JP2002137389A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high speed ink jet head which can print out a high quality image stably and can be driven with a low voltage. SOLUTION: In an ink jet head ejecting an ink liquid drop from a nozzle by deforming a diaphragm with electrostatic force thereby varying the volume of a pressure chamber, protrusions 12 are formed on the side of the diaphragm 11 facing the electrode side 21 in an actuator section 1 such that the protrusions 12 touch the upper surface on the electrode side 21 upon deformation of the diaphragm 11. An electrode 23 is provided at a specified part on the upper surface of an electrode substrate 22 on the electrode side 21. A specified part on the electrode side 21 is a non-electrode part where a slit-like groove is made so that the initial volume at the actuator section increases and the protrusions 12 touch the non-electrode part upon deformation of the diaphragm 11. Height of the protrusion is preferably set at 0.03 μm or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head of a drop-on-demand type ink jet recording apparatus which forms and discharges ink droplets only when recording is required and performs ink recording on a desired recording medium. In particular, the present invention relates to a structure of a recording head of an ink jet recording apparatus that discharges ink using electrostatic force. An application field of the present invention includes a recording head in a recording apparatus such as a copying machine, a facsimile, a printing machine, and a printer.

[0002]

2. Description of the Related Art An ink jet recording apparatus does not require a process such as development and fixing and can perform non-contact recording, so that noise during recording is extremely low, high-speed printing is possible, and the degree of freedom of ink is high. It has many advantages, such as the ability to use expensive and inexpensive plain paper. Among them, the so-called drop-on-demand method (ink-on-demand method), which discharges ink droplets only when recording is necessary, does not require the collection of ink droplets unnecessary for recording. It has been attracting attention because it is easy to use, the device configuration is small and the cost is low.

[0003] The ink-jet head of the drop-on-demand system includes, for example, Japanese Patent Publication No. 2-51734.
As shown in Japanese Patent Application Laid-Open No. H11-59911, there is a method in which the driving means is a piezoelectric element, and as shown in Japanese Patent Publication No. 61-59911, a method in which ink is ejected by heating ink to generate bubbles. .

In an ink jet head disclosed in Japanese Patent Application Laid-Open No. 3-23437, an ink is ejected by vibrating a vibration plate by using an electrostatic force as a driving means. This method has the advantages of small size, high density, high printing quality and long life. Further, for example, Japanese Patent Application Laid-Open No. 5-506
No. 01, the head using electrostatic force, in a medium substrate made of silicon, a nozzle, a discharge chamber, a recording body cavity and a vibrating plate are formed by etching,
An upper substrate having a recording material supply port and a lower substrate having electrodes provided opposite to the vibration plate are integrated, and an electric field is applied between the vibration plate and the electrodes to vibrate the vibration plate to form ink. Discharge is performed.

In a head using an electrostatic force, the electrostatic force is proportional to the square of the applied voltage, and is inversely proportional to the distance between the diaphragm and the electrode or the square of the distance between the diaphragm and the insulating film. Therefore, when the inkjet is driven at a low voltage, it is necessary to shorten the distance between the diaphragm and the electrode or the distance between the diaphragm and the insulating film. However, when the actuator section is sealed, the shorter the distance, the greater the effect of the increase in the internal pressure of the actuator section due to the displacement of the diaphragm.

Further, in Japanese Patent Application Laid-Open No. 7-299908, the volume excluded by the displacement and the volume of the actuator portion are limited to the range of 1: 2 to 1: 8, and the volume of the groove in which the wiring portion is formed is defined. The volume of the actuator section is increased by using the volume. However, there is a restriction that the capacity of the wiring portion is secured, and there is a problem that an unnecessary wiring portion must be manufactured. Further, at the time of high-speed driving, air accumulates inside the actuator section, pressure is not transmitted to the wiring section, and the effect of alleviating the increase in the internal pressure of the actuator section cannot be obtained.

Further, in Japanese Patent Application Laid-Open No. H11-34319, the internal pressure rise due to the displacement of the diaphragm is reduced by increasing the volume of the actuator portion which is not directly below the diaphragm. However, in order to sufficiently reduce the rise of the internal pressure, it is necessary to form a space in a portion other than the diaphragm, and thus there is a problem that downsizing is difficult.

FIG. 7 is a front sectional view showing the structure of a main part of an example of a conventional ink jet head.
This will be described with reference to FIG. This ink jet head includes a nozzle (nozzle hole) 61 for discharging ink, a pressurized liquid chamber 62 and a common ink channel 63 communicating with the nozzle.
A vibrating plate 64 forming a pressurized liquid chamber 62 and an actuator portion 66 including an electrode side 65 facing the vibrating plate. The electrode side 65 includes an electrode substrate 65a and an electrode (individual electrode) 65b provided on the electrode substrate.

As described above, the actuator section 66 includes the electrode substrate 65a, the electrode 65b provided thereon, and the diaphragm 64. The pressurized liquid chamber 62 includes a vibration plate 64, a side wall portion 67 above the diaphragm 64, and a lid member 68 above the diaphragm 64.
Is formed, and the pressurized liquid chamber 62 communicates with the common ink channel 63 via the fluid resistance 69. If the opening 70, which is the end of the gap between the diaphragm 64 and the electrode side 65, is left open, foreign substances such as dust in the atmosphere may enter the actuator section. The opening 70 is sealed with an insulating resin 71. However, the following problems occur due to the sealing of the opening.

In recording by the ink-jet head, an electric field is generated between the diaphragm 64 and the electrode 65b in the actuator section 66, and the diaphragm 64 is deformed by an electrostatic force, so that the volume of the pressurized liquid chamber 62 is increased. And supplies ink to the pressurized liquid chamber 62 via the common ink channel 63 and the fluid resistance 69. Then, when the electric field disappears, the diaphragm 64 returns to its original shape due to its restoring force. At this time, since the volume of the pressurized liquid chamber 62 also returns (decreases) to the original, ink is ejected from the nozzle 61.

Next, the relationship between the electrostatic force and the amount of displacement of the vibration plate in an ink jet head which discharges ink by vibrating the vibration plate using the electrostatic force for the driving means as shown in FIG. 7 will be described. I do. When the diaphragm is used as a common electrode and a voltage is applied between the common electrode and the individual electrode, an electrostatic force is generated which is inversely proportional to the square of the distance between the diaphragm and the electrode. The diaphragm is pulled by the electrostatic force and displaces until the restoring force and the electrostatic force balance.

The displacement is about 1/3 of the distance between the diaphragm and the electrode
If the vibration force exceeds the restoring force, the electrostatic force becomes larger than the restoring force, and the diaphragm is displaced to a position where it contacts the electrode. When the diaphragm is displaced until it comes into contact with the electrode, the displacement of the diaphragm increases, but an impact force is applied to the diaphragm or electric charges remain on the insulating film. There has been a problem that the diaphragm cannot return and the amount of displacement decreases.

As described above, the diaphragm 64 and the electrode 6
When the opening 70 between the five is sealed, the diaphragm receives a pressure due to a volume change of the actuator unit in addition to the restoring force and the electrostatic force. Then, due to the increase in the pressure inside the actuator section, the diaphragm is displaced to a point where the sum of this pressure and the restoring force balances the electrostatic force, and as a result, the displacement amount of the diaphragm decreases. In order to obtain the amount of displacement of the diaphragm required for ink ejection, it is necessary to generate an electrostatic force that balances the rise in pressure.

As described above, when the opening 70 is sealed, the driving voltage must be increased. To lower the driving voltage when the opening 70 is sealed, the pressure inside the actuator section must be increased. It needs to be suppressed. The pressure increase in the actuator section is determined by the ratio of the volume Va of the actuator section in an initial state where no voltage is applied to the volume Vb after the diaphragm is displaced: Va / Vb. For this reason, in order to suppress the pressure rise in the actuator section, there is a problem that the volume of the actuator section in the initial state must be increased.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide an ink jet head capable of stably printing a high-quality image. Is to provide. It is an object of the invention according to claims 2 and 3 to provide an ink jet head capable of stably printing a high-quality image and capable of driving at a low voltage. It is another object of the present invention to provide an ink jet head which can print a high quality image stably, can be driven at a low voltage, and has a high printing speed.

[0016]

According to a first aspect of the present invention, there is provided an ink jet head comprising: a nozzle for discharging ink;
A liquid chamber including an ink flow path and a pressurized chamber communicating with the nozzle, a vibration plate provided in a part of the flow path, and an actuator section including an electrode side facing the vibration plate; The side is composed of an electrode substrate and electrodes provided on the electrode substrate, the diaphragm is deformed by using an electrostatic force generated by generating an electric field between the diaphragm and the electrodes, and the volume of the pressure chamber is changed. In an ink jet head configured to eject ink droplets from the nozzle by a change, a protrusion is formed on a surface of the diaphragm facing the electrode side,
When the diaphragm is deformed, the projection comes into contact with the electrode side.

According to a second aspect of the present invention, there is provided the ink jet head according to the first aspect, wherein an appropriate portion of the electrode substrate is a non-electrode portion, and the projection comes into contact with the non-electrode portion when the diaphragm is deformed. .

According to a third aspect of the present invention, the height of the projection is set to 0.03 μm or more.

According to a fourth aspect of the present invention, in the ink jet head according to the second or third aspect, a slit-shaped groove is formed at an appropriate position on the upper surface side of the electrode substrate, and the vicinity of the groove is used as a non-electrode portion. It is characterized by the following.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment (According to Claim 1) FIG. 1 is a front sectional view showing a structure of an actuator section constituting an ink jet head. The actuator section 1 includes a vibration plate 11 and an electrode side 21. The electrode side 21 includes an electrode substrate 22 and an electrode 23 provided on an upper surface thereof.
(More precisely, individual electrodes). The actuator section 1 has a projection 12 formed on the surface of the diaphragm 11 on the side facing the electrode side 21, and when the diaphragm 11 is deformed by driving the actuator section 1, the projection 12 is moved to the electrode side 21.
(The electrode 23 or its vicinity) is different from the conventional actuator portion in that it comes into contact with the electrode portion.

In FIG. 1, reference numeral 20a denotes an opening, and reference numeral 2 denotes an opening.
Reference numeral 0b denotes an insulating resin sealing this opening. The other parts of the structure of the ink jet head are the same as those shown in FIG. For example, the pressurized liquid chamber (not shown) includes the vibrating plate 11, a side wall portion above the diaphragm, and a lid member further above the diaphragm 11, and a nozzle is formed on the lid member.

The recording operation of this ink jet head is the same as the conventional one except that the projection 12 comes into contact with the electrode side 21 when the diaphragm 11 is deformed. By forming the protrusions 12 on the diaphragm 11 in this way and making the protrusions 12 contact the electrode side 21 when the diaphragm 11 is deformed, the area of the diaphragm 11 contacting the electrode side 21 is reduced, 1
Since the impact force applied to 1 is reduced, a high-quality image can be stably printed.

Next, the manufacturing process of the above-mentioned ink jet head will be described. When forming the electrode 23, a single crystal silicon substrate as a material of the electrode substrate 22 is prepared, and anisotropic etching is performed using a mask on which the electrode is patterned, so that an electrode groove is formed on the single crystal silicon substrate. After forming the (concave portion), the electrode groove is filled with a metal material such as Al, Cr, Ni or the like, a semiconductor material doped with impurities, a conductive ceramic material (for example, titanium nitride) or the like as an electrode material. Individual electrode) 2
3 is assumed. As the electrode substrate 22, a substrate made of glass, ceramics, or the like can be used in addition to the single crystal silicon substrate. When a single crystal silicon substrate is used, it is necessary to form an insulating film such as SiO ₂ between the electrode substrate 22 and the electrode 23.

Similarly, a diaphragm 11 (common electrode side) having a protrusion 12 on one surface is formed by performing anisotropic etching on a single crystal silicon substrate as the diaphragm substrate.
In order to form the projection 12, for example, the following method is adopted. A single crystal silicon substrate as a diaphragm substrate is heat-treated in an oxidizing atmosphere to form an insulating film (silicon oxide film: SiO ₂ ) on the substrate. After a resist film is formed at a place where the insulating film is to be left, only the insulating film can be etched by using a hydrofluoric acid-based etching solution (BHF) as an etching solution. 12 are formed. According to this method, a groove having a depth equal to the thickness of the insulating film, and thus a projection having a height equal to the thickness of the insulating film, can be formed with high accuracy. Then, this diaphragm 11
And the electrode substrate 22 on which the individual electrodes 23 have been formed are joined by direct joining (direct joining between single crystal silicon substrates).

As a diaphragm substrate, a single crystal silicon substrate is often used. Another method for forming a silicon diaphragm is to diffuse impurities in advance,
There are a method of stopping etching at a desired thickness electrochemically and a method of using SOI. The thickness of the diaphragm is usually
It is set in the range of 1 to 20 μm.

It should be noted that direct bonding can be used as described above for bonding the electrode substrate made of single-crystal silicon and the diaphragm substrate made of single-crystal silicon. As a bonding method with the substrate, solid-phase bonding that can increase positional accuracy at the time of bonding can also be used. In this solid-phase bonding, anodic bonding can be performed by applying an electric field of several hundred volts at a temperature of 300 ° C. using borosilicate glass for the electrode substrate.

The pressurized liquid chamber forms a common ink flow path and a fluid resistance connected to an ink tank (not shown) on the same single crystal silicon substrate as the vibration plate 11, and is provided in contact with a lid member. Thus, the pressurized liquid chamber can be formed with a simple configuration. The pressurized liquid chamber may be formed by stacking a plurality of substrates. After assembling the ink jet head, the electrode 23 is connected to an unillustrated FPC. At this time, the opening 20a formed between the vibration plate 11 and the electrode 23 is sealed with an insulating resin 20b in order to prevent foreign matter from entering and contaminating the gap between the diaphragm 11 and the electrode 23.

Second Embodiment (According to Claims 2 and 3) FIG. 2 shows the structure of an actuator section constituting an ink jet head. FIG. 3 is a front sectional view when viewed from above. (B) is a bottom view of the diaphragm. The meaning of the above “short side” is shown in FIG.
It is clear when referring to (b). FIG. 3 is a diagram for explaining the operation of the actuator section, and is a front sectional view when the actuator section is viewed from the short side when a voltage is applied.

The actuator section according to the present embodiment comprises:
As shown in FIGS. 2A and 2B, the projections 12
In addition, an appropriate portion of the upper surface of the electrode substrate 22 facing the protrusion 12 is formed as a non-electrode portion 24 so that the protrusion 12 comes into contact with the non-electrode portion 24 when the diaphragm 11 is deformed. That is, by leaving a part of the upper surface of the electrode substrate 22 as a substrate as shown in FIG.
As shown in the figure, when the actuator unit 1 operates,
The projections 12 are in contact with the non-electrode portions 24, so that the diaphragm 11 is not in contact with the electrodes 23, thereby enabling stable ink ejection. The protrusion 12
The electrodes 23 can be formed by the method described in the first embodiment.

More specifically, when a voltage is applied to the actuator section 1 shown in FIG. 2, first, the projection 12 comes into contact with the electrode side 21 of the substrate portion on which the electrode is not formed. When the voltage is further increased, the diaphragm between the protrusions 12 comes into contact with the electrode 23. If the width of the projection 12 is too wide, the electrode area decreases and the generated electrostatic force also decreases. Therefore, it is preferable that the width of the projection be about several μm.
The formation position of the protrusion 12 in the short side direction (FIG. 2B) is determined by the center of the short side direction of the diaphragm 11 and the short side length of the diaphragm.
The projection 12 comes into contact with the above-mentioned substrate portion on the electrode side 21 before the diaphragm 11 is displaced when the diaphragm 11 is displaced by providing a plurality of positions in the long side direction between the positions と and / 3. .

Although the number of the projections 12 is not limited to the illustrated example, by setting it to 2 to 5 in the short side direction,
It is desirable to prevent the drive voltage of the actuator unit 1 from increasing. When the height of the projections 12 is less than 0.03 μm, unless the interval between the projections is set to about several μm, the projections 12 contact the electrode side 21 and at the same time the diaphragm portion between the projections 12 and 12 contacts the electrode 23. May occur. Therefore, by setting the height of the protrusion to 0.03 μm or more and forming two to five protrusions 12 in the short side direction of the vibration plate 11, the voltage at which the protrusion 12 contacts the electrode side 21 is reduced, and the vibration is reduced. The voltage at which the plate 11 contacts the electrode 23 can be increased.

Third Embodiment (According to Claim 4) FIG. 4 shows a structure of an actuator section constituting an ink jet head, and is a front sectional view when the actuator section is viewed from a short side. (Cross-sectional view along line BB in FIG. 5)
It is. FIG. 5 is a plan sectional view taken along line AA of FIG. In the actuator section of FIG. 2, the non-electrode section 24 is formed by the electrode substrate 22, whereas in the actuator section 1 shown in FIG. 4, the non-electrode section 31 is formed by a pair of plate members 32 made of a non-conductive material. 32.

More specifically, the projections 12 are formed on the vibration plate 11, and a pair of plate-like members 32, 32 made of plastic (for example, DFR) are placed parallel to each other where the projections 12 on the electrode side 21 contact. The volume (initial volume) of the actuator section is increased by forming a slit-like groove (gap) 33 between these plate-like members 32, 32 by inserting them in a state where they face each other. .
As shown in FIG. 5, the groove 33 is formed parallel to the long side of the diaphragm 11. Also, as shown in FIG. 4, by making the width Ws of the groove 33 smaller than the width Wt of the protrusion 12,
Does not enter the groove 33.

The formation of the groove 33 suppresses a rise in pressure in the actuator section, and enables low-voltage driving. When the actuator 1 is operated, the projection 12 of the vibration plate 11 contacts at least one of the upper end surfaces of the pair of plate members 32, but does not contact the electrode 23.

Instead of forming the groove 33 by the plate-like members 32, 32, a slit-like groove is formed on the upper surface of the electrode substrate 22 before the electrodes are provided, and an electrode of appropriate width is formed on both sides of the groove. The substrate portion may be left in a streak shape (this portion corresponds to the plate-like member), and electrodes may be provided on other portions of the upper surface of the electrode substrate.

Next, the effect of suppressing the pressure rise in the actuator portion by forming the slit-like groove 33 will be described. For example, when the width of the diaphragm is 100 μm, the length of the diaphragm is 1000 μm, and the distance between the diaphragm and the electrode side is 0.3 μm, the initial volume of the actuator section is 30 pl. When the diaphragm is displaced by a maximum of 0.5 μm, the volume of the actuator section is reduced to 14 pl. At this time, the pressure in the actuator section increases by one atmosphere. The applied voltage required to obtain a maximum displacement of the diaphragm of 0.5 μm is 1 unit higher than when the opening is open.
It rises by 0V or more.

On the other hand, when four grooves having a width of 2.8 μm, a depth of 1.3 μm and a length of 1000 μm are formed on the electrode side, the initial volume of the actuator portion increases to 47 pl,
Even when the maximum displacement of the diaphragm is 0.5 μm, the pressure rise in the actuator section is 0.48 atm, and the degree of pressure rise is reduced to about の of the case where the groove is not formed. Thus, it is possible to suppress an increase in the ink discharge voltage due to the sealing of the opening.

Further, as shown in FIG. 4, the advantage of forming the groove 33 at a position adjacent to the electrode 23 on the electrode side 21 is as follows. Since there is no need to separately provide a space for adjusting the volume of the actuator section, the head can be made compact. In the case where the space for adjustment is separately provided, air moves in a very narrow space of the order of μm, so that it takes time to move air. However, in the actuator section of the present embodiment, the pressure increases. The pressure is reduced in a short time because the distance between the location and the space for adjusting the volume of the actuator section is short. This is particularly advantageous when the inkjet head is driven at a high speed.

Fourth Embodiment (According to Claim 4) FIG. 6 is a plan view of an electrode constituting an actuator section. The actuator section 1 is configured such that electrodes are not provided in a rectangular region 41 of the electrode substrate 22 and the electrode substrate is left as it is, and a large number of stripe grooves 42 are formed on the surface of the region 41. The structure of the other parts and the operation and effect of this actuator portion are the same as those in FIG. In addition, the streak groove 4
Instead of 2, a circular groove may be formed.

Hereinafter, examples of the present invention and comparative examples will be described. Example 1 A diaphragm 11 and an electrode side 21 having the shape shown in FIG. In this case, the diaphragm had a width of 100 μm and a length of 1000 μm. An oxide film is formed on the surface of the single crystal silicon substrate, and is etched into a predetermined pattern, so that a height of 0.1 mm is obtained.
A projection of 04 μm and a width of 5 μm was formed at a position 30 μm from both ends in the short side direction of the substrate. A recording apparatus was constructed by mounting the inkjet head, and a pulse wave of a maximum voltage of +25 V was applied to the actuator section 1 as an applied voltage. As a result, the maximum displacement of the diaphragm was 0.245 μm.
m. Further, even after repeated vibrations, no decrease in displacement was observed.

Comparative Example 1 An ink jet head was produced in the same manner as in Example 1 except that the above-mentioned projection was not provided. When a pulse wave having a maximum voltage of +30 V was applied as an applied voltage to the actuator section, the maximum displacement of the diaphragm became 0.25 μm. However, the displacement amount decreased during repeated vibrations.

Comparative Example 2 An ink jet head was manufactured in the same manner as in Example 1 except that the height of the projection was changed to 0.01 μm. When a pulse wave having a maximum voltage of +25 V was applied as an applied voltage to the actuator section, the maximum displacement of the diaphragm became 0.025 μm. However, the displacement decreased as the vibration was repeated.

Example 2 As shown in FIG. 4, an ink jet head having an actuator section having two slit-like grooves having a width of 2.5 μm and a depth of 1.3 μm was prepared, and the ink jet head was mounted thereon for recording. The device was configured. When a pulse wave having a maximum voltage of +28 V was applied as an applied voltage to the actuator section, a maximum displacement of 0.245 μm was obtained. Further, according to the recording apparatus, low-voltage driving is possible, and high-quality images can be recorded at high speed.

[0044]

As is apparent from the above description, claim 1
In the ink jet head described in (1), a projection is formed on the diaphragm, and when the voltage is applied, the projection is configured to contact the electrode side, so that the area of the diaphragm that contacts the electrode side is reduced. Since the impact is reduced, a high-quality printed image can be stably obtained.

In the ink jet head according to the second aspect of the present invention, an appropriate portion of the electrode substrate is formed as a non-electrode portion, and the projection comes into contact with the non-electrode portion when the diaphragm is deformed.
In addition to the effect of the first aspect, low-voltage driving becomes possible.

In the ink jet head according to the third aspect, by setting the height of the projection to 0.03 μm or more,
In addition to the effect of the first aspect, low-voltage driving becomes possible.

In the ink jet head according to the fourth aspect, a slit-shaped groove is formed at an appropriate position on the upper surface side of the electrode substrate, and the vicinity of the groove is formed as a non-electrode portion, so that a high-quality image is formed. Can be printed stably, low-voltage driving is possible, and the printing speed is increased.

[Brief description of the drawings]

FIG. 1 is a front cross-sectional view illustrating a structure of an actuator section included in an inkjet head according to a first embodiment of the present invention.

FIGS. 2A and 2B show the structure of an actuator section constituting an ink jet head according to a second embodiment of the present invention, wherein FIG. 2A is a front sectional view when the actuator section is viewed from a short side; (B) is a bottom view of the diaphragm.

FIG. 3 is an operation explanatory view of the actuator section shown in FIG. 2, and is a front sectional view when the actuator section is viewed from a short side when a voltage is applied.

FIG. 4 is a front cross-sectional view showing the structure of an actuator section constituting an inkjet head according to a third embodiment of the present invention, when the actuator section is viewed from a short side (B in FIG. 5). FIG.

FIG. 5 is a plan sectional view taken along line AA of FIG. 4;

FIG. 6 is a plan view showing the structure of an actuator section constituting an inkjet head according to a fourth embodiment of the present invention, which is on the electrode side.

FIG. 7 is a front sectional view showing a configuration of a main part of a conventional inkjet head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Actuator part 11 Vibration plate 12 Projection 20a Opening 20b Insulating resin 21 Electrode side 22 Electrode board 23 Electrode (individual electrode) 24 Non-electrode part 31 Non-electrode part 32 Plate-shaped member 33 Slit-shaped groove (gap) 41 Rectangular Area 42 streak groove 61 nozzle (nozzle hole) 62 pressurized liquid chamber 63 common ink flow path 64 vibrating plate 65 electrode side 65a electrode substrate 65b electrode (individual electrode) 66 actuator part 67 side wall part 68 lid member 69 fluid resistance 70 Opening 71 Insulating resin

Claims (4)

[Claims] 1. A nozzle for discharging ink, a pressurized liquid chamber and a common ink flow path communicating with the nozzle, a vibration plate forming the pressurized liquid chamber, and an electrode facing the vibration plate. The electrode side includes an electrode substrate and an electrode provided on the electrode substrate, and vibrates using an electrostatic force generated by generating an electric field between the diaphragm and the electrode. In an inkjet head in which the plate is deformed and ink droplets are ejected from the nozzles by a change in volume of the pressure chamber, a projection is formed on a surface of the diaphragm facing the electrode side, and when the diaphragm is deformed, An ink jet head, wherein the projection is in contact with an electrode. 2. The ink jet head according to claim 1, wherein an appropriate portion of the electrode substrate is a non-electrode portion, and a projection comes into contact with the non-electrode portion when the diaphragm is deformed. 3. The ink jet head according to claim 2, wherein the height of the projection is 0.03 μm or more. 4. The ink jet head according to claim 2, wherein a slit-like groove is formed at an appropriate position on the upper surface side of the electrode substrate, and a non-electrode portion is formed around the groove. .