JP2003334945A - Liquid drop ejection head, ink cartridge, inkjet recorder, and micro pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low cost and space-saved liquid drop ejection head and an inkjet recorder. <P>SOLUTION: This liquid drop ejection head 0 comprises one or more nozzle holes 31, pressurizing liquid chambers 11 each communicating with each of nozzle holes, a common liquid chamber 12 communicating with the pressurizing liquid chambers 11, and a diaphragm 13 forming at least one wall of the pressurizing liquid chamber 11. The head 0 ejects a liquid drop by applying energy to a liquid in the pressurizing liquid chamber 11 by deforming the diaphragm 13. A deformable plate 14 of which the deforming amount is greater than that of the diaphragm is provided to one wall of the common liquid chamber 12, and an air pressure correction chamber 23 is provided opposite to the deformable plate 14. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet discharge head, an ink cartridge, an inkjet recording apparatus, and a micropump that discharge droplets of, for example, ink liquid by a pressure wave caused by electrostatic force.

[0002]

2. Description of the Related Art Among ink jet recording apparatuses that perform recording by ejecting ink droplets directly from a nozzle onto a recording medium, an on-demand method of ejecting ink only when necessary is a mechanism for collecting ink. Since it is not necessary, it is possible to reduce the price and size, and it has the feature of being compatible with colorization. The inkjet recording device
It is used as an image recording apparatus or an image forming apparatus such as a printer, a facsimile, a copying machine, and a plotter.
An inkjet head, which is a droplet ejection head in an inkjet recording apparatus, includes a nozzle that ejects an ink droplet and a pressurized liquid chamber (ejection chamber, pressure chamber,
(Also referred to as liquid chamber, ink flow path, etc.) and pressure generating means for pressurizing the ink in the pressurized liquid chamber, and pressurizing the ink in the pressurized liquid chamber with the pressure generated by the pressure generating means. In this way, ink droplets are ejected from the nozzle. As such an inkjet head, a piezo type and a bubble type are popular, but an electrostatic type inkjet head using an electrostatic force as a pressure generating means is also known. The piezo type inkjet head is an electromechanical conversion system in which a pressure wave is generated in an ink chamber by piezoelectric displacement of a piezo element and ink is ejected from an ink nozzle. The bubble type is an electrothermal conversion method in which bubbles are generated in an ink chamber by a heater that is heated to a high temperature in a short time, and ink is ejected due to volume expansion of the bubbles. In addition, the electrostatic ink jet head includes a pressurized liquid chamber that communicates with the ink nozzle holes, and a vibration plate that forms a part of the wall of the pressurized liquid chamber.
An arrangement is provided in which a large number of actuators each including an electrode arranged to face the diaphragm via a minute gap are arranged in parallel,
By applying a voltage to the electrodes to deform the vibrating plate and generate pressure in the pressurized liquid chamber, the ink liquid in the pressurized liquid chamber is discharged as droplets from the ink nozzle holes. In other words, the electrostatic ink jet head deforms the vibration plate of each actuator by using electrostatic attraction, and the mechanical force at the time of deformation or the electrostatic attraction is generated on the diaphragm. Ink in the pressurized liquid chamber is ejected from the nozzle by mechanical repulsion. In recent years, due to environmental issues, lead-free bubble type and electrostatic type have attracted attention,
In addition to lead-free, various electrostatic inkjet heads have been proposed that have a low environmental impact from the viewpoint of low power consumption. In addition, since this electrostatic ink jet head can be manufactured by a wafer process, it is easy to increase the density, and it is possible to manufacture a large number of elements with stable characteristics. Therefore, it is easy to downsize (Japanese Patent Laid-Open No. 2-2893).
No. 51, No. 5-050601, No. 6-071882).

Next, FIGS. 9 and 10 are an exploded perspective view showing a structural example of a conventional electrostatic type droplet discharge head, and a vertical sectional view of an actuator portion in an assembled state. The electrostatic droplet discharge head 100 according to the conventional example is an inkjet head used in, for example, an inkjet recording device,
The droplet discharge head 100 includes a channel substrate 101 which is a first substrate, an electrode substrate 102 which is a second substrate bonded to the lower side of the channel substrate 101, and a third substrate which is bonded to the upper side of the channel substrate 101. The nozzle plate 103, which is a substrate, and the nozzle plate 103 are laminated and bonded to each other. Further, the droplet discharge head 100 includes a plurality of nozzle holes 131 formed at appropriate positions of the nozzle plate 103, a pressurized liquid chamber 111 that is an ink flow path communicating with each nozzle hole 131, and a pressurized liquid chamber 111. The vibrating plate 113 forming part of the wall surface, the common liquid chamber 112 communicating with the pressurized liquid chamber 111 via the fluid resistance portion 132, which is a recess formed in the lower surface of the nozzle plate 103, and the vibrating plate 113.
Air gap (vibration chamber) 121 for bending the electrostatic force
An individual electrode 122 that is arranged to face the lower position via
Is equipped with. Depending on the voltage applied to the electrode 122,
A potential difference is applied between the electrode 122 and the vibrating plate 113, so that the vibrating plate 113 bends (vibrates). The nozzle hole 13 is generated by the pressure wave generated when the vibrating plate 113 bends to the vibrating chamber 121 side and then returns to the pressurized liquid chamber 111 side.
1 is configured to eject ink. A plurality of elongated pressure liquid chambers 111 are arranged in parallel with each other through a partition wall 111a. The nozzle plate 103 corresponding to each pressure liquid chamber 111 has one nozzle hole 131.
Penetration is formed at each place. When the nozzle plate 103 is bonded onto the flow path substrate 101, each pressurized liquid chamber 111 is defined by a partition wall 111a. The electrodes 122 provided on the electrode substrate 102 side are provided in the pressurized liquid chambers 11 on the flow path substrate 101 side.
It is formed at the bottom of the vibration chamber 121 formed so as to correspond to 1. Each vibration chamber 121 is partitioned by a partition wall 121a. The common liquid chamber 112 includes all the pressurized liquid chambers 111.
Common to the ink tank (not shown) through an ink supply port (droplet supply port) (not shown) that is arranged so as to extend across the end of Ink is supplied to the liquid chamber 112, and further, ink is supplied to each pressurized liquid chamber 111 via each fluid resistance portion 132.

Meanwhile, in the market, as in the case of other electronic devices, there is a strong demand for energy saving for OA devices and the like including ink jet printers. The electrostatic type droplet discharge head is characterized in that it consumes less power than other methods, but if further reduction in power consumption is promoted, it is necessary to further reduce the drive voltage. As a method of responding to such a request, it is considered that the width in the height direction of the vibration chamber 121 (distance between the electrode 122 and the vibration plate 113) is narrowed and the thickness of the vibration plate 113 is thinned. However, although the drive voltage can be lowered by adopting this configuration, the width of the vibrating chamber 121 in the height direction is narrow, and the rigidity of the vibrating plate is low. The vibrating plate is in contact with the electrode and is adsorbed by the force or the hydrogen bonding force, and it does not function as an actuator. Therefore, the vibrating chamber 121 must be configured so that liquid cannot enter from the outside air. For this reason, it is desirable that the vibration chamber 121 is completely shielded from the outside, but at least a structure that prevents liquid such as water from entering the vibration chamber may be used. However, the vibration chamber 12
Another problem arises in the case of adopting a configuration in which the gas outside the head cannot enter and leave the other space (hereinafter, referred to as an actuator chamber) communicating with 1 and the vibration chamber 121. That is,
Since the gas in the actuator chamber and the gas in the outside world cannot freely flow in and out, when the atmospheric pressure and temperature in the outside world change, there is a difference in atmospheric pressure between the actuator room and the outside world, and the equilibrium position of the diaphragm changes depending on the magnitude of this pressure difference. To do. For example, if the internal pressure in the actuator chamber is lower than the external pressure, the equilibrium position of the diaphragm approaches the electrode side, and if the internal pressure in the actuator chamber is higher than the external pressure, the balanced position of the diaphragm moves away from the electrode. As a result, the ejection amount and speed of the droplets ejected from the head change due to the atmospheric pressure difference between the actuator chamber and the outside world, and the droplet ejection head cannot maintain stable ejection characteristics. Therefore, it is necessary to provide correction means for atmospheric pressure and temperature by some means.

[0005] As an example of conventional measures against the above problems,
The following configurations are included. That is, JP-A-11-2861
No. 09 (hereinafter, referred to as Prior Art 1) discloses an "inkjet head drive control method and apparatus" which uses a pressure sensor as an atmospheric pressure detecting means or manually reads and reads the value of the external atmospheric pressure. That is, the drive voltage waveform is changed according to the embedded value. In addition, Japanese Unexamined Patent Application Publication No. 2001-300421 (hereinafter, referred to as Prior Art 2,
The "electrostatic actuator and the liquid ejecting apparatus using the same" disclosed in (1) are provided with a thin plate, which is called a displacement plate, that communicates with the atmosphere on a substrate that forms a vibrating plate, which is called a cavity plate. The pressure compensation chamber on the side opposite to the atmosphere is communicated with the vibration chamber, and the pressure of the vibration chamber is compensated by the deflection of the displacement plate. However, in the related art 1, the atmospheric pressure detection means, the storage means for storing the atmospheric pressure-driving voltage waveform for compensation, the control means, and the like are required, and the cost increase of the product cannot be avoided. was there. Further, in the prior art 2, in order to support the multi-driving of the head, the space of the displacement plate must be wide, which leads to an increase in the size of the head itself, which in turn leads to an increase in the size of the printer, thus saving space. There was a problem that it was not desirable from the viewpoint of aiming.

[0006]

As described above, the width of the vibrating chamber located between the electrode and the vibrating plate forming a part of the wall of the pressurized liquid chamber of the electrostatic ink jet head is several microns. If the vibration chamber is open to the atmospheric environment, dust may enter the vibration chamber and the dust in the vibration chamber may hinder the deformation of the diaphragm. Further, when water is adsorbed on the surface of the diaphragm, the diaphragm may be adsorbed on the electrodes by the liquid bridging force, which may cause ejection failure. Furthermore, when the diaphragm is continuously driven, the gas in the vibrating chamber gradually escapes to a depressurized state, and even when no voltage is applied, the diaphragm bends toward the electrode side and does not recover, and a sufficient amount of ink is ejected. / Pressure may not be obtained. Therefore, the atmosphere opening portion that is normally connected to the vibration chamber is sealed with resin or the like so that the vibration chamber portion is in a sealed state. However, if the vibration chamber interposed between the diaphragm and the electrode is sealed,
In an environment where the atmospheric pressure is significantly different from normal, such as in highlands where the atmospheric pressure is lower than normal, the diaphragm is constantly bent toward the pressurized liquid chamber due to the pressure difference between the pressure inside the vibration chamber and the low external pressure. Therefore, defective ejection occurs. When the external pressure is high, the diaphragm is bent in the opposite direction.
Then, JP-A-11-286109 and JP-A-2000-2
In the 72120 publication, the pressure difference between the inside of the vibration chamber is measured by the atmospheric pressure detection means, the voltage drive waveform is corrected, and a large-area vibration plate for separately adjusting the pressure is provided to change the volume of the sealed portion. The pressure difference from the outside air pressure is adjusted. However, when the atmospheric pressure detecting means and the large area pressure adjusting means are added, the head cost becomes high, and it becomes difficult to miniaturize and integrate the chip. The present invention has been made in view of the above, does not require addition of special components such as pressure detection means, and by providing a compact pressure adjusting means on the head chip, a low cost and wide range of environmental pressure In addition to producing a droplet discharge head that can handle
An object of the present invention is to provide a droplet discharge head, an ink cartridge, an inkjet recording device, and a micropump using the same.

[0007]

In order to solve the above-mentioned problems, the invention of claim 1 is a droplet discharge head which discharges droplets by a pressure wave due to electrostatic force, and at least one of which discharges droplets. A nozzle hole, a pressurized liquid chamber that communicates with the nozzle hole and contains the liquid to be discharged, a common liquid chamber that communicates with the pressurized liquid chamber, and a vibration that constitutes a part of the wall surface of the pressurized liquid chamber. A plate, a gap that is in contact with the vibration plate and is provided on the opposite side of the pressurized liquid chamber, and an electrode that is arranged to face the vibration plate through this gap, and the static electricity generated by the voltage applied to the electrode is provided. In a droplet discharge head that bends the diaphragm with electric power to increase the internal pressure in the pressurized liquid chamber and discharges droplets from the nozzle hole, the amount of deformation of the diaphragm on a part of the wall surface of the common liquid chamber A large deformable plate is installed and the deformable plate is sandwiched. The opposite side of the common liquid chamber, characterized in that a pressure correction chamber communicating with said gap. According to this, a part of the existing components (common liquid) can be simply introduced without adding complicated components such as pressure detecting means to the structure, increasing manufacturing man-hours, increasing complexity, and increasing cost. It is possible to construct a pressure correcting means by a simple change of simply deforming a part of the chamber) and to provide a droplet discharge head that can cope with a wide range of environmental atmospheric pressure at low cost. According to a second aspect of the present invention, in the droplet discharge head according to the first aspect, the thickness of the deformable plate is thinner than the thickness of the vibrating plate. The deformable plate is
By making the wall thickness thinner than the diaphragm, it is possible to function as an atmospheric pressure correction means. The invention of claim 3 is
The droplet discharge head according to claim 1, wherein the in-plane length of the deformable plate is larger than the in-plane length of the vibrating plate. Deformable by restraining the displacement of the deformable plate, that is, in the case of a rectangular deformable plate, the length of the short side is longer than the length of the short side of the rectangular diaphragm. The plate can be deformed more easily than the diaphragm having the same thickness, and can function as the atmospheric pressure correction means.

According to a fourth aspect of the present invention, in the droplet discharge head according to the first aspect, the volume of all voids communicating with the atmospheric pressure correction chamber is set to V ₀ , and a uniform pressure of 53 hPa is applied to the deformable plate. When added, the change amount of the volume V ₀ due to the displacement of the deformable plate is configured to be 0.15 × V ₀ or more. What environmental conditions (temperature, pressure) should be satisfied by the displaceable plate?
Even if there is a change in the volume, the volume change of the vibration chamber (void) related to the displacement of the deformable plate is sufficiently larger than the volume change of the vibration chamber (void) related to the displacement of the diaphragm. This is very important. As long as these conditions are satisfied, the equilibrium position of the vibration plate hardly changes even if a pressure difference occurs inside and outside the vibration chamber, and the pressure correction function is selected by selecting each material of the actuator and the deformable plate and the configuration parameters. It becomes easy to construct a droplet discharge head provided with. An ink cartridge according to a fifth aspect of the present invention is an ink cartridge in which a liquid droplet ejection head that ejects ink droplets and an ink tank that supplies ink to the liquid droplet ejection head are integrated. Item 1. The droplet discharge head according to any one of items 1 to 4. According to this, manufacturing defects can be reduced and cost can be reduced. An inkjet recording apparatus according to a sixth aspect of the present invention is an inkjet recording apparatus equipped with an inkjet head that ejects ink droplets, wherein the inkjet head is the droplet ejection head according to any one of claims 1 to 4. It is characterized by According to this, since the inkjet head which is any one of the droplet discharge heads according to the present invention is mounted, the reliability is high and the image quality can be improved. The micropump according to the invention of claim 7 is a micropump for transporting a liquid by deformation of a vibrating plate, wherein the micropump is claim 1.
The droplet discharge head according to any one of items 1 to 3 above. According to this, since the vibrating plate is deformed by the electrostatic force acting between the electrodes, it is possible to realize a small-sized micropump with low power consumption.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, the pressure generation mode of the electrostatic type liquid chamber ejection head is such that the individual electrode and the diaphragm are opposed to each other with a gap (air gap) in between, and the diaphragm is used as a common electrode, and between the individual electrode and the diaphragm. The configuration will be described using a configuration in which a potential difference is applied to the diaphragm and the diaphragm flexes. Further, in more detailed description using mathematical expressions, a deformable plate having a larger deformation amount than the diaphragm is considered as a rectangular thin plate.
Other shapes have the same essence as long as the amount of deformation is large. FIG. 1 is an exploded perspective view of a droplet discharge head according to an embodiment of the present invention, and FIG. 2 is a vertical sectional view showing an actuator portion in an assembled state. The electrostatic droplet discharge head 0 according to this embodiment is, for example, an inkjet head used in an inkjet recording apparatus. The droplet discharge head 0 includes a flow path substrate 1 that is a first substrate and a flow path. The electrode substrate 2 which is the second substrate bonded to the lower side of the substrate 1 and the nozzle plate 3 which is the third substrate bonded to the upper side of the flow channel substrate 1.
And is laminated and joined. Reference numeral 5 is a sealing material. Furthermore, this droplet discharge head 0
A plurality of nozzle holes 3 formed through the nozzle plate 3 at appropriate positions.
1. Pressurized liquid chamber 11 that is an ink flow path through which each nozzle hole 31 communicates, diaphragm 13 that forms part of the wall surface of pressurized liquid chamber 11, and recess formed in the lower surface of nozzle plate 3. Common liquid chamber 1 communicating with the pressurized liquid chamber 11 via the fluid resistance portion 32 that is
2. The individual electrodes 22 are provided so as to face each other at a lower position with a gap (vibration chamber) 21 for bending the diaphragm 13 by an electrostatic force. Due to the voltage applied to the electrode 22, a potential difference is applied between the electrode 22 and the diaphragm 13, and the diaphragm 13 is bent (vibrated). After the vibrating plate 13 bends toward the vibrating chamber 21, the pressurized liquid chamber 1
Ink is ejected from the nozzle hole 31 by the pressure wave generated when returning to the 1st side. A plurality of elongated pressure liquid chambers 11 are arranged in parallel with each other through a partition wall 11a, and one nozzle hole 31 is provided in each nozzle plate 3 corresponding to each pressure liquid chamber 11. It is formed through. When the nozzle plate 3 is bonded onto the flow path substrate 1, each pressurized liquid chamber 11 is partitioned by the partition wall 11a.

The electrode 22 provided on the electrode substrate 2 side is formed at the bottom of the vibration chamber 21 formed so as to correspond to each pressurized liquid chamber 11 on the flow path substrate 1 side. Each vibration chamber 21 has a partition wall 2
It is separated by 1a. The common liquid chamber 12 is arranged so as to extend across the end portions of all the pressurized liquid chambers 11, and is provided below the common liquid chamber 12 and in an ink supply port (a liquid Ink is supplied from an ink tank (not shown) to the common liquid chamber 12 via a droplet supply port), and further, ink is supplied to each pressurized liquid chamber 11 via each fluid resistance portion 32. The configuration of the common liquid chamber 12 can take various arrangement configurations depending on the configuration of the head, but in the present embodiment, one surface (lower surface) of the wall surfaces forming the common liquid chamber 12 is deformed more than the diaphragm 13. The configuration is characterized by a deformable plate (atmospheric pressure correction means) 14 that is easy to perform. That is, the deformable plate 14 arranged substantially on the same plane as the vibrating plate 13 is connected to the vibrating plate 13 via the partition wall 11b, but the deformable amount (deflection amount) of the deformable plate 14 is the vibrating plate 13. Is set to be larger than the deformation amount of. That is, in the equation (1) relating to the displacement amount (deflection amount) δ of the deformable plate 14, when the atmospheric pressure P has the same value, the deformable plate 14 has a value of δ that of the diaphragm 13. Is also set to be large. It is clear that when the values of the material and the constituent parameters other than the plate thickness t are constant, the amount of displacement of the deformable plate 14 can be changed by changing the plate thickness t. Further, the atmospheric pressure correction chamber (atmospheric pressure correction means) 23, which is a space on the opposite side of the common liquid chamber 12 with the deformable plate (atmospheric pressure correction means) 14 in between, communicates with the vibration chamber 21.
Further, the head internal space (= actuator chamber) including the atmospheric pressure correction chamber 23 and the vibration chamber 21 has a configuration completely shielded from the atmosphere. In this configuration, since the deformable plate 14 having a lower rigidity than the vibrating plate 13 communicates with the vibrating chamber 21, when a pressure difference occurs between the vibrating chamber 21 and the outside world,
The displacement of the vibrating plate 13 can be suppressed by not changing the equilibrium position of the vibrating plate 13 but rapidly changing the equilibrium position of the deformable plate 14.

If the configuration of the present invention is adopted as the shape of the ejection head, the equilibrium position of the vibrating plate 13 will not change significantly due to the difference in the internal pressure of the vibrating chamber 21 and the atmospheric pressure, so that it is inevitable. It is not necessary to change the driving voltage value to perform atmospheric pressure correction, the ejection amount and speed of droplets ejected from the head do not change due to the atmospheric pressure difference, and the droplet ejection head can maintain stable ejection characteristics. it can. Further, in this configuration, since the atmospheric pressure correction means is provided side by side with the common liquid chamber 12 that is indispensable for the head configuration, the increase in the head size can be suppressed to the minimum while the peculiarity to the electrostatic droplet discharge head is achieved. It is possible to perform atmospheric pressure correction, which is a problem.
In addition, in the illustrated embodiment, the vibration chamber 21 constituting each actuator is partitioned by the partition wall 21a, while the atmospheric pressure correction chambers 23 are common, so that the vibration chamber 21 is formed.
The rooms are in communication. However, this is only an example, and each vibration chamber 21 and atmospheric pressure correction chamber 23 may have a structure in which each actuator is independent (not in communication). In any case, the structure of the present invention can be similarly applied and the same effect can be obtained. However, when each vibration chamber 21 is independent, it is necessary to provide the structure of the present invention for each actuator. Also, the atmospheric pressure correction chamber 23 may be independent for each actuator. In practice, the pressurized liquid chamber 1 is designed so that the liquid droplet does not drip from the nozzle hole 31.
1, the pressures in the flow path 15 and the common liquid chamber 12 are set to be negative pressures. This negative pressure is applied to the vibrating plate 13 and the deformable plate 1.
Since it is applied to both No. 4 and No. 4, the above description is valid without being affected by the existence of this negative pressure.
The influence of atmospheric pressure is applied to the vibrating plate 13 and the deformable plate 14 through the liquid in the head. In order to make the amount of deformation of the deformable plate 14 larger than that of the vibrating plate 13, as can be seen from the equation (1), the thickness t of the deformable plate 14 is made thinner than the thickness of the vibrating plate 13, or Alternatively, the in-plane length that constrains the displacement of the deformable plate 14 (the short side length of the rectangular deformable plate) needs to be longer than the in-plane length that constrains the displacement of the diaphragm 13. Here, by adopting a configuration of increasing the in-plane length, a process of simultaneously forming the deformable plate 14 when forming the vibrating plate 13 can be applied, and an increase in manufacturing process and an accompanying increase in cost can be prevented. .

Next, when the initial equilibrium state of the volume (volume) of the actuator chamber including all the vibration chambers 21 communicating with the atmospheric pressure correction chamber 23 is represented by the state equation P ₀ V ₀ = nRT ₀ , When the temperature T ₀ and the atmospheric pressure P _{0 in} the state change to T and P, respectively, the state is PV = nR
Represented by T. Then, the volume difference ΔV before and after the state transition is given by the equation (2). On the other hand, the displacement amount δ of the central portion in the short side direction of the rectangular deformable plate 14 extending long in the direction intersecting with each diaphragm 13 is such that the displacement amount δ is the short side length a of the diaphragm 13 which is a rectangular thin plate. When it is sufficiently small, the pressure P is uniformly applied to the deformable plate 14, and is given by an equation. At this time, the volume change amount before and after the displacement can be expressed by the equation (3), assuming that the long side length b of the diaphragm 13 is sufficiently longer than the short side length a. Hereinafter, each material and constituent parameter of the diaphragm 13 will be represented by (δ,
ν, E, a, t), and each material / construction parameter of the deformable plate 14 is represented by (δ ′, ν ′, E ′, a ′, t ′). The feature of the present invention is that the equilibrium position of the vibrating plate 13 is maintained even if a pressure difference is generated between the inside and the outside of the vibration chamber 21 by providing the deformable plate 14 as the pressure correction means in a part of the ejection head as described above. It is configured so that it hardly changes and, as a result, the vibration characteristics hardly change. As an example, in normal use of the droplet discharge head, the atmospheric pressure fluctuates to 960 hPa with a standard value of 1013 hPa, and the temperature is 0 to 5 with a standard value of 25 ° C.
If it is assumed that the deformable plate 14 changes to 0 ° C., the condition that the deformable plate 14 should satisfy is that when a uniform load of 53 hPa is applied to the deformable plate 14, the actuator chamber due to the displacement of the deformable plate 14 (the pressure compensation chamber 23 All vibration chambers 2 communicating
The capacity change of the actuator chamber including 1) is 0.15 × V ₀ or more according to the equation (2). On the other hand, the deformable plate 14
Since the sum of the volume change amount of the vibration chamber 21 due to each displacement of the vibration plate 13 and the volume change amount of the vibration chamber 21 derived from the equation of state are equal, the condition of the following expression (4) is derived.
However, Pout is the atmospheric pressure of the outside world, and Pin is the atmospheric pressure in the vibration chamber 21. T ₀ is the temperature at the initial equilibrium state, and T is the temperature after the change. Therefore, the other condition that the deformable plate 14 must satisfy is expressed by the formula (4) under any environment (temperature, atmospheric pressure) conditions.
The value of the first term on the left side (the change in the volume of the vibration chamber related to the displacement of the deformable plate 14) is sufficiently larger than the value of the second term on the left side (the change in the volume of the vibration chamber related to the displacement of diaphragm 13). Is to grow. This is a condition under which the equilibrium position of the vibrating plate 13 hardly changes even if a pressure difference occurs inside and outside the vibrating chamber 21, and it is easy to implement by selecting each material of the actuator and the deformable plate 14 and the constituent parameters. .

Next, an embodiment according to the present invention will be described. [Example 1] [Evaluation method] The evaluation method is as follows. That is, in addition to the ejection head including the actuator in which the deformable plate 14 of the present invention is formed, the ejection head of the above-described embodiment is used as a comparative ejection head except that the deformable plate 14 is not formed. An ejection head having an actuator having exactly the same structure was manufactured. The ejection head of the present invention and the comparative ejection head were heated on a hot plate in an environmental test chamber at a set temperature of 10 ° C. At that time, the air gap length (the length of the vibration chamber 21) of both ejection heads with respect to the temperature was measured. As the measuring method, the diaphragm 13 was brought into contact with the electrode 22 by driving the actuator, and the displacement amount at this time was measured by a laser Doppler vibrometer. That is, this read value becomes the air gap length between the electrode 22 and the diaphragm 13. In addition, in order to read the displacement amount with the vibrometer, in the state where there is no liquid in the pressurized liquid chamber 11 and the common liquid chamber 12,
Moreover, the measurement was performed without joining the nozzle plates. However, the following results do not change significantly due to the absence of liquid. [Discharge head] The outline of the structure and manufacturing method of the discharge head is as follows.
It is as follows. Regarding the electrode substrate 2, a plurality of dugouts to be the vibration chamber 21 are formed in parallel on one surface of the Si substrate, an oxide film is formed in each dugout, and then T is formed on the oxide film.
The individual electrode 22 was formed by film-forming iN. Next, regarding the vibration substrate 1, the vibration plate 13, the common liquid chamber 12, and the deformable plate 1 accompanying the vibration plate 13 are formed by etching one surface of another Si substrate.
4 etc. were formed. At this time, the diaphragm 13 and the deformable plate 1
4 was formed in exactly the same process. afterwards,
The electrode substrate 2 and the vibration substrate 1 were joined by direct joining.
The number of actuators formed on each ejection head is 1.
It is the row 192. All the vibration chambers 21 communicate with one atmospheric pressure correction chamber 23. [Specifications of Vibration Plate 13] The specifications of the rectangular vibration plate 13 are as follows. Thickness t = 2 μm, short side length a = 125 μm, long side length b = 1
000 μm [Specification of the deformable plate 14 provided in the common liquid chamber 12] The specifications of the deformable plate 14 are as follows. Thickness t = 2 μm, short side length a = 2000 μm, long side length b =
30 mm [Shape of electrode 22] The electrode 22 facing the diaphragm 13 is
It was formed so as to be parallel to the diaphragm 13. Also,
The air gap length (the length of the vibration chamber 21) between the electrode 22 and the vibration plate 13 was designed to be 0.2 μm according to the specifications.

[Results] FIGS. 3 and 4 show the results of changes in the air gap length due to temperature changes in the ejection head of the present invention and the comparative ejection head, respectively. The air gap length (equal to the amount of displacement at the time of contact) is the vertical axis, and the temperature is the horizontal axis. FIG. 4 shows the relationship between the Gap length and the temperature in the actuator of the comparative ejection head, and it can be seen that the air in the actuator chamber expands and contracts with respect to the temperature, and the air Gap length obviously changes. Even if such an actuator is installed in a printer, it is difficult to eject ink stably against environmental changes without the combined use of compensating means such as temperature / atmospheric pressure detecting means and drive voltage correcting means. On the other hand, FIG. 3 shows the relationship between the Gap length and the temperature of the actuator according to the embodiment of the present invention, and no obvious change in the air Gap length is recognized with respect to the temperature change.
This is because the deformable plate 14, which has a lower rigidity, displaces in response to the expansion / contraction of the air in the actuator due to the temperature change sufficiently more sensitively than the vibration plate 13, so that the influence of the expansion / contraction of the air is affected. This is because it does not lead to displacement of the diaphragm 13. In this embodiment, the vibrating plate 13 and the deformable plate 11 are used.
However, in order to make the amount of deformation of the deformable plate 14 larger than that of the diaphragm 13, the diaphragm 1
It is also possible to use a different material for 3 or the deformable plate 14 and use a material having a lower Young's modulus than the vibrating plate 13 for the deformable plate 14.

Example 2 Next, an ink cartridge using the droplet discharge head (inkjet head) according to the above embodiment will be described with reference to FIG. This ink cartridge is one in which the inkjet head 51 of any of the above-described embodiments having a nozzle 50 and the like and an ink tank 52 that supplies ink to the inkjet head 51 are integrated. By integrating the high-performance head and the cartridge as described above, the total added value of the head is increased.

[Embodiment 3] Next, an example of an ink jet recording apparatus equipped with a droplet discharge head (ink jet head) according to the present invention will be described with reference to FIGS. 6 and 7. 6 is a side view of the mechanical section of the recording apparatus, and FIG. 7 is a perspective view of the recording apparatus. This inkjet recording apparatus is composed of a carriage movable in the main scanning direction inside a recording apparatus main body 51, a recording head including an inkjet head embodying the present invention mounted on the carriage, an ink cartridge for supplying ink to the recording head, and the like. The printer main body 5 that accommodates the printing mechanism 53 and the like
A sheet feeding cassette (or a sheet feeding tray) 54 capable of stacking a large number of sheets P from the front side can be detachably attached to the lower portion of the sheet 1, and the sheets P can be manually fed. The manual feed tray 55 can be opened and closed, the paper P fed from the paper feed cassette 54 or the manual feed tray 55 is taken in, the desired image is recorded by the printing mechanism unit 53, and then the paper is attached to the rear surface side. The sheet is discharged to the discharge tray 56. The printing mechanism unit 53 holds a carriage 63 slidably in the main scanning direction by a main guide rod 61 and a sub guide rod 62, which are guide members laterally mounted on left and right side plates (not shown), and the carriage 63 is yellow. (Y), cyan (C), magenta (M), black (B
The ink droplet ejection head 64 including the ink jet head according to the present invention for ejecting the ink droplets of each color of k) is arranged with a plurality of ink ejection ports (nozzles) in a direction intersecting the main scanning direction, and the ink droplet ejection direction is downward. I am wearing it towards. Further, each ink cartridge 65 for supplying ink of each color to the head 64 is replaceably mounted on the carriage 63.

The ink cartridge 65 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 inside thereof. The ink supplied to the inkjet head is maintained at a slight negative pressure by the capillary force of. Further, although the heads 64 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 6
3 is the main guide rod 6 on the rear side (downstream side in the paper transport direction)
1 is slidably fitted to the front side (upstream side in the paper transport direction)
Is slidably mounted on the secondary guide rod 62. Then, in order to move and scan the carriage 63 in the main scanning direction, the drive pulley 68 that is rotationally driven by the main scanning motor 67.
A timing belt 70 is stretched between the driven pulley 69 and the driven pulley 69, and the timing belt 70 is fixed to the carriage 63. The carriage 63 is reciprocally driven by the forward and reverse rotations of the main scanning motor 67. On the other hand, in order to convey the paper P set in the paper feed cassette 54 to the lower side of the head 64, the paper P is guided along with a paper feed roller 81 and a friction pad 82 for separating and feeding the paper P from the paper feed cassette 54. A guide member 83, a conveyance roller 84 that reverses and conveys the fed paper P, a conveyance roller 85 that is pressed against the peripheral surface of the conveyance roller 84, and a tip that defines the delivery angle of the paper P from the conveyance roller 84. The roller 86 is provided. The transport roller 84 is rotationally driven by a sub scanning motor via a gear train. Further, there is provided a print receiving member 89 which is a paper guide member for guiding the paper P sent out by the carrying roller 84 below the recording head 64 in correspondence with the movement range of the carriage 63 in the main scanning direction. On the downstream side of the print receiving member 89 in the sheet conveying direction,
A conveyance roller 91 and a spur 92 that are driven to rotate in order to send out the paper P in the paper discharge direction are provided, and further, a paper discharge roller 93 and a spur 94 that send out the paper P to the paper discharge tray 56, and a guide member that forms a paper discharge path. 95 and 96 are provided.

At the time of recording, by driving the recording head 64 in accordance with the image signal while moving the carriage 63, ink is ejected onto the stopped paper P to record one line, and the paper P 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 P has reached the recording area, the recording operation is ended and the paper P is discharged. A recovery device 97 for recovering the ejection failure of the head 64 is arranged at a position outside the recording area on the right end side of the carriage 63 in the moving direction. Recovery device 97
Has a cap means, a suction means, and a cleaning means. The carriage 63 uses the recovery device 9 while waiting for printing.
The head 64 is moved to the 7 side and the head 64 is capped by the capping means, and the ejection port portion is kept in a wet state to prevent ejection failure due to ink drying. Further, by ejecting ink that is not related to recording during recording or the like, the ink viscosity of all the ejection ports is made constant, and stable ejection performance is maintained. When an ejection failure occurs, the ejection port (nozzle) of the head 64 is sealed by a capping unit, and the bubbles are sucked together with the ink from the ejection port by the suction unit through a tube, and the ink or dust attached to the ejection port surface is discharged. Is removed by the cleaning means and the ejection failure is recovered. Further, the sucked ink is discharged to a waste ink reservoir (not shown) installed in the lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir. As described above, in this inkjet recording apparatus, the inkjet head embodying the present invention is mounted, stable ink droplet ejection characteristics are obtained, and image quality is improved. Although the present invention is applied to the inkjet head in the above-described embodiment, the present invention can also be applied to a droplet ejection head that ejects droplets other than ink, for example, a liquid resist for patterning.

Example 4 The droplet discharge head according to the embodiment of the present invention can be applied to a micro pump. FIG. 8 is a vertical cross-sectional view when the configuration of the actuator that constitutes the droplet discharge head described in the above embodiment is applied to a plurality of actuators that constitute a micropump. The actuator of this micropump has a flow path 11A for arranging a vibrating plate 13A between the upper and lower substrates 6 and 7 for flowing a fluid, and a plurality of vibration chambers 21A arranged along the flow path 11A. A pressure correction chamber 23A is formed adjacent to the vibration chamber 21A located at the end. Between the atmospheric pressure correction chamber 23A and the flow path 11A,
A deformable plate 14A having a configuration that is easier to deform than the diaphragm 13A is arranged. All the vibration chambers 21A of the actuators are configured to communicate with the atmospheric pressure correction chamber 23A. A plurality of electrodes 22A are arranged on each diaphragm 13A that constitutes each actuator of this micropump, and different potentials are applied to the adjacent electrodes 22A of the plurality of electrodes 22A provided on one diaphragm 13A. The diaphragm 13A is given, and as a result, the diaphragm 13A is bent. Here, the atmospheric pressure correction chamber 2 arranged so as to communicate with each vibration chamber 21A.
The plate thickness and other conditions of the deformable plate 14A constituting one wall of 3A are set so that the deformation amount thereof is larger than the deformation amount of the vibrating plate 13A. of course,
A plurality of atmospheric pressure correction chambers 23A may be formed. A plurality of the vibrating plates 13A provided with the plurality of electrodes 22A are arranged adjacent to each other along the flow direction of the fluid, and have a structure in which the fluid flows in the flow path 11A. By sequentially driving the vibrating plate 13A from the right side (upstream side) in the figure by applying a voltage to each electrode 22A, the fluid in the flow path 11A flows in the direction of the arrow, and the fluid can be transported. In this embodiment, the example in which the plurality of diaphragms 13A are provided is shown.
A may be one, and in order to improve transport efficiency, the flow path 1
A valve or the like may be provided in an appropriate place such as 1A. As described above, since the atmospheric pressure correction chamber 23A communicating with each vibration chamber 21A is provided and the deformable plate 14A that is more easily deformed than the vibration plate 13A is provided, the atmospheric pressure between the atmospheric pressure in the vibration chamber 21A and the external atmospheric pressure is provided. When a difference occurs, the vibration plate 13A is caused by the pressure difference.
Since the deformable plate 14A provided in the atmospheric pressure correction chamber 23A communicating with each of the vibration chambers 21A flexibly deforms and exerts the function of eliminating the pressure difference before the bending deformation of the pump causes the pump to malfunction. It is possible to maintain the function as.

[0020]

As described above, according to the present invention, it is not necessary to add special constituent elements such as pressure detecting means, and a compact pressure adjusting means in which a part of the existing constituent elements is processed is used as the head chip. By providing the liquid ejection head at low cost, it is possible to manufacture a droplet ejection head that can cope with a wide range of atmospheric pressures, and to provide a droplet ejection head, an ink cartridge, an inkjet recording device, and a micropump using the droplet ejection head. . That is, the droplet discharge head according to any one of claims 1 to 4 can reduce the cost because the head is prevented from increasing in size.
A highly reliable head can be obtained. In the ink cartridge of claim 5, the droplet discharge head which is the droplet discharge head according to any one of claims 1 to 3 according to the invention and the ink tank which supplies ink to the droplet discharge head are integrated. The defective product rate can be reduced and the cost can be reduced. According to the ink jet recording apparatus of the sixth aspect, since the ink jet head which is any one of the droplet ejection heads according to the present invention is mounted, the reliability is high.
Higher image quality is possible. In the micropump according to claim 7, since the diaphragm is deformed by the electrostatic force acting between the electrodes, a micropump having a small size and low power consumption can be realized.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view showing an actuator unit in an assembled state.

FIG. 3 is an explanatory diagram showing the relationship between the air gap and temperature of the actuator of this embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a gap and a temperature of a comparative actuator.

FIG. 5 is a schematic perspective view of an ink cartridge to which the droplet discharge head of the present invention is applied.

FIG. 6 is a schematic view of a mechanical section of an inkjet recording apparatus to which the droplet discharge head of the present invention is applied.

7 is a schematic perspective view of a main part of FIG.

FIG. 8 is a sectional view showing an example in which the present invention is applied to a micropump.

FIG. 9 is a schematic view of a mechanical portion of a conventional inkjet recording device.

FIG. 10 is a cross-sectional view of a conventional inkjet recording device.

[Explanation of symbols]

0 electrostatic droplet discharge head, 1 flow path substrate, 2 electrode substrate, 3 nozzle plate, 5 sealing material, 11 pressurized liquid chamber, 12
Common liquid chamber, 13 vibrating plate, 14 deformable plate, 15 flow path, 21 vibrating chamber, 22 electrode, 23 atmospheric pressure correcting chamber, 3
1 Nozzle hole, 32 Fluid resistance part, 50 Nozzle, 51
Inkjet head, 52 Ink tank, 53
Printing mechanism, 54 paper feed cassette, 63 carriage,
64 heads, 65 ink cartridges, 11A flow path, 13A vibration plate, 14A deformable plate, 21A vibration chamber, 22A electrode, 23A atmospheric pressure correction chamber.

Claims (7)

[Claims] 1. A droplet discharge head for discharging a droplet by a pressure wave caused by an electrostatic force, comprising at least one nozzle hole for discharging the droplet and a liquid communicating with and communicating with the nozzle hole. A pressure liquid chamber, a common liquid chamber that communicates with the pressure liquid chamber, a vibration plate that forms a part of the wall surface of the pressure liquid chamber, and a diaphragm that is in contact with the vibration plate and is on the opposite side of the pressure liquid chamber. It is provided with an air gap and an electrode arranged to face the diaphragm through the air gap, and the diaphragm is bent by the electrostatic force generated by the voltage applied to the electrode to increase the internal pressure in the pressurized liquid chamber. In a droplet discharge head that discharges droplets from the nozzle hole, a deformable plate larger than the deformation amount of the vibrating plate is provided on a part of the wall surface of the common liquid chamber, and the common liquid is sandwiched between the deformable plates. On the side opposite to the chamber, there is a pressure compensation chamber that communicates with the void. Droplet discharge head, characterized in that. 2. The droplet discharge head according to claim 1, wherein the deformable plate has a thickness smaller than that of the vibrating plate. 3. The droplet discharge head according to claim 1, wherein the in-plane length of the deformable plate is larger than the in-plane length of the vibrating plate. 4. The droplet discharge head according to claim 1, wherein the volume of all voids communicating with the atmospheric pressure correction chamber is set to V ₀ , and a uniform pressure of 53 hPa is applied to the deformable plate. , The volume V due to the displacement of the deformable plate
A droplet discharge head characterized in that the change of ₀ is 0.15 × V ₀ or more. 5. A droplet ejection head for ejecting ink droplets,
An ink cartridge in which an ink tank for supplying ink to the droplet discharge head is integrated, wherein the droplet discharge head is the droplet discharge head according to any one of claims 1 to 4. Ink cartridge to do. 6. An ink jet recording apparatus equipped with an ink jet head for ejecting ink droplets, wherein the ink jet head is constituted by the liquid droplet ejection head according to any one of claims 1 to 4. Inkjet recording device. 7. A micropump for transporting a liquid by deformation of a diaphragm, wherein the micropump is used.
3. A micropump comprising the droplet discharge head according to any one of items 1 to 3.