JP2003250280A - Electrostatic actuator, droplet discharge head, and inkjet recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide high stable discharging efficiency and characteristics at a low cost. <P>SOLUTION: A diaphragm 10 constituting the wall of a discharge chamber 6 which communicates with a nozzle hole 4 is provided with a plurality of electrodes 14a and 14b which, having a conductive structure, are electrically isolated from each other. An interval between the plurality of electrodes 14a and 14b is made narrower at a peripheral part than at a central part in a diaphragm surface, while a different potential is applied between the electrodes 14a and 14b, so that an electrostatic attraction is generated to deform 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. Further, the microactuator forming 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 pressure sensors and the like.

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, bubble type (thermal type) in which bubbles are generated by film boiling of ink and ink droplets are discharged by using an electrothermal conversion element such as a heating resistor arranged in the discharge, wall surface of discharge chamber There is an electrostatic type in which an ink droplet is ejected by deforming a vibration plate that forms an electrostatic force.

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 described in Japanese Patent Application 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.

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

[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 in which a vibrating plate formed of a conductive silicon substrate is provided with a protrusion and an electrode of a conductive member is formed on the vibrating plate, each electrode is originally disposed via the silicon vibrating plate. Since there is the same potential between the electrodes, there is a problem that electrostatic force is not generated between the electrodes and the diaphragm cannot be deformed.

Moreover, it is necessary to form a protrusion on the diaphragm and attach an electrode to this protrusion, and it is difficult to attach an electrode to the surface of such a three-dimensional fine structure, and the electrode is not formed well. There is a problem that a part is formed or variation occurs, stable manufacturing cannot be performed, and 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.

The present invention has been made in view of the above problems, and is an electrostatic actuator which is low in cost, has high driving efficiency, and can obtain stable operation characteristics, and droplet discharge efficiency is provided by including the electrostatic actuator. It is an object of the present invention to provide a highly reliable droplet discharge head that achieves high droplet discharge characteristics and high reliability, and an inkjet recording apparatus that includes this droplet discharge head and that enables high-quality recording.

[0015]

In order to solve the above problems, in an electrostatic actuator according to the present invention, a movable portion is provided with a plurality of electrodes made of a conductive structure electrically insulated from each other. At the same time, a means for promoting the deformation of the movable part is provided.

In the electrostatic actuator according to the present invention, the movable portion is provided with a plurality of electrodes made of a conductive structure that is electrically insulated from each other, and the electrodes are spaced from each other more than the central portion of the movable portion. The peripheral part of the movable part is narrowed.

In each of these electrostatic actuators according to the present invention, it is preferable that the thickness of the movable portion is thinnest on the fixed end side of the movable portion. Further, the internal stress of the movable part is preferably tensile stress, and in this case, the movable part preferably has a stress of 1 GPa or less. Further, it is preferable that the electrodes are arranged substantially in parallel.

The droplet discharge head according to the present invention has a vibrating plate serving as a movable portion which constitutes at least one wall surface of the ejection chamber in which the nozzles for ejecting the liquid droplets communicate with each other. The electrostatic actuator according to the present invention is provided.

Here, the ink cartridge 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.

[0021]

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 of the present invention, and is shown in a partial sectional view. 2 is a cross-sectional explanatory view of the same head in the longitudinal direction of the diaphragm, FIG. 3 is a cross-sectional explanatory view of the same head in the lateral direction of the diaphragm, and FIG. 4 is a plan explanatory view showing an electrode arrangement pattern of the same head.

This ink jet head is of a side shooter type in which ink droplets are ejected from nozzle holes provided on the surface of the substrate, and three first, second and third ink jet heads having a structure described in detail below are provided. 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. It is also possible to use an edge shooter type in which ink droplets are ejected from nozzle holes provided at the end of the substrate.

The intermediate first substrate 1 has a recess for forming the discharge chambers 6 and a recess for forming a common liquid chamber 8 for supplying ink to each discharge chamber 6. This first substrate 1 is, for example, a single crystal silicon substrate made of KOH.
Height from 20μm to 200 by anisotropic etching such as
The discharge chamber 6 of μm and the like are formed.

On the bottom surface of the first substrate 1, there is provided a vibrating plate 10 which also serves as a bottom wall of the discharge chamber 6 and the common liquid chamber 8. The vibrating plate 10 is formed by doping a silicon substrate forming the first substrate 1 with high-concentration boron to form a boron atom 1E20.
It is formed of a high-concentration boron diffusion layer containing / cm ³ or more. The vibrating plate 10 is made of a conductive film such as a metal, an insulating film such as a silicon oxide film or a silicon nitride film, a laminated film thereof, a resin film, or the like, which has strength enough to withstand the liquid discharge pressure. There is no particular limitation as long as it is a film having

An insulating film 11 such as a silicon oxide film or a silicon nitride film is formed on the lower surface (the surface opposite to the discharge chamber) of the vibration plate 10. Then, on the lower surface of the insulating film 11, a plurality of electrodes 14 made of a conductive structure that is electrically isolated from each other are provided at predetermined intervals. In this case, since the insulating film 11 is interposed between the diaphragm 10 and the electrode 14, the electrodes 14 are not electrically connected via the diaphragm 10. In addition, each electrode 14
Of the two electrodes adjacent to each other
4a and 14b. ) Are also electrically separated from each other via the air gap. The vibrating plate 10 (the portion corresponding to the discharge chamber 6 becomes the movable portion) and the plurality of electrodes 14 constitute the electrostatic actuator according to the present invention.

Here, the electrodes 14a and 14b, which are electrically separated from each other and are adjacent to each other, are arranged substantially parallel to each other at a predetermined interval in the lateral direction of the diaphragm 10 as shown in FIG. There is. In this case, the distance between the electrodes 14 a and 14 b (electrode distance) is changed within the plane of the diaphragm 10. That is, with respect to the distance g0 between the electrodes 14a and 14b at the center of the diaphragm 10 where the displacement of the diaphragm 10 can be maximized, the diaphragm 10 is near the fixed end (peripheral portion) of the diaphragm 10 where displacement is most difficult. Distance gn between electrodes 14a and 14b of
Is the narrowest. In this head, widening the electrode interval in the central portion of the diaphragm and narrowing it in the peripheral portion of the diaphragm is a means for promoting the deformation of the diaphragm 10.

Then, these electrodes 14a and 14b
A drive voltage (a voltage having a different potential) that causes a potential difference from each other is applied from the drive circuit (here, shown as an oscillation circuit) 15.

The second substrate 2 bonded to the lower surface of the first substrate 1 is a protective substrate for protecting the electrode 14 from external impacts and dust, and for reinforcing the strength of the first substrate 1. Is. A substrate made of glass, metal, silicon, resin, or the like is used as the second substrate 2, and a concave portion 16 having a depth of, for example, 1 mm is formed on the substrate 2 at a position corresponding to each diaphragm 10. There is. However, it is not always necessary to form the concave portion 16 for each diaphragm 10, and it is also possible to form a concave portion that surrounds the diaphragm arrangement or a concave portion that is joined only to the edge of the chip.

Further, the third substrate joined 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.

The operation of the ink jet head thus configured will be described. For example, in the configuration of FIG.
When a pulse potential of 0V to 40V is applied to 4a by the oscillating circuit 15, the surface of the electrode 14a is positively charged, and an electrostatic force is generated between the electrodes 14b adjacent to each other to which no pulse potential is applied, which causes electrostatic discharge. The suction action works and the electrode 14
End of the electrode (the vibrating plate 10 side is the fixed end) attracts each other
4 is displaced and the free end sides of these electrodes 14 are displaced, so that the vibration plate 10, which is the fixed end side of the electrodes 14, is bent upward. As a result, the pressure in the ejection chamber 6 rapidly increases, and the ink droplets 22 are ejected from the nozzle holes 4 toward the recording paper 23 as shown in FIG.

Then, when the potential of the electrode 14a returns to 0V, the potential difference between the electrode 14b and the electrode 14b disappears and the diaphragm 10
Restores the 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. That is, in this embodiment, the ink droplets are ejected by the pushing method.

Here, the force F acting between the electrodes is defined by the following (1)
As shown in the formula, it increases in inverse proportion to the square of the inter-electrode distance d. In order to drive at a low voltage, the electrode 14a and the electrode 1
It is important to form a narrow gap between the electrodes 4b, that is, a groove between the electrodes 14.

[0033]

[Equation 1]

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

As described above, in this ink jet head, the electrodes 14 that are electrically separated and independent from each other are provided on one surface of the diaphragm 10 formed of the insulating thin film, and the electrodes 14a and 14b facing each other are disposed between the electrodes 14a and 14b. By applying a voltage that causes a potential difference between the adjacent electrodes 14a
An electrostatic attractive force is generated between the electrode 14b and the electrode 14b, a large displacement of the diaphragm 10 can be obtained by a slight displacement of the electrode 14, stable droplet ejection characteristics can be obtained, and droplet ejection efficiency can be improved. Image quality recording is possible.

Here, in this head, as described above, the distance between the electrodes 14a and 14b adjacent to each other is changed within the plane of the diaphragm 10 so that the distance between the electrodes at the center of the diaphragm 10 is changed. The electrode interval near the fixed end of the diaphragm 10 is formed narrow. Thereby, the diaphragm 10 can be deformed more efficiently.

That is, the force F acting between the electrodes 14, 14 increases in inverse proportion to the square of the inter-electrode distance d, as shown in the above equation (1). Electrode 1 near the fixed end of diaphragm 10
By making the distance gn between 4 and 14 small, the force F acting between the electrodes 14a and 14b adjacent to each other becomes large, and the displacement of the diaphragm 10 is promoted. Then, as the distance from the fixed end of the diaphragm 10 is increased, the displacement of the diaphragm 10 is less affected by the fixed end.

Since the diaphragm 10 is fixed on four sides,
When viewed in the cross section in the short side direction, as shown in FIG. 5, the bending directions of the regions of the diaphragm are not the same. That is, the bending direction is opposite between the vicinity of the fixed end (peripheral portion) 10B of the diaphragm 10 and the vicinity of the central portion 10A. By disposing the electrodes 14 having the same structure in both of the portions in which the bending directions are reversed,
A portion for suppressing the displacement of the diaphragm 10 will be generated,
As a result, the bending amount of the diaphragm 10 is reduced.

Specifically, the vibrating plate 1 when the electrodes 14 are arranged in the region where the short side length ratio is 15% or less from the end in the short side direction of the vibrating plate.
It has been confirmed that the bending amount of 0 is 80% or less of the bending amount when the electrode 14 is not arranged in the same region. Therefore, by disposing the electrodes 14 only in the portions in which the bending direction of the diaphragm 10 in each region is the same, the bending amount of the diaphragm 10 can be maximized. At least the diaphragm 10 has a distance between the electrodes 14 that is closer to the fixed end than the distance g0 between the electrodes 14 at the center of the diaphragm 10 in a region of about 15 to 35% of the entire width of the diaphragm 10 from the fixed end. Is most efficient.

By narrowing the distance between the electrodes 14 near the fixed end of the diaphragm 10 in this way, as compared with the case where the same distance between the electrodes 14 is provided on the entire surface of the diaphragm 10, the diaphragm 10 is
The force acting between the electrodes 14 near the fixed end of the diaphragm 10 increases, and the portion of the diaphragm 10 near the fixed end of the diaphragm 10 is easily bent. Accordingly, the displacement of the diaphragm 10 near the fixed end of the diaphragm 10 can be increased (deformation is promoted),
The displacement of the electrode 14 due to the electrostatic attractive force generated between the electrodes 14 is efficiently converted into the bending moment acting on the diaphragm 10, the displacement efficiency of the diaphragm 10 is improved, and the manufacturing variation and the deflection of the diaphragm are increased. Even if there is a variation in the electrode spacing due to, a stable displacement of the diaphragm can be obtained. This means that the driving voltage can be lowered further.

In this head, the diaphragm 1
Since the structure itself provided at 0 functions as the electrode 14, it is possible to reduce the cost because there is no need for the difficult step of forming the electrode on the silicon structure by a method such as film formation as in the past. In addition, defects such as a short circuit caused by forming electrodes at extremely narrow intervals between structures can be reduced. Furthermore, there is no need for a step of separating the electrodes into comb-like shapes after forming the electrodes on the structure, and thus cost reduction and mass production are easy.

Further, since the diaphragm 10 and the electrodes 14 are electrically separated by the insulating film 11, even if a voltage is applied to the electrodes as in the conventional case, all the electrodes are made uniform through the diaphragm. It is possible to efficiently apply the voltage to the electrode 14 without causing a potential failure and malfunction, and without causing the voltage applied to the electrode 14 to leak to the diaphragm 10 side. Also,
Since the vibrating plate 10 is insulated from the electrode 14, the drive voltage is not applied to the liquid (here, ink), and the deterioration of the liquid due to the electrolysis when the drive voltage is applied does not occur. The reliability is improved and high quality recording becomes possible.

Since the electrodes are arranged substantially in parallel,
A large diaphragm displacement can be obtained with low reproducibility with good reproducibility.

Next, the ink jet head according to the second embodiment will be described with reference to FIG. In addition, this figure is a cross-sectional explanatory view of the same head taken along the lateral direction of the diaphragm.
In this head, the diaphragm 10 is formed of the silicon nitride film 10a whose internal stress is tensile stress. When the silicon nitride film 10a is formed of a deposited film, 1-1.
The tensile stress is about 2 GPa. By forming the diaphragm 10 with the tensile stress silicon nitride film 10a, the diaphragm 10 can be prevented from buckling, and the diaphragm 10 can be prevented.
Irregular deformation due to buckling of the electrodes is suppressed, the distance between the electrodes can be kept substantially constant, and stable low voltage driving can be performed.

In this case, when the tensile stress of the diaphragm 10 is large, the diaphragm 10 is less deformed. Therefore, the tensile stress is preferably 1 GPa or less, and particularly preferably 0.1 GPa or less. In order to reduce the stress of the silicon nitride film 10a forming the vibrating plate 10, impurities such as boron, phosphorus and hydrogen are implanted into the silicon nitride film 10a. For example, when the thickness of the silicon nitride film 10a is 1500 Å, the boron atom is 1E14 to 3
The stress can be relaxed by injecting energy of 50 KeV with a dose amount of E15 / cm ² degrees. If the thickness of the silicon nitride film is 3000 Å, 2E1 of boron atom is added.
The stress can be relaxed by injecting 80 KeV energy at a dose of about 4 to 6E15 / cm ² .

Further, in this head, the spacer 12 which is a layer or structure made of the same material as the electrode 14 is used as the vibration plate 1.
In a region other than 0, it is formed on substantially the same plane as the surface on which the electrode 14 is formed. The spacer 12 can be formed simultaneously with the electrode 14, and can be formed by not removing the electrode material other than the vibrating plate region.

By providing such a spacer 12, the electrode 14 which is a minute structure can be protected in the process before the first substrate 1 is bonded to the second substrate 2, and the wafer transfer or the wafer transfer can be performed in the manufacturing process. Therefore, defects due to breakage of the electrode 14 during the process can be reduced.

Next, an ink jet head according to the third embodiment will be described with reference to FIG. In addition, this figure is a cross-sectional explanatory view of the same head taken along the lateral direction of the diaphragm.
In this head, the diaphragm 10 is formed such that the diaphragm central portion 10A is thick and the diaphragm peripheral portion is thin.
That is, the thickness of the diaphragm 10 is thinnest in the vicinity of the fixed end of the diaphragm. In this head, the thickness of the diaphragm 10 is made thinnest in the vicinity of the fixed end of the diaphragm, which means that the displacement of the diaphragm 10 is promoted.
In addition, although the thickness of the diaphragm 10 is shown as an example in which the thickness is different in two steps here, it may be different in three or more steps.

In this case, about 15% of the total width of the diaphragm 10 from the fixed end of the fixed end of the diaphragm 10 which is fixed on all sides or 35% of the total width of the diaphragm 10 from the fixed end of the diaphragm 10.
It is preferable to reduce the film thickness in the region. Further, the film thickness is preferably as thin as possible in order to increase the vibration displacement, but a certain film thickness is required to secure durability. The thickness of the thin region is preferably set to 0.01 μm or more and about 50% or less of the thickness of the diaphragm 10.

As shown in FIG. 8, the arrangement pattern of the electrodes 14 of this head is such that the electrodes 14a and 14a are formed substantially parallel to each other in a comb-teeth shape, and the electrodes 14a and 14 are also formed.
The distance to a is equal in the plane of the diaphragm 10. The electrode spacing pattern may be the same as the electrode arrangement pattern of the first embodiment described above.

As described above, even if the electrode 4 is not arranged, the thickness of the diaphragm 10 is reduced in the vicinity of the fixed end of the diaphragm 10 where the vibration displacement is small, so that the entire surface of the diaphragm 10 has the same thickness. Compared with the case of the diaphragm 10, the rigidity is lowered and the diaphragm 10 is easily bent. As a result, the displacement of the diaphragm 10 near the fixed end of the diaphragm 10 can be increased (deformation is promoted), so that the displacement of the electrode 14 is reduced.
The bending moment acting on zero can be efficiently converted, and a stable displacement of the diaphragm can be obtained even if there is a variation in the electrode spacing due to manufacturing variations or the deflection of the diaphragm.
Furthermore, the driving voltage can be lowered.

Next, a manufacturing process of the ink jet head according to the second embodiment will be described with reference to FIGS. 9 and 10. Here, the electrode 14 is formed of polysilicon (polycrystalline silicon), and the diaphragm 10 is formed of a silicon nitride film which is an insulating material.

First, the manufacturing process of the electrostatic actuator portion will be described with reference to FIG. 8. As shown in FIG. 8A, a silicon substrate having a plane orientation (110) and a thickness of 400 μm is used as the base substrate 31. Then, a silicon oxide film 32 as a vibrating plate protective layer having a thickness of 0.2 μm and a silicon nitride film 33 serving as the vibrating plate 10 having a thickness of 0.5 μm are sequentially formed.

As a method of forming the silicon oxide film 32,
Although there are plasma CVD, sputtering, HTO, TEOSS, etc., here, since the silicon oxide film 32 on the diaphragm is finally removed by the diaphragm protection layer, the manufacturing method is not particularly limited as long as it is a deposited film. Further, the silicon nitride film 33 to be the vibrating plate 10 can be formed by a deposited film such as plasma CVD or LPCVD, and as described above, it is 1 to 1.2 GPa.
It is a tensile stress of a certain degree. Here, as described above, impurities such as boron, phosphorus, and hydrogen are implanted into the silicon nitride film 33 in order to relax the tensile stress of the internal stress.

Thereafter, as shown in FIG. 6B, polysilicon 34 is formed on the surface of the silicon nitride film 33 to a thickness of 5 μm, and impurity atoms of n-type or p-type conductivity are doped into the polysilicon 34. Dope. phosphorus for n-type conductivity,
Implant impurities such as arsenic. In the case of p-type conductivity, impurities such as boron are implanted. After the impurity implantation, 10
It is driven at 50 ° C. for 120 minutes to reduce the resistance of the polysilicon 34. By doping impurity atoms to lower the resistance value, it becomes possible to support high frequency driving and multi-channel driving. Further, by removing the surface of the polysilicon layer 34 by polishing, a strong bond can be obtained by a direct bond later.

Next, as shown in FIG. 6C, a resist pattern is formed on the polysilicon 34 by photolithography, and the polysilicon 34 is etched by dry etching at intervals of 0.3 μm and line width of 0.5 μm. The electrode 34 is formed by. At this time, the silicon nitride film 33 forms an etching stop layer. The arrangement pattern of the electrodes 34 has a comb tooth shape as shown in FIG. 5 or FIG.

The electrode structure of the electrostatic actuator is completed by the above process. Furthermore, if the base substrate 31 and the silicon oxide film 32 are removed by etching, an electrostatic actuator is completed, and it can be used for a micropump, an optical modulation device, etc. described later. Here, the base substrate 31
The step of forming the droplet discharge chamber 6 and the like to form a droplet discharge head will be described continuously with reference to FIG.

After forming a silicon nitride film 36 serving as a mask for potassium hydroxide etching by LP-CVD as shown in FIG. 7A, the silicon nitride film 36 is formed on the silicon nitride film 36 as shown in FIG. A resist pattern having a shape such as the discharge chamber 6 and the common liquid chamber 8 is obtained, the silicon nitride film 36 in the opening 36a of the resist is removed by etching by dry etching, and the resist is removed.

Then, as shown in FIG. 7C, the opening 36a of the silicon nitride film 36 is etched with a 25 wt% potassium hydroxide aqueous solution at 80 ° C., for example. When the etching reaches the silicon oxide film 32, the silicon oxide film 32 is hardly etched, so that the etching stops.

Here, the base substrate 31 has (110)
Since the silicon wafer of the plane is used, the vertical wall of the (111) plane is formed by anisotropic etching with potassium hydroxide. Since the vertical wall is obtained by using the (110) plane wafer, the discharge chambers can be arranged at high density.

Although an aqueous solution of potassium hydroxide is used here, an alkaline solution such as TMAH (tetramethylammonium hydroxide solution), EDP (ethylenediaminepyrocatechol) and lithium hydroxide can also be used.

Thereafter, as shown in FIG. 3D, the silicon nitride film 36 is removed by phosphoric acid heated to about 180 ° C., and the exposed portion of the silicon oxide film 32 is removed by buffered hydrofluoric acid or the like. Thus, the diaphragm 10 and the discharge chamber 6 made of the silicon nitride film 33 having a thickness of 0.5 μm are completed.

In this manufacturing process, since the electrodes 14 are formed by photolithography and etching, the electrodes facing each other can be formed in parallel with relatively high positional accuracy, and a large diaphragm displacement can be reproduced with a low driving voltage. It can be generated well.

Next, an example of the manufacturing process of the ink jet head according to the third embodiment will be described with reference to FIGS.
This will be described with reference to FIG. Here, the drive electrode 14 is formed of single crystal silicon. The diaphragm 10 is a high-concentration p-type impurity layer, and the high-concentration p-type impurity layer has the same thickness as the desired diaphragm thickness, here, 1 μm.

First, as shown in FIG. 11A, about 15% of the entire width of the diaphragm 10 from the fixed end of the diaphragm 10 is finished.
From the area or the fixed end of the diaphragm 10 to the entire width of the diaphragm 10
The high-concentration boron diffusion layer 4 so that the film thickness becomes thin in the 5% region.
A silicon substrate 41 having a distribution of 2 is formed.

That is, the thickness of the plane orientation (110) is 4
Boron is implanted with a high implantation energy of, for example, 200 keV into a central region of about 40 to 90% of the entire width of the diaphragm 10 corresponding to the central thickness of the diaphragm 10 on the silicon substrate 41 of 00 μm. Next, the energy lower than the energy injected into the central portion of the diaphragm 10 on the entire surface of the silicon substrate 41, for example, 70
Boron is injected with an injection energy of keV. Finally, the implanted boron atoms are driven to form the high-concentration boron diffusion layer 42. As a result, the high-concentration boron diffusion layer 42 serving as the diaphragm 10 has a thick central portion 42A (deep depth) and a thin central portion 42B (deep depth) 42B.

A compound layer of silicon and boron is formed on the surface of the high-concentration boron diffusion layer 42. To remove this layer, the compound layer is thermally oxidized and etched with a hydrofluoric acid-based etching solution. It can be removed by Roughness may occur on the surface where the silicon is diffused, and a strong bond may not be obtained in the subsequent direct bonding. Therefore, it is preferable to polish the diffusion surface to form a smooth surface.

Next, as shown in FIG. 6B, the compound layer is removed and polished, and then a silicon thermal oxide film 43 having a thickness of 50 nm is formed by wet oxidation at 900 ° C. for 5 minutes. Here, as the film forming method of the silicon oxide film 43, plasma CVD, sputtering, HT may be used in addition to thermal oxidation.
Although there are O, TEOS, etc., a thermal oxide film is preferable in terms of withstand voltage, defects, residual charges, durability and the like.

Then, as shown in FIG. 7C, another silicon substrate 44 for forming electrodes is prepared and directly bonded to the high-concentration boron diffusion layer 42 side of the silicon substrate 41. Here, a silicon wafer having a (100) plane orientation was used as the silicon substrate 44. The two wafers are firmly bonded by sticking together a silicon wafer having a good surface property and heating it at a high temperature. In addition, here, heat treatment was performed at 1000 ° C. for 2 hours.

Next, as shown in FIG. 6D, the silicon substrate 44 is polished to a thickness of 10 μm, and impurity atoms of n-type or p-type conductivity are doped into silicon. In the case of n-type conductivity, impurities such as phosphorus and arsenic are implanted. In the case of p-type conductivity, impurities such as boron are implanted. Then, after injecting impurities, drive at 1050 ° C. for 120 minutes,
Since the silicon substrate 44 is used as the electrode 14, the resistance is lowered.

Subsequently, as shown in FIG. 12A, a resist pattern is formed on the silicon substrate 44 polished by photolithography, and the silicon substrate 44 is line-etched at intervals of 0.5 μm and width of 0.5 μm by dry etching. Then, the electrode 14 is formed by etching. The shape of the electrode 14 is, for example, a comb tooth shape as shown in FIG. 5 or 8.

In this case, the silicon thermal oxide film 43 serves as a stop layer for etching. Dry etching requires ICP (Induc
edCouple Plasma) is effective.

The electrode structure of the electrostatic actuator is completed by the above process. Further, if the silicon substrate 41 is removed by etching, an electrostatic actuator is completed, and it can be used for a micropump, an optical modulation device, etc. described later. Here, the manufacturing method for forming the droplet discharge chamber 6 on the silicon substrate 41 and finishing the droplet discharge head will be described with reference to FIG.

As shown in FIG. 9B, a silicon nitride film 46 serving as a mask for potassium hydroxide etching is formed by LP-CVD, and a discharge chamber is formed on the silicon nitride film 46 as shown in FIG. A resist pattern having a shape such as 6 or the common liquid chamber 8 is obtained. Then, the silicon nitride film 46 and the silicon thermal oxide film 43 in the resist opening 46a are removed by dry etching to remove the resist.

Then, as shown in FIG.
Etching is performed from the opening of the silicon nitride film 46 and the silicon thermal oxide film 43 to the high concentration boron diffusion layer 42 (remaining about 10 μm) with a 25 wt% potassium hydroxide aqueous solution at ℃. Next, the etching solution is changed to a 30 wt% potassium hydroxide aqueous solution at 80 ° C. in which IPA is supersaturated, and the etching is continued to spontaneously stop when the high-concentration boron diffusion layer 42 is reached.

With a 25 wt% potassium hydroxide aqueous solution, the etching rate is large and stable etching can be obtained. Further, in the 30 wt% potassium hydroxide aqueous solution to which IPA is added, the etching selection ratio between the silicon substrate and the high-concentration boron layer is large, and the etching can be stopped accurately. I
Since PA has a low boiling point and evaporates significantly when heat is applied, it is preferable to attach a reflux device for cooling the vapor to liquefy it and returning it to the etching tank. As an etching solution that can increase the etching selection ratio of the high-concentration boron diffusion layer, potassium hydroxide aqueous solution having a low concentration of about 3 wt% to 10 wt%, EDP, or the like may be used other than IPA-added potassium hydroxide.

Thereafter, as shown in FIG. 9B, the silicon nitride film 46 is removed by removing the silicon thermal oxide film 43 with hydrofluoric acid or the like by phosphoric acid or the like heated to 180.degree.
The diaphragm 10 and the discharge chamber 6 made of silicon having a thickness of μm are completed. At this time, since the diaphragm 10 is formed of the high-concentration boron diffusion layer 42, the central portion 10A is thick and the peripheral portion 10B is thin.

The high-concentration boron diffusion layer can be formed by solid diffusion, coating diffusion, or a boron-doped epitaxial layer in addition to ion implantation. Since the shallow diffusion layer can be formed with high precision by ion implantation, it is suitable for forming a thin diaphragm. In addition, in the epitaxial layer, a layer doped with boron is grown on the silicon substrate, so the boundary of the high-concentration boron region becomes clear compared to solid diffusion, ion implantation, and coating diffusion, and a sharp etching stop can be realized. A more accurate diaphragm can be formed.

In addition to the high-concentration boron stop, P
Type silicon substrate with N type layer or N type silicon substrate with P type
It is also possible to use a method of forming a mold layer to stop the electrochemical etching.

Further, in the above description of the manufacturing process, the silicon substrate having the (110) plane orientation is used as the first substrate.
A silicon substrate having a (00) plane orientation can also be used.

Next, a head-integrated ink cartridge including a droplet discharge head according to the present invention will be described with reference to FIG. This ink cartridge 100 is one in which the inkjet head 101 of any of the above-described embodiments having a nozzle hole 101 and the like and an ink tank 102 that supplies ink to the inkjet head 101 are integrated.

As described above, in the case of the head integrated with the ink tank, the cost reduction and reliability of the head immediately leads to the cost reduction and reliability of the entire ink cartridge. Of the ink cartridge improves the yield and reliability of the ink cartridge,
The cost of the head-integrated ink cartridge can be reduced.

Next, one example of the mechanism of the ink jet recording apparatus equipped with the ink jet head (including the ink cartridge of the head integrated type) according to the present invention is shown in FIG.
This will be described with reference to FIGS. 15 is a perspective explanatory view of the same recording apparatus, and FIG. 16 is a side view of a mechanical section of the same recording apparatus.

This ink jet recording apparatus has a carriage movable in the main scanning direction inside the recording apparatus main body 111, 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 section 112 slides the carriage 123 in the main scanning direction (the direction perpendicular to the paper surface in FIG. 16) by the main guide rod 121 and the sub guide rod 122 which are guide members which 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.

Further, although the heads 124 of the respective colors are used as the recording heads in the present embodiment, a single head having nozzles for ejecting ink droplets of 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 paper carrying direction) and slidably fitted to the slave guide rod 122 on the front side (upstream side in the paper carrying 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, the paper feed roller 131 and the friction pad 132 for separately feeding the paper 113 from the paper feed cassette 114, and the paper 11 are provided.
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 conveying 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.

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 ejection failure occurs, the ejection port (nozzle) of the head 124 is sealed by 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 embodying 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 movable plate 204 (corresponding to a vibrating plate of the head) is provided, and a portion of the movable plate 204 which is not bonded and fixed to the protective substrate 202 is a movable portion 205.

An insulating film 206 is formed on the movable portion 205.
A plurality of electrodes 207, 207 are provided at predetermined intervals on the outer surface side through the same as the inkjet head. Here, similarly to the above-described embodiment of the droplet discharge head, the distance between the electrodes 207, 207 of the movable portion 205 is made narrower in the plane of the movable portion 205 near the central portion than in the vicinity of the fixed end, or the movable portion 205. The thickness of 205 itself is thin in the plane of the movable portion 205 near the fixed end.

The protective substrate 202 has the same function as the second substrate 2 of the head, and has a recess 208 for disposing the electrode 207. Here, the protective substrate 2
In No. 02, the concave portion 208 is formed by providing the spacer portion 209 on the flat plate substrate.

The operation principle of this micropump will be described. As described above, the electrode 2 is supplied by applying a pulse potential to every other electrode 207a, 207b every other electrode.
Since an electrostatic attraction force is generated between 07a and 207b, the movable portion 205 is deformed toward the flow path 203 side. Here, by sequentially driving the movable part 205 from the right side in the drawing, the flow path 2
The fluid in 03 flows in the direction of the arrow, and the fluid can be transported.

In this case, the electrostatic actuator composed of the movable portion 205 and the electrode 207 is stable by setting the electrode interval or the thickness of the movable portion, as in the case of the above-mentioned droplet discharge head. Efficient driving is possible, and the fluid can be stably and efficiently transferred.

In this example, a plurality of movable parts are provided, but the number of movable parts may be one. 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.

The insulating film 306 is formed on the movable portion 305.
A plurality of electrodes 307 and 307 are provided at predetermined intervals on the outer surface side via the, like the inkjet head. Here, similarly to the above-described embodiment of the droplet discharge head, the interval between the electrodes 307, 307 of the movable portion 305 is made narrower in the plane of the movable portion 305 near the central portion than in the vicinity of the fixed end, or the movable portion 305. The thickness of 305 itself is thin in the plane of the movable portion 305 near the fixed end.

The protective substrate 302 has the same function as the second substrate 2 of the head, and has a recess 308 for disposing the electrode 307. Here, the protective substrate 3
In No. 02, the concave portion 308 is formed by providing the spacer portion 309 on the flat plate substrate. A dielectric multilayer film or a metal film may be formed on the surface of the mirror 301 to increase the reflectance.

The principle of this optical device will be described. A plurality of electrodes 30 provided on the movable portion 305 of the mirror 301.
By applying a pulse potential to 7, 307,
Since an electrostatic attraction force is generated between the electrodes 307 and 307, the movable portion 305 is deformed into a convex shape and becomes a convex mirror. Therefore, when the light from the light source 310 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 3
01 when the movable part 305 is driven, the movable part 3
Since 05 serves as a convex mirror, the reflected light becomes divergent light. Thereby, an optical modulation device can be realized.

In this case, the electrostatic actuator composed of the movable portion 305 and the electrode 307 is stable by setting the electrode interval or the thickness of the movable portion, as in the case of the above-mentioned droplet discharge head. It is possible to configure an optical modulation device that can be driven efficiently and can obtain stable operation characteristics.

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 the case of FIG. 18, 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 electrodes 307 and 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 above embodiment, an example in which the inkjet head is used as the droplet discharge head has been described. However, as a droplet discharge head other than the inkjet head, for example, a droplet discharge for discharging a liquid resist as a droplet. 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. Further, the electrostatic actuator can be applied to a micro switch (micro relay), a multi-optical lens actuator (optical switch), a micro flow meter, a pressure sensor, etc., in addition to the micro pump and the light modulation device.

[0109]

As described above, according to the electrostatic actuator of the present invention, the movable portion is provided with a plurality of electrodes made of a conductive structure that is electrically insulated and separated from each other. Since the means for accelerating the deformation is taken, the deformation efficiency of the movable part is improved, the driving efficiency is high, and stable operation characteristics are obtained.

In the electrostatic actuator according to the present invention, the movable portion is provided with the plurality of electrodes made of the electrically conductive structure which are electrically insulated from each other, and the distance between the electrodes is larger than that in the central portion of the movable portion. Since the peripheral portion of the movable portion is narrowed, the deformation efficiency of the movable portion is improved, the driving efficiency is high, and stable operation characteristics are obtained.

In each of these electrostatic actuators according to the present invention, since the thickness of the movable portion is thinnest on the fixed end side of the movable portion, the displacement of the movable portion is facilitated and the displacement efficiency is improved. In addition, since the internal stress of the movable part is tensile stress, variations in displacement due to buckling can be suppressed and characteristics can be stabilized, and fluctuations in the distance between the electrodes can be suppressed, and stable low voltage driving can be achieved. Can be achieved. In this case, the movable part is easily deformed by applying a stress of 1 GPa or less. Further, since the electrodes are arranged substantially parallel to each other, it is possible to obtain a large displacement with good reproducibility by driving at a low voltage.

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 in which the nozzles for ejecting liquid droplets communicate, and the vibrating plate is deformed. Since the electrostatic actuator according to the present invention is provided, stable ejection characteristics can be obtained, and droplet ejection efficiency can be increased.

Here, by adopting a constitution in which the ink cartridge for supplying the ink is integrally provided, a stable ejection characteristic can be obtained and a head-integrated ink cartridge having a high droplet ejection efficiency can be constructed.

According to the ink jet recording apparatus of the present invention, since the ink jet head for ejecting ink droplets is the liquid droplet ejection head of 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 a cross-sectional explanatory view of the same head in the diaphragm longitudinal direction.

FIG. 3 is an enlarged cross-sectional explanatory view of a main part of the head in a lateral direction of a diaphragm.

FIG. 4 is an explanatory plan view for explaining an electrode shape and an arrangement pattern of the head.

FIG. 5 is an enlarged cross-sectional explanatory view of an essential part for explaining the operation of the head.

FIG. 6 is an enlarged cross-sectional view of an essential part of the inkjet head according to the second embodiment in the lateral direction of the diaphragm.

FIG. 7 is an enlarged cross-sectional view of an essential part in the lateral direction of the diaphragm of the inkjet head according to the third embodiment.

FIG. 8 is an explanatory diagram illustrating an example of a manufacturing process of the head according to the second embodiment.

FIG. 9 is an explanatory plan view for explaining an electrode arrangement pattern of the head.

FIG. 10 is an explanatory diagram illustrating a step following FIG.

FIG. 11 is an explanatory plan view illustrating an example of a manufacturing process of the inkjet head according to the third embodiment.

12 is an explanatory diagram illustrating a step following FIG. 11. FIG.

13 is an explanatory diagram illustrating a step following FIG.

FIG. 14 is a perspective view for explaining a head-integrated ink cartridge including a droplet discharge head according to the present invention.

FIG. 15 is a perspective explanatory view illustrating an example of an inkjet recording apparatus according to the present invention.

FIG. 16 is an explanatory diagram of a mechanical section of the recording apparatus.

FIG. 17 is an explanatory diagram illustrating an example of a micropump including an electrostatic actuator according to the present invention.

FIG. 18 is an explanatory diagram illustrating an example of an optical device including an electrostatic actuator according to the present invention.

FIG. 19 is a perspective explanatory view illustrating an application example of 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, 14, 14a, 14b ... Electrodes.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kaihei Isshiki             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2C057 AF03 AF55 AF99 AG12 AG42                       AG43 AG59 AG92 AG93 AP02                       AP22 AP27 AP32 AP34 AP53                       AP56 AP90 AQ02 AQ06 BA04                       BA15

Claims (9)

[Claims] 1. An electrostatic actuator for deforming a movable part, wherein the movable part is provided with a plurality of electrodes made of a conductive structure that is electrically isolated from each other and promotes deformation of the movable part. An electrostatic actuator characterized in that means are provided. 2. An electrostatic actuator for deforming a movable portion, wherein the movable portion is provided with a plurality of electrodes made of a conductive structure that is electrically isolated from each other, and an interval between the electrodes is the movable portion. An electrostatic actuator characterized in that a peripheral portion of a movable portion is narrower than a central portion of. 3. The electrostatic actuator according to claim 1, wherein the thickness of the movable portion is thinnest on the fixed end side of the movable portion. 4. The electrostatic actuator according to claim 1, wherein the movable portion has a tensile stress as an internal stress. 5. The electrostatic actuator according to claim 4, wherein the movable portion has a stress of 1 GPa or less. 6. The electrostatic actuator according to claim 1, wherein the electrodes are arranged substantially parallel to each other. 7. A droplet which has a vibrating plate serving as a movable portion which constitutes at least one wall surface of an ejection chamber in which a nozzle for ejecting the droplet communicates, and which ejects the droplet by deforming the vibrating plate. A droplet discharge head comprising the electrostatic actuator according to any one of claims 1 to 6 for deforming the vibrating plate. 8. The droplet discharge head according to claim 7, wherein an ink cartridge for supplying ink is integrally provided. 9. An ink jet recording apparatus equipped with an ink jet head for ejecting ink droplets, wherein the ink jet head is the liquid droplet ejecting head according to claim 7 or 8.