JPH05220955A - Ink jet head and production thereof - Google Patents

Abstract

PURPOSE:To faithfully and efficiently transmit the displacement of a piezoelectric element to an ink chamber to stably deliver an ink drop by a method wherein the piezoelectric element is positionally corrected in a displacing direction by a flat layer for the more accurate positioning of the piezoelectric element in the production process. CONSTITUTION:In an ink jet head in which an ink drop is delivered from a nozzle 2 by displacing an elastic member 8 forming a part of an ink chamber 5 by a piezoelectric element 22, a flat layer 10 is provided between the elastic member 8 and the piezoelectric element 22. The surface of a thin metal plate 6 is brought into contact with ink. The surface of the flat layer 10 is bonded to the piezoelectric element 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head for an on-demand type ink jet printer which ejects ink droplets according to a print signal to form an ink image on a recording medium such as recording paper, and a method for manufacturing the same.

[0002]

2. Description of the Related Art There are roughly three types of recording heads for so-called on-demand type ink jet printers that eject ink droplets in response to a print signal. The first type is a so-called bubble jet type in which a heater for instantaneously vaporizing ink is provided at the tip of the nozzle to generate and fly an ink droplet by the expansion pressure when the ink vaporizes. In the second type, a part of a container forming an ink chamber is composed of a piezoelectric element that is deformed by applying a voltage, and the pressure in the container generated by the deformation of the piezoelectric element causes ink to fly as a droplet. It is a thing. Further, in the third type, a piezoelectric element is provided in an ink chamber provided with a nozzle, the ink pressure in the ink chamber is changed by expansion and contraction of the piezoelectric element, and the ink is ejected as a droplet from the nozzle. The third type of on-demand type ink jet head is disclosed in Japanese Patent Publication No. 2-45985.
As disclosed in Japanese Patent Publication No. 52625/1990 and the other end of a piezoelectric element, one end of which is fixed to a base, is elastically contacted with an elastic wall of a container forming an ink chamber through a leg portion. Consists of According to the technique of the publication, as shown in FIGS. 3 and 4 of both publications, the elastic wall is bent in advance toward the ink chamber. In this state, the piezoelectric element is contracted to return the deflection of the elastic wall, and the piezoelectric element is expanded again to eject the ink in the ink chamber as a droplet from the nozzle. this,
As a means for flexing the elastic wall in advance, it is disclosed that a viscoelastic member is pushed between the leg portion and the elastic wall, and that a protruding portion is provided on the leg portion or the elastic wall.

[0003]

Reducing the size of the recording head,
The higher the density, the smaller the piezoelectric element and the ink chamber.
Therefore, the displacement amount of the piezoelectric element also becomes small, and the displacement of the piezoelectric element must be more efficiently transmitted to the ink chamber. Therefore, it is extremely important to pay attention to the joint between the piezoelectric element and the elastic member, particularly the positioning in the displacement direction of the piezoelectric element. However, in the configuration of the above-mentioned publication, the viscoelastic member and the elastic wall around the protruding portion absorb a considerable amount of pressure. Further, regarding the displacement direction of the piezoelectric element, since the viscoelastic member and the elastic wall are provided with a structure that bends in advance, the restored position of the piezoelectric element is difficult to stabilize, and the deflection amount is likely to vary. As a result, the speed of the ejected ink droplets, the volume of the ink droplets, the ejection response frequency, and the ejection characteristics of the ink droplets may become unstable. Further, since the structure of the same technology has a structure in which the leg portion is supported by being in line contact with the bearing portion, loss may occur here.

On the other hand, regarding the method of manufacturing the same head, when a plurality of ink chambers and the piezoelectric element are arranged in parallel, it is important to stabilize the position of the piezoelectric element in the displacement direction during manufacturing. By using, it becomes extremely difficult to reduce the variation of the position of the piezoelectric element in the displacement direction during manufacturing.

Therefore, an object of the present invention is to realize a head having a small ink pressure loss and stable ejection of ink droplets, and a method of manufacturing the head, with a simple structure and method.

[0006]

An ink jet head of the present invention is an ink jet head in which an elastic member forming a part of an ink chamber is displaced by a piezoelectric element to increase ink pressure in the ink chamber and eject an ink droplet from a nozzle. In the above, in at least one of the elastic member and the piezoelectric element, a flattening layer is provided for the purpose of correcting variation in the position in the displacement direction of the piezoelectric element during manufacturing. Further, the flattening layer is made of a photosensitive resin. Furthermore, the manufacturing method is characterized in that the member for providing the planarizing layer forms the planarizing layer after at least two members are joined. Further, the flattening layer is formed by providing a curable substance having fluidity between the reference flat plate side and the elastic member or the piezoelectric element, and then selectively curing the curable substance. It is characterized by

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing the construction of an embodiment of the present invention, in which each component is disassembled after assembly. 2, 3, and 4 are a partial cross-sectional view showing the same embodiment in more detail, a partial perspective view of the same embodiment seen from below, and a partial plan view of the same embodiment seen from directly above, respectively. .. Note that FIG. 4 shows a state in which the constituent parts are sequentially peeled from the top. 5, FIG. 6, FIG.
FIG. 8 shows a manufacturing method for forming a planarizing layer based on the configuration of the embodiment of the present invention. 9 and 10 are partial cross-sectional views of another embodiment of the present invention, FIG. 11 is a partial cross-sectional view illustrating the problems of the conventional example, and FIG. 12 is a partial cross-sectional view illustrating the effect of the present invention.

In these figures, 1 is a nozzle substrate. The nozzle substrate 1 is provided with a plurality of nozzles 2.
Reference numeral 3 is a cavity forming substrate. Cavity forming substrate 3
Is sandwiched between the nozzle substrate 1 and the elastic member 8 serving as an elastic wall to form the reservoir 4 and the ink chamber 5. Elastic member 8
Has a laminated structure including a thin metal plate 6 and a wall member 7.
The elastic member 8, the cavity forming substrate 3, and the nozzle substrate 1 are sequentially adhered and bonded, and then a flattening layer 10 described later is formed on the elastic member 8 side and adhered and bonded on the head frame 11.

A piezoelectric element 22 serving as a drive source for ejecting ink droplets.
Has one half of its longitudinal direction fixed to the fixing base 21, and the other half of the end not fixed is joined to the flattening layer 10. The fixed base 21 is provided with positive and negative conductive wiring patterns 24, and an electric field controlled by the control substrate 13 is applied to the piezoelectric element 22 via the lead frame 25. 1
1 is a head frame. 12 is a head frame 11
The fixing base 21 is supported to position the piezoelectric element 22 in the X and Y directions (see XYZ coordinates in FIG. 1) by the mounting holes penetrating therethrough. In the Z direction of the piezoelectric element 22, after joining the bonded body in which the flattening layer 10, the elastic member 8, the cavity forming substrate 3, and the nozzle substrate 1 are joined to the head frame 11, the tip of the piezoelectric element 22 is flattened. Abut 10 and position. 31 is the ink 5 from the ink reservoir (not shown)
An ink supply pipe for supplying 1. Ink supply pipe 31
Are press-fitted and adhered to the head frame 11. The ink flow path communicates with the reservoir 4 of the cavity forming substrate 3 and further the ink chamber 5 via the ink connection port 32 in the head frame 11, the flattening layer 10, and the ink communication port 33 in the elastic member 8. The above is the schematic configuration.

The structure will be described in more detail with reference to FIG. The positive electrode 41 and the negative electrode 42 of the piezoelectric element 22 face each other. The positive electrode 41 is electrically connected to the wiring pattern 24 on the fixed base 21 at the same time as being joined to the wiring pattern 24, especially the positive electrode conduction pattern. The negative electrode 42 is fixed to the fixed base 21 by the common plate 23.
The upper wiring pattern 24, especially the negative electrode conduction pattern, is electrically connected. The wiring pattern 24 and the control board 13 are connected by a lead frame 25, and the connection points are fixed by soldering. In addition, in the fixing plate 21, the piezoelectric element 22 has the flattening layer 1
It is adhesively fixed to the head frame 11 in a state of being in contact with 0. That is, in the Z direction of the piezoelectric element 22, the planarization layer 1
Position at 0. Therefore, the flat surface 60 of the head frame 11 that contacts the flattening layer 10 is finished with high precision by means such as flat surface polishing. However, in the conventional example in which the flattening layer 10 is not formed, as shown in FIG. 11, when the piezoelectric element 22a and the elastic member 8a are contacted and then directly bonded, the nozzle substrate 1a, the cavity forming substrate 3a, and the elastic member 8a are manufactured. Due to variations and warps in the thickness direction, the gap generated between the fixed plate of the piezoelectric element 22a and the elastic member 8a that abuts with the tip of the half that is not fixed is also varied. An adhesive for fixing the piezoelectric element 22a and the elastic member 8a is interposed in this gap. As a method of applying the adhesive, generally, a certain amount of adhesive is applied to the piezoelectric element 22a.
Alternatively, the elastic member 8a is applied so that there is no variation between the applied portions, and then the two are held in a bonded state to cure the adhesive. Other than this, for example, it is conceivable that after the piezoelectric element 22a and the elastic member 8a are brought into contact with each other, an appropriate amount corresponding to each gap between the piezoelectric element 22a and the elastic member 8a is filled. There is a very small possibility that the restrictions will be realized. Therefore, a method of applying a certain amount of adhesive while controlling it will be adopted. Piezoelectric element 22
When the gap between a and the elastic member 8a varies, as shown in FIG. 11, when the adhesive is bonded, 9a, 9b, 9c,
As shown in the table, a large variation is formed. Here, three typical types are shown, but in reality, more bonding states occur. 9a
Shows a desirable joining state, and a meniscus is formed in a fluid state before hardening, and the joining will be hardened in a stable state. This is because the gap between the elastic member 8a and the piezoelectric element 22a is appropriately maintained. On the other hand, 9b indicates a state in which the gap between the piezoelectric element 22a and the elastic member 8a is larger than an appropriate gap due to variations in thickness direction and warpage during the manufacturing process of the nozzle substrate 1a, the cavity forming substrate 3a, and the elastic member 8a. .. In this state, the adhesive provided in the gap between the piezoelectric element 22a and the elastic member 8a is in a state of being pulled in the Z direction, the curing of the adhesive varies, and the Young's modulus of the cured adhesive is increased. Is not stable and the adhesive strength is also reduced. 9
For c, the piezoelectric element 2 has variations due to the same reason.
The state where the gap between 2a and the elastic member 8a is smaller than an appropriate gap is shown. In this state, the meniscus 9a is destroyed and flows into the elastic member 8a because the gap is too small. When the adhesive flows into the elastic member 8a, the rigidity of the elastic member 8a is affected, and the expansion and contraction of the piezoelectric element 22a cannot be efficiently transmitted to the ink chamber 5.
Furthermore, the adhesive strength between the piezoelectric element 22a and the elastic member 8a may be reduced. Therefore, Z of the piezoelectric element 22
It is important to accurately perform directional positioning and to stabilize the gap between the tip end of the piezoelectric element 22 that is not fixed and the contact surface. FIG. 12 is a partial cross-sectional view illustrating the effect of providing the planarizing layer 10 according to the present invention. In the figure, a flattening layer is formed by the method described later,
The state joined to the piezoelectric element 22a is shown. The flattening layer is 10d, 10e, 10f, ... As shown in FIG. As shown by 9f, it is possible to form a stable meniscus on the adhesive with an appropriate gap. By holding in this state and curing the adhesive, it is possible to obtain stable adhesive strength and prevent the adhesive from flowing into the elastic member 8a.

On the other hand, the ink chamber 5 filled with the ink 51
The reservoir 4 is formed by the cavity forming substrate 3, the nozzle substrate 1, and the elastic member 8. Cavity forming substrate 3
Can be made by etching glass, laminating thin metal plates, exposing and forming a photosensitive resin, injection molding of a resin, and the like. In this embodiment, a photosensitive resin which is inexpensive in cost is used. The nozzle substrate 1 covering the upper surface of the cavity forming substrate 3 is made of a stainless steel plate of about 0.1 mm in which one nozzle 2 is opened in each of the plurality of ink chambers 5 by press working.

The nozzle substrate 1 can also be made by a nickel electroforming method.

The elastic member 8 for covering the lower surface of the cavity forming substrate 3 is formed on a thin metal plate 6 formed to a thickness of 5 μm or less by an electroforming method of nickel.
It has a structure in which wall members 7 each having a thickness of about 0 micron are laminated. The metal thin plate 6 is preferably as thin as possible in order to efficiently transmit the expansion and contraction of the piezoelectric element 22 to the ink chamber 5, but the ink 51 in the ink chamber 5 should not seep out. When the ink 51 exhibits conductivity, the positive electrode 41 of the piezoelectric element 22
This is because the ink 51 adheres to the space between the negative electrodes 42 and the control substrate 13 and causes an electrical short circuit. For the above reason, the metal thin plate 6 cannot be replaced with a resin such as a film. Resin is ink 5 when the thickness is about 5 microns.
1 exudes, and the mechanical strength is insufficient. If the piezoelectric element 22 is directly bonded to the metal thin plate 6, the structure becomes simple, but this is not possible due to the following reasons. For one reason, as shown in FIG. 2, when the positive electrode 41 comes into contact with the thin metal plate 6, the adjacent piezoelectric element is short-circuited. If the positive electrode 41 side is used as the common electrode, the ink 5
An electric field is applied to 1. This means that the ink 51
Will be ionized over time, leading to deterioration of reliability. That is, by disposing the insulating member, that is, the photosensitive resin, in the flattening layer 10, the above problem is solved, and the degree of freedom of wiring for controlling the piezoelectric element 22 is increased. Another reason is that as shown in FIG.
The cross-sectional shape of 2 and the cross-sectional shape of the ink chamber 5 are different from each other in terms of cost and manufacturing. This means that when the piezoelectric element 22 pressurizes and depressurizes the ink chamber 5, as shown in FIG. 4, the elastic member 8 that can be displaced is too short (a) to be sufficiently deflected, and conversely displaced. The length (b) of the elastic member 8 that can be formed is too long to absorb the generated pressure. Therefore, in order to efficiently transfer the pressure of the displacement of the piezoelectric element 22 to the ink chamber 5, an intermediate member capable of properly ensuring the lengths (a) and (b) is required. The wall member 7 is required for the above reasons. The wall member 7 is formed in the shape shown in FIG. 3 by an electroforming method. As shown in the figure, the tip of the piezoelectric element 22 is bonded to the island-shaped portion 10a of the flattening layer formed at the tip of the island-shaped portion 7a of the wall member 7. The island portions 7a and 10a are designed to be slightly smaller than the projection surface of the ink chamber 5, as shown in FIG.

In the ink droplet ejection operation, an electric field is applied from the control substrate 13 to the positive electrode 41 and the negative electrode 42 of the piezoelectric element 22 through the lead frame 25 and the wiring pattern 24 in accordance with the print signal in FIG. The piezoelectric element 22 to which the electric field is applied tends to contract in the longitudinal direction (vertical direction in the figure). At this time, the lower half of the piezoelectric element 22 is fixed to the fixed base 21 held by the head frame 11 and cannot be contracted and displaced. On the other hand, the upper half of the piezoelectric element 22 contracts and displaces without being constrained by other constraints, and the contracting force pulls the elastic member 8 via the flattening layer 10. Flattening layer 1
The thin metal plate 6 of the elastic member 8 pulled by the piezoelectric element 22 through 0 bends downward, and as a result, the volume of the ink chamber 5 expands. When the ink chamber 5 expands, the ink 51 flows from the reservoir 4 through the ink supply port 3a. Then
When the electric field of the piezoelectric element 22 is released, the piezoelectric element 22 expands to its original length and compresses the ink chamber 5. An ink droplet is ejected from the nozzle 2 with this pressure. The island-shaped portion 10a of the flattening layer and the elastic member 8 that transmit the displacement of the piezoelectric element 22 to the ink chamber 5.
As described above, since the island-shaped portion 7a is slightly smaller than the projected surface of the ink chamber 5, the ink chamber 5 is uniformly pressurized and depressurized while leaving the flexible portion of the thin metal plate 6. The above is the ink droplet ejection operation.

On the other hand, in addition to the above embodiments, for example, FIG.
As described above, the flattening layer 14 can be formed on the piezoelectric element 22 side. Further, as shown in FIG. 10, the flattening layer 16 may be formed on the piezoelectric element 22 side and the flattening layer 15 may be formed on the elastic member 8 side.

Next, a method of manufacturing the flattening layer 10 will be described with reference to FIGS. 5, 6, 7, and 8. FIG. 5 shows a method of manufacturing the bonded body 70 of the nozzle substrate 1 and the nozzle substrate side 3 a of the cavity forming substrate 3 in the order of steps. First, a photosensitive resin film (hereinafter referred to as a dry film) 61 is laminated on the nozzle substrate 1 processed by pressing or electroforming as described above. Next, a glass mask 62 having a pattern exposed to ultraviolet rays and a pattern not exposed to ultraviolet rays is arranged on the dry film 61 side, and ultraviolet rays are irradiated to perform exposure. After exposure, on the dry film 61,
Light-cured portions and unexposed portions are formed. Next, the unexposed portion is removed by performing development, and the bonded body 70 of the cavity forming substrate 3a and the nozzle substrate 1 is completed.

On the other hand, FIG. 6 shows a method of manufacturing a bonded body 80 of the elastic member 8 and the elastic member side 3b of the cavity forming substrate 3 in the order of steps. First, the dry film 71 is laminated on the elastic member 8 processed by the electroforming method as described above. Next, similarly to the above, the glass mask 72 is placed on the dry film 71 side, and ultraviolet rays are irradiated to perform exposure.
After the exposure, a portion cured by the exposure and an unexposed portion which is not exposed are formed on the dry film 71. Next, the unexposed portion is removed by performing development, and the bonded body 80 of the cavity forming substrate 3b and the elastic member 8 is completed.

FIG. 7 shows a method for manufacturing a completed cavity forming substrate 90 by fusing both the joined body 70 of the cavity forming substrate 3a and the nozzle substrate 1 and the joined body 80 of the cavity forming substrate 3b and the elastic member 8. Show. Fusing is 15
It is carried out at a temperature of 0 to 170 ° C. At this time, the surface of the dry film is fused by heat, but the crush amount of the dry film is determined by the pressing force and time. Further, it is important that the pressure is evenly applied in order to reduce the variation in the crush amount of the dry film. However, in reality, the crushing amount is likely to be unbalanced depending on the presence or absence of fusion-bonded meat on the dry film, that is, the pattern arrangement. In addition, warpage is likely to occur in the process of heating from the time of fusion and cooling to room temperature. For the above reasons, the thickness h of the cavity forming substrate completed body 90 tends to vary during manufacturing. This causes the gap between the piezoelectric element 22 and the elastic member 8 to vary as described above.
Is not efficiently transmitted to the ink chamber 5, resulting in unstable ejection characteristics of ink droplets. Therefore, it is important to provide the flattening layer 10.

FIG. 8 shows a process of forming the flattening layer 10. 90 is a completed cavity forming substrate. First, on the elastic member 8 side of the cavity forming substrate completed body 90,
A fluid material 10b forming the flattening layer 10 is applied.
If necessary, the elastic member 8 may be subjected to a primer treatment before the application for the purpose of improving the adhesion. Examples of the fluid substance 10b include a photosensitive resin, a thermosetting resin, and a room temperature curable resin, and in particular, a polyester resin, an acrylic resin, an epoxy resin, an APR resin, and various resists are used. In this embodiment, a polyester resin (photosensitive resin) which is relatively easy to handle and inexpensive is used. Next, a PET film for the purpose of releasability is provided at least on the fluid substance 10b at a portion provided with a gap member (not shown) for separating a certain distance from the most convex portion of the elastic member 8. Place on a wide area. Next, the glass mask 91 (reference flat plate of claim 4) is placed on the film. A pattern is arranged on the glass mask 91 for the purpose of selectively forming an exposed portion and an unexposed portion with respect to the fluid substance 10b. Further, at least one surface of the glass mask on the film side is polished to have a flatness of 0.1 to 0.1.
It is finished to about 0.2 micron. After placing the glass mask 91, exposure is performed by irradiating ultraviolet rays having a wavelength of about 300 to 400 nm. Since the fluid substance 10b is hard to be exposed to visible light of 400 nm or more, a dark room or special equipment is not required. After the exposure,
The fluid substance 10b is divided into two parts, the exposed portion undergoes a chemical change and is hardened, and the unexposed portion maintains a fluid state.
In this state, the fluid portion in the unexposed portion is removed. Since the fluid substance 10b can be easily removed with a weak alkaline liquid or water, the work is safe and harmless. Further, post-exposure can be carried out as necessary for the purpose of further reliably curing the cured portion. By the above method, the flattening layer 1
0 can be formed, and the flattening layer 10 can be formed with a high degree of precision in terms of plane accuracy that is similar to that of the glass mask 91. In addition to the thermosetting resin and the room temperature curable resin, the highly accurate flattening layer 10 can be similarly formed in addition to the present embodiment.

The flattening layer 10 formed as described above.
Is lighter due to the characteristics of the resin, the expansion / contraction force of the piezoelectric element 22 is hardly lost, and the ejection response frequency can be improved. In addition, by providing the flattening layer 10, it is possible to achieve a higher total accuracy than when the elastic member 8 is scraped for the purpose of improving the flatness accuracy.

[0021]

As described above, the elastic member including the thin metal plate having a very thin thickness and the wall member laminated with the thin plate while preventing the ink bleeding, and the flattening of the resin on at least one of the piezoelectric elements are provided. By providing the chemical layer, the piezoelectric element can be positioned with high accuracy in the displacement direction. In addition, the flattening layer is formed by selectively hardening the reference flat plate after at least two members have been joined, so that the warp and deviation of each member are corrected by the flattening layer, and the flattening layer is formed. A highly accurate plane can be created as the contact surface. Moreover, since the gap between the piezoelectric element bonding surfaces is stable, the adhesive strength is also stable, and the protrusion of the adhesive can be suppressed. As a result, the displacement of the piezoelectric element can be accurately and efficiently transmitted to the ink chamber. Efficiently transmitting the displacement of the piezoelectric element to the ink chamber not only stabilizes the ejection characteristics of the ink droplets, but also enables downsizing and high density of the recording head. Further, by using a photosensitive resin which is an insulating member for the flattening layer, it is possible to easily and inexpensively handle the manufacturing method at the same time, and at the same time, the elastic member and the piezoelectric element are electrically insulated from each other, so that the electric field is applied to the ink. Is prevented and adjacent piezoelectric elements are also insulated, so that the degree of freedom of electric wiring is increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention.

FIG. 2 is a partial sectional view of the above embodiment.

FIG. 3 is a partial perspective view of the above embodiment as seen from below.

FIG. 4 is a plan view of the above embodiment as seen from directly above.

FIG. 5 is a diagram showing one manufacturing method of one embodiment of the present invention.

FIG. 6 is a view showing one production method of the above-mentioned embodiment.

FIG. 7 is a view showing one production method of the above-mentioned embodiment.

FIG. 8 is a view showing one production method of the above-mentioned embodiment.

FIG. 9 is a partial cross-sectional view of another embodiment of the present invention.

FIG. 10 is a partial cross-sectional view of another embodiment of the present invention.

FIG. 11 is a partial cross-sectional view illustrating the problem of the conventional example.

FIG. 12 is a partial cross-sectional view illustrating the effect of the present invention.

[Explanation of symbols]

1, 1a Nozzle substrate 3, 3a Cavity forming substrate 5 Ink chamber 6 Metal thin plate 7 Wall member 8, 8a Elastic member 9a, 9b, 9c, 9d, 9e, 9f Flow hardening state of adhesive 10, 10d, 10e, 10f, 14, 15 and 16 Flattening layer 10b Fluid material 11 Head frame 12 Mounting hole 21 Fixing plate 22, 22a Piezoelectric element 23 Common plate 24 Wiring pattern 25 Lead frame 31 Ink supply pipe 32 Ink connection port 33 Ink connection port 51 Ink 60 Head frame plane 61, 71 Photosensitive resin film (dry film) 62, 72 Glass mask 90 Cavity forming substrate completed body 91 Glass mask (reference plate)

Claims (4)

[Claims] 1. An ink jet head for displacing an elastic member forming a part of an ink chamber by a piezoelectric element to increase ink pressure in the ink chamber and eject ink droplets from a nozzle, wherein the elastic member and the piezoelectric element are combined. An inkjet head having a flattening layer on at least one side. 2. The ink jet head according to claim 1, wherein the flattening layer is made of a photosensitive resin. 3. The ink jet head according to claim 1, wherein the member for providing the flattening layer forms the flattening layer after at least two members are joined. 4. The flattening layer provides a curable substance having fluidity between a reference flat plate side and the elastic member or the piezoelectric element, and then selectively cures the curable substance. The method of manufacturing an inkjet head according to claim 3, wherein the inkjet head is formed.