JPH07276627A - Inkjet head and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to propose an inkjet head that can achieve high density, high ink droplet ejection speed, and is excellent in reliability and mass productivity, and a manufacturing method thereof. A piezoelectric transducer 1 in which a plurality of pressure chambers 22 and at least a part of the pressure chamber 22 and a nozzle opening 13a communicating with each of the pressure chambers 22 are formed, and a thin portion and one end thereof are fixed to a base.
Is provided with a vibrating plate 20 with which the other end of the vibrating plate abuts, and the piezoelectric transducer 1 is expanded and contracted to eject ink droplets from the nozzle opening 13a. The vibrating plate 20 is made of a resin film thin portion 20a. And a metal thin film 2 formed in close contact with the film
0c and the projection 20b formed by depositing metal on the metal thin film 20c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density ink jet head used in an ink jet recording apparatus for forming an ink image on a recording medium such as recording paper by ejecting ink droplets according to a print signal and a method for manufacturing the same. More specifically, the present invention relates to a configuration of a vibrating plate that forms one wall surface of a pressure chamber for ejecting ink droplets and transmits expansion and contraction of a piezoelectric transducer to the pressure chamber, and a manufacturing method thereof.

[0002]

2. Description of the Related Art According to Japanese Patent Laid-Open No. 58-119870 and Japanese Patent Laid-Open No. 58-198772, a vibration plate forming a pressure chamber is provided at the other end of a piezoelectric transducer having one end fixed to a base. It is configured to abut via an island-shaped protrusion (referred to as a leg portion in the above-mentioned publication), and is configured to cause ink in the pressure chamber to fly as droplets from the nozzle opening due to expansion and contraction of the piezoelectric transducer.

However, none of these publications proposes a concrete structure or manufacturing method of the diaphragm, and since the legs have a complicated structure that engages with the bearings, they can be made compact and highly densified. Not only is it difficult to assemble, but it is extremely difficult to assemble a large number of legs and bearings with high precision.

As an example showing the structure of the diaphragm, Japanese Patent Laid-Open No. Hei.
No. 15555, a displacement generating element is a bimorph.
Alternatively, as shown in FIG. 18, a unimorph-type piezoelectric transducer using flexural deformation is used, but as shown in FIG. 18, a thin portion 61a made of silicon having a thickness of 1.8 μm (referred to as a diaphragm in the publication) and an oxide having a thickness of 100 μm An example is disclosed in which a protrusion 61b made of silicon is formed on the diaphragm 61 and the protrusion 61b and the piezoelectric converter 60 are brought into contact with each other.

Further, as a second example, in the same publication, an electroforming method is used on a thin portion 61a having a thickness of about 1 to 10 μm and made of a metal such as nickel, stainless steel, iron, copper or silver. There is disclosed a method in which the protrusion 61b is formed by and the protrusion 61b and the piezoelectric converter 60 are brought into contact with each other.

Further, as a third example, in the same publication, a thin portion 6 made of an organic material film having a thickness of 50 μm is also used.
An example is disclosed in which a protrusion 61b whose material and method thereof are not specified is fixed on 1a and the protrusion 61b and the piezoelectric transducer 60 are brought into contact with each other.

On the other hand, as a fourth example, JP-A-3-19074
In Japanese Patent No. 4 publication, as shown in FIG.
A piezoelectric transducer 70 in which a dummy layer of about 00 μm is formed is shown, and a thin portion 73a made of glass or stainless having a thickness of about 50 μm and having no protrusion (referred to as a cover plate member in the above publication). ), An example of fixing with an epoxy adhesive is disclosed.

Further, as a fifth example, JP-A-5-1696.
Japanese Patent No. 51 discloses a vibrating plate having a thin portion made of a thin metal plate and a protrusion made of a resin material, and a piezoelectric transducer that is in vertical contact with the protrusion.

[0009]

However, even with these conventional examples, the following problems occur, and an ink jet head in which the piezoelectric transducer is expanded and contracted at high speed and the pressure chambers are arranged at a high density is realized. It is difficult to do.

Since the piezoelectric transducer of the conventional ink jet head using a polymer resin having a thickness of 50 μm for the thin portion 61a is a flexural deformation type, the displacement amount can be taken out relatively, but the natural frequency related to flexural vibration is Press the diaphragm slowly and slowly. On the other hand, the pressure generating element of the present invention expands and contracts in the axial direction, and the natural frequency related to the expansion and contraction is very high.
It has a high velocity displacement and enables a high ink droplet ejection velocity. The displacement amount is several μm.

Therefore, in a diaphragm using a polymer resin having a low Young's modulus and being 20 times thicker than the displacement amount, the high-speed displacement is absorbed by the deformation of the resin, and ink droplets are ejected. Sufficient pressure and volume change cannot be generated in the pressure chamber 64.

The same problem occurs when a resin material is used for the protrusions, and a sufficient discharge speed and discharge amount cannot be obtained depending on the thickness of the protrusions, and the transmission efficiency is small due to a slight variation in the thickness of the protrusions. Changes and the ejection characteristics vary.

The silicon or metal film proposed as a thin portion cannot endure repeated bending deformations of hundreds of millions to billions of times, resulting in fatigue failure. Particularly in a high-density head, the thin portion that deforms has a size of only a few tens of μm, while in a high-density head, it is necessary to increase the displacement of the piezoelectric transducer, so the stress applied to the thin portion is extremely large. Become. That is, these materials are not suitable for a diaphragm for an inkjet head which is deformed at a high speed and a total of hundreds of millions of times or more. The thickness of the thin portion is limited to 2 μm in consideration of defects such as pinholes. However, with a metal material or a silicon material having a thickness of 2 μm or more, there is a problem that the flow path substrate itself bends because the bending rigidity is too high in the high-density head that the present inventors intend.

Japanese Unexamined Patent Publication (Kokai) No. 3-190744 discloses a diaphragm which does not have a protrusion for contacting the piezoelectric transducer. However, this does not determine the contact position of the piezoelectric transducer. If the thin portion 73a is a resin film, the permeated ink vapor directly attacks the piezoelectric transducer, so that a new permeation prevention means needs to be incorporated.

As can be seen from the above publications, a suitable manufacturing method for an ink jet head having excellent ejection characteristics and reliability has not yet been disclosed in detail.

According to the present invention, there is disclosed a structure and a manufacturing method of an ink jet head which solves the above-mentioned problems and is suitable for high density, has a high ink droplet ejection speed and high reliability, and can be easily mass-produced. It is a thing.

[0017]

Therefore, in the present invention, a plurality of pressure chambers, a nozzle opening communicating with each of the pressure chambers, and at least a part of the pressure chambers are formed, and a thin portion and one end are fixed to a base. An ink jet head having a vibrating plate having a protrusion with which the other end of the piezoelectric transducer abuts, and ejecting ink droplets from a nozzle opening by expansion and contraction of the piezoelectric transducer, the vibrating plate being made of a resin film. And a metal thin film formed in close contact with the film, and the projection formed in close contact with the metal thin film by metal deposition. In addition, the problem is solved by an excellent manufacturing method for realizing such a configuration.

[0018]

Embodiments will be described in detail below along with embodiments of the present invention. FIG. 1 is an exploded perspective view of an embodiment of an inkjet head according to the present invention. A mounting hole 11 penetrating through the frame 10 supports a plate member 5, which will be described later, in order to position the piezoelectric transducer 1 in the X-axis and Y-axis directions. The longitudinal end surface of the piezoelectric converter 1 is joined to a protrusion 20b formed on the vibration plate 20. Nozzle opening 1
The flow path is formed by sequentially stacking the plate-shaped nozzle substrate 13 having 3a, the vibration plate 20, and the flow path substrate 12.

FIG. 2 is a partial sectional view of an ink jet head to which this embodiment is applied. The pressure chamber 22 is formed by the nozzle substrate 13 having the nozzle openings 13 a, the flow path substrate 12, and the vibration plate 20. The vibration plate 20 is composed of a laminated body of an inorganic thin film 21, a resin thin portion 20a, a metal thin film 20c and a rigid protrusion 20b made of metal. Inorganic thin film 21
As will be described later, has a function of mainly preventing a change in physical properties due to permeation of the ink into the resin-made thin portion 20a. 23
Is a thick portion formed at the same time as the protrusion 20b.

The ink reservoir (not shown), the ink supply pipe 14, the ink communication port 16 and the pressure chamber 22 are in communication with each other, and the nozzle opening 13a is filled with the water-soluble ink 6 from the ink reservoir. The piezoelectric converter 1 is fixed to the frame 10 with an adhesive 99 via the plate member 5.

The frame 10 and the thick wall portion 23 are joined by an adhesive 24 having a thickness of several μm to several tens of μm, and the piezoelectric transducer 1
The protrusions 20b are joined by an adhesive 24 having a thickness of several μm to 7 μm.

Wirings for driving the piezoelectric converter 1 are the first wiring 30a, the second wiring 30b, the first conductive film 5a on the plate member, the first conductive film 4a on the converter, and the first conductive film 4a. Two
Of the conductive film 4b. The thin portion 20a is an electrically insulating material and can easily provide insulation between the electrode 4a of the piezoelectric transducer 1 and the ink 6.

In such a structure, the principle of ejecting ink droplets is as shown in FIG. FIG. 3A shows a standby state. As shown in FIG. 3 (b), the piezoelectric transducer 1 is used prior to ejection.
When a voltage is applied to the piezoelectric transducer 1, the piezoelectric transducer 1 contracts so as to pull the diaphragm 20. This electric field is released and the piezoelectric transducer 1
As the electric charge stored in the pressure chamber 22 is rapidly discharged, the piezoelectric transducer 1 is restored at a high speed as shown in FIG.
The pressure of the ink 6 inside is increased to eject the ink droplet 6a from the nozzle opening 13a, and the piezoelectric converter 1 returns to the standby state again.

FIG. 4 is a perspective view showing an embodiment of the ejection pressure generating means of the ink jet head according to the present invention.

The pressure generating means for ejecting the ink 6 as droplets is the piezoelectric converter 1, which is a multi-layer in which piezoelectric bodies 2 and conductive materials 3a and 3b (internal electrodes 3a and 3b) are alternately stacked. It is a structure. Conductive material 4 for the piezoelectric transducer 1
a and 4b (external electrodes 4a and 4b) are formed, and the external electrode 4a is electrically connected to the internal electrode 3a, and the external electrode 4b is electrically connected to the internal electrode 3b. The rear side of the piezoelectric transducer 1 is joined to the plate member 5, and the front end is joined to the protrusion 20b of the diaphragm 20 as described above.

By using such a vertical and laminated vibrator that expands and contracts in the axial direction, it is possible to obtain a high displacement speed and a required displacement which cannot be obtained by flexural deformation, and at a low voltage, resulting in a high displacement. It enables an ink jet head with high ejection speed and high density.

FIG. 5 is a perspective view of a main part of an ink jet head to which an embodiment of the present invention is applied, as seen from below.

According to the development example of the present inventors, the pressure chamber 22
Has a length (11 in FIG. 2) of 1.5 mm, the depth of the pressure chamber 22 (h1 in FIG. 2) is 0.2 mm, and the width of the pressure chamber 22 is 0.1 mm.
mm, the thickness of the thin portion 20a is 4 μm, the length of the protrusion 20b (12 in FIG. 2) is 1.3 mm, and the height of the protrusion 20b (see FIG. 2).
The middle h2) was 40 μm, the width of the protrusion 20b (w2 in FIG. 5) was 30 μm, and the array density of the pressure chambers 22 was increased to 180 (180 dpi) per inch. By increasing the thickness of the protrusion 20b, sufficient rigidity is secured.

Polyimide is used as the thin portion 20a, chromium having a thickness of 0.15 μm is used as the inorganic thin film 21, copper having a thickness of 0.2 μm is used as the metal thin film 20c, and protrusions 20 are used.
Nickel was used as b. Further, the dimensions of the piezoelectric transducer 1 are: width 80 μm, array pitch 180 dpi, thickness of laminated piezoelectric transducer 0.5 mm, distance between internal electrodes (thickness of internal piezoelectric body) 20 μm, active length (actually The length of the portion for displacement operation) was set to 5 mm. With this size, the natural frequency of expansion and contraction of the piezoelectric transducer is 120 KHz, and the external electrode 4a
When a voltage of 30 V is applied between 4 and 4b and a discharge is performed for 8 μs, a displacement of 1.5 μm can be obtained at the tip of the piezoelectric converter 1, and 0.1 μg from the nozzle opening having a diameter of 40 μm, 1
An ink droplet ejection rate of 0 m / sec was obtained.

When the density of the ink jet head is increased, the size of the pressure chamber is naturally limited, so that the area of the protrusion 20b cannot be increased at the same time. Further, in order to maintain the durability of the vibration plate 20 which is repeatedly deformed several hundreds of millions of times, it is necessary to secure the region of the thin portion 20a above a certain level.
Although the area of the protrusion 20b cannot be easily enlarged,
In the present invention, the thin portion 20a is as flexible as possible and the protrusion 20b is as rigid as possible, so that the protrusion 20b can be designed so as to press the pressure chamber 22 as widely as possible compared to the tip of the piezoelectric transducer 1. It has a high density and a large ejected ink droplet volume and ejection speed. Furthermore, by using a thin resin material, it was possible to secure durability of 2 billion operations or more.

Incidentally, it is an effective measure to secure the volume of the ink droplet that the protrusion 20b is made rigid, that is, a material having high rigidity is used and the protrusion is formed thick in the displacement direction. That is, it was confirmed that the manufacturing method according to the present invention, in which a metal material is used as the protrusion 20b as in the present invention, and the metal is deposited so that the protrusion 20b can be formed thick, is effective as a manufacturing method.

Further, the inventors of the present invention have found out as a result of conducting various experiments. When an adhesive is interposed between the thin portion 20a and the rigid island-shaped protrusion 20b, the thickness of the adhesive is increased. As a result, it was found that it is difficult to suppress variations in ejection characteristics because the displacement transmission efficiency changes. Transmitting the displacement of the piezoelectric transducer to the pressure chamber is such a delicate operation that it is essential to fix the thin portion 20a and the protrusion 20b directly. However, the present invention has solved that problem.

The metal thin film 20C enhances the adhesion strength between the resin film 20a and the protrusion 20b. That is, the protrusion 20
b is made thick to have high rigidity, while metal thin film 2
0C is intended to improve the adhesion between the resin film and the protrusion. Therefore, productivity can be improved by using a thin film forming means having excellent adhesion strength to secure the adhesion strength and using a means having a high formation speed to form the protrusion 20b.

FIG. 6 is a plan view showing an embodiment of the vibration plate 20 of the ink jet head according to the present invention, and FIG. 7 is a flow path substrate 1.
It is a top view which shows the Example of 2.

The flow path substrate 12 is provided with a plurality of pressure chambers 22 arranged in two rows and a common ink chamber 25 communicating with the pressure chambers 22, and can be precisely formed of a photosensitive resin material or silicon. it can. The diaphragm 20 includes a plurality of protrusions 20b arranged in two rows and a thin portion 20a surrounding the protrusions 20b.
And surrounding thick part 23, thin part 26 which is elongated and has a slightly larger area
Consists of. The flow path substrate 12 and the vibration plate 20 are overlapped and bonded using the positioning reference holes 29 and 27, and the projection 20b of the vibration plate is in the center of the pressure chamber 22 and the thin part 26 is in the common ink chamber 25. Therefore, they are located on the ink supply side of each pressure chamber. The round hole 28 is an ink inlet port to the common ink chamber 25 that communicates with the ink reservoir.

The thin portion 26 absorbs the pressure transmitted from the pressure chambers to prevent crosstalk between the pressure chambers, and improves the ink supply capability as a buffer when ink is supplied. According to the present invention, since the thin portion 26 is a resin thin film, it is possible to provide the above-mentioned functions with a small area, and the head can be miniaturized. Further, it has excellent durability despite the fact that a large negative pressure generated when sucking through the nozzle during purging acts. Also, thin portion 26 and thin portion 2
Since 0a is formed of an integral resin film and covers the pressure chamber and the common ink chamber, there is no problem of ink leakage.

A manufacturing method that realizes the above-described configuration of the present invention will be described below.

FIGS. 8A to 8F and FIGS. 9A to 9E show an embodiment of the first manufacturing method of the present invention.

First, a laminated plate is formed by laminating a thin uniaxially or biaxially stretched film 80a with an adhesive on one surface of a base plate 80 (FIG. 8A) having a thickness of 20 μm to 500 μm ( FIG. 8 (b)). As the material of the base plate 80, a polymer material or a metal material can be used, but PET is preferable from the viewpoint of laminating property and peeling property described later.
A resin film such as (polyethylene terephthalate) or polyphenylene sulfide (PPS) is preferable because of its flexibility and smoothness, and has a thickness of 30 μm to 150 μm.
μm is preferred. The stretched film 80a constitutes the thin portion 20a and the thin portion 26 of the vibration plate described above, and the thickness thereof is determined from the design related to ink droplet ejection and strength. In the high-density inkjet head as disclosed in the present invention, the stretched film 80a has a thickness of 2 μm to 10 μm.
The present inventors used a stretched film of PPS having a thickness of 3 μm to 5 μm.

Since the stretched film 80a contacts not only the ink but also various chemicals in the head assembling process, a material having corrosion resistance to these liquids is selected. As a result of evaluation by the present inventors, as a material,
PPS (polyphenylene sulfide), polyamide imide (PAI), polyethylene terephthalate (PE
T), polyethylene naphthalate (PEN) and polyimide (PI) were suitable and available stretched films.

The stretched film is excellent in thickness accuracy and strength due to its own characteristics, and above all has no pinholes.

Next, the metal thin film 8 is formed on the stretched film 80a.
3 is formed (FIG. 8C). The forming means is a well-known means such as vapor deposition, sputtering and CVD. Material is nickel,
It is made of any one of gold, chromium, titanium, copper, etc., or a laminate of these materials, and the material is appropriately selected according to the film material and the surface treatment state. According to the adhesion strength test result of the metal thin film, copper or chromium was suitable.

Next, after applying the photoresist 81, the photoresist 81 is irradiated with ultraviolet rays through the photomask 82 (FIG. 8D). The photoresist 81 is exposed,
It is selectively formed and removed through a developing process (FIG. 8E). Next, the metal 80b is deposited (metal plated) on the photoresist removal portion 81b using the metal thin film 83 as an electrode to form the protrusion 20b and the thick portion 23 of the diaphragm (FIG. 8 (f)).

After removing the photoresist 81a, the base plate 80 is peeled off and washed to complete the vibration plate 20 (FIG. 9A).

In FIG. 9A, the metal thin film 83 has a thin portion 80.
It has been found that the metal thin film of the single layer portion, which is still formed on the entire surface of a, but has only a thin portion without a protrusion or a thick portion, is likely to be cracked or floated due to ink penetration. Therefore, it is preferable to remove the metal thin film 83 by etching as shown in FIG.

In the above-described manufacturing example, the outer dimensions of the diaphragm 20 are smaller than 10 mm × 10 mm,
Actually, a large number of diaphragms 20 are formed on one base plate 80, and after separating each one, the base plate 80 is peeled off, or after peeling off the base plate 80, each diaphragm 20 is divided. To do.

On the other hand, the flow path substrate 12 can be precisely formed by using a photosensitive resin material or a silicon material. With the photosensitive resin material, the flow path can be formed through a so-called photo process. Further, in the silicon substrate, the flow path can be precisely formed by anisotropic etching.

The formed flow path substrate 12 and the vibrating plate 20 are joined in a state of being accurately positioned (FIG. 9 (c)), and the nozzle substrate 13 is further joined to the other surface of the flow path substrate 12 (FIG. 9 (c)). 9 (d)).

The reference hole 27 and the ink inlet hole 28 shown in FIG. 6 use the thick portion 23 made of metal as a mask.
It is formed by ablation processing by laser light irradiation from the thick portion 23 side.

Next, the thick portion 2 of the diaphragm 20 is attached to the frame 10.
3 (FIG. 9 (e)), and then the plate member 5 is fitted into the through hole 11 of the frame 10 to insert the pressure generating portion, and the protrusion 20b of the vibration plate 20 and the piezoelectric transducer 1 are connected. The tip surfaces are brought into contact with each other (Fig. 2 or Fig. 9e).

10 (a) to 10 (c) show an embodiment of the second manufacturing method of the present invention.

First, a resin film, for example, a stretched film 9
0a is prepared (FIG. 10 (a)), and the metal thin film 93 is provided on one side thereof.
Are formed (FIG. 10B). Next, it is laminated on the base plate 90 to form a laminated body (FIG. 10 (c)). Next, a photoresist is formed on the metal thin film 93, and the subsequent steps are as described above with reference to FIGS.

FIGS. 11A to 11C show a third manufacturing example. That is, in this embodiment, first, the metal thin film 103 is formed on one surface of the resin film, for example, the stretched film 100a, and the inorganic thin film 100c that functions as the inorganic thin film 21 shown in FIG. 2 is formed on the other surface (FIG. 11 (a)). )). Next, the surface of the inorganic thin film 100c is placed inside and laminated with the base plate 100 (FIG. 11B). The subsequent steps are as described above. The diaphragm 20 completed according to this embodiment is shown in FIG.
As shown in FIG. 1c, the inorganic thin film 10 is formed on one surface of the thin portion 100a.
0c, and the inorganic thin film 100c is located on the ink contact surface.

The inorganic thin film 100c prevents the diaphragm 20, particularly the thin portion 100a (20a and 26 in FIG. 6) from being deteriorated and the material constant from being changed, and the metal thin film 103 and the thin portion 100a are prevented from permeating the ink composition. Prevents a decrease in adhesion strength.
The thickness of the inorganic thin film 100c is preferably 0.1 to 0.5 μm so that the function of shielding the ink composition is not impaired, pinholes are particularly small, and flexibility as a thin portion is not impaired. As the inorganic thin film, a ceramic material, a glass material, a metal material such as chromium, titanium, gold, nickel or platinum can be used, and a metal material is preferable in terms of strength and reliability. According to the long-term contact test with ink, titanium 0.1
.About.0.3 .mu.m, or chromium 0.1 to 0.3 .mu.m, or chromium 0.05 .mu.m and nickel 0.1 to 0.
It has been obtained that the film having a thickness of 2 μm has the best adhesion strength.

The inorganic thin film 100c (thin film 21 in FIG. 2)
Is not necessarily essential for achieving the object of the present invention,
By selecting the ink, the ink composition, the material of the thin portion, and the allowable value for designing the ejection characteristics, it is possible to omit it when there is no problem in practical use, and such an embodiment has already been described.

Regarding the method of forming the protrusions, it is impossible to dispose the protrusions at a high density when forming them by etching, and the desired shape cannot be obtained when the thickness is increased. If so, the protrusion 20b having a uniform and sufficient thickness can be formed in the high-density head.

FIG. 12 is an enlarged cross-sectional view of the contact portion between the protrusion 20b and the piezoelectric converter 1, showing how the shape of the protrusion 20b changes depending on the thickness of the photoresist (shown by the broken line). Shows. When the photoresist thickness is small,
As shown in FIG. 2 (b), the upper portion of the protrusion 20b spreads like a mushroom, and the upper surface joined to the piezoelectric transducer 1 has an arc shape.

When the upper surface spreads, the adjacent protrusions 20b come closer to each other. Further, when the piezoelectric transducer 1 and the protrusion 20b are joined, if the piezoelectric transducer 1 is displaced as shown by the two-dot chain line in the figure, the adhesive is connected in a bridge shape at the narrow arrow portion. Further, if the upper surface of the protrusion has an arcuate shape, the contact with the piezoelectric transducer is not stable.

On the other hand, as shown in FIG. 12 (a), when a photoresist (shown by a broken line) is formed up to or near the height of the protrusion, the upper surface of the protrusion 20b does not spread and the upper surface becomes flat. The above-mentioned problems can be solved, and as a result, the protrusion arrangement interval can be reduced, and a high-density head can be realized.

13 (a) to 13 (e) show an embodiment of the fourth manufacturing method of the present invention.

First, a base plate 120 made of metal or ceramics having a thickness of 0.01 to 0.3 mm is prepared (FIG. 13A). As a material, copper, nickel, stainless steel, silicon, or the like, and a resin plate can be used depending on the case. A polymer resin 120a is formed on one of the surfaces of the base plate 120 and baked (FIG. 13).
(b)). The thickness is determined by the ink droplet ejection and the strength design of the vibrating plate, but is generally in the range of 2 to 10 μm, and the present inventors set it to 4 μm. As a film forming method, a vacuum film forming method, a dipping method, a roll coating method, a spinner coating method, a spray method, a casting method and the like are possible. Materials for the polymer resin include polyimide (PI) resin and polyetherimide (P
EI) resin, polyamide imide (PAI) resin, polysulfone (PSF) resin, polyether sulfone (PE)
S) resin, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin, polyphenylene sulfide (PPS) resin, polyolefin (AP
O) resin, polyethylene naphthalate (PEN) resin,
An aramid resin can be mentioned. Possible film forming methods differ depending on the material, but a roll coating method and a casting method, which can easily form a thin film having a smooth and uniform thickness, are preferable.

Further, a polymer resin material capable of withstanding various chemicals and inks used in the manufacturing process and a film forming method thereof are adopted.

The metal thin film 1 is formed on the polymer resin layer 120a.
23 is formed (FIG. 13C). The forming means is a well-known means such as vapor deposition, sputtering and CVD. As the film material, chromium, nickel, copper, gold, titanium, or two kinds selected from these are laminated. A photoresist is formed on the metal thin film 123, and the photoresist is irradiated with ultraviolet rays through a photomask to selectively expose the photoresist, and then developed. The photoresist is selectively formed and removed through the processes of exposure and development. Next, a metal is deposited (metal plated) on the metal thin film 123 in the photoresist removal portion to form the protrusion 20b and the thick portion 23 of the diaphragm. Finally, the photoresist is removed, and then the base plate 120 is dissolved and removed by etching to complete the required vibration plate 20 (FIG. 13).
(d)).

If necessary, an inorganic thin film 21 made of metal or ceramics is formed on the ink contact surface of the vibration plate 20 (FIG. 13 (e)). The inorganic thin film 21 prevents deterioration of the diaphragm 20, especially the thin portion 20a, and changes in the material constants, and also prevents a decrease in the adhesion strength between the protrusion and the thin portion due to the permeation of the ink composition.

FIGS. 14A to 14E, FIGS. 15A to 15E and FIGS. 16A and 16B show a fifth embodiment of the manufacturing process according to the present invention.

First, a silicon wafer 130 having a crystal orientation (110) plane is prepared (FIG. 14A). Silicon oxide films (SiO ₂ films) 138 and 139 are formed on the surface using a thermal oxidation furnace (FIG. 14B). Silicon oxide film 139
A resin layer 130a is formed on top of this (FIG. 14 (c)). As a forming method, a vacuum film forming method, a dipping method, a roll coating method, a spinner coating method, a spray method, a casting method and the like can be used. Polyimide (P
I) resin, polyetherimide (PEI) resin, polyamideimide (PAI) resin, polysulfone (PSF) resin, polyethersulfone (PES) resin, polyetherketone (PEK) resin, polyetheretherketone (PEEK) resin , Polyphenylene sulfide (PP
Examples thereof include S) resin, polyolefin (APO) resin, polyethylene naphthalate (PEN) resin, and aramid resin. The film formation method that can be performed differs depending on the material, but a method that can easily form a thin film having a smooth and uniform thickness is preferable.

Next, when a photosensitive resin is used as the resin 130a (for example, photosensitive polyimide resin), a hole 137 for positioning or ink supply is formed by a known photo process (FIG. 14D).

Next, a metal thin film 133 is formed on the resin layer (FIG. 14E), a photoresist 131 is further coated, and the photoresist 131 is patterned (FIG. 15).
(a)). Then, depositing the metal 130b on the metal film 133 is similar to the manufacturing method described above (FIG. 15).
(b)).

After removing the photoresist 131, the silicon oxide film 138 in the portion where the pressure chamber 22 is to be formed.
Is removed (FIG. 15 (c)), and a recess 22 to be a pressure chamber is formed from the other surface of the silicon substrate by etching (FIG. 1).
5 (d)). According to anisotropic etching, vertical (11
1) The pressure chamber 22 composed of the surface can be formed precisely. The metal thin film 133 is removed by etching (FIG. 15 (e)), and finally the oxide film 138 is removed (FIG. 16 (a)). Next, the nozzle substrate 13 is bonded so as to close the pressure chamber (FIG. 16).
(b)). According to this embodiment, the diaphragm 20 and the pressure chamber and the flow passage are integrally formed. Therefore, there are various effects such that the positional relationship between the pressure chamber 22 and the protrusion 130b (20b) is accurate, and the reliability of joining the flow path substrate and the diaphragm is high. Actually, the productivity is further enhanced by forming a large number of the vibrating plate portions and the flow path portions on one silicon wafer and then dividing them by dicing.

FIGS. 17A to 17F show an embodiment of the sixth manufacturing method according to the present invention.

First, a silicon wafer 140 having a crystal orientation (110) plane is prepared (FIG. 17A). Silicon oxide films (SiO ₂ films) 148 and 149 are formed using a thermal oxidation furnace (FIG. 17B).

Next, an inorganic thin film 146 is thinly formed on one surface of the silicon wafer 140 (FIG. 17C). The forming means is vapor deposition, sputtering, CVD or the like. The film material is chromium, nickel, copper, gold, titanium, or a laminate of two of these. The inventors obtained a stronger adhesion by forming a thin film of chromium and then forming a nickel film. A resin layer 140a is formed on the inorganic thin film 146. The subsequent process is as described with reference to FIGS. 14 to 16. FIG. 17F shows a cross-sectional view after the nozzle substrate 13 is bonded.

According to this embodiment, the inorganic thin film 146 can be formed on the ink contact side of the vibration plate (FIG. 17 (f)).

FIG. 14, FIG. 15, FIG. 16 of the above embodiment
And in FIG. 17, between the silicon substrate and the resin layer,
In addition, the thickness between the silicon substrate and the inorganic thin film is 0.1 μm
0.5 μm silicon oxide films 139 and 149 are arranged. The silicon oxide film is not always necessary and can be omitted. However, it has been found that when forming the pressure chamber, it is very useful for protecting the diaphragm from the alkaline etching solution containing KOH as the main composition used for anisotropic etching. Therefore, the placement of the silicon oxide film is a very important point for realizing stable manufacturing.

In any of the above embodiments, the thin portion 26 (FIG. 6) located in the common ink chamber 25 is integral with the thin portion 20a which has already been described, and is formed in the same step as the thin portion 20a. Therefore, it is excellent in terms of quality and cost.

It has already been explained that the reference hole 27 and the circular hole 28 for supplying ink to the common ink chamber in FIG. 6 are formed by ablation processing by an ultraviolet laser.

In the case of having an inorganic thin film (100c in FIG. 11), the resin film and the inorganic thin film are simultaneously drilled by laser processing.

It has already been described that when the photosensitive resin material is used as the resin material, the reference hole 27 and the round hole 28 can be formed by a photo process. However, when the inorganic thin film 146 is formed as in the embodiment of FIG. 17, the inorganic thin film remaining in the holes is preferably removed by laser processing.

In each of the above embodiments, nickel is the most suitable material for forming the protrusion 20b and the wall pressure portion 23, but other materials such as gold, chromium and copper are also possible.

Further, the thin portion 20a of the diaphragm 20 manufactured in each of the above-described embodiments needs to be in a stretched state without sagging. Because the slack absorbs the pressure and volume change generated in the pressure chamber, the slack reduces the ink droplet ejection speed and the ejection amount. Even when the resin film is in contact with the ink and swells, it is necessary to stretch the thin portion 20a.

Therefore, in the above-mentioned first to third manufacturing methods, a method of laminating on the base plate while applying tension to the stretched film is adopted.

In addition, in the fourth to sixth manufacturing methods, it is known that active tension application can be achieved by optimizing the resin material and the solvent composition, the film forming conditions of the resin material, and the subsequent firing conditions. .

The ratio of the resin film alone or the resin film with an inorganic thin film stretched by contact with ink is defined as a
%, When the base plate 80 of FIG. 8 (b), the base plate 120 of FIG. 13 (b), or the silicon substrate of FIG. 14 (c), FIG. 17 (d) is removed, the shrinkage ratio of the resin film is b%. At this time, when a <b, the thin portion 20a does not bend.

[0084]

As described above, the ink jet head and the method of manufacturing the same according to the present invention form a plurality of pressure chambers, a nozzle opening communicating with each of the pressure chambers, and at least a part of the pressure chambers. And a vibration plate whose one end is fixed to the base and which has a protrusion with which the other end abuts. The expansion and contraction of the piezoelectric converter ejects ink droplets from the nozzle opening. A thin-walled portion made of a film, a metal thin film formed in close contact with the film, and a metal projection formed in close contact with the thin film and deposited, and a manufacturing method that realizes these configurations. Since the thin part of is a resin film, it can withstand the required deformation and the required number of repetitions, and furthermore, by utilizing its durability, the width of the protrusion can be expanded as much as possible, and the density can be increased and the ejected ink can be larger. Compatibility of drop volume Made possible.

(2) Since the piezoelectric transducer and the thin portion are made of metal, and a material having a low Young's modulus does not exist between the thin portion and the protrusion, the high speed displacement of the piezoelectric transducer is directly applied to the pressure. Transmitted to the room.

(3) By the method of depositing a metal on the resin film via the metal thin film, the protrusion can be formed of a high-rigidity material and thick, and the metal thin film is interposed between the resin film and the protrusion. I got great adhesion.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a configuration of an inkjet head of the present invention.

FIG. 2 is a partial cross-sectional view of the inkjet head of the present invention.

FIG. 3 is a diagram showing an operation of the inkjet head of the present invention.

FIG. 4 is a diagram showing pressure generating means of the inkjet head of the present invention.

FIG. 5 is a partial perspective view of a main part of the inkjet head of the present invention as viewed from below.

FIG. 6 is a plan view showing an embodiment of the diaphragm of the present invention.

FIG. 7 is a plan view showing an embodiment of the flow path substrate of the present invention.

FIG. 8 is a manufacturing process diagram showing an embodiment of the manufacturing method of the inkjet head of the present invention.

9 is a manufacturing process diagram following FIG. 8 showing an embodiment of a method for manufacturing an inkjet head of the present invention.

FIG. 10 is a manufacturing process diagram showing an embodiment of the method of manufacturing the inkjet head of the present invention.

FIG. 11 is a manufacturing process diagram showing an embodiment of the manufacturing method of the inkjet head of the present invention.

FIG. 12 is an explanatory diagram related to the shape of the protrusion of the diaphragm.

FIG. 13 is a manufacturing process diagram showing an embodiment of the manufacturing method of the inkjet head of the present invention.

FIG. 14 is a manufacturing process diagram illustrating an embodiment of the manufacturing method of the inkjet head of the present invention.

FIG. 15 is a manufacturing process diagram following that of FIG. 14, showing an embodiment of a method for manufacturing an inkjet head of the present invention.

16 is a manufacturing process diagram following FIG. 15, showing an embodiment of a method for manufacturing an inkjet head of the present invention.

FIG. 17 is a manufacturing process chart showing an embodiment of the method of manufacturing the inkjet head of the present invention.

FIG. 18 is a diagram showing an example of a conventional inkjet head.

FIG. 19 is a diagram showing an example of a conventional inkjet head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric transducer 5 Plate member 6 Ink 10 Frame 12 Flow path substrate 13 Nozzle substrate 13a Nozzle opening 20 Vibration plate 20a Vibration plate thin part 20b Vibration plate protrusion 20c Metal thin film 21 Inorganic thin film 22 Pressure chamber 23 Vibration plate meat Thick part 25 Common ink chamber 26 Thin part 27, 29 provided in common ink chamber 27 Reference hole 28 Ink introduction hole provided in diaphragm 80, 120 Base plate 80a, 120a, 130a Resin film 83, 123, 133 Metal thin film 130 , 140 Silicon substrate 139, 149 Silicon oxide film

Claims (13)

[Claims] 1. A plurality of pressure chambers, a nozzle opening communicating with each of the pressure chambers, and at least a part of the pressure chambers are formed,
A vibrating plate having a thin portion and a protrusion whose one end is fixed to the base and the other end of which is in contact with the piezoelectric converter is provided, and the vibrating plate is directly deformed by expansion and contraction of the piezoelectric converter to eject ink droplets from the nozzle opening. In an ink jet head for discharging, the vibrating plate is formed by depositing metal by closely adhering to the thin portion formed of a resin film and at least one or more metal thin films formed in close contact with the film and the metal thin film. An inkjet head characterized by comprising. 2. A wall surface of a common ink chamber communicating with the plurality of pressure chambers has a thin portion made of a resin film integral with a resin film forming the pressure chamber, and the projection portion surrounding the thin portion. The inkjet head according to claim 1, wherein the inkjet head is formed of a thick portion formed at the same time. 3. A step of forming a laminate comprising a base plate, a resin film functioning as the thin portion, and a metal thin film on the resin film, a photoresist is coated on the metal thin film, and after exposure and development, selective treatment is performed. A step of removing the resist, a step of depositing a metal functioning as the protrusion on the removed portion using the thin film as an electrode, a step of removing the remaining photoresist and the base plate, and a vibration completed through the above steps. A method for manufacturing an ink jet head, comprising: a step of joining a plate to a flow path substrate having a pressure chamber; and a step of bringing a piezoelectric transducer into contact with the projection. 4. The inkjet according to claim 3, wherein the laminated body is manufactured by laminating a resin film having a metal thin film formed on one surface thereof with the base plate with the metal thin film as an outer side. Head manufacturing method. 5. The laminate has a metal thin film on one surface,
4. The method of manufacturing an inkjet head according to claim 3, wherein the resin film having an inorganic thin film formed on the other surface is manufactured by laminating the resin film on the base plate with the inorganic thin film as a contact surface. 6. The resin film is a stretched film, and the resin film is a stretched film.
5. The inkjet head and the manufacturing method thereof according to 5. 7. A step of forming a resin film layer functioning as a thin portion of the diaphragm on one surface of a silicon substrate having a crystal orientation (110) as a crystal plane, and forming a metal thin film on the resin film layer. A step of coating a photoresist on the metal thin film, selectively removing the resist after exposure and development, and a step of depositing a metal functioning as the protrusion on the removed portion using the metal thin film as an electrode A step of anisotropically etching the silicon substrate from the other surface of the silicon substrate to form a recess functioning as a pressure chamber, a step of joining a nozzle plate having a nozzle opening to the pressure chamber opening, the protrusion And a step of vertically contacting the piezoelectric conversion element with the step of manufacturing the inkjet head. 8. A step of forming an inorganic thin film on one surface of a silicon substrate having a crystal orientation (110) as a crystal plane, and a step of forming a resin film layer functioning as a thin portion of the diaphragm on the inorganic thin film. A step of forming a metal thin film on the resin film layer, a step of coating a photoresist on the metal thin film and selectively removing the resist after exposure and development, and using the metal thin film as an electrode in the removed portion. A step of depositing a metal functioning as the protrusion, a step of anisotropically etching the silicon substrate from the other surface of the silicon substrate to form a recess functioning as a pressure chamber, and forming a nozzle opening in the pressure chamber opening. A method for manufacturing an inkjet head, comprising: a step of joining a nozzle plate provided, and a step of vertically abutting a piezoelectric conversion element on the protrusion. 9. The method of manufacturing an ink jet head according to claim 7, wherein a silicon oxide film (SiO ₂ film) is formed between the silicon substrate and the resin film layer. 10. The method of manufacturing an inkjet head according to claim 3, wherein the thickness of the photoresist is thicker than or substantially equal to the thickness of the protrusion to be formed. 11. The method of manufacturing an inkjet head according to claim 3, wherein the amount of elongation of the resin film due to contact with ink is smaller than the amount of shrinkage of the resin film when the base plate is removed. 12. The manufacturing of an ink jet head according to claim 7, wherein the amount of elongation of the resin film due to contact with ink is smaller than the amount of shrinkage of the resin film when the silicon substrate is removed. Method. 13. The method of manufacturing an ink jet head according to claim 3, wherein the resin is a photosensitive resin.