JP2789828B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, printers using an ink jet recording method have been actively used as terminal equipment for personal computers and CAD. In this ink jet recording method, as an ink jet recording apparatus which discharges ink from a minute opening using an air flow and an electrostatic force, for example, Japanese Patent Application Laid-Open Nos.
A configuration as described in JP-A-9-146860 is known. Hereinafter, a conventional ink jet recording apparatus will be described with reference to FIG.

FIG. 3 is a schematic sectional view of a part of an ink jet 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, and 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 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 ejection port 107
Are formed, and the ink discharge ports 10 are
7, an air discharge port 108 is formed. An electrode 109 is provided on the outer surface of the air nozzle plate 102 at the outer periphery of the air discharge port 108. In addition, the ink chamber 10
An electrode 114 is provided in the vicinity of the ink ejection port 107 in 6. The air chamber 104 is connected to an air supply source 112 by an air supply pipe 110, and the ink chamber 106 is connected to an ink supply source 113 by an ink supply pipe 111. The electrodes 109 and 114 are connected to a signal source 115.

Next, the operation of the above configuration will be described. Air is supplied from the air supply source 112 to the air chamber 114.
And flows out at a constant flow rate into the air flow path 105 as an air layer while causing a sharper bend, and this air forms a sharp bend near the air discharge port 108 and the ink discharge port 107 while the air discharge port It flows out from 108. On the other hand, ink is supplied to the ink chamber 106 from the ink supply source 113, and the ink supply source 113 and the ink chamber 106 are supplied by air pressure sent from the air supply source 112.
A constant pressure is applied to the ink inside. As a result, during non-printing of the ink jet recording apparatus, the air pressure in the vicinity of the ink ejection port 107 caused by the air flow is substantially equal to the ink pressure in the ink ejection port 107, and the meniscus of the ink generated in the ink ejection port 107 is kept stationary. Will be. When a potential difference is generated between the electrode 109 and the electrode 114, the meniscus of the ink generated in the ink ejection port 107 is stretched in the direction of the air ejection port 108 by the electrostatic force due to the potential difference. Ink ejection port 10
Since a rapid change in pressure gradient is generated in the air flow path 105 from the nozzle 7 to the air discharge port 108 due to the air flow, the ink meniscus of the ink discharge port 107 is rapidly accelerated when the ink meniscus is stretched beyond a certain length, It flies in the airflow flowing out of the air discharge port 108.

[0005]

In the ink jet recording apparatus utilizing the air flow and the electrostatic force described above,
As for recording characteristics, driving at a relatively low voltage (500 V or less) instead of using electrostatic force and good responsiveness (10
２０20 kHz) and fine dot formation (20-3
0 μmφ) is extremely excellent.

However, there are some problems other than the recording characteristics. First, an air supply system including the air supply source 112 and the air supply pipe 110 is required.
The presence of this certainly increases costs in that respect. Further, a problem of reliability of the air supply system occurs. That is, the problem of dust present in the supply air or the problem of constant air pressure corresponds to this. In order to cope with these problems, a method of using a filter or detecting air pressure and applying electrical feedback to control the apparatus has been adopted. However, the apparatus is complicated and the cost is further increased. .

Second, there is a problem with the construction method. In assembling, when the ink discharge ports 107 and the air discharge ports 108 are arranged coaxially and concentrically, it is necessary to precisely maintain a constant interval between the air flow paths 105. This interval is slightly less than 100 μm, and high-precision parallelism is required, and the variation must be kept within several μm. This is because this interval is
This is because the air pressure in the vicinity of 7 is greatly affected. That is, as the interval increases, the air pressure near the ink ejection port 107 increases, approaches the pressure in the ink chamber 106, and the ink meniscus formed in the ink ejection port 107 is not held in a shape pushed out toward the air ejection port 108 side. In addition, the ink ejection amount and the responsiveness also decrease. Conversely, when this interval becomes narrow, the ink ejection amount and the responsiveness also increase, but the ejection becomes unstable. Therefore, it is necessary to maintain an optimum air flow path interval that balances these.

As described above, in the conventional ink jet recording apparatus, there are problems such as cost due to the presence of the air supply system, and the necessity of advanced technology because high precision is required at the time of assembly. This has been a major issue.

[0009]

According to the present invention, in order to solve the above-mentioned problems, two thin plates made of a conductive material and an insulating material each having fine openings of different sizes are formed.
Each opening is superposed so that the center of each opening becomes coaxial, electrodes are arranged around a large-diameter opening formed in a thin plate made of an insulating material, and the small-diameter opening is communicated with the ink chamber, and the electrode is connected to the electrode. A thin plate made of a conductive material is connected to a signal source.

[0010]

According to the present invention, by applying a signal voltage from the signal source in the above-described configuration, the ink meniscus formed in the small-diameter opening can be stretched and fly outside through the large-diameter opening for recording. In addition, high-precision assembling is unnecessary and cost reduction is made possible.

[0011]

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

FIG. 1 is a schematic partial cross-sectional view of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of the opening in FIG. A fine first opening 204 is formed in the first thin plate 202 made of a conductive material. On the other hand, a second opening 205 having a diameter larger than that of the first opening 204 is formed in the second thin plate 203 made of an insulating material. The two openings 203 and 204 are arranged so that their centers are coaxial, and the thin plates are overlapped. An electrode 206 is arranged around the second opening 205 on the side opposite to the overlapping surface, and is connected to the signal source 211 together with the first thin plate 202. The first opening 204 is adjacent to and communicates with the ink chamber 207 formed by the body member 201. Ink chamber 2
Reference numeral 07 denotes the ink tank 2 via the ink supply pipe 208.
09. In addition, as shown in FIG.
The ink meniscus is held at the outer edge of the ink meniscus. A relatively short distance (2 m) is in front of the second thin plate 203.
m or less). First opening 20
The diameter of 4 is set to several tens of μm, and the diameter of the second opening 205 is set to about 2 to 5 times.

In the above configuration, when a signal voltage is applied between the electrode 206 and the first thin plate 202 from the signal source 211, an electric field is concentrated on the surface of the ink meniscus formed in the first opening 204, and ink is drawn out by electrostatic force. It becomes a string and flies outward on the center line of the second opening 205 and adheres to the recording paper 212. Recording paper 212 and second thin plate 20
If the distance of 3 is too large, the flying ink returns and is attracted to and adheres to the electrode 206, so that the distance must be narrowed as described above.

The factors that determine the recording characteristics are the first aperture 20
4 and the shape of the second opening 205, the relative dielectric constant of the second thin plate 203, and the physical properties of the ink. Especially the second thin plate 203
The effective range of the relative dielectric constant is about 1 to 8, and the smaller the value, the higher the response, the lower the drive voltage, and the better the recording characteristics. In the physical properties of the ink, specific resistance is important and is 10 ⁴ to 10.
^It must be set within the range of ⁸ Ωcm. Also the first opening 2
The 04 and the second opening 205 do not need to be perfect circles, but may be any shape as long as the electric field acts uniformly.

The ink-repellent substance 213 applied to the inner wall and the periphery of the second opening 205 and the outer periphery of the first opening 204 shown in FIG. It also has the effect of not staining this part with excess ink. If ink adheres to this portion and becomes dirty, the applied state of the electric field may change slightly, which may affect the recording characteristics.

The recording characteristics of the present invention are slightly inferior in both the response and the driving voltage as compared with the conventional example shown in FIG. 3, but the structure is simple and extremely advantageous in the assembling method. The shape can be simplified by stacking thin plates having different opening diameters, which is advantageous in terms of cost.

[0017]

As described above, according to the present invention, two thin plates made of a conductive material and an insulating material each having fine openings of different sizes are formed so that the centers of the openings are coaxial. An electrode is arranged around a large-diameter opening formed in a thin plate made of an insulating material that has been polymerized, and the small-diameter opening communicates with the ink chamber, and the thin plate made of the electrode and the conductive material is used as a signal source. By adopting a connected configuration, it is possible to provide a simplified electrostatic suction type inkjet recording apparatus,
It has excellent advantages in cost, assembly method and reliability, and its effect is great.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view of an ink jet recording apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of an opening in FIG. 1;

FIG. 3 is a schematic partial cross-sectional view of a conventional ink jet recording apparatus.

[Explanation of symbols]

 101 body member 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 201 Body member 202 First thin plate 203 Second thin plate 204 First opening 205 Second opening 206 Electrode 207 Ink chamber 208 Ink supply tube 209 Ink tank 210 Air vent hole 211 Signal source 212 Recording paper 213 Ink repellent material

Claims (1)

(57) [Claims] 1. A first sheet of conductive material having a first opening and a second sheet of insulating material having a second opening having a larger diameter than the first opening, wherein the first sheet and the second sheet of insulating material have a larger diameter than the first opening. The center of the opening is superposed so as to be coaxial, a signal source connected to the electrode and the first thin plate disposed around the second opening, and an ink chamber communicated with the first opening. Characteristic inkjet recording device