JPH0781062A - Ink jet head device - Google Patents

Abstract

PURPOSE:To provide an ink jet head device preventing the chemical reaction between the ink and electrodes, occurrence of no dissolution and peeling of electrodes and having stable electrode life. CONSTITUTION:Dielectric layers 5 are formed on signal electrodes 4 and AC voltage is applied across the signal electrodes 4 and a current is allowed to flow across the signal electrodes 4 by the charge and discharge of a dielectric to boil ink. Further, overcoat layers 6 are formed on the dielectric layers 5 in a membrane form. By this constitution, since the direct contact of the signal electrodes 4 with ink has been eliminated and the reaction between the ink and the signal electrodes becomes hard to occur, the production of electrolytic air bubbles from the signal electrodes 4 and the dissolution and peeling of the signal electrodes 4 are hard to occur and stable electrode capacity can be obtained and long life can be secured.

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 device used for a print head such as a printer.

[0002]

2. Description of the Related Art In recent years, there have been increasing demands for printers to achieve high-speed printing, color printing, and low noise, and in particular, ink jet printers using ink jet heads have attracted attention.

The ink jet head system is roughly classified into a continuous system and an on-demand system. Further, the on-demand system includes a Kaiser system driven by a piezo element, a stem system, a Gould system, and bubbles generated by heat.
There is a bubble jet method in which ink is ejected by the volume change. Among these, the on-demand system in which an ink flow path and a pressure generating means are provided for each nozzle and ink droplets are ejected in response to a signal is accompanied by narrowing of a large number of ink flow paths in accordance with the high density demanded in recent years. In the case of manufacturing within the range, there are some points that the response frequency, flight stability, power consumption and efficiency are not sufficient.

A conventional bubble jet type ink jet head device will be described below. FIG. 8 is a sectional view of one nozzle of a conventional bubble jet type inkjet head, and FIG. 9 is a sectional view taken along the line AA of FIG. In FIG. 8, reference numeral 1 denotes a substrate on which a heat insulating layer 32 for effectively generating bubbles without allowing self-heating of the conductive ink to escape to the substrate 1 is laminated. A signal electrode 33a and a common electrode 33b are patterned on the heat insulating layer 32, and durable coatings 34a and 34b made of an oxide or a noble metal are coated on the signal electrode 33a and the common electrode 33b. A partition portion 2 made of an insulating material for preventing interference between the nozzles is provided on the durable coatings 34a and 34b, and a nozzle plate 3 having nozzles 8 is arranged on the partition portion 2, and the substrate 1
The partition 2 and the nozzle plate 3 constitute a pressure chamber 13. An ink channel 5 reaching the pressure chamber 13 is formed in the partition section 2.

In the figure, 11 is a signal generator for applying a voltage between the signal electrode 33a and the common electrode 33b, and 10 is a recording paper to which the conductive ink droplet 9 is attached. The operation of the inkjet head device configured as described above will be described below.

First, the signal generator 3 is operated by the signal generator 3.
When a voltage is applied between the common electrode 33a and the common electrode 33b, a line of electric force a is generated with respect to the common electrode 33b at the current passing portion b of the conductive ink having a predetermined volume resistivity as shown in FIGS. A current flows along this electric force line (a), and the conductive ink in the current passage portion (b) self-heats to start boiling and bubbles (not shown) are generated. The bubble rapidly increases the pressure of the conductive ink in the pressure chamber 13, and the conductive ink droplet 9 is ejected from the nozzle 8 and is ejected to adhere to the recording paper 10 to form a dot. The conductive ink consumed by the formation of the dots is always in the ink flow path 3
5, the conductive ink droplets 9 are continuously generated according to the signal from the signal generator 11, and arbitrary continuous dot formation is performed on the recording paper 10.

[0007]

However, in the above-mentioned conventional structure, since the durable coatings 34a and 34b are formed of the resin material and exposed in the pressure chamber 13, the pressure wave due to the capillary force or boiling is generated. Due to the heat insulation layer 32
And the conductive film 34a, 34b is filled with conductive ink, and the signal electrode 3 is protected by the durable film 34a, 34b.
3a, reaching the common electrode 33b, the durable coating 34a, 34
b, the formation of a local battery between the signal electrode 33a and the common electrode 33b, the dissolution of the signal electrode 33a and the common electrode 33b, the signal electrode 33a by the conductive ink, and the common electrode 3
There is a problem that the electrode performance is deteriorated such as corrosion of 3b.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide an ink jet head device which prevents chemical reaction between ink and electrodes, does not dissolve or peel off the electrodes, and has a long service life.

[0009]

In order to achieve this object, an ink jet head device of the present invention forms a dielectric layer on a pair of electrodes provided in a pressure chamber of a pressure chamber filled with ink. , A structure in which an alternating voltage is applied between both electrodes facing each other to flow a charging / discharging current of the dielectric layer. An overcoat layer is provided on the dielectric layer.

[0010]

With this structure, since the dielectric layer is formed on the electrodes, the chemical reaction between the electrode interface and the ink is eliminated, and the generation of electrolytic bubbles and the dissolution of the electrodes are eliminated. Further, since the overcoat layer is formed on the dielectric layer, the conductive ink hardly contacts the electrodes and the dielectric layer. Further, the overcoat layer can improve the strength against the pressure wave and the corrosion reaction bubbles due to the boiling of the ink while maintaining the charge / discharge characteristics of the dielectric layer, and prevent the durable coating layer from peeling off.

[0011]

【Example】

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view of an ink jet head device according to a first embodiment of the present invention. The same components as those shown in the conventional example are designated by the same reference numerals. In FIG. 1, 1 is a substrate, 2 is a partition part, 3 is a nozzle plate having nozzles 8, 13 is a pressure chamber formed by the substrate 1, partition part 2 and nozzle plate 3, and 4 is a part of the pressure chamber. A pair of signal electrodes pattern-formed on the substrate 1 so as to exist on the substrate 13, 9 are ink droplets ejected from the nozzle,
Reference numeral 10 is a recording paper to which the ink droplets 9 adhere, and these have basically the same structure as the above-mentioned conventional one.

The feature of the present embodiment is that a dielectric film 5 is formed on a pair of signal electrodes 4, an overcoat layer 6 is coated on the dielectric film 5, and the pair of signal electrodes 4 is formed by a signal generator 11. The purpose is to apply an AC voltage. In the figure, 7 indicates a durable coating layer, and 12 indicates a location where the electric field in the conductive ink generated by the signal generator 11 is concentrated.

FIG. 2 is an exploded perspective view of the main part of the ink jet head device of this embodiment. As shown in FIG. 2, a common ink chamber 14 for guiding ink to the pressure chambers 13 is provided on one side of the substrate 1, and an ink supply for supplying ink to each pressure chamber 13 is provided in the common ink chamber 14. A hole 15 is provided.

Further, FIG. 3 (a) is a diagram showing the ink jet head of this embodiment incorporated in an ink cartridge.
(B) is an exploded perspective view of the ink cartridge. As shown in the figure, the inkjet head 16 is fitted in and fixed to the ink cartridge 17. An ink filter 18 for removing dust and dirt contained in the conductive ink in the ink tank 20 is provided in the ink cartridge 17, and an ink introducing groove 19 for guiding the conductive ink to the common ink chamber 14 is formed. There is.

FIG. 4 shows a printer, in which the ink cartridge 17 is inserted through the cartridge insertion port 21 of the printer, and the inserted ink cartridge 17 is fixed to the carriage 22.
2 is guided by the guide shaft 23 to reciprocate serially. A platen roller 24 sends the recording paper 10.

The operation of the ink jet head device configured as described above will be described with reference to FIGS. 1, 2, 3, and 4. First, when the signal generator 11 applies an AC voltage of 1 MHz or more to the pair of signal electrodes 4 and a potential difference is generated between the pair of signal electrodes 4 adjacent to each other, the capacitors are charged and discharged according to the equivalent circuit shown in FIG. Here, 36 indicates a capacitor component by the dielectric layer 5 and the overcoat layer 6 on the surface of the signal electrode 4 shown in FIG. 1, and 37 indicates a resistance component by the resistance value of the ink. By this charging / discharging process, the electric force lines a shown in FIG. 1 are generated between the pair of signal electrodes 4 adjacent to each other in the conductive ink having a predetermined volume resistivity, and a current flows along the electric force lines a. , I ² R (I: current, R: resistance of conductive ink), the conductive ink self-heats due to the Joule loss of the current, and the current flows as time passes. Boiling starts from the portion of the current passing portion B of the sexual ink, and a bubble (not shown) is generated and expanded. As the bubble expands, the current in the conductive ink is bent to both sides of the bubble because the bubble is an insulator and the current cannot pass through the bubble, and the current density becomes highest on the bubble surface. Therefore, the bubble surface is heated most and the expansion of the bubble is further accelerated.
The pressure of the conductive ink in 3 rapidly increases. The conductive ink having a high pressure tends to move toward the nozzle 8 and the common ink chamber 14, but the existence of the ink supply hole 15 causes a fluid flow due to a sudden flow of the conductive ink due to a rapid pressure change. Since the resistance is larger than that of the nozzle 8, the rapid flow of the conductive ink due to the pressure change is directed to the nozzle 8, and the conductive ink droplet 9 is ejected from the nozzle 8 and is ejected and adhered to the recording paper 10. Dots are formed. When the expansion of the bubble reaches the maximum size, the current passing part b
Since the bubbles occupy a considerable portion, the current flowing through the conductive ink is reduced, and the heat of the bubble is deprived to the conductive ink, the nozzle plate 3, the signal electrode 4, the partition section 2 and the substrate 1, and the bubble is suddenly drawn. Shrinks and disappears. In this bubble, the heat of the bubble itself is taken from all directions,
The bubbles will eventually disappear in the conductive ink. With the disappearance of the bubble, the conductive ink in the pressure chamber 13 is agitated by the negative pressure at the time of disappearance and the temperature of the current passing portion (b) is lowered, and the electric current starts flowing again into the conductive ink. A heating time of several microseconds or more is required to start. During the heating time until the boiling starts, the signal generator 11 stops applying the voltage to the signal electrode 4 and prevents unnecessary flying of the conductive ink droplet 9 due to double boiling of the conductive ink. To do. Conductive ink drop 9
The conductive ink consumed by the flight of the ink is constantly transferred from the common ink chamber 14 to the pressure chamber 13 due to the surface tension of the conductive ink.
To the standby state. The temperature of the conductive ink in the pressure chamber 13 has risen slightly after the conductive ink droplet 9 has flown, but the conductive ink is in a standby state, the signal electrode 4, the nozzle plate 3, the partition 2 The heat is taken by the substrate 1, and the substrate 1 is cooled to almost the initial temperature.

By repeating the above operation, the ink cartridge 17 inserted from the cartridge insertion port 21 of the printer and mounted on the carriage 22 reciprocates along the guide shaft 23 in response to a print signal sent from a computer or the like. When moving, the signal generator 11 applies a drive voltage to an arbitrary signal electrode 4 in accordance with the position of the carriage 22, and conductive ink droplets 9 are continuously generated,
It adheres to the recording paper 10 sent by the platen roller 24, and the dots can be printed on the recording paper 10.

The signal electrode 4 exposed in the ink pressure chamber 13
Has a problem in that, in the energized state, it undergoes a redox reaction with cations and anions contained in the electrolyte and dye present in the conductive ink, resulting in the generation of electrolytic bubbles and the dissolution of the electrode itself. When the bubble repeatedly expands and contracts in the pressure chamber 13, cavitation usually occurs in the durable film layer 7 and the signal electrode due to the impact due to the pressure change of the ink. If the durable coating layer 7 is formed of a resist material containing a phenol resin or the like as a main component, the cavitation cannot be endured and the signal electrode 4 is peeled off. Further, as shown in FIG. 2, adjacent signal electrodes 4 facing each other have the same area exposed from the durable coating layer 7. However, one of the durable coating layers 7 formed of the resist material by the cavitation is partially formed. When it is peeled off, the exposed area of the signal electrode 4 is widened on one side, the electric resistance value of the signal electrode having a wide exposed portion is lowered, and more current flows between both electrodes. As a result, the current density of the other signal electrode facing the one signal electrode from which the durable coating layer 7 has peeled off increases, and the wear of the signal electrode is promoted. However, in this embodiment, the signal electrode 4 itself does not directly contact the conductive ink, and a current is passed through the ink during the charging / discharging process of the dielectric layer 5 formed on the signal electrode 4. Dissolution does not proceed. Further, since the overcoat layer 6 is formed on the dielectric layer 5, even if the bubbles repeatedly expand and contract in the pressure chamber 13, the signal electrode 4 and the durable film 7 are hardly peeled off or dropped. It is possible to obtain stable electrode performance.

Next, a method of forming the signal electrode 4 and the dielectric layer 5 on the substrate 1 will be described with reference to FIG. First, Pt is coated on the cleaned substrate 1 (silica glass or the like) by a vapor deposition method. The deposition conditions are as follows: a bulk sample of 99.99% Pt, which is the deposition source, is placed on a tungsten boat, the distance between the deposition source and the substrate 1 is 30 mm, and the power is 50.
A Pt film 25 having a thickness of 2 μm is formed at 0 W, a substrate temperature of 25 ° C., and a vapor deposition time of 60 minutes to obtain a substrate shown in FIG. As the material for forming the signal electrode, in addition to Pt, Ir
Platinum group elements such as Au and Au are good as electric conductors and are suitable as signal electrode materials.

Next, a photosensitive resist material containing a phenol resin as a main component was formed on the above substrate by a spin coater to a thickness of about 7 μm, and prebaked at 90 ° C. for 30 minutes to form a resist film 26. The substrate shown in 5 (b) is obtained. A photomask is overlaid on this substrate, exposed by a mask aligner for 20 seconds, and then developed, as shown in FIG.
As shown in (c), the head forming resist pattern 27
To form.

The substrate on which the resist pattern is formed is
Argon pressure 2 × 10 for milling with Lgon beam^-Four,
Beam power 300W, Stage tilt angle 45 degrees, Millin
For 80 minutes, and Pt except the resist
Head with milling of Pt film 25 to remove film 25
The forming resist pattern 27 is also milled, but P
t The resist material remaining on the pattern is washed in an organic solvent.
And completely remove it. Thus, as shown in FIG.
The Pt signal electrode 4 is formed. Next, as a dielectric layer, Ba
Sr_1-xTi_xO3 (x = 0.7) all over Pt pattern
Sputter on the surface. The sputtering conditions at this time are
Pressure 10 mTorr, AC power 800 W, sputtering time 2
BaS with a thickness of about 0.2 μm performed at a substrate temperature of 25 ° C. for 0 minutes
r_1-xTi _xO₃A dielectric film 28 is formed by
Al as an overcoat layer on this substrate₂O₃The spa
To Sputtering conditions are argon pressure 10 mTorr, A
C power 750 W, sputtering time 15 minutes, substrate temperature 25
Conducted at ℃, and the entire surface is made of alumina with a thickness of about 0.1 μm.
A bar coat film 29 is formed to obtain the substrate shown in FIG.
It Thus BaSr_1-xTi_xO₃Membrane and alumina
Is formed on the entire surface of the substrate as shown in FIG.
In addition, a register for dielectric film formation containing phenol resin as the main component
The strike pattern 30 directly above the signal electrode,
Formed with a vertical and horizontal margin of 1 μm
It The formation of the resist pattern 30 for forming the dielectric film is complete.
Phenolic resin is applied to the substrate on which the alumina film 26 is entirely formed.
About 7μm thickness of greasy resist material by spin coating
And prebaked at 90 ° C. for 30 minutes. The base
Put a photomask on the board and use a mask aligner to do 2
After exposure for 0 seconds, development is performed to form the resist pattern 27.
Form. Milling the substrate with an argon beam
Argon pressure 2 × 10^-Four, Beam power 300W, stay
Di tilt angle 45 degree, milling time 70 minutes, resist
Alumina film is removed except for the part where Milling
When the mill is finished, the resist is also milled.
The resist remaining on the overcoat film is
Completely wash and remove with the agent. By the above process
The dielectric layer 5 and overcoat shown in FIG.
A signal electrode 4 having a layer 6 is formed. Overcoat layer
6 is SiO in addition to alumina₂, SiC, Zr
O₂, ZnS, etc., cavitation of boiling bubbles
Stable electrode performance can be obtained.
The formation method is the same as for alumina, and the sputtering method
Gon pressure 10 mTorr, AC power 750 W, sputtering time
15 minutes at a substrate temperature of 150 ° C
The overcoat layer 29 is formed.

Photosensitive polyimide 3000 rpm on the signal electrode 4 having the dielectric layer 5 and the overcoat layer 6.
At 30 ° C. for 30 seconds and prebaked at 80 ° C. for 30 minutes to obtain the substrate shown in FIG. This substrate is exposed for 7 seconds to form a pattern of the durable coating layer,
After development, post-baking was performed at 400 ° C. for 1 hour, and then, as shown in FIG.
An electrode having the durable coating layer 7, the dielectric layer 5 and the overcoat layer 6 shown in (i) is formed. FIG. 6 shows FIG. 5 (i).
5A, the line AA 'corresponds to the line AA' in FIG.

When BaSr _1-x Ti _x O ₃ was used as the dielectric layer and alumina was used as the overcoat layer, boiling bubbles were generated when the applied voltage was 50 V and the AC frequency was 1 MHz or higher, and the signal electrode was dissolved. Stable electrode performance was obtained without peeling. (Embodiment 2) A method for forming the signal electrode 4 and the dielectric layer 5 on the substrate 1 according to another embodiment of the present invention will be described below with reference to FIG.
Will be explained. First, a Ti film is formed on the cleaned substrate 1 (silica glass or the like) by a sputtering method.
The sputtering condition is that the distance between the target and the substrate 1 is 80 m.
m, an argon pressure of 5 mTorr, a DC power of 300 W, a substrate temperature of 150 ° C., and a sputtering time of 40 minutes to form a Ti film 25 having a thickness of 2 μm to obtain the substrate shown in FIG. As the material for forming the signal electrode, in addition to Ti, Ta or Al
A material that forms a stable oxide film, such as, shows good characteristics as a dielectric. The sputtering conditions in the case of Ta are as follows: the distance between the target and the substrate is 80 mm, the argon pressure is 5 mTorr,
The DC power is 300 W, the substrate temperature is 150 ° C., and the sputtering time is 50 minutes. The sputtering conditions for Al are:
Distance between target and substrate is 80mm, argon pressure is 5m
Torr, DC power 300 W, substrate temperature 150 ° C., sputtering time 30 minutes. Next, a photosensitive resist material containing a phenol resin as a main component was formed on this substrate with a spin coater to a thickness of about 7 μm, and prebaked at 90 ° C. for 30 minutes to form a resist film 26, as shown in FIG.
The substrate shown in is obtained. A photomask is overlaid on this substrate, exposed by a mask aligner for 20 seconds, and then developed to form a head forming resist pattern 27 as shown in FIG. 5C.

The substrate on which the resist pattern is formed is milled by an argon beam at an argon pressure of 2 × 10 ⁻⁴ ,
Beam power 300 W, stage tilt angle 45 °, milling time 80 minutes, Ti except for resist
The head forming resist pattern 27 is also milled along with the milling of the Ti film 25 for removing the film 25.
The resist material remaining on the i pattern is washed in an organic solvent and completely removed. In this way, the Ti signal electrode 4 is formed as shown in FIG. Next, a dielectric film made of TiO ₂ is formed on the Ti pattern by the anodic oxidation method. The anodic oxidation is performed by immersing the electrode head portion in a 5% ammonium borate aqueous solution and using the signal electrode 4 as an anode at 1.5 A / cm.
A current density of ² is applied for 10 minutes to form a dielectric layer 5 (TiO ₂ ) having a thickness of about 0.1 μm. When the signal electrode 4 is made of Ta, the signal electrode 4 is used as an anode at 1.5 A / cm.
A current density of ² is applied for 10 minutes to form a dielectric layer 5 (Ta ₂ O ₅ ) having a thickness of about 0.1 μm. When the signal electrode 4 is made of Al, the signal electrode 4 is used as the anode and 1.2 A / c
A current density of m ² is applied for 5 minutes to form a dielectric layer 5 (Al ₂ O ₃ ) having a thickness of about 0.06 μm. Ti, Ta, Al
Shows a charge-discharge characteristic of a capacitor because it becomes an electrochemically stable metal oxide by forming an oxide film and has a relative dielectric constant of 10 to 100. Next, an Al ₂ O ₃ overcoat film is sputtered on this substrate. Sputtering conditions are argon pressure 10 mTorr, AC power 750
W, sputtering time 15 minutes, substrate temperature 25 ° C., overcoat film 29 of alumina having a thickness of about 0.1 μm is formed on the entire surface, and the substrate shown in FIG. 5E is obtained. Thus T
As shown in FIG. 5 (f), a dielectric film-forming resist pattern 30 containing phenol resin as a main component was formed on the entire surface of the substrate, on which the io ₂ film and the alumina were formed, directly above the signal electrode and vertically with respect to the signal electrode. , And both sides are formed with a margin of 1 μm. To form the resist pattern 30 for forming the dielectric film, first, a phenol resin-based resist material is applied by spin coating to a thickness of about 7 μm on a substrate on which the alumina film 26 is formed, and prebaking is performed at 90 ° C. for 30 minutes. A photomask is overlaid on the substrate, exposed by a mask aligner for 20 seconds, and then developed to form a resist pattern 27. The substrate is milled with an argon beam at an argon pressure of 2 × 10 ⁻⁴ , a beam power of 300 W, a stage tilt angle of 45 °, and a milling time of 70 minutes to remove the alumina film except the resist-coated portion. The resist is also milled during milling, but the resist remaining on the overcoat film at the time of finishing the milling is completely washed and removed by an organic solvent. Through the above steps, the signal electrode 4 having the dielectric layer 5 and the overcoat layer 6 shown in FIG. 5G is formed. As the overcoat layer 6, in addition to alumina, SiO ₂ , S
Even if iC, ZrO ₂ , ZnS or the like is used, it is difficult to undergo cavitation of boiling bubbles and stable electrode performance can be obtained. The forming method is the same as that of alumina, and is performed by the sputtering method at an argon pressure of 10 mTorr, an AC power of 750 W, a sputtering time of 15 minutes, and a substrate temperature of 150 ° C. to form an overcoat layer 29 having a thickness of about 0.1 μm.

A photosensitive polyimide 3000 rpm is formed on the signal electrode 4 having the dielectric layer 5 and the overcoat layer 6.
At 30 ° C. for 30 seconds and prebaked at 80 ° C. for 30 minutes to obtain the substrate shown in FIG. This substrate is exposed for 7 seconds to form a pattern of the durable coating layer,
After development, post-baking was performed at 400 ° C. for 1 hour, and then, as shown in FIG.
An electrode having the durable coating layer 7, the dielectric layer 5 and the overcoat layer 6 shown in (i) is formed. FIG. 6 shows FIG. 5 (i).
5A, the line AA 'corresponds to the line AA' in FIG.

When Ti oxide and Ta oxide are used as the dielectric layer and alumina as the overcoat layer, boiling bubbles are generated when the applied voltage is 50 V and the AC frequency is 6 MHz or more, and there is no melting or peeling of the electrode, which is stable. The electrode performance was obtained. When Al oxide is used as the dielectric layer and alumina is used as the overcoat layer, the applied voltage is 50 V,
When the AC frequency was set to 50 MHz or higher, boiling bubbles were generated, and the signal electrode was not melted or peeled, and stable electrode performance was obtained.

[0028]

As is apparent from the above description of the embodiments, since the present invention forms the dielectric layer and the overcoat layer on the signal electrode, the signal electrode does not come into direct contact with the ink. Therefore, the electrochemical reaction between the ink and the signal electrode does not occur, and it is possible to prevent the signal electrode from dissolving and the generation of electric bubbles. Further, since the signal electrode is protected by the dielectric layer and the overcoat layer, it is resistant to cavitation due to the pressure wave of boiling bubbles, and an excellent inkjet head capable of obtaining stable electrode performance can be realized. .

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an inkjet head device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of a main part of the inkjet head device.

FIG. 3A is a perspective view of the inkjet head and an ink cartridge. FIG. 3B is an exploded perspective view of the ink cartridge.

FIG. 4 is a partially cutaway perspective view of an inkjet printer having an ink cartridge incorporating the inkjet head.

5A to 5I are cross-sectional views of steps of forming an electrode, a dielectric layer, and an overcoat layer of an inkjet head according to an embodiment of the present invention.

FIG. 6 is a perspective view of FIG.

FIG. 7 is an equivalent circuit diagram of an inkjet head according to an embodiment of the present invention.

FIG. 8 is a cross-sectional view of a conventional inkjet head device.

FIG. 9 is a sectional view taken along line AA of FIG. 8 showing a conventional inkjet head.

[Explanation of symbols]

 1 Substrate 2 Partition 3 Nozzle Plate 4 Signal Electrode 5 Dielectric Layer 6 Overcoat Layer 7 Durable Layer 8 Nozzle 9 Ink Drop 10 Recording Paper 11 Signal Generator 12 Electrode Electric Field Concentration 13 Pressure Chamber

Claims (8)

[Claims] 1. A substrate, a pressure chamber formed on the substrate, a nozzle formed in the pressure chamber, and a pair of electrodes provided on the substrate and partly existing in the pressure chamber. ,
An inkjet head device comprising a signal generator that forms a dielectric layer on the pair of electrodes and applies an AC voltage to the pair of electrodes. 2. A dielectric layer provided on a pair of electrodes,
The inkjet head device according to claim 1, wherein the inkjet head device is a metal oxide. 3. The ink jet head device according to claim 2, wherein the dielectric layer is an oxide of Ti, Ta, or Al. 4. The dielectric layer provided on the pair of electrodes comprises:
The inkjet head device according to claim 1, wherein the inkjet head device is BaSr _1-x Ti _x O ₃ . 5. The AC frequency applied between the pair of electrodes is 1
The inkjet head device according to claim 1, wherein the inkjet head device is at least MHz. 6. The ink jet head device according to claim 1, wherein the material of the electrode is gold or a platinum group element. 7. The inkjet head device according to claim 1, wherein an overcoat layer is provided on the dielectric layer provided on the pair of electrodes. 8. The overcoat layer is Al₂O₃, SiO
₂, SiC, ZrO ₂Formed by ZnS, ZnS
7. The inkjet head device according to item 7.