JPH0452214B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an ink-on-demand jet, and more particularly to energy conversion means for a multi-nozzle head in which a large number of nozzles are integrated.

[Prior art]

2. Description of the Related Art Conventionally, as an image recording apparatus using dielectric ink, one disclosed in Japanese Patent Application Laid-Open No. 58-94480 is known. This image recording apparatus utilizes the fact that a voltage is applied between electrodes filled with dielectric ink, and the dielectric ink moves under force in a direction in which electrostatic energy between the electrodes increases.

However, this image recording device balances the weight of the dielectric ink and electrostatic force between parallel plate electrodes arranged vertically, and has low responsiveness and is greatly affected by capillary suction force. It was also impossible to tilt the recording device, which caused the problem that the recording device became larger.

〔the purpose〕

Therefore, the object of the present invention is to solve the above problems,
An object of the present invention is to provide a small inkjet head with high responsiveness.

〔Features〕

The present invention uses a liquid ink with a high dielectric constant,
Electrodes are placed opposite the wall of the pressure chamber containing liquid ink, and a voltage is applied between the electrodes to generate electrostatic force between the electrodes, which causes the wall of the pressure chamber to bend. , the ink is pressurized and ejected from a nozzle to record on a recording medium.

〔composition〕

FIG. 1 shows an embodiment of the present invention. Reference numeral 1 denotes a substrate made by injection molding of polysulfon, on the surface of which a pressure chamber 2, a nozzle 3, and a supply path 4 are formed as grooves, and furthermore, an electrode 5 is formed on the bottom surface of the pressure chamber 2 by sputtering. Reference numeral 6 denotes a polysulfon film diaphragm, and an electrode 7 is formed on the lower surface by sputtering. Wirings 8 and 9 are connected to the electrodes 5 and 7 and are connected to a drive circuit (not shown). 10 is a supply pipe that communicates the supply path 4 and the ink container 11. 12 is a liquid ink containing formamide as a main component.

In the above configuration, signals from a drive circuit (not shown) are applied to the electrodes 5 and 7 via the wirings 8 and 9. The voltage applied to the electrodes 5 and 7 is V,
V, distances d and m, and charges q and C, the forces F and N acting between the electrodes 5 and 7 are expressed as F=Vq/d... Here, the charge q is the electric capacitance C, F
It is expressed as q=CV... In addition, the electric capacitance C is the relative dielectric constant εs of the ink 12, and the dielectric constant ε ₀ of the vacuum = 8.9×10 ^-12 (F/
m) and the opposing area A (m ² ) of the electrodes 5 and 7, it is expressed as C=εsε ₀ A/d . On the other hand, pressure (Pα) is expressed as =F/A... Therefore, the pressure acting on the electrodes 5 and 7 is
The equations are collectively expressed as =εsε ₀ V ² /d ² ....

The pressure required for ink ejection is generally about 0.5×10 ⁵
(Pα), d = 10 (μm), εs of formamide
=109, it can be seen that ink can be ejected at V=72 (V).

The wall thickness of the pressure chamber portion of the substrate 1 and the diaphragm 6 is as follows:
In order to effectively use the added electrical energy to pressurize the ink, it must be as thin as 30μ, preferably
Desirably less than 10μ.

FIG. 2 shows a cross-sectional view taken along line A--A of the embodiment shown in FIG. The electrode 7 is connected to the pressure chambers 2-1, 2-2...
The electrodes 5 are provided in common to each pressure chamber, whereas the electrodes 5 are provided independently corresponding to each pressure chamber 5-1, 5-2, and 5-3. In this example, electrode 5
A voltage is applied between the pressure chamber 2-1 and the electrode 7.
The volume of the nozzle is reduced, and ink is ejected only from the nozzle corresponding to this volume. Here, the width of the pressure chamber ω ₁ is 70 μm, the width of the throat ω ₂ is 30 μm, and each pressure chamber is
The nozzles are arranged at a density of 10 nozzles/mm.
The density is books/mm.

As can be seen from the embodiments described above, according to the present invention, since ink with a high dielectric constant is used and electrodes are simply provided above and below the pressure chambers, the pressure chambers can be arranged in high density, and therefore the nozzle can be Can be highly integrated.

In addition, since the structure is only a substrate, a diaphragm, and electrodes arranged on each, it is extremely simple compared to a conventional piezoelectric element, and is highly mass-producible, making it possible to obtain a low-cost head.

FIG. 3 shows another embodiment of the invention. In this example, electrodes 5-1, 5-2 and electrode 7 are provided on the outer wall surface of pressure chamber 2. Further, the substrate 1 and the diaphragm 6 are extremely thin, about 1 μm. Therefore, the apparent dielectric constant does not drop that much, and since there are electrodes on the outside, it is easy to connect to a drive source, and the assembly is easy, as the substrate 1 and the diaphragm 6 can be bonded with solvent. There are also fewer problems such as the electrodes peeling off due to Furthermore, if the dielectric constant is increased by mixing a high dielectric material into the substrate 1 and the diaphragm 6, voltage loss can be reduced.

In the above embodiments, an example of an ink containing formamide as a main component was given, but glyconitrile, succinonitrile, P-nitroaniline, water, etc. also have a dielectric constant of 50 or more and can be considered as components of the ink. However, in the case of water, electrolysis occurs when voltage is applied, and the withstand voltage is low. The formamide of the example shown in FIG. 1 does not have such problems and is suitable as an ink component of the present invention.

Note that by ultrafinely pulverizing high dielectric substances such as barium titanate and PZT and diffusing them into the ink, it is possible to increase the dielectric constant of the ink and lower the driving voltage. In this case, it is necessary to make the diameter of the fine powder extremely small in order to avoid adverse effects such as clogging, and to prevent agglomeration by surface treatment.

Alternatively, the dielectric polymer material can be diffused into ink, adhered to a recording medium, and then heated and melted to be fixed on the recording medium.

〔effect〕

According to the present invention, an ink having a high dielectric constant,
A substrate is provided on one side, a diaphragm is provided on the other side, a pressure chamber is filled with an electrode on each side, and a voltage is applied between the electrodes to change the volume of the pressure chamber and eject ink, which improves responsiveness. Moreover, since there is no piezoelectric element, it has the effect of realizing a compact ink jet head.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, FIG. 2 is a sectional view taken along line A-A of the embodiment of FIG. 1, and FIG. 3 is a sectional view of another embodiment of the invention. 1...Substrate, 2...Pressure chamber, 3...Nozzle, 4
... Supply channel, 5, 7 ... Electrode, 12 ... Liquid ink.

Claims (1)

[Claims] 1. A pressure chamber filled with liquid ink having a high dielectric constant and provided with a substrate on one side and a diaphragm on the opposite side, each provided with an electrode; a nozzle communicating with the pressure chamber; An ink jet head comprising: a structure in which the ink is ejected from the nozzle by applying a voltage between the electrodes to change the volume of the pressure chamber.