JPS6319351B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is based on a patent application filed in 1983 by the same applicant.
This invention relates to an improvement in the inkjet recording head described in No. 8428.

FIG. 1 shows an improved inkjet recording head described in Japanese Patent Application No. 56-8428, and the principle will be briefly explained with reference to the same figure. An air outlet 1 is perforated in the insulating substrate 5, and an electrode 3 is provided on the surface of the insulating substrate 5 around the air outlet 1. An orifice plate 6 is arranged parallel to the insulating substrate 5, and an ink discharge port 2 is bored in the orifice plate 6, facing the air discharge port 1.
An air flow is sent from the periphery to the air layer 4 created by the insulating substrate 5 and the orifice plate 6 via the air supply pipe 10 and the air chamber 9, and flows out from the air outlet 1. Since the direction of the air flow changes rapidly near the air outlet 1, a rapid change in pressure gradient occurs in the air from the ink outlet 2 to the air outlet 1.

On the other hand, a constant pressure is applied to the ink in the ink chamber 11, and when the ink jet recording head is not driven, the air pressure near the ink ejection ports 2 and the ink pressure in the ink chamber 11 are approximately equal, and the ink pressure in the ink ejection ports 2 is approximately equal. Adjustments are made such that the resulting ink meniscus remains stationary. 8 is the body.

The signal source 12 is electrically connected to the ink supply pipe 7 communicating with the electrode 3 and the ink discharge port 2 so that a potential difference is generated between the electrode 3 and the ink within the ink discharge port 2 . When a potential difference is generated between the electrode 3 and the ink inside the ink discharge port 2 by the signal source 12, the meniscus of the ink generated in the ink discharge port 2 is stretched in the direction of the air discharge port 1 due to the electrostatic force caused by this potential difference. A rapid change in pressure gradient occurs in the space from the ink discharge port 2 to the air discharge port 1, and the degree of this change is greater than that of the air discharge port 1.
Therefore, when the ink meniscus generated at the ink ejection port 2 is stretched beyond a certain length, it is torn off by the change in the pressure gradient, and the ink liquid is ejected from the air ejection port 1.

2 is a sectional view showing an example in which the inkjet recording head having the structure shown in FIG. 1 is made into a multi-nozzle structure;
The figure is a perspective view of the same. Note that the same components will be represented by the same symbols hereinafter. Air outlet ports 1-1 to 1-8 are perforated at equal intervals in the insulating substrate 5, and electrodes are provided independently on the surface of the insulating substrate 5 around the air outlet ports 1-1 to 1-8. 3-1
~3-8 are provided. An orifice plate 6 is arranged parallel to the insulating substrate 5, and the ink discharge ports 2-1 to 2-8 are connected to the air discharge ports 1-1 to 1-8.
It is perforated opposite to. An ink chamber 11 communicating with an ink reservoir via an ink supply pipe 7 is filled with ink, and ink discharge ports 2-1 to 2-
8, an ink meniscus is generated respectively. On the other hand, an air flow is sent into the air chamber 9 via the air supply pipe 10, passes through the air layer 4 formed by the insulating substrate 5 and the orifice plate 6, and suddenly exits the air discharge ports 1-1 to 1-8. It is erupting with a curved shape.

A potential difference can be generated independently between the electrodes 3-1 to 3-8 and the ink in the ink chamber 11, and the electrode 3-n where this potential difference is generated
The ink meniscus generated at the ink ejection port 1-n corresponding to the electrode 3-n is stretched by electrostatic force, and due to the sudden change in pressure gradient, the ink meniscus generated at the ink ejection port 1-n corresponding to the electrode 3-n Ink liquid is ejected and flies. There are two manufacturing drawbacks to the multi-nozzle head of FIG. 2 or 3.

The first drawback is that air discharge ports 1-1 to 1-8
It is necessary that the ink discharge ports 2-1 to 2-8 form concentric circles with high precision. For this purpose, air discharge ports 1-1 to 1-8 and ink discharge ports 2 are required.
-1 to 2-8 must be drilled with good linearity and at equal intervals, and a sophisticated orifice drilling technique is required. Furthermore, in the assembly process, it is necessary to accurately align and connect the air outlets 1-1 to 1-8 and the ink outlets 2-1 to 2-8, and a high degree of skill is required.

The second drawback is that the electrodes 3-1 to 3-8 must each have a structure that can be controlled independently;
It is required to form a fine electrode pattern on the insulating substrate 5 in consideration of mutual insulation between the electrodes 3-1 to 3-8. The formation of such a fine electrode pattern becomes more difficult as the interval between the air discharge ports 1-1 to 1-8 becomes smaller.
The -8 shape is an obstacle to increasing the density of multi-nozzle heads.

The present invention solves the above-mentioned drawbacks of the multi-nozzle head, and one embodiment thereof will be described in detail below.

FIG. 4 is a perspective view showing an embodiment of the present invention. A large number of air discharge ports 1 are perforated in the insulating substrate 5 at equal intervals and in a straight line, and an electrode 3 is provided on the surface of the insulating substrate 5 in common to all the air discharge ports 1. Further, the orifice plate 6 is provided with a slit-shaped opening 13 extending in the same direction as the arrangement of the air discharge ports 1, and a large number of thin wires 14 are arranged perpendicularly to the slit-shaped opening 13 on the orifice plate 6.
bonded to the surface. The insulating substrate 5 is the body 8
However, the insulating substrate 5 and orifice plate 6
An air layer is formed at a constant distance from the air outlet 1, and the air flow is ejected from the air outlet 1 with a sharp bend.

FIG. 5 is an enlarged view of the air outlet 1 and the slit opening 13 shown in FIG. Thin wires 14 and 14' are installed perpendicularly to the slit-like opening 13, and the ink filling the slit-like opening 13 forms an ink meniscus in the gap between the thin wires 14 and 14'. . Thin line 1
The shape and arrangement density of 4 and 14' are selected so that the ink meniscus generated in this gap has sufficient retention force due to surface tension, and the viscous resistance due to this gap does not become too large. In general, it is better to arrange the thin wires 14, 14' to be sufficiently thin compared to the diameter of the air outlet 1 and to arrange a plurality of thin wires 14, 14' so that they correspond to one air outlet 1. Although the ink meniscus generated in the ink is in an effective state, in FIG. 5, thin lines 14, 14' having a relatively large shape and a coarse arrangement are drawn for the sake of clarity.

Air discharge ports 1 are perforated in the insulating substrate 5 at equal intervals, and the air discharge ports 1-n are arranged to face the thin wires 14-n. Multiple thin lines 1
Reference numeral 4 plays the role of an electrode, and is configured such that a potential difference is generated independently between each of the plurality of air discharge ports 1 and the electrode 3 commonly installed on the surface of the insulating substrate 5. When a potential difference is generated between the thin wire 14-n and the electrode 3, the meniscus of ink generated near the thin wire 14-n is stretched in the direction of the air outlet 1-n by the electrostatic force caused by this potential difference.
On the other hand, an air stream is ejected from the air outlet 1 in a sharp curve so as to create a steep pressure gradient, and the stretched ink liquid is ejected from the air outlet 1.
- Discharge and fly from n.

The thin wires 14' provided between the thin wires 14 are
The main purpose is to form a meniscus of ink in a suitable shape.
Depending on the case, it may be omitted, or a plurality of them may be installed.

Since the thin wires 14' do not play a role as electrodes, they may be made of an insulating material or a conductive material. In a configuration in which the thin wires 14 are arranged in high density, insulation between the thin wires 14 can be easily achieved by using an insulating material. In addition, if a conductive material is used for the thin wire 14', the air outlet 1
The thin wire 14-(n
-1) and the thin wire 14-n can be blocked, and good ejection characteristics can be maintained even in a high-density multi-nozzle configuration. In the actual configuration, a further improved multi-nozzle is achieved by arranging the thin wire 14, the thin wire 14' made of an insulating material, and the thin wire 14' made of a conductive material and having the same potential as the electrode 3 at appropriate intervals. head can be realized.

As explained in detail above, the present invention perforates an insulating substrate with a plurality of air outlets at equal intervals, forms an electrode that includes the plurality of air outlets in common on the surface of the insulating substrate, and A multi-nozzle head configuration is realized by providing an orifice plate having a slit-like opening in which thin wires are arranged in a position parallel to an insulating substrate.

In this configuration of the present invention, unlike the configuration shown in FIG. 2 or 3, the positional accuracy of the air outlet 1 is relatively rough and good, and there is no need to form electrodes in a fine pattern. , a high-density multi-nozzle configuration can be easily manufactured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an inkjet recording head according to an earlier application of the present invention, FIG. 2 is a sectional view showing an embodiment in which the configuration of FIG. 1 is made into a multi-head, and FIG. 3 is an exploded perspective view of the same. FIG. 4 is an exploded perspective view showing an embodiment of an inkjet recording head according to the present invention, and FIG. 5 is an enlarged perspective view of the same essential parts. 1... Air discharge port, 2... Ink discharge port, 3...
...Electrode, 4...Air layer, 5...Insulating substrate, 6...
... Orifice plate, 7 ... Ink supply pipe, 8 ... Body, 9 ... Air chamber, 10 ... Air supply pipe, 11
... Ink chamber, 12 ... Signal source, 13 ... Slit-shaped opening, 14, 14' ... Thin wire.

Claims (1)

[Claims] 1. Ink is held in a slit-shaped opening in which thin wires are arranged, and air discharge ports are arranged facing each other on the same axis as the ink discharge direction, and a sharp curve is formed in the gap between the slit-shaped opening and the air discharge port. a first means for sending out an air flow from the air outlet while causing the air flow to form a space where the pressure gradient changes such that the air pressure decreases in the direction from the slit-shaped opening to the air outlet; It has a second means for selectively generating a potential difference between the member having the discharge port and the thin wire according to a signal, and is formed into a slit-shaped opening by an attractive force caused by the potential difference of the second means. Stretch the ink meniscus,
An inkjet recording head characterized in that the first means applies an accelerating force of the air flow generated in the space where the pressure gradient changes to cause the ink in the slit-shaped opening to be ejected outward through the air ejection port.