JP2000168079A - Electrostatic actuator and ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic ink jet head having a counter electrode which is not charged easily through contact. SOLUTION: In an electrostatic ink jet 1, bottom face of each ink chamber 6 functions as a diaphragm 5 which serves as a common electrode. The segment electrode part 18 of an individual electrode 17 facing the diaphragm 5 through a microgap 15 is formed of an ITO film where the ITO crystal has a prevailing crystal orientation (222). When a segment electrode part 18 formed of such an ITO film is employed, contact charging can be suppressed on the surface of a counter electrode resulting in a reliable ink jet head exhibiting high print quality for a long term.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electrostatic actuator that uses an electrostatic force generated by applying a voltage between opposing electrodes as a driving source, and an ink jet head using the electrostatic actuator. It is. More specifically, the present invention relates to an electrostatic actuator and an ink jet head capable of suppressing contact charging generated on the surface of a counter electrode.

[0002]

2. Description of the Related Art An electrostatic ink-jet head which discharges ink droplets by using an electrostatic force generated between opposed electrodes is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 5-50601 and 6-70882 by the present applicant. Is disclosed.

In an electrostatic ink jet head, the bottom surface of an ink chamber communicating with an ink nozzle is formed as an elastically deformable diaphragm. A glass substrate is opposed to this diaphragm with a certain gap. The diaphragm is made of a thin silicon substrate and functions as one of the opposite electrodes. The other electrode film is formed on the surface of the glass substrate, and the surface of the electrode film is covered with an insulating layer. The electrode film is, for example, Ni formed by sputtering.
The insulating layer is, for example, a SiO2 film formed by mask sputtering.

When a voltage is applied between these opposed electrodes,
The vibrating plate forming the bottom surface of the ink is displaced by electrostatic attraction or repulsion against the glass substrate by the electrostatic force generated between them. Ink droplets are ejected from the ink nozzles due to fluctuations in the internal pressure of the ink chamber caused by the vibration of the bottom surface of the ink chamber. Therefore, by controlling the voltage applied between the opposing electrodes, a so-called ink-on-demand method in which ink droplets are ejected only when necessary for recording can be realized.

[0005]

Here, the counter electrode is:
With the vibration of the vibration plate, the insulating layer is interposed and repeatedly contacted. As a result, contact charging occurs on the surface of the insulating layer, and due to the contact charging, the electrostatic attraction force and the electrostatic repulsion force of the diaphragm fluctuate, and the vibration of the diaphragm may become unstable. is there. When the vibration of the diaphragm becomes unstable, ink droplets of an appropriate size are not ejected in an appropriate direction, and unnecessary ink mist is generated. As a result, printing defects and ink stains on the ink nozzle surface, the printer case, and the like occur.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to propose an electrostatic actuator capable of preventing operation instability due to contact charging by suppressing contact charging generated on the surface of the counter electrode. Is to do.

Another object of the present invention is to provide an ink-jet head capable of avoiding the occurrence of printing defects and the occurrence of ink stains at various portions due to unnecessary ink mist or the like by suppressing contact charging generated on the surface of the counter electrode. It is to propose.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides first and second relatively displaceable electrode members which are arranged at a predetermined interval and are opposed to each other. A driving means for generating an electrostatic force on the electrode member to relatively displace the electrode member, wherein the first electrode member is formed of an ITO film, and the ITO film has a crystal orientation of the ITO crystal. Wherein the composition ratio (222) / (400) is set to 0.5 or more.

Further, the electrostatic actuator of the present invention comprises:
The dominant crystal orientation of the ITO crystal of the ITO film is (40)
0).

Further, the present invention is characterized in that the dominant crystal orientation of the ITO crystal in the ITO film is (222).

In a typical electrostatic actuator, the first electrode member is formed on a surface of a rigid glass substrate,
The second electrode member is a diaphragm made of a silicon substrate. Further, the surface of at least one of the first and second electrode members is covered with an insulating layer.

In the case where the ITO film is formed by DC magnetron sputtering, if the glass substrate temperature is set to 350 degrees Celsius or less as a film forming condition,
An ITO film having a desired crystal orientation can be obtained.

[0013] In the electrostatic actuator of the present invention configured as described above, even if the first and second electrode members repeatedly contact, the occurrence of contact charging is suppressed as compared with the conventional electrostatic actuator. It was confirmed that the operation was stabilized for a long time.

On the other hand, the electrostatic ink-jet head according to the present invention has a structure to which the above-mentioned electrostatic actuator is applied, and is characterized in that one of the opposed electrodes is formed of an ITO film.

That is, an ink nozzle, an ink chamber communicating with the ink nozzle, a silicon vibration plate forming a part of the ink chamber, and a predetermined gap are arranged opposite to the vibration plate. An ink droplet is ejected from the ink nozzle by vibrating the vibrating plate by electrostatic force generated between the vibrating plate and the electrode, comprising an opposing substrate and an electrode formed on the surface of the opposing substrate. In the inkjet head, the electrodes formed on the surface of the counter substrate are formed from an ITO film,
Further, the ITO film is characterized in that the composition ratio (222) / (400) of the crystal orientation of the ITO crystal is 0.5 or more.

Further, the electrostatic ink jet head of the present invention is characterized in that the dominant crystal orientation of the ITO crystal of the ITO film is other than the (400) direction.

Further, the electrostatic ink jet head of the present invention is characterized in that the dominant crystal orientation of the ITO crystal of the ITO film is (222).

Also in this case, in a typical ink jet head, the electrodes are formed on the surface of a glass substrate, and the surface of the electrodes is covered with an insulating layer.

Further, if the ITO film is formed by a DC magnetron sputtering method under the condition that the glass substrate temperature is 350 ° C. or less, an ITO film having a desired crystal orientation can be obtained.

In the ink jet head having this structure, the contact charging on the surface of the counter electrode is suppressed, so that the vibration characteristics of the diaphragm can be stabilized. Therefore, it is possible to stabilize the ink discharge operation, discharge the ink droplets of an appropriate size, and suppress the occurrence of dot omission and deviation of the ink discharge direction. As a result, a highly reliable ink jet head having excellent printing quality can be realized.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an electrostatic drive type ink jet head incorporating an electrostatic actuator to which the present invention is applied will be described with reference to the drawings.

FIG. 1 is an exploded perspective view of the ink jet head of this embodiment. FIG. 2 is a sectional view of the assembled inkjet head (a sectional view taken along line II-II in FIG. 3), FIG. 3 is a plan view thereof, and FIG.
-IV line cut portion).

As shown in these figures, the ink jet head 1 is of a face ink jet type in which ink droplets are ejected from ink nozzles formed on the upper surface of a substrate. The inkjet head 1 has a three-layer structure in which a cavity plate 3 is sandwiched, a nozzle plate 2 is laminated on an upper side, and a glass substrate 4 is laminated on a lower side.

The cavity plate 3 is, for example, a silicon substrate. On the surface of the plate, a concave portion 7 whose bottom wall forms an ink chamber 6 functioning as a vibration plate 5;
The narrow groove 9 which forms the ink supply port 8 provided behind the concave portion 7 and the concave portion 11 which forms the ink reservoir 10 for supplying ink to each ink chamber 6 are formed by etching. Is formed. The lower surface of the cavity plate 3 is smoothed by mirror polishing.

The nozzle plate 2 joined to the upper side of the cavity plate 3 is formed of, for example, a silicon substrate, like the cavity plate 3. In the nozzle plate 2, a portion defining the upper surface of the ink chamber 6 is provided with a plurality of ink nozzles 21 communicating with each ink chamber 6.
Are formed.

By joining the nozzle plate 2 to the cavity plate 3, the recesses 7, 11 and the narrow groove 9 are closed, and the ink chamber 6, the ink supply port 8, and the ink reservoir 10 are respectively formed. You. A hole 12a for supplying ink to the ink reservoir 10 is provided in a portion defining the bottom surface of the ink reservoir 10, and after the substrate is joined, a hole 12b provided in the glass substrate 4 described later.
At the same time, an ink supply hole 12 is formed. Ink supply hole 12
Is connected to an ink tank (not shown) via a connection tube (not shown). The ink supplied from the ink supply holes 12 is supplied to the independent ink chambers 6 via the respective ink supply ports 8.

Here, the electrostatic actuator is provided in each ink chamber in order to temporarily increase the pressure in each ink chamber and eject ink droplets from the corresponding ink nozzle. Each electrostatic actuator has first and second electrode members opposed to each other with a small gap. In this example, the first electrode member is formed in a concave portion 16 of the glass substrate 4 as described later, and the second electrode member is a deformable diaphragm 5 formed at the bottom of the ink chamber 6. is there.

Next, the glass substrate 4 joined to the lower side of the cavity plate 3 is a borosilicate glass substrate having a thermal expansion coefficient close to that of silicon. In this glass substrate 4,
A concave portion 16 that forms the gap 15 is formed in a portion facing each diaphragm 5. An individual electrode (first electrode member) 17 facing the diaphragm is formed on the bottom surface of the concave portion 16. The individual electrodes 17
It has a segment electrode section 18 made of TO and a terminal section 19.

By joining the glass substrate 4 to the cavity plate 3, the diaphragm 5 defining the bottom surface of each ink chamber 6 and the segment electrode portion 18 of the individual electrode 17 are
They confront each other with a very narrow gap 15 therebetween. This gap 15 is sealed by a sealing material 20 arranged between the cavity plate 3 and the glass substrate 4.

The glass substrate 4 and the cavity plate 3 are bonded by anodic bonding. In the anodic bonding, first, the relative position of the glass substrate 4 and the cavity plate 3 is performed, and after the substrates are superposed, the glass substrate 4 is heated to 340 degrees Celsius in a nitrogen atmosphere.
A voltage of 900 V is applied between the substrate and the glass substrate, and the glass substrate 4 and the cavity plate 3 are joined.

The diaphragm 5 is made thin and has an out-of-plane direction,
That is, it can be elastically deformed vertically in FIG. The vibration plate 5 functions as a common electrode on each ink chamber side. An insulating layer 22 made of SiO2 is formed on the bottom surface 51 of the diaphragm 5 as a common electrode (second electrode member). With each of the diaphragms 5 sandwiching the gap 15,
A counter electrode is formed by each corresponding segment electrode 18.

A voltage applying device 25 is connected between the diaphragm 5 and the individual electrodes 17. One output of the voltage applying device 25 is connected to the terminal 19 of each individual electrode 17, and the other output is connected to a common electrode terminal 26 formed on the cavity plate 3. Since the cavity plate 3 itself has conductivity, a voltage can be supplied from the common electrode terminal 26 to the diaphragm (common electrode) 5.

When a voltage needs to be supplied to the diaphragm 5 with a lower electric resistance, for example, a thin film of a conductive material such as gold is formed on one surface of the cavity plate 3 by vapor deposition or sputtering. do it. In this example, since the anodic bonding is used to connect the cavity plate 3 and the glass substrate 4, a conductive film is formed on the channel forming surface side of the cavity plate 3.

In this case, the segment electrode portion 18 of the individual electrode 17 made of ITO of the ink jet head 1 of the present embodiment has, as an ITO film to be applied, a structure in the (222) direction and the (400) direction of the crystal orientation of the ITO film. Ratio (22
2) / (400) is 5 to 0.5.

After the anodic bonding is completed, the bonded glass substrate 4 and cavity plate 3 are exposed to nitrogen at a certain concentration of H.
MDS (hexamethyldisilazane) was vaporized and allowed to stand for a certain period of time in an atmosphere in which HM
DS is introduced, and then sealed with the sealing material 20.

The HMDS comprises a diaphragm 5 and a segment electrode 1
When the electrostatic actuator 8 is driven, the vibrating plate 5 and the segment electrode portion 18 are separated by the surface water adhered to the surface of the diaphragm 5 and the segment electrode portion 18 facing each other with the gap 15 therebetween.
Is introduced into the gap 15 and hermetically sealed in order to prevent the gas from adsorbing and becoming inoperable. Here, the HMDS has a function of chemically replacing surface water, which has remained after the anodic bonding, on the surface of the insulating film 22 and the surface of the segment electrode portion 18 by chemically replacing the HMDS. This H
With MDS, it is possible to ensure durability by driving the electrostatic actuator and the electrostatic inkjet head.

In the ink jet head 1 having this configuration, when the driving voltage from the voltage applying device 25 is applied between the opposing electrodes, Coulomb force is generated by the electric charge charged between the opposing electrodes, and the diaphragm 5 The ink chamber 5 is bent toward the electrode section 18 and the volume of the ink chamber 5 is increased. Next, when the drive voltage from the voltage applying device 25 is released and the electric charge between the opposing electrodes is discharged, the diaphragm 5 is restored by its elastic restoring force, and the volume of the ink chamber 6 is rapidly reduced. Due to the change in the internal pressure generated at this time, a part of the ink stored in the ink chamber 6 is ejected from the ink nozzle 21 communicating with the ink chamber 6 toward the recording paper.

When the voltage application and release between the opposing electrodes are repeated by the voltage applying device 25 in this manner, the diaphragm 5 as the common electrode is repeatedly interposed via the insulating film 22 to form the segment electrode portion 18 of the individual electrode. Contact the surface. As a result, contact charging occurs on the surface of the insulating film 22, and even if the application of the driving voltage is stopped, a predetermined amount of charge remains between the opposed electrodes without being discharged.

The residual charges become charged on the surface of the insulating film 22 and make the operation of the diaphragm 5 unstable when applying and releasing a voltage between the opposing electrodes.
Makes the ejection of the ink droplets unstable. As a result, excessive ink droplets may be ejected.

Further, the charge remaining due to the contact charging generates a weak discharge between the surface of the insulating film 22 and the segment electrode portion 18 of the individual electrode when the voltage is applied to and released from the opposing electrodes. There are cases. When the discharge is repeatedly generated by repeatedly applying and releasing the voltage between the opposed electrodes,
The organic film such as HMDS adhered to the surface inside the gap 15 gradually becomes foreign matter by the discharge. The vibrating plate 5 becomes inoperable due to the organic film converted into foreign matter by the discharge, and the ink jet head 1 cannot discharge ink droplets. The repetition of the above-described discharge of the contact charging causes malfunction of the electrostatic actuator and the electrostatic ink jet head, and it has been difficult to secure a stable operation of the electrostatic actuator for a long period of time.

In this embodiment, however, the segment electrode portion 18 of the individual electrode is formed of an ITO film, and the ITO film to be applied has a crystal orientation (22) of the ITO film.
2) composition ratio between (400) and (400) directions (222) / (40)
0) is 5 to 0.5. When this ITO film was used as an individual electrode, it was confirmed that contact charging on the surface of the insulating layer was suppressed, discharge was also suppressed, and stable ink ejection characteristics could be obtained over a long period of time.

FIG. 5 shows the experimental results of the present inventors. With respect to the six types of ink jet heads 1, ITO films having different composition ratios of the crystal orientation of the ITO crystal are used for the segment electrode portions 18 of the individual electrodes, the composition ratio of the crystal orientation of the ITO crystal of the ITO film, and the charging of the electrostatic actuator. The results of investigating the characteristics and durability of the electrostatic inkjet head are shown. The details are described below.

The ITO film applied to the individual electrode segment 18 of the ink jet head 1 is formed by DC magnetron sputtering. The ITO film uses two types of ITO targets having different relative densities,
The TO film was formed by changing the glass substrate temperature and the oxygen inflow amount, which are the conditions for forming the TO film.

The composition ratio of the crystal orientation of the ITO film is ITO
The composition ratios in the (222) direction and the (400) direction, which are the crystal orientations of the crystal, are shown. The composition ratio of (222) / (400) crystal orientations is obtained by quantifying the amount of crystals in each crystal orientation by counting the amount of X-ray diffraction per second at an angle corresponding to the crystal plane using a scintillation counter. The ratio is shown as a quantitative value. These measurements were made with an X-ray diffractometer.

The ratio (222) / (400) indicates which of the crystal grains constituting the ITO film, the (222) direction and the (400) direction, are larger. When the ratio (222) / (400) exceeds 1, among the ITO crystal grains constituting the ITO film, the IT (222) direction
It means that the O crystal is more than the ITO crystal in the (400) direction. At the same time, the dominant crystal orientation constituting the ITO crystal of the ITO film is at least the (400) direction.
Indicates that it is not an O crystal. ITO constituting the ITO film
Most of the crystals are ITO crystal of (222) direction and (400)
When composed of ITO crystals in different directions, the ratio (222)
If / (400) exceeds 1, the IT value of the ITO film
This indicates that the dominant crystal orientation of the O crystal is the (222) direction.

The charging characteristics of the electrostatic actuator indicate the evaluation results of the unstable behavior of the electrostatic actuator due to charging and the discharge of unnecessary ink droplets of the electrostatic inkjet head due to the unstable operation. The mark “特性” in the charging characteristic indicates that the behavior of the electrostatic actuator was stable and no unnecessary ink droplets were ejected by the electrostatic inkjet head. In addition, "x" in the charging characteristics indicates that the electrostatic actuator behavior was unstable and ejection of unnecessary ink droplets was confirmed by the electrostatic inkjet head.

Further, the durability of the electrostatic ink-jet head depends on the amount of ink droplets to be ejected, that is, the number of times of repetition of voltage application and release between the opposing electrodes required for the electrostatic ink-jet head. This indicates whether the ejection characteristics of ink droplets are stable for a long period of time. ○ for durability
It means that the ejection characteristics of the ink droplets were stable with respect to the required number of repetitions of voltage application and release. On the other hand, it indicates that the ejection characteristics of the ink droplets have changed or deteriorated during the repetition. Incidentally, voltage application required for the inkjet head 1 in the present embodiment,
The number of release cycles is 2.4 billion cycles,
And x were evaluated.

When the required durability is about 100 million cycles, the durability evaluation result in the experimental results shown in FIG. 5 becomes な る with respect to the composition ratio of all (222) / (400) crystal orientations tested. .

Here, in order to ensure the stability of the ejection characteristics of the ink droplets of the ink jet head 1 and the printing quality, the charging characteristics must first be ○. Furthermore, in order to secure the required durability, the durability must be 性. In order to secure charging characteristics and secure stable ejection characteristics of ink droplets, it is necessary to set the crystal orientation composition ratio (222) / (400) to 0.2 or more, and preferably to conduct experiments by the inventors. It is necessary to set the composition ratio to 0.5 or more as a composition ratio that can be confirmed by the result. In order to achieve both charging characteristics and durability, the composition ratio (222) / (400) of the crystal orientation needs to be around 0.5.

From these results shown in FIG. 5, as the ITO film applied to the segment electrode portion 18 of the individual electrode, the composition ratio of the crystal orientation of the ITO crystal (222) / (40
It can be confirmed that by applying an ITO film having 0) of 0.5 or more, stable ink ejection characteristics can be obtained over a long period of time.

Further, when the ITO film is formed by DC magnetron sputtering, the composition ratio (222)
As conditions for forming the ITO film so that / (400) becomes 0.5 or more, it is necessary to maintain the temperature of the glass substrate at 350 ° C. or less and appropriately set the oxygen introduction flow rate. It can be confirmed that there is.

Therefore, in the present embodiment, as the ITO film applied to the ink jet head 1, the composition ratio of the crystal orientation of the ITO film in the (222) direction and the (400) direction is (22).
2) / (400) is adjusted to 5 to 0.5, and the glass temperature is set to 280 degrees Celsius as a condition for forming the ITO film.
Degrees to 350 degrees, and other conditions such as the oxygen introduction flow rate were appropriately set.

When the durability of the ink-jet head 1 is more important, the crystal orientation of the ITO film (222) /
(400) is close to 0.5, and ITO for that
As a film forming condition, the glass temperature was maintained at a temperature around 350 degrees Celsius, and other conditions such as the amount of inflow of oxygen were set appropriately.

When more importance is placed on the stability of the ink droplet ejection of the ink jet head 1, the contact charge on the surface of the insulating layer 22 can be further suppressed by using an IT
The composition (222) / (400) of the crystal orientation of the O film is 1 or more, or the dominant crystal orientation of the ITO crystal of the ITO film is the (222) direction.
A glass temperature of 350 degrees Celsius or a film forming condition
The temperature was kept at 280 ° C. or lower, and other conditions such as the inflow of oxygen were set appropriately.

According to an experiment by the present inventors, when an ITO film is formed by DC magnetron sputtering, a glass substrate temperature is set to 350 degrees Celsius as a film forming condition.
It was confirmed that an ITO film in which the crystal orientation (222) direction was dominant could be formed by keeping the temperature at or below and appropriately setting other conditions such as the oxygen introduction flow rate.

(Other Embodiments) The above-described ink jet head is of a face ink jet type in which ink droplets are ejected from ink nozzles provided on the upper surface of a substrate. Instead, the present invention can of course be applied to an edge inkjet type in which ink is ejected from an ink nozzle provided at an end of the substrate.

Although the above example is an example in which the present invention is applied to an ink jet, the present invention can be applied to an electrostatic actuator other than an ink jet head.
For example, the present invention can be similarly applied to a micromechanical device, a display device using an electrostatic actuator, a micropump, and the like as disclosed in JP-A-7-177763.

Further, the present invention can be similarly applied to an electrostatic sensor which detects a voltage change generated between the opposed electrodes as a relative displacement of the opposed electrodes. The term “electrostatic actuator” in this specification is used as having a broad meaning including the detection unit of such an electrostatic sensor.

[0059]

As described above, in the electrostatic actuator according to the present invention, the first and second opposed-positioned actuators are provided.
One of the electrode members is formed of an ITO film, and the crystal orientation of the ITO film is (22).
2) composition ratio between (400) and (400) directions (222) / (40)
0) is 5 to 0.5.

According to such an electrostatic actuator, contact electrification generated on the surfaces of the first and second electrode members is suppressed, and a highly reliable and stable driving state can be maintained for a long time.

According to the ink jet head of the electrostatic drive type to which the present invention is applied, contact charge generated on the surface of the counter electrode can be suppressed, so that the amount and direction of ink droplets ejected from the ink nozzles are stable. In addition, since the separation of the ejected ink droplets is stabilized, the generation of extra ink droplets and unnecessary ink mist can be prevented. So for a long time,
A reliable inkjet head with excellent print quality can be realized.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an inkjet head to which the present invention has been applied.

FIG. 2 is a schematic longitudinal sectional view of the inkjet head of FIG.

FIG. 3 is a plan view of the inkjet head of FIG. 1;

FIG. 4 is a schematic cross-sectional view showing a part of the inkjet head of FIG.

FIG. 5 is a diagram showing experimental results using an inkjet head to which the present invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet head 2 Nozzle plate 3 Cavity plate 4 Glass substrate 5 Vibration plate (2nd electrode member) 6 Ink chamber 15 Gap 17 Individual electrode (1st electrode member) 18 Segment electrode part (ITO film) 21 Ink nozzle 22 Insulation film 25 Voltage application device

Claims (10)

[Claims] A first electrode member and a second electrode member that are relatively displaceable and that are opposed to each other at a predetermined interval; and a driving unit that generates an electrostatic force between the electrode members to relatively displace the electrode members. Wherein the first electrode member is formed of an ITO film, and the ITO film has a composition ratio (222) / (400) of the crystal orientation of the ITO crystal of 0.5 or more. An electrostatic actuator, comprising: 2. The electrostatic actuator according to claim 1, wherein the ITO film has a dominant crystal orientation of the ITO crystal other than (400). 3. The electrostatic actuator according to claim 1, wherein the ITO film has a dominant crystal orientation of (222) in the ITO film. 4. The method according to claim 1, wherein the first electrode member is formed on a surface of a rigid glass substrate, and the second electrode member is a diaphragm made of a silicon substrate. An electrostatic actuator, wherein at least one surface of the first and second electrode members is covered with an insulating layer. 5. The electrostatic actuator according to claim 4, wherein the ITO film is formed by a DC magnetron sputtering method under a condition that the temperature of the glass substrate is 350 ° C. or less. 6. An ink nozzle, an ink chamber communicating with the ink nozzle, a vibrating plate made of a silicon substrate forming a part of the ink chamber, and opposed to the vibrating plate with a constant gap. Having a counter substrate and an electrode formed on the surface of the counter substrate, wherein the diaphragm is released by electrostatic attraction by electrostatic force generated between the diaphragm and the electrode to release the ink. In an electrostatic ink jet head for ejecting ink droplets from a nozzle, the electrode formed on the surface of the counter substrate is formed of an ITO film, and the ITO film has a composition ratio of the crystal orientation of the ITO crystal (222) / (400) is 0.5 or more. 7. The electrostatic ink jet head according to claim 6, wherein the ITO film has a dominant crystal orientation of the ITO crystal other than (400). 8. The electrostatic ink jet head according to claim 6, wherein the ITO film has a dominant crystal orientation of (222) in the ITO film. 9. The electrostatic ink jet head according to claim 6, wherein the electrode is formed on a surface of a glass substrate, and the surface of the electrode is covered with an insulating layer. 10. The electrostatic ink jet head according to claim 9, wherein the ITO film is formed by a DC magnetron sputtering method under the condition that the temperature of the glass substrate is 350 ° C. or less. .