JPH04185351A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To ensure that a recording state can always be maintained stably by providing an ink chamber formed on a recording head with the lower volume being reduced compared to the upper volume and also an ink discharge orifice which is opened in said ink chamber in such a manner that the orifice is opposed to an air discharge orifice through an air passage. CONSTITUTION:If an ink amount filled in an ink chamber 106' reaches a constantly fixed level at the early stage of ink jet recording process, an ink liquid surface IL when filled rises so that the surface IL during the early stage is set high as a lower chamber (b) is so shaped as to retain a small volume. On the other hand, if air is introduced into the ink chamber 106' from an ink discharge orifice 107 by impact of a recording head 100, the ink liquid surface IL drops accordingly. In this case, if the air A of the ink chamber 106' increases by a specified amount, the ink liquid surface IL is elevated as the early stage ink liquid surface IL is high. Thus the surface can be maintained at the top of an ink supply pipe 111. Subsequently, the ink supply pipe 111 is submerged in ink I of the ink chamber 106', so that the air is no longer allowed to come into the ink chamber 106', and a normal ink supply state is ensured.

Description

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

Conventional technology Conventionally, inkjet recording devices that use airflow and electrostatic force to eject ink from minute apertures have been used.
For example, JP-A-57-120452, JP-A-59-1
A configuration described in the publication No. 46860 is known.

That is, FIG. 3 is a cross-sectional view of a conventional ink side recording head, in which the body member 10 of the recording head 100 is
An insulating air nozzle plate 102 is attached to the tip of the outer wall 1, and an insulating ink nozzle plate 103 is attached to the tip of the inner wall. Further, an air chamber 104 is formed between the outer wall and the inner wall of the body member 101, and an air passage 105 communicating with the air chamber 104 is formed between the air nozzle plate 102 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 around the air outlet 108 on the outer surface of the air nozzle plate 102 .

Furthermore, an electrode 4 is also provided around the ink discharge port 107 in the ink chamber 106 . Air chamber 104 is air supply pipe 1
10 communicates with an air supply source 112, and the ink chamber 10
6 is connected to an ink supply source 113 through an ink supply pipe 111. Electrodes 109 and 114 are then configured to be connected to a signal source 115.

With the configuration of the prior art example described above, when air is sent to the air chamber 104 from the air supply source 112, this air flows through the air flow path 1.
05 as an air layer at a constant flow rate, and the air discharge port 1
08 and near the ink ejection port 107, the air flows out from the air ejection port 108 while making a sharp bend. On the other hand, the ink chamber 1.06 is supplied with ink from the ink supply source 113, and a constant pressure is applied to the ink in the ink supply source 113 and the ink chamber 106 due to the pressure of the air sent from the air supply source 112. ing.

As a result, when the inkjet is not recording, the air pressure near the ink ejection port 107 caused by the air flow and the ink ejection port 1
The ink pressure inside the ejection port 107 becomes approximately equal, and the meniscus of ink generated at the E/R ejection port 107 is kept stationary. Then, a signal voltage is applied by the signal source 115,
When a potential difference is generated between the electrodes 109 and 114, the meniscus of ink in the ink discharge port 107 is stretched in the direction of the air discharge port 108 due to static electricity caused by this potential difference. Here, in the air flow path 105 from the ink discharge port 107 to the air discharge port 108, a sudden change in pressure gradient occurs due to the air flow, so that the ink meniscus of the ink discharge port 107 is pulled for a certain length or more. When stretched 1. @It is rapidly accelerated. Then, the meniscus of this ink is ejected from the air ejection port 108 and recorded on the recording paper.

Problems to be Solved by the Invention However, in the conventional inkjet recording apparatus described above, in the actual operation of initially supplying ink to the ink chamber 106, it is difficult to completely fill the ink chamber 106 with ink. In reality, some air remains in the upper part of the ink chamber 106. This ink chamber 10
In other types of inkjet recording devices that use piezo elements, the air inside the ink jet recording device causes a big problem as the pressure waves generated by the piezo elements are absorbed by the air, leading to the inability to eject. In the inkjet recording apparatus shown in FIG. 3 that uses air flow and static electricity, recording is performed by sucking and ejecting ink, so the air in the ink chamber 106 described above hardly poses a problem. On the contrary, this air absorbs pressure fluctuations propagated through the ink supply pipe 111, so that instability in the ejection state can be alleviated.

However, in this inkjet recording apparatus, when the inkjet recording apparatus is not used for a long time, air may gradually enter the inside from the connection part of the ink supply pipe 111. 1. If the air dissolved in the ink comes out, or if an impact is applied to the recording head 100 and the ink meniscus formed at the ink ejection port 107 is torn, more water will be added to the ink chamber 106. Air may accumulate. This increase in air in the ink chamber 106 is relatively easy to accomplish.

Here, in the ink chamber 106, the ink supply pipe 111 is connected to the middle of the ink discharge port 107 at approximately the same level, so when the amount of ink decreases, a large amount is accumulated in the ink chamber 106 as described above. Air easily enters the ink supply pipe 111 and enters the ink chamber 10 into the ink supply pipe 111.
6 air pressure comes into play. On the other hand, an ink meniscus is formed in the ink discharge port 107, and the ink chamber 1
The pressure balance within the 06 and the air chamber is approximately maintained. Therefore, when the ink supply source is pressurized by the air supply source to supply ink, the air pressure in the ink chamber 106 acts against the air pressure of the air supply source at the outlet of the ink supply pipe 111. Therefore, due to the pressure relationship between the two, the supply of ink by the ink supply pipe 111 becomes extremely poor, and a situation occurs in which ink is not sufficiently supplied to the ink chamber 106 as shown in FIG. 4.

There is a problem in that this ink supply failure causes recording failures such as blurring or interruption of recording midway through.

In view of such conventional problems, an object of the present invention is to supply ink smoothly even when the amount of air in the ink chamber increases.
To obtain an inkjet recording device that can always ensure a stable recording state.

Means for Solving the Problems In order to achieve this object, the present invention provides an ink chamber formed by reducing the volume of the lower part than the upper part of the recording head, and an air discharge port that faces the same through an air flow path. An inkjet recording device is proposed that includes an ink discharge port opened in an ink chamber, an ink supply source that communicates with an air supply source and is pressurized, and an ink supply pipe that communicates the ink supply source with the ink chamber. It is something.

According to the configuration of the present invention described above, the ink chamber is filled with ink by raising the liquid level during initial ink filling due to the shape of the ink chamber having a changed volume. Therefore, even if the air in the ink chamber increases by a certain amount, the ink liquid level is still maintained above the ink supply pipe, preventing air from entering the ink supply pipe. It becomes possible to smoothly supply ink from the ink chamber to the ink chamber.

EXAMPLE Hereinafter, an example of the present invention will be described in detail using FIGS. 1 and 2.

FIG. 1 is a cross-sectional view of an inkjet recording apparatus according to the present invention, in which a recording head 100 is provided with an air nozzle plate 10 having an air discharge 0108 on a body member 101 as in FIG.
2, and an ink nozzle plate 10 having an ink discharge port 107.
3 is installed. An air chamber 104 is provided inside the air nozzle plate 102 via an air passage 105, and an air chamber 104 is provided inside the ink nozzle plate 1
Ink chambers 106' are formed inside each of the ink chambers 03. Then, the air discharge port 108 and the ink discharge port 107
Electrodes 109 and 114 are respectively installed in the parts, and these electrodes 109 and 114 are connected to a signal source 115,
The ink meniscus is sucked and ejected.

Further, an air supply pipe 110 from an air supply source 112 is communicated with the air chamber 104 and an ink supply source 1.13, and the ink supply source 11.3 is communicated with the ink chamber 106' via an ink supply pipe 111. There is.

On the other hand, the ink chamber 106' is a chamber a whose upper and lower volumes differ.
, b. That is, the upper chamber a has a cylindrical shape with a large volume, but the lower chamber a has a cylindrical shape with a large volume.
The chamber is formed into a substantially trapezoidal shape by providing an inclined surface C so as to sequentially cover the cross-sectional area from the tip to the bottom surface d, and the volume is smaller than the upper chamber a.

Since the inkjet recording apparatus according to the illustrated embodiment has the above-described structure, the recording head 100
The air pressure near the ink ejection port 107 and the ink pressure are approximately equal, and the meniscus 0 of the ink generated at the ink ejection port 107 is held stationary.

Then, during recording, the electrodes 109.11 are
When a signal voltage is applied to 4, the meniscus IO is attracted from the ink ejection port 107 by the electrostatic force based on the potential difference between the signal voltages, and is ejected flying through the air flow flowing out from the air ejection port 108, thereby hitting the recorded object in front. Recording is carried out by attaching it to the

On the other hand, during such inkjet recording,
At the time of initial ink filling, the amount of ink is supplied to the ink chamber 106' to the extent that the ink chamber 106' is assembled.
1. Ink (■) is automatically supplied on 06/. Therefore,
Assuming that the amount of ink filled into the ink 106/ is constant at this initial stage, since the volume of the lower chamber is small, the ink liquid level IL at the time of filling will rise compared to the conventional example shown in FIG. As a result, the initial ink liquid level IL is set high.

On the other hand, due to the impact of the recording head 100, the ink ejection ports 10
7 or from the connection part of the ink supply pipe 111 into the ink chamber 106', the ink chamber 106'
'The air A inside increases, and the ink liquid level IL increases accordingly.
decreases. At this time, if the same fixed amount of air A as in the conventional example increases in the ink chamber 106', since the initial ink liquid level IL is high, the ink liquid level Ir in this case,
is also higher than that of the conventional example, making it possible to maintain it above the ink supply pipe 111 as shown in FIG. Therefore, the ink supply pipe 111 is always buried in the amount of ink in the ink chamber 106', preventing air from entering the ink chamber 106'.

In this way, air A is prevented from entering the ink supply pipe 111, so that the ink supply pipe 111 is maintained in a normal ink supply state. Therefore, all the air pressure of the ink supply source 113 acts on the ejection of the ink (2), and even if the ink level IL decreases as the air in the ink chamber 106' increases, the ink (2) will be smoothly ejected one by one as the ink (2) is consumed. is supplied. By supplying this ink (2), a stable recording state is maintained continuously.

On the other hand, the air A in the ink chamber 106' may increase further than in the above case, and the ink liquid level IL may drop below the ink supply pipe 111. In this case, the ink chamber 106'
At 6', a large amount of ink I adheres to the inclined surface C due to its viscosity and wettability, and the ink contact angle becomes larger than that of the inclined surface C, as shown by the dashed line in FIG. The ink on the inclined surface C is also adhered to and held at the opening of the ink supply pipe 111, and air A can be prevented from entering the ink supply pipe 111 in the same manner as described above.

It should be noted that the present invention is not limited to the embodiments described above.

Effects of the Invention As explained above, the inkjet recording apparatus according to the present invention can smoothly supply ink even when the air in the ink chamber 106' of the recording head increases, so that stable recording characteristics can be achieved. It can be obtained for a long time and its effects are great. Since the configuration is such that the shape and volume of the ink chamber are changed, the structure is simple. Since the ink chamber is configured to reduce the volume by providing an inclined surface directly below the ink supply pipe, this is effective even when the ink liquid level is further lowered by this inclined surface. Since there is no need to strictly control the air in the ink chamber, assembly work efficiency is improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an inkjet recording apparatus according to the present invention, FIG. 2 is a sectional view of the inkjet recording apparatus showing the state of air increase in the ink chamber, FIG. 3 is a sectional view of a conventional inkjet recording apparatus, and FIG. 4 is a sectional view of the inkjet recording apparatus according to the present invention. FIG. 2 is a cross-sectional view of the same inkjet recording apparatus showing a state in which air is increased in the ink chamber. 100... Recording head, 105 Air flow path, 106
'... Ink chamber, 107 - Ink discharge port, 108 - Air discharge port, 11.1 - Ink supply pipe, 112 - Air supply source, ] 13 - Ink supply source. Name of agent: Patent attorney Akira Okaji and 2 others'1j
J1 Figure 112 Air supply source Figure 2 112 Air supply source Figure 3 Anus 101 1゛12

Claims (1)

[Claims] An ink chamber formed by reducing the volume of the lower part than the upper part of the recording head, an ink discharge port that faces the air discharge port via an air flow path and is opened in the same ink chamber, and communicates with an air supply source. An inkjet recording apparatus comprising: an ink supply source that is pressurized; and an ink supply pipe that communicates the ink supply source with an ink chamber.