JP2008126584A - Ink jet apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a method of forming an ink liquid droplet and using an aerial current for transportation makes the aerial current prevent the impact of ink to a substrate. <P>SOLUTION: An aerial current control element for controlling an aerial current channel for cutting ink discharged from a nozzle and forming the liquid droplet and/or transporting the formed ink liquid droplet and the presence or absence of the discharge of the aerial current is provided to each ink jet nozzle. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet apparatus that forms minute ink droplets.

  In recent years, the use of inkjet devices has been expanding more and more, ranging from consumer use to industrial use, such as recording devices such as printers, manufacture of industrial fine wiring, and manufacture of color filters for liquid crystal devices. There are various mechanisms for generating ink droplets in an ink jet apparatus. Typical examples include a method using deformation of an element, a method of heating and foaming ink, and an ink by applying an electrostatic force to the ink. And a method for dividing the above. Among them, the method of accelerating the ink by using the deformation of the element and forming the fine ink droplet is one of the most practical methods in both the consumer and industrial fields. Since the method using the deformable element mechanically accelerates the ink, the droplet can be stably formed regardless of the thermal, electrical, and chemical properties of the ink. In addition, since the deformation of the element can be controlled regardless of the type of ink, the movement of the ink can be finely controlled.

An ink jet apparatus using a deformable element has excellent features as described above. However, in this method, the ink droplet formation itself is performed by passing the accelerated ink through the ejection port in which the orifice is opened, and the droplet itself is not controlled. Further, the flying of the formed ink droplet cannot be controlled. As a method for compensating for these drawbacks, Japanese Patent Application Laid-Open No. 11-227192 discloses an ink jet apparatus that uses a gas flow (air flow). According to this method, it is possible to assist the separation of the ink from the orifice by blowing a constant-speed air flow to the orifice to which the ink is supplied. In addition, the flying speed and direction of the ink can be controlled by changing the speed and direction of the airflow.
Japanese Patent Laid-Open No. 11-227192 Japanese Examined Patent Publication No. 6-409 Japanese Unexamined Patent Publication No. 63-122553

  However, the method using an air flow for forming and transporting ink droplets has a problem that the air flow prevents the ink from landing on the substrate. In a conventional method such as Japanese Patent Laid-Open No. 11-227192, the airflow always flows from the orifice toward the recording material, and the airflow that collides with the substrate flows along the substrate surface. The ink droplets flying toward the substrate are scattered by the air current on the surface of the recording material immediately before colliding with the substrate, and the landing accuracy is significantly lowered. In Japanese Patent Publication No. 6-409, each nozzle is provided with an air flow outlet. According to this configuration, it is possible to limit the region where the airflow is discharged to only the ink discharge region. However, there is always a gas flow on the substrate surface, which is not sufficient to prevent scattering of droplets by the airflow. Japanese Patent Laid-Open No. 63-122553 discloses a method of intermittently discharging an airflow at a constant period. According to this method, when ink is ejected at the same period as the ejection period as shown in FIG. 1 (a), the ejection of the airflow is limited to the ejection area and ejection time of the liquid droplets. Air flow can be minimized. However, it is difficult to draw an arbitrary pattern on a recording object on the premise that ink is ejected at a constant period. In the invention of Japanese Patent Laid-Open No. 63-122553, a method is also possible in which an air current is generated intermittently at a constant period and ink is ejected at an arbitrary time when the air current is generated, as shown in FIG. According to this method, an arbitrary pattern can be drawn on the recording material. However, even at the time when ink is not ejected, an air current flows near the ink ejection port, causing a problem that the ink in the ink ejection port is dried and the ejection performance is lowered.

  The present invention controls an air flow path for passing an air flow for dividing ink ejected from a nozzle to form droplets and / or transporting the formed ink droplets, and whether or not air currents are ejected. An air flow control element is an ink jet device provided for each ink jet nozzle.

  According to another aspect of the invention, the airflow control element is driven by a deformation element that accelerates ink.

  Furthermore, the present invention is an ink jet apparatus characterized in that the airflow control element is a valve driven by a deformation element that accelerates ink.

  According to the present invention, since the time during which the airflow is generated can be limited to only the time when the ink is ejected, the ink scattering due to the airflow can be minimized. Further, in the configuration of the present invention, since the air current is blown to the ink ejection port only at the time when the ink is ejected, the drying of the ink surface by the air current can be minimized.

  Further, since the deformation element also has a function of controlling the airflow, it is easy to open the valve at the time when ink is ejected and to spray the airflow onto the ink. Further, since it is not necessary to newly provide a drive system for opening and closing the air flow channel, the space in which the nozzles are configured can be minimized, and the plurality of nozzles can be arranged at high density. .

  According to the present invention, it is possible to generate an air flow near the ink ejection port on demand in accordance with the timing of ejecting ink. Therefore, it is possible to assist the formation of the ink droplets by the air current and transport the ink without the air currents preventing the ink droplets from landing on the substrate surface. Further, when ink is not ejected, no air flow is generated in the vicinity of the ink ejection port, so that ejection does not become unstable due to drying of the ink.

  In addition, it is possible to highly integrate (multi-nozzle) nozzles that have the function of generating an air flow on demand by combining the deformation element that accelerates ink with the function of opening and closing the air flow channel. Become.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 2 is a configuration diagram of an ink jet apparatus representing one embodiment of the present invention. FIG. 3 is an operation diagram illustrating the operation of the ink jet apparatus of FIG. In FIG. 2, the piezo element 1 is configured to be deformed by an electric field generated between the electrodes 2. One surface of the piezo element 1 forms an ink flow path with electrodes interposed therebetween, and compresses ink when the piezo element 1 is deformed. A pulse potential is applied to the electrode 2 by the electric pulse generator 8, and the piezo element 1 is deformed by the electric field generated by the potential difference. The deformed piezo element compresses the ink, and the ink is accelerated toward the ink discharge port 7. The accelerated ink is discharged as a droplet through the ink discharge port 7 to the outside. Different surfaces of the piezo element 1 constitute a part of the air flow channel 3. When the ink is not projected, that is, when the piezo element is not deformed, the piezo element and the other surface of the flow path are designed to contact each other at the contact surface 5, and the air flow path 3 is closed. When ink is ejected, due to the deformation of the piezo element, a gap is generated in the contact surface 5 between the piezo element and the ink flow path, and the air flow path communicates. The discharge port 4 side of the airflow channel extends to the vicinity of the ink discharge port 7 from which ink is discharged. Another side of the air flow channel is connected to a high-pressure cylinder 9 'and a regulator 9 that controls the gas pressure, and is maintained at a constant pressure higher than the outside air.

  Therefore, as shown in FIG. 3, when the piezo element is not deformed, the ink is not protruded, and the flow path is also blocked by the contact surface between the piezo element and the air flow path. When the piezo element is deformed, the air flow channel is connected almost simultaneously with the ejection of the ink, and the air flow is discharged from the air flow outlet. The generated airflow is directed to the ink in the vicinity of the ink discharge port, and collides with the ink to help the ink to be separated from the ink discharge port. Further, the air current plays a role of carrying the separated ink.

  In the present invention, the airflow may have only one of the functions of separating or transporting the ink.

  Further, as shown in FIG. 4, the piezo element may be configured to compress ink only from one side of the ink flow path. Furthermore, the configuration may be such that the entire periphery of the ink flow path is compressed.

  In this embodiment, the deformation direction of the piezo element is perpendicular to the ink protruding direction, but may be parallel to the ink protruding direction as shown in FIG.

  In FIG. 3, the airflow is discharged substantially parallel to the ink discharge direction, but the airflow may be discharged perpendicularly to the ink discharge direction as shown in FIG. In consideration of the ease of separation of the ink droplets and the flying direction of the ink droplets, the airflow may be ejected from other directions.

  The element for accelerating the ink is not limited to the piezo element, and may be a drive element using an electrostatic force as shown in FIG.

  In this embodiment, a part of the inner walls of the ink flow path and the air flow path is formed by a piezo element. However, as long as the air flow path is opened and closed by a piezo element or other driving element that compresses ink. The elements need not be part of the airflow channel.

  In the present embodiment, as a method for keeping the inside of the flow path at a pressure higher than the outside air, a high pressure cylinder and a regulator for controlling the pressure are used. However, other than this configuration, a fan, a diaphragm pump, or other general pumps and pressure generators may be used.

  In this embodiment, nitrogen gas is used as the air flow, but air may be used. In consideration of reaction with ink, a rare gas such as argon or xenon may be used. Further, the airflow may be a mixed gas with water, alcohol, or other organic solvent vapor in order to prevent the ink components from volatilizing during ink ejection and flight.

  This embodiment is an example in which an inkjet apparatus having a configuration in which a piezo element that opens and closes an air flow channel and a piezo element that pushes out ink is shared is made into a multi-nozzle.

  FIG. 8 is a diagram for explaining the apparatus according to the second embodiment of the present invention. The ink jet apparatus includes an ink / airflow discharge block 12, an airflow flow path constituting block 13, and a discharge port constituting block 14. In FIG. 8, each block is drawn separately so that the device configuration of this embodiment can be easily understood, but actually, each block is bonded. 9A to 9E are cross-sectional views of the inkjet device of FIG.

  8 and 9, an electrode for driving a piezo and an ejection pulse generator, a high-pressure cylinder for generating an air flow, an ink tank for supplying ink, and the like are drawn for the sake of simplicity. Absent.

  FIG. 10 depicts only the piezo portion (piezo block) of the ink / airflow discharge block 12 of FIG. FIG. 11 is a cross-sectional view for explaining the operation of the piezo block of FIG.

  The piezo block has an ink flow path 6 and an air chamber 15, and a thin film (not shown in the drawing) serving as an electrode is formed on the side walls of the ink flow path 6 and the air chamber 15 by a method such as sputtering or vapor deposition. A film is formed. An electric pulse generator (not shown in the drawing) is connected to the electrode, and by applying a potential to the electrode, an electric field is generated inside the piezoelectric element, and the piezoelectric element is deformed. In FIG. 11, (car 1) represents a cross section of the piezo block when no potential is applied, and (car 2) represents a cross section of the piezo block when the potential is applied. By independently deforming the piezo wall constituting the side wall of the ink chamber for each nozzle, ink can be ejected independently from a desired nozzle.

  In the air chamber 15 of FIG. 11, an air flow channel 3 is formed as shown in FIG. When the piezo block is not deformed, the piezo element 1 and the inner wall of the air flow channel 3 are in contact with each other at the contact surface 5, and the air flow channel is closed. When the ink is ejected, the piezo block is deformed to create a gap on the contact surface 5, and both sides of the air flow channel communicate with each other.

  The air flow channel 3 in FIG. 9 (a) is connected to the air flow channel of the air flow channel constituting block 13, and pressure gas is supplied from there. Accordingly, the air flow channel 3 communicates with the deformation of the piezo element, whereby an air flow is generated in the air flow channel.

  The generated air current is blown to the ink in the discharge port constituting block 14 to assist the ink droplet formation. Further, the airflow colliding with the ink is discharged to the outside of the ink jet apparatus together with the ink droplets. At that time, the airflow plays a role of carrying the ink droplets.

  In the present invention, the airflow may have only one of the functions of separating or transporting the ink.

  Further, as shown in FIG. 4, the piezo element may be configured to compress ink only from one side of the ink flow path. Furthermore, the configuration may be such that the entire periphery of the ink flow path is compressed.

  In this embodiment, the deformation direction of the piezo element is perpendicular to the ink protruding direction, but may be parallel to the ink protruding direction as shown in FIG.

  The ink jet apparatus shown in FIGS. 8 and 9 is configured to discharge an air flow substantially parallel to the ink discharge direction. However, as shown in FIG. 6, the air flow is discharged perpendicular to the ink discharge direction. May be. In consideration of the ease of separation of the ink droplets and the flying direction of the ink droplets, the air flow may be ejected from other directions.

  The element for accelerating the ink is not limited to the piezo element, and may be a drive element using an electrostatic force as shown in FIG.

  In this embodiment, a part of the inner walls of the ink flow path and the air flow path is formed by a piezo element. However, as long as the air flow path is opened and closed by a piezo element or other driving element that compresses ink. The elements need not be part of the airflow channel.

  In the present embodiment, as a method for keeping the inside of the flow path at a pressure higher than the outside air, a high pressure cylinder and a regulator for controlling the pressure are used. However, other than this configuration, a fan, a diaphragm pump, or other general pumps and pressure generators may be used.

  In this embodiment, nitrogen gas is used as the air flow, but air may be used. In consideration of reaction with ink, a rare gas such as argon or xenon may be used. Further, the airflow may be a mixed gas with water, alcohol, or other organic solvent vapor in order to prevent the ink components from volatilizing during ink ejection and flight.

It is a figure showing the timing of discharge of an air current and ink. It is sectional drawing showing an example of the apparatus structure of this invention. FIG. 3 is an operation diagram for explaining an operation of the apparatus having the configuration shown in FIG. 2. It is sectional drawing showing an example of the apparatus structure of this invention. It is sectional drawing showing an example of the apparatus structure of this invention. It is sectional drawing showing an example of the apparatus structure of this invention. It is sectional drawing showing an example of the apparatus structure of this invention. It is a figure of the Example which made the inkjet apparatus by this invention multi-nozzle. FIG. 9 is a cross-sectional view of the apparatus shown in FIG. 8 in cross sections (A) to (E). It is a figure showing the piezo block used for the apparatus represented by FIG. It is sectional drawing showing operation | movement of the piezo block represented in FIG.

Explanation of symbols

1 Piezo element
2 electrodes
3 Air flow path
4 Air outlet
5 Opening / closing point of air flow path (contact surface between piezo element and ink flow path)
6 Ink flow path
7 Ink ejection port
8 Discharge pulse generator (piezo element drive pulse generator)
9 Pressure regulator
9 'Nitrogen high pressure cylinder
10 Electrostatic drive element
11 Discharge pulse generator (pulse generator for driving electrostatic drive elements)
12 Ink / Airflow ejection block
13 Airflow channel building block
14 Discharge port configuration block
15 Air chamber
16 Ink droplet

Claims (6)

  For each ink outlet, an airflow outlet that discharges an airflow, an airflow passage that supplies airflow to the airflow outlet, and an airflow control device that controls the discharge of the airflow are supplied to the airflow path. An ink jet device comprising an airflow generation device.   2. The ink jet apparatus according to claim 1, wherein the airflow control device is driven by a deformation element that accelerates ink.   3. The ink jet apparatus according to claim 2, wherein the airflow control device is a valve that is opened and closed by a deformation element that accelerates ink.   4. The ink jet apparatus according to claim 2, wherein the deformation element for accelerating the ink is a piezo element.   4. The ink jet apparatus according to claim 2, wherein the deformation element for accelerating the ink is driven by a repulsive force generated when different electric potentials are applied to the electrodes facing each other.   The air stream is air, helium, argon, xenon, and a mixed gas thereof, or a mixed gas of the gas and water or alcohol vapor. The ink jet apparatus according to claim 5.

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