JP2003127367A - Piezoelectric actuator of ink jet printer head and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator of ink jet printer head which is simplified in its structure, reduced in cost and easily downsized and made highly efficient, and its manufacturing method. SOLUTION: In the piezoelectric actuator of the ink jet printer head 10, ink is ejected from nozzles 21 by controlling the pressure in an ink pressure chamber by deforming a diaphragm 70 which constitutes a part of the inner wall of the ink pressure chamber 51 using the piezoelectric element 80, wherein the piezoelectric actuator of the ink jet printer head is so constituted that the diaphragm 70 is formed on the surface of the piezoelectric element 80 by a plating method, and at least the surface region of the diaphragm in contact with ink is provided with a protective layer 60 formed of a material having ink resistance properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention provides a piezoelectric element,
Piezoelectric actuator for a so-called ink jet printer head, in which a vibration plate forming a part of the inner wall of the ink pressure chamber is deformed to control the pressure in the ink pressure chamber so that ink is ejected from a nozzle, and its manufacture Regarding the method.

[0002]

2. Description of the Related Art In recent years, non-impact recording type printers have been attracting attention because noise during recording is extremely small and high-speed printing is possible. In particular, a so-called ink jet printer, in which liquid ink droplets are ejected from the recording head and adhered to the recording paper to print characters, figures, photographs, etc., is capable of high-speed recording and at the same time on plain paper. Various ink jet printers have been developed and are commercially available because recording can be performed without performing a special fixing process or the like.

In such an ink jet printer, for example, an ink jet printer head having a structure as shown in FIGS. 5 to 9 is used. In FIG. 5, the printer head 900 is configured to bond a piezoelectric element and a vibration plate and to discharge ink droplets by utilizing the unimorph effect. That is, specifically, the printer head 900 sequentially stacks a nozzle plate 910, an ink pool plate 920, an ink supply plate 930, a pressure chamber plate 940, a vibration plate 950, and a piezoelectric element 960, as shown in FIG. It is configured by being joined to each other.

The nozzle plate 910 has a plurality of aligned nozzles 911 for ejecting ink. The ink pool plate 920 is the nozzle plate 9
A plurality of ink communicating portions 921 provided corresponding to each of the ten nozzles 911 and one ink pool 922 provided around these ink communicating portions 921 are provided.

Similarly, the ink supply plate 930 is provided with a plurality of ink communicating portions 931 provided corresponding to the nozzles 911 of the nozzle plate 910, and adjacent to the ink communicating portions 931. 92
No. 0 ink pool 922 and a plurality of ink supply ports 932, and at one end, the ink pool plate 9
20 ink pools 922 with ink inlets 93
3 and 3 are provided.

The pressure chamber plate 940 has a plurality of pressure chambers 9 for communicating the respective ink communication portions 930 of the ink supply plate 930 with the corresponding ink supply ports 932.
41 and an ink suction port 942 that communicates with the ink suction port 933 of the ink supply plate 930 at one end.

The vibrating plate 950 is made of a flat plate having flexibility and has an ink suction port 951 communicating with the ink suction port 942 of the pressure chamber plate 940. The piezoelectric elements 960 are the vibration plates 950, respectively.
A plurality of pressure chamber plates 940 are disposed so as to face each pressure chamber 941 of the pressure chamber plate 940.

Here, the nozzle plate 910, the ink pool plate 920, the ink supply plate 930,
The pressure chamber plate 940 and the vibration plate 950 have a pair of positioning holes 912 and 92 for positioning each other.
3,934,943,952 are provided at one end. The nozzle plate 910, ink pool plate 920, ink supply plate 930, pressure chamber plate 9
Although the 40 and the vibration plate 950 are formed separately from each other, at least two or more adjacent to each other may be integrally formed. In addition, the piezoelectric element 96
0 and the vibration plate 950 form a piezoelectric actuator for ejecting ink droplets.

Further, although not shown, the printer head 900 uses an electric signal line for inputting an electric signal to each piezoelectric element 960 and ink from an ink tank via ink suction ports 951, 942, 933. An ink flow path for filling the pool 922 is provided.

The printer head 900 having such a configuration
When assembling, each of the above plates, that is, the nozzle plate 910, the ink pool plate 920, the ink supply plate 930, the pressure chamber plate 940, and the vibrating plate 95.
0 are positioning holes 912, 923, 934, 94 with respect to each other.
3, 952, the piezoelectric elements 960 are positioned and bonded on the vibration plate 950 so as to have an appropriate positional relationship with the corresponding pressure chambers 941 of the pressure chamber plate 940. It In this way, the printer head 900, as shown in FIG.
Will be assembled.

Next, the operation of the printer head 900 will be described with reference to FIGS. 7A and 7B are sectional views taken along the line AA in FIG. 6, that is, sectional views taken along the nozzles 911 of the nozzle plate 910. Piezoelectric elements 960 are bonded to the vibration plate 950 so as to correspond to the respective pressure chambers 941 of the pressure chamber plate 940. Here, an upper electrode 961 and a lower electrode 962 are formed on the upper and lower surfaces of each piezoelectric element 960, respectively. A piezoelectric element 960 is polarized in the vertical direction P between the upper electrode 961 and the lower electrode 962, as indicated by an arrow P, for example.

The lower electrode 962 is electrically connected by being joined to the vibration plate 950. Thereby, each lower electrode 962 is connected to one side of the drive source 963 with the diaphragm 950 as a common electrode. Further, the upper electrode 961 is connected to the other side of the drive source 963 via the switch circuit 964 for each piezoelectric element 960.

When the switch circuit 964 is turned on based on the print command, a drive voltage is applied from the drive source 963 to the piezoelectric element 960 corresponding to the switch circuit 964. As a result, as shown in FIG. 7B, the piezoelectric element 960 tries to contract in the e direction due to the piezoelectric lateral effect.

By the way, the lower surface of the piezoelectric element 960 is
Since it is bonded to the diaphragm 950, the amount of strain due to contraction due to the load on the diaphragm 950 is suppressed to a low level. Therefore, the piezoelectric element 960 is, as shown in FIG.
Since the vicinity of the center is deformed downward as shown by the arrow f, the volume of the pressure chamber 941 decreases and the inside of the pressure chamber 941 is pressurized.

FIGS. 8A, 8B and 8C are shown in FIG.
9 is a cross-sectional view taken along line BB of FIG. 8, that is, a cross-sectional view showing a pressure chamber and an ink pool 922 for one nozzle 911. In the initial state shown in FIG. The nozzle 911 is filled through the chamber 941 and the ink communicating portions 931 and 921. Here, when the pressure chamber 941 is pressurized as described above, the ink filled in the pressure chamber 941 is changed from the state of FIG. 8A to the state shown in FIG. 8B. As indicated by arrows g and h, the pressure is released by the nozzle 911 and the ink supply port 932, and the nozzle 911 is released.
Is discharged from.

After that, when the electric charge of the piezoelectric element 960 is discharged, the distortion of the piezoelectric element 960 and the vibration plate 950 returns to the original as shown by the arrow i as shown in FIG. 8C.
At this time, from the ink pool 922 to the ink supply port 932
The ink is refilled into the pressure chamber 941 by a so-called refill operation as shown by an arrow j through
The process returns to the initial state shown in (a), and the series of printing operations ends. Actually, the series of printing operations described above are repeatedly performed at high speed, so that characters, figures, photographs, etc. are printed on the printing paper.

[0017]

By the way, as the printing speed of the printer is increased, there is a strong demand for downsizing of the ink jet type print head. Along with this, miniaturization and high efficiency of piezoelectric actuators used in ink jet print heads have become essential. In order to improve the efficiency of the characteristics of the piezoelectric actuator including the piezoelectric element 960 and the vibration plate 950 in the printer head 900 described above, a conventional method, for example, Japanese Patent Laid-Open No.
In No. 9-094965, after the diaphragm and the pressure chamber partition wall are formed by electrostatic bonding, the thickness of the diaphragm is thinned by processing, and further, in a state before being processed to the final thickness on the diaphragm. A method has been proposed in which a piezoelectric element is bonded and then the piezoelectric element is processed to a predetermined thickness.

According to this method, it is possible to strengthen the joint between the vibrating plate and the pressure chamber partition wall, and when joining the vibrating plate and the pressure chamber partition wall, a relatively thick vibrating plate is bonded and then Since the diaphragm is thinly processed, the workability is improved, and as a result, the diaphragm can be thinner. In this way, the diaphragm and the piezoelectric element can be made thinner, and the bonding strength between the diaphragm and the pressure chamber partition wall can be increased. Therefore, a piezoelectric actuator with higher efficiency can be obtained. Can be provided.

However, according to such a method,
When the vibration plate of the piezoelectric element is bonded, since the vibration plate is in a thin film state, a sufficient load cannot be applied to the bonding surface. Therefore, the adhesive layer between the piezoelectric element and the vibrating plate is formed to be relatively thick, which reduces the efficiency of the piezoelectric actuator. Further, since the thickness of the adhesive layer becomes uneven, there is a problem that the characteristics of the piezoelectric actuator in each pressure chamber vary, or the life is shortened depending on the state of the adhesive layer.

On the other hand, for example, Japanese Patent Laid-Open No. 05-301
No. 341 proposes a method of forming a piezoelectric actuator by growing a metal film on a piezoelectric element by electroplating and then forming a pressure chamber by an etching process. However, in this case, since the plated surface is processed by half etching, the variation of the vibration plate thickness becomes large, and the variation of the characteristics of the piezoelectric actuator similarly occurs. Further, since the plating surface is exposed to the ink, it is necessary to use plating having high ink resistance, which makes the etching process difficult. Further, in the thin film portion formed as the diaphragm, if a pinhole is generated in the plating, the piezoelectric element and the ink come into contact with each other. Therefore, it is necessary to select the thickness of the diaphragm so that the pinhole is free. is there. Therefore, it becomes difficult to increase the efficiency of the characteristics of the piezoelectric actuator.

The present invention has been made to solve the above-mentioned problems, and is an inkjet printer which has a simple structure and can be easily reduced in size and increased in efficiency at low cost. An object is to provide a piezoelectric actuator for a printhead.

[0022]

To achieve this object, in a piezoelectric actuator of an ink jet printer head according to a first aspect of the present invention, a vibrating plate constituting a part of an ink pressure chamber inner wall is deformed by a piezoelectric element. A piezoelectric actuator of an inkjet printer head for controlling the pressure in an ink pressure chamber to eject ink from a nozzle, wherein the vibrating plate is formed on a surface of a piezoelectric element by a plating method, At least the surface region of the plate that contacts the ink is provided with a protective layer made of an ink-resistant material.

When the piezoelectric actuator of the ink jet printer head has such a structure, the vibrating plate is formed on the surface of the piezoelectric element by the plating method, so that the bonding property of the vibrating plate to the surface of the piezoelectric element becomes good. Also,
The surface area of the piezoelectric element and the diaphragm that come into contact with the ink is
Since it is covered with the protective layer made of the ink resistant material, the vibrating plate formed by the plating method is not eroded by coming into contact with the ink in the ink pressure chamber. Therefore, the material of the diaphragm can be arbitrarily selected, so that the cost can be reduced. Further, since the diaphragm formed by the plating method is covered with the protective layer, even if a pinhole is generated in the diaphragm, the pinhole will be hidden from the ink by the protective layer. Therefore, it is not necessary to select the thickness of the diaphragm so as to be pinhole-free, and it is easy to make the diaphragm thin and increase the efficiency of the characteristics of the piezoelectric actuator.

Further, in the piezoelectric actuator of the ink jet printer head according to claim 2, the protective layer is
It is composed of a polymer film. When the piezoelectric actuator of the inkjet printer head has such a configuration, the protection layer is made of a polymer film made of, for example, liquid thermoplastic polyimide, so that ink resistance can be ensured.

According to a third aspect of the present invention, there is provided a piezoelectric actuator for an ink jet printer head, wherein the protective layer comprises:
It is formed by a plating method. When the piezoelectric actuator of the ink jet printer head has such a structure, the protective layer is formed by a plating method so as to have a gold-plated film at least in the surface region in contact with the ink in the ink pressure chamber.
Ink resistance can be secured. In this case, the cost can be further reduced by forming the portion other than the surface region, for example, as a nickel plating film.

According to a fourth aspect of the present invention, in a piezoelectric actuator of an ink jet printer head, a seed layer serving as a trigger is formed on the surface of the piezoelectric element before the vibration plate is formed by the plating method. When the piezoelectric actuator of the inkjet printer head has such a structure, when the diaphragm is formed by the plating method, the seed layer is formed on the surface of the piezoelectric element. Adhesion to the element surface is improved.

Further, in order to achieve this object, in a method of manufacturing a piezoelectric actuator of an ink jet printer head according to a fifth aspect of the present invention, a piezoelectric element is used to deform a vibrating plate forming a part of the inner wall of the ink pressure chamber. With respect to the piezoelectric actuator of the ink jet printer head that controls the pressure in the ink pressure chamber to eject ink from the nozzle, a vibration plate is formed on the surface of the piezoelectric element by a plating method, and the piezoelectric element of the vibration plate is opposite to the piezoelectric element. A method of manufacturing a piezoelectric actuator, wherein an ink pressure chamber is formed on a surface of a side surface of the vibrating plate, wherein a protective layer made of an ink resistant material is provided on at least a region of the surface of the vibration plate opposite to the piezoelectric element, exposed in the ink pressure chamber. Is formed.

When the method for manufacturing the piezoelectric actuator of the ink jet type printer head has such a structure, the vibrating plate is formed on the surface of the piezoelectric element by the plating method, so that the bonding property of the vibrating plate to the surface of the piezoelectric element becomes good. . In addition, since the ink-contacting surface area of the piezoelectric element and the vibrating plate is covered with the protective layer made of the ink-resistant material, the vibrating plate formed by the plating method is eroded by coming into contact with the ink in the ink pressure chamber. There is no such thing. Therefore, the material of the diaphragm can be arbitrarily selected, so that the cost can be reduced. Further, since the diaphragm formed by the plating method is covered with the protective layer, even if a pinhole is generated in the diaphragm, the pinhole will be hidden from the ink by the protective layer. Therefore, it is not necessary to select the thickness of the diaphragm so as to be pinhole-free, and it is easy to make the diaphragm thin and increase the efficiency of the characteristics of the piezoelectric actuator.

According to a sixth aspect of the present invention, there is provided a method of manufacturing a piezoelectric actuator for an ink jet printer head, wherein the step of forming the protective layer is performed after the ink pressure chamber is formed. When the method for manufacturing the piezoelectric actuator of the inkjet printer head has such a configuration, the protective layer does not exist between the pressure chamber plate that defines the ink pressure chamber and the piezoelectric element, so that the variation in thickness is further reduced. It can be reduced.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a piezoelectric actuator of an ink jet printer head, wherein a piezoelectric element member having a thickness larger than a final predetermined thickness is used as the piezoelectric element, and after forming a pressure chamber, the piezoelectric element is formed. The configuration includes a step of processing the member to a predetermined thickness to form a piezoelectric element. If the method for manufacturing a piezoelectric actuator of an ink jet printer head is configured in this way, the piezoelectric element member is relatively thick when forming the pressure chamber, so the strength of the piezoelectric element member is high and the workability of forming the pressure chamber is high. Will be improved.

In the method of manufacturing a piezoelectric actuator of an ink jet printer head according to an eighth aspect, the step of forming the ink pressure chamber includes a first step of joining the pressure chamber plate to the piezoelectric element, and the pressure chamber plate. And a second step of forming a concave portion to be a pressure chamber. In the method for manufacturing a piezoelectric actuator of an ink jet printer head according to claim 9, the step of processing the piezoelectric element member to a predetermined thickness is performed after the first step and in the second step. It is a configuration that is performed before. When the method for manufacturing the piezoelectric actuator of the ink jet printer head has such a configuration, when the piezoelectric element member is processed to have a predetermined thickness, the pressure chamber plate has no recessed portion to be a pressure chamber. Chamber plate strength is high. Therefore, the workability of the piezoelectric element member is improved.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a piezoelectric actuator for an ink jet printer head, wherein in the second step, the recess is formed by using the protective layer as a stopper during processing. When the method of manufacturing the piezoelectric actuator of the ink jet printer head has such a structure, when the recess is formed in the pressure chamber plate, the diaphragm exposed in the recess is covered with the protective layer, and thus the diaphragm is processed. There is no such thing as hurt.

According to the eleventh aspect of the present invention, there is provided a method of manufacturing a piezoelectric actuator for an ink jet printer head, wherein a plurality of piezoelectric elements are integrally formed, and after the step of forming the protective layer, the piezoelectric element is made of ink. Corresponding to the pressure chamber, the vibration plate and the protective layer are used as stoppers and separated into individual piezoelectric elements by blasting. When the method for manufacturing the piezoelectric actuator of the ink jet printer head is configured as described above, each piezoelectric element is integrally formed with each other before the individual piezoelectric elements are separated from each other. Therefore, the positioning with respect to the ink pressure chamber is facilitated. Can be done.

According to a twelfth aspect of the present invention, there is provided a method of manufacturing a piezoelectric actuator for an ink jet printer head, wherein the step of forming the vibration plate is performed after the step of forming the ink pressure chamber. When the method of manufacturing the piezoelectric actuator of the ink jet printer head has such a structure, the vibrating plate is formed only in the region exposed in the ink pressure chamber of the piezoelectric element.

Further, in the method of manufacturing a piezoelectric actuator for an ink jet printer head according to a thirteenth aspect, before the step of forming the vibration plate, a trigger for forming the vibration plate on the surface of the piezoelectric element by a plating method is used. The structure includes a step of forming a seed layer that becomes If the method for manufacturing the piezoelectric actuator of the ink jet printer head has such a structure, when the vibration plate is formed by the plating method, the seed layer is formed on the surface of the piezoelectric element. The adhesion of the plate to the surface of the piezoelectric element is improved.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First, a printer head manufactured by an embodiment of a method for manufacturing a piezoelectric actuator of an ink jet printer head according to the present invention will be described with reference to the perspective view shown in FIG. As shown in FIG. 1, the printer head 10 is configured such that a vibration plate is formed on the surface of a piezoelectric element by a plating method and the unimorph effect is used to eject ink droplets. That is, the printer head 10 is configured by sequentially stacking the nozzle plate 20, the ink pool plate 30, the ink supply plate 40, the pressure chamber plate 50, the protective layer 60, the vibration plate 70, and the piezoelectric element 80 from the bottom. There is.

The nozzle plate 20 is provided with a plurality of aligned nozzles 21 for ejecting ink. The ink pool plate 30 includes a plurality of ink communicating portions 31 provided corresponding to the nozzles 21 of the nozzle plate 20, and one ink pool 32 provided around the ink communicating portions 31. Is equipped with.

Similarly, the ink supply plate 40 is
A plurality of ink communicating portions 41 provided corresponding to each nozzle 21 of the nozzle plate 20 and each ink communicating portion 4
1, a plurality of ink supply ports 42 opening to the ink pool 31 of the ink pool plate 30, and at one end, the ink pool 3 of the ink pool plate 30.
1 and an ink suction port (not shown) that opens at 1.

The pressure chamber plate 50 is made of, for example, stainless steel SUS304, and has a plurality of pressure chambers 51 for communicating the respective ink communication portions 41 of the ink supply plate 40 with the corresponding ink supply ports 42, An ink suction port (not shown) communicating with the ink suction port of the ink supply plate 40 is provided at one end.

The protective layer 60 is made of a polymer material having ink resistance formed on the surface (lower surface in the case shown) of the vibration plate 70.

The vibrating plate 70 is composed of a thin film formed on the surface of the piezoelectric element by a plating method and has an ink suction port (not shown) communicating with the ink suction port of the pressure chamber plate 50. . A plurality of the piezoelectric elements 80 are arranged so as to face the pressure chambers 51 of the pressure chamber plate 50 with the diaphragm 70 interposed therebetween.

Here, the printer head 10 having such a configuration is manufactured as shown in each step of FIG. 2 by the first embodiment of the method of manufacturing the piezoelectric piezoelectric actuator according to the present invention.

First, as shown in FIG. 2A, a piezoelectric element member 90 is prepared. The piezoelectric element member 90 is selected to have an appropriate thickness. From the viewpoint of handling in manufacturing (eg, sputtering, plating, etc.), it is desirable that this thickness be appropriately thick with respect to the external dimensions and material of the piezoelectric element, but the piezoelectric element is finally polished to a predetermined thickness. In order to process into a large size, it is desirable that the thickness is thin so that the time required for processing is shortened. Thereby, the piezoelectric element member 90
For example, N-10 (external dimensions 60 mm × 30 mm × 0.3 t) manufactured by Tokin Co., Ltd. is used.

Then, as shown in FIG. 2B, a metal layer 91 to be a lower electrode is formed on the lower surface of the piezoelectric element member 90. Since this metal layer 91 is used as a metal layer that triggers the plating growth when forming the diaphragm by the plating method described later, it is desirable to select it in consideration of the adhesion to the diaphragm. Since the metal layer 91 is activated before plating the diaphragm, the thickness of the metal layer 91 is selected to be an appropriate thickness after the activation treatment. Further, the metal layer 91 may be formed by laminating, for example, two or more kinds of metal layers in order to secure the adhesion to the piezoelectric element member 90. Therefore, the metal layer 9
1 is composed of Cr having a thickness of 50 nm and Cu having a thickness of 300 nm by, for example, a sputtering method.

Subsequently, as shown in FIG. 2C, the metal layer 9 is used as a seed layer by a plating method.
A vibration plate 70 is formed on the lower surface of 1. This diaphragm 70
Is determined from the required thickness of the piezoelectric element, the material of the vibration plate, etc., and is selected to be about 20 to 50% of the thickness of the piezoelectric element for reasons such as improvement in deformation efficiency. . Therefore, the diaphragm 70 is formed of, for example, an electroless Ni plating film having a thickness of 10 μm.

Next, as shown in FIG.
A protective layer 60 is formed on the lower surface of 0. This protective layer 60
Is formed, for example, by applying a liquid polymer material to the lower surface of the diaphragm 92 and then curing the polymer by heat treatment. Specifically, for example, a liquid containing a thermoplastic polyimide as a main component is applied to the lower surface of the diaphragm 92 by a spin coating method, and a temporary cure is performed by heat treatment (150 ° C./1 hour). Here, if the thickness of the protective layer 60 is too thin, pinholes are generated and the effect of the protective layer 60 is impaired, and if it is too thick, the deformation efficiency of the actuator decreases, so an appropriate thickness, For example, it is selected to be 10 μm.

Thereafter, as shown in FIG. 2E, the pressure chamber plate 50 is bonded to the lower surface of the protective layer 60. Here, since the protective layer 60 is a thermoplastic polyimide, by stacking the pressure chamber plate 50 on the lower surface of the protective layer 60, for example, by heating and pressurizing under a condition of a pressure of 0.5 MPa and 250 ° C./1 hour. The pressure chamber plate 50 will be joined.

Then, as shown in FIG. 2F, from the surface (upper surface) of the piezoelectric element member 90 opposite to the vibration plate 70,
Processing is performed by polishing to a predetermined thickness. here,
The predetermined thickness of the piezoelectric element member 90 is determined based on the characteristics required for the piezoelectric actuator. If the thickness is thin, a large deformation can be obtained, but it is necessary to have a thickness that does not impair the characteristics of the piezoelectric element itself. Therefore,
For example, in the case of the piezoelectric element member 90 using N-10 described above, the thickness is selected to be 30 μm, for example.

Next, as shown in FIG. 2G, an upper electrode 92 is formed on the polished upper surface of the piezoelectric element member 90. The upper electrode 92 is selected to have a thickness that can sufficiently withstand the voltage and current used.
When it is electrically connected to the outside through the, it is necessary to be able to withstand the conditions of the electrical connection. Therefore, the upper electrode 92
Is composed of Cr having a thickness of 50 nm, Ni having a thickness of 600 nm, and Au having a thickness of 200 nm, for example, by a sputtering method.

Thereafter, as shown in FIG. 2H, the piezoelectric element member 90 is separated into individual piezoelectric elements 80 corresponding to each pressure chamber 51 of the pressure chamber plate 50 from above by, for example, blasting. , Individualize. As a result, the piezoelectric actuator is completed.

Further, the ink jet printer head 10 is completed by positioning and joining the piezoelectric actuator thus completed, the ink supply plate 40, the ink pool plate 30, and the nozzle plate 20 to each other. Become.

Next, the operation of the ink jet printer head 10 manufactured according to this embodiment will be described. When a drive voltage is applied to the piezoelectric element 80 based on the print command, the piezoelectric element 80 and the vibration plate 70 are deformed toward the corresponding pressure chamber 51 of the ink pressure chamber plate 50. As a result, the ink in the pressure chamber 51 is ejected from the nozzle 21 of the nozzle plate 20.

In this case, the diaphragm 7 corresponding to the pressure chamber 51
Since the surface of 0 is covered with the protective layer 60, the vibrating plate 70 does not come into direct contact with the ink in the pressure chamber 51.
The diaphragm 70 is not eroded by the ink. Therefore, the diaphragm 70 can be made of any material without considering ink resistance. As a result, the cost of the diaphragm 70 can be reduced, and the efficiency of the characteristics of the piezoelectric actuator can be improved.

FIG. 3 shows a second embodiment of a method of manufacturing an ink jet printer head according to the present invention, and the printer head is manufactured as shown in each step of FIG.

First, as shown in FIG. 3A, similarly to the case shown in FIG. 2, a piezoelectric element member 90 having an appropriate thickness, that is, a thickness larger than a final predetermined thickness is prepared.
As shown in (B), a metal layer 91 to be a lower electrode is formed on the lower surface of the piezoelectric element member 90.

Subsequently, as shown in FIG. 3C, the metal layer 9 is used as a seed layer by a plating method.
A vibration plate 70 is formed on the lower surface of 1. After that, FIG.
As shown in (D), an adhesive is applied to the lower surface of the vibration plate 70 to bond the pressure chamber plate 50 to the lower surface of the vibration plate 70.

Subsequently, as shown in FIG. 3E, from the surface (upper surface) of the piezoelectric element member 90 opposite to the vibration plate 70,
By polishing processing to a predetermined thickness, after that,
As shown in FIG. 3F, the upper electrode 92 is formed on the polished upper surface of the piezoelectric element member 90.

Next, as shown in FIG. 3G, the piezoelectric element member 90 is separated into individual piezoelectric elements 80 corresponding to each pressure chamber 51 of the pressure chamber plate 50 from above by, for example, blasting. And individualize. Finally, as shown in FIG. 3H, the protective layer 60 is formed from below. In this case, the protective layer 60 is formed, for example, by applying a liquid polymer material by a spray method and then curing the polymer by heat treatment. Thereby, the protective layer 60 is
The inner wall of each pressure chamber 51 of the pressure chamber plate 50 and the surface of the vibration plate 70 exposed to this pressure chamber 51 are covered.

Further, the ink jet printer head 10 is completed by positioning and joining the piezoelectric actuator thus completed, the ink supply plate 40, the ink pool plate 30, and the nozzle plate 20 to each other. Become.

In this case, as in the case of the piezoelectric actuator and the ink jet printer head shown in FIGS. 1 and 2, the vibrating plate 70 does not come into contact with the ink in the pressure chamber 51 of the pressure chamber plate 50. Further, in this case, since the protective layer 60 does not exist between the vibrating plate 70 and the pressure chamber plate 50, it is possible to further reduce the variation in the thickness in the lapping process and the variation in the characteristics of the piezoelectric actuator. can do.

FIG. 4 shows a third embodiment of the method for manufacturing an ink jet printer head according to the present invention, and the printer head is manufactured as shown in each step of FIG.

First, as shown in FIG. 4A, similarly to the case shown in FIG. 2, a piezoelectric element member 90 having an appropriate thickness, that is, a thickness larger than a final predetermined thickness is prepared.
As shown in (B), an adhesive (not shown) is applied to the lower surface of the piezoelectric element member 90, and the lower surface of the piezoelectric element member 90 is
The pressure chamber plate 50 is joined.

Next, as shown in FIG. 4C, a metal layer 91 to be a lower electrode is formed on the lower surface of the piezoelectric element member 90. Subsequently, as shown in FIG. 4D, a diaphragm 70 is formed on the lower surface of the metal layer 91 by a plating method using the metal layer 91 as a seed layer.

Thereafter, as shown in FIG. 4E, a protective layer 60 is formed from below. In this case, the protective layer 60 is
For example, a Ni plating film having a thickness of 7 μm and an Au plating film having a thickness of 3 μm are sequentially laminated by a plating method. As a result, the portion of the protective layer 60 exposed on the surface is covered with Au having ink resistance.

Next, as shown in FIG. 4F, the surface (upper surface) of the piezoelectric element member 90 opposite to the pressure chamber plate 50.
From the above to a predetermined thickness by polishing, and thereafter, as shown in FIG. 4G, the upper electrode 92 is formed on the polished upper surface of the piezoelectric element member 90.

Finally, as shown in FIG. 4H, the piezoelectric element member 90 is separated into individual piezoelectric elements 80 corresponding to each pressure chamber 51 of the pressure chamber plate 50 from above by, for example, blasting. And individualize. Thereby, the piezoelectric actuator is completed.

Further, the ink jet printer head 10 is completed by positioning and joining the piezoelectric actuator thus completed with the ink supply plate 40, the ink pool plate 30, and the nozzle plate 20. Become.

In this case, as in the case of the piezoelectric actuator and the ink jet printer head shown in FIGS. 1 and 2, the vibrating plate 70 does not come into contact with the ink in the pressure chamber 51 of the pressure chamber plate 50. Further, in this case, the protective layer 60 has a surface area A having ink resistance.
It is covered with the u-plated film, and the portion other than the surface region is formed with the Ni-plated film. This allows
The surface of the protective layer 60 has ink resistance, and more of the protective layer 60 is composed of a low-cost Ni plating film.

In the above-described embodiment, the pressure chamber plate 50 is configured to be joined in the state where the pressure chamber 51 is formed. However, the present invention is not limited to this, and the pressure chamber plate 50 may be joined in a state before the pressure chamber 51 is formed. , Bonded to the piezoelectric element member 90,
The pressure chamber 51 may be formed after the piezoelectric element member 90 is ground to a predetermined thickness. In this case, when the piezoelectric element member 90 is polished, the piezoelectric element member 90 is reinforced by the pressure chamber plate 50 without the pressure chamber 51, and the workability of the piezoelectric element member 90 is improved. become.

[0071]

As described above, according to the present invention, since the vibration plate is formed on the surface of the piezoelectric element by the plating method, the bonding property of the vibration plate to the surface of the piezoelectric element becomes good. In addition, since the ink-contacting surface area of the piezoelectric element and the vibrating plate is covered with the protective layer made of the ink-resistant material, the vibrating plate formed by the plating method is eroded by coming into contact with the ink in the ink pressure chamber. There is no such thing. Therefore, the material of the diaphragm can be arbitrarily selected, so that the cost can be reduced. Further, since the diaphragm formed by the plating method is covered with the protective layer, even if a pinhole is generated in the diaphragm, the pinhole will be hidden from the ink by the protective layer. Therefore, it is not necessary to select the thickness of the diaphragm so as to be pinhole-free, and it is easy to make the diaphragm thin and increase the efficiency of the characteristics of the piezoelectric actuator.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic perspective view showing the configuration of an embodiment of an inkjet printer head according to the present invention.

FIG. 2 is a process chart sequentially showing each process of the first embodiment of the manufacturing process of the piezoelectric actuator of the ink jet printer head according to the present invention.

FIG. 3 is a process diagram sequentially showing each process of the second embodiment of the manufacturing process of the piezoelectric actuator of the inkjet printer head according to the present invention.

FIG. 4 is a process diagram sequentially showing each process of the third embodiment of the manufacturing process of the piezoelectric actuator of the inkjet printer head according to the present invention.

FIG. 5 is an exploded perspective view showing the configuration of an example of a conventional inkjet printer head.

6 is a partially cutaway schematic perspective view showing the inkjet printer head of FIG.

7 is an enlarged cross-sectional view taken along the line AA of FIG. 6 showing (a) an initial state and (b) an operating state of the piezoelectric actuator of the inkjet printer head of FIG.

8 is an enlarged cross-sectional view taken along line BB of FIG. 6 showing (a) an initial state of the piezoelectric actuator of the ink jet printer head of FIG. 5, (b) an ink ejection state, and (c) an ink filling state. .

[Explanation of symbols]

10 Inkjet printer head 20 nozzle plate 21 nozzles 30 ink pool plate 31 Ink communication part 32 ink pool 40 ink supply plate 41 Ink communication part 42 Ink supply port 50 pressure chamber plate 51 Pressure chamber 60 protective layer 70 diaphragm 80 Piezoelectric element 90 Piezoelectric element member 91 Metal layer (lower electrode) 92 Upper electrode

Claims (13)

[Claims] 1. A piezoelectric actuator for an ink jet printer head, wherein a piezoelectric element is used to deform a vibrating plate forming a part of an inner wall of an ink pressure chamber to control the pressure in the ink pressure chamber and eject ink from a nozzle. The vibrating plate is formed on the surface of the piezoelectric element by a plating method, and at least the surface region of the vibrating plate that comes into contact with the ink is
A piezoelectric actuator for an inkjet printer head, comprising a protective layer made of an ink resistant material. 2. The piezoelectric actuator for an ink jet printer head according to claim 1, wherein the protective layer is made of a polymer film. 3. The piezoelectric actuator of an ink jet printer head according to claim 1, wherein the protective layer is formed by a plating method. 4. The ink jet method according to claim 1, wherein a seed layer serving as a trigger is formed on the surface of the piezoelectric element before the vibration plate is formed by the plating method. Piezoelectric actuator for printer head. 5. A piezoelectric actuator of an ink jet printer head, which controls a pressure in an ink pressure chamber by deforming a vibrating plate constituting a part of an ink pressure chamber inner wall by a piezoelectric element to eject ink from a nozzle. A method of manufacturing a piezoelectric actuator, wherein a vibration plate is formed on a surface of an element by a plating method, and an ink pressure chamber is formed on a surface of the vibration plate opposite to a piezoelectric element, wherein the piezoelectric element of the vibration plate is A method of manufacturing a piezoelectric actuator for an ink jet printer head, comprising a step of forming a protective layer made of an ink resistant material on at least an area of the opposite surface exposed in the ink pressure chamber. 6. The method for manufacturing a piezoelectric actuator of an ink jet printer head according to claim 5, wherein the step of forming the protective layer is performed after the ink pressure chamber is formed. 7. A step of forming a piezoelectric element by using a piezoelectric element member thicker than a final predetermined thickness as the piezoelectric element, forming a pressure chamber, and processing the piezoelectric element member to a predetermined thickness. 7. The method for manufacturing a piezoelectric actuator of an ink jet printer head according to claim 5, wherein the piezoelectric actuator includes the piezoelectric actuator. 8. The step of forming the ink pressure chamber comprises a first step of joining the pressure chamber plate to the piezoelectric element and a second step of forming a concave portion to be the pressure chamber in the pressure chamber plate. A method for manufacturing a piezoelectric actuator for an ink jet printer head according to any one of claims 5 to 7, characterized in that. 9. The process according to claim 8, wherein the step of processing the piezoelectric element member to a predetermined thickness is performed after the first step and before the second step. Of manufacturing a piezoelectric actuator for an ink jet printer head. 10. The piezoelectric actuator for an ink jet printer head according to claim 8, wherein the recess formed in the second step is formed by using the protective layer as a stopper during processing. Manufacturing method. 11. A plurality of piezoelectric elements are integrally configured, and after the step of forming a protective layer, the piezoelectric element corresponds to the ink pressure chamber, and the diaphragm and the protective layer serve as stoppers. 11. The method for manufacturing a piezoelectric actuator for an inkjet printer head according to claim 5, wherein the piezoelectric element is separated into individual piezoelectric elements by blasting. 12. A piezoelectric actuator for an ink jet printer head according to claim 5, wherein the step of forming the vibration plate is performed after the step of forming the ink pressure chamber. Method. 13. The method, before the step of forming the diaphragm, includes a step of forming a seed layer on the surface of the piezoelectric element as a trigger when the diaphragm is formed by a plating method. Item 13. A method of manufacturing a piezoelectric actuator for an inkjet printer head according to any one of Items 5 to 12.