JP2003266695A - Electrostatic actuator, liquid drop discharge head and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that stable and high driving efficiency and performance characteristic cannot be obtained at low costs. <P>SOLUTION: Electrodes 14a and 14b for generating an electrostatic force are set at a diaphragm 10, which comprise structural bodies electrically isolated from each other and having conductive properties. Moreover, a dielectric material 19 and an inert gas are filled in a space 18 where the electrodes face. <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.

Furthermore, when the protrusion is formed integrally with the diaphragm, the height of the protrusion is determined by the depth of the groove by a processing method such as etching, laser machining, electric discharge machining, or machining, so that the height accuracy is high. Difficult to process well. The amount of deflection of the diaphragm depends on the height of the protrusions, and if the height of the protrusions varies, it causes the amount of deflection of the diaphragm, causing variations in liquid ejection characteristics. Further, since the interval between the protrusions is formed by machining the groove, it is difficult to form a minute interval. Furthermore, the electrostatic force acting between the protrusions depends on the distance between the protrusions and is inversely proportional to the square of the distance between the protrusions. Therefore, if the distance between the protrusions is large, the electrostatic force is rapidly reduced and the driving voltage is increased. There is also the problem that the value must be raised.

The present invention has been made in view of the above problems, and is an electrostatic actuator that is low in cost, high in driving efficiency, and capable of obtaining stable operation characteristics. It is an object of the present invention to provide a droplet discharge head that has a high temperature and stable droplet discharge characteristics, and an inkjet recording apparatus that includes this droplet discharge head and that can perform high-quality recording.

[0016]

In order to solve the above-mentioned problems, an electrostatic actuator according to the present invention is composed of conductive structures which are insulated and separated from each other in a movable part thereof, and generate electrostatic force between them. For this purpose, a plurality of electrodes are provided, and the space facing the electrodes is filled with a dielectric material.

Here, it is preferable that the space facing the electrodes is filled with a dielectric material and gas, and more preferably the gas is an inert gas. Further, it is preferable that substantially the entire surface of the electrode is in contact with the dielectric material. Further, it is preferable to have a damper chamber which communicates with the space, and this damper chamber can communicate with a plurality of spaces.

The droplet discharge head according to the present invention comprises a vibrating plate having a movable part forming a part of the wall surface of the discharge chamber communicating with the nozzle hole for discharging a droplet, and deforming the movable part of the vibrating plate. The electrostatic actuator according to the present invention is provided. Here, an ink tank for supplying ink can 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.

[0020]

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. FIG. 2 is a cross-sectional explanatory view of the head in the lateral direction of the diaphragm, and FIG. 3 is a plan explanatory view showing an electrode arrangement pattern of the 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 is made of a silicon substrate, and has a penetrating portion for forming the ejection chamber 6 having the bottom wall as the vibration plate 10 and a common liquid for supplying ink to each ejection chamber 6. It has a penetration for forming the chamber 8.

The diaphragm 10 is a high-concentration p-type impurity diffusion layer,
A film having conductivity 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, is not particularly limited as long as the film has strength enough to withstand liquid discharge pressure. Not a thing. However, diaphragm 1
When a conductive film is used for 0, the insulating film (layer) 11 is formed on the surface (outer surface) opposite to the ejection chamber 6.

Here, the insulating film 1 is formed on the lower surface of the diaphragm 10.
1 and a plurality of electrodes 14 are formed on the surface of the insulating film 11 and have a conductive structure that is electrically isolated from each other, and have a plurality of electrodes 14 for generating an electrostatic force therebetween. is doing.

In this case, the vibrating plate 10 and each electrode 14 are electrically separated by the insulating film 11, and two adjacent electrodes 14 (each of which is the electrode 14a) to which different potentials are applied. , Electrode 14b) are also electrically separated from each other by the air gap. Vibration plate 10 and multiple electrodes 1
4 constitutes the electrostatic actuator according to the present invention which deforms the vibrating plate 10 (the deformable region corresponding to the discharge chamber 6) which is the movable part.

The electrodes 14a and 14b are shown in FIG.
As shown in FIG. 3, the drive circuit (here, the oscillator circuit is shown) 15 applies drive voltages (voltages of different potentials) that generate a potential difference to each other.

A space 18 facing the electrodes 14a and 14b is formed between the lower surface of the first substrate 1 and the recess 16 formed in the second substrate 2, and a dielectric material 19 and a gas are stored in the space 18. Filling.

In this case, the electrodes 14a, 14b are made so that substantially the entire surfaces of the electrodes 14a, 14b are in contact with the dielectric material 19.
By filling the dielectric material 19 between them, the electrostatic force can be efficiently generated. The gas is filled with an inert gas. By filling the inert gas, the characteristic variation of the dielectric material 19 can be suppressed, and stable operation characteristics and driving characteristics can be maintained for a long period of time.

Further, the partition wall portion 2 between the discharge chambers 6 of the first substrate 1
At 0, a damper chamber 21 communicating with the space 18 is formed. The damper chamber 21 can be formed so as to communicate with the two spaces 18 corresponding to the two adjacent discharge chambers 6, or can be formed outside the longitudinal end of the diaphragm along the lateral direction of the diaphragm. By providing it, it is possible to communicate with each space 18 corresponding to three or more ejection chambers 6, and by communicating with a plurality of spaces 18, it is possible to suppress an increase in the chip size of the head.

The second substrate 2 may be a substrate made of glass, metal, silicon, resin or the like, and the depth of the recess 16 may be about 1 mm. In addition, the concave portion 1 common to the plurality of diaphragms 10
6 to form the space 18 into a plurality of diaphragms 10.
It can also be formed corresponding to.

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.

The operation of the ink jet head thus constructed will be described. For example, in the configuration of FIG. 4, when a pulse potential of 0V to 40V is applied to the first electrode 14a by the oscillation circuit 15, the surface of the first electrode 14a is positively charged, and the adjacent first electrode 14a to which the pulse potential is not applied is applied. An electrostatic force is generated between the second electrode 14b and the second electrode 14b, and an electrostatic attraction action is exerted, so that the free ends (the vibrating plate 10 side is the fixed end) of the first and second electrodes 14a and 14b are attracted to each other.
4b is displaced, and the free ends of these electrodes 14a, 14b are displaced, so that the vibration plate 10, which is the fixed ends of the electrodes 14a, 14b, is bent upward. As a result, the pressure in the ejection chamber 6 rapidly rises, and the ink droplets 22 are ejected from the nozzle holes 4 toward the recording paper 23 as shown in FIG.

When the potential of the first electrode 14a returns to 0V, the potential difference between the first electrode 14a and the second electrode 14b disappears,
The diaphragm 10 is restored to 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. The first electrode 14
The application of different potentials to a and the second electrode 14b may be reverse to the above.

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. Therefore, in order to drive at a low voltage, the distance between the first electrode 14a and the second electrode 14b, that is, the electrode 1
It is important to form a narrow groove between the four. It is also important to increase the area S of the portion where the electrostatic force acts, and the area S can be increased by increasing the height of the electrode 14. Further, it is important to increase the dielectric constant ε between the electrodes.

[0035]

[Equation 1]

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

In this way, the electrodes 14a, 14 which are electrically separated and independent from each other are formed in the movable portion of the diaphragm 10.
By providing b and applying a voltage that causes a potential difference between them, an electrostatic attractive force is generated between the adjacent electrodes 14a and 14b, and a slight displacement of the electrode 14 causes a large displacement of the diaphragm 10. The electrostatic actuator that can be obtained is obtained, and by using this electrostatic actuator,
Stable droplet ejection characteristics are obtained, droplet ejection efficiency is improved, and high image quality recording is possible.

Further, since the diaphragm 10 and the electrodes 14 are electrically separated, even if a voltage is applied to the electrodes as in the conventional case, all the electrodes have the same potential through the diaphragm. There is no malfunction and the voltage applied to the electrode 14 does not leak to the vibrating plate 10 side.
A voltage can be applied to 4. Further, since the vibrating plate 10 is insulated from the electrode 14, the drive voltage is not applied to the liquid (here, ink), and the liquid may be deteriorated by electrolysis when the drive voltage is applied. In addition, reliability is improved and high quality recording is possible.

Then, in this embodiment, the electrode 1
Since the space 18 exposed by 4 is filled with the dielectric material 19 and the gas, a large electrostatic force can be generated between the electrodes 14a and 14b with the same driving voltage, or the same electrostatic force can be generated. Since the driving voltage can be lowered, the driving efficiency is further improved and the droplet ejection efficiency is improved.
Alternatively, further lower voltage driving can be achieved.

Further, since the damper chamber 20 communicating with the space 18 filled with the dielectric material 19 and the gas is provided,
The dielectric material 19 and the gas can be moved, and the diaphragm 1
Resistance to 0 deformation can be suppressed, and more efficient driving can be performed.

Therefore, an example of the manufacturing process of this head will be described with reference to FIGS. First, FIG.
As shown in FIG. 3A, a silicon substrate 31 having a crystal orientation (110) is used, and as shown in FIG.
A recess forming 0 (hereinafter simply referred to as "damper chamber 20")
A resist pattern 32 for forming the is formed, and the damper chamber 20 is formed by dry etching or wet etching.

Thereafter, as shown in FIG. 3C, a nitride film 33 for forming a vibration plate is formed on the silicon substrate 31 by LP-CVD to a thickness of 0.2 to 0.3 μm, and the nitride film 33 is formed. An oxide film 34 having a thickness of 0.1 μm and a polysilicon film 35 having a thickness of 1.5 to 3.0 μm are formed thereon.

Then, as shown in FIG. 3D, the electrode 1 made of polysilicon 35 is formed by digging the groove of the polysilicon 35 by photolithography and etching.
4 is formed, and as shown in FIG.
The oxide film 34 and the nitride film 33 other than the portion corresponding to are removed to form the diaphragm 10 made of the nitride film 33 having the oxide film 34 on the outer surface. The diaphragm 10 may be a laminated film of the oxide film 34 and the nitride film 33.

On the other hand, as shown in FIG. 5A, a silicon substrate 41 having a plane orientation (110) to be the second substrate 2 is prepared, and an oxide film 42 is formed as shown in FIG. 5B. hand,
As shown in FIG. 3C, the recess 16 is formed in the oxide film 42.

Thereafter, as shown in FIG. 6A, the silicon substrate 31 and the silicon substrate 41 are directly bonded to each other, and then the nitride film 45 serving as a mask is formed by LP-CVD as shown in FIG. 6B. And a silicon substrate 31 is formed by etching with a KOH solution as shown in FIG.
A penetrating portion to be the discharge chamber 6 (simply referred to as the discharge chamber 6) is formed in the.

Then, as shown in FIG. 7A, the nitride film 4 is formed.
5 is removed, the nozzle plate 3 is bonded onto the silicon substrate 31 as shown in FIG. 2B, and the dielectric material 19 is formed in the space 18 facing the electrode 14 as shown in FIG. Fill with gas (inert gas).

Next, an ink cartridge (ink tank integrated head) in which the droplet discharge head and the ink tank according to the present invention are integrated will be described with reference to FIG.
The ink cartridge-integrated head 50 is one in which the inkjet head 52 of any of the above-described embodiments having a nozzle hole 51 and the like and an ink tank 53 that supplies ink to the inkjet head 52 are integrated. .

By thus integrating the ink jet head, which is the droplet discharge head according to the present invention, and the ink tank, a head-integrated ink cartridge having excellent droplet discharge efficiency and stable droplet discharge characteristics can be obtained. Obtainable. Further, when the driver is mounted on the ink cartridge, the driver cost is also mounted on the ink cartridge. Since the droplet discharge head according to the present invention can be driven at a low voltage, the withstand voltage of the driver can be small and the cost can be reduced.

Next, an example of the mechanism of the ink jet recording apparatus equipped with the ink jet head (including the ink cartridge) according to the present invention will be described with reference to FIGS. 9 and 10. 9 is a perspective explanatory view of the same recording apparatus, and FIG. 10 is a side view of a main part of a mechanical section of the same recording apparatus.

In this ink jet recording apparatus, a main guide rod 62 and a sub guide rod 63 are horizontally mounted on a frame 61 in a substantially horizontal positional relationship, and the main guide rod 62 and the sub guide rod 63 move a carriage 65 in the main scanning direction. It is slidably supported on.

The carriage 65 is equipped with four heads 66 for ejecting yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (Bk) ink, respectively. The head 66 in this recording apparatus is configured as an edge shooter type head. Further, the carriage 65 has four ink cartridges 67 for supplying ink of each color to the head 66.
The y, 67m, 67c and 67k are exchangeably mounted.

The head 66 may be composed of a seven-color head in which, in addition to the above-mentioned four colors, three colors of light cyan, light magenta and light yellow are added. Further, as the head 66, a multi-color nozzle head having nozzles that eject ink droplets of each color with one head can be used instead of an independent head for each color.

Ink cartridge 67 (y, m, c,
k) is an atmosphere port communicating with the atmosphere in the upper part, and the head 6 is in the lower part.
6 has a supply port for supplying ink to each inkjet head, and has a porous body filled with ink inside, and the ink supplied to the inkjet head is slightly negative due to the capillary force of the porous body. The pressure is maintained. Ink is supplied from the ink cartridge 67 into each inkjet head of the head 66.

The carriage 65 is connected to a timing belt stretched between a drive pulley (driving timing pulley) rotated by a main scanning motor (not shown) and a driven pulley (idler pulley) to drive the main scanning motor. The carriage 65 is controlled to move and scan in the main scanning direction.

Further, the paper 7 set on the guide plate 68
0 is taken in by the platen roller 73 which is rotated by a drive source (not shown) via the drive gear 71 and the sprocket gear 72, and is indicated by the peripheral surface of the platen roller 73 and the guide roller 74 and the pressure roller 75 that are in pressure contact with the platen roller 73. It can be transported in the B direction. A knob 73a is attached to the platen roller 73.

In this ink jet recording apparatus, while the carriage 65 is moved and scanned in the main scanning direction (A direction indicated by the arrow), ink droplets are ejected from each head of the recording head 76 to form an image of one line on the paper 70. Is printed,
An image is recorded on the sheet 70 by repeating the operation of conveying the sheet 70 by one line in the sub-scanning direction (the direction of arrow B).

Although not shown, a head 66 is provided at a position outside the recording area on the right end side of the carriage 65 in the moving direction.
A recovery device for recovering the ejection failure of is disposed.
The recovery device has a cap unit, a suction unit, and a cleaning unit. The carriage 65 is moved to the recovery device side while waiting for printing, and the head 66 is moved by the capping means.
The ejection port portion (nozzle hole) is kept wet to prevent ejection failure due to ink drying. Further, by ejecting (purging) ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant, and stable ejection performance is maintained.

When an ejection failure occurs, the ejection port (nozzle) of the head 66 is sealed by the capping means, and the ink is adsorbed on the ejection port surface by the suction means through the tube together with the ink. The dust and the like are removed by the cleaning means and the ejection failure is recovered. 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 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 arranged at predetermined intervals on the outer surface side via the, like the inkjet head.

The protective substrate 202 has the same function as the second substrate 2 of the head, and forms a space 208 for arranging the electrodes 207. Here, the protective substrate 2
02 is a flat plate substrate provided with a spacer portion 209 to form a space 208 facing the electrode 207 between the movable plate 204 and the protective substrate 202.
10 and gas are filled.

The principle of operation of this micropump will be described. As described in the operation of the droplet discharge head, a pulse potential is applied to the plurality of electrodes 207, 207 every other pulse, so that the electrodes 207, 207 are electrically connected to each other. Since the electrostatic attraction force is generated, 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 fluid in the flow path 203 flows in the direction of the arrow, and the fluid can be transported.

In this case, since the electrostatic actuator composed of the movable portion 205 and the electrode 207 is structured in the same manner as the electrostatic actuator composed of the vibrating plate and the electrode of the droplet discharge head described above, the driving efficiency is improved. Improved and stable driving characteristics can be obtained, 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. A dielectric multilayer film or a metal film may be formed on the surface of the mirror 301 to increase the reflectance.

The movable portion 305 has an insulating film 306.
A plurality of electrodes 307, 307 are arranged at predetermined intervals on the outer surface side via the, like the inkjet head. The protective substrate 302 has the same function as the second substrate 2 of the head, and forms a space 308 for disposing the electrode 307. Here, the protective substrate 302 is provided with a spacer portion 309 on a flat plate substrate so that the mirror 3
01 and the protective substrate 302 between the space 307 facing the electrode 307
08 is formed to fill the space 308 with the dielectric material and the gas.

The principle of this optical device will be described. As with the operation of the droplet discharge head, the mirror 3
01, the plurality of electrodes 307, 30 provided on the movable part 305.
7 by applying a pulsed potential to the electrode 30
Since an electrostatic attraction force is generated between the moving parts 30 and 30,
5 is transformed into a convex shape to form a convex mirror. Therefore, the light from the light source 310 passes through the lens 311 and the mirror 301.
When the mirror 301 is not driven,
The light is reflected at the same angle as the incident angle, but when the movable portion 305 is driven by the mirror 301, 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, since the electrostatic actuator composed of the movable portion 305 and the electrode 307 is constructed in the same manner as the electrostatic actuator composed of the vibrating plate and the electrode of the droplet discharge head described above, A stable and efficient driving is possible, and 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 the case of FIG. 12, 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 each of the embodiments described above,
Although the electrode 14 is shown as being separated in only one direction,
The electrodes 14 are separated into a grid pattern as shown in FIG.
(Or the movable part) may be biaxially deformed.

In the above-described embodiment, an example in which the droplet ejection head is applied to an ink jet head has been described. However, as a droplet ejection head other than the ink jet head, for example, a droplet ejection for ejecting 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.

[0074]

As described above, according to the electrostatic actuator of the present invention, the movable portion is composed of the conductive structures that are insulated and separated from each other, and the plurality of movable members are provided for generating electrostatic force. Since the electrode is provided and the space facing this electrode is filled with the dielectric material, at a low voltage,
It is possible to obtain an actuator having high driving efficiency and capable of stable driving.

According to the droplet discharge head of the present invention, since the electrostatic actuator according to the present invention for deforming the movable portion of the vibration plate is provided, the droplet discharge efficiency is high and the droplet discharge is stable. The characteristics are obtained.

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 showing an inkjet head according to an embodiment of a droplet discharge head of the present invention.

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

FIG. 3 is an explanatory plan view for explaining an electrode arrangement pattern of the head.

FIG. 4 is a first diagram for explaining an example of a manufacturing process of the head.
Explanatory drawing explaining the manufacturing process on the substrate side

FIG. 5 is an explanatory view illustrating a manufacturing process on the second substrate side.

FIG. 6 is an explanatory diagram illustrating a step following FIG. 4 and FIG.

FIG. 7 is an explanatory diagram illustrating a step following FIG.

FIG. 8 is an explanatory perspective view for explaining an ink tank integrated head including a droplet discharge head according to the present invention.

FIG. 9 is an explanatory perspective view illustrating an example of an inkjet recording apparatus according to the present invention.

FIG. 10 is an explanatory diagram of a mechanical section of the recording apparatus.

FIG. 11 is an explanatory diagram illustrating an example of a micropump including an electrostatic actuator according to the present invention.

FIG. 12 is an explanatory diagram illustrating an example of an optical device including an electrostatic actuator according to the present invention.

FIG. 13 is a perspective explanatory view illustrating an example of a light modulation device using the optical device.

FIG. 14 is a perspective explanatory view for explaining another example of the electrode configuration.

[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, 11 ... Insulating film, 14 ... Electrode, 18 ... Space that the electrode faces, 19 ... Dielectric material, 20 ... Damper chamber, 50 ...
Ink tank integrated head, 66 ... Recording head, 201
... flow path substrate, 203 ... flow path, 205 ... movable part, 207
... electrodes, 301 ... mirrors, 305 ... movable parts, 307 ...
electrode.

Continued front page    (72) Inventor Tadashi Mimura             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh (72) Inventor Akira Shimizu             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2C057 AF52 AF55 AG53 AG54 AG56                       BA04 BA14 BA15

Claims (9)

[Claims] 1. An electrostatic actuator for deforming a movable part, wherein the movable part is provided with a plurality of electrodes that are made of a conductive structure that is insulated and separated from each other, and that are provided with a plurality of electrodes for generating mutual electrostatic force. An electrostatic actuator characterized in that a space facing a space is filled with a dielectric material. 2. The electrostatic actuator according to claim 1, wherein a space facing the electrode is filled with a dielectric material and a gas. 3. The electrostatic actuator according to claim 2, wherein the gas is an inert gas. 4. The electrostatic actuator according to claim 1, wherein substantially the entire surface of the electrode is in contact with the dielectric material. 5. The electrostatic actuator according to claim 1, further comprising a damper chamber communicating with the space. 6. The electrostatic actuator according to claim 5, wherein the damper chamber communicates with a plurality of spaces. 7. A droplet having a movable portion forming a part of a wall surface of a discharge chamber communicating with a nozzle hole for discharging the droplet, and the droplet being discharged by deforming the diaphragm. A droplet discharge head comprising the electrostatic actuator according to any one of claims 1 to 6, which deforms a movable portion of the vibrating plate. 8. The droplet discharge head according to claim 7, further comprising an ink tank for supplying ink. 9. An ink jet recording apparatus having an ink jet head for ejecting ink droplets, wherein the ink jet head is the liquid droplet ejecting head according to claim 7.