JPS6319350B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a new inkjet recording device that utilizes a pressure gradient created by an air flow.

FIG. 1 shows a new type of inkjet recording head described in an earlier application by the same applicant. A brief explanation of the prior application will be given below with reference to FIG. The nozzle plate 2 has an air outlet 1 perforated therein, a wall 3 is arranged parallel to the nozzle plate 2, and an ink outlet 4 is perforated in the wall 3 opposite to the air outlet 1. has been done. Nozzle plate 2 and wall 3
An air flow is sent from the surrounding area to the air layer 7 created by this, and it flows out from the air discharge port 1. Since the direction of the air flow changes rapidly near the air outlet 1, a rapid change in pressure gradient occurs in the space from the ink outlet 4 to the air outlet 1.

On the other hand, a constant pressure is applied to the ink inside the ink ejection port 4, and when the inkjet recording head is not driven, the air pressure near the ink ejection port 4 and the ink pressure inside the ink ejection port 4 are approximately equal. Adjustment is made so that the meniscus of ink generated at the ejection port 4 is kept stationary.

The signal source 5 connects the nozzle plate 2 so that a potential difference is generated between the nozzle plate 2 and the ink inside the ink ejection port 4.
It is also connected to an ink supply pipe 6 that communicates with the ink discharge port 4 . The signal source 5 causes the nozzle plate 2 to
When a potential difference occurs between the ink in the ink discharge port 4 and the ink discharge port 4, the meniscus generated in the ink discharge port 4 is stretched in the direction of the air discharge port 1 due to the electric field caused by this potential difference. A rapid change in pressure gradient occurs in the space from the ink discharge port 4 to the air discharge port 1, and the degree of this change is greater as the distance to the air discharge port 1 increases. When the resulting ink meniscus is stretched beyond a certain length, it is torn off by this change in pressure gradient and flies out of the air discharge port 1 as ink droplets.

As explained above, the head according to the earlier application by the present applicant uses electrostatic force to
By changing the shape of the ink meniscus that occurs in
Ink droplets are ejected by a sudden change in pressure gradient caused by an air flow.

FIG. 2 shows an example in which the inkjet recording head shown in FIG. 1 is made into a so-called multi-nozzle head having a plurality of ink ejection ports, and FIG. 2A is a front view and FIG. 2B is a sectional side view.

The ink chamber 8 communicates with a plurality of ink discharge ports 9 and at least one ink supply pipe 10 leading to an ink reservoir. Also, air supply pipe 1
The airflow flowing in from the ink discharge port 9 is made uniform in the air chamber 12 and passes through the air layer 13.
The ink is ejected from air ejection ports 14 facing each other, and the ink ejection ports 9 are arranged in a space where a rapid change in pressure gradient occurs. The nozzle plate 18 is provided with an air discharge port 14, around which electrodes 15 are provided independently, each electrically connected to an independent signal source 16.
The signal source 16 is electrically connected to the ink in the ink ejection port 9 on the one hand, and has a structure in which a potential difference is independently applied between the electrode 15 and the ink in the ink ejection port 9. It's summery. 17 is the body.

In a multi-nozzle head as shown in FIG. 2, high dimensional accuracy and skill are required in the machining and assembly process of the ink discharge port 9 and the air discharge port 14. In particular, in the structure shown in FIG. 2, since the ink ejection port 9 has a small value of several μm to several tens of μm,
The processing itself is difficult, and the air outlet 1
In order to improve the accuracy of hole alignment with 4, a very high level of skill is required in addition to dimensional accuracy.

The present invention eliminates these drawbacks and provides an inkjet recording device with a simple structure and stable characteristics.

An embodiment of the present invention will be described in detail below.

FIG. 3 shows an embodiment of the invention. The embodiment shown in FIG. 3 differs from that shown in FIG. 2 in that the ink discharge port 9 in FIG. 2 is replaced with a porous body 19. In the configuration shown in FIG. 3, an ink discharge port is not necessary, and the ink that has permeated into the porous body 19 is drawn out by electrostatic force and is ejected from the air discharge port 14. The fourth principle of flight is
This will be explained in more detail with the help of figures.

FIG. 4 is an enlarged view of the porous body 19 and air discharge port 14 of the inkjet recording device shown in FIG.
It is a line cross-sectional side view. The porous body 19 and the nozzle plate 18 having the air outlet 14 maintain uniform intervals,
They are placed facing each other to form an air layer 13.
The air flow sent into the air chamber 12 passes through the air layer 13 and flows out from the air outlet 14. On the other hand, a pressure approximately equal to the air pressure generated in the air layer 13 by the air flow is applied to the ink contained in the ink chamber 8 and the porous body 19, and the ink is retained within the porous body 19. It is adjusted to hang. The air pressure generated in the air layer 13 varies depending on the nozzle plate 18, the air outlet 14, the air layer 13, the air flow rate, etc., but generally, the air pressure generated in the air outlet 1
It is slightly lower in the vicinity of 4, and slightly higher in other parts. On the other hand, since the pressure of the ink in the ink chamber 8 and the porous body 19 is constant, the surface of the porous body 19 has a slight bulge near the air outlet 14 and a slight retraction in other parts. An ink level 21 is created. Electrode 15, ink chamber 8 and porous body 1
When a potential difference is generated in the ink in the ink 9, electric lines of force concentrate on the raised part of the ink liquid surface 21 closest to the electrode 15, and the ink in the raised part of the ink liquid surface 21 is stretched and becomes a droplet, which is released into the air. Discharge port 1
Fly from 4.

FIG. 5 shows another embodiment of the invention.

The embodiment shown in FIG. 5 differs from that shown in FIG. 4 in that an electrode 22 is added to the porous body 19. Electrode 2
No. 2 is provided corresponding to each air discharge port 14, and is located near the swollen portion of the ink liquid surface 21. In the configuration shown in FIG. 5, since a potential difference is provided between the electrode 15 and the electrode 22, the electric lines of force are well concentrated, and the influence of the swelling state of the ink liquid level 21 is small, resulting in stable characteristics. An inkjet recording device is obtained.

Note that the multiphoton material 19 is preferably made of minute pores, has a high porosity, can easily fill the pores with ink, and has a strong surface tension retention force. Further, the porous body 19 may be a collection of a plurality of nozzles.

As explained in the above embodiments, according to the present invention, by replacing the ink ejection opening with a porous material, an ink jet head with a very simple structure and less difficulty in manufacturing can be realized. be.

This effect is particularly great in a multi-nozzle head that utilizes an electric field, as in the earlier application filed by the present applicant.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of an inkjet recording device in a previous application filed by the present applicant, FIG. 2 a is a front view of the same, FIG. 2 b is a sectional view of the same, and FIGS. FIGS. 4a and 4b are respectively an enlarged front view and a sectional view of the main parts of FIG. 3, and FIG. 5 is an inkjet in another embodiment of the present invention. FIG. 1 is a cross-sectional side view showing the configuration of a recording device. 1,14...Air discharge port, 2,18...Nozzle plate, 3...Wall, 4,9...Ink discharge port, 5,1
6... Signal source, 6, 10... Ink supply pipe, 7,
13... Air layer, 8... Ink chamber, 11... Air supply pipe, 12... Air chamber, 15, 22... Electrode,
17...Body, 19...Porous body, 21...Ink liquid level.

Claims (1)

[Scope of Claims] 1. An air outlet is installed facing a porous material filled with liquid ink, and air is discharged from the air outlet while creating a sharp bend in the gap between the porous material and the air outlet. a first means for sending out a flow and forming a space in which the pressure gradient changes such that the pressure of the air decreases in the direction from the porous material to the air outlet; and an electrode provided around the air outlet; and the liquid ink filled in the porous material, the ink in the porous material is Inkjet recording characterized in that the ink in the porous material is ejected outward through an air ejection port by applying an accelerating force of an air flow generated in a space where the pressure gradient changes by the first means. Device. 2. The inkjet recording device according to claim 1, further comprising an electrode within the porous material at a position opposite to the air discharge port.