JP3433020B2 - 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 device, and particularly to a liquid ink in which a colorant is dispersed in a solvent, and at least a colorant component contained in the ink is ejected as an ink droplet onto a recording medium. The present invention relates to an inkjet recording device that records characters and images.

[0002]

2. Description of the Related Art A recording apparatus for recording an image by forming a recording dot by spraying a liquid ink as a minute droplet called an ink droplet on a recording medium has been put into practical use as an inkjet printer. This inkjet printer has less noise than a mechanical recording device such as a wire dot printer, and does not require processing such as development and fixing compared to an electrophotographic recording device such as the Carlson method. It has attracted attention as a plain paper recording technology.

Various types of ink jet printers have been proposed up to the present, and a typical method thereof is as follows: (a) Ink droplets are ejected and fly by the pressure of vapor generated by the heat of a heating element. Electric / heat conversion method (see, for example, Japanese Patent Publication No. 56-9429 and Japanese Patent Publication No. 61-59911), and (b) Piezoelectric system that ejects ink droplets by mechanical pressure pulse generated by a piezoelectric element. (Japanese Patent Publication Sho 53-1
2138), etc.

A recording head (hereinafter, referred to as an inkjet head) used in an inkjet printer is mounted on a carriage and is orthogonal to a conveyance direction (hereinafter, referred to as a sub-scanning direction) of a recording paper (hereinafter, referred to as a main scanning direction). A serial scanning type head that performs recording while moving in the scanning direction) has been put to practical use. This serial scanning type head cannot perform recording unless it moves by a predetermined amount in the main scanning direction, so it is difficult to increase the recording speed. Therefore, a line scanning printer in which the recording speed is increased by using a long head in which the length of the recording head is set to be substantially the same as the width of the recording paper is also considered. Practical application is not easy due to the following reasons.

In the ink jet recording system, a large number of individual fine nozzles corresponding to the resolution are provided, but in essence, local evaporation of the solvent tends to cause local ink concentration, which causes clogging of the nozzles. It is the cause. Further, in the method using the pressure of steam for forming an inkjet, adhesion of an insoluble substance formed by thermally or chemically reacting with the ink induces clogging of the nozzle, and pressure by a piezoelectric element is used. In the system, a complicated structure such as an ink flow path makes it easier to induce nozzle clogging. Even a serial scanning head that uses several tens to hundreds of nozzles may cause nozzle clogging, but a line scanning head that uses many thousands of nozzles. In
It has been probabilistically proved that the nozzles are clogged with a higher occurrence frequency, which has a problem of lacking practical reliability.

Further, in the method using the pressure of vapor, it is difficult to generate ink particles having a diameter of 20 μm or less, which corresponds to a recording dot having a diameter of about 50 μm on the recording paper, and therefore, a head having a high resolution is obtained. Is difficult to manufacture. Further, in the method using the pressure by the piezoelectric element, it is difficult to manufacture a head having a high resolution due to a problem in processing technology because the structure of the recording head is complicated. Therefore, the conventional inkjet apparatus has a problem that it is difficult to improve the resolution regardless of which method is used.

In order to solve these problems, a voltage is applied to an electrode array formed by arranging a plurality of individual electrodes formed of a thin film on a substrate, and electrostatic force is used to eject ink from the ink surface. An inkjet recording device has been proposed in which the colorant component therein is ejected as ink droplets.

Specifically, a method of ejecting ink droplets by using electrostatic attraction (Japanese Patent Laid-Open Nos. 49-62024 and 56-56).
4467, etc.), and a method of increasing the concentration of a colorant by using ink containing a charged colorant component to fly ink droplets (see Japanese Patent Publication No. 7-502218). In these systems, the structure of the recording head is a slit nozzle structure that does not require a nozzle for each individual dot,
Alternatively, since it has a nozzleless structure that does not require a partition of an ink flow path for each individual dot, it is effective in preventing and recovering from clogging, which was a major obstacle in realizing a line scanning recording head. Further, in the latter method of increasing the colorant concentration, it is possible to stably generate and fly ink droplets having a very small particle diameter, which is also suitable for high resolution.

[0009]

However, in the ink jet recording apparatus of the type in which the colorant component is ejected as ink particles by the electrostatic force described above, the recording head is nozzleless, so that it is effective for preventing clogging. The problem is that the ink droplet ejection position becomes unstable because the ink can move freely in the main scanning direction on the substrate of the recording head.

Further, since the ink droplets are ejected by the voltage having the same polarity as the colorant charging polarity and are made to fly to the recording medium, the colorant component repels and escapes from the electrode position on the recording head. There is also a problem that the components cannot be stably supplied to the ink droplet ejection position. Therefore, it is difficult to stably eject a sufficient amount of ink droplets from a predetermined ejection point, and there is a problem that characters and images cannot be satisfactorily recorded on a recording medium.

According to the present invention, the colorant component contained in the ink can be stably supplied to the leading edge of the individual electrode, which is the ink droplet ejection position, whereby the ink droplet can be ejected and ejected stably without clogging. It is an object of the present invention to provide an ink jet recording device that can be made.

[0012]

In order to solve the above-mentioned problems, an ink jet recording apparatus according to the present invention applies at least the coloring agent component by applying an electrostatic force to ink in which the coloring agent component is dispersed in a solvent. in the ink jet recording apparatus for recording on a recording medium by flying toward the ink droplets recording medium comprising, and one end surface opposed to the recording medium, parallel grooves a plurality of leading to the end face and intersects the end face drilling comprising a set has been on one side of the plane, the head substrate having at least a, each electrode layer formed along the inner surface of the parallel grooves of said plurality of which is Ho設to the head substrate, wherein in said ink A plurality of individual electrodes arranged to apply an electrostatic force to the colorant component and receding from the end face
Is provided so as to open the end face side of the plane,
Ink supply means for supplying the ink to an ink ejection position where the individual electrodes on the end surface side of the head substrate are arranged is provided.

As described above, in the ink jet recording apparatus according to the present invention, the ink supplied to the plurality of parallel grooves by the ink supply means reaches the ink flying position on the end surface of the head substrate due to the surface tension, and reaches the ink flying position. At least the coloring material in the ink flies and adheres to the surface of the recording medium by the electrostatic force generated by the voltage applied to each of the provided individual electrodes. As a result, an ink thin layer having a stable thickness is formed at the ink droplet flying position without receiving the pressure of the ink supplied onto the head substrate by the ink supply means, and the ink does not move in the main scanning direction. The flight position can be stabilized. Further, in the ink jet recording apparatus according to the present invention, it is possible to eject minute ink droplets from the electrode having a large opening, and therefore, it is possible to use a nozzle in comparison with an ink jet recording apparatus using a conventional individual electrode and an individual nozzle. No more clogging.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an ink jet recording apparatus according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a view showing the schematic arrangement of an inkjet recording apparatus according to the first embodiment of the present invention. In FIG. 1, an inkjet recording apparatus includes a platen 2 on which a recording medium 1 is mounted and which is set to a ground potential.
The line scanning type inkjet head 10 is provided so as to face the recording surface of the recording medium 1. The head 10 includes a head block 11 provided with an ink supply mechanism 20, a head substrate 12 embedded in the head block 11, and a head substrate 1 facing the recording medium 1.
2, a plurality of concave parallel grooves 13 formed in parallel in a direction orthogonal to the line scanning direction, an electrode layer 14 formed along the inner surface of each parallel groove 13, and the tip of the head block 11. And a solvent recovery mechanism 30 for recovering the solvent component of the ink in which the colorant component is diluted by using the inclined surface 11a.

Of the head 10, particularly the head block 11
The detailed configuration of the above is shown in the perspective view of FIG. In FIG. 2, a slit-shaped nozzle 15 having a predetermined gap is provided on the side of the head substrate 12 on which the parallel groove 13 is formed, and the nozzle 15 has an ink supply channel 21 of the ink supply mechanism 20. Ink that overflows from the parallel grooves 13 and the nozzles 15 that communicate with each other and that are provided in parallel are collected via an ink recovery channel 22.

The ink supply mechanism 20 will be described with reference to FIG. 1 again. The ink supply mechanism includes an ink supply passage 21, a nozzle 15, and an ink recovery passage 22.
And the recirculation tank 2 for temporarily storing the collected ink
3 and three. The ink 5 supplied to the nozzles 15 by the ink supply mechanism 20 including the reflux tank 23 contains a colorant component and a solvent component, and the inside of the ink supply mechanism 20 having the above-described structure is driven by an ink circulation pump (not shown). And the nozzle 1
5, the ink 6 infiltrates to the recording medium 1 side along the inner surface of each parallel groove 13 by the surface tension, and the ink 6 having a larger color material component than the ink flight point 16 of the head substrate 12 is ejected / flyed to the recording medium 1 side. It is something. The ink supply nozzle 15 is opened at a position retracted from the front end surface 12a of the head substrate 12.

The solvent recovery mechanism 30 has a slit-shaped opening 11b for dropping the solvent, which is guided by the inclined surface 11a inclined toward the tip side of the head 11, a recovery passage 31 communicating with the slit-shaped opening 11b, and the recovered solvent. A solvent tank 32 for storing,
Ink 7 containing a large amount of a solvent component that does not fly from the flight point 16 and does not contribute to recording is recovered.

The relationship between the head substrate 12, the parallel groove 13 and the electrode layer 14 will be described with reference to FIG. In the first embodiment, the parallel groove 13 has a sampling trapezoidal cross section.
The electrode layer 14 is formed so as to follow the inner surface shape of the above, and a large number of individual electrodes 17 are provided for each parallel groove 13 by such a configuration. As shown in FIG. 1, a bias voltage source 3 constantly applies, for example, a DC voltage of 1.5 kV to these individual electrodes 17, as a bias.
A pulse voltage of, for example, 500 V is superimposed on this bias as a signal voltage corresponding to the image signal from the signal voltage source 4. The counter electrode, which also serves as the platen 2, is set to the ground potential 0V as shown in the figure.

Next, the ink ejection operation of the ink jet recording apparatus based on the above construction will be described. At the time of recording, the ink 5 supplied from the ink circulation tank 23 to the slit-shaped nozzle 15 via the ink supply flow path 21 by a pump (not shown in FIG. 1) is guided by the parallel groove 13 and the inner surface of the parallel groove 13 due to surface tension. Is supplied to the ink flying position 16 up to the end surface of the head substrate 12, and a part of the ink is recovered in the reflux tank 23 via the ink recovery channel 22. The ink supplied through the ink supply nozzle 15 rises on the inner surface of each of the parallel grooves 13 formed in a concave shape by surface tension and is supplied to the ink flying position 16 on the end surface side of the electrode layer 14. It
As described above, at the time of recording, the ink 5 containing the coloring agent is always supplied to the ink flying position 16 of each individual electrode 17 by the ink supply mechanism 20.

The operation when the ink droplets of the ink 6 containing a sufficient amount of colorant are ejected and ejected toward the recording medium from the ink ejecting position 16 will be described. The bias voltage source 3 constantly applies a bias voltage to all of the individual electrodes 17, and when any one of a large number of individual electrodes 17 provided for recording is turned on, a bias voltage of 1.5 kV is applied. A pulse voltage of 500 V is superimposed and a total voltage of 2 kV is applied. As a result, the arbitrary individual electrode 17 which is turned on causes the ink supplied to the ink flying position 16 on the tip side thereof to be ejected and fly toward the recording medium 1, and the ejected ink contains a coloring agent. The ink droplets 6 adhere to the recording medium 1. At this time, the counter electrode, which also serves as the platen 2, is at the ground level of 0 V, so that the ink droplet 6 is electrically attracted.

The ink that has not contributed to recording because it has not been ejected as the ink droplet 6 from the ink droplet flying position 16, that is, the ink in which the concentration of the colorant component has decreased and the amount of the solvent component has increased, is the inclined surface of the head block 11. It is guided from 11a to the opening of the solvent recovery channel 31 and is recovered in the solvent tank 32 of the solvent recovery mechanism 30.

As described above, in the ink jet recording apparatus according to the first embodiment, the individual electrode 17 is formed by the electrode layer 14 formed along the inner surface of the concave parallel groove 13, so that the ink 5 has a surface. The tension causes the inside of the parallel groove 13 to be supplied to the ink droplet flying position 16 in a thin film state defined by the depth of the concave groove, and the ink droplet 6 is jetted from the thin ink layer toward the recording medium 1.

By doing so, the flow path of the ink 5 is stabilized, so that the tip surface 12a of the head substrate 12 is formed.
The ink droplet flying position 16 can be aligned with the substantially central position of each of the plurality of concave parallel grooves 13, and the coloring agent component contained in the ink in the main scanning direction due to the impact of the application of the pulse voltage at the time of flying. I won't run away. Moreover, the thickness of the ink thin film formed at the ink droplet flying position 16 is not affected by the pressure of the ink 5 supplied on the head substrate 12 or the atmospheric pressure, and can be stably set to a certain minute value. Will be maintained. Therefore, the flight of the ink droplets 6 is also stabilized, and a good image with stable density can be recorded on the recording medium 1.

Further, according to the first embodiment, since the ink is carried to the ink flying position 16 by the surface tension inside the concave parallel groove, the tip surface 12a of the head substrate 12 is caused by the action of gravity or vibration. It is possible to prevent the ink from spilling out.

Although the ink jet recording apparatus according to the first embodiment has been described as having the electrode layer 14 formed on the entire inner surface of the parallel groove 13, the present invention is not limited to such a constitution of the present invention. It may be configured as shown in FIG. FIG. 4 is a perspective view showing a main part of an ink jet recording apparatus according to a second embodiment of the present invention. In FIG. 4, a concave parallel groove 13 formed on a head substrate 12 is shown.
A non-electrode region 25 where no electrode layer is formed is provided in the center of the groove bottom of the electrode layer 14 formed along the inner surface of the electrode.

With this configuration, the charged coloring material in the ink has the same polarity as the polarity of the voltage applied to the bias voltage source and the signal voltage source, and the coloring material has a concave parallel groove 13 due to electrostatic force. The flight position 16 can be set more accurately by moving to the center of. Therefore, the ink flying position 16 is substantially in the center of the non-electrode area 25, and it is possible to eject and fly the ink toward the recording medium in a more reliable and stable state.

Although the parallel groove 13 has been described as a concave groove having a notched trapezoidal cross section, the present invention is not limited to such a configuration, and the third and third grooves shown in FIGS. As shown in the fourth embodiment, it may be formed to have various cutout shapes in cross section.

FIG. 5 is a perspective view of an essential part showing an ink jet recording apparatus according to a third embodiment of the present invention. In FIG. 5, the cross-sectional shape formed parallel to one surface of the head substrate 12 is rectangular. The parallel groove 26 is cut out in the rectangular parallel groove 26, and the electrode layer 14 having a U-shaped cross section is formed along the inner surface of the rectangular parallel groove 26. Each individual electrode 27 is formed by the rectangular parallelepiped groove 26 and the U-shaped electrode layer 14.

FIG. 6 is a perspective view of an essential part of an ink jet recording apparatus according to a fourth embodiment of the present invention. In FIG. 6, one side of the head substrate 12 is cut out in a V-shaped cross section. A plurality of parallel grooves 28 are formed.
The electrode layer 14 is formed along the cutout surface of the V-shaped parallel groove 28. The ink flying position 16 is located at the bottom of the V-shaped notch of the parallel groove 28. The parallel groove 28 and the electrode layer 14 form an individual electrode 29.

In each of the ink jet recording apparatuses according to the first to fourth embodiments, the tip surface 12a of the head substrate 12 and the end surface of the electrode layer 14 of the individual electrode are formed at the same level. However, the present invention is not limited to this, and the tip end surface of the electrode layer 14 is made to protrude from the tip end surface 12a of the head substrate 12 so that the ink flying position 1
6 may be arranged closer to the recording medium 1 side. 7 to 10 are perspective views showing the ink jet recording apparatuses according to the fifth to eighth embodiments, respectively, in which the electrode layer having the tip end surface protruding is attached to the parallel groove having the shape corresponding to FIGS. 3 to 6. .

In the ink jet recording apparatus according to the fifth embodiment shown in FIG. 7, the leading end surface is the end surface of the head substrate 12 on the inner surface of the trapezoidal notch-shaped concave parallel groove 13 corresponding to the first embodiment. An electrode layer 14A protruding from the recording medium side of 12a is formed. With such a configuration, the ink supplied to the ink flying position 16 is transferred to the head substrate 12
Good recording can be performed without contaminating the end face 12a of the.

An ink jet recording apparatus according to the sixth embodiment shown in FIG. 8 has a trapezoidal notch-shaped concave parallel groove 13 corresponding to the second embodiment and an inner surface of the parallel groove 13. The non-electrode portion 25 is formed in the central portion of the shaped electrode layer, and the electrode layer 14A protruding from the end surface 12a of the head substrate 12 toward the recording medium is provided. With such a configuration, ink can be ejected after being concentrated on the non-electrode portion 25, and good recording can be performed without contaminating the end surface 12a of the head substrate 12.

Next, in the ink jet recording apparatus according to the seventh embodiment shown in FIG. 9, a rectangular notch 26 corresponding to the third embodiment and an inner surface of the notch 26 are provided. An electrode layer 1 in which an electrode layer having a U-shaped cross section formed in such a shape is projected from the end surface 12a of the head substrate 12
4A, and the individual electrode 27A is composed of the electrode layer 14A protruding above the end surface 12 toward the recording medium. With such a configuration, it is possible to prevent the end surface 12a from being contaminated by the ink spilled from the ink flying position, as in the fifth and sixth embodiments.

Finally, the ink jet recording apparatus according to the eighth embodiment shown in FIG. 10 corresponds to the fourth embodiment shown in FIG. 6 and has a V-shaped cross section.
Has a V-shape corresponding to the inner surface of the V-shaped parallel groove 28, and the end surface of the V-shaped parallel groove 28 is the end surface 1 of the head substrate 12.
It has an individual electrode 29A provided with an electrode layer 14A projecting from 2a. The ink jet recording apparatus according to the eighth embodiment configured as described above also provides
In addition, similar to the ink jet recording apparatus according to the seventh embodiment, good recording can be performed without contaminating the end surface 12a of the head substrate 12.

[0035]

As described above, according to the ink jet recording apparatus of the present invention, the individual electrodes for applying the electrostatic force to the coloring material component in the ink are dug parallel to one surface of the head substrate. It is composed of an electrode layer formed on the end surface side of the head substrate along the inner surfaces of the plurality of parallel grooves, and carries the ink droplets to be ejected by surface tension along the inner surfaces of the parallel grooves to the flying position, to the recording medium. Since the ink droplets are made to fly, there is no clogging at the nozzle as in the case of using individual nozzles, and the amount of thin ink layer before forming the ink droplets to be made to fly by the inner surface of the parallel groove Since it can be adjusted, the flight of ink droplets can be stabilized without being affected by the ink pressure or atmospheric pressure, and high-quality recording with stable ink density can be performed.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing the overall configuration of an inkjet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a main part showing details of the inkjet recording apparatus according to the first embodiment shown in FIG.

FIG. 3 is a perspective view showing individual electrodes on an end surface of a head substrate in the inkjet recording apparatus according to the first embodiment.

FIG. 4 is a perspective view showing individual electrodes in an ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing individual electrodes in an ink jet recording apparatus according to a third embodiment of the present invention.

FIG. 6 is a perspective view showing individual electrodes in an inkjet recording apparatus according to a fourth embodiment of the present invention.

FIG. 7 is a perspective view showing individual electrodes in an ink jet recording apparatus according to a fifth embodiment of the present invention.

FIG. 8 is a perspective view showing individual electrodes in an inkjet recording apparatus according to a sixth embodiment of the present invention.

FIG. 9 is a perspective view showing an individual electrode in an inkjet recording device according to a seventh embodiment of the present invention.

FIG. 10 is a perspective view showing individual electrodes in an ink jet recording apparatus according to an eighth embodiment of the invention.

[Explanation of symbols]

1 recording medium 2 Platen (counter electrode) 11 head blocks 12 head substrate 12a end face 13, 26, 28 Parallel groove 14, 14A electrode layer 16 Ink flight position 17, 17A, 27, 27A, 29, 29A Individual electrodes 20 Ink supply means (mechanism)

─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideyuki Nakao Inventor Hideyuki Nakao 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center Co., Ltd. Muko Toshiba Town 1 Co., Ltd. Toshiba Research and Development Center (72) Inventor Yasushi Hosaka Komukai Toshiba Town, Kawasaki City, Kanagawa 1 Komatsu Toshiba Research and Development Center (56) Reference JP-A-5-116321 ( JP, A) JP 8-72248 (JP, A) JP 58-124662 (JP, A) JP 9-57977 (JP, A) JP 9-57979 (JP, A) JP Flat 9-201970 (JP, A) JP-A-56-58878 (JP, A) Special table Flat 7-502218 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B41J 2 / 06 B41J 2/175

Claims (5)

(57) [Claims] 1. An ink jet for performing recording on a recording medium by causing an ink droplet containing at least the colorant component to fly toward the recording medium by applying an electrostatic force to ink in which the colorant component is dispersed in a solvent. In the recording apparatus, one end face facing the recording medium and the end face intersecting with the end face .
A head substrate having at least one flat surface in which a plurality of parallel grooves are dug up to the end face , and formed along the inner surface of each of the plurality of parallel grooves dug in the head substrate. A plurality of individual electrodes arranged to apply an electrostatic force to the colorant component in the ink, and withdrawing from the end face to open the end face side of the plane.
Provided to an ink jet recording apparatus characterized by comprising an ink supply means for supplying the ink to said ink ejection position the individual electrodes are arranged in the end face side of the head substrate. 2. The ink jet recording apparatus according to claim 1, wherein the horizontal groove dug parallel to the head substrate is a concave groove having a concave sectional shape. . 3. The individual electrodes formed in each of the parallel grooves of the head substrate to which the ink is supplied by the ink supply means are formed on the end face side of the head substrate and on the center side of the electrode layer. The inkjet recording apparatus according to claim 2, further comprising: a non-electrode region that is formed. 4. The ink jet recording apparatus according to claim 1, wherein the electrode layer of the individual electrode is formed so as to protrude from the end surface of the head substrate toward the recording medium by a predetermined amount. Wherein said flat <br/> Gyomizo which is Ho設parallel to the head substrate, according to claim 1, characterized in that the V-shaped groove cross section becomes V-shaped Inkjet recording device.