JP6566323B2 - Droplet discharge head, droplet discharge apparatus, and image forming apparatus - Google Patents

Description

The present invention, a droplet discharge head having electrical transducer, to a droplet ejection apparatus and image forming apparatus equipped with the droplet discharge head.

  It is used in an ink jet recording apparatus that has a droplet discharge head equipped with this type of electromechanical conversion element and forms an image by adhering ink droplets to a sheet while conveying a medium. The medium here is also referred to as “paper”, but the material is not limited, and a recording medium, a recording medium, a transfer material, a recording paper, and the like are also used synonymously. The image forming apparatus means an apparatus for forming an image by discharging a liquid onto a medium such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics. The image formation is not only giving an image having a meaning such as a character or a figure to the medium but also giving an image having no meaning such as a pattern to the medium (simply ejecting a droplet). Also means. The ink is not limited to so-called ink, and is not particularly limited as long as it becomes liquid when ejected. For example, the ink is a generic term for liquids including DNA samples, resists, pattern materials, and the like. Use.

  2. Description of the Related Art Conventionally, a nozzle hole that discharges a liquid droplet 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 hole and contains a liquid, and the liquid chamber A droplet discharge head including a piezoelectric element as the electromechanical conversion element for pressurizing the liquid is known. In this droplet discharge head, when a predetermined droplet discharge voltage is applied to the piezoelectric element, it vibrates so as to deform the diaphragm that forms part of the wall of the liquid chamber, and the liquid is deformed by the deformation of the diaphragm. The liquid in the chamber is pressurized and droplets can be ejected from the nozzle holes.

  Also. The crystal of the piezoelectric film constituting the piezoelectric element is in a random state of polarization as shown in FIG. 16A immediately after the production of the piezoelectric film and before the polarization treatment. Thereafter, by repeatedly applying a polarization voltage for performing the polarization treatment, the crystal of the piezoelectric film becomes an aggregate of domains (domains) in which the directions of polarization are aligned as shown in FIG. . The direction of polarization in the crystal of the piezoelectric film 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 is known 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, in the method of manufacturing an electromechanical conversion element of Patent Document 1, a first drive electrode as a common electrode is formed on a substrate, and a piezoelectric material is formed on the first drive electrode to form an electromechanical conversion film. A piezoelectric film is formed. Charge supply means for generating corona discharge is disposed on the surface of the piezoelectric film so as to face the surface with a gap. Charge is supplied to the surface of the piezoelectric film by the corona discharge. As a result, a potential difference is generated in the piezoelectric film to perform polarization processing of the piezoelectric film.

The present invention is to provide an image forming apparatus capable of forming a electrical machinery transducer mounted droplet discharge head having a desired droplet ejection characteristics, a droplet discharge apparatus and high-quality image.

In order to achieve the above object, the invention of claim 1 is directed to a nozzle that discharges droplets, a liquid chamber that communicates with the nozzle, a diaphragm that forms part of a wall of the liquid chamber, and the diaphragm. A plurality of piezoelectric elements provided on the common electrode, a piezoelectric body, and individual electrodes laminated; a common electrode pad electrically connected to the common electrode; and a plurality electrically connected to the individual electrodes. A plurality of the individual electrode pads arranged in a row, and when viewed from the arrangement direction of the individual electrode pads, at least one of the common electrode pads. The part is arranged so as to overlap the individual electrode pad, and when the hysteresis loop is measured by applying an electric field strength of ± 150 [kV / cm] to the piezoelectric body, 0 [kV / cm at the start of measurement] ] In Pini And + 150 after voltage application [kV / cm], 0 [ kV / cm] when the polarization time 0 [kV / cm] at the time of returning to the Pr to the difference between the Pr and Pini is 10 [[mu] C / cm ² ] It is characterized by the following .

According to the present invention, there is a specific effect that it is possible to provide a droplet discharge head, a droplet discharge device, and an image forming apparatus that can form a high-quality image having an electromechanical conversion element and having desired droplet discharge characteristics. can get.

It is a perspective view which shows the structure of an inkjet recording device. It is a side view of the mechanism part of an inkjet recording device. 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. It is sectional drawing which shows an example of the layer structure of the diaphragm on a board | substrate, and a piezoelectric element. It is sectional drawing of a piezoelectric element periphery. It is a top view around a piezoelectric element. (A) And (b) is a characteristic view 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. It is a perspective view which shows an example of the whole structure of a polarization processing apparatus. It is a characteristic view which shows the change of the polarization amount difference (Pr-Pini) with respect to the distance of the horizontal direction orthogonal to the wire axial direction of a corona wire. It is explanatory drawing which shows typically the mode of the electric charge injection | pouring to the piezoelectric element by the discharge process in a polarization processing apparatus. SrRuO ₃ film is a characteristic diagram showing the X-ray diffraction measurement results of the formed samples. (A) is a top view which shows Example 2 of a separation process, (b) is a schematic side view. (A) is a top view which shows Example 2 of a separation process, (b) is a schematic side view. (A) is a top view which shows the comparative example of a separation process, (b) is a schematic side view. It is sectional drawing which shows the structure provided with the some droplet discharge head. (A) is explanatory drawing which shows the mode of the domain of the piezoelectric film before polarization processing. (B) is explanatory drawing which shows the mode of the domain of the piezoelectric film after polarization processing.

  First, the configuration of an ink jet recording apparatus equipped with an ink jet recording head which is an example of a liquid droplet ejection head according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration of an ink jet recording apparatus, and FIG. 2 is a side view of a mechanism portion of the ink jet recording apparatus.

  An ink jet recording apparatus 100 shown in FIGS. 1 and 2 accommodates a printing mechanism 103 and the like. The printing mechanism 103 and the like are configured by a droplet discharge head 1 mounted on a carriage 101 movable in the main scanning direction inside the apparatus main body and an ink cartridge 102 for supplying ink to the droplet discharge head 1. . A sheet feeding cassette (or a sheet feeding tray) 104 on which a large number of recording sheets P can be stacked from the front side is detachably attached to the lower part of the apparatus main body. Further, it has a manual feed tray 105 that is opened to manually feed the recording paper P, takes in the recording paper P fed from the paper feed cassette 104 or the manual feed tray 105, and prints a required image by the printing mechanism unit 103. After recording, the paper is discharged to a paper discharge tray 106 mounted on the rear side.

  The printing mechanism 103 holds the carriage 101 slidably in the main scanning direction with a main guide rod 107 and a sub guide rod 108 which are guide members horizontally mounted on left and right side plates (not shown). The carriage 101 has a droplet discharge head 1 that discharges ink droplets of yellow (Y), cyan (C), magenta (M), and black (Bk) in a plurality of ink discharge ports (nozzle holes). They are arranged in the sub-scanning direction orthogonal to the direction, and are mounted with the ink droplet ejection direction facing downward. In addition, each ink cartridge 102 for supplying ink of each color to the droplet discharge head 1 is replaceably mounted on the carriage 101.

  The ink cartridge 102 is provided with an atmosphere port communicating with the atmosphere above, and a supply port for supplying ink to the droplet discharge head 1 below. A porous body filled with ink is contained inside, and the ink supplied to the droplet discharge head 1 is maintained at a slight negative pressure by the capillary force of the porous body. Further, although the droplet discharge head is used for each color as the droplet discharge head 1, one droplet discharge head having nozzles for discharging ink droplets of each color may be used.

  Here, the carriage 101 is slidably fitted to the main guide rod 107 on the rear side (downstream side in the paper conveyance direction), and is slidably mounted on the secondary guide rod 108 on the front side (upstream side in the paper conveyance direction). doing. In order to move and scan the carriage 101 in the main scanning direction, a timing belt 112 is stretched between a driving pulley 110 and a driven pulley 111 that are rotationally driven by a main scanning motor 109a. The timing belt 112 is fixed to the carriage 101, and the carriage 101 is reciprocally scanned by forward and reverse rotation of the main scanning motor 109a.

  On the other hand, in order to convey the recording paper P set in the paper feeding cassette 104 to the lower side of the droplet discharge head 1, a paper feeding roller 113 and a friction pad 114 for separating and feeding the recording paper P from the paper feeding cassette 104, And a guide member 115 for guiding the recording paper P. Further, a conveyance roller 116 that reverses and conveys the fed recording paper P, a conveyance roller 117 that is pressed against the peripheral surface of the conveyance roller 116, and a leading end roller that defines a feeding angle of the recording paper P from the conveyance roller 116. 118. The conveyance roller 116 is rotationally driven via a gear train by the sub-scanning motor 109b.

  In addition, a printing receiving member 119 that is a paper guide member is provided to guide the recording paper P fed from the transport roller 116 below the droplet discharge head 1 in accordance with the moving range of the carriage 101 in the main scanning direction. ing. A conveyance roller 120 and a spur 121 that are rotationally driven to send the recording paper P in the paper discharge direction are provided on the downstream side of the printing receiving member 119 in the paper conveyance direction. Further, a paper discharge roller 123 for sending the recording paper P to the paper discharge tray 106, a spur 124, and guide members 125 and 126 for forming a paper discharge path are provided.

  When recording with the inkjet recording apparatus 100, the droplet discharge head 1 is driven in accordance with the image signal while moving the carriage 101, thereby discharging ink onto the stopped recording paper P to record one line. Thereafter, after the recording paper P is conveyed by a predetermined amount, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the recording paper P reaches the recording area, the recording operation is terminated and the recording paper P is discharged.

  A recovery device 127 for recovering the ejection failure of the droplet ejection head 1 is disposed at a position outside the recording area on the right end side in the movement direction of the carriage 101. Each of the recovery devices 127 includes a cap unit, a suction unit, and a cleaning unit (not shown). During printing standby, the carriage 101 is moved to the recovery device 127 side, and the droplet discharge head 1 is capped by the capping unit to keep the discharge port portion in a wet state, thereby preventing discharge failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ink ejection ports is made constant, and stable ejection performance is maintained.

  Further, when a discharge failure occurs, the ink discharge port of the droplet discharge head 1 is sealed with a capping unit, and bubbles and the like are sucked out from the discharge port with the suction unit through the tube. As a result, ink or dust adhering to the ink discharge port surface is removed by the cleaning means, and the discharge failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed at the lower part of the main body and absorbed and held by an ink absorber inside the waste ink reservoir.

  As described above, since the ink jet recording apparatus 100 includes the ink jet recording head having the actuator unit, stable ink droplet ejection characteristics can be obtained and the image quality can be improved.

  FIG. 3 is a schematic configuration diagram showing a configuration example of the droplet discharge unit 10 which is a basic component of the droplet discharge head according to the embodiment of the present invention. FIG. 4 is a cross-sectional view showing an example of the layer structure of the diaphragm and the piezoelectric element on the substrate. 5 and 6 are a detailed sectional view and a plan view of the periphery of the piezoelectric element 16, respectively. In FIG. 6, illustration of the first insulating protective film 17 and the second insulating protective film 22 is omitted, and the second insulating protective film is shown through a part of the members so that the configuration of the piezoelectric element can be understood. ing.

  In FIG. 3, the droplet discharge section 10 is a liquid chamber in which a nozzle plate 12 having a nozzle hole 11 for discharging a liquid droplet such as ink and a liquid chamber 13 communicating with the nozzle hole 11 and containing a liquid are formed. And a substrate (hereinafter simply referred to as “substrate”) 14. Further, a vibration plate 15 formed by a film forming method and a piezoelectric element 16 as an electromechanical conversion element for pressurizing the liquid in the liquid chamber 13 via the vibration plate 15 are provided on the substrate 14. ing. 3 and 4, the piezoelectric element 16 includes a common electrode 161 as a first drive electrode on the substrate 14 side, a piezoelectric film 162 made of PZT as an electromechanical conversion film, and a substrate of the piezoelectric film 162. An individual electrode 163 as a second drive electrode on the side opposite to the 14 side is laminated. As shown in FIGS. 5 and 6, the common electrode 161 is electrically connected to the electrode pad 18 as the first conductive member via the wiring 19 as the first wiring. The individual electrode 163 is connected to the electrode pad 20 as the second conductive member via the wiring 21 as the second wiring. In the droplet discharge unit 10 in FIG. 3, a drive voltage having a predetermined frequency and amplitude is applied between the common electrode 161 and the individual electrode 163 of the piezoelectric element 16. The piezoelectric element 16 to which the driving voltage is applied vibrates so as to deform the vibration plate 15 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 15. Thus, the droplets can be ejected from the nozzle holes 11.

  A wiring 19 and a wiring 21 are provided on the first insulating protective film 17 formed so that the first insulating protective film 17 covers the piezoelectric element 16. The common electrode 161 and the wiring 19 and the individual electrode 163 and the wiring 21 are electrically connected to each other through a contact hole 17 a in an opening formed in the first insulating protective film 17.

  Further, after the wiring 19 and the wiring 21 are formed, a second insulating protective film 22 is formed so as to cover the whole. The electrode pad 18 and the electrode pad 20 are electrically connected to the wiring 19 and the wiring 21 through contact holes in the openings formed in the second insulating protective film 22, respectively. With respect to the entire composite laminated substrate (hereinafter referred to as “actuator substrate”) including the substrate 14, the piezoelectric element 16, and various electrodes after the second insulating protective film 22 is formed, a gap is formed in the piezoelectric element 16. A sub-frame (not shown) as a structure provided so as to cover the piezoelectric element 16 in a non-contact state is joined. Electric charges generated by performing corona discharge or glow discharge on the piezoelectric element 16 manufactured as described above are supplied to the piezoelectric film 162 via the electrode pad 18 and the electrode pad 20, thereby polarizing the piezoelectric film 162. Processing is in progress. Specifically, corona discharge is performed by charge supply means (for example, a corona wire, a corona needle, etc.) that are opposed to the surfaces of the electrode pad 18 and the electrode pad 20 and are arranged with a gap therebetween. For example, when corona discharge is performed using a corona wire, cations are generated by ionizing molecules in the atmosphere, and the cations are supplied to the piezoelectric film 162 via the electrode pad 18 and the electrode pad 20. Thereby, the polarization process of the piezoelectric film is performed. In this polarization processing method, when the areas of the electrode pad 18 and the electrode pad 20 are the same, a certain amount of charge is generated in the individual electrode, whereas the common electrode having a smaller number of pads on the individual electrode side has individual charges. A charge having a value smaller than that of the charge at the electrode is generated. Therefore, a potential difference inside the piezoelectric film is generated by the charge difference between the individual electrode and the common electrode, and the polarization process is 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. 7A and 7B are characteristic diagrams showing measurement examples of the PE hysteresis loop characteristics of the piezoelectric elements before and after the polarization treatment, respectively. As shown in FIG. 7, the PE hysteresis loop characteristic is measured by applying 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. 7B, it is 5 [μC / cm ² ] or less. Is more preferable. 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. 7A, the displacement change after continuous driving as a piezoelectric actuator composed of a piezoelectric element. With respect to, sufficient characteristics cannot be obtained.

  FIG. 8 is a perspective view showing an example of the entire configuration of the polarization processing apparatus. As shown in the figure, the sample stage 201 is provided with a droplet discharge head including an electromechanical transducer to be polarized. The corona wire electrode 202 is connected to a corona power source 203 that supplies a voltage for corona discharge for polarization voltage. Between the sample stage 201 and the corona wire electrode 202, a grid electrode 204, which is a mesh electrode, is arranged, and a grid power source 205 for supplying a grid voltage is connected to the grid electrode 204. The moving direction of the sample stage 201, the corona wire electrode 202 and the grid electrode 204 is the same direction as shown by the arrows in FIG. Note that the sample stage 201, the corona wire electrode 202, or the grid electrode 204 may be rotated in different directions instead of the same direction. Accordingly, the relative position of the droplet discharge head on the sample stage 201 with respect to the corona wire electrode 202 or the grid electrode 204 can be freely changed.

  Here, as can be seen from FIG. 9 which is a characteristic diagram showing a change in polarization amount difference (Pr−Pini) with respect to a horizontal distance orthogonal to the wire axis direction of the corona wire, a uniform desired charge amount per unit area is obtained. There is a range of horizontal distance that can be charged. A region including this range is referred to as a charge supply region. As can be seen from FIG. 9, when the distance from the corona wire electrode fixed at a predetermined position, that is, from the time when the horizontal distance between the electrode pad and the corona wire electrode is gradually increased, the difference in polarization (Pr−Pini) is obtained. It can be seen that gradually increases and the polarization state deteriorates. Therefore, in this embodiment, as will be described later, two electrode pads 18 and 21 for supplying charges are positioned in the charge supply region as shown in FIG. 10 which is a schematic side view of FIG. Processing is in progress.

  Here, in FIG. 10, for example, when corona discharge is performed using the corona wire electrode 202, molecules in the atmosphere are ionized to generate cations and anions. Among the generated ions, cations are accumulated in the piezoelectric film 162. Due to the charge difference between the common electrode 161 and the individual electrode 163, a potential difference is generated inside the piezoelectric film 162, and the piezoelectric film 162 is polarized. In FIG. 10, a grid electrode 204 is provided in the gap between the corona wire electrode 202 and the electrode pad 20 of the piezoelectric element, and the charge supply region on the piezoelectric element 16 side is controlled by moving the grid electrode 204 in three dimensions. . Here, in view of the charge amount Q required for the polarization treatment, it is preferable that a charge amount of 1E-8C or more is accumulated, and it is more preferable that a charge amount of 4E-8C or more is accumulated. When the value is less than this value, the polarization process cannot be sufficiently performed, and sufficient characteristics cannot be obtained with respect to the displacement deterioration after continuous driving as a piezoelectric actuator of PZT. Moreover, when performing a polarization process, it is also possible to carry out heating as a countermeasure against cracks. In particular, when the electromechanical conversion film is constrained with respect to the substrate, even if the film itself tries to be distorted by the electric field generated during the polarization process, the film cannot be freely deformed due to the restraining force. This is because when the polarization treatment is performed while heating, the treatment can be performed while relaxing the stress of the electromechanical conversion film, so that cracks do not occur even if a desired polarization amount difference is obtained.

  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 in FIG. 3, 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. 3 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, a structure having an inclination of about 54 ° can be produced in the plane orientation (100), whereas a deep groove can be dug in the plane orientation (110), 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. 3, the vibration plate 15 is deformed by the force generated by the piezoelectric element 16 as an electromechanical conversion element, and liquid droplets such as ink in the liquid chamber (pressure chamber) 13 are ejected. 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 and the} like by, for example, a CVD (Chemical Vapor Deposition) 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 of is preferable. Furthermore, a material having a linear expansion coefficient in the range of 7 × 10 ⁻⁶ (1 / K) to 9 × 10 ⁻⁶ (1 / K) is more preferable. 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) plane orientation in accordance with the (111) plane orientation of the Pt of the first drive electrode with particular emphasis on the crystal orientation, the film formation temperature is 500 [ It is preferable to form a film by heating the substrate at a temperature of [° C.] or higher. For example, regarding the SRO film formation conditions described in Patent Document 2, after film formation at room temperature, thermal acidification is performed at a crystallization temperature (650 ° C.) by RTA treatment. In this case, the SRO film is sufficiently crystallized and a sufficient value is obtained as a specific resistance as an electrode. However, as the crystal orientation of the film, the (110) plane orientation is likely to be preferentially oriented. Also, the PZT formed in the film is easily oriented in the (110) plane orientation.

Here, for example, when a platinum film oriented in the (111) plane direction is used as a metal electrode film, and an SrRuO ₃ film as an oxide electrode film is formed thereon, the crystallinity of the oxide electrode is measured by X-ray diffraction measurement. The method of evaluation will be described.

Since Pt and SrRuO ₃ have close lattice constants, in the θ-2θ measurement in the normal X-ray diffraction measurement, the 2θ positions of the (111) plane of the SRO film and the (111) plane of Pt overlap and are difficult to discriminate. However, when Pt is tilted to Psi = 35 [°] due to the extinction law, the diffraction lines cancel each other at a position where 2θ is about 32 [°], and the diffraction intensity of Pt cannot be seen. Therefore, it is possible to confirm whether the SRO is preferentially oriented in the (111) plane orientation by inclining the Psi direction by about 35 [°] and judging from the peak intensity where 2θ is about 32 [°].

In FIG. 11, after forming a titanium oxide film as an adhesion layer on a silicon substrate, a platinum film oriented in the (111) plane orientation is formed, and the substrate is heated to, for example, 550 [° C.]. The X-ray diffraction measurement result of the sample on which the SrRuO ₃ film is formed by sputtering is shown.

  FIG. 11 shows data when 2θ = 32 [°] is fixed and Psi is changed. When Psi = 0 [°], almost no diffraction intensity is observed in the diffraction line on the (110) plane of SRO, and the diffraction intensity is observed in the vicinity of Psi = 35 [°]. ) It can be confirmed that the preferred orientation is in the plane orientation. In addition, from this result, it was confirmed that SRO was preferentially oriented in the (111) plane direction for those produced under the present film forming conditions.

  Further, when the SRO film formed by performing the RTA treatment after forming the SRO film described above at room temperature was similarly evaluated, the (110) plane in the SRO was obtained when Psi = 0 [°]. Directional diffraction intensity was observed.

  When it was estimated how much the displacement after driving was deteriorated compared to the initial displacement when continuously operating as a piezoelectric actuator, the orientation of the electromechanical conversion film (for example, PZT) greatly affected. The (110) plane orientation may be insufficient in suppressing displacement degradation. For this reason, as described above, the oxide electrode film is preferably oriented in the (111) plane orientation.

The surface roughness of the SrRuO ₃ film used for the oxide electrode is preferably 4 [nm] or more and 15 [nm] or less, and more preferably 6 [nm] or more and 10 [nm] or less. In addition, about the surface roughness here, the surface roughness (average roughness) measured by AFM is meant.

The surface roughness of the SrRuO ₃ film affects the film formation temperature, and when the substrate is heated from room temperature to 300 [° C.], the surface roughness is very small and becomes 2 [nm] or less. In this case, the surface roughness is very small and flat, but the crystallinity of the SrRuO ₃ film may not be sufficient. Thus, when the crystallinity of the SrRuO ₃ film is not sufficient, sufficient characteristics can be obtained with respect to the initial displacement as the piezoelectric actuator of the electromechanical conversion film (for example, PZT film) to be formed thereafter and the deterioration of the displacement after continuous driving. Disappear. 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. .

[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 (PbZrO ₃₎ and lead 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. Specifically, (Pb1-x, Ba) (Zr, Ti) O ₃ , (Pb1-x, Sr) (Zr, Ti) O ₃ , which partially replaces Pb of the A site with Ba or Sr. This 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 film thickness range, sufficient deformation (displacement) cannot be generated. If it is larger than this film thickness range, many layers are stacked, so that the number of steps increases and the process time becomes longer. 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 is larger than this range, polarization processing is not performed sufficiently, and sufficient characteristics are obtained for displacement deterioration after continuous driving. The trouble that it is not possible 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 of 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 for 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 ejecting droplets. On the other hand, if 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 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 17 needs to be a dense inorganic material. is there. Further, when an organic material is used as the first insulating protective film 17, it is not suitable because it is necessary to increase the film thickness in order to obtain sufficient protection performance. When the first insulating protective film 17 is a thick film, the vibration of the diaphragm 15 is remarkably hindered, resulting in a droplet discharge head having a low discharge performance. In order to obtain high protection performance with a thin film, it is preferable to use an oxide, nitride, or carbide film, but it has high adhesion to the electrode material, piezoelectric material, and diaphragm material that are the base of the first insulating protective film 17. It is necessary to select materials. In addition, it is necessary to select a film forming method that does not damage the piezoelectric element 16 as a film forming method for the first insulating protective film 17. 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 17 include a vapor deposition method and an ALD method, but an ALD method with a wide choice of usable materials is preferable. Preferable materials include oxide films used for ceramic materials such as Al ₂ O ₃ , ZrO ₂ , Y ₂ O ₃ , Ta ₂ O ₃ , and TiO ₂ . 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 17 needs to be a thin film enough to ensure the protection performance of the piezoelectric element 16 and at the same time needs to be as thin as possible so as not to inhibit the deformation (displacement) of the diaphragm 15. There is. The film thickness of the first insulating protective film 17 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 17 has two layers is also conceivable. In this case, since the second insulating protective film is thickened, the second insulating protective film is opened in the vicinity of the individual electrode (second drive electrode) 163 so as not to significantly inhibit the vibration of the diaphragm 15. A configuration is also 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 17, 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 (first drive electrode) 161 and the wiring 21 of the individual electrode 163. That is, it is necessary to set the electric field strength applied to the first insulating protective film 17 within a range that does not cause dielectric breakdown. Furthermore, in consideration of the surface property of the base of the first insulating protective film 17 and pinholes, the film thickness of the first insulating protective film 17 needs to be 200 [nm] or more, more preferably 500 [nm] or more. .

[Wiring, electrode pads]
The material of the wirings 19 and 21 and the electrode pads 18 and 20 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 the thickness is smaller than this range, the resistance increases, and a sufficient current cannot flow through the electrodes, making the head ejection unstable. On the other hand, if it is larger than this film thickness range, the process time becomes longer. The contact resistance in the contact hole 17b (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 this range is exceeded, it will not be possible to supply a sufficient current, causing problems when discharging droplets.

[Second insulating protective film]
The function as the second insulating protective film 22 is a passivation layer having a function as a protective layer for the common electrode wiring 19 and the individual electrode wiring 21. As shown in FIGS. 5 and 6 described above, the common electrode 161 and the individual electrode 163 are covered except for the lead portion (contact hole 17a) of the common electrode 161 and the individual electrode 163. 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 the material of the second insulating protective film 22, 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 17 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 second insulating protective film 22, the photolithography method and dry etching can be used to form the opening of the second insulating protective film 22. The area of the electrode pads 18 and 20 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 polarization processing using discharge in the method for manufacturing a droplet discharge head according to the present embodiment will be described.

  Hereinafter, an example of a specific method for manufacturing the electromechanical transducer will be described. However, the present invention is not limited to this example.

  First, a thermal oxide film (film thickness: 1 [μm]) was formed on a 6-inch silicon wafer.

Next, a first drive electrode was formed. Specifically, first, as an adhesion film, a titanium film (film thickness: 30 [nm]) was formed by a sputtering apparatus, and then thermally oxidized at 750 [° C.] using RTA. Subsequently, a platinum film (film thickness 100 [nm]) was formed as a metal film, and an SrRuO ₃ film (film thickness 60 [nm]) was formed as an oxide film by sputtering. Film formation was performed at a substrate heating temperature of 550 [° C.] during the sputtering film formation.

  Next, an electromechanical conversion film was formed. Specifically, a solution having a molar ratio of 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 normal propoxide 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 normal propoxide 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 in the synthesized PZT precursor solution was 0.5 [mol / L].

  Using the precursor solution, a film is formed on the substrate on which the first driving electrode is formed by spin coating, and after the film formation, drying is performed by heating at 120 [° C.], followed by further thermal decomposition at 500 [° C.]. The operation to be performed was repeated a plurality of times to laminate the electromechanical conversion film.

  When the electromechanical conversion film was laminated by repeating the above procedure, a crystallization heat treatment (temperature 750 [° C.]) was performed by RTA (rapid heat treatment) after the third thermal decomposition treatment. After the thermal decomposition treatment of the third layer, the film thickness of the electromechanical conversion film (PZT) subjected to RTA treatment was 240 [nm].

  The above process was performed a total of 8 times (24 layers) to obtain an electromechanical conversion film having a PZT film thickness of about 2 [μm].

Next, an SrRuO ₃ film (film thickness 40 [nm]) was formed by sputtering as the oxide film of the second drive electrode, and a Pt film (film thickness 125 [nm]) was formed by sputtering as the metal film.

  Thereafter, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. was formed by spin coating, and a resist pattern was formed by ordinary photolithography. Thereafter, the electromechanical conversion film and the second drive electrode were individually separated by etching using an ICP etching apparatus (manufactured by Samco), and a pattern as shown in FIGS. 5 and 6 was produced. Accordingly, the second drive electrode functions as an individual electrode, and the first drive electrode functions as a common electrode for the individualized electromechanical conversion film and the second drive electrode.

Next, as the first insulating protective film 17, an Al ₂ O ₃ film having a thickness of 50 [nm] was formed by the ALD method.

As raw materials, trimethylaluminum (TMA) (manufactured by Sigma-Aldrich) was used as the Al source, and O ₃ generated by an ozone generator was used as the O source. Then, an Al source and an O source were alternately supplied onto the substrate and laminated to form a film.

  Thereafter, as shown in FIG. 5, a contact hole 17b was formed by etching.

  Then, Al was sputtered as two electrode pads of the first wiring, the second wiring, the first conductive member, and the second conductive member, and was patterned by etching.

Further, after that, Si ₃ N ₄ was deposited to a thickness of 500 [nm] by plasma CVD as the second insulating protective film 22 to produce a piezoelectric element (electromechanical conversion element) 16.

  With respect to the actuator substrate (not shown) including the piezoelectric element (electromechanical conversion element) manufactured as described above, an opening (not shown) forming a part of the common liquid chamber and a piezoelectric element driving IC (not shown) A sub-frame (not shown) provided with an opening (not shown) or the like for arranging the film was adhesively bonded. The subframe was fabricated using a silicon wafer, and a thermal oxide film was formed on the surface of the subframe.

  Next, examples and comparative examples of polarization processing using corona discharge in the manufacturing method of the droplet discharge head of this embodiment will be described.

  Fig.12 (a) is a top view which shows Example 1 of a polarization process, FIG.12 (b) is a schematic side view. In this embodiment, as shown in FIG. 12, a plurality (two in the first embodiment) of electrode pads 18 of the first conductive member are arranged in a row, and a plurality of (five in the first embodiment) second pads. This is an example in which electrode pads 20 of conductive members are arranged in a row. In each electrode pad row, the electrode pads are arranged such that the row width W1 of each electrode pad 18 and the row width W2 of each electrode pad 20 overlap at least partially. The row directions of the rows are preferably parallel to each other, but it is not necessary to limit to this. The number of the electrode pads 18 and the electrode pads 20 may be one. In this case, the area of the electrode pad 18 is smaller than that of the electrode pad 20, and when viewed from an arbitrary direction in the mutual positional relationship. It is only necessary that the electrode pads overlap each other. At such electrode pad positions, the relative positions of the droplet discharge head and the charge supply means such as the corona wire are adjusted so that the electrode pads are located in the charge supply region described above. Thus, when corona discharge is performed on the charge supply region, charges are supplied to the electrode pad 18 and the electrode pad 20 substantially uniformly. Therefore, a desired difference is generated in the amount of charge supplied between the individual electrode and the common electrode due to the difference between the area of the electrode pad 18 and the area of the electrode pad 20. A desired polarization process can be performed on the electromechanical transducer, and a desired polarization characteristic of the electromechanical transducer can be obtained.

  Fig.13 (a) is a top view which shows Example 2 of a polarization process, FIG.13 (b) is a schematic side view. In this embodiment, as compared with the first embodiment, the column width W1 of each electrode pad 18 and the column width W2 of each electrode pad 20 are included in at least one column width so that the electrode pads completely overlap each other. Is arranged. Therefore, a desired difference is generated in the amount of charge supplied between the individual electrode and the common electrode due to the difference between the area of the electrode pad 18 and the area of the electrode pad 20. The desired polarization treatment for the electromechanical transducer can be performed without any loss, and the desired polarization characteristics of the electromechanical transducer can be obtained.

  FIG. 14A is a plan view showing a comparative example of separation processing, and FIG. 14B is a schematic side view. The comparative example shown in FIG. 14 shows an example in which the electrode pad 18 and the electrode pad 20 are greatly separated and the two electrode pads cannot be positioned in the charge supply region. In this comparative example, discharge is performed when the corona wire electrode 202 moves to the upper portion of the electrode pad 18, and discharge is performed again by moving the corona wire electrode 202 to the upper portion of the electrode pad 20.

  Polarization experiments were conducted on the above Example 1, Example 2 and Comparative Example, respectively, and the experimental results are shown in Table 1 below. As a configuration of the polarization processing apparatus, a scorotron method is adopted, and a voltage of 8 [kV] is applied to a φ50 [μm] tungsten wire and a voltage of 2.5 [kv] is applied to a grid electrode for 30 seconds. Went. The evaluation item is about polarization amount difference (Pr-Pini). In Example 1, it turns out that the polarization difference is small. This is because each of the electrode pad rows can be easily disposed almost directly below the corona wire electrode, and each electrode pad is positioned at least partially in the charge supply region, so that a substantially desired polarization process can be performed. . Further, in Example 2, since the pad rows completely overlap, both electrode pad rows can be arranged more strictly below the corona wire electrode 204, and each electrode pad is in the charge supply region with each other, and This is because it was perfectly positioned and there was no loss of polarization treatment. On the other hand, in the comparative example, the charge previously discharged and supplied to the electrode pad 18 leaks into the atmosphere while the corona wire electrode 204 is moved to the position of the electrode pad 20, and the following Table 1 As shown in FIG. 5, the difference in polarization amount was increased, and the desired polarization process could not be performed.

  In the present embodiment, the liquid droplet ejection head including one nozzle hole has been described. However, the present invention is not limited to this embodiment, and a configuration including a plurality of liquid droplet ejection heads as shown in FIG. You can also. In FIG. 15, a plurality of droplet discharge heads of FIG. 3 are arranged in series, and the same members are denoted by the same numbers. Moreover, although description about a liquid supply means, a flow path, fluid resistance, etc. was abbreviate | omitted, the incidental equipment which can be provided in a droplet discharge head can be provided naturally. Using the electromechanical transducers prepared in Examples 1 and 2 above, a droplet discharge head was prepared and liquid discharge was evaluated. Using ink with viscosity adjusted to 5 [cp] and applying a simple Pull waveform voltage with an intermediate potential of 10 to 30 [V] and confirming the discharge status from the nozzle holes, all the nozzle holes also It was confirmed that discharge was possible.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect 1)
In a method for manufacturing an electromechanical transducer having a structure in which a first drive electrode such as a common electrode 161, an electromechanical conversion film such as a piezoelectric film 162, and a second drive electrode such as an individual electrode 163 are stacked on a substrate 14. Forming a first drive electrode on the substrate, forming an electromechanical conversion film on the first drive electrode, forming a second drive electrode on the electromechanical conversion film, Forming a first insulating protective film 17 on the driving electrode and the second driving electrode; forming a first terminal electrode for external connection and a second terminal electrode for external connection on the first insulating protective film; Forming a first wiring such as a wiring 19 and a second wiring such as a wiring 21 electrically connected to each of the first driving electrode and the second driving electrode on the first insulating protective film; and a first terminal electrode And opening of the contact hole 17b etc. through which the second terminal electrode is exposed. A step of forming a second insulating protective film on the electromechanical conversion film, the first wiring, and the second wiring, a first contact portion corresponding to each position of the first terminal electrode and the second terminal electrode, and A first conductive member such as an electrode pad 18 having a second contact portion and a second conductive member such as an electrode pad 20 are brought into contact with the first terminal electrode and the second terminal electrode, thereby the first conductive member and the second conductive member. And supplying a charge generated by corona discharge or glow discharge to the conductive member to polarize the electromechanical conversion film. In the polarization process, the charge generated by corona discharge or glow discharge is generated. A first conductive member and a second conductive member are simultaneously positioned in a charge supply region supplied with a uniform charge amount per unit area, and corona discharge is applied to the first conductive member and the second conductive member. Or generated by glow discharge Charge supplying the, the electromechanical conversion film to polarization treatment.
According to this, as described in the above embodiment, the first conductive member and the second conductive member are simultaneously positioned in the charge supply region, and charges are generated by corona discharge or glow discharge. The charge is supplied uniformly to the charge supply region per unit area. As a result, uniform charges per unit area are supplied to the first conductive member and the second conductive member. For example, if there is a predetermined difference between the area of the first conductive member and the area of the second conductive member, there is a predetermined difference between the charge amount of the first drive electrode and the charge amount of the second drive electrode. The difference occurs. If the distance between the first drive electrode and the second drive electrode and the difference in area between the first drive electrode and the second drive electrode are substantially the same in any of the electromechanical conversion elements, the first drive A potential difference between the first drive electrode and the second drive electrode is generated due to a difference in charge amount between the electrode and the second drive electrode. Polarization processing is performed by this potential difference. Since the amount of charge supplied to the first drive electrode and the second drive electrode is substantially the same between the electromechanical conversion elements, the potential difference between the first drive electrode and the second drive electrode is also substantially the same between the electromechanical conversion elements. . Therefore, it is possible to reduce variation in polarization characteristics between manufactured electromechanical transducers.
(Aspect 2)
In (Aspect 1), the second conductive members such as the plurality of electrode pads 20 are arranged in a row, and the row width of the second conductive member perpendicular to the row direction of the second conductive member is set in the row direction. The widths of the first conductive members such as one electrode pad 18 orthogonal to each other overlap in the column direction.
According to this, as described in Example 1 of the above embodiment, at least a part of each of the plurality of second conductive members and one first conductive member is positioned in the charge supply region, Perform corona discharge or glow discharge. A uniform charge per unit area is supplied to the first conductive member and each second conductive member. In the polarization processing step, since a predetermined difference can be generated between the charge amount of the first drive electrode and the charge amount of the second drive electrode, a predetermined potential difference is generated inside the electromechanical conversion film, and the desired polarization process Is done. Therefore, it is possible to reduce variation in polarization characteristics between manufactured electromechanical transducers.
(Aspect 3)
In (Aspect 2), either the column width in the direction orthogonal to the column direction of the second conductive member or the width of the first conductive member is included in the other.
According to this, as described in Example 2 of the above embodiment, the plurality of second conductive members and one first conductive member are completely arranged in the charge supply region immediately below the corona wire electrode. The polarization process can be performed without loss.
(Aspect 4)
In (Aspect 1), a plurality of first conductive members are arranged in a row, and a plurality of second conductive members are arranged in a row. The row direction of the first conductive members and the second conductive members The column width of the first conductive member orthogonal to the column direction of the first conductive member is equal to the column width of the second conductive member orthogonal to the column direction of the second conductive member. , Overlapping in the column direction.
According to this, as described in Example 1 of the above embodiment, at least a part of each of the plurality of second conductive members and the plurality of first conductive members is positioned in the charge supply region, Perform corona discharge or glow discharge. A uniform charge per unit area is supplied to each first conductive member and each second conductive member. In the polarization processing step, since a predetermined difference can be generated between the charge amount of the first drive electrode and the charge amount of the second drive electrode, a predetermined potential difference is generated inside the electromechanical conversion film, and a desired polarization process is performed. Is done. Therefore, it is possible to reduce variation in polarization characteristics between manufactured electromechanical transducers.
(Aspect 5)
In (Aspect 4), either the column width in the direction orthogonal to the column direction of the second conductive member or the column width in the direction orthogonal to the column direction of the first conductive member is included in the other. It is.
According to this, as described in Example 2 of the above embodiment, the plurality of second conductive members and the plurality of first conductive members are completely arranged in the charge supply region immediately below the corona wire electrode. The polarization process can be performed without loss.
(Aspect 6)
(Embodiment 1) An electromechanical exchange element obtained by the method of manufacturing an electromechanical exchange element according to any one of (Embodiment 5), wherein the electromechanical conversion film has an electric field strength of ± 150 [kV / cm]. When measuring the hysteresis loop, the polarization at 0 [kV / cm] at the start of measurement is Pini, and after applying a voltage of +150 [kV / cm], 0 [kV / cm] when returning to 0 [kV / cm] / Cm], when the polarization is Pr, the difference between Pr and Pini is 10 [μC / cm ² ] or less.
According to this, as described in the above embodiment, when the difference between Pr and Pini is larger than 10 [μC / cm ² ], when the electromechanical conversion film is used as a piezoelectric actuator, the displacement deterioration after continuous driving is achieved. This is because sufficient characteristics may not be obtained. In this aspect, since the difference between Pr and Pini is 10 [μC / cm ² ] or less, when the electromechanical conversion film is used as a piezoelectric actuator, sufficient characteristics can be obtained with respect to displacement deterioration after continuous driving.
(Aspect 7)
In a droplet discharge head including a nozzle hole for discharging a droplet, a pressurizing chamber that communicates with the nozzle hole, and a discharge driving unit that pressurizes the liquid in the pressurizing chamber, A part of the wall is configured by a diaphragm, and the diaphragm is provided with the electromechanical conversion element of (Aspect 6).
According to this, since the electromechanical conversion element of aspect 6 is provided as described in the above embodiment, the electromechanical conversion element is sufficiently subjected to polarization processing in advance and has a low polarization amount difference. Yes. For this reason, the electromechanical conversion element is stably deformed with respect to a predetermined potential, and as a result, the droplet discharge head can also perform stable droplet discharge.
(Aspect 8)
The liquid droplet ejection head of (Aspect 7) was provided. According to this, since the liquid droplet ejection head according to aspect 7 is provided as described in the above embodiment, the electromechanical conversion element included in the liquid droplet ejection head is sufficiently polarized in advance. The electromechanical transducer has a low polarization difference. For this reason, the electromechanical transducer is stably deformed with respect to a predetermined potential, and as a result, the droplet discharge device can also stably discharge droplets.
(Aspect 9)
An image is formed by discharging a recording liquid onto a recording material with the droplet discharge head of (Aspect 7). According to this, since the liquid droplet ejection head according to aspect 7 is provided as described in the above embodiment, the electromechanical conversion element included in the liquid droplet ejection head is sufficiently polarized in advance. The electromechanical transducer has a low polarization difference. For this reason, the electromechanical conversion element is stably deformed with respect to a predetermined potential, and as a result, the image forming apparatus can also stably discharge droplets. Therefore, a high-quality image can be formed.

DESCRIPTION OF SYMBOLS 10 Droplet discharge part 11 Nozzle hole 12 Nozzle plate 13 Liquid chamber 14 Liquid chamber substrate 15 Vibrating plate 16 Piezoelectric element 17 First insulating protective film 17a Contact hole 18 Electrode pad 19 Wiring 20 Electrode pad 21 Wiring 22 Second insulating protective film 100 Inkjet recording apparatus 161 Common electrode 162 Piezoelectric film 163 Individual electrode 201 Sample stage 202 Corona wire electrode 203 Corona power supply 204 Grid electrode 205 Grid power supply

Japanese Patent No. 4927400 Japanese Patent No. 3784401

Claims (7)

A nozzle for discharging liquid droplets, a liquid chamber communicating with the nozzle, a diaphragm constituting a part of a wall of the liquid chamber, a common electrode, a piezoelectric body, and an individual electrode provided on the diaphragm. A droplet discharge head comprising: a plurality of stacked piezoelectric elements; a common electrode pad that is in electrical communication with the common electrode; and a plurality of individual electrode pads that are in electrical communication with the individual electrode. ,
The plurality of individual electrode pads are arranged in a row,
When viewed from the arrangement direction of the individual electrode pads, at least a part of the common electrode pad is disposed so as to overlap the individual electrode pads,
When a hysteresis loop is measured by applying an electric field strength of ± 150 [kV / cm] to the piezoelectric body, the polarization at 0 [kV / cm] at the start of measurement is Pini, and a voltage of +150 [kV / cm] After application, when the polarization at 0 [kV / cm] when returning to 0 [kV / cm] is Pr, the difference between Pr and Pini is 10 [μC / cm ² A droplet discharge head characterized by the following. The droplet discharge head according to claim 1.
The difference between Pr and Pini is 5 [μC / cm ² A droplet discharge head characterized by the following. The droplet discharge head according to claim 1 or 2,
The liquid droplet ejection head, wherein one of the common electrode pad and the individual electrode pad is included in the other when viewed from the arrangement direction of the individual electrode pads. In the liquid droplet ejection head according to any one of claims 1 to 3,
The area of the individual electrode pad and the area of the common electrode pad are both 2500 [μm. ² ] A liquid droplet ejection head characterized by the above. In the droplet discharge head according to any one of claims 1 to 4,
A droplet discharge head, wherein the area of the individual electrode pad and the area of the common electrode pad are different. Droplet discharge apparatus comprising the droplet discharging head according to any one of 請 Motomeko 1-5. An image forming apparatus comprising the droplet discharging head according to claim 1.

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