JP2000141644A - Ink jet recording head and ink jet recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head and an ink jet recorder capable of preventing a decrease in piezoelectric property of as piezoelectric material layer. SOLUTION: There is disclosed an ink jet recording head wherein a piezoelectric element 300 having a lower electrode 60, a piezoelectric material layer 70 and an upper electrode 80 is formed in a region corresponding to a pressure generating chamber 12 with a diaphragm forming a part of the pressure generating chamber 12 communicating with a nozzle therebetween. Both end sections at both sides in the width direction of the piezoelectric material layer 70 forming the piezoelectric element 300 are placed in a region opposite to the pressure generating chamber 12. A tensile membrane 90 having a tensile stress is continuously provided in each of at least both sides in the width direction of the piezoelectric material layer 70, thereby preventing a decrease in piezoelectric characteristic of the piezoelectric material layer 70.

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 communicates with a nozzle opening for discharging ink droplets, which is constituted by a vibrating plate, and a piezoelectric element is provided via the vibrating plate. TECHNICAL FIELD The present invention relates to an ink jet recording head and an ink jet recording apparatus for ejecting ink droplets by using an ink jet recording head.

[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 the nozzle opening. Two types of ink jet recording heads for ejecting ink droplets have been put into practical use, one using a longitudinal vibration mode piezoelectric element that expands and contracts in the axial direction of a piezoelectric element, and the other using a flexural vibration mode piezoelectric element. 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 bending vibration, and it is difficult to perform high-density arrangement.

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. 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.

[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 of the thin film. At this time, the internal stress of the piezoelectric layer is relaxed, and the tensile stress of the piezoelectric layer is weakened by the internal stress of the lower electrode, and the piezoelectric characteristics are reduced. This causes a problem that the ejection characteristics are deteriorated. In particular, when the compression films are present on both sides of the piezoelectric layer, the piezoelectric characteristics are likely to deteriorate.

[0008] In view of such circumstances, an object of the present invention is to provide an ink jet recording head and an ink jet recording apparatus in which a decrease in piezoelectric characteristics of a piezoelectric layer is suppressed.

[0009]

According to a first aspect of the present invention for solving the above-mentioned problems, an area corresponding to the pressure generating chamber is provided via a diaphragm constituting a part of the pressure generating chamber communicating with a nozzle opening. In the ink jet type recording head in which a piezoelectric element having a lower electrode, a piezoelectric layer, and an upper electrode is formed, both ends in the width direction of the piezoelectric layer constituting the piezoelectric element are in a region opposed to the pressure generating chamber. And a tensile film having a tensile stress is provided continuously on at least both sides in the width direction of the piezoelectric layer.

[0010] In the first aspect, the tension of the tensile film acts on the piezoelectric layer, and the piezoelectric characteristics are maintained.

According to a second aspect of the present invention, in the first aspect, the tensile film is provided in contact with end faces on both ends in the width direction of the piezoelectric layer. In the head.

In the second aspect, the piezoelectric layer is reliably pulled in the width direction by the tensile film.

According to a third aspect of the present invention, in the first aspect, the tensile film is provided in contact with end faces on both ends in the width direction of the piezoelectric layer and the upper electrode. Ink-jet recording head.

In the third aspect, a stronger tension of the tensile film acts on the piezoelectric layer.

According to a fourth aspect of the present invention, there is provided an ink jet recording head according to the third aspect, wherein the tensile film covers an upper surface of the upper electrode.

In the fourth aspect, the tensile film can be easily formed.

According to a fifth aspect of the present invention, there is provided an ink jet recording head according to the first aspect, wherein the tensile film is made of an insulating material.

In the fifth aspect, the insulation of the upper electrode can be maintained.

According to a sixth aspect of the present invention, there is provided an ink jet recording head according to any one of the first to fifth aspects, wherein the tensile film also serves as an environmental protection protective film.

According to the sixth aspect, the piezoelectric active portion and the elastic film are protected from the external environment.

According to a seventh aspect of the present invention, there is provided an ink jet recording head according to any one of the first to sixth aspects, wherein the tensile film also serves as an interlayer insulating film.

In the seventh aspect, the piezoelectric element and the lead electrode are connected in the contact hole in a region facing the pressure generating chamber.

An eighth aspect of the present invention is the ink jet recording head according to any one of the first to fourth aspects, wherein the tensile film is made of an organic material.

According to the eighth aspect, a tensile film having a tensile stress and effectively applying tension to the lower electrode can be formed.

A ninth aspect of the present invention is the ink jet recording head according to any one of the first to fourth aspects, wherein the tensile film is made of a conductive material.

In the ninth aspect, the material of the film having a tensile stress can be selected.

According to a tenth aspect of the present invention, there is provided an ink jet recording head according to the first aspect, wherein the tensile film doubles as an upper electrode.

In the tenth aspect, the upper electrode is a common electrode.

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

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

According to a twelfth 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 eleventh aspects.

According to the twelfth aspect, it is possible to realize an ink jet recording apparatus having improved ejection characteristics of the head.

[0033]

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. 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 a single crystal silicon 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 0.1 to 2 μm thick elastic film 50 made of silicon dioxide formed in advance 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 alkaline solution such as potassium hydroxide, the substrate is gradually eroded, and the first (1) plane is 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.

Each of the pressure generating chambers 12 and a common ink chamber 31 to be described later are connected to each of the pressure generating chambers 1 of the sealing plate 20 to be 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 has one surface constituting 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, on the elastic film 50 on the side opposite to the opening surface of the flow path forming substrate 10, for example, a thickness of 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. However, there is no problem even if the upper electrode film 80 is reversed for convenience of a drive circuit and wiring. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Also, here
The piezoelectric element 300 and a diaphragm whose displacement is generated by driving the piezoelectric element 300 are referred to as a piezoelectric actuator. In this embodiment, the lower electrode film 60 and the elastic film 5
0 acts as a diaphragm.

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 silicon single crystal substrate wafer 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 lower electrode film 60 is formed by sputtering. As a material of the lower electrode film 60, platinum or the like is preferable. This is because a piezoelectric film 70 described later, which is formed by a sputtering method or a sol-gel method,
Is from 600 to 600 ° C. in an air atmosphere or an oxygen atmosphere after film formation.
This is because it is necessary to perform crystallization by firing at a temperature of about 1000 ° C. That is, the material of the lower electrode film 60 must be able to maintain conductivity under such an oxidizing atmosphere at a high temperature. In particular, when lead zirconate titanate is used for the piezoelectric film 70, the material of the It is desirable that the change in conductivity due to the diffusion of lead be small, and for these reasons, platinum is preferred.

Next, as shown in FIG. 4C, a piezoelectric film 70 is formed. The piezoelectric film 70 can be formed by a sputtering method, but in the present embodiment, a so-called sol in which a metal organic substance is dissolved and dispersed in a solvent is applied, dried, gelled, and further baked at a high temperature. A so-called sol-gel method for obtaining a piezoelectric film 70 made of a metal 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. 4D, 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.

Next, as shown in FIG. 5A, the piezoelectric film 70 and the upper electrode film 80 are etched to
20 patterning is performed.

At this time, in this embodiment, the piezoelectric film 70
And the upper electrode film 80 is continuously patterned from one longitudinal end of the piezoelectric active portion 320 to the peripheral wall of the pressure generating chamber 12 so that the upper electrode film 80 is used as an individual electrode of each piezoelectric active portion 320. The electrode film 60 is used as a common electrode.

Next, as shown in FIG. 5B, a tensile film 90 is formed. The tensile film 90 is desirably an insulating material and a material having a tensile stress after the film is formed. An organic film such as a polyimide resin and a fluororesin, and an oxide film such as titanium oxide and zirconium oxide can be used.

Further, as shown in FIG. 5C, the tensile film 90 is etched to remove the tensile film on the piezoelectric active portion 320. Thus, the amount of displacement of the piezoelectric body active section 320 is improved.

The above is the film forming process. After forming the film in this manner, as shown in FIG. 5D, the silicon single crystal substrate is anisotropically etched with the above-described alkali solution to form the pressure generating chamber 12 and the like. The state of the force applied to the piezoelectric body active section 320 at this time will be described below. FIG. 6 is a diagram schematically showing a state of stress generated in each layer before and after forming the pressure generating chamber 12 by etching.

As shown in FIG. 6A, the pressure generating chamber 12
Before formation, the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 8
0 and the tensile film 90 respectively have tensile stresses σ ₃ , σ ₂ , σ
₁ and σ ₅ , and the elastic film 50 has a compressive stress σ ₄ . Therefore, as shown in FIG. 6B, when the pressure generating chamber 12 is formed below the piezoelectric active part 320, the tensile stress σ _{3 of} the lower electrode film 60, the upper electrode film 80 of the piezoelectric film 70,
σ ₂ and σ ₁ are released and the forces F ₃ , F ₂ ,
F ₁ , the compressive stress σ ₄ of the elastic film 50 is released and becomes the force F ₄ acting in the tensile direction, that is, the force acting in the direction of pulling the piezoelectric film 70. Further, the tensile stress σ ₅ of the tensile film 90 is also released to become a force F ₅ acting in the compression direction. However, since the tensile film 90 is provided on both sides in the width direction of the piezoelectric film 70, the pressure generating chamber 12 is formed. In the region opposed to, the force acts substantially in the direction in which the piezoelectric film 70 is pulled. As described above, since the force in the tensile direction acts on the piezoelectric film 70 more strongly than in the related art, it is possible to suppress a decrease in the piezoelectric characteristics of the piezoelectric film 70. Further, under suitable conditions, the original piezoelectric characteristics of the piezoelectric film 70 can be maintained.

When the tensile film 90 is not formed, as shown in FIG. 7A, before forming the pressure generating chamber 12, the lower electrode film 60, the piezoelectric film 70 and the upper electrode film 80 are formed.
Has tensile stresses σ ₃ , σ ₂ , and σ ₁ , respectively. Therefore, when the pressure generating chamber 12 is formed, the tensile stresses σ ₃ , σ ₂ , and σ ₁ are released as shown in FIG. Compressive forces F ₃ , F ₂ and F ₁ are obtained. That is, the piezoelectric film 70 includes
A strong force in the compression direction acts, and the piezoelectric characteristics deteriorate.

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 forming substrate having one chip size as shown in FIG. Divide every ten. 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
By applying a voltage between the upper electrode film 80 and the lower electrode film 60 in accordance with a recording signal from an external drive circuit (not shown), the elastic film 50, the lower electrode film 60, and the piezoelectric film 70 are bent and deformed. The pressure in the pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle opening 11.

In this embodiment, the piezoelectric active portion 32
Although the tensile film 90 on the zero is removed and provided only on both sides in the width direction of the piezoelectric film 70, the present invention is not limited to this. For example, the tensile film 90 is
You may make it provide continuously. In this case, the tensile film 90 may also serve as an environment-resistant (moisture-resistant) protective film, so that a decrease in the piezoelectric characteristics of the piezoelectric layer 70 can be suppressed.

The tensile film 90 may also serve as an interlayer insulating film. In this case, a part of the tensile film 90 that covers the upper surface of the portion corresponding to one end of each of the piezoelectric active portions 320. Then, a contact hole (not shown) for exposing a part of the upper electrode film 80 for connection to the outside is formed,
A drive signal may be supplied to each upper electrode film 80 via this contact hole.

(Embodiment 2) FIG. 8 is a plan view and a sectional view of a main part of an ink jet recording head according to Embodiment 2.

In the present embodiment, as shown in FIG. 8, the lower electrode film 60 is patterned so that both ends in the width direction are located in a region facing the pressure generating chamber 12.
It extends from one end in the longitudinal direction of the pressure generating chamber 12 to the peripheral wall, and serves as an individual electrode of each piezoelectric active part 320.
Further, a piezoelectric film 70 is formed on the lower electrode film 60 so as to cover both ends in the width direction of the lower electrode film 60. The film 90 is formed without contacting the upper electrode film 80.

On the other hand, the upper electrode film 80 is
0 extends from one end in the longitudinal direction to the peripheral wall of the pressure generating chamber 12, extends from each piezoelectric active part 320, and is connected to the upper electrode film to form a common electrode.

In the present embodiment, since the lower electrode film 60 is patterned, the diaphragm is made up of the elastic film 50 and the insulator film 55, and the strength of the diaphragm is maintained.

The method of manufacturing the ink jet recording head of the present embodiment is not particularly limited, but in the present embodiment, it is formed as follows.

First, as shown in FIG. 9A, an insulator film 55 is formed on an elastic film 50 formed on a flow path forming substrate 10 as in the first embodiment. The insulator film 55 is made of a material having good adhesion to the piezoelectric film 70, for example, the piezoelectric film 7.
It is preferable to be formed of an oxide or nitride of at least one element selected from the constituent elements of 0. In the present embodiment, after the zirconium layer is formed on the elastic film 50, the insulating film 55 is made of zirconium dioxide by thermal oxidation in a diffusion furnace at about 1150 ° C., for example.

Next, as shown in FIG. 9B, the lower electrode film 60 is formed by sputtering, and at least the both ends in the width direction face the pressure generating chamber 12 in the region corresponding to the pressure generating chamber 12. Patterning so as to be located in the region to be formed.

Next, as shown in FIG. 9C, the piezoelectric film 70 and the upper electrode film 80 are formed and patterned to form the piezoelectric active portion 320. At this time, the patterning is performed such that the piezoelectric film 70 covers at least the side surfaces at both ends in the width direction of the lower electrode film 60 and both ends in the width direction of the piezoelectric film 70 are located in a region facing the pressure generating chamber 12.

Next, as shown in FIG. 9D, after forming the tensile film 90, the tensile film 90 on the piezoelectric active portion 320 is formed.
Is removed, and patterning is performed so that only the both sides in the width direction of the piezoelectric film 70 do not contact the upper electrode film 80.

After that, the pressure generating chamber 12 is formed by etching the flow path forming substrate 10. At this time, the state of the force applied to the piezoelectric active portion 320 of the present embodiment will be described below.

As shown in FIG. 10A, the pressure generating chamber 1
Before the formation of the second electrode film 2, the lower electrode film 60, the piezoelectric film 70, the upper electrode film 80, and the tensile film 90 have tensile stresses σ ₃ , σ ₂ ,
sigma _1, has a sigma _5, the elastic film 50 and the insulating film 55 has a compressive stress sigma ₄ and sigma _6. Therefore, as shown in FIG. 10B, the pressure generating chamber 1 is located below the piezoelectric active portion 320.
2, the force of the elastic film 50, the insulator film 55, and the tensile film 90 from which the stress is released is the same as in the first embodiment.
It acts in the direction in which the piezoelectric film 70 is pulled.

Therefore, also in the present embodiment, similarly to the first embodiment, a decrease in the piezoelectric characteristics of the piezoelectric film 70 can be suppressed. In the present embodiment, since both sides in the width direction of the lower electrode film 60 are covered with the piezoelectric film 70,
The tension film 90 and the lower electrode film 60 are insulated.
Therefore, if the tensile film 90 is formed so as not to contact the upper electrode film 80 as in the present embodiment, not only an insulating material but also a conductive material can be used. The choice of materials is expanded.

In the present embodiment, the lower electrode film 60 is used as an individual electrode of each piezoelectric active part 320 and the upper electrode film 80 is used as a common electrode. However, the present invention is not limited to this.
It goes without saying that 0 may be used as a common electrode and the upper electrode film 80 may be used as an individual electrode.

(Embodiment 3) FIG. 11 is a plan view and a cross-sectional view of a main part of an ink jet recording head according to Embodiment 3.

In the present embodiment, the tensile film 90 is
This is an example in which it also serves as 0, as shown in FIG.
In the present embodiment, except that the tensile film 90 (upper electrode film 80) is formed continuously on the piezoelectric active portions 320 arranged side by side in the width direction and is used as a common electrode of the piezoelectric active portions 320.
This is the same as the second embodiment.

In this structure, the tensile film 90 (upper electrode film 80) is formed after the piezoelectric film 70 is patterned, and thereafter, only the tensile film 90 (upper electrode film 80) is patterned. Can be.

Also, in such a configuration, FIG.
As shown in (a), before the pressure generating chamber 12 is formed, the lower electrode film 60, the piezoelectric film 70, and the tensile film 90 (the upper electrode film 80) have the tensile stresses σ ₃ , σ ₂ , and σ ₅ , respectively. Has,
The elastic film 50 and the insulator film 55 have compressive stresses σ ₄ and σ ₆ . Therefore, as shown in FIG. 12B, when the pressure generating chamber 12 is formed below the piezoelectric active portion 320,
In the present embodiment, the force from which the stress of the lower electrode film 60 and the piezoelectric film 70 is released acts in the direction of compressing the piezoelectric film 70, whereas the elastic film 50, the insulator film 55, and the tensile film 90 The force from which the stress of the (upper electrode film 80) is released acts in the direction in which the piezoelectric film 70 is pulled.

As described above, in the structure of the present embodiment, since the tensile film 90 also serves as the upper electrode film 80, the force acting in the direction of compressing the piezoelectric film 70 is reduced, that is, relatively. In addition, since the force acting in the direction of pulling the piezoelectric film 70 increases, the deterioration of the piezoelectric characteristics of the piezoelectric film 70 can be further suppressed.

(Other Embodiments) Although the embodiments of the present invention have been described above, 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 plate 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. 13 is an exploded perspective view of the embodiment configured as described above, and FIG. 14 is a sectional view of the flow channel. In this embodiment, the nozzle opening 11 is formed in the nozzle substrate 45 opposite to the piezoelectric element, and the nozzle communication port 22 for communicating the nozzle opening 11 and the pressure generating chamber 12 is formed with the sealing plate 20 and the common ink chamber. It is arranged so as to penetrate the forming plate 30, the thin plate 41A, and the ink chamber side plate 40A.

The present 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.

Also in this embodiment, similarly to the above-described embodiment, by providing the tensile film 90, a decrease in the piezoelectric characteristics of the piezoelectric film 70 is suppressed, and excellent ink ejection can be realized.

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.

Further, for example, an insulating layer is provided between the piezoelectric element and the lead electrode, or an anisotropic conductive film is heat-welded to each upper electrode without providing the insulating layer. The film may be connected to a 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. 15, recording head units 1A and 1B having an ink jet recording head are
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 as a recording medium such as paper fed by a paper feed roller is wound around the platen 8 and conveyed. It has become so.

[0093]

As described above, according to the present invention, the tensile films are provided on both sides in the width direction of the piezoelectric film.
When forming the pressure generating chamber, the force that releases the stress of the tensile film acts in the direction of pulling the piezoelectric film, suppressing the decrease in the piezoelectric characteristics of the piezoelectric film and substantially improving the ink ejection performance. can do.

[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 cross-sectional view illustrating a state of a force applied to the piezoelectric active portion according to the first embodiment of the present invention when the pressure generating chamber is formed.

FIG. 7 is a cross-sectional view showing a state of a force applied to a conventional piezoelectric active portion when a pressure generating chamber is formed.

FIG. 8 is a plan view and a sectional view of a main part of an ink jet recording head according to a second embodiment of the invention.

FIG. 9 is a cross-sectional view illustrating a thin-film manufacturing process according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating a state of a force applied to a piezoelectric body active portion according to a second embodiment of the present invention when a pressure generating chamber is formed.

FIG. 11 is a plan view and a cross-sectional view of a main part of an ink jet recording head according to a third embodiment of the invention.

FIG. 12 is a cross-sectional view illustrating a state of a force applied to a piezoelectric active portion according to a third embodiment of the present invention when a pressure generating chamber is formed.

FIG. 13 is an exploded perspective view of an ink jet recording head according to another embodiment of the present invention.

FIG. 14 is a sectional view of a main part of an ink jet recording head according to another embodiment of the present invention.

FIG. 15 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 11 nozzle opening 12 pressure generating chamber 50 elastic film 60 lower electrode film 70 piezoelectric film 80 upper electrode film 90 tensile film 300 piezoelectric element 320 piezoelectric active portion

Claims (12)

[Claims] 1. An ink jet apparatus comprising a piezoelectric element having a lower electrode, a piezoelectric layer, and an upper electrode in a region corresponding to the pressure generating chamber via a vibration plate constituting a part of the pressure generating chamber communicating with the nozzle opening. In the recording head, the ends of the piezoelectric layer constituting the piezoelectric element on both sides in the width direction are located in a region facing the pressure generating chamber, and at least both sides in the width direction of the piezoelectric layer have a tensile stress. An ink jet recording head, wherein a tensile film having the following is continuously provided. 2. The ink jet recording head according to claim 1, wherein the tensile film is provided in contact with end faces on both ends in the width direction of the piezoelectric layer. 3. The ink jet recording head according to claim 1, wherein the tensile film is provided in contact with the end surfaces of the piezoelectric layer and the upper electrode on both ends in the width direction. 4. The ink jet recording head according to claim 3, wherein the tensile film covers an upper surface of the upper electrode. 5. An ink jet recording head according to claim 1, wherein said tensile film is made of an insulating material. 6. An ink jet recording head according to claim 1, wherein said tensile film also serves as an environmental protection film. 7. An ink jet recording head according to claim 1, wherein said tensile film also serves as an interlayer insulating film. 8. An ink jet recording head according to claim 1, wherein said tensile film is made of an organic material. 9. An ink jet recording head according to claim 1, wherein said tensile film is made of a conductive material. 10. The ink jet recording head according to claim 1, wherein said tensile film also serves as an upper electrode. 11. 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 element is formed by film formation and lithography. An ink jet recording head, comprising: 12. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.