JPH11115185A - Ink-jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakage due to the excess current of a contact hole and breakdown due to migration by excess current. SOLUTION: A piezoelectric vibrator composed of a vibration plate which constitutes part of a pressure generation chamber 12 communicating with a nozzle opening and at least the upper surface of which acts as a lower electrode 60, and a piezoelectric material active part 320 consisting of a piezoelectric material layer 70 formed on the surface of the vibration plate and an upper electrode 80 formed on the surface of the layer 70 is provided. In an area opposite to the chamber 12, a contact part 90a to be a joint part between a lead electrode for applying voltage to the active part 320 and the active part 320 is formed. The upper electrode 80 has a thick film part 330 which is thicker than the other parts of the electrode 80 at least in a part corresponding to the contact part 90a.

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 discharging ink droplets, and which is constituted by a vibrating plate. The present invention relates to an ink jet recording head that ejects ink droplets by displacement of a layer.

[0002]

2. Description of the Related Art A part of a pressure generating chamber which communicates with a nozzle opening for discharging ink droplets is constituted by a vibrating plate. There are two types of ink-jet recording heads that eject ink droplets from a piezoelectric vibrator, one that uses a longitudinal vibration mode piezoelectric vibrator that expands and contracts in the axial direction of the piezoelectric vibrator, and the other that uses a flexural vibration mode piezoelectric vibrator. 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 the vibrating plate, 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 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. 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 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 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.

[0006] According to this, the work of attaching the piezoelectric vibrator to the diaphragm is not required, and the precision of the lithography method is used.
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 is 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 portion facing the pressure generating chamber and the portion straddling the outside thereof, the piezoelectric active portion composed of the piezoelectric layer and the upper electrode is required. It is desirable that the pressure sensor be provided in a region facing the pressure generating chamber or be formed so that at least one end portion does not come out of the region facing the pressure generating chamber.

Further, in a recording head using such a flexural mode piezoelectric vibrator, the piezoelectric vibrators corresponding to the respective pressure generating chambers are covered with an insulator layer, and each of the piezoelectric vibrators is covered with the insulator layer. A window (hereinafter, referred to as a contact hole) is provided for each pressure generating chamber to form a connection portion with a lead electrode that supplies a voltage for driving,
A connection portion between each piezoelectric vibrator and the lead electrode is formed in the contact hole.

[0009]

However, since the upper electrode is formed so thin that it does not hinder the deformation of the diaphragm, the resistance is large, whereas the lead electrode reliably supplies power to the piezoelectric layer. Therefore, it is necessary to reduce the resistance, and since the difference between the two resistances is large, the current is concentrated near the end of the contact hole, and the overcurrent destroys the contact hole or migrates due to the overcurrent. There is a problem that the layer causes dielectric breakdown.

In view of such circumstances, it is an object of the present invention to provide an ink jet recording head capable of preventing a contact hole from being destroyed due to an overcurrent and a dielectric breakdown caused by migration due to the overcurrent. .

[0011]

According to a first aspect of the present invention, there is provided:
A vibrating plate constituting a part of a pressure generating chamber communicating with the nozzle opening, at least an upper surface of which acts as a lower electrode, a piezoelectric layer formed on the surface of the vibrating plate, and a piezoelectric layer formed on the surface of the piezoelectric layer A piezoelectric vibrator comprising a piezoelectric active part comprising an upper electrode; a lead electrode for applying a voltage to the piezoelectric active part; and a contact part serving as a connection part between the piezoelectric active part and the lead electrode. In the ink jet recording head, the upper electrode has a thick film portion which is thicker than other main portions of the upper electrode at least in a portion corresponding to the contact portion.

In the first aspect, the difference in resistance between the upper electrode and the lead electrode is reduced, and concentration of current on a part of the contact portion is prevented.

According to a second aspect of the present invention, in the first aspect, an insulator layer is formed on an upper surface of the piezoelectric active portion,
The contact portion is formed in a contact hole formed in the insulator layer.

In the second aspect, the concentration of current when applying a voltage to the piezoelectric active portion in the contact hole is reduced, and the breakage of the piezoelectric layer around the contact hole is prevented.

According to a third aspect of the present invention, in the first or second aspect, at least one longitudinal end of the piezoelectric active portion extends to a portion facing a side wall of the pressure generating chamber, and the thick film The portion is formed from a portion near the longitudinal end of the pressure generating chamber to a portion facing the side wall, and the contact portion is formed in a region facing the side wall. is there.

In the third aspect, since the thick film portion is formed up to the region facing the vicinity of the longitudinal end of the pressure generating chamber, the driving of the piezoelectric active portion in this portion is suppressed,
The stress applied to the piezoelectric active portion can be reduced, and peeling, cracking and the like are prevented.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the upper electrode is thinner near the end of the piezoelectric active portion around the thick film portion than the thick film portion. An ink jet recording head is characterized in that:

In the fourth aspect, the residual stress applied to the end of the piezoelectric active portion around the thick film portion is reduced, and the resistance of the upper electrode at the end of the piezoelectric active portion is high. When a current is supplied to the piezoelectric active portion, the current flows through the central portion in the width direction, so that breakage near the end of the piezoelectric active portion is prevented.

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

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

[0021]

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

(Embodiment 1) FIG. 1 is an assembly perspective view showing an ink jet recording head according to an embodiment 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 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 an elastic film 50 having a thickness of 1 to 2 μm and 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 a 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 are formed. The second (11) which forms an angle of about 70 degrees with the (111) plane and forms an angle of about 35 degrees with the above (110).
1) plane appears, and the etching rate of the (111) plane is about 1/18 as compared with the etching rate of the (110) plane.
This is performed using the property of being 0. By such anisotropic etching, two first (111)
Precision processing can be performed based on the depth processing of a parallelogram formed by two surfaces and two oblique second (111) surfaces, and the pressure generating chambers 12 can be arranged at 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 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 entirely covers one surface of the flow path forming substrate 10 on one surface, and also serves as a reinforcing plate for protecting the silicon single crystal substrate from impact and external force. In addition, the sealing plate 20
The other surface constitutes one wall surface of the common ink chamber 31.

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 opposite side of 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. (Piezoelectric element).

An insulator layer 90 having electrical insulation is formed so as to cover at least the periphery of the upper surface of each of the upper electrode films 80 and the side surfaces of the piezoelectric film 70. The insulator layer 90 is formed of a material that can be formed by a film formation method or shaped by etching, for example, silicon oxide, silicon nitride, or an organic material, preferably photosensitive polyimide having low rigidity and excellent electrical insulation. Is preferred.

FIG. 4 shows a planar positional relationship between the piezoelectric active portion and the pressure generating chamber and a cross section thereof.

As shown in FIG. 4A, the piezoelectric active portion 320 including the piezoelectric film 70 and the upper electrode film 80 is provided in a region facing the pressure generating chamber 12, and
As shown in the BB ′ section of FIG. 2B, the thickness of the upper electrode film 80 is formed in a portion corresponding to the contact hole 90 a formed in the insulator layer 90 and connecting the upper electrode film 80 and the lead electrode 100. Is provided with a thick film portion 330 thicker than other portions. In this embodiment, the thickness of the thick film portion 330 is 0.4 μm.
The thickness was formed. Further, in the portion other than the thick film portion 330, the upper electrode film 80 is formed to be thin as shown in the cross section CC ′ in FIG.
Is the thickness.

The upper electrode film 80 is first formed in a portion corresponding to the contact hole 90a with a predetermined thickness, for example, 0.3 μm in the present embodiment. The formation method is not particularly limited. For example, the film may be formed by masking a portion other than a predetermined portion. For example, the film may be formed by etching after forming the entire film. Thereafter, a whole is formed with a predetermined thickness, for example, 0.1 μm in this embodiment, and patterning is performed as described later. The upper electrode film 80 may be made of a material having high conductivity, and may be made of a metal such as Al, Au, Ni, Pt, or a conductive oxide. In the present embodiment, Pt is formed by sputtering.

By such a film forming process, the upper electrode film 80
Is formed to be thick at a portion corresponding to the contact hole 90a and thin at other portions.

The order of the above-mentioned film formation is not particularly limited, but it is not preferable to form a pattern on a predetermined portion after forming a thin film as a whole because the film may be peeled off in the patterning process. Alternatively, after a thick film is entirely formed, etching may be performed by ion milling or the like while partially leaving a thick film portion.

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. 5A, 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. 5B, 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
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 70 must be able to maintain conductivity at such a high temperature and in an oxidizing atmosphere. In particular, when PZT is used as 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.

Next, as shown in FIG. 5C, 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, the upper electrode film 80 is formed as described above. That is, as shown in FIG. 4D, first, the upper electrode film 80 is formed on a predetermined portion, in this embodiment, a portion corresponding to the contact hole, and then, as shown in FIG. , A film is formed with a predetermined thickness on the whole.

Next, as shown in FIG. 6, the lower electrode film 60,
The piezoelectric film 70 and the upper electrode film 80 are patterned.

First, as shown in FIG. 6A, 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. 6B, only the piezoelectric film 70 and the upper electrode film 80 are etched to
0 patterning is performed. Next, as shown in FIG. 6C, the piezoelectric active region is a region opposed to both sides in the width direction of each pressure generating chamber 12 (in FIG. 6, the pressure generating chamber 12 is not formed yet, but is indicated by a broken line). By removing portions of the lower electrode film 60 corresponding to the arms of the diaphragm on both sides of the portion 320, a lower electrode film removing portion 350 is formed. Thus, the lower electrode film removing section 3
By providing 50, the amount of displacement due to application of a voltage to the piezoelectric body active section 320 is improved.

It should be noted that the lower electrode removing section 350 is
The thickness may be reduced without completely removing 0.
Further, the lower electrode removing portion 350 is formed in a portion corresponding to the arm portion of the piezoelectric active portion 320, but is not limited thereto.
For example, it may be formed to the outer side in the longitudinal direction from both ends of the piezoelectric body active portion 320, or may be formed over substantially the entire peripheral portion of the pressure generating chamber 12. Needless to say, the lower electrode removing section 350 is not necessarily provided.

As described above, after patterning the lower electrode film 60 and the like, preferably, at least the periphery of the upper surface of each upper electrode film 80, and the piezoelectric film 70 and the lower electrode film 60.
Is formed so as to cover the side surfaces of the substrate (see FIG. 1).

The piezoelectric active portions 3 of the insulator layer 90
A contact hole 90a is formed in a part of a part covering the upper surface of a part corresponding to one end of 20. Then, each upper electrode film 8 is formed through the contact hole 90a.
A lead electrode 100 having one end connected to 0 and the other end extending to the connection terminal portion is formed.

FIG. 7 shows a process for forming such an insulator layer and a lead electrode.

First, as shown in FIG. 7A, an insulator layer 90 is formed so as to cover the periphery of the upper electrode film 80, the side surfaces of the piezoelectric film 70 and the lower electrode film 60. This insulator layer 9
The preferred material of 0 is as described above, but in this embodiment, a negative photosensitive polyimide is used.

Next, as shown in FIG. 7B, by patterning the insulator layer 90, each of the pressure generating chambers 12 is formed.
A contact hole 90a is formed in a portion corresponding to the vicinity of the end on the ink supply side. The contact hole 90
a may be provided at a portion of the pressure generating chamber 12 corresponding to the piezoelectric active portion 320, and may be provided at, for example, a central portion or a nozzle-side end portion.

Next, for example, a lead electrode 100 is formed by depositing a conductor such as Cr-Au on the entire surface and then patterning the conductor.

The above is the film forming process. After forming the film in this manner, as shown in FIG. 7C, the silicon single crystal substrate is subjected to anisotropic etching with the above-described alkali solution to form the pressure generating chamber 12 and the like.

In such an ink jet recording head, a number of chips are simultaneously formed on one wafer by the above-described series of film formation and anisotropic etching, and after the process is completed, as shown in FIG. It is divided into each flow path forming substrate 10 having a single chip size. 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 recording head thus configured takes in ink from an ink inlet 42 connected to external ink supply means (not shown),
After filling the inside with ink from 1 to the nozzle opening 11, according to a recording signal from an external driving circuit (not shown),
Lower electrode film 60 and upper electrode film 80 via lead electrode 100
Is applied between them, and the elastic film 50, the lower electrode film 60, and the piezoelectric film 70 are flexed and deformed, so that the pressure in the pressure generating chamber 12 increases and ink droplets are ejected from the nozzle openings 11.

As described above, the thick film portion 330 where the upper electrode film 80 is thick is formed in the portion corresponding to the contact hole 90a.
Is provided, the lead electrode 100 and the upper electrode film 80 are formed.
When a voltage is applied through the contact hole 90a, the current does not concentrate on a part of the contact hole 90a, and the contact hole 90a
Area can be effectively used for current supply, and it is possible to prevent the contact hole 90a from being broken by an overcurrent, or from causing dielectric breakdown due to migration due to the overcurrent.

Further, since the contact hole 90a can be effectively used for supplying current, the area of the contact hole 90a can be minimized, the displacement efficiency can be improved, and the total capacitance can be reduced. Further, when patterning the piezoelectric active portion 320 by ion milling or the like, the thick film portion 330 in which the upper electrode film 80 is formed thickly suppresses the damage to the piezoelectric film 70 and suppresses the piezoelectric film near the contact hole 90a. Destruction of the end of the body film 70 can be reduced.

(Embodiment 2) FIG. 8 shows a planar positional relationship between the piezoelectric active portion 320 and the pressure generating chamber 12 of the ink jet recording head according to Embodiment 2.

In this embodiment, one end of the piezoelectric active portion 320 is extended to a region facing the longitudinal side wall of the generation chamber 12, and a contact hole 90 a is formed in a region facing the side wall of the pressure generation chamber 12. The thick film portion 330A is the same as that of the first embodiment except that the thick film portion 330A is provided in a region corresponding to the contact hole 90a, that is, a region facing the side wall and a region facing near the end of the pressure generating chamber 12. .

Therefore, by adopting such a structure, as in the first embodiment, the current is not concentrated on a part of the contact hole 90a, and the contact hole 90a is destroyed by the overcurrent or the migration due to the overcurrent is prevented. It is possible to prevent dielectric breakdown due to the above.
Further, since the thick film portion 330A is formed up to a region facing the vicinity of the longitudinal end of the pressure generating chamber 12, the driving of the piezoelectric active portion 320 is suppressed, and the stress applied to the piezoelectric active portion 320 can be reduced. , Peeling, cracking, etc. can be prevented.

(Embodiment 3) FIG. 9 shows a planar positional relationship and a cross section of a lead electrode 100 and a piezoelectric active portion 320 of an ink jet recording head according to Embodiment 3.

In the present embodiment, as shown in FIG. 9, the upper electrode film 80 is formed on the piezoelectric active portion 32 around the thick film portion 330B.
The second embodiment is the same as the second embodiment except that it is formed to be thin in the vicinity of the zero end similarly to the portion other than the thick film portion 330B.

By adopting such a structure, as in the above-described embodiment, the current is not concentrated on a part of the contact hole 90a, and the contact hole 90a is destroyed by the overcurrent, or the migration is caused by the overcurrent. To prevent dielectric breakdown. Furthermore, since the upper electrode film 80 is formed to be thin in the vicinity of the end of the piezoelectric active portion 320 around the thick film portion 330B and like other portions, the residual stress at the end of the piezoelectric film 70 is reduced. In addition, since the resistance of the upper electrode film 80 at the end of the piezoelectric active portion 320 is high, the current flows through the central portion in the width direction when the current is supplied to the piezoelectric active portion 320. Therefore, the piezoelectric active part 3 by the repetitive driving
20 can be prevented from being broken near the end.

(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 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. 11 is an exploded perspective view of the embodiment configured as described above, and FIG. 12 is a cross-sectional view of the flow path thereof. 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.

In this embodiment, the thin plate 41
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.

In this embodiment, as in the first to third embodiments, the thick film portion is formed in the region corresponding to the contact hole, so that the current does not concentrate on the end of the contact hole. It is possible to prevent the contact hole from being destroyed due to the overcurrent and the insulation breakdown due to the migration due to the overcurrent.

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, in each of the above-described embodiments, the elastic film is provided separately from the lower electrode film as the vibration plate, but the lower electrode film may also serve as the elastic film.

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 spirit of the present invention is not contradicted.

[0076]

As described above, according to the present invention, the thickness of the upper electrode film in the region corresponding to the contact hole is provided to be thicker than the other main portions. Since the difference in resistance from the lead electrode is reduced and the current can be prevented from being concentrated near the end of the contact hole, the contact hole may be destroyed due to overcurrent, or the insulation may be damaged due to migration due to overcurrent. Can be prevented. Further, since the contact hole can be effectively used for current supply, the area of the contact hole can be minimized, and the area of the piezoelectric active portion required for forming the contact hole can be reduced. The total capacity can be reduced.

[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;

4A and 4B are a plan view and a cross-sectional view illustrating a main part of the ink jet recording head 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 view showing a thin film manufacturing process according to the first embodiment of the present invention.

FIG. 7 is a view showing a thin film manufacturing process according to the first embodiment of the present invention.

FIG. 8 is a plan view showing a main part of an ink jet recording head according to Embodiment 2 of the present invention.

FIG. 9 is a plan view and a cross-sectional view illustrating a main part of an inkjet recording head according to a third embodiment of the invention.

FIG. 10 is an exploded perspective view of 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.

[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 insulator layer 100 lead electrode 320 piezoelectric active portion 330, 330A, 330B thick film portion 350 lower electrode Removal unit

Claims (5)

[Claims] 1. A vibrating plate constituting a part of a pressure generating chamber communicating with a nozzle opening, at least an upper surface of which functions as a lower electrode, a piezoelectric layer formed on a surface of the vibrating plate, and a piezoelectric layer A contact portion serving as a connecting portion between the lead electrode for applying a voltage to the piezoelectric active portion and a connecting portion between the piezoelectric active portion and a piezoelectric vibrator comprising a piezoelectric active portion comprising an upper electrode formed on the surface; In the ink jet recording head, the upper electrode has a thick film portion which is thicker than other main portions of the upper electrode at least in a portion corresponding to the contact portion. head. 2. The piezoelectric element according to claim 1, wherein an insulating layer is formed on an upper surface of the piezoelectric active portion, and the contact portion is formed in a contact hole formed in the insulating layer. Inkjet recording head. 3. The pressure generating chamber according to claim 1, wherein at least one longitudinal end portion of the piezoelectric active portion is formed to extend to a portion facing a side wall of the pressure generating chamber. Wherein the contact portion is formed in a region facing the side wall from the vicinity of the longitudinal end of the ink jet recording head, and the contact portion is formed in a region facing the side wall. 4. The ink jet printer according to claim 1, wherein the upper electrode is thinner in the vicinity of an end of the piezoelectric active portion around the thick film portion than in the thick film portion. Type recording head. 5. 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: