JP2003211393A - Microactuator, droplet discharge head, ink cartridge, ink jet recording device, micropump, and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a high operating efficiency at low cost. <P>SOLUTION: An insulating film 11 is formed over a diaphragm 10 and a plurality of electrodes 14 electrically insulated from one another and each consisting of an electrically conductive structure are provided on the surface of the insulating film 11. An area 14C is provided where the film thickness of the electrode 14 near the fixed end of the diaphragm is reduced. <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 a microactuator, a droplet discharge head, an ink cartridge, an ink jet recording apparatus, a micro pump and an optical device.

[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 head, a vibrating plate is pushed to the ink chamber side to reduce the internal volume of the ink chamber, thereby driving the ink droplets by a pushing method.
It is a knock-out method that ejects ink droplets by deforming the vibration plate with the force in the outer direction of the ink chamber and returning the displacement of the vibration plate to the original inner volume from the state where the inner volume of the ink chamber is expanded. Some are driven.

As a push type electrostatic head, for example, as described in Japanese Patent Application Laid-Open No. 2-266943, ink is filled between a pair of electrodes, and one or both electrodes are filled. There is a type in which the ink acts as a vibrating plate, and when a voltage is applied between the electrodes, an electrostatic attractive force acts between the electrodes, and the electrodes (vibrating plate) are deformed, whereby the ink is pushed out and ejected.

Further, as described in Japanese Patent Laid-Open No. 2000-15805, a protrusion is provided on the surface of the diaphragm made of a silicon substrate, an electrode is formed on the protrusion, and a voltage is applied to the electrode. There is also a type that ejects ink by deforming the vibration plate by an electrostatic force that acts between the protrusions.

As a pulling-out method, for example, Japanese Patent Laid-Open No. 6-7
As described in Japanese Patent No. 1882, a pair of electrodes is provided via an air gap, one electrode functions as a diaphragm, and ink is filled on the opposite side of the diaphragm to the opposing electrode. An ink chamber is formed, and by applying a voltage between the electrodes (between the vibrating plate and the electrode), an electrostatic attractive force acts between the electrodes, the electrodes (vibrating plate) are deformed, and when the voltage is removed, the vibrating plate becomes elastic. Some return to the original state and use the force to eject ink.

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.

[0011]

However, in the droplet discharge head described in Japanese Patent Laid-Open No. 2-266943, since the ink is filled between the electrodes, the distance between the electrodes inevitably becomes large. Since the electrostatic force acting between the electrodes is inversely proportional to the square of the distance between the electrodes, there is a problem that the required voltage becomes very large as the distance between the electrodes increases. In this case, the voltage can be lowered to some extent depending on the dielectric constant of the ink, but it is not so effective because the distance between the electrodes has a great influence. In addition, the degree of freedom of the ink decreases because it is necessary to increase the dielectric constant of the ink or an electric field is applied to the ink. Therefore, the ink color, p
There is a problem that it is difficult to achieve high image quality because the physical properties of the ink such as H and viscosity are limited.

Further, in the droplet discharge head described in the above-mentioned Japanese Patent Application Laid-Open No. 6-71882, since no ink is filled between the electrodes, there is less restriction on the ink and it is advantageous for high image quality. However, 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, since this is a so-called hitting method in which ink is ejected by the elastic force of the diaphragm, the diaphragm needs to have a rigidity sufficient to eject the ink. There is a problem that the voltage becomes high due to the attraction.

Further, in the droplet discharge head described in the above-mentioned Japanese Patent Laid-Open No. 2001-47624, since the comb-teeth-shaped electrode is used, the displacement amount can be increased, but the generated force is very small, If an attempt is made to obtain the force required to eject ink, the voltage will become extremely high. Moreover, since the structure is complicated, it is difficult to manufacture, and the cost increases.

Further, in the droplet discharge head described in the above-mentioned Japanese Patent Laid-Open No. 2000-15805, a vibration plate formed of a conductive silicon substrate is provided with a projection, and the projection is provided with a conductive member. Since the electrodes are formed, there is a problem in that the electrodes cannot be deformed because the electrostatic potential is not generated between the electrodes via the silicon diaphragm and the electrostatic potential is not generated.

In addition, it is necessary to form a protrusion on the diaphragm and attach an electrode to this protrusion. 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, the interval between the protrusions must be narrowed for lowering the voltage, but it is difficult to form the electrode in such a narrow space, and the electrode is 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 a low cost microactuator having high driving efficiency, a low cost droplet discharging head having high droplet discharging efficiency and high image quality printing, An object of the present invention is to provide an ink cartridge in which this head is integrated, an inkjet recording apparatus capable of high-quality recording, a low cost, high-efficiency micropump and an optical device.

[0019]

In order to solve the above-mentioned problems, a microactuator according to the present invention is a microactuator which deforms a movable part, and the movable part is electrically conductive and electrically isolated from each other. There is provided at least two electrodes composed of a structure having a structure. This electrode is formed so that the vicinity of the fixed end of the movable portion is more easily bent than the other portions, and the movable portion is deformed by generating an electrostatic force between the electrodes. It is what makes me.

Here, it is preferable that the film thickness of the electrode near the fixed end of the movable portion is thinner than that of other portions. Further, it is preferable that a slit is formed in the electrode to provide a thin portion. Furthermore, the two electrodes are preferably arranged in parallel. Furthermore, it is preferable that the electrode is made of polysilicon or single crystal silicon, and in this case, the electrode contains an impurity atom whose conductivity type is n type or p type.

Further, it is preferable that the movable portion and the electrode are electrically separated, and in this case, an insulating film is provided between the movable portion and the electrode, and the insulating film is a silicon oxide film. Is preferred. Furthermore, it is preferable that the movable portion has a tensile stress, particularly a tensile stress of 1 GPa or less.

Further, it is preferable that an insulating film such as a thermal oxide film or a deposited film is provided on the surface of the electrode. Alternatively, it is preferable that a conductive film is formed on the electrode surface.

The droplet discharge head according to the present invention is a droplet discharge head that discharges droplets by deforming a vibrating plate, and includes the microactuator according to the present invention in which the vibrating plate is a movable portion. is there.

The ink cartridge according to the present invention is one in which the droplet discharge head according to the present invention that discharges ink droplets and the ink tank that supplies ink to the droplet discharge head are integrated.

The ink jet recording apparatus according to the present invention is
An inkjet head that ejects ink droplets is the droplet ejection head according to the present invention or the ink cartridge according to the present invention.

The micropump according to the present invention is a micropump that transports a liquid by deformation of a movable part, and includes the microactuator according to the present invention.

An optical device according to the present invention is an optical device that changes the reflection direction of light by displacement of a mirror formed on a movable portion, and includes the microactuator according to the present invention.

[0028]

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 head along the longitudinal direction of the diaphragm (along line AA in FIG. 4), FIG. 3 is a cross-sectional explanatory view of the head along the lateral direction of the diaphragm, and FIG. It is a plane explanatory view showing an electrode arrangement pattern.

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. It has a laminated structure in which the substrates 1, 2 and 3 are stacked and joined, and a plurality of nozzle holes 4 for ejecting ink droplets, an ejection chamber 6 communicating with each nozzle hole 4, and a fluid resistance portion 7 in each ejection chamber 6. A common liquid chamber (common ink chamber) 8 for supplying ink via the same is formed.

The intermediate first substrate 1 is made of a silicon substrate, and has a concave portion for forming the ejection chamber 6 having the bottom wall as the vibration plate 10 and a common liquid chamber for supplying ink to each ejection chamber 6. 8 has a recess for forming 8.

An insulating film 11 such as a thermal oxide film or a silicon nitride film is formed on the lower surface of the vibrating plate 10, and a plurality of electrodes 14 are formed on the surface of the insulating film 11 at predetermined intervals to form the vibrating plate. 10 and each electrode 14 are electrically separated, and two adjacent electrodes of each electrode 14 (relatively referred to as electrodes 14a and 14b) are electrically separated from each other. . The electrode 14 is formed of, for example, polysilicon or single crystal silicon. The vibrating plate 10 and the plurality of electrodes 14 constitute a microactuator according to the present invention that deforms the vibrating plate 10 that is a movable part.

Here, FIG. 4 shows an example of an electrode arrangement pattern for one diaphragm when viewed from the electrode 14 side of the first substrate 1. As shown in the figure, the electrodes 14a and 14b that are electrically separated from each other are
A drive voltage (a voltage of a different potential) that causes a potential difference is applied from a drive circuit (here, shown as an oscillator circuit) 15 via electrode lead lines 14A and 14B. Incidentally, here, the electrode lead lines 14A, 1
4B is arranged outside one vibration plate 10 (meaning a deformable region corresponding to the discharge chamber 6).

Then, the film thickness of the electrode 14 in the vicinity of the fixed end of the vibrating plate 10 which is fixed on all sides (here, in the vicinity of both ends in the longitudinal direction of the vibrating plate), that is, the height of the electrode 14 is reduced. The electrode 14 is preferably thin on one side in a region of about 5 to 30% in the longitudinal direction of the diaphragm. The film thickness (height) of the electrode 14 is preferably as thin as possible in order to increase the vibration displacement, but a certain film thickness is required to secure the response speed.

Therefore, the film thickness of the region 14C of the electrode 14 in the vicinity of the fixed end of the diaphragm is 0.05 μm or more, which is 5 times the electrode height.
It is set to about 0% or less. Even if the electrode 14 is not arranged, the electrode 1 is placed near the fixed end of the diaphragm 10 with small vibration displacement.
By reducing the film thickness of 4 in this way, the diaphragm 1
Compared with the case of the electrode 14 having the same film thickness as that of the center part, the diaphragm 1
0 makes it easier to bend. As a result, the displacement of the diaphragm in the vicinity of the fixed end of the diaphragm can be increased, so that the bending moment acting on the diaphragm can be efficiently converted, and the drive voltage can be further reduced.

Further, a spacer 12 which is a layer or a structural body made of the same material as the electrode 14 is provided on the electrode 1 in a region other than the vibrating plate 10.
It is formed on the substantially same plane as the surface forming 4. 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 and Therefore, defects due to breakage of the electrode 14 during the process can be reduced.

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.

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 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 as shown in FIG. 5, it is statically charged between adjacent electrodes 14b to which the pulse potential is not applied. Electric power is generated, electrostatic attraction works, the free ends of the electrodes 14 (the fixed end on the diaphragm 10 side) attract each other, and the electrodes 14 are displaced.
The displacement of the free end of the electrode causes the diaphragm 10, which is the fixed end of the electrode 14, to bend 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.

When the potential of the electrode 14a returns to 0V, the potential difference between the electrode 14b and the electrode 14b disappears, and the vibration plate 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 calculated 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.

[0042]

[Equation 1]

In the equation (1), F: force acting between electrodes, ε: permittivity, S: area of facing surfaces of 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 vibration plate 10 through the insulating film 11.
By applying a voltage that causes a potential difference between the four opposing electrodes 14a and 14b, an electrostatic attractive force is generated between the adjacent electrodes 14a and 14b, and a slight displacement of the electrode 14 causes the diaphragm 10 to move. A large displacement can be obtained, the droplet ejection efficiency is improved, and high image quality recording is possible.

In the microactuator of this head, the structure itself provided on the vibrating plate 10 acts as the electrode 14, so that it is difficult to form the electrode on the silicon structure by a method such as film formation as before. It is possible to reduce the cost because there is no need for a process, and it is possible to reduce defects such as a short circuit caused by forming electrodes in a very narrow space between structures. 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, the diaphragm 10 and the electrode 14 are made of the insulating film 1.
Since it is electrically separated by 1 or the like, even if a voltage is applied to the electrodes as in the conventional case, all the electrodes are at the same potential via the vibrating plate and malfunction does not occur. The generated voltage does not leak to the diaphragm 10 side, and the voltage can be efficiently applied to the electrode 14. In this case, as an example of electrically separating the vibration plate 10 and the electrode 14, by forming the insulating film 11 between the vibration plate 10 and the electrode 14, it is possible to easily insulate the liquid discharge head with high reliability. Can be obtained. If the diaphragm itself is made of an insulating material, the insulating film may not be provided.

Furthermore, as described above, the electrode 14 is formed to have a thin film thickness in the vicinity of the fixed end of the diaphragm 10 to make the diaphragm 10 easy to bend. The displacement of 10 can be increased, the bending moment acting on the diaphragm can be efficiently converted, and the driving voltage can be reduced.

Next, the ink jet head according to the second embodiment will be described with reference to FIG. The figure is a cross-sectional explanatory view of the same head taken along the longitudinal direction of the diaphragm. Also in this head, the film thickness of the electrode 14 in the vicinity of the fixed end of the diaphragm 10 which is fixed on all sides is thin, that is, the height of the electrode 14 is low. The electrode 14 has about 5 to 5 in the longitudinal direction of the diaphragm on one side.
The film thickness is reduced in the 30% region. 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 the response speed.
Here, the film thickness of the thin region 14C of the electrode 14 is 0.05.
It is set to about μm or more and about 50% or less of the electrode height.
Vibration plate 10 with small vibration displacement even if electrode 14 is not arranged
By making the film thickness of the electrode 14 thin near the fixed end, the electrode 14 having the same film thickness as that of the central portion of the diaphragm 10 can be obtained.
The diaphragm 10 is more easily bent than in the above case.

Further, the electrode 14 is provided with a slit 19 having a depth such that the electrode 14 is not broken. Slit 1
The number of 9 is determined by the length of the electrode 14, that is, the length of the diaphragm 10 (width in the longitudinal direction), but one or more is provided. Slit 19
If the number of the electrodes is increased, the diaphragm 10 is easily deformed, but the area of the electrode 14 is reduced accordingly.
The electrostatic attraction becomes weaker than the formula.

Therefore, if the slit 19 is as narrow as possible, it can contribute to the displacement of the diaphragm 10 efficiently. The width of the slit 19 is preferably about 0.1 to 20 μm, and more preferably 0.1 to 5 μm. Further, as described above, the film thickness of the electrode 13 is preferably as thin as possible in order to increase the vibration displacement, but a certain film thickness is required to secure the response speed. Therefore, the electrode 14 in the slit 19 portion
It is preferable to set the film thickness to about 0.05 μm or more and about 50% or less of the electrode height.

Thus, the electrode 1 near the fixed end of the diaphragm is
Since the film thickness of 4 is thinned to increase the displacement of the vibration plate 10 and the slit 19 is provided in the electrode 14, the electrode 14 is easily deformed along the displaced vibration plate 10, and The bending moment can be efficiently converted into a working bending moment, and the driving voltage can be further lowered.

Next, an ink jet head according to the third embodiment will be described with reference to FIGS. 7 to 9. FIG. 7 is an explanatory view showing the arrangement of electrode patterns for one diaphragm when viewed from the electrode side of the first substrate of the same head, and FIG. 8 is a cross-sectional explanatory view of essential parts taken along the line BB of FIG. , Fig. 9
FIG. 8 is a cross-sectional explanatory view taken along the line CC of FIG. 7.

In this head, the electrode lead-out line 14 is formed on the surface of one diaphragm 10 (which means the deformable region corresponding to the discharge chamber 6 as described above) which is a diaphragm.
A and 14B are arranged so that each electrode lead-out line 14A, 1
The electrodes 14a and 14b adjacent to each other are integrally formed in 4B, respectively, and different potentials are applied to the adjacent electrodes 14a and 14b.

In this case, as shown in FIG. 8, the film thickness of the electrode 14 in the vicinity of the fixed end of the diaphragm 10 which is fixed on all sides is thin, including the electrode lead-out lines 14A and 14B, that is, the height of the electrode 14 is the same. It is low. The electrode 14 has a thin film thickness on one side in a region of about 5 to 30% in the lengthwise direction of the diaphragm. As described above, the film thickness should be as thin as possible in order to increase the vibration displacement, but a certain film thickness is required to secure the response speed. Therefore, the film thickness of the thin region is set to 0.05 μm or more and about 50% or less of the electrode height. As shown in FIG. 9, the electrode lead-out line 14A (the same applies to the electrode lead-out line 14B).
Is a region 1 off one diaphragm 10 in the lateral direction of the diaphragm.
4Aa has a large film thickness.

It was difficult to bend the diaphragm 10 with the electrode 14 having the same film thickness as that of the central portion of the diaphragm 10 even if a high voltage is applied. However, as in the present embodiment, the electrode near the fixed end of the diaphragm 10 is difficult. By making 14 thin, the diaphragm 10 was easily bent. As a result, the displacement of the diaphragm in the vicinity of the fixed end of the diaphragm can be increased, so that it can be efficiently converted into a bending moment acting on the diaphragm, and further, the drive voltage can be lowered.

Further, by providing the slit 19 in the electrode 14 as described in the second embodiment, the vibration plate 10 is further improved.
Since the displacement can be increased, the bending moment acting on the diaphragm can be efficiently converted, and the driving voltage can be further reduced.

Next, an ink jet head according to the fourth embodiment will be described with reference to FIGS. 10 and 11 together with its manufacturing process. In this embodiment, the electrode 14 is made of polysilicon (polycrystalline silicon), and the diaphragm 10 is made of a silicon nitride film having tensile stress as an insulating material.

As shown in FIG. 10A, a silicon substrate having a plane orientation of (110) and a thickness of 400 μm is used as a base substrate 31, and a silicon oxide film 32 as a diaphragm protection layer is formed on the base substrate 31. Vibration plate 10 with a thickness of 2 μm
Then, a silicon nitride film 33 is formed in order to have a thickness of 0.5 μm.

Here, as a method for forming the silicon oxide film 32, there are plasma CVD, sputtering, HTO, TESO and the like. Here, the silicon oxide film 32 on the diaphragm is finally removed by the diaphragm protection layer. Therefore, the manufacturing method is not particularly limited as long as it is a deposited film.

Further, the silicon nitride film 3 which becomes the vibrating plate 10
3 can be formed by a deposited film such as plasma CVD or LPCVD, and has a tensile stress of about 1 to 1.2 GPa. The silicon nitride film 33 becomes a tensile stress and does not cause the diaphragm to buckle, but if the tensile stress is large, the diaphragm is less deformed.
A tensile stress of 0.1 GPa or less is preferable.

In order to reduce the tensile stress of the silicon nitride film 33, impurities such as boron, phosphorus and hydrogen are implanted. For example, the silicon nitride film 33 has a film thickness of 1500Å
When used, the boron atom is 1E14 to 3E15 / cm.
^The stress can be relaxed by implanting energy of 50 KeV with a dose amount of about ² . If the silicon nitride film 33 having a film thickness of 3000 Å is used, boron atoms of 2E
The stress can be relaxed by implanting 80 KeV energy with a dose amount of about 14 to 6E15 / cm ² .

Then, as shown in FIG. 9B, a polysilicon film 34 is formed to a thickness of 5 μm on the surface of the silicon nitride film 33, and an impurity atom of n-type or p-type conductivity is added to the polysilicon film 34. Dope. In the case of n-type conductivity, impurities such as phosphorus and arsenic are implanted. In the case of p-type conductivity type, impurities such as boron are implanted. Then, after the impurity implantation, driving is performed at 1050 ° C. for 120 minutes to reduce the resistance of the polysilicon film 34. By doping impurity atoms to lower the resistance value, it becomes possible to support high frequency driving and multi-channel driving. In addition, by removing the surface of the polysilicon film 34 by polishing, a strong bond can be obtained by direct bonding afterwards.

After that, as shown in FIG. 6C, a resist pattern is formed on the polysilicon film 34 by photolithography, and the polysilicon film 34 is etched by dry etching with an interval of 0.3 μm and a line width of 0.5 μm. Then, the electrode 14 and the spacer portion 12 are formed. At this time, the silicon nitride film 33 becomes an etching stop layer. Electrode 1
The shape of No. 4 is, for example, a comb tooth shape as shown in FIG.

Further, as shown in FIG. 6D (only this (d) is a sectional view along the longitudinal direction of the diaphragm), a resist pattern is formed on the polysilicon film 34 to be the electrode 14 by photolithography, and a dry pattern is formed. Electrode 1 by etching
4 is etched with a line width of 2 μm, and a slit 19 is formed in the electrode 14. At the same time, the thickness of the region 14C from the fixed end of the diaphragm to about 20% of the length of the diaphragm is thinned by photolithography and dry etching. The film thickness of the slit 19 and the region 14C near the diaphragm fixed end is 0.5 μm.

Through the above process, the electrode structure of the electrostatic actuator (microactuator) is completed. Further, 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 or an optical modulation device (optical device) described later. Here, the process of forming the ejection chamber 6 in the base substrate 31 and finishing the droplet ejection head according to the embodiment will be described.

As shown in FIG. 11A, LP- is formed on the entire surface.
A silicon nitride film 36 serving as a mask for etching potassium hydroxide is formed by CVD. Then, as shown in FIG. 3B, the discharge chamber 6 and the common liquid chamber 8 are formed on the silicon nitride film 36.
Liquid chamber-shaped resist pattern is formed, the silicon nitride film 36 in the opening of the resist is removed by dry etching, the resist is removed, and a mask pattern made of the liquid chamber-shaped silicon nitride film 36 is formed. .

After that, as shown in FIG.
The silicon substrate 31 is etched from the opening of the silicon nitride film 36 with 25 wt% potassium hydroxide aqueous solution.
When the etching reaches the silicon oxide film 32, the silicon oxide film 32 is hardly etched, so that the etching stops. In this embodiment, the base substrate (silicon substrate)
Since a (110) plane silicon wafer is used for 31, a 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 6 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) or lithium hydroxide may be used.

Then, as shown in FIG. 6D, 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.

Thus, by forming the electrodes 14 by photolithography and etching, the electrodes 14 and 14 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.

Further, by forming the electrodes 14 of polysilicon, the relatively thick electrodes 14 can be easily formed, and thin grooves between the electrodes 14 can be formed by dry etching. That is, since the distance (gap) between the electrodes 14 can be reduced, a large force can be generated as described above, and it is possible to drive at a low voltage.

Next, an ink jet head according to the fifth embodiment will be described with reference to FIGS. 12 to 14 together with its manufacturing process. It should be noted that only FIG. 13B is a sectional explanatory view taken along the longitudinal direction of the diaphragm, and the other drawings are sectional explanatory views taken along the lateral direction of the diaphragm. Here, the electrode 14 is formed of single crystal silicon. The diaphragm 10 is a high-concentration p-type impurity layer, for example, a high-concentration boron diffusion layer, and the high-concentration p-type impurity layer has the same thickness as the desired diaphragm thickness, here, 1 μm. There is.

That is, as shown in FIG.
Thickness of 400μm with (110) plane orientation as the substrate 1
Boron is diffused into the silicon substrate 41 by ion implantation to form a high-concentration boron diffusion layer 42. Here, the high-concentration boron diffusion layer 42 having a depth of 1 μm is formed. 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 can be removed by thermal oxidation and etching with a hydrofluoric acid-based etching solution. . 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, the diffusion surface is polished to form a smooth surface. As the substrate to be the first substrate 1, instead of the silicon substrate having the (110) plane orientation, (10
A silicon substrate having a 0) plane orientation may be used.

Then, as shown in FIG. 7B, the compound layer is removed and polished, and then the silicon thermal oxide film 43 to be an insulating film is formed to a thickness of 50 n by wet oxidation at 900 ° C. for 5 minutes.
It is formed with a thickness of m. Here, as a method for forming the silicon oxide film, plasma CVD, sputtering, HTO, TEO
Although there are S and the like, a silicon thermal oxide film is preferable in terms of withstand voltage, defects, residual charges, durability and the like.

Then, as shown in FIG.
Another silicon substrate 44 for forming 4 is prepared, and this silicon substrate 44 is 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 is 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. Here, heat treatment was performed at 1000 ° C./2 hours.

Thereafter, as shown in FIG. 6D, the silicon substrate 44 is polished to a thickness of 10 μm which is the desired length (height) of the electrode 14, and impurity atoms of n-type or p-type conductivity are used. Is 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. Next, 1
The silicon electrode 14 is driven at 050 ° C. for 120 minutes to reduce the resistance.

Next, as shown in FIG. 13A, a resist pattern is formed on the silicon substrate 44 polished by photolithography, and the silicon substrate 44 is dry-etched to have a line width of 0.5 μm and an interval of 0.5 μm. The electrodes 14 are formed by etching and the spacers 12 are formed. The shape of the electrode 14 is, for example, a comb tooth shape as shown in FIG. In the etching, the oxide film 43 serves as a stop layer. Dry etching requires ICP (Induced Couple Plasm) because very deep grooves need to be finely etched.
a) is effective.

Thereafter, as shown in FIG. 6B, a resist pattern is formed on the single crystal silicon (silicon substrate) 44 by photolithography, and the electrodes 14 are etched by dry etching to have a line width of 2 μm. The slit 19 is formed in the. At the same time, the region 14C from the fixed end of the diaphragm to about 20% of the length of the diaphragm is thinned by photolithography and dry etching. The film thickness near the slit 19 and the diaphragm fixed end is 0.5 μm. Note that only FIG. 13B is a cross-sectional explanatory view taken along the longitudinal direction of the diaphragm.

Through the above process, the electrode structure of the electrostatic actuator (microactuator) is completed. Further, if the base substrate 41 is removed by etching, an electrostatic actuator is completed, and it can be used for a micropump or an optical modulation device (optical device) described later. Here, the process of forming the ejection chamber 6 in the base substrate 31 and finishing the droplet ejection head according to the embodiment will be described.

As shown in FIG. 13C, a silicon nitride film 46 serving as a mask for potassium hydroxide etching is formed by LP-CVD. Then, as shown in FIG. 14A, a resist pattern having a shape such as the discharge chamber 6 and the common liquid chamber 8 is obtained on the silicon nitride film 46, and the silicon nitride film 46 and the oxide film 43 in the resist opening are formed. Etching is removed by dry etching to remove the resist.

Thereafter, as shown in FIG. 7B, the silicon substrate 41 is formed into a high-concentration boron diffusion layer 42 from the openings of the silicon nitride film 46 and the oxide film 43 with a 25 wt% potassium hydroxide aqueous solution at 80 ° C., for example. Just before reaching (10 remaining
Etching is performed up to about μm.

Next, the etching solution is changed to a 30 wt% potassium hydroxide aqueous solution at 80 ° C. in which IPA is supersaturated, the etching is continued, and when the high-concentration boron diffusion layer 42 is reached, the etching spontaneously stops. .

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 containing IPA, the etching selection ratio between the silicon substrate and the high-concentration boron layer is large, and the etching can be stopped accurately. IP
Since A 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 etchant capable of increasing 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% or EDP may be used other than potassium hydroxide added with IPA.

Thereafter, as shown in FIG. 6C, the silicon nitride film 46 is removed by thermal phosphoric acid, hydrofluoric acid or the like, and the thermal oxide film 43 is removed by hydrofluoric acid or the like.
1 μm thick silicon vibrating plate 10 forming the bottom wall is formed.

Here, since the electrode 14 is formed of single crystal silicon, the thickness (length) of the electrode 14 can be determined by polishing after the wafer is bonded, and the thickness of the electrode 14 cannot be formed by film formation. Thick electrodes can be formed. If the electrode is thick (high in height), the diaphragm can be deformed with a small force and can be driven at a low voltage. Further, it is possible to integrate the drive circuit of the droplet discharge head by utilizing the region of the bonded silicon wafer 44 which is not used as the electrode. The silicon wafer 44 is suitable for forming a drive circuit because it is the same as that used for forming semiconductor elements.

Further, in order to form the high-concentration boron diffusion layer, solid diffusion, coating diffusion, or a boron-doped epitaxial layer can be used 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,
It is also possible to use a method in which an N-type layer or a P-type layer of an N-type silicon substrate is formed on a P-type silicon substrate and electrochemical etching is stopped.

When a semiconductor such as polysilicon or single crystal silicon is used for the electrode 14 as described above,
When high frequency driving and multi-channel driving are performed, the electric resistance value of the electrodes may become a problem. In this case, it is preferable to introduce an impurity atom having n-type or p-type conductivity, for example, phosphorus or arsenic for n-type, boron or antimony for p-type.

Next, an ink jet head according to the sixth 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 embodiment, the insulating film 26 is formed on the surface of the electrode 14. That is, as described above, in order to reduce the driving voltage, the interval between the electrodes 14 must be reduced. However, when the electrodes 14 are formed with such a minute interval, even if the dust is small, If it is placed on the surface 14, it may cause a short circuit, which may cause a malfunction. Also, since the distance is very small, even if a minute water droplet is generated on the surface of the electrode 14 due to the humidity of the air, it may cause a short circuit. .

Therefore, by providing the insulating film 26 on the surface of the electrodes 14, it is possible to reduce malfunctions due to a short circuit between the electrodes 14. Further, discharge may occur between the electrodes 14 when a voltage is applied, which may cause a malfunction. By providing the insulating film 26, the breakdown voltage can be improved, and highly reliable droplet discharge can be achieved. The head is obtained.

Next, the ink jet head according to the seventh embodiment will be described with reference to FIG. It is to be noted that this figure is a cross-sectional explanatory view of the main parts of the electrode portion of the same head along the lateral direction of the diaphragm. Here, a thermal oxide film 27 is used as the insulating film 26 of the sixth embodiment. That is, when single crystal silicon or polysilicon is used for the electrode 14, the thermal oxide film can be uniformly and accurately formed on the electrode surface. Further, the thermal oxide film has high mechanical and electrical reliability, and a highly reliable droplet discharge head can be realized.

In this case, the thermal oxide film 27 grows while consuming about 44% of silicon. Explaining with reference to FIG. 16, the electrode 14 before oxidation is in the state shown by the dotted line A and is provided with a gap G1. When the thermal oxide film 27 having a thickness t is formed on this, silicon having a thickness of about 0.44 t is consumed, and the distance between the electrodes 14 becomes G3 and the space distance becomes G2.

The effective gap G, which is the electrical distance between the electrodes before the thermal oxide film 27 is formed, is G = G1, and the effective gap G ′ when the thermal oxide film 27 of thickness t is formed is
When the dielectric constant of the thermal oxide film is ε, it is expressed by the following equation (2).

[0093]

[Equation 2]

Here, the dielectric constant ε of the thermal oxide film is 3.7 to.
Since 3.9, G '<G, and the effective gap can be reduced by forming the thermal oxide film. As described above, the force acting between the electrodes 14 and 14 can be increased as the effective gap is smaller, and the electrostatic force acting between the electrodes 14 and 14 is inversely proportional to the square of the effective gap. Therefore, by forming a thermal oxide film to reduce the execution gap, the force can be increased or the drive voltage can be lowered. There is a limit in processing the electrodes to form a narrow interval, and when forming the groove by dry etching, the limit is about 0.5 μm. By forming an insulating film on the electrode surface, an effective gap smaller than this limit value can be formed and the driving voltage can be lowered.

Specifically, the dielectric constant of the thermal oxide film used here was 3.8. When G1 is 0.5 μm and the insulating film thickness t is 0.4 μm, the execution gap G ′ is 0.26 μm.
Therefore, the effective gap can be reduced to about 1/2. According to the formula (1) described above, the electrostatic force acting between the electrodes is 3.7 times, and if the same electrostatic force is to be obtained, the voltage can be reduced to about 1/2.

That is, G1 = 0.5 μm (ε = 3.
In the case of 8), when t = 0.2 μm: G2 = 0.28 μm, G ′ =
0.38 μm When t = 0.4 μm: G2 = 0.06 μm, G ′ =
It becomes 0.26 μm.

As a film that consumes and grows silicon, there is a thermal nitride film in addition to the thermal oxide film, and this thermal nitride film can be used as an insulating film having high mechanical and electrical reliability.

Next, an ink jet head according to the eighth embodiment will be described with reference to FIG. It is to be noted that this figure is a cross-sectional explanatory view of the main parts of the electrode portion of the same head along the lateral direction of the diaphragm. Here, a deposited insulating film 28 is used as the insulating film 26 formed on the surface of the electrode 14 of the sixth embodiment. Although the thermal oxide film 27 of the above-described embodiment consumes silicon to form a film, in the present embodiment, the film is deposited without consuming silicon. For example, high temperature heat CV
D, low temperature thermal CVD silicon oxide film, PE-CVD
Silicon oxide film and silicon nitride film, LP-CVD
And a silicon oxide film formed by sputtering, a metal oxide film such as titanium oxide, molybdenum oxide, or tungsten oxide, or a film formed by oxidizing a metal film formed by vacuum evaporation. The film formation by CVD is preferable in that the film can be formed uniformly on the surface of the structure.

Here, as an example of the deposited insulating film 28, a silicon oxide film is formed by high temperature CVD. High temperature CV
Since the silicon oxide film formed by D is deposited and formed on the film formation surface, the electrode surface before film formation and the electrode surface after film formation do not change. Therefore, when the film is formed by the thickness t, the electrode interval G1 before and after film formation does not change, and the space interval becomes G2 which is narrowed by the film thickness.

Here, the effective gap G, which is the electrical gap between the electrodes before the deposited insulating film (oxide film) 28 is formed, is
G = G1. When the oxide film 28 having the thickness t is formed, the effective gap G ′ is expressed by the following equation (3), where ε1 is the dielectric constant of the oxide film.

[0101]

[Equation 3]

Since the dielectric constant ε1 of the silicon oxide film formed by high temperature CVD is 4.0 to 4.5, G '<G,
By forming the oxide film (deposited insulating film), the effective gap can be reduced. Moreover, since the film can be formed without consuming the electrode material like the thermal oxide film of the seventh embodiment, the effective gap can be made smaller than that shown in the seventh embodiment. It is possible to further reduce the voltage. The oxide film used here had a dielectric constant of 4.0. G1 is 0.5μm, t is 0.2μ
m, G'is 0.2 μm and the effective gap is 2
Can be reduced to / 5. When converted into the electrostatic force acting between the electrodes by the above formula (1), it becomes 6 times, and if the same electrostatic force is to be obtained, the voltage can be lowered to 2/5.

That is, G1 = 0.5 μm (ε = 4.
0) and t = 0.2 μm: G2 = 0.1 μm, G ′ = 0.
2 μm.

The higher the dielectric constant, the greater the effect of reducing the effective gap. In addition, the effect of reducing the effective gap becomes greater by using a film having a higher dielectric constant such as a PE-CVD silicon oxide film.

Next, an ink jet head according to the ninth embodiment will be described with reference to FIG. It is to be noted that this figure is a cross-sectional explanatory view of the main parts of the electrode portion of the same head along the lateral direction of the diaphragm. In this embodiment, a conductive film 29 is formed on the surface of the electrode 14. By forming the conductive film 29 on the surface of the electrode, the electrode interval before the film formation was G1, whereas the electrode interval after the film formation of the thickness t is G2 which is twice the film formation thickness. Becomes This makes it possible to reduce the electrode spacing by forming a conductive film, improving the electrostatic force,
It is possible to reduce the driving voltage. Further, by using together with the method of forming the insulating film on the surface of the electrode described in the seventh and eighth embodiments, it is possible to improve reliability and further reduce the voltage.

The conductive film to be formed is polysilicon,
Alternatively, a metal film of aluminum, nickel, tungsten gold, or the like formed by sputtering or vacuum deposition can be used, but polysilicon that can be uniformly formed on the surface of the electrode as the structure is most preferable. In this case, it is preferable to introduce impurity atoms having n-type or p-type conductivity into the polysilicon, for example, phosphorus or arsenic for n-type and boron or antimony for p-type.

Next, the ink cartridge 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 lead to the cost reduction and reliability of the entire ink cartridge, so that the cost reduction and the reliability increase as described above. By improving the performance and reducing manufacturing defects, the yield and reliability of the ink cartridge can be improved, and the cost of the head-integrated ink cartridge can be reduced.

Next, an example of an ink jet recording apparatus equipped with the ink jet head or ink cartridge according to the present invention will be described with reference to FIGS. 20. FIG. 20 is a perspective explanatory view of the recording apparatus, and FIG. 21 is a side view of a mechanical portion of the 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. 21) 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 head-integrated ink cartridge according to the present invention can be 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 here, 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 sheet conveying direction) and slidably fitted to the sub guide rod 122 on the front side (upstream side in the sheet conveying 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 range of movement 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 out 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 a discharge failure occurs, the discharge 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, in this ink jet recording apparatus, since the ink jet head or the ink cartridge embodying the present invention is mounted, there is no ink droplet ejection failure due to defective driving of the diaphragm, and stable ink droplet ejection characteristics are obtained. As a result, 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, the micropump 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 micropump has a laminated structure in which a flow path substrate 201 and a protective substrate 202 are overlapped and bonded to each other. A flow path 203 through which a fluid flows is formed in the flow path substrate 201, and one wall surface of the flow path 203 is formed. A deformable movable plate 204 (corresponding to a vibration plate of the head) to be formed is provided, and the protective substrate 202 of the movable plate 204 is provided.
The portion that is not joined and fixed with is a movable portion 205.

An insulating film 206 is formed on the movable portion 205.
A plurality of electrodes 207 are provided at predetermined intervals on the outer surface side through the same as the inkjet head. 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 202
Is provided with the spacer portion 209 on the flat plate substrate,
08 has been formed.

Explaining the operating principle of this micropump, as described above, since the electrostatic attraction force is generated between the electrodes 207 by applying the pulse potential to the plurality of electrodes 207 every other one, the movable portion 205 is It deforms to 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 embodiment, an example in which a plurality of movable parts are provided is shown, but the number of movable parts may be one. Also, one or more valves between moving parts to increase transport efficiency,
For example, a check valve may be provided.

Next, an embodiment of the optical device 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 plurality of electrodes 307 are provided on the outer surface of the movable portion 305 with an insulating film 306 at predetermined intervals. Protective substrate 3
Reference numeral 02 has a function similar to that of the second substrate 2 of the head, and forms a recess 308 for disposing the electrode 307. Here, the protective substrate 302 has a recess 308 formed by providing a spacer portion 309 on a 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 307 provided on the movable portion 305 of the mirror 301.
To every other pulse potential,
Since an electrostatic attraction force is generated between the electrodes 307, the movable part 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.

Therefore, an example in which this optical device is applied will be described with reference to FIGS. 24 and 25. In this example, the above-mentioned optical devices are two-dimensionally arranged and the movable portion 305 of each mirror is independently driven.
Although a 4 × 4 array is shown here, more arrays are possible. Also, the electrodes can be arranged in a matrix in each of the embodiments of the droplet discharge head described above.

Therefore, similarly to FIG. 23 described above, the light from the light source 310 passes through the lens 311 and the mirror 301.
The light that is applied to the area where the mirror 301 is not driven enters the projection lens 312. On the other hand, a voltage is applied to the electrode 307 to move the movable portion 30 of the mirror 301.
Since the portion where 5 is deformed is a convex mirror, light diverges and hardly enters the projection lens 312. The light incident on the projection lens 312 is projected on a screen (not shown) or the like, and an image can be displayed on the screen.

In the embodiments of the micropump and the optical device, the actuator having the same structure as the ink jet head according to the first embodiment is used.
It is also possible to use an actuator having the same configuration as the inkjet heads according to the following embodiments.

In the above-described embodiment, the example in which the droplet ejection head is applied to the ink jet head has been described. However, as the droplet ejection head other than the ink jet head, for example, the droplet ejection for ejecting the liquid resist as the 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. The microactuator can be applied not only to micropumps and optical devices (light modulation devices) but also to microswitches (microrelays), multi-optical lens actuators (optical switches), microflowmeters, pressure sensors, etc. it can.

[0131]

As described above, according to the microactuator of the present invention, the movable portion is provided with at least two electrodes made of a conductive structure that is electrically insulated and separated from each other. Is formed so that the vicinity of the fixed end of the movable part bends more easily than other parts,
Since the movable portion is deformed by generating an electrostatic force between the electrodes, an actuator that can be driven at low voltage with high operation efficiency and low voltage can be obtained.

Here, the displacement of the movable portion near the fixed end of the movable portion can be increased by making the film thickness of the electrode near the fixed end of the movable portion thinner than the other portions. Further, the slits are formed in the electrode to provide the thin portion, so that the displacement efficiency of the movable portion is further improved.
Further, since the two electrodes are arranged in parallel, a large displacement of the movable portion can be obtained with low reproducibility with good reproducibility.

Furthermore, by forming the electrodes from polysilicon, relatively thick electrodes can be easily formed, and thin grooves between the electrodes can be formed by dry etching, that is, the distance between the electrodes can be increased. Since it can be made small, a large force can be generated, and it becomes possible to drive at a low voltage. Further, by forming the electrodes from single crystal silicon, thick electrodes that cannot be formed by film formation can be formed, and it becomes possible to drive at a lower voltage.

In this case, since the electrode contains impurity atoms of n-type or p-type conductivity, the electrode resistance value which is a problem in high frequency driving and multi-channel driving can be lowered, and power loss due to heat generation is reduced. And lower power consumption

Further, since the movable portion and the electrode are electrically separated, the voltage applied to the electrode does not leak to the movable portion side, the operation is not disabled, and the voltage is efficiently applied to the electrode. Can be applied. In this case, since the insulating film is provided between the movable portion and the electrode, the movable portion and the electrode can be easily electrically separated. In this case, since the insulating film is the silicon oxide film, the insulating property is good, the withstand voltage is high, and the reliability can be improved.

Further, since the movable portion has tensile stress, uneven displacement of the movable portion due to buckling of the movable portion can be suppressed, and the distance between adjacent electrodes can be kept constant, so that a stable low value can be obtained. It can be driven by voltage.
In this case, since the movable portion has a tensile stress of 1 GPa or less, the movable portion can be easily deformed, and malfunctions due to tensile stress can be reliably prevented.

Further, by providing an insulating film on the surface of the electrodes, malfunctions due to short circuit between the electrodes can be reduced, the breakdown voltage can be improved, and the reliability can be improved.
In this case, by providing the thermal oxide film, the effective gap between the electrodes can be reduced, and the force can be increased or the driving voltage can be reduced. Further, by providing the deposited film, the effective gap can be further reduced, and the voltage can be further reduced. Alternatively, by providing a conductive film on the surface of the electrodes, it is possible to reduce the electrode interval and reduce the driving voltage.

According to the droplet discharge head of the present invention, the droplet discharge head which discharges droplets by deforming the vibrating plate is provided with the microactuator of the present invention having the vibrating plate as a movable portion. Therefore, it is possible to obtain a head that is low in cost, high in droplet ejection efficiency, and capable of high-quality printing.

According to the ink cartridge of the present invention, the droplet discharge head according to the present invention that discharges ink droplets and the ink tank that supplies ink to the droplet discharge head are integrated, so that the droplets can be produced at low cost. It is possible to integrate a head having high ejection efficiency and capable of high-quality printing, reduce manufacturing defects, and reduce costs.

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 or the ink cartridge of the present invention, high image quality recording can be performed. Further, the cost of the device can be reduced.

The micropump according to the present invention is a micropump for transporting a liquid by deformation of a movable part, and is equipped with the microactuator according to the present invention. Therefore, the operation efficiency is high, the size is small, and the consumption is low. It is possible to reduce power consumption as well as cost.

According to the optical device of the present invention, the optical device changes the reflection direction of light by the displacement of the mirror formed on the movable part, and is equipped with the microactuator of the present invention. The power consumption can be reduced and the cost can be reduced.

[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 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 explanatory cross-sectional view of a main portion of the inkjet head according to the second embodiment, taken along the longitudinal direction of the diaphragm.

FIG. 7 is an explanatory diagram illustrating the arrangement of electrode patterns of the inkjet head according to the third embodiment.

FIG. 8 is an explanatory sectional view taken along line BB in FIG.

9 is a cross-sectional explanatory view taken along the line CC of FIG.

FIG. 10 is an explanatory diagram illustrating an inkjet head according to the fourth embodiment together with a manufacturing process thereof.

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

FIG. 12 is an explanatory diagram for explaining the inkjet head according to the fifth embodiment together with the manufacturing process thereof.

13 is an explanatory diagram illustrating a step following FIG.

14 is an explanatory diagram illustrating a step following FIG.

FIG. 15 is an explanatory cross-sectional view of essential parts along the lateral direction of the diaphragm of the inkjet head according to the sixth embodiment.

FIG. 16 is an enlarged explanatory view of an electrode portion along the lateral direction of the diaphragm of the inkjet head according to the seventh embodiment.

FIG. 17 is an enlarged explanatory view of an electrode portion along the lateral direction of the vibration plate of the inkjet head according to the eighth embodiment.

FIG. 18 is an enlarged explanatory diagram of an electrode portion along the lateral direction of the diaphragm of the inkjet head according to the ninth embodiment.

FIG. 19 is a perspective explanatory view for explaining the ink cartridge according to the invention.

FIG. 20 is a perspective explanatory diagram illustrating an example of an inkjet recording apparatus according to the present invention.

FIG. 21 is an explanatory diagram of a mechanical section of the recording apparatus.

FIG. 22 is an explanatory sectional view showing an embodiment of a micropump according to the present invention.

FIG. 23 is a sectional explanatory diagram illustrating an embodiment of an optical device according to the present invention.

FIG. 24 is a perspective explanatory view illustrating an example of a light modulation device using the optical device.

FIG. 25 is a perspective view for explaining a main part of the optical modulation 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 ... Electrode, 26 ... Insulating film, 100 ... Ink cartridge, 201 ... Flow path substrate, 203 ... Flow path, 2
05 ... Movable part, 207 ... Electrode, 301 ... Mirror, 30
5 ... Movable part, 307 ... Electrode.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F04B 43/12 G02B 26/08 E 3H077 G02B 5/10 H02N 1/00 B41J 3/04 103A 7/182 103H 26/08 G02B 7/18 Z H02N 1/00 (72) Inventor Kahei Isshiki 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Shinji Tanaka 1-chome, Nakamagome, Ota-ku, Tokyo No. 3-6 F-term in Ricoh Co., Ltd. (reference) 2C057 AF55 AF93 AG52 AG55 AG93 AP02 AP32 AP34 AP56 AQ02 BA03 BA15 2H041 AA11 AB14 AB38 AC06 AZ05 AZ08 2H042 DA01 DA08 DA12 DA20 DC08 DD11 DE00 2H043 CA10 CD04 CE21 3H07575 CC34 DA05 DA11 DB01 DB49 3H077 AA06 BB10 CC01 CC10 DD05 DD11 EE02 EE36 FF06 FF13 FF32

Claims (20)

[Claims] 1. A microactuator for deforming a movable part, wherein the movable part comprises at least two electrically conductive structures that are electrically isolated from each other.
One electrode is provided, and the electrode is formed so that the vicinity of the fixed end of the movable portion is bent more easily than the other portions, and the movable portion is deformed by generating an electrostatic force between the electrodes. Micro actuator. 2. The microactuator according to claim 1, wherein the film thickness of the electrode in the vicinity of the fixed end of the movable portion is thinner than that of other portions. 3. The microactuator according to claim 1, wherein a slit is formed in the electrode to provide a thin portion. 4. The microactuator according to claim 1, wherein the two electrodes are arranged in parallel. 5. The microactuator according to any one of claims 1 to 4, wherein the electrode is made of polysilicon or single crystal silicon. 6. The microactuator according to claim 5, wherein the electrode contains an impurity atom whose conductivity type is n type or p type. 7. The microactuator according to claim 1, wherein the movable portion and the electrode are electrically separated from each other. 8. The microactuator according to claim 7, wherein an insulating film is provided between the movable portion and the electrode. 9. The microactuator according to claim 8, wherein the insulating film is a silicon oxide film. 10. The microactuator according to claim 1, wherein the movable portion has tensile stress. 11. The microactuator according to claim 10, wherein the tensile stress of the movable portion is 1 GP.
A microactuator having a stress of a or less. 12. The microactuator according to claim 1, wherein an insulating film is formed on the electrode surface. 13. The microactuator according to claim 12, wherein the insulating film is a thermal oxide film. 14. The microactuator according to claim 12, wherein the insulating film is a deposited film. 15. The microactuator according to claim 12, wherein a conductive film is formed on the surface of the electrode. 16. A single or a plurality of nozzle holes for discharging liquid droplets, and a discharge chamber communicating with each of the nozzle holes,
A vibrating plate that forms at least one wall of the ejection chamber, wherein the vibrating plate is a movable part in a droplet ejection head that ejects droplets by deforming the vibrating plate. A liquid droplet ejection head comprising the microactuator according to any one of the claims. 17. An ink cartridge in which a droplet discharge head that discharges an ink droplet and an ink tank that supplies ink to the droplet discharge head are integrated, and the droplet discharge head according to claim 16 is provided. Ink cartridge characterized by. 18. An inkjet recording apparatus equipped with an inkjet head for ejecting ink droplets, wherein the inkjet head is the droplet ejection head according to claim 16 or the ink cartridge according to claim 17. Inkjet recording device. 19. A micropump for transporting a liquid by deformation of a movable part, comprising the microactuator according to any one of claims 1 to 15. 20. An optical device for changing the reflection direction of light by displacement of a mirror formed on a movable portion,
An optical device comprising the microactuator according to any one of claims 1 to 15.