JP2775544B2 - 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 and figures 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. In FIG. 3, an air nozzle plate 102 made of an insulating material is attached to a tip surface of an outer wall of a body member 101, and an ink nozzle plate 103 made of an insulating material is attached to a tip surface of an inner wall. An air chamber 104 is formed between the outer wall and the inner wall of the body member 101, and an air chamber 10 is provided between the air nozzle plate 102 and the ink nozzle plate 103.
4 is formed. Also,
An ink chamber 106 is formed inside the ink nozzle plate 103. An ink outlet 107 is formed in the center of the ink nozzle plate 103, and an air outlet 108 is formed in the air nozzle plate 102 so as to face the ink outlet 107. On the surface of the air nozzle plate 102, a first electrode 109 is formed around the air discharge port 108, and on the back surface of the ink nozzle plate 103, a second electrode 114 is formed around the ink discharge port 107. I have. Air chamber 10
4 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 first electrode 109 and the second electrode 114 are connected to a signal source 115.

Next, the operation of the above configuration will be described. Air from the air supply source 112 is supplied to the air chamber 1
14 and flows out at a constant flow rate into the air flow path 105 as an air layer while generating a sharp bend, and this air undergoes a sharp bend in the vicinity of the air discharge port 108 and the ink discharge port 107 while forming a sharp bend. Outflow from 108. On the other hand, ink is supplied to the ink chamber 106 from an ink supply source 113, and the ink supply source 113 and the ink chamber 1 are supplied by air pressure sent from the air supply source 112.
A constant pressure is applied to the ink in 06. As a result, during non-printing of the ink jet recording apparatus, the air pressure in the vicinity of the ink ejection port 107 generated by the air flow becomes 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 stops. Will be kept. When a potential difference is generated between the first electrode 109 and the second electrode 114 by the voltage applied from the signal source 115, the meniscus of the ink generated in the ink ejection port 107 by the electrostatic force due to the potential difference is changed to the air ejection port. Stretched in the direction of 108. Air flow path 10 from ink discharge port 107 to air discharge port 108
5 has an abrupt change in pressure gradient due to the air flow, the ink meniscus of the ink ejection port 107 is
When it is stretched beyond a certain length, it is rapidly accelerated and flows out of the air discharge port 108 to fly in the air flow.

[0005]

The ink jet recording apparatus utilizing such an air flow and an electrostatic force is driven at a relatively low voltage (500 V or less) in spite of the use of the electrostatic force. (10 to 20 kHz) and the capability of forming fine dots (20 to 30 μmφ).

However, there are some problems other than the recording characteristics. First, the air supply 11
2. An air supply system including the air supply pipe 110 is required. The presence of such an air supply system surely increases the cost. 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 it has been adopted, but the equipment becomes more complicated and the cost is further increased. Become.

Second, there is a problem in the method of construction. In assembling, when the ink discharge ports 107 and the air discharge ports 108 are arranged on the same concentric circle, it is necessary to precisely maintain a constant interval between the air flow paths 105. This interval is less than 100 μm,
A high degree of parallelism is required, and the variation must be kept within several μm. This is because this interval greatly affects the air pressure near the ink ejection port 107. That is, the air pressure in the vicinity of the ink ejection port 107 increases as the interval increases, approaches the pressure in the ink chamber 106, and the ink meniscus formed in the ink ejection port 107 is pushed out to the air ejection port 108 side. It is no longer held, and the ink ejection amount and the responsiveness decrease. Conversely, when this interval becomes smaller, the ink ejection amount,
The responsiveness also increases, but the ejection becomes unstable. Therefore, it is necessary to maintain an optimal air flow path interval that balances these.

In another electrostatic suction type ink jet recording system, for example, a structure as disclosed in Japanese Patent Application Laid-Open No. 58-208062, a space between an ink discharge opening and an electrode opening is larger in cross-sectional area than each opening. Is very disadvantageous when the nozzles are arranged at high density in the multi-nozzle system. In addition, if there is fine dust or ink in the space area, the state of the electric field changes and as a result, the ejection state becomes unstable,
It tends to be a problem in terms of reliability. Also, from the viewpoint of the stability of the recording characteristics, there are also difficulties in assembling such as positioning the ink ejection opening and the electrode opening and securing the parallelism.

The present invention is to solve the problem caused by the existence of the air supply system in the conventional ink jet recording apparatus, and to provide a low cost ink jet recording apparatus which is simple in structure and easy to assemble. With the goal.

[0010]

According to the present invention, there is provided a first head member having an ink discharge port in a front plate made of a thin plate and containing ink in an internal space.
A concave portion for detachably housing the first head member,
A second head member having an ink ejection opening larger than the ink ejection opening of the first head member on the front plate, the control member being formed around the ink ejection opening on the back surface of the front plate of the first head member; The electrode and a common electrode formed around the ink ejection opening on the front plate surface of the second head member are connected to a signal source.

[0011]

According to the present invention, recording is performed by applying the signal voltage between the electrodes to stretch the ink meniscus formed at the ink discharge port and to fly the ink to the outside through the ink discharge opening. In addition, the cost can be reduced by dividing the head part into two parts and simplifying the respective structures.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial cross-sectional schematic exploded perspective view of an ink jet recording apparatus according to an embodiment of the present invention.
FIG. 2 is an enlarged sectional view of a main part in FIG. 1. 1 and 2, 201 is a first head member, and 202 is a second head member, each of which is made of an insulating material. First
The head member 201 has a front plate 20 made of an insulating thin plate.
3 is formed in a box shape, and the internal space is an ink chamber 204 for storing ink. On the front plate 203,
A plurality of ink ejection ports 205 are formed in series in the horizontal direction, and a plurality of control electrodes 206 independent for each ink ejection port 205 are formed around the back surface. Each control electrode 2
06 are connected to a plurality of terminals 207 provided on the upper surface of the first head member 201, respectively.
In 04, it is in contact with the ink filled therein. The upper part of the front surface of the first head member 201 is sloped so that it can be easily mounted on the second head member 202.

On the other hand, the inner shape of the second head member 202 is formed in a recess 208 having the same shape as the first head member 201 except for the rear portion so that the first head member 201 can be housed and fixed with high precision. ing. The front plate 209 of the second head member 202 has a slit-shaped ink ejection opening 210 so that when the first head member 201 is mounted, the ink ejection openings 205 arranged in a line are aligned with the center.
Are formed. The size of the ink ejection opening 210 in the vertical direction is larger than the diameter of the ink ejection opening 205,
Assuming that the diameter of the ink ejection port 205 is several tens of μm, the size of the ink ejection port 210 is set to about 2 to 10 times the size. A single common electrode 211 is formed on the peripheral surface of the ink ejection opening 210, and a plurality of terminals 212 are provided on the upper surface of the concave portion 208 so as to contact the terminals 207 on the upper surface of the first head member 201 at the time of mounting. Have been.
And, between the terminal 212 and the common electrode 211,
A plurality of signal sources 213 corresponding to each control electrode 206 are connected. In addition, on the front surface of the ink ejection opening 210,
The recording paper 214 is arranged at a relatively short distance (2 mm or less) (see FIG. 2).

Next, the operation of the above embodiment will be described. The first head member 201 filled with the ink inside the ink chamber 204 is inserted into the recess 208 of the second head member 202, and the surface of the front plate 203 of the first head member 201 is positioned in front of the second head member 202. It is closely fixed to the back surface of the face plate 209. In this state, as shown in FIG.
The ink ejection opening 205 of the head member 201 faces the ink ejection opening 210 of the second head member 202, and the terminal 207 of the first head member 201 and the second head member 20
The second terminal 212 is in contact. When a signal voltage is applied between the electrodes 206 and 211 from the signal source 213, an electric field is concentrated on the surface of the ink meniscus formed at the front end side edge of the ink ejection port 205, and the ink is drawn forward by electrostatic force and pulled. It becomes a thread and the ink ejection opening 210
Fly forward and adhere to the recording paper 214. If the distance between the recording paper 214 and the ink ejection opening 210 is too large, the flying ink returns and the common electrode 211
This distance must be reduced as described above in order to be attracted to and adhere to.

The factors that determine the recording characteristics in the present embodiment include the shapes of the ink ejection openings 205 and 210, the thickness or relative permittivity of the front plates 203 and 209, and the physical properties of the ink. Front panel 20
The relative dielectric constants of 3 and 209 are in the effective range of about 1 to 8, and the smaller the value, the higher the response and the lower the drive voltage. Physical properties of the ink, specific resistance is important 10 ⁴ to 10
^A stable spinning state is obtained in the range of ⁸ Ωcm.

Further, by performing an ink-repellent coating process on the inner wall and the periphery of the ink ejection opening 210 and around the surface of the ink ejection opening 205, the ink ejection opening 2 is formed.
In addition to holding the ink meniscus at the leading edge of 05,
This portion also has the effect of not staining the portion with excess ink, which is an effective means for stable ejection. However, when the material forming the front plates 203 and 209 already has ink repellency like Teflon, it goes without saying that the ink repellent coating process is unnecessary.

The actual recording characteristics of the present embodiment are slightly inferior in responsiveness as compared with the conventional example shown in FIG. 3, but the structure is simple and the head section is divided into two. Therefore, simplification can be achieved in the assembling method, which is extremely advantageous in terms of cost.

Although not shown in this embodiment, if a groove is provided around each ink ejection port 205 on the surface of the front plate 203 and its outlet portion is protruded, the electric field can be efficiently concentrated, and the recording characteristics increase. I do. In the embodiment, the ink ejection openings 210 have a slit shape. However, when the arrangement density of the ink ejection openings 205 does not need to be considered so much, the ink ejection openings may be individually associated with the plurality of ink ejection openings 205. You may provide. Further, the ink ejection port 20
The present invention is also effective when 5 are arranged in a matrix.

[0019]

As described above, according to the present invention, a first head member having an ink discharge port in a front plate made of a thin plate and containing ink in an internal space, and the first head member can be detachably attached. A second head member having a recess for accommodating therein and having a larger ink ejection opening than the ink ejection opening of the first head member on the front plate, wherein the ink ejection on the back surface of the front plate of the first head member is provided. Since the control electrode formed around the outlet and the common electrode formed around the ink ejection opening on the front plate surface of the second head member are connected to the signal source, the structure is simple and the assembly is easy. A cost-effective inkjet recording apparatus can be realized, and the effect is great.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view of a main part of FIG. 1;

FIG. 3 is a schematic configuration diagram of a partial cross section of a conventional inkjet recording apparatus.

[Explanation of symbols]

 201 first head member 202 second head member 203 front plate 204 ink chamber 205 ink discharge port 206 control electrode 207 terminal 208 recess 209 front plate 210 ink discharge opening 211 common electrode 212 terminal 213 signal source 214 recording paper

Claims (3)

(57) [Claims] 1. A first head member having an ink discharge port on a front plate made of a thin plate and containing ink in an internal space;
A concave portion for detachably housing the first head member,
A second head member having a larger ink ejection opening on the front plate than the ink ejection opening of the first head member, and a control formed around the ink ejection opening on the back surface of the front plate of the first head member. An ink jet recording apparatus comprising: an electrode; a common electrode formed around an ink ejection opening on a front plate surface of the second head member; and a signal source connected to the control electrode and the common electrode. 2. A plurality of ink discharge ports of the first head member are formed in a row, and a plurality of control electrodes around the plurality of ink discharge ports are formed corresponding to the respective ink discharge ports. 2. An ink jet recording apparatus according to claim 1, wherein said ink jet recording apparatus is formed in a size to accommodate said plurality of ink ejection ports. 3. The ink jet recording apparatus according to claim 2, wherein a terminal connected to the control electrode is provided on a front surface of the first head member, and a terminal capable of contacting the terminal is provided on a back surface of the second head member.