JP2003276194A - Electrostatic actuator, liquid drop ejection head and ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that desired electrostatic force, displacement and pressure cannot be attained without elevating the driving voltage. <P>SOLUTION: Two pairs (electrode pairs) 14 of a movable electrode 14a and a fixed electrode 14b facing each other are disposed substantially in parallel with a diaphragm 10. The movable electrode 14a is secured to the diaphragm 10 and the fixed electrode 14b is secured to a second substrate 2. The movable electrode 14a is displaced through electrostatic attraction generated between the movable electrode 14a and the fixed electrode 14b thus deforming the diaphragm 10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic actuator, a droplet discharge head and an ink jet recording apparatus.

[0002]

2. Description of the Related Art An ink jet head, which is a liquid drop ejection head used in an ink jet recording apparatus used as an image recording apparatus such as a printer, a facsimile, a copying machine or an image forming apparatus, has a single or a plurality of nozzle holes for ejecting ink droplets. And a discharge chamber (also referred to as an ink chamber, a liquid chamber, a pressurized liquid chamber, a pressure chamber, an ink flow path, etc.) communicating with the nozzle hole, and a pressure generation for generating a pressure for pressurizing the ink in the discharge chamber. And ejecting ink droplets from the nozzle holes by pressurizing the ink in the ejection chamber with the pressure generated by the pressure generating means.

As the droplet discharge head, for example, a droplet discharge head for discharging a liquid resist as droplets, DN
There is also a droplet discharge head that discharges the sample A as droplets, but in the following, an inkjet head will be mainly described. The electrostatic actuator that constitutes the actuator portion of the droplet discharge head is, for example, an optical device such as a micropump or a micro light modulation device, a micro switch (micro relay), an actuator (optical switch) of a multi-optical lens, a micro flow meter. It can also be applied to microdevices such as pressure sensors.

By the way, as a droplet discharge head, an electromechanical conversion element such as a piezoelectric element is used as a pressure generating means to deform and displace a vibrating plate forming the wall surface of the discharge chamber to discharge ink droplets. Type, thermal type that uses an electrothermal conversion element such as a heating resistor arranged in the discharge to generate bubbles by film boiling of the ink to discharge ink droplets, vibration that forms the wall surface of the discharge chamber There is an electrostatic type in which a plate is deformed by electrostatic force to eject ink droplets.

In recent years, a lead-free bubble type and an electrostatic type have been attracting attention due to environmental problems. In addition to lead-free, a plurality of electrostatic types have been proposed which have little influence on the environment from the viewpoint of low power consumption. ing.

In this electrostatic ink jet head, for example, as described in Japanese Patent Laid-Open No. 6-71882, a pair of electrodes is provided through an air gap, and one electrode is a vibrating plate. An ink chamber filled with ink is formed on the side opposite to the electrodes facing the vibrating plate, and an electrostatic attractive force acts between the electrodes by applying a voltage between the electrodes (between the vibrating plate and the electrodes). (Vibration plate)
When the voltage is removed and the voltage is removed, the vibrating plate returns to its original state due to the elastic force, and there is a method in which the force is used to eject ink droplets.

Further, as disclosed in Japanese Patent Laid-Open No. 2001-47624, a vibrating plate is provided on one side of electrode pairs which are formed in a comb-like shape and nested in each other, and a voltage is applied to the electrode pairs. There is also a method in which an electrostatic attraction is generated between the comb teeth, the vibration plate is deformed by the displacement of the electrodes, and the ink is ejected by the elastic force of the vibration plate when the voltage is cut off.

Further, as described in Japanese Patent Laid-Open No. 2000-15805, a protrusion is provided on the surface of the vibration plate made of a silicon substrate, an electrode is formed on the protrusion, and a voltage is applied to the electrode. In some cases, the vibrating plate is deformed by an electrostatic force acting between the protrusions to eject ink droplets.

[0009]

However, in the above-described head using the diaphragm and the electrode (electrode pair) facing the diaphragm, the displacement of the diaphragm cannot be increased and a large excluded volume is obtained. It is difficult to eject large ink droplets. Further, since the return spring force of the vibrating plate is used as the pressure generating means for ejecting the ink liquid, the pressure controllability for ejecting the liquid is not good, and it is difficult to control the liquid droplet amount with high precision, thereby achieving high image quality. Is difficult. Furthermore, in order to reduce the voltage, the air gap between the electrodes must be made extremely small, and it is very difficult to form such a minute gap with high accuracy and with little variation, and the yield does not increase. There is such a problem.

Further, in a head having a vibrating plate on one side of electrode pairs formed in a comb shape and nested in each other,
Since the comb-teeth-shaped electrode is used, the displacement amount can be increased, but the generated force is very small, and if an attempt is made to generate the generated force enough to eject ink droplets, the voltage will be extremely high. There is a problem. Moreover, since the structure is complicated, it is difficult to manufacture, and there is a problem that the cost becomes high.

Further, in a head having a protrusion on the diaphragm, it is necessary to form a protrusion on the diaphragm and attach an electrode to the protrusion. It is difficult to attach an electrode, and there are problems that a part where an electrode is not formed well is formed or variation occurs, so that the electrode cannot be stably manufactured and the yield is low.

Further, in order to reduce the voltage, it is necessary to narrow the intervals between the protrusions, but it is difficult to form electrodes in such narrow intervals, and the electrodes are formed between the narrow protrusions. Then, a defect such as a short circuit may occur. Further, it is impossible to form an electrode on the protrusion by a general method because the photolithography process in a three-dimensional structure is difficult in resist coating, exposure, etc. Therefore, using a special device, There is a problem that the manufacturing process becomes long and the cost becomes high.

Moreover, the shape of the protrusion is comb-shaped,
The displacement of the vibrating plate in the longitudinal direction is hindered by the rigidity of the protrusions, a sufficient and efficient amount of displacement cannot be obtained, and desired ink ejection becomes difficult. Further, when the protrusions are needle-shaped, not only is it difficult to perform microfabrication in a stable shape, but also it is not possible to obtain a uniform interval between opposing electrodes and sufficient electrostatic force cannot be obtained. Will be difficult.

As described above, in the conventional head including the actuator using the principle of electrostatic force, there is a trade-off relationship between the low voltage and the ink ejection amount. In addition, since the vibration plate area becomes smaller as the density increases, it is necessary to obtain a large displacement in order to obtain a sufficient ink discharge amount, and a large electrostatic force is required to largely displace the vibration plate. . However, there is a problem that such a request cannot be met at all.

The present invention has been made in view of the above problems, and it is possible to obtain a desired electrostatic force, a displacement amount, and a pressure by controlling the number of electrodes without increasing the driving voltage, and it is possible to reduce the cost. In addition, an electrostatic actuator having high drive efficiency and stable operation characteristics, a droplet discharge head having high droplet discharge efficiency and stable droplet discharge characteristics by including this electrostatic actuator, and this droplet discharge head An object of the present invention is to provide an ink jet recording apparatus that is equipped with a head and is capable of high quality recording.

[0016]

In order to solve the above-mentioned problems, an electrostatic actuator according to the present invention is provided with at least two pairs of movable electrodes and fixed electrodes which are parallel to a thin film and which face each other. The thin film is deformed by the electrostatic force acting on.

It is preferable that the movable electrode is fixed to the thin film and the electrode is fixed to the substrate. Further, it is preferable that the thin film is deformed in a convex shape on the side opposite to the side on which the electrodes are provided. Furthermore, it is preferable that the thin film can be deformed into a concave shape and a convex shape. Furthermore, a fixed electrode for generating an electrostatic force for deforming the thin film in a concave shape and a fixed electrode for deforming in a convex shape can be independently provided.

It is preferable that a drive voltage for generating an electrostatic force is applied to the fixed electrode and the movable electrode is set to the ground potential. Furthermore, it is preferable that the movable electrode and the fixed electrode are made of a high melting point material. Furthermore, the movable electrode and the fixed electrode are preferably made of polysilicon. The movable electrode and the fixed electrode are n
Type or p-type impurity atoms are preferably included.

Further, it is preferable that the electrode distance between the movable electrode and the fixed electrode is such that the thin film can be deformed by 0.2 μm or more. Further, it is preferable that a drive voltage is applied so that the movable electrode and the fixed electrode do not come into contact with each other.

The droplet discharge head according to the present invention has a diaphragm which is a thin film forming at least one wall surface of the discharge chamber communicating with the nozzle for discharging droplets, and a book for deforming this diaphragm. The electrostatic actuator according to the invention is provided.

Here, the ink tank for supplying the ink may be integrally provided.

The ink jet recording apparatus according to the present invention is
The inkjet head for ejecting ink droplets is the droplet ejection head according to the present invention.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of an inkjet head according to a first embodiment of a droplet discharge head including an electrostatic actuator of the present invention, and is shown in a partial cross-sectional view. FIG. 2 is a cross-sectional explanatory view of a principal part of the same head in the lateral direction of the diaphragm.

This ink jet head is of a side shooter type in which ink droplets are ejected from nozzle holes provided in the surface portion of the substrate, and three first, second and third ink jet heads having a structure described in detail below. It has a laminated structure in which the substrates 1, 2 and 3 are stacked and joined, and a plurality of nozzle holes 4 for ejecting ink droplets, an ejection chamber 6 communicating with each nozzle hole 4, and a fluid resistance portion 7 in each ejection chamber 6. A common liquid chamber (common ink chamber) 8 for supplying ink via the same is formed.

The intermediate first substrate 1 is made of a silicon substrate, and has a concave portion for forming the discharge chamber 6 and each discharge chamber 6.
It has a concave portion for forming a common liquid chamber 8 for supplying ink to. On the bottom surface of the first substrate 1, there is provided a vibrating plate 10 which is a thin film and serves as a bottom wall of the discharge chamber 6 and the common liquid chamber 8.

The vibrating plate 10 is formed of a high-concentration boron diffusion layer containing 1E20 / cm ³ or more of boron atoms formed by doping the silicon substrate forming the first substrate 1 with high-concentration boron, or It is formed of a conductive thin film such as metal.

Then, the second substrate 2 is joined to the first substrate 1 via the partition wall portion 12, and the vibrating plate 10 is placed in the space 13 formed between the first substrate 1 and the second substrate 2. The movable electrode 14a and the fixed electrode 1 that are substantially parallel to each other and face each other.
Two pairs (electrode pairs) 14 with 4b are arranged. The diaphragm 10 and the two pairs of electrodes 14 constitute an electrostatic actuator according to the present invention that deforms the diaphragm 10 which is a thin film by an electrostatic force.

Here, the movable electrodes 14a of each electrode pair 14 are connected to each other and fixed to the lower surface of the diaphragm 10 via the connecting portion 14c, and the fixed electrodes 14b of each electrode pair 14 are connected to each other. And is fixed to the upper surface of the second substrate 2. The two movable electrodes 14a and 14a of each electrode pair 14 and the connecting portion 14c thereof are referred to as "movable electrode 14A", and the two fixed electrodes 14b and 14b of each electrode pair 14 are referred to as "fixed electrode 14B". Say.

In this case, the movable electrode 14A has the same potential as the diaphragm 10, and the movable electrode 14A and the fixed electrode 14B are electrically separated. Here, since the movable electrode 14A, the fixed electrode 14B and the partition wall portion 12 are made of the same material, an insulating film 15 such as a nitride film is formed on the second substrate 2 to form the second substrate 2 and the partition wall portion. 12, that is, the diaphragm 10 and the movable electrode 14A are electrically separated, and the fixed electrode 14B is electrically connected to the second substrate 2.

In addition, the movable electrode 14a and the fixed electrode 14b
Is formed of a high melting point material or polysilicon. By using the solid melting point material, it is possible to withstand the heat treatment in the manufacturing process and the restrictions in the manufacturing process are reduced, and by using polysilicon, fine processing can be easily performed and high density can be dealt with. Furthermore, the movable electrode 14a and the fixed electrode 1
By introducing an n-type or p-type impurity atom into 4b,
The resistance can be reduced and high frequency driving becomes possible. Furthermore, the electrode interval between the movable electrode 14a and the fixed electrode 14b is set to an interval that allows the diaphragm 10 to be deformed by 0.2 μm or more. As a result, the vibration plate 10 can be sufficiently deformed, and it is possible to cope with the high density of the head.

The third substrate bonded to the upper surface of the first substrate 1
For the substrate 3, for example, a nickel substrate having a thickness of 50 μm is used, and a fluid resistance portion for communicating the nozzle hole 4, the common liquid chamber 8 and the discharge chamber 6 with the surface portion of the third substrate 3 so as to communicate with the discharge chamber 6, respectively. 7 is provided, and an ink supply port 9 is provided so as to communicate with the common liquid chamber 8.

Next, the operation of the thus constructed ink jet head will be described with reference to FIGS. 3 and 4. For example, as shown in FIG. 3, the diaphragm 10 and the fixed electrode 1
4B, a drive circuit (oscillation circuit) 17 is connected via a switch means 18, and as shown in FIG. 4, the switch means 18 is turned on to drive the drive circuit 17 from 0V to 4V.
When a pulse potential of 0 V is applied and the surface of the fixed electrode 14b is positively charged, an electrostatic force is generated between the adjacent movable electrodes 14a to which the pulse potential is not applied, and the electrostatic force is attracted. Works, and the fixed electrode 14b and the movable electrode 14a attract each other.

At this time, since the fixed electrode 14b is fixed to the second substrate 2, the movable electrode 14a is fixed to the fixed electrode 14b.
The diaphragm 10 is attracted to the side, and as a result, the diaphragm 10 is bent upward (deformed into a convex shape on the side opposite to the electrode side). As a result, the pressure in the ejection chamber 6 rapidly rises, and as shown in FIG. 2, the ink droplets 22 can be ejected from the nozzle holes 4 toward the recording paper 23.

When the potential of the fixed electrode 14b returns to 0V, the potential difference between the fixed electrode 14b and the movable electrode 14a disappears, and the diaphragm 10 is restored to its original state. When the vibration plate 10 is restored, ink is replenished from the common liquid chamber 8 into the ejection chamber 6 through the fluid resistance portion 7.

Here, the force F acting between the electrodes is as follows (1)
As shown in the formula, it increases in inverse proportion to the square of the inter-electrode distance d. In order to increase the displacement of the diaphragm 10 at a low voltage, it is necessary to provide two or more electrode pairs 14 (in multiple stages) and increase the distance between the movable electrode 14a and the fixed electrode 14b.

[0036]

[Equation 1]

In the equation (1), F: force acting between electrodes, ε: permittivity, S: area of opposing surfaces of electrodes, d:
Distance between electrodes, V: applied voltage.

As described above, in the droplet discharge head including the electrostatic actuator of the present invention, a sufficient electrostatic force and displacement of the vibrating plate 7 cannot be obtained by the pair of movable electrode 14a and fixed electrode 14b. Since two or more pairs of electrodes for generating the vibration are provided, the vibration plate 10 can be deformed by the sum of the electrostatic force generated in each electrode pair 14 at a low voltage.
A large displacement can be obtained.

Further, by fixing the movable electrode to the thin film (vibration plate) and fixing the fixed electrode to the substrate, it becomes possible to perform a push-out that deforms (pushes up) the vibration plate 10 in a convex shape to the side opposite to the electrode. It is possible to accurately control the displacement amount of the thin film.

Here, the movable electrode 14a and the fixed electrode 14b
The reliability is improved by forming an insulating film, for example, a thermal oxide film on the surface of each electrode in order to prevent the short circuit.
Further, the voltage applied between the movable electrode 14a and the fixed electrode 14b is set to a voltage value at which the movable electrode 14a and the fixed electrode 14b do not come into contact with each other.
It is possible to prevent electrical shorting of 4b, destruction of electrodes due to contact, generation of residual charges, etc., and reliability is improved.

Further, the movable electrode side is set to the ground potential,
By applying the drive voltage to the fixed electrode side, the electric field is not applied to the ink, particularly when a droplet discharge head as an inkjet head is configured, and there is no restriction on ink selection for higher image quality and the like. .

Next, the ink jet head according to the second embodiment will be described with reference to FIG. It should be noted that this figure is a cross-sectional explanatory view of a main part of the same head taken along the lateral direction of the diaphragm. The head serves as a movable electrode 14A fixed to the diaphragm 10 side of the first embodiment, a connecting portion 14c connecting the movable electrode 14a and the diaphragm 10, and a connecting portion 14c (movable electrode 14a and The connection portion 14d has a planar shape and an area smaller than that of the same size).

The operation of this head will be described with reference to FIGS. 6 and 7.
(Corresponds to FIG. 3 and FIG. 4, respectively),
Although the same as in the first embodiment, by providing the connecting portion 14d having a planar shape and an area smaller than that of the movable electrode 14a, the substantial thickness of the diaphragm 10 is fixed in a state where the movable electrode 14A is fixed to the diaphragm 10. Since the area in which the vibration increases increases is small, the rigidity of the diaphragm 10 due to the provision of the movable electrode 14A can be suppressed, the decrease in displacement efficiency of the diaphragm 10 can be reduced, and the diaphragm 10 can be efficiently deformed. As a result, the effects of lower voltage driving and an increase in the displacement amount can be obtained as compared with the first embodiment.

In addition, similarly to the first embodiment, since the diaphragm can be pushed, the displacement of the diaphragm can be arbitrarily controlled by the applied pulse waveform, so that high ink ejection accuracy can be obtained and high image quality can be obtained. It is relatively easy to obtain.

Next, the ink jet head according to the third embodiment will be described with reference to FIG. It should be noted that this figure is a cross-sectional explanatory view of a main part of the same head taken along the lateral direction of the diaphragm. In this head, the movable electrode 24A fixed to the diaphragm 10 side and the fixed electrode 24B fixed to the second substrate 2 side.
1 and 24B2 are arranged.

Each of the movable electrodes 24A is composed of three movable electrodes 24a (the upper, middle, and lower parts are distinguished from the top in the drawing).
And a connecting portion 24d with the diaphragm 10. Further, the fixed electrode 24B1 has two fixed electrodes 24b1 (which are distinguished from the upper side in the figure to the upper and lower stages) facing the movable electrode 24a in the upper and middle stages of the movable electrode 24A, and the fixed electrode 24B.
B2 is a movable electrode 24a in the middle and lower stages of the movable electrode 24A.
Has two fixed electrodes 24b2 facing each other (the upper stage and the lower stage are distinguished from the top in the drawing).

Therefore, in this electrode configuration, the upper movable electrode 24a of the movable electrode 24A and the upper fixed electrode 24b1 of the fixed electrode 24B1 form the electrode pair 24, and the movable electrode 24
The middle movable electrode 24a, the lower fixed electrode 24b1 of the fixed electrode 24B1, and the upper fixed electrode 24b2 of the fixed electrode 24B2 form the electrode pair 24 (the movable electrode 24a
Is also used. ), The lower movable electrode 2 of the movable electrode 24A
4a and the lower fixed electrode 24b2 of the fixed electrode 24B2 form an electrode pair 24, respectively.

That is, in this embodiment, an electrostatic force is generated between the movable electrode 24a and the movable electrode 24a in a direction in which the diaphragm 10 is displaced toward the electrode side, that is, in order to deform the diaphragm 10 into a concave shape. Fixed electrode 24b1
The movable electrode 24a between the movable electrode 24a and the movable electrode 24a.
The fixed electrode 24b2 is provided for generating an electrostatic force in the direction in which 0 is displaced to the side opposite to the electrode, that is, for deforming the diaphragm 10 into a convex shape.

With this configuration, as shown in FIG. 9, the drive circuit 17 and the switch means 19 are connected between the movable electrode 24a and the fixed electrodes 24b1 and 24b2, and as shown in FIG. When the means 19 is switched to the a side and a pulsed voltage is applied between the movable electrode 24a and the fixed electrode 24b1, the movable electrode 24a and the fixed electrode 2
The electrostatic attraction works with 4b1 to displace the movable electrode 24a downward, and the diaphragm 10 is deformed into a concave shape.

Further, as shown in FIG. 11, the switch means 19 is switched to the b side to move the movable electrode 24a and the fixed electrode 24.
When a pulsed voltage is applied between the movable electrode 24a and the fixed electrode 24b2, an electrostatic attraction force acts between the movable electrode 24a and the fixed electrode 24b2, the movable electrode 24a is displaced upward, and the diaphragm 10 is deformed in a convex shape. To do.

Therefore, the fixed electrodes 24b1 and 24b2
By alternately applying a pulse to, the diaphragm 10 can be pushed up and pulled down, and the fixed electrode 24b
1 or 24b2 is changed from a state in which a voltage is applied to one to a state in which a voltage is applied to the other, that is, by shifting the state of FIG. 10 from the initial state to the state of FIG. The displacement amount can be doubled compared to the first and second embodiments, and high density and low voltage driving can be achieved.

Next, the manufacturing process of the ink jet head according to the first embodiment will be described with reference to FIGS. First, as shown in FIG.
A nitride film 32 of 0.1 μm and a silicon oxide film 33 of 0.5 μm are formed on a silicon substrate 31 serving as a second substrate of 00 μm.
It is deposited by the CVD method. After that, the silicon oxide film 33 in the portion corresponding to the spacer portion 12 is removed by resist patterning and oxide film dry etching.

Then, as shown in FIG. 3B, phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method and polished to a thickness of 0.5 μm by CMP, and then the movable electrode 3 is deposited.
4a1 and part of the partition wall 12a are patterned by litho and unnecessary polysilicon is etched by polysilicon dry etching.

Then, as shown in FIG. 6C, after depositing a silicon oxide film 38a by a 0.6 μm CVD method,
The resist patterning and oxide film dry etching are performed to remove the silicon oxide film 38a on the partition wall 12a and form a groove 39a for forming a fixed electrode.

Thereafter, as shown in FIG. 3D, phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method and polished by CMP to a thickness of 0.5 μm.
Patterning is performed by lithography so that 4b1 and the partition 12b are left, and unnecessary polysilicon is etched by polysilicon dry etching.

Then, as shown in FIG. 7E, a method with good step coverage, for example, plasma CVD and organic SOG + is used.
A silicon oxide film 40a having a thickness of 1 μm is deposited on the fixed electrode 34b1 by an etch back method or the like, and the silicon oxide film 40a on the partition wall 12b is removed by resist patterning and oxide film dry etching, and the movable electrode of the next stage and the movable electrode Groove 41a for forming a connecting portion for connecting the electrode 34a1
To form.

Next, as shown in FIG. 13A, phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method and polished to a thickness of 0.5 μm by CMP, and then the movable electrode 34a2 and the partition 12c are removed. Patterning is performed by litho so as to leave, and unnecessary polysilicon is etched by polysilicon dry etching.

Further, as shown in FIG. 7B, as in the above, after depositing the silicon oxide film 38b by the 0.6 μm CVD method, the silicon oxide film on the partition wall 12c is patterned by resist patterning and oxide film dry etching. A groove 39b is formed for removing the film 38b and forming a connecting portion that connects the fixed electrode of the next stage and the fixed electrode 34b1.

Then, as shown in FIG. 6C, polysilicon doped with phosphorus is deposited to a thickness of 2.5 μm by the CVD method and polished by CMP to a thickness of 0.5 μm, and then the fixed electrode 3 is formed.
4b2 and the partition 12d are left to be patterned by lithography, and unnecessary polysilicon is etched by polysilicon dry etching.

Next, as shown in FIG. 14A, as in the above, a method with good step coverage, for example, plasma CVD
Then, a 1 μm silicon oxide film 40b is deposited on the fixed electrode 34b2 by the organic SOG + etchback method or the like. After that, the silicon oxide film 40b on the partition wall 12d is removed by resist patterning and oxide film dry etching.
A groove 41b for forming a connecting portion that connects the 4a2 and the diaphragm 10 is formed.

Then, as shown in FIG. 9B, after the phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method, the movable electrode 34b2 and the vibrating plate 10 are connected and joined. Patterning is performed by lithography so as to leave the connecting portion 34c and a part of the partition wall 12e, and unnecessary polysilicon is etched by polysilicon dry etching.

Then, as shown in FIG. 7C, a method with good step coverage, for example, plasma CVD and organic SOG + is used.
A silicon oxide film 42 of 0.5 μm is deposited on the connecting portion 34c and the partition wall 12e by an etch back method or the like.

After that, as shown in FIG.
By the P method, the silicon oxide film 42 is polished until the connecting portion 34c and the partition wall 12e are exposed.

Then, as shown in FIG. 7B, in order to form the vibration plate 10, phosphorus-doped polysilicon is deposited to a thickness of 1.5 μm by a CVD method, and then a thickness of 0.5 μm is obtained by CMP. Polishing is performed to make the surface of the polysilicon 43 that becomes the vibration plate 10 a mirror surface.

Thereafter, as shown in FIG. 16, an opening 44 for removing the silicon oxide film is formed in the polysilicon 43 by litho etching.

Next, as shown in FIG. 17A, a 400 μm thick silicon substrate 51 having a thickness of 400 μm is formed by forming a thermal oxide film 52 to a thickness of 100 nm on the silicon substrate 51 having a thickness of 400 μm by wet oxidation at 900 ° C. for 10 minutes. The silicon substrate 51 is prepared and the thermal oxide film 52 is formed on the polysilicon 43.
Then, they are bonded together and heated at a high temperature (1000 ° C./2 hours) to firmly bond them.

Then, as shown in FIG. 7B, a resist is used to remove the silicon oxide film in the electrode chamber corresponding to the shape of the liquid chamber such as the discharge chamber 6 and the opening 44 of the polysilicon 43 described above. The portion is patterned, and silicon etching is performed by an ICP etcher until the underlying thermal oxide film 52 is exposed to form a liquid chamber (flow passage) such as the discharge chamber 6. Next, after removing the resist, the thermal oxide film 52 is removed to form the diaphragm 10 made of the polysilicon 43, and the silicon oxide films 33 and 3 remaining in the electrode formation portion are formed.
8a, 38b, 40a, 40b are removed with hydrofluoric acid.

Thereafter, the ink jet head is completed by bonding the nozzle plate 3 together.

Although the manufacturing process for forming the electrodes in two steps has been described here, when forming electrode pairs in three or more steps, the steps of FIGS. 12 (e) to 13 (c) are repeated. Can be realized easily. Further, by performing the electrode formation and the gap formation by the CVD method, the film thickness can be easily controlled, and the structure suitable for the purpose can be easily manufactured.

In addition, when the vibrating plate is ejected, ink ejection is controlled only by the restoring force of the vibrating plate, but in the case of the push ejection of the present embodiment, the displacement of the vibrating plate can be arbitrarily changed by the applied pulse waveform. Since it can be controlled, a high ink ejection accuracy can be obtained, and a high image quality can be obtained relatively easily.

Next, the ink jet head according to the second embodiment will be described with reference to FIG. Here, after performing the steps of FIGS. 12A to 14C in the same manner as in the manufacturing step of the head according to the first embodiment, FIG.
As shown in (a), by litho-etching, a connecting portion forming groove 45 (width 1 μm) for forming a connecting portion 34d between the connecting portion 34c of the movable electrode and the vibration plate 10 and the partition wall portion 12e.
The upper oxide film is removed.

Then, as shown in FIG. 18B, phosphorus-doped polysilicon is deposited to a thickness of 1.2 μm by the CVD method and polished by CMP so that the connecting portion 34d and the partition 12f remain. After that, the nozzle plate 3 is pasted through the same steps as in FIGS. 16 and 17 to complete the inkjet head.

Although the manufacturing process for forming the electrodes in two steps has been described here, when forming electrode pairs in three or more steps, the steps of FIGS. 12 (e) to 13 (c) are repeated. Can be realized easily. Further, by performing the electrode formation and the gap formation by the CVD method, the film thickness can be easily controlled, and the structure suitable for the purpose can be easily manufactured.

Next, the manufacturing process of the ink jet head according to the third embodiment will be described with reference to FIGS. First, as shown in FIG.
A silicon oxide film 62 having a thickness of 0.1 μm is formed by a CVD method on a silicon substrate 61 serving as a second substrate having a thickness of 00 μm, and polysilicon doped with phosphorus is formed to have a thickness of 0.3 μm, and a voltage is applied to a fixed electrode. After forming the wirings 63 and 64 for performing the etching by litho etching, the nitride film 6 is formed by the CVD method.
5 is formed to a thickness of 0.1 μm. Then, the silicon oxide film 66 is formed to a thickness of 1 μm by the CVD method, and the silicon oxide film 66 at the location where the partition wall 12a is formed is removed by litho etching. The wirings 63 and 64 can also be formed of a high melting point material such as titanium nitride or tungsten.

Next, as shown in FIG. 7B, after phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method, it is patterned by lithography so as to leave the movable electrode 74a1 and the partition 12a. , Unnecessary polysilicon is etched by polysilicon dry etching.

Then, the silicon oxide film 67a is set to 0.6 μm.
After depositing to a thickness of m by the CVD method, the silicon oxide film 67a on the partition wall 12a is removed by resist patterning and oxide film dry etching, and a connecting portion between movable electrodes (a part of the movable electrode) is formed. Groove (movable electrode connection hole) 70
a, Grooves (fixed electrode connection holes) 68a and 69a for forming a connecting portion (a part of the fixed electrode) for connecting the fixed electrode and the wirings 63 and 64 are formed.

Subsequently, as shown in FIG. 7C, after phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method, a part of the movable electrode 76a1 and the partition wall 12 are formed.
b, the fixed electrode 74b11, a part of the fixed electrode 77b11,
Patterning is performed by lithography so as to leave 77b21, and unnecessary polysilicon is etched by polysilicon dry etching.

Then, the silicon oxide film 71a is deposited to a thickness of 1 μm by a method having a good step coverage, for example, plasma CVD and organic SOG + etchback method. After that, by litho etching, the movable electrode connection hole 70b and the fixed electrode connection hole 6 are formed.
8b and 69b are formed, and the silicon oxide film 71a on the partition wall 12b is removed.

After that, as shown in FIG. 6D, after phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method, a part of the movable electrode 76a2 and the partition wall 12 are formed.
c, patterning is performed by lithography so as to leave the fixed electrodes 77b12 and 77b22, and unnecessary polysilicon is etched by polysilicon dry etching.

Then, the silicon oxide film 71b is deposited to a thickness of 1 μm by a method having a good step coverage, for example, plasma CVD and organic SOG + etchback method. After that, the movable electrode connection hole 70c and the fixed electrode connection hole 68 are formed by litho etching.
c and 69c are formed, and the silicon oxide film 71b on the partition 12c is removed.

Next, as shown in FIG. 20A, after phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method, a part of the movable electrode 76a3 and the partition wall 12 are formed.
d, the fixed electrode 74b21, a part of the fixed electrode 77b13,
Patterning is performed by litho so as to leave 77b23, and unnecessary polysilicon is etched by polysilicon dry etching.

Then, the silicon oxide film 67b is set to 0.6 μm.
It is deposited to a thickness of m by the CVD method. After that, the silicon oxide film 67b on the partition wall 12d is removed by resist patterning and oxide film dry etching, and the movable electrode connection hole 70 is formed.
d, the fixed electrode connection holes 68d and 69d are formed.

As shown in FIG. 10B, after phosphorus-doped polysilicon is deposited to a thickness of 2.5 μm by the CVD method, the movable electrode portion 76a4, the partition wall portion 12e, and the fixed electrode portion 77b14 are deposited. , 78b24 are left unetched, and unnecessary polysilicon is etched by polysilicon dry etching.

Then, the silicon oxide film 67c is set to 0.6 μm.
After depositing by the mCVD method, the silicon oxide film 67c on the partition wall 12e is removed by resist patterning and oxide film dry etching, and the movable electrode connection hole and the fixed electrode connection hole are formed, and then phosphorus-doped poly is used. Silicon CV
The fixed electrode 74b1 is deposited to a thickness of 2.5 μm by the D method.
2, patterning with litho so as to leave a part of the fixed electrode 77b25, the partition wall 12f, and a part of the movable electrode 76a5,
Unnecessary polysilicon is etched by polysilicon dry etching.

Then, as shown in FIG. 7C, a method with good step coverage, for example, plasma CVD and organic SOG + is used.
After depositing a silicon oxide film 71c to a thickness of 1 μm by an etch back method or the like, a movable electrode connection hole 70d is formed by litho etching.
The fixed electrode connection hole 69e is formed and the silicon oxide film 71c on the partition 12f is removed.

The formation of these electrodes and the formation of the silicon oxide film are repeated to form the structure shown in FIG. Thereby, the partition 12 and the movable electrodes 74a1, 74a2, 7
4a3, fixed electrodes 74b11, 74b12, 74b2
1, 74b22, a connecting portion 74 between the diaphragm 10 and the movable electrode
d has also been done. After that, by performing the same processing as that of FIG. 17 described in the manufacturing process of the first embodiment, FIG.
The structure of (b) is obtained. The ink jet head is completed by bonding the nozzle plate 3 to this.

Although the manufacturing process for forming the electrodes in four steps has been described here, an arbitrary plurality of steps of electrodes can be formed by repeating the steps. Further, since the electrode formation and the gap formation are performed by the CVD method, the film thickness can be easily controlled,
A structure suitable for the purpose can be easily manufactured.

In the manufacturing process of each of the above-described embodiments, the silicon oxide film is used as the sacrificial layer to form the inter-electrode gap, but it may be formed of a thermal oxide film. Also,
In order to prevent a short circuit between the movable electrode and the fixed electrode, it is preferable to form an insulating film, for example, a thermal oxide film on the surface of each electrode.

Next, an ink cartridge in which an ink jet head as a droplet discharge head and an ink tank according to the present invention are integrated will be described with reference to FIG.
This ink cartridge (ink tank integrated head)
Reference numeral 100 denotes an inkjet head 102 of any of the above-described embodiments that has a nozzle hole 101 and the like, and an ink tank 103 that supplies ink to the inkjet head 102, which are integrated.

By thus integrating the ink jet head, which is the liquid droplet ejection head according to the present invention, and the ink tank, the liquid droplet ejection head that has high droplet ejection efficiency and stable droplet ejection characteristics is integrated. The obtained ink cartridge (ink tank integrated head) is obtained.

Next, an example of an ink jet recording apparatus equipped with an ink jet head (including an ink cartridge integrated head) according to the present invention will be described with reference to FIGS. 23 and 2.
This will be described with reference to FIG. 23 is a perspective explanatory view of the recording apparatus, and FIG. 24 is a side view of a mechanical portion of the recording apparatus.

This ink jet recording apparatus has a carriage movable inside the recording apparatus main body 111 in the main scanning direction, a recording head including the ink jet head according to the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. Printing mechanism section 11 composed of
A sheet feeding cassette (or a sheet feeding tray) 114 capable of accommodating a large number of sheets 113 from the front side can be detachably attached to the lower portion of the apparatus main body 111 for accommodating 2 or the like. The manual feed tray 115 for manually feeding the paper 113 can be opened and closed, the paper 113 fed from the paper feed cassette 114 or the manual feed tray 115 is taken in, and a desired image is recorded by the printing mechanism unit 112. After that, the output tray 1 mounted on the rear side
The paper is discharged to 16.

The printing mechanism 112 slides the carriage 123 in the main scanning direction (the direction perpendicular to the paper surface in FIG. 24) by the main guide rod 121 and the sub guide rod 122, which are guide members that are horizontally mounted on the left and right side plates (not shown). The carriage 123 is freely held, and yellow (Y), cyan (C),
A head 124, which is an ink jet head that is a droplet ejection head according to the present invention that ejects ink droplets of each color of magenta (M) and black (Bk), is arranged in a direction in which a plurality of ink ejection ports intersects the main scanning direction. , The ink droplet ejection direction is downward. Also, the carriage 123
Each ink cartridge 125 for supplying each color ink to the head 124 is replaceably mounted.

The ink cartridge 125 has an upper atmosphere port communicating with the atmosphere, a lower supply port for supplying ink to the ink jet head, and a porous body filled with ink in the interior. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of.

Although the heads 124 for the respective colors are used here as the recording heads, a single head having nozzles for ejecting ink droplets for the respective colors may be used.

Here, the carriage 123 is slidably fitted to the main guide rod 121 on the rear side (downstream side in the sheet transport direction) and slidably fitted to the slave guide rod 122 on the front side (upstream side in the sheet transport direction). It is placed in. Then, in order to move and scan the carriage 123 in the main scanning direction, a timing belt 130 is stretched between the drive pulley 128 and the driven pulley 129 which are rotationally driven by the main scanning motor 127, and the timing belt 130 is mounted on the carriage 123. The carriage 123 is reciprocally driven by the forward and reverse rotations of the main scanning motor 127.

On the other hand, in order to convey the paper 113 set in the paper feed cassette 114 to the lower side of the head 124, a paper feed roller 131 and a friction pad 132 for separating and feeding the paper 113 from the paper feed cassette 114, and the paper 11
Guide member 133 for guiding the sheet 3 and the fed sheet 11
A conveyance roller 134 that reverses and conveys 3 is provided, a conveyance roller 135 that is pressed against the peripheral surface of the conveyance roller 134, and a leading end roller 136 that defines the feed angle of the paper 113 from the conveyance roller 134. Conveyor roller 1
The sub-scanning motor 137 is rotationally driven through a gear train.

A print receiving member 139, which is a paper guide member for guiding the paper 113 sent out from the carrying roller 134 below the recording head 124 in correspondence with the movement range of the carriage 123 in the main scanning direction, is provided. There is. A transport roller 141 and a spur 142 that are driven to rotate in order to send the paper 113 in the paper discharge direction are provided on the downstream side of the print receiving member 139 in the paper transport direction, and further, the paper 113 is sent to the paper discharge tray 116. Roller 143 and spur 1
44, and guide members 145 and 146 that form the paper discharge path
And are arranged.

At the time of recording, by driving the recording head 124 in accordance with the image signal while moving the carriage 123, ink is ejected onto the stopped paper 113 to record one line, and the paper 113 is moved by a predetermined amount. After transportation, the next line is recorded. Upon receiving a recording end signal or a signal that the trailing edge of the paper 113 reaches the recording area, the recording operation is ended and the paper 113 is ejected. In this case, the head 12
In the ink jet head according to the present invention, which composes No. 4, the controllability of ink droplet ejection is improved and the characteristic variation is suppressed, so that an image with high image quality can be stably recorded.

Further, a recovery device 147 for recovering the ejection failure of the head 124 is arranged at a position outside the recording area on the right end side of the carriage 123 in the moving direction. The recovery device 147 has a cap means, a suction means, and a cleaning means. The carriage 123 is moved to the recovery device 147 side while the printing is on standby, the head 124 is capped by the capping means, and the ejection port portion is kept wet to prevent ejection failure due to ink drying.
Also, by ejecting ink that is not related to recording during recording, etc., the ink viscosity of all ejection ports is made constant,
Maintains stable discharge performance.

When a discharge failure occurs, the discharge port (nozzle) of the head 124 is sealed with a capping means,
Bubbles and the like are sucked out together with the ink from the discharge port by the suction means through the tube, and the ink and dust adhering to the surface of the discharge port are removed by the cleaning means to recover the discharge failure. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed in the lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.

As described above, since this ink jet recording apparatus is equipped with the ink jet head which is the liquid droplet ejection head according to the present invention, stable ink droplet ejection characteristics are obtained and the image quality is improved. Further, since a head that can be driven at a low voltage is mounted, the power consumption of the entire inkjet recording device can be reduced.

Next, a micropump as a microdevice including the electrostatic actuator according to the present invention will be described with reference to FIG. It should be noted that the figure is a cross-sectional explanatory view of the main parts of the micropump. This micro pump
The flow path substrate 201 and the protection substrate 202 are laminated and bonded to each other. The flow path substrate 201 is formed with a flow path 203 through which a fluid flows, and is also deformable to form one wall surface of the flow path 203. A thin film movable plate 204 (corresponding to a vibrating plate of the head) is provided to protect the movable plate 204.
The portion that is not joined and fixed with is a movable portion 205.

Then, the movable portion 205 and the protective substrate 203
A movable part 2 similar to that described in the embodiment of the droplet discharge head is provided in the space 208 formed by the partition wall 209.
Electrode pairs 207 each of which is composed of a movable electrode and a fixed electrode, which are substantially parallel to each other and which face each other, are provided in two stages.

The operation principle of this micropump will be described. As described in the operation of the droplet discharge head, the electrode pair 2 is used.
By applying a pulse potential to 07, the movable electrode is displaced and the movable portion 205 is deformed in a convex shape toward the flow path 203 side. Here, by sequentially driving the movable part 205 from the right side in the drawing, the fluid in the flow path 203 flows in the direction of the arrow, and the fluid can be transported.

In this case, the movable portion 205 and the electrode pair 207 are
Since the electrostatic actuator configured by is configured in the same manner as the electrostatic actuator including the vibration plate and the electrode pair of the droplet discharge head described above, the driving efficiency is improved, and stable driving characteristics are obtained. The fluid can be stably and efficiently transferred.

In this example, a plurality of movable parts are provided, but only one movable part may be provided. Also, one or more valves, such as a check valve, may be provided between the moving parts to increase transport efficiency.

Next, an embodiment of an optical device as another example of the microdevice including the electrostatic actuator according to the present invention will be described with reference to FIG. The figure is a schematic configuration diagram of the device. In this optical device, a deformable mirror 301 and a protective substrate 302 are overlapped and bonded to each other, and a portion of the mirror 301 which is not bonded and fixed to the protective substrate 302 is a movable part 305. In addition,
A dielectric multilayer film or a metal film may be formed on the surface of the mirror 301 to increase the reflectance.

Then, the movable portion 305 and the protective substrate 303
In the space 308 formed by the partition 309 and the partition 309, the movable part 3 similar to that described in the embodiment of the droplet discharge head is provided.
Electrode pairs 307 each of which includes a movable electrode and a fixed electrode, which are substantially parallel to each other and which face each other, are provided in two stages.

The principle of this optical device will be described. As in the case of the operation of the droplet discharge head, the mirror 3
01 by applying a pulse potential to the electrode pair 307, 307 provided in the movable part 305 of the electrode pair 30.
The movable electrodes 7 and 307 are displaced, and the movable portion 305 is deformed into a convex shape to form a convex mirror. Therefore, the light source 310
When the light from irradiates the mirror 301 through the lens 311, the light is reflected at the same angle as the incident angle when the mirror 301 is not driven, but the mirror 301 does not move.
When 05 is driven, the movable portion 305 serves as a convex mirror, so that the reflected light becomes divergent light. Thereby, an optical modulation device can be realized.

In this case, the movable portion 305 and the electrode pair 307
The electrostatic actuator configured by is configured in the same manner as the electrostatic actuator configured by the vibration plate and the electrode of the droplet discharge head described above, so that stable and efficient driving is possible, An optical modulation device that can obtain stable operation characteristics can be configured.

Therefore, an example in which this optical device is applied will be described with reference to FIG. In this example, the above-mentioned optical devices are arranged two-dimensionally, and the movable portion 305 of each mirror is arranged.
Is driven independently. Here, the movable parts 305 are arranged in a 4 × 4 matrix.

Therefore, as in FIG. 26 described above, the light from the light source 310 passes through the lens 311 and the mirror 301.
The light that is applied to the area where the mirror 301 is not driven enters the projection lens 312. On the other hand, a portion where the movable portion 305 of the mirror 301 is deformed by applying a voltage to the electrode pair 307, 307 is a convex mirror, so that light diverges and hardly enters the projection lens 312. The light incident on the projection lens 312 is projected on a screen (not shown) or the like, and an image can be displayed on the screen.

In the embodiments of these micropumps and optical devices, the electrostatic actuator having the same structure as the ink jet head according to the first embodiment is described, but the ink jet according to the second and subsequent embodiments. An electrostatic actuator having the same structure as the head can be used.

In the above-described embodiment, the example in which the droplet discharge head is applied to the ink jet head has been described. However, as the droplet discharge heads other than the ink jet head, for example, the droplet discharge for discharging the liquid resist as the droplets. The present invention can also be applied to other droplet discharge heads such as a head and a droplet discharge head that discharges a DNA sample as droplets. Although the electrostatic actuator has been described as an example applied to a micropump and an optical device (light modulation device), a microswitch (microrelay), a multi-optical lens actuator (optical switch), a micro flowmeter, a pressure sensor, etc. Can also be applied to.

[0116]

As described above, according to the electrostatic actuator of the present invention, at least two pairs of movable electrodes and fixed electrodes, which are parallel to the thin film and are opposed to each other, are provided, and electrostatic charges acting between the electrodes are provided. Since the thin film is deformed by force, it is possible to obtain an actuator with high driving efficiency that can obtain a desired electrostatic force and displacement amount by controlling the number of electrodes without raising the driving voltage at low cost. it can.

According to the droplet discharge head of the present invention, the droplet discharge head has a vibrating plate serving as a movable portion which constitutes at least one wall surface of the discharge chamber communicating with the nozzle for ejecting the droplet, and the vibrating plate is deformed. Since the electrostatic actuator according to the present invention is provided for this purpose, a head with low cost and high droplet ejection efficiency can be obtained.

The ink jet recording apparatus according to the present invention is
Since the inkjet head that ejects ink droplets is the droplet ejection head according to the present invention, high image quality recording can be performed.

[Brief description of drawings]

FIG. 1 is an exploded perspective view illustrating an inkjet head according to a first embodiment of a droplet discharge head of the invention.

FIG. 2 is an explanatory cross-sectional view of a main part of the head in a lateral direction of a diaphragm.

FIG. 3 is a schematic explanatory diagram for explaining the operation of the head.

FIG. 4 is a schematic explanatory view showing an operating state for explaining the operation of the head.

FIG. 5 is an explanatory cross-sectional view of a principal part of the inkjet head according to the first embodiment of the droplet ejection head of the present invention in the lateral direction of the diaphragm.

FIG. 6 is a schematic explanatory diagram for explaining the operation of the head.

FIG. 7 is a schematic explanatory view showing an operating state for explaining the operation of the head.

FIG. 8 is an explanatory cross-sectional view of a principal portion of a droplet discharge head according to a third embodiment of the present invention in a lateral direction of a diaphragm of an inkjet head.

FIG. 9 is a schematic explanatory diagram for explaining the operation of the head.

FIG. 10 is a schematic explanatory view showing an operation state for explaining the operation of the head.

FIG. 11 is a schematic explanatory view showing another operation state for explaining the operation of the head.

FIG. 12 is a cross-sectional explanatory diagram for explaining the manufacturing process of the head according to the first embodiment.

FIG. 13 is an explanatory cross-sectional view for explaining the process following FIG.

FIG. 14 is an explanatory cross-sectional view for explaining the process following FIG.

FIG. 15 is an explanatory cross-sectional view for explaining the process following FIG.

16 is an explanatory diagram for explaining the process following FIG.

FIG. 17 is an explanatory cross-sectional view for explaining the process following FIG.

FIG. 18 is a cross-sectional explanatory diagram for explaining the manufacturing process of the head according to the second embodiment.

FIG. 19 is a cross-sectional explanatory diagram for explaining the manufacturing process of the head according to the third embodiment.

FIG. 20 is an explanatory sectional view for explaining a step following FIG.

21 is an explanatory sectional view for explaining the process following FIG. 20. FIG.

FIG. 22 is an explanatory perspective view for explaining an ink tank integrated head including a droplet discharge head according to the present invention.

FIG. 23 is a perspective explanatory view illustrating an example of an inkjet recording apparatus according to the present invention.

FIG. 24 is an explanatory diagram of a mechanical section of the recording apparatus.

FIG. 25 is a cross-sectional explanatory diagram illustrating an example of a micropump including an electrostatic actuator according to the present invention.

FIG. 26 is a sectional explanatory view illustrating an example of an optical device including an electrostatic actuator according to the present invention.

FIG. 27 is a perspective explanatory view illustrating an example of a light modulation device using the optical device.

[Explanation of symbols]

1 ... 1st substrate, 2 ... 2nd substrate, 3 ... Nozzle plate, 4 ... Nozzle hole, 6 ... Discharge chamber, 7 ... Fluid resistance part, 8 ... Common liquid chamber, 1
0 ... Vibration plate, 14a, 24a ... Movable electrode, 14b, 24
b1, 24b2 ... Fixed electrodes.

Claims (14)

[Claims] 1. An electrostatic actuator for deforming a thin film by using electrostatic force, wherein at least two pairs of movable electrodes and fixed electrodes that are substantially parallel to the thin film and face each other are provided, and static electricity that acts between the electrodes. An electrostatic actuator characterized in that the thin film is deformed by force. 2. The electrostatic actuator according to claim 1, wherein the movable electrode is fixed to the thin film, and the electrode is fixed to a substrate. 3. The electrostatic actuator according to claim 1, wherein the thin film is deformed in a convex shape on a side opposite to a side on which the electrode is provided. 4. The electrostatic actuator according to claim 1 or 2, wherein the thin film is deformable into a concave shape and a convex shape. 5. The electrostatic actuator according to claim 1, 2 or 4, wherein the fixed electrode for generating an electrostatic force for deforming the thin film into a concave shape and the fixed electrode for deforming into a convex shape are independent of each other. An electrostatic actuator comprising: 6. The electrostatic actuator according to claim 1, wherein a drive voltage for generating an electrostatic force is applied to the fixed electrode, and the movable electrode is set to the ground potential. And electrostatic actuator. 7. The electrostatic actuator according to claim 1, wherein the movable electrode and the fixed electrode are made of a high melting point material. 8. The electrostatic actuator according to claim 1, wherein the movable electrode and the fixed electrode are made of polysilicon. 9. The electrostatic actuator according to claim 1, wherein the movable electrode and the fixed electrode contain an n-type or p-type impurity atom. 10. The electrostatic actuator according to claim 1, wherein an electrode interval between the movable electrode and the fixed electrode is an interval capable of deforming the thin film by 0.2 μm or more. And electrostatic actuator. 11. The electrostatic actuator according to claim 1, wherein a drive voltage is applied so that the movable electrode and the fixed electrode do not come into contact with each other. 12. A droplet discharge device, comprising: a diaphragm, which is a thin film forming at least one wall surface of a discharge chamber communicating with a nozzle for discharging a droplet, and deforming the diaphragm to discharge the droplet. A droplet discharge head comprising the electrostatic actuator according to any one of claims 1 to 11 for deforming the vibration plate. 13. The droplet discharge head according to claim 12, wherein an ink tank for supplying ink is integrally provided. 14. An inkjet recording apparatus equipped with an inkjet head for ejecting ink droplets, wherein the inkjet head is the droplet ejection head according to claim 12 or 13.