JPS5814758A - Exciting method for ink injection head - Google Patents

Abstract

PURPOSE:To improve the characteristics of granulation by bringing a position corresponding to a node in the higher harmonic mode of the excitation frequency of an electrostrictive vibrator to the condition of non-electrode or non-polarization and forcedly inducing higher harmonic vibration. CONSTITUTION:The electrodes 17a, 17b, 17c of an ultrasonic vibrator are insulated and split at the point of the node of the third higher harmonic mode of the electrostrictive vibrator 16. Consequently, excitation in the third higher harmonic mode 3fo is easily generated even when the ultrasonic vibrator is being excited in a fundamental mode fo, these synthetic vibration is transmitted to ink in the head as the result of the excitation, the nonlinearity of a fluid is corrected, and the generation of a satellite can be suppressed. Since not only the third higher harmonic but also the second, the fourth and the fifth higher harmonics are synthesized even when the electrostrictive vibrator 26 is being driven by the fundamental harmonic fo in the ink injection head formed in this manner, the characteristics of granulation are improved, and a printing region can be expanded.

Description

[Detailed description of the invention] This invention relates to a method for exciting an ink jet head.

Conventionally, the configuration shown in FIG. 1 has been known as a device for causing an electrostrictive vibrator to ultrasonically vibrate in a non-sinusoidal manner (see Japanese Patent Publication No. 55-35920). In FIG. 1, 1, 2.3 are electrostrictive vibrators with different resonance frequencies, 4, 5, 6, 'i', 8. 9 are electrostrictive vibrators 1, 2, respectively. 3 electrode, 10.11 is electrode 5
, 6 and 7.8 respectively, and
The electrostrictive vibrators 1, 2.3 are integrated while being electrically separated. Moreover, the electrodes 4, 5, of the electrostrictive vibrator 1, 2.3,
6, 'i', 8. 9 is input terminal 12, 13
, 14.

15, and is configured to input an excitation signal having a resonant frequency of each electrostrictive vibrator at an arbitrary amplitude.

The conventional ultrasonic vibrating device configured in this manner requires a plurality of electrostrictive vibrators and the same number of driving sources for driving the electrostrictive vibrators, which has the disadvantage of increasing costs. In addition, since each vibrator 1, 2.3 is used in a resonance mode, its shape becomes extremely large at a low driving frequency, and conversely, its shape becomes small at a high driving frequency, so the frequency range in which it can be used is inevitably limited. However, it was not suitable for broadband ultrasonic vibration. Furthermore, the resonant frequency shifts due to changes in environmental temperature or deterioration, and as a result, the amplitude of the ultrasonic vibration decreases, but at this time, since each resonant frequency is not constant, the resultant vibration mode may not match the intended one. The disadvantage was that it was significantly different.

In order to eliminate the drawbacks of the conventional example described above, the present invention forcibly induces harmonic vibration by making the portion corresponding to the node in the harmonic mode of the excitation frequency of the electrostrictive vibrator into a non-electrode or non-polarized state. Its purpose is to improve the atomization characteristics of an inkjet printing device and expand the printable area by making the electrostrictive vibrator of the inkjet head undergo complex vibration in a practical manner with a simple configuration. The present invention provides a method for exciting an ink ejecting head.

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 2 is a diagram showing the vibration mode of a conventional general ultrasonic vibrator, where 16 is an electrostrictive vibrator, l'i', and 1B are electrodes, and the excitation mode of this electrostrictive vibrator 16 is Mode f with nodes at both ends. Or mode f with the node in the center. The fundamental wave oscillates at ′. When both ends of the electrostrictive vibrator 16 are forcibly fixed in order to support it, the mode f/ is suppressed and the mode f becomes an antinode at the center. dominates the excitation. When applied to excite the ink jet head in such a state, the ink in the ink jet head is in mode f. Since the non-linearity of the fluid is not corrected, satellites are likely to occur in areas where the vibration level is low.

Therefore, in the present invention, the electrodes of the ultrasonic transducer are insulated and divided at the nodes of the third harmonic mode.

That is, FIG. 3 shows a cross-sectional view and a plan view of a rectangular ultrasonic transducer according to an embodiment of the present invention, in which 16 is an electrostrictive transducer, 1'Ia, 1'7h, 17c, and 1B are electrodes, and the electrodes l'7a, 17b, and 1'7c are the third electrodes.
It is insulated and divided at the node of harmonic mode 3fo.

FIG. 4 shows a cross-sectional view of a circular ultrasonic transducer according to another embodiment of the present invention, in which 19 is an electrostrictive transducer, 20.
Reference numeral 21 denotes an electrode, and the electrode 20°2 is similar to the previous embodiment.
1 is insulated and adjacent to the node of the third harmonic mode 3fo.

In the ultrasonic transducer configured as shown in FIGS. 3 and 4, the fundamental wave mode f. Even if the ink is excited in the head, excitation in the third harmonic mode 3fo also easily occurs, and as a result, these combined vibrations are transmitted to the ink in the head, and as a result, the nonlinearity of the fluid is corrected. The generation of satellites can be suppressed. .

FIG. 5 shows a sectional view of an ink jet head equipped with an ultrasonic vibrator according to an embodiment of the present invention, in which 22 is a head, 23 is an orifice, 24 is a diaphragm, and 25 is a diaphragm 23.
26 is an electrostrictive vibrator bonded to the electrode 25; 27a, 2'7b, 2'7c are electrodes bonded to the electrostrictive vibrator 26; 28 is an excitation section;
7a, 2''7b, and 2'7c are electrically connected to the excitation section 28.

In the ink jet head configured in this way, the electrostrictive vibrator 26 has a fundamental wave f. Although it is driven by
Harmonic components are also synthesized. Also, in this case, the third
Not only harmonics but also second, fourth and fifth harmonics can be considered in exactly the same way, and can be achieved extremely easily.

In addition, in the explanation of the above example, the electrodes were divided, but in addition to this, the node portions of the electrostrictive vibrator may be partially heated using a laser beam or an electromagnetic beam to partially change the polarization. It may be destroyed or the electrode itself may be dissolved to provide a node function.

As explained above, according to the present invention, harmonic vibrations are forcibly induced by placing the portions corresponding to the nodes in the harmonic mode of the excitation frequency of the electrostrictive vibrator in a non-electrode or non-polarized state. The excitation of the ink jet head can be made into complex vibrations, so that the atomization characteristics of the ink jet printing device are improved, the printable area is expanded, and the structure is simple and practical.

[Brief explanation of drawings]

Fig. 1 is a side view of a conventional ultrasonic vibration device, and Fig. 2 is a side view of a conventional ultrasonic vibration device.
FIG. 3 is a sectional view and a plan view of an ultrasonic transducer according to an embodiment of the present invention, and FIG. 4 is a sectional view of a conventional ultrasonic transducer according to another embodiment of the present invention. A cross-sectional view, a side cross-sectional view, and FIG. 5 are cross-sectional views of an ink jet head equipped with an ultrasonic vibrator of the present invention. 16. 19... Electrostrictive vibrator, 17α, 17b,
17C, 1B. 20, 21... Electrode, 22... Head, 23...
... Orifice, 24 ... Vibration plate, 25 ... Electrode,
26... Electrostrictive vibrator, 27αr 2'lb, 2'
7c... Electrode, 28... Excitation part. Figure 1 Figure 4 Figure 3 Figure 5 Figure 2

Claims (1)

[Claims] 1. A method for exciting an ink ejecting head, the method comprising: forcibly inducing harmonic vibration by making a portion corresponding to a node in a harmonic mode of an excitation frequency of an electrostrictive vibrator into a non-electrode or non-polarized state.