JPS6239251A - Inkjet recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an inkjet recording apparatus that records characters, images, etc. on a recording material by ejecting ink from minute openings.

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,
An air chamber 104 is formed between the outer wall and inner wall of the body member 101, and an air nozzle plate 102 and an ink nozzle plate 1030 are formed between the outer wall and the inner wall of the body member 101.
An air passage 105 communicating with the air chamber 104 is formed therebetween, and an ink chamber 106 is formed inside the ink nozzle plate 103. An ink nozzle plate 1.031']-t inter-discharge port j07 is formed, and an air discharge port 108 is formed in the air nozzle plate 102 opposite to the ink discharge port 107. Air discharge ports 10 are provided on the outer surface of the air nozzle plate 102.
An electrode 109 is provided on the outer periphery of 8. 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 (v@, not shown) through an ink supply pipe 111 made of a conductive material. The electrode 109 and the ink supply tube 111 are connected to the signal source 11
Connected to 2.

Next, the above conventional example will be explained. Air 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.
This air flows out from the air outlet 108 while making a sharp bend near the air outlet 108 and the ink outlet 107 . On the other hand, the ink chamber 106H 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 the 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 caused by the air flow and the ink ejection port 10 are reduced.
Since the ink pressure within the ink discharge port 107 is approximately equal, the ink meniscus generated at the ink ejection port 107 is kept stationary. When a potential difference is generated between the electric potential 109 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. Ink discharge port 107
Since the air flow path 105 leading to the air outlet 108 undergoes a rapid change in pressure gradient due to the air flow, when the ink meniscus at the ink outlet 107 is stretched beyond a certain length, it is rapidly accelerated and the air It is discharged from the discharge port 108.

Actually, taking into consideration the characteristics of the inkjet recording head such as responsiveness and ejection amount, a negative bias electrode vb is attached to the 1i pole 109 as shown in FIG.

A positive rectangular waveform signal voltage V8 is applied to the ink supply pipe 111.
Apply. Bias voltage vb\'i, ink ejection port 1
The ink meniscus at 07 is slightly convex. The actual driving voltages are set to bias voltage vb=-soov and signal voltage Vs=+500V, as shown in FIG. 3(b).

Problems to be Solved by the Invention However, in the form of the driving voltage of the inkjet recording head as in the conventional example described above, the bias voltage Vb or -500V applied to the electrode 109 and the signal voltage applied to the ink supply tube 411, that is, the ink, are Vs is +500v, which is a high 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 damage to the inkjet recording head due to discharge, and there is a problem with reliability.

Therefore, the present invention lowers the signal voltage applied to the ink, thereby reducing the size and cost of the electric circuit, as well as preventing the risk of damage due to discharge and improving reliability. Furthermore, it is an object of the present invention to provide an inkjet recording apparatus that can increase the amount of ink ejected to improve recording density.

Means for Solving the Problems and Technical Means of the present invention for solving the above-mentioned problems are a tenth air nozzle plate provided on the surface side of an air nozzle plate having an air ejection port opposite to the ink ejection port. Regret, 1 sadness, LSj
, q difficult scale - 1 η ahead of 1 Negative voltages Vb and Vb' are applied to the electrodes, respectively, and a positive voltage Vs is applied to the ink, so that the absolute value is lVb l>IVs l
>lVb'l.

For production The effects of the above technical means are as follows.

That is, the second electrode can draw out ink from the ink discharge port, and the first electrode can discharge the ink to the outside of the air discharge port. By using the second electrode in this way, the electrostatic force can be more efficiently concentrated on the ink at the ink ejection port, and therefore the signal voltage applied to the ink can be lowered, and the amount of ink ejected can be increased. be able to.

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

As shown in FIG. 1(,), an air nozzle plate 2 made of insulating material is attached to the tip of the outer wall of body member 1, and an ink nozzle plate 3 made of insulating material is attached to the tip of the inner wall. An air chamber 4 is formed between the outer wall and the inner wall, an air passage 5 communicating with the air chamber 4 is formed between the air nozzle plate 2 and the ink nozzle plate 3, and an ink chamber 6 is formed inside the ink nozzle plate a. It is formed. An ink discharge lower is formed in the ink nozzle plate 3, and an air discharge port e is formed in the air nozzle plate 2 facing the ink discharge lower.

The air chamber 4 is supplied with air by an air supply pipe 9 (not shown)
The ink chamber 6 is connected to an ink supply pipe 10 made of a conductive material.
The ink supply source (not shown) is communicated with the ink supply source (not shown). A first electrode 11 is provided on the outer surface of the air nozzle plate 2 at the outer periphery of the air outlet 8, and a second electrode 11 is provided on the inner surface of the air nozzle plate 2 at the outer periphery near the air outlet B in the air flow path S. An electrode 12 is provided, and a negative bias voltage (DC voltage) Vb is applied to the first electrode 11 and the second electrode 12, respectively.

vb' is applied, and a positive voltage v8 is applied to the ink supply pipe 10, that is, ink, and the absolute value is lvb l>
The VC is set so that the relationship lvsl>Ivb't holds.

Next, the operation of the above embodiment will be explained (the ink ejection principle is the same as the conventional one, so the details will be omitted). In the embodiment described above, by providing the second electrode 12 as described above, the second electrode 12 draws the ink from the ink ejection lower and guides it to the ejection state, and the first electrode 11 draws out the ink from the ink ejection lower. can be discharged outward from the air discharge port 8. Therefore, the electrostatic force generated by the first electrode 11 can be more efficiently concentrated on the ink of the ink discharge lower, and ink can be discharged easily. Here, when the negative voltage becomes large, the ink ejection amount and responsiveness increase, but
A dust phenomenon occurs, resulting in poor image quality and ink accumulation on the front surface of the inkjet recording head. On the other hand, when the voltage is in the positive direction from 0, the image quality improves, but the responsiveness decreases. For these reasons, as shown in FIG. 1(b), it has been found that when the bias voltage Vb is 150V, the bias voltage V has an almost optimum value between -200V and 0V.

Further, the signal voltage v8 at this time is the second electrode 1 as described above.
2, it has become possible to eject ink with good efficiency, and it has become possible to reduce the voltage to +250 to +300 V, which is approximately half that of the conventional example. Furthermore, the amount of ink discharged could be increased by about 30% compared to the conventional example.

Note that the size and shape of the second electrode 12 are factors that affect the recording characteristics, so it is desirable that the second electrode 12 be as close to the ink discharge lower and air discharge ports 8 as possible, but if it is too close, part of the ink may There is a risk that it will adhere to the second electrode 12. Therefore, an appropriate distance is required from the ink discharge lower and the air discharge port 8. Further, the second electrode 12 can also be used as a spacer for controlling the thickness of the air flow path 5.

Effects of the Invention As described above, according to the present invention, a first air nozzle plate is provided on the surface side of the air nozzle plate having air discharge ports opposite to the ink discharge ports.
A second electrode is provided between the first electrode and the ink ejection port on the inner surface side of the air nozzle plate, and negative voltages vb, vb' are applied to the first and second electrodes, respectively. death,
A positive voltage vs is applied to the ink, and the absolute value is l
Since the setting is such that the relationship is Vb l>l Vs l>lVb'l, the second electrode draws out the ink from the ink ejection port, and the first electrode draws the ink outward from the air ejection port. The ink can be ejected, and electrostatic force can be more efficiently concentrated on the ink at the ink ejection port.

Therefore, the signal voltage applied to the ink can be lowered, the risk of discharge can be prevented, reliability can be improved, and the electric circuit can be made smaller and lower in cost. Furthermore, the amount of ink ejected can be increased and the recording density can be improved.

[Brief explanation of drawings]

FIG. 1(,) is a sectional view showing an embodiment of the inkjet recording device of the present invention, FIG. 1(b) is an explanatory diagram of driving voltage thereof, and FIG. , FIG. 3(a) is a sectional view for explaining the driving voltage, and the same figure (bl is a diagram for explaining the driving voltage. 2... Air nozzle plate, 3... Ink nozzle plate , 7... Ink discharge port, 8... River/air discharge port, 11... First electrode, 12...
-Second electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure 3 in 2 nosunshi 1 opposite mouth □θV -5θθV Cb) Base □OV θ~-200V Kudan J! 25'~''300''' θV Figure 2 Figure 3

Claims (1)

[Claims] a first electrode provided on the surface side of an air nozzle plate having an air discharge port opposite to the ink discharge port; and a first electrode provided on the inner surface side of the air nozzle plate, between the first electrode and the ink discharge port. Negative voltages Vb and Vb' are applied to the first and second electrodes, respectively, and a positive voltage Vs is applied to the ink, and the absolute value is |Vb|
An inkjet recording apparatus characterized in that the inkjet recording apparatus is set to have a relationship of >|Vs|>|Vb'|.