JP3340378B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly, to a recording method using a liquid ink in which a coloring material is dispersed, by flying at least a coloring material component in the ink as an ink droplet on a recording medium. The present invention relates to an ink jet recording apparatus for performing the above.

[0002]

2. Description of the Related Art A device for recording an image by spraying liquid ink as small droplets called ink droplets on a recording medium to form recording dots has been put to practical use as an ink jet printer.

[0003] Ink jet printers have the advantage that they are less noisy than printers of other recording methods and do not require processing such as development and fixing. The method of inkjet printer is
Although many proposals have been made so far, in particular, as described in JP-B-56-9429 and JP-B-61-59911, for example, ink droplets are ejected by the pressure of steam generated by the heat of a heating element. Method, for example,
As described in, for example, Japanese Patent Application Laid-Open No. 3-12138, a method of flying an ink droplet by a mechanical pressure pulse generated by a piezoelectric element is typical.

A recording head (hereinafter, referred to as an ink jet head) used in an ink jet printer is mounted on a carriage and transported in a recording paper direction (hereinafter, referred to as a recording head).
A serial scanning head that performs recording while moving in a direction (hereinafter, referred to as a main scanning direction) perpendicular to a sub-scanning direction has been put to practical use. However, with this serial scanning head, it is difficult to increase the recording speed. Therefore, a printer that increases the recording speed by using a line scanning type head in which the length of the recording head is the same as the width of the recording paper has been considered. It is not easy for the following reasons.

[0005] For example, in the ink jet recording system, a large number of individual nozzles corresponding to the resolution are provided. However, evaporation or volatilization of the solvent tends to cause local concentration of the ink, which is a cause of nozzle clogging. Had become.

Further, in a system using vapor pressure for forming an ink jet, adhesion of an insoluble substance formed by a thermal or chemical reaction with ink tends to cause nozzle clogging.

Further, in the system using the pressure by the piezoelectric element, a complicated structure such as an ink flow path has more easily induced clogging. A line scanning head that requires thousands of nozzles, which is more than a serial scanning head that uses tens to hundreds of tens of nozzles, is likely to be clogged at a very high frequency, and There was a problem that the above reliability was lacking.

[0008] Further, in the method using the pressure of steam, a diameter of 20 μm corresponding to a recording dot having a diameter of 50 μm on recording paper is used.
Since it is difficult to generate ink particles having a particle size of μm or less, it has been difficult to manufacture a high-resolution head.

Further, in the method using the pressure generated by the piezoelectric element, the recording head has a complicated structure, so that it is difficult to manufacture a high-resolution head due to a problem in processing technology.

For this reason, the conventional ink jet system is
All of them have a problem that it is difficult to improve the resolution. In order to solve these problems, a voltage is applied to an electrode array formed by arranging a plurality of thin-film control electrodes on a substrate, and the ink or the color material components in the ink are separated from the ink surface using electrostatic force. An ink jet recording method has been proposed in which the ink is ejected as ink droplets. For example, JP-A-49-62024, JP-A-56-44
No. 67, a method in which ink droplets fly using electrostatic attraction, and Japanese Patent Application Laid-Open No. 7-502218 discloses a method of using an ink containing a charged colorant component, A method has been proposed in which ink droplets are made to fly by increasing the pressure.

In these systems, the recording head has a slit-like nozzle structure which does not require a nozzle for each individual dot, or a nozzleless structure which does not require a partition of an ink flow path for each individual dot. This is effective for preventing and recovering from clogging which has been a major obstacle in realizing a line scanning type recording head. In addition, the latter can stably generate and fly an ink droplet having a very small diameter, and is therefore suitable for high resolution.

However, in the ink jet recording apparatus of the type in which the color material component is ejected as ink droplets by the above-described electrostatic force, since the recording head is nozzleless, it is effective in preventing clogging, but on the substrate of the recording head. There has been a problem that the ink droplets can be freely moved in the main scanning direction, so that the ejection positions of the ink droplets become unstable.

In addition, since the ink droplets are ejected at a voltage having the same polarity as the charging polarity of the coloring material and fly on the recording medium, the coloring material component repels from the electrode position on the recording head and escapes. There is also a problem that the components cannot be stably supplied to the ejection position of the ink droplet.

[0014] Therefore, it is difficult to eject a sufficient amount of ink droplets from a predetermined ejection point in a stable state and fly them, and there is a problem that characters and images cannot be recorded well on a recording medium.

[0015]

SUMMARY OF THE INVENTION According to the present invention, a color material component in ink is stably supplied to the leading edge of a control electrode, which is an ink droplet ejection position, and the ink droplet ejection position is stable. It is another object of the present invention to provide an ink jet recording apparatus capable of stably ejecting and flying ink droplets without clogging.

[0016]

According to the present invention, an ink in which a coloring material component is dispersed in a solvent is acted on by electrostatic force to fly at least an ink droplet containing the coloring material component toward a recording medium. In an ink jet recording apparatus that performs recording, an insulating substrate having a plurality of arranged through holes, a plurality of control electrodes formed around the through holes on the surface of the insulating substrate, and for applying the electrostatic force, and A control electrode substrate having at least an insulating protective layer formed on the control electrode; a convex ink guide disposed substantially at the center of the through-hole and projecting in the ink droplet flight direction; And an ink supply unit for supplying the ink to the convex ink guide through the ink jet recording apparatus.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet apparatus according to the present invention comprises:
An insulating substrate having a plurality of arranged through holes, a plurality of control electrodes formed around the through holes on the surface of the insulating substrate for applying an electrostatic force, and an insulating protection formed at least on the control electrodes; A control electrode substrate having a layer, a convex ink guide disposed at a substantially central position of the through hole, protruding in the ink droplet flying direction, and ink supply means for supplying ink to the convex ink guide through the through hole. .

According to the present invention, since a plurality of through holes and a convex ink guide projecting from the through holes in the ink droplet flying direction are provided corresponding to the image points, the ink is applied to the image points. And the ink is supplied to the ink droplet flying position of each convex ink guide. At this time, the ink moves on the convex ink guide to the ink droplet flying position by using the wetting and the surface tension. For this reason, there is no clogging in the nozzles, and the ink droplet flying position and the meniscus at the ink droplet flying position are determined uniformly, and are affected by the ink pressure, the atmospheric pressure, mechanical vibration, and adjacent dots. Without this, the flight of the ink droplets is stabilized, and high-quality recording with stable density can be performed. In this manner, the color material components in the ink can be stably supplied to the leading edge of the control electrode, which is the ink droplet ejection position, and the ink droplet ejection position can be stabilized to cause clogging of the ink droplet. It is possible to discharge and fly without any trouble. In addition, by providing an insulating protective layer at least on the control electrode, it is possible to prevent conduction between the control electrodes due to the adhesion of the charging ink or dust or the like on and between the control electrodes.

The color material component is positively or negatively charged, and is recorded by causing an ink droplet containing at least the color material component to fly toward a recording medium by applying an electrostatic force having the same polarity as the color material component. Is preferably performed.

Preferably, the convex ink guide has a slit-like groove formed at a substantially central position. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 is a plan view showing a configuration of a line scanning type ink jet head according to an embodiment of the present invention.

In this embodiment, as shown in FIG. 1, this line scanning type ink jet head has a plurality of through holes 14.
Are provided in a predetermined arrangement, the control electrode 15 provided on the surface of the insulating substrate 13 around the through-hole 14, and the convex portion protrudes from under the insulating substrate 13 in the flying direction of the ink through the through-hole 14. Ink guide 50. The ink is stored in an ink tank 58 (not shown) below the insulating substrate 13, and the ink guide 50 is immersed in the ink chamber 58. The ink is
The ink is supplied from the ink chamber 58 to the ink droplet flying position 54 of the ink guide 50 by wetting or surface tension.

FIG. 2 is a sectional view taken along the line AA 'of FIG. FIG. 3 is an enlarged view of the ink flying portion. As shown in FIGS. 2 and 3, the ink flying portion 25 includes the control electrode substrate 12 and the convex ink guide 50. The control electrode substrate 12 and the convex ink guide 50 are supported on the head block 40 by a predetermined method. In the figure, the ink 9 is, for example, a colloidal dispersion of a positively charged coloring material component in an insulating solvent having a resistivity of 10 ⁺⁸ Ωcm or more together with a charge control agent and a binder. An ink chamber 58 formed by the substrate 12 and the head block 40 is supplied and filled from an ink supply system (not shown).

The control electrode substrate 12 includes a plurality of control electrodes 1.
5, an insulating substrate 13 having a through-hole 14 formed corresponding to the control electrode 15, a control electrode 15 formed on the surface of the insulating substrate 13 around the through-hole 14, and further on the control electrode 15. And the formed insulating protective layer 16. The inner diameter of the control electrode 15 is provided with substantially the same size as the diameter of the through hole 14. Further, the insulating substrate 13 is made of, for example, polyimide having a thickness of about 25 μm, the electrostatic electrode 15 is made of, for example, copper plating having a thickness of about 18 μm, and the inner diameter of the through hole 14 is, for example, 150 to 300 μm.
It is about mΦ. The insulating protective film 16 is, for example, 1 to 10 μm.
It may be formed by coating or depositing a resin such as polyimide or polyparaxylene with a thickness of about m, or depositing SiO ₂ or the like.

The convex ink guides 50 are made of, for example, an insulating member such as plastic resin or ceramics, and are arranged at the same row interval and pitch so that the center of each ink guide 50 and the center of the through hole 14 are equal. I have. Each convex ink guide 50 has, for example, a triangular or trapezoidal shape at the tip of a flat plate having a constant thickness, and has a width of 30 to 6 at the center.
It has a shape in which a slit 54 of about 0 μm is formed, and its tip can be an ink droplet flying position 59.

In opposition to the tip of the convex ink guide 50,
A recording medium 21 which is a recording paper is provided.
A counter electrode 22 also serving as a platen for guiding the recording medium 21 is disposed on the back surface of the recording medium 21.

Next, the recording operation of the above-described ink jet recording apparatus will be described with reference to FIGS. At the time of recording, the ink 9 filled in the ink chamber 58 shown in FIG.
Is supplied from the through hole 14 to the ink flying position 59 at the tip of the convex ink guide 50. Here, a voltage of, for example, DC 1.5 kV is always applied as a bias from the bias voltage source 6 to the control electrode 15, and a signal voltage corresponding to an image signal from the signal voltage source 7 is, for example, 500 V when turned on. A pulse voltage is superimposed. On the other hand, the counter electrode 22 provided on the back surface of the recording medium 21 is set to the ground potential 0 V as shown in FIG.

Here, the control electrode 15 is in the ON state (500
V is applied), and bias DC 1.5 kV
When a total voltage of 2 kV, on which a pulse voltage of 500 V is superimposed, is applied, the ink droplet 5 centering on the color material component jumps out of the ink droplet flying position 59 at the tip of the convex ink guide 50 and is pulled by the counter electrode 22. Thus, the image flies toward the recording medium 21 to form an image.

In this case, since the flow path of the ink 9 is determined, the ink droplet flying position 59 is determined at a substantially central position of the convex ink guide 50. At the time of flying, the color material component is changed in the main scanning direction by applying a voltage. Never escape. Also,
As shown in the present embodiment, the surface of the convex ink guide 50 that conveys the liquid ink into the independent through-hole 14 and the control electrode provided around the same, and protrudes substantially perpendicularly from the through-hole 14, The ink is supplied to the slit 54 formed at the center of the convex ink guide 50 by wetting or surface tension, whereby the ink 9 reaches the ink droplet flying position 59, so that the ink 9 is formed at the ink droplet flying position 59. The size and position of the meniscus are stably maintained without being affected by the state of the ink supply system such as pressure, the atmospheric pressure, and the effects of mechanical vibration. Therefore, the flying of the ink droplets 5 is stabilized, and a good image with a stable density can be recorded on the recording medium 21.

[0030]

As described above, according to the ink jet recording apparatus of the present invention, ink is supplied to each of the convex ink guides in a manner corresponding to the image point, and there is no clogging at the nozzles. Since the ink droplet flight position and the meniscus at the ink droplet flight position are determined uniformly, the ink droplet flight is stabilized without being affected by the ink pressure, atmospheric pressure, mechanical vibration, and adjacent dots, High-quality recording with stable density can be performed.

Further, by providing an insulating protective layer on the surface of the control electrode, even if highly conductive ink is used or conductive dust adheres to the control electrode, the control electrode is not electrically connected to the control electrode. And an ink jet recording apparatus with high performance can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of a line scanning type ink jet head according to an embodiment of the present invention.

FIG. 2 is an enlarged view of an ink flying portion corresponding to one dot;

FIG. 3 is an enlarged view of an ink flying section in FIG. 2;

[Description of sign]

 DESCRIPTION OF SYMBOLS 5 ... Ink drop 6 ... Bias voltage source 7 ... Signal voltage source 9 ... Ink 12 ... Control electrode substrate 13 ... Insulating substrate 14 ... Through hole 15 ... Control electrode 16 ... Insulating protective layer 21 ... Recording medium 22 ... Counter electrode 25 ... Ink flying section 40 ... Head block 50 ... Ink guide 54 ... Slit 58 ... Ink chamber 59 ... Ink drop flying position

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Hosaka 1 Ritsumeikan Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Hideyuki Nakao Toshiba-cho, Komukai-shi, Kawasaki-shi, Kanagawa No. 1 Toshiba R & D Center Co., Ltd. (72) Koichi Ishii, Inventor Koichi Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center Co., Ltd. (72) Kazuhiko Higuchi Komukai, Sachi-ku, Kawasaki-shi, Kanagawa No. 1, Toshiba Town Inside the Research and Development Center, Toshiba Corporation (56) References JP-A-9-314867 (JP, A) JP-A-2-29,4949 (JP, A) (58) Fields studied (Int. Cl. ⁷⁾ , DB name) B41J 2/06 B41J 2/385

Claims (3)

(57) [Claims] An ink jet recording apparatus which performs recording by applying an electrostatic force to an ink in which a coloring material component is dispersed in a solvent to fly at least an ink droplet containing the coloring material component toward a recording medium. An insulating substrate having a plurality of arranged through holes, a plurality of control electrodes formed around the through holes on the surface of the insulating substrate for applying the electrostatic force, and formed at least on the control electrodes; A control electrode substrate having an insulating protective layer formed thereon, a convex ink guide disposed substantially at the center of the through-hole, and protruding in the direction of ink droplet flight, and forming the ink into the convex ink guide through the through-hole. And an ink supply unit for supplying the ink. 2. The recording material according to claim 1, wherein the color material component has a positive or negative charge property, and an electrostatic force having the same polarity as that of the color material component is applied to cause the ink droplet to fly toward a recording medium to perform recording. The ink jet recording apparatus according to claim 1, wherein: 3. The ink jet recording apparatus according to claim 1, wherein the convex ink guide has a slit-like groove formed at a substantially central position.