JP2826535B2 - Electrostatic inkjet printhead - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic ink jet print head, and more particularly, to an electrostatic ink jet print head which performs recording by flying toner particles by electrostatic force using ink in which toner particles are dispersed in a carrier liquid. About.

[0002]

2. Description of the Related Art The non-impact recording method has recently attracted attention in that noise during recording is extremely small to a negligible level. Among them, the ink jet recording method that can record directly on a recording medium at high speed with a simple mechanism and that can record on plain paper is an extremely powerful recording method, and various methods have been proposed so far. Have been.

In this method, a voltage is applied between a needle-like recording electrode and an electrode provided on the back of the recording paper facing the needle-like recording electrode using an ink in which toner particles are dispersed in a carrier liquid. Fly the color material in the ink by electrostatic force,
There is a way to record.

FIG. 5 shows, for example, Japanese Patent Application No. 07-120252.
FIG. 6 is a perspective view showing the conventional ink jet print head shown in the specification, and FIG. 6 is a plan view of the head end of the ink jet print head and AA.
It is sectional drawing.

With reference to FIGS. 5 and 6, this conventional ink jet print head will be described. Substrate 21
Is made of a flat insulating material, and a plurality of recording electrodes 22 are formed on the surface thereof at intervals equivalent to the desired resolution. The recording electrode 22 is formed on the substrate 21 by sputtering a conductive material such as Cu or Ni over the entire surface of the substrate 21 and then exposing and developing the same through a mask in which the shape of the recording electrode 22 is patterned. The recording electrode 22
Are formed as independent electrodes, and the recording electrodes 22
Is connected to a driver (not shown), and a high-voltage pulse is selectively applied during recording. Further, the recording electrode 22
The insulating coating material is spin-coated on the surface of the substrate 21 on which is formed so that the ink and the recording electrode 22 are insulated.

[0006] The meniscus forming member 23 includes a recording electrode 22.
After laminating or spin-coating an insulative and photosensitive resist material on the substrate 21 on which the recording electrodes 22 are formed, exposure and development are performed through a mask in which the shape of the meniscus forming member 23 is patterned, so that each of the recording electrodes 22 Are formed so as to overlap. An upper cover 24 is mounted on the meniscus forming member 23 at a position retracted from the tip of the meniscus forming member 23. The upper cover 24 is made of an insulating material, and the ink supply port 25 and the ink discharge port 26 are processed in advance. The substrate 21, the upper cover 24, and the meniscus forming member 23 on each recording electrode 22 form a minute slit-shaped ink ejection port 27.
The ink supplied from the nozzle 5 passes through the ink ejection port 27 and is supplied to the distal ends of the meniscus forming members 23 protruding outward from the ink ejection port 27, and a meniscus is formed at each of the meniscus forming member 23 distal ends. It has become.

[0007]

However, a first problem of the above-mentioned conventional electrostatic ink jet print head is that the ejection of ink droplets from an ejection point at which ejection is performed becomes unstable. It is. The reason is that the ink at the tip of the meniscus forming member serving as the discharge point is continuously connected by the meniscus between the adjacent meniscus forming members, so that the ink on the meniscus when the ink is discharged from the discharge point. This is because the vibration of the liquid surface affects the ink at the tip of the nearby meniscus forming member.

[0008] The second problem is that a discharge from a fixed discharge point is not performed. The reason is that the tip of the meniscus forming member serving as the discharge point cannot recede from the end surface of the substrate to form a clear convex meniscus, and discharge occurs from a position other than the discharge point.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic ink jet print head which stabilizes the ejection of ink droplets.

[0010]

According to the present invention, there is provided an electrostatic ink jet print head which applies an electric field to ink in which charged toner particles are dispersed, discharges the toner particles by an electrostatic force generated by the electric field, and performs printing. In the print head of the electrostatic ink jet recording apparatus that performs
An orifice plate having an orifice formed of a plurality of micro holes; a base plate supporting the orifice plate and forming a chamber for holding ink together with the orifice plate; and a convex portion formed at the same interval as the orifice. A discharge member having a tip configured to independently project from each of said orifices.

Further, in the electrostatic ink jet print head of the present invention, an independent recording electrode is patterned on the orifice plate so as to surround the periphery of each of the orifices, and each of the recording electrodes is insulated. It is characterized by the following.

Further, in the electrostatic ink jet print head of the present invention, a migration electrode is formed on a surface of the chamber facing the orifice plate so as to be in electrical contact with the ink in the chamber. It is characterized by being.

Further, in the electrostatic ink jet print head according to the present invention, the orifice plate, the base plate and the ejection member are formed of an insulating material having a low dielectric constant.

[0014]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the electrostatic ink jet print head of the present invention.
1A is a perspective view thereof, FIG. 1B is a cross-sectional view taken along the line AA, FIG.
(C) is BB sectional drawing. FIG. 2 is a detailed view of an orifice portion of the orifice plate according to this embodiment.
2A is a diagram of the orifice plate viewed from the front, and FIG. 2B is a diagram of the orifice plate viewed from the back. FIG. 3 is a sectional view taken along the line CC in FIG.
(A)), It is DD sectional drawing (FIG.3 (b)).

Referring to FIGS. 1, 2 and 3, an electrostatic ink jet print head according to an embodiment of the present invention includes an orifice plate 2 having an orifice 1 formed of a plurality of micro holes, and an orifice plate. A base plate 5 which forms a chamber 4 for supporting the ink 2 and holding the ink 3 together with the orifice plate 2; and a protrusion formed at the same interval as the orifice 1 such that the tip of the protrusion projects independently of the individual orifice 1. And a discharge member 6.

The orifice plate 2 is made of a thin insulating material, and has an orifice 1 composed of a plurality of fine holes at the same interval as a desired dot pitch. Also, on the front or back surface of the orifice plate 2,
N formed independently so as to surround each orifice 1
A recording electrode 7 made of a metal material such as i or Al, and an electrode pad 8 connected to each recording electrode 7 and plated with a metal material such as Ni or Al by Au plating are formed by a thin film forming process. ing. Further, the surface of the orifice plate 2 on which the recording electrodes 7 are formed is coated with an insulating resin 9 except for the electrode pads 8.

The base plate 5 is a mold or machining member made of an insulating material, and has a chamber 4 for supporting the orifice plate 2 and holding the ink 3 together with the orifice plate 2. An ink supply port 10 and an ink discharge port 11 for circulating the ink 3 therein are formed. On the surface of the chamber 4 facing the orifice plate 2, an electrophoresis electrode 12 made of a metal material such as Cu capable of making electrical contact with the ink 3 in the chamber 4 is provided.

The discharge member 6 is formed of a thin plate of insulating material, and has a plurality of protrusions having the same interval as the pitch of each orifice 1 of the orifice plate 2 and the tip of which is smaller than the diameter of the orifice 1. A part is formed. The discharge member 6 is disposed in the chamber 4, and the tip of each protrusion (hereinafter, referred to as a discharge point 13) of the discharge member 6, which is the discharge point 13, is opposed to each of the orifices 1 of the orifice plate 2 by a counter electrode. It is arranged so as to protrude by a desired amount toward the 15 side.

The ink 3 is composed of toner ink in which charged toner particles serving as a coloring material are dispersed in a liquid carrier. The ink 3 is supplied from an ink tank (not shown) through an ink supply port 10 through a pump (not shown) into the print head. And then collected from the ink discharge port 11 into an ink tank (not shown), and supplied again to the chamber 4 in the print head. Thus, the ink 3 is constantly circulated between the ink tank and the chamber 4 in the print head. The ink 3 supplied to the chamber 4 is discharged onto each of the orifices 1 in the orifice plate 2 by a discharge point 13.
Is held while forming an independent meniscus 14 having a convex shape as a vertex.

The operation of this embodiment will be described with reference to FIG. 4 which is an explanatory diagram of the operation of this embodiment.

At a position facing the orifice plate 2 of the print head, a counter electrode 15 is provided with a certain gap from the discharge point 13. Recording paper 16
The paper is fed while keeping a constant gap from the discharge point 13 while making contact with the counter electrode 15 using the counter electrode 15 as a platen. The counter electrode 15 is always applied with a ground level or a bias voltage on the opposite polarity side to the polarity of the toner particles in the ink 3, and the recording paper 16 fed on the counter electrode 15 has the same potential as the counter electrode 15. Be charged.

At the time of recording standby, a bias voltage of the same polarity as the polarity of the toner particles in the ink 3 is applied to the migration electrode 12 such that the ink 3 is not discharged from the discharge point 13. Of ink 3 is a migration electrode 12
Is charged to the same potential as. Further, the toner particles in the ink 3 in the chamber 4 circulate while moving so as to gather toward the ejection point 13 on the orifice 1 by the electric field between the ink 3 and the counter electrode 15.

At the time of recording, a pulse voltage of the same polarity as the polarity of the toner particles in the ink 3 is applied to the recording electrode 7 surrounding the discharge point 13 corresponding to the desired printing, and an electric field between the recording electrode 7 and the counter electrode 15 is applied. As a result, an electrostatic force acts on the toner particles in the ink 3 on the discharge point 13, and the electrostatic force of the toner particles overcomes the surface tension of the meniscus 14 on the discharge point 13. Drops 17 are ejected toward the counter electrode 15 and printing is performed on the recording paper 16. Dots are formed on the recording paper 16 in the form of deposited toner particles, and the deposited toner particles are fixed onto the recording paper 16 by a fixing mechanism (not shown) such as a heat roller.

[0025]

As described above, the first effect of the present invention is to enable stable ejection of ink droplets from the ejection point where ejection is performed. The reason is that each of the discharge points has an orifice individually, and by forming an independent meniscus, the vibration of the liquid surface on the meniscus when the ink is discharged from the discharge point causes the discharge point to approach the discharge point. This is because it does not affect the meniscus above.

The second effect is that the discharge can always be performed from a predetermined discharge point. The reason is that the discharge point is formed as a minute convex point protruding from the orifice plate with respect to the counter electrode, and further, the meniscus is formed by the orifice formed of the minute hole, so that the meniscus fluctuation with the discharge point at the top is considered. This is because a small convex meniscus can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of an electrostatic ink jet print head according to the present invention, FIG. 1 (a) is a perspective view thereof, FIG. 1 (b) is a sectional view taken along AA, FIG. ) Is a BB cross-sectional view.

FIG. 2 is a detailed view of an orifice portion of the orifice plate according to the embodiment, FIG. 2 (a) is a view of the orifice plate from the front, and FIG. 2 (b) is a view of the orifice plate from the back. is there.

3 is a sectional view taken along the line CC in FIG. 2 (FIG. 3A), FIG.
FIG. 3D is a sectional view (FIG. 3B).

FIG. 4 is a diagram illustrating the operation of this embodiment.

FIG. 5 is a perspective view of a conventional electrostatic ink jet print head.

FIG. 6 is a plan view (FIG. 6A) and a cross-sectional view taken along the line AA (FIG. 6B) of the head end portion of the conventional electrostatic ink jet print head.

[Explanation of symbols]

 Reference Signs List 1 orifice 2 orifice plate 3 ink 4 chamber 5 base plate 6 discharge member 7 recording electrode 8 electrode pad 9 insulating resin 10 ink supply port 11 ink discharge port 12 migration electrode 13 discharge point 14 meniscus 15 counter electrode 16 recording paper 17 ink drop

Continued on the front page (72) Inventor Hitoshi Minemoto 7546 Yasuda, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. (72) Inventor Hitoshi 7546 Yasuda, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. (72) Inventor Yoshihiro Hagiwara 7546 Yasuda, Oji, Kashiwazaki, Niigata Inside Niigata Nippon Electric Co., Ltd. (72) Inventor Toru Yakushiji 7546, Yasuda, Oji, Kashiwazaki, Niigata Niigata Nippon Electric Co., Ltd. (56) References JP-A-8-258270 (JP, A) JP-A-9-123458 (JP, A) JP-A-9-164688 (JP, A) JP-A-9-239988 (JP, A) JP-A 9-254372 (JP JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/06 B41J 2/16

Claims (4)

(57) [Claims] 1. A print head of an electrostatic ink jet recording apparatus for applying an electric field to ink in which charged toner particles are dispersed, discharging the toner particles by electrostatic force generated by the electric field, and performing printing. An orifice plate having an orifice formed of micro holes, a base plate supporting the orifice plate and forming a chamber for holding ink together with the orifice plate, and a convex portion formed at the same interval as the orifice, and the tip of the convex portion is formed. A discharge member configured to project independently from each of said orifices. 2. The static recording device according to claim 1, wherein an independent recording electrode is patterned on the orifice plate so as to surround a periphery of each of the orifices, and each of the recording electrodes is coated with an insulating film. Electric inkjet print head. 3. The electrophoresis electrode according to claim 1, wherein a migration electrode is formed on a surface of the chamber facing the orifice plate so as to be in electrical contact with ink in the chamber. The electrostatic ink jet print head as described in the above. 4. The electrostatic ink jet print head according to claim 1, wherein said orifice plate, said base plate and said discharge member are formed of an insulating material having a low dielectric constant.