JPH0310847A - Ink jet driving device - Google Patents

Abstract

PURPOSE:To enable a beautiful letter and a beautiful pattern to be formed by a method wherein a low voltage power source which continues oscillation so that a vibrator does not jet ink, and a switching means which switches a high voltage power source to an oscillation circuit by a jetting command are provided to the oscillation circuit. CONSTITUTION:A low voltage power source LV which is likely to continue oscillation to an extent that a vibrator 7 of an oscillation circuit 6 does not jet ink 3 is left to be connected. When a high voltage power source HV capable of jetting ink sufficiently is supplied herein to the oscillation circuit 6 by a switching means 5 which switches by a jetting command 5a, since the vibrator 7 oscillates in the case of no jetting command, a vibrating width is suddenly increased, and a plurality of pulses of ink jet pressing force can be generated by an almost characteristic frequency of the vibrator. Therefore, an almost constant dot becomes capable of being formed, and a beautiful letter and a beautiful pattern can be printed out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the configuration of an inkjet drive device for a printer that controls the ejection of ink from a nozzle to print out characters, figures, etc.

[Conventional technology]

An embodiment according to the prior art will be explained with reference to FIGS. 3 and 4.

FIG. 3 is a simple cross-sectional view of a printer head used in the present invention.

1 is a nozzle plate having a nozzle 1a for ejecting ink.

2 is a frame which holds ink 3 together with the nozzle plate 1. Tanks for supplying ink are not shown, and 4 is a vibrator, for example an elastic body 4a that is also an electrode. I! It consists of a piezoelectric body 4b having strain characteristics and the other electrode 4C that applies a voltage to the piezoelectric body 4b.

Here, when the injection command shown in FIG. 4(a) is issued, the vibrator 4 is gently displaced to the right in FIG. 3, although the circuit is not shown. This is the displacement marked with - in FIG. 4(b). When the injection command disappears, the distorted piezoelectric body 4b is released and the vibrator 4 is suddenly displaced to the left in FIG. 3 and returns to the neutral point while undergoing damped vibration. This situation is shown by the displacement marked 10 in FIG. 4(b). This rapid displacement presses the ink 3 and causes it to be ejected from the nozzle.

In this way, in the past, ink was basically ejected by single-shot excitation of the vibrator 4.

[Problem to be solved by the invention]

However, with the above-mentioned conventional technology, there was a problem that beautiful prints could not be obtained due to large variations in the amount of ink ejected at one time due to variations in ink characteristics, affinity between the nozzle and ink, changes in ink surface tension, etc. .

Furthermore, the injection frequency was approximately 3 KHz at most.

Therefore, the present invention is intended to solve these problems, and its purpose is to form an oscillation circuit including the above-mentioned vibrator, and to enable appropriate control of the amount of ink to be ejected by applying multiple excitation pressures. An object of the present invention is to provide an inkjet drive device for a high-speed inkjet printer that has a response frequency of 10 KHz or more.

[Means for Solving the Problems] The inkjet drive device of the present invention has the following features.

A vibrator facing a nozzle in the ink, forming an oscillation circuit including the vibrator in an inkjet drive device that presses the ink with the vibration of the vibrator to selectively eject the ink from the nozzle. do. A low-voltage power source is connected to the vibrator of the oscillation circuit so that the oscillation continues to such an extent that the ink is not jetted, and a high-voltage power source that can jet enough ink is connected to the oscillation circuit by means of a switch that switches the high-voltage power supply with a jetting command. supply The oscillation condition is satisfied because it oscillates even when there is no injection command.

Therefore, the vibrator can rapidly increase its vibration amplitude, and the ink ejecting force of multiple lights can be generated at approximately the natural vibration frequency of the vibrator.

[Effect]

According to the above configuration of the present invention, a desired vibration amplitude of the vibrator can be obtained within a predetermined time. Therefore, the pressing force of a predetermined plurality of lights can be improved. In this way, the ink can be easily cut from the nozzle and the ink becomes evenly distributed particles, creating beautiful letters and letters.
Shapes can be formed.

〔Example〕

FIG. 1 is a diagram showing a specific circuit configuration in an embodiment of the present invention.

In the figure, 5 is a switch means for switching the high voltage power supply HV. 5a represents a switch control end or signal, and the signal is a print or injection command. 6 is an oscillation circuit. This oscillation circuit 6 oscillates at the natural frequency of the oscillator 4 shown in FIG. 3, and 7 is the equivalent of the oscillator, and 8 is a one-way element such as a diode, which disconnects the high-voltage power supply HV to the oscillation circuit 6. It supplies a low voltage power supply LV when the power supply is on. This is because the oscillation circuit 6 is kept oscillating to such an extent that no ink is ejected, and when the high-voltage power supply HV is applied, the vibrator 7 quickly reaches a predetermined vibration amplitude while satisfying the vibration conditions. If there is no low-voltage power supply LV and the system starts from a stopped state, the startup characteristics will vary greatly each time, making it impossible to obtain a high-speed response.

GND represents grounding.

FIG. 1 shows an ejection command in which the vibration amplitude of the vibrator 7 included in the oscillation circuit 6, which is oscillated by the low voltage power supply LV, is rapidly increased by applying the high voltage power supply HV to control ink jetting. It is.

Returning now, FIG. 1 will be explained in detail. Low voltage power supply L
V is about 5-30V. High voltage power supply HV is 50V~
It is 200v. Since the signal voltage of the injection command 5a is normally about 5V, the switch means 5 converts the level using an N-type transistor TR2 and resistors R1 and R2. This level-converted injection signal 5a is transferred to a P-type transistor T r
+ Gate 1i! When applied to the pole, the high voltage power supply HV can be applied to the oscillation circuit 6.

Although various types of oscillation circuit 6 can be considered, a simple drain-grounded type oscillation circuit is shown. TRI is an N-type transistor, R
3 is a source resistance, and resistors R4 and Rs provide a gate bias voltage of TR3.

The capacitors 01 and 02 are used to make the series impedance of the vibrator 7 and the coil 7 operate inductively, thereby satisfying the oscillation conditions.

FIG. 2 is a diagram showing an example of the operation of FIG. 1. Figure 2(a)
is the injection command signal, the dotted line indicates the maximum repetition period, and FIG. 2(b) shows the oscillation state of the oscillation circuit 6.
Corresponding to (a), a steady small amplitude and a large amplitude for injection are shown. tr and tf represent the rise and fall times.

Note that the natural vibration frequency of the vibrator 7 depends on the desired response frequency, but is selected within a wide range of 50 KHz to 2 MHz.

〔Effect of the invention〕

As described above, according to the present invention, it is easy to rapidly increase the vibration amplitude of the vibrator, and therefore the wave number of the ink pressing force can also be controlled by the width of the ejection command signal. It is relatively influenced by the characteristics of the constituent elements, and the desired amount of ink can be easily controlled.

Therefore, it is possible to form dots in a more or less uniform manner, and the ability to print out beautiful characters and figures is a great contribution to the industrial world.

FIG. 1 is a diagram showing a specific circuit in an embodiment of the present invention. FIG. 2 is a diagram showing the oscillation state of FIG. 1.

FIG. 3 shows a cross-sectional configuration diagram of a printer head including a vibrator that generates a pressing force for ejecting ink.

FIG. 4 is a diagram showing a conventional method of displacing a vibrator for ejecting ink.

5... Switch means 6...Oscillation circuit 7... Vibrator that's all

Claims (1)

[Claims] (1) A vibrator that faces a nozzle in the ink, and an oscillation that includes the vibrator in an inkjet drive device that presses the ink with the vibration of the vibrator and selectively ejects the ink from the nozzle. a low-voltage power source that continues to oscillate so as to prevent the vibrator from ejecting the ink in the oscillation circuit; a high-voltage power source; and a switch means for switching the high-voltage power source to the oscillation circuit in response to an ejection command; An inkjet driving device characterized in that the ejection of the ink is controlled by allowing the vibrator to rise rapidly to a predetermined amplitude.