JPH02103152A - Nozzleless ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To always keep the jet direction of an ink droplet constant by providing an auxiliary slit to the upper part of an ink jet slit part and arranging the flight direction of the ink droplet emitted by an air stream flowing from below to above. CONSTITUTION:A flat plate-shaped piezoelectric element 1 and an auxiliary plate 12 are fixed to a holder 3. The acoustic energy emitted from the piezoelectric element 1 is reflected by a reflecting plate 2 to be concentrated to a slit (b) to eject an ink droplet 8. At this time, an electric field can be applied to ink having electric viscosity effect by an electrode 4 and, by applying a voltage pulse to the electrode 4, the jet place and timing of the ink droplet 8 can be controlled. An air chamber 15 is present between the piezoelectric element 1 and the auxiliary plate 12 and the air injected from air injection ports 17, 17' passes through the air chamber to be vented upwardly from an auxiliary slit 13. The ink droplet 8 is always ejected vertically from the slit (b) by this air stream 14. Since the jet direction of the ink droplet can be arranged in one direction with good reproducibility, printing of good quality can be performed with good reproducibility.

Description

[Detailed Description of the Invention] [Summary] Regarding a nozzle-less inkjet recording device, the purpose of the present invention is to provide an inkjet recording device that can always keep the jetting direction of ink droplets constant. The acoustic energy emitted from the piezoelectric element is reflected by a reflecting plate with a parabolic surface provided in the liquid to concentrate on a line on the liquid surface and eject ink droplets, and the ink is made to have an electrorheological effect. A nozzle-less inkjet recording device that controls the location and timing of ink ejection by applying an electric field to ink using an electrode provided in an ink ejection slit, and an auxiliary air flow path formed above the ink ejection slit. An auxiliary slit formed by a plate is provided, and an air flow flowing from the bottom to the top through the auxiliary plate slit aligns the flying direction of the ink droplets ejected from the ink ejection slit portion.

[Industrial application field]

The present invention relates to a nozzleless inkjet recording device.

Inkjet recording devices are extremely low-noise, capable of high-speed printing, can use inexpensive plain paper, do not require development and fixation, and can record kanji characters, figures, etc.

Conventional inkjet recording apparatuses eject ink from narrow nozzles, which can sometimes become clogged with foreign matter. to solve this problem,
A method of ejecting ink by concentrating the acoustic energy emitted from a flat piezoelectric element placed on the liquid surface onto one point or a single strip of the liquid surface using a parabolic reflector placed in the liquid (nozzleless method). An inkjet recording device) has been proposed.

Furthermore, a method has been proposed in which the ink is given an electrorheological effect and an electrode is provided in the ink jetting section, thereby making it possible to control the timing of ink jetting and jetting from any point on the line using an electric field. There is.

When printing on recording paper, clear printing cannot be achieved unless the direction in which the ink droplets are ejected is perpendicular to the slits on the line. Therefore, there is a need for an ink ejecting unit that ejects ink droplets in a direction perpendicular to the slit.

[Conventional technology]

FIGS. 3A and 3B are explanatory diagrams of a conventional nozzleless inkjet recording apparatus.

In FIG. 3(a), the head is composed of two planar piezoelectric elements 1 and a holder 3 having a parabolic reflector 2 at the bottom. The bottom of the holder (aluminum material) 3 is shaped like a parabolic gutter, and its focal point a is set in the middle of the two piezoelectric transducers 1 in the form of a line (slit b). The piezoelectric element 1 is located on the surface of the ink, and a hydrostatic pressure is applied to the slit b (the slit width is, for example, 0.5 to 1 m) from an external ink tank (not shown). Piezoelectric element 1
Electrodes 4 for applying an electric field to the ink are densely provided in the slit b (ink ejection position) as shown in FIG. 3(b). 5 is an insulator.

In addition, electrorheological ink 6 is used as the ink, and the ejection part'll
An electric field is applied to the ink, making it possible to control the ejection position of the ink on the line. The electrorheological ink 6 contains a solvent (oil is required as a solvent, silicone oil, liquid paraffin, etc.) and fine powder (hydrophilic particles, S
ioz, Sioz Al2O, etc.), a surfactant, and a pigment (phthalocyanine, etc.).

By supplying electric power to the piezoelectric element 1, the piezoelectric element 1 vibrates in the thickness direction and emits acoustic energy. This acoustic energy is reflected by the reflection plate 2 having a radiation surface and concentrated on the slit b. In this state, the ink meniscus is continuous in the slit direction, so the ink does not become particles (sprayed), but by applying an electric signal to the electrode terminal 7, any electrode 4 facing across the slit b can be By applying a voltage (~100 V) to the ink, the viscosity of the ink between arbitrary electrodes increases, and the ink in the areas where there is no electric field is ejected. By applying an electric field to the ink at the ink ejection position in this manner, the ink can be ejected at any location of the linear slit b at any time. Note that 11 indicates a piezoelectric element terminal.

(Problems to be Solved by the Invention) In the conventional nozzle-less inkjet, acoustic energy emitted from a piezoelectric element l fixed to a holder 3 is transferred to a reflector plate 2.
The ink droplets 8 are reflected and concentrated on the slit b and are ejected. At this time, the timing of ejection is controlled by applying a voltage to the electrode 4 and changing the viscosity of the electrorheological ink 6.
The injection direction was defined by the vector direction of acoustic energy.

However, the vibrations caused by the piezoelectric element 1 are transmitted not only in the thickness direction of the piezoelectric element 1, but also directly to the holder 3 holding the piezoelectric element 1, and the vibrations cause waves on the liquid surface and the reflection plate. 2, the ejecting direction of the droplets 8 is disturbed, and the droplets 8 are ejected in an oblique direction (arrow) away from the perpendicular direction to the slit b, resulting in a problem that the print on the recording paper 10 becomes unclear.

Therefore, an object of the present invention is to provide an inkjet recording apparatus that can always keep the ejection direction of ink droplets constant.

[Means to solve the problem]

The problem is that, as shown in FIGS. 1(a) and 1(b), acoustic energy emitted from a piezoelectric element 1 placed on the ink liquid surface is reflected by a parabolic reflecting plate 2 placed in the liquid. The ink droplets 8 are ejected concentratedly on a line on the liquid surface, and the ink is made to have an electrorheological effect, and an electric field is applied to the ink 6 using the electrode 4 provided in the ink ejection slit part to eject the ink. A nozzle-less inkjet recording device that controls location and timing, wherein an auxiliary slit 3 formed by an auxiliary plate 12 forming an air flow path is provided above the ink ejection slit part, and the auxiliary slit 13 is arranged from bottom to top. This problem is solved by the inkjet recording apparatus of the present invention, which aligns the flying direction of the ink droplets 8 ejected from the ink ejection slit portion by the air flow 14 flowing through the ink ejection slit.

[Effect]

In the present invention, as shown in FIG. 1(b), an auxiliary slit 13 is formed by an auxiliary plate 12 above a slit b made by a piezoelectric element l. An air chamber 15 is provided between the piezoelectric element 1 and the auxiliary plate 12.
is provided to generate an air flow 14 in the direction of the arrow. After the ink droplets 8 are ejected from the slit b, their attitude is controlled by the air flow 14 and they reach the recording paper. This air flow 14 allows the ejection direction of the ink droplets 8 to be kept constant at all times.

〔Example〕

FIGS. 1A and 1B are explanatory diagrams of an embodiment of the present invention. Note that the same reference numerals refer to the same objects throughout the plan.

FIG. 1(A) is a perspective view of a cross section of the head, and numeral 3 indicates a holder, to which a flat piezoelectric element 1 and an auxiliary plate 12 are fixed. The bottom of the holder 3 (aluminum material) is shaped like a parabolic gutter, and its focal point is shown in Figure 3 (A) (
As in (b), a line is set between the two piezoelectric elements 1. The acoustic energy emitted from the piezoelectric element 1 is reflected by the reflection plate 2, and then concentrated on the slit b to eject ink droplets 8.

At this time, an electric field can be applied to the ink having an electrorheological effect by an electrode 4, and by applying a voltage pulse to the electrode 4, the ejection location and timing of the ink droplet 8 can be controlled. ing. Note that 18 is an ink injection port, and the injection port 18 is connected to an external ink tank (not shown).

On the other hand, there is an air chamber 15 between the piezoelectric element 1 and the auxiliary plate 12, and the air injected from the air inlet 17, 17' passes through the air chamber 15 and escapes upward from the auxiliary slit 13. This air flow 14 causes the ink droplets 8 to always be ejected vertically from the slit b. Therefore, clear printing can be performed without the droplet ejecting direction being disturbed and being ejected obliquely to the slit as in the conventional case.

In the embodiment, if the air flow velocity flowing out from the air chamber 15 to the auxiliary slit 13 is about 5 m/s or less, it is not effective in improving the jetting direction of ink droplets (and about 100 m/s).
If the temperature exceeds s, the ink will be ejected only by the air flow. Therefore, the air flow velocity is approximately 5 m/s to 100 m/s
It is desirable that it be within the range of . Further, the thickness of the air chamber 15 was approximately 200 μm.

FIG. 2 is an explanatory diagram of another embodiment of the present invention.

In FIG. 2, 19 is an electrode substrate, 20 is an electrode, 2
1 is an electrode terminal, 22 is a gutter-shaped piezoelectric element, and piezoelectric element 2
2 was placed in the ink so that its center was on the slit between the electrodes 20. 23a and 23b are electrode terminals for piezoelectric elements, and 24a and 24b are piezoelectric element terminals.

An auxiliary slit 26 of the auxiliary plate 25 is provided above this slit, and an air chamber 27 is provided between the electrode substrate 19 and the auxiliary plate 25 to generate an air flow in the direction of the arrow.

Even with the above configuration, the ink used, the ink jetting principle, the function of the electrode 20, etc. are exactly the same as the embodiments shown in FIGS. 1(a) and 1(b), and the effects are also the same. Explanation will be omitted.

[Effects of the Invention] As explained above, according to the present invention, by providing the auxiliary slit with the auxiliary plate at the upper part of the ink ejection slit section, the ejection direction of the ink droplets is controlled by the air flow flowing through the auxiliary slit from the bottom to the top. can be aligned in one direction with good reproducibility, so high-quality printing can be performed with good reproducibility.

[Brief explanation of the drawing]

Figures 1 (A) and (B) are diagrams for explaining one embodiment of the present invention, Figure 2 is a diagram for explaining another embodiment of the present invention, and Figure 3 (A) (
B) is an explanatory diagram of a conventional nozzleless inkjet recording apparatus, and FIG. 4 is a diagram illustrating conventional liquid surface waves. In the figure, 1.22 is a piezoelectric element, 2 is a reflector, 3 is a holder, 4.20 is an electrode, 8 is an ink drop, 5&ura is, 12.25 is an auxiliary plate, 13.26 is an auxiliary slit, 14 is an air flow , 15.27 is an air chamber, 16 is an ink chamber, 17.17' is an air inlet, 18 is an ink inlet, 19 is an electrode substrate, 23a and 23b are piezoelectric element electrodes, 16 is 2t 3 is a lure 4 Bunka Sun Moon's Buya ρ 1 Kuniji Masu Gosuke's Tobigo qji C U $ 2
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Claims (1)

[Claims] Acoustic energy emitted from a piezoelectric element (1) provided on the ink liquid surface is reflected by a parabolic reflector (2) provided in the liquid and concentrated on a line on the liquid surface. to eject ink droplets (8),
The ink has an electrorheological effect, and an electric field is applied to the ink using an electrode (4) provided in the ink ejection slit (b) to control the location and timing of ink ejection. , An auxiliary slit (13) formed by an auxiliary plate (12) forming an air flow path is provided at the upper part of the ink ejection slit part (b), and an air flow (
14), the nozzle-less inkjet recording apparatus is characterized in that the flight directions of the ink droplets jetted from the ink jetting slit section (b) are aligned.