JP6915327B2 - Liquid discharge head, manufacturing method of liquid discharge head, liquid discharge unit, and device for discharging liquid - Google Patents

Description

The present invention relates to a liquid discharge head, a method for manufacturing a liquid discharge head, a liquid discharge unit, and a device for discharging a liquid.

Regarding a liquid discharge head used in a printer, a facsimile, a copying device, etc., it has a nozzle for discharging liquid, a pressure chamber through which the nozzle communicates, and an electromechanical conversion element such as a piezoelectric element for pressurizing the liquid in the pressure chamber. Things are known. Further, two types of liquid discharge heads have been put into practical use, one using an actuator in a longitudinal vibration mode and one using an actuator in a flexural vibration mode.

As a method using the deflection vibration mode, for example, a uniform piezoelectric material layer is formed over the entire surface of the diaphragm by a film forming technique, and this piezoelectric material layer is cut into a shape corresponding to a pressure chamber by a lithography method. It is known that an electromechanical conversion element is formed independently in each pressure chamber.

It is known that such an electromechanical conversion element is subjected to a polarization treatment. That is, the piezoelectric crystal contained in the electromechanical conversion film forming the electromechanical conversion element has a random polarization direction, but by performing a polarization process in which voltage application is repeated, the polarization directions are aligned and electricity is obtained. It suppresses displacement deterioration after continuous driving of the mechanical conversion element.

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

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

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

However, if the polarization of the dummy electromechanical conversion element advances too much, the deflection of the diaphragm at that portion affects the degree of deflection of the diaphragm at the position of the electromechanical conversion element of the drive channel on the end side. It turned out that it would end up. In this way, if the degree of bending of the diaphragm varies between the electromechanical conversion elements, the discharge performance of the liquid discharge head will be affected.

Therefore, an object of the present invention is to provide a liquid discharge head capable of suppressing the occurrence of variation in the degree of bending of the diaphragm between electromechanical conversion elements and obtaining good discharge performance.

In order to achieve such an object, the liquid discharge head according to the present invention is formed with a plurality of nozzles for discharging liquid and a plurality of pressure chambers for liquid discharge communicating with the nozzles arranged side by side in a predetermined direction. A pressure chamber forming substrate on which at least one dummy pressure chamber is formed arranged on the end side of the pressure chamber in the direction, and a part thereof provided on one surface of the pressure chamber forming substrate, the pressure chamber and the said. A vibrating plate layer forming the wall surface of the dummy pressure chamber, an electromechanical conversion element provided on the vibrating plate layer corresponding to each pressure chamber, and an electromechanical conversion element provided on the vibrating plate layer corresponding to each dummy pressure chamber. A dummy electromechanical conversion element, an electrode pad electrically connected to the electromechanical conversion element, a dummy electrode pad electrically connected to the dummy electromechanical conversion element, and at least the end of the dummy electrode pad. The dummy electrode pad located in the portion is provided with a wiring formed so as to face at least a part thereof and a discharge control means for controlling the discharge of liquid from the nozzle. The dummy electrode pad is electrically joined to the discharge control means, and the dummy electrode pad is not electrically joined to the discharge control means .

According to the present invention, it is possible to suppress the occurrence of variation in the degree of bending of the diaphragm between the electromechanical conversion elements and obtain good discharge performance.

It is sectional drawing which illustrates the liquid discharge head. It is sectional drawing which illustrates the manufacturing process of a liquid discharge head. It is sectional drawing which illustrates the liquid discharge head. It is a figure which illustrates the wiring and the like of a liquid discharge head. It is a figure explaining the bending of a diaphragm. It is a figure explaining the definition of the bending amount of a diaphragm. It is a figure which illustrates the schematic structure of the polarization processing apparatus. It is a figure explaining the corona discharge. It is a figure which illustrates the PE hysteresis loop. It is a top view which illustrates the liquid discharge head. It is a top view which illustrates the liquid discharge head. It is a top view which illustrates the liquid discharge head. It is a top view (1) which illustrates the liquid discharge head which concerns on 1st Embodiment. (A) is a cross-sectional view taken along the dotted line portion of FIG. 13, and (b) is a cross-sectional view taken along the alternate long and short dash line portion of FIG. It is a top view (2) which illustrates the liquid discharge head which concerns on 1st Embodiment. It is a top view which illustrates the liquid discharge head which concerns on 2nd Embodiment. It is a top view which illustrates the liquid discharge head which concerns on 3rd Embodiment. It is a top view which illustrates the liquid discharge head which shows the state connected with the drive IC. It is a plane explanatory view of the main part of an example of the apparatus which discharges a liquid. It is a side explanatory view of the main part of an example of a device which discharges a liquid. It is a plane explanatory view of the main part of another example of a liquid discharge unit. It is a front explanatory view of another example of a liquid discharge unit. It is a figure explaining the holding substrate.

Hereinafter, the configuration according to the present invention will be described in detail based on the embodiments shown in FIGS. 1 to 23.

(Liquid discharge head)
[First Embodiment]
<Construction of liquid discharge head>
FIG. 1 is a cross-sectional view of the liquid discharge head 1 showing an embodiment of the liquid discharge head. The liquid discharge head 1 includes a substrate 10, a diaphragm 20, an electromechanical conversion element 30, and an insulating protective film 40. Further, the electromechanical conversion element 30 has a lower electrode 31, an electromechanical conversion film 32, and an upper electrode 33.

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

A nozzle plate 50 provided with a nozzle 51 for ejecting ink droplets is joined to the lower portion of the substrate 10. A pressure chamber 10x (sometimes referred to as an ink flow path, a pressurized liquid chamber, a pressurized chamber, a discharge chamber, a liquid chamber, etc.) communicating with the nozzle 51 is provided by the nozzle plate 50, the substrate 10, and the diaphragm 20. It is formed. The diaphragm 20 forms a part of the wall surface of the ink flow path. In other words, the pressure chamber 10x is partitioned by the substrate 10 (constituting the side surface), the nozzle plate 50 (constituting the lower surface), and the diaphragm 20 (constituting the upper surface), and communicates with the nozzle 51.

In order to manufacture the liquid discharge head 1, first, as shown in FIG. 2, the diaphragm 20, the lower electrode 31, the electromechanical conversion film 32, and the upper electrode 33 are sequentially laminated on the substrate 10. After that, the lower electrode 31, the electromechanical conversion film 32, and the upper electrode 33 are etched into a desired shape and coated with the insulating protective film 40. Then, an opening is formed in the insulating protective film 40 to selectively expose the lower electrode 31 and the upper electrode 33. Then, the substrate 10 is etched from below to prepare a pressure chamber 10x. Next, the nozzle plate 50 having the nozzle 51 is joined to the lower surface of the substrate 10, and the liquid discharge head 1 is completed.

Although only one liquid discharge head 1 is shown in FIG. 1, in reality, as shown in FIG. 3, a liquid discharge head 2 in which a plurality of liquid discharge heads 1 are arranged in a predetermined direction is manufactured. The liquid discharge head 2 has a structure (liquid discharge head 1) including a nozzle 51 for discharging liquid, a pressure chamber 10x with which the nozzle 51 communicates, and a discharge driving means for boosting the liquid in the pressure chamber 10x. It is a structure in which a plurality of pieces are arranged in a predetermined direction. Here, the discharge driving means can be configured to include a diaphragm 20 forming a part of the wall of the pressure chamber 10x and an electromechanical conversion element 30 provided with an electromechanical conversion film 32.

In the liquid discharge head 2, the portion of the structure (dummy pressure chamber, vibrating plate 20, electromechanical conversion element 30) that does not discharge the liquid is called a dummy channel 4 (dummy ch), whereas the liquid is discharged. In the head 2, the portion of the structure (pressure chamber 10x, vibrating plate 20, electromechanical conversion element 30) that discharges the liquid is referred to as a drive channel 3 (drive ch).

Next, the configuration of the liquid discharge head 2 including the wiring and the like will be described. 4A and 4B are views illustrating the wiring and the like of the liquid discharge head 2, FIG. 4A is a cross-sectional view, and FIG. 4B is a plan view. In addition, in FIG. 4B, the illustration of the insulating protective film 40 and 70 is omitted.

In the example of FIG. 4, the insulating protective film 40 is composed of two layers (insulating protective films 40a and 40b). A plurality of wirings 60 are provided on the second layer of the insulating protective film 40b, and an insulating protective film 70 is further provided on the wiring 60. The insulating protective film 40 includes a plurality of openings 40x, and the surface of the lower electrode 31 or the upper electrode 33 is exposed in the openings 40x. The wiring 60 is connected to the upper electrode 33 by filling the opening 40x (the portion of the contact hole H in FIG. 4B) and is connected to the lower electrode 31 by filling the opening 40x. Includes wiring.

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

<Deviation (curvature) of diaphragm>
By the way, in the step of manufacturing the liquid discharge head 2, when the pressure chamber 10x is manufactured, the diaphragm 20 bends (curves) so as to be convex toward the pressure chamber 10x, as shown in FIG. Therefore, the diaphragm 20 is formed in a state of being bent convexly toward the pressure chamber 10x side. The amount of deflection of the diaphragm 20 affects the amount of displacement of the diaphragm 20. Further, when the diaphragm 20 is bent, residual vibration is generated when the ink is discharged. In order to suppress the residual vibration, it is necessary to generate a predetermined waveform, but it is necessary to reduce the frequency of the predetermined waveform, and it becomes difficult to secure the ejection performance at a high frequency.

In order to secure the ejection performance at high frequencies, it is necessary to increase the rigidity of the diaphragm 20, the electromechanical conversion film 32, and the insulating protective film 40, and it is necessary to use a material having a high Young's modulus or to make the film thicker. .. In the liquid discharge head 2, the vibrating plate 20 is _{formed from a plurality of layers containing silicon oxide film (SiO 2} ), silicon nitride film (SiN), polysilicon (Poly-Si) and the like as materials in consideration of stress design. be able to. The thickness of the diaphragm 20 is preferably 1 μm or more and 3 μm or less. Further, by setting the Young's modulus of the diaphragm 20 to 75 GPa or more and 95 GPa or less, the ejection performance at a high frequency can be ensured.

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

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

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

<Material of liquid discharge head, etc.>
Next, suitable materials and the like constituting the liquid discharge head 2 will be described. As the substrate 10, it is preferable to use a silicon single crystal substrate, and it is usually preferable to have a thickness of 100 to 600 μm. There are three types of plane orientations, (100), (110), and (111), but (100) and (111) are generally widely used in the semiconductor industry, and the liquid discharge head 2 is also mainly (1). A single crystal substrate having a plane orientation of 100) can be used.

Further, when the pressure chamber 10x is produced, the silicon single crystal substrate is processed by using etching. In this case, anisotropic etching is preferably used as the etching method. 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 in which the surface is immersed in an alkaline solution such as KOH, the etching rate of the (111) plane is about 1/400 of that of the (100) plane. Therefore, in the plane orientation (100), a structure having an inclination of about 54 ° can be produced, whereas in the plane orientation (110), a deep groove can be dug. Therefore, since the arrangement density can be increased while maintaining the rigidity, the liquid discharge head 2 may also use the single crystal substrate having the plane orientation of (110). However, in this case, it should be noted that _{SiO 2,} which is a mask material, is also etched.

The width (length in the lateral direction) of the pressure chamber 10x is preferably 50 μm or more and 250 μm or less, and more preferably 60 μm or more and 150 μm or less.

The diaphragm 20 is deformed and displaced by receiving a force generated by the electromechanical conversion film 32, and ejects ink droplets in the pressure chamber 10x. Therefore, it is preferable that the diaphragm 20 has a predetermined strength. Specific examples thereof include _{those produced by Si, SiO 2} , Si ₃ N _{4 and the} like by a CVD method or the like. Further, as the material of the diaphragm 20, it is preferable to select a material having a coefficient of linear expansion close to that of the lower electrode 31 and the electromechanical conversion film 32.

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

Specific materials for the vibrating plate 20 include aluminum oxide, zirconium oxide, iridium oxide, ruthenium oxide, tantalum oxide, hafnium oxide, osmium oxide, renium oxide, rhodium oxide, palladium oxide, and compounds thereof. These can be produced by a spin coater using a sputtering method or a Sol-gel method.

The film thickness of the diaphragm 20 is preferably 1 to 10 μm, more preferably 2 to 5 μm.

As the lower electrode 31 and the upper electrode 33, platinum having high heat resistance and low reactivity can be used as the metal material. However, platinum may not have sufficient barrier properties against lead, in which case platinum group elements such as iridium and platinum-rhodium, or alloy films thereof can be used. ..

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

Further, in the lower electrode 31 and the upper electrode 33, an oxide electrode film made of _{SrRuO 3} or LaNiO _{3 may be formed between the metal material and the electromechanical conversion film 32.} Regarding the oxide electrode film between the lower electrode 31 and the electromechanical conversion film 32, the orientation control of the electromechanical conversion film 32 (for example, PZT film) produced on the oxide electrode film is also affected, so the orientation should be prioritized. The material selected depends on the orientation.

In the liquid discharge head 2, when PZT is used as the electromechanical conversion film 32 and preferentially oriented to PZT (100), _{a seed layer such as LaNiO 3} , TiO ₂ , or PbTiO _{3 is} placed on the metal material as the lower electrode 31. It is preferable to prepare and then form a PZT film.

Further, an SRO film can be used as the oxide electrode film between the upper electrode 33 and the electromechanical conversion film 32, and the thickness of the SRO film is preferably 20 nm to 80 nm, more preferably 30 nm to 50 nm.

As the electromechanical conversion film 32, lead zirconate titanate (PZT) can be preferably used. PZT is a solid solution of lead zirconate (PbZrO ₃ ) and lead titanate (PbTIO ₃ ), and the characteristics of PZT differ depending on the ratio of _{PbZrO 3} and PbTiO _3. For example, the ratio of PbZrO ₃ and PbTiO ₃ is at a ratio of 53:47, indicating a chemical formula _{Pb (Zr0.53, Ti0.47) O 3} , generally using a PZT or the like indicated as PZT (53/47) be able to.

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

The crystal orientation is represented by ρ (hkl) = I (hkl) / ΣI (hkl). Here, ρ (hkl) is the degree of orientation in the (hkl) plane orientation, I (hkl) is the peak intensity of any orientation, and ΣI (hkl) is the sum of the peak intensities. The degree of orientation of (100) orientation calculated based on the ratio of the peak intensities of each orientation when the sum of the peak intensities obtained by the θ-2θ measurement of the X-ray diffraction method is 1, is 0.75 or more. It is preferably 0.85 or more, and more preferably 0.85 or more.

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

When PZT is produced by the Sol-gel method, first, lead acetate, zirconium alkoxide, and titanium alkoxide compound are used as starting materials. Then, a PZT precursor solution can be prepared by dissolving it in methoxyethanol, which is a common solvent, to obtain a uniform solution. Since the metal alkoxide compound is easily hydrolyzed by water in the atmosphere, an appropriate amount of acetylacetone, acetic acid, diethanolamine or the like may be added as a stabilizer to the PZT precursor solution.

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

The film thickness of the electromechanical conversion film 32 is preferably 1 to 3 μm, more preferably 1.5 to 2.5 μm.

As the electromechanical conversion film 32, an ABO3 type perovskite type crystalline film other than PZT may be used. As the ABO3 type perovskite type crystalline film other than PZT, for example, a lead-free composite oxide film such as barium titanate may be used. In this case, a barium titanate precursor solution can be prepared by using a barium alkoxide or a titanium alkoxide compound as a starting material and dissolving it in a common solvent.

These materials are described by the general formula ABO3, and correspond to composite oxides containing A = Pb, Ba, Sr B = Ti, Zr, Sn, Ni, Zn, Mg, and Nb as main components. As a specific description thereof, it is expressed as (Pb _1-x , Ba) (Zr, Ti) O ₃ , (Pb _1-x , Sr) (Zr, Ti) O ₃ , which is one of the Pb of the A site. This is the case when the parts are replaced with Ba or Sr. Such substitution is possible if it is a divalent element, and its effect is to reduce the deterioration of characteristics due to evaporation of lead during heat treatment.

As the material of the insulating protective film 40, it is necessary to prevent damage to the piezoelectric element due to the film forming and etching processes and to select a material in which moisture in the atmosphere does not easily permeate. Therefore, it is possible to use a dense inorganic material. preferable.

In order to obtain high protection performance in a thin film, it is preferable to use an oxide, a nitride, or a carbonized film. It is necessary to select. In addition, it is necessary to select a film forming method that does not damage the piezoelectric element. That is, the plasma CVD method in which the reactive gas is converted into plasma and deposited on the substrate, or the sputtering method in which the plasma is collided with the target material and blown to form a film is not preferable. Examples of the preferable film forming method include a vapor deposition method and an ALD method (Atomic Layer Deposition), but the ALD method having a wide choice of materials that can be used is preferable. Preferred materials for the insulating protective film 40 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 during the process can be suppressed.

The film thickness of the insulating protective film 40 needs to be a sufficient thin film that can secure the protective performance of the electromechanical conversion element 30, and at the same time, it needs to be as thin as possible so as not to hinder the displacement of the diaphragm 20. The film thickness of the insulating protective film 40 is preferably in the range of 20 nm to 100 nm.

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

The function of the insulating protective film 70 is a passivation layer having the function of a protective layer of the wiring 60. As shown in FIG. 4, the upper electrode 33 and the lower electrode 31 are covered except for the positions of the electrode pads 61 and 62 (opening 70x). As a result, an inexpensive Al or an alloy material containing Al as a main component can be used as the electrode material. As a result, the liquid discharge head 2 can be obtained at low cost and with high reliability.

Any inorganic material or organic material can be used as the material of the insulating protective film 70, but it is necessary to use a material having 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, in the case of an organic material, it is not suitable because a thick film is required. 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 technique with a proven track record in semiconductor devices.

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

Further, a structure having an opening on the electromechanical conversion element 30 and the diaphragm 20 around the electromechanical conversion element 30 is preferable. This is the same reason as the thinning of the individual liquid chamber region of the insulating protective film 40. This makes it possible to obtain a highly efficient and highly reliable liquid discharge head 2.

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

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

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

<Polarization processing device>
Next, the polarization processing apparatus will be described. FIG. 7 is a diagram illustrating a schematic configuration of a polarization processing apparatus. The polarization processing device 500 includes a corona electrode 510 and a grid electrode 520, and the corona electrode 510 and the grid electrode 520 are connected to a corona electrode power supply 511 and a grid electrode power supply 521, respectively. A temperature control function is added to the stage 530 in which the sample is set, and the polarization treatment can be performed while applying a temperature of up to about 350 ° C. A ground 540 is installed on the stage 530, and if this is not added, the polarization process cannot be performed.

For example, the grid electrode 520 is meshed, and when a high voltage is applied to the corona electrode 510, ions and electric charges generated by the corona discharge efficiently fall on the lower stage 530, and the electric machine. It is devised so that it is injected into the conversion film 32. By adjusting the magnitude of the voltage applied to the corona electrode 510 and the grid electrode 520 and the distance between the sample and each electrode, it is possible to adjust the strength of the corona discharge.

As shown in FIG. 8, when corona discharge is performed using the corona wire 600, molecules 610 in the atmosphere are ionized to generate cations 620. Then, the generated cation 620 flows through the pad portion of the electromechanical conversion element 30, so that the electric charge can be injected into the electromechanical conversion element 30.

In this case, it is considered that the internal potential difference is generated by the charge difference between the upper electrode and the lower electrode, and the polarization treatment is performed. At this time, the amount of charge Q required for the polarization treatment is not particularly limited, but it is preferable that an amount of charge ^{of 1.0 × 10-8 C or more is accumulated in the electromechanical conversion element 30.} It is more preferable that an amount of charge of 0 × ^{10-8 C or more is accumulated.}

Here, the state of the polarization processing can be determined from the PE hysteresis loop of the electromechanical conversion element 30. The method of determining the polarization treatment will be described with reference to FIG. FIG. 9 (a) illustrates the PE hysteresis loop before the polarization treatment, and FIG. 9 (b) illustrates the PE hysteresis loop after the polarization treatment.

Specifically, first, as shown in FIG. 9, the hysteresis loop is measured by applying an electric field strength of ± 150 kv / cm. Then, when the initial polarization at 0 kv / cm is Pind and the polarization at 0 kv / cm when the voltage is returned to 0 kv / cm after applying a voltage of + 150 kv / cm is Pr, the value of Pr-Pind is used as the polarizability. It can be defined and the quality of the polarized state can be judged from this polarizability.

Polarizability Pr-Pind is preferably at 10 [mu] C / cm ² or less, still more preferably 5 [mu] C / cm ² or less. In FIG. 7, a desired polarizability Pr-Pind can be obtained by adjusting the voltage of the corona electrode 510 and the grid electrode 520, the distance between the stage 530 and the corona electrode 510 and the grid electrode 520, and the like. .. However, when trying to obtain a desired polarizability Pr-Pind, it is preferable to generate a high electric field in the electromechanical conversion film 32.

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

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

FIG. 10 is a top view of the end side of the liquid discharge head 2 having the dummy channel 4 on the end side of the drive channel 3, and is an end portion of the drive channel 3 in the arrangement direction (that is, the arrangement direction of the pressure chamber 10x). An example in which three dummy channels 4 are provided on the side is shown. As already described with reference to FIG. 4, the upper electrode 33 of the electromechanical conversion element 30 of the drive channel 3 is connected to the wiring 60 via the opening 40x of the insulating protective film 40 (not shown in FIG. 10). In the wiring 60, an electrode pad 62 is formed in the opening 70x of the insulating protective film 70. In the example of FIG. 10, the opening 70x of the insulating protective film 70 is formed over the arrangement direction so as to include the plurality of electrode pads 62, but even if the openings are opened only at the positions of the respective electrode pads 62. good.

On the other hand, since the dummy channel 4 does not drive the discharge of the liquid, as shown in the example shown in FIG. 10, for the dummy electromechanical conversion element 34 of the dummy channel 4, the wiring is pulled out from the dummy electromechanical conversion element 34 and the electrodes are electrode. It is not configured to have a pad.

As in the example shown in FIG. 10, in the dummy channel 4, in the configuration in which the wiring is pulled out from the dummy electromechanical conversion element 34 and the terminal electrode (electrode pad) is not provided, the dummy channel 4 is subjected to the polarization process (corona discharge process). In, no charge was injected, and it was found that the amount of deflection of the diaphragm 20 in the dummy channel 4 (FIG. 5) was much smaller than that in the drive channel 3. That is, as the polarization progresses due to the corona discharge treatment, the amount of contraction of the electromechanical conversion film 32 increases, so that the amount of deflection increases. At this time, the amount of deflection of the drive channel 3 at the end close to the dummy channel 4 increases. , It becomes slightly smaller due to the influence of the deflection of the dummy channel 4.

On the other hand, in the present embodiment, first, as shown in FIG. 11, in the dummy channel 4, the wiring 60 is pulled out from the dummy electromechanical conversion element 34 to provide an electrode pad (dummy electrode pad 63).

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

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

In this way, by pulling out the wiring 60 from the dummy electromechanical conversion element 34 of the dummy channel 4 and performing the polarization treatment with the dummy electrode pad 63 provided, the charge injection is concentrated on the dummy electrode pad 63 and the end portion. It is possible to suppress the charge concentration of the drive channel 3 on the side to the electrode pad 62 and suppress the variation in the amount of deflection and the polarizability.

However, as a result of further studies by the inventors of the present application, as shown in FIGS. 11 and 12, in the configuration in which the dummy channel 4 and the dummy electrode pad 63 are provided, the polarization process promotes the polarization of the dummy electromechanical conversion element 34. When the excess charge is concentrated on the dummy electrode pad 63, the deflection of the diaphragm 20 at the position of the dummy channel 4 causes the diaphragm at the position of the electromechanical conversion element 30 of the drive channel 3 on the end side. It was found that it affects the degree of bending of 20.

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

FIG. 13 is a top view of the liquid discharge head 2 according to the first embodiment. In addition to the example shown in FIG. 11, the liquid discharge head 2 shown in FIG. 13 has a predetermined interval with respect to the dummy electrode pad 63 of the dummy channel 4 located at the most extreme end thereof, and faces at least a part thereof. The guard ring wiring 64 is provided so as to do so. By providing the guard ring wiring 64, it is possible to release the excess charge concentrated on the dummy electrode pad 63 to the guard ring wiring 64 and avoid the charge concentration on the dummy electrode pad 63.

FIG. 14A is a cross-sectional view of the liquid discharge head 2 in the direction orthogonal to the arrangement direction of the pressure chambers 10x at the formation position of the guard ring wiring 64 (dotted line portion in FIG. 13). Further, FIG. 14B is a cross-sectional view of the liquid discharge head 2 in the arrangement direction of the pressure chamber 10x (one-dot chain line portion in FIG. 13) at the formation position of the guard ring wiring 64.

As shown in FIG. 14, the guard ring wiring 64 is formed on the insulating protective film 40, and is conductive with the lower electrode 31 via the contact hole H at the other end side of the end facing the dummy electrode pad 63. There is. As shown in FIG. 14, it is preferable that the other end side of the end of the guard ring wiring 64 facing the dummy electrode pad 63 is electrically connected to the lower electrode 31. In this way, by conducting the guard ring wiring 64 through the lower electrode 31 laminated on the relatively low resistance diaphragm layer 20, the electric charge injected into the guard ring wiring 64 vibrates through the lower electrode 31. It can be moved to the plate layer 20. If the other end side of the guard ring wiring 64 can be connected to another layer capable of moving the electric charge injected into the guard ring wiring 64, it may be connected to the other layer.

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

In the example of FIG. 13, an example in which the guard ring wiring 64 is provided for the dummy electrode pad 63 of the dummy channel 4 located at the endmost portion is shown. Here, as shown in FIG. 13, it is preferable to provide the guard ring wiring 64 only for the dummy electrode pad 63 of the dummy channel 4 located at the endmost portion. For example, as shown in FIG. 15, the guard ring wiring is provided. 64 may be continuously provided from the dummy channel 4 located at the endmost portion to a predetermined number of dummy electrode pads 63. Further, when the guard ring wiring 64 is provided for the electrode pads of a plurality of channels, the guard ring wiring 64 may be formed including the electrode pads 62 on the drive channel 3 side. Further, the guard ring wiring 64 includes from the dummy electrode pad 63 of the dummy channel 4 located at the endmost portion (left end portion) shown in FIG. 13 to the dummy electrode pad 63 of the dummy channel 4 located at the right end portion (not shown). It may be formed.

The shape of the guard ring wiring 64 at the position facing the dummy electrode pad 63 is preferably formed in an L shape so as to face the two sides of the dummy electrode pad 63, for example, as shown in FIG. The guard ring wiring 64 may be provided at a position facing at least a part of the dummy electrode pad 63, and the range and shape thereof are not particularly limited, but the peripheral length of the dummy electrode pad 63 is 50. By providing them so as to face each other at a position of% or more, it is possible to preferably avoid charge concentration on the dummy electrode pad 63.

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

As described above, in the liquid discharge head 2 according to the present embodiment, the dummy electrode pad of the wiring 60 connected to the dummy electromechanical conversion element 34 of the dummy channel 4 at least at the end end in the arrangement direction of the drive channel 3. A guard ring wiring 64 is provided at a position facing at least a part of 63, and is connected to the lower electrode 31. As a result, the excess charge generated at the end of the dummy channel 4 due to the polarization treatment can be released through the guard ring wiring 64. As a result, it is possible to suppress variations in the polarizability and variations in the amount of deflection.

Therefore, the bending of the diaphragm 20 at the portion of the dummy electromechanical conversion element 34 affects the degree of bending of the diaphragm 20 at the position of the electromechanical conversion element 30 of the drive channel 3 on the end side. It can be avoided, and it is possible to suppress the occurrence of variation in the degree of bending of the diaphragm 20 between the electromechanical conversion elements 30 of the drive channel 3 for discharging the liquid, and to obtain good discharge performance.

[Second Embodiment]
Hereinafter, other embodiments of the liquid discharge head according to the present invention will be described. The description of the same points as in the above embodiment will be omitted as appropriate.

FIG. 16 is a top view of the liquid discharge head 2 according to the second embodiment. In the liquid discharge head 2 shown in FIG. 16, in addition to the configuration shown in FIG. 13, a short-circuit wiring 65 for conducting the dummy electrode pad 63 and the lower electrode 31 after the polarization treatment is produced. As a result, in the dummy channel 4, the upper electrode 33 and the lower electrode 31 are short-circuited so that an electrically stable state can be obtained.

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

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

(Device that discharges liquid)
An example of a device for discharging a liquid having a liquid discharge head according to the present invention will be described with reference to FIGS. 19 and 20. FIG. 19 is an explanatory plan view of a main part of the device, and FIG. 20 is an explanatory side view of the main part of the device.

This device is a serial type device, and the carriage 403 is reciprocated in the main scanning direction by the main scanning moving mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is bridged over the left and right side plates 491A and 491B to movably hold the carriage 403. Then, the carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 bridged between the drive pulley 406 and the driven pulley 407.

The carriage 403 is equipped with a liquid discharge unit 440 in which a liquid discharge head 2 and a head tank 441 are integrated. The liquid discharge head 2 of the liquid discharge unit 440 discharges liquids of, for example, yellow (Y), cyan (C), magenta (M), and black (K). Further, the liquid discharge head 2 is mounted by arranging a nozzle array composed of a plurality of nozzles 51 in a sub-scanning direction orthogonal to the main scanning direction and directing the discharge direction downward.

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

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

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

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

Then, the transport belt 412 orbits in the sub-scanning direction by rotationally driving the transport roller 413 via the timing belt 417 and the timing pulley 418 by the sub-scanning motor 416.

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

The maintenance / recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle 51 is formed) of the liquid discharge head 2, a wiper member 422 that wipes the nozzle surface, and the like.

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

In this device configured in this way, the paper 410 is fed onto the transport belt 412 and sucked, and the paper 410 is transported in the sub-scanning direction by the orbital movement of the transport belt 412.

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

As described above, since this device is provided with the above-mentioned liquid discharge head, there is no liquid discharge failure due to a diaphragm drive failure, stable liquid discharge characteristics can be obtained, and a high-quality image can be stably formed. can do.

(Liquid discharge unit)
Next, an example of a liquid discharge unit having a liquid discharge head according to the present invention will be described with reference to FIG. FIG. 21 is an explanatory plan view of a main part of the unit.

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

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

Next, another example of the liquid discharge unit having the liquid discharge head according to the present invention will be described with reference to FIG. FIG. 22 is a front explanatory view of the unit.

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

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

In the present application, the "device for discharging a liquid" is a device provided with a liquid discharge head or a liquid discharge unit and driving the liquid discharge head to discharge the liquid. The device for discharging the liquid includes not only a device capable of discharging the liquid to a device to which the liquid can adhere, but also a device for discharging the liquid toward the air or the liquid.

The "device for discharging the liquid" can also include means for feeding, transporting, and discharging paper to which the liquid can adhere, as well as a pretreatment device, a posttreatment device, and the like.

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

Further, the "device for discharging a liquid" is not limited to a device in which a significant image such as characters and figures is visualized by the discharged liquid. For example, those that form patterns that have no meaning in themselves and those that form a three-dimensional image are also included. The above-mentioned "material to which a liquid can adhere" means a material to which a liquid can adhere at least temporarily, such as one that adheres and adheres, and one that adheres and permeates. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic substrates, electronic components such as piezoelectric elements, powder layers (powder layers), organ models, and media such as inspection cells. Yes, including anything to which the liquid adheres, unless otherwise specified.

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

The "liquid" also includes inks, treatment solutions, DNA samples, resists, pattern materials, binders, modeling solutions, solutions containing amino acids, proteins, calcium, and dispersions.

Further, the "device for discharging the liquid" includes, but is not limited to, a device in which the liquid discharge head and the device to which the liquid can adhere move relatively. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, and the like.

In addition, as a "device for ejecting liquid", a treatment liquid coating device for ejecting a treatment liquid to the paper in order to apply the treatment liquid to the surface of the paper for the purpose of modifying the surface of the paper, raw materials, etc. There is an injection granulation device or the like that granulates fine particles of raw materials by injecting a composition liquid in which the above-mentioned material is dispersed in a solution through a nozzle.

The "liquid discharge unit" is a liquid discharge head integrated with functional parts and a mechanism, and is an aggregate of parts related to liquid discharge. For example, the "liquid discharge unit" includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

Here, "integration" means, for example, a liquid discharge head and a functional component, a mechanism fixed to each other by fastening, adhesion, engagement, etc., or one in which one is movably held with respect to the other. include. Further, the liquid discharge head, the functional parts, and the mechanism may be detachably attached to each other.

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

Further, as a liquid discharge unit, there is a liquid discharge head and a carriage integrated.

Further, as a liquid discharge unit, there is a liquid discharge head in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably by a guide member forming a part of the scanning movement mechanism. Further, as shown in FIG. 21, there is a liquid discharge unit in which a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

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

Further, as a liquid discharge unit, as shown in FIG. 22, a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. ..

The main scanning movement mechanism shall also include a single guide member. Further, the supply mechanism includes a single tube and a single loading unit.

Further, the pressure generating means used for the "liquid discharge head" is not limited. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) as described in the above embodiment, it is composed of a thermal actuator using an electrothermal conversion element such as a heat generating resistor, a vibrating plate, and a counter electrode. An electrostatic actuator or the like may be used.

In addition, image formation, recording, printing, printing, printing, modeling, etc. in the terms of the present application are all synonymous.

It should be noted that the above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be carried out without departing from the gist of the present invention.

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

Hereinafter, examples of the present invention will be described.

[Example 1]
A 6-inch silicon wafer was prepared as the substrate 10, and a thermal oxide film (thickness 1 μm) was prepared on the substrate 10 as the diaphragm 20. Then, a titanium film (thickness 20 nm) was formed on the diaphragm 20 as an adhesion layer by a sputtering apparatus at a film formation temperature of 350 ° C., and then thermally oxidized at 750 ° C. using RTA (rapid heat treatment). Further, a platinum film (thickness 160 nm) was formed on the adhesion layer by a sputtering apparatus at a film formation temperature of 400 ° C. to prepare a lower electrode 31.

_{Next, a solution adjusted to Pb: Ti = 1: 1 as a PbTIO 3} layer to be a base layer on the lower electrode 31 and a solution adjusted to Pb: Zr: Ti = 115: 49: 51 as an electromechanical conversion film 32. The solution was prepared and a film was formed by the spin coating method.

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

A PZT precursor solution was synthesized by dissolving isopropoxide titanium and isopropoxide zirconium in methoxyethanol, proceeding with an alcohol exchange reaction and an esterification reaction, and mixing with the above-mentioned methoxyethanol solution in which lead acetate was dissolved. The PZT concentration was 0.5 mol / liter. The PT solution was also prepared in the same manner as PZT, and using these solutions, the PT layer was first formed by spin coating, and after the film was formed, it was dried at 120 ° C., and then the PZT solution was formed by spin coating. The film was dried at 120 ° C. and then thermally decomposed at 400 ° C.

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

_{Next, an SrRuO 3} film (thickness 40 nm) was formed as an oxide electrode film constituting the upper electrode 33, and a platinum film (thickness 125 nm) was formed as a metal film by a sputtering method. After that, a photoresist (TSMR8800) manufactured by Tokyo Ohka Co., Ltd. was formed by a spin coating method, a resist pattern was formed by ordinary photolithography, and then a pattern as shown in FIG. 4 was formed using an ICP etching apparatus (manufactured by SAMCO). Made. As a result, the electromechanical conversion element 30 was produced on the diaphragm 20.

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

Then, as shown in FIG. 4, a contact hole H was formed by etching. Then, Al was formed into a film by a sputtering method and patterned by etching to form a wiring 60, and a guard ring wiring 64 was produced, and Si ₃ N ₄ was formed into a film of 500 nm as an insulating protective film 70 by a plasma CVD method. Then, an opening 70x was provided in the insulating protective film 70 to expose a part of the wiring 60 and the guard ring wiring 64, and the structure shown in FIG. 13 was produced.

Then, the polarization treatment was performed by the corona charging treatment using the polarization treatment apparatus 500. A tungsten wire having a diameter of 50 μm is used for the corona charging treatment. The polarization treatment conditions include a treatment temperature of 80 ° C., a voltage of corona electrode 510 of 9 kV, a voltage of grid electrode 520 of 1.5 kV, a treatment time of 30 s, a distance of 4 mm between corona electrode 510 and grid electrode 520, and between grid electrode 520 and stage 530. The distance was 4 mm.

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

[Comparative Example 1]
As shown in FIG. 11, the liquid discharge head 2 was manufactured in the same manner as in Example 1 except that the structure without the guard ring wiring 64 was manufactured.

[Comparative Example 2]
As shown in FIG. 10, the liquid discharge head 2 was produced in the same manner as in Example 1 except that the structure without the dummy electrode pad 63 was produced.

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

Then, the back surface of the substrate 10 was etched to form a pressure chamber 10x and a dummy pressure chamber to form a liquid discharge head 2. However, the nozzle plate 50 provided with the nozzle 51 is not joined to the lower part of the substrate 10, and the liquid discharge head 2 is in a semi-finished state.

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

For the electromechanical conversion element 30 of each of the liquid discharge heads 2 manufactured in Examples 1 and 2 and Comparative Examples 1 and 2, XRD measurement at the corresponding position using a chip corresponding to the position of C3 shown in FIG. The displacement characteristics (piezoelectric constant) and the amount of curvature of the diaphragm were evaluated. Regarding the evaluation of the displacement characteristics, the vibration evaluation was carried out from the pressure chamber 10x side. Specifically, the amount of deformation due to the application of an electric field (150 kV / cm) was measured with a laser Doppler vibrometer and calculated from the adjustment by simulation. The amount of curvature (radius of curvature) of the diaphragm 20 was measured using a white light interference type surface shape measuring machine.

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

As can be seen from Table 1, in Examples 1 and 2 and Comparative Example 1, the displacement difference is within the target 8% as the displacement slope in the channel group from each end in the chip to 20 ch. In Comparative Example 2, there was a large variation of 13.0%. Further, it was confirmed that the displacement difference can be more preferably suppressed in Examples 1 and 2 as compared with Comparative Example 1 in which the guard ring is not provided.

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

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

Specifically, using an ink whose viscosity was adjusted to 5 cp, the ejection state when an applied voltage of -10 to -30 V was applied was confirmed by a simple Push waveform. As a result, it was confirmed that each of the liquid discharge heads 2 produced in Examples 1 and 2 and Comparative Example 1 can be discharged from any nozzle 51 and can be discharged at a high frequency. On the other hand, regarding the liquid discharge head 2 produced in Comparative Example 2, it was confirmed that the liquid discharge speed greatly varied in the nozzle 51 corresponding to the channel group at each end in the head.

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

Japanese Unexamined Patent Publication No. 2014-177049

Claims (9)

Multiple nozzles that discharge liquid and
A plurality of pressure chambers for discharging liquid communicating with the nozzle are formed side by side in a predetermined direction, and at least one dummy pressure chamber arranged on the end side of the pressure chamber in the predetermined direction is formed. Forming substrate and
A diaphragm layer provided on one surface of the pressure chamber forming substrate, and a part thereof constitutes a wall surface of the pressure chamber and the dummy pressure chamber.
An electromechanical conversion element provided on the diaphragm layer corresponding to each pressure chamber,
A dummy electromechanical conversion element provided on the diaphragm layer corresponding to each dummy pressure chamber,
An electrode pad electrically connected to the electromechanical conversion element and
A dummy electrode pad electrically connected to the dummy electromechanical conversion element and
A wiring formed so as to face at least a part of the dummy electrode pad located at least at the end of the dummy electrode pad.
A discharge control means for controlling the discharge of liquid from the nozzle is provided.
The electrode pad is electrically joined to the discharge control means, and the electrode pad is electrically joined to the discharge control means.
The liquid discharge head is characterized in that the dummy electrode pad is not electrically joined to the discharge control means. The electromechanical conversion element includes a lower electrode laminated on the diaphragm layer.
The liquid discharge head according to claim 1, wherein the wiring is conductive to the lower electrode. The liquid discharge head according to claim 1 or 2, wherein the wiring is formed so as to face 50% or more of the peripheral length of the dummy electrode pad. The liquid discharge head according to any one of claims 1 to 3, wherein the distance between the wiring and the dummy electrode pad is in the range of 3 to 50 μm. The liquid discharge head according to any one of claims 1 to 4, wherein a short-circuit wiring for conducting the dummy electrode pad and the common electrode of the electromechanical conversion element is provided. The liquid discharge head according to claim 5, further comprising an insulating protective film that covers the short-circuit wiring. The method for manufacturing a liquid discharge head according to claim 5.
A method for manufacturing a liquid discharge head, wherein the step of manufacturing the short-circuit wiring is a step after the polarization treatment of the electromechanical conversion element and the dummy electromechanical conversion element. A liquid discharge unit comprising the liquid discharge head according to any one of claims 1 to 6. A device for discharging a liquid, which comprises the liquid discharge head according to any one of claims 1 to 6 or the liquid discharge unit according to claim 8.

Images