JPH11348280A - Ink jet recording head and ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head, a method for manufacturing the same and an ink jet recorder capable of improving a deformable quantity of an elastic membrane and the durability thereof. SOLUTION: This ink jet recording head comprises elastic membranes 50, 51, 53 forming a part of a pressure generating chamber 12 communicated to a nozzle opening, a lower electrode 60 provided above the elastic membranes 50, 51, 53, a piezoelectric material layer 70 formed on the lower electrode 60 and an upper electrode 80 formed on the surface of the piezoelectric material layer 70. It further comprises a piezoelectric vibrator which includes the piezoelectric material layer 70 formed on each region corresponding to the pressure generating chamber 12, lower electrode 60 and upper electrode 80. A stress of the membrane forming the elastic membranes 50, 51, 53 at arm sections at both sides in the width direction of the piezoelectric material layer 70 forming the piezoelectric vibrator is greater than that of the membrane forming the elastic membrane 50, 51, 53 among them in a pulling direction so that the piezoelectric layer 70 is pulled toward outsides in the width direction, thereby improving the piezoelectric characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure generating chamber which is in communication with a nozzle opening for ejecting ink droplets, which is constituted by an elastic film, and a piezoelectric layer is formed on the surface of the elastic film to form a piezoelectric material. The present invention relates to an ink jet recording head for ejecting ink droplets by displacement of a layer, a method for manufacturing the same, and an ink jet recording apparatus.

[0002]

2. Description of the Related Art A part of a pressure generating chamber communicating with a nozzle opening for discharging ink droplets is formed of an elastic film, and this elastic film is deformed by a piezoelectric vibrator to pressurize ink in the pressure generating chamber to open the nozzle opening. There are two types of ink-jet recording heads that eject ink droplets from a piezoelectric vibrator, one that uses a piezoelectric vibrator that expands and contracts in the axial direction of the piezoelectric vibrator, and one that uses a piezoelectric vibrator that flexes. Has been put to practical use.

In the former method, the volume of the pressure generating chamber can be changed by bringing the end face of the piezoelectric vibrator into contact with an elastic film, so that a head suitable for high-density printing can be manufactured. A complicated process of cutting the piezoelectric vibrators into a comb-tooth shape in accordance with the arrangement pitch of the nozzle openings, and a work of positioning and fixing the separated piezoelectric vibrators in the pressure generating chambers, which complicates the manufacturing process. There is.

On the other hand, in the latter, a piezoelectric vibrator can be formed on an elastic film by a relatively simple process of sticking a green sheet of a piezoelectric material according to the shape of the pressure generating chamber and firing the green sheet. However, due to the use of flexural vibration, a certain area is required, and there is a problem 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 over the entire surface of the elastic film by a film forming technique as disclosed in Japanese Patent Application Laid-Open No. 5-286131. A proposal has been made in which this piezoelectric material layer is cut into a shape corresponding to the pressure generating chambers by lithography, and a piezoelectric vibrator is formed so as to be independent for each pressure generating chamber.

According to this, the work of attaching the piezoelectric vibrator to the elastic film becomes unnecessary, and the precision of the lithography method is eliminated.
In addition to the fact that the piezoelectric vibrator can be manufactured by a simple and simple method, there is an advantage that the thickness of the piezoelectric vibrator can be reduced and high-speed driving is possible. In this case, the piezoelectric vibrator 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 elastic film.

[0007]

However, in the above-described manufacturing method using the thin film technology and the lithography method,
A pressure generating chamber is formed after patterning the thin film. At this time, the internal stress of the piezoelectric layer is relaxed, and the elastic film is bent toward the pressure generating chamber due to the internal stress of the lower electrode. It remains as the initial deformation of the elastic film. Therefore, there is a problem that the amount of deformation of the elastic film due to the driving of the piezoelectric vibrator is substantially reduced, and a problem that the durability of the elastic film is reduced.

Further, since the lower electrode generally extends from the region facing the pressure generating chamber to the peripheral wall thereof and forms a diaphragm together with the elastic film, there is a problem that the displacement efficiency is low. Further, a structure is known in which the lower electrode on the both sides in the width direction of the pressure generating chamber, that is, the lower electrode, is over-etched to remove a part or all of the lower electrode to increase the displacement efficiency. Increases, and an increase in excluded volume cannot be expected. In addition, such a structure has a problem that the characteristics inherent to the piezoelectric vibrator cannot be actually obtained.

In view of such circumstances, an object of the present invention is to provide an ink jet recording head, a method of manufacturing the same, and an ink jet recording apparatus which improve the deformation amount and durability of the elastic film.

[0010]

According to a first aspect of the present invention for solving the above-mentioned problems, an elastic film constituting a part of a pressure generating chamber communicating with a nozzle opening and a lower member provided on the elastic film are provided. An electrode, a piezoelectric layer formed on the lower electrode, and an upper electrode formed on the surface of the piezoelectric layer, and the piezoelectric layer formed for each region corresponding to the pressure generating chamber; In an ink jet recording head in which a piezoelectric vibrator including the lower electrode and the upper electrode is formed, the stress of a film forming the elastic film of the arm on both sides in the width direction of the piezoelectric layer forming the piezoelectric vibrator. However, in the ink jet type recording head, the stress in the tensile direction is larger than the stress of the film constituting the elastic film therebetween.

According to the first aspect, when the pressure generating chamber is formed, the piezoelectric layer is pulled outward in the width direction by the force that releases the stress of the film constituting the elastic film of the arm portion, and the piezoelectric characteristics are reduced. The amount of deformation of the elastic film is improved.

According to a second aspect of the present invention, in the first aspect, the elastic film has a tensile film having a tensile stress at least in the arm portion, and the tensile film has at least a thickness between the arm portions. The ink jet recording head is characterized in that a tensile film removing portion is formed in which a part of the tensile film is removed.

In the second aspect, by providing the tensile film removing portion, the tensile film in a portion corresponding to the arm portion becomes a tensile stress, and when forming the pressure generating chamber, the piezoelectric layer is pulled in the width direction. Can be

According to a third aspect of the present invention, there is provided an ink jet recording head according to the second aspect, wherein the tensile film removing portion is slightly narrower than a width of the piezoelectric vibrator.

[0015] In the third aspect, the patterning of the piezoelectric layer after the formation of the tensile film removing portion can be favorably performed.

According to a fourth aspect of the present invention, there is provided an ink jet recording head according to any one of the first to third aspects, wherein the tensile film is made of a metal film.

In the fourth aspect, a tensile stress is generated by forming the tensile film with a metal film.

According to a fifth aspect of the present invention, there is provided an ink jet recording head according to any one of the first to third aspects, wherein the tensile film is formed of a metal oxide film.

In the fifth aspect, since the tensile film is formed of a metal oxide film, a tensile stress is generated, and the strength is improved.

According to a sixth aspect of the present invention, in any one of the second to fifth aspects, a non-tensile film having a smaller tensile stress or a smaller compressive stress than the tensile film is provided above the tensile film removing portion. An ink jet recording head comprising:

In the sixth aspect, the piezoelectric layer is further strongly pulled outward in the width direction by the tensile film and the non-tensile film.

A seventh aspect of the present invention is the ink jet recording head according to the sixth aspect, wherein the non-tensile film also serves as the lower electrode.

In the seventh aspect, when the pressure generating chamber is formed, the piezoelectric layer is pulled outward in the width direction by the force that releases the stress of the lower electrode.

An eighth aspect of the present invention is the ink jet recording head according to the sixth or seventh aspect, wherein the non-tensile film is patterned for each of the pressure generating chambers together with the piezoelectric vibrator. It is in.

In the eighth aspect, the thickness of the arm does not increase, and the amount of deformation of the elastic film does not decrease.

A ninth aspect of the present invention is the ink jet recording head according to any one of the sixth to eighth aspects, wherein the non-tensile film is a compression film made of a metal oxide. .

In the ninth aspect, when the pressure generating chamber is formed, the piezoelectric layer is further strongly pulled outward in the width direction by the force that releases the stress of the compression film.

A tenth aspect of the present invention is the ink jet recording head according to any one of the first to ninth aspects, wherein the upper electrode has a compressive stress.

In the tenth aspect, when the pressure generating chamber is formed, the piezoelectric layer is further strongly pulled outward in the width direction by the force that releases the compressive stress of the upper electrode.

According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the lower electrode extends from at least one longitudinal end of a region facing the pressure generating chamber to the outside thereof. The ink jet recording head is characterized in that:

In the eleventh aspect, connection to an external wiring can be made via the extended lower electrode.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the upper electrode and the piezoelectric layer
An ink jet recording head is provided which extends from at least one longitudinal end of a region facing the pressure generating chamber to the outside thereof.

In the twelfth aspect, connection to external wiring can be made via the extended upper electrode.

The thirteenth aspect of the present invention is directed to the eleventh or twelfth aspect.
In the above aspect, the extending direction of the lower electrode may be different from the extending direction of the upper electrode and the piezoelectric layer.

In the thirteenth aspect, the upper and lower electrodes and the external wiring can be easily connected.

A fourteenth aspect of the present invention is the ink jet recording head according to the thirteenth aspect, wherein one of the lower electrode and the upper electrode is a common electrode.

In the fourteenth aspect, connection with external wiring can be easily performed.

According to a fifteenth aspect of the present invention, in any one of the first to fourteenth aspects, the pressure generating chamber is formed by anisotropic etching on a silicon single crystal substrate, and each layer of the piezoelectric vibrator is formed by film formation. And an ink jet recording head formed by a lithography method.

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

According to a sixteenth aspect of the present invention, in any one of the first to fifteenth aspects, the piezoelectric layer is formed by a sol-gel method or a sputtering method. It is in.

In the sixteenth aspect, the piezoelectric layer can be easily formed.

According to a seventeenth aspect of the present invention, there is provided an ink jet recording apparatus comprising the ink jet recording head according to any one of the first to sixteenth aspects.

According to the seventeenth aspect, it is possible to realize an ink jet recording apparatus in which the ink ejection performance of the head is improved.

[0044]

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 and a cross section of one of the pressure generating chambers in the longitudinal direction. It is a figure showing a structure.

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, a silicon single crystal substrate is anisotropically etched on the opening surface of the flow path forming 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 alkaline solution such as KOH, the substrate is gradually eroded and the first (111) plane perpendicular to the (110) plane and the first (111) plane A second (1) which forms an angle of about 70 degrees with the (111) plane and forms an angle of about 35 degrees with the (110) plane.
11) plane, and the etching rate of the (111) plane is about 1/1 compared to the etching rate of the (110) plane.
This is performed using the property of being 80.
By such anisotropic etching, two first (11
Precision processing can be performed based on depth processing of a parallelogram formed by the 1) plane and two oblique second (111) planes, and the pressure generating chambers 12 can be arranged at high density. it can.

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 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 described above, 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 of the ink chamber side plate 40 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, 0.2 to 0.1 mm.
At 6 μm, a tensile film 51 having a tensile stress is formed,
As will be described in detail later, the piezoelectric active portion 3 of the tensile film 51
In a part of the portion corresponding to 20, a tensile film removing portion 52 from which the tensile film 51 has been removed is formed. In the present embodiment, a compression film 53 having a thickness of, for example, 0.5 to 1 μm and having a compressive stress is further formed on the tensile film 51.
20 and is patterned.

On the compression film 53, a lower electrode film 60 having a thickness of, for example, about 0.2 μm, a piezoelectric film 70 having a thickness of, for example, about 1 μm, and a .1 μm
The upper electrode film 80 is formed by lamination in a process described later to form a piezoelectric vibrator (piezoelectric element) 300. Here, the piezoelectric vibrator 300 includes the lower electrode film 60 and the piezoelectric film 7.
0 and a portion including the upper electrode film 80. In general,
One of the electrodes of the piezoelectric vibrator 300 is used as a common electrode,
The other electrode and the piezoelectric film 70 are formed by patterning 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 serves as a common electrode of the piezoelectric vibrator 300 and the upper electrode film 8
Although 0 is used as the individual electrode of the piezoelectric vibrator 300, there is no problem even if this is reversed for convenience of the drive circuit and wiring. In any case, the piezoelectric active portion is formed for each pressure generating chamber.

Here, a process for 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 FIG.

As shown in FIG. 4A, first, a wafer of a silicon single crystal substrate serving as the flow path forming substrate 10 is
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 tensile film 51 having a tensile stress is formed by a sputtering method.
The tensile film 51 is not particularly limited as long as it has a tensile stress and can withstand deformation at the time of ink ejection. For example, a metal film such as Pt or Ir is suitable.

Next, as shown in FIG. 4C, a portion of the tensile film 51 corresponding to the piezoelectric active portion 320 in the surface direction is patterned to remove the tensile film 51 and remove the tensile film. 52 is formed. The width of the tensile film removing portion 52 is not particularly limited, but is preferably formed to be equal to or slightly smaller than the width of the piezoelectric active portion 320 in a region corresponding to the piezoelectric active portion 320. If a crack occurs in the piezoelectric film 70, it is preferable that the piezoelectric film 70 be formed wider.

Next, as shown in FIG. 4D, a compression film 53 having a compression stress is formed. For example, in the present embodiment, the compressed film 53 having a compressive stress is formed using a monoclinic zirconia film. The compression film 53 is formed by the tension film 5
1 is formed by forming a zirconium layer on the substrate 1 by a sputtering method and then performing thermal oxidation treatment in oxygen in a diffusion furnace at about 1150 ° C. and has a strong compressive stress. Here, since zirconium is heated to a temperature higher than the phase transition temperature when being oxidized, it undergoes a phase transition upon cooling and becomes monoclinic, and becomes zirconia having compressive stress.

Next, as shown in FIG. 4E, a lower electrode film 60 is formed by sputtering. Pt or the like is preferable as the material of the lower electrode film 60. This is because a piezoelectric film 70 to be described later, which is formed by sputtering or a sol-gel method, has a thickness of 600 to 100 in an air atmosphere or an oxygen atmosphere after the film formation.
This is because it is necessary to perform crystallization by firing at a temperature of about 0 ° C. That is, the material of the lower electrode film 60 must be able to maintain conductivity at such a high temperature and in an oxidizing atmosphere. In particular, when PZT is used for the piezoelectric film 70, the conductivity of the material by diffusion of PbO is increased. It is desirable that there is little change in sex, and Pt is preferred for these reasons. In the process of firing the piezoelectric film 70 at a high temperature or oxidizing the zirconium layer, each layer below the piezoelectric film 70 has a strong tensile stress due to a change in the crystal structure or the like depending on the material. . For example, Pt and Ir have a strong tensile stress, and exhibit a function as a tensile film.

Next, as shown in FIG. 4F, a piezoelectric film 70 is formed. The piezoelectric film 70 can be formed by sputtering, but 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, and further baked at a high temperature. A so-called sol-gel method for obtaining a piezoelectric film 70 made of an oxide is used. As a material for the piezoelectric film 70, a lead zirconate titanate (PZT) -based material is suitable when used in an ink jet recording head.

Next, as shown in FIG. 4G, an upper electrode film 80 is formed. The upper electrode film 80 is preferably made of a highly conductive material and has a compressive stress. For example, in the present embodiment, Ir is formed by a sputtering method.

Next, as shown in FIG. 5, the lower electrode film 60,
The piezoelectric film 70, the upper electrode film 80, and the compression film 53 are patterned.

First, as shown in FIG. 5A, the lower electrode film 60, the piezoelectric film 70 and the upper electrode film 80 are etched together to pattern the entire pattern of the lower electrode film 60. Next, as shown in FIG. 5B, the piezoelectric film 70 and the upper electrode film 80 are etched to pattern the piezoelectric active portion 320. Next, as shown in FIG.
At least the lower electrode film 60 and the compression film 53 on both sides in the width direction of the piezoelectric active portion 320, that is, the arms of the diaphragm are removed by etching.

In this embodiment, the pressure generating chamber 12
Is formed by etching. The state of the stress applied to the piezoelectric active portion 320 at this time will be described below. In addition,
FIG. 6 is a diagram schematically showing a state of stress applied to each layer before and after forming the pressure generating chamber 12 by etching.

Each layer in a state of being formed on the flow path forming substrate 10
6A, the elastic film 50 and the compression film 53 are formed as shown in FIG.
And the upper electrode film 80 has a compressive stress σ
₁, Σ_Two, Σ_ThreeAnd the lower electrode film 60 and the piezoelectric film
70 is the tensile stress σ_Four, Σ_FiveReceiving You. Also pull
The film 51 also has a tensile stress σ from the flow path forming substrate 10.₆Receiving
Area where the piezoelectric active portion 320 is patterned
A part is opened because the tensile film removal part 52 is formed in
Have been. Also, the tensile stress σ of the tensile film 51₆Is the pressure
Viewed from the flow path forming substrate 10 in a region facing the force generating chamber 12
Then, on the tensile film removing section 52 side, the compression method
It is acting in the direction.

When the piezoelectric active portion 320 is patterned as shown in FIG. 6B, the tensile stresses σ ₄ and σ ₅ of the lower electrode film 60 and the piezoelectric film 70 are partially released, and the upper electrode The film 80 also releases a part of the compressive stress σ ₃ . Similarly to the upper electrode film 80, a part of the compressive stress σ ₂ of the compressive film 53 is released, but the tensile stress σ ₆ is not released because the tensile film 51 is not patterned.

Next, as shown in FIG. 6C, when the pressure generating chamber 12 is formed below the piezoelectric active portion 320, the tensile stresses σ ₄ and σ _{5 of} the lower electrode film 60 and the piezoelectric film 70 are released. As a result, the compressive stresses σ ₁ and σ _{3 of} the elastic film 50 and the upper electrode film 80 are released, and the elastic film 50 becomes a force in the tensile direction. Becomes However, in the present embodiment, the tension film 51
The tensile stress σ ₆ of the compression film 53 is released and the compressive stress σ ₂ of the compression film 53 is released and the tensile force is released. The power to do is eased.

As described above, in the compression direction, the lower electrode film 60
And a force that releases the stresses σ ₄ and σ _{5 of the} piezoelectric film 70 acts, while a force that releases the stresses σ ₁ and σ ₃ of the elastic film 50 and the upper electrode film 80 in the tensile direction. In this embodiment, the tension film 51 and the compression film 53
Stresses σ ₆ and σ ₂ act. Therefore, when the force in the pulling direction is increased, the diaphragm deforms convexly upward, and the forces in both directions are balanced, the diaphragm hardly bends. Further, in the present embodiment, when forming the pressure generating chamber 12, the arm portion of the diaphragm is subjected to the stress σ of the elastic film 50.
₁ and the force that releases the stress σ ₆ of the tensile film 51 acts only in the tensile direction. Therefore, under suitable conditions, the diaphragm deforms upwardly.

When the tension film 51 and the compression film 53 are not formed, as shown in FIG. 7A, before the pressure generating chamber 12 is formed, the lower electrode film 60 and the piezoelectric film 70 are respectively tensioned. While receiving the stresses σ ₄ and σ ₅ , the elastic film 5
0 and the upper electrode film 80 receive compressive stresses σ ₁ and σ ₃ .
When the pressure generating chambers 12 are formed, the tensile stresses σ ₄ and σ _{5 of} the lower electrode film 60 and the piezoelectric film 70 are released to produce a force to contract, whereas the elastic film 50 is patterned. As a result, only the compressive stress of the upper electrode film 80 is released, and it becomes a force in the tensile direction. As a result, since the force in the compression direction is larger than the force in the tension direction,
Is deformed convexly downward as shown in FIG. 7B, and this remains as initial deformation. As described above, particularly when a piezoelectric film is formed by a sol-gel method or a sputtering method that requires firing at a high temperature, a strong tensile stress is generated in the lower electrode film. This has led to a decrease in characteristics.

As described above, in this embodiment, the elastic film 5
On the other hand, a tensile film 51 is formed on
The tensile film removing part 52 is provided in a region corresponding to
A compression film 53 was formed on the tension film 51. This allows
Patterning and pressure generation chamber 12
After formation, the force from which the stress of the tensile film 51 is released substantially becomes a force in the tensile direction, and the force from which the stress of the compression film 53 is released becomes a force in the tensile direction. Therefore, in addition to the force from which the stress of the elastic film 50 and the upper electrode film 80 are released, the force from which the stress of the tensile film 51 and the compression film 53 are released acts in the tensile direction, so that the lower electrode film 60 and the piezoelectric film The body layer 70 and the force in the compression direction in which the stress is released are offset, and the deformation of the elastic film 50 due to the formation of the pressure generating chamber 12 can be reduced or eliminated. At this time, the piezoelectric film 70 is pulled outward in the width direction by the force acting in the pulling direction, and the amount of bending is reduced. Further, the piezoelectric film 70
Found that the smaller the amount of deflection, the better the piezoelectric properties. Therefore, by reducing the amount of bending of the piezoelectric film 70, the piezoelectric characteristics of the piezoelectric film 70 are improved,
The excluded volume can be increased.

In the above description, the pressure generating chamber 12 is formed after the piezoelectric active portion 320 is patterned. However, in actuality, as shown in FIG. 2, at least the upper surface of each upper electrode film 80 is formed. An insulating layer 90 having electrical insulation is formed so as to cover the periphery and the side surfaces of the piezoelectric film 70 and the lower electrode film 60, and further correspond to one end of each piezoelectric active portion 320 of the insulating layer 90. A contact hole 90a exposing a part of the upper electrode film 80 for connecting to the lead electrode 100 is formed in a part of the part covering the upper surface of the part to be formed, and each upper electrode film 80 is formed through the contact hole 90a. A lead electrode 100 having one end connected and the other end extending to the connection terminal may be formed. Here, the lead electrode 100
Is preferably formed to have a width as narrow as possible so as to reliably supply a drive signal to the upper electrode film 80. In the present embodiment, the contact hole 90 a is provided at a position facing the pressure generating chamber 12, but the piezoelectric film 70 and the upper electrode film 80 of the piezoelectric active part 320 are provided on the peripheral wall of the pressure generating chamber 12. The contact hole 90a may be provided at a position extending to the facing region and facing the peripheral wall of the pressure generating chamber 12.

In the series of film formation and anisotropic etching described above, a number of chips are simultaneously formed on one wafer, and after the process is completed, a flow path of one chip size as shown in FIG. It is divided for each forming substrate 10. Further, the divided flow path forming substrate 10 is sequentially adhered and integrated with the sealing plate 20, the common ink chamber forming substrate 30, and the ink chamber side plate 40 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), fills the inside from the common ink chamber 31 to the nozzle opening 11 with ink, and
In accordance with a recording signal from an external drive circuit (not shown), a voltage is applied between the lower electrode film 60 and the upper electrode film 80 via the lead electrode 100, and the elastic film 50, the lower electrode film 60, and the piezoelectric film 70 The pressure generating chamber 1 is deformed by bending.
The pressure in 2 increases, and ink droplets are ejected from nozzle opening 11.

FIG. 8 shows the relationship between the force applied to the diaphragm and the amount of elastic deformation when the piezoelectric vibrator of this embodiment is driven.
(A). As shown in the drawing, in the present embodiment, since the diaphragm is not deformed in the initial stage, the force F generated at the time of driving is obtained.
Is generated in the elastic deformation region. On the other hand, as shown in FIG. 8B, when the initial deformation t is caused by the force f applied at the initial stage, if the force F is applied at the time of driving, it enters the plastic deformation region. Is not obtained, a deformation T ′ occurs, and (T−
T ′) is the loss of deformation.

As described above, in the present embodiment, the tension film 51 is formed of Pt, ir, etc., and the compression film 53 is formed of zirconia or the like. However, the present invention is not limited to this. The tensile film 53 is made of, for example, MgO, Ca
By adding an additive such as O or a rare earth oxide of about several percent, the material may be formed of stable or partially stabilized zirconia having a tensile stress. At this time, the compression film 53 is preferably made of a material similar to the tensile film 51, and for example, monoclinic zirconia having a compressive stress is suitable. As described above, by forming the tensile film 51 and the compression film 53 with similar materials, an effect of improving the adhesion between them can be obtained. Further, in the case of such a configuration, by forming the elastic film 50 of zirconia, all portions where the tensile film 51 is in contact with other films are formed of similar materials, and the adhesion is improved. Further improve.

In this embodiment, the tensile film removing unit 5
2 is formed by completely removing the tensile film 51 in the thickness direction, but is not limited thereto. For example, as shown in FIG. It may be formed by removing by half etching or the like. The depth of the tensile film removing portion 52 is not particularly limited. However, since the force at which the tensile stress of the tensile film 51 is released is proportional to this depth, it can be determined in consideration of the stress balance of the entire film. Good. With such a configuration, the same effect as described above can be obtained, and since the bonding surface with the compression film 53 is made of the same material, the adhesion is improved.

(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 the above embodiment, the tensile film 5
Although the compressive film 53 formed on the substrate 1 is used as a compressive stress, the present invention is not limited to this, and a tensile stress may be used as long as the stress is at least smaller than that of the tensile film 51.

In the present embodiment, the lower electrode film 60 is formed on the compression film 53. However, the present invention is not limited to this. For example, the compression film 53 may also serve as the lower electrode film 60. Alternatively, for example, the lower electrode film 60 may be formed on the tension film 51 without providing the compression film 53.

For example, in addition to the sealing plate 20 described above,
The common ink chamber forming plate 30 may be made of glass ceramic, and further, the thin film 41 may be made of glass ceramic as a separate member, and the material, structure and the like can be freely changed.

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. 10 is an exploded perspective view of the embodiment constructed as described above, and FIG. 11 is a sectional view of the flow path. In this embodiment, the nozzle openings 11 are drilled in the nozzle substrate 120 opposite to the piezoelectric vibrator, and these nozzle openings 11
A nozzle communication port 22 for communicating the pressure generating chamber 12 with the pressure generating chamber 12 is provided so as to penetrate the sealing plate 20, the common ink chamber forming plate 30, the thin plate 41A, 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 40. Is omitted.

Here, also in this embodiment, as in the above-described embodiment, by forming a tensile film on the elastic film, the initial deflection of the elastic film is reduced, and the amount of deformation due to the driving of the piezoelectric active portion is reduced. Can be substantially increased.

Further, needless to say, the present invention can be similarly applied to an ink jet recording head of a type in which a common ink chamber is formed in a flow path forming substrate.

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 piezoelectric film is formed by laminating substrates to form a pressure generating chamber, or a piezoelectric film is formed by attaching a green sheet or by screen printing, or a piezoelectric film formed by crystal growth. The present invention can be applied to ink jet recording heads having various structures, such as those that form a recording medium.

Further, the example in which the insulator layer is provided between the piezoelectric vibrator and the lead electrode has been described. However, the present invention is not limited to this. The conductive film may be thermally welded, and the anisotropic conductive film may be connected to the lead electrode, or may be connected using various bonding techniques such as wire bonding.

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 the 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. 12, recording head units 1A and 1B having an ink jet recording head are
Cartridges 2A and 2B constituting ink supply means are provided detachably, and 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 shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is wound around the platen 8. It is designed to be transported.

[0097]

As described above, according to the present invention,
Forming a tensile film having a tensile stress on the elastic film, forming at least a part of the portion corresponding to the piezoelectric active portion in the thickness direction to form a tensile film removing portion, when forming the pressure generating chamber, By pulling the piezoelectric layer outward in the width direction, the piezoelectric characteristics of the piezoelectric layer are improved, and the volume removed is improved.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an ink jet recording head according to an 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 view showing a modification of the sealing plate of FIG. 1;

FIG. 4 is a diagram showing a thin film manufacturing process according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a thin film manufacturing process according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a state of stress applied to the piezoelectric active portion of the present embodiment when the pressure generating chamber is formed.

FIG. 7 is a view showing a state of stress applied to a conventional piezoelectric active portion when forming a pressure generating chamber.

FIG. 8 is a graph showing the relationship between the force applied to the diaphragm and the amount of elastic deformation when the piezoelectric vibrator is driven.

FIG. 9 is a cross-sectional view of a principal part showing a modified example of the ink jet recording head according to the first embodiment of the present invention.

FIG. 10 is an exploded perspective view showing an ink jet recording head according to another embodiment of the present invention.

FIG. 11 is a cross-sectional view showing an ink jet recording head according to another embodiment of the present invention.

FIG. 12 is a schematic view of an ink jet recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 flow path forming substrate 12 pressure generating chamber 50 elastic film 51 tensile film 52 tensile film removing section 53 compression film 54 compression film removing section 60 lower electrode film 70 piezoelectric film 80 upper electrode film 90 insulator layer 100 lead electrode 300 piezoelectric vibration Child 320 Piezoelectric active part

Claims (17)

[Claims] An elastic film forming a part of a pressure generating chamber communicating with a nozzle opening; a lower electrode provided on the elastic film; a piezoelectric layer formed on the lower electrode; An ink jet type comprising an upper electrode formed on the surface of the body layer, and forming a piezoelectric vibrator including the piezoelectric layer, the lower electrode, and the upper electrode formed for each region corresponding to the pressure generating chamber. In the recording head, the stress of the film forming the elastic film of the arm portion on both sides in the width direction of the piezoelectric layer forming the piezoelectric vibrator is greater in the tensile direction than the stress of the film forming the elastic film therebetween. An ink jet recording head, characterized in that: 2. The elastic film according to claim 1, wherein the elastic film has a tensile film having a tensile stress on at least the arm portion, and the tensile film has at least a part in a thickness direction removed between the arm portions. An ink jet recording head, wherein a tensile film removing portion is formed. 3. The ink jet recording head according to claim 2, wherein the tensile film removing portion is slightly narrower than the width of the piezoelectric vibrator. 4. An ink jet recording head according to claim 1, wherein said tensile film is made of a metal film. 5. The ink jet recording head according to claim 1, wherein said tensile film is made of a metal oxide film. 6. An ink jet printer according to claim 2, wherein a non-tensile film having a smaller tensile stress or a smaller compressive stress than said tensile film is provided above said tensile film removing portion. Type recording head. 7. The method according to claim 6, wherein the non-tensile film comprises:
An ink jet recording head, which also serves as the lower electrode. 8. The ink jet recording head according to claim 6, wherein the non-tensile film is patterned for each of the pressure generating chambers together with the piezoelectric vibrator. 9. The ink jet recording head according to claim 6, wherein the non-tensile film is a compression film made of a metal oxide. 10. The ink jet recording head according to claim 1, wherein the upper electrode has a compressive stress. 11. The ink jet printer according to claim 1, wherein the lower electrode extends from at least one longitudinal end of a region facing the pressure generating chamber to the outside thereof. Type recording head. 12. The pressure sensor according to claim 1, wherein the upper electrode and the piezoelectric layer extend outward from at least one longitudinal end of a region facing the pressure generating chamber. An ink jet recording head characterized by the following. 13. The ink jet recording head according to claim 11, wherein the extending direction of the lower electrode is different from the extending direction of the upper electrode and the piezoelectric layer. 14. The ink jet recording head according to claim 13, wherein one of the lower electrode and the upper electrode is a common electrode. 15. The pressure generating chamber according to claim 1, wherein the pressure generating chamber is formed on a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric vibrator is formed by film formation and lithography. An ink jet recording head, characterized in that: 16. An ink jet recording head according to claim 1, wherein said piezoelectric layer is formed by a sol-gel method or a sputtering method. 17. An ink jet recording apparatus comprising the ink jet recording head according to claim 1. Description: