JPH04276454A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To remove air in an ink chamber of an ink jet head which uses air flow and electrostatic force. CONSTITUTION:A small opening 116, whose peripheral surface is covered with an ink-repellent material 117, for communicating an ink chamber 106 with an air passage 105 is provided at upper part of an ink discharge opening 107 facing an air discharge opening 108. As a result, even when air in the ink chamber 106 increases, ink does not remain in the small opening 116, but it discharges by an appropriate quantity automatically so as to restore former state, so that stable recording property without blurring and discharge failure can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus for recording characters, figures, etc. on a recording material by ejecting ink from a minute opening.

0002

2. Description of the Related Art Recently, printers using an inkjet recording method have been widely used as terminal equipment for personal computers and CAD. Among these inkjet recording methods, there are examples of inkjet recording apparatuses that eject ink from minute openings using air flow and electrostatic force, such as those disclosed in Japanese Patent Laid-Open No. 57-120452 and Japanese Patent Laid-Open No. 59-1999.
A configuration as described in Japanese Patent No.-146860 is known. A conventional inkjet recording apparatus will be described below with reference to FIG.

FIG. 3 is a schematic partial cross-sectional view of an inkjet recording apparatus. 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 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 between the air nozzle plate 102 and the ink nozzle plate 103, and an ink chamber 106 is formed inside the ink nozzle plate 103. The ink nozzle plate 103 has an ink discharge port 107.
is formed, and the air nozzle plate 102 has ink ejection ports 10.
An air discharge port 108 is formed opposite to the air outlet 7 . An electrode 109 is provided on the outer surface of the air nozzle plate 102 at the outer periphery of the air outlet 108 . In addition, the ink chamber 10
An electrode 114 is provided around the ink discharge port 107 in the ink discharge port 6 . The air chamber 104 is communicated with an air supply source 112 through an air supply pipe 110, and the ink chamber 106 is communicated with an ink supply source 113 through an ink supply pipe 111. Electrode 109 and electrode 114 are connected to signal source 115.

[0004] The operation of the above configuration will now be explained. Air is supplied from the air supply source 112 to the air chamber 114
The air flows out at a constant flow rate into the air flow path 105 as an air layer while making a sharp bend, and this air makes a sharp bend near the air outlet 108 and the ink outlet 107 while passing through the air outlet. It is leaking from 108. On the other hand, the ink chamber 106 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 air pressure sent from the air supply source 112. 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 ejection port 1
The ink meniscus generated at 07 will remain stationary. When a potential difference is generated between the electrode 109 and the electrode 114, 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 causes a sudden change in pressure gradient in the air flow path 105 from the air flow path 105 to the air discharge port 108, when the ink meniscus of the ink discharge port 107 is stretched beyond a certain length, it is rapidly accelerated and the air It flies in the airflow flowing out from the discharge port 108.

[0005]

[Problems to be Solved by the Invention] In the operation of this ink jet recording apparatus, when first supplying ink to the ink chamber 106, it is difficult to completely fill the chamber with ink, and the ink escapes to the upper part of the ink chamber 106. The reality is that there is residual air. In other types of inkjet using piezo elements, the air inside this ink chamber 106 is
The pressure waves generated by the piezo element are absorbed by the air, which causes a situation where ink cannot be ejected, resulting in a serious problem. On the other hand, Figure 3
In the inkjet recording method that uses airflow and electrostatic force as shown in , this air hardly poses a problem because recording is performed by the action of drawing out ink. Conversely, since the pressure fluctuations propagated through the ink supply pipe 111 are absorbed by this air, there is an effect of alleviating ejection instability.

However, when the inkjet recording apparatus is not used for a long time, air may gradually enter the inside from the joint of the ink supply tube 111. In addition, air dissolved in the ink is generated outside, or the ink meniscus formed at the ink ejection port 107 is torn due to impact applied to the head, so that more air accumulates in the ink chamber 106. There are cases. Ink chamber 1
The increasing air in 06 is relatively easy to reach up to a certain amount. If a situation occurs in which the air in the ink chamber 106 increases and ink exists only in the ink ejection port 107 and not around it, as shown in FIG. 4 (enlarged view of the ejection port), this occurs. Since the ink in the ink ejection port 107 is cut off from the electrode 114, no electrostatic force is applied to it;
Since air is also present in the surrounding area, it becomes impossible to supply ink, and the recording becomes blurred or stagnant.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides an inkjet recording apparatus that can perform stable recording even when the amount of air in the ink chamber increases.

[0008]

[Means for Solving the Problems] In a head structure of an inkjet recording device using air flow and electrostatic force, the present invention provides at least a peripheral surface above an ink discharge port that communicates an ink chamber with an air flow path. It is characterized by a structure in which minute openings are made of an ink-repellent material.

[0009]

[Operation] According to the above structure of the present invention, even if air increases in the ink chamber, the minute opening is made of an ink-repellent material, so the ink is separated at that part and does not form an ink meniscus. Therefore, the increased air in the ink chamber can be automatically removed through the minute opening, and stable recording can be performed by always maintaining a constant amount of air in the ink chamber.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to the drawings.

FIG. 1 is a partially sectional schematic diagram of an inkjet recording apparatus according to an embodiment of the present invention. Further, FIG. 2 is an enlarged view of the ink ejection orifice portion of FIG. 1. Since most of the configuration is the same as that of the inkjet recording apparatus shown in FIG. 3 described above, the explanation will be omitted, and only the different parts will be explained.

A minute opening 116 is formed in the ink nozzle plate 103 above the ink discharge port 107, and the ink chamber 10
6 and the air flow path 105 are communicated with each other. Also, the minute aperture 11
The periphery of 6 is coated with a fluorine-based ink repellent material 117.

The operation of the configuration shown in FIGS. 1 and 2 as described above will be explained below. FIG. 2 shows a state in which ink is normally filled and stable recording is possible. Since the periphery of the minute opening 116 is coated with a fluorine-based ink-repellent material 117, the ink is repelled around the minute opening 116. Since air is flowing at high speed in the narrow air channel 105, the pressure on the ink chamber 106 side is slightly higher than that on the air channel 105 side. Air flow path 1
There is no leakage to the 05 side.

Now, let us consider a case where air increases in the ink chamber 106 for some reason. At this time, since the minute aperture 116 is located above the ink ejection port 107, no ink is present around the minute aperture 116. Fluorine-based ink-repellent material 117 is also applied inside the micro opening 116.
Since the ink is coated, the ink does not exist separately within the minute openings 116. After all, even if air increases in the ink chamber 106, the pressure on the ink chamber 106 side is slightly higher than that on the air flow path 105 side, so the increased amount of air in the ink chamber 106 automatically flows through the micro opening 116. The air then escapes to the air flow path 105 side, returning to the normal state shown in FIG.

[0015] Through this series of operations, the increased air in the ink chamber 106 can be discharged to the outside from the minute opening 116, and as a result, stable ink supply can be performed, and blurring and inability to record can be eliminated.

As described above, according to this embodiment, the ink discharge port 10
By providing a minute opening 116 coated with an ink-repellent material 117 on the upper part of the ink chamber 10,
6 can be automatically removed, and stable recording characteristics can be obtained.

[0017] In the embodiment, an example was shown in which the minute opening 116 was coated with an ink-repellent material 117.
It goes without saying that the same effect can be obtained when the small portion constituting the minute opening 116 is made of an ink-repellent material.

[0018]

As described above, according to the present invention, by providing a minute opening in the upper part of the ink discharge port that communicates the ink chamber with the air flow path and having at least the peripheral surface made of an ink-repellent material, The increased air in the ink chamber is automatically removed by an appropriate amount from that part, and stable recording characteristics without blurring or inability to eject can be obtained, which is highly effective.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional schematic diagram of an inkjet recording apparatus in an embodiment of the present invention.

[Figure 2] Enlarged view of the ink discharge port in Figure 1

[Fig. 3] Partial cross-sectional schematic diagram of a conventional inkjet recording device

[Figure 4] Enlarged view of the ink discharge port in Figure 3

[Explanation of symbols]

101 Body parts 102 Air nozzle plate 103 Ink nozzle plate 104 Air chamber 105 Air flow path 106 Ink chamber 107 Ink discharge port 108 Air discharge port 109 Electrode 110 Air supply pipe 111 Ink supply pipe 112 Air supply source 113 Ink supply source 114 Electrode 115 Signal source 116 Micro aperture 117 Ink-repellent material

Claims (1)

[Claims] 1. An ink discharge port, an air discharge port disposed opposite to the ink discharge port, an ink chamber communicating with the ink discharge port, and an ink chamber for supplying ink to the ink chamber via an ink supply path. an ink supply source, an air chamber communicated with the air discharge port via an air flow path made of a thin layer, an air supply source for supplying air to the air chamber via an air supply path, and the ink. a minute opening located above the discharge port and communicating between the ink chamber and the air flow path and having at least a peripheral surface made of an ink-repellent material; a first electrode disposed near the surface of the air discharge port; and a second electrode disposed in the ink chamber near the ink discharge port, and a potential difference is provided between the first and second electrodes to draw ink from the ink discharge port and from the air discharge port. An inkjet recording device that performs recording by flying an inkjet in an outflowing air stream.