JPH0544346B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is characterized in that liquid ink is ejected by an electric field to form dots on a recording medium, and images such as characters and figures are formed by the combination of these dots. The present invention relates to printing devices.

Conventional technology Conventionally, so-called inkjet printers, which form images on a recording medium by ejecting liquid ink droplets from a nozzle, have been known to produce less noise during printing and to perform multicolor printing compared to other printing methods. Many inventions have been made and improvements have been made for reasons such as being advantageous in terms of running costs and the like. However, countermeasures against nozzle clogging caused by ink evaporation are not sufficient, and this has become a practical problem.

In order to eliminate the occurrence of such nozzle clogging, a type of printer using liquid ink that is different from the above-mentioned inkjet printer is being considered.

First, to give an example, as described in JP-A-56-170 and JP-A-56-4467, a slit-shaped opening is formed instead of a nozzle that is prone to clogging. However, an electric field is applied between opposing electrodes facing this opening to cause the ink to fly.

This type of ink has a problem in that the structure for releasing ink droplets from the slit-shaped opening is delicate and lacks stability.

In addition, as for other methods, JP-A-54-
As seen in Japanese Patent Application Laid-open No. 23534 and Japanese Patent Application Laid-open No. 159355/1983, ink is guided to the tip of a needle-like member along its outer periphery, and the ink is caused to fly by an electric field.

In this type of product, magnetic ink must be used to guide the ink to the tip of the needle-like member, and this magnetic ink has a high degree of freedom in color selection due to the ground color of the magnetic powder contained in it. The disadvantage is that there is no

Problems to be Solved by the Invention In order to solve the disadvantages of the above-mentioned inkjet printer using liquid ink while maintaining its features, it is necessary to avoid clogging in the part where the ink is ejected. That is absolutely necessary.

Also, the use of magnetic ink as the liquid ink is undesirable due to its color, and it must be possible to print with ordinary plain ink.

In order to solve these problems, the applicant invented a printing device of the type shown in FIG. 8, and
A patent application was filed. First, an ink container 2 for storing ordinary liquid ink 1 is provided, and a needle-shaped recording electrode 3 having electrical conductivity and ink-impregnating property is provided inside the ink container 2 and immersed in the ink 1. The tip 4 of the electrode 3 is exposed from the ink container 2. A counter electrode 6 is provided at the tip 4 of the recording electrode 3 with a recording paper 5 interposed therebetween. , 9 are connected. Then, the switching circuit 7
A control circuit 10 that generates a control signal according to an image signal is connected to.

The following recording electrodes 3 are used as the above-mentioned recording electrodes 3.

(1) Metal particles formed by casting without losing air permeability.(2) Sintering formed from conductive particles such as transition metal oxides.(3) Conductive particles mixed with carbon fine particles. Breathable foam molded plastics Among these, (1) and (2) are a collection of irregularly shaped particles, and the pores formed between the particles communicate three-dimensionally. In addition, (3) also has a substantially similar structure.

Therefore, the ink 1 always reaches the tip 4 of the recording electrode 3, and the switching circuit 7 operates according to the image signal to generate an electric field between the recording electrode 3 and the counter electrode 6, and the tip reaches the tip 4. 4, the ink 1 is ejected toward the recording paper 5.

Printing is performed according to this principle, but since the tip 4 of the recording electrode 3 is exposed to the outside, the ink 1 in that part dries, but the ink container 2
Since the degree of fluid communication with the ink 1 inside is high, the concentration of the ink 1 can be uniformized well, and no slag of the ink 1 is generated at the tip 4.

In this way, this type of printing device is a dramatic advance over conventional technology, but in order to increase the printing speed, it is necessary to reduce the amount of ink 1 supplied without the risk of droplets. This is something that needs to be increased. That is, it is desirable that the recording electrode 3 has a high ability to retain the ink 1 and has low fluid resistance.

Means for Solving the Problems A recording electrode is formed by integrally molding a fibrous material into a bundle so as not to lose air permeability in the fiber direction.
In order to impart electrical conductivity to the recording electrode, the fibrous material is made electrically conductive, mixed with electrically conductive material, or a thin metal film is formed on its surface.

Function The material forming the recording electrode is a fibrous material,
Moreover, since the ink is integrated into a bundle so as not to lose air permeability in the direction of the fibers, the fluid resistance of the ink is low in the direction of the fibers, and even if the amount of ink consumed is large, it can be supplied sufficiently, and the printing can be done easily. No scratches will occur.

Embodiment A first embodiment of the present invention will be described based on FIGS. 1 to 6. Components that are the same as those described in connection with FIG. 8 are designated by the same reference numerals, and description thereof will be omitted. First, the printer 11 has two (first
Guide shaft 1 (only one is shown in the figure)
2 is provided horizontally, and a carrier 13 is attached to this guide shaft 12 so as to be able to reciprocate from side to side. A printing head 14 is placed on this carrier 13. Further, in the center of the printer 11, a counter electrode 6 facing the printing head 14 is horizontally attached. Behind this counter electrode 6 is a tractor 1 that feeds recording paper 5 as a recording medium.
5 is provided. An operating knob 16 projecting outward is coupled to the tractor 15.

The printing head 14 is similar to that shown in FIG. 8, but the recording electrode 17 has a different structure as will be described later. The upper surface of the ink container 2 is covered with a printed wiring board 18, and the recording electrode 17 is held at the tip of a wire 19 that is electrically connected and fixed to the printed wiring board 18. Further, the printed wiring board 18 is connected to a connector 20,
This connector 20 is connected to a switching circuit 21.

For the recording electrode 17, stainless steel fibers are used as the fibrous material, and the stainless steel fibers are bundled in the direction of the fibers so as not to lose air permeability and are integrally formed into a needle shape.

In such a configuration, the printing operation is performed in the eighth
Although it is similar to that described with reference to the figure, since the recording electrode 17 has a low fluid resistance in the direction of its fibers, the exhausted ink 1 is quickly replenished. For example, the viscosity of ink 1 is approximately 5 cp (the specific resistance is approximately 10 ⁷ Ω−
cm), and the voltage applied to the counter electrode 6 is -1.8KV.
It is assumed that the voltage applied to the recording electrode 17 according to the image signal is +1.4 KV. Under such conditions, most of the recording electrode 17 is inserted into the ink 1 in the ink container 2, so
The internal space of the recording electrode 17 contains ink 1 in a supersaturated state, and is abundantly supplied to the tip 4 of the recording electrode 17 .

Furthermore, since the recording electrode 17 has a large number of through holes, even if some of the holes become clogged, it can be compensated for by the many other holes. Since these many through-holes are not completely independent and communicate with adjacent holes in many parts, there is a high possibility that even if clogging occurs, it will recover.

Furthermore, similar results can be obtained by using carbon fibers instead of stainless steel fibers. As such conductive fibers, conductive glass fibers can also be used. That is, an example of this conductive glass fiber is a glass fiber monofilament plated with nickel.

Next, the recording electrode 17 may be formed by blending polyester fiber and stainless steel fiber. By doing so, the manufacturing process is often stabilized. Moreover, natural fibers may be used instead of polyester fibers.

In addition, a bundle 22 is formed of non-conductive fibers such as polyacetal or polyester, and a metal thin film 23 is formed by sputtering as shown in FIG.
may be formed to impart conductivity.
This metal thin film 23 has a thickness of about 0.1 μm and is attached to one side of the bundle 22 .

As shown in FIG. 6, such a metal thin film 23 may be formed by depositing the entire circumference by vacuum evaporation or the like, and exposing the fiber bundle only near the ends by masking or etching. In this case, the ink 1 is not supplied from the outer peripheral surface, but is sufficiently sucked from the end of the bundle 22.

Next, FIG. 7 shows a second embodiment of the present invention, in which a large number of recording electrodes 17 are arranged in parallel. In this case, each recording electrode 17
An independent switching circuit 7 is connected to the control circuit 10, and a switching operation corresponding to the image is performed by the control circuit 10.

Effects of the Invention In the present invention, as described above, the recording electrode facing the counter electrode with a recording medium interposed therebetween is formed by integrally molding a fibrous material. As a result, the ink supply to the tip of the recording electrode is plentiful, and high print quality can be obtained even during high-speed printing, and the ink at the tip does not flow out. Since there are a large number of micropores, there is no clogging due to ink drying, and the recording electrode can be made conductive by making the fibrous material itself conductive or by attaching a thin metal film. This is possible by simple means.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view showing a first embodiment of the present invention, FIG. 2 is a perspective view of the printer, FIG. 3 is a side view of the recording electrode, FIG. 4 is a rear view thereof, and FIG. 5 is a metal 6 is a sectional view showing another example, FIG. 7 is a vertical sectional side view showing a second embodiment of the present invention, and FIG. FIG. 3 is a longitudinal side view for explaining the printing method of the present invention. 1... Ink, 4... Tip, 5... Recording paper (recording body), 6... Counter electrode, 17... Recording electrode,
22... Bundled body, 23... Metal thin film.

Claims (1)

[Scope of Claims] 1. A recording electrode with ink attached to the tip thereof and a counter electrode are arranged facing each other with a recording body interposed therebetween, and an electric field between these recording electrodes and the counter electrode exceeds a predetermined value. In a printing device in which ink sometimes flies from the tip of the recording electrode to form an image on the recording medium, the fibrous material is integrally formed into a bundle so as not to lose air permeability in the fiber direction. A printing device characterized by forming recording electrodes. 2. The printing device according to claim 1, wherein the recording electrode is formed of a conductive fibrous material such as metal fiber, carbon fiber, or conductive glass fiber. 3. The printing according to claim 1, wherein the recording electrode is formed by mixing a fibrous material made of natural fibers or synthetic fibers with a conductive fibrous material such as metal fiber or carbon fiber. Device. 4. A recording electrode with ink attached to its tip and a counter electrode are arranged facing each other with a recording body interposed therebetween, and when the electric field between these recording electrodes and the counter electrode exceeds a predetermined value, the tip of the recording electrode In a printing device in which ink is ejected from a portion of the recording medium to form an image on the recording medium, a bundle is formed by integrally molding a fibrous material into a bundle so as not to lose air permeability in the direction of the fibers. , a printing device characterized in that a thin metal film is adhered to the surface of the bundled body.