JP3610811B2 - Inkjet recording head and inkjet recording apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording head in which an initial deformation of a diaphragm is eliminated to improve a displacement amount, and the durability of the diaphragm is improved.
[0002]
[Prior art]
A part of the pressure generation chamber that communicates with the nozzle opening that ejects ink droplets is composed of a diaphragm, and the diaphragm is deformed by a piezoelectric vibrator to pressurize the ink in the pressure generation chamber and eject ink droplets from the nozzle opening. Two types of ink jet recording heads have been put into practical use, one that uses a piezoelectric vibrator in a longitudinal vibration mode that extends and contracts in the axial direction of the piezoelectric vibrator and one that uses a piezoelectric vibrator in a flexural vibration mode. Yes.
[0003]
The former can change the volume of the pressure generation chamber by bringing the end face of the piezoelectric vibrator into contact with the vibration plate, making it possible to manufacture a head suitable for high-density printing. There is a problem that the manufacturing process is complicated because it requires a difficult process of cutting into a comb-tooth shape in accordance with the arrangement pitch of the above and an operation of positioning and fixing the cut piezoelectric vibrator in the pressure generating chamber.
[0004]
On the other hand, in the latter case, a piezoelectric vibrator can be formed on the diaphragm by a relatively simple process of attaching a green sheet of piezoelectric material in accordance with the shape of the pressure generating chamber and firing it. In order to use vibration, a certain area is required, and there is a problem that high-density arrangement is difficult.
[0005]
On the other hand, in order to eliminate the inconvenience of the latter recording head, a uniform piezoelectric material layer is formed by thin film technology over the entire surface of the diaphragm as seen in Japanese Patent Laid-Open No. 5-286131. There has been proposed a method in which a piezoelectric vibrator is formed so that a layer is cut into a shape corresponding to a pressure generation chamber by a lithography method and independent for each pressure generation chamber.
[0006]
This eliminates the need to affix the piezoelectric vibrator to the diaphragm, so that not only can the piezoelectric vibrator be created by a precise and simple technique called lithography, but also the thickness of the piezoelectric vibrator can be reduced. There is an advantage that it can be made thin and can be driven at high speed.
[0007]
[Problems to be solved by the invention]
However, the above-described thin film technology and the manufacturing method using the lithography method have a problem that it is difficult to obtain a sufficient discharge capacity because the amount of deformation caused by driving the piezoelectric vibrator is small.
[0008]
In view of such circumstances, it is an object of the present invention to provide an ink jet recording head in which an amount of deformation is improved by driving a piezoelectric vibrator.
[0009]
[Means for Solving the Problems]
According to a first aspect of the present invention for solving the above-mentioned problem, a diaphragm comprising a part of a pressure generating chamber communicating with a nozzle opening and comprising an elastic film and a lower electrode formed thereon, and the diaphragm A piezoelectric layer formed on the surface of the substrate and an upper electrode formed on the surface of the piezoelectric layer. At least the lower electrode, the piezoelectric layer, and the upper electrode are formed using a film formation and lithography method. In the ink jet recording head including the piezoelectric vibrator, the vibration plate has a recess extending in the longitudinal direction at least on both sides in the width direction inside the pressure generating chamber, and the depth of the recess is determined by the thickness of the elastic film. The ink jet recording head is characterized in that it is 0.5 times or more and reaches a part of the lower electrode.
[0010]
In the first aspect, by providing the concave portion, the displacement amount of the diaphragm due to the driving of the piezoelectric active portion can be greatly improved.
[0011]
According to a second aspect of the present invention, in the ink jet recording head according to the first aspect, the elastic film includes a first elastic film and a second elastic film provided thereon. is there.
[0012]
In the second aspect, the durability of the elastic film is improved.
[0013]
A third aspect of the present invention is an ink jet recording apparatus comprising the ink jet recording head described in the first or second aspect.
[0014]
In the third aspect, the ink jet recording apparatus with improved head characteristics and improved reliability can be realized.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on embodiments.
[0022]
(Embodiment 1)
FIG. 1 is an assembled perspective view showing an ink jet recording head according to Embodiment 1 of the present invention, and FIG. 2 is a plan view and a cross-sectional view in the longitudinal direction of one pressure generating chamber.
[0023]
As shown in the drawing, the flow path forming substrate 10 is composed of a silicon single crystal substrate having a plane orientation (110) in this embodiment. As the flow path forming substrate 10, one having a thickness of about 150 to 300 μm is usually used, preferably about 180 to 280 μm, more preferably about 220 μm. This is because the arrangement density can be increased while maintaining the rigidity of the partition between adjacent pressure generating chambers.
[0024]
Elastic films 50 and 51 having a thickness of 0.1 to 2 μm made of silicon dioxide previously formed by thermal oxidation are formed on both surfaces of the flow path forming substrate 10. Further, on one surface of the flow path forming substrate 10, after the elastic film 51 is patterned, the silicon single crystal substrate is anisotropically etched to form the nozzle opening 11 and the pressure generating chamber 12.
[0025]
Here, in the anisotropic etching, when the silicon single crystal substrate is immersed in an alkaline solution such as KOH, the first (111) plane perpendicular to the (110) plane is gradually eroded and the first (111) ) Surface and an angle of about 70 degrees and the above (110) and a second (111) surface of about 35 degrees appear, and the (111) surface compared to the etching rate of the (110) surface. The etching rate is about 1/180. By this anisotropic etching, precision processing can be performed based on the parallelogram depth processing formed by two first (111) surfaces and two oblique second (111) surfaces. The pressure generating chambers 12 can be arranged with high density.
[0026]
In the present 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 substantially penetrates the flow path forming substrate 10 and is formed by etching up to a part of the elastic film 50 as will be described later. Note that the elastic film 50 is extremely small in the amount of being attacked by the alkaline solution for etching the silicon single crystal substrate.
[0027]
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 etching (half etching) the silicon single crystal substrate halfway in the thickness direction. Half etching is performed by adjusting the etching time.
[0028]
Here, the size of the pressure generation chamber 12 that applies ink droplet discharge pressure to the ink and the size of the nozzle opening 11 that discharges ink droplets are optimized according to the amount of ink droplets to be discharged, the discharge speed, and the discharge frequency. The For example, when recording 360 ink droplets per inch, the nozzle opening 11 needs to be accurately formed with a groove width of several tens of μm.
[0029]
Further, each pressure generating chamber 12 and a common ink chamber 31 described later communicate with each other through an ink supply communication port 21 formed at a position corresponding to one end portion of each pressure generating chamber 12 of a sealing plate 20 described later. The ink is supplied from the common ink chamber 31 through the ink supply communication port 21 and is distributed to the pressure generating chambers 12.
[0030]
The sealing plate 20 is provided with an ink supply communication port 21 corresponding to each of the pressure generation chambers 12 described above, has a thickness of, for example, 0.1 to 1 mm, a linear expansion coefficient of 300 ° C. or less, and, for example, 2 5 to 4.5 [× 10 ⁻⁶ / ° C.]. The ink supply communication port 21 may be a single slit hole that crosses the vicinity of the ink supply side end of each pressure generating chamber 12 or a plurality of slit holes. The sealing plate 20 entirely covers one surface of the flow path forming substrate 10 on one side, and also serves as a reinforcing plate that protects the silicon single crystal substrate from impact and external force. The sealing plate 20 constitutes one wall surface of the common ink chamber 31 on the other surface.
[0031]
The common ink chamber forming substrate 30 forms the peripheral wall of the common ink chamber 31, and is produced by punching a stainless plate having an appropriate thickness according to the nozzle numerical aperture and the ink droplet ejection frequency. In the present embodiment, the common ink chamber forming substrate 30 has a thickness of 0.2 mm.
[0032]
The ink chamber side plate 40 is made of a stainless steel substrate, and constitutes one wall surface of the common ink chamber 31 on one surface. Further, the ink chamber side plate 40 is formed with a thin wall 41 by forming a recess 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 the pressure generated when ink droplets are discharged toward the opposite side of the nozzle opening 11, and is unnecessary for the other pressure generation chamber 12 via the common ink chamber 31. Prevent the application of positive or negative pressure. In the present embodiment, the ink chamber side plate 40 is set to 0.2 mm and a part thereof is a thin wall having a thickness of 0.02 mm in consideration of rigidity required when the ink introduction port 42 is connected to an external ink supply unit. Although the wall 41 is used, 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.
[0033]
On the other hand, on the elastic film 50 opposite to the pressure generating chamber 12 of the flow path forming substrate 10, a lower electrode film 60 having a thickness of, for example, about 0.5 μm and a piezoelectric film having a thickness of, for example, about 1 μm. A body film 70 and an upper electrode film 80 having a thickness of, for example, about 0.1 μm are laminated by a process described later to constitute a piezoelectric vibrator (piezoelectric element). Thus, in the region facing the pressure generation chambers 12 of the elastic film 50, the piezoelectric vibrator is provided independently for each pressure generation chamber 12, and in this embodiment, the lower electrode film 60 is a piezoelectric film. The common electrode of the vibrator is used and the upper electrode film 80 is an individual electrode of the piezoelectric vibrator. However, there is no problem even if this is reversed for the convenience of the drive circuit and wiring. Further, in the present embodiment, the piezoelectric film 70 is individually provided corresponding to each pressure generating chamber 12, but the piezoelectric film is provided as a whole and the upper electrode film 80 corresponds to each pressure generating chamber 12. It may be provided individually. In any case, a piezoelectric active part is formed for each pressure generating chamber 12.
[0034]
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 FIG.
[0035]
As shown in FIG. 3A, first, a silicon single crystal substrate wafer to be the flow path forming substrate 10 is thermally oxidized in a diffusion furnace at about 1100 ° C., and both sides of the flow path forming substrate 10 are made of silicon dioxide. The elastic films 50 and 51 are formed at a time.
[0036]
Next, as shown in FIG. 3B, the lower electrode film 60 is formed by sputtering. As a material of the lower electrode film 60, Pt or the like is suitable. This is because a piezoelectric film 70 described later formed by sputtering or a sol-gel method needs to be crystallized by firing at a temperature of about 600 to 1000 ° C. in an air atmosphere or an oxygen atmosphere after the film formation. It is. That is, the material of the lower electrode film 70 must be able to maintain conductivity at such a high temperature and in an oxidizing atmosphere. In particular, when PZT is used as the piezoelectric film 70, the conductivity due to the diffusion of PbO. It is desirable that there is little change in properties, and Pt is preferred for these reasons.
[0037]
Next, as shown in FIG. 3C, a piezoelectric film 70 is formed. Sputtering can be used to form the piezoelectric film 70. In this embodiment, a so-called sol in which a metal organic material is dissolved and dispersed in a solvent is applied, dried, gelled, and further fired at a high temperature. A so-called sol-gel method for obtaining a piezoelectric film 70 made of an oxide is used. As a material of the piezoelectric film 70, a lead zirconate titanate (PZT) -based material is suitable when used for an ink jet recording head.
[0038]
Next, as shown in FIG. 3D, an upper electrode film 80 is formed. The upper electrode film 80 may be made of a highly conductive material, and many metals such as Al, Au, Ni, and Pt, conductive oxides, and the like can be used. In this embodiment, Pt is formed by sputtering.
[0039]
Next, as shown in FIG. 4, the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 80 are patterned.
[0040]
First, as shown in FIG. 4A, the lower electrode film 60, the piezoelectric film 70, and the upper electrode film 80 are etched together to pattern the entire pattern of the lower electrode film 60. Next, as shown in FIG. 4B, only the piezoelectric film 70 and the upper electrode film 80 are etched to pattern the piezoelectric active portion 320.
[0041]
The above is the film forming process. After the film is formed in this manner, as shown in FIG. 5, the silicon single crystal substrate is anisotropically etched with the alkali solution described above to form the pressure generating chamber 12 and the like. At this time, in this embodiment, a concave portion described later is formed at a position facing the arm portion of the piezoelectric active portion on the pressure generating chamber 12 side of the diaphragm.
[0042]
First, as shown in FIG. 5A, a portion of the elastic film 51 corresponding to the position where the pressure generating chamber 12 is formed is patterned to form an opening 51a and a step 51b having a relatively thin film thickness. The opening 51 a is provided in a region corresponding to a concave portion to be described later, in this embodiment, on both sides of the portion facing the piezoelectric active portion, and the stepped portion 51 b is provided in the piezoelectric active portion of the pressure generating chamber 12. It is provided in a region corresponding to the part. The step 51a may be formed by half etching or the like.
[0043]
Next, as shown in FIG. 5B, the silicon single crystal substrate is anisotropically etched with the alkali solution described above to form the pressure generating chamber 12 and the recess 330. By this etching, first, the silicon single crystal substrate in the region of the opening 51a is eroded, and at the same time, the surrounding stepped portion 51b is also eroded. As a result, the step portion 51b is completely removed, and the portion of the silicon single crystal substrate covered with the step portion 51b is eroded with a delay. Thereafter, the silicon single crystal substrate in the region of the opening 51a is completely removed, but etching is performed until the silicon single crystal substrate in the region of the stepped portion 51b is completely removed, that is, until the pressure generation chamber 12 is formed. As a result, the elastic film 50 in the region of the opening 51a is eroded and a recess 330 is formed.
[0044]
The depth of the concave portion 330 can be adjusted by the thickness of the step portion 51b. That is, the thicker the step 51b is, the deeper the recess 330 is formed. Further, the depth of the recess 330 is preferably in a range reaching 0.5 part or more of the elastic film 50 and reaching a part of the lower electrode film 60. Note that the elastic film 51 needs to be formed thicker than the elastic film 50 so that the depth of the recess 330 reaches a part of the lower electrode film 60.
[0045]
FIG. 6 shows the positional relationship between the recess 330 thus formed, the piezoelectric active part 320 and the pressure generating chamber 12. 6A is a plan view, and FIGS. 6B and 6C are a cross-sectional view taken along the line BB ′ and a cross-sectional view taken along the line CC ′, respectively.
[0046]
As shown in the figure, the concave portion 330 of the present embodiment has a thickness of the elastic film 50 across the longitudinal direction on the elastic film 50 on both sides in the width direction of the piezoelectric active portion 320 in a region facing the pressure generating chamber 12. Is formed at a depth of about 0.5 to 1 times.
[0047]
The depth of the concave portion 330 improves the amount of deformation of the diaphragm, but must be designed so as not to greatly affect the decrease in the durability of the diaphragm, and is not less than 0.5 times the film thickness of the elastic film 50. A range up to reaching a part of the lower electrode film 60 is preferable. In addition, the width and length of the concave portion 330 must be designed so as not to greatly affect the durability of the diaphragm in consideration of the size of the piezoelectric active portion and the like.
[0048]
As described above, in the present embodiment, by forming the recesses 330 on both sides in the width direction of the piezoelectric active part, it is possible to reduce the stress due to the driving of the piezoelectric active part and improve the displacement. Moreover, since the recessed part 330 can be formed simultaneously with the pressure generation chamber 12, it can be formed easily, without increasing a manufacturing process.
[0049]
In this embodiment, the elastic film 50 is formed of a single silicon dioxide film. However, the present invention is not limited to this, and another layer may be provided and the elastic film may be formed of a plurality of layers. Good.
[0050]
For example, as shown in FIG. 7, a second elastic film 52 made of a hard material such as zirconia oxide may be provided between the elastic film 50 and the lower electrode film 60. Thereby, the residual stress applied to the flow path forming substrate 10 after the formation of the piezoelectric active portion 320 can be reduced, and the vibration plate can be prevented from being broken due to the stress change when the pressure generating chamber 12 is formed. .
[0051]
When the second elastic film 52 is provided in this manner, the elastic plate is not easily deformed, and therefore, it is particularly necessary to form the recess 330 in the elastic film 50.
[0052]
In the above description, the pressure generation chamber 12 is formed after the formation of the piezoelectric active portion 320, but actually, as shown in FIG. 2, at least the periphery of the upper surface of each upper electrode film 80, and the piezoelectric An insulating layer 90 having electrical insulation is formed so as to cover the side surfaces of the body film 70 and the lower electrode film 60, and an upper surface of a portion corresponding to one end portion of each piezoelectric active portion 320 of the insulating layer 90 A contact hole 90a exposing a part of the upper electrode film 80 is formed in a part of the portion covering the lead electrode 100, and one end is connected to each upper electrode film 80 through the contact hole 90a. Alternatively, the pressure generation chamber 12 may be formed after the lead electrode 100 having the other end extending to the connection terminal portion is formed. Here, the lead electrode 100 is preferably formed to have a width as narrow as possible so that a drive signal can be reliably supplied to the upper electrode film 80.
[0053]
In the present embodiment, the contact hole 90a is provided at a position facing the peripheral wall of the pressure generating chamber 12. However, the piezoelectric active portion 320 is patterned in a region facing the pressure generating chamber 12 to generate pressure. A contact hole 90 a may be provided at a position facing the chamber 12.
[0054]
Further, in the series of film formation and anisotropic etching described above, a large number of chips are simultaneously formed on a single wafer, and after the completion of the process, a flow path forming substrate 10 having a single chip size as shown in FIG. Divide every time. Further, the divided flow path forming substrate 10 is sequentially bonded 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.
[0055]
The ink jet head configured in this manner 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, and then fills the outside with an external (not shown). In accordance with a recording signal from the drive circuit, a voltage is applied between the lower electrode film 60 and the upper electrode film 80 via the lead electrode 100 to bend and deform the elastic film 50, the lower electrode film 60, and the piezoelectric film 70. As a result, the pressure in the pressure generating chamber 12 increases, and ink droplets are ejected from the nozzle openings 11.
[0056]
(Other embodiments)
While the embodiments of the present invention have been described above, the basic configuration of the ink jet recording head is not limited to that described above.
[0057]
For example, in addition to the sealing plate 20 described above, the common ink chamber forming plate 30 may be made of glass ceramics, and further, the thin film 41 may be made of glass ceramics as a separate member. It is.
[0058]
In the above-described embodiment, the nozzle opening is formed on the end face of the flow path forming substrate 10, but the nozzle opening protruding in the direction perpendicular to the face may be formed.
[0059]
FIG. 8 shows an exploded perspective view of the embodiment configured as described above, and FIG. 9 shows a cross section of the flow path. In this embodiment, the nozzle openings 11 are formed in the nozzle substrate 120 opposite to the piezoelectric vibrator, and the nozzle communication ports 22 that connect the nozzle openings 11 and the pressure generating chambers 12 are the sealing plate 20 and the common ink. The chamber forming plate 30, the thin plate 41A, and the ink chamber side plate 40A are arranged so as to penetrate.
[0060]
The present embodiment is basically the same as the above-described embodiment except that the thin plate 41A and the ink chamber side plate 40A are separate members, and the opening 40b is formed in the ink chamber side plate 40. Are denoted by the same reference numerals, and redundant description is omitted.
[0061]
Here, in this embodiment as well, as in the above-described embodiment, by providing a recess in the diaphragm on the pressure generation chamber side, stress due to driving of the piezoelectric body active portion can be suppressed, and the amount of displacement can be improved. it can.
[0062]
Of course, the present invention can be similarly applied to an ink jet type recording head in which a common ink chamber is formed in a flow path forming substrate.
[0063]
In each of the embodiments described above, a thin film type ink jet recording head that can be manufactured by applying a film forming and lithography process is taken as an example. However, the present invention is not limited to this example. Ink jet recording heads of various structures, such as those that form pressure generation chambers, those that form a piezoelectric film by attaching a green sheet or screen printing, or those that form a piezoelectric film by crystal growth The present invention can be employed.
[0064]
Further, in the above-described embodiment, the elastic film is provided as the diaphragm separately from the lower electrode film, but the lower electrode film may also serve as the elastic film.
[0065]
In addition, the example in which the insulator layer is provided between the piezoelectric vibrator and the lead electrode has been described. However, the present invention is not limited to this. For example, without providing the insulator layer, an anisotropic conductive film is provided on each upper electrode. It is good also as a structure which heat-welds and connects this anisotropic conductive film with a lead electrode, and connects using various bonding techniques, such as wire bonding.
[0066]
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. In addition, the ink jet recording head of each of these embodiments constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus. FIG. 10 is a schematic view showing an example of the ink jet recording.
[0067]
As shown in FIG. 10, in the recording head units 1A and 1B having the ink jet recording head, cartridges 2A and 2B constituting ink supply means are detachably provided, and 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 body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, each discharge a black ink composition.
[0068]
The driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and timing belt 7 (not shown), so that the carriage 3 on which the recording head units 1A and 1B are mounted is moved along the carriage shaft 5. The On the other hand, the apparatus 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.
[0069]
【The invention's effect】
As described above, according to the present invention, since the concave portion is formed in the diaphragm inside the pressure generating chamber, the stress due to the driving of the piezoelectric active portion can be suppressed and the amount of displacement can be improved. Further, since the recess can be formed at the same time as the pressure generating chamber, it can be easily formed without increasing the number of manufacturing steps.
[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.
2A and 2B are diagrams illustrating an ink jet recording head according to the first embodiment of the invention, and are a plan view and a cross-sectional view of FIG.
FIG. 3 is a diagram showing a thin film manufacturing process according to the first embodiment of the present invention.
FIG. 4 is a diagram showing a thin film manufacturing process according to Embodiment 1 of the present invention.
FIG. 5 is a diagram illustrating a manufacturing process of a pressure generating chamber and a recess according to the first embodiment of the present invention.
6A and 6B are a plan view and a cross-sectional view showing a main part of the ink jet recording head according to the first embodiment of the invention.
FIG. 7 is a cross-sectional view showing deformation of the diaphragm.
FIG. 8 is an exploded perspective view of an ink jet recording head according to another embodiment of the present invention.
FIG. 9 is a cross-sectional view showing an ink jet recording head according to another embodiment of the present invention.
FIG. 10 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 formation board | substrate 11 Nozzle opening 12 Pressure generating chambers 50 and 51 Elastic film 52 2nd elastic film 60 Lower electrode film 70 Piezoelectric film 80 Upper electrode film 90 Insulator layer 100 Lead electrode 320 Piezoelectric active part 330 Recessed part

Claims (3)

A diaphragm comprising a part of a pressure generating chamber communicating with the nozzle opening, and comprising an elastic film and a lower electrode formed thereon, a piezoelectric layer formed on the surface of the diaphragm, and the piezoelectric layer Inkjet type comprising a piezoelectric active part comprising an upper electrode formed on the surface of the substrate and comprising at least the lower electrode, the piezoelectric layer, and a piezoelectric vibrator in which the upper electrode is formed using a film forming and lithography method In the recording head,
The diaphragm has a recess extending in the longitudinal direction at least on both sides in the width direction inside the pressure generating chamber,
The depth of the concave portion is 0.5 times or more the thickness of the elastic film and is in a range up to reaching a part of the lower electrode. 2. The ink jet recording head according to claim 1, wherein the elastic film comprises a first elastic film and a second elastic film provided thereon. An ink jet recording apparatus comprising the ink jet recording head according to claim 1.

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