JP2000108347A - Ink jet recording head, method of manufacturing the same, and ink jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head in which a characteristic of a piezoelectric element is prevented from deteriorating while maintaining a displacement efficiency of a diaphragm, a method of manufacturing the same, and an ink jet recording apparatus. A pressure generating chamber (12) formed in a silicon single crystal substrate communicating with a nozzle opening, an elastic film (50) constituting a part of the pressure generating chamber, and a lower electrode (60) provided on the elastic film (50) In the ink jet recording head including the piezoelectric layer 70 and the upper electrode 80, the lower electrode thin film portion 60a is formed in a region facing the pressure generating chamber 12.

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, 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 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, in the above-described manufacturing method using the thin film technology and the lithography method,
A pressure generating chamber is formed after patterning of the thin film. At this time, due to the effect of internal stress relaxation of the upper electrode and the piezoelectric layer,
There is a problem in that the diaphragm bends toward the pressure generating chamber, and the warp remains as initial deformation of the elastic film.

Generally, since the lower electrode extends from the region facing the pressure generating chamber to the peripheral wall and constitutes the diaphragm together with the elastic film, there is a problem that the displacement efficiency is low.
Also known is a structure in which the lower electrode on the both sides in the width direction of the pressure generating chamber, that is, the so-called lower part of the arm, is over-etched to remove part or all of the lower electrode to increase the displacement efficiency. Increases, and an increase in excluded volume cannot be expected. It is considered that this is because the elastic film reaches the plastic deformation region beyond the elastic region. Furthermore, since the lower electrode is thin, there is a problem that the resistance of the lower electrode is increased, causing a problem in power supply, and a part of the lower electrode is removed during patterning.

In view of such circumstances, it is an object of the present invention to provide an ink jet recording head, a method of manufacturing the same, and an ink jet recording apparatus in which the characteristics of the piezoelectric element are prevented from deteriorating while maintaining the displacement efficiency.

[0010]

According to a first aspect of the present invention, there is provided a pressure generating chamber communicating with a nozzle opening, an elastic film forming a part of the pressure generating chamber, and the elastic film. A lower electrode provided thereon, a piezoelectric layer formed on the lower electrode, and an inkjet recording head including an upper electrode formed on the piezoelectric layer, wherein the lower electrode is
An ink jet recording head is characterized in that at least a region facing the pressure generating chamber is formed to be thinner than other regions.

In the first aspect, since the thickness of the lower electrode is reduced in the region facing the pressure generating chamber, the change in stress does not affect the piezoelectric layer, and deterioration in characteristics is avoided. You.

According to a second aspect of the present invention, in the first aspect, a piezoelectric active portion comprising the piezoelectric layer and the upper electrode is formed in a region facing the pressure generating chamber, The lower electrode and the lower electrode on the both sides in the width direction have the same thickness.

In the second aspect, the deterioration of the characteristics of the piezoelectric element due to the change in the stress of the lower electrode is avoided.

According to a third aspect of the present invention, in the first or second aspect, the lower electrode in a region facing the peripheral wall separating the pressure generating chambers is thicker than a region facing the pressure generating chamber. And an ink jet recording head.

[0015] In the third aspect, the lower electrode is thickened in a region facing the peripheral wall to reduce the overall resistance.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the lower electrode has a laminated structure of a plurality of layers made of a plurality of materials, and the lower electrode has a structure in a region facing the pressure generating chamber. An ink jet recording head is characterized in that there is no part of a plurality of layers.

According to the fourth aspect, it is possible to improve the actuator characteristics by selecting an optimum lower electrode material according to a specific region.

According to a fifth aspect of the present invention, in the fourth aspect, a material forming at least a layer existing in a region facing the pressure generating chamber in the multilayer structure of the plurality of layers of the lower electrode is oxidized. An ink jet recording head comprising a conductor layer.

In the fifth aspect, the vibration plate is less likely to be plastically deformed, and the characteristic change of the piezoelectric element after the formation of the pressure generating chamber is prevented.

According to a sixth aspect of the present invention, in any one of the second to fifth aspects, the lower electrode has a thickness formed in a part of a region below the piezoelectric layer thicker than other parts. An ink jet recording head having a film portion, wherein the thick film portion extends to a region from which the piezoelectric layer has been removed.

According to the sixth aspect, the electrical connection between the lower electrode of the piezoelectric active portion and the lower electrode other than the region facing the pressure generating chamber is ensured, and the resistance value of the entire lower electrode is reduced.

According to a seventh aspect of the present invention, in the sixth aspect, the thick film portion of the lower electrode extends outward from at least one longitudinal end of the piezoelectric layer pattern. The feature is the ink jet recording head.

According to the seventh aspect, the electrical connection of the lower electrode can be reliably performed without affecting the driving of the piezoelectric active portion.

According to an eighth aspect of the present invention, in the sixth or seventh aspect, at least a part of the lower electrodes on both sides in the width direction of the piezoelectric active portion is substantially removed. In the recording head.

In the eighth aspect, even if the lower electrodes are not continuously provided on both sides in the width direction of the piezoelectric active portion, electrical connection can be made via the thick film portion.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the pressure generation chamber is formed in a silicon single crystal substrate by anisotropic etching, and the lower electrode, the piezoelectric layer, An ink jet recording head is characterized in that each layer of the electrode is formed by film formation and lithography.

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

According to a tenth aspect of the present invention, there is provided an ink jet recording apparatus comprising any one of the first to ninth ink jet recording heads.

According to the tenth aspect, it is possible to realize an ink jet recording apparatus in which the displacement efficiency of the piezoelectric element is improved.

According to an eleventh aspect of the present invention, a lower electrode, a piezoelectric layer, and an upper electrode are formed in a region corresponding to the pressure generating chamber on an elastic film provided on one surface of a silicon single crystal substrate forming the pressure generating chamber. In a method of manufacturing an ink jet recording head for forming a piezoelectric element composed of an electrode, the lower electrode layer is formed on the elastic film, and the lower electrode layer is patterned by half etching so that the lower electrode layer is formed in a region facing the pressure generating chamber. Forming an electrode thin film portion, forming a piezoelectric layer and an upper electrode layer on the lower electrode layer, and patterning the piezoelectric layer and the upper electrode layer to face the pressure generating chamber. And forming the piezoelectric element therein.

In the eleventh aspect, since the piezoelectric layer is formed after the lower electrode is half-etched, the change in stress of the lower electrode does not affect the characteristics of the piezoelectric layer.

According to a twelfth aspect of the present invention, the lower electrode, the piezoelectric layer, and the upper electrode are formed in a region corresponding to the pressure generating chamber on the elastic film provided on one surface of the silicon single crystal substrate forming the pressure generating chamber. In a method for manufacturing an ink jet type recording head for forming a piezoelectric element composed of an electrode, a first
Laminating the conductor layer, the piezoelectric film, and the upper electrode layer, and patterning the piezoelectric layer and the upper electrode layer to form the piezoelectric element in a region facing the pressure generating chamber. A step of laminating a second conductor layer directly or with another layer interposed on the first conductor layer and the upper electrode layer; Removing a portion of the region facing the chamber.

In the twelfth aspect, an optimum lower electrode material can be selected according to a specific region, and a high-characteristic actuator can be formed.

[0034]

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

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

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

Here, in the anisotropic etching, when the silicon single crystal substrate is immersed in an alkaline solution such as potassium hydroxide, the substrate is gradually eroded and becomes the first (1) perpendicular to the (110) plane.
An (11) plane and a second (111) plane which forms an angle of about 70 degrees with the first (111) plane and forms an angle of about 35 degrees with the (110) plane appear, and (110) This is performed by utilizing the property that the etching rate of the (111) plane is about 1/180 compared to the etching rate of the plane. By such anisotropic etching, precision processing can be performed based on the depth processing of a parallelogram formed by two first (111) planes and two oblique second (111) planes. , The pressure generating chambers 12 can be arranged at a high density.

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

On the other hand, each nozzle opening 11 communicating with one end of each pressure generating chamber 12 is formed 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 in each of the pressure generating chambers 12 described above.
Corresponding ink supply communication port 21 is drilled.
For example, at 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]
Made of ceramics. In addition, the ink supply communication port 21
Each of the pressure generating chambers 1 is, as shown in FIGS.
One slit crossing the vicinity of the end on the ink supply side of No. 2
Hole 21A or a plurality of slit holes 21B.
You may. The sealing plate 20 is provided on one side with the flow path forming substrate 10.
Cover the entire surface of the silicon single crystal substrate,
It also serves as a reinforcing plate to protect against force. 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 0.2.
0.5 μm lower electrode layer 60 and a thickness of, for example, about 1 μm
The piezoelectric layer 70 and the upper electrode layer 80 having a thickness of, for example, about 0.1 μm are laminated and formed by a process described later, thereby forming the piezoelectric element 300. Here, the piezoelectric element 300
Denotes a portion including the lower electrode layer 60, the piezoelectric layer 70, and the upper electrode layer 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 7 are used as a common electrode.
0 is patterned for each pressure generating chamber 12.
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 320. In the present embodiment, the lower electrode layer 60 is used as a common electrode of the piezoelectric element 300 and the upper electrode layer 80 is used as an individual electrode of the piezoelectric element 300. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Also,
Here, the piezoelectric element 300 and the vibration plate whose displacement is generated by driving the piezoelectric element 300 are referred to as a piezoelectric actuator. In the present embodiment, the lower electrode thin film portion 60a and the elastic film 50 described later function as a diaphragm.
The lower electrode thin film portion 60a may also serve as an elastic film.

Here, a process for forming the piezoelectric layer 70 and the like on the flow path forming substrate 10 made of a silicon single crystal substrate will be described with reference to FIG.

As shown in FIG. 4A, first, a silicon single crystal substrate wafer serving as the flow path forming substrate 10 is
The elastic film 50 made of silicon dioxide is formed by thermal oxidation in a diffusion furnace at 0 ° C., and the lower electrode layer 60 is formed on the elastic film 50 by sputtering. As a material of the lower electrode layer 60, platinum or the like is preferable. This is because a piezoelectric layer 70 described later, which is formed by sputtering or a sol-gel method, has a thickness of 600 to 1000 in an air atmosphere or an oxygen atmosphere after the film formation.
This is because it is necessary to crystallize by firing at a temperature of about ° C. That is, the material of the lower electrode layer 60 must be able to maintain conductivity under such high temperature and oxidizing atmosphere.
In particular, when lead zirconate titanate is used for the piezoelectric layer 70, 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. 4B, the lower electrode layer 60 is patterned. Here, the lower electrode is formed thin by half-edging the area facing the pressure generating chamber 12 and the surrounding area on the peripheral wall of the pressure generating chamber.

Next, as shown in FIG. 4C, a piezoelectric layer 70 and an upper electrode layer 80 are formed on the lower electrode layer 60. In this embodiment, a so-called sol-gel method is used in which a so-called sol in which a metal organic substance is dissolved and dispersed in a catalyst is applied, dried and gelled, and further fired at a high temperature to obtain a piezoelectric layer 70 made of a metal oxide. Formed. As a material of the piezoelectric layer 70, a lead zirconate titanate (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, and may be, for example, a sputtering method.

Further, after forming a precursor film of lead zirconate titanate by a sol-gel method or a sputtering method,
A method of growing crystals at a low temperature by a high-pressure treatment method in an alkaline aqueous solution may be used.

The upper electrode layer 80 may be made of any material having high conductivity, and may be made of many 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. 4D, the piezoelectric layer 70 and the upper electrode layer 80 are etched and the whole is patterned to perform the piezoelectric active portion 320, the lower electrode thin film portion 60a, and the lower electrode thick film. The part 60b is formed.

The above is the film forming process. After forming the film in this manner, as shown in FIG. 4E, the silicon single crystal substrate is subjected to anisotropic etching with the above-described alkali solution to form the pressure generating chamber 12 and the like.

FIG. 5A is a cross-sectional view of a main part of the ink jet recording head of the present embodiment thus formed.

In the ink jet recording head of this embodiment, the lower electrode thin film portion 60 corresponding to the pressure generating chamber 12 is provided.
Since the piezoelectric active part 320 composed of the piezoelectric layer 70 and the upper electrode layer 80 is provided on “a”, the piezoelectric layer 70 is not affected by a change in the stress of the lower electrode.

The lower electrode thin film portion 60a serving as one electrode of the piezoelectric active portion 320 is connected to the lower electrode thick film portion 60b on the peripheral wall of the pressure generating chamber 12 and serves as a common electrode for each piezoelectric element 300. Although not shown, it is connected to an external wiring near the end. Therefore, the resistance of the lower electrode as a whole does not increase, and sufficient power can be supplied to the piezoelectric active portion 320.

Here, as shown in FIG. 5B, the piezoelectric layer 71 and the upper electrode layer 81 formed on the lower electrode thick film portion 61 on the peripheral wall may be left without being removed by etching. Good. In this configuration, the lower electrode thick film portion 61 on the peripheral wall can be prevented from being over-etched and thinned, so that the resistance of the lower electrode thick film portion 61 can be prevented from increasing, and the piezoelectric active portion 320 can be prevented. Enough power can be supplied.

In the series of film formation and anisotropic etching described above, a number of chips are simultaneously formed on one wafer, and after the process is completed, a flow path forming substrate having one chip size as shown in FIG. Divide every ten. Further, the divided flow path forming substrate 10 is sequentially adhered and integrated with the sealing plate 20, the common ink chamber forming substrate 30, and the ink chamber side plate 40 to form an ink jet recording head.

The ink jet head thus configured takes in ink from an ink inlet 42 connected to an external ink supply means (not shown), fills the interior from the common ink chamber 31 to the nozzle opening 11 with ink, and
According to a recording signal from an external driving circuit (not shown), a voltage is applied between the lower electrode thin film portion 60a and the upper electrode layer 80,
By bending and deforming the piezoelectric body active portion 320, the pressure in the pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle opening 11.

(Embodiment 2) FIG. 6 is a diagram showing a thin film manufacturing process of an ink jet recording head according to Embodiment 2.

As shown in FIG. 6A, first, an elastic film 50, a first conductive layer 62, a piezoelectric layer 70, and an upper electrode layer 80 are formed on a silicon single crystal substrate serving as a flow path forming substrate 10. Films are formed sequentially. Here, the first conductor layer 62 is a layer made of a conductive oxide, and in this embodiment, iridium oxide is formed.

Next, as shown in FIG. 6B, the piezoelectric layer 70 and the upper electrode layer 80 are etched and patterned to form a piezoelectric active portion 320. Further, as shown in FIG.
As shown in (2), a second conductor layer 63 is formed on the piezoelectric active part 320 and the first conductor layer 62. In the present embodiment, platinum is formed as the second conductor layer 63.

Next, as shown in FIG. 6D, the second conductive layer 63 is patterned to form a first conductive layer 62 and a second conductive layer on the peripheral wall of the pressure generating chamber 12. A lower electrode having a layered structure including the layer 63 is formed.

Before forming the second conductive layer 63, a resist may be patterned in a region corresponding to the pressure generating chamber 12, and the second conductive layer 63 may be patterned by lift-off.

The above is the film forming process. After forming the film in this manner, as shown in FIG. 6E, the silicon single crystal substrate is anisotropically etched with the above-described alkali solution to form the pressure generating chamber 12 and the like.

FIG. 7 is a sectional view of a principal part of the ink jet recording head of the present embodiment thus formed.

In the ink jet type recording head of this embodiment, the lower electrode is composed of the first conductor layer 62 and the second conductor layer 63.
The lower electrode has no second conductor layer 63 in a region facing the pressure generating chamber 12 and a region around the lower electrode, and has a structure thinner than other portions. Therefore, similarly to the first embodiment, the piezoelectric layer is not affected by a change in the stress of the lower electrode.

In the present embodiment, the first conductive layer 62 in the region facing the pressure generating chamber is made of a material having relatively high rigidity and difficult to be plastically deformed. Plastic deformation of the diaphragm can be suppressed. Further, the lower electrode on the peripheral wall has a laminated structure of the second conductive layer 63 and the first conductive layer 62 having good conductivity, thereby preventing the whole resistance from increasing, and the piezoelectric active portion 320 Enough power can be supplied.

Further, by forming the elastic film 50 with a ceramic material such as zirconia or a laminated structure of a ceramic material layer and a silicon dioxide layer, a change in the diaphragm can be further suppressed, and a stable actuator can be manufactured. .

(Embodiment 3) FIGS. 8A and 8B are a front view and a sectional view of a main part of an ink jet recording head according to a third embodiment.

In this embodiment, the lower electrode thick film portion 64 is formed in a part of a region below the longitudinal end of the piezoelectric active portion 320 including the piezoelectric layer 70 and the upper electrode layer 80. This is the same as in the first embodiment. The lower electrode thick film portion 64 is patterned together at the time of forming the above-described lower electrode thick film portion 60b of the peripheral wall portion, and is connected outside the piezoelectric active portion 320 in the longitudinal direction.

As described above, in the present embodiment, the lower electrode thin film portion 60a below the piezoelectric active portion 320 is electrically connected to the lower electrode thin film portion 60a via the lower electrode thick film portion 64 at the end of the piezoelectric active portion 320. As a result, sufficient power can be supplied to the piezoelectric body active section 320. With this structure, when patterning the piezoelectric active portion 320, the lower electrode thin film portion 60 on both sides in the width direction of the piezoelectric active portion 320 is formed.
Even if a is partially etched completely by overetching, electrical connection can be secured.

The lower electrode thick film portion 64 is preferably provided at both ends in the longitudinal direction of the piezoelectric active portion 320, but may be provided only at one end.

In this embodiment, the lower electrode thick film portion 64 is used.
Although the piezoelectric layer 70 and the upper electrode layer 80 are provided up to the upper part, the present invention is not limited to this. As shown in FIG.
The piezoelectric active portion 320 may be patterned only on the lower electrode thin film portion 60a.

After the piezoelectric layer 70 and the upper electrode layer 80 are patterned so as to remain on the lower electrode thick film portion 64 as shown in FIG. The body layer removing portion 71 may be formed.

Further, in this embodiment, the lower electrode thick film portion 6
The reference numeral 4 extends from the longitudinal direction of the piezoelectric body active portion 320, but it goes without saying that it may extend from the lateral direction or may be provided at a plurality of locations.

(Other Embodiments) The embodiments of the present invention have been described above, but the basic configuration of the ink jet recording head is not limited to the above.

For example, in addition to the sealing plate 20 described above, the common ink chamber forming plate 30 may be made of glass ceramic, and the thin film 41 may be made of glass ceramic as a separate member. Changes are free.

In the above-described embodiment, the nozzle openings are formed on the end surface of the flow path forming substrate 10. However, the nozzle openings may be formed so as to be connected 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 forming plate 30, the thin plate 41A, and the ink chamber side plate 40A.

This embodiment is different from the first embodiment in that
A is basically the same as the above-described embodiment except that the ink chamber side plate 40A and the ink chamber side plate 40A are separate members, and the opening is formed in the ink chamber side plate 40A. Is omitted.

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

As described above, the present invention can be applied to ink-jet recording heads having various structures, as long as the spirit of the present invention is not contradicted.

The ink jet recording head of each of the embodiments constitutes a part of a recording head unit having an ink flow path communicating with an ink cartridge and the like, and is mounted on an ink jet recording apparatus. FIG.
FIG. 1 is a schematic view showing an example of the ink jet recording apparatus.

As shown in FIG. 12, recording head units 1A and 1B having an ink jet recording head are
Cartridges 2A and 2B constituting ink supply means are 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 and a timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted moves along the carriage shaft 5. Moved. On the other hand, the apparatus main body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is wound around the platen 8. It is designed to be transported.

[0089]

As described above, in the present embodiment, since the lower electrode thin film portion is formed in the region facing the pressure generating chamber, sufficient electric power is supplied while suppressing the resistance of the lower electrode,
In addition, there is an effect that the characteristics of the piezoelectric element can be improved.

[Brief description of the drawings]

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

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

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

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

FIGS. 5A and 5B are a main part cross-sectional view and a main part cross-sectional view illustrating a modified example of the inkjet recording head according to the first embodiment of the present invention.

FIG. 6 is a diagram illustrating a thin film manufacturing process according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a main part of an ink jet recording head according to a second embodiment of the invention.

FIG. 8 is a plan view and a cross-sectional view of a main part of an inkjet recording head according to a third embodiment of the invention.

FIG. 9 is a cross-sectional view of a principal part showing a modification of the ink jet recording head according to Embodiment 3 of the present invention.

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flow path forming substrate 12 Pressure generating chamber 50 Elastic film 60 Lower electrode layer 60a Lower electrode thin film part 60b Lower electrode thick film part 70 Piezoelectric layer 80 Upper electrode layer 300 Piezoelectric element 320 Piezoelectric active part

Claims (12)

[Claims] 1. A pressure generating chamber communicating with a nozzle opening, an elastic film constituting a part of the pressure generating chamber, a lower electrode provided on the elastic film, and a piezoelectric formed on the lower electrode. In an ink jet recording head including a body layer and an upper electrode formed on the piezoelectric layer, the lower electrode has a film thickness of at least a region facing the pressure generating chamber and a film thickness of another region. An ink jet recording head formed to be thinner. 2. A piezoelectric active part comprising the piezoelectric layer and the upper electrode is formed in a region facing the pressure generating chamber, and a lower electrode below the piezoelectric active part is formed. An ink jet recording head, wherein the thickness of the lower electrode on both sides in the width direction is the same. 3. An ink jet recording head according to claim 1, wherein a lower electrode in a region facing the peripheral wall separating the pressure generating chambers is thicker than a region facing the pressure generating chambers. 4. The lower electrode according to claim 1, wherein the lower electrode has a multilayer structure of a plurality of layers made of a plurality of materials, and a part of the plurality of layers does not exist in a region facing the pressure generating chamber. An ink jet recording head characterized by the following. 5. The material according to claim 4, wherein a material forming a layer existing in at least a region opposed to the pressure generating chamber in the multilayer structure of the lower electrode includes an oxide conductor layer. Characteristic inkjet recording head. 6. The lower electrode according to claim 2, wherein the lower electrode has a thick film portion formed in a part of a region below the piezoelectric layer so as to be thicker than another part. An ink jet recording head, wherein a film portion extends to a region where the piezoelectric layer has been removed. 7. The ink jet recording head according to claim 6, wherein the thick film portion of the lower electrode extends from at least one longitudinal end of the piezoelectric layer pattern to the outside thereof. 8. The ink jet recording head according to claim 6, wherein at least a part of lower electrodes on both sides in the width direction of the piezoelectric active portion is substantially removed. 9. 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 of the lower electrode, the piezoelectric layer, and the upper electrode is formed by film formation and lithography. An ink jet recording head formed by a method. 10. An ink jet recording apparatus comprising the ink jet recording head according to claim 1. 11. A piezoelectric element including a lower electrode, a piezoelectric layer, and an upper electrode is formed in a region corresponding to the pressure generating chamber on an elastic film provided on one surface of a silicon single crystal substrate forming a pressure generating chamber. Forming the lower electrode layer on the elastic film and patterning the lower electrode layer by half-etching to form a lower electrode thin film portion in a region facing the pressure generating chamber. Forming a piezoelectric layer and an upper electrode layer on the lower electrode layer; and patterning the piezoelectric layer and the upper electrode layer to form the piezoelectric element in a region facing the pressure generating chamber. And a method of manufacturing an ink jet type recording head. 12. A piezoelectric element comprising a lower electrode, a piezoelectric layer, and an upper electrode is formed in a region corresponding to the pressure generating chamber on an elastic film provided on one surface of a silicon single crystal substrate forming a pressure generating chamber. Forming a first conductive layer, a piezoelectric film, and the upper electrode layer on the elastic film, and patterning the piezoelectric layer and the upper electrode layer. Forming the piezoelectric element in a region facing the pressure generating chamber by using the first
Laminating a second conductor layer directly or with another layer interposed on the conductor layer and the upper electrode layer, and at least a portion of the second conductor layer facing the pressure generating chamber And a step of removing ink.