JPS60240459A - Ink jet printer head - Google Patents

Abstract

PURPOSE:To obtain good printing by concentrating an electric field only to one place of ink, by making the thickness of the projecton, where the leading end of a recording electrode is positioned and ink is turned around, thinner toward the leading end thereof. CONSTITUTION:Large number of projection 16, each of which becomes thinner in its thickness toward the leading end thereof and received cutting processing in its underside are provided to a PC plate 2 and the leading ends of recording electrodes 1 are arranged to said projections 16, the ink film 18 of the ink 4 in an ink jet orifice 6 is turned around each projection 16 to wet the leading end of each recording electrode 1 but formed in a miniscus state along the shape of the projection in the vicinity of the leading end of each projection. When a recording signal is applied to the recording electrode 1, the concn. of an electric field is generated only at one place because the ink film 18 is formed in the meniscus state. Therefore, the ink 4 is easily flied from each projection 16 and always flown in the same state and adhered to recording paper to form a uniform dot.

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to an inkjet printer head for an inkjet printer that prints by flying ink droplets.

Technical Background and Problems of the Invention Recently, an inkjet method has been developed in which an electric field is partially concentrated on the ink film formed at the opening of a slit, and the ink in that part is ejected as ink droplets by Coulomb force to perform printing. dot printers are being considered. Such a printer has the advantage of producing very little noise during printing.

On the other hand, since the surface of the ink film is flat, it has the disadvantage that it is difficult to concentrate the electric field. Therefore, an inkjet printer head is being considered that allows the electric field to be easily concentrated at a predetermined position on the ink film. Example 6 of something like this
This will be explained based on the diagram and FIG. 7. Multiple recording electrodes
A PCC 20 with printed wiring is provided, and this PCC
The ink holding section 3 is fixed on the board, and these PCCs 20
An ink ejection hole 6 that holds ink 4 and has an opening 5 is formed between the ink holding portion 3 and the ink ejection hole 6 . or.

A plurality of protrusions 7 projecting from the opening 5 in a zigzag pattern are integrally formed on the PC board 2, and the tip of the recording electrode 1 is disposed on each of these protrusions 7. The inkjet printer head 8 is formed in this way. A counter electrode 10 is provided to face the inkjet printer head 8 with a recording paper 9 interposed therebetween.

With such a configuration, the ink 4 in the ink ejection hole 6
wraps around the protrusion 7 and is held in the opening 5 by surface tension, forming an ink film 11. This ink film 11 wets the tip of the recording electrode 1.

Along the shape of the protrusion 7, only the vicinity of the tip of the protrusion 7 protrudes. Therefore, recording electrode 1 and counter electrode 1
0, an electric field is concentrated on the ink 4 existing near the tip of the protrusion 7, but this concentration of electric field becomes stronger, the ink 4 easily flies, and the printing condition becomes stable. .

On the other hand, in order to maintain PCC201 strength, it must have a certain degree of thickness. However, the protrusion 7 that is integrated with the PCC 20 also has a thickness α that is the same width as the PCC 20, and two separated edges 12 are formed at the tip of the protrusion 7. Therefore, the ink film 11 is formed in a shape that wraps around both of the two gills 912. Therefore, two edges】
The disadvantage is that the concentration of the electric field is dispersed in the ink 4 existing in the vicinity of each of the two inks. This causes the problem that the amount and direction of the flying ink 4 are not constant due to changes in the atmosphere, making it impossible to perform stable printing.

OBJECTS OF THE INVENTION The present invention has been made in view of the above points, and an object thereof is to obtain an ink-end printer head capable of concentrating an electric field only at one location of the ink existing near the tip of the protrusion.

Summary of the Invention In the present invention, the thickness of the protrusion around which the tip of the recording electrode is located and the ink wraps around is made thinner as it approaches the tip of the protrusion, so that the shape of the ink film formed at the tip of the protrusion becomes meniscus. The structure is such that the electric field can be concentrated only at one location of the ink near the tip of the protrusion.

Embodiment of the Invention An embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. Note that the same parts as in FIGS. 6 and 7 are indicated by the same reference numerals, and description thereof will be omitted. inkjet printer head 8
is placed on a recording paper 14 held horizontally with the recording surface 13 facing upward. A grounded counter electrode 15 is provided in contact with the back surface of the recording paper I4, and the inkjet printer head 8 is placed at a position facing the counter electrode 5 at an angle of 30 degrees.

Next, a plurality of protrusions 16 are integrally formed with the PC board 2 and are machined on the lower side so that the thickness becomes thinner toward the tip. is installed. Further, two edges 17 are formed at the tip of the protrusion 16, and the distance β between these edges 17 is close to each other.

It is thinner than the thickness of the PC board.

In such a configuration, the ink 4 in the ink ejection hole 6
is held in the opening 5 by surface tension to form an ink film 18. This ink film 18 wraps around the protrusion 16 and wets the tip of the recording electrode 1, and is formed in a meniscus shape along the shape of the protrusion 16 near the tip of the protrusion 16.

Therefore, when a recording signal is selectively applied to the recording electrode 1, a potential difference is generated between the recording electrode 1 and the counter electrode 15.

A Coulomb force is generated between the recording electrode 1 and the counter electrode 15,
The electric field concentrates on the ink 4 existing near the tip of the protrusion 16.

At this time, since the ink film 18 is formed in a meniscus shape near the tip of the protrusion 6, an electric field is concentrated only at the - location of the ink film 18. Therefore, the protrusion 1
6 The ink 4 existing near the tip always flies in the same state and adheres to the recording paper 14 to form a uniform dot.
Furthermore, since the electric field is concentrated only at one predetermined location in the ink film 18, the generated electric field becomes stronger. This makes it easier for the ink 4 to fly from the protrusion 16.

In addition, in practice, as shown in FIGS. 5(a) and 5(b), the upper side or both the upper and lower sides of the protrusion 16 may be cut to reduce the thickness of the tip of the protrusion 16. Further, the tip of the protrusion 16 may be sharpened or rounded.

Effects of the Invention In the present invention, the protrusion where the tip of the recording electrode is located and the ink wraps around it is made thinner as it gets closer to the tip of the protrusion, so that the shape of the ink film formed at the tip of the protrusion becomes meniscus-shaped. As a result, the electric field can be concentrated in only one location of the ink near the tip of the protrusion. Therefore, the ink always flies in the same state, resulting in uniform dot shapes and good printing results. In addition, since the electric field is concentrated on the ink film, the ink becomes easier to fly, and the gap between the recording electrode and the counter electrode can be increased.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a protrusion showing an embodiment of the present invention, Fig. 2 is a perspective view showing an example of installation of an inkjet printer head, Fig. 3 is a perspective view of the whole, and Fig. 4 is a perspective view of the protrusion and inkjet printer head. A side view showing the shape with the membrane, FIG. 5 is a side view showing a modification thereof,
FIG. 6 is a perspective view showing a conventional example, and FIG. 7 is an enlarged side view showing the shapes of the protrusion and ink film in FIG. 6. 1... Recording electrode, 4... Ink, 5... Aperture, 6
...Ink ejection hole, 16...Protrusion 3'' Figure 17

Claims (1)

[Scope of Claims] A slit-shaped ink ejection hole for holding ink is provided, a plurality of recording electrodes are provided perpendicular to the opening of the ink ejection hole, and a plurality of protrusions at which tips of these recording electrodes are located are provided. A portion is formed to protrude from the opening. An inkjet printer head characterized in that the thickness of these protrusions is made thinner toward the tips of the protrusions.