JP2008194943A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic attraction type inkjet recorder using an electroviscous fluid superior in depositing precision and having a simple structure and an advantage of high speed and high resolution recording. <P>SOLUTION: Ink 19 is a fluid having an electroviscous effect that the viscosity is varied by an electric field. A nozzle is equipped with two electrodes 13, 14 having different shapes, two electrodes having different distances to a recording medium, or two electrodes in which one includes an insulation material disposed in an ink supply hole between the electrode and the recording medium and the other includes an insulation material disposed in the ink supply hole between the electrode and the recording medium. A recording voltage is applied to the electrodes to vary the viscosity of the ink passing therethrough. By applying an acceleration potential across the electrode and the counter electrode, the ink of which the viscosity is relatively lowered by the electrostatic attraction force, is ejected. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic attraction type recording method and apparatus for recording an image by ejecting ink, and more particularly to an electric potential for changing the viscosity of the fluid using electroviscous particles and other potentials for electrostatically inducing the fluid. The present invention relates to an electrostatic attraction type recording method and an apparatus using an electrorheological fluid for controlling the ejection of a fluid using the.

  Electrorheological fluids are now well known as electric field responsive fluids. The electrorheological fluid was first announced through U.S. Pat.No. 2,417,850 granted to Winslow in 1943, followed by Winslow U.S. Pat. It was proposed as various forms. These proposed electrorheological fluids are basically a mixture of liquids with electrorheological properties mixed with powdered additives with very small particle diameters. It has a changing nature. It is known that the change in viscosity is roughly proportional to the strength of the applied electric field. The current state in which the viscosity changes depending on the strength of the electric field is called an electroviscous effect. The electrorheological effect is changed by the strength of the applied electric field, and indicates that the viscosity of the fluid changes almost at the same time as the electric field is applied. In the electrorheological fluid described above, the viscosity of the fluid may change from a liquid state to a substantially solid state even with an electric field of several kv / mm. By making use of such characteristics of the electrorheological fluid and making an ink and using an appropriate control means, the desired image can be recorded. Japanese Patent Application Laid-Open No. 55-117663 discloses a technique for recording an image using such electroviscous ink.

  The structure of a conventional head for ejecting electrorheological ink is as shown in FIG. One nozzle sheet 1 and two support sheets 2 and 3 overlap each other. The nozzle sheet 1 receives an ink receiving portion 1a for receiving a certain amount of ink, and ink nozzles from which ink can be ejected. 1b is formed, an ink supply port 2a and an electrode plate 4 are formed on the upper support sheet 2 of the two support sheets 2 and 3, and another electrode plate 4 'is formed on the lower support sheet 3. ing. Such a conventional head maintains a constant pressure inside and outside the nozzle 1b, and the viscosity of the ink in the nozzle 1b changes due to the recording potential 5 applied to the two electrode plates 4, 4 '. When the viscosity has a low viscosity in a liquid state, ink is ejected by a pressure difference applied between the inside and outside of the nozzle. That is, the viscosity of the ink in the nozzle changes depending on the strength of the electric field created by the two electrodes, but the ink is not ejected when the viscosity has a high viscosity in the solid state, and is ejected by the pressure difference when the viscosity becomes low. Is the structure. In such a technique for ejecting electrorheological ink with a recording potential, a pressure difference is generated inside and outside the nozzle, and an additional means for maintaining the pressure difference constant is necessary, so that the apparatus becomes very complicated. The whole cannot be miniaturized and there is an uneconomic problem.

  As another conventional recording technique for solving the problem of the recording technique using an electrorheological fluid, there is an electrostatic attraction method. This method is known from US Pat. No. 3,060,429. As shown in FIG. 2, the acceleration potential difference (nozzle and nozzle) is applied by applying an acceleration potential 9 by a recording signal between the nozzle 6a of the ink storage tank 6 and the platen 8 on which the recording paper 7 is guided. The ink is moved from the nozzle to the recording paper on the platen by the electrostatic force induced in the ink by the potential difference between the platens. This method has an advantage that it can be configured with a simple device because it does not require pressure generation and adjustment as compared with the recording technique using the electrorheological fluid. However, in this method, it was considerably lowered due to the progress of research in the meantime, but since the recording potential was almost the same as the acceleration potential, it stopped at the level where high voltage had to be controlled and it was still difficult to control and disadvantageous for high resolution recording There was a point.

Japanese Patent Laid-Open No. 6-64172 proposes a recording apparatus that solves the above problems. The recording apparatus proposed in Japanese Patent Laid-Open No. 6-64172 uses ink having electroviscosity, and controls the flow from the nozzles by changing the viscosity of the ink by applying a predetermined recording potential according to a recording signal. When the ink is changed to a low viscosity in a liquid state, recording is performed by ejecting the ink with an acceleration voltage. However, in this method, since there are two electrodes in each nozzle, when ink is ejected, ink droplets are ejected from the vicinity of each electrode, and it is very difficult to control the landing accuracy. There can be a problem.
U.S. Pat.No. 2,417,850 U.S. Pat.No. 3,047,057 Soviet Patent No. 1,391,951 U.S. Pat.No. 4,812,251 JP 55-117663 A U.S. Pat.No. 3,060,429 JP-A-6-64172

  The object of the present invention has been devised to solve the above-mentioned problems of the prior art, and is advantageous for recording at high speed and high resolution with a simple structure, and uses an electrorheological fluid with excellent landing accuracy. An electrostatic attraction type ink jet recording apparatus is provided.

  The ink jet recording apparatus according to the present invention achieves the above object by the following configuration.

  (1) Two electrodes are arranged on the wall surface in the vicinity of the ink discharge port, and by controlling the voltage between the two electrodes, the viscosity of the ink exhibiting an electrorheological effect in the ink discharge port is changed. 2. An ink jet recording apparatus, wherein the two electrodes have different shapes in an ink jet recording apparatus that ejects ink exhibiting an electrorheological effect in the ink discharge port by electrostatic force toward a counter electrode.

  (2) One of said two electrodes is an electrode which has a shape where the front-end | tip narrowed toward the counter electrode, The inkjet recording device as described in (1) characterized by the above-mentioned.

  (3) The ink jet recording apparatus according to (2), wherein an electrode having a shape whose tip is narrowed toward the counter electrode is disposed at the same position of the discharge port in all the discharge ports. .

  (4) The ink jet recording apparatus according to (2), wherein the electrode having a shape whose tip is narrowed toward the counter electrode is a common electrode.

  (5) Two electrodes are arranged on the wall surface in the vicinity of the ink discharge port, and by controlling the voltage between the two electrodes, the viscosity of the ink exhibiting the electrorheological effect in the ink discharge port is changed. In the ink jet recording apparatus that causes the ink having an electrorheological effect in the ink discharge port to fly toward the counter electrode by electrostatic force, the distance between one of the two electrodes and the recording medium is the distance between the other electrode and the other electrode. An ink jet recording apparatus characterized in that the distance is shorter than a distance from a recording medium.

  (6) In all the ejection openings, the electrodes whose distance from the recording medium is shorter than the distance between the other electrode and the recording medium are arranged at the same location of the ejection openings. The ink jet recording apparatus according to (5).

  (7) The inkjet recording apparatus according to (5), wherein the electrode whose distance from the recording medium is shorter than the distance between the other electrode and the recording medium is a common electrode.

  (8) Two electrodes are arranged on the wall surface in the vicinity of the ink discharge port, and by controlling the voltage between the two electrodes, the viscosity of the ink exhibiting an electrorheological effect in the ink discharge port is changed. In an ink jet recording apparatus that ejects ink having an electrorheological effect in the ink discharge port by electrostatic force toward a counter electrode, insulation is provided between an electrode excluding one of the two electrodes and a recording medium. An ink jet recording apparatus, wherein an object is disposed in the ink supply port.

  (9) The electrode according to (8), wherein an electrode in which no insulator is disposed in the ink supply port is disposed at the same position of the discharge port in all the discharge ports. Inkjet recording apparatus.

  (10) The ink jet recording apparatus according to (8), wherein an electrode in which an insulator is not disposed in the ink supply port between the recording medium is a common electrode.

(Function)
The recording apparatus according to the present invention can reduce the influence of the electric field of the adjacent recording electrodes by using a potential viscous fluid as the ink. Furthermore, two electrodes having different shapes, or two electrodes having different distances from the recording medium, or an electrode in which an insulator is disposed in the ink supply port between the recording medium and the recording medium are insulated by an insulator. By preparing a nozzle in which an electrode that is not arranged in the supply port is prepared, it is possible to discharge ink droplets with high accuracy from one location of the discharge port when discharging ink, and a static that has excellent landing accuracy. It becomes possible to provide an electro-attractive inkjet recording apparatus.

  As described above, the recording apparatus according to the present invention can reduce the influence of the electric field of adjacent recording electrodes by using a potential viscous fluid as ink. Furthermore, two electrodes having different shapes, or two electrodes having different distances from the recording medium, or an electrode in which an insulator is disposed in the ink supply port between the recording medium and the recording medium are insulated by an insulator. By preparing a nozzle in which an electrode that is not arranged in the supply port is prepared, it is possible to discharge ink droplets with high accuracy from one location of the discharge port when discharging ink, and a static that has excellent landing accuracy. It becomes possible to provide an electro-attractive inkjet recording apparatus.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

  In FIG. 3, the ejection head 10 includes an ink storage tank 11 that stores a certain amount of ink, and a nozzle 12 that ejects ink from the ink storage tank 11. The ink is always filled in the ink storage tank 11 by using a normal ink supply means such as an existing ink jet printer head. The ink stored in the ink storage tank 11 is an electroviscous ink whose viscosity changes depending on the electric field, and is obtained by suspending finely pulverized ink powder in an electrorheological fluid. In order to satisfy the conditions that the electrorheological fluid must have as a recording ink, it may be possible to consider mixing pigments, dyes, coagulants, rust inhibitors, diffusing agents, and the like. In addition, in order to keep the fluid in a mixed state, the powdered additive and the electrorheological fluid have the same density so that they are not precipitated, or when they are precipitated or suspended due to a difference in density, mixing means for preventing this. Could be taught.

  The ink thus produced is continuously supplied to the nozzle 12 connected to the ink storage tank 11 according to the current state of the capillary tube, and can be ejected to the outside through the nozzle.

  The nozzles 12 of the jet head 10 can be manufactured by arranging in rows and columns like a gluing or mesh shape like current inkjet printer heads and thermal heads for higher resolution, higher speed, colorization, etc. .

  As a valve means for changing the viscosity of the ink filled in the nozzle 12 and controlling the flow of ink in the nozzle, two electrodes 13 and 14 having different shapes facing each other at a predetermined interval in the nozzle 12 are used. Is provided so that a predetermined recording potential 15 can be applied to the two electrodes 13 and 14 having different shapes to create an electric field that can change the viscosity of the ink. The recording potential 15 is intermittently applied by a recording signal modulated by the desired image. Here, the recording electricity 15 is different from the recording technology using the existing electrorheological fluid (FIG. 1), and it is sufficient to create an electric field that prevents the ink from flowing from the nozzle 12 or not. Applied at a low potential.

  Next, an accelerating means for moving the ink whose viscosity is changed so as to flow through the nozzle 12 by the valve means as described above to the recording medium 16 moves the platen 17 on which the nozzle 12 and the recording medium 16 are guided. It is configured to be connected to a constant acceleration potential 18 so that an electrostatic force that accelerates the movement of the ink having the reduced viscosity is formed therebetween. Then, the ink that has been changed to a low-viscosity viscosity by the valve means is ejected by the accelerating force of the electrostatic force and ejected onto the recording medium 16 without the assistance of the pressure difference applied to the inside and outside of the existing nozzle. The ink ejection will be described in more detail. In the case where the two electrodes 13 and 14 facing each other at a predetermined interval in the nozzle 12 have the same shape and are arranged at symmetrical positions (FIG. 4), As a result, meniscuses are formed from the vicinity of the two electrodes, and ink droplets are ejected from the vicinity of the respective electrodes. However, by making the two electrodes 13 and 14 different shapes (FIG. 5) or making them vertically asymmetric (FIGS. 6 and 7), an electrode in which the electric field is more likely to concentrate, Alternatively, the ink droplet 19 can be ejected only from the vicinity of one electrode where a meniscus is easily formed.

  The operation of recording an image according to the present invention will be described as follows.

  The ink filled in the ink storage tank 11 of the ejection head 10 is supplied to the nozzle according to the current state of the capillary tube. The ink maintains a balance by forming a meniscus from the tip of the nozzle 12 by the action of the capillary, the surface tension, and gravity.

  When the recording potential 15 is applied in this state, the ink in the nozzle 12 has a high viscosity in a gel state, that is, a shear yield strength that does not flow. However, when the recording potential 15 is not applied, the ink changes to a low viscosity in a liquid state and enters a flow state. However, the state is not a state where it flows arbitrarily and goes out of the nozzle 12.

  On the other hand, when the acceleration potential 18 is applied, the ink existing in the nozzle 12 is electrostatically induced by the difference in the acceleration potential 18 and receives a force to move toward the platen 17 that is the acceleration electrode. When the ink in the nozzle 12 is changed to a liquid state, the ink is ejected only from the vicinity of the electrode where the electric field tends to concentrate or the meniscus is easily formed. However, when the ink is in a gel state, it cannot be ejected even by acceleration force. That is, a stepwise force is applied to the ink in the nozzle 12 by applying the recording potential 15 and the acceleration potential 18 described above, and a desired image can be recorded by appropriately selecting the timing and conditions of the force.

  Although it is the structure of the multiple nozzle of the electrode in which an electric field tends to concentrate or the electrode in which a meniscus is easy to form, as shown in FIGS. With this configuration, the potential of the potential applied to the electrodes arranged in the adjacent nozzles can be reduced by setting the same electric potential for the electrodes where electric fields tend to concentrate or the meniscuses are easily formed at all the discharge ports. It can be minimized. Further, when ink is ejected, the recording voltage can be freely controlled by controlling only the potential of the other electrode of the electrode on which the electric field tends to concentrate or the electrode on which the meniscus is easily formed. Further, in order to make the configuration simple and advantageous for high integration, it is desirable to use an electrode that tends to concentrate an electric field or an electrode that easily forms a meniscus as the common electrode 14B. As an example, in FIG. 8, a large number of flow paths 20B are divided at a predetermined interval in the nozzle body 19B, and electrodes 13 connected to independent recording potentials 15 are arranged on the inner surfaces of the flow paths 20B, respectively. Shows an example configuration in which a common electrode 14B having a shape different from that of the electrode 13 in the form of a metal thin film is covered. Means for forming an electrode that easily concentrates an electric field or an electrode that easily forms a meniscus will be described below.

  As shown in FIG. 5, the first means for forming an electrode that easily concentrates an electric field or an electrode that easily forms a meniscus is to change the shape of the two electrodes 12 and 13 in the nozzle 12 to different shapes. It is to be. In FIG. 5, an inclined portion is formed at the tip of one of the electrodes 13 so that the electric field is easily concentrated in the vicinity of the electrode 13, thereby enabling ink droplets to be selectively ejected only from the vicinity of the electrode 13. .

  As shown in FIG. 6, the second means for forming an electrode that easily concentrates an electric field or an electrode that easily forms a meniscus is one of the two electrodes 13 and 14 in the nozzle 12 and The distance from the recording medium is shorter than the distance between the other electrode 14 and the recording medium. With this configuration, the ink in the vicinity of the electrode 13 is more easily attracted to the recording medium side by the electric field than the ink in the vicinity of the other electrode 14, and ink droplets can be selectively ejected only from the vicinity of the electrode 13. .

  As shown in FIG. 7, a third means for forming an electrode that easily concentrates an electric field or an electrode that easily forms a meniscus is an insulator between one electrode 14 in the nozzle 12 and the recording medium. 21 is arranged. By disposing the insulator 21 between the electrode 14 and the recording medium, the electric field between the electrode 14 and the recording medium can be weakened, so that ink droplets can be selectively ejected only from the other electrode 13. Is possible.

FIG. 9 is an exploded perspective view showing a fluid ejection head for explaining a conventional recording technique using an electrorheological fluid. Sectional drawing which showed the ejection head and the platen in order to demonstrate the recording technique by the conventional electrostatic attraction system. Schematic of the apparatus shown in order to demonstrate the technique which records an image as an electrostatic attraction system using an electrorheological fluid. The figure which showed the structural example of the nozzle which injects electrorheological fluid in order to implement this invention. The figure which showed the structural example of the nozzle which injects electrorheological fluid in order to implement this invention. The figure which showed the structural example of the nozzle which injects electrorheological fluid in order to implement this invention. The figure which showed the structural example of the nozzle which injects electrorheological fluid in order to implement this invention. The figure which showed the structural example of the nozzle which injects electrorheological fluid in order to implement this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle sheet 1a Ink receiving part 1b Ink nozzle 2 Support sheet 2a Ink supply port 3 Support sheet 4 Electrode plate 4 'Electrode plate 5 Recording potential 6 Ink storage tank 6a Nozzle 7 Recording paper 8 Platen 9 Acceleration potential 10 Ejecting head 11 Ink Storage tank 12 Nozzle 13 Electrode 14 Electrode 14B Common electrode 15 Recording potential 16 Recording medium 17 Platen 18 Acceleration potential 19 Ink droplet 19B Nozzle body 20B Flow path

Claims (10)

  Two electrodes are arranged on the wall surface near the ink discharge port, and by controlling the voltage between the two electrodes, the viscosity of the ink showing the electroviscous effect in the ink discharge port is changed, and the electrode is changed from the electrode to the counter electrode. An ink jet recording apparatus in which ink having an electrorheological effect in the ink discharge port is ejected by electrostatic force toward the ink jet recording apparatus, wherein the two electrodes have different shapes.   2. The ink jet recording apparatus according to claim 1, wherein one of the two electrodes is an electrode having a shape whose tip is narrowed toward the counter electrode.   3. The ink jet recording apparatus according to claim 2, wherein an electrode having a shape whose tip is narrowed toward the counter electrode is disposed at the same position of the discharge port in all of the discharge ports.   The ink jet recording apparatus according to claim 2, wherein the electrode having a shape whose tip is narrowed toward the counter electrode is a common electrode.   Two electrodes are arranged on the wall surface near the ink discharge port, and by controlling the voltage between the two electrodes, the viscosity of the ink showing the electroviscous effect in the ink discharge port is changed, and the electrode is changed from the electrode to the counter electrode. In the ink jet recording apparatus in which the ink exhibiting the electrorheological effect in the ink discharge port is caused to fly by electrostatic force, the distance between one of the two electrodes and the recording medium is the distance between the other electrode and the recording medium. An ink jet recording apparatus characterized in that it is shorter than the distance.   6. The electrode having a distance from the recording medium shorter than the distance between the other electrode and the recording medium is arranged at the same location of the ejection opening in all the ejection openings. 2. An ink jet recording apparatus according to 1.   6. The ink jet recording apparatus according to claim 5, wherein the electrode whose distance from the recording medium is shorter than the distance between the other electrode and the recording medium is a common electrode.   Two electrodes are arranged on the wall surface near the ink discharge port, and by controlling the voltage between the two electrodes, the viscosity of the ink showing the electroviscous effect in the ink discharge port is changed, and the electrode is changed from the electrode to the counter electrode. In the ink jet recording apparatus in which the ink showing the electrorheological effect in the ink discharge port is ejected by electrostatic force toward the ink, an insulator is provided in the ink supply port between one of the two electrodes and the recording medium. An ink jet recording apparatus, wherein the ink jet recording apparatus is disposed.   9. The ink jet recording according to claim 8, wherein an electrode in which an insulator is not disposed in the ink supply port is disposed at the same position of the discharge port in all the discharge ports. apparatus.   9. The ink jet recording apparatus according to claim 8, wherein an electrode in which an insulator is not disposed in the ink supply port with the recording medium is a common electrode.

Images