JP2000211134A - Ink-jet recording head and ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet recording head and an ink-jet recording apparatus wherein a piezoelectric element layer and an upper electrode are extended to a peripheral wall and the destruction of the piezoelectric element layer at the boundary part with the peripheral wall is prevented. SOLUTION: In an ink jet recording head consisting of a pressure generating chamber 12 communicating with a nozzle orifice, the lower electrode 60 provided to the region corresponding to the pressure generating chamber 12, the piezoelectric element layer 70 provided on the lower electrode 60 and the upper electrode 80 provided on the surface of the piezoelectric element layer 70 and having the piezoelectric element having a piezoelectric element activating part 320 becoming a substantial drive part provided to the region opposed to the pressure generating chamber, the piezoelectric element layer 70 constituting the piezoelectric element activating part 320 and the upper electrode 80 are extended from the region opposed to the pressure generating chamber 12 to the outside of this region and a discontinuous electrode 61 discontinuous to the lower electrode 60 is provided under the piezoelectric element layer of the region opposed to the boundary part of the end part of the pressure generating chamber 12 and a peripheral wall to suppress displacement at this part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure generating chamber which communicates with a nozzle opening for discharging ink droplets, which is constituted by a vibrating plate. TECHNICAL FIELD The present invention relates to an ink jet recording head and an ink jet recording apparatus for ejecting ink droplets by means of a printer.

[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.

Further, in this case, the piezoelectric element 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. However, due to the problem of the amount of displacement per unit drive voltage and the stress applied to the piezoelectric layer at the part facing the pressure generating chamber and the part straddling the outside, the piezoelectric active part consisting of the piezoelectric layer and the upper electrode is pressurized. It is desirable to form so as not to go out of the generation chamber.

Therefore, a structure has been proposed in which, for example, a piezoelectric layer and an upper electrode extend from the piezoelectric active portion corresponding to each pressure generating chamber to the outside of the pressure generating chamber.

[0009]

However, in the above-described structure, the rigidity of the diaphragm is reduced on the side from which the piezoelectric layer and the upper electrode are drawn out, and the stress at the end of the piezoelectric active portion of the pressure generating chamber becomes large. There is a problem that the piezoelectric layer is broken.

In the case where the piezoelectric layer is formed by the sol-gel method, the thickness of the piezoelectric layer is reduced around the lower electrode removing portion,
There is a problem that the piezoelectric active portion causes dielectric breakdown at the end of the pattern of the lower electrode.

In view of such circumstances, the present invention provides an ink jet recording head and an ink jet recording head in which a piezoelectric layer and an upper electrode are extended to a peripheral wall and breakage of the piezoelectric layer at a boundary with the peripheral wall is prevented. It is an object to provide a recording device.

[0012]

According to a first aspect of the present invention, there is provided a pressure generating chamber communicating with a nozzle opening, a lower electrode provided in a region corresponding to the pressure generating chamber, and a lower electrode provided in a region corresponding to the pressure generating chamber. A piezoelectric element comprising a piezoelectric layer provided on the electrode and an upper electrode provided on the surface of the piezoelectric layer, the piezoelectric element having a piezoelectric active part serving as a substantial driving part in a region facing the pressure generating chamber; In the ink jet recording head, the piezoelectric layer and the upper electrode constituting the piezoelectric active portion extend from an area facing the pressure generation chamber to outside the area, and an end of the pressure generation chamber. On the lower side of the piezoelectric layer in a region opposed to the portion, the peripheral wall and the boundary portion,
In the ink jet recording head, a discontinuous lower electrode that is discontinuous to the lower electrode is provided.

In the first aspect, the rigidity of the diaphragm at the portion where the piezoelectric layer and the upper electrode are drawn out to the region outside the pressure generating chamber is maintained high, and the diaphragm and the piezoelectric layer at this portion are prevented from being broken. Is done.

According to a second aspect of the present invention, in the first aspect, the discontinuous lower electrode is provided near a longitudinal end of the pressure generating chamber of the lower electrode, and is provided at least in parallel with the pressure generating chamber. An ink jet recording head is characterized by being discontinuous with the lower electrode by a lower electrode removing portion extending in the setting direction.

In the second aspect, the distance between the discontinuous lower electrode and the lower electrode can be reduced, and the rigidity of the diaphragm is kept higher.

According to a third aspect of the present invention, there is provided an ink jet recording head according to the first or second aspect, wherein the discontinuous lower electrode is not electrically connected to any of them.

According to the third aspect, the discontinuous lower electrode and the lower electrode are reliably insulated.

According to a fourth aspect of the present invention, in the first or second aspect, the discontinuous lower electrode is connected to a resistor so that a time constant to be charged is larger than a driving pulse. And an ink jet recording head.

In the fourth aspect, the discontinuous lower electrode is reliably insulated from the lower electrode, and the discontinuous lower electrode is prevented from having an excessive potential.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the discontinuous lower electrode is connected to the discontinuous lower electrode on the side of the peripheral wall opposite to the lower electrode. A lower electrode for wiring which is continuous and one end of which is connected to an external wiring is provided for each of the piezoelectric elements, and the piezoelectric layer and the upper electrode extend to the lower electrode for wiring, and the upper electrode Is connected to the lower electrode for wiring in the ink jet recording head.

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

According to a sixth aspect of the present invention, in the first or second aspect, the discontinuous lower electrode is separated for each of the piezoelectric active portions in a longitudinal direction of the pressure generating chamber. An ink jet recording head is connected to the upper electrode of each piezoelectric active portion.

According to the sixth aspect, the rigidity of the diaphragm at the portion where the piezoelectric layer and the upper electrode are drawn out to the area outside the pressure generating chamber is kept high, and the wiring can be efficiently drawn out.

According to a seventh aspect of the present invention, there is provided an ink jet recording head according to the sixth aspect, wherein each of the discontinuous lower electrodes and the lower electrode have an interval capable of being insulated. .

In the seventh aspect, each of the piezoelectric active portions is reliably driven, and the ejection characteristics are maintained satisfactorily.

An eighth aspect of the present invention is the ink jet recording head according to the sixth or seventh aspect, further comprising an intermediate electrode connected between the adjacent discontinuous lower electrodes. It is in.

In the eighth aspect, the removal of the lower electrode film can be minimized, and the rigidity of the diaphragm can be maintained more reliably.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the piezoelectric layer remains in at least a part of the lower electrode film removed portion other than a region corresponding to the piezoelectric element. An ink jet recording head is characterized in that:

In the ninth aspect, the discontinuous portion and the lower electrode are reliably insulated, and the reliability can be improved.

According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the pressure generating chamber is formed on a silicon single crystal substrate by anisotropic etching, and each layer of the piezoelectric element is formed of a thin film and lithography. An ink jet recording head characterized by being formed by a method.

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

According to an eleventh aspect of the present invention, there is provided an ink jet recording apparatus comprising the ink jet recording head according to any one of the first to tenth aspects.

According to the eleventh aspect, it is possible to realize an ink jet recording apparatus in which the characteristics of the head are improved and the reliability is improved.

[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, and FIG. 2 is a plan view thereof and a cross section in the longitudinal direction of one pressure generating chamber. FIG.

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 an elastic film 50 having a thickness of 1 to 2 μm and made of silicon dioxide formed in advance 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 with an ink supply communication port 21 corresponding to each of the pressure generating chambers 12 described above, and has a thickness of, for example, 0.1 to 1 mm and a linear expansion coefficient of 300 ° C. or less. , For example, 2.5-4.5 [× 10 ⁻⁶ / ° C.]. In addition, the ink supply communication port 21
Each of the pressure generating chambers 1 is, as shown in FIGS.
It may be one slit hole 21A crossing the vicinity of the second ink supply side end or a plurality of slit holes 21B. The sealing plate 20 entirely covers one surface of the flow path forming substrate 10 on one surface, and also serves as a reinforcing plate for protecting the silicon single crystal substrate from impact and external force. In addition, the sealing plate 20
The other surface constitutes one wall surface of the common ink chamber 31.

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

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

On the other hand, on the elastic film 50 on the side opposite to the opening surface of the flow path forming substrate 10, a thickness of, for example, about 0.5 μm
A lower electrode film 60, a piezoelectric film 70 having a thickness of, for example, about 1 μm, and an upper electrode film 80 having a thickness of, for example, about 0.1 μm are formed by lamination in a process to be described later.
0. Here, the piezoelectric element 300 refers to 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 70 are 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. In any case, the piezoelectric active portion is formed for each pressure generating chamber. Also, here
The combination of the piezoelectric element 300 and the vibration plate whose displacement is generated by driving the piezoelectric element 300 is referred to as a piezoelectric actuator.

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 and 6 are cross-sectional views in the width direction of the pressure generating chamber 12, and FIG.
Is a longitudinal sectional view of the pressure generating chamber 12. FIG.

First, as shown in FIG. 4A, a silicon single crystal substrate wafer to be
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,
After film formation, 600 to 10 in an air atmosphere or an oxygen atmosphere
This is because it is necessary to perform crystallization by firing at a temperature of about 00 ° 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. 5, which is a longitudinal sectional view of the pressure generating chamber 12, the lower electrode film 60 is patterned into a predetermined shape. That is, the lower electrode film removing portion 330 having a predetermined width is provided in a region of the lower electrode film 60 opposed to the vicinity of one end of the pressure generating chamber 12, for example, in the direction in which the pressure generating chambers 12 are juxtaposed and along the side wall. The pressure generating chamber 12
A discontinuous lower electrode film 61 that is discontinuous from the lower electrode film 60 is formed at the boundary between the end of the lower electrode film and the peripheral wall. At the same time, the lower electrode film 60 in a region facing the peripheral wall is patterned to form an independent wiring lower electrode film 62 corresponding to each pressure generating chamber 12.

Next, as shown in FIG. 4C, 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 of the piezoelectric film 70, a lead zirconate titanate-based material is suitable when used in an ink jet recording head. The method for forming the piezoelectric film 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.

Next, as shown in FIG. 4D, an upper electrode film 80 is formed. The upper electrode film 80 only needs to be a material having high conductivity, and can use many metals such as aluminum, gold, nickel, and platinum, and a conductive oxide. In the present embodiment, platinum is formed by sputtering.

Thereafter, as shown in FIG. 6A, only the piezoelectric film 70 and the upper electrode film 80 are etched to pattern the piezoelectric active portion 320. The above is the film forming process. After forming the film in this manner, as shown in FIG. 6B, 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. 7 shows a plan view and a cross section of a main part of the ink jet recording head thus formed.

As shown in FIG. 7, the piezoelectric active portion 320 is basically provided in a region facing the pressure generating chamber 12, and the piezoelectric film 70 and the upper electrode film 80 extend in the longitudinal direction of the pressure generating chamber 12. It extends continuously from one end to a region facing the peripheral wall. The lower electrode film 60 is provided over a region corresponding to the plurality of pressure generating chambers 12 arranged in parallel.

In the vicinity of the end of the pressure generating chamber 12 on the side where the piezoelectric film 70 and the upper electrode film 80 are extended, a lower electrode film removing portion 330 from which the lower electrode film 60 has been removed is provided, for example. The lower electrode film is provided in the shape of the pressure generating chamber 12 in a narrow groove extending in the direction in which the pressure generating chamber 12 is arranged. The film 60 is a discontinuous lower electrode film 61 that is discontinuous.

Here, the lower electrode film 60 and the discontinuous lower electrode film 6
It is necessary that the width of the lower electrode film removing portion 330 that separates the lower electrode film 1 from the lower electrode film 60 be at least as long as the insulating strength between the lower electrode film 60 and the discontinuous lower electrode film 61 can be maintained. It is preferable to maintain rigidity.

On the peripheral wall of the discontinuous lower electrode film 61 opposite to the pressure generating chamber 12, a lead electrode discontinuous with the lower electrode film 60 and having one end connected to an external terminal (not shown) is provided. A wiring lower electrode film 62 to be used is provided. The lower electrode film for wiring 62 is provided with a lower electrode film removing portion 330.
As a result, the discontinuous lower electrode 61 is discontinuous, and is patterned for each piezoelectric active portion 320. Then, the piezoelectric film 70 and the upper electrode film 80 are formed by the lower electrode film 62 for wiring.
The upper electrode film 8 is extended by the connection wiring 90.
0 and the wiring lower electrode film 62 are connected.

Thus, in this embodiment, the discontinuous lower electrode film 61 becomes a floating electrode that is not electrically connected to any other components, and the piezoelectric film 70 and the upper electrode film 80 existing on the lower electrode film 60 are formed. Constitutes a piezoelectric active portion 320 which is a substantial driving portion, and the piezoelectric film 70 and the upper electrode film 80 on the discontinuous lower electrode film 61 are not strongly driven.

With such a configuration, the boundary between the pressure generating chamber 12 and the peripheral wall is not strongly driven by the application of the voltage to the piezoelectric active portion 320. The rigidity of the diaphragm at this point is high, and it is possible to prevent the breakdown of the diaphragm or the breakdown of the piezoelectric film 70 at this portion.

In the present embodiment, the discontinuous lower electrode film 6
1 is formed in the direction in which the plurality of pressure generating chambers 12 are juxtaposed, but is not limited to this. For example, as shown in FIG. Is also good. Thus, the piezoelectric film 7 on the discontinuous lower electrode 61
Since the zero and upper electrode films 80 are not completely driven, breakage of the diaphragm or the piezoelectric film 70 can be more reliably prevented.

In this embodiment, the discontinuous lower electrode film 6
1 is a floating electrode that is not electrically connected to other parts, but is not limited to this. For example,
It may be connected to the electrode layer via a resistor having a predetermined resistance value so that the charging time constant is larger than the drive pulse of the piezoelectric active section 320.

A series of film formation and anisotropic etching of the piezoelectric active portion 320 and the pressure generating chamber 12 described above are performed by:
A large number of chips are simultaneously formed on one wafer, and after completion of the process, the wafer is divided into flow path forming substrates 10 each having one chip size as shown in FIG. 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 external ink supply means (not shown),
After filling the interior from 1 to the nozzle opening 11 with ink, a voltage is applied between the upper electrode film 80 and the lower electrode film 60 according to a recording signal from an external drive circuit (not shown), By bending and deforming the lower electrode film 60 and the piezoelectric film 70, the pressure in the pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle openings 11.

(Embodiment 2) FIG. 9 is a sectional view of a main part of an ink jet recording head according to Embodiment 2.

In this embodiment, as shown in FIG. 9, the discontinuous lower electrode film 61 has a lower electrode film removing portion 330 near the end of the pressure generating chamber 12 in the direction in which the pressure generating chambers are juxtaposed. It is provided and is discontinuous with the lower electrode film 60. The lower electrode film removing section 330 extends in the longitudinal direction of the pressure generating chamber 12 on the peripheral wall in the width direction of each pressure generating chamber 12, and the discontinuous lower electrode film 61 corresponds to each piezoelectric active section 320. And have been separated. That is, each of the separated discontinuous lower electrode films 61 is left in a state of being patterned so as to form a wiring corresponding to each piezoelectric active portion 320.

Here, the width of the lower electrode film removing portion 330 for separating each discontinuous lower electrode film 61 is formed to be narrow enough to maintain at least the insulation strength thereof. Of course, the lower electrode film 60 and the discontinuous lower electrode film 61 also have the same insulation strength as in the first embodiment.

The piezoelectric film 70 and the upper electrode film 80 extending from each of the piezoelectric active portions 320 are extended to above the discontinuous lower electrode film 61, and the upper electrode film 80 and the discontinuous lower electrode film are extended. 61 are connected by a connection wiring 90. The discontinuous lower electrode film 61 is connected to an external wiring near its end, and is used as a lead electrode.

In such a configuration, the discontinuous lower electrode film 61
Can be used effectively, and the manufacturing process can be simplified and the manufacturing cost can be reduced. Of course, also in the present embodiment, the same effect as in the first embodiment can be obtained.

(Embodiment 3) FIG. 10 is a sectional view of an essential part of an ink jet recording head according to Embodiment 3.

In this embodiment, as shown in FIG. 10, an intermediate electrode film 340 which is separated by a lower electrode film removing section 330 and is not connected to any other is provided between each discontinuous lower electrode film 61. Except for this, the configuration is the same as that of the second embodiment.

With such a configuration, the width of the lower electrode film removing portion 330 separating each discontinuous lower electrode film 61 can be reduced. That is, since the intermediate electrode film 340 is provided between the discontinuous lower electrode films 61, even if the width of the lower electrode film removing portion 330 is reduced, the insulation strength thereof can be reliably maintained. Thereby, the rigidity of the diaphragm is further increased, and the diaphragm is broken or the piezoelectric film 70 is broken at the boundary between the pressure generating chamber 12 and the peripheral wall as in the above-described embodiment.
Can be prevented from being destroyed.

In the above embodiment, the lower electrode film 60
And lower electrode film removing section 330 between discontinuous lower electrode film 61
Is formed with a width that can maintain the insulation strength between each lower electrode film 60 and the discontinuous lower electrode film 61.
As shown in FIG. 11, for example, the upper electrode film 80
May be removed to provide an inactive portion 350 in which the piezoelectric film 70 that is not substantially driven remains. Thereby, the insulation strength can be more reliably maintained. Needless to say, if the piezoelectric film 70 is not driven, the upper electrode film 80 need not be removed.

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

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

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

FIG. 12 is an exploded perspective view of the embodiment configured as described above, and FIG. 13 is a cross-sectional view of the flow path. In this embodiment, the nozzle openings 11 are drilled in the nozzle substrate 120 opposite to the piezoelectric vibrator, and these nozzle openings 11
A nozzle communication port 22 for communicating the pressure generating chamber 12 with the pressure generating chamber 12 is provided so as to penetrate the sealing plate 20, the common ink chamber forming plate 30, the thin plate 41A, and the ink chamber side plate 40A.

In this embodiment, the thin plate 41
A is basically the same as the above-described embodiment except that the ink chamber side plate 40A and the ink chamber side plate 40A are separate members, and the opening is formed in the ink chamber side plate 40A. Is omitted.

Of course, it is needless to say that the above-described embodiments can be more effective when implemented in combination as appropriate.

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

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 according to 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. 14, the recording head units 1A and 1B having the ink jet recording heads
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 3. The platen 8 can be rotated by a driving force of a paper feed motor (not shown), and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller, is wound around the platen 8 and conveyed. It has become so.

[0087]

As described above, according to the present invention, a discontinuous lower electrode that is discontinuous with the lower electrode film of the piezoelectric active part is provided below the piezoelectric film extending from the piezoelectric active part. Since the membrane is provided, the rigidity of the diaphragm at the boundary between the end of the pressure generating chamber and the peripheral wall is increased, and the breakage of the diaphragm or the piezoelectric layer at this portion can be prevented. . In addition, the thickness of the piezoelectric layer becomes uniform, and the effect of preventing a decrease in dielectric strength can be prevented.

[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 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 perspective view showing a modification of the sealing plate of FIG. 1;

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 illustrating a thin-film manufacturing process according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a thin-film manufacturing process according to the first embodiment of the present invention.

FIGS. 7A and 7B are a plan view and a cross-sectional view illustrating a main part of the inkjet recording head according to the first embodiment of the invention.

FIG. 8 is a plan view showing a modified example of the ink jet recording head according to the first embodiment of the present invention.

FIG. 9 is a plan view illustrating a main part of an ink jet recording head according to a second embodiment of the present invention.

FIG. 10 is a plan view illustrating a main part of an ink jet recording head according to a third embodiment of the invention.

FIG. 11 is a plan view and a cross-sectional view illustrating a main part of an inkjet recording head according to another embodiment of the present invention.

FIG. 12 is an exploded perspective view of an ink jet recording head according to another embodiment of the present invention.

FIG. 13 is a cross-sectional view illustrating an ink jet recording head according to another embodiment of the present invention.

FIG. 14 is a schematic view 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 discontinuous lower electrode film 62 lower electrode film for wiring 70 piezoelectric film 80 upper electrode film 300 piezoelectric element 320 piezoelectric active portion 330 lower electrode film removing portion 340 Intermediate electrode film 350 Inactive part

Claims (11)

[Claims] 1. A pressure generating chamber communicating with a nozzle opening, a lower electrode provided in a region corresponding to the pressure generating chamber, a piezoelectric layer provided on the lower electrode, and a surface provided on the piezoelectric layer. An ink jet recording head comprising: a piezoelectric element having a piezoelectric active portion, which is a substantially driving portion in a region facing the pressure generating chamber, the piezoelectric element comprising the piezoelectric active portion. The body layer and the upper electrode extend from inside a region facing the pressure generating chamber to outside the region, and are disposed below the piezoelectric layer in a region facing an end of the pressure generating chamber and the peripheral wall and a boundary portion. An ink jet recording head, wherein a discontinuous lower electrode that is discontinuous to the lower electrode is provided on the side. 2. The lower electrode removing section according to claim 1, wherein the discontinuous lower electrode is provided near a longitudinal end of the pressure generating chamber of the lower electrode and extends at least in a direction in which the pressure generating chambers are arranged. An ink jet recording head which is discontinuous with the lower electrode. 3. The ink jet recording head according to claim 1, wherein the discontinuous lower electrode is not electrically connected to any of the electrodes. 4. The ink jet recording head according to claim 1, wherein the discontinuous lower electrode is connected to a resistor so that a charging time constant is larger than a driving pulse. 5. The non-continuous lower electrode according to claim 1, wherein:
A wiring lower electrode that is discontinuous with the discontinuous lower electrode and one end of which is connected to an external wiring is provided for each of the piezoelectric elements, and the piezoelectric layer and the upper electrode extend to the wiring lower electrode. An ink jet recording head which is extended and the upper electrode is connected to the lower electrode for wiring. 6. The piezoelectric active part according to claim 1, wherein the discontinuous lower electrode is separated for each of the piezoelectric active parts in a longitudinal direction of the pressure generating chamber. An ink jet recording head connected to an electrode. 7. The ink-jet recording head according to claim 6, wherein each of the discontinuous lower electrodes and the lower electrodes has an interval capable of being insulated. 8. The ink-jet recording head according to claim 6, further comprising an intermediate electrode connected between the adjacent discontinuous lower electrodes. 9. The piezoelectric layer according to claim 1, wherein the piezoelectric layer remains in at least a part of the lower electrode film removed portion other than a region corresponding to the piezoelectric element. Ink jet recording head. 10. 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 a thin film and a lithography method. An ink jet recording head, characterized in that: 11. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.