JP2000272124A - Actuator device and its manufacture and ink jet type recording head and ink jet type recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator device and its manufacture and an ink jet type recording head and an ink jet type recording apparatus in which breakdown of a piezoelectric layer is prevented. SOLUTION: An end part of a lower electrode 60 becomes an end part of a piezoelectric active part 320 which is substantially a driving part of a piezoelectric element 300. A thickness decrease part 61 where a thickness of the lower electrode 60 gradually decreases is set to the end part of the lower electrode 60 outwards the piezoelectric active part 320, so that a reduction in film thickness of a piezoelectric layer 70 at the end part of the lower electrode 60 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator device having a piezoelectric element which is displaced by applying a voltage to a piezoelectric material layer and a method of manufacturing the same, and more particularly to a pressure generating chamber communicating with a nozzle opening for discharging ink droplets. The present invention relates to an ink jet recording head and an ink jet recording apparatus in which a part is formed by a vibration plate, a piezoelectric element is formed on the surface of the vibration plate, and an ink droplet is ejected by displacement of the piezoelectric element.

[0002]

2. Description of the Related Art A part of a pressure generating chamber communicating with a nozzle opening for discharging ink droplets is constituted by a vibrating plate, and the vibrating plate is deformed by a piezoelectric element to pressurize the ink in the pressure generating chamber to pass through the nozzle opening. Two types of ink jet recording heads that eject ink droplets have been commercialized, one using a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of the piezoelectric element, and the other using a flexural vibration mode piezoelectric actuator. ing.

In the former method, the volume of the pressure generating chamber can be changed by bringing the end face of the piezoelectric element into contact with the diaphragm, so that a head suitable for high-density printing can be manufactured. There is a problem in that a difficult process of cutting into a comb shape in accordance with the arrangement pitch of the openings and an operation of positioning and fixing the cut piezoelectric element in the pressure generating chamber are required, and the manufacturing process is complicated.

On the other hand, in the latter, a piezoelectric element can be formed on a diaphragm by a relatively simple process of sticking a green sheet of a piezoelectric material according to the shape of a pressure generating chamber and firing the green sheet. In addition, there is a problem that a certain area is required due to the use of flexural vibration, and that high-density arrangement is difficult.

On the other hand, in order to solve the latter disadvantage of the recording head, a uniform piezoelectric material layer is formed by a film forming technique over the entire surface of the diaphragm as disclosed in Japanese Patent Application Laid-Open No. 5-286131. A proposal has been made in which the piezoelectric material layer is cut into a shape corresponding to the pressure generating chambers by a lithography method, and a piezoelectric element is formed so as to be independent for each pressure generating chamber.

This eliminates the need for attaching the piezoelectric element to the vibration plate, which not only allows the piezoelectric element to be manufactured by a precise and simple method such as lithography, but also reduces the thickness of the piezoelectric element. There is an advantage that it can be made thin and can be driven at high speed.

Further, in this case, the piezoelectric element corresponding to each pressure generating chamber can be driven by providing at least only the upper electrode for each pressure generating chamber while the piezoelectric material layer is provided on the entire surface of the vibration plate. However, due to the problem of the amount of displacement per unit drive voltage and the stress applied to the piezoelectric layer at the part facing the pressure generating chamber and the part straddling the outside, the piezoelectric layer and the upper electrode constituting the piezoelectric active part are However, it is desirable to form the pressure generating chamber so as not to go out of the pressure generating chamber as much as possible.

Therefore, after patterning the lower electrode,
A structure has been proposed in which a piezoelectric element is formed by forming and patterning a piezoelectric layer and an upper electrode, and the piezoelectric layer and the upper electrode are extended from one end to a peripheral wall.

[0009]

However, in the above structure, the piezoelectric layer is usually formed on the patterned lower electrode by a wet method such as a sol-gel method or a sputtering method. The piezoelectric layer near the end of the electrode is formed thinner than other portions. When a voltage is applied in this state, the electric field intensity increases in a thin portion of the piezoelectric layer, and there is a problem that dielectric breakdown occurs.

In view of such circumstances, an object of the present invention is to provide an actuator device which prevents dielectric breakdown of a piezoelectric layer, a method of manufacturing the same, and an ink jet recording head and an ink jet recording device.

[0011]

According to a first aspect of the present invention, there is provided a lower electrode provided on one side of a substrate with an insulating layer interposed therebetween, and a piezoelectric member provided on the lower electrode. In the piezoelectric element comprising a layer and an upper electrode provided on the surface of the piezoelectric layer, an end of the lower electrode is an end of a piezoelectric active part which is a substantial driving part of the piezoelectric element, and the lower electrode The actuator device is characterized in that a thinner portion in which the thickness of the lower electrode gradually decreases toward the outside of the piezoelectric active portion is provided at an end of the actuator.

In the first aspect, since the film thickness is gradually reduced at the end of the lower electrode, the thickness of the piezoelectric layer formed near the end of the lower electrode does not become thin. In addition, dielectric breakdown near the end of the piezoelectric active portion is prevented.

According to a second aspect of the present invention, in the first aspect, the tapered portion has an inclined surface in which the thickness of the lower electrode is gradually reduced. In the actuator device.

In the second aspect, the piezoelectric layer is formed along the inclined surface of the portion having a gradually decreasing thickness, so that the thickness of the piezoelectric layer at the end of the piezoelectric active portion does not become thin.

[0015] A third aspect of the present invention is the actuator device according to the first aspect, characterized in that the thickness of the lower electrode is gradually reduced in a step-like manner. .

In the third aspect, the piezoelectric layer is formed along the shape of the portion having the gradually decreasing thickness, and has substantially the same thickness as the other portions.

According to a fourth aspect of the present invention, in the first aspect, the tapered portion has an inclined curved surface in which the thickness of the lower electrode is continuously reduced. In the actuator device.

In the fourth aspect, the piezoelectric layer is formed along the shape of the portion having a gradually decreasing thickness, and has a thickness substantially equal to that of the other portions.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the thickness of the piezoelectric layer formed on the tapered portion is smaller than the thickness of the other portions. Actuator device characterized in that it is also thick.

In the fifth aspect, there is no electric field concentration in the piezoelectric layer near the end of the piezoelectric active portion, and dielectric breakdown is prevented.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the piezoelectric element is provided in a region corresponding to a pressure generating chamber formed in the substrate, and The actuator device is characterized in that an end is located inside a peripheral wall in the pressure generating chamber.

In the sixth aspect, the driving of the piezoelectric active portion is not hindered, and the dielectric breakdown of the piezoelectric layer is prevented.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the piezoelectric layer and the upper electrode extend to the same position as the end of the lower electrode or to the outside thereof. An actuator device is characterized in that:

In the seventh aspect, the upper electrode and the lower electrode are reliably insulated from each other, and the dielectric breakdown of the piezoelectric layer near the end of the piezoelectric active portion can be reliably prevented.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the lower portion is further provided outside the piezoelectric layer provided outside the end portion of the tapered portion. The actuator device is characterized in that a lower electrode for wiring, which is provided discontinuously with the electrode and whose one end is connected to an external wiring, is provided for each of the piezoelectric elements.

In the eighth aspect, the lower electrode and the lower electrode for wiring are reliably insulated by the piezoelectric layer, and the wiring can be easily formed.

A ninth aspect of the present invention is the actuator device according to any one of the first to eighth aspects, wherein the lower electrode is provided continuously over a plurality of adjacent piezoelectric elements. .

In the ninth aspect, the rigidity of the lower electrode is improved, and the durability is improved.

A tenth aspect of the present invention is the actuator device according to any one of the first to ninth aspects, wherein the lower electrode is patterned for each piezoelectric element.

In the tenth aspect, the amount of displacement caused by driving the piezoelectric active portion is improved.

An eleventh aspect of the present invention is a flow path forming substrate which defines a pressure generating chamber in which the substrate of the actuator device according to any one of the first to tenth aspects communicates with a nozzle opening. A nozzle forming substrate having the nozzle opening is joined to the other surface of the forming substrate.

According to the eleventh aspect, it is possible to realize an ink jet recording head capable of discharging ink satisfactorily from a nozzle opening by driving a piezoelectric element.

According to a twelfth aspect of the present invention, in the eleventh aspect, the pressure generation chamber is formed by anisotropic etching on a silicon single crystal substrate, and each layer of the piezoelectric element is formed by a thin film and a lithography method. An ink jet recording head is characterized in that:

In the twelfth aspect, an ink jet recording head having high-density nozzle openings can be manufactured in a large amount and relatively easily.

A thirteenth aspect of the present invention is directed to the eleventh or twelfth aspect.
An ink jet recording apparatus comprising the ink jet recording head according to the above aspect.

According to the thirteenth aspect, it is possible to realize an ink jet recording head with improved head reliability.

According to a fourteenth aspect of the present invention, a lower electrode layer, a piezoelectric layer and an upper electrode layer are sequentially laminated on a substrate with an insulating layer interposed therebetween, and each layer is patterned. A method for forming a piezoelectric element comprising the upper electrode layer, wherein the lower electrode layer is formed and patterned to a position corresponding to a region to be an end of a piezoelectric active portion of the piezoelectric element. A first step of forming a tapered portion where the thickness of the lower electrode layer is gradually reduced, and forming the piezoelectric layer and the upper electrode layer thereon and patterning them to form the piezoelectric element And a second step of manufacturing the actuator device.

In the fourteenth aspect, the piezoelectric layer is formed with a substantially uniform thickness on the lower electrode layer including the gradually decreasing thickness.

According to a fifteenth aspect of the present invention, in the fourteenth aspect, in the first step, a resist film having substantially the same shape as the shape of the gradually decreasing thickness is formed at an end of the lower electrode layer. And forming the tapered portion by patterning.

In the fifteenth aspect, the piezoelectric layer is formed along the shape of the gradually decreasing portion of the thick film, and the thickness of the piezoelectric layer and the thickness of the other portions become more uniform.

According to a sixteenth aspect of the present invention, in the fourteenth aspect, in the first step, at least a region on the insulating layer to be the film thickness decreasing portion on the insulating layer is covered with a mask, and the lower portion is formed by mask evaporation. An electrode device is deposited on a predetermined region.

In the sixteenth aspect, the tapered portion having a cross section of an inclined curved surface is relatively easily formed.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.

(Embodiment 1) FIG. 1 is an exploded perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a plan view thereof and a cross section of one pressure generating chamber in the longitudinal direction. FIG.

As shown in the figure, the flow path forming substrate 10 is made of a silicon single crystal substrate having a plane orientation (110) in this embodiment. As the flow path forming substrate 10, usually 150 to 3
A thickness of about 00 μm is used.
Those having a thickness of about 0 to 280 μm, more preferably about 220 μm are suitable. This is because the arrangement density can be increased while maintaining the rigidity of the partition wall between the adjacent pressure generating chambers.

One surface of the flow path forming substrate 10 is an opening surface, and the other surface is formed with a 1-2 μm thick elastic film 50 made of silicon dioxide previously formed by thermal oxidation.

On the other hand, the opening surface of the flow path forming substrate 10 is anisotropically etched on a silicon single crystal substrate,
A nozzle opening 11 and a pressure generating chamber 12 are formed.

Here, in the anisotropic etching, when the silicon single crystal substrate is immersed in an alkali solution such as potassium hydroxide, the substrate is gradually eroded and becomes the first (1) perpendicular to the (110) plane.
An (11) plane and a second (111) plane which forms an angle of about 70 degrees with the first (111) plane and forms an angle of about 35 degrees with the (110) plane appear, and (110) This is performed by utilizing the property that the etching rate of the (111) plane is about 1/180 compared to the etching rate of the plane. By such anisotropic etching, precision processing can be performed based on the depth processing of a parallelogram formed by two first (111) planes and two oblique second (111) planes. , The pressure generating chambers 12 can be arranged at a high density.

In this embodiment, the long side of each pressure generating chamber 12 is formed by the first (111) plane, and the short side is formed by the second (111) plane. The pressure generating chamber 12 is provided on the flow path forming substrate 1.
It is formed by etching until it reaches the elastic film 50 almost through 0. The amount of the elastic film 50 that is attacked by the alkaline solution for etching the silicon single crystal substrate is extremely small.

On the other hand, each nozzle opening 11 communicating with one end of each pressure generating chamber 12 is formed to be narrower and shallower than the pressure generating chamber 12. That is, the nozzle opening 11 is formed by partially etching (half-etching) the silicon single crystal substrate in the thickness direction. In addition,
Half etching is performed by adjusting the etching time.

Here, the size of the pressure generating chamber 12 for applying the ink droplet ejection pressure to the ink and the size of the nozzle opening 11 for ejecting the ink droplet depend on the amount of the ejected ink droplet, the ejection speed, and the ejection frequency. Optimized. For example,
When recording 360 ink droplets per inch, the nozzle openings 11 need to be formed with a groove width of several tens of μm with high accuracy.

Further, each pressure generating chamber 12 and a common ink chamber 31 described later are connected to each pressure generating chamber 1 of the sealing plate 20 described later.
The ink is supplied from a common ink chamber 31 through the ink supply communication port 21 formed at a position corresponding to one end of the pressure generation chamber 12. Distributed to

The sealing plate 20 is provided with an ink supply communication port 21 corresponding to each of the pressure generating chambers 12 and has a thickness of, for example, 0.1 to 1 mm and a linear expansion coefficient of 300 ° C. or less. , For example, 2.5-4.5 [× 10 ⁻⁶ / ° C.]. In addition, the ink supply communication port 21
Each of the pressure generating chambers 1 is, as shown in FIGS.
It may be one slit hole 21A crossing the vicinity of the second ink supply side end or a plurality of slit holes 21B. The sealing plate 20 is provided on one side with the flow path forming substrate 10.
, And also serves as a reinforcing plate for protecting the silicon single crystal substrate from impacts and external forces. Also, sealing plate 2
0 forms one wall surface of the common ink chamber 31 on the other surface.

The common ink chamber forming substrate 30 forms the peripheral wall of the common ink chamber 31, and is formed by punching a stainless steel plate having an appropriate thickness according to the number of nozzles and the ink droplet ejection frequency. . In the present embodiment, the thickness of the common ink chamber forming substrate 30 is 0.2 mm.

The ink chamber side plate 40 is made of a stainless steel substrate, and one surface thereof constitutes one wall surface of the common ink chamber 31. In the ink chamber side plate 40, a thin wall 41 is formed by forming a concave portion 40a by half etching on a part of the other surface, and an ink introduction port 42 for receiving ink supply from the outside is punched and formed. ing. The thin wall 41 is for absorbing pressure generated at the time of ink droplet ejection toward the side opposite to the nozzle opening 11, and is unnecessary for the other pressure generating chambers 12 via the common ink chamber 31. Prevents positive or negative pressure from being applied.
In the present embodiment, the ink chamber side plate 40 is made 0.2 mm in consideration of rigidity required at the time of connection between the ink introduction port 42 and an external ink supply means, and a part of the thickness is 0.02 mm.
The thickness of the ink chamber side plate 40 may be 0.02 mm from the beginning in order to omit the formation of the thin wall 41 by half etching.

On the other hand, the thickness of the elastic film 50 on the side opposite to the opening surface of the flow path forming substrate 10 is, for example, about 0.5 μm.
A lower electrode film 60, a piezoelectric film 70 having a thickness of, for example, about 1 μm, and an upper electrode film 80 having a thickness of, for example, about 0.1 μm are formed by lamination in a process to be described later.
0. Here, the piezoelectric element 300 refers to a portion including the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 80. Generally, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric film 70 are patterned for each pressure generating chamber 12. Here, a portion which is constituted by one of the patterned electrodes and the piezoelectric film 70 and in which a piezoelectric strain is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion 320. In the present embodiment, the lower electrode film 60 is used as a common electrode of the piezoelectric element 300 and the upper electrode film 80 is used as an individual electrode of the piezoelectric element 300. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Also, here
The combination of the piezoelectric element 300 and the vibration plate whose displacement is generated by driving the piezoelectric element 300 is referred to as a piezoelectric actuator.

In this embodiment, the piezoelectric active portion 32
The end of the lower electrode film 60 which is the end of the piezoelectric active portion 3
The thickness is gradually reduced toward the outside of the thin film 20. A lead electrode 100 for connecting the upper electrode film 80 and the external wiring is provided from the thinned film thickness portion 61 side. I have.

Here, a process of forming the piezoelectric film 70 and the like on the flow path forming substrate 10 made of a silicon single crystal substrate will be described with reference to FIGS. 4 and 6 are sectional views of the pressure generating chamber 12 in the longitudinal direction, and FIG. 5 is a sectional view of the pressure generating chamber 12 in the width direction.

First, as shown in FIG. 4A, a silicon single crystal substrate wafer serving as the flow path forming
Thermal oxidation is performed in a diffusion furnace at 0 ° C. to form an elastic film 50 made of silicon dioxide.

Next, as shown in FIG. 4B, a lower electrode film 60 is formed by sputtering. Preferable materials for the lower electrode film 60 include platinum, iridium, iridium oxide, and alloys thereof. This is because a piezoelectric film 70 described later, which is formed by a sol-gel method or a sputtering method, is formed at 600 to 1000 ° C. in an air atmosphere or an oxygen atmosphere after the film formation.
This is because it is necessary to perform crystallization by firing at about the same temperature. That is, the material of the lower electrode film 60 must be able to maintain conductivity under such high temperature and oxidizing atmosphere.
In particular, as the piezoelectric film 70, lead zirconate titanate (PZ
When T) is used, it is desirable that the change in conductivity due to the diffusion of lead oxide is small, and for these reasons, platinum, iridium, iridium oxide, or an alloy thereof is preferable.

Next, as shown in FIG. 4C, the lower electrode film 60 is patterned into a predetermined shape for each of the pressure generating chambers 12, and a tapered portion 61 is formed at an end thereof. For example, in the present embodiment, a resist film having substantially the same shape as the tapered portion 61 is formed in a region corresponding to the end of the lower electrode film 60, that is, one end of the resist film is continuously formed. After forming an inclined surface that gradually decreases outward, etching is performed to form a gradually reducing portion 61 having a predetermined shape.
At the same time, the lower electrode film 60 in the region facing the peripheral wall at one end in the longitudinal direction of the pressure generating chamber 12 is patterned to form an independent wiring lower electrode film 62 corresponding to each pressure generating chamber 12.

The method of forming the resist film to have substantially the same shape as the gradually thinning portion 61 is not particularly limited. For example, the resolution of patterning is appropriately changed by adjusting the distance between the mask and the substrate during exposure. Can be formed.

Next, as shown in FIG. 4D, a piezoelectric film 70 is formed. In this embodiment, a so-called sol in which a metal organic substance is dissolved and dispersed in a solvent is applied, dried, and gelled,
Further, the film was formed using a so-called sol-gel method in which a piezoelectric film 70 made of a metal oxide was obtained by firing at a high temperature. As a material of the piezoelectric film 70, a lead zirconate titanate-based material is suitable when used in an ink jet recording head. The method for forming the piezoelectric film 70 is not particularly limited, and may be, for example, a sputtering method.

Further, after forming a precursor film of lead zirconate titanate by a sol-gel method or a sputtering method,
A method of growing crystals at a low temperature by a high-pressure treatment method in an alkaline aqueous solution may be used.

Next, as shown in FIG. 4E, an upper electrode film 80 is formed. The upper electrode film 80 only needs to be a material having high conductivity, and can use many metals such as aluminum, gold, nickel, and platinum, and a conductive oxide. In the present embodiment, platinum is formed by sputtering.

Thereafter, as shown in FIG. 5A, only the piezoelectric film 70 and the upper electrode film 80 are etched to pattern the piezoelectric active portion 320. The above is the film forming process. After the film is formed in this manner, as shown in FIG. 5B, the silicon single crystal substrate is anisotropically etched with the above-described alkali solution to form the pressure generating chamber 12 and the like.

FIG. 6 shows a plan view and a cross section of a main part of the ink jet recording head thus formed.

As shown in FIG. 6, the piezoelectric element 300 including the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 80 is basically patterned in each pressure generating chamber 12 in this embodiment. The piezoelectric active section 320 is provided. on the other hand,
The lower electrode film 60 includes a plurality of adjacent piezoelectric elements 3 arranged in parallel.
The pressure generating chamber 12 is provided continuously over one end of the pressure generating chamber 12, and one end side in the longitudinal direction of the pressure generating chamber 12 is patterned inside a region corresponding to the pressure generating chamber 12.

In the present embodiment, the lower electrode film 6 is provided at the end of the lower electrode film 60 toward the outside of the piezoelectric active portion 320.
There is provided a film thickness gradually decreasing portion 61 in which the film thickness of 0 gradually decreases.
The shape of the tapered portion 61 is not particularly limited. For example, in this embodiment, the lower electrode film 60 has an inclined surface in which the film thickness is gradually reduced.

The lower electrode film 60 is independently patterned for each piezoelectric active part 320 in a region facing the outer peripheral wall of the end of the lower electrode film 60 constituting the piezoelectric active part 320. A wiring lower electrode film 62 used as a wiring of each piezoelectric active part 320 is formed. Then, the upper electrode film 80 and the lower electrode film 62 for wiring are connected by the lead electrode 100 extending through the thin film thickness portion 61 at the end of the lower electrode film 60.

As described above, in the present embodiment, the thickness of the lower electrode film 60 which is the end of the piezoelectric active portion 320 is gradually reduced toward the outside of the piezoelectric active portion 320. The small portion 61 is provided. Thereby, the piezoelectric film 70
Is formed on the lower electrode film 60 including the tapered portion 61.
0, and the entire film thickness is substantially uniform. That is, the thickness of the piezoelectric film 70 at the end of the lower electrode film 60 does not become thin, and dielectric breakdown due to electric field concentration of the piezoelectric film 70 near the end of the piezoelectric active part 320 can be formed. it can.

In the present embodiment, the tapered portion 61 is formed as an inclined surface whose thickness is gradually reduced. However, the present invention is not limited to this. For example, as shown in FIG. As described above, the gradually-thinning portion 61A may be configured such that the thickness thereof is intermittently gradually reduced so that the cross section thereof has a substantially stepped shape. Such a film thickness gradually decreasing portion 6
The method of forming 1A is not particularly limited, either. For example, a resist is applied a plurality of times on the lower electrode film 60, and a region where the lower electrode film 60 becomes the gradually reduced thickness 61A is substantially the same as the gradually reduced thickness portion 61A. After the same step-shaped resist film is formed, the lower electrode film 60 can be formed by patterning.

Further, for example, as shown in FIG.
The cross-section may be a gradually-thinning portion 61B having an inclined curved surface. There is no particular limitation on the method of forming such a gradually decreasing thickness portion 61B. For example, a region on the elastic film 50 where the lower electrode film 60 is not formed and a region to be the gradually decreasing thickness portion 61 are covered with a mask. The lower electrode film 60 is formed by vapor deposition. That is, the lower electrode film 60
A part of the region covered by the mask is also formed so as to extend from the gap of the mask, and the cross section becomes a gradually decreasing thickness 61B of the inclined curved surface. Further, as described above, the lower electrode film 60 can be formed by forming a resist film having substantially the same shape as the tapered portion 61B on the lower electrode film 60 and then patterning the lower electrode film 60.

Further, in this embodiment, the lead electrode 10
0, the upper electrode film 80 is connected to the lower electrode film 62 for wiring. However, the present invention is not limited to this. For example, the piezoelectric film 70 and the upper electrode film 80 The extension may be provided to directly connect the upper electrode film 80 and the lower electrode film 62 for wiring. Further, for example, without providing the lower electrode film 62 for the wiring, the lead electrode 100 may be extended from the upper electrode film 80 to the peripheral wall to connect the lead electrode 100 and the external wiring. The piezoelectric film 70 and the upper electrode film 80 may be extended, and the upper electrode film 80 and the external wiring may be directly connected near the ends.

In this embodiment, the lower electrode film 60 is provided continuously over a plurality of adjacent piezoelectric elements 300. However, the present invention is not limited to this.
Patterning may be performed every 00, and the pressure generating chamber 12 may be drawn outside from the side opposite to the side from which the lead electrode 100 is drawn. In this case, as shown in FIG.
The lower electrode film 60 drawn from each piezoelectric element 300 may be connected on the peripheral wall to form a common electrode, or FIG.
As shown in (b), the upper electrode film 80 drawn from each piezoelectric element 300 may be connected on the peripheral wall to serve as a common electrode, and the lower electrode film 60 may be used as an individual electrode of each piezoelectric element 300.

When the lower electrode film 60 is patterned for each piezoelectric element 300 in this manner, the piezoelectric film 70
May be formed with a width wider than the lower electrode film 60, and the side surfaces at both ends in the width direction of the lower electrode film 60 may be covered with the piezoelectric film 70.

A large number of chips are simultaneously formed on one wafer by a series of film formation and anisotropic etching of the piezoelectric active section 320 and the pressure generating chamber 12 described above, and after the process is completed, FIG. The flow path is divided for each flow path forming substrate 10 of one chip size as shown. Further, the divided flow path forming substrate 10 is divided into a sealing plate 20 and a common ink chamber forming substrate 3.
0 and the ink chamber side plate 40 are sequentially bonded and integrated to form an ink jet recording head.

The ink-jet head thus configured takes in ink from an ink inlet 42 connected to external ink supply means (not shown),
After filling the interior from 1 to the nozzle opening 11 with ink, a voltage is applied between the upper electrode film 80 and the lower electrode film 60 according to a recording signal from an external drive circuit (not shown), By bending and deforming the lower electrode film 60 and the piezoelectric film 70, the pressure in the pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle openings 11.

(Other Embodiments) The embodiments of the present invention have been described above, but the basic configuration of the ink jet recording head is not limited to the above.

For example, in addition to the sealing plate 20 described above, the common ink chamber forming substrate 30 may be made of glass ceramic, and the thin film 41 may be made of glass ceramic as a separate member. Changes are free.

In the above-described embodiment, the nozzle openings are formed on the end surface of the flow path forming substrate 10. However, the nozzle openings may be formed to project in a direction perpendicular to the surface.

FIG. 9 is an exploded perspective view of the embodiment configured as described above, and FIG. 10 is a cross-sectional view of the flow path thereof. In this embodiment, the nozzle openings 11 are formed in the nozzle forming substrate 120 opposite to the piezoelectric vibrator, and these nozzle openings 1 are formed.
The nozzle communication port 22 for communicating the pressure generation chamber 1 with the pressure generation chamber 12 is
Sealing plate 20, common ink chamber forming substrate 30, and thin plate 41
A and the ink chamber side plate 40A.

This embodiment is different from the first embodiment in that
A is basically the same as the above-described embodiment except that the ink chamber side plate 40A and the ink chamber side plate 40A are separate members, and the opening is formed in the ink chamber side plate 40A. Is omitted.

Of course, it is needless to say that the respective embodiments described above can achieve further effects by being appropriately combined and implemented.

In each of the embodiments described above, a thin film type ink jet recording head which can be manufactured by applying a film forming and lithography process is described as an example.
Of course, the present invention is not limited to this. For example, a structure in which substrates are laminated to form a pressure generating chamber, or a structure in which a green sheet is attached or a piezoelectric film is formed by screen printing, or a crystal formed by a hydrothermal method or the like The present invention can be applied to ink jet recording heads of various structures, such as those that form a piezoelectric film by growth.

As described above, the present invention can be applied to ink-jet recording heads having various structures, as long as the gist of the present invention is not contradicted.

The ink jet recording head of each of these embodiments constitutes a part of a recording head unit having an ink flow path communicating with an ink cartridge and the like, and is mounted on an ink jet recording apparatus. FIG.
FIG. 1 is a schematic view showing an example of the ink jet recording apparatus.

As shown in FIG. 11, the recording head units 1A and 1B having the ink jet recording heads
Cartridges 2A and 2B constituting ink supply means are detachably provided. A carriage 3 on which the recording head units 1A and 1B are mounted is provided on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. I have. The recording head units 1A and 1B are, for example,
Each of them ejects a black ink composition and a color ink composition.

The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted moves along the carriage shaft 5. Moved. On the other hand, the apparatus main body 4 is provided with a platen 8 along the carriage 3. The platen 8 can be rotated by a driving force of a paper feed motor (not shown), and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller, is wound around the platen 8 and conveyed. It has become so.

[0090]

As described above, according to the present invention, the film thickness decreasing portion in which the film thickness gradually decreases toward the outside of the piezoelectric active portion is provided at the edge of the lower electrode film which is the edge of the piezoelectric active portion. Was provided. Thus, the piezoelectric film is formed with a substantially uniform thickness on the lower electrode film, and the thickness of the piezoelectric film does not become thin even near the end of the lower electrode film. Therefore, dielectric breakdown of the piezoelectric film due to electric field concentration near the end of the lower electrode film can be prevented, and a piezoelectric element having improved durability and reliability can be formed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an ink jet recording head according to a first embodiment of the present invention.

FIG. 2 is a plan view and a cross-sectional view of the inkjet recording head according to the first embodiment of the present invention, showing the same.

FIG. 3 is a perspective view showing a modification of the sealing plate of FIG. 1;

FIG. 4 is a cross-sectional view illustrating a thin-film manufacturing process according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a thin-film manufacturing process according to the first embodiment of the present invention.

FIG. 6 is a plan view and a cross-sectional view illustrating a main part of the inkjet recording head according to the first embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a modification of the ink jet recording head according to the first embodiment of the present invention.

FIG. 8 is a plan view showing a modified example of the ink jet recording head according to the first embodiment of the present invention.

FIG. 9 is an exploded perspective view of an ink jet recording head according to another embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating an ink jet recording head according to another embodiment of the present invention.

FIG. 11 is a schematic view of an ink jet recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 12 pressure generating chamber 50 elastic film 60 lower electrode film 61, 61A, 61B film thickness gradually decreasing portion 62 lower electrode film for wiring 70 piezoelectric film 80 upper electrode film 300 piezoelectric element 320 piezoelectric active portion

Claims (16)

[Claims] 1. A piezoelectric element comprising a lower electrode provided on one surface side of a substrate via an insulating layer, a piezoelectric layer provided on the lower electrode, and an upper electrode provided on the surface of the piezoelectric layer. In an actuator device comprising: an end of the lower electrode is an end of a piezoelectric active portion that is a substantial driving portion of the piezoelectric element, and an end of the lower electrode is outside the piezoelectric active portion. An actuator device comprising: a tapered portion in which the thickness of the lower electrode gradually decreases. 2. The method according to claim 1, wherein the gradually decreasing thickness is
An actuator device, wherein the lower electrode has an inclined surface in which the film thickness of the lower electrode is gradually reduced. 3. The method according to claim 1, wherein the gradually decreasing thickness is
An actuator device, wherein the thickness of the lower electrode is gradually reduced in a stepwise manner. 4. The method according to claim 1, wherein the gradually decreasing thickness is
An actuator device, wherein the lower electrode has an inclined curved surface in which the film thickness of the lower electrode is gradually reduced. 5. The actuator according to claim 1, wherein the thickness of the piezoelectric layer formed on the tapered portion is larger than the thickness of the other portion. apparatus. 6. The pressure generating chamber according to claim 1, wherein the piezoelectric element is provided in a region corresponding to a pressure generating chamber formed in the substrate, and an end of the piezoelectric active portion is provided in the pressure generating chamber. An actuator device which is located inside a peripheral wall. 7. The actuator device according to claim 1, wherein the piezoelectric layer and the upper electrode extend to the same position as the end of the lower electrode or to the outside thereof. 8. The piezoelectric element according to claim 1, wherein the lower electrode is provided discontinuously further outside the piezoelectric layer provided outside an end of the tapered portion. An actuator device, wherein a wiring lower electrode having one end connected to an external wiring is provided for each of the piezoelectric elements. 9. The actuator device according to claim 1, wherein the lower electrode is provided continuously over a plurality of adjacent piezoelectric elements. 10. The actuator device according to claim 1, wherein the lower electrode is patterned for each piezoelectric element. 11. The flow path forming substrate, wherein the substrate of the actuator device according to any one of claims 1 to 10 defines a pressure generating chamber communicating with a nozzle opening, and on the other surface side of the flow path forming substrate, An ink jet recording head, wherein a nozzle forming substrate having the nozzle openings is joined. 12. The pressure generating chamber according to claim 11, wherein the pressure generating chamber is formed on a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric element is formed by a thin film and a lithography method. Ink jet recording head. 13. An ink jet recording apparatus comprising the ink jet recording head according to claim 11. 14. A lower electrode layer, a piezoelectric layer, and an upper electrode layer are sequentially laminated on an insulating layer on a substrate, and each layer is patterned, and the lower electrode layer, the piezoelectric layer, and the upper electrode layer are formed. In a method of manufacturing an actuator device for forming a piezoelectric element, the film thickness of the lower electrode layer is formed at a position corresponding to a region to be an end of a piezoelectric active portion of the piezoelectric element by forming and patterning the lower electrode layer. A first step of forming a tapered portion having a gradually decreasing thickness, and a second step of forming the piezoelectric layer and the upper electrode layer thereon and patterning these to form the piezoelectric element. A method for manufacturing an actuator device, comprising: 15. The film forming method according to claim 14, wherein in the first step, a resist film having substantially the same shape as the shape of the tapered portion is formed at an end of the lower electrode layer and patterned. A method for manufacturing an actuator device, wherein a tapered portion is formed. 16. The method according to claim 14, wherein, in the first step, at least a region of the insulating layer, which is to be the portion having a gradually decreasing thickness, is covered with a mask, and the lower electrode layer is vapor-deposited on a predetermined region by mask vapor deposition. A method for manufacturing an actuator device, comprising: