JP2000043258A - Ink-jet type recording head and ink-jet type recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet type recording head and an ink-jet type recording apparatus which eliminate operation failures of a piezoelectric element caused by a change in the external environment such as a humidity or the like. SOLUTION: In the ink-jet type recording head which includes nozzle openings 17 through which ink is discharged, a passage formation substrate 10 where pressure generation chambers 12 communicating with the nozzle openings 17 are formed, and a piezoelectric actuator set at one face of the passage formation substrate 10 for generating a pressure change to the pressure generation chambers 12, a protecting member 20 is jointed to the side of the piezoelectric actuator of the passage formation substrate 10 for covering the piezoelectric actuator of at least an area opposite to the pressure generation chambers 12. The protecting member 20 consists of a liquid-holding member in which an insulating liquid 25 is impregnated and held, so that the piezoelectric actuator is shielded from the outside air and prevented from malfunctioning due to an external environment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element in which a part of a pressure generating chamber communicating with a nozzle opening for discharging ink droplets is constituted by a diaphragm, and a piezoelectric element is formed on the surface of the diaphragm. The present invention relates to an ink jet recording head and an ink jet recording apparatus for ejecting ink droplets by displacement of the ink jet recording head.

[0002]

2. Description of the Related Art A part of a pressure generating chamber communicating with a nozzle opening for discharging ink droplets is constituted by a vibrating plate, and the vibrating plate is deformed by a piezoelectric element to pressurize the ink in the pressure generating chamber to pass through the nozzle opening. Two types of ink jet recording heads that eject ink droplets have been commercialized, one using a longitudinal vibration mode piezoelectric actuator that expands and contracts in the axial direction of the piezoelectric element, 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. In this case, the piezoelectric actuator corresponding to each pressure generating chamber can be driven by providing at least only the upper electrode for each pressure generating chamber while the piezoelectric material layer is provided on the entire surface of the vibration plate.

[0007]

In the above-described manufacturing method using the thin film technology and the lithography method, when the piezoelectric element is formed by sputtering a piezoelectric material, compared with the structure formed by firing a green sheet, When driven at the same voltage, a high electric field is applied due to the thinness of the piezoelectric element, and when absorbing moisture in the air, the leakage current between the drive electrodes is likely to increase, eventually leading to dielectric breakdown. . To solve such a problem,
A proposal has been made in which a piezoelectric element is covered with an environmental protection film made of an oxide film, a nitride film, an organic film, or the like, and is isolated from an external environment.

However, there is a problem that it is difficult to use an oxide film and a nitride film as environmental protection films because of their high rigidity. In the case of an organic film, the piezoelectric element can be protected relatively easily, but one that can be used more easily and has improved reliability is desired.

In view of such circumstances, the present invention provides an ink jet recording head and an ink jet recording apparatus which eliminate malfunctions caused by changes in the external environment such as humidity of a piezoelectric element formed by a film forming technique. The task is to

[0010]

According to a first aspect of the present invention, there is provided a flow path forming substrate having a nozzle opening for discharging ink, a pressure generating chamber communicating with the nozzle opening, and A piezoelectric actuator provided on one surface of the flow path forming substrate and configured to generate a pressure change in the pressure generating chamber, wherein the ink jet recording head is joined to the piezoelectric actuator side of the flow path forming substrate, at least A protection member that covers the piezoelectric actuator in a region facing the pressure generating chamber, the protection member includes:
An ink jet recording head, comprising a liquid holding member for impregnating and holding an insulating liquid.

In the first aspect, the piezoelectric actuator is shielded from the external environment by the protection member, the adsorption of moisture to the piezoelectric layer of the piezoelectric actuator is prevented, and the insulating liquid is easily impregnated and held.

According to a second aspect of the present invention, in the first aspect, a space is provided between the protection member and the piezoelectric actuator to such an extent that the driving of the piezoelectric actuator is not hindered. And an ink jet recording head.

In the second aspect, the protection member and the piezoelectric actuator are not in contact with each other, and do not hinder ink ejection.

According to a third aspect of the present invention, there is provided an ink jet recording head according to the second aspect, wherein the insulating liquid is sealed in the space.

In the third aspect, the insulating liquid prevents moisture from adsorbing to the piezoelectric layer of the piezoelectric actuator, and the space can be filled with the liquid through the liquid holding member.

A fourth aspect of the present invention is the ink jet recording head according to the first aspect, wherein the protection member is elastically deformable and is in close contact with the piezoelectric actuator.

In the fourth aspect, the protection member reliably prevents moisture from adsorbing to the piezoelectric layer of the piezoelectric actuator, and since the protection member is elastically deformable, does not hinder ink ejection. .

According to a fifth aspect of the present invention, there is provided the ink jet method according to any one of the first to fourth aspects, wherein the insulating liquid is selected from the group consisting of a silicone oil and a fluorine-based inert liquid. In the recording head.

In the fifth aspect, the piezoelectric actuator is isolated from the outside by the silicone oil or the fluorine-based inert liquid.

A sixth aspect of the present invention is the ink jet recording head according to any one of the first to fifth aspects, wherein the liquid holding member is a foamable resin having open cells.

In the sixth aspect, the protective member is formed by impregnating the foaming resin with the insulating liquid.

According to a seventh aspect of the present invention, there is provided an ink jet recording head according to any one of the first to fifth aspects, wherein the liquid holding member is a liquid absorbing material made of fiber or pulp. is there.

In the seventh aspect, the protective member is formed by impregnating the insulating liquid into the liquid absorbing material made of fiber or pulp.

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

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

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, a reservoir communicating with the pressure generating chamber is defined in the flow path forming substrate, and the nozzle having the nozzle opening is provided. An ink jet recording head is characterized in that the plates are joined.

According to the ninth aspect, an ink jet recording head that discharges ink from the nozzle openings can be easily realized.

According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the flow path forming substrate includes a common ink chamber for supplying ink to the pressure generating chamber; A flow path unit for forming a flow path communicating with the nozzle opening is joined to the ink jet recording head.

In the tenth aspect, ink is ejected from the nozzle opening via the flow path unit.

An eleventh 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 tenth aspects.

According to the eleventh aspect, it is possible to realize an ink jet recording apparatus with improved head reliability.

[0032]

FIG. 1 is an assembled perspective view showing an ink jet recording head according to an embodiment of the present invention, and FIGS. 2 (a) and 2 (b) are longitudinal views of one of the pressure generating chambers. It is a figure which shows each cross-section in the direction and the direction which intersects it.

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,
Row 1 of pressure generating chambers 12 partitioned by a plurality of partition walls 11
3 are arranged in a substantially U-shape so as to surround three rows of the two rows of pressure generating chambers 12, and each of the pressure generating chambers 1.
An ink supply port 15 for communicating the reservoir 2 with the reservoir 14 at a constant fluid resistance is formed. In addition, an ink introduction hole 16 for supplying ink to the reservoir 14 from outside is formed at a substantially central portion of the reservoir 14.

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 are formed. 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. Here, the elastic film 50 is
The amount attacked by the alkaline solution for etching the silicon single crystal substrate is extremely small. Further, each ink supply port 15 communicating with one end of each pressure generating chamber 12 is connected to one of the pressure generating chambers 12.
It is formed shallower. That is, the ink supply port 15
Is formed by etching (half-etching) the silicon single crystal substrate halfway in the thickness direction. Note that the half etching is performed by adjusting the etching time.

Further, on the opening side of the flow path forming substrate 10,
A nozzle plate 18 in which a nozzle opening 17 communicating with the ink supply port 15 of each pressure generating chamber 12 on the opposite side is formed is fixed via an adhesive or a heat welding film. The thickness of the nozzle plate 18 is, for example, 0.1 to 1
mm, the coefficient of linear expansion is 300 ° C. or less, for example, 2.5 to
It is made of 4.5 [× 10 ⁻⁶ / ° C.] glass-ceramic or non-rusting steel. The nozzle plate 18 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 17 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 17 need to be formed with a diameter of several tens of μm with high accuracy.

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
The piezoelectric film 300 and the upper electrode film 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 film 60, the piezoelectric film 70, and the upper electrode film 80. Generally, one of the electrodes of the piezoelectric element 300 is used as a common electrode, and the other electrode and the piezoelectric film 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 film 70 and in which a piezoelectric strain is generated by applying a voltage to both electrodes is referred to as a piezoelectric active portion 320. In the present embodiment, the lower electrode film 60 is used as a common electrode of the piezoelectric element 300, and the upper electrode film 80 is used as an individual electrode of the piezoelectric element 300. However, there is no problem even if the upper electrode film 80 is reversed for convenience of a drive circuit and wiring. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Also,
Here, the piezoelectric element 300 and a vibration plate whose displacement is generated 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.

Here, a process of 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.

As shown in FIG. 3A, 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. 3B, a lower electrode film 60 is formed by sputtering. Pt or the like is preferable as the material of the lower electrode film 60. This is because a piezoelectric film 70 to be described later, which is formed by sputtering or a sol-gel method, has a thickness of 600 to 100
This is because it is necessary to perform crystallization by firing at a temperature of about 0 ° C. That is, the material of the lower electrode film 60 must be able to maintain conductivity at such a high temperature and in an oxidizing atmosphere. In particular, when PZT is used for the piezoelectric film 70, the conductivity of the material by diffusion of PbO is increased. It is desirable that there is little change in sex, and Pt is preferred for these reasons.

Next, as shown in FIG. 3C, 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 solvent 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. The 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 aqueous alkali solution may be used.

Next, as shown in FIG. 3D, 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 Al, Au, Ni, and Pt, and a conductive oxide can be used. In the present embodiment, P
t is formed by sputtering.

Next, as shown in FIG. 3E, a piezoelectric element is provided for each of the pressure generation chambers 12.
The upper electrode film 80 and the piezoelectric film 70 are patterned.
FIG. 3E shows a case where the piezoelectric film 70 is patterned with the same pattern as the upper electrode film 80. However, as described above, the piezoelectric film 70 does not necessarily need to be patterned. This is because, when a voltage is applied using the pattern of the upper electrode film 80 as an individual electrode, an electric field is applied only between each upper electrode film 80 and the lower electrode film 60 which is a common electrode. This has no effect. However, in this case, it is necessary to apply a large voltage to obtain the same excluded volume. Therefore, it is preferable to pattern the piezoelectric film 70 as well. Thereafter, the lower electrode film 60 is patterned to remove unnecessary portions.

Here, the patterning is performed by forming a resist pattern and then performing etching or the like.

The resist pattern is formed, for example, by applying a negative resist by spin coating or the like, and performing exposure, development, and baking using a mask having a predetermined shape. Of course, a positive resist may be used instead of the negative resist.

The etching is performed using a dry etching apparatus, for example, an ion milling apparatus until the silicon dioxide film is exposed. After the etching, the resist pattern is removed using an ashing device or the like.

As a dry etching method, a reactive etching method or the like may be used in addition to the ion milling method. It is also possible to use wet etching instead of dry etching, but the patterning accuracy is somewhat inferior to the dry etching method, and the upper electrode film 8
Since the material of 0 is also limited, it is preferable to use dry etching.

Next, as shown in FIG. 4A, an insulator layer 90 is formed so as to cover the periphery of the upper electrode film 80 and the side surfaces of the piezoelectric film 70. In this embodiment, a negative photosensitive polyimide is used as a material of the insulator layer 90.

Next, as shown in FIG. 4B, by patterning the insulator layer 90, a contact hole 90a is formed in a portion facing each communication portion 14. This contact hole 90a is provided with a lead electrode 100 described later.
And the upper electrode film 80.

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

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

In the above-described series of film formation and anisotropic etching, a large number of chips are simultaneously formed on one wafer, and after completion of the process, a flow path of one chip size as shown in FIG. It is divided for each forming substrate 10. Also,
The nozzle plate 18 is adhered to the divided flow path forming substrate 10 to form an ink jet recording head.

Further, in the ink jet recording head of this embodiment thus configured, the protection member 20 impregnated with the insulating liquid 25 is provided on the flow path forming substrate 10 on the piezoelectric element 300 side. .

The protection member 20 has a concave portion 20a on one side which is a space that does not come into contact with the piezoelectric element 300, and a concave portion 20a is formed in a region facing each row 13 of the pressure generating chambers 12. A partition wall 20b for partitioning is provided. Further, the periphery of the flow path forming substrate 10 defining the concave portion 20a and the partition wall 20b form a contact portion 20c which comes into contact with the flow path forming substrate 10, and the contact portion 20c is provided on the lower electrode film 60. , For example, with an adhesive or the like. At this time, in the present embodiment, the upper electrode film 80 of each piezoelectric element 300 is used.
Since the lead electrode 100 connected to the substrate is patterned in the longitudinal direction up to near the end of the flow path forming substrate 10,
The protection member 20 is fixed with the lead electrode 100 held therebetween.

In this embodiment, the protection member 20 is fixed on the lower electrode film 60, but is not limited to this. For example, the protection member 20 is fixed directly on the flow path forming substrate 10 or on the elastic film 50. May be. In any case, the protection member 20 can be securely fixed.

Thus, the piezoelectric element 300 is held in the recess 20a of the protection member 20 in a state where the driving thereof is not hindered. In the present embodiment, the protection member 2
In the space in the concave portion 20a between 0 and the piezoelectric element 300,
The insulating liquid 25 is sealed so that the piezoelectric element 300 does not come into contact with the outside air.

Here, the protective member 20 is made of an insulating liquid 25.
And a liquid holding member for impregnating and holding. Here, the liquid holding member is a material having a property of absorbing and holding a liquid and having at least a strength capable of holding the liquid in a certain shape. For example, a number of small holes communicating with each other in the material Or has a gas permeability by the gap, refers to a material that absorbs and retains liquid in the small holes or gaps, various porous materials, or foamed resin materials, or a material obtained by hardening various fibers or pulp, and the like. For example, in the present embodiment, a foamed resin material, a so-called “foam” is used. In addition, the liquid holding member has air permeability itself, but has airtightness by impregnating and holding the insulating liquid 25, thereby enabling isolation from an external atmosphere. Therefore, the insulating liquid 25 only needs to be sufficiently impregnated into the liquid holding member, and does not necessarily need to be filled into the internal space.

Moreover, the pressure change inside the protection member 20 due to the driving of the piezoelectric active part 320 is absorbed by the insulating liquid 25 impregnated and held in the liquid holding member.
The insulating liquid 25 is preferably a silicone oil or a fluorine-based inert liquid. For example, in the present embodiment, the silicone oil is used.

The method of forming the protective member 20, that is, the method of impregnating the liquid holding member with the insulating liquid 25 and filling the inside thereof is not particularly limited, and the liquid holding member has a property of absorbing and holding the liquid. Since the material is a material, for example, after the liquid holding member is fixed to the flow path forming substrate 10, the insulating liquid 25 can be easily impregnated from the outer surface of the liquid holding member. Further, by further impregnating, the inner space can be easily filled with the insulating liquid 25.

With such a configuration, the piezoelectric element 300
Is completely shut off from the external environment by the protection member 20,
Adsorption of moisture on the piezoelectric film 70 of the piezoelectric element 300 can be prevented. Further, it is possible to prevent a change in the temperature of the piezoelectric film 70 due to a change in the external environment. Therefore,
Since a high insulation resistance can be maintained without increasing a leak current between the lower electrode film 60 and the upper electrode film 80, the pressure generating chamber 12 is expanded and contracted with a fixed displacement amount to achieve good printing. Quality can be maintained.

Further, in the present embodiment, since the protection member 20 is formed of a liquid holding member impregnated with an insulating liquid, when the piezoelectric active portion 320 is driven, the impregnated insulating liquid 25 is impregnated.
Accordingly, the pressure change is absorbed in the protection member 20 and does not hinder the driving of the piezoelectric active portion 320.

In this embodiment, the protection member 20 is fixed by the partition wall 20b in the center line region where the periphery of the flow path forming substrate 10 and the row 13 of the pressure generating chambers 12 face each other. However, for example, as shown in FIG. 5, a partition wall 20 b is further provided in a region of each of the pressure generating chambers 12 of the protective member 20 facing the partition 11, and each of the partition walls 20 b is provided in a space defined for each of the piezoelectric elements 300. The insulating liquid 25 may be filled. Thereby, the influence of the change of the other piezoelectric element 300 is suppressed, and the piezoelectric active unit 320 is more reliably
Good driving can be maintained. Also in this case, since the protection member 20 is formed of a liquid holding member impregnated with the insulating liquid 25, each space defined for each piezoelectric element 300 is easily filled with the insulating liquid 25. be able to. Further, the pressure change in each space of the protection member 20 is absorbed by the insulating liquid 25.

(Embodiment 2) FIG. 6 is a sectional view of a main part of an ink jet recording head according to Embodiment 2. This embodiment is the same as the first embodiment except that no space is provided between the protection member 20 and the piezoelectric element 300 as shown in FIG. 6, and the protection member 20 is provided so as to be in close contact with the piezoelectric element 300. is there. In the present embodiment, a material that can be elastically deformed, for example, a sponge-like foamed resin material, is used as the liquid holding material constituting the protection member 20 so as not to hinder the driving of the piezoelectric active portion 320.

With such a configuration, similarly to the first embodiment, the driving of the piezoelectric active portion 320 is not hindered.
Good print quality can be maintained. In the present embodiment, since the protection member 20 is in close contact with the piezoelectric film 70 of the piezoelectric element 300, the piezoelectric film 7
It is possible to prevent moisture from adsorbing to zero, and does not hinder the driving of the piezoelectric active part 320.

(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 the above embodiment, the upper electrode film 8
0 is a contact hole 90 provided in the insulator layer 90
a, the lead electrode 100 is connected to the lead electrode 100.
00 is extended to the outside of the protection member 20 and connected to an external wiring, but is not limited to this. For example, as shown in FIG.
It may be extended to the outside of 0 and connected to an external wiring. In this case, the lower electrode film 60 may be extended to the outside, but the lower electrode film 60 is only provided in a region facing the pressure generating chamber 12 in order to eliminate unnecessary driving. For example, as shown in FIG. 8, the lower electrode film 60 extends to the outside, and an insulator having an insulating property is formed on the lower electrode film 60 in a region corresponding to the vicinity of the longitudinal end of the pressure generating chamber 12. In addition to forming the layer 90A, the piezoelectric film 70 is provided only in a region facing the pressure generating chamber 12, and the insulating layer 90A
Alternatively, only the upper electrode film 80 may be extended to the outside of the protection member 20. In this case, it is preferable to provide the piezoelectric layer 70 under the end of the piezoelectric layer 70 to prevent insulation failure.

Further, for example, in the above-described embodiment, the reservoir 14 is formed together with the pressure generating chamber 12 in the flow path forming substrate 10, but a member forming the common ink chamber is provided so as to overlap the flow path forming substrate 10. You may.

FIG. 9 shows a partial cross section of the ink jet recording head thus constructed. In this embodiment, the sealing plate 160, the common ink chamber forming plate 170, the thin plate 180, and the ink chamber side plate 19 are provided between the nozzle plate 120A having the nozzle openings 11A formed therein and the flow path forming substrate 10A.
0 so that the pressure generating chamber 1
Nozzle communication port 31 that communicates between 2A and nozzle opening 11A
Is arranged. That is, the common ink chamber 3 is formed by the sealing plate 160, the common ink chamber forming plate 170, and the thin plate 180.
2 are defined, and each pressure generating chamber 12A and the common ink chamber 32
Are communicated through the ink communication holes 33 formed in the sealing plate 160. The sealing plate 160 is also provided with an ink introduction hole 34 for introducing ink into the supply ink chamber 32 from outside. Also, the ink chamber side plate 190 located between the thin plate 180 and the nozzle plate 120A.
Has a penetrating portion 35 formed at a position facing each of the supply ink chambers 32, and allows the thin wall 180 to absorb the pressure generated at the time of discharging the ink droplet toward the side opposite to the nozzle opening 11A. As a result, it is possible to prevent unnecessary positive or negative pressure from being applied to the other pressure generating chambers via the common ink chamber 32. In addition,
The thin plate 180 and the ink chamber side plate 190 may be formed integrally.

Also in such an embodiment, the above-described protective member is fixed to the surface of the flow path forming substrate 10A opposite to the opening surface, so that the piezoelectric active portion can be easily shut off from the outside. Thus, adsorption of moisture to the piezoelectric film can be prevented.

In each of the embodiments described above, a thin film type ink jet recording head which can be manufactured by applying a film forming and lithography process is described as an example.
Of course, the present invention is not limited to this. For example, an inkjet type having various structures, such as a type in which a pressure generating chamber is formed by laminating substrates, or a type in which a green sheet is attached or a piezoelectric film is formed by screen printing or the like. The present invention can be applied to a recording head.

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 these 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. 10, recording head units 1A and 1B having an ink jet recording head are
Cartridges 2A and 2B constituting ink supply means are detachably provided. A carriage 3 on which the recording head units 1A and 1B are mounted is provided on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. I have. The recording head units 1A and 1B are, for example,
Each of them ejects a black ink composition and a color ink composition.

The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted moves along the carriage shaft 5. Moved. On the other hand, the apparatus main body 4 is provided with a platen 8 along the carriage 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.

[0079]

As described above, according to the present invention, at least the piezoelectric active portion of the piezoelectric element is covered with the protective member impregnated with the insulating liquid. Adsorption of moisture to the layer can be prevented, and the piezoelectric characteristics of the piezoelectric layer can be improved. Further, since the protection member is elastically deformable, the driving of the piezoelectric active portion is not hindered. Therefore, the piezoelectric active portion can be driven favorably, good print quality can be maintained, and reliability can be improved. Furthermore, since the insulating liquid can be impregnated into the protective member and filled into the protective member from the outer surface of the protective member, the protective member can be easily manufactured.

[Brief description of the drawings]

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

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

FIG. 3 is a cross-sectional view illustrating a thin-film manufacturing process according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a thin-film manufacturing process according to the first embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a modification of the ink jet recording head according to the first embodiment of the present invention.

FIG. 6 is a sectional view of a main part of an ink jet recording head according to a second embodiment of the present invention.

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

FIG. 8 is a cross-sectional view of a main part of an ink jet recording head according to another embodiment of the present invention.

FIG. 9 is a cross-sectional view of a main part of an ink jet recording head according to another embodiment of the present invention.

FIG. 10 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 11 partition 12 pressure generating chamber 17 nozzle opening 20 protective member 25 insulating liquid 50 elastic film 60 lower electrode film 70 piezoelectric film 80 upper electrode film 90, 90A insulator layer 100 lead electrode 300 piezoelectric element 320 piezoelectric Active part

Claims (11)

[Claims] 1. A flow path forming substrate formed with a nozzle opening for discharging ink, a pressure generating chamber communicating with the nozzle opening, and a pressure generating chamber provided on one surface of the flow path forming substrate. An ink jet recording head comprising: a piezoelectric actuator that generates a pressure change; and a protection member that is joined to the piezoelectric actuator side of the flow path forming substrate and covers at least the piezoelectric actuator in a region facing the pressure generation chamber. The protection member is formed of a liquid holding member that impregnates and holds an insulating liquid. 2. The ink jet recording head according to claim 1, wherein a space is provided between the protection member and the piezoelectric actuator to such an extent that the driving of the piezoelectric actuator is not hindered. 3. The ink jet recording head according to claim 2, wherein the insulating liquid is sealed in the space. 4. The ink jet recording head according to claim 1, wherein the protection member is elastically deformable and is in close contact with the piezoelectric actuator. 5. The ink jet recording head according to claim 1, wherein the insulating liquid is selected from the group consisting of silicone oil and a fluorine-based inert liquid. 6. The ink jet recording head according to claim 1, wherein the liquid holding member is a foamable resin having open cells. 7. The ink jet recording head according to claim 1, wherein the liquid holding member is a liquid absorbing material made of fiber or pulp. 8. 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 actuator is formed by film formation and lithography. An ink jet recording head, comprising: 9. The flow path forming substrate according to claim 1, wherein a reservoir communicating with the pressure generating chamber is defined in the flow path forming substrate, and a nozzle plate having the nozzle opening is joined thereto. Inkjet recording head. 10. The flow path forming substrate according to claim 1, wherein a common ink chamber for supplying ink to the pressure generation chamber, and a flow path communicating the pressure generation chamber with the nozzle opening. An ink jet recording head, wherein a flow path unit forming a path is joined to the ink jet recording head. 11. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.