JP2012144001A - Piezoelectric actuator, liquid ejection head and liquid ejection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator with large displacement, a liquid ejection head and a liquid ejection apparatus.SOLUTION: The piezoelectric actuator 100 includes: a vibrating plate 10; a first electrode 21 formed on the vibrating plate 10; an orientation control layer 30 formed above the first electrode 21; a piezoelectric layer 40 formed above the orientation control layer 30; and a second electrode 50 formed above the piezoelectric layer 40. A storage part 11 is processed to be recessed in the vibrating plate 10, and the first electrode 21 is formed in the storage part 11.

Description

  The present invention relates to a piezoelectric actuator, a liquid ejecting head, and a liquid ejecting apparatus.

  Conventionally, a liquid ejecting apparatus represented by an ink jet printer applies pressure to a pressure chamber by a piezoelectric actuator and ejects ink from nozzle holes. The piezoelectric actuator is configured such that the piezoelectric layer is deformed and driven when a voltage is applied by the lower electrode and the upper electrode, and discharge is controlled independently for each corresponding pressure chamber (for example, Patent Document 1).

  By the way, in order to improve the resolution in the liquid ejecting apparatus, it is necessary to further increase the density, and it is required to increase the number of piezoelectric actuators installed per unit area.

JP 2005-119199 A

  However, if a large number of piezoelectric actuators are installed to improve the resolution, the width of the pressure chamber becomes narrow, so that there is a problem that the displacement amount of the piezoelectric actuator becomes small.

  In view of the circumstances described above, an object of the present invention is to obtain a piezoelectric actuator having a large displacement amount, a liquid ejecting head including the piezoelectric actuator, and a liquid ejecting apparatus, and can be realized as the following application examples.

  Application Example 1 A piezoelectric actuator according to this application example includes a diaphragm in which a concave housing portion is formed, a first electrode formed in the housing portion, and an orientation control layer formed on the first electrode. And a piezoelectric layer formed on the orientation control layer and a second electrode formed on the piezoelectric layer.

  According to this application example, since the concave accommodating portion is formed in the diaphragm and the first electrode is formed in the accommodating portion, a voltage is applied between the first electrode and the second electrode, and the piezoelectric layer is formed. At the time of deformation, the film thickness of the diaphragm portion that is deformed together becomes thin, and the amount of displacement increases as a piezoelectric actuator.

Application Example 2 In the piezoelectric actuator according to the application example described above, it is preferable that a surface of the housing portion that faces the orientation control layer of the first electrode is in the same plane as the surface of the diaphragm.
Here, the term “in-plane” does not need to be exactly the same, and even if the surface of the first electrode facing the orientation control layer is displaced from the surface including the surface of the diaphragm, the displacement due to manufacturing variations If so, they shall be included in the same plane.

  According to this application example, since the surface of the diaphragm and the surface of the accommodated first electrode are in the same plane, the piezoelectric layers can be laminated at a time. Therefore, the process of forming the piezoelectric layer is shortened.

  Application Example 3 A piezoelectric actuator having a protective film formed so as to cover at least the side surface of the piezoelectric layer described in the application example is preferable.

  According to this application example, the side surface of the piezoelectric layer is not exposed to the atmosphere, and deterioration of piezoelectric characteristics due to moisture in the atmosphere can be suppressed.

  Application Example 4 It is preferable that the diaphragm described in the application example is made of zirconia.

  According to this application example, when lead zirconate titanate is used as the piezoelectric layer, the diaphragm made of zirconia can prevent lead from diffusing into the lower layer.

  Application Example 5 It is preferable that the piezoelectric actuator described in the application example is used for a liquid jet head.

  According to this application example, it is possible to provide a liquid ejecting head having a piezoelectric actuator which is one aspect of this application example.

  Application Example 6 It is preferable that the liquid ejecting head described in the application example is used in a liquid ejecting apparatus.

  According to this application example, it is possible to provide a liquid ejecting apparatus having a liquid ejecting head which is one aspect of the present application example.

Sectional drawing which shows typically the piezoelectric actuator which concerns on embodiment. The top view which shows typically the piezoelectric actuator which concerns on embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric actuator which concerns on embodiment. Sectional drawing which shows typically the manufacturing process of the piezoelectric actuator which concerns on embodiment. Sectional drawing which shows typically the piezoelectric actuator which concerns on a modification. FIG. 3 is a cross-sectional view schematically illustrating the liquid ejecting head according to the embodiment. FIG. 3 is an exploded perspective view schematically illustrating the liquid ejecting head according to the embodiment. Schematic which shows an example of the liquid ejecting apparatus which concerns on embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is made different from the actual scale so that each layer and each member can be recognized.

FIG. 1 is a cross-sectional view schematically showing a piezoelectric actuator 100 according to an embodiment. FIG. 2 is a plan view schematically showing the piezoelectric actuator 100. FIG. 2 shows a row in which a plurality of piezoelectric actuators 100 are arranged. 1 is a cross-sectional view taken along line AA in FIG.
First, a schematic configuration of the piezoelectric actuator 100 according to the embodiment will be described.

As shown in FIG. 1, the piezoelectric actuator 100 includes a vibration plate 10, a first electrode 21 as a lower electrode, an orientation control layer 30, a piezoelectric layer 40, and a second electrode 50 as an upper electrode.
The diaphragm 10 is formed with a housing portion 11 in which the first electrode 21 is housed, and the first electrode 21 is formed in the housing portion 11. On the first electrode 21, the orientation control layer 30 is formed across the first electrode 21 and the diaphragm 10. Here, the surface 12 of the diaphragm 10 on which the accommodating portion 11 is formed and the surface 23 of the first electrode 21 facing the alignment control layer 30 (the surface 23 when there is no alignment control layer 30) are in the same plane. It is formed as follows.

A plurality of piezoelectric layers 40 are formed on the orientation control layer 30 as shown in FIG. 2, and the second electrode 50 shown in FIG. 1 is formed on each piezoelectric layer 40.
1 and 2, the first electrode 21 is formed as a common electrode of each piezoelectric layer 40, and the second electrode 50 is formed as an individual electrode.

A method for manufacturing the piezoelectric actuator 100 will be described below.
3A to 4H are cross-sectional views showing the manufacturing process of the piezoelectric actuator 100. FIG. In the figure, a case where two rows in which a plurality of piezoelectric actuators 100 are arranged is formed.
In FIG. 3A, the diaphragm 10 is prepared. The material of the diaphragm 10 can be zirconia.
3B, the accommodating portion 11 in which the first electrode 21 shown in FIGS. 1 and 2 is formed is formed by processing the diaphragm 10 into a concave shape. For this processing, dry etching or wet etching can be used.

In FIG. 3C, the first electrode 21 is formed in the accommodating portion 11. More specifically, the first electrode 21 is formed on the processed diaphragm 10 by forming the material constituting the first electrode 21 thickly by sputtering or the like and then polishing until the surface 12 of the diaphragm 10 comes out. can get.
The film thickness of the first electrode 21 can be about 80 nm, for example. Moreover, as the 1st electrode 21, metals, such as iridium or platinum, can be used, for example. The first electrode 21 is one electrode for applying a voltage to the piezoelectric layer 40.

  In the region configured such that the surface of the first electrode 21 is in the same plane as the surface 12 of the diaphragm 10, the piezoelectric layer 40 shown in FIGS. 1 and 2 has the first electrode 21, the second electrode 50, and the like. This is a substantial drive region of the piezoelectric actuator 100 sandwiched between the two, and the vibration plate 10 is thinned by the film thickness of the first electrode 21 and the displacement amount due to the drive can be increased.

In FIG. 3D, the orientation control layer 30 is formed on the first electrode 21. The orientation control layer 30 also has a function as a buffer layer that controls the crystal orientation of the piezoelectric layer 40. The thickness of the orientation control layer 30 can be about 40 nm, for example. Moreover, as the orientation control layer 30, for example, a conductive oxide can be used. For example, lanthanum nickelate (LaNiO ₃ : LNO) (hereinafter referred to as LNO) or a composite oxide of strontium and ruthenium (SrRuO ₃ : SRO) can be used.

  In FIG. 4 (e), when a conductive oxide is used for the orientation control layer 30, it is necessary to prevent conduction between the first electrodes 21. Therefore, as shown in FIG. 4E, the orientation control layer 30 is processed, and the orientation control layer 30 is divided for each row in which the piezoelectric actuators 100 are arranged.

In FIG. 4F, the piezoelectric layer 40 is formed on the orientation control layer 30. A piezoelectric material can be used for the piezoelectric layer 40. For the piezoelectric layer 40, for example, a perovskite oxide represented by the general formula ABO ₃ can be used. A includes lead, and B includes at least one of zirconium and titanium. B can further include niobium, for example. Specifically, examples of the piezoelectric layer 40 include lead zirconate titanate (Pb (Zr, Ti) O ₃ : PZT) and lead zirconate titanate niobate (Pb (Zr, Ti, Nb) O _3. : PZTN) and the like can be used.

Moreover, although the film thickness of the piezoelectric body layer 40 is dependent on the use of the piezoelectric actuator 100, it can be 300 nm-3000 nm, for example. As shown in FIG. 2, the piezoelectric layer 40 is formed to have a short side and a long side in a plan view. The piezoelectric layer 40 is formed so that the opposing short sides are located outside the first electrode.
Here, since the surface 23 of the first electrode 21 in the housing portion 11 is in the same plane as the surface of the diaphragm 10, the surface of the diaphragm 10 and the surface 23 of the first electrode 21 are flat. Therefore, the piezoelectric layer 40 can be laminated at a time.

  In FIG. 4G, the second electrode 50 is formed on the piezoelectric layer 40. The second electrode 50 is paired with the first electrode 21 and functions as the other electrode. The thickness of the 2nd electrode 50 can be 20 nm-200 nm, for example. As the second electrode 50, for example, platinum, iridium, or a conductive oxide thereof can be used. In addition, the second electrode 50 may be a single layer of the exemplified material or may have a structure in which a plurality of materials are stacked.

  In FIG. 4H, the individual piezoelectric actuators 100 can be obtained by processing the second electrode 50 and the piezoelectric layer 40.

  As a modification, as shown in FIG. 5, the orientation control layer 30 may be made of a non-conductive material such as titania. In FIG. 5, since it is not necessary to process the orientation control layer 30, the process can be shortened.

Next, a liquid ejecting head 600 including the piezoelectric actuator 100 according to the embodiment will be described with reference to the drawings. FIG. 6 is a cross-sectional view schematically illustrating a main part of the liquid jet head 600 according to the embodiment. FIG. 7 is an exploded perspective view of the liquid jet head 600 according to the embodiment, which is shown upside down from a state in which it is normally used.
The liquid ejecting head 600 includes the piezoelectric actuator 100 described above.

As shown in FIGS. 6 and 7, the liquid ejecting head 600 includes a nozzle plate 6 having nozzle holes 5, a pressure chamber substrate 8 for forming the pressure chamber 7, and a piezoelectric actuator 100.
The number of piezoelectric actuators 100 is not particularly limited, and a plurality of piezoelectric actuators 100 may be formed. In FIG. 6, the piezoelectric actuator 100 is formed on the substrate 9. A protective film 60 is formed on the piezoelectric actuator 100 so as to cover the side surface of the piezoelectric layer 40. Here, a part of the protective film 60 on the second electrode 50 is removed so as not to hinder the movement of the piezoelectric actuator 100.
When a plurality of piezoelectric actuators 100 are formed, either the first electrode 21 or the second electrode 50 can be used as a common electrode. Further, the liquid ejecting head 600 can include a housing 80.

  As shown in FIGS. 6 and 7, the nozzle plate 6 has nozzle holes 5. The nozzle holes 5 include liquids such as ink (not only liquids but also various functional materials adjusted to an appropriate viscosity with a solvent or dispersion medium, or those containing metal flakes, etc.). .) Can be jetted as a liquid. In the nozzle plate 6, for example, a large number of nozzle holes 5 are provided in a row. Examples of the material of the nozzle plate 6 include silicon and stainless steel (SUS).

  The pressure chamber substrate 8 is provided on the nozzle plate 6 (lower in the example of FIG. 7). Examples of the material of the pressure chamber substrate 8 include silicon. The pressure chamber 7 is provided by dividing the space between the nozzle plate 6 and the substrate 9 by the pressure chamber substrate 8. The volume of the pressure chamber 7 changes due to the deformation of the diaphragm 10 and the substrate 9. The pressure chamber 7 communicates with the nozzle hole 5, and liquid or the like is ejected from the nozzle hole 5 when the volume of the pressure chamber 7 changes.

The piezoelectric actuator 100 is provided on the pressure chamber substrate 8 (lower in the example of FIG. 7). The piezoelectric actuator 100 is electrically connected to a piezoelectric element drive circuit (not shown), and can operate (vibrate or deform) based on a signal from the piezoelectric element drive circuit. The diaphragm 10 and the substrate 9 can be deformed by the operation of the laminated structure (piezoelectric layer 40), and the internal pressure of the pressure chamber 7 can be appropriately changed.
As shown in FIG. 7, the housing 80 can accommodate the nozzle plate 6, the pressure chamber substrate 8, and the piezoelectric actuator 100. Examples of the material of the housing 80 include resin and metal.

  Here, the case where the liquid ejecting head 600 is an ink jet recording head has been described. However, the liquid jet head of the present invention includes, for example, a color material jet head used for manufacturing a color filter such as a liquid crystal display, an electrode material jet head used for forming an electrode such as an organic EL display and an FED (surface emitting display), It can also be used as a bio-organic matter ejecting head used for biochip manufacturing.

  Next, the liquid ejecting apparatus 700 according to the embodiment will be described with reference to the drawings. The liquid ejecting apparatus 700 includes the liquid ejecting head 600 described above. Hereinafter, a case where the liquid ejecting apparatus 700 is an ink jet printer having the above-described liquid ejecting head 600 will be described. FIG. 8 is a perspective view schematically illustrating a liquid ejecting apparatus 700 according to the embodiment.

  As illustrated in FIG. 8, the liquid ejecting apparatus 700 includes a head unit 730, a driving unit 710, and a control unit 760. Further, the liquid ejecting apparatus 700 includes an apparatus main body 720, a paper feed unit 750, a tray 721 for installing the recording paper P, a discharge port 722 for discharging the recording paper P, and an operation disposed on the upper surface of the apparatus main body 720. A panel 770.

  The head unit 730 includes an ink jet recording head (hereinafter, also simply referred to as “head”) configured from the liquid ejecting head 600 described above. The head unit 730 further includes an ink cartridge 731 that supplies ink to the head, and a transport unit (carriage) 732 on which the head and the ink cartridge 731 are mounted.

  The drive unit 710 can reciprocate the head unit 730. The drive unit 710 includes a carriage motor 741 serving as a drive source for the head unit 730, and a reciprocating mechanism 742 that receives the rotation of the carriage motor 741 and reciprocates the head unit 730.

  The reciprocating mechanism 742 includes a carriage guide shaft 744 supported at both ends by a frame (not shown), and a timing belt 743 extending in parallel with the carriage guide shaft 744. The carriage guide shaft 744 supports the carriage 732 while allowing the carriage 732 to freely reciprocate. Further, the carriage 732 is fixed to a part of the timing belt 743. When the timing belt 743 is caused to travel by the operation of the carriage motor 741, it is guided to the carriage guide shaft 744 and the head unit 730 reciprocates. During this reciprocation, ink is appropriately discharged from the head, and printing on the recording paper P is performed.

  In the embodiment, an example is shown in which printing is performed while both the liquid ejecting head 600 and the recording paper P move. However, in the liquid ejecting apparatus of the present invention, the liquid ejecting head 600 and the recording paper P are relative to each other. Alternatively, a mechanism for printing on the recording paper P at a different position may be used. Further, in the embodiment, an example in which printing is performed on the recording paper P is shown, but the recording medium that can be printed by the liquid ejecting apparatus of the present invention is not limited to paper, but is cloth, film, metal A wide range of media can be mentioned, and the configuration can be changed as appropriate.

The control unit 760 can control the head unit 730, the driving unit 710, and the paper feeding unit 750.
The paper feeding unit 750 can feed the recording paper P from the tray 721 to the head unit 730 side. The paper feed unit 750 includes a paper feed motor 751 serving as a drive source thereof, and a paper feed roller 752 that rotates by the operation of the paper feed motor 751. The paper feed roller 752 includes a driven roller 752a and a drive roller 752b that are vertically opposed to each other with the feeding path of the recording paper P interposed therebetween. The drive roller 752b is connected to the paper feed motor 751. When the paper feeding unit 750 is driven by the control unit 760, the recording paper P is sent so as to pass below the head unit 730.

The head unit 730, the driving unit 710, the control unit 760, and the paper feeding unit 750 are provided inside the apparatus main body 720.
The liquid ejecting apparatus 700 includes the piezoelectric actuator 100 having a large displacement amount.

  The liquid ejecting apparatus exemplified above has one liquid ejecting head, and the liquid ejecting head can perform printing on a recording medium. However, the liquid ejecting apparatus may have a plurality of liquid ejecting heads. . When the liquid ejecting apparatus includes a plurality of liquid ejecting heads, the plurality of liquid ejecting heads may be independently operated as described above, or the plurality of liquid ejecting heads may be connected to each other to It may be a gathered head. An example of such a set of heads is a line-type head in which nozzle holes of a plurality of heads have a uniform interval as a whole.

  As described above, the liquid ejecting apparatus 700 as an ink jet printer has been described as an example of the liquid ejecting apparatus according to the present invention. However, the liquid ejecting apparatus according to the present invention can be used industrially. As the liquid or the like (liquid material) discharged in this case, various functional materials adjusted to an appropriate viscosity with a solvent or a dispersion medium can be used. In addition to the exemplified image recording apparatus such as a printer, the liquid ejecting apparatus of the present invention includes a color material ejecting apparatus, an organic EL display, an FED (surface emitting display), and an electrophoretic display used for manufacturing a color filter such as a liquid crystal display. The present invention can also be suitably used as a liquid material ejecting apparatus used for forming electrodes such as electrodes and color filters, and a bioorganic material ejecting apparatus used for biochip manufacturing.

  As described above, according to the piezoelectric actuator 100 according to the embodiment, the amount of displacement increases due to the above-described effect of thinning the diaphragm, so that the lack of displacement due to the shortening of the pressure chamber width due to high density is solved. The

  DESCRIPTION OF SYMBOLS 10 ... Diaphragm, 11 ... Housing part, 12 ... Surface of diaphragm, 21 ... First electrode, 23 ... Surface of first electrode, 30 ... Orientation control layer, 40 ... Piezoelectric layer, 50 ... Second electrode, 60 Protective film 100 Piezoelectric actuator 600 Liquid ejecting head 700 Liquid ejecting apparatus

Claims (6)

A diaphragm in which a concave housing portion is formed;
A first electrode formed in the housing;
An orientation control layer formed on the first electrode;
A piezoelectric layer formed on the orientation control layer;
A piezoelectric actuator, comprising: a second electrode formed on the piezoelectric layer. 2. The piezoelectric actuator according to claim 1, wherein a surface of the housing portion facing the orientation control layer of the first electrode is in the same plane as the surface of the diaphragm.   The piezoelectric actuator according to claim 1, further comprising a protective film formed so as to cover at least a side surface of the piezoelectric layer.   The piezoelectric actuator according to claim 1, wherein the diaphragm is made of zirconia.   A liquid ejecting head comprising the piezoelectric actuator according to claim 1.   A liquid ejecting apparatus comprising the liquid ejecting head according to claim 5.

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