JP2002225267A - Ink-jet recording head, its manufacturing method, and ink-jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet recording head which prevents crosstalk and improves an ink discharge characteristic, its manufacturing method, and an ink-jet recorder. SOLUTION: The ink-jet recording head is equipped with a fluid passage forming substrate 10 consisting of a silicon single crystal substrate in which a pressure generation chamber 12 communicating with a nozzle opening 21 is partitioned, a lower substrate 60 set through a diaphragm 50 on one face side of the fluid passage forming substrate 10, and a piezoelectric element 300 comprising a piezoelectric layer 70 and an upper electrode 80. At least at one part in a longitudinal direction of the side face of the pressure generation chamber 12, a curvature part 15 in which the side face is curved to the standard face in a longitudinal direction is set.

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. TECHNICAL FIELD The present invention relates to an ink-jet recording head for ejecting ink droplets by a method, 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 constituted by a vibrating plate, and the vibrating plate is deformed by a piezoelectric element to pressurize the ink in the pressure generating chamber and to form an ink through the nozzle opening. Ink jet recording heads that eject droplets use a longitudinal vibration mode piezoelectric actuator in which piezoelectric elements expand and contract in the axial direction, and a flexural vibration mode piezoelectric actuator.
The types have 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 element into contact with the diaphragm, so that a head suitable for high-density printing can be manufactured. There is a problem in that a difficult process of cutting into a comb shape in accordance with the arrangement pitch of the openings and an operation of positioning and fixing the cut piezoelectric element in the pressure generating chamber are required, and the manufacturing process is complicated.

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

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

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

[0007]

However, in such an ink jet recording head, since the pressure generating chambers are formed to penetrate the flow path forming substrate, when the arrangement density of the pressure generating chambers is increased, the pressure generating chambers will not generate pressure. There is a problem that the thickness of the partition wall that partitions the chamber becomes thin, and crosstalk occurs between adjacent pressure generating chambers.

In addition, since the inner surface of the pressure generating chamber is flat, the partition wall defining the pressure generating chamber is apt to fall down, and the flow resistance of the ink is low, so that the ink in the pressure generating chamber after ink ejection is attenuated. However, there is a problem that it takes a long time to obtain good ink ejection characteristics.

In view of such circumstances, an object of the present invention is to provide an ink jet recording head which prevents crosstalk and has improved ink ejection characteristics, a method of manufacturing the same, and an ink jet recording apparatus.

[0010]

According to a first aspect of the present invention, there is provided a flow path forming substrate comprising a silicon single crystal substrate in which a pressure generating chamber communicating with a nozzle opening is defined. In an ink jet recording head including a lower electrode, a piezoelectric element including a piezoelectric layer and an upper electrode via a vibration plate on one surface side of a path forming substrate, at least a part of a side surface of the pressure generating chamber in a longitudinal direction is provided. An ink jet recording head is characterized in that the side surface has a curved portion curved with respect to a reference surface in a longitudinal direction.

In the first aspect, the rigidity of the partition walls defining the pressure generating chamber increases, and the flow resistance of the ink in the pressure generating chamber increases, so that the decay time of the vibration of the ink in the pressure generating chamber is shortened. .

A second aspect of the present invention is the ink jet recording head according to the first aspect, wherein the curved portion is provided continuously over the entire surface of the side surface in the longitudinal direction. .

In the second aspect, the rigidity of the partition walls defining the pressure generating chamber is reliably increased, and the flow resistance of the ink in the pressure generating chamber is reliably increased.

According to a third aspect of the present invention, in the second aspect, the curved portion is provided such that a thickness of a partition wall defining the pressure generating chamber is substantially constant. In the ink jet recording head.

In the third aspect, by providing the curved portion so that the thickness of the partition is substantially constant, the rigidity of the partition can be increased and crosstalk can be prevented.

According to a fourth aspect of the present invention, in the first aspect, the curved portion is provided near the nozzle opening and the width of the pressure generating chamber is widened by the curved portion. The feature is the ink jet recording head.

According to the fourth aspect, the pressure generating chamber and the nozzle opening can be easily and reliably connected to each other when the flow path forming substrate and the nozzle plate are joined.

According to a fifth aspect of the present invention, in the first aspect, the curved portion is provided near an end on an ink supply path side for supplying ink to the pressure generating chamber. In the recording head.

In the fifth aspect, the pressure returning to the ink supply path side can be reduced by the curved portion, and the ink can be ejected with a low driving voltage.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the main surface of the silicon single crystal substrate is (1).
10) An ink jet recording head characterized in that the orientation is azimuth.

In the sixth aspect, the pressure generating chamber having the curved portion can be formed easily and with high precision.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the pressure generating chamber and the curved portion are formed by anisotropically etching the flow path forming substrate. An ink jet recording head is characterized in that:

In the seventh aspect, the pressure generating chamber having the curved portion can be easily and accurately formed by the anisotropic etching.

An eighth aspect of the present invention is the ink jet recording head according to any one of the first to seventh aspects, wherein the piezoelectric layer is made of lead zirconate titanate (PZT).

In the eighth aspect, the piezoelectric elements can be arranged at a high density, and the head can be reduced in size.

According to a ninth 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 eighth aspects.

According to the ninth aspect, it is possible to realize an ink jet recording apparatus with improved ink ejection characteristics.

According to a tenth aspect of the present invention, there is provided a flow path forming substrate formed of a silicon single crystal substrate in which a pressure generating chamber communicating with a nozzle opening is formed, and a diaphragm provided on one side of the flow path forming substrate. In a method of manufacturing an ink jet recording head for forming a piezoelectric element including a lower electrode, a piezoelectric layer, and an upper electrode formed of a thin film formed by film formation and a lithography method, the vibration is applied to one surface of the flow path forming substrate. Forming a plate and a lower electrode and forming a protective film on the other surface, forming or removing at least a part of a region of the protective film that becomes the pressure generating chamber to form a removed portion, Applying and firing a (PZT) precursor to be a body layer, forming the upper electrode on the piezoelectric layer,
A step of patterning the piezoelectric layer and the upper electrode to form the piezoelectric element, and an anisotropic etching using the protective film as a mask pattern to a side surface facing the removed portion with respect to a longitudinal reference plane. Forming the pressure generating chamber having a curved portion that bends.

In the tenth aspect, the pressure generating chamber having the curved portion can be easily and accurately formed.

According to an eleventh aspect of the present invention, in the tenth aspect, the removing portion is formed over a region where the pressure generating chamber is formed, and is formed over the entire lengthwise side surface of the pressure generating chamber. And forming the curved portion continuously.

In the eleventh aspect, the curved portion can be formed easily and with high precision.

According to a twelfth aspect of the present invention, in the ink jet type according to the eleventh aspect, the curved portion is formed such that a thickness of a partition wall defining the pressure generating chamber is substantially constant. A method for manufacturing a recording head.

In the twelfth aspect, by providing the curved portion so that the thickness of the partition is substantially constant, the rigidity of the partition can be increased and crosstalk can be prevented.

According to a thirteenth aspect of the present invention, in the tenth aspect, the removing portion is formed in a region communicating with the nozzle opening of the pressure generating chamber, and is formed in a region communicating with the nozzle opening of the pressure generating chamber. The method of manufacturing an ink jet recording head according to claim 1, wherein the curved portion is formed.

According to the thirteenth aspect, the curved portion can be easily and accurately formed in a region communicating with the nozzle opening of the pressure generating chamber, and the pressure generating chamber can be formed at the time of joining the nozzle plate and the flow path forming substrate. It is possible to easily and surely communicate with the nozzle opening.

According to a fourteenth aspect of the present invention, in the tenth aspect, the removing section is formed near an end on an ink supply path side for supplying ink to the pressure generating chamber, and the ink supply section of the pressure generating chamber is provided. A method of manufacturing an ink jet recording head, wherein the curved portion is formed in a roadside area.

In the fourteenth aspect, the curved portion can be easily and accurately formed on the ink supply path side, and the ink in the pressure generating chamber is prevented from returning to the ink supply path side so that the ink is supplied at a low driving voltage. Can be ejected.

A fifteenth aspect of the present invention is the method for manufacturing an ink jet recording head according to any one of the tenth to fourteenth aspects, wherein the piezoelectric layer is made of lead zirconate titanate (PZT). It is in.

In the fifteenth aspect, the piezoelectric elements can be arranged at a high density, and the head can be reduced in size.

A sixteenth aspect of the present invention is the method for manufacturing an ink jet recording head according to any one of the tenth to fifteenth aspects, wherein the main surface of the silicon single crystal substrate has a (110) orientation. It is in.

According to the sixteenth aspect, the pressure generating chamber having the curved portion can be formed easily and with high precision.

[0042]

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 of the ink jet recording head, and FIG. It is sectional drawing of the pressure generation chamber of an ink jet type recording head, and its AA 'sectional drawing.

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. One surface of the flow path forming substrate 10 is an opening surface,
On the other surface, an elastic film 50 having a thickness of 0.1 to 2 μm and made of silicon dioxide formed in advance by thermal oxidation is formed.

In the flow path forming substrate 10, pressure generating chambers 12 partitioned by a plurality of partition walls 11 are anisotropically etched so as to be arranged side by side in the width direction. On the outside in the longitudinal direction, there is formed a communication part 13 which forms a part of a reservoir 100 which communicates with a reservoir part of a reservoir forming substrate which will be described later and serves as a common ink chamber of each pressure generation chamber 12. Each of the generating chambers 12 communicates with one longitudinal end of the generating chamber 12 via an ink supply path 14.

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 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, each pressure generating chamber 12
The long side is formed by a curved portion that is curved in the width direction of the pressure generating chamber 12 and the short side is formed by the second (111) plane with reference to the first (111) plane. I have. The pressure generating chamber 12 is formed by etching until it reaches the elastic film 50 substantially through the flow path forming substrate 10. Here, the amount of the elastic film 50 that is attacked by the alkaline solution for etching the silicon single crystal substrate is extremely small. Further, each ink supply passage 14 communicating with one end of each pressure generating chamber 12 is formed shallower than the pressure generating chamber 12. That is, the ink supply path 14 is formed by partially etching (half-etching) the silicon single crystal substrate in the thickness direction. Note that the half etching is performed by adjusting the etching time.

The thickness of such a flow path forming substrate 10 may be determined by selecting an optimum thickness according to the arrangement density of the pressure generating chambers 12. For example, if the arrangement density is about 180 per inch, , The thickness of the flow path forming substrate 10 is 220 μm
However, for example, in the case of arranging at a relatively high density of 200 or more per inch, the thickness of the flow path forming substrate 10 is preferably set to be relatively thin at 100 μm or less. This is because the partition 11 between the adjacent pressure generating chambers 12
This is because the arrangement density can be increased while maintaining the rigidity.

Further, at least a part of the side surface of the pressure generating chamber 12 in the longitudinal direction, for example, in this embodiment, the pressure generating chamber 1
A curved portion 15 whose side surface is curved with respect to the reference surface in the longitudinal direction is provided over the entire surface in the longitudinal direction. Here, the reference plane in the longitudinal direction is defined as (1) on the surface of the flow path forming substrate 10.
The first (111) plane perpendicular to the (10) plane, and the curved portion 15 continuously protrudes on both sides in the width direction of the pressure generating chamber 12 with respect to the first (111) plane. It is curved. The curved portion 15 is formed so as not to bend in the depth direction of the pressure generating chamber 12 but to be perpendicular to the surface.

The curved portions 15 provided on both side surfaces of the partition 11 are preferably formed so that the thickness of the partition 11 is substantially uniform in the longitudinal direction of the pressure generating chamber 12. Thereby, the rigidity of the partition 11 can be made uniform, and the ink ejection characteristics can be improved.

As described above, by providing the curved portion 15 on the side surface of the pressure generating chamber 12, the rigidity of the partition wall 11 can be increased, and the partition wall 11 is hard to fall down even if the arrangement density of the pressure generating chambers 12 is increased. Therefore, crosstalk can be prevented.

Further, by providing the curved portion 15 on the surface of the partition wall 11 of the pressure generating chamber 12, the flow resistance of the ink in the pressure generating chamber 12 can be increased. The vibration of the ink is attenuated in a short time, and high-speed driving can be performed.

As will be described in detail later, such a curved portion 15 is formed by diffusing Pb or the like on the surface of the silicon single crystal substrate and anisotropically etching the pressure generating chamber 12.
Are formed at the same time as

Further, on the opening side of the flow path forming substrate 10,
A nozzle plate 20 provided with a nozzle opening 21 communicating with the pressure supply chamber 12 on the side opposite to the ink supply path 14 is fixed via an adhesive or a heat welding film. The thickness of the nozzle plate 20 is, for example, 0.1 to 1
mm, the coefficient of linear expansion is 300 ° C. or less, for example, 2.5 to
4.5 [× 10 ⁻⁶ / ° C.] glass ceramic,
Or made of non-rusting steel. The nozzle 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.

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 21 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 21 need to be formed with a diameter of several tens of μm with high accuracy.

On the other hand, the lower electrode film 60 having a thickness of, for example, about 0.2 μm and the piezoelectric layer 70 having a thickness of, for example, about 1 μm are formed on the elastic film 50 provided on the flow path forming substrate 10. When,
The upper electrode film 80 having a thickness of, for example, about 0.1 μm is laminated and formed by a process described later, and forms the piezoelectric element 300. Here, the piezoelectric element 300 includes the lower electrode film 60,
A portion including the piezoelectric layer 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 layer 70 are connected to each of the pressure generating chambers 1.
It is structured by patterning every two. Here, a portion which is constituted by one of the patterned electrodes and the piezoelectric layer 70 and in which a piezoelectric strain is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion. In the present embodiment, the lower electrode film 60 is a common electrode of the piezoelectric element 300, and the upper electrode film 8
Although 0 is used as the individual electrode of the piezoelectric element 300, there is no problem even if this 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
The diaphragm and the vibration plate that is displaced by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator. In the example described above, the elastic film 50 and the lower electrode film 60 function as a diaphragm, but the lower electrode film may also serve as the elastic film.

The upper electrode film 80, which is an individual electrode of the piezoelectric element 300, is connected to an external wiring (not shown) via a lead electrode 90 extending from the vicinity of one longitudinal end of the piezoelectric element 300 on the elastic film 50. Have been.

Further, the piezoelectric element 30 of the flow path forming substrate 10
On the 0 side, a reservoir forming substrate 30 having a reservoir portion 31 constituting at least a part of the reservoir 100 is joined. In the present embodiment, the reservoir section 31 penetrates the reservoir forming substrate 30 in the thickness direction, and
2 and is communicated with the communicating portion 13 of the flow path forming substrate 10 as described above, and each of the pressure generating chambers 1 is formed.
The two reservoirs 100 serve as a common ink chamber.

As the reservoir forming substrate 30, it is preferable to use a material having substantially the same thermal expansion coefficient as that of the flow path forming substrate 10, for example, glass, ceramic material or the like. It was formed using a silicon single crystal substrate of the same material as that of No. 10. Thereby, even if both are bonded at a high temperature using a thermosetting adhesive, they can be securely bonded. Therefore, the manufacturing process can be simplified.

The piezoelectric element 3 of the reservoir forming substrate 30
A piezoelectric element holding portion 32 capable of sealing the space is provided in a region opposed to the piezoelectric element 300 while securing a space that does not hinder the movement of the piezoelectric element 300. Sealed inside. In the present embodiment, the piezoelectric element holding section 32 is formed to have a size that covers the plurality of piezoelectric elements 300 arranged in parallel.

Further, a compliance substrate 40 including a sealing film 41 and a fixing plate 42 is joined to the reservoir forming substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility (for example, a polyphenylene sulfide (PPS) film having a thickness of 6 μm).
One surface of the reservoir 31 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as a metal (for example, stainless steel (SUS) having a thickness of 30 μm).
Etc.). The area of the fixing plate 42 facing the reservoir 100 is the opening 4 completely removed in the thickness direction.
Therefore, one surface of the reservoir 100 is sealed with only the sealing film 41 having flexibility, thereby forming a flexible portion 45 that can be deformed by a change in internal pressure.

Further, an ink introduction port 44 for supplying ink to the reservoir 100 is formed on the compliance substrate 40 substantially outside the central portion of the reservoir 100 in the longitudinal direction. Further, the reservoir forming substrate 30 is provided with an ink introduction path 36 that communicates the ink introduction port 44 with the side wall of the reservoir 100.

The ink jet recording head of this embodiment takes in ink from the ink inlet 44 connected to an external ink supply means (not shown),
After the inside is filled with ink from 00 to the nozzle opening 21, each lower electrode film 60 corresponding to the pressure generating chamber 12 is formed according to a recording signal from an external driving circuit (not shown).
By applying a voltage between the upper electrode film 80 and the elastic film 50, the lower electrode film 60 and the piezoelectric layer 70 are flexed and deformed, the pressure in each pressure generating chamber 12 increases, and the nozzle opening 2
An ink droplet is ejected from 1.

Here, a method for manufacturing such an ink jet recording head will be described in detail. 4 and 5 are cross-sectional views in the direction in which the pressure generating chambers are juxtaposed, illustrating the method of manufacturing the ink jet recording head.

First, as shown in FIG. 4A, a silicon single crystal substrate wafer serving as the flow path forming substrate 10 is
The elastic film 50 made of silicon dioxide and the first protective film 55 are formed by thermal oxidation in a diffusion furnace at 0 ° C. The first protective film 55 is used as a mask pattern for forming the pressure generating chamber 12 in a later step.

Next, as shown in FIG. 4B, the lower electrode film 60 is formed by sputtering on the elastic film 50 of the flow path forming substrate 10.
It is formed over the entire upper surface and patterned into a predetermined shape. Preferable materials for the lower electrode film 60 include platinum and iridium. This is because it is necessary to crystallize a piezoelectric layer 70 described later formed by a sputtering method or a sol-gel method by firing at a temperature of about 600 to 1000 ° C. in an air atmosphere or an oxygen atmosphere after the film formation. Because. That is, the material of the lower electrode film 60 must be able to maintain conductivity under such high temperature and oxidizing atmosphere.
In particular, as the piezoelectric layer 70, lead zirconate titanate (PZ
When T) is used, it is desirable that the change in conductivity due to the diffusion of lead oxide is small, and for these reasons, platinum and iridium are preferred.

Next, as shown in FIG. 4C, the first protective film 55 is etched to form an opening 55a so as to open the entire region where the pressure generating chamber 12 is formed.

The opening 55a is for diffusing Pb or the like to the surface of the silicon single crystal substrate when the piezoelectric layer 70 is baked in order to form the curved portion 15; Since the portion 15 is formed continuously over the entire longitudinal surface of the side surface of the pressure generating chamber 12, the opening 55a
Is provided so that the entire region where the pressure generating chamber 12 is formed is open.

In this step of forming the opening 55 a in the first protective film 55, before firing the piezoelectric layer 70,
There is no particular limitation, and it may be performed before the step of forming the lower electrode film 60.

Further, in the present embodiment, the first protective film 5
5, an opening 55a is formed in a region where the curved portion 15 is formed;
Although the surface of the flow path forming substrate 10 is made to appear, the opening 5
An opening may be formed on the bottom surface of 5a, that is, on the surface of the flow path forming substrate 10 while leaving the first protective film 55 thin. Thus, the shape, density, and the like of the curved portion 15 can be controlled by the thickness of the first protective film 55 left on the bottom surface of the opening.

Next, as shown in FIG. 4D, a PZT precursor to be the piezoelectric layer 70 is applied and fired to form the piezoelectric layer 70.

In the present embodiment, for example, in the present embodiment, a so-called sol in which a metal organic material is dissolved and dispersed in a catalyst is applied, dried and gelled, and then fired at a high temperature to form a piezoelectric material made of a metal oxide. The layer 70 was formed by using a so-called sol-gel method. As a material for the piezoelectric layer 70, a PZT-based material is suitable when used in an ink jet recording head. The method for forming the piezoelectric layer 70 is not particularly limited. For example, the piezoelectric layer 70 may be formed by a spin coating method such as a sputtering method or a MOD method (organic metal thermal coating decomposition method).

Also, a method of forming a precursor film of lead zirconate titanate by a sol-gel method, a sputtering method, a MOD method, or the like, and then crystallizing the film at a low temperature by a high-pressure treatment in an alkaline aqueous solution may be used. Good.

In firing the piezoelectric layer 70, the first
Pb and the like are diffused into the surface layer of the region facing the opening 55a of the flow path forming substrate 10 by the opening 55a of the protective film 55. By diffusing Pb or the like into the surface layer of the silicon single crystal substrate in this manner, when the pressure generating chamber 12 is formed by anisotropic etching in a later step, the region where the opening 55a is provided, A curved portion 15 is formed on the entire surface in the longitudinal direction of the side surface of the generation chamber 12. In addition, a thin second protective film 56 made of silicon dioxide is formed on the surface of the flow path forming substrate 10 facing the opening 55a by thermal oxidation. As described above, when the first protective film 55 is left thin on the bottom surface of the opening 55a, the second protective film 56 is not formed.

Next, as shown in FIG. 5A, an upper electrode film 80 is formed on the piezoelectric layer 70, and only the piezoelectric layer 70 and the upper electrode film 80 are etched to pattern the piezoelectric element 300. Do.

The upper electrode film 80 may be made of any material having high conductivity, and may be made of a number of metals such as aluminum, gold, nickel and platinum, or a conductive oxide. In the present embodiment, platinum is formed by sputtering.

Next, as shown in FIG. 5B, a lead electrode 90 is formed over the entire surface of the flow path forming substrate 10 and is patterned for each piezoelectric element 300.

The above is the film forming process. After forming the film in this manner, anisotropic etching of the silicon single crystal substrate was performed using the above-described alkali solution, and FIG.
As shown in (c), the pressure generating chamber 12, the communication section 13, and the ink supply path 14 are formed.

At this time, the surface of the region where the pressure generating chambers 12 of the flow path forming substrate 10 are formed is formed with an opening 55a through the opening 55a.
Since b and the like are diffused, the curved portion 15 is formed over the entire lengthwise side surface of the pressure generating chamber 12.

Here, the shape of the curved portion 15 is determined by the amount of Pb or the like diffused into the flow path forming substrate 10. Therefore, as described above, the opening 55a of the first protective film 55
By leaving the first protective film 55 with a predetermined thickness on the bottom surface of the substrate, the amount of Pb or the like diffused into the flow path forming substrate 10 can be adjusted to control the shape of the curved portion 15.

In this embodiment, the first protective film 55
Can be used as a mask pattern for forming the pressure generating chamber 12 as it is. The opening 55
The second protective film 56 formed on the bottom surface of a is very thin, and can be easily removed when anisotropic etching with an alkaline solution is performed.

By a series of film formation and anisotropic etching as described above, a number of chips are simultaneously formed on one wafer, and after the process is completed, a flow path forming substrate of one chip size as shown in FIG. Divide every ten. Then, the nozzle plate 20, the reservoir forming substrate 30, and the compliance substrate 40 are sequentially bonded to and integrated with the divided flow path forming substrate 10 to obtain an ink jet recording head.

(Embodiment 2) FIG. 6A shows Embodiment 2.
It is a plan view of an inkjet recording head according to,
(B) is a principal part enlarged plan view.

As shown in the figure, the present embodiment is the same as the first embodiment except that the curved portion 15A is provided only near the end on the ink supply path 14 side of the pressure generating chamber 12A. It is.

By providing the curved portion 15A near the end on the ink supply path 14 side, the pressure generating chamber 12A
The pressure within which the ink returns to the ink supply path 14 can be reduced. Accordingly, the ink in the pressure generating chamber 12A can be ejected at a low pressure, so that the ink jet recording head can be driven at a low driving voltage.

The area where the curved portion 15A is formed is not limited to this. For example, the curved portion 15A may be
It may be provided on the side of the nozzle opening 21 of 2A or substantially at the center. As a method of forming the curved portion 15A only in the predetermined region in this way, in the step shown in FIG. 4C, the opening 55a may be provided only in the region where the curved portion 15A is to be formed. The portion 15A is a pressure generating chamber 12A
The opening 55a is formed to have a width substantially equal to the width of the pressure generating chamber 12A.

Note that, as in the present embodiment, the pressure generating chamber 12
When providing the curved portion 15A in a part of the longitudinal direction of A,
Since the opening of the first protective film 55 is formed only in the region where the curved portion 15A is formed, the flow path forming substrate 10
Is formed by anisotropic etching, it is necessary to further pattern the first protective film 55 to provide an opening in a region where the pressure generating chamber 12A is formed.

(Embodiment 3) FIG. 7A shows Embodiment 3.
It is a plan view of an inkjet recording head according to,
(B) is a principal part enlarged plan view.

As shown in the figure, the present embodiment is different from the above-described first embodiment except that the curved portion 15B is provided only near the end on the side communicating with the nozzle opening 21 on the side surface of the pressure generating chamber 12B. The same is true.

The curved portion 15B is provided so that the width of a region communicating with the nozzle opening 21 of the pressure generating chamber 12B is wider than other portions. That is, the pressure generating chamber 1
Each of the curved portions 15B provided on both side surfaces of the 2B,
The pressure generating chamber 12B is provided so as to be curved so as to protrude outward in the width direction.

As described above, the curved portion 15B
The shape of the first protective film 55 in the step shown in FIG.
It can be controlled by appropriately leaving the first protective film 55 on the bottom surface of the opening 55a formed by patterning, that is, the surface of the flow path forming substrate 10. In particular,
The shape of the curved portion 15B can be controlled by adjusting the diffusion amount of Pb or the like in a region opposed to the opening of the flow path forming substrate 10 by the thickness of the first protective film 55 left on the surface of the flow path forming substrate 10. it can.

As described above, by forming the curved portion 15B in a region communicating with the nozzle opening 21 of the pressure generating chamber 12B,
When the flow path forming substrate 10 and the nozzle plate 20 are joined, the pressure generating chamber 12B and the nozzle opening 21 can be reliably communicated even if a slight displacement occurs.

In addition to the curved portion 15B of the present embodiment,
A curved portion 15A similar to that of Embodiment 2 described above may be provided at the end of the pressure generating chamber 12B on the ink supply path 14 side.

(Other Embodiments) The first to third embodiments of the present invention have been described above. However, the basic structure of the ink jet recording head and its manufacturing method is not limited to the above.

In the first to third embodiments described above, the pressure generating chambers 12, 12A, and 12B are provided so as to penetrate the flow path forming substrate 10. However, the present invention is not limited to this. For example, a shallow pressure generating chamber may be used. . In any case, at least a part of the side surface of the pressure generating chamber in the longitudinal direction has a curved portion 15, 15A, 15B.
By providing the same, the same effect as in the first to third embodiments described above can be obtained.

The ink jet recording head according to the above-described embodiment forms 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. 2 is a schematic diagram illustrating an example of the ink jet recording apparatus.

As shown in FIG. 8, the recording head units 1A and 1B having ink jet recording heads are provided with detachable cartridges 2A and 2B constituting ink supply means.
The carriage 3 on which B is mounted is provided movably in the axial direction on a carriage shaft 5 attached to the apparatus main body 4. The recording head units 1A and 1B are, for example,
Each of them ejects a black ink composition and a color ink composition.

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

[0099]

As described above, according to the present invention,
At least a part of the side surface of the pressure generating chamber in the longitudinal direction is provided with a curved portion whose side surface is curved in the width direction from the reference surface in the longitudinal direction, thereby increasing the rigidity of the partition wall defining the pressure generating chamber and preventing crosstalk. In addition, the ink in the pressure generating chamber can be attenuated in a short time to improve the ink ejection characteristics. Further, by providing the curved portion at the end on the ink supply path side, the pressure toward the ink supply path side in the pressure generating chamber can be reduced, and the drive voltage for driving the piezoelectric element can be reduced. Furthermore, by providing the curved portion in a region communicating with the nozzle opening of the pressure generation chamber so that the width of the pressure generation chamber is widened, even if the nozzle plate is displaced during bonding with the flow path forming substrate, the nozzle plate and the pressure generation chamber may be displaced. It is possible to reliably communicate with the nozzle opening.

[Brief description of the drawings]

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

FIG. 2 is a plan view of the ink jet recording head according to the first embodiment of the present invention.

FIGS. 3A and 3B are cross-sectional views of an ink jet recording head according to Embodiment 1 of the present invention, in which FIG. 3A is a cross-sectional view of a pressure generating chamber in a longitudinal direction, and FIG. It is.

FIG. 4 is a cross-sectional view in a direction in which pressure generating chambers are arranged in a manufacturing process of the ink jet recording head according to Embodiment 1 of the present invention.

FIG. 5 is a cross-sectional view in a direction in which pressure generating chambers are arranged in a manufacturing process of the ink jet recording head according to Embodiment 1 of the present invention.

FIG. 6 is a plan view of an ink jet recording head according to Embodiment 2 of the present invention.

FIG. 7 is a plan view of an ink jet recording head according to Embodiment 3 of the present invention.

FIG. 8 is a schematic diagram of an ink jet recording apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flow path forming substrate 11 Partition wall 12, 12A, 12B Pressure generating chamber 13 Communication part 14 Ink supply path 15, 15A, 15B Curved part 20 Nozzle plate 21 Nozzle opening 30 Reservoir forming substrate 40 Compliance substrate 50 Elastic film 60 Lower electrode film 70 Piezoelectric layer 80 Upper electrode film 90 Lead electrode 100 Reservoir

Claims (16)

[Claims] 1. A flow path forming substrate formed of a silicon single crystal substrate in which a pressure generating chamber communicating with a nozzle opening is defined, and a lower electrode and a piezoelectric body on one surface side of the flow path forming substrate via a diaphragm. In the ink jet recording head comprising a layer and a piezoelectric element comprising an upper electrode, at least a part of the side of the pressure generating chamber in the longitudinal direction,
An ink jet recording head according to claim 1, wherein said side surface has a curved portion curved with respect to a reference surface in a longitudinal direction. 2. The ink jet recording head according to claim 1, wherein the curved portion is provided continuously over the entire surface of the side surface in the longitudinal direction. 3. The ink jet recording head according to claim 2, wherein the curved portion is provided so that a thickness of a partition wall defining the pressure generating chamber is substantially constant. 4. The ink jet recording head according to claim 1, wherein the curved portion is provided near the nozzle opening, and the width of the pressure generating chamber is widened by the curved portion. 5. The ink jet recording head according to claim 1, wherein the curved portion is provided near an end on an ink supply path side for supplying ink to the pressure generating chamber. 6. The ink jet recording head according to claim 1, wherein a main surface of the silicon single crystal substrate has a (110) orientation. 7. The ink jet recording head according to claim 1, wherein the pressure generating chamber and the curved portion are formed by anisotropically etching the flow path forming substrate. . 8. An ink jet recording head according to claim 1, wherein said piezoelectric layer is made of lead zirconate titanate (PZT). 9. An ink jet recording apparatus comprising the ink jet recording head according to claim 1. 10. A flow path forming substrate comprising a silicon single crystal substrate in which a pressure generating chamber communicating with a nozzle opening is defined;
A method of manufacturing an ink jet recording head for forming a piezoelectric element comprising a lower electrode, a piezoelectric layer, and an upper electrode formed of a thin film formed by film formation and lithography on one surface side of the flow path forming substrate via a vibration plate. In the step of forming the vibration plate and the lower electrode on one surface of the flow path forming substrate and forming a protective film on the other surface, and thinning at least a part of the region of the protective film that becomes the pressure generating chamber or Removing and forming a removed portion; applying and firing a (PZT) precursor to be the piezoelectric layer; forming the upper electrode on the piezoelectric layer; Patterning the upper electrode to form the piezoelectric element, and performing anisotropic etching using the protective film as a mask pattern to curve the side facing the removed portion with respect to the reference plane in the longitudinal direction. Forming the pressure generating chamber having a curved portion having a curved portion. 11. The pressure generating chamber according to claim 10, wherein the removing portion is formed over a region where the pressure generating chamber is formed, and the curved portion is continuously formed over the entire lengthwise side surface of the pressure generating chamber. A method for producing an ink jet recording head, comprising: 12. The method according to claim 11, wherein the curved portion is formed such that a thickness of a partition wall defining the pressure generating chamber is substantially constant. 13. The pressure generating chamber according to claim 10, wherein the removing portion is formed in a region communicating with the nozzle opening of the pressure generating chamber, and the curved portion is formed in a region communicating with the nozzle opening of the pressure generating chamber. A method for manufacturing an ink jet recording head. 14. The pressure generating chamber according to claim 10, wherein the removing section is formed near an end on an ink supply path side for supplying ink to the pressure generating chamber, and the curved section is provided in a region of the pressure generating chamber on the ink supply path side. A method for producing an ink jet recording head, comprising: 15. The method according to claim 10, wherein
A method for manufacturing an ink jet recording head, wherein the piezoelectric layer is made of lead zirconate titanate (PZT). 16. In any one of claims 10 to 15,
A method for manufacturing an ink jet recording head, wherein a main surface of the silicon single crystal substrate has a (110) orientation.