JP2818581B2 - 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.

In this method, a voltage is applied between an electrode provided on the back surface of a recording paper and a needle electrode facing the recording paper, and a color material such as ink is caused to fly by an electrostatic force of the generated electric field, thereby performing recording. There is.

FIG. 8 shows, for example, Japanese Patent Application No. 07-120252.
FIG. 9 is a perspective view showing a first example of this conventional ink jet recording head shown in the specification, and FIG. 9 is a plan view and a cross-sectional view of the head end portion of this ink jet recording head.

[0005] A first example of this conventional ink jet recording method will be described with reference to FIGS. 8 and 9. The substrate 21 is an insulator such as glass, and has a plurality of recording electrodes 22 on its surface.
Are formed. The recording electrode 22 is obtained by patterning a conductive material such as chromium sputtered on the entire surface of the substrate by photolithography, and is, for example, 300 dpi (dot per inch).
ch) pitch, that is, at intervals of about 85 μm. The recording electrode 22 is connected to a driver (not shown), and can selectively apply a high voltage pulse to the recording electrode 22 during recording.

The meniscus forming member 23 is formed by processing a photosensitive polymer film laminated on the substrate 21 by photolithography, and is formed at a position slightly receded from the leading end of the recording electrode 22 so as to overlap each recording electrode 22. Have been. The thickness of the photosensitive polymer film is 30 μm, and the width of the meniscus forming member 23 is about 30 μm. A cover 24 is mounted on the meniscus forming member 23 at a position further retracted from the tip of the meniscus forming member 23. The cover 24 is an insulating member, and the ink supply port 25 and the ink discharge port 26 are processed in advance. The substrate 21 and the cover 24 form a slit-shaped ink ejection port 27, and a meniscus forming member 23 on the recording electrode 22 protrudes outside the ink ejection port 27. The meniscus forming member 23 also has a purpose of supporting the cover 24, and therefore partially extends below the cover 24. Further, when the meniscus forming member 23 is formed, a continuous wall surface is simultaneously formed on the head side portion and the rear end portion, and the substrate 21 and the cover 24 constitute an ink chamber.

FIG. 10 shows, for example, Japanese Patent Application No. 08-01289.
FIG. 7 is a perspective view showing a second example of a conventional electrostatic inkjet recording head shown in the specification of Japanese Patent Publication No. 7-107. Referring to FIG. 10, the substrate 31 is an insulator such as plastic, and supports the base film 40 from the back side. The base film 40 is an insulator such as polyimide, has a thickness of about 50 μm, and has a plurality of recording electrodes 32 integrally formed on its surface. The recording electrodes 32 are formed by pattern-plating a conductive material such as copper on the base film 40 to a thickness of 20 to 30 μm, and are arranged at a pitch of 300 dpi, that is, at intervals of about 85 μm. In addition, the recording electrodes 32 protrude independently from the end faces of the base film 40, and the protruding amount is 80 μm to 500 μm.
It is about μm. Further, the surface of the recording electrode 32 is uniformly covered with an insulating coating member 33 with a thickness of 10 μm or less.

[0008] This conventional electrostatic ink jet recording head uses a tape-shaped head in which recording electrodes 32 are integrally formed on a base film 40.
A TAB tape used for pe Automated Bonding (TAB) technology is used, and an insulating coating member 33 is formed by chemical vapor deposition of parylene resin.

On the base film 40, a recording electrode 32 is provided.
The cover 34 is attached at a position that does not cover the protruding portion. The cover 34 is an insulating member, and the ink supply port 35 and the ink discharge port (not shown) are processed in advance. The space defined by the base film 40 and the cover 34 forms an ink chamber. It is filled from the ink supply port 35 and is filled inside. Further, the cover 34 has an opening at the tip, and the base film 4
The slit-shaped opening formed by the cover 0 and the cover 34 forms an ink ejection port 37, in which an ink meniscus is formed. An electrophoresis electrode 41 that is in contact with the ink 36 is formed inside the cover 34. The migration electrode 41
A voltage having the same polarity as the potential of the toner is applied, and the toner particles in the ink 36 supplied from the ink supply port 35 are separated by the electric field between the migrating electrode 41 and a counter electrode (not shown).
It is transported to the vicinity of 2 by the electrophoresis phenomenon.

FIG. 11 is an enlarged view of the vicinity (part A) of the ink ejection port 37 of this conventional electrostatic ink jet recording head in a state where ink is supplied (see FIG. 11).
(A)) and AA cross section (FIG. 11 (b)) are shown. Referring to FIG. 11 in conjunction with FIG. 10, the ink 36 is applied to the ink ejection port 37 by the surface tension of the ink meniscus 3.
8 is formed. Since a negative pressure is applied to the ink 36 in the head and the recording electrode 32 protrudes from the base film 40 and the cover 34, the ink meniscus 38 has a concave shape obliquely downward when viewed from the side.
Furthermore, since each recording electrode 32 individually protrudes outside the ink ejection port 37, an ink meniscus 38 is formed corresponding to each recording electrode 32 when viewed from above. Therefore, when a high-voltage pulse is applied to an arbitrary recording electrode 32,
The ink meniscus 38 protruding from the recording electrode 32 portion.
The electric field is concentrated at the tip. The charged toner in the ink 36 is guided by this electric field, is drawn out from the tip end of the protruding ink meniscus 38, and forms a toner group 39. To fly. The toner adhering to the printing paper and forming the recording dots is heated and fixed by the heater.

[0011]

However, the first problem of the above-mentioned conventional ink jet recording head is that the head cost is high. The reason is that the manufacturing process is complicated because a head is manufactured on a substrate by a thin film forming technique (photolithography).

A second problem is that the thickness of the meniscus forming member is limited by the thickness of the film, and the amount of ink supply is limited. The reason is that the meniscus forming member is formed of a photosensitive polymer film.

A third problem is that it is difficult to always supply a proper toner. The reason is,
This is because the supply of the toner particles to the ink ejection port is performed only by the electrophoretic force of the toner by the electrophoretic electrode.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrostatic ink jet recording head which discharges only toner particles in an ink by an electrostatic field, and always supplies a proper toner. And to provide a more reliable and lower cost multi-element head.

[0015]

According to the present invention, there is provided an electrostatic ink jet recording head comprising a base film having an insulating property and a surface of the base film, one end of which protrudes from the end of the base film. A plurality of recording electrodes, the surfaces of which are formed and further coated with an insulating coating material, are sandwiched so as not to cover the recording electrodes with the base film, and a gap between the recording electrodes from the front surface to the back surface of the base film. And an upper cover and a lower cover for supplying and holding the ink containing the toner particles by passing the ink.

Further, the electrostatic ink jet recording head of the present invention, when supplying the ink containing the toner particles,
An electrophoretic electrode is disposed in the upper cover at a position upstream of the recording electrode section so as to be in contact with the ink.

Further, in the electrostatic ink jet recording head of the present invention, when supplying the ink containing the toner particles, the electrostatic ink jet recording head is located upstream of the recording electrode portion in the upper cover, and is provided in the lower cover. An electrophoresis electrode is provided at a position downstream of the recording electrode portion so as to be in contact with the ink, and the two electrophoresis electrodes are electrically connected.

Further, in the electrostatic ink jet recording head according to the present invention, the upper cover and the lower cover are in close contact with the recording electrodes near the recording electrodes, and the ink flows between the plurality of recording electrodes. I do.

Further, in the electrostatic ink jet recording head according to the present invention, the upper cover is in close contact with the recording electrode in the vicinity of the recording electrode, and the lower cover is in close contact with the base film in the vicinity of the recording electrode. Wherein the ink flows between the recording electrodes.

Further, in the electrostatic ink jet recording head of the present invention, the insulating base film and the recording electrodes are integrally formed on a two-layer or three-layer tape used in Tape Automated Bonding technology. It is characterized by being.

[0021]

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 one embodiment of the present invention, FIG. 2 is a plan view of a head end portion of this embodiment, and FIG. It is sectional drawing.

Referring to FIGS. 2 and 3 in conjunction with FIG.
The electrostatic ink jet recording head of this embodiment is
A base film 10 having an insulating property, and a plurality of base films formed on the surface of the base film 10 and having one end protruding from an end of the base film 10 and further covering the surface with an insulating coating material. An upper cover 4 for sandwiching the recording electrode 2 and the base film 10 so as not to cover the recording electrode 2 and for supplying and holding ink containing toner particles by passing a gap between the recording electrodes 2 from the front surface to the back surface of the base film 10. And the lower cover 3.

The substrate 1 is an insulator such as plastic, and supports the base film 10 from the back side. The base film 10 is made of an insulator such as polyimide and has a thickness of about 50 μm.
Are integrally formed on the surface. The recording electrode 2 is made of a conductive material such as copper on the base film 10 by 20 to 30 μm.
m, for example, 300d
They are arranged at a pi pitch, that is, at intervals of about 85 μm. The recording electrodes 2 project independently from the end faces of the base film 10, and the amount of projection is 8
It is about 0 μm to 500 μm. Further, the recording electrode 2
The surface of the tip is uniformly covered with an insulating coating member 17 having a thickness of 10 μm or less.

In the electrostatic ink jet recording head of this embodiment, a tape-shaped head in which the recording electrodes 2 are integrally formed on a base film 10 is used. Specifically, Tape Automated Bonding (TAB) technology Is used, and the insulating coating member 17 is further formed by chemical vapor deposition of parylene resin.

The upper cover 4 and the lower cover 3 are attached at positions that do not cover the protruding portions of the recording electrodes 2 so as to sandwich the recording electrodes 2 protruding from the base film 10. The upper cover 4 is an insulating member, and the ink supply port 5 is processed in advance. The space defined by the base film 10 and the upper cover 4 constitutes an ink chamber. Filled and filled inside. Further, the upper cover 4 has an opening at the tip end, and a slit-shaped opening formed by the base film 10 and the upper cover 4 forms an ink ejection port 7, where an ink meniscus is formed. I have. The lower cover 3 is made of an insulating material, and an ink outlet (not shown) is processed in advance. The space defined by the base film 10 and the lower cover 3 also forms an ink chamber. The ink passes through the space between the recording electrode 2 and the ink ejection port 7 and is discharged from an ink discharge port (not shown) via the ink chamber.

The electrostatic ink jet recording head of this embodiment is connected to an ink tank (not shown) by a tube, applies a negative pressure of about 1 cmH ₂ O, and forcibly circulates the 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.

The ink forms an ink meniscus 8 at the ink ejection port 7 by its surface tension. A negative pressure is applied to the ink in the head, and the recording electrode 2 is made of a base film 10, an upper cover 4, and a lower cover 3.
When viewed from the side, the ink meniscus 8 has a concave shape obliquely downward on the upper cover 4 side and a symmetrical shape on the lower cover 3 side when viewed from the side. Furthermore, since each recording electrode 2 individually protrudes outside the ink ejection port 7, the ink meniscus 8 forms an ink meniscus individually 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 electric field is concentrated on the tip of the ink meniscus protruding from the recording electrode 2. The charged toner in the ink is guided by this electric field, drawn out from the tip of the protruding ink meniscus, and forms a toner group 9 and flies in the direction of the recording paper, not shown, facing the recording head. . The toner adhering to the recording paper and forming the recording dots is heated by a heater and fixed.

FIG. 4 is a schematic diagram of a TAB tape used in the electrostatic ink jet recording head of this embodiment. A method of manufacturing the TAB tape 12 will be briefly described. Flash plating is performed on a tape-like base film 10 such as polyimide having sprocket holes 15 at both ends. Next, dry film is laminated and exposed,
A pattern is formed by 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 base film 10
The inner lead portion 13 protruding from the portion where is removed by etching becomes the recording electrode 2.

FIG. 5 is a perspective view and a sectional view of another embodiment of the present invention. In this embodiment, in addition to the configuration of the above-described embodiment, an electrophoresis electrode 11 that is in contact with ink is formed inside the upper cover 4. Electrophoresis electrode 11
Is applied with a voltage having the same polarity as the potential of the toner, and causes the toner particles in the ink supplied from the ink supply port 5 to move toward the recording electrode 2 in the vicinity of the recording electrode 2 by an electric field between the migrating electrode 11 and a counter electrode (not shown). To be transported. For this reason, in addition to the supply of the toner particles to the vicinity of the ink ejection port 7 due to the forced ink circulation by the pump, the toner particle concentration in the vicinity of the ink ejection port 7 is increased upstream of the ink chamber by the electrophoretic movement of the toner particles. It is relatively higher than that. Therefore, when a high voltage pulse is applied to an arbitrary recording electrode 2, the charged toner in the ink is guided by the electric field generated at the recording electrode 2 to form a sufficient amount of toner group 9, and the recording head , Which flies in the direction of the recording paper. However, the ink passes through the gap between the recording electrodes 2 and is forcibly discharged to an ink outlet (not shown) together with the surplus toner particles.

FIG. 6 is a sectional view of still another embodiment of the embodiment of FIG. In this embodiment, in addition to the configuration of the above-described embodiment, a migration electrode 11 that is in contact with ink is formed inside the upper cover 4 and inside the lower cover 3, and they are electrically connected. Electrophoresis electrode 11
Is applied with a voltage having the same polarity as the potential of the toner, and causes the toner particles in the ink supplied from the ink supply port 5 to move toward the recording electrode 2 in the vicinity of the recording electrode 2 by an electric field between the migrating electrode 11 and a counter electrode (not shown). To be transported. For this reason, in addition to the supply of the toner particles to the vicinity of the ink ejection port 7 due to the forced ink circulation by the pump, the toner particle concentration in the vicinity of the ink ejection port 7 is increased upstream of the ink chamber by the electrophoretic movement of the toner particles. It is relatively higher than that. Further, the toner particles move in the direction opposite to the movement of the counter ion toner particles having the polarity opposite to the charge of the toner particles generated by the electrophoretic movement, and are finally attracted to the electrophoresis electrode 11. Therefore, when a high voltage pulse is applied to an arbitrary recording electrode 2, the charged toner in the ink is guided by the electric field generated at the recording electrode 2 to form a sufficient amount of toner group 9, and the recording head , Which flies in the direction of the recording paper. However, the surplus toner particles and counter ions that have not been discharged pass through the gap between the recording electrodes 2 and are forcibly discharged to an ink discharge port (not shown).

FIG. 7 is a sectional view of still another embodiment of the above-described embodiment. In this embodiment, the upper cover 4 has a configuration in which the tip portion is in close contact with the recording electrode 2. Since the pattern of the recording electrode 2 on the base film 10 has a thickness of about 20 to 30 μm, the space between the portion where the pattern of the recording electrode 2 is not provided and the upper cover 4 forms an ink flow path. The slit-shaped opening forms an ink ejection port 7 and an ink meniscus 8
Are formed. That is, the ink flow path and the ink ejection port 7 are formed without specially processing the tip of the upper cover 4.

[0033]

The first effect is that the cost of the recording head can be reduced. The reason is that an insulating coating is applied to the inner lead portion of the TAB tape to form a recording electrode, so that the manufacturing process of the recording head is simple.

The second effect is that a stable recording electrode interval and a stable recording electrode protrusion amount can be secured. The reason is that a plurality of recording electrodes can be formed with high density and high accuracy by using the head manufacturing process of the present invention.

A third effect is that the recording head can be made thinner and smaller. The reason is that the recording head is made of TAB tape.

A fourth effect is that reliable toner ejection can be obtained irrespective of printing conditions. The reason is that the ink is made to flow through the gap between the recording electrodes, so that excess toner particles and counter ions are forcibly discharged from the vicinity of the recording electrode, so that stable toner particles are always kept near the recording electrode. This is because they are supplied.

[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 a plan view of a head end portion of the embodiment of FIG.

FIG. 3 is a sectional view taken along the line AA in FIG.

FIG. 4 is a schematic view of a TAB tape used in the electrostatic ink jet recording head of the embodiment of FIG.

FIG. 5 is a perspective view and a cross-sectional view of another embodiment of the present invention.

FIG. 6 is a cross-sectional view of still another embodiment of the embodiment of FIG.

FIG. 7 is a sectional view of still another embodiment of the embodiment of FIG. 6;

FIG. 8 is a perspective view showing a first example of a conventional inkjet recording head.

9 is a plan view and a cross-sectional view of a head end portion of the ink jet recording head of FIG.

FIG. 10 is a perspective view showing a second example of a conventional electrostatic ink jet recording head.

11 is an enlarged view (FIG. 11 (a)) of the vicinity of the ink ejection port (part A) of the conventional electrostatic ink jet recording head of FIG. 10 in a state where ink is supplied (FIG. 11 (a)) and AA. A cross section (FIG. 11B) is shown.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording electrode 3 Lower cover 4 Upper cover 5 Ink supply port 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 17 Insulating coating member

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ryosuke Agematsu 7546 Yasuda, Oji, Kashiwazaki, Niigata Inside Niigata Nippon Electric Co., Ltd. In-house (72) Inventor Toru Yakushiji 7546 Yasuda, Kashiwazaki-shi, Niigata Prefecture Niigata Nippon Electric Co., Ltd. Inventor Tadashi Mizoguchi 7546 Yasuda, Kashiwazaki-shi, Niigata Niigata Nippon Electric Co., Ltd. (56) References JP-A-10-809 (JP, A) JP-A-10-808 (JP, A) JP-A-9 -201971 (JP, A) JP-A-9-201970 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/06

Claims (6)

(57) [Claims] 1. A base film having an insulating property, wherein the base film is formed on a surface of the base film and one end of the base film protrudes from an end of the base film, and the surface is further covered with an insulating coating material. And a plurality of recording electrodes, and an upper that sandwiches the base film so as not to cover the recording electrodes and supplies and holds ink containing toner particles by passing a gap between the recording electrodes from the front surface to the back surface of the base film. An electrostatic ink jet recording head comprising a cover and a lower cover. 2. The method according to claim 1, wherein when the ink containing the toner particles is supplied, an electrophoretic electrode is disposed at a position upstream of the recording electrode portion in the upper cover so as to be in contact with the ink. The electrostatic ink jet recording head according to claim 1. 3. When supplying the ink containing the toner particles, a position located upstream of the recording electrode unit in the upper cover and a position located downstream of the recording electrode unit in the lower cover are provided. 2. The electrostatic ink jet recording head according to claim 1, wherein a migration electrode is provided so as to be in contact with the ink, and the two migration electrodes are electrically connected. 4. The static electricity according to claim 1, wherein the upper cover and the lower cover are in close contact with the recording electrodes in the vicinity of the recording electrodes, and the ink flows between the plurality of recording electrodes. Electric inkjet recording head. 5. The recording medium according to claim 5, wherein a portion of the upper cover near the recording electrode is in close contact with the recording electrode, and a portion of the lower cover near the recording electrode is in close contact with the base film, and the ink flows between the plurality of recording electrodes. The electrostatic ink jet recording head according to claim 1, wherein 6. The recording medium according to claim 1, wherein the insulating base film and the recording electrodes are integrally formed on a two-layer or three-layer tape used in a TapeAutomated Bonding technique. 3. The electrostatic ink jet recording head according to 3.