JP2000318154A - Ink jet recording head and ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head and an ink jet recorder which can be applied even to high speed driving of a piezoelectric element while suppressing lowering of displacement thereof. SOLUTION: The ink jet recording head comprises a pressure generating chamber 12 communicating with the nozzle opening, and a piezoelectric element 300 comprising a lower electrode 60 provided in a region corresponding to the pressure generating chamber 12 through a diaphragm, a piezoelectric layer 70 provided on the lower electrode 60, and an upper electrode 80 provided on the surface of the piezoelectric layer 70 wherein a piezoelectric active part 320 serving as the substantial driving part for the piezoelectric element 300 is formed in a region opposite to the pressure generating chamber 12. The upper electrode 80 is made thin by forming a stripe electrode 102 narrower than the upper electrode 80 along the longitudinal direction thereof in the region on the upper electrode 80 becoming the piezoelectric active part 320.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element formed in a part of a pressure generating chamber communicating with a nozzle opening for discharging an ink drop via a vibration plate, and the ink drop is discharged by displacement of the piezoelectric element. The present invention relates to an ink jet recording head 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 to pass through the nozzle opening. Two types of ink jet recording heads that eject ink droplets have been put into practical use, one using a longitudinal vibration mode piezoelectric actuator in which a piezoelectric element expands and contracts in the axial direction, and the other using a flexural vibration mode piezoelectric actuator. ing.

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

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

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

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

[0007]

However, when the piezoelectric element is formed as a thin film as described above, the piezoelectric material layer is formed to be extremely thin. The ratio of the causes is very large.

Further, since the piezoelectric material layer is a thin film, it has a large electric capacity and a large inflow current during driving. For this reason, in order to realize high-speed driving of the piezoelectric element, it is necessary to lower the electric resistance of the upper electrode, and there is a problem that the thickness of the upper electrode cannot be reduced.

In view of such circumstances, it is an object of the present invention to provide an ink jet recording head and an ink jet recording apparatus which can suppress a decrease in displacement of a piezoelectric element and can be applied to high-speed driving of the piezoelectric element. .

[0010]

According to a first aspect of the present invention for solving the above-mentioned problems, a pressure generating chamber communicating with a nozzle opening and a region corresponding to the pressure generating chamber are provided via a diaphragm. A piezoelectric element comprising a lower electrode, a piezoelectric layer provided on the lower electrode, and an upper electrode provided on the surface of the piezoelectric layer, wherein the piezoelectric element is substantially disposed in a region facing the pressure generating chamber. In the ink jet recording head in which the piezoelectric active portion serving as a simple driving portion is formed, the region serving as the piezoelectric active portion on the upper electrode has a width larger than the width of the upper electrode over the longitudinal direction of the upper electrode. An ink jet recording head is characterized in that a narrow band electrode having a small width is formed.

In the first aspect, a relatively large current can be applied to the upper electrode via the narrow band electrode when driving the piezoelectric element or the like, so that the film thickness of the upper electrode can be reduced and the rigidity of the upper electrode can be reduced. A reduction in the displacement of the piezoelectric active portion is suppressed. Further, since the narrow band electrode is formed with a relatively small width, there is no reduction in the displacement amount of the piezoelectric active portion due to the rigidity of the narrow band electrode.

According to a second aspect of the present invention, there is provided the ink jet recording head according to the first aspect, wherein the piezoelectric layer has crystals oriented preferentially.

In the second aspect, as a result of forming the piezoelectric layer in the thin film process, the crystals are preferentially oriented.

According to a third aspect of the present invention, there is provided an ink jet recording head according to the second aspect, wherein the piezoelectric layer has a columnar crystal.

In the third aspect, as a result of the piezoelectric layer being formed in the thin film process, the crystal has a columnar shape.

According to a fourth aspect of the present invention, in any one of the first to third aspects, a lead electrode for connecting the upper electrode to an external wiring is provided continuously from the narrow band electrode. An ink jet recording head is characterized in that:

According to the fourth aspect, the narrow band electrode and the external wiring are reliably connected via the lead electrode, and a relatively large current can be reliably supplied to the upper electrode.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the area covered by the narrow electrode is not more than １ ／ of the area of the piezoelectric active portion. The feature is the ink jet recording head.

In the fifth aspect, it is possible to reliably prevent the displacement of the piezoelectric active portion from being reduced due to the rigidity of the narrow band electrode.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the narrow electrode is extended substantially at the center in the width direction of the piezoelectric active portion. In the ink jet recording head.

In the sixth aspect, since the narrow electrode extends in the center of the piezoelectric active portion, the current flows substantially uniformly over the entire surface of the upper electrode.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects, at least a region of the upper electrode to be the piezoelectric active portion is formed with an electrically continuous film thickness. An ink jet recording head is characterized in that:

According to the seventh aspect, it is possible to more reliably prevent a reduction in the displacement of the piezoelectric active portion due to the rigidity of the upper electrode.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the film thickness of at least the region serving as the piezoelectric active portion of the upper electrode is less than 50 nm. In the ink jet recording head.

In the eighth aspect, since the elastic modulus of the upper electrode in the region to be the piezoelectric active portion is reduced, the reduction in the displacement of the piezoelectric active portion due to the rigidity of the upper electrode is more reliably prevented.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, an end of the lower electrode is provided at one end in a longitudinal direction of the pressure generating chamber, and the piezoelectric layer and the upper electrode are provided. The electrode extends to the outside thereof, and the end of the lower electrode serves as one end of the piezoelectric active portion.

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

According to a tenth aspect of the present invention, in any one of the fourth to ninth aspects, the lead electrode is extended on a peripheral wall of the pressure generating chamber and connected to the external wiring. The feature is the ink jet recording head.

According to the tenth aspect, the wiring can be easily and efficiently extracted from the piezoelectric active portion.

According to an eleventh aspect of the present invention, in any one of the fourth to ninth aspects, the lower electrode for wiring is provided discontinuously from the lower electrode and one end of which is connected to the external wiring. An ink jet recording head is provided for each piezoelectric element, wherein the lower electrode for wiring and the upper electrode are connected via the lead electrode.

In the eleventh aspect, the wiring can be easily and efficiently extracted from the piezoelectric active portion.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the lower electrode extends to the partition on both sides in the width direction of the pressure generating chamber and a region facing the adjacent pressure generating chamber. An ink jet recording head is provided continuously.

In the twelfth aspect, the rigidity of the diaphragm on both sides in the width direction of the piezoelectric active portion increases, and the durability improves.

According to a thirteenth aspect of the present invention, in any one of the first to eleventh aspects, the lower electrode constituting the piezoelectric element is provided for each of the pressure generating chambers, and at least both ends in the width direction are provided. Located in the area facing the pressure generating chamber,
An ink jet recording head is provided so as to extend from one longitudinal end of the pressure generating chamber to above a peripheral wall of the pressure generating chamber.

In the thirteenth aspect, since the lower electrode is provided in the region facing the pressure generating chamber, the displacement of the diaphragm caused by driving the piezoelectric active portion is improved.

According to a fourteenth aspect of the present invention, in the thirteenth aspect, the extending direction of the lower electrode to the peripheral wall is different from the extending direction of the lead electrode to the peripheral wall. In the recording head.

In the fourteenth aspect, the wiring of each piezoelectric element can be easily formed.

According to a fifteenth aspect of the present invention, in the thirteenth aspect, the extending direction of the lower electrode on the peripheral wall is the same as the extending direction of the lead electrode on the peripheral wall. And an ink jet recording head.

In the fifteenth aspect, the wiring can be easily pulled out without requiring an interlayer insulating film and a contact hole.

According to a sixteenth aspect, in the thirteenth aspect, in the thirteenth aspect, the lower electrode extends from at least one end in the longitudinal direction of a region facing the pressure generating chamber to the outside in the width direction to form a common electrode. An ink jet recording head is characterized in that:

In the sixteenth aspect, the wiring can be easily drawn without requiring an interlayer insulating film and a contact hole.

According to a seventeenth aspect of the present invention, in any one of the first to sixteenth 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.

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

An eighteenth aspect of the present invention is an ink jet recording apparatus comprising the ink jet recording head according to any one of the first to seventeenth aspects.

According to the eighteenth aspect, it is possible to realize an ink jet recording apparatus in which the driving efficiency of the head is improved and the ink can be ejected favorably.

[0046]

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

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

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

One surface of the flow path forming substrate 10 is an opening surface, and the other surface is formed with a 0.1 to 2 μm-thick elastic film 50 made of silicon dioxide previously formed by thermal oxidation.

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

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

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

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

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

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

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

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

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

On the other hand, the thickness of the elastic film 50 on the side opposite to the opening surface of the flow path forming substrate 10 is, for example, about 0.2 to
The lower electrode film 60 having a thickness of about 1 μm
And the upper electrode film 80 having a thickness of, for example, about 0.02 μm are laminated and formed by a process described later.
The piezoelectric element 300 is constituted. Here, the piezoelectric element 30
0 is the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 80
Means the part containing 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. In this case, the piezoelectric active portion 320 is constituted by one of the patterned electrodes and the piezoelectric film 70, and generates a piezoelectric strain by applying a voltage to both electrodes.
That. In the present embodiment, the lower electrode film 60 is
Although the common electrode is 0 and the upper electrode film 80 is an individual electrode of the piezoelectric element 300, it does not matter if the configuration is reversed for convenience of a drive circuit and wiring. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Further, here, the piezoelectric element 300 and the elastic film whose displacement is generated by driving the piezoelectric element 300 are collectively referred to as a piezoelectric actuator. In the present embodiment, as described later, since the lower electrode film 60 is patterned, the elastic film 50 functions 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 FIGS. 4 is a longitudinal sectional view of the pressure generating chamber 12, and FIG. 5 is a sectional view in the width direction.

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 a high temperature and oxidizing atmosphere. In particular, when the piezoelectric film 70 is made of lead zirconate titanate (PZT), It is desirable that the change in conductivity due to the diffusion of lead oxide is small, and for these reasons, platinum is preferred.

Next, as shown in FIG. 4C, the lower electrode film 60 is patterned into a predetermined shape. That is, the lower electrode film 60 is patterned in a region opposed to the vicinity of one end in the longitudinal direction of the pressure generation chamber 12, and for each pressure generation chamber 12,
The lower electrode film 61 for wiring, which is provided from the vicinity of one end in the longitudinal direction to a region facing the peripheral wall, and is a part of a wiring connecting the upper electrode film 80 of the piezoelectric active portion 320 and an external wiring.
To form

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

Further, a method of forming a PZT precursor film by a sol-gel method or a sputtering method, and then growing the crystal at a low temperature by a high-pressure treatment in an alkaline aqueous solution may be used.

In any case, in the piezoelectric film 70 thus formed, the crystal is preferentially oriented unlike the bulk piezoelectric material, and in the present embodiment, the crystal is formed in the piezoelectric film 70. It is formed in a column shape. Note that the preferential orientation refers to a state in which a crystal orientation direction is not disordered and a specific crystal plane is oriented in a substantially constant direction. In addition, a crystal having a columnar thin film refers to a state in which substantially columnar crystals are gathered in a plane direction with their central axes substantially aligned in the thickness direction to form a thin film. Of course, it may be a thin film formed of preferentially oriented granular crystals. The thickness of the piezoelectric film manufactured in the thin film process is generally 0.5 to 5 μm.

Next, as shown in FIG. 4E, an upper electrode film 80 is formed. The upper electrode film 80 only needs to be a material having high conductivity, and many metals such as aluminum, gold, nickel, platinum, and iridium, and a conductive oxide can be used. In the present embodiment, platinum is formed by sputtering. Further, the upper electrode film 80 is preferably formed to be electrically continuous and as thin as possible to a certain extent, for example, a thickness of less than 0.05 μm. It was formed with a thickness of 0.02 μm. As described above, by forming the upper electrode film 80 with a thickness of less than 0.05 μm, the elastic constant of the upper electrode film 80 becomes significantly smaller than when the upper electrode film 80 is formed as a thick film, The rigidity of the upper electrode film 80 becomes smaller.

Next, as shown in FIG. 5A, the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 80 are etched together to pattern the entire pattern of the lower electrode film 60. Only the film 70 and the upper electrode film 80 are etched to pattern the piezoelectric active part 320.

Next, as shown in FIG. 5B, an electrode layer 100 which will be described later as a lead electrode and a strip electrode is formed. The material of the electrode layer 100, that is, the material of the lead electrode and the strip electrode is not particularly limited, but is preferably a material having relatively low rigidity and low electric resistance, for example, gold (Au), aluminum (Al) or copper (Cu) is preferably used. In this embodiment,
Gold is used. Actually, gold is formed with a thickness of about 0.2 μm via chromium (Cr) in order to enhance the adhesiveness.

Next, as shown in FIG. 5C, the electrode layer 100 is patterned to correspond to the lead electrode 101 connecting the upper electrode film 80 and the lower electrode film 61 for wiring and at least the piezoelectric active portion 320. A narrow band electrode 102 having a width smaller than that of the upper electrode film 80 is formed in the region to be formed. In the present embodiment, the lead electrode 101 and the strip electrode 102 are provided continuously.

Here, the area covered by the narrow band electrode 102 is preferably equal to or less than １ ／ of the area of the piezoelectric active portion 320, and is desirably formed as narrow as possible. For example, in this embodiment, it is formed with a width of about 5 μm.

Thereafter, 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.

A large number of chips are simultaneously formed on one wafer by a series of film formation and anisotropic etching described above, and after the process is completed, a flow path forming substrate of 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.

FIG. 6 is a plan view and a cross-sectional view showing a main part of the ink jet recording head of the present embodiment thus formed.

As shown in FIG. 6, the lower electrode film 60 constituting the piezoelectric element 300 has a plurality of pressure generating chambers 12 arranged in parallel.
The lower electrode film 60 is continuously provided in a region opposed to the piezoelectric element 320 and is patterned in the vicinity of one longitudinal end of the pressure generating chamber 12. In addition, outside the end of the lower electrode film 60, the lower electrode film 60 extends from the region facing the pressure generating chamber 12 to the peripheral wall.
Is provided with a wiring lower electrode film 61 that is discontinuous. Although not shown, one end of the lower electrode film for wiring 61 is connected to an external wiring to form a part of the wiring of the piezoelectric element.

On the other hand, the piezoelectric film 70 and the upper electrode film 80 are basically provided in a region facing the pressure generating chamber 12 to form the piezoelectric active portion 320, and one end in the longitudinal direction has a wiring on the peripheral wall. It extends to the lower electrode film 61 for use. In the present embodiment, as described above, the upper electrode film 80 is formed so as to be electrically continuous and as thin as possible. Therefore, the driving of the piezoelectric active part 320 is not hindered by the rigidity of the upper electrode film 80, the displacement of the piezoelectric active part 320 is improved, and the ink ejection characteristics can be improved.

On the upper electrode film 80 constituting such a piezoelectric active portion 320, a narrow band electrode 102 having a width smaller than the width of the upper electrode film 80 extends in the longitudinal direction of the upper electrode film 80. It is formed. For example, in the present embodiment, one narrow band electrode 102 is extended substantially at the center in the width direction of the piezoelectric active portion 320. In the present embodiment, the lead electrode 101 extends continuously from the narrow band electrode 102 to the lower electrode film 61 for wiring, and the upper electrode film 80 and the lower electrode film 61 for wiring are interposed via the lead electrode 101. And are connected.

Here, when the film thickness of the upper electrode film 80 is reduced as described above, the displacement of the piezoelectric active portion 320 due to the rigidity of the upper electrode film 80 can be suppressed, but the electric resistance increases, so that high-speed driving is performed. Can not do. However, in the present embodiment, the upper electrode film 8 of the piezoelectric active portion 320 is used.
0, a narrow band electrode 102 made of a material having a low electric resistance is provided in the longitudinal direction.
Even if the film thickness of the upper electrode film 8
A current sufficient to drive the piezoelectric active portion 320 to zero can flow. In the present embodiment, the narrow band electrode 10
Since the lead electrodes 101 are continuously formed from No. 2, it is possible to reliably supply a current to the narrow band electrode 102 via the lead electrodes 101. Further, the strip electrode 1
02 is formed with a very small width as described above, so that the driving of the piezoelectric body active portion 320 is not hindered by the narrow band electrode 102, so that a sufficient displacement amount of the piezoelectric body active portion 320 And can be driven at high speed.

As described above, even in the case of the piezoelectric film 70 manufactured by the thin film process, the above-described configuration can reduce the film thickness of the upper electrode film 80 to lower the rigidity, and can reduce the thickness of the narrow band electrode. Since the electric resistance can be kept substantially low by the element 102, a sufficient amount of displacement of the piezoelectric body active portion 320 can be obtained, and high-speed driving can be performed.

In this embodiment, the lead electrode 101
Is continuously extended from the narrow band electrode 102 provided in the region facing the piezoelectric active portion 320 to the lower electrode film 61 for wiring. However, the present invention is not limited to this.
As shown in (a) and (b), the strip electrode 102 is independently formed on the upper electrode film 80 in a region facing the piezoelectric active portion 320.
A may be formed, and a lead electrode 101A for connecting the upper electrode film 80 and the lower electrode film 61 for wiring may be separately provided. Even with such a configuration, it is of course possible to obtain the same effects as those of the above-described embodiment.

In the case of such a configuration, for example, as shown in FIG. 7C, only the upper electrode film 80 constituting the piezoelectric active portion 320 may be a thin film portion 81 having a small thickness. Good. Thereby, the lead electrode 101 and the strip electrode 1
Since a relatively large current can flow through the upper electrode film 80 between the thin film portion 81 and the narrow band electrode 102, a current sufficient to drive the piezoelectric active portion 320 can flow more reliably.

Further, in the present embodiment, the narrow band electrode 102 is extended substantially at the center of the piezoelectric active portion 320 in the width direction. However, the present invention is not limited to this. For example, as shown in FIG.
The two narrow band electrodes 102B may be provided near both ends in the width direction of the piezoelectric body active portion 320, respectively. Even in such a configuration, a sufficient amount of displacement of the piezoelectric body active portion 320 can be obtained and the device can be driven at a high speed, as described above.

Further, in the present embodiment, the lower electrode film 60 is formed in the direction in which the pressure generating chambers 12 are juxtaposed to serve as a common electrode for the plurality of piezoelectric elements 300. However, the present invention is not limited to this. The film 60 may be patterned for each pressure generating chamber 12.

For example, as shown in FIG. 9A, the lower electrode film 60 is patterned for each piezoelectric element 300, and is extended from the end of the pressure generating chamber 12 opposite to the lead electrode 101 onto the peripheral wall. Alternatively, the common electrode may be connected to the lower electrode film 60 extending from each piezoelectric element 300 on the peripheral wall.

For example, as shown in FIG.
For example, the lower electrode film 60 serving as a common electrode is
2 may extend from the longitudinal end to the outer peripheral wall in the width direction. At this time, the position where the lower electrode film 60 crosses the end of the pressure generating chamber 12 is preferably within a width dimension from the longitudinal end of the pressure generating chamber 12. this is,
This is because the deformation due to the driving of the piezoelectric active portion 320 is not hindered. In the case of such a configuration, the upper electrode film 80
By applying a voltage between the upper electrode film 80 and the lower electrode film 60 in a region opposed to the pressure generating chamber 12 by applying a voltage between the upper electrode film 80 and the lower electrode film 60, become.

Also, for example, as shown in FIG.
The upper electrode film 80 and the lower electrode film 60 may extend on the peripheral wall from the same longitudinal end.

In any of the above configurations, the same effects as described above can be obtained by providing the narrow band electrode 102 in the longitudinal direction of the upper electrode film 80.

(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, a protective film made of an insulating material or the like may be further provided on the piezoelectric active portion 320, and the piezoelectric active portion 320 may be covered with this protective film. This can prevent the piezoelectric film 70 from being broken due to the external environment and the like, and can improve the durability. Further, even in such a configuration, a sufficient amount of displacement can be obtained by forming the upper electrode film 80 thin as described above and providing the narrow band electrode 102 thereon.

In the above-described embodiment, for example, the wiring lower electrode film 61 is provided from the vicinity of one longitudinal end of the pressure generating chamber 12 to the peripheral wall, and the wiring lower electrode film 61 and the upper electrode film 80 are provided. Are connected by the lead electrode 101, but the present invention is not limited to this. For example, the lead electrode 101 is extended on the peripheral wall without providing the lower electrode film 61 for wiring,
You may make it connect the lead electrode 101 and external wiring directly.

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

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

FIG. 10 is an exploded perspective view of the embodiment configured as described above, and FIG. 11 is a cross-sectional view of the flow path. In this embodiment, the nozzle openings 11 are bored in the nozzle substrate 120 opposite to the piezoelectric element, and the nozzle communication ports 22 for communicating the nozzle openings 11 and the pressure generating chambers 12 are formed with the sealing plate 20 and the common ink chamber. It is arranged so as to penetrate the formation substrate 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 40A. Is omitted.

Of course, 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.

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 or the like, and is mounted on an ink jet recording apparatus. FIG.
FIG. 1 is a schematic view showing an example of the ink jet recording apparatus.

As shown in FIG. 12, recording head units 1A and 1B having an ink jet recording head are
Cartridges 2A and 2B constituting ink supply means are 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.

Then, the driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears (not shown) and the timing belt 7, 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, a platen 8 is provided on the apparatus main body 4 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is wound around the platen 8. It is designed to be transported.

[0100]

As described above, according to the present invention, the upper electrode is formed with such a small thickness as not to hinder the driving of the piezoelectric active portion due to its rigidity. It can be significantly improved. In addition, since the narrow electrode having a width smaller than the width of the piezoelectric active portion is formed on the upper electrode in the longitudinal direction, even if the thickness of the upper electrode is thin, the narrow electrode is formed. Through the upper electrode, a current sufficient for driving the piezoelectric active portion can flow into the upper electrode. Thereby, the driving amount of the piezoelectric active portion is improved, and an ink jet recording head that can be driven at high speed can be realized.

[Brief description of the drawings]

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

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

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

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

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

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

FIGS. 7A and 7B are a plan view and a cross-sectional view of a main part showing a modified example of the ink jet recording head according to the first embodiment of the invention.

FIG. 8 is a main part plan view showing a modification of the ink jet recording head according to Embodiment 1 of the present invention.

FIG. 9 is a main part plan view showing a modification of the ink jet recording head according to Embodiment 1 of the present 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.

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

[Explanation of symbols]

 Reference Signs List 10 flow path forming substrate 12 pressure generating chamber 50 elastic film 60 lower electrode film 61 lower electrode film for wiring 70 piezoelectric film 80 upper electrode film 101, 101A lead electrode 102, 102A, 102B narrow electrode 300 piezoelectric element 320 piezoelectric active Department

Claims (18)

[Claims] 1. A pressure generating chamber communicating with a nozzle opening, a lower electrode provided in a region corresponding to the pressure generating chamber via a diaphragm, a piezoelectric layer provided on the lower electrode, and the piezoelectric body A piezoelectric element comprising an upper electrode provided on the surface of the layer, and an ink jet recording head in which a piezoelectric active portion serving as a substantial driving portion of the piezoelectric element is formed in a region facing the pressure generating chamber, An ink jet printing method, wherein a narrow band electrode having a width smaller than the width of the upper electrode is formed in a region on the upper electrode which is to be the piezoelectric active portion over a longitudinal direction of the upper electrode. Type recording head. 2. The ink jet recording head according to claim 1, wherein crystals of the piezoelectric layer are preferentially oriented. 3. The ink-jet recording head according to claim 2, wherein the piezoelectric layer has a columnar crystal. 4. The ink jet recording head according to claim 1, wherein a lead electrode for connecting the upper electrode to an external wiring is provided continuously from the narrow band electrode. . 5. The ink jet recording head according to claim 1, wherein the area covered by the narrow band electrode is equal to or less than １ ／ of the area of the piezoelectric active portion. 6. An ink jet recording head according to claim 1, wherein said narrow band electrode is extended substantially at the center in the width direction of said piezoelectric active portion. 7. An ink jet recording method according to claim 1, wherein at least a region of said upper electrode to be said piezoelectric active portion is formed to have an electrically continuous film thickness. head. 8. The ink jet recording head according to claim 1, wherein a film thickness of at least a region of said upper electrode to be said piezoelectric active portion is less than 50 nm. 9. The pressure generating chamber according to claim 1, wherein an end of the lower electrode is provided at one end in a longitudinal direction of the pressure generating chamber,
Further, the piezoelectric layer and the upper electrode extend to the outside thereof, and an end of the lower electrode serves as one end of the piezoelectric active section. 10. An ink jet recording head according to claim 4, wherein said lead electrode extends on a peripheral wall of said pressure generating chamber and is connected to said external wiring. 11. The piezoelectric element according to claim 4, wherein a wiring lower electrode is provided for each of the piezoelectric elements, the wiring lower electrode being provided discontinuously from the lower electrode and having one end connected to the external wiring. An ink jet recording head, wherein a lower electrode for wiring and the upper electrode are connected via the lead electrode. 12. The pressure sensor according to claim 1, wherein the lower electrode is provided continuously up to the partition wall on both sides in the width direction of the pressure generating chamber and a region facing the adjacent pressure generating chamber. An ink jet recording head characterized by the following. 13. The pressure generating chamber according to claim 1, wherein the lower electrode constituting the piezoelectric element is provided for each of the pressure generating chambers, and at least both ends in the width direction of the piezoelectric element face the pressure generating chamber. And extending from one longitudinal end of the pressure generating chamber to a peripheral wall of the pressure generating chamber. 14. The ink jet recording head according to claim 13, wherein a direction in which the lower electrode extends on the peripheral wall is different from a direction in which the lead electrode extends on the peripheral wall. 15. The ink jet recording head according to claim 13, wherein a direction in which the lower electrode extends on the peripheral wall and a direction in which the lead electrode extends on the peripheral wall are the same. 16. The method according to claim 13, wherein the lower electrode comprises:
An ink jet recording head, which extends from at least one end in the longitudinal direction of the region facing the pressure generating chamber to the outside in the width direction to form a common electrode. 17. 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 a lithography method. An ink jet recording head, comprising: 18. An ink jet recording apparatus comprising the ink jet recording head according to claim 1. Description: