JPH0338348A - Inkjet recording apparatus - Google Patents

Abstract

PURPOSE:To remove electrode reaction, while simplifying a circuit, improving the reliability and making it easy to detach a signal electrode, by impressing a constant voltage to a first electrode at the outer surface of an air nozzle plate and a second electrode within the ink and impressing a signal voltage to a third electrode at the rear surface of said air nozzle plate. CONSTITUTION:When the ink is discharged, the potential difference between a first electrode 11 and a second electrode 12 is 1000V. Since a voltage decrease of 400V is found at the rear side of an air nozzle plate 2, ink can be discharged by impressing 600V between a third electrode 13 and the second electrode 12. When the ink is not discharged, the potential difference of approximately 550V is set between the third electrode 13 and second electrode 12 in consideration of the stability when recording is not performed. Accordingly, if the signal voltage of 100V is given to the third electrode 13, it will invite the discharge of the ink. The signal voltage can be rendered small. When recording is not performed, a constant voltage, namely, OV and +550V are applied to the third electrode 13 and second electrode 12, respectively. When recording is performed, a signal voltage of a rectangular wave of -100V is given to the third electrode 13. The voltage applied to the second electrode 12 as an electrode within the ink is always constant, so that no electrode reaction is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inkgeno-recording device that records characters, images, etc. on a non-recorded object by ejecting ink from a minute opening.

2. Description of the Related Art Conventionally, as an inkjet recording device that uses airflow and electrostatic force to eject ink from a minute opening, a configuration such as that described in Japanese Patent Application Laid-Open No. 57-120452 has been known. There is. Hereinafter, a conventional inkjet recording apparatus will be explained with reference to FIG. An air nozzle plate 102 made of an insulating material is attached to the tip of the outer wall of the body member 101, an ink nozzle plate 103 made of an insulating material is attached to the tip of the inner wall, and an air chamber 104 is formed on the exterior and inner wall of the body member 101. and air nozzle plate 1
An air flow path 105 communicating with the air chamber 104 is formed between the ink nozzle plate 103 and the ink nozzle plate 103.
An ink chamber 106 is formed inside. The ink nozzle plate 103 has an ink discharge port 107 formed therein, and the air nozzle plate 102 has an air discharge port 108 formed opposite to the ink discharge port 107 . An electrode 109 is provided on the outer surface of the air nozzle plate 102 at the outer periphery of the air outlet 108 . The air chamber 104 is communicated with an air supply source (not shown) through an air supply pipe 110, and the ink chamber 106 is communicated with an ink supply source (not shown) through an ink supply pipe 111 made of a conductive material.

Next, the above conventional example will be explained. An air flow is sent from an air supply source to the air chamber 104, and flows out into the air flow path 105 at a constant flow rate as an air layer while making a sharp bend. air outlet 10 while making a sharp bend.
It is leaking from 8.

On the other hand, the ink chamber 106 is constantly filled with ink from the ink supply source, and a constant pressure is applied to the ink supply source and the ink in the ink chamber 106 by air pressure sent from the air supply source. As a result, when the inkjet recording device is not recording, the air pressure near the ink ejection port 107 generated by the air flow and the ink pressure inside the ink ejection port 107 are approximately equal, and the ink meniscus generated at the ink ejection port 107 is kept stationary. ing. And electrode 1
When a potential difference is created between the ink supply tube 111 and the ink supply pipe 111, the meniscus of ink generated at the ink discharge port 107 is stretched in the direction of the air discharge port 108 due to the electrostatic force caused by this potential difference. Since the air flow path 105 from the ink discharge port 107 to the air discharge port 108 has a rapid change in pressure gradient caused by the air flow, the ink discharge port 107
When the ink meniscus is stretched beyond a certain length, it is rapidly accelerated and ejected from the air ejection port 108.

In actuality, considering the characteristics of the inkjet recording head, such as the responsiveness and ejection amount, the electrode 1 is
In 09, a negative bias voltage (2) is applied to the ink electrode of b1, and a positive rectangular waveform signal voltage VS is applied to the ink electrode. The bias voltage yb makes the ink meniscus at the ink ejection port 107 slightly convex so that ink can be easily ejected. As shown in FIG. 3(b), the bias voltage Vb-soov1 signal voltage VS is set to 500.

However, in the driving voltage of the inkjet recording head as in the conventional example, the bias voltage applied to the electrode 109 is
b is -500V, and the signal voltage VS applied to the ink supply tube 111, that is, the ink, is +500V, which is high as a driving voltage. In particular, since the signal voltage VS is a high voltage with a rectangular waveform, the electric circuit becomes large-scale and expensive.

If the driving voltage is high, there is a risk of loss due to discharge of the inkjet recording head, and there is a problem with reliability.

As a solution to the above problems, for example, JP-A-62
A configuration as described in Japanese Patent No. 39251 is known. The explanation will be given below with reference to FIGS. 4(a) and 4(b).As shown in FIG.
An air nozzle plate 102 made of insulating material is attached to the tip of the outer wall of the ink nozzle plate 102, and an ink nozzle plate 103 made of insulating material is attached to the tip of the inner wall.
An air flow path 105 communicating with the air chamber 104 is formed between the ink nozzle plate 103 and the ink chamber 106.
is formed. The ink nozzle plate 103 has an ink discharge port 107 formed therein, and the air nozzle plate 102 has an air discharge port 108 formed therein opposite to the ink discharge port 107 . The air chamber 104 is communicated with an air supply source (not shown) through an air supply pipe 110, and the ink chamber 106 is communicated with an ink supply source (not shown) through an ink supply pipe 111 made of a conductive material. An electrode 112 is provided on the outer surface of the air nozzle plate 102 at the outer periphery of the air outlet 108,
An electrode 113 is provided on the inner surface of the air nozzle plate 102 on the outer periphery of the air passage 105 near the air outlet 108 .

Then, negative bias voltages (DC) Vb and yb4 are applied to the electrodes 111 and 113, respectively, and a positive voltage VS is applied to the ink through the ink supply pipe 111.
is applied, and the relationship is set to be 1Vbl>VSI>lVb'l in absolute value.

Next, the operation of the above configuration will be explained. The principle of ink ejection is the same as that shown in FIG. 3, so the details thereof will be omitted. In the above configuration, the electrode 113 draws ink from the ink ejection port 107 and guides it to the ejection state, and the electrode 111 draws ink from the air ejection port 107.
08 can be discharged outward. Therefore electrode 1
The electrostatic force caused by the ink discharge port 107
The ink can be concentrated and the ink can be easily ejected.

Problems to be Solved by the Invention However, in the inkjet recording head such as the conventional example described above, the signal voltage is applied to the electrode in the ink, so even if the signal voltage is lowered, the voltage is still as high as +250 to +300. Furthermore, in the case of a multi-nozzle recording head, since a rectangular wave voltage is applied to the ink electrodes, an electrode reaction occurs between the ink electrodes.

Therefore, the present invention lowers the signal voltage, makes the voltage applied to the electrode in the ink constant, eliminates electrode reaction, simplifies the circuit and improves reliability, and furthermore, makes it possible to easily take out the signal electrode. The purpose of this invention is to provide an inkjet recording device that achieves this.

Means for Solving the Problems And the means of the present invention for solving the above problems are as follows:
A first electrode on the outer surface side of the air nozzle plate and a second electrode inside the ink.
A constant voltage is applied to the third electrode on the back surface of the air nozzle plate, and a signal voltage is applied to the third electrode on the back surface of the air nozzle plate.

action The effects of the above technical means are as follows.

That is, when a constant voltage is applied to the first electrode to prevent ink from being ejected, and when a constant potential difference is provided between the second and third electrodes, which is slightly lower than the potential difference at which ink is ejected, ink is ejected. By applying a signal voltage to the third electrode, ink can be ejected efficiently with a low signal voltage.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

Figure 1! The structure of the present invention is shown in al. Ink ejection principle,
The recording throat configuration is the same as that shown in FIG. 4 (al) above, so its details will be omitted.

FIG. 1 (bl indicates the potential and signal voltage applied to the first to third electrodes.

When compared with the conventional example shown in FIG. 3 without the third electrode 13, the first electrode 11 and the second electrode 1 are connected to each other during ink ejection.
2 is 100OV, and due to the structure, there is a voltage drop of 400V on the back side of the air nozzle plate 2, so the potential difference between the back side of the air nozzle plate 2 and the third electrode 13 is 600V.
It is. That is, if 600V is applied between the third electrode 13 and the second electrode 12, ink will be ejected. Therefore, a potential difference smaller than 600 V must be provided between the third electrode 13 and the second electrode 12 when ink is not ejected. Considering stability during non-recording, a potential difference of about 550V is appropriate. In this state, if a signal voltage change of 100 cm is applied to the third electrode 13, ink will be ejected. Therefore, the signal voltage can be reduced. Considering the simplification and reliability of the signal drive circuit, the voltage of the third electrode 13 is OV1 during non-recording.
A constant voltage of +550 V is applied to the V2O3 electrode 12, and a rectangular signal voltage of -100 V is preferably applied to the third electrode 13 during recording. Since a constant voltage is always applied to the second electrode 12 as an ink electrode, no electrode reaction occurs.

Air flow also plays a role in the stable ejection of ink.
Acceleration due to electric field distribution in the air nozzle is also important. In other words, a certain amount of potential difference is required between the first electrode 11 and the second electrode 12 during ink ejection. Since the potential difference between the front side and the back side of the air nozzle during recording is 400 cm, the same potential difference as this condition is provided, and a constant voltage of -4 is applied to the first electrode 11.
Apply 00V.

This reduces the signal potential difference from the conventional 500 V to 100 V.
I was able to lower it to V.

In the above example, the voltage is applied with negative voltage applied to the air nozzle side and positive voltage applied to the ink side, but it is also possible to apply voltage positive voltage to the air nozzle side and negative voltage applied to the ink nozzle side. Furthermore, if the third electrode 13 and the second electrode 12 are as close as possible, the response speed will be faster and the voltage loss will be less. Therefore, the second electrode 12 can be provided on the inner surface of the ink nozzle plate 3 preferable.

Furthermore, if multiple ink nozzles and air nozzles are provided, the third electrode 13 is divided corresponding to each nozzle, and independent signals are given to each of the divided third electrodes, ink can be ejected in accordance with each signal. A multi-nozzle inkjet recording head can be easily created.

Effects of the Invention As explained above, according to the present invention, the signal voltage is applied to the electrode on the back side of the air nozzle plate, so the signal voltage only needs to be small, and the voltage applied to the ink electrode can be kept constant. , electrode reactions can be eliminated, simplifying the circuit and improving reliability.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view showing an embodiment of the inkjet recording apparatus of the present invention, FIG. 1(b) is a driving voltage waveform diagram thereof,
FIG. 2 is a sectional view showing an example of a conventional inkjet recording apparatus, FIG. 3(a) is a sectional view for explaining the driving voltage of the inkjet recording apparatus of FIG. FIG. 4 (Al is a sectional view showing another example of a conventional inkjet recording device, and FIG. 4F is an explanatory diagram of the driving voltage. 2... Air nozzle plate, 3... Ink nozzle plate, 7)・
Ink discharge port, 8...Air discharge port, 11...First electrode, 12...Second electrode, 13...Third electrode.

Claims (1)

[Claims] (1) an ink nozzle plate having an ink discharge port, an air nozzle plate having an air discharge port opposite to the ink discharge port, and an ink chamber disposed adjacent to the ink discharge port;
means for causing an air flow to flow out from the air outlet through an air flow path formed in a gap between the ink nozzle plate and the air nozzle plate; and means arranged on the outer surface of the air nozzle plate surrounding the air outlet. a second electrode in contact with the ink in the ink chamber; and a third electrode disposed on the inner surface of the air nozzle plate surrounding the air discharge port; and a second electrode, and a signal voltage is applied to the third electrode.