JP3340379B2 - 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 for performing recording by flying ink droplets, and more particularly to a type in which an electrostatic force is generated by an individual electrode provided on a recording head to discharge ink droplets. Related to an ink jet recording apparatus.

[0002]

2. Description of the Related Art Ink jet recording apparatuses have the advantage that they are less noisy than recording methods of other recording methods and do not require processing such as development and fixing.

[0003] Many ink jet recording apparatuses have been devised up to the present, for example, Japanese Patent Publication No. 56-9429.
As described in JP-B-61-59911, a method of flying ink droplets by the pressure of steam generated by the heat of a heating element, for example, as described in JP-B-53-12138, A typical method is to fly an ink droplet by a mechanical pressure pulse generated by a piezoelectric element.

A head used in an ink jet recording apparatus is mounted on a carriage and performs recording while moving in a direction (hereinafter, referred to as a main scanning direction) orthogonal to a conveying direction of recording paper (hereinafter, referred to as 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, it has been considered to increase the recording speed by using a long head in which the length of the recording head is the same size as the width of the recording paper, that is, a so-called line scanning type head. However, such a line scanning type head is realized. It was not easy for the following reasons.

[0005] In the ink jet recording system, the local concentration of the ink tends to occur due to the evaporation and volatilization of the solvent, which causes clogging at individual thin nozzles corresponding to the resolution.

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

[0007] In the method using the pressure of the piezoelectric element, a complicated structure such as an ink flow path or the like is more likely to induce clogging. Line scan heads that require thousands of nozzles, even more than serial scan heads that use tens to hundreds of tens of nozzles, have a high probability of clogging and have a high probability of clogging. It is a big problem in terms of gender.

Further, there is a problem that the conventional ink jet recording apparatus is not suitable for improving the resolution. That is, it is difficult to generate ink particles having a diameter of 20 μm or less (this corresponds to recording dots having a diameter of about 50 μm on recording paper) by the method using the pressure of steam.

Also, in the method using the pressure generated by the piezoelectric element, the recording head has a complicated structure, and it is difficult to produce a high-resolution head due to a problem in processing technology.
To overcome these drawbacks, a voltage is applied to an electrode array in which a plurality of control electrodes made of a thin film are arranged on a substrate,
An ink jet recording system has been devised in which an ink or a color material component in the ink is caused to fly as an ink droplet from an ink liquid surface using electrostatic force. For example, JP-A-49-6202
No. 4, and JP-A-56-4467, a method of flying ink droplets using electrostatic attraction, for example,
O93 / 11866, PCT / AU92 / 00665,
As described in Japanese Patent Application Laid-Open No. 7-502218, a method has been devised in which an ink containing a charged coloring material component is used to increase the concentration of the coloring material to fly ink droplets. In these systems, the recording head configuration is a slit-shaped nozzle configuration that does not require a nozzle for each individual dot,
Alternatively, the nozzle-less configuration that does not require the partition of the ink flow path for each individual dot is effective for preventing and recovering from clogging, which has been a major obstacle in realizing a line scanning recording head. The latter is also suitable for high resolution because it can stably generate and fly ink droplets having a very small diameter.

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, the recording head is nozzleless, which is effective in preventing clogging. 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 to the recording medium, the coloring material component repels and escapes from the electrode position on the recording head, and the coloring material component is repelled. Has not been able to be stably supplied to the ink droplet ejection position. Therefore, it is difficult to eject a sufficient amount of ink droplets from a predetermined ejection point in a stable manner and fly, and characters and images cannot be recorded well on a recording medium.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a color material component in ink is stably supplied to an ink droplet ejection position, and the ink droplet ejection position is stable so that the ink droplet is not clogged. An object of the present invention is to provide an ink jet recording apparatus capable of stably ejecting and flying.

[0013]

SUMMARY OF THE INVENTION An ink jet recording apparatus according to the present invention applies an electrostatic force to an ink in which a coloring material component is dispersed in a solvent, and directs an ink droplet containing at least the coloring material component to a recording medium. A multi-layer insulating substrate having a plurality of arranged through holes, formed around the through holes on the surface of the multi-layer insulating substrate, for applying the electrostatic force. A plurality of control electrodes, and a control electrode substrate which is respectively drawn out from the control electrode and has a lead wire led between layers of the multilayer insulating substrate through a through hole, and is arranged at a substantially central position of the through hole; A convex ink guide protruding in an ink droplet flight direction; and an ink supply means for supplying the ink to the convex ink guide through the through hole. .

In the ink jet recording apparatus of 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. A multi-layer insulating substrate having a plurality of arranged through-holes, a plurality of control electrodes formed around the through-holes on the surface of the multi-layer insulating substrate, and for applying the electrostatic force. And a control electrode substrate having a lead line which is respectively drawn out from the control electrode, and is separately led to any one of the layers of the multilayer insulating substrate via the through hole or the surface of the multilayer insulating substrate; and A convex ink guide that is disposed at a substantially central position of the through hole and protrudes in the ink droplet flying direction; and a b that supplies the ink to the convex ink guide through the through hole. Providing an ink jet recording apparatus characterized by comprising a click supplying means.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet recording apparatus according to the present invention has an insulating substrate having a plurality of arranged through holes, and a plurality of controls formed around the through holes on the surface of the insulating substrate to apply an electrostatic force. A control electrode substrate having a lead line drawn out from each of the electrode and the control electrode and led between the layers of the multilayer insulating substrate through a through hole; and a control electrode substrate disposed at a substantially central position of the through hole and protruding in an ink droplet flying direction. And a supply unit for supplying ink to the convex ink guide through the through hole.

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

Preferably, the convex ink guide has a slit-like groove formed at a substantially central position. According to the present invention, the ink has a configuration in which a plurality of through-holes forming an ink protruding portion and a convex ink guide protruding from the through-hole in the ink droplet flying direction are provided corresponding to the image points. Are supplied to the ink droplet flying position of each convex ink guide after being separated in accordance with the image point. 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.

Further, in the present invention, a multilayer substrate is used as an insulating substrate, and lead lines respectively drawn from the control electrodes are led between the layers of the multilayer substrate through through holes to lead to a wider area without the control electrodes. Forming a line. This is because when lead lines are provided on the surface of an insulating substrate, it must be set so as to lead a plurality of lead lines through a narrow interval between control electrodes formed on this surface. This is because there is a limit and it is difficult to increase the resolution.

This will be described below with reference to the drawings.
FIG. 1 is a schematic diagram showing a structure of a main part of a head of an ink jet recording apparatus provided with a lead line on the surface of an insulating substrate,
FIG. 2 shows a perspective view of the surface region.

As shown in FIG. 1, an insulating substrate 11 having a through hole 10 is provided on one surface of an ink tank 17 filled with ink 16. As shown in FIGS. 1 and 2, a protruding ink guide 13 having a slit 12 formed in the middle is inserted into the center of the through hole 10. Control electrodes 14 are formed around the through holes 10, and lead lines 15 for individually applying a voltage to each control electrode 14 are formed. The ink guides 13 are made of, for example, an insulating resin such as polyimide or ceramics, and are formed in a line at the same pitch as the through-holes 10 formed in the insulating substrate 11. It has a standing structure. When a recording voltage is applied to the control electrode 14 from which ink is ejected by the head having such a structure, the ink that has passed through the slit 12 of the ink guide 13 is removed from the control electrode 1.
An image can be formed on the recording medium 21 which is protruded by the electric field between the counter electrode 4 and the opposing electrode 20 and is opposed to the recording medium 21. The presence of the protrusions of the ink guide 13 stabilizes the ink ejection point, so that a clear and stable image can be recorded. Further, since the ink rises in the slit 12 by the capillary force, the ink can be stably supplied to the ejection point.

However, the inkjet head of the type shown in FIG. 1 cannot produce a high-resolution recording head. At present, 720 dp in other ink jet recording systems
A head having a resolution of about i has also been manufactured. However, in this method, the size of the through hole 10 is about 200 μm, and further, the larger control electrode 14 is connected to the through hole 10.
, The resolution of a head that can be formed in one line is limited to about 50 dots / inch. If the 50 dpi head is arranged obliquely, high resolution can be realized without limit. However, the size of the head becomes very large. For example, when the head of 50 dpi is placed diagonally and 800 dpi is set, 210 mm
Theoretically, to record the A4 width of about 3.3
This requires a head with a width of m, which is not practical.

One method of avoiding this is to hold the recording paper in the form of a drum and record it with a 50 dpi head while moving the drum in a horizontal direction with respect to the head by 800 dpi in one revolution and rotating it 16 times. 800d
The pi image is recorded. The resolution can be increased by such a method. In this case, however, compared to the case where a high-resolution head having a recording speed of 800 dpi is used, the resolution is 1/16.
Until late.

Further, as another method for avoiding such a problem, there is a method in which a large number of ink discharge units are arranged in a plane instead of a single line. Since the ink discharge units are arranged in a staggered manner on a plane, the resolution should be theoretically high. However, when the head is actually designed and viewed, the number of lead lines of the control electrode 10 becomes large, and many lead lines must be formed in a narrow portion between the control electrodes. turn into. As a result, even in the method of arranging the ink ejection portions on a plane, the practically still 5
The limit is about 0 dots / inch, and a higher resolution head cannot be manufactured any more.

On the other hand, in the present invention, a multi-layer substrate is used as an insulating substrate, and the lead lines respectively drawn from the control electrodes are guided between the layers of the multi-layer substrate through through holes, so that a large area without control electrodes is provided. A lead line can be formed in the region. This makes it possible to further narrow the pitch of the through holes of the ink ejection section, and to obtain a high-resolution inkjet apparatus.

Further, according to the present invention, it is possible to guide the lead lines separately on the surface of the insulating substrate or between the layers of the multilayer insulating substrate. As a result, the respective lead lines are overlapped in the depth direction without conducting, and the pitch of the through holes of the ink discharge unit can be further reduced, so that a higher resolution inkjet device can be obtained.

FIG. 3 is a schematic sectional view showing the structure of the main part of the head of the ink jet recording apparatus according to the present invention, and FIG. 4 is a perspective view of the surface area of FIG. 3 and 4
1 and 2 except that the control substrate 111 has a multi-layer structure, for example, four layers, and each of the lead lines 15 ′ connected to the control electrode 14 is led separately between the layers of the multi-layer substrate. It is. Lead lines 15, 115, 125, and 135 for applying a voltage to each control electrode 14 are connected to the control electrode 14 on the surface through the through holes 18 from the surface of the multilayer insulating substrate and from each layer of the multilayer insulating substrate. ing. Specifically, the lead 15 to the first control electrode 14 is formed on the surface layer of the control substrate 111, and the lead 115 to the second control electrode 14 is
Leader line 1 formed on the layer and connected to third control electrode 14
Reference numeral 25 is formed on the third layer of the control substrate 111, and a lead 135 to the fourth control electrode 14 is formed on the fourth layer of the control substrate 111. With such a head configuration, in the example of FIG. 1 and FIG.
Although an area for forming the lead line 15 was necessary,
In the example shown in FIGS. 3 and 4, four lead lines 15,
Since 115, 125, and 135 can be overlapped in the depth direction, one wiring area is sufficient.

FIGS. 3 and 4 show an example of a single row. However, in the case of increasing the resolution, many such rows can be further arranged. With reference to FIG. 5, a case where the number of rows is large will be described. FIG. 5 is a diagram of a head in which three ink ejection units are arranged in three rows, as viewed from above the through hole 10. In this case, the ink guides 13 are arranged in three rows as indicated by dotted lines in the figure. Here, consider a case where the resolution viewed from the direction of arrow A is, for example, 200 dpi. The distance between each row is 5
By arranging them at a resolution of 0 dpi and adjusting the angle of each row, the resolution viewed from the direction of arrow A can be made 200 dpi. Since the distance between each row is equivalent to 50 dpi, about 500 μm, the hole diameter of the through hole 10 is 200 μm,
Assuming that the width of the control electrode 14 is 50 μm, the shortest part of the region where the lead 15 can be wired between the control electrodes is approximately 2 μm.
00 μm. In the ink jet recording apparatus shown in FIGS. 1 and 2, considering the most severe case, three lead lines 15 must be formed between the control electrodes 14 as shown in the figure. That is, in this portion, three lead lines 15 are formed between 200 μm, and the line / space of the lead line 15 is approximately 30 μm / 3.
0 μm. It is difficult to stably form such a wiring by a normal etching technique, and it is not suitable for practical use. Further, it is difficult to manufacture a high-resolution head.

On the other hand, in the method of the present invention, one lead line may be formed in each layer.
Since the space is also about 70 μm, it can be easily manufactured with a high yield by ordinary technology.

As described above, according to the present invention, an ink jet recording apparatus having a sufficiently high resolution can be obtained. Note that the above example is an example, and the number of protrusions of the ink guide and the number of layers of the control board are not limited to this example.
Further, in the example of FIG. 3, one lead line is formed on the surface, but there is no problem if all the lead lines are formed between layers of the multilayer substrate. In addition, an insulating film can be formed on the surface of the control electrode and the lead wire formed on the surface with a thin resin or the like. This is several hundred volts between each control electrode.
This is to prevent the occurrence of electric discharge in the part where the distance is narrow because the voltage is applied. Further, particularly when used for a long time or in a place with a lot of dust, the conductive dust adheres to the control electrode, so that the control electrode is more easily discharged. Even when conductive ink is used, discharge is likely to occur. In order to avoid these discharges, it is preferable to form an insulating layer on the electrode portion. However, if a thick insulating layer is formed, the voltage applied to the control electrode will not be sufficiently applied to the tip of the ink guide. It is preferable to attach it by about several μm by evaporation or the like.

FIG. 6 is a schematic cross-sectional view showing the arrangement of ink ejection units in another example of the ink jet recording apparatus of the present invention. In this example, a large number of control electrodes and through-holes are formed on a plane at a resolution equivalent to 50 dpi in both the main scanning and sub-scanning directions. Assuming that the direction in which the lead lines extend is the sub-scanning direction and the direction orthogonal to the sub-scanning direction is the main scanning direction, in the case of this head, scanning in the sub-scanning direction allows an image having a resolution of 400 dpi in the main scanning direction. Can be formed. In this example, 16 lines are arranged in the main scanning direction, but if this number is increased to be equal to the width of the recording paper, a line head can be configured. In the case of an A4 width line head, about 400 rows are required. When configuring such a line head, it is desirable to arrange the ink guides in the direction of the dotted line shown in FIG. This is because no matter how long the head is, eight ink guides are sufficient. This is because when the direction is as shown in FIG. 5, 400 ink guides are required when the number of ink guides is A4 width. Also, variations in the manufacture of the ink guides are absorbed and become difficult to see when the ink guides are arranged as shown in the figure.

As compared with FIG. 3 and FIG. 4, since eight rows are arranged in the sub-scanning direction, two lead lines are formed for each layer when manufacturing with a four-layered control board. Here, if the through hole is 200 μm and the control electrode is a 300 μm square, the distance between the control electrodes is the same as in the example shown in FIG.
It is about 200 μm. As shown in FIG. 6, the surface layer has a thickness of 200 μm at a position where the electrode is closest, and it is sufficient that a single lead wire passes through this. Therefore, the line / space of the lead wire is about 70 μm, which is a value that can be sufficiently manufactured. In the lead wires formed in the inner layer, two lead wires are respectively passed between the through holes. FIGS. 7, 8, and 9 show examples of wiring patterns of lead lines on the second, third, and fourth layers, respectively. On the second, third, and fourth layers,
Since no control electrode is formed, the lead line inside the multilayer insulating substrate is connected to the control electrode on the first layer through a through hole. Therefore, it is sufficient to pass two lead wires between the through holes, that is, about 300 μm. The line / space of the internal lead wire is about 60 μm, which is a value that can be dealt with by ordinary etching technology. That is, 400 dpi
Even when a head having a resolution of about the same level is manufactured, the head can be manufactured by using a multilayer substrate having four layers. Of course, if a multilayer substrate having four or more layers is used, the conditions are relaxed. However, since the length of the projections of the ink guide becomes long, it is desirable to reduce the number of layers as much as possible.

In this example, the control electrode may be circular or square. If a through hole is formed by etching or the like, a square through hole instead of a circular one can be produced. Further, in this example, eight control electrodes are wired in the first to fourth layers every two from the end, but the present invention is not limited to this. For example, the first and fifth control electrode leads from the left end are wired to the first layer, the second and sixth layers are arranged in the second layer, the third and seventh layers are arranged in the third layer, the fourth and eighth layers are similarly arranged. In the fourth layer. That is, as long as two lead lines are wired in each layer, there is no problem even if the lead line of any control electrode is wired in any layer.

FIG. 10 shows still another example of the ink jet recording apparatus of the present invention. In the examples so far, all the lead lines are extracted in only one direction, but in this example, an example in which the lead lines are extracted in both directions is shown. By forming the lead lines on both sides, the resolution of the head is further increased by a factor of two. That is, another 8 in the sub-scanning direction.
Increase the number of rows to 16 rows, and the newly increased through hole
It is arranged so as to be located between the through holes shown in FIG. 3 in the main scanning direction and at a position 1.5 times apart from the control electrode pitch in the sub scanning in the sub scanning direction.

In this manner, a head having a resolution of 800 dpi in the main scanning direction can be realized. Any number of layers can be used as long as the number of layers of the multilayer substrate is large. However, with the current technology, four layers are sufficient for the multilayer substrate, and each layer has a structure in which four lead lines are drawn out to both sides by two at a time. ing.

[0035]

As described above, when the ink jet recording apparatus of the present invention is used, the color material component in the ink is stably supplied to the leading edge of the control electrode which is the discharge position of the ink droplet. Is stable, and the ink droplet can be stably ejected and fly without clogging.

Further, in the ink jet recording apparatus of the present invention, a lead wire for supplying a voltage to a control electrode for applying an electrostatic force required for ink ejection is provided between the layers inside the control board having a multilayer structure, thereby drawing out. It is possible to further reduce the pitch of the through-holes in the ink discharge section and increase the resolution without causing conduction between lines.

Further, by forming the lead lines separately on the surface of the insulating substrate or between the layers of the multilayer insulating substrate, it is possible to further narrow the pitch of the through-holes in the ink discharge section.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a structure of a main part of a head of an ink jet recording apparatus provided with a lead line on a surface of an insulating substrate.

FIG. 2 is a perspective view of the surface region of FIG. 1;

FIG. 3 is a schematic sectional view illustrating a configuration of a main part of a head of an ink jet recording apparatus according to the present invention.

FIG. 4 is a perspective view of the surface region of FIG. 3;

FIG. 5 is a schematic diagram showing a state of a head in which four ink ejection units are arranged in three rows.

FIG. 6 is a schematic cross-sectional view illustrating an arrangement of ink ejection units in another example of the inkjet recording apparatus of the present invention.

FIG. 7 shows an example of a lead line pattern on a second layer in FIG. 6;

8 is an example of a lead line pattern on a third layer in FIG. 6;

9 is an example of a lead line pattern on a fourth layer in FIG. 6;

FIG. 10 is a schematic cross-sectional view illustrating an arrangement of ink ejection units in still another example of the inkjet recording apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Through-hole 11 ... Control board 12 ... Slit 13 ... Ink guide 14 ... Control electrode 15, 115, 125, 135 ... Lead-out line 16 ... Ink 17 ... Ink tank 18 ... Through-hole 20 ... Counter electrode 21 ... Recording medium

Continued on the front page (72) Inventor Yasuo Hosaka 1 Toshiba-cho, Komukai, Kawasaki-shi, Kanagawa Prefecture Inside the R & D Center of Toshiba Corporation (72) Inventor Hideyuki Nakao 1st Toshiba-cho, Komukai-ku, Saiwai-ku, Kawasaki-shi, Kanagawa Stock (72) Koichi Ishii, Inventor Koichi Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture (72) Kazuhiko Higuchi, Inventor Kazuhiko Higuchi 1, Komukai-Toshiba-cho, Kochi-ku, Kawasaki-shi, Kanagawa Address Toshiba Research and Development Center Co., Ltd. (56) References JP-A-9-314867 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/06 B41J 2/385

Claims (2)

(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. A multi-layer insulating substrate having a plurality of arranged through-holes, a plurality of control electrodes formed around the through-holes on the surface of the multi-layer insulating substrate to apply the electrostatic force, and each of the plurality of control electrodes being pulled out from the control electrode. A control electrode substrate having a lead line led between layers of the multilayer insulating substrate via a through hole; and a convex ink guide disposed at a substantially central position of the through hole and protruding in an ink droplet flying direction. And an ink supply unit for supplying the ink to the convex ink guide through the through hole. 2. 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. A multi-layer insulating substrate having a plurality of arranged through-holes, a plurality of control electrodes formed around the through-holes on the surface of the multi-layer insulating substrate to apply the electrostatic force, and each of the plurality of control electrodes being pulled out from the control electrode. A control electrode substrate having a lead wire divided and guided to any one of the layers of the multilayer insulating substrate through the surface of the multilayer insulating substrate or through holes; and a control electrode substrate disposed at a substantially central position of the through hole. A convex ink guide protruding in an ink droplet flight direction; and an ink supply means for supplying the ink to the convex ink guide through the through hole. Inkjet recording device.