JP2003276195A - Electrostatic actuator, liquid drop ejection head and ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that stabilized drop ejection characteristics cannot be attained at a low cost. <P>SOLUTION: A bend part 11 is formed in a diaphragm 10 by forming recesses 10a and 10b in the opposite sides thereof and two electrically isolated conductive electrodes 14a and 14b are provided in the recess 10b of the bend 11 through an insulating film 12. <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 microdevices such as pressure sensors.

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

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

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

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

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

[0009]

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

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

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

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

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

The present invention has been made in view of the above problems, and is provided with an electrostatic actuator that is low in cost, high in driving efficiency (deformation efficiency), and capable of obtaining stable operation characteristics. An object of the present invention is to provide a liquid droplet ejection head that is low in cost, has high droplet ejection efficiency, and can obtain stable droplet ejection characteristics, and an inkjet recording apparatus that is equipped with this liquid droplet ejection head and is capable of high-quality recording. .

[0015]

In order to solve the above problems, an electrostatic actuator according to the present invention has a bending portion in a movable portion, and the bending portion is electrically insulated and separated from each other, and At least 2 for generating electrostatic attraction
It is provided with two electrodes.

Here, at least two electrodes for generating electrostatic attraction between each other can be arranged substantially parallel or non-parallel. Further, it is preferable that the bent portion is formed by at least two grooves arranged in different directions. Furthermore, the thickness of the bent portion of the movable portion is made thinner than that of the other portion, or. It is preferable that the bent portion of the movable portion has a thin portion and a thick portion.

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

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

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

[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 including an electrostatic actuator of the present invention, and is shown in a partial cross-sectional view. 2 is a cross-sectional explanatory view of the same head in the longitudinal direction of the diaphragm, FIG. 3 is a cross-sectional explanatory view of the same head in the lateral direction of the diaphragm, FIG. FIG. 6 is an explanatory view of the plate seen from the bottom surface side, and FIG. 6 is an explanatory plan view of 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.

The intermediate first substrate 1 is made of a silicon substrate, and has a concave portion for forming the discharge chamber 6 and each discharge chamber 6.
It has a concave portion for forming a common liquid chamber 8 for supplying ink to. On the bottom surface of the first substrate 1, a vibrating plate (movable part) 10 which is also a bottom wall of the discharge chamber 6 and the common liquid chamber 8 is integrally formed.

The diaphragm 10 has concave portions (grooves) 10a and 10b having a rectangular cross-section formed on both sides thereof to form a bent portion 11 thinner than other portions bent in the sectional shape. Then, an insulating film 12 (see FIG. 4) such as a silicon oxide film or a silicon nitride film is formed in the recess 10b on the lower surface side of the bent portion 11, and the surface of the insulating film 12 is electrically insulated from each other. Two electrodes 14 for generating an electrostatic force between the separated conductive members are arranged substantially parallel to each other. By arranging the electrodes 14a and 14b in parallel, variations in the electrostatic force generated between the electrodes are reduced, and a stable displacement of the diaphragm 10 can be obtained. Here, regarding each of the electrodes 14, one of the two electrodes 14 to which different potentials are applied in order to generate electrostatic force between each other is referred to as an electrode 14a, and the other is referred to as an electrode 14b.

In this case, the diaphragm 10 and each electrode 14 are electrically separated by the insulating film 12, and two adjacent electrodes 14a, 14a of each electrode 14 are also electrically separated from each other by a gap. To be done. The vibrating plate 10 and the two electrodes 14a and 14b constitute an electrostatic actuator according to the present invention that deforms the vibrating plate 10 that is a movable portion.

Then, as shown in FIG. 6, each electrode 14a and each electrode 14a are connected from the drive circuit (here, shown as an oscillation circuit) 15 to each electrode 14a.
Driving voltages (voltages having different potentials) that cause a potential difference to each other can be applied to 4b.

The second substrate 2 bonded to the lower surface of the first substrate 1 is a protective substrate for protecting the electrodes 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, as shown in FIG. 6, each electrode 1
If the drive circuit 15 applies a pulse potential of 0V to 40V to 4a and no potential is applied to each electrode 14b,
The surface of the electrode 14a is positively charged, an electrostatic force is generated between the electrode 14a and the adjacent electrode 14b facing each other to which a pulse potential is not applied, and an electrostatic attraction action is exerted.
As shown in FIG. 7, the bending portion 11 of the vibration plate 10 is deformed as shown by the thick line 20 when 14 b approaches, the volume of the discharge chamber 6 increases by ΔV, and the ink is discharged from the common liquid chamber 8 more. It is replenished into the discharge chamber 6 through the fluid resistance portion 7.

When the potential of the electrode 14a returns to 0V from this state, the potential difference between the electrode 14a and the electrode 14b disappears, and the electrostatic force disappears. Therefore, the bent portion 11 of the vibration plate 10 is restored to the original state, and the discharge chamber 6 is discharged. As a result, the pressure in the discharge chamber 6 rises sharply and the ink droplets 22 can be discharged from the nozzle holes 4 toward the recording paper 23 as shown in FIG. .

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

[0031]

[Equation 1]

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

As described above, in the ink jet head including the electrostatic actuator, the bending portion 11 is formed on the diaphragm 10, and the bending portion 11 is provided with at least two electrodes 14 which are electrically separated and independent. By applying a voltage that causes a potential difference between the electrodes 14a and 14b facing each other, the adjacent electrodes 14a and 14b
And an electrostatic attraction force is generated between them and the bent portion 11 of the vibration plate 10 is deformed by a slight displacement of the electrode 14, so that driving efficiency is improved, droplet ejection efficiency is improved, and high image quality recording is possible. .

In this case, the bent portion 11 provided on the diaphragm 10
Since the electrodes 14a and 14b are provided inside, the vibration plate 10
Since the electrostatic force acts between the electrodes 14a and 14b within the plane, the diaphragm 10 (bending portion 11) can be more efficiently deformed. Further, since the electrostatic force acting between the electrodes 14a and 14b is in the direction perpendicular to the vibration plate 10, the excluded volume can be earned without increasing the vibration plate area, and it is possible to arrange the electrodes at a high density.

The vibrating plate 10 and the electrode 14 are made of an insulating film 12.
Since it is electrically separated by means such as the above, even if a voltage is applied to the electrodes as in the conventional case, all the electrodes are at the same potential through the vibrating plate and no malfunction occurs, so that they are applied to the electrode 14. The voltage can be efficiently applied to the electrode 14 without leaking the voltage to the diaphragm 10. in this case,
By forming the insulating film 12 between the diaphragm 10 and the electrode 14 as an example of electrically separating the diaphragm 10 and the electrode 14, insulation can be easily performed and reliability can be improved. If the diaphragm 10 itself is made of an insulating material,
An insulating film may not be separately provided.

Furthermore, by arranging the electrodes 14a and 14b in parallel, there is little variation in the electrostatic force generated between the electrodes, and since the grooves are formed by dry etching, the distance between the electrodes can be reduced, so that a large force is applied. It can be generated and can be driven with a low voltage.

Next, the ink jet head according to the second embodiment will be described with reference to FIG. The figure is an explanatory view of the diaphragm portion of the head as viewed from the bottom. In this embodiment, two grooves (recesses) 10c along the short side direction and a groove (recess) 10 along the long side direction are formed on the diaphragm 10.
The bent portion 11 is formed by providing a and 10b.

That is, the bent portion 11 formed uniformly in the side direction as in the first embodiment has a beam structure and is hard to be deformed in the direction perpendicular to the beam. Since the bent portion 11 is formed in a plurality of directions instead of one direction as described above, the number of portions serving as beams is reduced and the diaphragm 10 (bent portion 11) is easily deformed.

Next, the ink jet head according to the third embodiment will be described with reference to FIGS. 9 and 10 together with its manufacturing process. As shown in FIG. 9A, a silicon substrate 31 for forming the diaphragm 10 having a plane orientation (100) and a thickness of 400 μm is prepared, a resist pattern is formed, and a space is formed between the silicon substrates 31 by dry etching. The recess 10b is formed with a line width of 1 μm and 1 μm.

Next, as shown in FIG. 3B, after the silicon oxide film 32 is formed in the recess 10b of the silicon substrate 31, as shown in FIG. Polysilicon) is formed and patterned by dry etching using a lithography method to form the recesses 10.
The opposing electrodes 14a and 14b are formed in b.

After that, as shown in FIG.
A silicon substrate 35, which is the second substrate 2 in which the concave portion 16 of about μm is formed, is prepared separately and bonded to the silicon substrate 31 so as to protect the electrode portion. Direct joining is used for the joining method,
After prebonding, a strong bondability was obtained by performing heat treatment at 1000 ° C. for 2 hours in a furnace.

Next, as shown in FIG.
CMP the surface of the silicon substrate 31 on which 4a and 14b are formed.
After being thinned to a thickness of 5 μm by a processing method or the like, a resist pattern is formed by aligning the polished surface with an infrared transmissive aligner, and the silicon substrate 31 is etched by dry etching to form the concave portion 10a. The portion 11 is formed and the diaphragm 10 made of the silicon substrate 31 is obtained.

After that, as shown in FIG. 3B, a silicon substrate 36, which is the first substrate 1 in which a portion to be the discharge chamber 6 is formed in advance, is prepared, and a vibration is formed on the silicon substrate 31 by using an adhesive. Bonded on the plate 10. Then, the same figure (c)
As shown in FIG. 3, the nozzle substrate 3 is attached onto the silicon substrate 36 with an adhesive to complete the head.

Since the electrodes 14a and 14b are formed parallel to each other as described above, the electrostatic force generated between the electrodes 14a and 14b has little variation, and the groove (recess 10b) is formed by dry etching. So electrode 14
Since the distance between a and 14b can be reduced, a large force can be generated, and it is possible to drive at a low voltage.

Next, an ink jet head according to the fourth embodiment will be described with reference to FIG. 11 together with its manufacturing process. As shown in FIG.
Similar to (c), the plane orientation (100) has a thickness of 400 μm.
A silicon substrate 31 for forming the vibration plate 10 having a thickness of 10 m is prepared, a resist pattern is formed, and the recesses 10b are formed in the silicon substrate 31 with a line width of 1 μm and 1 μm by dry etching. Membrane 32
After forming a film, polycrystalline silicon (polysilicon) is formed as an electrode material, and is patterned by dry etching using a lithography method to form the electrodes 14a and 14b facing each other in the recess 10b.

After that, as shown in FIG.
A silicon substrate 35, which is the second substrate 2 in which the concave portion 16 of about μm is formed, is prepared separately and bonded to the silicon substrate 31 so as to protect the electrode portion. Direct joining is used for the joining method,
After prebonding, a strong bondability was obtained by performing heat treatment at 1000 ° C. for 2 hours in a furnace.

Next, as shown in FIG.
After the surface of the silicon substrate 31 on which a and 14b are formed is thinned to a thickness of 5 μm by a CMP method or the like, a resist pattern is formed by aligning the polished surface with an infrared transmissive aligner, and the silicon substrate 31 is etched by dry etching. Then, the bent portion 11 is formed by forming the concave portion 10a, and the diaphragm 10 including the silicon substrate 31 is obtained.

In this case, the depth of the recess 10a formed in the silicon substrate 31 is shallower than the depth of the recess 10b previously formed. Here, as described above, the depth of the recess 10a is set to 2 μm while the depth of the recess 10b is set to 4 μm.

Thereafter, as shown in FIG. 10D, a silicon substrate 36, which is the first substrate 1 in which a portion to be the discharge chamber 6 is formed in advance, is prepared as in the case of FIGS. 10B and 10C. Then, after bonding to the vibration plate 10 formed of the silicon substrate 31 with an adhesive, the nozzle substrate 3 is bonded onto the silicon substrate 36 with the adhesive to complete the head.

In the head of this embodiment, as shown in FIG. 12, the thickness of the portion 11a of the bent portion 11 on the side of the discharge chamber 6 is different from that of the portion 11b on the side opposite to the discharge chamber 6, and the side of the discharge chamber 6 is different. The thickness t1 of the portion 11a is thin, and the thickness t2 of the portion 11b opposite to the discharge chamber 6 is thin.

Therefore, the opposing electrodes 14a, 14b
By applying different electric potentials to generate electrostatic force,
As described above, the electrodes 14a and 14b try to displace in the approaching direction. At this time, the thickness t1 of the portion 11a of the bent portion 11 formed on the discharge chamber side is the same as the portion of the bent portion 11 on which the electrode is formed. Since the thickness of the electrode 11b is smaller than the thickness t2 of the electrode 11b, the electrostatic force generated between the electrodes generates a bending moment that tends to displace the diaphragm itself upward, and the electrodes 14a, 1
A large displacement of the diaphragm 10 (bent portion 11) can be obtained with a slight displacement between 4b.

In this case, as shown in FIG. 13, a concave portion 11c is further formed in the portion 11a of the bent portion 11 formed on the discharge chamber side.
By forming and reducing the thickness, it becomes possible to obtain a large displacement of the diaphragm at a lower voltage.

Next, an ink jet head according to the fifth 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 short side direction of the diaphragm.
In this head, a bent portion 51 is formed by forming groove portions (recessed portions) 50a and 50b having a substantially triangular cross section on both sides of the diaphragm 50, and the bent portion 51 is formed in the bent portion 51. Two electrodes 14a and 14b to which different potentials are applied are formed via an insulating film 52.
In this case, the two electrodes 14a and 14b are in a non-parallel state.

With this structure, the opposing electrodes 1
By applying different electric potentials to 4a and 14b to generate electrostatic force, a large electrostatic force is generated in a place where the electrode interval is narrow (on the bottom side of the recess 50b).
b is displaced in the approaching direction, whereby the bent portion 51 of the diaphragm 50 is displaced, and accordingly, the electrodes 14a, 14
Since the distance between b changes gradually and approaches each other, a large displacement of the diaphragm 50 (bent portion 51) can be obtained with a low voltage.

Next, the manufacturing process of the head of this embodiment will be described with reference to FIGS. Figure 15
As shown in (a), the plane orientation (100) has a thickness of 400 μm.
A silicon substrate 61 for forming the diaphragm 50 of m is prepared, a silicon nitride film 71 is deposited on the entire surface, a resist pattern is formed, and the silicon nitride film 71 is etched by dry etching to correspond to the groove 50b. A pattern of the silicon nitride film 71 is formed.

After that, as shown in FIG. 7B, the silicon substrate 6 is formed using the pattern of the silicon nitride film 71 as a mask.
By etching 1 with KOH, a groove 50b having a substantially triangular cross section is formed.

Next, as shown in FIG. 6C, after forming a silicon oxide film 62 in the groove 50b of the silicon substrate 61, polycrystalline silicon (polysilicon) is formed as an electrode material, and the lithography method is used. Patterning is performed by dry etching using the electrode 1 on the inclined wall surface in the groove 50b.
4a and 14b are formed.

After that, as shown in FIG.
A silicon substrate 65, which is the second substrate 2 in which the recess 16 of about μm is formed, is separately prepared and bonded to the silicon substrate 61 so as to protect the electrode portion. Direct joining is used for the joining method,
After prebonding, a strong bondability was obtained by performing heat treatment at 1000 ° C. for 2 hours in a furnace.

Next, as shown in FIG. 16A, the electrode 1
CMP the surface of the silicon substrate 61 on which 4a and 14b are formed.
After reducing the thickness to 3 μm by a processing method or the like, a silicon nitride film 72 is formed on the entire surface, a polished surface is aligned with an infrared transmissive aligner to form a resist pattern, and the silicon nitride film 72 is dry-etched. Form a pattern.

Then, as shown in FIG. 7B, the silicon substrate 61 is patterned using the pattern of the silicon nitride film 72 as a mask.
Is etched with KOH to form a substantially triangular groove 50a, thereby forming a bent portion 51 and obtaining a diaphragm 50 made of a silicon substrate 61.

After that, as shown in FIG. 6C, a silicon substrate 66 which is the first substrate 1 in which a portion to be the discharge chamber 6 is formed in advance is prepared, and vibration is formed on the silicon substrate 61 by using an adhesive. After bonding on the plate 50, the silicon substrate 66
The nozzle substrate 3 is bonded on the upper surface with an adhesive to complete the head.

Next, a head-integrated ink cartridge including a droplet discharge head according to the present invention will be described with reference to FIG. This ink cartridge 100 is one in which the inkjet head 102 of any of the above-described embodiments having a nozzle hole 101 and the like and an ink tank 103 that supplies ink to the inkjet head 102 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. Of the ink cartridge improves the yield and reliability of the ink cartridge,
The cost of the head-integrated ink cartridge can be reduced.

Next, one example of the mechanism of the ink jet recording apparatus equipped with the ink jet head (including the ink cartridge of the head integrated type) according to the present invention is shown in FIG.
This will be described with reference to FIGS. 18 is a perspective explanatory view of the recording apparatus, and FIG. 19 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. 19) by the main guide rod 121 and the sub guide rod 122 which are guide members which are laterally mounted on the left and right side plates (not shown). The carriage 123 is freely held, and yellow (Y), cyan (C),
A head 124, which is an ink jet head that is a droplet ejection head according to the present invention that ejects ink droplets of each color of magenta (M) and black (Bk), is arranged in a direction in which a plurality of ink ejection ports intersects the main scanning direction. , The ink droplet ejection direction is downward. Also, the carriage 123
Each ink cartridge 125 for supplying each color ink to the head 124 is replaceably mounted.

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

Further, although the heads 124 of the respective colors are used as the recording heads in the present embodiment, a single head having nozzles for ejecting ink droplets of the respective colors may be used.

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

On the other hand, in order to convey the paper 113 set in the paper feed cassette 114 to the lower side of the head 124, 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.

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

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

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

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

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

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

The movable portion 205 is formed as a bent portion similarly to the ink jet heads of the first to third embodiments, and electrodes 207a and 207b to which different potentials are applied are formed in the concave portion on the side opposite to the flow path 203. It is provided.

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

The operation principle of this micropump will be described. As described above, the electrodes 207a and 207a and 207b are provided by applying different potentials to the plurality of electrodes 207a and 207b.
Since an electrostatic attraction force is generated between 07b, the movable portion 205, which is a bent portion, is deformed to the side opposite to the flow path 203, and the rear electrode 20 is deformed.
It returns to the original state by stopping the voltage application to 7a and 207b. Here, by sequentially driving the movable part 205 from the right side in the drawing, the fluid in the flow path 203 flows in the direction of the arrow, and the fluid can be transported.

In this case, the electrostatic actuator composed of the movable portion 205, which is the bent portion, and the electrodes 207a and 207b enables stable and efficient driving as in the case of the above-described droplet discharge head. Therefore, the fluid can be stably and efficiently transferred. Note that the electrostatic actuator may have the same configuration as the inkjet heads of the fourth and subsequent embodiments.

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 movable plate 304 provided with a deformable mirror 301 and a protective substrate 302 are overlapped and bonded to each other, and a portion of the movable plate 304 which is not bonded and fixed to the protective substrate 302 is a movable portion 305 which is a bent portion. Has become.

The movable portion 305 is formed as a bent portion similarly to the ink jet head of the fourth embodiment, and electrodes 307a and 307b to which different potentials are applied are provided in the concave portion on the side opposite to the mirror 301.

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

The principle of this optical device will be described. By applying different potentials to the electrodes 307a and 307b provided on the movable portion 305 which is the bent portion having the mirror 301, electrostatic attraction force is generated between the electrodes 307a and 307b. Occurs, the movable portion 305 is deformed into a convex shape and becomes a convex mirror. Therefore, the light from the light source 310 is reflected by the lens 311.
When the mirror 301 is irradiated via the light, the light is reflected at the same angle as the incident angle when the mirror 301 is not driven, but when the movable portion 305 is driven by the mirror 301, the movable portion 305 becomes a convex mirror. The reflected light becomes divergent light. Thereby, an optical modulation device can be realized.

In this case, the movable portion 305 and the electrode 307
The electrostatic actuator composed of a and 307b enables stable and efficient driving as in the case of the droplet discharge head described above, and can constitute an optical modulation device that can obtain stable operation characteristics. . When the mirror 301 is transformed into a concave mirror, it has the same configuration as the inkjet heads of the first to third embodiments, and when it is transformed into a concave mirror, the inkjet heads of the fourth and subsequent embodiments are used. It has the same configuration.

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. 21, 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 307a and 307a serves as a convex mirror, so that light diverges and hardly enters the projection lens 312. The light incident on the projection lens 312 is projected on a screen (not shown) or the like, and an image can be displayed on the screen.

In the above-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, as the microdevice using the electrostatic actuator, in addition to a micropump and an optical device (light modulation device), a microswitch (microrelay),
It can also be applied to actuators (optical switches) of multi-optical lenses, micro flowmeters, pressure sensors, and the like.

[0090]

As described above, according to the electrostatic actuator of the present invention, the movable portion has the bending portion, and the bending portion is electrically insulated and separated from each other so that an electrostatic attractive force is exerted between them. Since at least two electrodes for generating are provided, an actuator with high driving efficiency can be obtained at low cost.

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

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

[Brief description of drawings]

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

FIG. 2 is 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 enlarged explanatory view of a main part of FIG.

FIG. 5 is an explanatory view of one diaphragm of the same head as seen from the electrode side.

FIG. 6 is an explanatory plan view for explaining an electrode arrangement pattern of the head.

FIG. 7 is an enlarged cross-sectional explanatory view of an essential part for explaining the operation of the head.

FIG. 8 is an explanatory view of one diaphragm of the inkjet head according to the second embodiment as viewed from the electrode side.

FIG. 9 is a sectional explanatory view for explaining the inkjet head according to the third embodiment together with the manufacturing process thereof.

FIG. 10 is a sectional explanatory view explaining a step following FIG. 9;

FIG. 11 is a sectional explanatory view for explaining the inkjet head according to the fourth embodiment together with the manufacturing process thereof.

FIG. 12 is an explanatory diagram for explaining the configuration and operation of the head of the same embodiment.

FIG. 13 is an explanatory diagram for explaining the configuration of the inkjet head according to the fifth embodiment.

FIG. 14 is an explanatory diagram for explaining an inkjet head according to the sixth embodiment.

FIG. 15 is a cross-sectional explanatory diagram illustrating a manufacturing process of the inkjet head according to the embodiment.

16 is a cross-sectional explanatory diagram illustrating a step following the step of FIG.

FIG. 17 is an explanatory perspective view for explaining an ink cartridge integrated head including a droplet discharge head according to the present invention.

FIG. 18 is a perspective explanatory diagram illustrating an example of an inkjet recording apparatus according to the present invention.

FIG. 19 is an explanatory diagram of a mechanical section of the recording apparatus.

FIG. 20 is a cross-sectional explanatory diagram illustrating an example of a micropump including an electrostatic actuator according to the present invention.

FIG. 21 is a sectional explanatory view illustrating an example of an optical device including an electrostatic actuator according to the present invention.

FIG. 22 is a perspective explanatory view illustrating an example of a light modulation device using the optical device.

[Explanation of symbols]

1 ... 1st substrate, 2 ... 2nd substrate, 3 ... Nozzle plate, 4 ... Nozzle hole, 6 ... Discharge chamber, 7 ... Fluid resistance part, 8 ... Common liquid chamber, 1
0 ... Vibration plate, 10a, 10b ... Recessed portion, 11 ... Bent portion, 1
2 ... Insulating film, 14, 14a, 14b ... Electrode, 100 ... Ink cartridge, 114 ... Recording head, 201 ... Flow path substrate, 203 ... Flow path, 205 ... Movable part, 207a, 2
07b ... electrode, 301 ... mirror, 305 ... movable part, 3
07a, 307b ... Electrodes.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Shimizu             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2C057 AF52 AG54 AN01 AP25 AP32                       AP33 AQ02 BA04 BA15                 3H077 AA06 CC02 DD01 FF07

Claims (9)

[Claims] 1. An electrostatic actuator for deforming a movable portion, wherein the movable portion has a bending portion, and the bending portion is electrically insulated and separated from each other, and at least for generating an electrostatic attractive force therebetween. An electrostatic actuator comprising two electrodes. 2. The electrostatic actuator according to claim 1, wherein at least two electrodes for generating electrostatic attraction between each other are arranged substantially parallel to each other. 3. The electrostatic actuator according to claim 1, wherein at least two electrodes for generating electrostatic attraction between them are arranged non-parallel to each other. 4. The electrostatic actuator according to claim 1, wherein the bent portion is at least 2.
An electrostatic actuator characterized in that it is formed by grooves arranged in three different directions. 5. The electrostatic actuator according to claim 1, wherein the bent portion of the movable portion is thinner than the other portions. 6. The electrostatic actuator according to claim 1, wherein the bent portion of the movable portion has a thin portion and a thick portion. 7. A droplet which discharges the droplet by having a vibrating plate which is a movable part forming at least one wall surface of an ejection chamber communicating with a nozzle which ejects the droplet. A droplet discharge head comprising the electrostatic actuator according to any one of claims 1 to 7 for deforming the vibrating plate. 8. The droplet discharge head according to claim 7, wherein an ink cartridge for supplying ink is integrally provided. 9. An ink jet recording apparatus equipped with an ink jet head for ejecting ink droplets, wherein the ink jet head is the liquid droplet ejecting head according to claim 7 or 8.