JP2002248757A - Ink-jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic ink-jet head comprising a nozzle plate having a nozzle for ejecting ink droplets, an ejection chamber communicating with the nozzle, a vibrating plate for providing the wall surface of the ejection chamber and an electrode facing the vibrating plate, for ejecting ink droplets from the nozzle by deforming the vibrating plate by the electrostatic force, capable of stably sealing the opening of the gap between the vibrating plate and the electrode according to passage of the time. SOLUTION: An opening 25 of a gap 16 is sealed with an inorganic film 26, and an opening of a communication path 22 communicating with the gap 16 is sealed with an organic film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, and more particularly to an electrostatic ink jet head.

[0002]

2. Description of the Related Art As an ink jet head used in an image recording apparatus such as a printer, a facsimile, and a copying apparatus or an ink jet recording apparatus used as an image forming apparatus, a nozzle for discharging ink droplets and a discharge chamber (ink flow) communicating with the nozzle are used. Channel, ink chamber, pressure chamber, liquid chamber,
Also referred to as a pressurized chamber, a pressurized liquid chamber, and the like. ), A diaphragm forming the wall surface of the discharge chamber, and an electrode facing the diaphragm, and the diaphragm is deformed by electrostatic force to change the pressure / volume in the discharge chamber, thereby causing the ink to flow from the nozzles. 2. Description of the Related Art An electrostatic inkjet head for discharging droplets is known.

In such an ink jet head, an electrostatic actuator is constituted by a diaphragm serving as a movable portion and electrodes facing the diaphragm. Electrostatic actuators with a diaphragm as a movable part include micro-pumps, micro-switches (micro-relays), multi-optical lens actuators (micro-mirrors), micro flow meters, pressure sensors, etc. Although it is used, the following mainly describes the inkjet head.

Meanwhile, in an electrostatic ink jet head, while the head is driven by repeatedly applying a voltage between the opposed electrodes (between the diaphragm and the electrodes), the surface of the opposed electrode, that is, the opposed diaphragm is driven. If moisture adheres to the surface of the electrode or the surface of the electrode on the diaphragm side, electrostatic attraction or electrostatic repulsion may be reduced due to the charging of these polar molecules. In addition, the polar molecules adsorbed on the surface of the vibration plate and the surface of the electrode side may be hydrogen-bonded to each other, and the vibration plate may remain stuck to the electrode side, and may not operate.

Therefore, in a conventional electrostatic ink jet head, for example, as shown in Japanese Patent Application Laid-Open No. 6-71882, a diaphragm and electrodes are formed by using a thermosetting or photo-curing resin (adhesive). Gap (vibration chamber)
Is sealed.

[0006]

However, in the above-mentioned conventional ink jet head, gas is generated from the adhesive when the adhesive is hardened, and the diaphragm is deformed by the curing and contraction of the adhesive. There are problems such as unstable ejection. There is also a method of using an elastic adhesive to avoid deformation of the diaphragm due to curing shrinkage or gas from the sealing agent as described above, but in the case of a sealing film of resin,
When the use environment and the storage environment (pressure, temperature) change, the ink discharge characteristics, the vibration plate driving characteristics, etc. change over time. That is, air passes between the inside and outside of the vibration chamber via the sealant There is a problem to do.

The present invention has been made in view of the above problems, and has as its object to provide an ink jet head that is stable over time.

[0008]

In order to solve the above-mentioned problems, an ink jet head according to the present invention has a plurality of gaps formed by sealing an opening of a gap formed between a diaphragm and an electrode with an inorganic film. The opening of the communication path communicating with the outside is sealed with an organic film.

Here, the inorganic film is preferably an oxide film. In this case, the oxide film is preferably a film formed by a CVD method or a thermal oxidation method. Further, it is preferable that the organic film is a room temperature curable resin. Further, it is preferable that the opening of the gap is narrower than the gap.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory cross-sectional view of an ink jet head according to the present invention along a longitudinal direction of a diaphragm.
FIG. 3 is an explanatory cross-sectional view of the communication passage opening portion of the head in the longitudinal direction of the diaphragm, and FIG. 3 is an explanatory cross-sectional view of main parts of the head along the lateral direction of the diaphragm.

The ink jet head has a flow path substrate 1 which is a first substrate using a silicon substrate such as a single crystal silicon substrate or an SOI substrate having a crystal plane orientation of (110), and a lower side of the flow path substrate 1. An electrode substrate 2 which is a second substrate using a single crystal silicon substrate having a crystal plane orientation of (100).
A plurality of nozzles 4 for ejecting ink droplets; a discharge chamber 6 as an ink flow path to which each nozzle 4 communicates; A common liquid chamber 8 and the like, which communicate with the chamber 6 via a fluid resistance portion 7 also serving as an ink supply path, are formed.

The discharge chamber 6 and the discharge chamber 6
A concave portion forming the diaphragm 10 also serving as a first electrode serving as a bottom portion, which is a wall surface, and a through portion forming the common liquid chamber 8 are formed. When a single-crystal silicon substrate is used, for example, when a single-crystal silicon substrate is used, boron is injected in advance to the thickness of the diaphragm to form a high-concentration boron layer serving as an etching stop layer. By anisotropically etching the concave portion serving as the chamber 6 using an etching solution such as a KOH aqueous solution, the high-concentration boron layer serves as an etching stop layer, and the diaphragm 10 is formed with high precision.

When an SOI substrate in which a silicon active layer is bonded to a silicon base substrate via an oxide layer is used, the diaphragm 10 is formed of the active layer. In this head, the diaphragm 10 also functions as the first electrode, but the first electrode may be formed integrally with the diaphragm 10 separately from the diaphragm 10.

For example, a single crystal silicon substrate having a crystal plane orientation (100) is used as the electrode substrate 2, and a silicon oxide film layer 12 as an insulating layer is formed on the silicon substrate by a thermal oxidation method or the like. An electrode forming groove 14 is formed in the portion of the film layer 12, an electrode 15 which is a second electrode facing the diaphragm 10 is provided on the bottom surface of the groove 14, and a required electrode is provided between the diaphragm 10 and the counter electrode 15. A gap 16 having a length (here, 0.1 μm or less) is formed, and the diaphragm 10 and the electrode 15 constitute an electrostatic actuator section.

Here, the electrode 15 extends to the outside along the electrode forming groove 14 to connect to a connection means such as an FPC cable connected to an external drive circuit (driver IC) for applying a drive waveform. Is formed. Further, on the surface of the electrode 15, an electrode protective film 17 made of an oxide insulating film such as a SiO ₂ film or a nitride insulating film such as a Si ₃ N ₄ film is formed.
5 without forming the electrode protection film 17 on the surface of the diaphragm 10
An insulating film can be formed on the side. The electrode substrate 2
Has an ink supply port 18 communicating with the common liquid chamber 8.

Although the electrode 15 of the electrode substrate 2 is made of TiN, other materials such as Al, Cr, Ni, etc., which are generally used in a process of forming a semiconductor element, and TiN are used. , W, or the like, or a polycrystalline silicon material whose resistance is reduced by impurities can be used. When a silicon substrate is used as the electrode substrate 2, an impurity diffusion region can be used as the electrode 15. In this case, the impurity used for the diffusion is an impurity having a conductivity type opposite to the conductivity type of the substrate silicon, a pn junction is formed around the diffusion region, and the electrode 15 and the electrode substrate 2 are electrically insulated.

Further, an individual communication passage 2 communicating with each gap 16 between the diaphragm 10 and the electrode 15 is formed in the electrode substrate 2.
1 and a common communication passage 22 communicating with each of the individual communication passages 21. Two common communication passages 22 corresponding to the respective nozzle rows are connected at one end in the nozzle row direction as shown in FIG. An opening 23 communicating with the outside is formed collectively in the book, and an atmosphere opening port 24 is formed in the flow path substrate 1 corresponding to the opening 23 of the communication passage 22 of the electrode substrate 2.

The bonding between the flow path substrate 1 and the electrode substrate 2 can be performed by an adhesive, but more reliable physical bonding, for example, when the electrode substrate 2 is formed of a silicon substrate Alternatively, a direct bonding method via an oxide film can be used. This direct bonding is performed at a high temperature of about 1000 ° C. Also, the electrode substrate 2 is formed of a silicon substrate,
Pyrex (registered trademark) glass may be formed between the electrode substrate 2 and the flow path substrate 1, and anodic bonding may be performed via this film. Furthermore, the flow path substrate 1 and the electrode substrate 2 can be bonded by eutectic bonding in which a binder such as gold is interposed between bonding surfaces using a silicon substrate.

The nozzle plate 3 is formed by arranging a large number of nozzles 4 in two rows, forming a groove serving as a fluid resistance portion 7 which connects the common liquid chamber 8 and the discharge chamber 6, and forming a groove on the discharge surface. Water repellent treatment is applied. Examples of the nozzle plate 3 include a plating film manufactured by Ni electroforming, a silicon substrate,
Metals such as SUS and those having a multilayer structure of a metal layer such as resin and zirconia can also be used. Here, the nozzle plate 3 is bonded to the flow path substrate 41 with an adhesive.

In this ink jet head, the opening 25 of the gap 16 formed between the flow path substrate 1 and the groove 14 of the electrode substrate 2 is sealed with an inorganic film 26, and the common communication path described above is used. The opening 23 is sealed by filling the air opening 24 of the flow path substrate 1 corresponding to the opening 23 with the organic film 27.

As described above, by sealing the opening 25 of the gap 16 with the inorganic film 26, generation of gas at the time of curing as in the case of sealing with an adhesive, and deformation of the diaphragm 10 due to curing shrinkage can be prevented. And there is no variation in the amount of adhesive entering the vibration chamber (in the gap 16).
A stable operation can be obtained with high reliability even under high temperature and high humidity. In addition, by forming the communication paths 21 and 22 and sealing the opening 23 with the organic film 27, sealing with the inorganic film 26 is performed under reduced pressure. In this case, it is possible to prevent the diaphragm 10 from being deformed.

Here, an oxide film can be used as the inorganic film 26. By using an oxide film, if a sealing step is performed before joining the nozzle plate 3, an oxide film can be simultaneously formed on the flow path wall surfaces such as the discharge chamber 6 and the common liquid chamber 8, and liquid contact reliability is improved. improves. Such an oxide film can be formed by CVD or thermal oxidation.

Further, as the organic film 27, a room temperature curing type resin can be used. By using the room-temperature curing resin, there is no outgas due to heat, and the deformation of the diaphragm 10 due to the thermal expansion of the air in the vibration chamber can be suppressed, resulting in a variation in the amount of deformation (variation in the thickness of the diaphragm). The variation in the vibration characteristics of the diaphragm and the variation in the ink droplet speed can be reduced.

In the ink jet head configured as described above, when a pulse potential of 0 V to 35 V is applied to the individual electrodes 15 by a driving circuit, the surface of the electrodes 15 is positively charged. 10
Is charged to a negative potential, so that the diaphragm 10 is deformed toward the electrode 15 by electrostatic attraction. Next, when the application of the pulse potential to the electrode 15 is turned off, the diaphragm 10 is restored to the discharge chamber side with the discharge of the electric charge accumulated on the surface of the electrode 15, and at that time, the diaphragm 10 suddenly enters the discharge chamber 6. A volume change / pressure change occurs, and the filled ink droplet is ejected from the nozzle 5.

Next, another embodiment of the ink jet head according to the present invention will be described with reference to FIGS. First, as shown in FIG.
A silicon wafer 30 having a mold crystal plane orientation (100) is prepared, and an electrode substrate 31 is formed from the silicon wafer 30. An oxide film is formed on the electrode substrate 31 by a thermal oxidation method, wet oxidation, or the like, and the oxide film is formed on the electrode portion 32 (the electrode portion 32 is the electrode forming groove, the electrode, and the electrode protection insulating film of the above-described embodiment). Are formed, and the communication passages 33 are formed so as to communicate the gaps (the electrode forming grooves in this state) of the respective electrode portions 32. ) To form the openings 34 collectively. In this example, the communication passage 35 is provided between the gaps.
The individual communication passages 21 are not formed to communicate with each other for each gap as in the above-described embodiment.

On the other hand, as shown in FIG. 2B, a silicon substrate 41 serving as a flow path substrate, which is a silicon wafer 40 having a crystal plane orientation of (110) on which a high-concentration boron diffusion layer is formed, is prepared. c), the silicon substrate 41 and the electrode substrate 31 (the silicon wafer 30 and the silicon wafer 4).
0) and the silicon substrate 4
1 is polished until the thickness becomes 100 μm to obtain a predetermined liquid chamber height.

Next, a nitride film serving as an etching mask is deposited on the laminated substrate in which the electrode substrate 31 and the silicon substrate 41 are directly bonded, and an ink supply port is formed in the electrode substrate 31 as shown in FIG. At the same time, the discharge chamber 46 including the vibration plate 45, the common liquid chamber 48, the temporary bonding area 49, and the communication path opening (atmosphere opening port) 50 are formed on the silicon substrate 41 by wet etching to obtain the flow path substrate 51. At this stage, the high-concentration boron diffusion layer remains and the communication passage opening 50 is not opened.

Thereafter, as shown in FIG. 2D, a portion of the flow path substrate 51 corresponding to the electrode pad portion 32a of the electrode portion 32 is removed by dry etching to form an opening.

Next, as shown in FIG. 5A, the space between the flow path substrate 51 and the electrode substrate 31 (opening of the gap) is sealed with an inorganic film 61. When sealing with the inorganic film 61 is performed under reduced pressure, the diaphragm 45 has a shape that bends downward.

Next, as shown in FIG. 3B, the inorganic film 61 on the electrode pad portion 32a is removed by dry etching to form an opening. Thereafter, the silicon wafer is cut by dicing for each head chip. Next, as shown in FIG. 3B, the high-concentration boron diffusion layer remaining in the air opening 50 of the flow path substrate 51 is removed by dry etching to form an opening. Even when the diaphragm 45 is bent under the reduced pressure, the opening 34 of the communication passage 33 is opened to the atmosphere by opening the air opening 50, so that the gap of the electrode portion 32 is opened. The diaphragm 45 is restored to the parallel state because the air flows into the inside.

Then, as shown in FIG. 3C, the exposed individual electrodes of the electrode portion 32 and the FPC cable 62 are electrically connected by an anisotropic conductive film. A driver IC is mounted on the cable by wire bonding. Next, an organic sealant 63 is filled in the air opening 50 to seal the opening 34 of the communication path 33. With this sealing,
The gap becomes a completely enclosed space. Then, FIG.
In order to join the nozzle plate 53 having the nozzles 54 formed on the flow path substrate 51 (actuator section) to the nozzle plate 53, an adhesive is applied to the upper surface of the flow path substrate 51 and then temporarily bonded to the temporary bonding application area 49. A photocurable adhesive 64 is applied as an agent by a dispenser.

Then, as shown in FIG. 3D, a nozzle plate 53 having a nozzle 54 formed by Ni electroforming or the like,
The electrostatic actuator portion to which the adhesive has been applied is positioned and temporarily pressurized. Here, the photocurable adhesive is irradiated with ultraviolet rays to cure the adhesive 64, and is then subjected to main pressure to be cured by heating.

As described above, a gap opening (referred to as a first communication passage) formed by the electrode forming groove and the flow path substrate that communicates each vibration chamber (gap between the vibration plate and the electrode) with the outside. And a communication path (referred to as a second communication path) 33 that communicates the plurality of vibration chambers and communicates with the outside. The open end between the first communication path and the outside is sealed with an inorganic film 61. , Second
The open end (opening 34) between the communication path 33 and the outside is formed by the organic
By sealing with 3, the head having high humidity resistance and reliability can be obtained.

Even if the open end (gap opening) between the first communication path and the outside is sealed with the inorganic film 61 under reduced pressure, the open end between the second communication path and the outside is thereafter opened. As a result, the diaphragm returns to the equilibrium state, and it is possible to reduce variations in diaphragm vibration characteristics caused by variations in the amount of deflection of the diaphragm (variations in the thickness of the diaphragm).

The distance between the flow path substrate and the electrode substrate at the open end communicating from the vibration chamber to the outside is made narrower than the distance between the vibration plate and the electrode portion opposed to the vibration plate. By making the gap opening narrower than the gap, it is possible to seal the open end communicating from the vibration chamber to the outside with a thinner inorganic film, thereby improving the throughput.

Further, it is possible to use an oxide film as the inorganic film and perform sealing with the oxide film at the same time as the process of forming an oxide film for improving the liquid contact property of the flow path portion. A highly efficient head is obtained. Furthermore, by using a room-temperature-curable resin as the organic film, there is no outgas due to heat at the time of sealing, and it is possible to suppress deformation of the diaphragm due to thermal expansion of air in the vibration chamber. It is possible to suppress variations in vibration characteristics of the diaphragm due to variations in the thickness of the diaphragm, and variations in ink droplet speed.

Next, a specific example of the manufacturing process of the ink jet head will be specifically described with reference to FIGS. FIGS. 6 and 7 are cross-sectional explanatory views of the vibration chamber portion of the head along the longitudinal direction of the diaphragm, and FIGS. 8 and 9 are cross-sectional explanatory views of the vibration chamber spacing wall portion of the head along the longitudinal direction of the diaphragm.

First, as shown in FIGS. 6 (a) and 8 (a), a P-type silicon substrate serving as an electrode substrate 31 having a crystal plane orientation (100) and a thickness of 625 μm is prepared.
In FIG. 1, an oxide film 72 having a thickness of 2 μm was formed by wet oxidation. The oxidation conditions are 1050 ° C. and 18.5 h.

Next, as shown in each figure (b), the resist is patterned using a gradation mask.
The oxide film 72 was patterned by dry etching and wet etching to form an electrode forming groove 74. At this time, by forming the electrode forming groove 74 using a gradation mask, a non-parallel gap (a gap where the diaphragm and the electrode are positioned in a non-parallel state) can be formed. It is possible to form a gap shape which is advantageous for the formation.

As shown in FIGS. 8B and 8C,
In the partition wall 73 (a portion serving as a gap spacer) in the short direction of the diaphragm between the electrode forming grooves 74 formed by the oxide film 72, a communication path 35 that connects each gap to each other is formed, and the oxide film 72 is formed. Formed a communication passage 33 and an opening 34 which are continuous with the communication passage 35.

Then, as shown in FIG. 6C, a 200 nm thick TiN 303 is formed on the surface of the oxide film 72 by sputtering, and the TiN film is etched into an electrode shape to form an individual electrode 75. After that, a silicon oxide film is formed to a thickness of 200 nm as an electrode protection film, and the silicon oxide film and the TiN film other than the electrode portion 32 are removed by dry etching and wet etching, respectively, so that an oxide film 77 is formed on the electrode 75. Formed.

Thereafter, as shown in each figure (d), a silicon substrate 41 having a thickness of 400 μm and a crystal plane orientation (110) on which a high-concentration boron diffusion layer 42 is formed is placed on the electrode substrate 31 at a bonding temperature of 900 to 100 ° C. Then, the silicon substrate 41 was polished to a predetermined liquid chamber height of 100 μm.

Next, as shown in FIGS. 7A and 9A, a nitride film (not shown) is laminated and patterned on the electrode substrate 31 and the silicon substrate 41, and an ink supply port 78 is formed in the electrode substrate 31. It is formed by wet etching.

Thereafter, as shown in FIG.
The discharge chamber 46 and the common liquid chamber 48 having the liquid crystal layer 5 were formed by wet etching to obtain the flow path substrate 51. At this time,
Temporary adhesive area 49 for nozzle plate bonding and communication passage opening 5
0, an electrode pad opening region was also formed at the same time.

Since the etching rate of the region into which boron is implanted is lower than that of the silicon region into which boron is not implanted, the diaphragm 45 is selectively provided only in the region where boron is implanted.
It is possible to leave as. At this time, since the electrode substrate 31 and the silicon substrate 41 are joined under reduced pressure, the region (diaphragm 45) which has been etched and turned into a thin film has a shape bent downward.

Further, the electrode substrate 31 and the oxide film 72 were etched, and the high-concentration boron diffusion layer 42 was etched to make the ink supply port 78 and the common liquid chamber 48 communicate.

Next, as shown in each of the figures (c), the flow path substrate 51 of the electrode pad portion 32a was opened by etching. At this time, since the gap 76 is opened to the atmosphere,
The diaphragm 45 has a horizontal shape. Therefore, an open end (opening of the gap 76) communicating from each vibration chamber to the outside was sealed with an oxide film 61 formed by a CVD method.

In this case, the diaphragm 45 was bent downward when the pressure was returned to the normal pressure because the vacuum CVD was performed. Then, the oxide film 6 on the electrode pad portion 32a is formed.
1 was removed by etching. Then, each head chip was separated from the wafer by dicing. Thereafter, by opening the open end (atmosphere opening port 34) of the communication passage 33 connected to the outside through each vibration chamber (gap 76), the inside of the gap 76 is opened to the atmosphere through the communication passage 33 and once bent. The diaphragm 45 has returned to the horizontal state. Therefore, the open end of the communication passage 33 was sealed with a cold-setting epoxy adhesive (Ultite 1540; trade name).

As described above, the electrostatic actuator section 81
It was created.

Next, assembling steps of the ink jet head including the above-described actuator section 81 will be described with reference to FIG.
This will be described with reference to FIG. This figure is an exploded perspective view of the entire head. First, an FPC cable 83 on which a driver IC 82 is mounted is connected to the electrostatic actuator section 81 obtained as described above by an anisotropic conductive film.

Thereafter, an adhesive is applied to the upper surface of the flow path substrate 51 in order to join the electrostatic actuator section 81 and the nozzle plate 53. When the flow path substrate 51 and the nozzle plate 53 are joined by an adhesive, since the protrusion of the adhesive affects the ejection characteristics, the coating film thickness needs to be about 1 μm. Therefore, the adhesive was applied to the upper surface of the flow path substrate 51 by a transfer method. Specifically, the method was such that the adhesive was thinned to a roller with a doctor blade, the adhesive was transferred from the roller by a transfer pad, and the adhesive was further transferred from the transfer pad to the upper surface of the flow path substrate 51.

In order to position the nozzle plate 53 and the flow path substrate 51 (position the nozzle 54 and the discharge chamber 46), an ultraviolet curing adhesive 64 for temporary bonding is formed on the flow path substrate 51. It was applied to the temporary adhesive application area 49 by a dispenser. Then, a nozzle plate 53 formed by Ni electroforming or the like and an electrostatic actuator portion 81 coated with an adhesive
And were provisionally pressurized. Thereafter, the ultraviolet-curable adhesive was irradiated with ultraviolet rays to cure the adhesive, and then subjected to main pressure to be cured by heating.

When warping occurs due to a difference in linear expansion coefficient between the silicon substrate forming the flow path substrate 51 and the nozzle plate 53 (for example, Ni or SUS) at the time of heat bonding, the actuator portion is caused by internal stress. Since the adhesive 81 may be broken, the curing temperature of the adhesive is preferably low. Therefore, it is preferable to use a two-component mixed type (room temperature curing type) epoxy adhesive. The lower the curing temperature, the better, and here the curing was performed at 50 ° C.

A joint 86 for supplying ink from an ink supply tank or ink cartridge is provided.
Then, the frame 88 to which the filter 87 was heat-welded was bonded and bonded. An adhesive was applied to the frame 88 to bond the actuator section 81, and the actuator 81 was aligned and bonded.

With respect to this ink jet head, the amount of deformation of the diaphragm and the amount of change with time were measured when the ink jet head manufactured by the conventional forming method was left in a high temperature environment (70 ° C.) for 48 hours and then returned to room temperature. FIG. 11 shows the result. In the conventional ink jet head, when the substrate is released to the gap atmosphere, the opening of the gap is sealed with an adhesive such as epoxy having a high viscosity when the substrate temperature falls to room temperature.

In the conventional ink jet head, the diaphragm undergoes deformation of about 0.1 μm immediately after returning to room temperature, and the amount of deformation changes over time. Deformation amount is 0.0
It can be seen that there is almost no change with time when the thickness is less than 05 μm. In addition, the result of the humidity resistance environment measurement was good.

[0057]

As described above, according to the ink jet head of the present invention, the opening of the gap formed between the diaphragm and the electrode is sealed with the inorganic film, and the plurality of gaps communicate with the outside. The opening of the communicating passage is sealed with an organic film, so there is no gas generated during curing such as adhesive sealing, deformation of the diaphragm due to curing shrinkage, and variation in the amount of adhesive entering the vibration chamber And the reliability under high temperature and high humidity is improved, and the deformation of the diaphragm caused when the inorganic film is sealed under reduced pressure can be prevented.

Here, since the inorganic film is an oxide film, an oxide film can be simultaneously formed on the wall surface of the flow path, and the reliability of liquid contact can be improved. In this case, the oxide film can be easily formed because the oxide film is a film formed by a CVD method or a thermal oxidation method. Further, by using the room-temperature curing type resin as the organic film, deformation of the diaphragm due to thermal expansion of the air in the vibration chamber can be suppressed, and variation in the vibration characteristics of the diaphragm can be reduced. Furthermore, by making the opening of the gap narrower than the gap, the throughput of the sealing step can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view of a vibration chamber portion of an inkjet head according to an embodiment of the present invention, taken along a longitudinal direction of a diaphragm.

FIG. 2 is an explanatory cross-sectional view taken along the longitudinal direction of the diaphragm at the end of the head in the nozzle arrangement direction.

FIG. 3 is an explanatory cross-sectional view of the head taken along a lateral direction of a diaphragm.

FIG. 4 is an explanatory diagram illustrating an inkjet head according to another embodiment of the present invention together with its manufacturing process.

FIG. 5 is an explanatory view illustrating a step following FIG. 4;

FIG. 6 is an explanatory cross-sectional view along a longitudinal direction of a vibration plate in a vibration chamber portion specifically illustrating a manufacturing process of the inkjet head according to the embodiment;

FIG. 7 is an explanatory sectional view illustrating a step following FIG. 6;

FIG. 8 is an explanatory cross-sectional view of a partition wall portion of a vibration chamber along a longitudinal direction of the diaphragm.

FIG. 9 is an explanatory sectional view illustrating a step following FIG. 8;

FIG. 10 is an exploded perspective view of an inkjet head including an actuator according to the present invention.

FIG. 11 is an explanatory diagram illustrating an example of measurement results of an initial change amount and a change with time of a diaphragm with respect to an inkjet head according to the present invention and a conventional inkjet head.

[Explanation of symbols]

Reference numerals 1, 51: flow path substrate, 2, 31: electrode substrate, 3, 5: nozzle plate, 4, 5: nozzle, 6, 46: discharge chamber, 7: fluid resistance part, 8, 48: common liquid chamber, 10 , 45 ... diaphragm, 1
5, 75: electrode, 16, 76: gap, 21: individual communication path, 22: common communication path, 25: gap opening, 26,
61: oxide film, 27, 63: organic film, 33, 35: communication path.

Claims (6)

[Claims] A nozzle for discharging ink droplets, a discharge chamber communicating with the nozzle, a diaphragm forming at least a part of a wall surface of the discharge chamber, and an electrode facing the diaphragm. In an inkjet head that ejects ink droplets by deforming a vibration plate with electrostatic force, an opening of a gap formed between the vibration plate and an electrode is sealed with an inorganic film, and a plurality of the gaps communicate with the outside. An opening of the communicating passage, which is sealed with an organic film. 2. The ink jet head according to claim 1, wherein said inorganic film is an oxide film. 3. The ink jet head according to claim 2, wherein said oxide film is a film formed by a CVD method. 4. The ink jet head according to claim 2, wherein said oxide film is a film formed by a thermal oxidation method. 5. The ink jet head according to claim 1, wherein the organic film is a room temperature curable resin. 6. The ink jet head according to claim 1, wherein an opening of the gap is narrower than the gap.