JPH04276455A - 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:An air pressure regulating mechanism 116 is connected to an air supply source 112, air is supplied to an ink supply source 113 and an air chamber 104 in a head, and air pressure is raised by the air pressure regulating mechanism 116. As a result, pressure difference in an air passage 105 adjacent to an ink chamber 106 and an ink discharge opening 107 is increased, ink being separated in the ink discharge opening 107 is pushed out, and increased air in the ink chamber 106 is discharged by an appropriate quantity from the ink discharge opening 107, 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. Furthermore, air pressure is applied to the ink supply source 113 from the air supply source 112 . Electrode 109 and electrode 114 are connected to signal source 115.

[0004] The operation of the above configuration will now be described. 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]

SUMMARY OF THE INVENTION According to the present invention, an air pressure adjustment mechanism is connected to an air supply source of an inkjet recording apparatus that utilizes air flow and electrostatic force.

[0009]

[Operation] With the above configuration, the present invention operates the air pressure adjustment mechanism in the non-recording area to increase the air pressure, thereby increasing the differential pressure between the ink chamber and the air flow path near the ink discharge port, thereby increasing the air pressure inside the ink chamber. Due to the effect of this, the ink that is separated and present at the ink ejection port can be discharged to the outside, and stable recording can then be performed.

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. 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.

The air supply source 112 includes an air pressure adjustment mechanism 11.
6 are connected to each other, and air is supplied to an air chamber 104 in the head and an ink supply source 113 through an air supply pipe 110.

The operation of the configuration shown in FIG. 1 as described above will be explained below. Now, as shown in Figure 4,
Air in the ink chamber 106 increases and the ink discharge port 10
Let us consider a case where ink exists separately only in 7 and printing becomes unstable. At this time, the head is moved to a non-recording area away from the recording paper, and the air pressure supplied to the ink supply source 113 and the air chamber 104 is increased by the air pressure adjustment mechanism 116. The pressure Pa in the ink chamber 106 has a value greater than the pressure Pn in the air flow path 105 near the ink discharge port 107. This is because a considerable flow velocity is maintained in the air flow path 105, and this differential pressure Pa-Pn increases as the air pressure increases. This situation is shown in FIG. Pa on the horizontal axis has a value approximately equal to the air pressure after passing through the air pressure adjustment mechanism 116.

[0014] As a result, the differential pressure Pa-Pn is
The ink meniscus formed in 7 is transferred to the ink chamber 10.
It acts as a force that pushes the air from the 6 side to the air discharge port 108 side. As this value increases, as shown in FIG.
The ink that is separated within the ink chamber 106 can be pushed out, and the increased air in the ink chamber 106 can be discharged to the outside. As a result, stable ink supply can be achieved, and blurring and inability to record can be eliminated.

According to this embodiment, the air supply source 112
An air pressure adjustment mechanism 116 is provided in the ink chamber 106, and by operating the air pressure adjustment mechanism 116 in the non-printing area to increase the air pressure, the differential pressure between the ink chamber 106 and the air flow path 105 near the ink ejection port 107 is increased. The ink chamber 106 is discharged to the outside by discharging the ink that is separated and existing in the ink ejection port 107 due to the influence of the increased air.
The increased air inside can be removed and stable recording characteristics can be obtained.

Note that the air pressure adjustment mechanism 116 is connected to the air supply source 1.
It goes without saying that even if the air supply source 112 is not connected to the air supply source 12, the same effect can be obtained if there is a device inside the air supply source 112 that has this function.

[0017]

As described above, according to the present invention, by increasing the air pressure by providing an air pressure adjustment mechanism, the pressure difference between the ink chamber and the air flow path is increased, and an appropriate amount of air in the ink chamber is removed. It is possible to obtain stable recording characteristics that do not cause failure or inability to eject, 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] Graph showing the relationship between Pa and Pa-Pn

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

[Figure 4] Enlarged view of Figure 3 ink discharge port section

[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 Air pressure adjustment mechanism

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 communicating with the air discharge port via an air flow path; an air pressure adjustment mechanism included in or connected to the air supply source; the ink supply source and the air chamber; an air supply pipe connecting the air pressure adjustment mechanism; a first electrode disposed near the ink discharge port; a second electrode disposed near the air discharge port; and first and second electrodes. 1. An inkjet recording apparatus comprising: a signal source connected to an inkjet recording apparatus, the air pressure being increased in a non-printing area by the action of the air pressure adjustment mechanism.