JPH03293142A - Ink jet device - Google Patents

Abstract

PURPOSE:To obtain an ink jet device capable of low voltage drive and high operating efficiency by applying an electric field, the direction of which is almost perpendicular and opposite to the polarized direction of an electrostrictive element to paired electrodes 2 which apply an electric field in an almost perpendicular direction to the polarized direction. CONSTITUTION:An electrostrictive element 2 used for a ink jet device is polarized in 'P' direction, and if an electric field E is applied in a perpendicular direction to a polarized P direction between electrodes E1, E2, the element 2 causes a shear distortion. Therefore, the paired electrodes are given polarity in a polarized direction which is parallel with the plane of the electric distortion element. In addition, an electric field with the left and right side reversed is applied vertically in the polarized direction so that the element becomes displaced to apply pressure to the ink. However, a uniform field distribution is obtained as an electrode is formed on the entire displacement part. At the same time, a distance between the electrodes is minimized, so that a high field intensity can be obtained at a low voltage. As a result, an ink jet device which ensures a significantly efficient operation, and the compactness and large scale integration of an ink jet head and cost reduction due to a decreased drive voltage, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet jetting device, and more particularly to a pressure-on-demand type inkjet jetting head using an electrostrictive vibrator. For example, Infusiella 1
-Applicable to printers and plotters.

In order to increase the speed of the J1 capture-on-demand type inkjet ejection device, the nozzle is highly integrated, but the circuit that moves the head is also integrated into an IC, resulting in further integration, miniaturization, and cost reduction. Cost reduction is being promoted. Therefore, the challenges to address these issues are: - The ink ejection mechanism itself must be compact and the nozzle pitch can be reduced;
■It is important that the driving voltage and current are low and that the vibration circuit can be implemented as an IC at a low cost.

A known document describing the prior art related to the present invention is US Pat. No. 4,584,590. FIG. 9 is a diagram showing electric fields and polarization directions according to a conventional example. In the figure, 1]
- is an electrostrictive body, and 12 to 15 are electrostrictive body moving electrodes. When the electrodes 12.13 are set to negative polarity and the electrodes 14.15 are set to positive polarity, the electric field E becomes in the direction of the arrow. The central part (+ electrode part) is displaced in the direction of arrow 16 by polarizing P in a direction perpendicular to the direction of this electric field. This displacement pressurizes the ink. However, with this configuration, the electric field strength becomes weaker at the center in the thickness direction of the electrostrictive body, and the distance between the electrodes becomes longer, so a high voltage is required to obtain sufficient displacement.

The present invention was made in view of the above-mentioned circumstances.
The purpose of this invention is to provide an efficient inkjet jetting device that is capable of low-voltage operation.

In order to achieve the above object, the present invention provides (1) an on-demand inkjet ejection device including an ink pressurizing chamber having an ink inlet and an ink ejecting port, and a wall surface of the ink pressurizing chamber. an electrostrictive body constituting a part of the train body, the electrostrictive body is polarized in one direction substantially parallel to the short direction of the wall surface formed by the train body, and the electrostrictive body is shared in a direction substantially perpendicular to the polarization direction. and an electrode that applies an electric field in a direction substantially perpendicular to the polarization direction in order to vibrate the electrostrictive body in a mode, and there are two pairs of electrodes, each of which is substantially perpendicular to the polarization direction of the electrostrictive body, and whose directions are opposite to each other. (2) Of the two pairs of electrodes, the potentials on one side of the electrostrictive body are equal (vO), and one of the electrodes on the opposite side is set to Vo. (3) integrally forming the electrode on the side to which the potential (2) 0 is applied;
4) It is characterized in that the potential Vo is set to the ground level. Hereinafter, a description will be given based on embodiments of the present invention.

First, FIGS. 4(a) and 4(b) are diagrams for explaining the shear mode distortion of the electrostrictive body used in the infusiera 1 to injection device of the present invention, where 2 is the electrostrictive body, El and E2 are In the electrostrictive drive electrode, E is the electric field and its application direction, and P is the polarization and its direction. In the figure, a rectangular segment S of the electrostrictive body 2 is shown. The electrostrictive body 2 is polarized in the P direction. Referring to figure (b), between electrodes E and E2,
A potential is applied in the direction denoted by E orthogonal to the polarization direction P or in the direction shown in FIG. Comparing the diagram (a) in which no potential is applied and the diagram (b) in which the potential is applied, distortion is caused in the segment l-S in diagram (b).

That is, when an electric field E is applied in a direction perpendicular to the direction of polarization P, shear strain (shear mode strain) occurs as shown in Figure (b).
It can be seen that this can cause

FIG. 1 is a configuration diagram of an electrostrictive body used in an inkjet jetting device according to the present invention, in which 2 is an electrostrictive body, 4 is an electrostrictive body drive electrode, E is an electric field and its application direction, and P is polarization. and its direction. The electrostrictive body is polarized in a direction parallel to the plane, and two pairs of electrodes are polarized as shown in the figure, and electric fields with opposite left and right directions are applied perpendicular to the polarization direction to cause the same displacement as in the conventional example. Pressurize.

Here, in order to explain the characteristics of the electrostrictive body of the present invention, the second
A comparison with the conventional example will be made based on FIGS. (a) and (b). Figure (a) shows a conventional electrostrictive body, and Figure (b) shows an electrostrictive body of the present invention.

In the conventional device shown in the figure (,), the electric field is formed as shown by the dotted line in the figure, and the electric field strength becomes weaker at the center of the electrostrictive body in the thickness direction. Furthermore, since the distance between the electrodes becomes long, a high voltage is required to obtain sufficient displacement.

On the other hand, in the present invention shown in Figure (b), since the electrode is formed on the entire surface of the displacement part, a --like electric field distribution can be obtained. Furthermore, since the distance between the electrodes can be reduced, high electric field strength can be obtained with low voltage.

FIG. 3 is a diagram showing the electric field and polarization direction of the electrostrictive body of the present invention. The parts that cause shear strain are as explained above, but in other parts (a), (b), (c), and (d), the polarization direction and electric field direction have the relationship shown in the figure, and the direction of the long plane The mode becomes an extensional vibration mode, and parts (A) and (D) extend, and (
Parts b) and (c) are displaced in the shrinking direction. As can be seen from the figure, this results in promoting shear strain, which is the main strain, and further increases efficiency.

FIGS. 5(a) to 5(c) are diagrams for explaining the displacement of the electrostrictive body of the present invention, where FIG. 5(a) is a configuration diagram, FIG. 5(b) is a diagram showing a displacement state, and FIG. ) is an explanatory diagram for comparison with a conventional example. t is the thickness of the electrostrictive body, Ql is the length of the electrode, Q2 is the distance between the electrodes, vl is the left and right displacement volume, v2 is the displacement volume at the center, △■ is the overall displacement volume, and Q is the electrode's displacement volume. depth, δ
is the amount of displacement of the electrostrictive body, and ■ is the applied voltage. To displacement volume■
The following formula holds true for .

△V=2Vyu+■2 v2=Q, 2・δ・a 3=8,5. V,'・ Therefore, FIGS. 6(a) to (c) show the conventional electrostrictive body displacements explained for comparison with the displacement of the electrostrictive body of the present invention shown in FIGS. 5(a) to (c). FIG. 3 is a diagram showing the displacement of a strained body. Figure (a) is a configuration diagram, Figure (b) is a partial view of the left half of Figure (a), and Figure (c) is an explanatory diagram for comparison with the present invention. According to figure (c), the following formula holds true.

d is · V Therefore, the X erox method depends only on the d 15 constant of PZT and the applied voltage V, regardless of the dimensions (t, + Q).

On the other hand, in the present invention, as shown in FIG. 5(c), 6-d
,5. V, Q. Therefore, if the same PZT material and applied voltage are used, a larger displacement than the above-mentioned Xerox method can be obtained by setting Ω,>t. Therefore, the driving voltage can be reduced when obtaining the same displacement.

FIGS. 7(a) and 7(b) are diagrams showing the Infusiera 1-injection device of the present invention, where FIG. 7(a) is a plan view and FIG. 7(b) is a diagram (
It is a sectional view taken along ■-■ of a). 1 is a housing of an ink pressurizing chamber, 2 is an electrostrictive body, 3a to 3c are ink pressurizing chambers, 4-1
a to 4-40 are electrostrictive body electrodes, 5 is a counter block, 6 is an insulating seal body, 7a and 7b are bonding layers, 8a to 8C
is an ink jetting port, and 98 to 9c are ink inlets.

The ejecting device has a single electrostrictive body 2 for driving three ink ejecting ports. The electrostrictive body 2 has electrodes 4-1a to 4-40 formed on its surface, and is attached to the housing of the electrostrictive body 2 and the ink pressurizing chamber. The housing 1 has three ink pressurizing chambers 38 to 3C formed therein, and the ink pressurizing chambers 3a to 3C.
3G is connected to ink jet ports 88 to 8c. The ink source communicates with the ink pressurizing chambers 3a-3c via ink inlets 98-9c. This ink pressurizing chamber 38~
3c and the housing 1 are connected to the electrostrictive body 2 by the insulating seal body 6.
is separated from. The counter block 5 is attached to the opposite surface of the electrostrictive body 2.

FIG. 8 is an example of the ejection control of the inkjet ejection apparatus according to the present invention. In the figure, 10 is a controller, and other parts having the same functions as in FIG. 7 are given the same reference numerals.

Controller 1. O connects the power source and the electrostrictive drive electrode. The state shown in the figure is when the power is turned off, but when the switch S is turned on and the power is turned on, the electrode 4-L
a, 4-1b, 4-1c have a negative potential, and electrode 4
A positive potential is applied to -3a, 4-3b, and 4-3c, and a displacement as shown in FIG. 3 is obtained.

As is clear from the above explanation, the present invention is significantly more efficient than the conventional example, and has a great effect on the miniaturization and high integration of the head and the reduction of drive voltage, resulting in low-cost IC implementation. bring.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an electrostrictive body used in an inkjet jetting apparatus according to the present invention, and FIG. 2(a). (b) is a diagram for explaining the characteristic points of the electrostrictive body of the present invention. Figure (a) is a conventional example, Figure (b) is a diagram showing an example of the present invention, and Figure 3 is a diagram showing the example of the present invention. FIGS. 4(a) and 4(b) are diagrams showing the electric field and polarization direction of the electrostrictive body of the present invention, and FIGS. Figures (a) to (c) are diagrams for explaining the displacement of the electrostrictive body of the present invention, and Figures 6 (a) to (c) are
Diagram for explaining the displacement of a conventional electrostrictive body, FIG. 7(a)
, (b) are diagrams showing the inkjet jetting device of the present invention. Figure 1 (a) is a plan view, Figure (b) is a sectional view taken along line nn of Figure (a), and Figure 8 is an inkjet spraying device according to the present invention. FIG. 9, which is a diagram showing an example of injection control of an injection device, is a diagram showing the electric field and polarization direction of a conventional electrostrictive body. ]-- Housing of ink pressurizing chamber, 2... Electrostrictive body,
3a to 3c... ink pressure chamber, 4-1a to 4-40.
・Electrostrictive moving electrode, 5... Counter block, 6...
Insulating seal body, 7a, 7b... bonding layer, 8a, 8c...
...Ink jet port, 98~9G...Ink inlet, 1
0 controller.

Claims (1)

[Claims] 1. In an on-demand inkjet jetting device,
an ink pressurizing chamber having an ink inlet and an ink ejection port;
an electrostrictive body constituting a part of the wall surface of the ink pressurizing chamber; the electrostrictive body is polarized in one direction substantially parallel to the short direction of the wall surface formed by the electrostrictive body; It has an electrode that applies an electric field in a direction substantially perpendicular to the polarization direction in order to vibrate in a shear mode in a direction substantially perpendicular to the polarization direction, and the electrode has two
An inkjet ejecting apparatus characterized in that there are a pair of electrostrictive bodies, each of which applies an electric field substantially perpendicular to the polarization direction of the electrostrictive body and opposite in direction.