JPH05212867A - Electrostatic ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To reduce the applied voltage to a first electrode required in order to fly an ink droplet. CONSTITUTION:A Langevin vibrator 6 applying ultrasonic vibration to the ink 4 in an ink chamber 3 is mounted on a head 1 and a high voltage pulse is applied across a rear electrode 8 and an ink nozzle 4 in the driving state of the vibrator 6 and an ink droplet is allowed to fly from a nozzle orifice 4a by the electrostatic field generated between both electrodes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic ink jet recording apparatus that ejects ink droplets by utilizing an electrostatic field.

[0002]

2. Description of the Related Art An ink jet recording apparatus has an ink chamber filled with a conductive ink and a plurality of ink ejecting portions communicating with the ink chamber, and each ink ejecting portion is provided with a first electrode. At the same time, a second electrode is provided outside the ink chamber so as to face the ink ejection ports of each ink ejection unit,
There is an electrostatic ink jet recording apparatus in which a high voltage pulse corresponding to a recording signal is applied between both electrodes and an electrostatic field generated between both electrodes causes ink droplets to fly from the ink ejection ports of each ink ejection portion. (Japanese Patent Publication Sho 61-3595
No. 3).

[0003]

However, in the electrostatic ink jet recording apparatus as described above, ink droplets cannot be ejected unless a very high voltage is applied to the first electrode, and each first It was necessary to prevent voltage leakage between the electrodes. Therefore, it is necessary to drive each of the first electrodes in a time-division manner, which requires a complicated control circuit, wiring, and the like, resulting in high cost.

An object of the present invention is to provide an electrostatic ink jet recording apparatus which can reduce the voltage applied to the first electrode required to fly an ink droplet.

[0005]

In an electrostatic ink jet recording apparatus according to the present invention, an ink chamber filled with a conductive ink, a plurality of ink ejecting portions communicating with the ink chamber,
Ultrasonic vibration applying means for ultrasonically vibrating the ink in the ink chamber, a first electrode provided in each ink ejection portion, and a second electrode provided outside the ink chamber so as to face the ink ejection port of each ink ejection portion. A high voltage pulse corresponding to a recording signal is applied between the first electrode and the second electrode while the ultrasonic vibration applying means is being driven, and an ink droplet is ejected from the ink ejection port between the two electrodes. And a high voltage pulse applying means for generating an electrostatic field.

[0006]

According to the present invention, the high voltage pulse applying means applies the high voltage pulse corresponding to the recording signal between the first electrode and the second electrode while the ultrasonic vibration applying means is driven, An electrostatic field generated between the electrodes causes ink droplets to fly from the ink ejection port.

When the ultrasonic vibration applying means is driven, the ink inside the ink chamber vibrates ultrasonically, and the ink meniscus at the ink ejection port becomes unstable.

Therefore, when a high voltage pulse is applied between the first electrode and the second electrode while the ultrasonic vibration applying means is driven, the Coulomb force locally concentrates and causes the ink droplet to fly. In that case, the voltage applied to the first electrode required to fly the ink droplet can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrostatic ink jet recording apparatus to which the present invention is applied will be described below with reference to the drawings. In this electrostatic ink jet recording apparatus, as shown in FIG.
Is provided, and ink droplets can be ejected from the head 1 toward the recording paper 2 in front of it to record on the recording paper 2.

The head 1 is formed of an insulating material in a box shape, has an ink chamber 3 formed therein, and an ink nozzle 4 as an ink ejecting portion is attached to a front portion thereof. The ink chamber 3 is opened upward and is filled with a highly conductive ink 5 having conductivity. The ink nozzle 4 is in communication with the ink chamber 3 and opens on the front surface of the head so that ink droplets can be ejected from a nozzle port 4a serving as an ink ejection port. Ink nozzle 4
Is made of a conductive material and also acts as a first electrode. A plurality of ink nozzles 4 are provided,
These are arranged side by side at a predetermined interval and insulated from each other.

The head 1 is equipped with a Langevin vibrator 6 as an ultrasonic vibration imparting means, and the Langevin vibrator 6 can vibrate the ink 5 in the ink chamber 3 by ultrasonic waves. The Langevin vibrator 6 is supported by the head 1 via a supporting means (not shown), and the oscillation part is immersed in the ink 5 in the ink chamber 3 through the upper opening 3 a of the ink chamber 3. The Langevin vibrator 6 is driven via a high frequency drive circuit 7.

The head 1 generates an electrostatic field from the nozzle opening 4a of the ink nozzle 4 to the front thereof while the Langevin vibrator 6 is driven, and the electrostatic field causes ink droplets to fly from the nozzle opening 4a toward the recording paper 2. It is designed to let you. That is, the back electrode 8 as a second electrode is provided in front of the head 1 and behind the recording paper 2 and faces the nozzle opening 4 a of the ink nozzle 4. Then, the back electrode 8 is connected to the negative electrode of the DC power source 10 and the recording signal is responded to through the high frequency pulse drive circuit 9 as the high voltage pulse applying means to the ink nozzle 4 while the Langevin vibrator 6 is driven. A positive high voltage pulse is applied so that an ink droplet is ejected from the nozzle opening 4a toward the recording paper 2 while the Langevin vibrator 6 is driven between the back electrode 8 and the ink nozzle 4. It is designed to generate an electrostatic field.

Next, the operation will be described. At the time of recording on the recording paper 2, a high voltage pulse corresponding to a recording signal is applied between the back electrode 8 and the ink nozzle 4 by the high frequency pulse driving circuit 9 while the Langevin vibrator 6 is driven, and a high voltage pulse is generated between them. The electrostatic field causes ink droplets to fly from the nozzle opening 4a toward the recording paper 2.

Here, when the Langevin vibrator 6 is driven, the ink 5 in the ink chamber 3 vibrates ultrasonically to generate the ink 5.
The ink meniscus at the nozzle opening 4a becomes unstable due to the cavitation and the vibration of bubbles generated inside.

Therefore, when a high voltage pulse is applied between the back electrode 8 and the ink nozzle 4 while the Langevin vibrator 6 is driven, the Coulomb force is locally concentrated and the efficiency of flying ink drops is increased. It works well, and the voltage applied to the ink nozzle 4 required to fly the ink droplet can be reduced. Therefore, voltage leakage between the ink nozzles 4 can be prevented, and a complicated control circuit and wiring for preventing voltage leakage as in the conventional art are not required, and the cost can be reduced.

(Experimental Example 1) Back electrode 8 and ink nozzle 4
And the distance d is 0.8 mm, the voltage applied to the back electrode 8 is -800 V, the high voltage pulse applied to the ink nozzle 4 is 2 kHz, the duty is 50%, and the driving frequency of the Langevin vibrator 6 is 30 kHz. The voltage applied to the ink nozzle 4 required to fly the ink droplet was measured when the Langevin oscillator 6 was not used and when the Langevin oscillator 6 was used.

As a result, the voltage applied to the ink nozzle 4 required to fly the ink droplet was +1100 volts when the Langevin oscillator 6 was not used, whereas it was +1000 when the Langevin oscillator 6 was used.
It was a bolt. That is, when the Langevin vibrator 6 was used, the voltage applied to the ink nozzle 4 required to fly the ink droplet was reduced by 100 volts.

(Experimental Example 2) Back electrode 8 and ink nozzle 5
The distance d, the high voltage pulse applied to the ink nozzle 5, and the driving frequency of the Langevin vibrator 6 are
Under the same conditions as above, the voltage applied to the back electrode 8 was set to -600 V, and the Langevin vibrator 6
The voltage applied to the ink nozzles 4 required to fly the ink droplets was measured when the ink was not used and when the Langevin vibrator 6 was used.

As a result, the voltage applied to the ink nozzle 4 required to fly the ink droplet was +1300 volts when the Langevin oscillator 6 was not used, whereas it was +1200 when the Langevin oscillator 6 was used.
It was a bolt. That is, also in this experimental example, when the Langevin vibrator 6 was used, the voltage applied to the ink nozzle 4 required to fly the ink droplet was reduced by 100 volts.

In the above embodiment, the Langevin vibrator 6 is used to ultrasonically vibrate the ink 5 in the ink chamber 3. However, if the ink 5 in the ink chamber 3 can be ultrasonically vibrated. For example, as shown in FIG. 2, a disk-shaped barium titanate oscillator 1 is provided on the bottom wall of the ink chamber 3.
5 may be attached to cause the ink 5 in the ink chamber 3 to vibrate ultrasonically. In this case, the barium titanate vibrator 15 can be installed not only on the bottom wall of the ink chamber 3 but also on the side wall of the ink chamber 3 or the outer circumference of the head 1 as needed, and the degree of freedom in design is improved.

[0021]

As described above, according to the electrostatic ink jet recording apparatus of the present invention, the ultrasonic vibration applying means for ultrasonically vibrating the ink in the ink chamber is provided, and the driving state of the ultrasonic vibration applying means. At this point, a high voltage pulse is applied between the first electrode and the second electrode, and the electrostatic field generated between the two electrodes causes the ink droplets to fly from the ink ejection port. It is possible to reduce the voltage applied to the first electrode required for the above, which eliminates the need for a complicated control circuit or wiring for preventing the voltage leak between the first electrodes, and has an excellent effect that the cost can be reduced. ..

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electrostatic ink jet recording apparatus to which the present invention is applied.

FIG. 2 is a sectional view of an essential part showing another embodiment.

[Explanation of symbols]

3 Ink Chamber 4 Ink Nozzle (Ink Ejection Portion, First Electrode) 4a Nozzle Port (Ejection Port) 6 Langevin Transducer (Ultrasonic Vibration Applying Means) 8 Back Electrode (Second Electrode) 9 High Frequency Pulse Drive Circuit (High Voltage pulse applying means)

Claims (1)

[Claims] 1. An ink chamber filled with a conductive ink, a plurality of ink ejecting portions communicating with the ink chamber, ultrasonic vibration applying means for ultrasonically vibrating the ink in the ink chamber, and each of the inks. A first electrode provided on the ejection portion, a second electrode provided outside the ink chamber so as to face the ink ejection port of each ink ejection portion, and the first electrode when the ultrasonic vibration applying means is driven. High voltage pulse applying means for applying a high voltage pulse corresponding to a recording signal between the first electrode and the second electrode to generate an electrostatic field for ejecting an ink droplet from the ink ejection port between the two electrodes. An electrostatic ink jet recording apparatus comprising: