening formed in the first insulating protective film 18. It is connected.

  After the first wiring 20 and the second wiring 22 are formed, a second insulating protective film 23 is formed so as to cover the whole. The pad electrodes 19 and 21 are formed in a contact hole 23a as an opening in which the second insulating protective film 23 is formed. For the entire composite laminated substrate (hereinafter referred to as “actuator substrate”) including the liquid chamber substrate 14, the substrate 14, the piezoelectric element 16, and various electrodes after the second insulating protective film 23 is formed. A subframe, which will be described later, is bonded to the element 16 as a structure provided so as to cover the piezoelectric element 16 in a non-contact state via a gap.

  FIG. 5A is a plan view showing an example of the actuator substrate 25 in which the plurality of droplet discharge sections 10 having the above-described configuration are formed in two rows facing each other, and FIG. 5B is a plan view of FIG. It is sectional drawing which looked at the aa 'surface of () from the arrow direction. In FIG. 5, the first insulating protective film 18 and the second insulating protective film 23 are not shown.

  In FIG. 5, the subframe 26 is bonded to the actuator substrate 25. The sub-frame 26 is a structure having at least an insulating surface provided so as to cover the piezoelectric element 16 in a non-contact state with respect to the piezoelectric element 16 of the actuator substrate 25 through a gap. A recess 26a is formed in the portion to be performed. The sub-frame 26 has an opening 26 b that forms a part of a common liquid supply path that supplies liquid to the plurality of liquid chambers 13. Further, the sub-frame 26 has an opening 26c in which a piezoelectric element driving IC as a driving electric circuit element for applying a pulse driving voltage having a predetermined amplitude and frequency to the plurality of piezoelectric elements 16 is disposed. Yes. The pad electrode 21 for the individual electrode is exposed in the opening 26. The piezoelectric element driving IC is electrically connected to the pad electrode 21 for individual electrodes via the bump electrode 27. The subframe 26 has an opening 26d through which the pad electrode 19 for the common electrode is exposed.

Next, the polarization process of the piezoelectric element 16 performed after joining the sub-frame 26 to the actuator substrate 25 will be described.
In the present embodiment, the corona discharge method or the glow discharge method is performed on the subframe 26 having the openings 26c and 26d through which the pad electrode 19 for the common electrode and the pad electrode 21 for the individual electrode are exposed. ing. By this discharge treatment, charges having different amounts of charge having a predetermined polarity are applied to the common electrode 161 and the individual electrode 163 of the piezoelectric element 16 through the pad electrode 19 for the common electrode and the pad electrode 21 for the individual electrode. Yes. By this charge application, polarization processing can be performed on the piezoelectric film 162 sandwiched between the common electrode 161 and the individual electrode 163 of the piezoelectric element 16.

FIG. 6 is an explanatory diagram schematically showing the state of charge injection into the common electrode pad electrode 19 and the individual electrode pad electrode 21 by the discharge treatment. FIGS. 7A and 7B are an electrode arrangement diagram and an equivalent circuit diagram showing the principle of polarization of the piezoelectric element 16 by charge injection, respectively.
In FIG. 6, for example, when corona discharge is performed using the corona wire electrode 31, molecules in the atmosphere are ionized to generate cations and anions. Among the generated ions, positive ions flow into the common electrode 161 and the individual electrode 163 of the piezoelectric element 16 via the pad electrodes 19 and 21, and are accumulated in these electrodes.

  Here, as shown in FIG. 7A, it is assumed that the number of pad electrodes 21 for individual electrodes is A, and the number of pad electrodes 19 for common electrodes is B. Further, it is assumed that the exposed areas of the pad electrodes 19 and 21 are the same. Under this condition, if charge Q is injected into each pad electrode, the accumulated amount of charge for each piezoelectric element indicated by the capacitor in FIG. That is, charges Q are generated on the individual electrode (upper electrode) 163 side of the piezoelectric element 16, whereas charges of Q × (B / A) are generated on the common electrode (lower electrode) 161 side. It is considered that an internal potential difference is generated between the electrodes due to the difference in the amount of charge generated in each of the individual electrode 163 and the common electrode 161, and the polarization treatment of the piezoelectric film 162 is performed.

  In consideration of the number (B) and area (b) of pad electrodes 19 for common electrodes, and the number (A) and area (a) of pad electrodes 21 for individual electrodes, (A × a) The value of / (B × b) is preferably in the following range. That is, the value of (A × a) / (B × b) is preferably 0.1 or more, more preferably 1 or more. When this value is not reached, the difference in the amount of charge generated in each of the individual electrode 163 and the common electrode 161 is reduced, and the internal potential difference between the electrodes is eliminated, so that the polarization process is not performed.

Here, the state of the polarization treatment of the piezoelectric film 162 can be determined from the PE hysteresis loop characteristics of the piezoelectric element.
FIGS. 8A and 8B are graphs showing measurement examples of PE hysteresis loop characteristics before and after polarization processing, respectively. As shown in FIG. 8, the hysteresis loop is measured with an electric field strength of ± 150 [kV / cm]. The first polarization at 0 [kV / cm] is Pini, and after applying a voltage of +150 [kV / cm], the polarization at 0 [kV / cm] when returning to 0 [kV / cm] is Pr. Then, the value of Pr−Pini is defined as a polarization amount difference. Whether the polarization state is good or bad can be determined from this polarization amount difference (Pr-Pini). For example, the polarization amount difference (Pr−Pini) is preferably 10 [μC / cm ² ] or less, and as shown in FIG. 8B, it is 5 [μC / cm ² ] or less. Further preferred. On the other hand, when the value of the polarization amount difference (Pr−Pini) is larger than 10 [μC / cm ² ] as shown in FIG. 8A, deformation deterioration after continuous driving as a piezoelectric actuator comprising a piezoelectric element ( With respect to (displacement deterioration), sufficient characteristics cannot be obtained.

Further, in the liquid droplet ejection head of this embodiment, a plurality of individual electrode pad electrodes 21 are arranged at predetermined intervals as shown in FIG. 5 described above. When the polarization treatment by the corona discharge or the glow discharge is performed on the plurality of individual electrode pad electrodes 21 arranged in a row in this manner, the individual electrode pad electrodes 21 located at both ends of the row are obtained. The charge injection tends to increase. for that reason,
There is a possibility that the piezoelectric elements 16 connected to the pad electrodes 21 for individual electrodes located at both ends of the row cause electric charge concentration, and dielectric breakdown may occur in the piezoelectric elements 16 as shown in FIG.

  Therefore, in the present embodiment, the dummy pad electrode 35 as a dummy terminal electrode is provided at a position adjacent to the end of the row of the plurality of individual electrode pad electrodes 21. This dummy pad electrode 35 can avoid excessive charge injection into the individual electrode pad electrodes 21 located at both ends of the row. Therefore, excessive charge concentration on the piezoelectric element 16 connected to the pad electrode 21 for the individual electrode does not occur, and dielectric breakdown of the piezoelectric element 16 can be avoided, so that the piezoelectric element 16 can be made more uniform. Polarization processing becomes possible. In particular, as shown in FIG. 5, if a dummy piezoelectric element 40, which is a charge storage element, is connected to the dummy pad electrode 35, or if the dummy pad electrode 35 is connected to the ground (GND), the excess to the piezoelectric element 16 is caused. Charge concentration can be prevented more effectively.

  Next, the materials and methods of the respective parts and members, which are the constituent elements of the droplet application head of the present embodiment, will be described more specifically.

〔substrate〕
As the substrate 14, it is preferable to use a silicon single crystal substrate, and it is preferable to have a thickness in the range of 100 [μm] to 600 [μm]. There are three types of plane orientations: (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry. In this configuration example, A single crystal substrate having a (100) plane orientation was mainly used. Further, when the liquid chamber (pressure chamber) 13 as shown in FIG. 1 is manufactured, the silicon single crystal substrate is processed using etching. As an etching method in this case, it is common to use anisotropic etching. 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. Therefore, while a structure having an inclination of about 54 ° can be produced in the plane orientation (100), a deep groove can be removed in the plane orientation (110), so that the arrangement density is increased while maintaining rigidity. I know you can. As this configuration example, it is possible to use a single crystal substrate having a (110) plane orientation. However, in this case, SiO ₂ which is a mask material is also etched, so it is preferable to use this point in consideration.

(Diaphragm)
As shown in FIG. 1, upon receiving the force generated by the piezoelectric element 16 as an electromechanical transducer, the underlying diaphragm 15 is deformed, and liquid droplets such as ink in the liquid chamber (pressure chamber) 13 are discharged. Discharge. Therefore, it is preferable that the diaphragm 15 has a predetermined strength. Examples of the material include those made of Si, SiO ₂ , Si ₃ N ₄ or the like by, for example, a CVD method. Furthermore, it is preferable to select a material close to the linear expansion coefficient of the common electrode (lower electrode) 161 and the piezoelectric film 162 as shown in FIG. In particular, PZT is often used as a material for piezoelectric films. Therefore, the material of the diaphragm 15 is in the range of 5 × 10 ⁻⁶ (1 / K) to 10 × 10 ⁻⁶ (1 / K), which is close to the linear expansion coefficient 8 × 10 ⁻⁶ (1 / K) of PZT. A material having a linear expansion coefficient is preferably 7 × 10 ⁻⁶ (1 / K) or more and 9 × 10 ⁻⁶ (1 / K) or less. Specific examples of the material 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 materials can be produced by a spin coater using, for example, a sputtering method or a sol-gel method. The film thickness is preferably in the range of 0.1 [μm] to 10 [μm], and more preferably in the range of 0.5 [μm] to 3 [μm]. If it is smaller than this range, it becomes difficult to process the liquid chamber (pressure chamber) 13 as shown in FIG. On the other hand, if it is larger than the above range, the diaphragm 15 is not easily deformed, and ejection of droplets such as ink droplets becomes unstable.

[Common electrode (first drive electrode)]
The common electrode (first drive electrode) 161 is preferably made of metal or metal and oxide. Here, both materials are devised so as to suppress peeling and the like by inserting an adhesion layer between the diaphragm 15 and the metal film constituting the common electrode 161. Details of the metal electrode film and the oxide electrode film including the adhesion layer are described below.

[Adhesion layer]
The adhesion layer is formed as follows, for example. After Ti is formed by sputtering, the formed titanium film is thermally oxidized using an RTA (Rapid Thermal Annealing) apparatus to form a titanium oxide film. The conditions for thermal oxidation are, for example, a temperature in the range of 650 [° C.] to 800 [° C.], a treatment time in the range of 1 [min] to 30 [min], and an O ₂ atmosphere. To form the titanium oxide film, reactive sputtering may be used, but thermal oxidation of the titanium film at a high temperature is desirable. The production by reactive sputtering requires a special sputtering chamber configuration because the silicon substrate needs to be heated at a high temperature. Furthermore, the crystallinity of the titanium O ₂ film is better in the oxidation by the RTA apparatus than in the oxidation by a general furnace. This is because, according to oxidation in a normal heating furnace, a titanium film that is easily oxidized forms several crystal structures at a low temperature, and thus it is necessary to break it once. Therefore, oxidation by RTA having a high temperature rising rate is advantageous in order to form better crystals. Moreover, as materials other than Ti, materials such as Ta, Ir, and Ru can be used. The thickness of the adhesion layer is preferably in the range of 10 [nm] to 50 [nm], and more preferably in the range of 15 [nm] to 30 [nm]. If it is below this range, there is concern about the adhesion, and if it exceeds this range, the quality of the crystal of the electrode film produced on the adhesion layer will be affected.

[Metal electrode film]
Conventionally, platinum having high heat resistance and low reactivity has been used as the metal material of the metal electrode film, but it may not be said that it has sufficient barrier properties against lead. -Platinum group elements, such as rhodium, and these alloy films are also mentioned. Further, when platinum is used, it is preferable that the above-mentioned adhesion layer is laminated first because adhesion to the base (particularly SiO ₂ ) is poor. As a manufacturing method, vacuum film formation such as sputtering or vacuum deposition is generally used. The film thickness is preferably in the range of 80 [nm] to 200 [nm], and more preferably in the range of 100 [nm] to 150 [nm]. When the thickness is smaller than this range, a sufficient current cannot be supplied as the common electrode 161, and a problem occurs when ejecting droplets. Further, when the thickness is larger than this range, the cost increases when an expensive material of a platinum group element is used. In the case of using platinum as a material, the surface roughness increases when the film thickness is increased, which affects the surface roughness and crystal orientation of the oxide electrode film and PZT produced thereon. This causes a problem that sufficient displacement for ink ejection cannot be obtained.

[Oxide electrode film]
As a material for the oxide electrode film, SrRuO ₃ (hereinafter, abbreviated as “SRO” as appropriate) is preferably used. In addition to SrRuO ₃ , Srx (A) (1-x) Ruy (1-y), A = Ba, Ca, B = Co, Ni, x, y = 0 to 0.5 Also mentioned. The oxide electrode film can be produced by a film formation method such as sputtering. The film quality of the SrRuO ₃ thin film varies depending on the sputtering conditions. Therefore, in order to place the SrRuO ₃ film in the (111) orientation in the same way as the Pt (111) of the first drive electrode with particular emphasis on the crystal orientation, the film forming temperature is 500 [° C.] or higher. It is preferable to form a film by heating the substrate. For example, with respect to the SRO film formation conditions described in Patent Document 4, thermal acidification is performed at room temperature film formation and then RTA treatment at a crystallization temperature (650 ° C.). In this case, the SRO film is sufficiently crystallized and a sufficient value is obtained as the specific resistance as an electrode. However, as the crystal orientation of the film, (110) is easily preferentially oriented, and the film is formed thereon. The (110) orientation of the deposited PZT is also facilitated.

  As for the crystallinity of SRO produced on Pt (111), the lattice constants of Pt and SRO are close to each other. Therefore, in the normal X-ray θ-2θ measurement, the 2θ positions of SRO (111) and Pt (111) overlap. It is difficult to distinguish. With respect to Pt, diffraction lines cancel each other at a position where 2θ inclined by Psi = 35 ° is about 32 ° due to the disappearance rule, and no diffraction intensity is observed. Therefore, it is possible to confirm whether the SRO is preferentially oriented to (111) by inclining the Psi direction by about 35 ° and judging from the peak intensity where 2θ is about 32 °.

  FIG. 9 is a graph showing X-ray θ-2θ measurement data measured by shaking Psi while fixing the crystallinity of SRO constituting the oxide electrode film at 2θ = 32 °. When Psi = 0 °, almost no diffraction intensity is observed with SRO (110), but near Psi = 35 °, diffraction intensity is observed. I was able to confirm. In addition, regarding the SRO produced by the room temperature film formation + RTA process described above, the diffraction intensity of SRO (110) is observed when Psi = 0 °.

  In addition, when the amount of displacement after being driven was estimated to be deteriorated compared to the initial displacement when continuously operating as a piezoelectric actuator, the orientation of PZT has a great influence. (110) Insufficient displacement suppression is insufficient. Further, when the surface roughness of the SRO film is observed, it affects the film forming temperature, and the surface roughness is very small from room temperature to 300 ° C. and becomes 2 [nm] or less. As for the roughness, the surface roughness (average roughness) measured by AFM is used as an index. Although the surface roughness is very flat, the crystallinity is not sufficient, and sufficient characteristics cannot be obtained with respect to initial displacement as a piezoelectric actuator of PZT formed after that and displacement deterioration after continuous driving. . The surface roughness is preferably in the range of 4 [nm] to 15 [nm], and more preferably in the range of 6 [nm] to 10 [nm]. If this range is exceeded, the dielectric breakdown voltage of the PZT deposited thereafter is very poor and leaks easily. Therefore, in order to obtain crystallinity and surface roughness as described above, the film formation temperature is 500 [° C.] to 700 [° C.], preferably 520 [° C.] to 600 [° C.]. Has been implemented.

Regarding the composition ratio of Sr and Ru after film formation, Sr / Ru is preferably 0.82 or more and 1.22 or less. If it is out of this range, the specific resistance increases, and sufficient conductivity as an electrode cannot be obtained. Furthermore, the thickness of the SRO film is preferably in the range of 40 [nm] to 150 [nm], and more preferably in the range of 50 [nm] to 80 [nm]. If the thickness is smaller than this range, sufficient characteristics cannot be obtained for initial displacement and displacement deterioration after continuous driving, and a function as a stop etching layer for suppressing over-etching of the piezoelectric film (PZT film) can also be obtained. It becomes difficult. If the thickness is exceeded, the dielectric strength of the piezoelectric film (PZT film) formed thereafter is very poor and leaks easily. Further, the specific resistance is preferably 5 × 10 ⁻³ [Ω · cm] or less, and more preferably 1 × 10 ⁻³ [Ω · cm] or less. If it is larger than this range, sufficient contact resistance cannot be obtained at the interface with the wiring as the common electrode 161, and sufficient current cannot be supplied as the common electrode 161, causing problems when discharging droplets. To do.

[Piezoelectric film (electromechanical conversion film)]
PZT was mainly used as the material for the piezoelectric film 162. The PZT a solid solution of lead zirconate (PbTiO3) titanate (PbTiO _3), characteristics differ by the ratio. In general, the composition exhibiting excellent piezoelectric characteristics has a ratio of PbZrO ₃ and PbTiO ₃ of 53:47. When expressed by a chemical formula, Pb (Zr0.53, Ti0.47) O ₃ , general PZT (53/47) It is indicated. Examples of composite oxides other than PZT include barium titanate. In this case, it is also possible to prepare a barium titanate precursor solution by dissolving barium alkoxide and a titanium alkoxide compound in a common solvent. is there. These materials are described by the general formula ABO ₃ , and A = Pb, Ba, Sr, B = Ti, Zr, Sn, Ni, Zn, Mg, and a composite oxide mainly composed of Nb. As specific description (Pb1-x, Ba) ( Zr, Ti) O3, (Pb1-x, Sr) (Zr, Ti) O 3, which was partially substituted with Ba and Sr and Pb in the A site Is the case. 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 a method for manufacturing the piezoelectric film 162, it can be manufactured by a spin coater using a sputtering method or a sol-gel method. In that case, since patterning is required, a desired pattern is obtained by photolithography etching or the like. When PZT is produced by a sol-gel method, a PZT precursor solution can be produced by using lead acetate, zirconium alkoxide, and titanium alkoxide compounds as starting materials and dissolving them in methoxyethanol as a common solvent to obtain a uniform solution. Since the metal alkoxide compound is easily hydrolyzed by moisture in the atmosphere, an appropriate amount of a stabilizer such as acetylacetone, acetic acid or diethanolamine may be added to the precursor solution as a stabilizer.

  When the piezoelectric film (PZT film) 162 is obtained on the entire surface of the substrate 14, 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 precursor concentration so that a film thickness of 100 nm or less can be obtained in one step in order to obtain a crack-free film. Become.

The film thickness of the piezoelectric film 162 is preferably in the range of 0.5 [μm] to 5 [μm], and more preferably in the range of 1 [μm] to 2 [μm]. If it is smaller than this range, it will not be possible to generate sufficient deformation (displacement), and if it is larger than this range, many layers will be laminated, resulting in an increase in the number of steps and a longer process time.
The relative dielectric constant of the piezoelectric film 162 is preferably in the range of 600 to 2000, and more preferably in the range of 1200 to 1600. At this time, if it is smaller than this range, sufficient deformation (displacement) characteristics cannot be obtained, or if it exceeds this range, polarization processing is not performed sufficiently, and sufficient characteristics cannot be obtained for displacement deterioration after continuous driving. Such a problem occurs.

[Individual electrode (second drive electrode)]
The individual electrode (second drive electrode) 163 is preferably made of a metal or an oxide and a metal. Details of the oxide electrode film and the metal electrode film are described below.

[Oxide electrode film]
Examples of the material for the oxide electrode film include the same materials as those described for the oxide electrode film used in the common electrode (first drive electrode) 161 described above. The thickness of the oxide electrode film (SRO film) is preferably in the range of 20 [nm] to 80 [nm], and more preferably in the range of 40 [nm] to 60 [nm]. If the thickness is less than this range, sufficient characteristics cannot be obtained for the deterioration characteristics of initial deformation (displacement) and deformation (displacement). On the other hand, if it exceeds this range, the dielectric breakdown voltage of the piezoelectric film (PZT film) formed thereafter is very poor and leaks easily.

[Metal electrode film]
Examples of the material of the metal electrode film include the same materials as those described for the metal electrode film used in the common electrode (first drive electrode) 161 described above. The film thickness is described as a metal electrode film, and the film thickness is preferably in the range of 30 [nm] to 200 [nm], and more preferably in the range of 50 [nm] to 120 [nm]. When the thickness is smaller than this range, a sufficient current cannot be supplied as the individual electrode 163, and a problem occurs when a droplet is ejected. On the other hand, when the thickness is larger than the above range, the cost increases when an expensive material of a platinum group element is used. In addition, when platinum is used as the material, the surface roughness increases when the film thickness is increased, and process defects such as film peeling are likely to occur when wiring is formed through an insulating protective film. .

[First insulating protective film]
Since it is necessary to select a material that prevents the moisture in the atmosphere from permeating while preventing damage to the piezoelectric element due to the film formation / etching process, the material of the first insulating protective film 18 needs to be a dense inorganic material. There is. Further, when an organic material is used as the first insulating protective film 18, it is not suitable because it is necessary to increase the film thickness in order to obtain sufficient protection performance. If the first insulating protective film 18 is a thick film, the vibration of the diaphragm 15 is remarkably hindered, resulting in a droplet discharge head with low discharge performance. In order to obtain high protection performance with a thin film, it is preferable to use an oxide, nitride, or carbonized film. However, the electrode material, the piezoelectric material, and the diaphragm material serving as the base of the first insulating protective film 18 have adhesiveness. It is necessary to select a high material. In addition, it is necessary to select a film forming method that does not damage the piezoelectric element 16 as a method for forming the first insulating protective film 18. 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 a preferable film formation method for the first insulating protective film 18 include a vapor deposition method and an ALD method, but an ALD method with a wide range of materials that can be used is preferable. As a preferable material, 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 film thickness of the first insulating protective film 18 needs to be a thin film enough to ensure the protection performance of the piezoelectric element 16 and at the same time as thin as possible so as not to inhibit the deformation (displacement) of the diaphragm 15. There is a need. The film thickness of the first insulating protective film 18 is preferably in the range of 20 [nm] to 100 [nm]. When the thickness is greater than 100 [nm], the deformation (displacement) amount of the vibration plate 15 is reduced, so that a droplet discharge head with low discharge efficiency is obtained. On the other hand, when the thickness is smaller than 20 [nm], the function of the piezoelectric element 16 as a protective layer is insufficient, so that the performance of the piezoelectric element 16 is deteriorated as described above.

Further, a configuration in which the first insulating protective film 18 has two layers is also conceivable. In this case, in order to increase the thickness of the second insulating protective film, the second insulating protective film is opened in the vicinity of the individual electrode (second driving electrode) 163 so as not to significantly inhibit the vibration of the diaphragm 15. Can also be mentioned. In this case, as the second insulating protective film, any oxide, nitride, carbide or a composite compound thereof can be used, and SiO ₂ generally used in semiconductor devices can also be used. . Arbitrary methods can be used for forming the two-layer first insulating protective film 18, and examples thereof include a CVD method and a sputtering method. 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 a voltage applied between the common electrode (lower electrode) 161 and the wiring 22 of the individual electrode. That is, it is necessary to set the electric field strength applied to the first insulating protective film 18 within a range not causing dielectric breakdown. Furthermore, in consideration of the surface property of the base of the first insulating protective film 18 and pinholes, the film thickness of the first insulating protective film 18 needs to be 200 [nm] or more, more preferably 500 [nm] or more. It is.

[Wiring, pad electrode]
The material of the wirings 20 and 22 and the pad electrodes 19 and 21 is preferably a metal electrode material made of any one of an Ag alloy, Cu, Al, Au, Pt, and Ir. As a method for manufacturing these electrodes, 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 in the range of 0.1 [μm] to 20 [μm], and more preferably in the range of 0.2 [μm] to 10 [μm]. If it is smaller than this range, the resistance becomes large, and a sufficient current cannot flow through the electrodes, making the head ejection unstable. On the other hand, if it is larger than this range, the process time becomes longer. The contact resistance at the contact hole portion (for example, 10 [μm] × 10 [μm]) connected to the common electrode 161 and the individual electrode 163 is 10 [Ω] or less with respect to the common electrode 161, and the individual electrode 163. Is preferably 1 [Ω] or less. More preferably, it is 5 [Ω] or less for the common electrode 161 and 0.5 [Ω] or less for the individual electrode 163. If it exceeds this range, it will not be possible to supply a sufficient current, and problems will occur when discharging droplets.

[Second insulating protective film]
The function as the second insulating protective film 23 is a passivation layer having a function as a protective layer for the first wiring 20 for the common electrode and the second wiring 22 for the individual electrode. As shown in FIGS. 3 and 4 described above, the individual electrode 163 and the common electrode 161 are covered except for the lead-out portion (opening 23a) of the individual electrode 163 and the lead-out portion of the common electrode 161 (not shown). Thereby, an inexpensive Al or an alloy material containing Al as a main component can be used as the electrode material. As a result, a low-cost and highly reliable droplet discharge head (inkjet head) can be obtained. As a material of the second insulating protective film 23, 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 for patterning because it needs to be 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. When the film thickness is thin, a sufficient passivation function cannot be exhibited, so that disconnection due to corrosion of the wiring material occurs, and the reliability of the ink jet is lowered.

Further, a structure having openings on the piezoelectric element 16 and the surrounding diaphragm 15 is preferable. This is the same reason that the region corresponding to the individual liquid chamber of the first insulating protective film 18 is thinned. As a result, a highly efficient and highly reliable droplet discharge head (inkjet head) can be obtained. Since the piezoelectric element 16 is protected by the insulating protective films 18 and 23, the opening of the second insulating protective film 23 can be formed by photolithography and dry etching. The area of the pad electrodes 19 and 21 is preferably 50 × 50 [μm ² ] or more, and more preferably 100 × 300 [μm ² ] or more. When the value is less than this value, sufficient polarization processing cannot be performed, and there is a problem that sufficient characteristics cannot be obtained with respect to deformation (displacement) deterioration after continuous driving.

Next, a more specific example of the polarization process using discharge in the manufacturing method of the droplet discharge head of the present embodiment will be described.
<Examples 1 and 2>
First, Embodiments 1 and 2 will be described with reference to FIG.
In Examples 1 and 2, a thermal oxide film (film thickness: 1 [μm]) was formed on a 6-inch silicon wafer as the base substrate 14, and a common electrode (first drive electrode) 161 was formed. First, after forming a titanium film (film thickness 30 [nm]) as an adhesion film of the common electrode 161 with a sputtering apparatus, thermal oxidation was performed at 750 [° C.] using RTA. Subsequently, a platinum film (film thickness 100 [nm]) as a metal film and an SrRuO film (film thickness 60 [nm]) as an oxide film were formed by sputtering. Film formation was performed at a substrate heating temperature of 550 [° C.] during the sputtering film formation.

  Next, a piezoelectric film (element electromechanical conversion film) 163 was formed. First, a solution adjusted to Pb: Zr: Ti = 114: 53: 47 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. 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 of this PZT precursor solution was 0.5 mol / liter. Using this PZT precursor solution, a film was formed by spin coating, and after the film formation, drying at 120 [° C.] and thermal decomposition at 500 [° C.] were performed. After thermal decomposition treatment of the third layer, crystallization heat treatment (temperature 750 [° C.]) was performed by RTA (rapid heat treatment). 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 thickness of about 2 [μm].

  Next, an individual electrode (second drive electrode) 163 was formed. First, an SrRuO film (film thickness 40 [nm]) was formed as an oxide film of the individual electrode 163, and a Pt 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 a spin coat method, a resist pattern is formed by a normal photolithography method, and then the above-described FIG. 4 is used by using an ICP etching apparatus (manufactured by Samco). A pattern as shown was prepared.

Next, as the first insulating protective film 18, an Al ₂ O ₃ film having a thickness of 50 [nm] was formed using an ALD method. At this time, TMA (Sigma Aldrich) was used as the Al raw material, and O ₃ generated by an ozone generator was used as the O raw material, and the film formation was advanced by alternately laminating Al and O. Thereafter, as shown in FIGS. 3 and 4, a contact hole portion 18a was formed by etching. Thereafter, Al is sputtered as wiring and pad electrodes, patterned by etching, and Si ₃ N ₄ is deposited as a second insulating protective film 23 by plasma CVD to a thickness of 500 [nm]. Element 16) was produced. At this time, 25 areas of 30 [mm] × 10 [mm] in a 6-inch wafer were arranged. Each of the 25 areas has 300 pad electrodes 21 for individual electrodes, and each row has a two-row configuration in which 150 pad electrodes 21 are two rows.

  For the actuator substrate 25 including the piezoelectric element (electromechanical conversion element) 16 manufactured as described above, an opening 26b for forming a part of the common liquid chamber, an opening 26c for disposing the piezoelectric element driving IC, and the like. The sub-frame 26 provided with was bonded by bonding. The subframe 26 was manufactured using a silicon wafer, and a thermal oxide film was formed on the surface of the subframe 26.

  In the first and second embodiments, the piezoelectric element driving IC is mounted on the actuator substrate 25. Since the mounting space can be reduced by mounting the piezoelectric element driving IC directly on the actuator substrate 25, the number of actuator substrates that can be removed from the silicon wafer can be increased, and the cost can be reduced.

  In the first and second embodiments, the dummy pad electrode 35 is positioned adjacent to the end of the row of the pad electrodes 21 for the individual electrodes on the actuator substrate 25 connected to the terminal of the piezoelectric element driving IC. Is formed. The dummy pad electrode 35 is formed on the same column as the pad electrode 21 for the individual electrode constituting the droplet discharge portion (drive channel). That is, the dummy pad electrodes 35 are adjacent to the end portions of the individual electrode pad electrodes 21 at the same interval as the individual electrode pad electrodes 21 along the plurality of individual electrode pad electrode 21 columns. It is provided in the position to do. The dummy pad electrode 35 has the same area as the pad electrode 21 for individual electrodes.

  Further, in the first and second embodiments, a dummy piezoelectric element 40 as a dummy electromechanical conversion element that is a charge storage element is connected to the dummy pad electrode 35 via a wiring. The dummy piezoelectric elements 40 are formed on the same column as the piezoelectric elements 16 constituting the droplet discharge portion (drive channel). That is, the dummy piezoelectric elements 40 are provided at positions adjacent to the end portions of the rows of the piezoelectric elements 16 at the same intervals as the intervals of the piezoelectric elements 16 along the rows of the plurality of piezoelectric elements 16. The dummy piezoelectric element 40 has the same area as the piezoelectric element 16.

  In the first and second embodiments, the bump electrode 27 is formed on the dummy pad electrode 35 in the same manner as the pad electrode 21 for the individual electrode. The material of the bump electrode 27 is preferably gold. Further, the cost can be further reduced by using a gold stud bump. The effect of the gold stud bump is that the area where the bump electrode is formed is smaller than the area of the actuator substrate 25, and the gold plating bump by the plating method increases the cost of process and material loss.

  Forming bump electrodes on the individual electrode pad electrode 21 and the dummy pad electrode 35 before the polarization treatment by corona discharge or the like has the following effects. That is, the area of the pad electrode 21 for an individual electrode becomes very small as the piezoelectric element driving IC is mounted with high density. On the other hand, when a polarization process such as corona discharge is performed, it is necessary to inject a predetermined charge into the pad electrode 21 for the individual electrode and the pad electrode 19 for the common electrode. Here, by forming the bump electrode 27 on the pad electrode 21 for the individual electrode, the surface area of the pad electrode 21 can be increased, so that a stable polarization process can be performed.

  The first embodiment is an embodiment in which the bump electrode 27 is not formed on the pad electrode 21 for the individual electrode, and the second embodiment is an embodiment in which the bump electrode 27 is formed on the pad electrode 21 for the individual electrode. is there.

In order to confirm the effect of the configuration including the dummy pad electrode 35 and the dummy piezoelectric element 40 of the first and second embodiments, the polarization processing experiment was performed on the actuator substrate of the first and second embodiments and the actuator substrate of the comparative example shown in Table 1. Went. The structure of the charging apparatus using corona discharge used in this experiment employs a scorotron system, a voltage of 8 [kV] is applied to a corona wire of φ 50 [μm], and 2.5 to the grid electrode. A voltage of [kV] was applied and the treatment was performed for 30 seconds. The evaluation items are the following two items (1) and (2).
(1) Presence or absence of dielectric breakdown between the upper and lower electrodes of the piezoelectric element 16 due to the polarization treatment of corona discharge (2) Polarization amount difference (Pr-Pini)

  In Examples 1 and 2 in Table 1, a dummy pad electrode 35 is formed on the same row of pad electrodes 21 for individual electrodes, and the dummy pad electrode 35 and the dummy piezoelectric element 40 are connected. As a result, charge concentration on the individual electrode 163 to which the pad electrode 21 for the individual electrode is connected can be suppressed, and insulation breakdown in the piezoelectric element 16 of the droplet discharge portion (drive channel) can be prevented. However, since the charge injection concentrates on the dummy pad electrode 35, the dielectric breakdown occurs in the dummy piezoelectric element 40. Although cracks occurred in the dummy piezoelectric element 40 starting from this dielectric breakdown part, there is no problem in quality because the piezoelectric element is an undriven channel. Further, by forming the bump electrode 27 on the pad electrode 21 for the individual electrode as in the second embodiment, the amount of charge injection into the pad electrode 21 can be increased, and the aforementioned polarization amount difference (Pr-Pini) is reduced. I was able to.

<Example 3>
Next, Example 3 will be described with reference to FIG.
In Example 3, a droplet discharge head was manufactured in the same manner as in Examples 1 and 2 except for the following points.
In an ink jet type image forming apparatus using a droplet discharge head having the above-described configuration, an increase in the number of nozzles is required for the purpose of improving the printing speed, and the droplet discharge head is becoming longer. In order to realize the long length of the multi-nozzle and the droplet discharge head, it is necessary to mount a plurality of piezoelectric element driving ICs on the same row. Therefore, in order to secure the mounting accuracy of the piezoelectric element driving IC and the mounting area 50, the distance between the pad electrodes for the individual electrodes is increased in the connecting portion 51 of the piezoelectric element driving IC. Since electric charges are concentrated on the pad electrode for the individual electrode of the connecting portion 51 which becomes the discontinuous portion during the polarization treatment by corona discharge or the like, dielectric breakdown is likely to occur.

Therefore, in the third embodiment, the dummy pad electrode 36 is positioned adjacent to the individual electrode pad electrode 21 in the connecting portion 51 between the plurality of mounting areas 50 to which the individual piezoelectric element driving ICs are connected. Is provided. The dummy pad electrodes 36 are formed on the same column as the individual electrode pad electrodes 21 at the same pitch as the individual electrode pad electrodes 21 and are connected to the dummy piezoelectric elements 41.
The dummy piezoelectric elements 41 cannot be formed on the same column as the piezoelectric elements 16 of the droplet discharge section (drive channel) in terms of layout, but are disposed at positions away from the columns of the piezoelectric elements 16. The dummy piezoelectric element 41 is not limited in shape, and is preferably set so that the facing area is the same as that of the piezoelectric element 16 of the droplet discharge portion (drive channel) so that the electrostatic capacitance is the same. . By aligning the areas so that the capacitances are the same, the charge injection profile during polarization processing by corona discharge or the like can be aligned with the droplet discharge portion (drive channel), and the polarization amount difference (Pr) within the column -Pini
) Can be suppressed.

  Here, liquid chamber processing is not performed immediately below the dummy piezoelectric element 41 between the piezoelectric element driving ICs. This is because if the liquid chamber processing is performed at a place other than the same row, the stress distribution of silicon constituting the liquid chamber becomes non-uniform. If the stress distribution of the silicon constituting the liquid chamber 13 becomes non-uniform, stress is applied to a part of the diaphragm 15, which causes variations in deformation (displacement) characteristics of the piezoelectric element 16.

  In the third embodiment, as a result of the trial evaluation with the above configuration, as in the second embodiment, the droplet discharge portion (drive channel) of the connecting portion 51 of the piezoelectric element driving IC was stable without causing dielectric breakdown. It was confirmed that a polarization amount difference was obtained.

Next, Example 4 will be described with reference to FIG.
In Example 4, a droplet discharge head was manufactured in the same manner as Examples 1 and 2 except for the following points.
In the fourth embodiment, four dummy pad electrodes 36 are continuously formed in the connecting portion 51 between the piezoelectric element driving ICs, and the four dummy pad electrodes 36 are proportional to the number of the dummy pad electrodes 36. Are connected in common by quadrupling the area of a single dummy piezoelectric element 42 connected to each other. By sharing the dummy piezoelectric element 42, the installation area can be reduced as compared with the case where the dummy piezoelectric element 42 is provided individually. Therefore, the chip area on which the actuator substrate 25 is formed can be reduced and the size can be reduced. In addition, since the number of dummy pad electrodes 36 within a very small area can be increased, the variation in the polarization amount difference between the piezoelectric elements in the row can be more reliably reduced.

  As described above, the liquid discharge evaluation was performed using the droplet discharge head 10 manufactured in Examples 1 to 4 described above. Using an ink whose viscosity is adjusted to 5 [cp], and confirming the discharge state when a voltage of −3 to −20 [V] is applied by a simple push waveform, ink droplets are discharged from all the nozzle holes 11. It was confirmed that stable ejection was possible.

<Example 5>
Next, Example 5 will be described with reference to FIG.
In Example 5, a droplet discharge head was produced in the same manner as in Examples 1 and 2 except for the following points.
In the fifth embodiment, the dummy pad electrode 35 formed at a position adjacent to the end of the row of the plurality of individual electrode pad electrodes 21 is connected to the ground (GND) wiring 38 via the wiring 37. Yes.
Further, in Example 5, in the polarization treatment by corona discharge, a φ50 [μm] tungsten corona wire is used, and the distance between the corona wire and the sample to be processed (actuator substrate) is set to 5 [mm]. A voltage of 6 [kV] was applied to the corona wire, and the sample (actuator substrate) was subjected to polarization treatment for 20 minutes.

<Example 6>
In this Example 6, in the polarization process using corona discharge, a voltage of 8 [kV] was applied to the corona wire, and the sample (actuator substrate) was subjected to the polarization process for 20 minutes. An actuator substrate 25 including a piezoelectric element similar to that shown in FIG.

<Example 7>
In this example 7, in the polarization process using corona discharge, a voltage of 6 [kV] was applied to the corona wire and the sample (actuator substrate) was subjected to the polarization process for 1 minute. An actuator substrate 25 including a piezoelectric element similar to that shown in FIG.
<Example 8>
In the eighth embodiment, as shown in FIG. 13, the actuator substrate 25 including the piezoelectric element similar to the fifth embodiment is formed except that the ground (GND) wiring 38 ′ is patterned and drawn to a position directly below the dummy pad electrode 35. Was made.

<Comparative example 2>
An actuator substrate 25 including a piezoelectric element similar to that of Example 5 was manufactured, except that the polarization treatment corona charging treatment using corona discharge was not performed.

<Comparative Example 3>
An actuator substrate 25 including a piezoelectric element similar to that of Example 5 was prepared except that no dummy PAD was prepared for the individual electrode PAD row.

The piezoelectric elements manufactured in Examples 5 to 8 and Comparative Examples 2 and 3 were evaluated for electrical characteristics and electromechanical conversion ability (piezoelectric constant). A typical PE hysteresis curve is shown in FIG. The electromechanical conversion ability (piezoelectric constant) was calculated by measuring the amount of deformation by applying an electric field (150 [kV / cm]) with a laser Doppler vibrometer and fitting by simulation. After evaluating the initial characteristics, durability (characteristics immediately after applying the applied voltage 1 × 10 ¹⁰ times) was evaluated.
About Examples 5-8, it had the characteristic equivalent to a general ceramic sintered compact also about the result after an initial stage characteristic and a durability test. Specifically, the remanent polarization Pr was 20 to 27 [μC / cm ² ], and the piezoelectric constant was −120 to −160 [pm / V].
About the comparative examples 2 and 3, a characteristic does not change compared with a general ceramic sintered compact as some initial characteristics. However, in the characteristic after 1 × 10 ¹⁰ times with respect to Comparative Example 2 (immediately after the addition of 1 × 10 ¹⁰ times repeatedly applied voltage), as compared with Examples 5-8, was confirmed to have significantly degraded It was. Further, with respect to the comparative example 2, as shown in the piezoelectric element 16 surrounded by the frame A in FIG.

  Moreover, the liquid discharge head of FIG. 16 was produced using the piezoelectric element produced in Examples 5-8, and liquid discharge evaluation was performed. Using an ink whose viscosity is adjusted to 5 [cp], and confirming the discharge state when an applied voltage of −10 to −30 [V] is applied by a simple push waveform, ink droplets are discharged from all the nozzle holes 11. Was confirmed to be discharged. FIG. 16 is a configuration example in which a plurality of droplet discharge heads 10 of FIG. 1 having one nozzle hole 11 are arranged.

  As described above, according to this embodiment, the piezoelectric element 16 having performance equivalent to that of bulk ceramics can be formed by a simple manufacturing process. Then, as shown in FIGS. 1 and 16 described above, etching is removed from the back surface for forming the subsequent liquid chamber (pressure chamber) 13, and the nozzle plate 12 having the nozzle holes 11 is joined to thereby remove the liquid. The droplet discharge head 10 can be manufactured. 1 and 16, the liquid supply means, the flow path, and the fluid resistance are not shown.

Next, an image forming apparatus provided with the droplet discharge head having the above configuration will be described.
FIG. 13 is a side view illustrating an example of an image forming apparatus including the droplet discharge head according to the present embodiment. FIG. 14 is a partial plan view of the image forming apparatus.
In the image forming apparatus of the present embodiment, a carriage 103 as a droplet discharge device (ink droplet discharge device) includes a guide rod 101 and a guide rail 102 that are horizontally mounted on left and right side plates (not shown). Is slidably held on the surface. The carriage 103 is moved and scanned in the direction indicated by the arrow (main scanning direction) via the timing belt 105 spanned between the driving pulley 106A and the driven pulley 106B by the main scanning motor 104.

  A recording head 107 is disposed on the carriage 103 in a direction along the main scanning direction, and is mounted with the droplet discharge direction facing downward. The recording head 107 is, for example, droplet discharge heads 107k, 107c, and 107m that discharge recording liquid droplets (ink droplets) of each color of black (K), cyan (C), magenta (M), and yellow (Y). , 107y. Although an independent droplet discharge head is used here, a configuration in which one or a plurality of heads having a plurality of nozzle rows that discharge droplets of recording liquid of each color can be used. Further, the number of colors and the arrangement order are not limited to this.

  In addition, the carriage 103 is equipped with a sub tank 108 for each color for supplying each color ink to the recording head 107. Ink is supplied to the sub tank 108 from a main tank (ink cartridge) (not shown) via an ink supply tube 109.

  Further, the image forming apparatus according to the present embodiment is provided with a paper feeding unit for feeding paper 112 as a recording medium stacked on a paper stacking unit (pressure plate) 111 such as a paper feeding cassette 110. The paper feed unit includes a paper feed roller 113 and a separation pad 114 that are half-moon rollers that separate and feed paper 112 from the paper stacking unit 111 one by one. The separation pad 114 is made of a material having a large friction coefficient, facing the paper feed roller 113. The separation pad 114 is biased toward the paper feed roller 113 side.

  In addition, the image forming apparatus according to the present embodiment is provided with a transport unit for transporting the paper 112 fed from the paper feed unit below the recording head 107. The transport unit includes a transport belt 121 for electrostatically attracting and transporting the paper 112 and a counter for transporting the paper 112 sent from the paper feed unit via the guide 115 with the transport belt 121 interposed therebetween. And a roller 122. Further, the conveying unit is urged toward the conveying belt 121 by a conveying guide 123 for changing the direction of the sheet 112 sent substantially vertically upward by approximately 90 ° and following the conveying belt 121 and a pressing member 124. The pressure roller 125A and the tip pressure roller 125B are provided. Further, a charging roller 126 that is a charging unit for charging the surface of the transport belt 121 is provided.

  Here, the conveyance belt 121 is an endless belt, and is stretched between the conveyance roller 127 and the tension roller 128. Then, the conveyance roller 127 is rotated from the sub-scanning motor 131 via the timing belt 132 and the timing roller 133 so that the conveyance belt 121 circulates in the belt conveyance direction (sub-scanning direction). A guide member 129 is disposed on the back side of the conveying belt 121 so as to correspond to an image forming area formed by the recording head 107.

  The charging roller 126 is disposed so as to contact the surface layer of the conveyor belt 121 and rotate following the rotation of the conveyor belt 121. For example, 2.5 [N] is applied to both ends of the shaft as a pressing force. Yes.

  Further, the image forming apparatus according to the present embodiment is provided with a paper discharge unit for discharging the paper 112 recorded by the recording head 107. The paper discharge unit includes a separation unit for separating the paper 112 from the conveyance belt 121, a paper discharge roller 152 and a paper discharge roller 153, and a paper discharge tray 154 that stocks the paper 112 to be discharged. .

  A double-sided paper feeding unit 155 is detachably attached to the back of the image forming apparatus according to the present embodiment. The double-sided paper feeding unit 155 takes in the paper 112 returned by the reverse rotation of the transport belt 121, reverses it, and feeds it again between the counter roller 122 and the transport belt 121.

  Further, as shown in FIG. 14, a maintenance / recovery mechanism 156 for maintaining and recovering the state of the nozzles of the recording head 107 is disposed in a non-printing area on one side of the carriage 103 in the scanning direction. The maintenance / recovery machine 156 includes caps 157 for capping each nozzle surface of the recording head 107 and a wiper blade 158 which is a blade member for wiping the nozzle surface. Further, the maintenance / recovery machine 156 includes a blank discharge receiver 159 for receiving droplets when performing blank discharge for discharging droplets that do not contribute to recording in order to discharge the thickened recording liquid (ink).

  In the image forming apparatus configured as described above, the sheets 112 are separated and fed one by one from the sheet feeding unit, and the sheet 112 fed substantially vertically upward is guided by the guide 115, and includes the transport belt 121 and the counter roller. It is sandwiched between and conveyed. Further, the leading edge of the paper 112 is guided by the transport guide 123 and pressed against the transport belt 121 by the front end pressure roller 125, and the transport direction is changed by approximately 90 °. At this time, a positive voltage and a negative output are alternately applied to the charging roller 126 from the AC bias supply unit by a control circuit (not shown), that is, an alternating voltage is applied. As a result, the charging voltage pattern in which the conveyor belt 121 alternates, that is, plus and minus are alternately charged in a band shape with a predetermined width in the sub-scanning direction that is the circumferential direction. When the paper 112 is fed onto the conveyance belt 121 charged alternately with plus and minus, the paper 112 is attracted to the conveyance belt 121 by electrostatic force, and the paper 112 is conveyed in the sub-scanning direction by the circular movement of the conveyance belt 121. Is done.

  Then, by driving the recording head 107 according to the image signal while moving the carriage 103 in the forward and backward directions, ink droplets are ejected onto the stopped paper 112 to record one line, and the paper 112 is After transporting a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 112 has reached the recording area, the recording operation is finished, and the paper 112 is discharged onto the paper discharge tray 154.

  In the case of double-sided printing, the recorded paper 112 is fed into the double-sided paper feeding unit 155 by reversely rotating the transport belt 121 when the recording of the front surface (surface to be printed first) is completed. . Then, the paper 112 is reversed by the double-sided paper feeding unit 155 (with the back surface being the printing surface) and fed again between the counter roller 122 and the conveyor belt 121. Timing control is performed according to this paper feed, and the paper 112 on which the image is recorded on both sides is discharged to the paper discharge tray 154 after being transported onto the transport bell 121 and recorded on the back surface in the same manner as described above. Is done.

  During printing (recording) standby, the carriage 103 is moved to the maintenance / recovery mechanism 155 side, the nozzle surface of the recording head 107 is capped by the cap 157, and the nozzle is kept in a wet state to prevent ejection failure due to ink drying. Is done. Further, the recording liquid is sucked from the nozzle in a state where the recording head 107 is capped by the cap 157 (referred to as “nozzle suction” or “head suction”), and a recovery operation for discharging the thickened recording liquid and bubbles is performed. Wiping is performed by the wiper blade 158 in order to clean and remove ink adhering to the nozzle surface of the recording head 107 by this recovery operation. In addition, an idle ejection operation for ejecting ink not related to recording is performed before the start of recording or during recording. Thereby, the stable ejection performance of the recording head 107 is maintained.

  As described above, since the image forming apparatus according to the present embodiment includes the recording head configured by the droplet discharge head having the above-described configuration, it is possible to reduce the size and cost and to discharge with the same discharge head size. Since the number of nozzles can be increased, further high-speed printing is possible.

  In the above embodiment, the present invention has been described with reference to an example in which the present invention is applied to an image forming apparatus having a printer configuration. However, the present invention is not limited to this. For example, the present invention may be applied to an image forming apparatus such as a printer / fax / copier multifunction machine. it can. The present invention can also be applied to an image forming apparatus using a recording liquid or a fixing processing liquid that is a liquid other than ink.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A nozzle 11 for discharging droplets, a liquid chamber 13 communicating with the nozzle 11, an electromechanical conversion element such as a piezoelectric element 16 provided on a substrate so as to pressurize the liquid in the liquid chamber 13, and an electromechanical conversion A first terminal electrode such as a pad electrode 19 connected to a first drive electrode such as a common electrode 161 on the substrate side of the element and a second electrode such as an individual electrode 163 opposite to the substrate side of the electromechanical transducer. A plurality of second terminal electrodes such as the pad electrode 21 connected to the drive electrodes, the plurality of second terminal electrodes being arranged at a predetermined interval, and the plurality of second terminal electrodes A dummy terminal electrode such as a dummy pad electrode 35 was provided at a position adjacent to the end of the row of terminal electrodes.
According to this, as described in the above embodiment, by performing a discharge treatment toward the opening where at least the first terminal electrode and the second terminal electrode of the cover member are exposed, the terminal electrode is charged. Can be injected. Since the charges injected into the terminal electrode reach the first drive electrode and the second drive electrode, charges having different charge amounts can be applied to the first drive electrode and the second drive electrode. . Since a predetermined potential difference is formed between the first drive electrode and the second drive electrode by the application of the electric charge, the electromechanical conversion element can be polarized. This electric discharge polarization process does not require a probe card that is brought into direct contact with the terminal electrode, and can be polarized at once for a plurality of electromechanical transducer elements with a simple configuration, thereby reducing the manufacturing cost. Can do.
In addition, since dummy terminal electrodes such as the dummy pad electrode 35 are provided at positions adjacent to the end portions of the plurality of second terminal electrode rows, the end portions of the plurality of second terminal electrode rows are provided. Excessive charge injection into can be avoided. Therefore, excessive charge concentration on the electromechanical conversion element connected to the second terminal electrode at the end portion does not occur, and the dielectric breakdown of the electromechanical conversion element can be avoided. More uniform polarization processing becomes possible. Therefore, it is possible to reduce variation in polarization characteristics of the electromechanical transducer that is polarized by the injected charge.
As described above, it is possible to reduce the variation in polarization characteristics of the electromechanical transducer while reducing the manufacturing cost.
(Aspect B)
In the aspect A, the plurality of second terminal electrodes are arranged so as to be arranged at a predetermined interval, and the dummy terminal electrodes are arranged along the row of the plurality of second terminal electrodes. Are provided at positions adjacent to the end portions of the row of the plurality of second terminal electrodes at the same intervals as the terminal electrodes. According to this, as described in the above embodiment, excessive charge injection to the end of the row of the plurality of second terminal electrodes can be avoided more reliably, so that the variation in the polarization characteristics of the electromechanical transducer element Can be more reliably reduced.
(Aspect C)
In the above aspect A or B, the dummy terminal electrode has the same area as the second terminal electrode. According to this, as described in the above embodiment, excessive charge injection to the end of the row of the plurality of second terminal electrodes can be avoided more reliably, so that the variation in the polarization characteristics of the electromechanical transducer element Can be more reliably reduced.
(Aspect D)
In any one of the aspects A to C, bump electrodes are formed on the dummy terminal electrode and the second terminal electrode. According to this, since the surface area of the terminal electrode exposed to discharge can be increased as described in the above embodiment, a predetermined charge can be stably injected into the terminal electrode, and stable due to discharge. Polarization processing can be performed.
(Aspect E)
In the above aspect D, the bump electrode is a gold stud bump electrode. According to this, as described in the above embodiment, the manufacturing cost can be reduced as compared with the gold plating bump electrode.
(Aspect F)
In any one of the above aspects A to E, a charge storage element connected to the dummy terminal electrode is provided. According to this, as described in the above embodiment, since the charge injected into the dummy terminal electrode by discharge can be released and stored in the charge storage element, an excessive increase in the charge amount at the dummy terminal electrode can be avoided. Insulation breakdown in the dummy terminal electrode can be prevented.
(Aspect G)
In the above aspect F, the charge storage element is the same element as the electromechanical conversion element. According to this, since the increase in the amount of charge in the dummy terminal electrode is equivalent to that of the second terminal electrode adjacent to the dummy terminal electrode, as described in the above embodiment, Dielectric breakdown can be prevented more reliably.
(Aspect H)
In the aspect F or G, the plurality of electromechanical conversion elements are arranged so as to be arranged at a predetermined interval, and the charge storage element is arranged along the column direction of the plurality of electromechanical conversion elements. It is provided at a position adjacent to the end of the row of the plurality of electromechanical transducer elements at the same interval as that of the transducer elements. According to this, since the charge storage element can be formed in the same manner as the plurality of electromechanical conversion elements as described in the above embodiment, the manufacture is facilitated.
(Aspect I)
In the aspect F or G, the plurality of electromechanical conversion elements are arranged so as to be arranged at a predetermined interval, and the charge storage elements are provided at positions different from the column direction of the plurality of electromechanical conversion elements. Yes. According to this, as described in the above embodiment, the charge storage element can be formed without being affected by the arrangement direction of the columns of the plurality of electromechanical conversion elements, and restrictions on the layout of the charge storage element Less.
(Aspect J)
In any one of the above aspects A to I, a plurality of the dummy terminal electrodes are formed so as to be arranged at a predetermined interval, and the plurality of dummy terminal electrodes has a capacitance according to the number of the dummy terminal electrodes. Is connected to a single charge storage element. According to this, as described in the above-described embodiment, the charge storage element is provided for each of the plurality of dummy terminal electrodes, so that the charge storage element is provided as compared with the case where the charge storage element is provided individually. The area can be reduced. Therefore, the size can be reduced. In addition, the number of dummy terminal electrodes within a very small area can be increased, and variations in the polarization amount difference between the electromechanical transducers in the column can be reduced.
(Aspect K)
In any one of the above aspects A to E, the dummy terminal electrode is connected to the ground. According to this, as described in the above embodiment, since the electrification excessively injected into the dummy terminal electrode can be quickly released to the ground, in the second terminal electrode adjacent to the dummy terminal electrode Charge concentration can be prevented more effectively.
(Aspect L)
In any one of the above aspects A to K, the electromechanical transducer is provided with a structure such as a subframe provided so as to cover the electromechanical transducer via a gap. According to this, as described in the above embodiment, even when the structure is provided, it is possible to reduce the variation in the polarization characteristics of the electromechanical conversion element when the polarization treatment by the discharge is performed. .
(Aspect M)
In any one of the above aspects A to K, an insulating protective film such as a second insulating protective film 23 is provided so as to cover the electromechanical conversion element in contact with the electromechanical conversion element. . According to this, as described in the embodiment, even when the insulating protective film is provided, it is possible to reduce variations in the polarization characteristics of the electromechanical conversion element when the polarization treatment by the discharge is performed. Can do.
(Aspect N)
A polarization processing method for an electromechanical conversion element in a droplet discharge head according to any one of the above aspects A to M, wherein the first terminal electrode, the second terminal electrode, and the discharge means are interposed via a gap. The step of making it mutually oppose and the electric charge of mutually different electric charge amount is provided to the said 1st drive electrode and the said 2nd drive electrode via the said 1st terminal electrode and the said 2nd terminal electrode by the said discharge means. And a step of performing a discharge treatment toward the first terminal electrode and the second terminal electrode. According to this, as described in the above embodiment, it is possible to reduce the variation in the polarization characteristics of the electromechanical conversion element while reducing the manufacturing cost.
(Aspect O)
In the above aspect N, the discharge treatment is performed such that positive charges generated by corona discharge or glow discharge are injected into the first terminal electrode and the second terminal electrode. According to this, as described in the above embodiment, charge injection into the terminal electrode can be stably performed, and stable polarization processing can be performed.
(Aspect P)
In the above aspect N or O, the electric discharge treatment is performed by applying a voltage so that the electric field strength is ± 150 [kV / cm] with respect to the electromechanical conversion element. The related hysteresis loop is measured, the polarization when the electric field strength at the start of the measurement is 0 [kV / cm] is Pini, and the electric field strength becomes 0 [kV / cm] after the subsequent electric field strength becomes +150 [kV / cm]. / Cm], the polarization amount difference Pr-Pini is set to 10 [μC / cm ² ] or less, where Pr is the polarization when returning to / cm]. According to this, as described in the above embodiment, deformation deterioration (displacement deterioration) after continuous driving of the electromechanical conversion element can be prevented, and stable droplet discharge characteristics can be obtained over a long period of time.
(Aspect Q)
A nozzle 11 for discharging droplets, a liquid chamber 13 communicating with the nozzle 11, an electromechanical conversion element such as a piezoelectric element 16 provided on a substrate so as to pressurize the liquid in the liquid chamber 13, and an electromechanical conversion A first terminal electrode such as a pad electrode 19 connected to a first drive electrode such as a common electrode 161 on the substrate side of the element and a second electrode such as an individual electrode 163 opposite to the substrate side of the electromechanical transducer. A plurality of second terminal electrodes such as the pad electrode 21 connected to the driving electrodes of the liquid droplet ejection head, wherein the plurality of second terminal electrodes are arranged so as to be arranged at a predetermined interval. A manufacturing method, the step of providing an electromechanical conversion element provided on the substrate, the step of forming the first terminal electrode and the second terminal electrode, the step of providing the cover member, Claims N to P And, including the. According to this, as described in the above embodiment, it is possible to reduce the variation in the droplet discharge characteristics of the droplet discharge head while reducing the manufacturing cost of the droplet discharge head.
(Aspect R)
A droplet discharge apparatus including the droplet discharge head according to any one of the above aspects A to M. According to this, as described in the above embodiment, it is possible to reduce the variation in droplet discharge characteristics of the droplet discharge head while reducing the manufacturing cost of the droplet discharge device.
(Aspect S)
A droplet discharge device including a droplet discharge head having an electromechanical conversion element processed by the polarization processing method according to any one of the above aspects N to P. According to this, as described in the above embodiment, it is possible to reduce the variation in droplet discharge characteristics of the droplet discharge head while reducing the manufacturing cost of the droplet discharge device.
(Aspect T)
An image forming apparatus including the droplet discharge device according to the aspect R or S as the ink droplet discharge device. According to this, as described in the above embodiment, it is possible to improve the image quality by reducing the variation in the droplet ejection characteristics of the droplet ejection head while reducing the manufacturing cost of the image forming apparatus. .

10 Liquid droplet ejection part 11 Nozzle 12 Nozzle substrate 13 Liquid chamber (pressure chamber)
14 Substrate (Liquid chamber substrate)
15 Diaphragm 16 Piezoelectric element 161 Common electrode (lower electrode)
162 Piezoelectric film (piezoelectric material)
163 Individual electrode (upper electrode)
DESCRIPTION OF SYMBOLS 15 Diaphragm 18 1st insulating protective film 18a Contact hole 19 Pad electrode for common electrodes 20 1st wiring 21 Pad electrode for individual electrodes 22 2nd wiring 23 2nd insulating protective film 23a Contact hole 25 Actuator substrate 26 Subframe 26a Recessed part 26b-26d Opening 27 Bump electrode 28 Silicon wafer 29 Actuator 31 Corona wire 32 Grid electrode 33 Base plate 35, 36 Dummy pad electrode 37 Wiring 38, 38 'Ground (GND) wiring 40-42 Dummy piezoelectric element 107 Recording head

JP 2004-202849 A JP 2010-034154 A JP 2006-203190 A Japanese Patent No. 3784401

Claims (15)

A nozzle for ejecting liquid droplets, a liquid chamber communicating with the nozzle, an electromechanical conversion element provided on the substrate so as to pressurize the liquid in the liquid chamber, and a substrate-side first of the electromechanical conversion element A plurality of first terminal electrodes connected to one drive electrode and a second terminal electrode connected to a second drive electrode on the opposite side of the substrate side of the electromechanical transducer,
The plurality of second terminal electrodes are arranged so as to be arranged at a predetermined interval, and a dummy terminal electrode is provided at a position adjacent to an end of the row of the plurality of second terminal electrodes,
Bump electrodes are formed on the dummy terminal electrode and the second terminal electrode,
A polarized dummy electromechanical transducer is connected to the dummy terminal electrode,
The plurality of electromechanical transducer elements are arranged to be arranged at a predetermined interval,
The liquid droplet ejection head, wherein the dummy electromechanical transducer element is provided at a position different from a column direction of the plurality of electromechanical transducer elements. The droplet discharge head according to claim 1.
The plurality of second terminal electrodes are arranged to be arranged at a predetermined interval,
The dummy terminal electrode is adjacent to an end portion of the plurality of second terminal electrode rows at the same interval as the interval between the plurality of second terminal electrodes along the row of the plurality of second terminal electrodes. A droplet discharge head provided at a position where In the liquid droplet ejection head according to claim 1 or 2,
The liquid droplet ejection head, wherein the dummy terminal electrode has the same area as the second terminal electrode. The droplet discharge head according to any one of claims 1 to 3,
The droplet discharge head, wherein the bump electrode is a gold stud bump electrode. The droplet discharge head according to any one of claims 1 to 4,
The liquid droplet ejection head, wherein the dummy electromechanical conversion element is the same element as the electromechanical conversion element. The droplet discharge head according to any one of claims 1 to 5,
A plurality of the dummy terminal electrodes are formed to be arranged at a predetermined interval,
The droplet discharge head, wherein the plurality of dummy terminal electrodes are connected to a single dummy electromechanical transducer having a capacitance set according to the number of dummy terminal electrodes. The droplet discharge head according to any one of claims 1 to 6,
A droplet discharge head, comprising: a structure provided on the electromechanical conversion element so as to cover the electromechanical conversion element through a gap. The droplet discharge head according to any one of claims 1 to 6,
A droplet discharge head, comprising: an insulating protective film provided to cover the electromechanical conversion element in contact with the electromechanical conversion element. A method for polarization treatment of an electromechanical transducer in a droplet discharge head according to any one of claims 1 to 8,
Making the first terminal electrode and the second terminal electrode and the discharge means face each other with a gap between them;
The discharge means applies the first charge electrode and the second drive electrode to the first drive electrode and the second drive electrode through the first terminal electrode and the second terminal electrode, respectively, so as to give different charges. And a step of performing a discharge treatment toward the terminal electrode and the second terminal electrode. A nozzle for ejecting liquid droplets, a liquid chamber communicating with the nozzle, an electromechanical conversion element provided on the substrate so as to pressurize the liquid in the liquid chamber, and a substrate-side first of the electromechanical conversion element A plurality of first terminal electrodes connected to one drive electrode, and a second terminal electrode connected to a second drive electrode opposite to the substrate side of the electromechanical transducer, In a droplet discharge head in which a plurality of second terminal electrodes are arranged so as to be arranged at a predetermined interval and a dummy terminal electrode is provided at a position adjacent to an end of a row of the plurality of second terminal electrodes. A polarization processing method for an electromechanical transducer,
Making the first terminal electrode and the second terminal electrode and the discharge means face each other with a gap between them;
The discharge means applies the first charge electrode and the second drive electrode to the first drive electrode and the second drive electrode through the first terminal electrode and the second terminal electrode, respectively, so as to give different charges. And a step of performing a discharge treatment toward the terminal electrode and the second terminal electrode. In the method for polarization treatment of an electromechanical transducer according to claim 9 or 10,
The electromechanical transducer polarization treatment method, wherein the discharge treatment is performed such that positive charges generated by corona discharge or glow discharge are injected into the first terminal electrode and the second terminal electrode. . In the method for polarization treatment of an electromechanical transducer according to claim 9, 10 or 11,
In the discharge treatment, a voltage is applied to the electromechanical transducer so that the electric field strength is ± 150 [kV / cm], and a hysteresis loop of the relationship between the electric field strength and polarization of the electromechanical transducer is measured. When the electric field strength at the start of measurement is 0 [kV / cm], the polarization is Pini, and the electric field strength returns to 0 [kV / cm] after the subsequent electric field strength becomes +150 [kV / cm] A polarization treatment method for an electromechanical conversion element, wherein the polarization rate Pr-Pini is 10 [μC / cm ² ] or less when the polarization of Pr is Pr. A nozzle for ejecting liquid droplets, a liquid chamber communicating with the nozzle, an electromechanical conversion element provided on the substrate so as to pressurize the liquid in the liquid chamber, and a substrate-side first of the electromechanical conversion element A plurality of sets of first terminal electrodes connected to one drive electrode and second terminal electrodes connected to a second drive electrode opposite to the substrate side of the electromechanical transducer,
A cover member having at least an insulating surface provided to cover the electromechanical conversion element;
A method of manufacturing a droplet discharge head, wherein the plurality of second terminal electrodes are arranged so as to be arranged at a predetermined interval,
Providing an electromechanical conversion element provided on the substrate;
Forming the first terminal electrode and the second terminal electrode;
Providing the cover member;
A method for manufacturing a droplet discharge head, comprising the step of polarization processing according to claim 9. Droplet discharge apparatus having any one of the droplet discharge head according to claim 1 to 8.   An image forming apparatus comprising the droplet discharge device according to claim 14 as an ink droplet discharge device.