JPH05116321A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To obtain an electrostatic attraction type recording apparatus being simplified and excellent in cost, assembly technique and reliability by connecting a signal wire between first and second electrodes respectively provided around an external tapered recess and around an internal ink discharge port. CONSTITUTION:When signal voltage is applied from a signal wire 211 to first and second electrodes 206, 207, an electrostatic force acts on the ink meniscus of an ink discharge port 204, and because the discharge port 204 and tapered recess 203 are shaped symmetrically with respect to the central axis, ink is extracted on the central axis of the discharge port 204 in the direction of the electrode 206 and jumps from the discharge port 204 without hitting against the inner peripheral wall of the recess 203 to adhere to a recording paper 212 so that recording is conducted. Thus, a thin plate 202 is equipped with the recess 203 coaxially continuing to the discharge port 204 so that ink discharged from the discharge port 204 does not hit against the inner peripheral wall of the recess 203 and therefore it is possible to contrive to improve a discharge stability. Further, the recess 203 is easy to manufacture because the accuracy of the recess is not required much, and adhering ink, dust, etc., are also easy to remove.

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 and the like on a recording medium by ejecting ink from minute openings.

[0002]

2. Description of the Related Art Conventionally, as an ink jet recording apparatus for ejecting ink from a minute opening by utilizing an air flow and an electrostatic force, for example, JP-A-57-120452 and JP-A-59-146860 are known. A configuration as described in the publication is known.

A conventional ink jet recording apparatus will be described below with reference to FIG. Body member 101
An air nozzle plate 102 made of an insulating material is attached to the front end surface of the outer peripheral wall of the above, and an ink nozzle plate 103 made of an insulating material is attached to the front end surface of the inner peripheral wall. Body member 101
An air chamber 104 is formed between the outer peripheral wall and the inner peripheral wall of the
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 between the ink nozzle plate 103 and the body member 101. An ink ejection port 107 is formed in the center of the ink nozzle plate 103, and an air ejection port 108 is formed in the center of the air nozzle plate 102 so as to face the ink ejection port 107.
An electrode 109 is provided on the outer surface of the air nozzle plate 102 around the air ejection port 108, and the electrode 1 is provided around the ink ejection port 107 on the ink chamber 106 side of the ink nozzle plate 103.
14 are provided. The air chamber 104 has an air supply pipe 11
0 communicates with the air supply source 112, 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 the signal source 11
Connected to 5.

Next, the operation of the above conventional example will be described. When the air is sent from the air supply source 112 into the air chamber 104, the air is sharply bent and the air passage 10
5 as an air layer at a constant flow rate, and further flows out from the air ejection port 108 while making a sharp bend near the air ejection port 108 and the ink ejection port 107. On the other hand, ink is supplied from the ink supply source 113 into the ink chamber 106, and a constant pressure is applied to the ink inside the ink supply source 113 and the ink chamber 106 by the air pressure sent from the air supply source 112. Has been. This allows
At the time of non-recording of the ink jet recording apparatus, the air pressure in the vicinity of the ink ejection port 107 generated by the air flow and the ink pressure in the ink ejection port 107 are almost equal, and the ink ejection port 10
The meniscus of the ink generated in 7 is kept stationary. Then, 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 due to the electrostatic force due to this potential difference causes the air ejection port 1 to move.
It is stretched in the direction of 08. Since an abrupt change in pressure gradient is caused by the air flow in the air flow path 105 from the ink ejection port 107 to the air ejection port 108, when the ink meniscus of the ink ejection port 107 is stretched for a certain length or more, it is rapidly accelerated. The air is discharged from the air discharge port 108.

[0005]

By the way, an ink jet recording apparatus utilizing such air flow and electrostatic force is
In terms of recording characteristics, it has extremely excellent performance such as being driven at a relatively low voltage (500 V or less), having good responsiveness (10 to 20 kHz), and being capable of forming fine dots (20 to 30 μm φ). Have However, there are some problems other than the recording characteristics. That is, first of all, first, the air supply source 112 and the air supply pipe 110
This is a point that requires an air supply system such as. The existence of this will definitely raise the cost. Furthermore, the reliability problem of the air supply system arises. That is, the problem of dust existing in the supply air, the problem of constant air pressure, and the like correspond to this. To deal with these problems, a filter is used or a method of detecting air pressure and controlling by applying electric feedback is taken, but the device becomes more complicated and the cost is further reduced. The result will be to raise.

Secondly, there is a problem in the construction method that the distance between the air flow paths 105 must be kept constant. In particular, in the case of a multi-nozzle, this interval is a little less than 100 μm and the parallelism is good, and the variation between nozzles must be within several μm. This interval has a subtle effect on the air pressure in the vicinity of the ink ejection port 107. That is, as the distance increases, the air pressure near the ink ejection port 107 rises and approaches the pressure inside the ink chamber 106, and the ink meniscus formed in the ink ejection port 107 is held in a shape pushed out toward the air ejection port 108 side. The amount of discharged ink and the responsiveness are reduced. On the contrary, when the distance is narrowed, both the ink ejection amount and the responsiveness increase, but the ejection becomes unstable.
Therefore, it is necessary to maintain an optimum air flow path interval that can balance these.

As described above, in the above-mentioned conventional ink jet recording apparatus, there are problems in terms of cost due to the existence of the air supply system, and construction method problems such as the necessity of highly accurate assembly near the air discharge port and the ink discharge port. It was a major issue.

[0008]

In order to solve the above-mentioned problems, the present invention eliminates the air supply system and forms an ink ejection port having a tapered concave portion whose diameter is expanded outward on a thin plate, The first electrode is provided around the tapered recessed portion and the second electrode is provided around the inner ink ejection port to connect the signal source between both electrodes, and the ink ejection port is connected to the ink chamber and the ink supply port. The ink tank is connected to the ink tank via a tube.

[0009]

According to the present invention, with the above structure, a signal voltage is applied between the first and second electrodes provided around the tapered recess on the outer surface of the thin plate and around the ink discharge port on the inner surface. It is possible to extend the ink from the ink ejection port and to eject the ink to the outside through the tapered recess formed in the thin plate, and at the same time, to realize a low-cost inkjet recording device that does not require high-precision assembly. You can

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic partial cross-sectional view of an inkjet recording apparatus according to an embodiment of the present invention. Figure 1
In the figure, 201 is a box-shaped body member, and 202 is a thin plate fixed to the open end surface of the body member 201.
The thin plate 202 is made of an insulating material, and a tapered concave portion 203 whose diameter is expanded outward is formed in a central portion of the thin plate 202, and an ink discharge port 204 coaxially continuous with the tapered concave portion 203 is formed inside thereof. ing. A first electrode 206 is formed around the tapered recess 203 on the outer surface of the thin plate 202, and a second electrode 207 is formed around the ink ejection port 204 on the inner surface of the thin plate 202. It is connected to the. The second electrode 207 may be provided continuously around the ink ejection port 204 or may be provided separately. Ink ejection port 2
Reference numeral 04 is connected to an ink chamber 205 formed by a body member 201 and a thin plate 202, and is connected to an ink tank 209 via an ink supply pipe 208. Ink supply means is constituted by these. An air vent hole 210 is provided above the ink tank 209.
The diameter of the ink ejection port 204 is several tens of μm, and the tapered recess 20
The outer opening diameter of 3 is appropriately determined in relation to the thickness of the thin plate 202. Specifically, it is desirable to set the illustrated taper angle θ to 8 ° or more. Further, a recording paper 212 is arranged at a relatively close position on the front surface of the thin plate 202.

Next, the operation of the above embodiment will be described. From the signal source 211 to the first and second electrodes 206, 2
When a signal voltage is applied to 07, an electrostatic force acts on the ink meniscus formed in the ink ejection port 204, and the ink ejection port 204 and the tapered concave portion 203 are symmetrical about the central axis. On axis first
The ink is discharged toward the electrode 206 and the ink discharge port 2
From 04, it flies without hitting the inner peripheral wall of the tapered concave portion 303 and adheres to the recording paper 212 for recording. When the recording paper 212 is too far away from the thin plate 202, the ink that has flown is attracted to the first electrode 206 and returns to the thin plate 2.
02 and the first electrode 206, the recording paper 21
It is necessary to make the distance between the second electrode 206 and the second electrode 206 narrow so that the ink does not return.

The factors that influence the recording characteristics include the shape of the ink ejection port 204, the hole diameter, the shape of the tapered recess 203, the hole diameter, the depth, the inclination angle, the dielectric constant of the thin plate 202, and the physical properties of the ink. .. These conditions are optimized according to the purpose of use of the device.

Thus, according to the above embodiment, the thin plate 2
No. 02 is provided with a tapered recess 203 coaxially continuous with the ink discharge port 204, the ink discharged from the ink discharge port 204 does not collide with the inner peripheral wall of the tapered recess 203, so that the discharge stability is improved. Can be improved. Further, since the precision of the tapered recess 203 is not required so much, it is easy to manufacture, and it is easy to remove the adhesion of ink, dust and the like.

If excess ink adheres to the inner peripheral wall of the tapered concave portion 203 and the first electrode 206, the electric field distribution changes and the flying state of the ink becomes unstable. Therefore, as shown in FIG. Tapered recess 203 and first
The outer surface of the thin plate 202 including the electrodes 206 may be coated with an ink repellent material 213 that repels ink. However, when the material of the thin plate 202 already has ink repellency such as Teflon, the tapered concave portion 203
No coating on the inner wall is required.

FIG. 3 shows an example in which the linear portion of the ink ejection port 204 has a distance of zero and the tapered concave portion 203 reaches the inner surface of the thin plate 202. With such a configuration, the ink ejection port 204 and the tapered recess 2
There is an advantage that the 03 holes can be made easier.

The recording characteristics in each of the above-mentioned embodiments are slightly disadvantageous in terms of responsiveness and driving voltage as compared with the conventional example shown in FIG. 4, but due to the simplification of the structure, in terms of cost and assembly method. Is extremely advantageous.

[0017]

As described above, according to the present invention, the ink discharge port having the tapered concave portion whose diameter is expanded outward is formed in the thin plate, and the first electrode is provided around the outer tapered concave portion. By providing the second electrode around the inner ink ejection port and connecting the signal source between both electrodes,
It is possible to realize an electrostatic suction type ink jet recording apparatus which is simplified and excellent in terms of cost, assembling method and reliability, and its effect is extremely great.

[Brief description of drawings]

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

FIG. 2 is an enlarged sectional view of an ink ejection port portion according to another embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of an ink ejection port portion according to still another embodiment of the present invention.

FIG. 4 is a schematic partial cross-sectional view of a conventional inkjet recording device.

[Explanation of symbols]

 201 body member 202 thin plate 203 tapered recess 204 ink discharge port 205 ink chamber 206 first electrode 207 second electrode 208 ink supply pipe 209 ink tank 210 air vent hole 211 signal source 212 recording paper 213 ink repellent substance

Continued Front Page (72) Inventor and Shuko Matsu Matsushita Giken Co., Ltd. 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Prefecture

Claims (3)

[Claims] 1. A thin plate made of an insulating material having an ink ejection port on the inner side thereof and having a tapered concave portion which is coaxially continuous with the ink ejection port and has a diameter expanded outward, and an outer surface of the thin plate. A first electrode formed around the tapered recess, a second electrode formed around the ink ejection port on the inner surface of the thin plate, and connected between the first and second electrodes. An ink jet recording apparatus comprising: a signal source, an ink chamber communicating with the ink ejection port, and an ink tank connected to the ink chamber via an ink supply pipe. 2. The ink jet recording apparatus according to claim 1, wherein the tapered recess reaches the inner surface of the thin plate. 3. The ink jet device according to claim 1, wherein the outer surface of the thin plate including the tapered concave portion and the first electrode is coated with an ink repellent substance.