JP2788886B2 - Electrostatic ink jet recording head - 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 recording head, and more particularly to an electrostatic ink jet recording head which performs recording by attaching toner particles to a recording medium.

[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 directly perform high-speed recording on a recording medium with a simple mechanism and that can perform recording on plain paper is an extremely powerful recording method, and various methods have been proposed so far. ing. Among them, there is a method in which a voltage is applied between an electrode provided on the back surface of a recording paper and a needle electrode facing the electrode, and a color material such as ink is caused to fly by an electrostatic force of the generated electric field, thereby performing recording.

FIG. 6 is a perspective view showing an example of a conventional ink jet recording head. Referring to FIG. 6, the print head 20 includes a substrate 21 and a cover 24,
A slit-shaped ink jet port 23 for holding ink is provided between these. A plurality of recording electrodes 22 are arranged on the substrate 21 in a direction from the ink ejection port 23 to the counter electrode 25. Electric wires (not shown) are connected to these recording electrodes 22, and a high-voltage pulse is selectively applied to these recording electrodes 22 during recording.

On the other hand, the printing paper 2 facing the recording electrode 22
A counter electrode 25 is provided on the back surface of the recording electrode 6, and an electric field is generated between the recording electrode 22 and the recording electrode 22 during recording. The recording electrode 22 is formed in a thin needle shape, and an electric field concentrates on the tip thereof.
As a result, electric charges are accumulated in the ink near the recording electrode 22.

The process of accumulating charges differs depending on the type of ink used. Electrostatic induction is dominant in conductive inks, and polarization is dominant in dielectric inks. Further, in the ink in which the coloring material particles serving as the base of the color are dispersed, the coloring material particles themselves have an apparent charge due to the zeta potential, and the charged coloring material migrates due to the electric field concentrated at the tip of the recording electrode 22. .

In any case, the Coulomb force acting on the accumulated electric charges causes the ink or the coloring material particles in the ink to be pulled in the direction of the counter electrode 25, that is, in the direction of the printing paper 26. When the Coulomb force becomes stronger than the surface tension of the ink, the ink flies and adheres to the printing paper 26. At this time, desired recording can be performed by appropriately controlling the high voltage pulse applied to the recording electrode 22 according to the print image.

However, since the conductivity and permittivity of the ink used for printing is higher than the conductivity and permittivity of air, the location where the electric field concentrates is not determined only by the arrangement of the recording electrodes 22, and the ink jetting is not performed. It also depends on the state of the ink meniscus at the outlet 23. That is, in FIG. 6, the ink meniscus is expected to be uniform in the longitudinal direction of the ink ejection port 23. However, in actuality, the processing accuracy of the ink ejection port 23 and the meniscus of the meniscus after the ink ejection is performed. Due to the vibration and the natural fluctuation of the meniscus, minute irregularities are generated.

In this case, the electric field is more concentrated on the minute meniscus projection near the recording electrode 22 due to the conductivity and dielectric properties of the ink. Once the meniscus starts to be deformed by the Coulomb force, the electric field is concentrated more strongly, and eventually, a minute unevenness of the meniscus is generated in the initial stage, so that the portion where the ink flies cannot be appropriately controlled. In other words,
Even if a high voltage pulse is applied to a certain recording electrode 22, the ink flies from a position that does not correspond to the recording electrode 22,
Recording may not be performed at a desired position. This leads to a significant deterioration in print quality.

For the purpose of solving the above disadvantages, Japanese Patent Application Laid-Open No.
In Japanese Patent Application Laid-Open No. 228162/1992, as shown in FIG.
A structure is disclosed in which a predetermined convex portion 28 is provided at a position corresponding to the recording electrode 27 at the front end portion of the device 1 so that the ink meniscus is provided with irregularities in advance and an electric field is concentrated on the recording electrode 27. . The print head 30 includes a reinforcing plate 29 at a position where each recording electrode 27 is partitioned.
Are arranged.

FIG. 8 is a perspective view showing another example of the conventional ink jet recording head, and FIG. 9A is a top view of the head end of the ink jet recording head.
(B) is the AA sectional view. Referring to FIGS. 8 and 9, a substrate 41 is an insulator such as glass, and a plurality of recording electrodes 42 are formed on the surface thereof. Recording electrode 42
Is a conductive material such as chromium sputtered over the entire surface of the substrate 41 and patterned by photolithography.
For example, they are arranged at a pitch of 300 dpi (dots per inch), that is, at an interval of about 85 μm. The recording electrode 42 is connected to a driver (not shown), and can selectively apply a high voltage pulse to the recording electrode 42 during recording.

The meniscus forming member 43 is formed by processing a photosensitive polymer film laminated on the substrate 41 by photolithography, and is formed at a position slightly receded from the leading end of the recording electrode 42 so as to overlap each recording electrode 42. Have been. The thickness of the photosensitive polymer film is 30 μm, and the width of the meniscus forming member 43 is about 30 μm. A cover 44 is mounted on the meniscus forming member 43 at a position further retracted from the tip of the meniscus forming member 43. The cover 44 is an insulating member, and the ink supply port 45 and the ink discharge port 46 are processed in advance. The substrate 41 and the cover 44 form a slit-shaped ink ejection port 47, and a meniscus forming member 43 riding on the recording electrode 42 protrudes outside the ink ejection port 47. The meniscus forming member 43 also has a purpose of supporting the cover 44, and therefore also partially extends below the cover 44. Further, when the meniscus forming member 43 is formed, a continuous wall surface is simultaneously formed on the head side portion and the rear end portion, so that the ink chamber is constituted together with the substrate 41 and the cover 44.

[0012]

However, in the above-mentioned conventional electrostatic ink jet recording head, a plurality of recording electrodes 42 are patterned by photolithography on a conductive material such as chromium which is formed by sputtering the entire surface of a substrate 41. Further, since the meniscus forming member 43 is formed by processing a photosensitive polymer film laminated on a substrate by photolithography, there is a problem that the manufacturing process of the head is complicated and the cost of the head cannot be reduced. Furthermore, since the meniscus forming member 43 is formed of a photosensitive polymer film, the thickness of the meniscus forming member 43 is limited by the thickness of the film, and there is a problem that the ink supply amount is limited.

SUMMARY OF THE INVENTION An object of the present invention is to provide a low cost and reliable multi-element electrostatic ink jet recording head for discharging only toner particles in ink by an electrostatic field. To supply the head.

[0014]

An electrostatic ink jet recording head according to the present invention comprises a base film having an insulating property and one side of the base film, one end of which protrudes from the end of the base film. A plurality of recording electrodes are formed and the surface of which is covered with an insulating coating material, and a cover is formed on the recording electrode surface and holds ink containing toner particles therein.

Further, in the electrostatic ink jet recording head according to the present invention, the cover is in close contact with the recording electrode near the recording electrode, and the ink flows between the plurality of recording electrodes.

Further, in the electrostatic ink jet recording head of the present invention, an electrophoretic electrode is provided in the cover so as to be in contact with the ink in order to convey the toner particles to the vicinity of the recording electrode.

Further, the insulating base film and the recording electrode of the electrostatic ink jet recording head of the present invention are used in a tape automated bonding technique.
The tape is integrally formed with a three-layer or three-layer tape.

[0018]

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

FIG. 1 is a perspective view of an electrostatic ink jet recording head according to an embodiment of the present invention. Referring to FIG. 1, a substrate 1 is an insulator such as plastic and supports a base film 10 from the back side. The base film 10 is an insulator such as polyimide and has a thickness of 5
A plurality of recording electrodes 2 are integrally formed on the surface thereof. The recording electrode 2 is a base film 10
A conductive material such as copper is pattern-plated thereon to a thickness of 20 to 30 μm, and is arranged at a pitch of 300 dpi, that is, at an interval of about 85 μm. Also, the recording electrode 2
The protrusions protrude independently from the end faces of the base film 10, and the protrusion amount is about 80 μm to 500 μm. Further, the surface of the recording electrode 2 is uniformly covered with an insulating coating member 3 with a thickness of 10 μm or less.

According to the recording head of the present invention, the base film 1
A tape-shaped head in which the recording electrode 2 is integrally formed on the recording head 2 is used. Specifically, Tape Automated Bonding (T
AB) The TAB tape used in the technique is used, and the insulating coating member 3 is formed by chemical vapor deposition of parylene resin.

A cover 4 is mounted on the base film 10 at a position that does not cover the projection of the recording electrode 2. The cover 4 is an insulating member, and the ink supply port 5 and the ink discharge port (not shown) are processed in advance. The space defined by the base film 10 and the cover 4 forms an ink chamber. It is filled from the ink supply port 5 and filled inside. Further, the cover 4 has an opening at the tip end, and a slit-shaped opening formed by the base film 10 and the cover 4 forms an ink ejection port 7 where an ink meniscus is formed.

The ink jet head of the present embodiment is
It is connected to an ink tank (not shown) by a tube, applies a negative pressure of about 1 cmH ₂ O, and forcibly circulates ink. The ink is obtained by dispersing fine particles of a thermoplastic resin, a so-called toner, which is colored together with a charge control agent in a petroleum organic solvent (isoparaffin), and the toner is apparently charged to a positive polarity by a zeta potential.

FIG. 2 is an enlarged view (FIG. 2A) of the vicinity of the ink ejection port 7 (part A) when ink is supplied from the ink jet head according to the present embodiment, as viewed from above.
2A shows a cross section (FIG. 2B). Referring to FIG. 2 in conjunction with FIG. 1, the ink 6 forms an ink meniscus 8 at the ink ejection port 7 due to its surface tension. Since a negative pressure is applied to the ink 6 in the head and the recording electrode 2 protrudes from the base film 10 and the cover 4, the ink meniscus 8 has a concave shape obliquely downward when viewed from the side. Furthermore, since each recording electrode 2 individually protrudes outside the ink ejection port 7, an ink meniscus 8 is formed corresponding to each recording electrode 2 when viewed from above. Therefore, when a high voltage pulse is applied to an arbitrary recording electrode 2, the ink meniscus 8 protruding from the recording electrode 2 portion
The electric field is concentrated at the tip. The charged toner in the ink 6 is guided by this electric field, is drawn out from the tip of the protruding ink meniscus 8, and forms a toner group 9 in the direction of a counter electrode (not shown) facing the recording head, that is, in the printing paper direction. To fly. The toner adhering to the printing paper and forming the recording dots is heated and fixed by the heater.

FIG. 3 is a schematic view of a TAB tape used in the electrostatic recording head of the present invention. Referring to FIG.
A method of manufacturing the AB tape 12 will be schematically described. Flash plating is performed on a tape-like base film 10 such as polyimide having sprocket holes 15 at both ends. Next, a dry film is laminated, and a pattern is formed by exposure and development. Thereafter, the base film 10 is etched by pattern plating with copper or the like, and the through holes 14 are formed. Thereafter, the resist film is removed and finish plating is performed. Thereafter, an insulating coating member is chemically vapor-deposited where necessary, and used as a recording head. In this process, the inner lead portions 13 protruding where the base film 10 is removed by etching become the recording electrodes 2.

FIG. 4 is a perspective view of another embodiment of the present invention. Referring to FIG. 4, in this embodiment, in addition to the configuration of the above-described embodiment, a migration electrode 11 that is in contact with ink 6 is formed inside cover 4. Electrophoresis electrode 1
Reference numeral 1 denotes a state in which a voltage having the same polarity as the potential of the toner is applied, and the toner particles in the ink 6 supplied from the ink supply port 5 are electrically transferred to the vicinity of the recording electrode 2 by an electric field between the migrating electrode 11 and a counter electrode (not shown). Convey by electrophoresis.

FIG. 5 is an enlarged view (FIG. 5 (a)) of the vicinity of the ink ejection port 7 when the ink 6 is supplied from a recording head according to still another embodiment of the present invention as viewed from above (FIG. 5 (a)). −
Section A (FIG. 5 (b)) and section BB (FIG. 5 (c))
Is shown. Referring to FIGS. 5A, 5B, and 5C, a cover 4 is mounted on the base film 10 at a position where the protrusion of the recording electrode 2 is not covered. The cover 4 is an insulating member, and an ink supply port (not shown) and an ink discharge port (not shown) are processed in advance. The space defined by the base film 10 and the cover 4 forms an ink chamber, and the ink 6 is filled from the ink supply port to fill the inside. Further, the cover 4 has a configuration in which the front end portion is not particularly opened, and the cover 4 is in close contact with the base film 10. Base film 10
The pattern of the upper recording electrode 2 has a thickness of 20 to 30 μm.
m, the space between the portion where the pattern of the recording electrode 2 has no pattern and the cover 4 forms the ink flow path 16. The slit-shaped opening forms an ink ejection port 7, and an ink meniscus 8 is formed therein. That is, the ink flow path 16 and the ink ejection port 7 are formed without specially processing the tip of the cover 4.

[0027]

As described above, in the electrostatic ink jet recording head of the present invention, the inner lead portion of the TAB tape is coated with an insulating coating to form a recording electrode. There is an effect that cost can be reduced. Further, in the present recording head, it is necessary to configure a plurality of recording electrodes with high density and high precision. However, by using the present manufacturing process, a stable recording electrode interval and a stable electrode protrusion amount can be secured. Furthermore,
Since the head is tape-shaped, the head can be made thinner and smaller.

[Brief description of the drawings]

FIG. 1 is a perspective view of an electrostatic ink jet recording head according to an embodiment of the present invention.

FIG. 2 is an enlarged view (FIG. 2 (a)) and a cross-sectional view taken along the line AA of the vicinity of an ink ejection port (part A) in a state where ink is supplied in the ink jet head of the embodiment of FIG. (FIG. 2B).

FIG. 3 is a schematic view of a TAB tape used for the electrostatic recording head of the present invention.

FIG. 4 is a perspective view of an electrostatic ink jet recording head according to another embodiment of the present invention.

FIG. 5 is an enlarged view (FIG. 5 (a)) of the vicinity of an ink ejection port when ink is supplied from an electrostatic ink jet recording head according to still another embodiment of the present invention, as viewed from above (FIG. 5 (a)); A section (FIG. 5B) and BB section (FIG.
(C)).

FIG. 6 is a perspective view of a conventional electrostatic ink jet recording head.

FIG. 7 is a perspective view of another conventional electrostatic ink jet recording head.

FIG. 8 is a perspective view of still another conventional electrostatic ink jet recording head.

9 is a top view (FIG. 9A) of the head end portion of the ink jet recording head of FIG. 8 and a cross-sectional view taken along the line AA (FIG. 9B).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording electrode 3 Insulating coating member 4 Cover 5 Ink supply port 6 Ink 7 Ink ejection port 8 Ink meniscus 9 Toner group 10 Base film 11 Migration electrode 12 TAB tape 13 Inner lead part 14 Through hole 15 Sprocket hole 16 Ink flow Road

Continued on the front page (72) Inventor Ryosuke Agematsu 7546 Tajiri Industrial Park, Kashiwazaki City, Niigata Prefecture Niigata Nippon Electric Co., Ltd. (72) Inventor Hitoshi Minemoto 7546 Tajiri Industrial Park, Kashiwazaki City, Niigata Prefecture Niigata Nippon Electric Co., Ltd. 72) Inventor Tohru Yakushiji 7546 Tajiri Industrial Park, Kashiwazaki-shi, Niigata Prefecture Niigata Nippon Electric Co., Ltd. (72) Inventor Tadashi Mizoguchi 7546 Tajiri Industrial Park, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. Tsuji, Kashiwazaki-shi, Niigata Pref. 7546 Inside Niigata Nippon Electric Co., Ltd. (56) References JP-A-3-504836 (JP, A) JP-A-6-21936 (JP, A) JP-A-7-1739 ( JP, A) JP-A-58-188863 (JP, A) JP-A-9-57979 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/06

Claims (4)

(57) [Claims] 1. A base film having an insulating property, the base film being formed on one side of the base film, one end of the base film protruding from an end of the base film, and the surface thereof being covered with an insulating coating material. A plurality of recording electrodes, and a cover formed above the recording electrode surface and holding ink containing toner particles therein. 2. The electrostatic ink jet recording head according to claim 1, wherein the recording electrode near the cover is in close contact with the recording electrode, and the ink flows between the plurality of recording electrodes. 3. The electrophoretic electrode according to claim 1, wherein an electrophoresis electrode is provided in the cover so as to be in contact with the ink in order to transport the toner particles to the vicinity of the recording electrode.
The electrostatic ink jet recording head according to the above. 4. The recording medium according to claim 1, wherein the insulating base film and the recording electrode are integrally formed on a two-layer or three-layer tape used in Tape Automated Bonding technology. 3. The electrostatic ink jet recording head according to 2.