JPH0281633A - Liquid droplet forming device - Google Patents

Abstract

PURPOSE:To obtain the title device miniaturized and densified still more by arranging the first electrode to an elastic movable part and forming an insulating material having a dielectric constant different from that of the liquid in contact with the second electrode to the surface electrode, and allowing a current to flow to the first electrode to deform the elastic movable part. CONSTITUTION:A control electrode 17 as the first electrode is arranged to the surface of a cantilevered beam 15 and an insulating film 18 composed of silicon (SiO2) having a dielectric constant epsilon1 as an insulating material is laminated to the surface of the control electrode 17. An earth electrode 19 as the second electrode is arranged to the inner wall of the ink chamber 14 opposed to the cantilevered beam 15 composed of the above mentioned three-layer structure and ink 20 having a dielectric constant epsilon2 as a liquid is injected in the ink chamber 14. In this constitution, the relation of epsilon1<epsilon2 is formed. When control voltage due to a printing pixel signal is applied between the control electrode 17 and the earth electrode 19 in this state, force acts on the control electrode 17 having the insulating film 18 having a small dielectric constant formed to the surface thereof from the ink 20 having a high dielectric constant. By this method, the ink 20 becomes an ink droplet from a nozzle 16.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a droplet forming device used in an ink supply means of an inkjet printer or the like.

2. Description of the Related Art A droplet forming device conventionally used as an ink supply means for an inkjet printer or the like will be explained using a specific example. First, as a first conventional example, there is a pressurized on-demand type inkjet printer as shown in FIG. This is an ink chamber 3 having a nozzle 1 and an ink supply port 2.
A piezoelectric element 5 is disposed on the side wall of the diaphragm 4 through a diaphragm 4, and by applying a control voltage for printing to this piezoelectric element 5 through a lead wire 6, the piezoelectric element 5 is displaced, and this displacement causes a The diaphragm 4 was deformed to pressurize the ink 7 in the ink chamber 3, thereby ejecting ink droplets from the nozzle 1.

Next, as a second conventional example, as shown in FIG. 7, there is one disclosed in Japanese Patent Publication No. 60-59869. A control electrode 10 is provided at the nozzle 9 at the tip of the ink chamber 8, and a counter electrode 12 is provided at a position facing the control electrode 10 with a recording paper 11 in between. By applying a high voltage that is the control voltage.

Printing is performed by ejecting ink 13 from nozzle 9 and adhering it to recording paper 11 by electrostatic attraction between control electrode 10 and counter electrode 12.

Problems to be Solved by the Invention First, in the case of the first conventional example, since the method of ejecting the ink 7 from the ink chamber 3 is by displacing the piezoelectric element 5, the shape of the piezoelectric element 5 is If it is not large enough, sufficient displacement for ejecting the ink 7 will not be obtained. Therefore, in such a device, the shape of the piezoelectric cord 5 naturally becomes large, and as a result, there is a problem that it is impossible to obtain a device with high density.

Furthermore, in the case of the second conventional example, the ink 13 is ejected from the nozzle 9 using electrostatic attraction between the control electrode 10 and the counter electrode 12; Due to its large size, a high voltage is required to eject the ink 13. As a result, the power supply circuit for generating the high voltage becomes large-scale, which increases the cost of the apparatus.

Means for Solving the Problems Therefore, in order to solve such problems, claim 1
The described invention includes forming a nozzle for discharging liquid, providing a liquid chamber communicating with the nozzle and having an elastic movable part inside, and disposing a first electrode in the elastic movable part, and facing the first electrode. A second electrode is disposed on the inner wall of the liquid chamber at a position where the second electrode is placed, an insulator having a dielectric constant different from that of the liquid in contact with the second electrode is formed on the surface of the first electrode, and a current is applied to the first electrode. Printing control means for deforming the elastic movable portion of the sink is provided.

Further, the invention according to claim 2 provides a nozzle for discharging liquid, a liquid chamber communicating with the nozzle and having an elastic movable part inside, a first electrode disposed in the elastic movable part, and A second electrode is disposed on the inner wall of the liquid chamber at a position facing the first electrode, an insulator having a dielectric constant different from that of the liquid in contact with the second electrode is formed on the surface of the first electrode, and the second electrode is formed on the surface of the first electrode. Printing control means is provided to apply a current to one electrode and deform its elastic movable part, and a counter electrode is disposed at a position facing the nozzle.

By deforming the elastic movable part by the printing control means, the liquid protruding from the nozzle is attracted to the counter electrode side by the electrostatic attraction force between the nozzle and the counter electrode.

In the invention according to claim 1, by applying a control voltage between the first electrode and the second electrode by the printing control means,
The elastic movable part can be deformed due to the difference in the dielectric constant of the insulator formed on the surface of the first electrode and the dielectric constant of the liquid in contact with the second electrode. Droplets can now be easily ejected from the nozzle without using a nozzle, and the first elastic movable part uses etching technology, and the first and second electrodes use thin film technology such as sputtering or vapor deposition. Since it can be made extremely small, it is possible to obtain a device that is much smaller and has a higher density.

In the invention according to claim 2, by applying a control voltage between the first electrode and the second electrode by the printing control means,
The elastic movable part can be deformed due to the difference in the dielectric constant of the insulator formed on the surface of the first electrode and the dielectric constant of the liquid in contact with the second electrode.

As a result, the liquid protruding from the nozzle can be ejected forcefully by the electrostatic attraction force acting between it and the ground electrode, so the switching voltage applied between the electrodes as in the second conventional example can be replaced with a high voltage. There is no need for a drive, which makes it possible to obtain an inexpensive and lightweight device. In addition, the elastic movable part can be made extremely small using etching technology, and the first and second electrodes can be made extremely small using thin film technology such as sputtering and vapor deposition, so they can be made much smaller and more dense. You can get the equipment.

Embodiment An embodiment of the invention according to claim 1 is shown in FIGS. 1 to 3 (
The explanation will be based on a) and (b). Note that this embodiment corresponds to the first conventional example.

A cantilever beam 15 as an elastic movable portion is provided in the ink chamber 14 as a liquid chamber, and a nozzle 16 is formed at one end of the ink chamber 14 .

In this case, the cantilever beam 15 is made by etching silicon (Sin2). Also.

A control electrode 1 as a first electrode is provided on the surface of the cantilever beam 15.
On the surface of the control electrode 17, an insulating film 18 made of silicon (810□) having a dielectric constant ε1 is laminated as an insulator. The ink chamber 14 facing the cantilever beam 15 having a three-layer structure in this way
A ground electrode 19 as a second electrode is disposed on the inner wall of the housing. Further, ink 20 having a dielectric constant C2 is injected into the ink chamber 14 as a liquid. Furthermore, between the control electrode 17 and the ground electrode 19,
A pulsed control voltage is applied from a control power source (not shown) serving as a printing control means.

In such a configuration, it is now assumed that there is a relationship of ε□<12. When a control voltage based on a pixel signal for printing is applied between the control electrode 17 and the ground electrode 19 in this state, an insulating film 18 with a low dielectric constant is formed on the surface of the ink 20 having a high dielectric constant. Force acts on the electrode 17 side. As a result, the cantilever beam 15 deforms downward toward the recess 21 as shown in FIG. 3(a), and then returns to its original flat state as shown in FIG. 3(b) when the control voltage is turned off. Return. Due to the pressure when trying to return, the ink 2
0 is ejected from the nozzle 16 as an ink droplet.

As described above, ink droplets can be easily discharged by deforming the cantilever beam 15 using the difference in dielectric constant between the ink 20 and the insulating film 18, and thereby, the first conventional example ( There is no need to use a piezoelectric element 5 (see FIG. 6), and one cantilever beam 15 can be created by etching technology.

Since the control electrode 17 and the ground electrode 19 can be created using thin film techniques such as sputtering and vapor deposition, it is possible to obtain a device that is more compact and denser than ever before.

Next, a modification of the invention according to claim 1 described above is shown in FIG.
In this embodiment, which will be explained based on a) and (b), a ground electrode 19 as a second electrode is disposed on the recess 21 side of the ink chamber 14, and the other configurations are the same as in the above-mentioned embodiment. There is nothing that will change.

Therefore, in this case, when a control voltage is applied due to the relationship *M 1 < E @, the cantilever beam 15 will be deformed upward, and the pressure during this deformation will cause the ink 20 to be converted into ink droplets from the nozzle 16. It will be discharged.

Next, an embodiment of the invention according to claim 2 will be described based on FIG. This embodiment corresponds to the second conventional example, and a detailed explanation of the same parts as the embodiment of the invention claimed in claim 1 will be omitted, and the same parts will be denoted by the same reference numerals. .

A cantilever beam 15 as an elastic movable part is provided in the ink chamber 14 as a liquid chamber, and a control electrode 17 as a first electrode is disposed on the surface of this cantilever beam 15. An insulating film 18 of Sin having a dielectric constant ε1 is formed on the surface of the cantilever beam 17, so that the cantilever beam 15 has a three-layer structure. A ground electrode 19 serving as a second electrode is provided in the recess 21 below the cantilever beam 15 .

Further, a counter electrode 22 is disposed at a position facing the nozzle 16 formed at one end of the ink chamber 14 with a gap g interposed therebetween. Note that also in the case of this embodiment, the insulating film 1
The dielectric constant ε1 of 8 and the dielectric constant ε2 of the ink 20 as a liquid.
There is a relationship of cl ε2 between the control electrode 15 and the ground electrode 19, and a pulsed control voltage is applied between the control electrode 15 and the ground electrode 19 from a control power source (not shown) as a printing control means. It has become.

In such a configuration, when a control voltage is applied to the control electrode 15 by a pixel signal for printing, the cantilever beam 15 is deformed upward due to the difference in dielectric constant. At this time, the ink 20, which is normally kept drawn inward from the nozzle 16 by negative pressure, is subjected to pressure in the discharge direction due to the deformation of the cantilever 15, forming a meniscus a. As a result, the gap between the ink 20 and the counter electrode 22 becomes smaller, and the electrostatic attraction force acting between the ink 20 and the counter electrode 22 causes the ink 20 to be discharged toward the recording paper 23 to perform printing. .

As described above, in this embodiment, the switching of the control voltage only needs to deform the cantilever beam 15 in the vertical direction, and it is sufficient to switch the control voltage to the opposite electrode 12 as in the second conventional example (see FIG. 7). Since a high voltage is not required for driving between the two, the power supply circuit can be made inexpensive. Furthermore, since the cantilever beam 15, the control electrode 17, and the ground electrode 19 can be created using etching technology or thin film technology, they can be extremely miniaturized as in the embodiment of the invention described in claim 1. A high-density device can be obtained.

Note that in this embodiment, the earth electrode 19 is used as the second electrode.
Although it is arranged in the recess 21 below the ink chamber 14, it is not limited to this, and the same effect can be obtained even if it is arranged above the ink chamber 14 in the opposite position.

Effects of the Invention The invention according to claim 1 forms a nozzle for discharging a liquid, provides a liquid chamber communicating with the nozzle and having an elastic movable part inside, and arranges a first electrode in the elastic movable part, A second electrode is disposed on the inner wall of the liquid chamber at a position facing the first electrode, and an insulator having a dielectric constant different from the dielectric constant of the liquid in contact with the second electrode is formed on the surface of the first electrode. Since the printing control means is provided to apply a current to the first electrode and deform its elastic movable part, by applying a control voltage between the first electrode and the second electrode by the printing control means, the surface of the first electrode is The elastic movable part can be deformed due to the difference in the dielectric constant of the insulator formed on the second electrode and the dielectric constant of the liquid in contact with the second electrode. In addition, the elastic movable part uses etching technology, and the first and second electrodes are made extremely small using thin film technology such as sputtering and vapor deposition. Therefore, it is possible to obtain a device that is much smaller in size and has a higher density.

Further, the invention according to claim 2 provides a nozzle for discharging liquid, a liquid chamber communicating with the nozzle and having an elastic movable part inside, a first electrode disposed in the elastic movable part, and A second electrode is disposed on the inner wall of the liquid chamber at a position facing the first electrode, an insulator having a dielectric constant different from that of the liquid in contact with the second electrode is formed on the surface of the first electrode, and the second electrode is formed on the surface of the first electrode. A printing control means is provided to apply a current to one electrode and deform its elastic movable part, and a counter electrode is disposed at a position facing the nozzle, and the printing control means deforms the elastic movable part to control the liquid protruding from the nozzle. Since the electrostatic attraction force between the first electrode and the second electrode is used to attract the opposite electrode, by applying a control voltage between the first electrode and the second electrode by the printing control means, the first electrode The elastic movable part can be deformed due to the difference in the dielectric constant of the insulator formed on the surface and the dielectric constant of the liquid in contact with the second electrode, which causes the liquid protruding from the nozzle to interact with the ground electrode. Because it can be ejected forcefully by electrostatic attraction,
It is no longer necessary to drive the switching voltage applied between the t11 poles at a high voltage as in the second conventional example, thereby making it possible to obtain an inexpensive and lightweight device. In addition, the elastic movable part uses etching technology, and the first and second electrodes are sputtered.

Since each of them can be made extremely small using thin film technology such as vapor deposition, it is possible to obtain a device that is much smaller and has a higher density.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the invention as claimed in claim 1;
FIG. 2 is a longitudinal sectional side view thereof, and FIGS. 3(a) and 3(b) are explanatory diagrams showing the state of the elastic movable portion before and after deformation. 4(a) and 4(b) are explanatory diagrams showing a modification of FIG. 1 and show the state before and after deformation of the elastic movable part, and FIG. 5 is a machine side view showing an embodiment of the invention as claimed in claim 2. - FIG. 6 is a vertical side view showing the first conventional example, and FIG. 7 is a side view showing the second conventional example. 14... Liquid chamber, 15... Elastic movable part, 16... Nozzle, 17... First electrode, 18... Insulator, 19...
...Second electrode. 22...Counter electrode, ε2...Dielectric constant Applicant Rico Co., Ltd. Figure (a) (b) Ichitsu LL diagram (a) (b) Figure Ichiatsu Zkon

Claims (1)

[Claims] 1. A nozzle for discharging liquid, a liquid chamber communicating with the nozzle and having an elastic movable part inside, a first electrode disposed on the elastic movable part, and a first electrode disposed on the elastic movable part. a second electrode disposed on the inner wall of the liquid chamber at an opposing position; an insulator formed on the surface of the first electrode and having a dielectric constant different from the dielectric constant of the liquid in contact with the second electrode; A droplet forming device comprising a printing control means for applying a current to the first electrode to deform its elastic movable portion. 2. A nozzle for discharging liquid, a liquid chamber communicating with the nozzle and having an elastic movable part inside, a first electrode disposed on the elastic movable part, and a liquid chamber located at a position opposite to the first electrode. a second electrode disposed on the inner wall of the chamber; an insulator formed on the surface of the first electrode having a dielectric constant different from the dielectric constant of the liquid in contact with the second electrode; and an electric current applied to the first electrode. a printing control means for deforming the elastic movable part by causing the printing control means to deform the elastic movable part, and a counter electrode disposed at a position facing the nozzle, and the printing part protrudes from the nozzle by deforming the elastic movable part by the printing control means. A droplet forming device, characterized in that the liquid is attracted to the opposite electrode by electrostatic attraction between the liquid and the opposite electrode.